Limits on the Existence of sub-MeV Sterile Neutrinos from the Decay of

Sterile neutrinos are natural extensions to the standard model of particle physics and provide a possible portal to the dark sector. We report a new search for the existence of sub-MeV sterile neutrinos using the decay-momentum reconstruction technique in the decay of ^{7}Be. The experiment measures the total energy of the ^{7}Li daughter atom from the electron capture decay of ^{7}Be implanted into sensitive superconducting tunnel junction (STJ) quantum sensors. This first experiment presents data from a single STJ operated at a low count rate for a net total of 28 days, and provides exclusion limits on sterile neutrinos in the mass range from 100 to 850 keV that improve upon previous work by up to an order of magnitude.

A register study of the impact of stopping third trimester selective serotonin reuptake inhibitor exposure on neonatal health.

OBJECTIVE: To determine whether risk for adverse neonatal outcomes are reduced by stopping SSRI use before the end of pregnancy. METHOD: Using population health data, maternal health and prenatal SSRI prescriptions were linked to neonatal birth records (N = 119,547) (1998-2001). Neonates SSRI-exposed in the last 14 days (L14) of gestation were compared with infants who had gestational exposure, but not during the last 14 days (NL14). Propensity score matching was used to control for potential confounders (total exposure, maternal health characteristics). RESULTS: Increased risk for neonatal respiratory distress was present where L14 exposure occurred compared with risk where exposure stopped before L14. However, controlling for potential maternal and neonatal confounders, differences disappeared. CONCLUSION: Controlling for maternal illness severity, reducing exposure to SSRI's at the end of pregnancy had no significant clinical effect on improving neonatal health. These findings raise the possibility that some adverse neonatal outcomes may not be an acute pharmacological condition such as toxicity or withdrawal.

Association of the arterial access site at angioplasty with transfusion and mortality: the M.O.R.T.A.L study (Mortality benefit Of Reduced Transfusion after percutaneous coronary intervention via the Arm or Leg).

BACKGROUND: Bleeding and transfusion after percutaneous coronary intervention (PCI) are known predictors of mortality. Transradial arterial access reduces bleeding and transfusion related to femoral access complications, although its association with mortality is unknown. OBJECTIVE: To determine the association of arterial access site (radial or femoral) with transfusion and mortality in unselected PCIs. DESIGN, SETTING AND PATIENTS: By data linkage of three prospectively collated provincial registries, 38,872 procedures in 32,822 patients in British Columbia were analysed. The association between access site, transfusion and outcomes was assessed by logistic regression, propensity score matching and probit regression. MAIN OUTCOME MEASURES: 30-Day and 1-year mortality. RESULTS: 1134 (3.5%) patients had at least one blood transfusion. Transfused patients had a significantly increased 30-day and 1-year mortality, adjusted odds ratio (95% CI) 4.01 (3.08 to 5.22) and 3.58 (2.94 to 4.36), respectively. By probit regression the absolute increase in risk of death at 1 year associated with receiving a transfusion was 6.78%. The number needed to treat was 14.74 (prevention of 15 transfusions required to "avoid" one death). Radial access halved the transfusion rate. After adjustment for all variables, radial access was associated with a significant reduction in 30-day and 1-year mortality, odds ratio = 0.71 (95% CI 0.61 to 0.82) and 0.83 (0.71 to 0.98), respectively (all p<0.001). CONCLUSIONS: In a registry of all comers to PCI, transradial access was associated with a halving of the transfusion rate and a reduction in 30-day and 1-year mortality.

Advanced mercuric iodide detectors for X-ray microanalysis.

We first present a brief tutorial on Mercuric Iodide (HgI2) detectors and the intimately related topic of near-room temperature ultralow noise preamplifiers. This provides both a physical basis and technological perspective for the topics to follow. We next describe recent advances in HgI2 applications to x-ray microanalysis, including a space probe Scanning Electron Microscope (SEM), Synchrotron x-ray detectors, and energy dispersive detector arrays. As a result of this work, individual detectors can now operate stably for long periods in vacuum, detect soft x-rays to the oxygen K edge at 523 eV, or count at rates exceeding 2x10(5)/sec. The detector packages are small, lightweight, and use low power. Preliminary HgI2 detector arrays of 10 elements with 500eV resolution have also been constructed and operate stably. Finally, we discuss expected advances in HgI2 array technology, including improved resolution, vacuum operation, and the development of soft x-ray transparent encapsulants. Array capabilities include: large active areas, high (parallel) count rate capability and spatial sensitivity. We then consider areas of x-ray microanalysis where the application of such arrays would be advantageous, particularly including elemental microanalysis, via x-ray fluorescence spectroscopy, in both SEMs and in scanning x-ray microscopes. The necessity of high count rate capability as spatial resolution increases is given particular attention in this connection. Finally, we consider the possibility of Extended X-ray Absorption Fine Structure (EXAFS) studies on square micron sized areas, using detector arrays.

X-ray absorption edge fine structure of potassium ions in various environments: application to frog blood cells.

The edge spectrum is a sensitive probe of local chemistry. Edge spectra of potassium in various chemical environments were measured, and each environment gives a unique edge spectrum. Hydrated potassium has a unique spectrum that is insensitive to counterions. Comparison of the spectra shows that the chemical state of potassium in cells differs appreciably from that in aqueous solutions.