Understanding Brazil’s Oil Industry: Policy Dynamics and Self-Sufficiency

This paper focuses on the premise that despite changes in the type of Brazil’s governmental leadership—and their respective political priorities and economic policies—the nation has engaged in a continual movement toward the fulfillment of its vision of self-sufficiency in oil, for the purposes of economic development as well as those of national security. After attaining self-sufficiency in oil in 2006, new offshore discoveries beginning in 2007 have placed Brazil among the world’s top ten countries in oil reserves. In light of these discoveries, the Brazilian government is considering a new legal framework with respect to its offshore oil reserves. This paper provides historical evidence to substantiate the premise and assesses the implications of the new framework in relation to continuing the country’s historical goal and achievement of self-sufficiency in oil

Mapping Nanostructural Variations in Silk by Secondary Electron Hyperspectral Imaging

Nanostructures underpin the excellent properties of silk. Although the bulk nanocomposition of silks has been well studied, direct evidence of the spatial variation of nanocrystalline (ordered) and amorphous (disordered) structures has remained elusive. Here we demonstrate that secondary electron hyperspectral imaging, can be exploited for direct imaging of hierarchical structures in carbon based materials which cannot be revealed by any other standard characterization methods. Applying this technique to silks from domesticated (Bombyx mori) and wild (Antheraea mylitta) silkworms, we report a variety of previously unseen features which highlight the local interplay between ordered and disordered structures. We conclude that our technique is able to differentiate composition on the nanoscale and enables in-depth studies into the relationship between morphology and performance of these complex biopolymer systems

Overview of the techniques used for the study of non-terrestrial bodies: Proposition of novel non-destructive methodology

Meteorites and impact glasses have been largely analysed using different techniques, but most studies have been focused on their geologicalemineralogical characterization and isotopic ratios, mainly of a destructive nature. However, much more information can be gained by applying novel non-destructive analytical procedures and techniques that have been scarcely used to analyse these materials. This overview presents some new methodologies to study these materials and compares these new approaches with the commonly used ones. Techniques such as X-Ray Fluorescence (XRF) and Laser Induced Breakdown Spectroscopy (LIBS), for elemental characterization, the hyphenated Raman spectroscopy- SEM/EDS and the combination of them, allow extracting simultaneous information from elemental, molecular and structural data of the studied sample; furthermore, the spectroscopic image capabilities of such techniques allow a better understanding of the mineralogical distribution. © 2017 Elsevier B.V. All rights reserved.Ministerio de Economía, Industria y Competitividad (project ESP2014-56138-C3-2-R

Detector signal characterization with a Bayesian network in XENONnT

We developed a detector signal characterization model based on a Bayesian network trained on the waveform attributes generated by a dual-phase xenon time projection chamber. By performing inference on the model, we produced a quantitative metric of signal characterization and demonstrate that this metric can be used to determine whether a detector signal is sourced from a scintillation or an ionization process. We describe the method and its performance on electronic-recoil (ER) data taken during the first science run of the XENONnT dark matter experiment. We demonstrate the first use of a Bayesian network in a waveform-based analysis of detector signals. This method resulted in a 3% increase in ER event-selection efficiency with a simultaneously effective rejection of events outside of the region of interest. The findings of this analysis are consistent with the previous analysis from XENONnT, namely a background-only fit of the ER data

Searching for Heavy Dark Matter near the Planck Mass with XENON1T

Multiple viable theoretical models predict heavy dark matter particles with a mass close to the Planck mass, a range relatively unexplored by current experimental measurements. We use 219.4 days of data collected with the XENON1T experiment to conduct a blind search for signals from multiply interacting massive particles (MIMPs). Their unique track signature allows a targeted analysis with only 0.05 expected background events from muons. Following unblinding, we observe no signal candidate events. This Letter places strong constraints on spin-independent interactions of dark matter particles with a mass between 1×10$^{12}$ and 2×10$^{17}$  GeV/c$^2$. In addition, we present the first exclusion limits on spin-dependent MIMP-neutron and MIMP-proton cross sections for dark matter particles with masses close to the Planck scale

