2,380 research outputs found
Desenvolvimento de um condicionador de sinal para eletroantenografia
O objetivo principal que motivou este trabalho foi o de construir um condicionador de sinal para medição da resposta elĂ©trica das antenas de insetos devido Ă receção de sinais quĂmicos (Eletroantenografia). O estudo da resposta das antenas dos insetos Ă© particularmente relevante para o estudo das pragas de insetos, para a sua monitorização, e tambĂ©m para a descodificação dos mecanismos olfativos nas relaçÔes planta-inseto, com consequĂȘncias para o desenvolvimento de dispositivos biossensores. O trabalho desenvolvido enquadra-se numa ĂĄrea interdisciplinar da fĂsica, quĂmica, fisiologia, ecologia aplicada e saĂșde pĂșblica. O inseto usado nesta experiĂȘncia foi o gorgulho do eucalipto (Gonipterus Platensis), que tem vindo a dizimar as plantaçÔes de eucalipto em Portugal, provocando graves perdas econĂłmicas aos proprietĂĄrios. O condicionador desenvolvido consiste num sistema de âinterfaceâ com a antena do inseto e um amplificador operacional de baixo ruĂdo e ganho variĂĄvel, que permite amplificar o sinal elĂ©trico da antena para nĂveis adequados Ă aquisição e tratamento de sinal. A vantagem do aparelho construĂdo Ă© o fĂĄcil manuseamento do material biolĂłgico e quĂmico,comparado com ensaios de Eletroantenografia tradicionais com recurso a pipetas de âPasteurâ. Este projeto indicou que o sistema desenvolvido poderĂĄ ser capaz da medição da resposta da antena do gorgulho a estĂmulos olfativos de eucalipto
Exciton g-factors in monolayer and bilayer WSe2 from experiment and theory
The optical properties of monolayer and bilayer transition metal dichalcogenide semiconductors are governed by excitons in different spin and valley configurations, providing versatile aspects for van der Waals heterostructures and devices. Here, we present experimental and theoretical studies of exciton energy splittings in external magnetic field in neutral and charged WSe2 monolayer and bilayer crystals embedded in a field effect device for active doping control. We develop theoretical methods to calculate the exciton g-factors from first principles for all possible spin-valley configurations of excitons in monolayer and bilayer WSe2 including valley-indirect excitons. Our theoretical and experimental findings shed light on some of the characteristic photoluminescence peaks observed for monolayer and bilayer WSe2. In more general terms, the theoretical aspects of our work provide additional means for the characterization of single and few-layer transition metal dichalcogenides, as well as their heterostructures, in the presence of external magnetic fields
Globally Gridded Satellite (GridSat) Observations for Climate Studies
Geostationary satellites have provided routine, high temporal resolution Earth observations since the 1970s. Despite the long period of record, use of these data in climate studies has been limited for numerous reasons, among them: there is no central archive of geostationary data for all international satellites, full temporal and spatial resolution data are voluminous, and diverse calibration and navigation formats encumber the uniform processing needed for multi-satellite climate studies. The International Satellite Cloud Climatology Project set the stage for overcoming these issues by archiving a subset of the full resolution geostationary data at approx.10 km resolution at 3 hourly intervals since 1983. Recent efforts at NOAA s National Climatic Data Center to provide convenient access to these data include remapping the data to a standard map projection, recalibrating the data to optimize temporal homogeneity, extending the record of observations back to 1980, and reformatting the data for broad public distribution. The Gridded Satellite (GridSat) dataset includes observations from the visible, infrared window, and infrared water vapor channels. Data are stored in the netCDF format using standards that permit a wide variety of tools and libraries to quickly and easily process the data. A novel data layering approach, together with appropriate satellite and file metadata, allows users to access GridSat data at varying levels of complexity based on their needs. The result is a climate data record already in use by the meteorological community. Examples include reanalysis of tropical cyclones, studies of global precipitation, and detection and tracking of the intertropical convergence zone
Resource-aware Research on Universe and Matter: Call-to-Action in Digital Transformation
Given the urgency to reduce fossil fuel energy production to make climate
tipping points less likely, we call for resource-aware knowledge gain in the
research areas on Universe and Matter with emphasis on the digital
transformation. A portfolio of measures is described in detail and then
summarized according to the timescales required for their implementation. The
measures will both contribute to sustainable research and accelerate scientific
progress through increased awareness of resource usage. This work is based on a
three-days workshop on sustainability in digital transformation held in May
2023.Comment: 20 pages, 2 figures, publication following workshop 'Sustainability
in the Digital Transformation of Basic Research on Universe & Matter', 30 May
to 2 June 2023, Meinerzhagen, Germany, https://indico.desy.de/event/3748
Partial inhibition of mitochondrial complex I ameliorates Alzheimer\u27s disease pathology and cognition in APP/PS1 female mice.
