Detecting shielded special nuclear material, such as nuclear explosives, is a difficult challenge pursued by non-proliferation, anti-terrorism, and nuclear security programs worldwide. Interrogation with intense fast-neutron pulses is a promising method to characterize concealed nuclear material rapidly but is limited by suitable source availability and proven instrumentation. In this study we have pioneered a demonstration of such an interrogation method using a high-intensity, short-pulse, laser-driven neutron source that offers potential benefits compared to conventional neutron sources.
View Article and Find Full Text PDFFactors associated with neurotoxin treatments in children with cerebral palsy (CP) are poorly studied. We developed and externally validated a prediction model to identify the prognostic phenotype of children with CP who require neurotoxin injections. We conducted a longitudinal, international, multicenter, double-blind descriptive study of 165 children with CP (mean age 16.
View Article and Find Full Text PDFPortugal's first Mobile Drug Consumption Room (MDCR) has been operating for over three years in two Lisbon neighborhoods. This qualitative study first creates a baseline understanding of community perceptions concerning the acceptability of and expectations surrounding drug consumption rooms in the communities of intervention. Then, at least six months after the initial interviews, it determines how these perceptions changed and what changes participants perceive in the neighborhoods.
View Article and Find Full Text PDFIndigenous trees play key roles in West African landscapes, such as the néré tree (Parkia biglobosa (Jacq.) R.Br.
View Article and Find Full Text PDFObjective: To investigate the seasonal variations of women's dietary diversity (WDD) (items consumed and food supply) and its linkages with agriculture, market and wild resources.
Design: A cohort of 300 women was followed-up over a year to investigate WDD and food sources (production, purchase or foraging). Monthly qualitative 24 h recalls allowed computing WDD Scores from a standard 10-food groups (FG) classification (WDDS-10).
Four emergency shelters were instituted in Lisbon during COVID-19, and are still in operation. Between March and August 2020, they served over 600 people. The shelters host a diverse population, including people experiencing homelessness, foreigners, LGBTI + people, those with reduced mobility, couples, those with pets, and People Who Use Drugs, including alcohol (henceforth PWUD).
View Article and Find Full Text PDFTyrannosaurus rex and other tyrannosaurid dinosaurs were apex predators during the latest Cretaceous, which combined giant size and advanced neurosensory systems. Computed tomography (CT) data have shown that tyrannosaurids had a trademark system of a large brain, large olfactory bulbs, elongate cochlear ducts, and expansive endocranial sinuses surrounding the brain and sense organs. Older, smaller tyrannosauroid relatives of tyrannosaurids developed some, but not all, of these features, raising the hypothesis that tyrannosaurid-style brains evolved before the enlarged tyrannosaurid-style sinuses, which might have developed only with large body size.
View Article and Find Full Text PDFManaging infections of sheep with anthelmintic resistant gastrointestinal nematodes (GIN) is a major challenge for sheep producers in Western Europe. New methods of grazing management have been poorly explored as a component of an integrated and sustainable control of these parasites. Therefore, the purpose of this study was to evaluate the effect of two different types of grazing systems of sheep (intensive cell grazing versus conventional rotational grazing) on GIN infections over two years in a farm located in a temperate environment of Western France.
View Article and Find Full Text PDFBackground: Ahead of opening Portugal's first mobile drug consumption room (MDCR) in Lisbon, information from People Who Use Drugs (PWUD) and local community members was necessary to determine current needs and shape the intervention. A participatory and peer-led process was ensured at all stages of data gathering and planning of the intervention.
Methods: Prospective clients were surveyed to determine their willingness to use the service and preferences for use and to gain sociodemographic information.
Compact, bright neutron sources are opening up several emerging applications including detection of nuclear materials for national security applications. At Los Alamos National Laboratory, we have used a short-pulse laser to accelerate deuterons in the relativistic transparency regime. These deuterons impinge on a beryllium converter to generate neutrons.
View Article and Find Full Text PDFIntense lasers can accelerate protons in sufficient numbers and energy that the resulting beam can heat materials to exotic warm (10 s of eV temperature) states. Here we show with experimental data that a laser-driven proton beam focused onto a target heated it in a localized spot with size strongly dependent upon material and as small as 35 μm radius. Simulations indicate that cold stopping power values cannot model the intense proton beam transport in solid targets well enough to match the large differences observed.
View Article and Find Full Text PDFOn 27 August 2016, the Juno spacecraft acquired science observations of Jupiter, passing less than 5000 kilometers above the equatorial cloud tops. Images of Jupiter's poles show a chaotic scene, unlike Saturn's poles. Microwave sounding reveals weather features at pressures deeper than 100 bars, dominated by an ammonia-rich, narrow low-latitude plume resembling a deeper, wider version of Earth's Hadley cell.
View Article and Find Full Text PDFBoth dust and silica phytoliths have been shown to contribute to reducing tooth volume during chewing. However, the way and the extent to which they individually contribute to tooth wear in natural conditions is unknown. There is still debate as to whether dental microwear represents a dietary or an environmental signal, with far-reaching implications on evolutionary mechanisms that promote dental phenotypes, such as molar hypsodonty in ruminants, molar lengthening in suids or enamel thickening in human ancestors.
