The search for astrophysical high-energy neutrinos is one of the most important approaches to pin-point the sources of cosmic rays. The advantage of using these neutral and only weakly-interacting ...particles as messengers in order to look deep into the sources themselves is at the same time the main challenge, as extremely large detectors are needed to measure a significant signal. With the finalization of the large underground detectors IceCube and ANTARES, the quantity and the quality of the recorded data are now at a stage where many analyses have a sensitivity limited by the systematic error rather than statistical uncertainties. Such an error source is the Monte Carlo description of the lepton energy losses before a lepton reaches the detector and of all leptons within the detector. A very accurate simulation of the propagation of muons through large amount of matter is needed because a muon may sustain hundreds of interactions before it is detected by the experiment. Requirements on the precision of the muon propagation code are very stringent. A stochastical correct description of the series of lepton interactions within the detector is needed for a correct conclusion from the measured signature to the lepton energy respectively neutrino energy. In this paper, the Monte Carlo code PROPOSAL (Propagator with optimal precision and optimized speed for all leptons) is presented as a public tool for muon propagation through transparent media. Up-to-date cross sections for ionization, bremsstrahlung, photonuclear interactions, electron pair production, Landau–Pomeranchuk–Migdal and Ter-Mikaelian effects, muon and tau decay, as well as Molière scattering are implemented for different parametrizations. Thus, a full study of the systematic uncertainties is possible from the theoretical description of lepton energy loss in the context of high-energy neutrino analyses and other astroparticle physics experiments that rely on the proper description of lepton propagation. A numerical precision of better than 10−6 is achieved, setting the systematic error for high-energy neutrino analyses to a minimum from the numerical prospective.
•Vertically aligned carbon nanofibers were intercalated with SiO2 for mechanical strength and isolation of individual electrodes.•Stable and robust electrochemical hydrogen peroxide sensor is stable ...and robust.•Five consecutive calibration curves were done with different hydrogen peroxide concentrations over a period of 3days without any deterioration in the electrochemical response.•The sensor was also used for the measurement of hydrogen peroxide as one of the by-products of the reaction of cholesterol oxidase with cholesterol and the sensor response exhibited linear behavior from 50μM to 1mM in cholesterol concentration.•In general, the electrochemical sensor is robust, stable, and reproducible, and the detection limit and sensitivity responses were among the best when compared with the literature.
A vertically aligned carbon nanofiber-based (VACNF) electrode platform was developed for an enzymeless hydrogen peroxide sensor. Vertical nanofibers have heights on the order of 2–3μm, and diameters that vary from 50 to 100nm as seen by atomic force microscopy. The VACNF was grown as individual, vertically, and freestanding structures using plasma-enhanced chemical vapor deposition. The electrochemical sensor, for the hydrogen peroxide measurement in solution, showed stability and reproducibility in five consecutive calibration curves with different hydrogen peroxide concentrations over a period of 3days. The detection limit was 66μM. The sensitivity for hydrogen peroxide electrochemical detection was 0.0906mAcm−2mM−1, respectively. The sensor was also used for the measurement of hydrogen peroxide as the by-product of the reaction of cholesterol with cholesterol oxidase as a biosensor application. The sensor exhibits linear behavior in the range of 50μM–1mM in cholesterol concentrations. The surface analysis and electrochemistry characterization is presented.
We report the first observation of an anisotropy in the arrival direction of cosmic rays with energies in the multi-TeV region in the Southern sky using data from the IceCube detector. Between 2007 ...June and 2008 March, the partially deployed IceCube detector was operated in a configuration with 1320 digital optical sensors distributed over 22 strings at depths between 1450 and 2450 m inside the Antarctic ice. IceCube is a neutrino detector, but the data are dominated by a large background of cosmic-ray muons. Therefore, the background data are suitable for high-statistics studies of cosmic rays in the southern sky. The data include 4.3 billion muons produced by downward-going cosmic-ray interactions in the atmosphere; these events were reconstructed with a median angular resolution of 3° and a median energy of ~20 TeV. Their arrival direction distribution exhibits an anisotropy in right ascension with a first-harmonic amplitude of (6.4 ± 0.2 stat. ± 0.8 syst.) × 10-4.