Alzheimer\u27s Disease (AD) is a devastating neurodegenerative disorder without a cure. Here we show that mitochondrial respiratory chain complex I is an important small molecule druggable target in AD. Partial inhibition of complex I triggers the AMP-activated protein kinase-dependent signaling network leading to neuroprotection in symptomatic APP/PS1 female mice, a translational model of AD. Treatment of symptomatic APP/PS1 mice with complex I inhibitor improved energy homeostasis, synaptic activity, long-term potentiation, dendritic spine maturation, cognitive function and proteostasis, and reduced oxidative stress and inflammation in brain and periphery, ultimately blocking the ongoing neurodegeneration. Therapeutic efficacy in vivo was monitored using translational biomarkers FDG-PET, 31P NMR, and metabolomics. Cross-validation of the mouse and the human transcriptomic data from the NIH Accelerating Medicines Partnership-AD database demonstrated that pathways improved by the treatment in APP/PS1 mice, including the immune system response and neurotransmission, represent mechanisms essential for therapeutic efficacy in AD patients
National and subnational short-term forecasting of COVID-19 in Germany and Poland during early 2021
We compare forecasts of weekly case and death numbers for COVID-19 in Germany and Poland based on 15 different modelling approaches. These cover the period from January to April 2021 and address numbers of cases and deaths one and two weeks into the future, along with the respective uncertainties. We find that combining different forecasts into one forecast can enable better predictions. However, case numbers over longer periods were challenging to predict. Additional data sources, such as information about different versions of the SARS-CoV-2 virus present in the population, might improve forecasts in the future
First results of the CAST-RADES haloscope search for axions at 34.67 ÎŒeV
We present results of the Relic Axion Dark-Matter Exploratory Setup (RADES), a detector which is part of the CERN Axion Solar Telescope (CAST), searching for axion dark matter in the 34.67ÎŒeV mass range. A radio frequency cavity consisting of 5 sub-cavities coupled by inductive irises took physics data inside the CAST dipole magnet for the first time using this filter-like haloscope geometry. An exclusion limit with a 95% credibility level on the axion-photon coupling constant of gaÎł & 4 Ă 10â13 GeVâ1 over a mass range of 34.6738ÎŒeV < ma < 34.6771ÎŒeV is set. This constitutes a significant improvement over the current strongest limit set by CAST at this mass and is at the same time one of the most sensitive direct searches for an axion dark matter candidate above the mass of 25ÎŒeV. The results also demonstrate the feasibility of exploring a wider mass range around the value probed by CAST-RADES in this work using similar coherent resonant cavitiesWe wish to thank our colleagues at CERN, in particular Marc Thiebert from the coating lab, as well as the whole team of the CERN Central Cryogenic Laboratory for their support and advice in speci c aspects of the project. We thank Arefe Abghari for her contributions as the project's summer student during 2018. This work has been funded by the Spanish Agencia Estatal de Investigacion (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) under project FPA-2016-76978-C3-2-P and PID2019-108122GB-C33, and was supported by the CERN Doctoral Studentship programme. The research leading
to these results has received funding from the European Research Council and BD, JG and SAC acknowledge support through the European Research Council under grant ERC-2018-StG-802836 (AxScale project). BD also acknowledges fruitful discussions at MIAPP supported by DFG under EXC-2094 { 390783311. IGI acknowledges also support from the European Research Council (ERC) under grant ERC-2017-AdG-788781 (IAXO+ project). JR has been supported by the Ramon y Cajal Fellowship 2012-10597, the grant PGC2018-095328-B-I00(FEDER/Agencia estatal de investigaci on) and FSE-GA2017-2019-E12/7R (Gobierno de AragĂłn/FEDER) (MINECO/FEDER), the EU through the ITN \Elusives" H2020-MSCA-ITN-2015/674896 and the Deutsche Forschungsgemeinschaft under grant SFB-1258 as a Mercator Fellow. CPG was supported by PROMETEO II/2014/050 of Generalitat Valenciana, FPA2014-57816-P of MINECO and by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreements 690575 and 674896. AM is supported by the European Research Council under Grant No. 742104. Part of this work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344
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