Predicted SAR in Sprague-Dawley rat as a function of permittivity values

Specific absorption rate (SAR) value is dependent on permittivity value. However, variability in the published permittivity values for human and animal tissue and the development of sophisticated 3-dimensional digital anatomical models to predict SAR values has resulted in the need to understand how model parameters (permittivity value) affect the predicted whole body and localized SAR values. In this paper, we establish the partial derivative of whole body SARs and localized SAR values (defined as SAR for individual organs with respect to a change in the permittivity values of all tissue types, as well as for those tissues with the most variable permittivity values. Variations in the published permittivity values may substantially influence whole body and localized SAR values, but only under special conditions. Orientation of the exposed object to the incident electromagnetic wave is one of the most crucial factors. Published 2001 Wiley-Liss, Inc.     

The effects of the menstrual cycle, pregnancy and early lactation on haematology and plasma biochemistry in the baboon (Papio hamadryas)

The changes in the haematology and clinical biochemistry associated with the different stages of the menstrual cycle, gestation and lactation in the baboon (Papio hamadryas) were evaluated in a prospective longitudinal study. Serial EDTA and heparin blood samples were collected from 12 baboons. Haemoglobin concentration, haematorcrit, red blood cell and white blood cell counts were decreased in the luteal compared to the follicular phase (P<0.001); the reverse effect was observed for platelet count, total protein and albumin concentrations. The changes in plasma concentrations of sodium, potassium, urea, creatinine and cholesterol and plasma osmolality were characterized by reductions (P<0.01) in early pregnancy which were maintained throughout gestation. Plasma concentrations of total protein, albumin and alkaline phosphatase, as well as haemoglobin, haematocrit and red cell count were reduced (P<0.001) from mid-gestation. Platelet count and plasma calcium concentration fell continuously throughout gestation (P<0.001). Plasma triglycerides were lower and plasma iron was higher (P<0.01) in gestation compared to the phases of the menstrual cycle and lactation. By 1 week post partum, all parameters except haemaglobin had returned to pre-conception levels.     

Extreme value analysis in biometrics

We review some approaches of extreme value analysis in the context of biometrical applications. The classical extreme value analysis is based on iid random variables. Two different general methods are applied, which will be discussed together with biometrical examples. Different estimation, testing, goodness‐of‐fit procedures for applications are discussed. Furthermore, some non‐classical situations are considered where the data are possibly dependent, where a non‐stationary behavior is observed in the data or where the observations are not univariate. A few open problems are also stated.     

Genetic analysis of return over feed in Canadian Holsteins

The objective of this study was to investigate genetic merit of return over feed (ROF), which is a herd profit index defined by CanWest Dairy Herd Improvement as a difference between milk income and feed cost. A multiple-trait (MT) model and random regression model (RRM) were used. The traits analyzed in MT were rearing cost and ROF of the first three lactations. In RRM, a cumulative ROF was fitted as function of age and rearing cost was treated as a correlated trait. Variance components were estimated within a Bayesian framework by Gibbs sampling using a subsample of data. Breeding values were then estimated for 3 041 078 animals using records of 1 951 893 cows. Estimates of heritability for rearing cost from MT and RRM were 0.23 and 0.22, respectively. ROF per lactation and cumulative ROF were negatively correlated with rearing cost. Estimates of heritability of ROF through the first, second and third lactation from MT were 0.27, 0.10 and 0.08, respectively. Estimates of heritability of ROF from RRM increased with age and ranged from 0.08 through 0.31. Estimated breeding values (EBVs) for ROF from MT and RRM were moderately correlated with official EBV for production traits and the Canadian selection index (Lifetime Profit Index). Herd life EBV had -0.07 and 0.19 correlations with EBVs for ROF from MT and RRM, respectively. From both MT and RRM, small favorable correlations were reported between EBVs for ROF and for bone quality and angularity, whereas low unfavorable correlations were reported with EBV for udder depth, front end and chest width. Majority of correlations between EBVs for ROF and for reproduction traits were near 0, with the exception of EBV for gestation length, calf size and calving ease, where small favorable correlations were reported. The ROF is a good indicator of cow profitability despite the fact that it is a simplified profit index that does not account for animal-specific health and reproductive cost. However, because ROF does not account for differences in heritabilities between components of profit, ROF is not recommended to be used for direct selection for profit.     

