bluuebunny/crossref_metadata_2025 huggingface dataset:
Nutritional Consequences of Experimentally Introduced Tourism in Brown Bears
Authors: RODE KARYN D. , FARLEY SEAN D. , FORTIN JENNIFER , ROBBINS CHARLES T.
Published: May 2007

Abstract:Although numerous studies have documented behavioral effects of nature‐based tourism on wildlife populations, few studies have determined whether behavioral changes translate to effects on individual condition and population health. This issue is currently a concern for wildlife managers in Alaska, USA, and Canada where bear viewing is a rapidly growing industry expanding into previously undisturbed bear habitats. Rather than record observations at long established tourism sites, we experimentally introduced bear viewing into 2 relatively undisturbed brown bear(Ursus arctos)populations in south‐central Alaska. We examined the nutritional consequences of behavioral changes induced by the presence and activity of bear viewers for bears feeding on early summer vegetation and late‐summer salmon(Oncorhynchus kisutchandO. nerka).We used Global Positioning System collars, monitored food resource availability, and quantified individual resource use and condition for a year prior to and during the introduction of bear viewing. Though bear viewing altered spatiotemporal resource use in all treatments, total resource use declined only when we exposed bears to 24‐hour daily human activity. Energy expenditure, indexed as daily travel distances, was significantly higher when bears responded by altering spatial rather than temporal resource use. However, body weight and composition were unaffected by all treatments as bears shifted their foraging to other locations or times. Managers can minimize nutritional impacts of bear‐viewing programs by avoiding spatial displacement and providing predictable time periods when bears can access food resources free of human activity. Bears in this study exhibited a high degree of behavioral plasticity, which may be an important factor in identifying flagship species for sustainable ecotourism programs.
Detectability and Response Rates of Ferruginous Pygmy‐Owls
Authors: FLESCH AARON D. , STEIDL ROBERT J.
Published: May 2007

Abstract:Survey techniques that are both reliable and efficient are necessary to accurately estimate population parameters, especially for rare species. Cactus ferruginous pygmy‐owls (Glaucidium brasilianum cactorum;hereafter pygmy‐owls) have declined in southwestern North America and are surveyed often to comply with federal law. We studied owl responses to broadcasted calls to quantify how detectability and response rates (owls/station/transect) vary with environmental, spatial, temporal, and weather‐related factors. We surveyed owls along 392 transects (1,113 km) throughout Sonora, Mexico, including a subset of 14 transects (47.2 km) that we surveyed repeatedly to assess factors that affected response rates. We challenged 17 adults and 23 juveniles that were radiomarked, adults attending 50 occupied nests, and adults attending 6 groups of radiomarked juveniles to respond to broadcasted calls to assess factors that affected detectability. Across Sonora, response time averaged 2.6 ± 0.1 minutes (xM ± SE,n= 520), with 99 ± 0.4% of owls detected in ≤8 minutes; response distance averaged 251 ± 7 m, with 91 ± 1% of owls detected at ≤400 m. Response time decreased by an average of 4 ± 2% and response distance decreased by 12 ± 3 m with each half‐month period from early courtship through brooding (P≤ 0.035). Response time averaged 39 ± 24% faster during morning than midday at occupied nests. Detectability was 1.0 ± 0.0 when surveyors were 100 m from occupied nests and decreased to 0.78 ± 0.10 when surveyors were 500 m from occupied nests. Detectability was higher during incubation, brooding, and natal dispersal (0.89 ± 0.05‐1.0 ± 0.0) than during fledgling‐dependency (0.50 ± 0.20‐0.67 ± 0.19). Response rates of males did not vary from early courtship to brooding (P= 0.84), yet those of females decreased systematically to zero across the same period (P< 0.001). Because detectability of pygmy‐owls remains consistently high during nesting, response rates generated from carefully designed surveys can provide reliable estimates of occupancy and abundance.
Projected Availability of Natural Cavities for Wood Ducks in Southern Illinois
Authors: NIELSEN CHARLOTTE L. ROY , GATES ROBERT J. , ZWICKER EDWARD H.
Published: May 2007

