Balancing Act: An Interdisciplinary Exploration of Trade-offs in Reproducing Females.

Trade-offs resulting from the high demand of offspring production are a central focus of many subdisciplines within the field of biology. Yet, despite the historical and current interest on this topic, large gaps in our understanding of whole-organism trade-offs that occur in reproducing individuals remain, particularly as it relates to the nuances associated with female reproduction. This volume of Integrative and Comparative Biology (ICB) contains a series of papers that focus on reviewing trade-offs from the female-centered perspective of biology (i.

Seasonal patterns of body temperature in response to experimental photoperiod variation in a non-hibernating ground squirrel.

Unlike numerous other members of the holarctic Tribe Marmotini of the squirrel family (Sciuridae) that typically exhibit spontaneous bouts of torpor that progress into an annual season of hibernation, members of the genus Ammospermophilus (antelope ground squirrels) do not enter torpor, and they remain active throughout the year in nature. We have experimentally evaluated seasonal patterns of variation in the circadian rhythm of body temperature in captive A. leucurus over a two-and-a-half-year period by exposing groups to either a constant daily photoperiod of 12 h light or a seasonally changing photoperiod that cycled between a summer maximum of 16 h per day and a winter minimum of 8 h; ambient air temperature was maintained at 26 °C.

Exploring the association between quality of homecare services and older adults' well-being.

Homecare services play an important role in enabling older adults with chronic illness or functional impairment to continue living in their homes and communities. Previous research on homecare services has not fully explored the potential psychological benefits of homecare services. This study investigates the association between quality of homecare services and psychological well-being by analyzing two surveys.

Exploring determinants of behavioral chronotype in a diurnal-rodent model of human physiology.

Numerous studies conducted with human participants have shown that differences in chronotype, defined as individual patterns of early or late beginning of daily activity, have implications for many biobehavioral processes, such as cognitive performance, mood, impulsivity, academic achievement of college students, and mental health. However, the determinants of individual variation in chronotype have not been investigated. Basic research on circadian rhythms has provided a basis for investigating the causes of chronotype variation, but experimental tests of pertinent hypotheses are difficult to conduct with human subjects.

Diurnally active rodents for laboratory research.

Although inbred domesticated strains of rats and mice serve as traditional mammalian animal models in biomedical research, the nocturnal habits of these rodents make them inappropriate for research that requires a model with human-like diurnal activity rhythms. We conducted a literature review and recorded locomotor activity data from four rodent species that are generally considered to be diurnally active, the Mongolian gerbil ( Meriones unguiculatus), the degu ( Octodon degus), the African (Nile) grass rat ( Arvicanthis niloticus), and the antelope ground squirrel ( Ammospermophilus leucurus). Our data collected under 12-hour light/dark cycles confirmed and expanded the existing literature in showing that the activity rhythms of antelope ground squirrels and African grass rats are stronger and more concentrated in the light phase of the light/dark cycle than the activity rhythms of Mongolian gerbils and degus, making the former two species preferable and more reliable as models of consistent diurnal activity in the laboratory.

Circadian rhythms of body temperature and locomotor activity in the antelope ground squirrel, Ammospermophilus leucurus.

We studied circadian rhythms of body temperature and locomotor activity in antelope ground squirrels (Ammospermophilus leucurus) under laboratory conditions of a 12L:12D light-dark cycle and in constant darkness. Antelope ground squirrels are diurnally active and, exceptionally among ground squirrels and other closely related members of the squirrel family in general, they do not hibernate. Daily oscillations in body temperature consisted of a rise in temperature during the daytime activity phase of the circadian cycle and a decrease in temperature during the nighttime rest phase.

Diversification and gene flow in nascent lineages of island and mainland North American tree squirrels (Tamiasciurus).

