TY - BOOK TI - QTL Cartographer: a reference manual and tutorial for QTL mapping AU - Basten, C.J. AU - Weir, B.S. AU - Zeng, Z.-B. DA - 1997/// PY - 1997/// PB - Department of Statistics, NC State University ER - TY - RPRT TI - Optimal Group Testing in the presence of Blockers AU - Langfeldt, S.A. AU - Hughes-Oliver, J.M. AU - Ghosh, S.K. AU - Young, S. A3 - North Carolina State University DA - 1997/// PY - 1997/// M1 - 2297 M3 - Institute of Statistics Mimeographs PB - North Carolina State University SN - 2297 ER - TY - SOUND TI - Latent Waiting Time Models For Bivariate Event Times With Censoring AU - Ghosh, S. DA - 1997/4// PY - 1997/4// ER - TY - RPRT TI - Bayesian Nonparametric Inference for Nonhomogeneous Poisson Processes AU - Kuo, L. AU - Ghosh, S.K. A3 - University of Connecticut DA - 1997/// PY - 1997/// M1 - 97-18 M3 - Technical Report PB - University of Connecticut SN - 97-18 ER - TY - CONF TI - Forecasting-based Operational Modeling and Simulation AU - Ghosh, S. T2 - SRC Workshop on Operational Methods in Semiconductor for Manufacturing C2 - 1997/2/19/ CY - Berkeley, California DA - 1997/2/19/ PY - 1997/2/19/ ER - TY - CONF TI - Proportional Hazards Models: A Latent Competing Risk Approach AU - Ghosh, S. T2 - VI Seminar on Applied Statistics: Statistics and Population C2 - 1997/6/4/ CY - San Jose, Costa Rica DA - 1997/6/4/ PY - 1997/6/4/ ER - TY - SOUND TI - Bayesian Analysis of Zero-inflated Regression Models AU - Ghosh, S. DA - 1997/4// PY - 1997/4// ER - TY - SOUND TI - Spatial Modeling: A Bayesian Approach AU - Ghosh, S. DA - 1997/10/3/ PY - 1997/10/3/ ER - TY - JOUR TI - Two-term Edgeworth expansion for M-estimators of a linear regression parameter without Cramér-type conditions and an application to the bootstrap AU - Karabulut, I. AU - Lahiri, S. N. T2 - Journal of the Australian Mathematical Society. Series A. Pure Mathematics and Statistics AB - Abstract A two-term Edgeworth expansion for the distribution of an M-estimator of a simple linear regression parameter is obtained without assuming any Cramér-type conditions. As an application, it is shown that certain modification of the naive bootstrap procedure is second order correct even when the error variables have a lattice distribution. This is in marked contrast with the results of Singh on the sample mean of independent and identically distributed random variables. DA - 1997/6// PY - 1997/6// DO - 10.1017/S1446788700001063 VL - 62 IS - 3 SP - 361-370 J2 - J Aust Math Soc A LA - en OP - SN - 0263-6115 UR - http://dx.doi.org/10.1017/S1446788700001063 DB - Crossref KW - bootstrap KW - Cramer's condition KW - edgeworth expansion KW - M-estimators KW - regression ER - TY - JOUR TI - Bootstrap-Adjusted Calibration Confidence Intervals for Immunoassay AU - Zeng, Qi AU - Davidian, Marie T2 - Journal of the American Statistical Association AB - Abstract In immunoassay, a nonlinear heteroscedastic regression model is used to characterize assay concentration-response, and the model fitted to data from standard samples is used to calibrate unknown test samples. Usual large-sample methods to construct individual confidence intervals for calibrated concentrations have been observed in empirical studies to be seriously inaccurate in terms of achieving the nominal level of coverage. We show theoretically that this inaccuracy is due largely to estimation of parameters characterizing assay response variance. By exploiting the theory, we propose a bootstrap procedure to adjust the usual intervals to achieve a higher degree of accuracy. We provide both theoretical results and simulation evidence to show that the proposed method attains the nominal level. A practical advantage of the procedure is that it may be implemented reliably using far fewer bootstrap samples than are needed in other resampling schemes. DA - 1997/3// PY - 1997/3// DO - 10.1080/01621459.1997.10473625 VL - 92 IS - 437 SP - 278-290 J2 - Journal of the American Statistical Association LA - en OP - SN - 0162-1459 1537-274X UR - http://dx.doi.org/10.1080/01621459.1997.10473625 DB - Crossref ER - TY - JOUR TI - Will the casual trend continue? Modeling of US men's apparel sales, 1990-96 AU - Suh, MW AU - Funderburk, RE T2 - JOURNAL OF THE TEXTILE INSTITUTE AB - Since the late 1980s the buzz-word in the men's apparel industry has been casual. Tailored suits and coats have been replaced in the office by jeans, slacks and sport shirts. The evolution of this trend by itself is fascinating, but perhaps most important is the future direction of the evolving phenomenon. This paper presents a statistical methodology based on the use of indicator variables and time trend to model and forecast sales of various men's apparel items in order to determine the future direction of the casual trend in the United States. DA - 1997/// PY - 1997/// DO - 10.1080/00405009708658573 VL - 88 IS - 1 SP - 82-97 SN - 0040-5000 ER - TY - JOUR TI - Catch rate estimation for roving and access point surveys AU - Pollock, K. H. AU - Hoenig, J. M. AU - Jones, C. M. AU - Robson, D. S. AU - Greene, C. J. T2 - North American Journal of Fisheries Management DA - 1997/// PY - 1997/// VL - 17 IS - 1 SP - 11 ER - TY - JOUR TI - Interpretation of "an average" in wetland hydrology analyses AU - Hunt, W. F. AU - Skaggs, R. W. T2 - Paper (American Society of Agricultural Engineers) DA - 1997/// PY - 1997/// IS - 972033 SP - 18 ER - TY - JOUR TI - The exact test for cytonuclear disequilibria AU - Basten, C. J. AU - Asmussen, M. A. T2 - Genetics DA - 1997/// PY - 1997/// VL - 146 IS - 3 SP - 1165-1171 ER - TY - JOUR TI - Analysis of environmental data with censored observations AU - Liu, SP AU - Lu, JC AU - Kolpin, DW AU - Meeker, WQ T2 - ENVIRONMENTAL SCIENCE & TECHNOLOGY AB - The potential threats to humans and to terrestrial and aquatic ecosystems from environmental contamination could depend on the sum of the concentrations of different chemicals. However, direct summation of environmental data is not generally feasible because it is common for some chemical concentrations to be recorded as being below the analytical reporting limit. This creates special problems in the analysis of the data. A new model selection procedure, named forward censored regression, is introduced for selecting an appropriate model for environmental data with censored observations. The procedure is demonstrated using concentrations of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), deethylatrazine (DEA, 2-amino-4-chloro-6-isopropylamino-s-triazine), and deisopropylatrazine (DIA, 2-amino-4-chloro-6-ethylamino-s-triazine) in groundwater in the midwestern United States by using the data derived from a previous study conducted by the U.S. Geological Survey. More than 80% of the observations for each compound for this study were left censored at 0.05 μg/L. The values for censored observations of atrazine, DEA, and DIA are imputed with the selected models. The summation of atrazine residue (atrazine + DEA + DIA) can then be calculated using the combination of observed and imputed values to generate a pseudo-complete data set. The all-subsets regression procedure is applied to the pseudo-complete data to select the final model for atrazine residue. The methodology presented can be used to analyze similar cases of environmental contamination involving censored data. DA - 1997/12// PY - 1997/12// DO - 10.1021/es960695x VL - 31 IS - 12 SP - 3358-3362 SN - 0013-936X ER - TY - CONF TI - Longitudinal study of alternative approaches to engineering education: survey of assessment results AU - Felder, R. M. AU - Felder, Gary N. AU - Dietz, E. J. AB - In the fall of 1990, the authors began a longitudinal study of a cohort of students enrolled in the introductory engineering course. These students were taught in a sequence of five engineering courses in five consecutive semesters, using a variety of instructional methods including extensive collaborative (team-based) learning, routine assignment of open-ended problems and problem formulation exercises, and other techniques designed to address the spectrum of learning styles found in all engineering classes. The students enrolled in the introductory course in the fall 1992 semester were designated as a comparison group. Academic performance and retention data were collected and attitudes and self-confidence levels were assessed for both groups throughout their second, third, and fourth years of college. This paper provides a mostly qualitative summary of the assessment data analyzed so far. C2 - 1997/// C3 - 1997 Frontiers in Education Conference Proceedings, ASEE/IEEE, November 1997 DA - 1997/// DO - 10.1109/fie.1997.632656 SP - 1284-1289 M1 - 1997 November PB - Washington, D.C.: American Society for Engineering Education ER - TY - JOUR TI - Knowledge-based vs. rule-based SPC AU - Quesenberry, C. P. T2 - Automotive Excellence DA - 1997/// PY - 1997/// VL - 3 IS - 3 ER - TY - JOUR TI - The cotton pickin' web: a new information source for cotton producers AU - Stinner, R. E. AU - Van Duyn, J. AU - O'Leary, P. T2 - Beltwide Cotton Conferences. Proceedings DA - 1997/// PY - 1997/// VL - 1 IS - 1997 SP - 72 ER - TY - JOUR TI - Spinning quality/process improvement through variance tolerancing AU - Suh, M. W. AU - Woo, J. L. AU - Koo, H. J. T2 - Beltwide Cotton Conferences. Proceedings DA - 1997/// PY - 1997/// VL - 1 IS - 1997 SP - 691-696 ER - TY - JOUR TI - Molecular genetics of growth and development in Populus (Salicaceae) .5. Mapping quantitative trait loci affecting leaf variation AU - Wu, R AU - Bradshaw, HD AU - Stettler, RF T2 - AMERICAN JOURNAL OF BOTANY AB - We examined the genetic variation of leaf morphology and development in the 2-yr-old replicated plantation of an interspecific hybrid pedigree of Populus trichocarpa T. & G. and P. deltoides Marsh. via both molecular and quantitative genetic methods. Leaf traits chosen were those that show pronounced differences between the original parents, including leaf size, shape, orientation, color, structure, petiole size, and petiole cross section. Leaves were sampled from the current terminal, proleptic, and sylleptic branches. In the F2 generation, leaf traits were all significantly different among genotypes, but with significant effects due to genotype X crown-position interaction. Variation in leaf pigmentation, petiole length. And petiole length proportion appeared to be under the control of few quantitative trait loci (QTLs). More QTLs were associated with single leaf area, leaf shape, lamina