508 research outputs found

    THE INFLUENCE OF WATER TEMPERATURE AND FLOW ON YEAR CLASS STRENGTH OF TWAITE SHAD (ALOSA FALLAX FALLAX) FROM THE RIVER SEVERN, ENGLAND.

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    Year class strength (YCS) was estimated for the 25 year period between 1972 and 1996. The index (YCS) was based on the mean number of six year old female fish caught per tide (1972-1991) in a net fishery at the start of the freshwater phase of their spawning migration, or predicted from juvenile data (1992-1996). The variation in recruitment as measured by the coefficient of variation for the 20 year period (1972 to 1991) was 124.5 %. There was good spawning success in 1976 and 1989 and particularly poor recruitment in the periods 1977 to 1981 and 1985 to 1988. Since 1990 recruitment has remained relatively stable. Water temperature was positively correlated to YCS with mean July temperature explaining the greatest proportion of the variance in YCS (67 %), followed by August (48 %), June (31 %) and October (20 %) ; May and September temperatures did not significantly explain the variation in YCS. Flow in the months June to August were significantly inversely correlated with YCS, with the greatest proportion of the variability explained by August flows (41 %), followed by flows in July (36 %) and June (25 %). Flows in May, September and October were not significantly correlated with YCS. Combining environmental variables in a multiple regression indicated that mean daily temperature between June and August accounted for 77.1 % of the variability in year class strength. The inclusion of flow did not increase significantly the amount of variation explained

    Sensitivity studies for r-process nucleosynthesis in three astrophysical scenarios

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    In rapid neutron capture, or r-process, nucleosynthesis, heavy elements are built up via a sequence of neutron captures and beta decays that involves thousands of nuclei far from stability. Though we understand the basics of how the r-process proceeds, its astrophysical site is still not conclusively known. The nuclear network simulations we use to test potential astrophysical scenarios require nuclear physics data (masses, beta decay lifetimes, neutron capture rates, fission probabilities) for all of the nuclei on the neutron-rich side of the nuclear chart, from the valley of stability to the neutron drip line. Here we discuss recent sensitivity studies that aim to determine which individual pieces of nuclear data are the most crucial for r-process calculations. We consider three types of astrophysical scenarios: a traditional hot r-process, a cold r-process in which the temperature and density drop rapidly, and a neutron star merger trajectory.Comment: 8 pages, 4 figures, submitted to the Proceedings of the International Nuclear Physics Conference (INPC) 201

    Blood Brain-Derived Neurotrophic Factor (BDNF) and Major Depression:Do We Have a Translational Perspective?

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    Major depressive disorder (MDD) affects millions of people worldwide and is a leading cause of disability. Several theories have been proposed to explain its pathological mechanisms, and the "neurotrophin hypothesis of depression" involves one of the most relevant pathways. Brain-derived neurotrophic factor (BDNF) is an important neurotrophin, and it has been extensively investigated in both experimental models and clinical studies of MDD. Robust empirical findings have indicated an association between increased BDNF gene expression and peripheral concentration with improved neuronal plasticity and neurogenesis. Additionally, several studies have indicated the blunt expression of BDNF in carriers of the Val66Met gene polymorphism and lower blood BDNF (serum or plasma) levels in depressed individuals. Clinical trials have yielded mixed results with different treatment options, peripheral blood BDNF measurement techniques, and time of observation. Previous meta-analyses of MDD treatment have indicated that antidepressants and electroconvulsive therapy showed higher levels of blood BDNF after treatment but not with physical exercise, psychotherapy, or direct current stimulation. Moreover, the rapid-acting antidepressant ketamine has presented an early increase in blood BDNF concentration. Although evidence has pointed to increased levels of BDNF after antidepressant therapy, several factors, such as heterogeneous results, low sample size, publication bias, and different BDNF measurements (serum or plasma), pose a challenge in the interpretation of the relation between peripheral blood BDNF and MDD. These potential gaps in the literature have not been properly addressed in previous narrative reviews. In this review, current evidence regarding BDNF function, genetics and epigenetics, expression, and results from clinical trials is summarized, putting the literature into a translational perspective on MDD. In general, blood BDNF cannot be recommended for use as a biomarker in clinical practice. Moreover, future studies should expand the evidence with larger samples, use the serum or serum: whole blood concentration of BDNF as a more accurate measure of peripheral BDNF, and compare its change upon different treatment modalities of MDD

    Subtypes of Late-Life Depression:A Data-Driven Approach on Cognitive Domains and Physical Frailty

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    Background: With increasing age, symptoms of depression may increasingly overlap with age-related physical frailty and cognitive decline. We aim to identify late-life-related subtypes of depression based on measures of depressive symptom dimensions, cognitive performance, and physical frailty. Methods: A clinical cohort study of 375 depressed older patients with a DSM-IV depressive disorder (acronym NESDO). A latent profile analysis was applied on the three subscales of the Inventory of Depressive Symptomatology, as well as performance in five cognitive domains and two proxies for physical frailty. For each class, we investigated remission, dropout, and mortality at 2-year follow-up as well as change over time of depressive symptom severity, cognitive performance, and physical frailty. Results: A latent profile analysis model with five classes best described the data, yielding two subgroups suffering from pure depression (“mild” and “severe” depression, 55% of all patients) and three subgroups characterized by a specific profile of cognitive and physical frailty features, labeled as “amnestic depression,” “frail-depressed, physically dominated,” and “frail-depressed, cognitively dominated.” The prospective analyses showed that patients in the subgroup of “mild depression” and “amnestic depression” had the highest remission rates, whereas patients in both frail-depressed subgroups had the highest mortality rates. Conclusions: Late-life depression can be subtyped by specific combinations of age-related clinical features, which seems to have prospective relevance. Subtyping according to the cognitive profile and physical frailty may be relevant for studies examining underlying disease processes as well as to stratify treatment studies on the effectiveness of antidepressants, psychotherapy, and augmentation with geriatric rehabilitation

