Fluctuation-dissipation relations in driven dissipative systems

Exact theoretical results for the violation of time dependent fluctuation-dissipation relations in driven dissipative systems are presented. The ratio of correlation to delayed response in the stochastic model introduced in [Phys. Rev. Lett. 93, 240601 (2004)] is shown to depend on measurement time. The fluctuation temperature defined by this ratio differs both from the temperature of the environment performing the driving, and from other effective temperatures of the system, such as the average energy (or "granular temperature"). General explanations are given for the time independence of fluctuation temperature for simple measurements or long measurement times.Comment: Author name changed; Clarifications made (mostly in introduction); References adde

Comment on ``Conduction states in oxide perovskites: Three manifestations of Ti3+^{3 +} Jahn-Teller polarons in barium titanate''

In this comment to [S. Lenjer, O. F. Schirmer, H. Hesse, and Th. W. Kool, Phys. Rev. B {\bf 66}, 165106 (2002)] we discuss the electronic structure of oxygen vacancies in perovskites. First principles computations are in favour of rather deep levels in these vacancies, and Lenjer et al suggest that the electrons' interaction energy is negative, but data on electroconductivity are against.Comment: 2 pages, no figure

Quantitative Evaluation of 5-Hydroxytryptamine (Serotonin) Neuronal Release and Uptake: An Investigation of Extrasynaptic Transmission

Whether neurotransmitters are restricted to the synaptic cleft (participating only in hard-wired neurotransmission) or diffuse to remote receptor sites (participating in what has been termed volume or paracrine transmission) depends on a number of factors. These include (1) the location of release sites with respect to the receptors, (2) the number of molecules released, (3) the diffusional rate away from the release site, determined by both the geometry near the release site as well as binding interactions, and (4) the removal of transmitter by the relevant transporter. Fast-scan cyclic voltammetry allows for the detection of extrasynaptic concentrations of many biogenic amines, permitting direct access to many of these parameters. In this study the hypothesis that 5-hydroxytryptamine (5-HT) transmission is primarily extrasynaptic in the substantia nigra reticulata, a terminal region with identified synaptic contacts, and the dorsal raphe nucleus, a somatodendritic region with rare synaptic incidence, was tested in brain slices prepared from the rat. Using carbon fiber microelectrodes, we found the concentration of 5-HT released per stimulus pulse in both regions to be identical when elicited by single pulse stimulations or trains at high frequency. 5-HT efflux elicited by a single stimulus pulse was unaffected by uptake inhibition or receptor antagonism. Thus, synaptic efflux is not restricted by binding to intrasynaptic receptors or transporters. The number of 5-HT molecules released per terminal was estimated in the substantia nigra reticulata and was considerably less than the number of 5-HT transporter and receptor sites, reinforcing the hypothesis that these sites are extrasynaptic. Furthermore, the detected extrasynaptic concentrations closely match the affinity for the predominant 5-HT receptor in each region. Although they do not disprove the existence of classical synaptic transmission, our results support the existence of paracrine neurotransmission in both serotonergic regions

Direct Observation of a Fractional Charge

We performed measurements of Quantum Shot Noise in order to determine the quasiparticle charge in the Fractional Quantum Hall regime. The noise is generated by a current flow through a partially transmitting Quantum Point Contact in a 2DEG. The noise is directly proportional to the charge of the quasiparticles, thus allowing direct determination of the charge. We measured Quantum Shot Noise at a filling factor of 1/3 and found that the charge is e/3; as predicted by Laughlin.Comment: 3 pages, PostScript, 4 figures. Submitted to Natur

Receptors and Other Signaling Proteins Required for Serotonin Control of Locomotion in Caenorhabditis elegans

A better understanding of the molecular mechanisms of signaling by the neurotransmitter serotonin is required to assess the hypothesis that defects in serotonin signaling underlie depression in humans. Caenorhabditis elegans uses serotonin as a neurotransmitter to regulate locomotion, providing a genetic system to analyze serotonin signaling. From large-scale genetic screens we identified 36 mutants of C. elegans in which serotonin fails to have its normal effect of slowing locomotion, and we molecularly identified eight genes affected by 19 of the mutations. Two of the genes encode the serotonin-gated ion channel MOD-1 and the G-protein-coupled serotonin receptor SER-4. mod-1 is expressed in the neurons and muscles that directly control locomotion, while ser-4 is expressed in an almost entirely non-overlapping set of sensory and interneurons. The cells expressing the two receptors are largely not direct postsynaptic targets of serotonergic neurons. We analyzed animals lacking or overexpressing the receptors in various combinations using several assays for serotonin response. We found that the two receptors act in parallel to affect locomotion. Our results show that serotonin functions as an extrasynaptic signal that independently activates multiple receptors at a distance from its release sites and identify at least six additional proteins that appear to act with serotonin receptors to mediate serotonin response.National Institutes of Health (U.S.) (Grant GM24663

Practices for Protecting and Enhancing Fish and Wildlife on Coal Mined Land in the Uinta-Southwestern Utah Region

This handbook contains information on the best current practices to minimize disturbances and adverse impacts of surface mining on fish and wildlife resources. Current state and federal legislation was reviewed to determine those practices which were most compatible with the best technology currently available, fish and wildlife plans, and reclamation plans for the Uinta-Southwestern region of the U.S. The information presented includes risks, limitations, approximate costs, and maintenance and management requirements of each practice. Plans for the restoration of specific habitats, according to the best current practices, are also included

Well-being at a Military Medical School and Implications for Military Retention.

INTRODUCTION: Physical and psychological well-being play a critical role in the academic and professional development of medical students and can alter the trajectory of a student\u27s quality of personal and professional life. Military medical students, given their dual role as officer and student, experience unique stressors and issues that may play a role in their future intentions to continue military service, as well as practice medicine. As such, this study explores well-being across the 4 years of medical school at Uniformed Services University (USU) and how well-being relates to a student\u27s likelihood to continue serving in the military and practicing medicine. METHODS: In September 2019, 678 USU medical students were invited to complete a survey consisting of three sections-the Medical Student Well-being Index (MSWBI), a single-item burnout measure, and six questions regarding their likelihood of staying in the military and medical practice. Survey responses were analyzed using descriptive statistics, analysis of variance (ANOVA), and contingency table analysis. Additionally, thematic analysis was conducted on open-ended responses included as part of the likelihood questions. RESULTS: Our MSWBI and burnout scores suggest that the overall state of well-being among medical students at USU is comparable to other studies of the medical student population. ANOVA revealed class differences among the four cohorts, highlighted by improved well-being scores as students transitioned from clerkships to their fourth-year curriculum. Fewer clinical students (MS3s and MS4s), compared to pre-clerkship students, indicated a desire to stay in the military. In contrast, a higher percentage of clinical students seemed to reconsider their medical career choice compared to their pre-clerkship student counterparts. Medicine-oriented likelihood questions were associated with four unique MSWBI items, whereas military-oriented likelihood questions were associated with one unique MSWBI item. CONCLUSION: The present study found that the overall state of well-being in USU medical students is satisfactory, but opportunities for improvement exist. Medical student well-being seemed to have a stronger association with medicine-oriented likelihood items than with military-oriented likelihood items. To obtain and refine best practices for strengthening engagement and commitment, future research should examine if and how military and medical contexts converge and diverge throughout training. This may enhance the medical school and training experience and, ultimately, reinforce, or strengthen, the desire and commitment to practice and serve in military medicine