566 research outputs found

    High energy Coulomb-scattered electrons for relativistic particle beam diagnostics

    Full text link
    A new system used for monitoring energetic Coulomb-scattered electrons as the main diagnostic for accurately aligning the electron and ion beams in the new Relativistic Heavy Ion Collider (RHIC) electron lenses is described in detail. The theory of electron scattering from relativistic ions is developed and applied to the design and implementation of the system used to achieve and maintain the alignment. Commissioning with gold and 3He beams is then described as well as the successful utilization of the new system during the 2015 RHIC polarized proton run. Systematic errors of the new method are then estimated. Finally, some possible future applications of Coulomb-scattered electrons for beam diagnostics are briefly discussed.Comment: 16 pages, 23 figure

    Marine Mammal Strandings

    Get PDF
    Since the 1980s, there has been growing concern about the health of marine mammal populations in coastal waters and in particular with respect to a decline in harbour porpoise (Phocoena phocoena) numbers. A variety of possible causes have been proposed including infectious diseases, changes in food supply, pollution and entanglement in fishing gear. Recent studies linking contaminant data with disease levels in cetaceans suggest that higher contaminant levels are generally found in animals with a higher number of diseases i.e. that chronic exposure to PCBs or trace metals negatively influences the health status of some cetacean species by predisposing individuals to mortality associated with infectious disease (Jepson et al., 1999; Siebert et al., 1999). The reverse may also be true, that high levels of disease may disable the animal to the extent that coping with contaminants is not possible and toxins accumulate. The potentially serious role of infectious disease was demonstrated by the phocine distemper epidemic of 1987, which killed approximately 18,000 common seals (Phoca vitulina) in the North Sea and adjacent waters (Kennedy, 1990) and by the subsequent morbillivirus epidemic in striped dolphins (Stenella coeruleoalba) in the Mediterranean sea (Domingo et al., 1990). Rejinders (1986) and Brouwer et al. (1989) demonstrated that feeding captive common seals with fish caught in highly polluted waters had deleterious effects on their health and there was speculation that pollution may have been a factor in the severity of these epidemics (Aguilar and Raga, 1990, Aguilar and Borrell, 1994, deSwart et al., 1994). Relatively little work on the health status and contaminant loadings in cetacean and pinniped populations in the Irish Sea has been undertaken to date (e.g., Morris et al., 1989, Law et al., 1995, Berrow et al., 1998a). Given the need for such data from relatively "high-medium" polluted waters (e.g., the Irish Sea) such a data collection programme is highly desirable. For a large number of cetacean and seal species, the only way to assess their health status and contaminant loadings, bar live capture and/or killing them, is through a Strandings Programme. Such programmes involve the recording and recovering of beach cast animals. Strandings programmes allow for some definition of the distribution of different species, but are primarily used to examine health status and to determine population parameters necessary for management decisions. Such programmes are imperative, as they allow top mammalian predators to be monitored and increase our knowledge of a number of biological parameters (for example, age, reproductive status, diet), parasites and contaminant loadings. Cause of death can reflect disease status and in the absence of observer programmes, can indicate fishing associated mortalities (by-catch).Funder: European Unio

    Decision making and risk management in adventure sports coaching

    Get PDF
    Adventure sport coaches practice in environments that are dynamic and high in risk, both perceived and actual. The inherent risks associated with these activities, individuals’ responses and the optimal exploitation of both combine to make the processes of risk management more complex and hazardous than the traditional sports where risk management is focused almost exclusively on minimization. Pivotal to this process is the adventure sports coaches’ ability to make effective judgments regarding levels of risk, potential benefits and possible consequences. The exact nature of this decision making process should form the basis of coaching practice and coach education in this complex and dynamic field. This positional paper examines decision making by the adventure sports coach in these complex, challenging environments and seeks to stimulate debate whilst offering a basis for future research into this topic

    The atrial natriuretic peptide and guanylyl cyclase-A system modulates pancreatic beta-cell function

    Get PDF
    Atrial natriuretic peptide (ANP) and its guanylyl cyclase-A (GC-A) receptor are being involved in metabolism, although their role in the endocrine pancreas is still greatly unknown. The aim of this work is to study a possible role for the ANP/GC-A system in modulating pancreatic beta-cell function. The results presented here show a direct effect of the GC-A receptor in regulating glucose-stimulated insulin secretion (GSIS) and beta-cell mass. GC-A activation by its natural ligand, ANP, rapidly blocked ATP-dependent potassium (K(ATP)) channel activity, increased glucose-elicited Ca(2+) signals, and enhanced GSIS in islets of Langerhans. The effect in GSIS was inhibited in islets from GC-A knockout (KO) mice. Pancreatic islets from GC-A KO mice responded to increasing glucose concentrations with enhanced insulin secretion compared with wild type (WT). Remarkably, islets from GC-A KO mice were smaller, presented lower beta-cell mass and decreased insulin content. However, glucose-induced Ca(2+) response was more vigorous in GC-A KO islets, and basal K(ATP) channel activity in GC-A KO beta-cells was greatly diminished compared with WT. When protein levels of the two K(ATP) channel constitutive subunits sulfonylurea receptor 1 and Inward rectifier potassium channel 6.2 were measured, both were diminished in GC-A KO islets. These alterations on beta-cell function were not associated with disruption of glucose tolerance or insulin sensitivity in vivo. Glucose and insulin tolerance tests were similar in WT and GC-A KO mice. Our data suggest that the ANP/GC-A system may have a modulating effect on beta-cell function

    NMRD studies on phthalate dioxygenase: evidence for displacement of water on binding substrate

    Full text link
     Water proton T 1 –1 measurements at magnetic fields between 0.01 and 50 MHz [nuclear magnetic relaxation dispersion (NMRD) measurements] have been performed on solutions of phthalate dioxygenase (PDO) reconstituted at the catalytic iron site with copper(II) or manganese(II). The data show evidence of a weakly coordinated water molecule in CuPDO; in the presence of the substrate, phthalate, this water appears to become even less tightly bound, and an additional tightly coordinated water can be detected. In PDO reconstituted with manganese, one tightly coordinated water is detected in the presence and in the absence of phthalate. An attempt is made to reconcile these data with low-temperature near-IR magnetic circular dichroism and X-ray absorption data, which show that PDO reconstituted with iron or cobalt is six-coordinate in the absence of substrate and five-coordinate in the presence of substrate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42322/1/775-1-5-468_60010468.pd

    Transient early preeclampsia in twin pregnancy with a triploid fetus: a case report

    Get PDF
    INTRODUCTION: Triploid pregnancies have an increased risk of early preeclampsia. Twin pregnancies consisting of one healthy fetus and one complete or partial molar, with or without a triploid fetus, are rare and management is complex. CASE PRESENTATION: A 33-year-old Caucasian woman presented with a dichorionic diamniotic twin pregnancy. One fetus showed early growth restriction resulting in fetal death at 20 weeks. The placenta was enlarged with some cysts. Chorionic villus biopsy confirmed triploidy. At 21 weeks, the patient developed preeclampsia with a blood pressure of 154/98 mmHg and proteinuria (24 hour protein excretion of 2.5 g/L), for which she was hospitalized. Without pharmacological interventions, the blood pressure normalized and proteinuria disappeared. At 35 weeks, she again developed preeclampsia. A cesarean section was performed at 38 weeks and a healthy child was born. CONCLUSIONS: Survival of the healthy fetus is possible in a twin pregnancy with a triploid fetus complicated by early preeclampsia. The pregnancy should not be terminated if the triploid twin has died and as long as conservative management is safe
    • …
    corecore