bluuebunny/crossref_metadata_2025 huggingface dataset:
Applying sample survey methods to clinical trials data
Authors: LaVange L. M. , Koch G. G. , Schwartz T. A.
Published: August 2002

This paper outlines the utility of statistical methods for sample surveys in analysing clinical trials data. Sample survey statisticians face a variety of complex data analysis issues deriving from the use of multi‐stage probability sampling from finite populations. One such issue is that of clustering of observations at the various stages of sampling. Survey data analysis approaches developed to accommodate clustering in the sample design have more general application to clinical studies in which repeated measures structures are encountered. Situations where these methods are of interest include multi‐visit studies where responses are observed at two or more time points for each patient, multi‐period cross‐over studies, and epidemiological studies for repeated occurrences of adverse events or illnesses. We describe statistical procedures for fitting multiple regression models to sample survey data that are more effective for repeated measures studies with complicated data structures than the more traditional approaches of multivariate repeated measures analysis. In this setting, one can specify a primary sampling unit within which repeated measures have intraclass correlation. This intraclass correlation is taken into account by sample survey regression methods through robust estimates of the standard errors of the regression coefficients. Regression estimates are obtained from model fitting estimation equations which ignore the correlation structure of the data (that is, computing procedures which assume that all observational units are independent or are from simple random samples). The analytic approach is straightforward to apply with logistic models for dichotomous data, proportional odds models for ordinal data, and linear models for continuously scaled data, and results are interpretable in terms of population average parameters. Through the features summarized here, the sample survey regression methods have many similarities to the broader family of methods based on generalized estimating equations (GEE). Sample survey methods for the analysis of time‐to‐event data have more recently been developed and implemented in the context of finite probability sampling. Given the importance of survival endpoints in late phase studies for drug development, these methods have clear utility in the area of clinical trials data analysis. A brief overview of methods for sample survey data analysis is first provided, followed by motivation for applying these methods to clinical trials data. Examples drawn from three clinical studies are provided to illustrate survey methods for logistic regression, proportional odds regression and proportional hazards regression. Potential problems with the proposed methods and ways of addressing them are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Order‐restricted dose‐related trend tests
Authors: Mancuso Jessica Y. , Ahn Hongshik , Chen James J.
Published: August 2002

Methods of isotonic regression are proposed to increase the power of common trend tests in situations where a monotonicity constraint is imposed upon the dose‐response function. Isotonic versions of Cochran–Armitage type trend tests for binary response data are developed, and the bootstrap method is used in finding the empirical distributions of the test statistics and their critical values. The isotonic likelihood ratio test with a survival adjustment is also proposed. This survival adjustment can be applied to the likelihood ratio test for either the order‐restricted or unrestricted parameter cases. To achieve the isotonic modifications, an amalgamation algorithm is applied when the observed dose‐response is non‐monotonic. A Monte Carlo simulation study comparing these trend tests shows the advantages of the isotonic modifications and survival adjustment. By applying the proposed methods to data from a toxicology and carcinogenesis study conducted as part of the National Toxicology Program, the effect of CI Pigment Red 23 is investigated. Copyright © 2001 John Wiley & Sons, Ltd.
Meta‐analysis of continuous outcome data from individual patients
Authors: Higgins Julian P. T. , Whitehead Anne , Turner Rebecca M. , Omar Rumana Z. , Thompson Simon G.
Published: August 2002

Meta‐analyses using individual patient data are becoming increasingly common and have several advantages over meta‐analyses of summary statistics. We explore the use of multilevel or hierarchical models for the meta‐analysis of continuous individual patient outcome data from clinical trials. A general framework is developed which encompasses traditional meta‐analysis, as well as meta‐regression and the inclusion of patient‐level covariates for investigation of heterogeneity. Unexplained variation in treatment differences between trials is considered as random. We focus on models with fixed trial effects, although an extension to a random effect for trial is described. The methods are illustrated on an example in Alzheimer's disease in a classical framework using SAS PROC MIXED and MLwiN, and in a Bayesian framework using BUGS. Relative merits of the three software packages for such meta‐analyses are discussed, as are the assessment of model assumptions and extensions to incorporate more than two treatments. Copyright © 2001 John Wiley & Sons, Ltd.
Effects of psychosocial stress or food restriction on body mass and blood cellular immunity in laboratory rats
Authors: Stefanski Volker
Published: August 2002

Immunological changes were studied in socially stressed loser rats and in rats restricted of food or water. Seven days of chronic social confrontation resulted in a significant loss of body mass as well as in marked alterations of blood cellular immunity in loser rats. Loser males showed increased numbers of granulocytes, reduced numbers of CD4 T cells, CD8 T cells, and B cells, as well as a lowered proliferative response of lymphocytes to concanavalin A. To test the possibility of whether the immunological change in loser males is a direct effect of altered nutritional state, non‐confronted males were restricted of food (−90 per cent) for 7 days to mimic the weight loss of loser males. While losers and food restricted males lost a similar 15 per cent of their initial body mass, their immunological outcome largely differed: food or water restriction had little immunological impact, except on granulocytes (reduced numbers). Obviously, social stress alters granulocyte numbers in a different direction than under food or water restriction. Together the data indicate that modulation of blood cellular immunity in loser males is unlikely to be caused by altered nutritional state during socially stressful confrontations. Copyright © 2001 John Wiley & Sons, Ltd.
The evolution of firm networks: from emergence to early growth of the firm
Authors: Hite Julie M. , Hesterly William S.
Published: August 2002

