Chimie et neutrinos

Cet article illustre la synergie qui existe entre la chimie et la détection des neutrinos, ces particules élémentaires dont l'existence fut confirmée grâce à l'invention des détecteurs à liquide scintillant par des chimistes. Les progrès de ces détecteurs sont issus des recherches des chimistes. La résolution de l'énigme des neutrinos solaires fut rendue possible entre autres par l'obtention d'une extrême pureté radiochimique des différentes cibles utilisées

The Reactor Antineutrino Anomaly

Recently new reactor antineutrino spectra have been provided for 235U, 239Pu, 241Pu and 238U, increasing the mean flux by about 3 percent. To good approximation, this reevaluation applies to all reactor neutrino experiments. The synthesis of published experiments at reactor-detector distances <100 m leads to a ratio of observed event rate to predicted rate of 0.976(0.024). With our new flux evaluation, this ratio shifts to 0.943(0.023), leading to a deviation from unity at 98.6% C.L. which we call the reactor antineutrino anomaly. The compatibility of our results with the existence of a fourth non-standard neutrino state driving neutrino oscillations at short distances is discussed. The combined analysis of reactor data, gallium solar neutrino calibration experiments, and MiniBooNE-neutrino data disfavors the no-oscillation hypothesis at 99.8% C.L. The oscillation parameters are such that |Delta m_{new}^2|>1.5 eV^2 (95%) and sin^2(2\theta_{new})=0.14(0.08) (95%). Constraints on the theta13 neutrino mixing angle are revised.Comment: 19 pages, 15 figures ; v2/3 include typos corrected ; v4 final version: add 5 Rovno & 2 Savannah River results + add additional constistency checks + add a discussion on the inverse beta decay cross section normlizatio

Characterization of a Novel Human Type II Epithelial Keratin K1b, Specifically Expressed in Eccrine Sweat Glands

In this study, we show that a novel human type II epithelial keratin, K1b, is exclusively expressed in luminal duct cells of eccrine sweat glands. Taking this luminal K1b expression as a reference, we have used antibodies against a plethora of epithelial keratins to systematically investigate their expression in the secretory globule and the two-layered sweat duct, which was divided into the intraglandular, intradermal, and intraepidermal (acrosyringium) segments, the latter being further subdivided into the sweat duct ridge and upper intraepidermal duct. We show that (i) each of the eccrine sweat gland tissue compartments expresses their own keratin patterns, (ii) the peripheral and luminal duct layers exhibit a sequential keratin expression, with both representing self-renewing cell layers, (iii) the intradermal duct and the sweat duct ridge display hitherto unknown length variations, and (iv) out of all cell layers, the luminal cell layer is the most robust layer and expresses the highest number of keratins, these being concentrated at the apical side of the cells to form the cuticle. We provide evidence that the cellular and intercellular properties of the peripheral and the luminal layers reflect adaptations to different functions

The sign of the day-night asymmetry for solar neutrinos

A qualitative understanding of the day-night asymmetry for solar neutrinos is provided. The greater night flux in nu_e is seen to be a consequence of the fact that the matter effect in the sun and that in the earth have the same sign. It is shown in the adiabatic approximation for the sun that for all values of the mixing angle theta_V between 0 and pi/2, the night flux of neutrinos is greater than the day flux. Only for small values of theta_V where the adiabatic approximation badly fails does the sign of the day-night asymmetry reverse.Comment: 3 pages, 3 figures, typos corrected and references adde

Beta decay of 115-In to the first excited level of 115-Sn: Potential outcome for neutrino mass

Recent observation of beta decay of 115-In to the first excited level of 115-Sn with an extremely low Q_beta value (Q_beta ~ 1 keV) could be used to set a limit on neutrino mass. To give restriction potentially competitive with those extracted from experiments with 3-H (~2 eV) and 187-Re (~15 eV), atomic mass difference between 115-In and 115-Sn and energy of the first 115-Sn level should be remeasured with higher accuracy (possibly of the order of ~1 eV).Comment: 9 pages, 3 figures; talk at the NANP'05 Conferenc

M004 In aortic stenosis, 2D speckle tracking differentiates left ventricular dysfunction load- to remodelling-dependant

