671 research outputs found

    Behavioural Evidence and Chemical Identification of a Female Sex Pheromone in Anagrus atomus (Hymenoptera: Mymaridae)

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    Anagrus atomus (L.) is an egg parasitoid involved in the biological control of Empoasca vitis (G\uf6the) in vineyards. Sex pheromones play a crucial role in mate finding for several parasitoid species and could be used for monitoring under field conditions. We carried out laboratory and field studies aimed at assessing the existence and identity of a possible A. atomus sex pheromone. We found that males were significantly attracted by virgin females independent of age. Males were not attracted to individuals of the same sex, but they were attracted by a crude extract from an unmated female and its polar fraction. Eugenol (4-allyl-2-methoxyphenol) was identified as the attractive substance and proved to be attractive not only in the olfactometer but also in another laboratory bioassay and under field conditions. Attraction of males, but not females, confirms that this is not an aggregation pheromone. This is the first sex-pheromone component identified in Mymaridae, however more compounds could be involved in the mating behaviour of A. atomus. The utility of a sex pheromone in A. atomus is discussed in the context of fitness returns

    Global public health policies: gathering public health associations' perspectives

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    Background Advocacy is one of the core functions of public health and is a key tool for achieving Sustainable Development Goals. Public health associations play a key role in advocating for the development and implementation of strategies to prevent diseases and promote health and well-being. Objective This study aims to map out the focus of public health advocacy carried out by selected national public health associations over 4 years, between 2018 and 2021, in order to identify gaps and strengths and support associations and professionals in their advocacy efforts. Methods Twelve national public health associations participated in the study. Official policy documents produced between 2018 and 2021 were collected and analysed. The title and summary of the policy documents were examined line by line and coded into the main subject categories and themes. A qualitative thematic analysis was conducted. Policies were assessed from global and regional perspectives. Results A total of 220 policy documents were analysed. Overall, the largest number of policy documents came from high-income countries and dealt with environmental health and communicable diseases, including COVID-19, with, however, important differences among regions. In the African region, public health advocacy focused mainly on strengthening health systems; Europe and South America were mostly concerned with communicable diseases and pandemic management; and North America and the Western Pacific regions focused primarily on climate change. Limited attention was paid to international health and health as a human right in all regions. Conclusion Our study showed that, especially in high-income countries, public health associations actively engage in advocacy; however, more effort needs to be devoted to implementing a more international and intersectoral approach at the global level, anchored in health as a human right and aligned with the Sustainable Development Goals

    LCA to Estimate the Environmental Impact of Dairy Farms: A Case Study

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    Intensive farming is responsible for extreme environmental impacts under different aspects, among which global warming represents a major reason of concern. This is a quantitative problem linked to the farm size and a qualitative one, depending on farming methods and land management. The dairy sector is particularly relevant in terms of environmental impact, and new approaches to meeting sustainability goals at a global scale while meeting society's needs are necessary. The present study was carried out to assess the environmental impact of dairy cattle farms based on a life cycle assessment (LCA) model applied to a case study. These preliminary results show the possibility of identifying the most relevant impacts in terms of supplied products, such as animal feed and plastic packaging, accounting for 19% and 15% of impacts, respectively, and processes, in terms of energy and fuel consumption, accounting for 53% of impacts overall. In particular, the local consumption of fossil fuels for operations within the farm represents the most relevant item of impact, with a small margin for improvement. On the other hand, remarkable opportunities to reduce the impact can be outlined from the perspective of stronger partnerships with suppliers to promote the circularity of packaging and the sourcing of animal feed. Future studies may include the impact of drug administration and the analysis of social aspects of LCA

    A reaction-diffusion model for the hydration/setting of cement

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    We propose a heterogeneous reaction-diffusion model for the hydration and setting of cement. The model is based on diffusional ion transport and on cement specific chemical dissolution/precipitation reactions under spatial heterogeneous solid/liquid conditions. We simulate the spatial and temporal evolution of precipitated micro structures starting from initial random configurations of anhydrous cement particles. Though the simulations have been performed for two dimensional systems, we are able to reproduce qualitatively basic features of the cement hydration problem. The proposed model is also applicable to general water/mineral systems.Comment: REVTeX (12 pages), 4 postscript figures, tarred, gzipped, uuencoded using `uufiles', coming with separate file(s). Figure 1 consists of 6 color plates; if you have no color printer try to send it to a black&white postscript-plotte

    Effect of heat treatment and defects on the tensile behavior of a hot work tool steel manufactured by laser powder bed fusion

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    Microstructure and tensile properties of a hot work tool steel manufactured via laser powder bed fusion (LPBF) were investigated. Specimens were built under two different orientations and subjected to two quenching and tempering heat treatments, featuring different austenitizing and tempering temperatures and the eventual presence of a sub-zero step. Microstructural analyses revealed a homogeneous tempered martensite structure after both heat treatments, with the only distinction of a higher alloying segregation at a sub micrometric scale length in samples subjected to the highest tempering temperatures. Hardness and tensile tests indicated a negligible effect of building orientation on mechanical properties, but a significant influence of heat treatment parameters. The treatment featuring the lower tempering temperatures and the sub-zero step resulted in higher hardness, tensile strength, and elongation, attributed to a lower martensite tempering and alloying segregation. Tensile fracture occurred via crack initiation and unstable propagation from large LPBF defects in all the investigated conditions

    A comparison of edge-preserving approaches for differential interference contrast microscopy