This paper addresses whether cohesive networks of socially embedded ties or sparse networks rich in structural holes are more conducive to the success of new firms. We propose that the networks of emerging firms evolve in order to adapt to the firm's changing resource needs and resource challenges. As firms emerge, their networks consist primarily of socially embedded ties drawn from dense, cohesive sets of connections. We label these networks identity based. As firms move into the early growth stage, their networks evolve toward more ties based on a calculation of economic costs and benefits. This shift from identity‐based to more calculative networks is manifested in the evolution of the firm networks: (1) from primarily socially embedded ties to a balance of embedded and arm's‐length relations; (2) from networks that emphasize cohesion to those that exploit structural holes; and (3) from a more path‐dependent to a more intentionally managed network. Thus, this paper suggests that both cohesive and sparse networks are conducive to firm performance when they are aligned with and address firms' evolving resource challenges. Copyright © 2001 John Wiley & Sons, Ltd.
Technological acquisitions and the innovation performance of acquiring firms: a longitudinal study
Authors: Ahuja Gautam , Katila Riitta
Published: August 2002

This paper examines the impact of acquisitions on the subsequent innovation performance of acquiring firms in the chemicals industry. We distinguish between technological acquisitions, acquisitions in which technology is a component of the acquired firm's assets, and nontechnological acquisitions: acquisitions that do not involve a technological component. We develop a framework relating acquisitions to firm innovation performance and develop a set of measures for quantifying the technological inputs a firm obtains through acquisitions. We find that within technological acquisitions absolute size of the acquired knowledge base enhances innovation performance, while relative size of the acquired knowledge base reduces innovation output. The relatedness of acquired and acquiring knowledge bases has a nonlinear impact on innovation output. Nontechnological acquisitions do not have a significant effect on subsequent innovation output. Copyright © 2001 John Wiley & Sons, Ltd.
Guanxi and organizational dynamics: organizational networking in Chinese firms
Authors: Park Seung Ho , Luo Yadong
Published: August 2002

This paper focuses on the utilization of guanxi, which is an important cultural and social element in China, and the impact of guanxi on firm performance. Although guanxi is embedded in every aspect of Chinese social life, companies demonstrate different needs and capacity for guanxi cultivation. Chinese firms develop guanxi as a strategic mechanism to overcome competitive and resource disadvantages by cooperating and exchanging favors with competitive forces and government authorities. We develop an integrative framework theorizing guanxi utilization according to institutional, strategic, and organizational factors, and we explore the impact of guanxi on firm performance, primarily sales growth and net profit growth. Our findings, based on a survey of 128 firms in central China, provide strong support that institutional, strategic, and organizational factors are critical determinants of guanxi with competitive forces. However, only institutional and strategic factors are significant for guanxi utilization with government authorities. In general, guanxi leads to higher firm performance, but is limited to increased sales growth, and has little impact on profit growth. Guanxi benefits market expansion and competitive positioning of firms, but does not enhance internal operations. Copyright © 2001 John Wiley & Sons, Ltd.
How much does the business group matter in Korea?
Authors: Chang Sea Jin , Hong Jaebum
Published: August 2002

We partition the variances of profits of the companies associated with Korean business groups into business group‐specific effects, industry effects, and affiliate company‐specific effects, which roughly match corporate‐parent effects, industry effects and business unit effects, respectively, in the extant literature. We find substantial corporate‐parent effects (here, business group effects) along with industry effects and business unit effects (here, affiliate company‐specific effects). This finding may indicate that business groups play an important role in developing countries by circumventing market inefficiencies. Our results also suggest that these effects tend to be smaller in large business groups and to decrease over time. Copyright © 2002 John Wiley & Sons, Ltd.
The implications of strategy and social context for the relationship between top management team heterogeneity and firm performance
Authors: Carpenter Mason A.
Published: August 2002

This research reexamines the link between top management team (TMT) heterogeneity and firm performance. Specifically, I theorize that the effects of education, work experience, and tenure on performance will depend upon the top management team's strategic and social context. In a test of such theorizing, I find that (1) the positive relationships between TMT educational, functional, and tenure heterogeneity and performance are contingent on complexity, as indicated by a firm's international strategy and, (2) such relationships are clearly stronger in short‐tenured top management teams. The theory and results presented here provide impetus for future studies, as well as suggest to upper echelon researchers that they think more critically about the conditions under which demographic characteristics are most likely to influence organizational outcomes like performance. Copyright © 2002 John Wiley & Sons, Ltd.
Top management team compensation: the missing link between CEO pay and firm performance?
Authors: Carpenter Mason A. , Sanders WM. Gerard
Published: August 2002

In this research we discuss the relationship between CEO and top management team (TMT) member compensation, and explore the implications of TMT pay for firm performance. Specifically, we suggest that firm performance may benefit due to agency and group behavioral issues when top management team member pay is aligned—alignment is defined as the degree to which TMT member pay reflects (1) shareholder interests and (2) key political and strategic contingencies within the firm. In support of our theorizing, we found CEO pay to be related to TMT pay; TMT compensation, in turn, predicted performance (i.e., return on assets and Tobin's q) when aligned with shareholder interests and internal contingencies. Moreover, the effect of CEO pay on future firm performance was dependent on top team pay. Copyright © 2002 John Wiley & Sons, Ltd.
An enhanced thread synchronization mechanism for Java
Authors: Chiao Hsin‐Ta , Yuan Shyan‐Ming
Published: August 2002