angle, abaxial color, and petiole flatness, and in these traits the number of QTLs varied among crown positions. In general, the estimates of QTL numbers from Wright's biometric method were close to those derived from molecular markers. For those traits with few underlying QTLs, a single marker interval could explain from 30 to 60% of the observed phenotypic variance. For multigenic traits, certain markers contributed more substantially to the observed variation than others. Genetic cluster analysis showed developmentally related traits to be more strongly associated with each other than with unrelated traits. This finding was also supported by the QTL mapping. For example, the same chromosomal segment of linkage group L seemed to account for 20% of the phenotypic variation of all dimension-related traits, leaf size, petiole length. and midrib angle. In both traits. the P. deltoides alleles had positive effects and were dominant to the P. trichocarpa alleles. Similar relationships were also found for lamina angle. abaxial greenness, and petiole. DA - 1997/2// PY - 1997/2// DO - 10.2307/2446076 VL - 84 IS - 2 SP - 143-153 SN - 1537-2197 KW - growth KW - leaf trait KW - linkage map KW - Populus KW - quantitative trait loci (QTL) mapping KW - Salicaceae ER - TY - JOUR TI - Sibship reconstruction without parental information AU - Painter, I. T2 - Journal of Agricultural, Biological, and Environmental Statistics DA - 1997/// PY - 1997/// VL - 2 IS - 2 SP - 212-229 ER - TY - JOUR TI - Limit theorems and a general framework for risk analysis in clonal forestry AU - Bishir, J AU - Roberds, J T2 - MATHEMATICAL BIOSCIENCES AB - Use of clonally propagated plantings in reforestation offers management advantages of phenotypic uniformity and high yields. Disadvantages include low genetic diversity and the possibility that the clone or clones chosen are particularly susceptible to attack by an insect or pathogen unforeseen as a problem at the time of clonal selection. In this paper, we continue consideration of the problem of choosing an optimal number of clones to minimize the risk of plantation failure. We present an analysis in which risk of failure for a plantation is represented by the probability that the proportion, S, of ramets that survive until harvest is less than or equal to a prescribed value. Our approach includes most earlier treatments as special cases. We show that the proportion S converges in distribution and, furthermore, that, under general conditions, a moderate number of clones, usually no more than 20 to 40 and often fewer, provides equivalent or better protection against catastrophic loss than does a large number of clones. DA - 1997/5// PY - 1997/5// DO - 10.1016/S0025-5564(96)00184-8 VL - 142 IS - 1 SP - 1-11 SN - 0025-5564 ER - TY - CHAP TI - You bet your life: Life-history strategies in fluctuating environments (1) AU - Ellner, S. P. T2 - Case studies in mathematical modeling: Ecology, physiology, and cell biology CN - QH541.15.M3 C37 1997 PY - 1997/// SP - 3-24 PB - Upper Saddle River, N.J.: Prentice Hall ER - TY - JOUR TI - Asymptotic inference for near unit roots in spatial autoregression AU - Bhattacharyya, B. B. AU - Richardson, G. D. AU - Franklin, L. A. T2 - Annals of Statistics AB - Asymptotic inference for estimators of $(\alpha_n, \beta_n)$ in the spatial autoregressive model $Z_{ij}(n) = \alpha_n Z_{i-1, j}(n) + \beta_n Z_{i, j-1}(n) - \alpha_n \beta_n Z_{i-1, j-1}(n) + \varepsilon_{ij}$ is obtained when $\alpha_n$ and $\beta_n$ are near unit roots. When $\alpha_n$ and $\beta_n$ are reparameterized by $\alpha_n = e^{c/n}$ and $\beta_n = e^{d/n}$, it is shown that if the "one-step Gauss-Newton estimator" of $\lambda_1 \alpha_n + \lambda_2 \beta_n$ is properly normalized and embedded in the function space $D([0, 1]^2)$, the limiting distribution is a Gaussian process. The key idea in the proof relies on a maximal inequality for a two-parameter martingale which may be of independent interest. A simulation study illustrates the speed of convergence and goodness-of-fit of these estimators for various sample sizes. DA - 1997/// PY - 1997/// DO - 10.1214/aos/1031594738 VL - 25 IS - 4 SP - 1709-1724 ER - TY - CONF TI - The impact of meteorology on ozone in Huston AU - Eder, B. K. AU - Davis, J. M. AU - Nychka, D. C2 - 1997/// C3 - EPA/A&WMA International Symposium on Measurement of Toxic and Related Air Pollutants (1992 May 4-9: Durham, N.C.) Measurement of toxic and related air pollutants: Proceedings of the 1992 EPA/A&WMA International Symposium CN - TD881 .E6 1992 DA - 1997/// SP - 204-214 PB - Pittsburgh, Pa.: A&WMA ER - TY - BOOK TI - Principles and procedures of statistics: A biometrical approach AU - Steel, R. G. D. AU - Torrie, J. H. AU - A., Dickey D. CN - QA276 .S82 1997 DA - 1997/// PY - 1997/// PB - New York: McGraw-Hill SN - 0070610282 ER - TY - JOUR TI - Effects of clover and small grain cover crops and tillage techniques on seedling emergence of dicotyledonous weed species AU - Blum, U. AU - King, L. D. AU - Gerig, T. M. AU - Lehman, M. E. AU - Worsham, A. D. T2 - American Journal of Alternative Agriculture AB - Abstract We monitored emergence of morning-glory, pigweed, and prickly sida from seeded populations in no-till plots with no debris (reference plots) or with crimson clover, subterranean clover, rye, or wheat debris. Cover crops were either desiccated by glyphosate or mowed and tilled into the soil. Debris levels, soil temperature, moisture, pH, nitrate, total phenolic acid and compaction were monitored during May to August in both 1992 and 1993. Seedling emergence for all three weed species ranged from <1 to 16% of seeds sown. Surface debris treatments delayed weed seedling emergence compared with the reference plots. Rye and wheat debris consistently suppressed weed emergence; in contrast, the effects of clover debris on weed emergence ranged from suppression to stimulation. Gfyphosate application resulted in a longer delay and greater suppression of seedling emergence in May than in April. In 1993, plots in which living biomass was tilled into the soil were also included and monitored. Weed seedling emergence was stimulated when living biomass was incorporated into the soil. Covariate, correlation and principle component analyses did not identify significant relationships between weed seedling emergence and soil physical and chemical characteristics (e.g., total phenolic acid, nitrate, moisture, temperature). We hypothesize that the observed initial delay of the weed seedling emergence for all three species was likely due to low initial soil moisture. The subsequent rapid recovery of seedling emergence of morning-glory and pigweed but notprickfy sida in the clover compared with the small grain debris plots was likely due to variation in soil allelopathic agents or nitrate-N levels. The stimulation of weed seedling emergence when living biomass was incorporated into the soil was likely caused by an increase in “safe” germination sites coupled with the absence of a zone of inhibition resulting from tillage. DA - 1997/// PY - 1997/// DO - 10.1017/s0889189300007487 VL - 12 IS - 4 SP - 146-161 ER - TY - CHAP TI - Testing spatial autocorrelation for binary or categorical response variables AU - Gumpertz, M. L. T2 - Exercises in plant disease epidemiology A2 - L. J. Francl, A2 - Neher, D. A. CN - SB732.56 .E94 1997 PY - 1997/// SP - 78-84 PB - St. Paul, Minn.: APS Press ER - TY - CHAP TI - Spatial autocorrelation: Methods for continuous variables AU - Gumpertz, M. L. AU - Ristaino, J. B. T2 - Exercises in plant disease epidemiology A2 - L. J. Francl, A2 - Neher, D. A. CN - SB732.56 .E94 1997 PY - 1997/// SP - 72-77 PB - St. Paul, Minn.: APS Press ER - TY - CHAP TI - Likelihood ratio tests and intersection-union tests AU - Berger, R. L. T2 - Advances in statistical decision theory and applications A2 - S. Panchapakesan, A2 - Balakrishnan, N. CN - QA279.4 .A38 1997 PY - 1997/// SP - 225-237 PB - Boston: Birkhauser ER - TY - JOUR TI - Statistical issues in the search for genes? AU - Doerge, R. W. AU - Zeng, Z. B. AU - Weir, B. S. T2 - Statistical Science DA - 1997/// PY - 1997/// VL - 12 IS - 1997 SP - 195-219 ER - TY - JOUR TI - Measuring the effect of observations using the posterior and intrinsic bayes factors with vague prior information AU - Dey, D. K. AU - Ghosh, S. K. AU - Chang, H. T2 - Sankhya. Series A DA - 1997/// PY - 1997/// VL - 59 IS - 1997 SP - 376-391 ER - TY - JOUR TI - Identification of hysteretic control influence operators representing smart actuators part I: Formulation AU - Banks, HT AU - Kurdila, AJ AU - Webb, G T2 - MATHEMATICAL PROBLEMS IN ENGINEERING AB - A large class of emerging actuation devices and materials exhibit strong hysteresis characteristics during their routine operation. For example, when piezoceramic actuators are operated under the influence of strong electric fields, it is known that the resulting input–output behavior is hysteretic. Likewise, when shape memory alloys are resistively heated to induce phase transformations, the input–output response at the structural level is also known to be strongly hysteretic. This paper investigates the mathematical issues that arise in identifying a class of hysteresis operators that have been employed for modeling both piezoceramic actuation and shape memory alloy actuation. Specifically, the identification of a class of distributed hysteresis operators that arise in the control influence operator of a class of second order evolution equations is investigated. In Part I of this paper we introduce distributed,hysteretic control influence operators derived from smoothed Preisach operators and generalized hysteresis operators derived from results of Krasnoselskii and Pokrovskii. For these classes, the identification problem in which we seek to characterize the hysteretic control influence operator can be expressed as an ouput least square minimization over probability measures defined on a compact subset of a closed half-plane. In Part II of this paper, consistent and convergent approximation methods for identification of the measure characterizing the hysteresis are derived. DA - 1997/// PY - 1997/// DO - 10.1155/S1024123X97000586 VL - 3 IS - 4 SP - 287-328 SN - 1024-123X KW - hysteretic Preisach operators KW - smart materials KW - evolution equations KW - identification ER - TY - CHAP TI - Visualizing spatial patterns AU - Gumpertz, M. L. T2 - Exercises in plant disease epidemiology A2 - L. J. Francl, A2 - Neher, D. A. CN - SB732.56 .E94 1997 PY - 1997/// SP - 59-63 PB - St. Paul, Minn.: APS Press ER - TY - JOUR TI - Autologistic model of spatial pattern of Phytophythora epidemic in bell pepper: effects of soil variables on disease presence AU - Gumpertz, M. L. AU - Graham, J. M. AU - Ristaino, J. B. T2 - Journal of Agricultural, Biological, and Environmental Statistics DA - 1997/// PY - 1997/// VL - 2 IS - 2 SP - 131-156 ER - TY - JOUR TI - Quantitative genetic analysis of divergence in male secondary sexual traits between Drosophila simulans and Drosophila mauritiana AU - True, , JR AU - Liu, JJ AU - Stam, LF AU - Zeng, ZB AU - Laurie, CC T2 - EVOLUTION DA - 1997/6// PY - 1997/6// DO - 10.2307/2411157 VL - 51 IS - 3 SP - 816-832 SN - 0014-3820 KW - genitalia KW - interspecific divergence KW - morphological evolution KW - quantitative trait loci mapping KW - sexual dimorphism ER - TY - JOUR TI - Immunochemical identification of AFLR, a regulatory protein, involved in aflatoxin biosynthesis AU - Liu, BH AU - Brewer, JF AU - Flaherty, JE AU - Payne, G AU - Bhatnagar, D AU - Chu, FS T2 - FOOD AND AGRICULTURAL IMMUNOLOGY AB - Polyclonal antibodies against AFLR, the aflR gene product of Aspergillus flavus and A. parasiticus, were generated by immunizing a rabbit with the Escherichia coli‐expressed recombinant AFLR protein of A. flavus. Immunoblot analysis revealed that the antibodies not only reacted with the recombinant AFLR protein of A. flavus or A. parasiticus but also with native 47‐kDa AFLR in A. flavus and A. parasiticus. Immunoblot analysis revealed that accumulation of the 47‐kDa AFLR in cultures of A. flavus and A. parasiticus correlated well with the production of aflatoxin under various culture conditions that regulate aflatoxin formation. Neither AFLR nor aflatoxin was found when A. parasiticus NRRL 2999 was grown in peptone mineral salts (PMS) medium; however, both were detected after the culture was transferred to glucose mineral salts (GMS) medium. The AFLR protein was absent in the non‐aflatoxigenic Penicillium and Fusarium species grown in GMS medium. The data indicate that the antibodies obtained in the present studies are specific for AFLR and could be used in various studies to monitor the role of AFLR in regulating aflatoxin biosynthesis. DA - 1997/12// PY - 1997/12// DO - 10.1080/09540109709354959 VL - 9 IS - 4 SP - 289-298 SN - 1465-3443 KW - aflatoxin KW - AFLR KW - antibodies KW - regulation KW - A-flavus KW - A-parasiticus ER - TY - CHAP TI - Geostatistical applications in epidemiology AU - Gumpertz, M. L. AU - Larkin, R. P. AU - Ristaino, J. B. T2 - Exercises in plant disease epidemiology A2 - L. J. Francl, A2 - Neher, D. A. CN - SB732.56 .E94 1997 PY - 1997/// SP - 94-99 PB - St. Paul, Minn.: APS Press ER - TY - JOUR TI - Bayesian analysis of DNA profiling data in forensic identification applications: discussion AU - Weir, B. S. AU - Painter, I. S. T2 - Journal of the Royal Statistical Society. Series A, General DA - 1997/// PY - 1997/// VL - 160 (part3) IS - 1997 SP - 465-466 ER - TY - JOUR TI - Size- and species dependent variability in consumption and growth rates of larvae and juveniles of three freshwater fishes AU - Letcher, BH AU - Rice, JA AU - Crowder, LB AU - Binkowski, FP T2 - CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES DA - 1997/2// PY - 1997/2// DO - 10.1139/cjfas-54-2-405 VL - 54 IS - 2 SP - 405-414 SN - 0706-652X ER - TY - JOUR TI - Sex-specific quantitative trait loci affecting longevity in Drosophila melanogaster AU - Nuzhdin, SV AU - Pasyukova, EG AU - Dilda, CL AU - Zeng, ZB AU - Mackay, TFC T2 - PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA AB - Senescence, the decline in survivorship and fertility with increasing age, is a near-universal property of organisms. Senescence and limited lifespan are thought to arise because weak natural selection late in life allows the accumulation of mutations with deleterious late-age effects that are either neutral (the mutation accumulation hypothesis) or beneficial (the antagonistic pleiotropy hypothesis) early in life. Analyses of Drosophila spontaneous mutations, patterns of segregating variation and covariation, and lines selected for late-age fertility have implicated both classes of mutation in the evolution of aging, but neither their relative contributions nor the properties of individual loci that cause aging in nature are known. To begin to dissect the multiple genetic causes of quantitative variation in lifespan, we have conducted a genome-wide screen for quantitative trait loci (QTLs) affecting lifespan that segregate among a panel of recombinant inbred lines using a dense molecular marker map. Five autosomal QTLs were mapped by composite interval mapping and by sequential multiple marker analysis. The QTLs had large sex-specific effects on lifespan and age-specific effects on survivorship and mortality and mapped to the same regions as candidate genes with fertility, cellular aging, stress resistance and male-specific effects. Late age-of-onset QTL effects are consistent with the mutation accumulation hypothesis for the evolution of senescence, and sex-specific QTL effects suggest a novel mechanism for maintaining genetic variation for lifespan. DA - 1997/9/2/ PY - 1997/9/2/ DO - 10.1073/pnas.94.18.9734 VL - 94 IS - 18 SP - 9734-9739 SN - 0027-8424 ER - TY - CHAP TI - Predation on juvenile fishes: Dynamic interactions between size-structured predators and prey AU - Rice, J. A. AU - Crowder, L. B. AU - Marschall, E. A. T2 - Early life history and recruitment in fish populations (Fish and Fisheries series #21) A2 - R. C. Chambers, A2 - Trippel, E. A. CN - QL639.25 .E318 1997 PY - 1997/// VL - 21 SP - 333-356 PB - London: Chapman & Hall ER - TY - JOUR TI - Nonadditive effects of terrestrial and aquatic predators on juvenile estuarine fish AU - Crowder, L. B. AU - Squires, D. D. AU - Rice, J. A. T2 - Ecology (Brooklyn, New York, N.Y.) AB - Small fish frequently avoid large fish predators by moving into shallow refuges, but this can increase encounters with terrestrial piscivores. In previous experiments, we documented that juvenile spot (Leiostomus xanthurus) respond to southern flounder (Paralichthys lethostigma) by moving into shallow water. This might increase their risk of predation by birds. We conducted a pond-scale field experiment to test the hypothesis that predation by birds and flounder will have nonadditive effects on spot survival and size. We expected spot to have lower survival in the presence of both predators than expected based on their additive effects (i.e., facilitation among predators). The experiment was a 2 × 2 factorial with and without flounders and bird access. Flounder significantly reduced spot survival while birds did not, but there was a significant interaction effect. Spot survived better with both predators than expected based on adding separate predator effects. Mean spot growth rate was unaffected by treatment. Spot moved to shallow water in the presence of flounder and aggregated more tightly in the presence of birds. The observed nonadditive effects could have been due to interference between flounder and birds. However, because all the flounder in our experiments survived and their growth was unaffected by birds, we favor the idea that behavioral changes (increased aggregation) by spot to avoid bird predation also further reduced their vulnerability to flounder. Our results suggest that modeling the effects of multiple predators will be more complicated than simply adding up the effects observed in experiments with single predators. DA - 1997/// PY - 1997/// DO - 10.1890/0012-9658(1997)078[1796:neotaa]2.0.co;2 VL - 78 IS - 6 SP - 1796-1804 ER - TY - JOUR TI - Cycle time and residence time density approximations in a stochastic model for circulatory transport AU - Smith, C. E. AU - Lansky, P. AU - Lung, T.-H. T2 - Bulletin of Mathematical Biology AB - The concentration of a drug in the circulatory system is studied under two different elimination strategies. The first strategy—geometric elimination—is the classical one which assumes a constant elimination rate per cycle. The second strategy—Poisson elimination—assumes that the elimination rate changes during the process of elimination. The problem studied here is to find a relationship between the residence-time distribution and the cycle-time distribution for a given rule of elimination. While the presented model gives this relationship in terms of Laplace-Stieltjes transform, the aim here is to determine the shapes of the corresponding probability density functions. From experimental data, we expect positively skewed, gamma-like distributions for the residence time of the drug in the body. Also, as some elimination parameter in the model approaches a limit, the exponential distribution often arises. Therefore, we use laguerre series expansions, which yield a parsimonious approximation of positively skewed probability densities that are close to a gamma distribution. The coefficients in the expansion are determined by the central moments, which can be obtained from experimental data or as a consequence of theoretical assumptions. The examples presented show that gamma-like densities arise for a diverse set of cycle-time distributions and under both elimination rules. DA - 1997/// PY - 1997/// DO - 10.1007/bf02459468 VL - 59 IS - 1 SP - 1-22 ER - TY - JOUR TI - Application of recurrent selection for low grain moisture content at harvest in tropical maize AU - Hawbaker, MS AU - Hill, WS AU - Goodman, MM T2 - CROP SCIENCE AB - Late maturity and high grain moisture content at harvest have been major limitations to the use of tropical maize ( Zea mays L.) germplasm in temperate regions. The objective of this study was to determine if selection for reduced grain moisture content at harvest in a tropical maize population indirectly influenced grain yield potential. Two hundred sixteen temperately‐adapted S 4 lines were derived in 1991 at Raleigh, NC, from Cycle 9 of recurrent phenotypic selection for reduced grain moisture at harvest in the tropical maize population TROPHY, and these were testcrossed in 1992 at Raleigh, NC, to the temperate hybrid B73 Ht × Mo17 Ht . Selected subsets of these testcrosses were evaluated for their agronomic potential in seven environments over two years, and their performance was compared with that of Cycle 0 S 0 testcrosses as well as three public and three commercial F 1 hybrids. Selected Cycle 9 S 4 testcrosses had higher mean grain yield (7.14 