Evolutionary theories of aging: confirmation of a fundamental prediction, with implications for the genetic basis and evolution of life span.

Evolutionary considerations predict that rate of aging should vary in direct relation to the mortality rate of presenescent young adults (extrinsic mortality rate) independently of differences in physiology, such as rate of metabolism. This prediction emerges from theory irrespective of the particular genetic mechanisms responsible for variation in aging. Yet this critical relationship has not been confirmed in comparative studies of natural populations.

Evidence-based nursing practice: what US nurse executives really think.

This article by Darlene Sredl considers qualitative statements from US nurse executives about their belief in and implementation of evidence-based nursing practice. Their statements suggest uncertainty about the way forward.

Imaging cortical electrical stimulation in vivo: fast intrinsic optical signal versus voltage-sensitive dyes.

We applied high-temporal-resolution optical imaging utilizing both the fast intrinsic optical signal (fIOS) and voltage-sensitive dyes (VSDs) to observe the spatiotemporal characteristics of rat somatosensory cortex during electrical stimulation. We find that changes in both the fIOS and VSD signals occur rapidly (<30 ms) after the stimulus is applied, suggesting that both membrane depolarization and transmembrane ion movement occur shortly after the stimulus, preceding the more gradual physiological changes in oxygen consumption revealed by the slower component of the intrinsic optical signal. We find that the VSD signal spreads through a much larger area of cortex than the fIOS.

Patch exploitation in two dimensions: from Daphnia to simulated foragers.

We explore the variability that animals display in their movement choices as they forage in a finite-sized food patch with a uniform food distribution, and present a framework for how these choices may be adjusted to optimize foraging efficiency. Inspired by experimental studies of the zooplankton Daphnia, we model foraging animals as "agents" moving in two dimensions in repeated and successive sequences of hops, pauses, and turns. For Daphnia and other species, critical movement parameters such as hop lengths, pause times, and turning angles are typically reported as probability density functions.

Reporting to the police by Hispanic victims of violence.

Though reporting violence to the police has been extensively investigated, the nature of Hispanic reporting of victimization has not. This is surprising because Hispanics are the fastest growing and largest ethnic group in the United States. Using over a decade of data from the National Crime Victimization Survey, this article investigates Hispanic reporting of victimization relative to non-Hispanic Whites, Blacks, American Indians, and Asians.

Frustration, drift, and antiphase coupling in a neural array.

Synchronization among neurons is critical for many processes in the nervous system, ranging from the processing of sensory information to the onset of pathological conditions such as epilepsy. Here, we study synchronization in an array of neurons, each modeled by a set of nonlinear ordinary differential equations. We find that an array of 20x20 coupled neurons undergoes a series of alternating low and high synchronization states, as measured by phase-locking and frequency entrainment, as the coupling constant is tuned.

Transitions between multistable states as a model of epileptic seizure dynamics.

Epileptic seizures are generally considered to result from excess and synchronized neural activity. Additionally, changes in amplitude and frequency are often seen in local field potential or electroencephalogram recordings during a seizure event. To investigate how seizures initiate, and how dynamical changes occur during seizure progression, we develop a neocortical network model based on a model suggested by Wilson [J.

Optimal foraging by zooplankton within patches: the case of Daphnia.

The motions of many physical particles as well as living creatures are mediated by random influences or 'noise'. One might expect that over evolutionary time scales internal random processes found in living systems display characteristics that maximize fitness. Here we focus on animal random search strategies [G.

Overt and relational victimization among children with frequent abdominal pain: links to social skills, academic functioning, and health service use.

Objectives: Chronic abdominal pain is linked with school absenteeism and diminished social competence; yet, little is know about the extent to which negative peer encounters contribute to symptoms and functioning in youth with abdominal pain. This study compared children with frequent abdominal pain with a pain-free control group on measures of overt and relational victimization and examined the link between abdominal pain and school-related functioning.

Methods: Participants were 60 children with frequent abdominal pain and 60 gender- and age-matched peers.

Role of physical anthropology in intermediate and secondary education.

The role of physical anthropology in precollegiate education has been limited, but has the potential to play a vital and integral role in promoting students' understanding of themselves and others. This study describes the development, implementation, and results of a program constructed on an inquiry-based learning model that introduces middle and high school students to the content of physical anthropology. Demonstrated student learning indicates that intermediate and secondary students are capable of acquiring and applying complex content about human evolution and diversity.

Evolving U.S. service model for patients with severe mental illness and co-occurring substance use disorder.

Co-occurring severe mental illness and substance use disorder has been recognized as a common problem in the U.S. since the early 1980s (1-3).

Stochastic resonance and sensory information processing: a tutorial and review of application.

Objective: To review the stochastic resonance phenomena observed in sensory systems and to describe how a random process ('noise') added to a subthreshold stimulus can enhance sensory information processing and perception.