Abstract:Wood ducks (Aixsponsa)and other species use tree cavities in forested wetlands and adjacent upland forests for nest sites and cover. The availability of tree cavities suitable for nesting is important to the population dynamics of hole‐nesting species, but there is little quantitative information on how forest succession and maturation affect densities of suitable nest sites in eastern deciduous forests. Several studies have measured availability of tree cavities for nesting wood ducks, but data on cavity formation and persistence rates are needed to model changes in cavity abundance. We measured abundance and persistence of tree cavities suitable for nesting wood ducks in southern Illinois, USA, during 1993‐2002. We simulated changes in abundance of nest cavities in the Mississippi River floodplain and adjacent upland forests using estimates of tree cavity densities by tree‐diameter size classes and 10‐year cavity persistence rates by tree species. Cavities were disproportionately common in the largest size classes, but tree species varied in their propensity to form cavities. Beech(Fagus grandifolia;0.41 cavities/tree) and sycamore(Plantanus occidentalis;0.50 cavities/tree) were prolific cavity producers, whereas a small proportion (0.05 cavities/tree) of cottonwoods(Populus deltoides)contained cavities. Kaplan‐Meier estimates of annual and 10‐year cavity persistence averaged 0.95 and 0.64, respectively. Cavity persistence also differed among species (P= 0.02): cottonwoods had the lowest (0.54) and sycamores had the highest (0.89) 10‐year tree cavity persistence rates. Tree fall (50.0%), cavity floor deterioration (37.5%), and narrowing of the cavity entrance (12.5%) were the most prevalent causes of tree cavity loss. Forest stand projections indicated that cavity abundance will increase up to 34% over recent levels during the first 10 years and by 44% after 50 years. Most of this increase will be contributed by tree species that are not commonly used by wood ducks, but cavities will increase in oaks(Quercusspp.) and beeches as the forest matures into cavity‐bearing size classes. Sycamores will steadily contribute cavities, but cottonwood is predicted to provide fewer cavities due to low survival of cavity‐bearing size classes. Our results suggest that availability of nest and den sites for cavity‐dependent wildlife will increase as eastern deciduous forests mature over the next half century. Cost‐effectiveness of artificial nest box programs should be reevaluated in light of projected changes in tree cavity availability as deciduous forests mature in the eastern United States.
A Method for Capturing Pygmy Rabbits in Summer
Authors: LARRUCEA EVELINE S. , BRUSSARD PETER F.
Published: May 2007

Abstract: Degradation of sagebrush habitat and a lack of information on current status motivated a petition to list the pygmy rabbit (Brachylagus idahoensis) as threatened or endangered under the Endangered Species Act. The petition brought on renewed interest in obtaining data on pygmy rabbits; however, pygmy rabbits are notoriously difficult to capture, especially in summer. We tested box‐trap, net, noose‐pole, and fabric‐fence methods to capture pygmy rabbits in 4 areas of northern Nevada and eastern California, USA. We captured 25 different pygmy rabbits in 30 captures from April 2005 to July 2006. The combination of camouflaged box traps baited with canned green beans was 35% more successful and required less effort per captured rabbit than any other method. Noose‐pole methods also were successful. These techniques provide an efficient method of capturing pygmy rabbits in summer when many remote field sites are most accessible.
Survival and Cause‐Specific Mortality of Neonatal Mule Deer Fawns, North‐Central New Mexico
Authors: LOMAS LAURIE A. , BENDER LOUIS C.
Published: May 2007

Abstract: Because of significant declines in mule deer (Odocoileus hemionus) populations across New Mexico, USA, we investigated survival of fawns in north‐central New Mexico, USA. We captured 19 fawns, 34 fawns, and 47 fawns in 2002, 2003, and 2004, respectively, and used fawn morphological measurements, habitat characteristics, and adult female (hereafter “female”) condition to model preweaning fawn survival. Survival was 0.0, 0.12, 0.52 for 2002, 2003, and 2004, respectively, and was related to birth mass (χ12 = 9.5, P = 0.002), birth date (χ12= 8.4, P = 0.004), litter size (χ22 = 9.4, P = 0.009), female body fat (χ12 = 40.9, P < 0.001), annual precipitation (χ12 = 35.0, P < 0.001), summer precipitation (χ12= 37.5, P < 0.001), and winter precipitation (χ12 = 32.0, P < 0.001). Total ingesta‐free body fat of females (β = 3.01, SE = 0.75; odds ratio = 20.19, 95% CI = 4.64‐87.91) and birth mass of fawns (β = 1.188, SE = 0.428; odds ratio = 3.38, 95% CI = 1.42‐7.59) were the best predictors of survival of individual fawns, although few of the logistic models differed in model selection criteria. Fawn survival in north‐central New Mexico was driven by an interaction of total and seasonal precipitation and its effect on plant production, consequential effects on female nutrition, and ultimately, fawn birth attributes. Habitat conditions were so poor throughout north‐central New Mexico during 2002 and 2003 (and likely during other drought yr) that, based upon birth attributes, few fawns could have survived regardless of proximate causes of mortality. In 2004, precipitation enhanced security cover, maternal body condition, birth attributes and, thus, survival of fawns. However, more habitat enhancements are needed to improve the nutritional quality of mule deer habitats in north‐central New Mexico and further enhance maternal and fawn condition to recover mule deer populations in this region.
Population Irruptions of Northern Bobwhite: Testing an Age‐Specific Reproduction Hypothesis
Authors: HERNÁNDEZ FIDEL , KELLEY KRISAN M. , ARREDONDO JUAN A. , HERNÁNDEZ FROYLÁN , HEWITT DAVID G. , BRYANT FRED C. , BINGHAM RALPH L.
Published: May 2007

