Material radiopurity control in the XENONnT experiment.

The selection of low-radioactive construction materials is of the utmost importance for rare-event searches and thus critical to the XENONnT experiment. Results of an extensive radioassay program are reported, in which material samples have been screened with gamma-ray spectroscopy, mass spectrometry, and 222 Rn emanation measurements. Furthermore, the cleanliness procedures applied to remove or mitigate surface contamination of detector materials are described. Screening results, used as inputs for a XENONnT Monte Carlo simulation, predict a reduction of materials background ( ∼ 17%) with respect to its predecessor XENON1T. Through radon emanation measurements, the expected 222 Rn activity concentration in XENONnT is determined to be 4.2 ( - 0.7 + 0.5 )  µ Bq/kg, a factor three lower with respect to XENON1T. This radon concentration will be further suppressed by means of the novel radon distillation system.

222 Rn emanation measurements for the XENON1T experiment.

The selection of low-radioactive construction materials is of utmost importance for the success of low-energy rare event search experiments. Besides radioactive contaminants in the bulk, the emanation of radioactive radon atoms from material surfaces attains increasing relevance in the effort to further reduce the background of such experiments. In this work, we present the 222 Rn emanation measurements performed for the XENON1T dark matter experiment. Together with the bulk impurity screening campaign, the results enabled us to select the radio-purest construction materials, targeting a 222 Rn activity concentration of 10 µ Bq / kg in 3.2 t of xenon. The knowledge of the distribution of the 222 Rn sources allowed us to selectively eliminate problematic components in the course of the experiment. The predictions from the emanation measurements were compared to data of the 222 Rn activity concentration in XENON1T. The final 222 Rn activity concentration of ( 4.5 ± 0.1 ) µ Bq / kg in the target of XENON1T is the lowest ever achieved in a xenon dark matter experiment.

Search for Coherent Elastic Scattering of Solar

We report on a search for nuclear recoil signals from solar ^{8}B neutrinos elastically scattering off xenon nuclei in XENON1T data, lowering the energy threshold from 2.6 to 1.6 keV. We develop a variety of novel techniques to limit the resulting increase in backgrounds near the threshold. No significant ^{8}B neutrinolike excess is found in an exposure of 0.6 t×y. For the first time, we use the nondetection of solar neutrinos to constrain the light yield from 1-2 keV nuclear recoils in liquid xenon, as well as nonstandard neutrino-quark interactions. Finally, we improve upon world-leading constraints on dark matter-nucleus interactions for dark matter masses between 3 and 11 GeV c^{-2} by as much as an order of magnitude.

Constraining the Spin-Dependent WIMP-Nucleon Cross Sections with XENON1T.

We report the first experimental results on spin-dependent elastic weakly interacting massive particle (WIMP) nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases. No significant signal excess is observed, and a profile likelihood ratio analysis is used to set exclusion limits on the WIMP-nucleon interactions. This includes the most stringent constraint to date on the WIMP-neutron cross section, with a minimum of 6.3×10^{-42} cm^{2} at 30 GeV/c^{2} and 90% confidence level. The results are compared with those from collider searches and used to exclude new parameter space in an isoscalar theory with an axial-vector mediator.

First Results on the Scalar WIMP-Pion Coupling, Using the XENON1T Experiment.

We present first results on the scalar coupling of weakly interacting massive particles (WIMPs) to pions from 1 t yr of exposure with the XENON1T experiment. This interaction is generated when the WIMP couples to a virtual pion exchanged between the nucleons in a nucleus. In contrast to most nonrelativistic operators, these pion-exchange currents can be coherently enhanced by the total number of nucleons and therefore may dominate in scenarios where spin-independent WIMP-nucleon interactions are suppressed. Moreover, for natural values of the couplings, they dominate over the spin-dependent channel due to their coherence in the nucleus. Using the signal model of this new WIMP-pion channel, no significant excess is found, leading to an upper limit cross section of 6.4×10^{-46} cm^{2} (90% confidence level) at 30 GeV/c^{2} WIMP mass.

Light Dark Matter Search with Ionization Signals in XENON1T.