Results: Nonlinear systems need a threshold, subthreshold information bearing stimulus and 'noise' for stochastic resonance phenomena to occur. These three ingredients are ubiquitous in nature and man-made systems, which accounts for the observation of stochastic resonance in fields and conditions ranging from physics and engineering to biology and medicine.

Counting unstable periodic orbits in noisy chaotic systems: A scaling relation connecting experiment with theory.

The experimental detection of unstable periodic orbits in dynamical systems, especially those which yield short, noisy or nonstationary data sets, is a current topic of interest in many research areas. Unfortunately, for such data sets, only a few of the lowest order periods can be detected with quantifiable statistical accuracy. The primary observable is the number of encounters the general trajectory has with a particular orbit.

Increased phase synchronization of spontaneous calcium oscillations in epileptic human versus normal rat astrocyte cultures.

Stochastic synchronization analysis is applied to intracellular calcium oscillations in astrocyte cultures prepared from epileptic human temporal lobe. The same methods are applied to astrocyte cultures prepared from normal rat hippocampus. Our results indicate that phase-repulsive coupling in epileptic human astrocyte cultures is stronger, leading to an increased synchronization in epileptic human compared to normal rat astrocyte cultures.

Phase synchronization and stochastic resonance effects in the crayfish caudal photoreceptor.

We study the nonlinear response of the crayfish caudal photoreceptor to periodic mechanical stimuli in terms of stochastic synchronization. The amplitude and frequency of the mechanical stimuli and the light level are used as control parameters. The system shows multiple locking regions as the stimulus frequency is varied.

Synchronization of noisy systems by stochastic signals.

We study, in terms of synchronization, the nonlinear response of noisy bistable systems to a stochastic external signal, represented by Markovian dichotomic noise. We propose a general kinetic model which allows us to conduct a full analytical study of the nonlinear response, including the calculation of cross-correlation measures, the mean switching frequency, and synchronization regions. Theoretical results are compared with numerical simulations of a noisy overdamped bistable oscillator.

Surrogates for finding unstable periodic orbits in noisy data sets.

Recently, searches for unstable periodic orbits in biological and medical applications have become of interest. The motivations for this research range, in order of ascending complexity, from efforts to understand the dynamics of simple sensory neurons, through speculations regarding neural coding, to the hopeful development of new diagnostic and/or control techniques for cardiac and epileptic pathologies. Biological and medical data are, however, noisy and nonstationary.

Synchronization of noise-induced bursts in noncoupled sensory neurons.

We report experimental observation of phase synchronization in an array of nonidentical noncoupled noisy neuronal oscillators, due to stimulation with external noise. The synchronization derives from a noise-induced qualitative change in the firing pattern of single neurons, which changes from a quasiperiodic to a bursting mode. We show that at a certain noise intensity the onsets of bursts in different neurons become synchronized, even though the number of spikes inside the bursts may vary for different neurons.

Homology modeling of the estrogen receptor subtype beta (ER-beta) and calculation of ligand binding affinities.

Estrogen is a steroid hormone playing critical roles in physiological processes such as sexual differentiation and development, female and male reproductive processes, and bone health. Numerous natural and synthetic environmental compounds have been shown capable of estrogenic effects. This area has been the focus of significant fundamental and applied research due both to the potential detrimental effects of these compounds upon normal physiological processes and to the potential beneficial effects of tissue-selective estrogen agonists/antagonists for the prevention and treatment of numerous diseases.

Raynaud's phenomenon.

Many persons are affected by the phenomenon known as Raynaud's. Raynaud's is classified in 2 ways-as Raynaud's disease or Raynaud's syndrome. Classification is based on the presence of associated conditions.

Extracting dynamical structure from unstable periodic orbits.

The topological recurrence algorithm provides a fast and robust method for detecting the presence of unstable periodic orbits (UPO's) in short, noisy experimental data files. We present here a technique for improving this method by using a matrix fitting algorithm to extract dynamical information about the system from these UPO's. This method greatly increases the sensitivity of the algorithm, and also provides a method for identifying false positive results.

Stochastic biperiodic oscillations in the electroreceptors of paddlefish.

We report that the electroreceptors in paddlefish possess the novel property of being biperiodic, that is, being composed of two intrinsic self-sustained noisy oscillators, one residing in the hair cells, and another in the terminals of primary afferent neurons. The two oscillators are coupled unidirectionally. Thus the receptor system as a whole undergoes stochastic biperiodic oscillations.

Emotional support needs of gay males with AIDS.

Twenty-five gay and three bisexual males with AIDS (PWAs) rated their needs for four different kinds of emotional support (expressing love and concern, expressing encouragement and positive feedback, serving as a confidant, and providing a philosophical or spiritual perspective) from five different support providers (parents, partners, friends, HIV-positive friends and physicians). Findings support the importance of emotional support for this population. The results indicate that differences exist depending on type and provider of support.