Abstract: Age‐specific reproduction has been suggested for northern bobwhite (Colinus virginianus) and has been hypothesized as a factor contributing to population irruptions. However, little research has been conducted on the subject. We conducted a laboratory and field study to determine if age‐specific reproduction occurred in northern bobwhites. Our objectives were to compare 7 reproductive measures (% F nesting, date of first incubated nest, egg‐laying rate, nesting rate, clutch size, egg mass, and egg hatchability) between first‐ and second‐year breeders and determine if differential reproduction was impacted by diet quality. The laboratory study consisted of a 2 × 2 factorial experiment with age and diet quality (low protein [12%] and high protein [24%]) as the factors. Data for the field study represented a 6‐year data set of bobwhite reproduction (May‐Sep 2000‐2005) obtained from an ongoing radiotelemetry study in southern Texas, USA. We documented similar productivity (i.e., % F laying, egg‐laying rate, and egg mass) and timing of laying (i.e., date of first egg) between juvenile (n = 33) and adult bobwhites (n = 27) in our laboratory study. However, females on the high‐protein diet exhibited a greater egg‐laying rate than females on the low‐protein diet. Under field conditions, we also documented no difference in productivity (% F nesting, nesting rate, clutch size, egg hatchability) and timing of nesting (date of first incubated nest) between age classes (n = 59 juv and 32 ad). Our findings do not support early suppositions of age‐specific reproduction in quail. Quail irruptions should not be influenced by population age structure as it relates to age‐specific reproduction.
Conceptualizing Brazilian Multiple and Fluid Cultural Profiles
Authors: Caldas Miguel P.
Published: May 2007

This paper puts forth a conceptual framework of multiple and fluid national culture focused on the contemporary Brazilian context. Drawing from recent criticism on the excessive determinism and simplicity of typical cross‐cultural depictions, the study (1) analyzes Brazilian contemporary culture from a historical perspective; (2) summarizes prevailing Brazilian cultural depictions in the literature; (3) proposes a conceptual framework centered on the dynamics between cultural differentiation and homogeneity, putting forth predictions on the potential future shifts of the Brazilian cultural texture along these two extremes; and (4) makes the case for culture research focused further on the study and depiction of multiple national cultures, and on their fluidity over time, rather than on monolithic and stable national cultures.
Mexico’s Management and Organization Studies Challenges in the Twenty‐First Century: Practices, Knowledge, and Reencounters
Authors: Ibarra‐Colado Eduardo
Published: May 2007

The paper demonstrates that management and organization studies (MOS) differ if we consider them from an Anglo‐centric point of view or if we look at them from the hybrid‐modernity of countries such as Mexico. The argument will be developed as follows. First, the relatively small attention traditionally given to MOS in Mexico is shown, and also noted is the recent change in this situation because of modernization process. Second, the paper recognizes the transformations of the organization and operation of the world under globalization and neoliberalism considering the generalization of an organizational imperative expressed in new practices and a new mode of rationality. Then the paper characterizes the recent development of MOS explaining its paradigmatic explosion and increasing fragmentation to those changes already discussed. The argument concludes by recognizing the Anglo‐centric condition of MOS and its inability to consider other realities from a decentered point of view. This condition places the urgency of a reencounter with the main agendas of MOS in countries such as Mexico in order to demonstrate the challenges faced by the discipline in a globalized but differentiated world.
Sketches of Spain: The Politics of Fashion
Authors: Carter Chris , Clegg Stewart , Kornberger Martin , Mueller Frank , Contardo Ianna
Published: May 2007

In this paper, we propose an understanding of what personnel professionals consume when they “adopt” black‐box management initiatives (Scarbrough, 1995; Wilson, 1992). Second, we explore the way in which professional associations and, hence, institutional actors pursue their own professional projects (Abbott, 1988) within a context of political legitimacies and illegitimacies. Thus, in a double move, we seek to explore the linkages between managerial methods used by institutions to increase their jurisdiction or their “authority to speak” (Foucault, 1972) and the processes of isomorphism.
The effects of alcohol and the salience of aggressive cues on triggered displaced aggression
Authors: Denson Thomas F. , Aviles Fredy E. , Pollock Vicki E. , Earleywine Mitch , Vasquez Eduardo A. , Miller Norman
Published: May 2007

Alcohol increases the aggression‐augmenting effects of provocation. Theories of alcohol and aggression suggest that impaired cognitive processing induced by acute intoxication leads individuals to process aggression‐inducing social cues differently depending on whether they are high or low in salience. We examined the effects of intoxication and aggressive cue salience within the triggered displaced aggression paradigm. An ethnically diverse sample of 74 primarily young adult participants (40 men and 34 women; M=23.28, SD=3.14 years) were recruited from the university community and surrounding area. All participants were provoked by an experimenter, randomly assigned to a 2 (alcohol condition: alcohol vs. placebo) × 2 (trigger salience: high vs. low salience) between‐subjects design, and then given the opportunity to aggress against the undeserving triggering agent. As expected, intoxication combined with a salient triggering cue elicited the most displaced aggression among all conditions. These results provide the first evidence that the effect of alcohol on triggered displaced aggression is moderated by the salience of the triggering event. Aggr. Behav. 34:25–33, 2008. © 2007 Wiley‐Liss, Inc.
The geometry of separation boundaries: Four‐component mixtures
Authors: Bellows Meghan , Lucia Angelo
Published: May 2007

