8,643 research outputs found

    Extreme drought impacts have been underestimated in grasslands and shrublands globally

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    Climate change is increasing the frequency and severity of short-term (~1 y) drought events—the most common duration of drought—globally. Yet the impact of this intensification of drought on ecosystem functioning remains poorly resolved. This is due in part to the widely disparate approaches ecologists have employed to study drought, variation in the severity and duration of drought studied, and differences among ecosystems in vegetation, edaphic and climatic attributes that can mediate drought impacts. To overcome these problems and better identify the factors that modulate drought responses, we used a coordinated distributed experiment to quantify the impact of short-term drought on grassland and shrubland ecosystems. With a standardized approach, we imposed ~a single year of drought at 100 sites on six continents. Here we show that loss of a foundational ecosystem function—aboveground net primary production (ANPP)—was 60% greater at sites that experienced statistically extreme drought (1-in-100-y event) vs. those sites where drought was nominal (historically more common) in magnitude (35% vs. 21%, respectively). This reduction in a key carbon cycle process with a single year of extreme drought greatly exceeds previously reported losses for grasslands and shrublands. Our global experiment also revealed high variability in drought response but that relative reductions in ANPP were greater in drier ecosystems and those with fewer plant species. Overall, our results demonstrate with unprecedented rigor that the global impacts of projected increases in drought severity have been significantly underestimated and that drier and less diverse sites are likely to be most vulnerable to extreme drought

    Ethnic differences in response to atypical antipsychotics in patients with schizophrenia: individual patient data meta-analysis of randomised placebo-controlled registration trials submitted to the Dutch Medicines Evaluation Board.

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    BACKGROUND: Little is known about the effect of ethnicity on the response to antipsychotic medication in patients with schizophrenia. AIMS: To determine whether ethnicity moderates the response to antipsychotic medication in patients with schizophrenia, and whether this moderation is independent of confounders. METHOD: We analysed 18 short-term, placebo-controlled registration trials of atypical antipsychotic medications in patients with schizophrenia (N = 3880). A two-step, random-effects, individual patient data meta-analysis was applied to establish the moderating effect of ethnicity (White versus Black) on symptom improvement according to the Brief Psychiatric Rating Scale (BPRS) and on response, defined as >30% BPRS reduction. These analyses were corrected for baseline severity, baseline negative symptoms, age and gender. A conventional meta-analysis was performed to determine the effect size of antipsychotic treatment for each ethnic group separately. RESULTS: In the complete data-set, 61% of patients were White, 25.6% of patients were Black and 13.4% of patients were of other ethnicities. Ethnicity did not moderate the efficacy of antipsychotic treatment: pooled β-coefficient for the interaction between treatment and ethnic group was -0.582 (95% CI -2.567 to 1.412) for mean BPRS change, with an odds ratio of 0.875 (95% CI 0.510-1.499) for response. These results were not modified by confounders. CONCLUSIONS: Atypical antipsychotic medication is equally effective in both Black and White patients with schizophrenia. In registration trials, White and Black patients were overrepresented relative to other ethnic groups, limiting the generalisability of our findings

    What Does the Geometry of the Hβ BLR Depend On?

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    We combine our dynamical modeling black-hole mass measurements from the Lick AGN Monitoring Project 2016 sample with measured cross-correlation time lags and line widths to recover individual scale factors, f , used in traditional reverberation-mapping analyses. We extend our sample by including prior results from Code for AGN Reverberation and Modeling of Emission Lines ( caramel ) studies that have utilized our methods. Aiming to improve the precision of black-hole mass estimates, as well as uncover any regularities in the behavior of the broad-line region (BLR), we search for correlations between f and other AGN/BLR parameters. We find (i) evidence for a correlation between the virial coefficient log10(fmean,σ){\mathrm{log}}_{10}({f}_{\mathrm{mean},\sigma }) and black-hole mass, (ii) marginal evidence for a similar correlation between log10(frms,σ){\mathrm{log}}_{10}({f}_{\mathrm{rms},\sigma }) and black-hole mass, (iii) marginal evidence for an anticorrelation of BLR disk thickness with log10(fmean,FWHM){\mathrm{log}}_{10}({f}_{\mathrm{mean},\mathrm{FWHM}}) and log10(frms,FWHM){\mathrm{log}}_{10}({f}_{\mathrm{rms},\mathrm{FWHM}}) , and (iv) marginal evidence for an anticorrelation of inclination angle with log10(fmean,FWHM){\mathrm{log}}_{10}({f}_{\mathrm{mean},\mathrm{FWHM}}) , log10(frms,σ){\mathrm{log}}_{10}({f}_{\mathrm{rms},\sigma }) , and log10(fmean,σ){\mathrm{log}}_{10}({f}_{\mathrm{mean},\sigma }) . Last, we find marginal evidence for a correlation between line-profile shape, when using the root-mean-square spectrum, log10(FWHM/σ)rms{\mathrm{log}}_{10}{(\mathrm{FWHM}/\sigma )}_{\mathrm{rms}} , and the virial coefficient, log10(frms,σ){\mathrm{log}}_{10}({f}_{\mathrm{rms},\sigma }) , and investigate how BLR properties might be related to line-profile shape using caramel models