Pleistocene climate cycles and glaciations had profound impacts on taxon diversification in the Boreal Forest Biome. Using population genetic analyses with multilocus data, we examined diversification, isolation, and hybridization in two sibling species of tree squirrels (Tamiasciurus douglasii and Tamiasciurus hudsonicus) with special attention to the geographically and genetically enigmatic population of T. hudsonicus on Vancouver Island, Canada.

Summit on medical school education in sexual health: report of an expert consultation.

INTRODUCTION.: Medical education in sexual health in the United States and Canada is lacking. Medical students and practicing physicians report being underprepared to adequately address their patients' sexual health needs.

Thermoregulatory changes anticipate hibernation onset by 45 days: data from free-living arctic ground squirrels.

Hibernation is a strategy of reducing energy expenditure, body temperature (T(b)) and activity used by endotherms to escape unpredictable or seasonally reduced food availability. Despite extensive research on thermoregulatory adjustments during hibernation, less is known about transitions in thermoregulatory state, particularly under natural conditions. Laboratory studies on hibernating ground squirrels have demonstrated that thermoregulatory adjustments may occur over short intervals when animals undergo several brief, preliminary torpor bouts prior to entering multiday torpor.

Population delimitation across contrasting evolutionary clines in deer mice (Peromyscus maniculatus).

Despite current interest in population genetics, a concrete definition of a "population" remains elusive. Multiple ecologically and evolutionarily based definitions of population are in current use, which focus, respectively, on demographic and genetic interactions. Accurate population delimitation is crucial for not only evolutionary and ecological population biology, but also for conservation of threatened populations.

Genetic and phenotypic variation across a hybrid zone between ecologically divergent tree squirrels (Tamiasciurus).

A hybrid zone along an environmental gradient should contain a clinal pattern of genetic and phenotypic variation. This occurs because divergent selection in the two parental habitats is typically strong enough to overcome the homogenizing effects of gene flow across the environmental transition. We studied hybridization between two parapatric tree squirrels (Tamiasciurus spp.

Guiding principles for physician reentry programs.

Physician reentry is defined by the American Medical Association (AMA) as: "A return to clinical practice in the discipline in which one has been trained or certified following an extended period of clinical inactivity not resulting from discipline or impairment." Physician reentry programs are creating an avenue for physicians who have left medicine in good standing to return to clinical practice. To date, however, programs have developed independently, with little coordination among them.

Phenological variation in annual timing of hibernation and breeding in nearby populations of Arctic ground squirrels.

Ecologists need an empirical understanding of physiological and behavioural adjustments that animals can make in response to seasonal and long-term variations in environmental conditions. Because many species experience trade-offs between timing and duration of one seasonal event versus another and because interacting species may also shift phenologies at different rates, it is possible that, in aggregate, phenological shifts could result in mismatches that disrupt ecological communities. We investigated the timing of seasonal events over 14 years in two Arctic ground squirrel populations living 20 km apart in Northern Alaska.

The full-time clinical faculty: what goes around, comes around.

In his 1910 report entitled Medical Education in the United States and Canada, Abraham Flexner advanced an ideal model of medical education that included a university-based, full-time, salaried faculty whose time was devoted to teaching and research. This article traces the evolution of the "full-time" concept for clinical faculty and describes factors that have affected its implementation. Between 1910 and the 1930s, the full-time system for clinical faculty was implemented at a limited number of medical schools, but lack of financing made the system generally unworkable.

Nuclear and mitochondrial DNA reveal contrasting evolutionary processes in populations of deer mice (Peromyscus maniculatus).

We investigated a major geographic break in mitochondrial DNA (mtDNA) haplotypes in deer mice, Peromyscus maniculatus, by analysing spatial variation in a 491-bp fragment of the mtDNA control region from 455 samples distributed across a north-south transect of 2000 km in Western North America. To determine whether the mtDNA break was reflected in the nuclear genome, we then compared spatial variation in 13 nuclear microsatellites of 95 individuals surrounding the mtDNA break. Using a canonical correlation analysis we found that nuclear genomic variation was not correlated with mtDNA differentiation.

