436 research outputs found
Charged-Particle Multiplicities in Charged-Current Neutrino-- and Anti-Neutrino--Nucleus Interactions
The CHORUS experiment, designed to search for
oscillations, consists of a nuclear emulsion target and electronic detectors.
In this paper, results on the production of charged particles in a small sample
of charged-current neutrino-- and anti-neutrino--nucleus interactions at high
energy are presented. For each event, the emission angle and the ionization
features of the charged particles produced in the interaction are recorded,
while the standard kinematic variables are reconstructed using the electronic
detectors. The average multiplicities for charged tracks, the pseudo-rapidity
distributions, the dispersion in the multiplicity of charged particles and the
KNO scaling are studied in different kinematical regions. A study of
quasi-elastic topologies performed for the first time in nuclear emulsions is
also reported. The results are presented in a form suitable for use in the
validation of Monte Carlo generators of neutrino--nucleus interactions.Comment: 17 pages, 5 figure
The Scientific Foundations of Forecasting Magnetospheric Space Weather
The magnetosphere is the lens through which solar space weather phenomena are focused and directed towards the Earth. In particular, the non-linear interaction of the solar wind with the Earth's magnetic field leads to the formation of highly inhomogenous electrical currents in the ionosphere which can ultimately result in damage to and problems with the operation of power distribution networks. Since electric power is the fundamental cornerstone of modern life, the interruption of power is the primary pathway by which space weather has impact on human activity and technology. Consequently, in the context of space weather, it is the ability to predict geomagnetic activity that is of key importance. This is usually stated in terms of geomagnetic storms, but we argue that in fact it is the substorm phenomenon which contains the crucial physics, and therefore prediction of substorm occurrence, severity and duration, either within the context of a longer-lasting geomagnetic storm, but potentially also as an isolated event, is of critical importance. Here we review the physics of the magnetosphere in the frame of space weather forecasting, focusing on recent results, current understanding, and an assessment of probable future developments.Peer reviewe
Projected WIMP sensitivity of the LUX-ZEPLIN dark matter experiment
LUX-ZEPLIN (LZ) is a next-generation dark matter direct detection experiment that will operate 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. Using a two-phase xenon detector with an active mass of 7 tonnes, LZ will search primarily for low-energy interactions with weakly interacting massive particles (WIMPs), which are hypothesized to make up the dark matter in our galactic halo. In this paper, the projected WIMP sensitivity of LZ is presented based on the latest background estimates and simulations of the detector. For a 1000 live day run using a 5.6-tonne fiducial mass, LZ is projected to exclude at 90% confidence level spin-independent WIMP-nucleon cross sections above 1.4 Ă 10-48cm2 for a 40 GeV/c2 mass WIMP.
Additionally, a 5Ï discovery potential is projected, reaching cross sections below the exclusion limits of recent experiments. For spin-dependent WIMP-neutron(-proton) scattering, a sensitivity of 2.3 Ă 10â43 cm2 (7.1 Ă 10â42 cm2) for a 40 GeV/c2
mass WIMP is expected. With underground installation well underway, LZ is on track for commissioning at SURF in 2020
RelaçÔes empĂricas entre caracterĂsticas dendromĂ©tricas da Caatinga brasileira e dados TM Landsat 5
O objetivo deste trabalho foi ajustar modelos para estimar caracterĂsticas dendromĂ©tricas da Caatinga brasileira a partir de dados do sensor TM do Landsat 5. Medidas de diĂąmetro e altura das ĂĄrvores foram obtidas de 60 parcelas de inventĂĄrio (400 m2), em dois municĂpios do Estado de Sergipe. A ĂĄrea basal e o volume de madeira foram estimados com uso de equação alomĂ©trica e de fator de forma (f = 0,9). As variĂĄveis explicativas foram obtidas do sensor TM, apĂłs correção radiomĂ©trica e geomĂ©trica, tendo-se considerado, na anĂĄlise, seis bandas espectrais, com resolução espacial de 30 m, alĂ©m dos Ăndices de razĂŁo simples (SR), de vegetação por diferença normalizada (NDVI) e de vegetação ajustado ao solo (Savi). Na escolha das melhores variĂĄveis explicativas, foram considerados coeficiente de determinação (R2), raiz do erro quadrĂĄtico mĂ©dio (RMSE) e critĂ©rio bayesiano de informação (CBI). A ĂĄrea basal por hectare nĂŁo apresentou correlação significativa com nenhuma das variĂĄveis explicativas utilizadas. Os melhores modelos foram ajustados Ă altura mĂ©dia das ĂĄrvores por parcela (R2 = 0,4; RMSE = 13%) e ao volume de madeira por hectare (R2 = 0,6; RMSE = 42%). As mĂ©tricas derivadas do sensor TM do Landsat 5 tĂȘm grande potencial para explicar variaçÔes de altura mĂ©dia das ĂĄrvores e do volume de madeira por hectare, em remanescentes de Caatinga situados no Nordeste brasileiro
On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection
A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)
Development and characterization of polymorphic microsatellite markers in taro (Colocasia esculenta)
Microsatellite-containing sequences were isolated from enriched genomic libraries of taro (Colocasia esculenta (L.) Schott). The sequencing of 269 clones yielded 77 inserts containing repeat motifs. The majority of these (81.7%) were dinucleotide or trinucleotide repeats. The GT/CA repeat motif was the most common, accounting for 42% of all repeat types. From a total of 43 primer pairs designed, 41 produced markers within the expected size range. Sixteen (39%) were polymorphic when screened against a restricted set of taro genotypes from Southeast Asia and Oceania, with an average of 3.2 alleles detected on each locus. These markers represent a useful resource for taro germplasm management, genome mapping, and marker-assisted selection
TRY plant trait database â enhanced coverage and open access
Plant traitsâthe morphological, anatomical, physiological, biochemical and phenological characteristics of plantsâdetermine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of traitâbased plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traitsâalmost complete coverage for âplant growth formâ. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and traitâenvironmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
New insights into the genetic etiology of Alzheimer's disease and related dementias
Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE Δ4 allele
- âŠ