    A Randomized, Double-Blind, Placebo-Controlled, Parallel Study Investigating the Efficacy of a Whole Coffee Cherry Extract and Phosphatidylserine Formulation on Cognitive Performance of Healthy Adults with Self-Perceived Memory Problems

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    Abstract Introduction Cognition refers to brain functions including memory, learning, and thought processing and is increasingly important to individuals. However, impairment of cognitive function is a concern among North American adults. Therefore, effective and reliable treatments are needed. Methods This randomized, double-blind, placebo-controlled study examined the effects of 42 days of Neuriva® supplementation, a whole coffee cherry extract and phosphatidylserine supplement, on memory, accuracy, focus and concentration and learning among 138 healthy adults (40–65 years) with self-reported memory problems. Plasma brain-derived neurotrophic factor (BDNF) levels, Computerized Mental Performance Assessment System (COMPASS) tasks, the Everyday Memory Questionnaire (EMQ), and Go/No-Go tests were assessed at baseline and day 42. Results As compared to placebo, Neuriva® supplementation elicited greater improvements at day 42 in numeric working memory COMPASS task accuracy outcomes (p ≤ 0.024) which assessed memory, accuracy, and focus and concentration, and reaction time outcomes (p ≤ 0.031) which assessed memory as well as focus and concentration. Neuriva® supplementation improved overall accuracy (p = 0.035) in the picture recognition task that assessed memory, accuracy, and learning compared to placebo. No significant differences between groups were observed for BDNF, the EMQ, or Go/No-Go tests. Conclusion Results suggest 42 days of Neuriva® supplementation was safe, well tolerated, and beneficial in improving memory, accuracy, focus and concentration, and learning in a healthy adult population with self-reported memory problems

    Agua Salud alphavirus infection, dissemination and transmission in Aedes aegypti mosquitoes

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    Mosquitoes are competent vectors for many important arthropod-borne viruses (arboviruses). In addition to arboviruses, insect-specific viruses (ISV) have also been discovered in mosquitoes. ISVs are viruses that replicate in insect hosts but are unable to infect and replicate in vertebrates. They have been shown to interfere with arbovirus replication in some cases. Despite the increase in studies on ISV–arbovirus interactions, ISV interactions with their hosts and how they are maintained in nature are still not well understood. In the present study, we investigated the infection and dissemination of the Agua Salud alphavirus (ASALV) in the important mosquito vector Aedes aegypti through different infection routes (per oral infection, intrathoracic injection) and its transmission. We show here that ASALV infects the female Ae. aegypti and replicates when mosquitoes are infected intrathoracically or orally. ASALV disseminated to different tissues, including the midgut, salivary glands and ovaries. However, we observed a higher virus load in the brain than in the salivary glands and carcasses, suggesting a tropism towards brain tissues. Our results show that ASALV is transmitted horizontally during adult and larval stages, although we did not observe vertical transmission. Understanding ISV infection and dissemination dynamics in Ae. aegypti and their transmission routes could help the use of ISVs as an arbovirus control strategy in the future