Understanding the chemical nature of the surface of carbon nanofibers (CNF) is critical in assessing their fundamental properties and tailoring them for the right application. To gain such knowledge, ...we present here a detailed X-ray adsorption spectroscopy (XAS) study accompanied by high resolution transmission electron microscopy (TEM) micrographs of two morphologically different CNF pairs (tetrahedral amorphous carbon (ta-C) grown “open structured” fibers and traditional bamboo-like “closed structured” fibers), where the surface chemical properties and structural features of the fibers are investigated in depth and the effects of nitric acid treatment on the fibers are revealed. The morphology of the fiber and/or the original seed- and adhesion layers markedly affect the response of the fibers to the acid treatment. Results also show that the nitric acid treatment increases the observed sp2 intensity and modifies the two types of fibers to become more-alike both structurally and with respect to their oxygen functionalities. The XAS and HRTEM results confirm that a short nitric acid treatment does not remove the Ni catalyst particle but, instead, oxidizes their surfaces, especially in the case of ta-C grown fibers.
Uptake of Government-promoted sanitation remains a challenge in India. We aimed to investigate a low-cost, theory-driven, behavioural intervention designed to increase latrine use and safe disposal ...of child faeces in India.
We did a cluster-randomised controlled trial between Jan 30, 2018, and Feb 18, 2019, in 66 rural villages in Puri, Odisha, India. Villages were eligible if not adjacent to another included village and not designated by the Government to be open-defecation free. All latrine-owning households in selected villages were eligible. We assigned 33 villages to the intervention via stratified randomisation. The intervention was required to meet a limit of US$20 per household and included a folk performance, transect walk, community meeting, recognition banners, community wall painting, mothers’ meetings, household visits, and latrine repairs. Control villages received no intervention. Neither participants nor field assessors were masked to study group assignment. We estimated intervention effects on reported latrine use and safe disposal of child faeces 4 months after completion of the intervention delivery using a difference-in-differences analysis and stratified results by sex. This study is registered at ClinicalTrials.gov, NCT03274245.
We enrolled 3723 households (1807 48·5% in the intervention group and 1916 51·5% in the control group). Analysis included 14 181 individuals (6921 48·8% in the intervention group and 7260 51·2% in the control group). We found an increase of 6·4 percentage points (95% CI 2·0–10·7) in latrine use and an increase of 15·2 percentage points (7·9–22·5) in safe disposal of child faeces. No adverse events were reported.
A low-cost behavioural intervention achieved modest increases in latrine use and marked increases in safe disposal of child faeces in the short term but was unlikely to reduce exposure to faecal pathogens to a level necessary to achieve health gains.
The Bill & Melinda Gates Foundation and International Initiative for Impact Evaluation.
Knowledge of soil hydraulic parameters and their spatiotemporal variation is crucial for estimating the water and solute fluxes across the land-atmosphere boundary and within the vadose zone at ...different scales. The objective of this study was to determine soil hydraulic conductivities saturated hydraulic conductivity, K(sat), and unsaturated hydraulic conductivity, K(psi) and their spatial and temporal variations in a clay-dominated biporous Vertisol near College Station, TX, using tension infiltrometers. The study was conducted within a 20- by 16-m plot across several seasons during a 21-mo period (May 2003-January 2005) to investigate the impact of varying disk sizes (measurement support) on K(psi), and the spatial and temporal variations of K(psi) under natural environmental conditions due to pore space evolution. Infiltration occurred in a bimodal fashion consisting of preferential flow (occurring at soil water pressure heads psi = -0.05 to 0 m) and matrix flow (at psi = -0.2 to -0.1 m). Biological and structural macropores present in the soil resulted in gravity-dominated flow near saturation (psi = -0.05 to 0 m) for all experiments. The Student's t-test of analysis of variance indicated that hydraulic conductivities were not affected by changes in the infiltration disk sizes. Although the K(psi) values at four different locations within the plot did not show significant spatial variability, they demonstrated strong temporal variation during the 21-mo period based on the evolution of natural environmental conditions due to seasonal precipitation, root growth and decay, and structural pore space dynamics. Temporal trends of K(psi) indicated that hydraulic conductivities close to saturation were positively correlated with antecedent moisture conditions reflecting liquid cohesion, water films bridging across cracking peds, and the activation of flow in biological and structural macroporosity in the biporous soil system.