The thread synchronization mechanism of Java is derived from Hoare's monitor concept. In the authors' view, however, it is over simplified and suffers the following four drawbacks. First, it belongs to a category of no‐priority monitor, the design of which, as reported in the literature on concurrent programming, is not well rated. Second, it offers only one condition queue. Where more than one long‐term synchronization event is required, this restriction both degrades performance and further complicates the ordering problems that a no‐priority monitor presents. Third, it lacks the support for building more elaborate scheduling programs. Fourth, during nested monitor invocations, deadlock may occur. In this paper, we first analyze these drawbacks in depth before proceeding to present our own proposal, which is a new monitor‐based thread synchronization mechanism that we term EMonitor. This mechanism is implemented solely by Java, thus avoiding the need for any modification to the underlying Java Virtual Machine. A preprocessor is employed to translate the EMonitor syntax into the pure Java codes that invoke the EMonitor class libraries. We conclude with a comparison of the performance of the two monitors and allow the experimental results to demonstrate that, in most cases, replacing the Java version with the EMonitor version for developing concurrent Java objects is perfectly feasible. Copyright © 2001 John Wiley & Sons, Ltd.
Voices of Asian American Students
Authors: Lagdameo Angela , Lee Sophia , Nguyen Bao , Liang Christopher T. H. , Lee Sunny , Maekawa Kodama Corinne , McEwen Marylu K.
Published: August 2002

Three college students share their experiences as Asian Americans in college and offer suggestions for improvement in campus programs and services.
(R)‐N‐[11C]methyl‐3‐pyrrolidyl benzilate, a high‐affinity reversible radioligand for PET studies of the muscarinic acetylcholine receptor
Authors: Skaddan Marc B. , Jewett Doug M. , Sherman Phil S. , Kilbourn Michael R.
Published: August 2002

We recently reported the synthesis and binding affinity of ligands for the muscarinic acetylcholine receptor (mAChR) based on both the pyrrolidyl and piperidyl benzilate scaffold. One of these, (R)‐3‐pyrrolidyl benzilate, was successfully radiolabeled with [11C]methyl triflate and the resulting compound, (R)‐N‐[11C]methyl‐3‐pyrrolidyl benzilate (3‐[11C]NMPYB), was evaluated as a reversible, acetylcholine‐sensitive tracer for the mAChR (Ki of unlabeled 3‐NMPYB is 0.72 nM). This compound displayed high, receptor‐mediated retention in regions of the mouse and rat brain known to have high concentrations of mAChRs. Moreover, bolus studies in a pigtail monkey showed that this compound had superior clearance from the brain when compared to muscarinic radiotracers previously employed in human PET studies. Infusion studies in the same monkey revealed that it was possible to achieve equilibrium of radiotracer distribution for 3‐[11C]NMPYB in both the striatum and cortex. Sensitivity to endogenous acetylcholine levels was evaluated by injecting phenserine (5 mg/kg) into rats prior to administration of 3‐[11C]NMPYB in an equilibrium infusion protocol. This pretreatment produced a modest, statistically significant decrease (9–11%) in the distribution volume ratios for muscarinic receptor rich regions of the rat brain as compared to controls. Synapse 45:31–37, 2002. © 2002 Wiley‐Liss, Inc.
Nurturing scholarship through holistic faculty development: A synergistic approach
Authors: Zahorski Kenneth J.
Published: August 2002

Institution‐wide cultures of hope and opportunity help encourage, nurture, and support scholarship. This chapter identifies the prerequisites for creating such an environment, discusses the intrainstitutional partnerships that promote scholarship, and lists some of the benefits accruing from the resulting gestalt.
Estrogenic effect of leachates and soil extracts from lysimeters spiked with sewage sludge and reference endocrine disrupters
Authors: Dizer Halim , Fischer Birgit , Sepulveda Isabel , Loffredo Elisabetta , Senesi Nicola , Santana Fernando , Hansen Peter‐D.
Published: August 2002