BackgroundIn aortic stenosis, it is not known which between longitudinal, radial and circumferential contraction is influenced by loading conditions or remodelling. To test our hypothesis and to understand left ventricular function recovery, we investigated patients at early, i.e. 7 days (contractility enhancement load-dependant) and at late follow-up, i.e. 3 months (contractility enhancement remodelling-dependant) after transcutaneous aortic valve implantation (TAVI).Methods and ResultsTwenty-three subjects (AS: valve orifice < or =0.7cm2; 14 female; mean age, 84+/-6 years) were studied. All subjects of the study had conventional 2D-Doppler echocardiography and speckle tracking analysis (GE HealthCare). Speckle tracking was sampled in short-axis view for radial and circumferential strain and in apical 4, 3 and 2-chamber view for averaged longitudinal strain. Measurements were performed before, 7 days and 3 months after TAVI. Mean pressure gradient decreased from 41±20mmHg to 10±3mmHg (p<0.001) while aortic valve area increased from 0.6±0.1 to 1.7±0.2cm2 (p<0.001) after implantation. Biplane Simpson EF was 50±10 %, 51±13 and 58±11 % at baseline, 7-day and 3-month follow-up (p=0.01), respectively. Improvement of circumferential strain found 7 days after TAVI is sustained at 3 months. Radial strain increased shortly after TAVI, then decreased at 3 months and was compensated by improvement of longitudinal strain (see figure).ConclusionIn patients with aortic stenosis, radial contraction is load dependant, circumferential contraction is both load- and remodelling-dependant, whereas longitudinal contraction is remodeling-dependant

Gamow-Teller Strengths of the Inverse-Beta Transition 176Yb --> 176Lu for Spectroscopy of Proton-Proton and other sub-MeV Solar Neutrinos

Discrete Gamow-Teller (GT) transitions, 176Yb-->176Lu at low excitation energies have been measured via the (3He,t) reaction at 450 MeV and at 0 degrees. For 176Yb, two low-lying states are observed, setting low thresholds Q(neutrino)=301 and 445 keV for neutrino capture. Capture rates estimated from the measured GT strengths, the simple two-state excitation structure, and the low Q(neutrino) in Yb--Lu indicate that Yb-based neutrino-detectors are well suited for a direct measurement of the complete sub-MeV solar electron-neutrino spectrum (including pp neutrinos) where definitive effects of flavor conversion are expected

The NuMI Neutrino Beam and Potential for an Off-Axis Experiment

The Neutrinos at the Main Injector (NuMI) facility at Fermilab is under construction and due to begin operations in late 2004. NuMI will deliver an intense $\nu_{\mu}$ beam of variable energy 2-20 GeV directed into the Earth at 58 mrad. Several aspects of the design are reviewed, and potential limitations to the ultimate neutrino flux are described. In addition, potential measurements of neutrino mixing properties are described.Comment: talk given at NuFact '02, Imperial College London, proceedings to appear in J. Phys. G, revised to add a referenc

Transcatheter Aortic Valve Implantation in Dialysis Patients

Background/Aims: Transcatheter aortic valve implantation (TAVI) has emerged as a new therapeutic option for high-risk patients. However, dialysis patients were excluded from all previous studies. The aim of this study is to compare the outcomes of TAVI for dialysis patients with those for patients with chronic kidney disease (CKD) stages 3 and 4 and to compare TAVI with open surgery in dialysis patients. Methods: Part I: comparison of 10 patients on chronic hemodialysis with 116 patients with non-dialysis-dependent CKD undergoing TAVI. Part II: comparison of transcatheter (n = 15) with open surgical (n = 24) aortic valve replacement in dialysis patients. Results: Part I: dialysis patients were significantly younger (72.3 vs. 82.0 years; p < 0.01). Hospital stay was significantly longer in dialysis patients (21.8 vs. 12.1 days; p = 0.01). Overall 30-day mortality was 3.17%, with no deaths among dialysis patients. Six-month survival rates were similar (log-rank p = 0.935). Part II: patient age was comparable (66.5 vs. 69.5 years; p = 0.42). Patients in the surgical group tended to stay longer in hospital than TAVI patients (29.5 vs. 22.5 days; p = 0.35). Conclusion: TAVI is a safe procedure in patients on chronic hemodialysis. Until new data become available, we find no compelling reason to refuse these patients TAVI. Copyright (C) 2012 S. Karger AG, Base