The muon and anti-muon neutrino energy spectrum is determined from 2000–2003 AMANDA telescope data using regularised unfolding. This is the first measurement of atmospheric neutrinos in the energy ...range 2–200
TeV. The result is compared to different atmospheric neutrino models and it is compatible with the atmospheric neutrinos from pion and kaon decays. No significant contribution from charm hadron decays or extraterrestrial neutrinos is detected. The capabilities to improve the measurement of the neutrino spectrum with the successor experiment IceCube are discussed.
While atomic force microscopy (AFM) has become a promising tool for visualizing membrane morphology of cells, many studies have reported the presence of artifacts such as cliffs on the edges of ...cells. These artifacts shield important structural features such as lamellopodia, filopodia, microvilli and membrane ridges, which represent characteristic status in signaling processes such as spreading and activation. These cliff-like edges arise from a premature contact of the probe side contact with the cell prior to the probe top apex-cell contact. Carbon nanotube (CNT) modified AFM probes were utilized to address this drawback. Using rat basophilic leukemia (RBL) cells, this work revealed that CNT probes diminish cliff-like artifacts and enabled visualization of entire membrane morphology and structural features in three dimensions. The high aspect ratio of CNT probes provides a very effective remedy to the cliff-like artifacts as well as tip convolution of conventional probes, which shall enhance the validity and application of AFM in cellular biology research.
► When imaging cells, atomic force microscopy frequently encounters an artifact known as “side cliffs.” ► Using carbon nanotube (CNT) modified probes, this artifact can be completely eliminated. ► The origin and mechanism of elimination of this artifact are also discussed.
Predictions of nonequilibrium preferential flow and transport are limited as long as the fracture and the matrix pore system cannot be represented by separate hydraulic functions. Previous approaches ...to describe hydraulic properties of soils with bimodal or multimodal pore size distributions are still restricted to soils with a single porous continuum. The objective of this study was to develop and test a fitting procedure for estimating retention and conductivity functions for dual‐permeability models using bulk soil data. The estimation is based on a set of van Genuchten‐Mualem functions for the two pore systems. A stepwise procedure is carried out that (1) assumes 3 out of 11 parameters to be known, (2) determines initial values for the remaining eight parameters to be fitted, and (3) fits the set of hydraulic functions simultaneously to θ(h) and K(h) data to obtain the parameter estimates. This procedure was evaluated using a synthetic data set, and it was applied to laboratory‐measured θ(h) and K(h) data from a loamy Dystric Gleysol soil. The results show that the effect of a fracture pore system on the unsaturated hydraulic conductivity function might be underestimated if only observations of water retention are considered. The fitted dual‐continuum hydraulic conductivity functions match the unsaturated soil's conductivity data better than a bimodal single‐domain approach that predicts hydraulic conductivity based on fitted water retention functions. Moreover, the dual‐continuum functions provide hydraulic parameters for dual‐permeability preferential flow models.
Geiger-mode Avalanche Photodiodes (G-APD) bear the potential to significantly improve the sensitivity of Imaging Air Cherenkov Telescopes (IACT). We are currently building the First G-APD Cherenkov ...Telescope (FACT) by refurbishing an old IACT with a mirror area of 9.5 square meters and are constructing a new, fine-pixelized camera using novel G-APDs. The main goal is to evaluate the performance of a complete system by observing very high energy gamma-rays from the Crab Nebula. This is an important field test to check the feasibility of G-APD-based cameras to replace at some time the PMT-based cameras of planned future IACTs like AGIS and CTA. In this article, we present the basic design of such a camera as well as some important details.
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