First Dark Matter Search with Nuclear Recoils from the XENONnT Experiment

We report on the first search for nuclear recoils from dark matter in the form of weakly interacting massive particles (WIMPs) with the XENONnT experiment, which is based on a two-phase time projection chamber with a sensitive liquid xenon mass of 5.9 ton. During the (1.09±0.03)  ton yr exposure used for this search, the intrinsic $^{85}$Kr and $^{222}$Rn concentrations in the liquid target are reduced to unprecedentedly low levels, giving an electronic recoil background rate of (15.8±1.3)  events/ton yr keV in the region of interest. A blind analysis of nuclear recoil events with energies between 3.3 and 60.5 keV finds no significant excess. This leads to a minimum upper limit on the spin-independent WIMP-nucleon cross section of 2.58×10$^{47}$  cm$^2$ for a WIMP mass of 28  GeV/c$^2$ at 90% confidence level. Limits for spin-dependent interactions are also provided. Both the limit and the sensitivity for the full range of WIMP masses analyzed here improve on previous results obtained with the XENON1T experiment for the same exposure

Searching for Heavy Dark Matter near the Planck Mass with XENON1T

Multiple viable theoretical models predict heavy dark matter particles with a mass close to the Planck mass, a range relatively unexplored by current experimental measurements. We use 219.4 days of data collected with the XENON1T experiment to conduct a blind search for signals from Multiply-Interacting Massive Particles (MIMPs). Their unique track signature allows a targeted analysis with only 0.05 expected background events from muons. Following unblinding, we observe no signal candidate events. This work places strong constraints on spin-independent interactions of dark matter particles with a mass between 1$\times$10$^{12}\,$GeV/c$^2$ and 2$\times$10$^{17}\,$GeV/c$^2$. In addition, we present the first exclusion limits on spin-dependent MIMP-neutron and MIMP-proton cross-sections for dark matter particles with masses close to the Planck scale.Comment: 7 pages, 6 figure

Search for events in XENON1T associated with Gravitational Waves

We perform a blind search for particle signals in the XENON1T dark matter detector that occur close in time to gravitational wave signals in the LIGO and Virgo observatories. No particle signal is observed in the nuclear recoil, electronic recoil, CE$\nu$NS, and S2-only channels within $\pm$ 500 seconds of observations of the gravitational wave signals GW170104, GW170729, GW170817, GW170818, and GW170823. We use this null result to constrain mono-energetic neutrinos and Beyond Standard Model particles emitted in the closest coalescence GW170817, a binary neutron star merger. We set new upper limits on the fluence (time-integrated flux) of coincident neutrinos down to 17 keV at 90% confidence level. Furthermore, we constrain the product of coincident fluence and cross section of Beyond Standard Model particles to be less than $10^{-29}$ cm$^2$/cm$^2$ in the [5.5-210] keV energy range at 90% confidence level

Design and performance of the field cage for the XENONnT experiment

The precision in reconstructing events detected in a dual-phase time projection chamber depends on an homogeneous and well understood electric field within the liquid target. In the XENONnT TPC the field homogeneity is achieved through a double-array field cage, consisting of two nested arrays of field shaping rings connected by an easily accessible resistor chain. Rather than being connected to the gate electrode, the topmost field shaping ring is independently biased, adding a degree of freedom to tune the electric field during operation. Two-dimensional finite element simulations were used to optimize the field cage, as well as its operation. Simulation results were compared to $^{83m} Kr$ calibration data. This comparison indicates an accumulation of charge on the panels of the TPC which is constant over time, as no evolution of the reconstructed position distribution of events is observed. The simulated electric field was then used to correct the charge signal for the field dependence of the charge yield. This correction resolves the inconsistent measurement of the drift electron lifetime when using different calibrations sources and different field cage tuning voltages

International genome-wide meta-analysis identifies new primary biliary cirrhosis risk loci and targetable pathogenic pathways.

Primary biliary cirrhosis (PBC) is a classical autoimmune liver disease for which effective immunomodulatory therapy is lacking. Here we perform meta-analyses of discovery data sets from genome-wide association studies of European subjects (n=2,764 cases and 10,475 controls) followed by validation genotyping in an independent cohort (n=3,716 cases and 4,261 controls). We discover and validate six previously unknown risk loci for PBC (Pcombined<5 × 10(-8)) and used pathway analysis to identify JAK-STAT/IL12/IL27 signalling and cytokine-cytokine pathways, for which relevant therapies exist