    Serotonin receptor inhibitor is associated with falls independent of frailty in older adults

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    Objectives: To evaluate whether fall risk in older adults is associated with the use of selective serotonin receptor inhibitor (SSRI) monotherapy among geriatric outpatients, and whether this association is moderated by the presence of depressive disorder and/or frailty. Methods: Prospective cohort study with a 12-month follow-up and including 811 community-dwelling adults aged 60 or older from a university-based Geriatric Outpatient Unit. Major depressive disorder (MDD) was diagnosed according to DSM-5 criteria; subsyndromal depression as not meeting MDD criteria, but a Geriatric Depression Scale 15-item score ? 6 points. Frailty was evaluated with the FRAIL questionnaire. The association between SSRI use, depression, or both as well as the association between SSRI use, frailty, or both with falls were estimated through a generalized estimating equation (GEE) adjusted for relevant confounders. Results: At baseline, 297 patients (36.6%) used a SSRI (82 without remitted depression) and 306 (37.7%) were classified as physically frail. Frailty was more prevalent among SSRI users (44.8% versus 33.7%, p =.004). After 12 months, 179 participants had at least one fall (22.1%). SSRI use, depression as well as frailty were all independently associated with falls during follow-up. Nonetheless, patients with concurrent of SSRI usage and non-remitted depression had no higher risk compared to either remitted SSRI users or depressed patients without SSRIs. In contrast, concurrence of SSRI use and frailty increases the risk of falling substantially above those by SSRI usage or frailty alone. Conclusion: SSRI usage was independently associated with falls. Especially in frail-depressed patients, treatment strategies for depression other than SSRIs should be considered

    Impact of sheep grazing on juvenile sea bass, Dicentrarchus labrax L., in tidal salt marshes

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    The diet of young of the year sea bass, Dicentrarchus labrax L., from sheep grazed and ungrazed tidal salt marshes were com-pared qualitatively and quantitatively in Mont Saint-Michel Bay. In areas without grazing pressure, the vegetation gradient changes from a pioneer Puccinellia maritima dominated community at the tidal ¯at boundaries through a Atriplex portulacoides dominated community in the middle of the marsh to a mature Elymus pungens dominated community at the landward edge. The A. portula-coides community is highly productive and provides important quantities of litter which provides a habitat and good supply to substain high densities of the detrivorous amphipod Orchestia gammarellus. In the grazed areas, the vegetation is replaced by P. maritima communities, a low productive grass plant, and food availability and habitat suitability are reduced for O. gammarellus. Juvenile sea bass colonise the salt marsh at ¯ood during 43% of the spring tides which inundate the salt marsh creeks. They forage inside the marsh and feed mainly on O. gammarellus in the ungrazed marshes. In grazed areas, this amphipod is replaced by other species and juvenile sea bass consume less food from the marsh. This illustrates a direct effect of a terrestrial herbivore on a coastal food web, and suggests that management of salt marsh is complex and promotion of one component of their biota could involve reductions in other species

    A multidimensional program including standing exercises, health education, and telephone support to reduce sedentary behavior in frail older adults:Randomized clinical trial

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    Objectives: The primary aim of this study was to evaluate the effect of a multidimensional program including home-based standing exercises, health education, and telephone support for the reduction of sedentary behavior in community-dwelling frail older adults. The secondary aim of this study was to evaluate the safety and adherence of the program. Study design: A single-blind, randomized controlled trial. Methods: A total of 43 frail older adults were randomly assigned to the intervention and control groups. The intervention consisted of combined strategies including home-based standing exercises, health education, and telephone support for 16 weeks for frail older adults. The control group received orientation regarding the harmful effects of a sedentary lifestyle. Sedentary behavior was evaluated by total sedentary time, accumulated sedentary time in bouts of at least 10 min, and by the break in sedentary time, measured by an accelerometer used for at least 600 min/day for 4 days. Safety was assessed by self-reporting of possible adverse events. Adherence was assessed based on the number of days in which standing exercises were performed by the participants. Repeated measures ANOVA and Tukeys post hoc test were used to analyze the collected data. Results: The intervention group reduced the sedentary time by 30 min/day (p= 0.048), but without significant maintenance after 30 days of the program. Of the total number of participants, 82% (n = 14) of the intervention group participants showed more than 70% adherence to the program. The main adverse effects faced by the intervention group participants were tiredness (53%; n = 9) and lower limb pain (47%; n = 8). Conclusions: The multidimensional program reduced sedentary behavior, was safe, and showed satisfactory adherence in frail older adults

    Beta-delayed-neutron studies of 135,136^{135,136}Sb and 140^{140}I performed with trapped ions

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    Beta-delayed-neutron (β\betan) spectroscopy was performed using the Beta-decay Paul Trap and an array of radiation detectors. The β\betan branching ratios and energy spectra for 135,136^{135,136}Sb and 140^{140}I were obtained by measuring the time of flight of recoil ions emerging from the trapped ion cloud. These nuclei are located at the edge of an isotopic region identified as having β\betan branching ratios that impact the r-process abundance pattern around the A~130 peak. For 135,136^{135,136}Sb and 140^{140}I, β\betan branching ratios of 14.6(11)%, 17.6(28)%, and 7.6(28)% were determined, respectively. The β\betan energy spectra obtained for 135^{135}Sb and 140^{140}I are compared with results from direct neutron measurements, and the β\betan energy spectrum for 136^{136}Sb has been measured for the first time
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