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    In this paper we address the problem of estimating the phase from color images acquired with differential-interference-contrast microscopy. In particular, we consider the nonlinear and nonconvex optimization problem obtained by regularizing a least-squares-like discrepancy term with an edge-preserving functional, given by either the hypersurface potential or the total variation one. We investigate the analytical properties of the resulting objective functions, proving the existence of minimum points, and we propose effective optimization tools able to obtain in both the smooth and the nonsmooth case accurate reconstructions with a reduced computational demand

    Swimming at the Time of COVID-19: A Cross-Sectional Study among Young Italian Competitive Athletes

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    During the coronavirus disease 2019 (COVID-19) pandemic, several restriction measures were imposed to control the virus transmission, with important repercussions on different sectors, including sport. This study aimed to explore the effects of the COVID-19 pandemic on Italian competitive swimmers by analyzing how the disease and the restriction measures affected their training. In total, 396 competitive swimmers (mean age 16.0 ± 3.2 years) participated. A questionnaire was used to collect their general information, to assess whether they had had COVID-19 and the number of training days lost due to the disease or to the closure of swimming facilities, and the possible alternative training adopted. Twenty-four (6.1%) participants had had COVID-19 and lost, on average, 32 training days. The closure of facilities caused an interruption in swimming training for about 18% of the participants. The majority of these continued their training, mainly through home-based exercise, but reduced their weekly training time (-8 median hours/week). A positive association was found between regularly adopted weekly training volume and that assumed during pandemic closure (OR 9.433, CI95% 1.644–54.137, p = 0.012), suggesting that the previous level of engagement in sport can represent a predictor of exercise maintenance in challenging situations such as a pandemic. Further studies are needed to identify personal, environmental, and social resources that can help individuals to counteract the negative effects of restriction measures

    On the global hydration kinetics of tricalcium silicate cement

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    We reconsider a number of measurements for the overall hydration kinetics of tricalcium silicate pastes having an initial water to cement weight ratio close to 0.5. We find that the time dependent ratio of hydrated and unhydrated silica mole numbers can be well characterized by two power-laws in time, x/(1x)(t/tx)ψx/(1-x)\sim (t/t_x)^\psi. For early times t<txt < t_x we find an `accelerated' hydration (ψ=5/2\psi = 5/2) and for later times t>txt > t_x a `deaccelerated' behavior (ψ=1/2\psi = 1/2). The crossover time is estimated as tx16hourst_x \approx 16 hours. We interpret these results in terms of a global second order rate equation indicating that (a) hydrates catalyse the hydration process for t<txt<t_x, (b) they inhibit further hydration for t>txt > t_x and (c) the value of the associated second order rate constant is of magnitude 6x10^{-7} - 7x10^{-6} liter mol^{-1} s^{-1}. We argue, by considering the hydration process actually being furnished as a diffusion limited precipitation that the exponents ψ=5/2\psi = 5/2 and ψ=1/2\psi = 1/2 directly indicate a preferentially `plate' like hydrate microstructure. This is essentially in agreement with experimental observations of cellular hydrate microstructures for this class of materials.Comment: RevTeX macros, 6 pages, 4 postscript figure

    Precessing jets from a moving source and bright X-ray filaments in galaxy clusters

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    We present hydrodynamical calculations carried out with the 3D yguazu-a code of a precessing jet model, which interacts with a plane parallel wind. This scenario describes an extragalactic jet, in which the jet source is in motion with respect to the surrounding intra-cluster medium. From the numerical results, synthetic emission maps and spectra in X-ray band were obtained. We compare these predictions with observations of the radio jets emanating from the radio-galaxy 4C 26.42 (in the Abell 1795 galaxy cluster). We find that the general morphology of the radio jets can be described by a point-symmetric precessing jet system interacting with a plane parallel wind (i.e., the intra-cluster medium flowing past the galaxy). We also find that our synthetic X-ray emission maps reproduce the observed large scale structures (with sizes of the order of tens of kpc).Comment: Accepted for publication in A&A - 7 Pages, 6 figure

    A novel kcna2 variant in a patient with non-progressive congenital ataxia and epilepsy: Functional characterization and sensitivity to 4-aminopyridine

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    Kv1.2 channels, encoded by the KCNA2 gene, are localized in the central and peripheral nervous system, where they regulate neuronal excitability. Recently, heterozygous mutations in KCNA2 have been associated with a spectrum of symptoms extending from epileptic encephalopathy, intellectual disability, and cerebellar ataxia. Patients are treated with a combination of antiepileptic drugs and 4-aminopyridine (4-AP) has been recently trialed in specific cases. We identified a novel variant in KCNA2, E236K, in a Serbian proband with non-progressive congenital ataxia and early onset epilepsy, treated with sodium valproate. To ascertain the pathogenicity of E236K mutation and to verify its sensitivity to 4-AP, we transfected HEK 293 cells with Kv1.2 WT or E236K cDNAs and recorded potassium currents through the whole-cell patchclamp. In silico analysis supported the electrophysiological data. E236K channels showed voltagedependent activation shifted towards negative potentials and slower kinetics of deactivation and activation compared with Kv1.2 WT. Heteromeric Kv1.2 WT+E236K channels, resembling the condition of the heterozygous patient, confirmed a mixed gain-and loss-of-function (GoF/LoF) biophysical phenotype. 4-AP inhibited both Kv1.2 and E236K channels with similar potency. Homology modeling studies of mutant channels suggested a reduced interaction between the residue K236 in the S2 segment and the gating charges at S4. Overall, the biophysical phenotype of E236K channels correlates with the mild end of the clinical spectrum reported in patients with GoF/LoF defects. The response to 4-AP corroborates existing evidence that KCNA2-disorders could benefit from variant-tailored therapeutic approaches, based on functional studies
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