We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4 keV_{ee}, we observe <1 event/(tonne day keV_{ee}), which is more than 1000 times lower than in similar searches with other detectors. Despite observing a higher rate at lower energies, no DM or CEvNS detection may be claimed because we cannot model all of our backgrounds. We thus exclude new regions in the parameter spaces for DM-nucleus scattering for DM masses m_{χ} within 3-6 GeV/c^{2}, DM-electron scattering for m_{χ}>30 MeV/c^{2}, and absorption of dark photons and axionlike particles for m_{χ} within 0.186-1 keV/c^{2}.

Search for Light Dark Matter Interactions Enhanced by the Migdal Effect or Bremsstrahlung in XENON1T.

Direct dark matter detection experiments based on a liquid xenon target are leading the search for dark matter particles with masses above ∼5 GeV/c^{2}, but have limited sensitivity to lighter masses because of the small momentum transfer in dark matter-nucleus elastic scattering. However, there is an irreducible contribution from inelastic processes accompanying the elastic scattering, which leads to the excitation and ionization of the recoiling atom (the Migdal effect) or the emission of a bremsstrahlung photon. In this Letter, we report on a probe of low-mass dark matter with masses down to about 85 MeV/c^{2} by looking for electronic recoils induced by the Migdal effect and bremsstrahlung using data from the XENON1T experiment. Besides the approach of detecting both scintillation and ionization signals, we exploit an approach that uses ionization signals only, which allows for a lower detection threshold. This analysis significantly enhances the sensitivity of XENON1T to light dark matter previously beyond its reach.

Dark Matter Search Results from a One Ton-Year Exposure of XENON1T.

We report on a search for weakly interacting massive particles (WIMPs) using 278.8 days of data collected with the XENON1T experiment at LNGS. XENON1T utilizes a liquid xenon time projection chamber with a fiducial mass of (1.30±0.01) ton, resulting in a 1.0 ton yr exposure. The energy region of interest, [1.4,10.6] keV_{ee} ([4.9,40.9] keV_{nr}), exhibits an ultralow electron recoil background rate of [82_{-3}^{+5}(syst)±3(stat)] events/(ton yr keV_{ee}). No significant excess over background is found, and a profile likelihood analysis parametrized in spatial and energy dimensions excludes new parameter space for the WIMP-nucleon spin-independent elastic scatter cross section for WIMP masses above 6 GeV/c^{2}, with a minimum of 4.1×10^{-47} cm^{2} at 30 GeV/c^{2} and a 90% confidence level.

First Dark Matter Search Results from the XENON1T Experiment.

We report the first dark matter search results from XENON1T, a ∼2000-kg-target-mass dual-phase (liquid-gas) xenon time projection chamber in operation at the Laboratori Nazionali del Gran Sasso in Italy and the first ton-scale detector of this kind. The blinded search used 34.2 live days of data acquired between November 2016 and January 2017. Inside the (1042±12)-kg fiducial mass and in the [5,40] keV_{nr} energy range of interest for weakly interacting massive particle (WIMP) dark matter searches, the electronic recoil background was (1.93±0.25)×10^{-4} events/(kg×day×keV_{ee}), the lowest ever achieved in such a dark matter detector. A profile likelihood analysis shows that the data are consistent with the background-only hypothesis. We derive the most stringent exclusion limits on the spin-independent WIMP-nucleon interaction cross section for WIMP masses above 10 GeV/c^{2}, with a minimum of 7.7×10^{-47} cm^{2} for 35-GeV/c^{2} WIMPs at 90% C.L.

Lifetimes of (214)Po and (212)Po measured with Counting Test Facility at Gran Sasso National Laboratory.

The decays of (214)Po into (210)Pb and of (212)Po into (208)Pb tagged by the previous decays from (214)Bi and (212)Bi have been studied inserting quartz vials inside the Counting Test Facility (CTF) at the underground laboratory in Gran Sasso (LNGS). We find that the mean lifetime of (214)Po is (236.00 ± 0.42(stat) ± 0.15(syst)) µs and that of (212)Po is (425.1 ± 0.9(stat) ± 1.2(syst)) ns. Our results are compatible with previous measurements, have a much better signal to background ratio, and reduce the overall uncertainties.