Mg ha ‒1 ) and lower mean grain moisture at harvest (184 g kg −1 ) than the Cycle 0 So testcrosses (6.77 Mg ha −1 , and 189 g kg −1 respectively). The highest yielding Cycle 9 S 4 testcrosses were comparable to the commercial hybrid LH132 × LH51. This study supported the conclusion that ergonomically competitive inbred lines with acceptable grain moisture content at harvest can be derived from 100% tropical germplasm. DA - 1997/// PY - 1997/// DO - 10.2135/cropsci1997.0011183X003700050040x VL - 37 IS - 5 SP - 1650-1655 SN - 0011-183X ER - TY - JOUR TI - A Markov chain model of coalescence with recombination AU - Simonsen, KL AU - Churchill, GA T2 - THEORETICAL POPULATION BIOLOGY AB - Trees that describe the ancestry of DNA sequences sampled from a population may differ between loci because of genetic recombination. We seek to understand the relationship between such trees for loci that are linked with non-zero recombination rate. We consider a coalescent process model with recombination, as described by Hudson (1983; 1990). For two loci and a sample size of two sequences, a detailed analysis of this process yields the joint distribution of the two trees (one at each locus). A number of interesting results follow from this analysis, including the distribution of the number of recombination events in the history of the sample. For the general case ofmloci and samples of sizen, we describe an algorithm for simulating the tree building process. Because analytic results are difficult to obtain in this case, we use simulation to study properties of trees at multiple linked loci such as total tree time and number of recombination events. DA - 1997/8// PY - 1997/8// DO - 10.1006/tpbi.1997.1307 VL - 52 IS - 1 SP - 43-59 SN - 0040-5809 ER - TY - JOUR TI - Semiparametric efficiency and its implication on the design and analysis of group-sequential studies AU - Scharfstein, DO AU - Tsiatis, AA AU - Robins, JM T2 - JOURNAL OF THE AMERICAN STATISTICAL ASSOCIATION AB - Abstract Authors have shown that the time-sequential joint distributions of many statistics used to analyze data arising from group-sequential time-to-event and longitudinal studies are multivariate normal with an independent increments covariance structure. In Theorem 1 of this article, we demonstrate that this limiting distribution arises naturally when one uses an efficient test statistic to test a single parameter in a semiparametric or parametric model. Because we are able to think of many of the statistics in the literature in this fashion, the limiting distribution under investigation is just a special case of Theorem 1. Using this general structure, we then develop an information-based design and monitoring procedure that can be applied to any type of model for any type of group-sequential study provided that there is a unique parameter of interest that can be efficiently tested. DA - 1997/12// PY - 1997/12// DO - 10.2307/2965404 VL - 92 IS - 440 SP - 1342-1350 SN - 0162-1459 KW - independent increment KW - information-based design and monitoring KW - longitudinal study KW - maximum information trial KW - time-to-event study ER - TY - JOUR TI - SASGENE: A SAS computer program for genetic analysis of gene segregation and linkage AU - Liu, JS AU - Wehner, TC AU - Donaghy, SB T2 - JOURNAL OF HEREDITY DA - 1997/// PY - 1997/// DO - 10.1093/oxfordjournals.jhered.a023099 VL - 88 IS - 3 SP - 253-254 SN - 0022-1503 ER - TY - JOUR TI - Period-doubling bifurcations for systems of difference equations and applications to models in population biology AU - Selgrade, JF AU - Roberds, JH T2 - NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS DA - 1997/7// PY - 1997/7// DO - 10.1016/S0362-546X(96)00041-7 VL - 29 IS - 2 SP - 185-199 SN - 1873-5215 KW - discrete models KW - period-doubling bifurcation KW - Henon map KW - population genetics KW - pioneer and climax populations ER - TY - JOUR TI - Modeling aggregation and growth processes in an algal population model: Analysis and computations AU - Ackleh, AS AU - Fitzpatrick, BG T2 - JOURNAL OF MATHEMATICAL BIOLOGY AB - Aggregation, the formation of large particles through multiple collision of smaller ones is a highly visible phenomena in oceanic waters which can control material flux to the deep sea. Oceanic aggregates more than 1 cm in diameter have been observed and are frequently described to consist of phytoplankton cells as well as other organic matter such as fecel pellets and mucus nets from pteropods. Division of live phytoplankton cells within an aggregate can also increase the size of aggregate (assuming some daughter cells stay in the aggregate) and hence could be a significant factor in speeding up the formation process of larger aggregate. Due to the difficulty of modeling cell division within aggregates, few efforts have been made in this direction. In this paper, we propose a size structured approach that includes growth of aggregate size due to both cell division and aggregation. We first examine some basic mathematical issues associated with the development of a numerical simulation of the resulting algal aggregation model. The numerical algorithm is then used to examine the basic model behavior and present a comparison between aggregate distribution with and without division in aggregates. Results indicate that the inclusion of a growth term in aggregates, due to cell division, results in higher densities of larger aggregates; hence it has the impact to speed clearance of organic matter from the surface layer of the ocean. DA - 1997/3// PY - 1997/3// DO - 10.1007/s002850050062 VL - 35 IS - 4 SP - 480-502 SN - 0303-6812 KW - phytoplankton aggregation KW - size structure population model KW - numerical approximation ER - TY - JOUR TI - General formulas for obtaining the MLEs and the asymptotic variance-covariance matrix in mapping quantitative trait loci when using the EM algorithm AU - Kao, CH AU - Zeng, ZB T2 - BIOMETRICS AB - We present in this paper general formulas for deriving the maximum likelihood estimates and the asymptotic variance-covariance matrix of the positions and effects of quantitative trait loci (QTLs) in a finite normal mixture model when the EM algorithm is used for mapping QTLs. The general formulas are based on two matrices D and Q, where D is the genetic design matrix, characterizing the genetic effects of the QTLs, and Q is the conditional probability matrix of QTL genotypes given flanking marker genotypes, containing the information on QTL positions. With the general formulas, it is relatively easy to extend QTL mapping analysis to using multiple marker intervals simultaneously for mapping multiple QTLs, for analyzing QTL epistasis, and for estimating the heritability of quantitative traits. Simulations were performed to evaluate the performance of the estimates of the asymptotic variances of QTL positions and effects. DA - 1997/6// PY - 1997/6// DO - 10.2307/2533965 VL - 53 IS - 2 SP - 653-665 SN - 0006-341X KW - asymptotic variance-covariance matrix KW - EM algorithm KW - epistasis KW - gene mapping KW - general formulas KW - heritability KW - maximum likelihood KW - normal mixture model KW - quantitative trait loci ER - TY - JOUR TI - Combining information from data in mapping analysis: use of multiple markers and multiple traits AU - Zeng, Z. B. T2 - Animal Biotechnology DA - 1997/// PY - 1997/// DO - 10.1080/10495399709525876 VL - 8 IS - 1 SP - 145-150 ER - TY - JOUR TI - Catch-effort maximum likelihood estimation of important population parameters AU - Gould, WR AU - Pollock, KH T2 - CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES DA - 1997/4// PY - 1997/4// DO - 10.1139/cjfas-54-4-890 VL - 54 IS - 4 SP - 890-897 SN - 1205-7533 ER - TY - JOUR TI - Benzene-induced hematotoxicity and bone marrow compensation in B6C3F1 mice AU - Farris, GM AU - Robinson, SN AU - Gaido, KW AU - Wong, BA AU - Wong, VA AU - Hahn, WP AU - Shah, RS T2 - FUNDAMENTAL AND APPLIED TOXICOLOGY AB - Long-term inhalation exposure of benzene has been shown to cause hematotoxicity and an increased incidence of acute myelogenous leukemia in humans. The progression of benzene-induced hematotoxicity and the features of the toxicity that may play a major role in the leukemogenesis are not known. We report the hematological consequences of benzene inhalation in B6C3F1 mice exposed to 1, 5, 10, 100, and 200 ppm benzene for 6 hr/day, 5 days/week for 1, 2, 4, or 8 weeks and a recovery group. There were no significant effects on hematopoietic parameters from exposure to 10 ppm benzene or less. Exposure of mice to 100 and 200 ppm benzene reduced the number of total bone marrow cells, progenitor cells, differentiating hematopoietic cells, and most blood parameters. Replication of primitive progenitor cells in the bone marrow was increased during the exposure period as a compensation for the cytotoxicity induced by 100 and 200 ppm benzene. In mice exposed to 200 ppm benzene, the primitive progenitor cells maintained an increased percentage of cells in S-phase through 25 days of recovery compared with controls. The increased replication of primitive progenitor cells in concert with the reported genotoxicity induced by benzene provides the components necessary for producing an increased incidence of lymphoma in mice. Furthermore, we propose this mode of action as a biologically plausible mechanism for benzene-induced leukemia in humans exposed to high concentrations of benzene. DA - 1997/4// PY - 1997/4// DO - 10.1006/faat.1997.2293 VL - 36 IS - 2 SP - 119-129 SN - 0272-0590 ER - TY - JOUR TI - Altering developmental trajectories in mice by restricted index selection AU - Atchley, W. R. AU - Xu, S. AU - Cowley, D. E. T2 - Genetics DA - 1997/// PY - 1997/// VL - 146 IS - 2 SP - 629-640 ER - TY - JOUR TI - A natural classification of the basic helix-loop-helix class of transcription factors AU - Atchley, WR AU - Fitch, WM T2 - PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA AB - A natural (evolutionary) classification is provided for 242 basic helix–loop–helix (bHLH) motif-containing proteins. Phylogenetic analyses of amino acid sequences describe the patterns of evolutionary change within the motif and delimit evolutionary lineages. These evolutionary lineages represent well known functional groups of proteins and can be further arranged into five groups based on binding to DNA at the hexanucleotide E-box, the amino acid patterns in other components of the motif, and the presence/absence of a leucine zipper. The hypothesized