The determination of distillation boundaries for four‐component mixtures that exhibit azeotropy is studied. It is shown that these distillation boundaries correspond to local maxima in surface areas under conditions of Levi‐Civita parallelism. An extension of the optimization methodology given in Lucia and Taylor is used to determine local maxima in surface areas by repeatedly computing maximum line integrals or distances in one spherical coordinate over a set of initial conditions that span the range of the second spherical coordinate. An optimization formulation that defines the determination of local maxima in surface areas subject to residue curve and stable node constraints is given. Numerical measurement of surface areas is accomplished using a triangulation procedure. Several numerical examples of varying complexity involving four‐component mixtures that exhibit azeotropes are presented to show the efficacy of the proposed optimization methodology. Geometric illustrations are used throughout to highlight key features of our methodology for determining distillation boundaries in four‐component mixtures. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Compressible cake characterization from steady‐state filtration analysis
Authors: Kovalsky Peter , Gedrat Marion , Bushell Graeme , Waite T. David
Published: May 2007

A numerical technique for quantifying the key material properties that describe how a flocculated suspension behaves under constant pressure filtration is presented with unrestricted compressive yield stress and permeability models used to describe these material properties. Using an iterative procedure, the optimal parameters for these models are calculated as are pressure and solid fraction distribution profiles. Input parameters to the numerical analysis are flux and final cake height data obtained from batch filtration experiments, which are driven to steady‐state. This technique is validated against piston driven filtration (odeometer) and centrifuge experiments for zirconia, soil particles, and yeast assemblages. The compressive yield stress calculated from filtration experiments agrees well with values obtained by odeometer and centrifuge studies for all particle systems studied at both the low and high solid pressure regions. Similarly, the calculated permeability agrees well with the measured permeability. © 2007 American Institute of Chemical Engineers AIChE J, 2007
The politics of lead toxicology and the devastating consequences for children
Authors: Rosner David , Markowitz Gerald
Published: May 2007

At virtually every step in the history of the uncovering of lead's toxic qualities, resistance was shown by a variety of industrial interests to the association of lead and toxicity. During the first half of the last century, three primary means were used to undermine the growing body of evidence: first, the lead industry sought to control lead research by sponsoring and funding university research. In the 1920s, the General Motors Company, with the aide of DuPont and Standard Oil Companies, established the Kettering Labs, a research unit at the University of Cincinnati which, for many decades was largely supported by industry funds. In the same decade, the lead industry sponsored the research of Joseph Aub at Harvard who worked on neurophysiology of lead. A second way was to shape our understanding of lead itself, portraying it as an indispensable and healthful element essential for all modern life. Lead was portrayed as safe for children to use, be around, and even touch. The third way that lead was exempted from the normal public health measures and regulatory apparatus that had largely controlled phosphorus poisoning, poor quality food and meats and other potential public health hazards was more insidious and involved directly influencing the scientific integrity of the clinical observations and research. Throughout the past century tremendous pressure by the lead industry itself was brought to bear to quiet, even intimidate, researchers and clinicians who reported on or identified lead as a hazard. This article will draw on our previous work and add new documentation of the trajectory of industry attempts to keep out of the public view the tremendous threat of lead poisoning to children. Am. J. Ind. Med. 50:740–756, 2007. © 2007 Wiley‐Liss, Inc.
The 19‐bp deletion polymorphism in intron‐1 of dihydrofolate reductase (DHFR) may decrease rather than increase risk for spina bifida in the Irish population
Authors: Parle‐McDermott Anne , Pangilinan Faith , Mills James L. , Kirke Peadar N. , Gibney Eileen R. , Troendle James , O'Leary Valerie B. , Molloy Anne M. , Conley Mary , Scott John M. , Brody Lawrence C.
Published: May 2007

Periconceptional maternal folic acid supplementation can prevent up to 70% of pregnancies affected with neural tube defects (NTDs), including spina bifida. This has focused attention on folate‐related genes such as dihydrofolate reductase (DHFR) in a bid to identify the genetic factors that influence NTD risk through either the fetal or maternal genotype. We considered a novel intronic 19‐bp deletion polymorphism and two polymorphisms within the 3′ untranslated region (721A > T and 829C > T) of the DHFR gene as candidates for NTD risk. We studied NTD cases (n = 283), mothers of cases (n = 280), fathers of cases (n = 279), and controls (n = 256). We did not find the DHFR 829C > T polymorphism to be variable within the Irish population. The 19‐bp intron deletion and the 721A > T polymorphisms were found to be in linkage disequilibrium. In contrast to a previous study, the 19‐bp intron deletion allele did show a significant protective effect in mothers of NTD cases when present in one (relative risk 0.59 [95%CI: 0.39–0.89], P = 0.01) or two copies (relative risk 0.52 [95%CI: 0.32–0.86], P = 0.01). Analysis of mRNA levels revealed a small increase in expression (∼1.5‐fold) associated with the 19‐bp intron deletion polymorphism, but this was not significant. In conclusion, the DHFR intron 19‐bp deletion allele may be a protective NTD genetic factor by increasing DHFR mRNA levels in pregnant women. © 2007 Wiley‐Liss, Inc.
Metabolic effects of static magnetic fields on streptococcus pyogenes
Authors: Morrow A.C. , Dunstan R.H. , King B.V. , Roberts T.K.
Published: May 2007