View Article and Find Full Text PDFWhile grazing as a selective factor towards hypsodont dentition on mammals has gained a lot of attention, the importance of fruits and seeds as fallback resources for many browsing ungulates has caught much less attention. Controlled-food experiments, by reducing the dietary range, allow for a direct quantification of the effect of each type of items separately on enamel abrasion. We present the results of a dental microwear texture analysis on 40 ewes clustered into four different controlled diets: clover alone, and then three diets composed of clover together with either barley, corn, or chestnuts.
View Article and Find Full Text PDFTable-top laser-plasma ion accelerators have many exciting applications, many of which require ion beams with simultaneous narrow energy spread and high conversion efficiency. However, achieving these requirements has been elusive. Here we report the experimental demonstration of laser-driven ion beams with narrow energy spread and energies up to 18 MeV per nucleon and ∼5% conversion efficiency (that is 4 J out of 80-J laser).
View Article and Find Full Text PDFPhotosynthesis is Nature's major process for converting solar into chemical energy. One of the key players in this process is the multiprotein complex photosystem I (PSI) that through absorption of incident photons enables electron transfer, which makes this protein attractive for applications in bioinspired photoactive hybrid materials. However, the efficiency of PSI is still limited by its poor absorption in the green part of the solar spectrum.
View Article and Find Full Text PDFWith the development of several novel heating sources, scientists can now heat a small sample isochorically above 10,000 K. Although matter at such an extreme state, known as warm dense matter, is commonly found in astrophysics (e.g.
View Article and Find Full Text PDFRecently, photoactive proteins have gained a lot of attention due to their incorporation into bioinspired (photo)electrochemical and solar cells. This paper describes the measurement of the asymmetry of current transport of self-assembled monolayers (SAMs) of the entire photosystem I (PSI) protein complex (not the isolated reaction center, RCI), on two different "director SAMs" supported by ultraflat Au substrates. The director SAMs induce the preferential orientation of PSI, which manifest as asymmetry in tunneling charge-transport.
View Article and Find Full Text PDFWe present a detailed study of the use of a non-parallel, inhomogeneous magnetic field spectrometer for the investigation of laser-accelerated ion beams. Employing a wedged yoke design, we demonstrate the feasibility of an in-situ self-calibration technique of the non-uniform magnetic field and show that high-precision measurements of ion energies are possible in a wide-angle configuration. We also discuss the implications of a stacked detector system for unambiguous identification of different ion species present in the ion beam and explore the feasibility of detection of high energy particles beyond 100 MeV/amu in radiation harsh environments.
View Article and Find Full Text PDFThe origin of Titan's nitrogen-rich atmosphere is thought to be ammonia ice, but this has not yet been confirmed. Furthermore, it is uncertain whether the building blocks of Titan formed within the Saturnian subnebula or in the colder protosolar nebula (PSN). Recent measurements of the nitrogen isotope ratio in cometary ammonia, combined with evolutionary constraints on the nitrogen isotopes in Titan's atmosphere provide firm evidence that the nitrogen in Titan's atmosphere must have originated as ammonia ice formed in the PSN under conditions similar to that of cometary formation.
View Article and Find Full Text PDFThe large multiprotein complex, photosystem I (PSI), which is at the heart of light-dependent reactions in photosynthesis, is integrated as the active component in a solid-state organic photovoltaic cell. These experiments demonstrate that photoactive megadalton protein complexes are compatible with solution processing of organic-semiconductor materials and operate in a dry non-natural environment that is very different from the biological membrane.
View Article and Find Full Text PDFNeutrons are unique particles to probe samples in many fields of research ranging from biology to material sciences to engineering and security applications. Access to bright, pulsed sources is currently limited to large accelerator facilities and there has been a growing need for compact sources over the recent years. Short pulse laser driven neutron sources could be a compact and relatively cheap way to produce neutrons with energies in excess of 10 MeV.
View Article and Find Full Text PDFOptic nerve involvement may occur in various infectious diseases, but is rarely reported after infection by the human immunodeficiency virus (HIV). We report the atypical case of a 38-year-old patient in whom the presenting features of HIV infection were due to a bilateral optic neuropathy associated with macular subretinal fluid and cystoid macular edema, which responded well to antiretroviral therapy.
View Article and Find Full Text PDFExperimental data from the Trident Laser facility is presented showing quasimonoenergetic carbon ions from nm-scaled foil targets with an energy spread of as low as ±15% at 35 MeV. These results and high-resolution kinetic simulations show laser acceleration of quasimonoenergetic ion beams by the generation of ion solitons with circularly polarized laser pulses (500 fs, λ=1054 nm). The conversion efficiency into monoenergetic ions is increased by an order of magnitude compared with previous experimental results, representing an important step towards applications such as ion fast ignition.
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