ancestral amino acid sequence for the bHLH transcription factor family is given together with the ancestral sequences of the subgroups. It is suggested that bHLH proteins containing a leucine zipper are not a natural, monophyletic group. DA - 1997/5/13/ PY - 1997/5/13/ DO - 10.1073/pnas.94.10.5172 VL - 94 IS - 10 SP - 5172-5176 SN - 0027-8424 ER - TY - JOUR TI - The occurrence and significance of epistatic variance for quantitative characters and its measurement in haploids AU - Shaw, AJ AU - Weir, BS AU - Shaw, FH T2 - EVOLUTION AB - Epistatic genetic variance for quantitative traits may play an important role in evolution, but detecting epistasis in diploid organisms is difficult and requires complex breeding programs and very large sample sizes. We develop a model for detecting epistasis in organisms with a free-living haploid stage in their life cycles. We show that epistasis is indicated by greater variance among families of haploid progeny derived from individual diploids than among clonally replicated haploid sibs from the same sporophyte. Simulations show that the power to detect epistasis is linearly related to the number of sporophytes and the number of haploids per sporophyte in the dataset. We illustrate the model with data from growth variation among gametophytes of the moss, Ceratodon purpureus. The experiment failed to detect epistatic variance for biomass production, although there was evidence of additive variance. DA - 1997/4// PY - 1997/4// DO - 10.1111/j.1558-5646.1997.tb02421.x VL - 51 IS - 2 SP - 348-353 SN - 1558-5646 KW - epistasis KW - gene interactions KW - haploids KW - mosses KW - quantitative genetics KW - sib analysis KW - variance components ER - TY - JOUR TI - Severe thunderstorm and tornado warnings at Raleigh, North Carolina AU - Hoium, DK AU - Riordan, AJ AU - Monahan, J AU - Keeter, KK T2 - BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY AB - The National Weather Service issues public warnings for severe thunderstorms and tornadoes when these storms appear imminent. A study of the warning process was conducted at the National Weather Service Forecast Office at Raleigh, North Carolina, from 1994 through 1996. The purpose of the study was to examine the decision process by documenting the types of information leading to decisions to warn or not to warn and by describing the sequence and timing of events in the development of warnings. It was found that the evolution of warnings followed a logical sequence beginning with storm monitoring and proceeding with increasingly focused activity. For simplicity, information input to the process was categorized as one of three types: ground truth, radar reflectivity, or radar velocity. Reflectivity, velocity, and ground truth were all equally likely to initiate the investigation process. This investigation took an average of 7 min, after which either a decision was made not to warn or new information triggered the warning. Decisions not to issue warnings were based more on ground truth and reflectivity than radar velocity products. Warnings with investigations of more than 2 min were more likely to be triggered by radar reflectivity, than by velocity or ground truth. Warnings with a shorter investigation time, defined here as “immediate trigger warnings,” were less frequently based on velocity products and more on ground truth information. Once the decision was made to warn, it took an average of 2.1 min to prepare the warning text. In 85% of cases when warnings were issued, at least one contact was made to emergency management officials or storm spotters in the warned county. Reports of severe weather were usually received soon after the warning was transmitted—almost half of these within 30 min after issue. A total of 68% were received during the severe weather episode, but some of these storm reports later proved false according to Storm Data. Even though the WSR-88D is a sophisticated tool, ground truth information was found to be a vital part of the warning process. However, the data did not indicate that population density was statistically correlated either with the number of warnings issued or the verification rate. DA - 1997/11// PY - 1997/11// DO - 10.1175/1520-0477(1997)078<2559:STATWA>2.0.CO;2 VL - 78 IS - 11 SP - 2559-2575 SN - 0003-0007 ER - TY - JOUR TI - Numerical simulations of a gravity wave event over CCOPE .1. The role of geostrophic adjustment in mesoscale jetlet formation AU - Kaplan, ML AU - Koch, SE AU - Lin, YL AU - Weglarz, RP AU - Rozumalski, RA T2 - MONTHLY WEATHER REVIEW AB - Mesoscale model simulations are performed in order to provide insight into the complex role of jet streak adjustments in establishing an environment favorable to the generation of gravity waves on 11–12 July 1981. This wave event was observed in unprecedented detail downstream of the Rocky Mountains in Montana during the Cooperative Convective Precipitation Experiment. The high-resolution model simulations employ a variety of terrain treatments in the absence of the complicating effects of precipitation physics in order to examine the complex interactions between orography and adiabatic geostrophic adjustment processes. Results indicate that prior to gravity wave formation, a four-stage geostrophic adjustment process modified the structure of the mid- to upper-tropospheric jet streak by creating secondary mesoscale jet streaks (jetlets) to the southeast of the polar jet streak in proximity to the gravity wave generation region (WGR). During stage I, a strong rightward-directed ageostrophic flow in the right exit region of the polar jet streak (J1) developed over west-central Montana. This thermally indirect transverse secondary circulation resulted from inertial-advective adjustments wherein momentum was transported downstream and to the right of J1 as air parcels decelerated through the exit region. During stage II, a highly unbalanced jetlet (J2) formed just northwest of the WGR in response to the inertial-advective forcing accompanying the ageostrophic circulation associated with J1. The mass field adjusted to this ageostrophic wind field. An adiabatic cooling and warming dipole resulting from this thermally indirect secondary circulation was the cause for frontogenesis and a rightward shift in the midtropospheric pressure gradients. Since this secondary circulation associated with J2 occurred above a dramatic vertical variation in the thermal wind, the vertical transport of potentially colder air from below was larger ahead of and to the right of J1, thus shifting the new jetlet (J2) well away from J1 as the mass field adjusted to the new wind field. Stage III was established when the new mass field, which developed in association with J2 during stage II, set up a dynamically unbalanced circulation oriented primarily across the stream, and directly over the WGR. This new leftward-directed ageostrophic cross-stream flow (A) formed between jetlet J2 and the original exit region of the polar jet streak J1. Finally, a midlevel mesoscale jetlet (J3) is simulated to have developed in stage IV over the WGR in response to the integrated mass flux divergence associated with both the stage II and III adjustment processes. This lower-level return branch circulation to jetlet J2 was further enhanced by velocity divergence accompanying the localized cross-stream ageostrophic wind maximum (A), which develops during stage III. The entire multistage geostrophic adjustment process required about 12 h to complete over a region encompassing approximately 400 km × 400 km. DA - 1997/6// PY - 1997/6// DO - 10.1175/1520-0493(1997)125<1185:NSOAGW>2.0.CO;2 VL - 125 IS - 6 SP - 1185-1211 SN - 1520-0493 ER - TY - JOUR TI - Inferring mechanism from time-series data: Delay-differential equations AU - Ellner, S. P. AU - Kendall, B. E. AU - Wood, S. N. AU - McCauley, E. AU - Briggs, C. J. T2 - Physica. D, Nonlinear Phenomena DA - 1997/// PY - 1997/// VL - 110 IS - 3-4 SP - 182-194 ER - TY - JOUR TI - Identification of hysteretic control influence operators representing smart actuators, Part II: Convergent approximations AU - Banks, HT AU - Kurdila, AJ AU - Webb, G T2 - JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES AB - In a previous paper, the authors investigated the lower semicontinuity properties of two generalizations of the classical Preisach operator: the smoothed Preisach operator and the Krasnoselskii/Pokrovskii (KP) integral hysteresis operators. In particular, it was demonstrated that the output least squares identification problem for the KP operator is well-posed over compact subsets of the Preisach plane. The identification of the hysteretic control influence operator was shown to be equivalent to the identification of a measure in the space of probability measures taken with the weak* topology. In this paper, a consistent and convergent approximation scheme is introduced for this class of integral hysteresis operator. The Galerkin approximation scheme is shown to be function space parameter convergent. A numerical example is presented that illustrates aspects of the theory derived in this paper. DA - 1997/6// PY - 1997/6// DO - 10.1177/1045389X9700800606 VL - 8 IS - 6 SP - 536-550 SN - 1045-389X ER - TY - JOUR TI - Heterosis and genotype x environment interactions of juvenile aspens in two contrasting sites AU - Li, B.-L. AU - Wu, R.