This study aimed to develop a simple experimental system utilising bacterial cells to investigate the dose responses resulting from exposures to static magnetic flux densities ranging from 0.05 to 0.5 T on viability, bacterial metabolism and levels of DNA damage in Streptococcus pyogenes. Exposure of S. pyogenes to a field of 0.3 T at 24 °C under anaerobic conditions resulted in a significant (P < 0.05) decrease in growth rate, with an increased mean generation time of 199 ± 6 min compared to the control cells at 165 ± 6 min (P < 0.05). Conversely, exposure to magnetic fields of 0.5 T significantly accelerated the growth rate at 24 °C compared to control cells, with a decreased mean generation time of 147 ± 4 min (P < 0.05). The patterns of metabolite release from cells incubated in phosphate buffered saline (PBS) at 24 °C and exposed to different magnetic flux densities (0.05–0.5 T) were significantly (P < 0.05) altered, compared to non‐exposed controls. Concentrations of metabolites, with the exception of aspartic acid (r = 0.44), were not linearly correlated with magnetic flux density, with all other r < 0.20. Instead, “window” effects were observed, with 0.25–0.3 T eliciting the maximal release of the majority of metabolites, suggesting that magnetic fields of these strengths had significant impacts on metabolic homeostasis in S. pyogenes. The exposure of cells to 0.3 T was also found to significantly reduce the yield of 8‐hydroxyguanine in extracted DNA compared to controls, suggesting some possible anti‐oxidant protection to S. pyogenes at this field strength. Bioelectromagnetics 28:439–445, 2007. © 2007 Wiley‐Liss, Inc.
Hayman's Graphical Analysis in Segregating Generations of a Diallel Cross
Authors: Singh M. , Singh R. K.
Published: May 2007

The expected values of average degree of dominance in F2 and later segregating generations of a diallel cross have been mathematically derived, and compared to its value in F1 generation. The interpretation of intercepts on Wr axis, a measure of average degree of dominance, differed in segregating generations from that of F1 at origin, and between origin and tangent in Wr, Vr‐graph.
Die praktische Belevanz des McNemar‐Tests
Authors: Zimmermann H.
Published: May 2007

By application of the McNemar‐Test the question of the practical relevance (practical significance) of the resulting test statistic generally arises. An analogy to the t‐Test for paired measurements gives some measure for the practical relevance. The evaluation of this relevance is based upon suggestions made by COHEN (1977).
Cluster Analysis via Density Functions: Amelioration of a Lower Bound of the Parameter
Authors: Kopp B.
Published: May 2007

This paper refers to an earlier investigation on Cluster Analysis procedures based on general empirical density functions, in which the number of classes is controled by a positive parameter λ: the number of clusters, m, increases as λ →∞. Since there is no functional relationship between m and λ, upper and lower bounds of the parameter are of interest (see KOPP, 1976a). We now give a better value for the lower bound of λ in the case of the multivariate normal distribution.
Local and Regional vs. Global Contingency Testing
Authors: Havránek T. , Lienert G. A.
Published: May 2007

Contingency analysis of r × c‐tables is systematized as follows: Global contingency testing based on the total chisquare under H0 of independent row and column variables is least favorable to exhaustive interpretation. Local contingency testing based on chi‐square components of the individual cells of an r × c‐table and realized in Configural frequency analysis (KRAUTH and LIENERT, 1973) is more favourable to substantive interpretation. Compromising between global and local contingency testing leads to so‐called generalized local and regional contingency testing. Every contingency testing (local, regional and naturally global) is including all N individuals of a sample supposed to have been drawn randomly from a defined population. Extension to 3‐and t‐dimensional contingency analysis is outlined, and biomedical applications are discussed.
Symmetric Intervals and Confidence Intervals
Authors: Baudoin Claude , O'quigley John
Published: May 2007

We show that the symmetric “confidence intervals” of WESTLAKE (1972, 1976), widely used and referred to in bioequivalence studies, are not confidence intervals in any accepted sense. Nevertheless, meaningful symmetric intervals can be constructed in the context of Bayesian or fiducial inference.
Tests of Special Structures on the Dispersion Matrix Associated with a Two‐Way Mixed Effects Model
Authors: Patel H. I. , Tsai K. T.
Published: May 2007

Exact and approximate methods are available in the literature to compare the fixed effect levels in an unbalanced two‐way mixed model under the conventional distributional assumptions for random effects. However, as suggested by SHEFFÉ (1959) the conventional assumptions may not be justified in practice. Recently, KHATRI and PATEL (1992) have studied a model with an unstructured dispersion matrix associated with the random effects of which the conventional model is a special model. In this note we give likelihood ratio tests for testing some special structures on the dispersion matrix.
Estimation of Vaccine Efficacy in Non‐Randomly Mixing Populations
Authors: Haber Michael , Halloran M. Elizabeth , Longini Ira M. , Watelet Luc
Published: May 2007