Several experiments were conducted to evaluate the behavior and performance of some potential endocrine disrupters (ECDs). Two in vitro screening assays, one based on MCF7‐cell proliferation (E‐screen test) and the other on estrogenic receptor activity [enzyme‐linked receptor assay (ELRA)], were used for the tests, which were done in lysimeters 80 cm in diameter with depths of 30 cm (shallow) or 90 cm (deep). A sandy soil was used to fill in all lysimeters, which were spiked on the surface with either: (a) a sewage sludge (SS) at a dose equivalent to 20 tons ha−1; (b) a mixture of reference ECDs, comprising 17α‐ and 17β‐estradiol (E2), nonylphenol, octylphenol, and bisphenol A at doses 100 times higher than the maximum concentrations respectively found in the applied SS; or (c) a mixture of ECDs and SS. After percolation of the lysimeters with rain and/or artificial water, five leachates were sampled from each lysimeter during a period of 210 days. Immediately after the lysimeter percolation experiments, four and six soil fractions were dissected from, respectively, the 30‐cm and 90‐cm lysimeters and extracted by water. Both the leachate and soil extract samples were analyzed for their estrogenicity using the assays indicated above. The E‐screen assay was highly sensitive only for some leachate and extract samples but gave no response for most leachates and soil extracts. The results of the ELRA assay suggests a significantly higher estrogenicity of leachate samples from shallow lysimeters compared with that of leachates from deep lysimeters. In contrast, the estrogenic effect measured for soil extracts of shallow lysimeters was lower than that measured for soil extracts of deep lysimeters. The results of the E‐screen assay suggests the occurrence of a fast mobilization of applied ECDs and a moderate retardation effect of native ECDs contained in applied SS in the sandy soil used in the lysimeters. In lysimeters spiked with a mixture of SS and ECDs, the washing‐out effect of ECDs in the first leachate fraction decreased, but the distribution of ECDs in the lysimeters increased. The relatively high estrogenic impact measured for soil water extracts suggests that the ECDs were mostly associated with water‐soluble fractions of organic matter and/or water‐suspended fractions of the mineral soil matrix. The application of SS to agricultural and forest fields may determine the immobilization of ECDs in soil or their movement to surface and/or groundwater. Therefore, an endocrine risk of exposure exists for the water and soil organisms. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 105–112, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10038
Evaluation of the genotoxic potential of municipal waste water discharged into the Paraguay River during periods of flood and drought
Authors: Serra de Lima Moraes Danielle , Jordão Berenice Quinzani
Published: August 2002

The cytogenotoxic effects of the waste water from Corumbá and of the water of the Paraguay River, where this sewer discharges, were evaluated in flood and drought seasons. Allium cepa root meristems were exposed to 20 and 72 h treatments. Mitotic index, frequency, and types of aberrant cells were compared to the control. The waste water was genotoxic to this organism. The cycle of flood and drought influenced the levels of genotoxicity observed with the river water. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 113–116, 2001
Cauchy–Schwarz bound on the generalized Marcum Q‐function with applications
Authors: Annamalai A. , Tellambura C.
Published: August 2002

The Cauchy–Schwarz bounding technique is used to derive useful bounds on the generalized Marcum Q‐function and its complement. Three new exponential‐type bounds on QM (α, β) are derived, and these are found to be tight and useful for a number of applications of interest. One such example is the derivation of an upper bound on the average symbol error rate probability for noncoherent and differentially coherent communication systems over generalized fading channels. It is shown that these exponential‐type bounds are considerably tighter than the Chernoff bound (Rappaport SS. IEEE Trans. on Information Theory 1971; 17: 497–498) counterpart. Numerical results also reveal that the tightness of one of the exponential‐type bounds is comparable to the bound obtained in Simon and Alouini (IEEE Trans. on Communications 2000: 359–366), while another is found to be superior than that obtained in Simon and Alouini over a wide range of arguments. Copyright © 2001 John Wiley & Sons, Ltd.
Effect of Placing a Diffuser around a Wind Turbine
Authors: Hansen M. O. L. , Sørensen N. N. , Flay R. G. J.
Published: August 2002

An actuator disc CFD model of the flow through a wind turbine in a diffuser is developed and validated. Further, it is shown theoretically from a 1D analysis that the Betz limit can be exceeded by a factor proportional to the relative increase in mass flow through the rotor induced by the diffuser. The theoretical 1D result is verified by the CFD model. Copyright © 2000 John Wiley & Sons, Ltd.
In situlocalization of β‐glucans in the cell wall ofSchizosaccharomyces pombe
Authors: Humbel Bruno M. , Konomi Mami , Takagi Tomoko , Kamasawa Naomi , Ishijima Sanae A. , Osumi Masako
Published: August 2002

The chemical composition of the cell wall ofSz. pombeis known as β‐1,3‐glucan, β‐1,6‐glucan, α‐1,3‐glucan and α‐galactomannan; however, the three‐dimensional interactions of those macromolecules have not yet been clarified. Transmission electron microscopy reveals a three‐layered structure: the outer layer is electron‐dense, the adjacent layer is less dense, and the third layer bordering the cell membrane is dense. In intact cells ofSz. pombe, the high‐resolution scanning electron microscope reveals a surface completely filled with α‐galactomannan particles. To better understand the organization of the cell wall and to complement our previous studies, we set out to locate the three different types of β‐glucan by immuno‐electron microscopy. Our results suggest that the less dense layer of the cell wall contains mainly β‐1,6‐branched β‐1,3‐glucan. Occasionally a line of gold particles can be seen, labelling fine filaments radiating from the cell membrane to the α‐galactomannan layer, suggesting that some of the radial filaments contain β‐1,6‐branched β‐1,3‐glucan. β‐1,6‐glucan is preferentially located underneath the α‐galactomannan layer. Linear β‐1,3‐glucan is exclusively located in the primary septum of dividing cells. β‐1,6‐glucan only labels the secondary septum and does not co‐localize with linear β‐1,3‐glucan, while β‐1,6‐branched β‐1,3‐glucan is present in both septa. Linear β‐1,3‐glucan is present from early stages of septum formation and persists until the septum is completely formed; then just before cell division the label disappears. From these results we suggest that linear β‐1,3‐glucan is involved in septum formation and perhaps the separation of the two daughter cells. In addition, we frequently found β‐1,6‐glucan label on the Golgi apparatus, on small vesicles and underneath the cell membrane. These results give fresh evidence for the hypothesis that β‐1,6‐glucan is synthesized in the endoplasmic reticulum–Golgi system and exported to the cell membrane. Copyright © 2001 John Wiley & Sons, Ltd.
Cloning and characterization of a LON gene homologue from the human pathogen Paracoccidioides brasiliensis
Authors: Barros Tânia F. , Puccia Rosana
Published: August 2002