Seasonal glucocorticoid responses to capture in wild free-living mammals.

We determined baseline and capture-induced glucocorticoid concentrations during two different seasons in three species of wild free-living rodents: brown lemmings (Lemmus trimucronatus), golden-mantled ground squirrels (Spermophilus saturatus), and yellow-pine chipmunks (Tamias amoenus). Initial blood samples were obtained within 3 min of capture, so that initial glucocorticoid levels reflect baseline titers of undisturbed animals. Animals were held for an additional 30 min, when a second blood sample was taken to measure stress-induced glucocorticoid titers.

Photoperiod affects daily torpor and tissue fatty acid composition in deer mice.

Photoperiod and dietary lipids both influence thermal physiology and the pattern of torpor of heterothermic mammals. The aim of the present study was to test the hypothesis that photoperiod-induced physiological changes are linked to differences in tissue fatty acid composition of deer mice, Peromyscus maniculatus ( approximately 18-g body mass). Deer mice were acclimated for >8 weeks to one of three photoperiods (LD, light/dark): LD 8:16 (short photoperiod), LD 12:12 (equinox photoperiod), and LD 16:8 (long photoperiod).

The risk less known: female-to-male transgender persons' vulnerability to HIV infection.

Studies have consistently found high levels of HIV infection among male-to-female (MTF) transgender people, particularly MTF sex workers. Due to lack of empirical data, HIV/AIDS risk among female-to-male (FTM) transgender people, however, is not well understood. This study analysed data from two needs assessment surveys to compare risk for HIV infection between 122 MTF and 62 FTM transgender people.

Genetic structure of desert ground squirrels over a 20-degree-latitude transect from Oregon through the Baja California peninsula.

The genetic structure of populations over a wide geographical area should reflect the demographic and evolutionary processes that have shaped a species across its range. We examined the population genetic structure of antelope ground squirrels (Ammospermophilus leucurus) across the complex of North American deserts from the Great Basin of Oregon to the cape region of the Baja California peninsula. We sampled 73 individuals from 13 major localities over this 2500-km transect, from 43 to 22 degrees north.

Cost of living in free-ranging degus (Octodon degus): seasonal dynamics of energy expenditure.

Animals process and allocate energy at different seasons at variable rates, depending on their breeding season and changes in environmental conditions and resulting physiological demands. Overall total energy expenditure, in turn, should either increase in some seasons due to special added demands (e.g.

Service utilization, service barriers, and gender among HIV-positive consumers in primary care.

Title I of the Ryan White CARE Act provides emergency assistance to localities disproportionately affected by HIV and AIDS. In 1999, the Title I Chicago Area HIV Services Planning Council expressed concern regarding the lack of a client-level database. In response to the Planning Council, evaluators conducted a longitudinal interview study of HIV-positive individuals who were receiving primary care at Title I funded clinics within Chicago and the surrounding collar counties.

Historical demography and genetic structure of sister species: deermice (Peromyscus) in the North American temperate rain forest.

To investigate the evolutionary and biogeographical history of Peromyscus keeni and P. maniculatus within the coastal forest ecosystem of the Pacific Northwest of North America, we sampled 128 individuals from 43 localities from southeastern Alaska through Oregon. We analysed mitochondrial DNA variation using DNA sequence data from the mitochondrial cytochrome-b (cyt-b) gene and control region, and we found two distinct clades consistent with the morphological designation of the two species.

Milk composition of free-living yellow-pine chipmunks (Tamias amoenus): temporal variation during lactation.

Milk is the sole food source of mammals during early postnatal development, and its composition may be modified to meet changing nutritional and energetic demands from birth to weaning. These demands are especially acute in small mammals that breed in highly seasonal environments. We investigated the temporal course of milk composition during lactation in free-living yellow-pine chipmunks, Tamias amoenus, a small altricial omnivorous rodent that produces a single annual litter immediately after emerging from hibernation.