A deterministic model for the transmission of an acute infectious disease in a heterogeneous, nonrandomly mixing population is developed. This model facilitates the estimation of transmission probabilities from the observed attack rates. If some of the members of the population are vaccinated, then the vaccine efficacy (VE), defined as the relative reduction in the transmission probability due to vaccination, can be estimated. We provide several estimators of VE, depending on the amount of information available on the mixing pattern and on the action of the vaccine. We show that if vaccinated persons increase the frequency of their contacts with infectious persons, then estimators ignoring this change in behavior may substantially underestimate the VE.
Estimation of the Spirometric Residual Volume (RV) by a Regression Built from Gower Distances
Authors: Bartkowiak Anna , Liebhart Jerzy
Published: May 2007

We estimate the Residual Volume, a spirometric parameter, by use of four continuous and four categorical variables. The estimation is done using distance‐based regression, which allows to construct the predicting regression equation from mixed‐type explanatory variables. The additionally introduced categorical variables improve essentially the goodness of fit of the regression equation.
A Robust Test for Homoscedasticity in a Two‐Way Layout
Authors: Piepho Hans‐Peter
Published: May 2007

This paper discusses tests for homogeneity of row‐variances in a two‐way classification. Parametric tests for this problem are shown to be highly sensitive to departures from the normality assumption. Levene's robust tests tend to be rather liberal when the number of rows exceeds the number of columns. A modification is suggested which improves the approximation for this situation, while retaining the desirable robustness property.
On the PBB Designs for Multiresponse Experiments
Authors: Brzeskwiniewicz Henryk
Published: May 2007

We present the idea of using multiresponse incomplete block designs when not all responses can be observed in all experimental units. For a special class of such designs, in which partial designs are PBB designs, a method for estimating natural treatment contrast is given. We also consider the problem of testing the hypotheses concerning the natural and any estimable treatment contrasts. For testing this hypothesis the Wald statistics, being asymptotically chi‐square distributed, is proposed.
Further Study on the Statistical Test to Detect Spatial Pattern
Authors: Ping Sun
Published: May 2007

In the study of spatial patterns, the statistic I' = (n — 1)s2/x was commonly used. In this paper, we found that x — s2 has an approximated normal distribution with zero mean if the xi's (i = 1 to n) are independent identically distributed Poisson variables. Based on this conclusion, the hypothesis that a point pattern is completely random can be tested directly. And a method for the test of spatial patterns was proposed which can be sued as an alternative to the Chi‐square based dispersion index test.
A Genetic Basis Behind Combining Ability and Breeding Values in Mono‐ and Di‐genic Systems
Authors: Arunachalam V.
Published: May 2007

Combining ability and breeding values are concepts of crucial importance in practical breeding. However, in early literature, methods of partitioning the genetic value into additive and dominance effects were described mostly in single gene and under random mating. Though average effect and average excess of gene substitution were defined by Fisher and a practial method of obtaining breeding values outlined by Falconer, concerted attempts are scarce in integrating the concepts of combining ability, breeding value and additive effects. Only a few workers have reported the values of those parameters for inbred populations while published reports on those effects in digenic systems with linkage appear to be not readily available. Practical breeders continue to use those concepts as if they were independent. This paper is therefore an attempt at filling the research gaps and setting those concepts in proper practical perspective.
Gene Flow Technique for Stage‐Structured Populations
Authors: Muralidharan K. , Jain J. P.
Published: May 2007

The gene flow technique for predicting response to selection with overlapping generations is formulated in terms of demographic parameters for stage‐structured population and illustrated with a sequential selection scheme in dairy cows.
On a Continuous Branching Process and Birth‐Death and Immigration Models for Testing the Efficacy of Some Control Programmes for AIDS
Authors: Biswas Suddhendu , Thomas Mariamma
Published: May 2007

The present communication is an attempt to describe the mode of propagation of AIDS epidemic and its control programme using a branching process as well as a birth‐death and immigration model. A comparison of the project of AIDS control programme on the basis of its propagation by a continuous branching process model with that of a linear birth and death process with immigration shows a remarkable contrast. Branching process model shows that it is possible to control the propagation of the disease by suitably increasing the detection rate and lowering the infection rate. However, the propagation of AIDS models by birth and death Process with or without immigration shows that it is increasingly difficult to control the invasion of AIDS merely by controlling the birth, death and immigration parameters.
Size and Power of Test Statistics for Gene Correlation in 2 × 2 Contingency Tables
Authors: Mannan M. , Nassar R.
Published: May 2007

Monte Carlo simulation of size and power of two proposed tests for linkage disequilibrium between two genes each with two alleles were investigated. Results were compared with two commonly used statistics, the correlation coefficientrand the log‐odds ratio tests. Depending on the sign of the linkage disequilibrium, the new tests were found to be more powerful than either of the correlation or log‐odds ratio tests. However, on average (positive and negative linkage disequilibrium) the Chi‐square test using the correlation coefficient was to a small extent more powerful than the other tests.
Determination of Selection Gradients Using Multiple Regression versus Structural Equation Models (SEM)
Authors: Pugesek Bruce H. , Tomer Adrian
Published: May 2007