A LON gene homologue from the human pathogen Paracoccidioides brasiliensis (PbLON) has been cloned, sequenced and characterized. It encodes a putative ATP‐dependent proteinase Lon, which in Saccharomyces cerevisisae (PIM1) is a heat‐inducible protein involved in the degradation of abnormal or short‐lived proteins in the mitochondria. The PbLON ORF is within a 3369 bp fragment interrupted by two introns located in the 3′segment. The 5′ and 3′ regions flanking the ORF contain sequences which resemble known transcription elements. Several transcription binding factor motifs have also been found, including sites for heat shock/stress response and nitrogen control. The deduced protein consists of 1063 residues containing a mitochondrial import signal at the N‐terminus and conserved ATP‐binding (GPPGVGKT) and serine catalytic (KDGPSAG) sites. It shares high identity with Lon homologues from S. cerevisiae (73%), Homo sapiens (62%) and Escherichia coli (56%). In P. brasiliensis, an MDJ1 putative gene has also been partially sequenced adjacent to PbLON, possibly sharing divergently orientated promoter elements. This chromosomal organization is interesting, since Mdj1p is a heat shock chaperone essential for substrate degradation by PIM1 in yeast. The LON nucleotide andflanking sequence regions have been submitted to GenBank under Accession No. AF239178. Copyright © 2001 John Wiley & Sons, Ltd.
The putative monocarboxylate permeases of the yeast Saccharomyces cerevisiae do not transport monocarboxylic acids across the plasma membrane
Authors: Makuc Judita , Paiva Sandra , Schauen Matthias , Krämer Reinhard , André Bruno , Casal Margarida , Leão Cecília , Boles Eckhard
Published: August 2002

We have characterized the monocarboxylate permease family of Saccharomyces cerevisiae comprising five proteins. We could not find any evidence that the monocarboxylate transporter‐homologous (Mch) proteins of S. cerevisiae are involved in the uptake or secretion of monocarboxylates such as lactate, pyruvate or acetate across the plasma membrane. A yeast mutant strain deleted for all five MCH genes exhibited no growth defects on monocarboxylic acids as the sole carbon and energy sources. Moreover, the uptake and secretion rates of monocarboxylic acids were indistinguishable from the wild‐type strain. Additional deletion of the JEN1 lactate transporter gene completely blocked uptake of lactate and pyruvate. However, uptake of acetate was not even affected after the additional deletion of the gene YHL008c, which had been proposed to code for an acetate transporter. The mch1–5 mutant strain showed strongly reduced biomass yields in aerobic glucose‐limited chemostat cultures, pointing to the involvement of Mch transporters in mitochondrial metabolism. Indeed, intracellular localization studies indicated that at least some of the Mch proteins reside in intracellular membranes. However, pyruvate uptake into isolated mitochondria was not affected in the mch1–5 mutant strain. It is concluded that the yeast monocarboxylate transporter‐homologous proteins perform other functions than do their mammalian counterparts. Copyright © 2001 John Wiley & Sons, Ltd.
Patterns of excretion of fecal estradiol and progesterone and urinary chorionic gonadotropin in Grevy’s zebras (Equus grevyi): Ovulatory cycles and pregnancy
Authors: Asa C.S. , Bauman J.E. , Houston E.W. , Fischer M.T. , Read B. , Brownfield C.M. , Roser J.F.
Published: August 2002

The ovulatory cycle and pregnancy of the endangered Grevy’s zebra (Equus grevyi) was characterized by analyzing excretion patterns of fecal estradiol and progesterone. Pregnancy was further described by assay of urinary equine chorionic gonadotropin. Courtship and mating behavior were similar to that seen in the domestic horse, but cycle length was longer, ranging from 28 to 35 days. Steroid hormone profiles during pregnancy were likewise similar to the horse, but gestation length was longer (391 and 406 days) in the two mature mares. A young mare was first seen to mate when 1 year 3 months of age, at which time she conceived but then aborted at 101 days’ gestation. Conception occurred after one and possibly two more abortions. A healthy foal was born after a gestation period of 425 days, when the mare was 3 years 4 months old, the youngest age at first foaling to be reported for this species. Equine chorionic gonadotropin (eCG) was first detected between 35 and 40 days’ gestation, as in the horse, returning to baseline at about 195 days. However, in one young mare, eCG was also detectable around the time of ovulation. The eCG antibody may have cross‐reacted with luteinizing hormone, which would have been reaching peak concentrations at about that time. The general agreement of the endocrine results with observed occurrence of mating behavior and of parturition demonstrates that assay of excreted hormones can be used to document puberty, monitor ovarian cycles, and diagnose and monitor pregnancy in Grevy’s zebra mares. Zoo Biol 20:185–195, 2001. © 2001 Wiley‐Liss, Inc.
Grooming, kinship, and co‐feeding in captive spider monkeys (Ateles geoffroyi)
Authors: Pastor‐Nieto Rosalía
Published: August 2002