-L. T2 - Canadian Journal of Forest Research DA - 1997/// PY - 1997/// DO - 10.1139/97-110 VL - 27 IS - 10 SP - 1525-1537 ER - TY - JOUR TI - A two-step approach to measurement error in time-dependent covariates in nonlinear mixed-effects models, with application to IGF-I pharmacokinetics AU - Higgins, K. M. AU - Davidian, Marie AU - Giltinan, D. M. T2 - Journal of the American Statistical Association AB - Abstract The usual approach to the analysis of population pharmacokinetic studies is to represent the concentration-time data by a nonlinear mixed-effects model. Primary objectives are to characterize the pattern of drug disposition in the population and to identify individual-specific covariates associated with pharmacokinetic behavior. We consider data from a study of insulin-like growth factor I (IGF-I) administered by intravenous infusion to patients with severe head trauma. Failure to maintain steady-state levels of IGF-I was thought to be related to the temporal pattern of several covariates measured in the study, and an analysis investigating this issue was of interest. Observations on these potentially relevant covariates for each subject were made at time points different from those at which IGF-I concentrations were determined; moreover, the covariates themselves were likely subject to measurement error. The usual approach to time-dependent covariates in population analysis is to invoke a simple interpolation scheme, such as carrying forward the most recent covariate value, ignoring measurement error; however, for these data, the complicated observed covariate pattern makes this approach suspect. A nonlinear mixed-effects model incorporating a model for time-dependent covariates measured with error is used to describe the IGF-I data, and fitting is accomplished by a two-step strategy implemented using standard software. The performance of the method is evaluated via simulation. DA - 1997/// PY - 1997/// DO - 10.1080/01621459.1997.10473995 VL - 92 IS - 438 SP - 436–448 ER - TY - JOUR TI - Statistical inference of a time-to-failure distribution derived from linear degradation data AU - Lu, JC AU - Park, J AU - Yang, Q T2 - TECHNOMETRICS AB - Abstract In the study of semiconductor degradation, records of transconductance loss or threshold voltage shift over time are useful in constructing the cumulative distribution function (cdf) of the time until the degradation reaches a specified level. In this article, we propose a model with random regression coefficients and a standard-deviation function for analyzing linear degradation data. Both analytical and empirical motivations of the model are provided. We estimate the model parameters, the cdf, and its quantiles by the maximum likelihood (ML) method and construct confidence intervals from the bootstrap, from the asymptotic normal approximation, and from inverting likelihood ratio tests. Simulations are conducted to examine the properties of the ML estimates and the confidence intervals. Analysis of an engineering dataset illustrates the proposed procedures. KEY WORDS: Bootstrap confidence intervalLikelihood ratio testRandom coefficientsReliabilityStandard-deviation function DA - 1997/11// PY - 1997/11// DO - 10.2307/1271503 VL - 39 IS - 4 SP - 391-400 SN - 0040-1706 KW - bootstrap confidence interval KW - likelihood ratio test KW - random coefficients KW - reliability KW - standard-deviation function ER - TY - JOUR TI - Power studies for the transmission/disequilibrium tests with multiple alleles AU - Kaplan, N. L. AU - Martin, E. R. AU - Weir, B. S. T2 - American Journal of Human Genetics DA - 1997/// PY - 1997/// VL - 60 IS - 1997 SP - 691-702 ER - TY - JOUR TI - Modeling of nonsymmetrical damage in plate-like structures AU - Banks, HT AU - Emeric, P AU - Plancke, L T2 - MATHEMATICAL AND COMPUTER MODELLING AB - A two-dimensional model for in-plane vibrations of a damped linear elastic Hookean partially clamped plate-like structure with a nonsymmetrical damage is proposed. The model includes both active and passive contributions of piezoelectric ceramic patches bonded to the surface of the structure. Both strong and weak formulations of the equations of motion are presented. The problem is then formulated as a second-order equation in time. The existence, uniqueness of the solutions, and continuity with respect to the data are discussed. DA - 1997/8// PY - 1997/8// DO - 10.1016/S0895-7177(97)00131-3 VL - 26 IS - 3 SP - 55-65 SN - 0895-7177 KW - damped elastic plates KW - in-plane dynamic vibrations KW - nonsymmetric damage KW - well-posedness ER - TY - JOUR TI - Mapping quantitative trait loci with dominant and missing markers in various crosses from two inbred lines AU - Jiang, CJ AU - Zeng, ZB T2 - GENETICA DA - 1997/// PY - 1997/// DO - 10.1023/A:1018394410659 VL - 101 IS - 1 SP - 47-58 SN - 0016-6707 KW - dominant markers KW - genetic mapping KW - Markov chain KW - missing data KW - quantitative trait loci ER - TY - JOUR TI - Interpreting DNA mixtures AU - Weir, B. S. AU - Triggs, C. M. AU - Starling, L. AU - Stowell, L. I. AU - Walsh, K. A. J. AU - Buckleton, J. T2 - Journal of Forensic Sciences DA - 1997/// PY - 1997/// VL - 42 IS - 2 SP - 213-222 ER - TY - JOUR TI - Influence of fall nitrogen and spring nitrogen-potassium applications on yield and fruit quality of 'Chandler' strawberry AU - Miner, G. S. AU - Poling, E. B. AU - Carroll, D. E. AU - Nelson, L. A. AU - Campbell, C. R. T2 - Journal of the American Society for Horticultural Science DA - 1997/// PY - 1997/// VL - 122 IS - 2 SP - 290-295 ER - TY - JOUR TI - Dietary fibre content of thirteen apple cultivars AU - Gheyas, F AU - Blankenship, SM AU - Young, E AU - McFeeters, R T2 - JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE AB - Fibre composition of the following 13 apple cultivars was studied: ‘Cortland’, ‘Empire’, ‘Fuji’, ‘Golden Delicious’, ‘Gala’, ‘Granny Smith’, ‘Jonagold’, ‘Mutsu’, ‘McIntosh’, ‘Delicious’, ‘Rome’, ‘Stayman’ and ‘York’. Fruit samples from each of these cultivars were analysed for non-starch cell wall materials (NSCWM) and non-starch polysaccharides (NSP). NSCWM was further fractionated into soluble and insoluble fibre fractions. Both NSCWM and NSP content were found to be significantly influenced by cultivar. NSCWM content ranged from 19·1 g kg−1 apple flesh in ‘Fuji’ to 36·2 g kg−1 in ‘York’. Mean(±SD) NSCWM content of all the cultivars was 23·1±4·5 g kg−1. NSP content of apple flesh ranged from 13·8 g kg−1 in ‘McIntosh’ to 28·7 g kg−1 in ‘York’ with the overall mean for all cultivars being 17·9±4·2 g kg−1. Relative amount of monosaccharides found in the hydrolysates of apple fibre also varied among cultivars. The greatest difference was observed in galactose content. ©1997 SCI DA - 1997/11// PY - 1997/11// DO - 10.1002/(SICI)1097-0010(199711)75:3<333::AID-JSFA883>3.0.CO;2-R VL - 75 IS - 3 SP - 333-340 SN - 0022-5142 KW - Malus domestica KW - apple KW - dietary fibre KW - firmness KW - soluble fibre KW - insoluble fibre ER - TY - JOUR TI - Developmental quantitative genetics, conditional epigenetic variability and growth in mice AU - Atchley, W. R. AU - Zhu, J. T2 - Genetics DA - 1997/// PY - 1997/// VL - 147 IS - 2 SP - 765-776 ER - TY - JOUR TI - A method for the incorporation of parametric uncertainty in the weighted evaluation multi-attribute decision analysis model AU - Lavelle, JP AU - Wilson, , JR AU - Gold, HJ AU - Canada, , JR T2 - COMPUTERS & INDUSTRIAL ENGINEERING AB - We develop an extension of the classic Weighted Evaluation (WE) Multi-Attribute Decision Analysis (MADA) model that allows for uncertainty in the parameters of the model. Uncertainties in attribute importance weights and alternative evaluation ratings are represented by independent uniform, triangular or beta random variables; and an iterative multi-variate integration scheme is used to evaluate the mean, variance and skewness of the resulting Probabilistic Weighted Evaluation (PWE). These moments are used to compute two-term Edgeworth and normal approximations to the distribution of: (a) the PWE for each of several alternatives that are to be analysed separately; or (b) the difference between PWEs for selected alternatives that are to be analysed on a pairwise basis. The proposed methodology is used to compare probabilistically three alternative solutions to the Mexico City Airport Siting Problem of Keeney and Raiffa (Keeney, R. L. and Raiffa, H., Decisions with Multiple Objectives. Wiley, New York, 1976). DA - 1997/9// PY - 1997/9// DO - 10.1016/S0360-8352(97)00012-0 VL - 32 IS - 4 SP - 769-786 SN - 0360-8352 ER - TY - JOUR TI - A consistent estimator for the distribution of quality adjusted survival time AU - Zhao, HW AU - Tsiatis, AA T2 - BIOMETRIKA AB - Quality adjusted survival analysis is a new approach to therapy evaluation in clinical trials. It has received much attention recently because of its ability to take patients' quality of life into consideration. In this paper, we present a method that enables us to calculate the survival distribution of quality adjusted lifetime. Using martingale theory for counting processes, we can show that our estimator is asymptotically consistent, normally distributed, and its asymptotic variance estimate can be obtained analytically. Simulation experiments are conducted to compare our estimator with the true underlying distribution for two cases that are of practical importance. DA - 1997/6// PY - 1997/6// DO - 10.1093/biomet/84.2.339 VL - 84 IS - 2 SP - 339-348 SN - 0006-3444 KW - counting process KW - martingale process KW - quality of life KW - survival analysis ER - TY - JOUR TI - The effect of economic thresholds and life-history parameters on the evolution of pesticide resistance in a regional setting AU - Peck, SL AU - Ellner, SP T2 - AMERICAN NATURALIST AB - We explore the dynamics of alleles conferring insecticide resistance in agroecosystems in which economic thresholds are used to manage insect pest populations. The dynamics of economic thresholds on resistance evolution are first explored in a single-field model. A two-dimensional cellular automata model is then used to examine the effects of migration, refuges, and crop rotation in a large region of fields under different management strategies. The single-field model indicates that economic thresholds may have important implications for pesticide management strategies, because resistance evolution is no longer independent of the growth process. In the regional model, the growth rate of the population, the selection pressure on the resistant allele, and migration all affect the time to resistance. Rotation is most beneficial when migration rates are either very high or very low and has little effect at intermediate migration rates. Resistance develops in large patches, so the level of resistance in a given field may be only weakly related to the history of pesticide treatment in that field. This finding may explain the high regional variability found in field studies of resistance in pests such as Colorado potato beetle. DA - 1997/1// PY - 1997/1// DO - 10.1086/285978 VL - 149 IS - 1 SP - 43-63 SN - 0003-0147 ER - TY - JOUR TI - On-line measurement of fabric bending behavior .1. Theoretical study of static fabric loops AU - Zhou, NYM AU - Ghosh, TK T2 - TEXTILE RESEARCH JOURNAL AB - In order to develop an on-line system to characterize fabric bending rigidity, four potential loop shapes are proposed. Loop shapes are chosen such that they can be formed under dynamic conditions. Results from theoretical models of these loops show the nature of the response of loop shapes to varying fabric bending behaviors. Two candidate loop shapes are identified for further investigation under nonlinear and dynamic conditions. DA - 1997/10// PY - 1997/10// DO - 10.1177/004051759706701003 VL - 67 IS - 10 SP - 712-719 SN - 1746-7748 ER - TY - JOUR TI - Functional marginality is important: response AU - Brinkley, P. A. AU - Meyer, K. P. AU - Lu, J.