    The Bergen proton CT system

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    The Bergen proton Computed Tomography (pCT) is a prototype detector under construction. It aims to have the capability to track and measure ions’ energy deposition to minimize uncertainty in proton treatment planning. It is a high granularity digital tracking calorimeter, where the first two layers will act as tracking layers to obtain positional information of the incoming particle. The remainder of the detector will act as a calorimeter. Beam tests have been performed with multiple beams. These tests have shown that the ALPIDE chip sensor can measure the deposited energy, making it possible for the sensors to distinguish between the tracks in the Digital Tracking Calorimeter (DTC)

    Competition drives the evolution of emergent neutrality in the dietary niches of mammalian herbivores

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    The coexistence of multiple species competing for a finite set of resources is a widely debated topic in community ecology. Species with strongly overlapping niches are expected to drive each other towards exclusion, but such species may also coexist if they have similar competitive abilities. This compromise can lead to a peculiar pattern of clumped coexistence, where multiple species share similar niches, leaving gaps open in the theoretically available niche space. Large mammal herbivores may be a good example of this, where species’ dietary niches clump as either grazers, browsers, or intermediate-feeders, rather than being continuously distributed over the resource gradient. Here, we develop a model of such emergent neutrality amongst species competing for a set of predefined resources each distributed along a finite niche axis. The model is commensurate with stable isotope niches, thus allowing us to compare its predictions with empirical evidence for changes in community niche structure over evolutionary time. We present stable carbon and oxygen isotope evidence for six discontinuous Late Quaternary assemblages from the central interior of South Africa, demonstrating the emergence of a clumped niche structure from an initial pattern of strongly overlapping diets. We show that species tend to cluster on parts of the niche axis where resource availability is highest, mirroring the proliferation of grazer species as landscapes became more grass-dominated. However, the presence of competition means that species’ niches continue to differentiate, explaining the persistence of browser and intermediate-feeder species even in these open, predominantly treeless landscapes. These results highlight that species interactions are a necessary factor for robust inferences about the evolutionary dynamics of palaeocommunities

    Nausea and nausea-related symptoms in children with cancer: Presence, severity, risk factors and impact on quality of life during the first year of treatment

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    Aims: Identify 1) presence of nausea and nausea-related symptoms and its relationship with health-related quality of life (HRQoL), and 2) severity of nausea and associations with patient-related factors in children with cancer during the first year of treatment. Methods: A historical cohort study of 781 patients with cancer (2–21 years) was conducted. Presence and severity of nausea were assessed at 3, 6, 9, and 12 months after diagnosis using the nausea scale of the PedsQL3.0 Cancer Module, comprising 5 symptoms, using proxy-report (2–7 years) or self-report (8–21 years). Multivariable multilevel analyses were performed to evaluate the association between patient-related factors and nausea. Overall HRQoL (generic PedsQL) was compared between children with presence and absence of nausea related-symptoms. Results: The presence of nausea during medical treatment was highest at 6 months after diagnosis (42.9 %). Highest symptom presence was seen on the item “food not tasting good” (range 51.6 %−62.8 %). For all nausea-related symptoms, average HRQoL scores were 9.9–14.4 points lower for patients with symptoms compared to patients without symptoms.Pain, treatment anxiety, and worry were significantly associated with nausea in all children. In patients aged 8–21 years, male gender, a solid tumor, and BMI were associated with nausea. Patients with solid tumors were at higher risk of nausea compared to patients with hematological malignancies or brain/CNS tumors. Patients with a high BMI reported less nausea compared to patients with a normal BMI. Conclusion: Nausea is still a major problem in children with cancer and has a negative impact on HRQoL

    Directed communication in games with directed graphs

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    We introduce a novel concept of directed communication and a related connectedness in directed graphs, and apply this to model certain cooperation restrictions in cooperative games. In the literature on communication in directed networks or directed graphs, one can find different notions of connectedness, and different ways how directed communication restricts cooperation possibilities of players in a game. In this paper, we introduce a notion of connectedness in directed graphs that is based on directed paths. We assume that a coalition of players in a game can only cooperate if these players form a directed path in a directed communication graph. We define a restricted game following the same approach as Myerson for undirected communication situations, and consider the allocation rule that applies the Shapley value to this restricted game. We characterize this value by extended versions of the well-known component efficiency, fairness and balanced contributions axioms. Moreover, using the new notion of connectedness, we apply this allocation rule to define network centrality, efficiency and vulnerability measures for directed networks.</p