Selection studies involving multiple intercorrelated independent variables have employed multiple regression analysis as a means to estimate and partition natural and sexual selection's direct and indirect effects. These statistical models assume that independent variables are measured without error. Most would conclude that such is not the case in the field studies for which these methods are employed. We demonstrate that the distortion of estimates resulting from error variance is not trivial. When independent variables are intercorrelated, extreme distortions may occur. We propose to use Structural Equation Models (SEM), to estimate error variance and produce highly accurate coefficients for formulation of selection gradients. This method is particularly appropriate when the selection is viewed as happening at the level of the latent variables.
Fish Shape Analysis Using Landmarks
Authors: Glasbey C. A. , Horgan G. W. , Gibson G. J. , Hitchcock D.
Published: May 2007

Landmarks are used to summarize the shapes of ten haddock and nine whiting. Error variance models, after generalized Procrustes analysis, are compared using simulation tests. The power to discriminate between fish species is shown to be increased by permitting non‐affine transformations that correct for fish curvature.
Nested ANOVA for Repeated Surveys with Autocorrelated Errors
Authors: Prayag V. R. , Chiplonkar S. A. , Paranjpe S. A.
Published: May 2007

Diet surveys in the science of human nutrition involve longitudinal observations on the same individuals repeated at distinct time points. Consequently a common feature of such surveys is inherent correlation between successive observations. In this paper, an autoregressive model of order 1 is assumed for the successive observations on the same individual in a survey. Further, observations on the same individual in two different surveys are assumed to be correlated. The technique of analysis of variance is modified suitably for this set up and applied to two nutritional surveys carried on army recruits.
A Simple, Flexible Failure Model
Authors: Yu Shuiyang , Voit Eberhard O.
Published: May 2007

A new failure model is introduced in the form of a four‐parameter nonlinear differential equation, with failure probability as the dependent variable and failure time as the independent variable. The first parameter characterizes the location, the second the scale, and the other two the shape of the model. The type of the accompanying hazard function is immediately read off the shape parameters. The new model approximates the classical failure models with rather high precision, but also models cases where the failure density is skewed to the left. It can be used to analyze survival data objectively, based on the shape of the failure distribution. The computation of quantiles and moments is easy and fast. Nonlinear regression methods are used to estimate parameter values.
Accurate Confidence Intervals for the Ratio of Specific Occurrence/Exposure Rates in Risk and Survival Analysis
Authors: Tu Dongsheng , Gross Alan J.
Published: May 2007

Transformation and computer intensive methods such as the jackknife and bootstrap are applied to construct accurate confidence intervals for the ratio of specific occurrence/exposure rates, which are used to compare the mortality (or survival) experience of individuals in two study populations. Monte Carlo simulations are employed to compare the performances of the proposed confidence intervals when sample sizes are small or moderate.
Hidden Markov Models and Animal Behaviour
Authors: Macdonald Iain L. , Raubenheimer David
Published: May 2007

This paper proposes the use of hidden Markov time series models for the analysis of the behaviour sequences of one or more animals under observation. These models have advantages over the Markov chain models commonly used for behaviour sequences, as they can allow for time‐trend or expansion to several subjects without sacrificing parsimony. Furthermore, they provide an alternative to higher‐order Markov chain models if a first‐order Markov chain is unsatisfactory as a model. To illustrate the use of such models, we fit multivariate and univariate hidden Markov models allowing for time‐trend to data from an experiment investigating the effects of feeding on the locomotory behaviour of locusts (Locusta migratoria).
Maximum Likelihood Neural Network Prediction Models
Authors: Faraggi David , Simon Richard
Published: May 2007

Neural networks have received much attention in recent years mostly by non‐statisticians. The purpose of this paper is to incorporate neural networks in a non‐linear regression model and obtain maximum likelihood estimates of the network parameters using a standard Newton‐Raphson algorithm. We use maximum likelihood estimators instead of the usual back‐propagation technique and compare the neural network predictions with predictions of quadratic regression models and with non‐parametric nearest neighbor predictions. These comparisons are made using data generated from a variety of functions. Because of the number of parameters involved, neural network models can easily over‐fit the data, hence validation of results is crucial.
Estimation and Testing of Tumor Incidence Rates in Experiments Lacking Cause‐of‐Death Data
Authors: Ahn Hongshik , Kodell Ralph L.
Published: May 2007

Approximate nonparametric maximum likelihood estimation of the tumor incidence rate and comparison of tumor incidence rates between treatment groups are examined in the context of animal carcinogenicity experiments that have interval sacrifice data but lack cause‐of‐death information. The estimation procedure introduced by MALANI and VAN RYZIN (1988), which can result in a negative estimate of the tumor incidence rate, is modified by employing a numerical method to maximize the likelihood function iteratively, under the constraint that the tumor incidence rate is nonnegative. With the new procedure, estimates can be obtained even if sacrifices occur anywhere within an interval. The resulting estimates have reduced standard error and give more power to the test of two heterogeneous groups. Furthermore, a linear contrast of more than two groups can be tested using our procedure. The proposed estimation and testing methods are illustrated with an experimental data set.
Estimating Location Parameters Using Censored Rank Statistics
Authors: Öhman Marie‐Louise
Published: May 2007