Allo‐grooming is perhaps the most powerful affiliative behavior observed in non‐human primates. However, the functional significance of grooming in New World monkeys has not yet been fully understood, perhaps because grooming is less frequently observed in platyrrhines. To differentiate the potential role of affiliative investment and/or kinship on sharing access to food (co‐feeding) in spider monkeys, behavioral data on grooming, embracing, and feeding were collected from two different groups of captive study subjects: a familiar/kin group and a non‐familiar/non‐kin group. The results of this study suggest that family‐related spider monkeys that engage in grooming tend to share access to food resources more than unfamiliar conspecifics that do not groom. One explanation for this difference is that the unfamiliar study subjects had not yet invested in the affiliative social network, were not reciprocating their affiliative investments and hence, had a higher tendency toward single animal monopolizing resources. Degree of relatedness alone was not found to be a determinant for sharing the access to food, suggesting that familiarity in spider monkeys is based on the extent to which animals invest in affiliative relationships. In this study, only animals that had engaged in long‐term grooming and recognized each other as familiar shared the access to food. Therefore, it might be likely that in spider monkeys, long‐term grooming of high intensity has to be developed for co‐feeding to occur. Zoo Biol 20:293–303, 2001. © 2001 Wiley‐Liss, Inc.
On foliated circle bundles over closed orientable 3-manifolds
Authors: Miyoshi Shigeaki
Published: August 2002

We show that there exists a family of smooth orientable circle bundles over closed orientable 3-manifolds each of which has a codimension-one foliation transverse to the fibres of class C0 but has none of class C3. There arises a necessary condition induced from the Milnor-Wood inequality for the existence of a foliation transverse to the fibres of an orientable circle bundle over a closed orientable 3-manifold. We show that with some exceptions this necessary condition is also sufficient for the existence of a smooth transverse foliation if the base space is a closed Seifert fibred manifold.
On the deleted product criterion for embeddability of manifolds in $ \Bbb {R}^m $
Authors: Skopenkov A.
Published: August 2002

For a space N let

\tilde N = \{(x,y) \in N \times N|x \neq y \}

. Let

\Bbb {Z}_2

act on Ñ and on

S^{m-1}

by exchanging factors and antipodes, respectively. For an embedding

f : N \to \Bbb {R}^m

define the map

\tilde f : \tilde N \to S^{m-1}

by

\tilde f(x,y) = {fx-fy \over|fx-fy|}

.¶Theorem. Let

d = 3n - 2m + 2

and N be a closed PL n-manifold.¶a) If

d \in \{0,1,2 \}

, N is d-connected and there exists an equivariant map

F : \tilde N \to S^{m-1}

, then N is PL-embeddable in

\Bbb {R}^m

.¶b) If

d \in \{-1,0,1\}

,

m-n \ge 3

, N is (d + 1)-connected and

f, g : N \to \Bbb {R}^m

are PL-embeddings such that

\tilde f,\tilde g

are equivariantly homotopic, then f, g are PL-isotopic.¶Corollary. a) Every closed 6-manifold N such that H1(N) = 0 PL embeds in

\Bbb {R}^{10}

;¶b) Every closed PL 2-connected 7-manifold PL embeds in

\Bbb {R}^{11}

;¶c) There are exactly four PL embeddings

S^{2l+1} \times S^{2l+1} \subset \Bbb {R}^{6l+4}

up to PL isotopy (l > 0).
Continuously many quasiisometry classes of 2-generator groups
Authors: Bowditch Brian H.
Published: August 2002

We construct continuously many quasiisometry classes of torsion-free 2-generator small cancellation groups.
Dérivée des petites valeurs propres des surfaces de Riemann
Authors: Batchelor Ph.
Published: August 2002

On estime la dérivée des petites valeurs propres du Laplacien sur une famille de surfaces de Riemann. Ces valeurs propres sont considérées comme des fonctions sur l'espace de Teichmüller, et l'estimation des dérivées peut s'exprimer dans ce contexte.
The representation ring of a compact Lie group revisited
Authors: Oliver Robert
Published: August 2002

We describe a new construction of the induction homomorphism for representation rings of compact Lie groups: a homomorphism first defined by Graeme Segal. The idea is to first define the induction homomorphism for class functions, and then show that this map sends characters to characters. This requires a detection theorem - a class function of G is a character if its restrictions to certain subgroups of G are characters - which in turn requires a review of the representation theory for nonconnected compact Lie groups.
Regularity properties of H-graphs
Authors: Finn Robert , Lu J.
Published: August 2002

It is proved that if H(u) is non-decreasing and if

H (-\infty) \neq H (+\infty)

, then if u (x) describes a graph over a disk BR (0), with (upward oriented) mean curvature H(u), there is a bound on the gradient

| Du(0) |

that depends only on R, on u (0), and on the particular function H (u). As a consequence a form of Harnack's inequality is obtained, in which no positivity hypothesis appears. The results are qualitatively best possible, in the senses a) that they are false if H is constant, and b) the dependences indicated are essential. The demonstrations are based on an existence theorem for a nonlinear boundary problem with singular data, which is of independent interest.
Stable constant mean curvature hypersurfaces in some Riemannian manifolds
Authors: Montiel S.
Published: August 2002

We determine all stable constant mean curvature hypersurfaces in a wide class of complete Riemannian manifolds having a foliation whose leaves are umbilical hypersurfaces. Among the consequences of this analysis we obtain all the stable constant mean curvature hypersurfaces in many nonsimply connected hyperbolic space forms.
Milnor link invariants and quantum 3-manifold invariants
Authors: Habegger N. , Orr Kent E.
Published: August 2002

