RESUMEN
We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4 million reactor ν[over ¯]_{e} inverse ß decay candidates observed over 1958 days of data collection. The installation of a flash analog-to-digital converter readout system and a special calibration campaign using different source enclosures reduce uncertainties in the absolute energy calibration to less than 0.5% for visible energies larger than 2 MeV. The uncertainty in the cosmogenic ^{9}Li and ^{8}He background is reduced from 45% to 30% in the near detectors. A detailed investigation of the spent nuclear fuel history improves its uncertainty from 100% to 30%. Analysis of the relative ν[over ¯]_{e} rates and energy spectra among detectors yields sin^{2}2θ_{13}=0.0856±0.0029 and Δm_{32}^{2}=(2.471_{-0.070}^{+0.068})×10^{-3} eV^{2} assuming the normal hierarchy, and Δm_{32}^{2}=-(2.575_{-0.070}^{+0.068})×10^{-3} eV^{2} assuming the inverted hierarchy.
RESUMEN
The Daya Bay experiment has observed correlations between reactor core fuel evolution and changes in the reactor antineutrino flux and energy spectrum. Four antineutrino detectors in two experimental halls were used to identify 2.2 million inverse beta decays (IBDs) over 1230 days spanning multiple fuel cycles for each of six 2.9 GW_{th} reactor cores at the Daya Bay and Ling Ao nuclear power plants. Using detector data spanning effective ^{239}Pu fission fractions F_{239} from 0.25 to 0.35, Daya Bay measures an average IBD yield σ[over ¯]_{f} of (5.90±0.13)×10^{-43} cm^{2}/fission and a fuel-dependent variation in the IBD yield, dσ_{f}/dF_{239}, of (-1.86±0.18)×10^{-43} cm^{2}/fission. This observation rejects the hypothesis of a constant antineutrino flux as a function of the ^{239}Pu fission fraction at 10 standard deviations. The variation in IBD yield is found to be energy dependent, rejecting the hypothesis of a constant antineutrino energy spectrum at 5.1 standard deviations. While measurements of the evolution in the IBD spectrum show general agreement with predictions from recent reactor models, the measured evolution in total IBD yield disagrees with recent predictions at 3.1σ. This discrepancy indicates that an overall deficit in the measured flux with respect to predictions does not result from equal fractional deficits from the primary fission isotopes ^{235}U, ^{239}Pu, ^{238}U, and ^{241}Pu. Based on measured IBD yield variations, yields of (6.17±0.17) and (4.27±0.26)×10^{-43} cm^{2}/fission have been determined for the two dominant fission parent isotopes ^{235}U and ^{239}Pu. A 7.8% discrepancy between the observed and predicted ^{235}U yields suggests that this isotope may be the primary contributor to the reactor antineutrino anomaly.
RESUMEN
This Letter reports a measurement of the flux and energy spectrum of electron antineutrinos from six 2.9 GWth nuclear reactors with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls in the Daya Bay experiment. Using 217 days of data, 296 721 and 41 589 inverse ß decay (IBD) candidates were detected in the near and far halls, respectively. The measured IBD yield is (1.55±0.04) ×10(-18) cm(2) GW(-1) day(-1) or (5.92±0.14) ×10(-43) cm(2) fission(-1). This flux measurement is consistent with previous short-baseline reactor antineutrino experiments and is 0.946±0.022 (0.991±0.023) relative to the flux predicted with the Huber-Mueller (ILL-Vogel) fissile antineutrino model. The measured IBD positron energy spectrum deviates from both spectral predictions by more than 2σ over the full energy range with a local significance of up to â¼4σ between 4-6 MeV. A reactor antineutrino spectrum of IBD reactions is extracted from the measured positron energy spectrum for model-independent predictions.
RESUMEN
This Letter reports an improved search for light sterile neutrino mixing in the electron antineutrino disappearance channel with the full configuration of the Daya Bay Reactor Neutrino Experiment. With an additional 404 days of data collected in eight antineutrino detectors, this search benefits from 3.6 times the statistics available to the previous publication, as well as from improvements in energy calibration and background reduction. A relative comparison of the rate and energy spectrum of reactor antineutrinos in the three experimental halls yields no evidence of sterile neutrino mixing in the 2×10^{-4}â²|Δm_{41}^{2}|â²0.3 eV^{2} mass range. The resulting limits on sin^{2}2θ_{14} are improved by approx imately a factor of 2 over previous results and constitute the most stringent constraints to date in the |Δm_{41}^{2}|â²0.2 eV^{2} region.