Science and Values Influencing Predator Control for Alaska Moose Management

ABSTRACT We encourage informed and transparent decision-making processes concerning the recently expanded programs in Alaska, USA, to reduce predation on moose (Alces alces). The decision whether to implement predator control ultimately concerns what society should value; therefore, policymakers, not objective biologists, play a leadership role. From a management and scientific standpoint, biological support for these predator-control programs requires convincing evidence that 1) predators kill substantial numbers of moose that would otherwise mostly live and be available for harvest, 2) low predation can facilitate reliably higher harvests of moose, 3) given less predation, habitats can sustain more moose and be protected from too many moose, and 4) sustainable populations of Alaska's brown bears (Ursus arctos), black bears (Ursus americanus), and wolves (Canis lupus) will exist in and out of control areas. We reviewed 10 moose mortality studies, 36 case histories, 10 manipulative studies, 15 moose nutrition studies, and 3 recent successful uses of nutrition-based management to harvest excess female moose. Results of these studies support application of long-term, substantial predator control for increasing yield of moose in these simple systems where moose are a primary prey of 3 effective predators. We found no substantive, contradictory results in these systems. However, to identify and administer feasible moose population objectives, recently established moose nutritional indices must be monitored, and regulatory bodies must accept nutrition-based management. In addition, the efficacy of techniques to reduce bear predation requires further study. Predicting precise results of predator control on subsequent harvest of moose will continue to be problematic because of a diversity of changing interactions among biological, environmental, and practical factors. In Alaska, the governor has the prerogative to influence regulations on predator control by appointing members to the Board of Game. At least annually, the Board of Game hears a wide spectrum of public opinions opposing and favoring predator control. We summarized these opinions as well as the societal and cultural values and expectations that are often the primary basis for debates. Advocates on both sides of the debate suggest they hold the higher conservation ethic, and both sides provide biased science. We recommend a more constructive and credible dialogue that focuses openly on values rather than on biased science and fabricated conspiracies. To be credible and to add substance in this divisive political arena, biologists must be well informed and provide complete information in an unbiased and respectful manner without exaggeration.     

Evidence for size and sex-specific dispersal in a cooperatively breeding cichlid fish

African Great Lake cichlid populations are divided into thousands of genetic subpopulations. The low gene flow between these subpopulations is thought to result from high degrees of natal philopatry, heavy predation pressure, and a patchy distribution of preferred habitats. While predation pressure and habitat distribution are fairly straightforward to assess, data on dispersal distances and rates are scarce. In fishes, direct observations of dispersal events are unlikely, but dispersal can be studied using molecular markers. Using seven microsatellite loci, we examined dispersal in the cooperatively breeding cichlid fish, Neolamprologus pulcher. As this species is found in well-defined groups clustered into subpopulations, we could assess dispersal on a narrow (within subpopulation) and broad (between subpopulation) scale. While fish were generally more related to others in their own subpopulation than they were to fish from other subpopulations, large males diverged from this pattern. Large males were more related to other large males from different subpopulations than they were to large males from their own subpopulation, suggesting more frequent dispersal by large males. Across subpopulations, relatedness between large males was higher than the relatedness among large females; this pattern was not detected in small males and small females. Within a subpopulation, individuals appeared to be preferentially moving away from relatives, and movement was unrestricted by the physical distance between groups. Our results highlight the importance of examining multiple spatial scales when studying individual dispersal biases.     

Erythropoietin in Cerebrospinal Fluid: Age-related Reference Values and Relevance in Neurological Disease

We aimed to establish age-related reference values for Erythropoietin (EPO) in cerebrospinal fluid (CSF) and to evaluate concentrations in neurological diseases. CSF and serum EPO was measured in controls with tension-type headache (CTTH), in patients with ALS, dementia and depression using ELISA technique. Stability experiments showed CSF EPO to be stable for two and a half months and over two thaw/freeze cycles. A positive correlation of CSF EPO with age was found (P < 0.01). We found a CSF/serum EPO concentration ratio of 0.126, pointing towards an intrathecal synthesis of EPO. The ALS group showed significantly lowered CSF EPO compared to age-matched CTTH (P < 0.012), whereas the dementia and depression group showed no significant differences compared to CTTH. The establishment of age-related reference values in a large cohort of controls will improve the interpretation of future CSF EPO evaluations in neurological diseases. The authors have not reported any conflicts of interest.     

Caloric restrictions affect some factors involved in age-related hypercholesterolemia

Ageing has been defined as a progressive decrease in physiological capacity and a reduced ability to respond to environmental stresses. It has been observed that diet-restricted animals show a minor morbidity in age-related disease. Among these age-related diseases, hypercholesterolemia is the most recurring one and it is often associated with cardiac failure. Several studies have been published indicating age-dependent changes in circulating levels of cholesterol in both humans and in rodents; recently changes have also been reported in the proteins involved in cholesterol homeostasis, that is, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoAR), Insig-induced gene (Insig) protein, SREBP cleavage activating protein (SCAP), sterol regulatory element binding protein (SREBP), and low density lipoprotein receptor (LDLr). Most age-related modifications of biochemical parameters are normalized or very improved in food-restricted animals, so the aim of this work is to examine whether or not alterations of the factors involved in cholesterol homeostasis which occur during ageing could be counteracted by caloric restriction (CR). The data show that the diet restrictions used attenuate the age-related effects on the factors involved in the synthesis and the degradation rate of HMG-CoAR; in spite of this, CRs have a good effect on the age-related hypercholesterolemia whose reduction seems to depend both on the correct membrane LDLr localization and on the proper restored HMG-CoAR activity.     

Vertebrate aging research 2006

This Hot Topics review, the first in a projected annual series, discusses those articles, published in the last year, which seem likely to have a major impact on our understanding of the aging process in mammals and the links between aging and late-life illnesses. The year's highlights include studies of oxidation damage in the very-long-lived naked mole-rat, and of caloric restriction in monkeys, humans, and growth hormone-unresponsive mice. Two studies of resveratrol, one showing its ability to extend lifespan in a short-lived fish, the other demonstrating beneficial effects in mice subjected to a diet high in fat, may well be harbingers of a parade of intervention studies in the coming decade.