-C. T2 - Applied Statistics [Journal of the Royal Statistical Society. Series C] DA - 1997/// PY - 1997/// VL - 46 IS - 2 SP - 289-286 ER - TY - JOUR TI - Experimental confirmation of a PDE-based approach to design of feedback controls AU - Banks, HT AU - Smith, RC AU - Brown, DE AU - Silcox, RJ AU - Metcalf, VL T2 - SIAM JOURNAL ON CONTROL AND OPTIMIZATION AB - Issues regarding the experimental implementation of PDE-based controllers are discussed in this work. While the motivating application involves the reduction of vibration levels for a circular plate through excitation of surface-mounted piezoceramic patches, the general techniques described here will extend to a variety of applications. The initial step is the development of a PDE model which accurately captures the physics of the underlying process. This model is then discretized to yield a vector-valued initial value problem. Optimal control theory is used to determine continuous-time voltages to the patches, and the approximations needed to facilitate discrete-time implementation are addressed. Finally, experimental results demonstrating the control of both transient and steady-state vibrations through these techniques are presented. DA - 1997/7// PY - 1997/7// DO - 10.1137/S0363012995285909 VL - 35 IS - 4 SP - 1263-1296 SN - 0363-0129 KW - feedback control KW - piezoceramic actuators KW - PDE model ER - TY - JOUR TI - Computational methods for a curved beam with piezoceramic patches AU - Banks, HT AU - Zhang, Y T2 - JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES AB - We develop a computational scheme to approximate the solutions of a mathematical model that describes the vibrations of a curved beam structure. The physical model also includes pairs of piezoceramic patches that can be viewed either as passive devices, changing only the structural properties of the beam, or as active devices used to control vibrations of the beam. As part of our numerical experiments, we compare schemes with a method that employs hybrid B-spline basis elements and a method that employs just one family of B-spline basis elements. We calculate the first four fundamental frequencies and mode shapes of the structure, and we simulate patch-activated vibrations. Finally, we devote a section to investigation of locking phenomena which have been reported for some shell problems. DA - 1997/3// PY - 1997/3// DO - 10.1177/1045389X9700800307 VL - 8 IS - 3 SP - 260-278 SN - 1045-389X ER - TY - JOUR TI - Codon bias and plasticity in immunoglobulins AU - Kepler, TB T2 - MOLECULAR BIOLOGY AND EVOLUTION AB - Immunoglobulin genes experience Darwinian evolution twice. In addition to the germline evolution all genes experience, immunoglobulins are subjected, upon exposure to antigen, to somatic hypermutation. This is accompanied by selection for high affinity to the eliciting antigen and frequently results in a significant increase in the specificity of the responding population. The hypermutation mechanism displays a strong sequence specificity. Thus arises the opportunity to manipulate codon bias in a site-specific manner so as to direct hypermutation to those parts of the gene that encode the antigen-binding portions of the molecule and away from those that encode the structurally conserved regions. This segregation of mutability would clearly be advantageous; it would enhance the generation of potentially useful variants while keeping mutational loss to acceptably low levels. But it is not clear that the advantage gained would be large enough to produce a measurable effect within the background stochasticity of the evolutionary process. I have performed a pair of statistical tests to determine whether site-specific codon bias in human immunoglobulin genes is correlated with the sequence specificity of the somatic mutation mechanism. The sequence specificity of the mutator was determined by analysis of a database of published immunoglobulin intron sequences that had experienced somatic mutation but not selection. The site-specific codon bias was determined by analysis of published sequences of human germline immunoglobulin V genes. Both tests strongly suggest that evolution has acted to enhance the plasticity of immunoglobulin genes under somatic hypermutation. DA - 1997/6// PY - 1997/6// DO - 10.1093/oxfordjournals.molbev.a025803 VL - 14 IS - 6 SP - 637-643 SN - 0737-4038 KW - codon bias KW - immunoglobulin KW - somatic mutation KW - hypermutation KW - immunity ER - TY - JOUR TI - Tests for linkage and association in nuclear families AU - Martin, ER AU - Kaplan, NL AU - Weir, BS T2 - AMERICAN JOURNAL OF HUMAN GENETICS AB - The transmission/disequilibrium test (TDT) originally was introduced to test for linkage between a genetic marker and a disease-susceptibility locus, in the presence of association. Recently, the TDT has been used to test for association in the presence of linkage. The motivation for this is that linkage analysis typically identifies large candidate regions, and further refinement is necessary before a search for the disease gene is begun, on the molecular level. Evidence of association and linkage may indicate which markers in the region are closest to a disease locus. As a test of linkage, transmissions from heterozygous parents to all of their affected children can be included in the TDT; however, the TDT is a valid chi2 test of association only if transmissions to unrelated affected children are used in the analysis. If the sample contains independent nuclear families with multiple affected children, then one procedure that has been used to test for association is to select randomly a single affected child from each sibship and to apply the TDT to those data. As an alternative, we propose two statistics that use data from all of the affected children. The statistics give valid chi2 tests of the null hypothesis of no association or no linkage and generally are more powerful than the TDT with a single, randomly chosen, affected child from each family. DA - 1997/8// PY - 1997/8// DO - 10.1086/514860 VL - 61 IS - 2 SP - 439-448 SN - 0002-9297 ER - TY - JOUR TI - A joint model for survival and longitudinal data measured with error AU - Wulfsohn, MS AU - Tsiatis, AA T2 - BIOMETRICS AB - The relationship between a longitudinal covariate and a failure time process can be assessed using the Cox proportional hazards regression model. We consider the problem of estimating the parameters in the Cox model when the longitudinal covariate is measured infrequently and with measurement error. We assume a repeated measures random effects model for the covariate process. Estimates of the parameters are obtained by maximizing the joint likelihood for the covariate process and the failure time process. This approach uses the available information optimally because we use both the covariate and survival data simultaneously. Parameters are estimated using the expectation-maximization algorithm. We argue that such a method is superior to naive methods where one maximizes the partial likelihood of the Cox model using the observed covariate values. It also improves on two-stage methods where, in the first stage, empirical Bayes estimates of the covariate process are computed and then used as time-dependent covariates in a second stage to find the parameters in the Cox model that maximize the partial likelihood. DA - 1997/3// PY - 1997/3// DO - 10.2307/2533118 VL - 53 IS - 1 SP - 330-339 SN - 0006-341X KW - EM algorithm KW - longitudinal data KW - repeated measures KW - survival ER - TY - JOUR TI - Validity of spatial analyses for large field trials AU - Brownie, C. AU - Gumpertz, M. L. T2 - Journal of Agricultural, Biological, and Environmental Statistics DA - 1997/// PY - 1997/// VL - 2 IS - 1 SP - 1-23 ER - TY - JOUR TI - Shape matching with smart material structures using piezoceramic actuators AU - Fitzpatrick, BG T2 - JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES AB - In this paper, we consider the problem of driving a flexible structure from an "unforced" equilibrium position to a given desired shape. Within the context of smart materials, we focus on piezoceramic actuators as controls. Our approach is to base the choice of input voltages on a physical model of the structure, with "good" voltage choices being those whose modelbased displacements "'closely" match the desired shape. This shape matching problem is posed as a least squares problem in a Hilbert space that represents the displacement component of the state space of the flexible structure model. Here we treat the structure as a distributed parameter system, so that the state space is infinite dimensional. Thus, we must examine questions of existence of solutions and convergence of approximations. To illustrate our techniques, we give some numerical examples. DA - 1997/10// PY - 1997/10// DO - 10.1177/1045389X9700801007 VL - 8 IS - 10 SP - 876-882 SN - 1045-389X ER - TY - JOUR TI - Periodicity and stochastic trends in economic time series. P H Franses AU - Hall, A. R. T2 - Economic Journal DA - 1997/// PY - 1997/// VL - 107 IS - 444 SP - 1602-1603 ER - TY - JOUR TI - Mantel-Haenszel test statistics for correlated binary data AU - Zhang, J AU - Boos, DD T2 - BIOMETRICS AB - This paper proposes two new Mantel-Haenszel test statistics for correlated binary data in 2 x 2 tables that are asymptotically valid in both sparse data (many strata) and large-strata limiting models. Monte Carlo experiments show that the statistics compare favorably to previously proposed test statistics, especially for 5-25 small to moderate-sized strata. Confidence intervals are also obtained and compared to those from the test of Liang (1985, Biometrika 72, 678-682). DA - 1997/12// PY - 1997/12// DO - 10.2307/2533489 VL - 53 IS - 4 SP - 1185-1198 SN - 0006-341X KW - multicenter clinical trials KW - odds ratio KW - sparse data KW - strata ER - TY - JOUR TI - Hardy-Weinberg testing for continuous data AU - McIntyre, L. M. AU - Weir, B. S. T2 - Genetics DA - 1997/// PY - 1997/// VL - 147 IS - 4 SP - 1965-1975 ER - TY - JOUR TI - Generating confidence intervals for composition-based landscape indexes AU - Hess, GR AU - Bay, JM T2 - LANDSCAPE ECOLOGY DA - 1997/10// PY - 