RESUMEN
We report a new measurement of electron antineutrino disappearance using the fully constructed Daya Bay Reactor Neutrino Experiment. The final two of eight antineutrino detectors were installed in the summer of 2012. Including the 404 days of data collected from October 2012 to November 2013 resulted in a total exposure of 6.9×10^{5} GW_{th} ton days, a 3.6 times increase over our previous results. Improvements in energy calibration limited variations between detectors to 0.2%. Removal of six ^{241}Am-^{13}C radioactive calibration sources reduced the background by a factor of 2 for the detectors in the experimental hall furthest from the reactors. Direct prediction of the antineutrino signal in the far detectors based on the measurements in the near detectors explicitly minimized the dependence of the measurement on models of reactor antineutrino emission. The uncertainties in our estimates of sin^{2}2θ_{13} and |Δm_{ee}^{2}| were halved as a result of these improvements. An analysis of the relative antineutrino rates and energy spectra between detectors gave sin^{2}2θ_{13}=0.084±0.005 and |Δm_{ee}^{2}|=(2.42±0.11)×10^{-3} eV^{2} in the three-neutrino framework.
RESUMEN
A search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment's unique configuration of multiple baselines from six 2.9 GW(th) nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the 10(-3) eV(2)<|Δm(41)(2) |< 0.3 eV(2) range. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. The derived limits on sin(2) 2θ(14) cover the 10(-3) eV(2) â² |Δm(41)(2)| â² 0.1 eV(2) region, which was largely unexplored.
RESUMEN
A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9 GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3) eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(µµ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.
RESUMEN
The Daya Bay Reactor Neutrino Experiment has measured a nonzero value for the neutrino mixing angle θ(13) with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 GWth reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With a 43,000 ton-GWth-day live-time exposure in 55 days, 10,416 (80,376) electron-antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is R=0.940±0.011(stat.)±0.004(syst.). A rate-only analysis finds sin(2)2θ(13)=0.092±0.016(stat.)±0.005(syst.) in a three-neutrino framework.
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An attempt has been made to assess the output of progesterone in mice by measuring the concentration of pregnanediol-3 alpha-glucuronide (PdGl in serial samples of unextracted urine. Longitudinal studies with 95 animals have shown that sufficient urine (greater than 40 microliter) can be obtained from individual animals (80% success rate) without stress every day or at intervals of 2 h. The sc administration of 50 microgram progesterone in lauric acid ethyl ester resulted in a 9-fold increase in the concentration of urinary PdGl (within 4 h) and a significantly elevated output for the next 26 h. During the induction of superovulation with PMS and hCG, the values of PdGl increased significantly (P less than 0.0005; by Student's t test) from 2.08 +/- 0.97 to 3.99 +/- 2.55 ng/ml (mean +/- SD) at the time of corpus luteum formation. There was a good correlation (r = 0.84; n = 154) between the values expressed as nanograms per ml urine and nanograms per mg creatinine. The results demonstrate that the concentration of PdGl in serial samples of urine may be used as an index of gonadal function in female mice.
Asunto(s)
Glucuronatos/orina , Pregnanodiol/análogos & derivados , Progesterona/metabolismo , Animales , Cuerpo Lúteo/fisiología , Creatinina/orina , Femenino , Ratones , Pregnanodiol/orina , Radioinmunoensayo , Esteroides/orina , Superovulación , Vagina/fisiologíaRESUMEN
Superficially similar cleavable targeting signals specify whether lumenal proteins are transported across the thylakoid membrane by a Sec- or delta pH-dependent pathway. A twin-arginine motif is essential but not sufficient to direct delta pH-dependent targeting; here we show that a second determinant is located in the hydrophobic region. A highly hydrophobic amino acid is found either two or three residues C-terminal to the twin-arginine in all known transfer peptides for the delta pH-dependent system, and substitution of this residue in the 23-kDa (23K) peptide markedly inhibits translocation. Further, whereas the insertion of twin-arginine in a Sec-dependent precursor does not permit efficient delta pH-dependent targeting, the simultaneous presence of a leucine at the +3 position (relative to the RR) enables the peptide to function as efficiently as an authentic transfer peptide. RRNVL, RRAAL and RRALA within a Sec targeting signal all support efficient delta pH-dependent targeting, RRNVA is less effective and RRNAA/RRNAG are totally ineffective. We conclude that the core signal for this pathway is a twin-arginine together with an adjacent hydrophobic determinant.