Let

{\cal Z}(M)

be the 3-manifold invariant of Le, Murakami and Ohtsuki. We show that

{\cal Z}(M) = 1 + o(n)

, where

o(n)

denotes terms of degree

\geq n

, if M is a homology 3-sphere obtained from

S^3

by surgery on an n-component Brunnian link whose Milnor

\overline\mu

-invariants of length

\leq 2n

vanish. We prove a realization theorem which is a partial converse to the above theorem.¶Using the Milnor filtration on links, we define a new bifiltration on the

\Bbb Q

vector space with basis the set of oriented diffeomorphism classes of homology 3-spheres. This includes the Milnor level 2 filtration defined by Ohtsuki. We show that the Milnor level 2 and level 3 filtrations coincide after reindexing.
Combinatorial volume preserving flows and taut foliations
Authors: Gabai D.
Published: August 2002

A

\pi_1

-injective closed surface in an orientable 3-manifold with a tangentially smooth, transversely C0 taut foliation can be homotoped to an immersed surface which is either transverse to the foliation except at isolated saddle tangencies or mapped into a leaf.
Strong approximation for Zariski dense subgroups over arbitrary global fields
Authors: Pink Richard
Published: August 2002

Consider a finitely generated Zariski dense subgroup

\Gamma

of a connected simple algebraic group G over a global field F. An important aspect of strong approximation is the question of whether the closure of

\Gamma

in the group of points of G with coefficients in a ring of partial adeles is open. We prove an essentially optimal result in this direction, based on the condition that

\Gamma

is not discrete in that ambient group. There are no restrictions on the characteristic of F or the type of G, and simultaneous approximation in finitely many algebraic groups is also studied. Classification of finite simple groups is not used.
Symplectic invariants of elliptic fixed points
Authors: Siburg K. F.
Published: August 2002

To the germ of an area-preserving diffeomorphism at an elliptic fixed point, we associate the germ of Mather's minimal action. This yields a strictly convex function which is symplectically invariant and comprises the classical Birkhoff invariants as the Taylor coefficients of its convex conjugate. In addition, however, the minimal action contains information about the local dynamics near the fixed point; for instance, it detects the

C^0

-integrability of the diffeomorphism. Applied to the Reeb flow, this leads to new period spectrum invariants for three-dimensional contact manifolds; a particular case is the geodesic flow on a two-dimensional Riemannian manifold, where the period spectrum is the classical length spectrum.
Sharp Retrenchment, Modulated Refinement and Simulation
Authors: Banach R. , Poppleton M.
Published: August 2002

Sharp retrenchment is introduced and brie y justified informally, as a liberalisation of refinement. In sharp retrenchment the relationship between an abstract operation and its concrete counterpart is mediated by extra predicates, allowing most particularly the description of non-refinement-like properties, and the mixing of I/O and state aspects in the passage between levels of abstraction. Sharp retrenchments are brie y contrasted with unsharp ones. Sharp retrenchments are shown to have a natural law of composition, and the way in which refinements may be viewed as sharp retrenchments is discussed. Modulated refinement is introduced as a version of refinement allowing mixing of I/O and state aspects, in order to facilitate comparison between sharp retrenchment and refinement, and various notions of simulation are considered in this context, specifically: stepwise simulation, the ability of simulator to mimic a sequence of execution steps of the simulatee; strong simulation, in which states and step labels are mapped independently between simulatee and simulator; and the refinement notion itself. Special cases of sharp retrenchment are shown to possess various subsets of these simulation properties, and the extent to which sharp retrenchments contain refinements within them is addressed. The details of the theory are worked out for the B-Method, though the applicability of the underlying ideas is not limited to just that formalism.
Effects of open versus closed kinetic chain training on knee laxity in the early period after anterior cruciate ligament reconstruction
Authors: Morrissey Matthew C. , Hudson Zoe L. , Drechsler Wendy I. , Csoutts Fiona J. , Knight Philippa R. , King John B.
Published: August 2002

Knee extensor resistance training using open kinetic chain (OKC) exercise for patients recovering from anterior cruciate ligament reconstruction (ACLR) surgery has lost favour mainly because of research indicating that OKC exercise causes greater ACL strain than closed kinetic chain (CKC) exercise. In this prospective, randomized clinical trial the effects of these two regimes on knee laxity were compared in the early period after ACLR surgery. Thirty‐six patients recovering from ACLR surgery (29 males, 7 females; age mean=30) were tested at 2 and 6 weeks after ACLR with knee laxity measured using the Knee Signature System arthrometer. Between tests subjects trained using either OKC or CKC resistance of their knee and hip extensors in formal physical therapy sessions three times per week. Following adjustment for site of treatment, pretraining injured knee laxity, and untreated knee laxity at post‐training, the use of OKC exercise, when compared to CKC exercise, was found to lead to a 9% increase in looseness with a 95% confidence interval of –8% to +29%. These results indicate that the great concern about the safety of OKC knee extensor training in the early period after ACLR surgery may not be well founded.
Feasibility of Sentinel Lymph Node Biopsy and Lymphatic Mapping in Nodular Thyroid Neoplasms
Authors: Dixon Elijah , McKinnon J. Gregory , Pasieka Janice L.
Published: August 2002