1997/10// DO - 10.1023/A:1007967425429 VL - 12 IS - 5 SP - 309-320 SN - 1572-9761 KW - landscape indexes KW - landscape diversity KW - accuracy assessment KW - uncertainty KW - classification error KW - error matrixes KW - bootstrapping ER - TY - JOUR TI - Calibration inference based on multiple runs of an immunoassay AU - Zeng, Q AU - Davidian, M T2 - BIOMETRICS AB - Several authors have documented the poor performance of usual large-sample, individual calibration confidence intervals based on a single run of an immunoassay. Inaccuracy of these intervals may be attributed to the paucity of information on model parameters available in a single run. Methods for combining information from multiple runs to estimate assay response variance parameters and to refine characterization of the standard curve for the current run via empirical Bayes techniques have been proposed. We investigate formally the utility of these techniques for improving the quality of routine individual calibration inference. DA - 1997/12// PY - 1997/12// DO - 10.2307/2533499 VL - 53 IS - 4 SP - 1304-1317 SN - 0006-341X KW - confidence interval KW - empirical Bayes KW - nonlinear mixed effects KW - pooled variance estimation ER - TY - JOUR TI - A Monte Carlo permutation approach to choosing an affection status model for bipolar affective disorder AU - Simonsen, K. L. AU - Kaplan, N. L. AU - Martin, E. R. T2 - Genetic Epidemiology DA - 1997/// PY - 1997/// VL - 14 IS - 6 SP - 681-686 ER - TY - PCOMM TI - Transmission/disequilibrium tests for multiallelic loci: reply AU - Kaplan, N. L. AU - Martin, E. R. AU - Weir, B. S. DA - 1997/// PY - 1997/// SP - 778 ER - TY - JOUR TI - Testing homogeneity of intra-run variance parameters in immunoassay AU - Zeng, Q AU - Davidian, M T2 - STATISTICS IN MEDICINE AB - A common assumption in the analysis of immunoassay data is a similar pattern of within-run variation across runs of the assays. One makes this assumption without formal investigation of its validity, despite the widely acknowledged fact that accurate understanding of intra-run variation is critical to reliable calibration inference. We propose a simple procedure for a formal test of the assumption of the homogeneity of parameters that characterize intra-run variation based on representation of standard curve data from multiple assay runs by a non-linear mixed effects model. We examine the performance of the procedure and investigate the robustness of calibration inference to incorrect assumptions about the pattern of intra-run variation. DA - 1997/8/15/ PY - 1997/8/15/ DO - 10.1002/(SICI)1097-0258(19970815)16:15<1765::AID-SIM603>3.0.CO;2-P VL - 16 IS - 15 SP - 1765-1776 SN - 0277-6715 ER - TY - JOUR TI - Spherical-radial integration rules for Bayesian computation AU - Monahan, J. AU - Genz, A. T2 - Journal of the American Statistical Association AB - Abstract The common numerical problem in Bayesian analysis is the numerical integration of the posterior. In high dimensions, this problem becomes too formidable for fixed quadrature methods, and Monte Carlo integration is the usual approach. Through the use of modal standardization and a spherical-radial transformation, we reparameterize in terms of a radius r and point z on the surface of the sphere in d dimensions. We propose two types of methods for spherical-radial integration. A completely randomized method uses randomly placed abscissas for the radial integration and for the sphere surface. A mixed method uses fixed quadrature (i.e., Simpson's rule) on the radius and randomized spherical integration. The mixed methods show superior accuracy in comparisons, require little or no assumptions, and provide diagnostics to detect difficult problems. Moreover, if the posterior is close to the multivariate normal, then the mixed methods can give remarkable accuracy. DA - 1997/// PY - 1997/// DO - 10.1080/01621459.1997.10474018 VL - 92 IS - 438 SP - 664-674 ER - TY - BOOK TI - SPC methods for quality improvement AU - Quesenberry, C. P. CN - TS156.8 .Q47 1997 DA - 1997/// PY - 1997/// PB - New York, NY: Wiley SN - 0471130877 ER - TY - JOUR TI - Risk analyses in clonal forestry AU - Roberds, JH AU - Bishir, JW T2 - CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE AB - The number of clones to use in plantations is an important problem that must be addressed by practitioners of clonal forestry because of productivity and forest health considerations. This problem has been analyzed from a number of perspectives, but analyses based upon risk of plantation failure have provided special insight about effects produced by an increase in numbers of clones. In this paper, we describe alternative models and methods that have been proposed to investigate the effect of number of clones on risk of plantation failure following an unforeseen catastrophic event. Properties of these models are reviewed and conclusions resulting from the analysis of each model are given. Results from these analyses and recently developed theory indicate that use of 30 to 40 unrelated clones in plantations provides protection against catastrophic failure roughly equivalent to the use of large numbers of unrelated clones. A detailed description of the recently introduced time-to-failure model is also presented, and several examples that illustrate properties of this model are discussed. Finally, some implications regarding the development of breeding populations are identified and explored. Resume : La problOmatique du nombre de clones utilisOs dans les plantations clonales doit Œtre abordOe par les praticiens de la foresterie clonale en raison des implications quielle peut avoir pour la productivitO et la santO des forŒts. Ce problme a OtO OtudiO sous de nombreux angles, mais il siest avOrO que liapproche basOe sur le risque diOchec de plantation a permis de rOvOler les effets rOsultant diune augmentation du nombre de clones utilisOs. Les auteurs de liOtude font la description des mOthodes et modles alternatifs qui ont OtO proposOs pour Otudier lieffet du nombre de clones sur le risque diOchec de plantation suite ‡ un OvOnement catastrophique imprOvisible. Les auteurs prOsentent la revue des caractOristiques ainsi que les conclusions dOcoulant de lianalyse de chacun de ces modles. Les rOsultats de cette analyse ainsi que les considOrations thOoriques dOveloppOes rOcemment indiquent que liutilisation de 30 ‡ 40 clones non apparentOs par plantation procure une protection contre des Ochecs catastrophiques qui est ‡ peu prs Oquivalente ‡ celle qui dOcoule de liutilisation diun grand nombre de clones non apparentOs. Une description dOtaillOe du modle rOcent de «dOlai diOchec» est prOsentOe. Quelques exemples illustrant les caractOristiques de ce modle sont Ogalement discutOs. Enfin, certaines implications relatives au dOveloppement des populations diOlevage sont identifiOes et discutOes. (Traduit par la ROdaction) DA - 1997/3// PY - 1997/3// DO - 10.1139/x96-202 VL - 27 IS - 3 SP - 425-432 SN - 0045-5067 ER - TY - JOUR TI - Effects of measurement error on catch-effort estimation AU - Gould, WR AU - Stefanski, LA AU - Pollock, KH T2 - CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES DA - 1997/4// PY - 1997/4// DO - 10.1139/cjfas-54-4-898 VL - 54 IS - 4 SP - 898-906 SN - 1205-7533 ER - TY - JOUR TI - A linear theory for jet streak formation due to zonal momentum forcing in a stably stratified atmosphere AU - Weglarz, RP AU - Lin, YL T2 - JOURNAL OF THE ATMOSPHERIC SCIENCES AB - A perturbation potential vorticity (PV) theory is developed to investigate the three-dimensional, time-dependent, linear geostrophic adjustment of a stably stratified, Boussinesq atmosphere that is disturbed from (i) quiescent equilibrium due to a localized, unbalanced, zonal wind anomaly and (ii) geostrophic equilibrium of the uniform zonal flow due to an isolated couplet of acceleration–deceleration forcing. This prescribed zonal momentum forcing propagates downstream at a speed c that is less than the basic-state zonal flow speed U and physically represents the parameterized effects of nonlinear inertial advection. Transient, dispersive inertia–gravity waves in all fields are essentially removed during the early stage of the response associated with the initial value problem. The steady-state equilibrium that conserves the initial perturbation PV is a localized, geostrophic zonal jet with meridionally confluent (diffluent) flow in its entrance (exit) region. This jet is supported by a couplet of perturbation low and high pressure north and south of the zonal jet core, respectively. There exist no steady-state ageostrophic winds and vertical motions once balanced equilibrium is reached. This long-term asymptotic response characterizes a localized linear thermal wind balance among the baroclinic perturbations that will not be preserved in the nonlinear initial value problem. The forced response for a uniform, stably stratified, zonal flow whose Rossby number is RoU = (U − c)/2af = 0.1, where a is the half-width of the prescribed zonal momentum forcing as seen by a Galilean observer traveling at the speed c < U, shows many similar characteristics with the forced shallow water flow response of Weglarz. In particular, the early response for t ≤ τ = 2a/(U − c) is characterized by a pair of easterly and westerly zonal jet streaks produced by flow acceleration/deceleration in the forcing entrance/exit region. The mass field quickly adjusts to the sub-Rossby scale (a ≪ 2djetN/f) perturbations in the wind field, forming a pair of high–low couplets that geostrophically support the isolated zonal jets. For t > τ, the easterly zonal jet is advected downstream at the relative velocity U − c, leaving an isolated, meso-α-scale, westerly zonal jet streak in the vicinity of the forcing center. The ageostrophic winds characterize a mesoscale cyclonic circulation that circumvents the forcing center. The divergence associated with this circulation produces a four-cell pattern of vertical motion that flanks the core of the zonal jet streak. This pattern of steady, externally forced, vertical motion is reversed from the pattern normally inferred from traditional nonlinear quasigeostrophic jet streak dynamics because the accelerations produced by the imposed zonal momentum forcing dominate those produced by local time rate of change and linear inertial advection of the geostrophic flow. DA - 1997/4/1/ PY - 1997/4/1/ DO - 10.1175/1520-0469(1997)054<0908:ALTFJS>2.0.CO;2 VL - 54 IS - 7 SP - 908-932 SN - 0022-4928 ER -