Asunto(s)
Arginina/metabolismo , Proteínas de la Membrana/metabolismo , Señales de Clasificación de Proteína/metabolismo , Secuencia de Aminoácidos , Arabidopsis/metabolismo , Transporte Biológico , Concentración de Iones de Hidrógeno , Proteínas de la Membrana/química , Datos de Secuencia Molecular , Mutagénesis , Señales de Clasificación de Proteína/químicaRESUMEN
Obstructed labor due to a large sacrococcygeal tumor is reported. A technique of transabdominal intrauterine reduction in the size of the tumor to allow delivery of the infant in satisfactory condition is described. The method and the successful outcome have not previously been reported. It is recommended as a combined obstetric and pediatric surgical solution to similar complications. The complication should be circumvented by ultrasonographic screening of high-risk or suspect cases and of women entering a high-risk environment for delivery.
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Enfermedades Fetales , Complicaciones del Trabajo de Parto , Región Sacrococcígea , Teratoma/cirugía , Adulto , Episiotomía , Femenino , Parto Domiciliario , Humanos , Recién Nacido , Enfermedades del Recién Nacido/cirugía , EmbarazoRESUMEN
On 27 December 2004, a giant gamma flare from the Soft Gamma-Ray Repeater 1806-20 saturated many satellite gamma-ray detectors, being the brightest transient event ever observed in the Galaxy. AMANDA-II was used to search for down-going muons indicative of high-energy gammas and/or neutrinos from this object. The data revealed no significant signal, so upper limits (at 90% C.L.) on the normalization constant were set: 0.05(0.5) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the gamma flux and 0.4(6.1) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the high-energy neutrino flux.
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Four weighing lysimeters (1.8 m diameter, 1 m depth, weight 3.5-4.5 Mg) were used to estimate transpiration from single, isolated trees. The weighing mechanism incorporated a simple, new system of wire ropes around torsion tubes, producing a lever action through which most of the weight was tared off with a counter weight. Weight differences measured by load cell under the main lever arm were unaffected by hysteresis or temperature change. Sensitivity better than 100 g was achieved in windless conditions. Daily measurements over yearly periods (trees could be regularly replaced using extra pots) revealed both sigmoid seasonal patterns, and sigmoid diurnal changes closely related to micrometeorological variables, for a range of tree species. Measurements taken during rainfall demonstrated that an isolated tree intercepts considerably more precipitation than does a uniform crop covering the same ground area, and that substantial evaporation from the canopy takes place while it is raining.
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The patient required bilateral salpingoophorectomy for pain caused by the late effects of pelvic infection. Division of adhesions was followed by torrential bleeding from the gluteal tributaries of the right internal iliac vein aggravated by the partial retraction of those veins into the subgluteal region. Measures to control the bleeding and the late complications are described.
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Pérdida de Sangre Quirúrgica/prevención & control , Transfusión Sanguínea , Vena Ilíaca , Complicaciones Intraoperatorias , Adulto , Femenino , Humanos , Histerectomía , Ligadura , Quistes Ováricos/cirugía , Ovariectomía , Enfermedad Inflamatoria Pélvica/cirugía , Complicaciones Posoperatorias , Nervio Ciático/lesiones , Stents , Adherencias Tisulares , Uréter/lesionesRESUMEN
Values for the temperature-dependent heat capacity of wood were applied to correct the coefficient used to calculate sap velocity from heat pulse velocity, leading to values at 20 degrees C about 5% smaller than values calculated with the widely employed algorithm of Edwards and Warwick. Errors are larger at lower temperatures (7% at 10 degrees C) and so are more problematic at night and during cold periods.
