Experimental investigation of geologically produced antineutrinos with KamLAND

The detection of electron antineutrinos produced by natural radioactivity in the Earth could yield important geophysical information. The Kamioka liquid scintillator antineutrino detector (KamLAND) has the sensitivity to detect electron antineutrinos produced by the decay of 238U and 232Th within the Earth. Earth composition models suggest that the radiogenic power from these isotope decays is 16 TW, approximately half of the total measured heat dissipation rate from the Earth. Here we present results from a search for geoneutrinos with KamLAND. Assuming a Th/U mass concentration ratio of 3.9, the 90 per cent confidence interval for the total number of geoneutrinos detected is 4.5 to 54.2. This result is consistent with the central value of 19 predicted by geophysical models. Although our present data have limited statistical power, they nevertheless provide by direct means an upper limit (60 TW) for the radiogenic power of U and Th in the Earth, a quantity that is currently poorly constrained.

First results from KamLAND: evidence for reactor antineutrino disappearance

KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.

Indication of reactor ν(e) disappearance in the Double Chooz experiment

The Double Chooz experiment presents an indication of reactor electron antineutrino disappearance consistent with neutrino oscillations. An observed-to-predicted ratio of events of 0.944±0.016(stat)±0.040(syst) was obtained in 101 days of running at the Chooz nuclear power plant in France, with two 4.25 GW(th) reactors. The results were obtained from a single 10 m(3) fiducial volume detector located 1050 m from the two reactor cores. The reactor antineutrino flux prediction used the Bugey4 flux measurement after correction for differences in core composition. The deficit can be interpreted as an indication of a nonzero value of the still unmeasured neutrino mixing parameter sin(2)2θ(13). Analyzing both the rate of the prompt positrons and their energy spectrum, we find sin(2)2θ(13)=0.086±0.041(stat)±0.030(syst), or, at 90% C.L., 0.017<sin(2)2θ(13)<0.16.

Esophageal perforation: an increasing challenge

Esophageal perforation continues to be a challenge. The overall incidence is rising even though iatrogenic perforations are decreasing. With early diagnosis followed by prompt surgical treatment, most patients can be expected to survive. Roentgenographic contrast studies demonstrated a perforation in all but 1 of our patients who had this examination and should be used early in patients suspected of having an esophageal perforation. The mortality rate is directly related to the interval between perforation and initiation of treatment. Nonoperative treatment, even for cervical esophageal perforations, is not advocated. An aggressive approach, consisting of closure of the perforation and adequate drainage, is indicated for both diagnosis and surgical treatment.

Measurement of neutrino oscillation with KamLAND: evidence of spectral distortion

We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 nu (e) candidate events with energies above 3.4 MeV compared to 365.2+/-23.7 events expected in the absence of neutrino oscillation. Accounting for 17.8+/-7.3 expected background events, the statistical significance for reactor nu (e) disappearance is 99.998%. The observed energy spectrum disagrees with the expected spectral shape in the absence of neutrino oscillation at 99.6% significance and prefers the distortion expected from nu (e) oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2). A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2) and tan((2)theta=0.40(+0.10)(-0.07), the most precise determination to date.

Precision measurement of neutrino oscillation parameters with KamLAND

The KamLAND experiment has determined a precise value for the neutrino oscillation parameter Deltam21(2) and stringent constraints on theta12. The exposure to nuclear reactor antineutrinos is increased almost fourfold over previous results to 2.44 x 10(32) proton yr due to longer livetime and an enlarged fiducial volume. An undistorted reactor nu[over]e energy spectrum is now rejected at >5sigma. Analysis of the reactor spectrum above the inverse beta decay energy threshold, and including geoneutrinos, gives a best fit at Deltam21(2)=7.58(-0.13)(+0.14)(stat) -0.15+0.15(syst) x 10(-5) eV2 and tan2theta12=0.56(-0.07)+0.10(stat) -0.06+0.10(syst). Local Deltachi2 minima at higher and lower Deltam21(2) are disfavored at >4sigma. Combining with solar neutrino data, we obtain Deltam21(2)=7.59(-0.21)+0.21 x 10(-5) eV2 and tan2theta12=0.47(-0.05)+0.06.

Long-term results of Roux-en-Y hepatocholangiojejunostomy

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First Search for Short-Baseline Neutrino Oscillations at HFIR with PROSPECT

This Letter reports the first scientific results from the observation of antineutrinos emitted by fission products of ^{235}U at the High Flux Isotope Reactor. PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, consists of a segmented 4 ton ^{6}Li-doped liquid scintillator detector covering a baseline range of 7-9 m from the reactor and operating under less than 1 m water equivalent overburden. Data collected during 33 live days of reactor operation at a nominal power of 85 MW yield a detection of 25 461±283 (stat) inverse beta decays. Observation of reactor antineutrinos can be achieved in PROSPECT at 5σ statistical significance within 2 h of on-surface reactor-on data taking. A reactor model independent analysis of the inverse beta decay prompt energy spectrum as a function of baseline constrains significant portions of the previously allowed sterile neutrino oscillation parameter space at 95% confidence level and disfavors the best fit of the reactor antineutrino anomaly at 2.2σ confidence level.

Surviving Boerhaave's syndrome without thoracotomy

A case of Boerhaave's syndrome managed without thoracotomy is described. The diagnosis was not confirmed for 24 h when a barium swallow revealed free rupture of the esophagus into the left pleural cavity. Although survival has been reported with nonoperative management of contained esophageal perforations, to our knowledge, this is the first report of surviving Boerhaave's syndrome with free pleural rupture, without thoracotomy.

Plagiarised letters of recommendation submitted for the National Resident Matching Program

OBJECTIVES

Residency is a critical step in the professional development of physicians. Given the high stakes of the process, it is not surprising, although nonetheless troubling, that professional misconduct may occur: multiple studies have, rightfully, condemned applicants for plagiarising personal statements or misrepresenting publications. To date, however, no studies have examined whether faculty members may engage in similar behaviours.

METHODS

Software was used to evaluate 3864 unique applications containing 13 617 letters of recommendation submitted through the Electronic Residency Application Service (ERAS) to the Yale University Department of Psychiatry Residency Program in recruitment cycles from 2013-2014 to 2016-2017. The software identified pairs of letters written by different authors with at least 75 words of shared language, counting only words present in contiguous phrases of at least eight words (Shared Wording Across People, SWAP). Independent reviewers determined whether the shared language reflected acceptable forms of common usage (e.g. describing a setting of care) or was intended to convey unique attributes of an applicant, thereby representing plagiarism.

RESULTS

We found that 5.1% of letters contained SWAP and 4.1% of letters contained plagiarism. In total, 11.8% of all applications included at least one plagiarised letter. By comparison, 2.6% of applicants' personal statements contained plagiarism.

CONCLUSIONS

The present data demonstrate a surprising prevalence of plagiarism in letters of recommendation written for residency applicants. These data call into question both the relative weight that should be accorded to letters of recommendation and, more broadly, beg further discussion of how we conceptualise professionalism in medicine.