In this paper censored data rank location estimators are obtained by using censored one‐sample rank test statistics of the location parameter and censored two‐sample rank test statistics of the shift of location parameter. Also, methods for constructing censored small sample confidence intervals and asymptotic confidence intervals for the location are considered. Generalizations of the solutions from uncensored one‐sample and two‐sample rank tests are utilized.
Normality Testing in a Mixed Model of a Two‐way Nested Classification
Authors: Wagner Wieslaw , Brzeskwiniewicz H.
Published: May 2007

The paper presents a testing procedure verifying the hypothesis about the normal distribution of random components in a mixed model of a two‐way nested classification. The basis for this application is a simple sample obtained from orthogonal and the O'Reilly‐Quesenberry transformation to the residual vector from the method of least squares (MLS).
Additive and Non‐additive Genetic Correlations. II. Application to Data Obtained from a 12 × 12 Diallel Cross
Authors: Hohls Trevor , Clarke G. P. Y. , Shanahan P. E. , Gevers H. O.
Published: May 2007

The proposed genetic correlation analysis, that involves the partitioning of the overall genetic correlation into an additive and a non‐additive component, has been applied to data obtained from a diallel experiment involving 12 white modified opaque‐2 maize inbred lines. The correlation analysis provided an insight into possible indirect selection strategies for the improvement of inferior kernel quality traits associated with the opaque‐2 gene. Direct selection for high yield and low vitreousness rating would provide an efficient selection strategy for the development of high‐yielding modified opaque‐2 maize hybrids with desirable endosperm traits. It was concluded that it is not necessary to conduct the density, hardness and breakability determinations.
A Conditional Test of Independence of Markov Chains
Authors: Solow Andrew R. , Smith W. K. , Recchia C.
Published: May 2007

This note describes a simple conditional test of the independence of two first‐order, two‐state Markov chains. The test is illustrated using some data from an experiment concerning animal behavior.
Analysis of a Generalized Linear Mixed Model: A Case Study and Simulation Results
Authors: Engel Bas , Buist Willem
Published: May 2007

A class of generalized linear mixed models can be obtained by introducing random effects in the linear predictor of a generalized linear model, e.g. a split plot model for binary data or count data. Maximum likelihood estimation, for normally distributed random effects, involves high‐dimensional numerical integration, with severe limitations on the number and structure of the additional random effects. An alternative estimation procedure based on an extension of the iterative re‐weighted least squares procedure for generalized linear models will be illustrated on a practical data set involving carcass classification of cattle. The data is analysed as overdispersed binomial proportions with fixed and random effects and associated components of variance on the logit scale. Estimates are obtained with standard software for normal data mixed models. Numerical restrictions pertain to the size of matrices to be inverted. This can be dealt with by absorption techniques familiar from e.g. mixed models in animal breeding. The final model fitted to the classification data includes four components of variance and a multiplicative overdispersion factor. Basically the estimation procedure is a combination of iterated least squares procedures and no full distributional assumptions are needed. A simulation study based on the classification data is presented. This includes a study of procedures for constructing confidence intervals and significance tests for fixed effects and components of variance. The simulation results increase confidence in the usefulness of the estimation procedure.
Generalized Linear Mixed‐Effects Models with a Finite‐Support Random‐Effects Distribution: A Maximum‐Penalized‐Likelihood Approach
Authors: Leung Moon K. , Elashoff Robert M.
Published: May 2007

We discuss a method for simultaneously estimating the fixed parameters of a generalized linear mixed‐effects model and the random‐effects distribution of which no parametric assumption is made. In addition, classifying subjects into clusters according to the random regression coefficients is a natural by‐product of the proposed method. An alternative approach to maximum‐likelihood method, maximum‐penalized‐likelihood method, is used to avoid estimating “too many” clusters. Consistency and asymptotic normality properties of the estimators are presented. We also provide robust variance estimators of the fixed parameters estimators which remain consistent even in presence of misspecification. The methodology is illustrated by an application to a weight loss study.
A Bayesian Estimator of the Optimum for a Single Factor Quadratic Response Model
Authors: Fan T. H. , Karson M. J. , Wang H. S.
Published: May 2007

Estimation of the location and magnitude of the optimum has long been considered an important problem in response surface methodology. In the industrial context, prior information accumulated by the subject matter specialist bears special significance. In this paper we use the Bayesian approach to estimating the optimum in a single factor quadratic regression model. Following the Bayesian general linear model development by Broemeling the normal/gamma conjugate prior is used. Explicit formulas for the generalized maximum likehood estimates of the characteristic parameters are obtained from the joint posterior distribution.
A Note on Testing Hypotheses about Trimmed Means
Authors: Wilcox Rand R.
Published: May 2007

A well known result is that skewness can cause problems when testing hypotheses about measures of location, particulary when a one‐sided test is of interest. Wilcox (1994) reports both theoretical and simulation results showing that when testing hypotheses about trimmed means, control over Type I error probabilities can be substantially better than methods for means. However, at least in some situations, control over the probability of a Type I error might still be judged to be inadequate. One way of adressing this concern is to combine trimmed means with the bootsrap method advocated by Westfall and Yuong (1993). This note reports simulation results indicating that there are situations where substantial improvements over Type I error probabilities are indeed obtained.