Acute and chronic consequences of polidocanol foam injection in the lung in experimental animals.

OBJECTIVE: To assess the presence of pulmonary embolism and inflammation after polidocanol foam injection into the peripheral veins of rabbits. METHOD: The animals were treated with polidocanol foam (1 or 3 mg/kg) or vehicle. Early (15 minutes) and late (30 days) animals were evaluated by perfusional lung scintigraphy and histopathological examination. RESULTS: In the control group no alterations were found. After polidocanol foam injection it was observed that an important reduction of pulmonary perfusion in the early periods, was mainly in the left lung (P < 0.001), with consequent embolism in the histological evaluation. In late periods it was observed that the presence of thrombus was with fibrin in small veins, compatible with chronic thrombus and the presence of chronic pulmonary inflammation. CONCLUSIONS: The injection of polidocanol foam in experimental animals can induce venous embolism and chronic inflammatory infiltration.

First evidence of pep solar neutrinos by direct detection in Borexino.

We observed, for the first time, solar neutrinos in the 1.0-1.5 MeV energy range. We determined the rate of pep solar neutrino interactions in Borexino to be 3.1±0.6{stat}±0.3{syst} counts/(day·100 ton). Assuming the pep neutrino flux predicted by the standard solar model, we obtained a constraint on the CNO solar neutrino interaction rate of <7.9 counts/(day·100 ton) (95% C.L.). The absence of the solar neutrino signal is disfavored at 99.97% C.L., while the absence of the pep signal is disfavored at 98% C.L. The necessary sensitivity was achieved by adopting data analysis techniques for the rejection of cosmogenic {11}C, the dominant background in the 1-2 MeV region. Assuming the Mikheyev-Smirnov-Wolfenstein large mixing angle solution to solar neutrino oscillations, these values correspond to solar neutrino fluxes of (1.6±0.3)×10{8} cm{-2} s^{-1} and <7.7×10{8} cm{-2} s{-1} (95% C.L.), respectively, in agreement with both the high and low metallicity standard solar models. These results represent the first direct evidence of the pep neutrino signal and the strongest constraint of the CNO solar neutrino flux to date.

Precision measurement of the (7)Be solar neutrino interaction rate in Borexino.

The rate of neutrino-electron elastic scattering interactions from 862 keV (7)Be solar neutrinos in Borexino is determined to be 46.0±1.5(stat)(-1.6)(+1.5)(syst) counts/(day·100 ton). This corresponds to a ν(e)-equivalent (7)Be solar neutrino flux of (3.10±0.15)×10(9) cm(-2) s(-1) and, under the assumption of ν(e) transition to other active neutrino flavours, yields an electron neutrino survival probability of 0.51±0.07 at 862 keV. The no flavor change hypothesis is ruled out at 5.0 σ. A global solar neutrino analysis with free fluxes determines Φ(pp)=6.06(-0.06)(+0.02)×10(10) cm(-2) s(-1) and Φ(CNO)<1.3×10(9) cm(-2) s(-1) (95% C.L.). These results significantly improve the precision with which the Mikheyev-Smirnov-Wolfenstein large mixing angle neutrino oscillation model is experimentally tested at low energy.

Estudo anatômico da projeção cutânea do nervo mediano através de pontos topográficos / Anatomic study of the branching of the median nerve through topographic points

Atualmente, diversas vias de acesso têm sido empregadas na realização da cirurgia do canal do carpo, variando em e localização na palma da mão. Foram determinados pontos topográficos na palma da mão, visando estabelecer locais fixos e de simples identificação para, com isto, obter um local de fácil acesso ao retináculo dos flexores (RF), evitando comprometer qualquer estrutura no local do túnel do carpo. Os autores deste trabalho tomaram como base a técnica empregada por Serra et al (1997) e analizaram o estudo anatômico desta região para tornar a cirurgia do túnel do carpo ainda direitas e 10 esquerdas de cadáveres conservados em formadeído a 10% e operadas 10 mãos de paciente com Síndrome do túnel do carpo. Não se levou consideração as diferenças morfométricas de indivíduos étnicos. Em todas as peças estudadas identificou-se um ponto preciso , denominado X, sendo que a partir deste ponto localizou-se a margem distal do RF e a emergência da ramificação do nervo mediano (NM).