Although the prognostic significance of occult lymph node metastases in thyroid cancer remains controversial, identifying these patients may help direct therapy. The purpose of this study was to determine the feasibility and safety of sentinel lymph node biopsy (SLNBx) in thyroid nodular disease. Patients undergoing thyroid resection, with no evidence of clinical lymphadenopathy, were enrolled. The nodule was injected with isosulfan blue vital dye. Blue‐stained lymphatic channels were traced within the central compartment to the SLN, which was excised. A total of 40 patients underwent SLNBx; lymphatics were seen in 31 patients, and SLNs were found in 26. In 11 patients the lymphatic vessels were traced through the central compartment into the lateral or mediastinal compartments, although a central SLN was retrieved in only 6. Of the 18 patients with benign neoplasms, 14 had benign SLNs, and no SLN was found in 4. A thyroid lymphoma patient had a true positive SLN. In the 12 patients with papillary thyroid cancer (PTC), 6 had true positive SLNs, and 2 had a true negative SLN. In one patient with metastatic PTC, the parathyroid stained blue. Another patient with PTC had lateral lymphatic channels, but no SLN was found. There were two false negatives, proven by a node dissection in one and lateral uptake on 131I scanning in the other. There were no postoperative complications. SLNBx for thyroid disease is feasible and safe. Potential staining of the parathyroids makes their identification before injection mandatory. The variable lymphatic drainage patterns and the two false‐negative nodes indicate that further investigation is required before the procedure can be recommended for patients with thyroid disease.
What Is Appropriate Treatment for Carcinoma of the Thoracic Esophagus?
Authors: Law Simon , Wong John
Published: August 2002

Recent advances in the treatment of esophageal cancer have yielded a variety of new options for management of this highly lethal disease. Various approaches to surgical resection have been proposed. Chemotherapy and radiotherapy with or without surgery have been tested in numerous trials, the results of which are often conflicting and confusing for clinicians. The changing epidemiology of the disease between East and West adds to the controversy. In this review, the authors address some of the more controversial debates. The following questions are asked: What is the appropriate approach for surgical resection? What is the appropriate extent of resection? Is multimodality treatment appropriate for esophageal cancer?
Lung Transplantation versus Lung Volume Reduction as Surgical Therapy for Emphysema
Authors: Meyers Bryan F. , Patterson G. Alexander
Published: August 2002

There are currently two surgical therapies aimed at crippling, end‐stage emphysema: lung transplantation and lung volume reduction surgery (LVRS). Unfortunately, most emphysema patients are poor candidates for any surgical intervention. The authors favor a meticulous selection process in which indications and contraindications are considered and the best solution is devised for each patient. Patients with ideal circumstances for LVRS—hyperinflation, heterogeneous distribution of disease, FEV1 of more than 20%, and normal PCO2—are offered LVRS. Patients with diffuse disease, low FEV1, hypercapnia, and associated pulmonary hypertension are directed toward transplantation. LVRS has not been a satisfactory option for patients with a1‐antitrypsin deficiency, and we prefer a transplant in most of these patients. With these considerations, we find that few patients are serious candidates for both procedures. Combinations of lung volume reduction and lung transplantation, simultaneously or sequentially, are possible but rarely necessary.
Hypercoagulability following Multiple Trauma
Authors: Engelman Daniel T. , Gabram Sheryl G.A. , Allen Lisa , Ens Gordon E. , Jacobs Lenworth M.
Published: August 2002

We sought evidence of hypercoagulability in 59 seriously injured trauma patients. An extended coagulation profile (consisting of tissue plasminogen activator antigen concentration, plasminogen activator inhibitor, serum antithrombin III, protein C antigen, functional protein C, protein S antigen, D‐dimer, and prothrombin fragment 1.2) was compared to control values. Laboratory evidence of hypercoagulability was seen in 85% (n= 50) of the patients. Patients with an Injury Severity Score (ISS) ≥ 16 (n= 36) had significantly elevated levels of D‐dimer and decreased levels of functional protein C compared to patients with an ISS ≤ 15 (n= 23). Functional protein C had a negative correlation (r=−0.44;p< 0.001) with the ISS. A hypercoagulable state exists immediately following severe trauma. Greater injury severity may increase this hypercoagulable state. Decreased levels of functional protein C best correlated with increased injury severity.
Major Vessel Resection during Limb‐Preserving Surgery for Soft Tissue Sarcomas
Authors: Karakousis Constantine P. , Karmpaliotis Constantine , Driscoll Deborah L.
Published: August 2002

There is uncertainty in the literature as to whether major vessel involvement in extremity soft tissue sarcomas constitutes an indication for amputation. This retrospective review includes 21 patients who underwent major vessel resection in the context of limb preservation for soft tissue sarcomas. Resected vessels were the common iliac in one, external iliac and common femoral in six, common and superficial femoral in five, superficial femoral in six, distal superficial and popliteal in two, and subclavian vessels in one. Wound infection occurred postoperatively in five patients (24%). One Gore‐tex and one vein graft became exposed, but the wounds healed by secondary intention with routine wound care. Three patients (14%) manifested local recurrence, of which one required an amputation. The estimated 5‐year survival rate is 63%. Involvement of major vessel(s) by soft tissue sarcomas of the extremities is not in itself an indication for amputation, as with en bloc resection of major vessels the local recurrence and 5‐year survival rates parallel those of patients with soft tissue sarcomas not requiring major vessel resection.