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A study of 115 gravid patients who required cervical cerclage indicated that the optimum time to perform the surgical procedure was between the fourteenth and eighteenth weeks. If the operation is delayed until later in the second trimester, the incidence of chorioamnionitis is increased 2.6-fold, and premature rupture of the membranes prior to the thirty-second week of gestation is trebled. Amniocentesis performed in nine patients with chorioamnionitis and intact membranes after cerclage demonstrated the polymicrobial nature of the amniotic fluid infection. The isolation of such organisms at Bacteroides bivius, Eubacterium lentum, and Staphylococcus epidermidis indicates their potential importance in chorioamnionitis. Early recourse to amniocentesis is recommended when chorioamnionitis is suspected, and, moreover, prophylactic antibiotics should be used when cerclage is performed after the eighteenth week of pregnancy.
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Aborto Habitual/prevención & control , Complicaciones Infecciosas del Embarazo/etiología , Incompetencia del Cuello del Útero/cirugía , Adolescente , Adulto , Amnios , Líquido Amniótico/microbiología , Infecciones Bacterianas/etiología , Corion , Femenino , Rotura Prematura de Membranas Fetales/etiología , Viabilidad Fetal , Humanos , Inflamación/etiología , Complicaciones Posoperatorias , Embarazo , Segundo Trimestre del Embarazo , Factores de TiempoRESUMEN
A unified nomenclature for use in heat pulse measurement of sap flow is proposed. This unified nomenclature overcomes fundamental misunderstandings of the physics of heat and sap movement in wood. The nomenclature is also appropriate to other methodologies for sap flow measurement, such as heat balance methods.
RESUMEN
Flow of water in a single tree was modeled in terms of the Darcy equation using a catena of four compartments: root, stem (further divided into discs), branches and leaves. Within each compartment or disc, water content was related to both water potential and conductivity of the xylem tissue using power or logarithmic functions, thus introducing both capacitance and variable resistance to flow in the model. Transpiration from the leaves to the atmosphere was used as the upper boundary to the model, and the soil-root interface as the lower boundary. Parameters for the water content, water potential and conductivity functions, together with physical dimensions were obtained by direct measurement or from the literature. A sensitivity analysis showed that the largest changes in simulated water potential and flow were associated with changes in the parameters directly controlling conductivity. Simulation of both smoothed diurnal changes and stepwise changes showed a phase lag down the tree, with flow tending to approach a steady state, but with changes in the gradients of water potential, water content and conductivity. A preliminary test of the model was made against field data using the Penman-Monteith equation to estimate the transpiration rate in a well-watered Pinus contorta Dougl. stand. Stem flow, water potential and water content were measured directly on a representative tree, which was subsequently harvested to provide dimensions and laboratory estimations of the parameters in the functions by direct measurement.
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We digested chromosomal DNAs from 12 Campylobacter strains (C. jejuni, 4 strains; C. coli, 2 strains; C. fetus subsp. fetus, 2 strains; C. hyointestinalis, 2 strains; and C. upsaliensis, 2 strains) and from 4 Helicobacter strains (H. pylori, 2 strains; and H. mustelae, 2 strains) with HindIII, SstI, BamHI, DpnI, MboI, and Sau3AI. Restriction fragments were then separated by electrophoresis in 1% agarose or 10% polyacrylamide gels. Only DNAs from three Campylobacter species (C. jejuni, C. coli, and C. upsaliensis) were digested with DpnI (an enzyme that recognizes only methylated adenine in GATC sequences). We used MboI and Sau3AI to confirm these findings.
Asunto(s)
Adenina/metabolismo , Campylobacter/genética , Cromosomas Bacterianos/metabolismo , ADN Bacteriano/metabolismo , Composición de Base , MetilaciónRESUMEN
LIGHT is a member of the TNF cytokine superfamily that signals through the lymphotoxin (LT)beta receptor and the herpesvirus entry mediator. LIGHT may function as a costimulatory factor for the activation of lymphoid cells and as a deterrent to infection by herpesvirus, which may provide significant selective pressure shaping the evolution of LIGHT. Here, we define the molecular genetics of the human LIGHT locus, revealing its close linkage to the TNF superfamily members CD27 ligand and 4-1BB ligand, and the third complement protein (C3), which positions LIGHT within the MHC paralog on chromosome 19p13.3. An alternately spliced isoform of LIGHT mRNA that encodes a transmembrane-deleted form is detected in activated T cells and gives rise to a nonglycosylated protein that resides in the cytosol. Furthermore, membrane LIGHT is shed from the cell surface of human 293 T cells. These studies reveal new mechanisms involved in regulating the physical forms and cellular compartmentalization of LIGHT that may contribute to the regulation and biological function of this cytokine.