DNA fragment assembly using neural prediction techniques.

The paper describes an alternative approach to the fragment assembly problem. The key idea is to train a recurrent neural network to tracking the sequence of bases constituting a given fragment and to assign to a same cluster all the sequences which are well tracked by this network. We make use of a 3-layer Recurrent Perceptron and examine both edited sequences from a ftp site and artificial fragments from a common simulation software: the clusters we obtain exhibit interesting properties in terms of error filtering, stability and self consistency; we define as well, with a certain degree of approximation, a metric on the fragment set. The proposed assembly algorithm is susceptible to becoming an alternative method with the following properties: (i) high quality of the rebuilt genomic sequences, (ii) high parallelizability of the computing process with consequent drastic reduction of the running time.

Sensitivity to vecuronium after botulinum toxin administration.

When used to treat focal dystonias, botulinum toxin may cause a transient impairment of neuromuscular transmission in muscles distant from those injected. These systemic effects are not clinically evident, but should not be ignored when patients are exposed to other drugs or conditions that also impair neuromuscular transmission. A patient is described who underwent general anesthesia twice during treatment with botulinum toxin for a long history of blepharospasm. On both occasions, the neuromuscular block produced by vecuronium (0.05 mg kg-1) was monitored in the abductor digiti minimi muscle. Compared with that observed in 24 individuals who were free from neuromuscular problems, the patient's sensitivity to vecuronium was low 90 days after the seventh treatment with toxin and normal 8 days after the ninth. The possibility is considered that repeated treatments with the toxin may cause continuous remodeling of neuromuscular junctions and may cause the patient to develop some tolerance to the action of neuromuscular blockers.

Pioventriculitis asociada a derivaciones ventriculares / Pyoventriculitis associated to ventricular shunts

Las infecciones vinculadas a derivaciones de liquido cefalorraquideo (L.C.R) continúan siendo una seria complicación (4.5 al 15 por ciento) según las series revisadas). El objetivo de este trabajo fue determinar la distribución etiológica y analizar las alteraciones citoquímicas del L.C.R. según el germen hallado. Se analizaron retrospectivamene 50 episodios de pioventriucluitis ocurridos entre junio de 1992 y mayo de 1995. Las derivaciones ventriculares estuvieron indicadas en el 64 por ciento de los casos de hidrocefalia congénita, en el 24 por ciento por hidrocefalia secundaria a infección del sistema nervioso central (S.N.C) y en el 12 por ciento restante por hidrocefalia secundaria a tumores y hemorragias. Un 46 por ciento de las pioventriculitis se registraron en menores de un año. El 84 por ciento de los episodios ocurrió dentro de los seis meses de colocación del sistema con mayor incidencia en los primeros treinta diás; el 74 por ciento eran portadores de derivación ventrículo peritoneal. La etiología encontrada fue Staphylococcus coagulasa positivo (36 por ciento); Staphylococcus coagulasa negativo (34 por ciento) y bacilos Gram negativos (30 por ciento). La celularidad promedio observada en el L.C.R. diagnóstico fue de 116 células/mm3. para staphylococcus coagulasa positivo, 82 células/mm3 para Staphylococcus coagulasa negativo, y 319 células/mm3 para bacilos Gram negativos, existiendo una diferencia significtiva (p<0,05) entre la celularidad de las pioventriculitis producidas por Staphylococcus y aquellas producidas por bacilos Gram negativos, no así entre Staphylococcus coagulasa positivo y coagulasa negativo. El valor de la glucorraquia en el L.C.R. diagnóstico no mostró diferencias significativas entre los gérmenes hallados. Solo el 46 por ciento de los episodios presentaron al diagnóstico glucorraquia menor de 40 mg por ciento. Valores de glucorraquia bajos no indicaron infección persistente.