First background-free limit from a directional dark matter experiment: results from a fully fiducialised DRIFT detector

The addition of O2 to gas mixtures in time projection chambers containing CS2 has recently been shown to produce multiple negative ions that travel at slightly different velocities. This allows a measurement of the absolute position of ionising events in the z (drift) direction. In this work, we apply the z-fiducialisation technique to a directional dark matter search. In particular, we present results from a 46.3 live-day source-free exposure of the DRIFT-IId detector run in this completely new mode. With full-volume fiducialisation, we have achieved the first background-free operation of a directional detector. The resulting exclusion curve for spin-dependent WIMP-proton interactions reaches 0.9 pb at 100 GeV/c2, a factor of 2 better than our previous work. We describe the automated analysis used here, and argue that detector upgrades, implemented after the acquisition of these data, will bring an additional factor of \u3e3 improvement in the near future

Radon in the DRIFT-II directional dark matter TPC: emanation, detection and mitigation

Radon gas emanating from materials is of interest in environmental science and also a major concern in rare event non-accelerator particle physics experiments such as dark matter and double beta decay searches, where it is a major source of background. Notable for dark matter experiments is the production of radon progeny recoils (RPRs), the low energy (100 keV) recoils of radon daughter isotopes, which can mimic the signal expected from WIMP interactions. Presented here are results of measurements of radon emanation from detector materials in the 1m3 DRIFT-II directional dark matter gas time projection chamber experiment. Construction and operation of a radon emanation facility for this work is described, along with an analysis to continuously monitor DRIFT data for the presence of internal 222Rn and 218Po. Applying this analysis to historical DRIFT data, we show how systematic substitution of detector materials for alternatives, selected by this device for low radon emanation, has resulted in a factor of 10 reduction in internal radon rates. Levels are found to be consistent with the sum from separate radon emanation measurements of the internal materials and also with direct measurement using an attached alpha spectrometer. The current DRIFT detector, DRIFT-IId, is found to have sensitivity to [...] with current analysis efficiency, potentially opening up DRIFT technology as a new tool for sensitive radon assay of materials

Experimental approaches to study the nutritional value of food ingredients for dogs and cats

This review covers methods that have been applied to study the nutrient value or quality of specific ingredients fed to dogs, cats and comparable species (i.e. foxes, minks, rats, etc.). Typically, the nutritional value or utilization of a specific ingredient is measured by total tract digestibility and has been expanded through the measurement of total nutrient balance (i.e. nitrogen or energy). However, to better understand digestion it is necessary to obtain a more accurate measurement of nutrients entering and leaving the small intestine. Accurate measurement of small intestinal digestion is crucial in dogs and cats because nutrient digestion and absorption occurs primarily in the small intestine. Measuring small intestinal digestibility requires access to digesta leaving the small intestine and can be obtained by placing a cannula at the terminal ileum. This approach also necessitates the use of markers (e.g. chromic oxide) to monitor flow of digesta. Specifically, this approach has been used for the direct measurement of intestinal digestion of carbohydrates and amino acids. It also permits a separate measurement of large intestinal digestion which is particularly useful for the study of fiber fermentation. Passage of foods through the gastrointestinal tract is also an important component of utilization and these methods are reviewed

Angiogenin variants in Parkinson disease and amyotrophic lateral sclerosis.

Contains fulltext : 95644.pdf (publisher's version ) (Closed access)OBJECTIVE: Several studies have suggested an increased frequency of variants in the gene encoding angiogenin (ANG) in patients with amyotrophic lateral sclerosis (ALS). Interestingly, a few ALS patients carrying ANG variants also showed signs of Parkinson disease (PD). Furthermore, relatives of ALS patients have an increased risk to develop PD, and the prevalence of concomitant motor neuron disease in PD is higher than expected based on chance occurrence. We therefore investigated whether ANG variants could predispose to both ALS and PD. METHODS: We reviewed all previous studies on ANG in ALS and performed sequence experiments on additional samples, which allowed us to analyze data from 6,471 ALS patients and 7,668 controls from 15 centers (13 from Europe and 2 from the USA). We sequenced DNA samples from 3,146 PD patients from 6 centers (5 from Europe and 1 from the USA). Statistical analysis was performed using the variable threshold test, and the Mantel-Haenszel procedure was used to estimate odds ratios. RESULTS: Analysis of sequence data from 17,258 individuals demonstrated a significantly higher frequency of ANG variants in both ALS and PD patients compared to control subjects (p = 9.3 x 10(-6) for ALS and p = 4.3 x 10(-5) for PD). The odds ratio for any ANG variant in patients versus controls was 9.2 for ALS and 6.7 for PD. INTERPRETATION: The data from this multicenter study demonstrate that there is a strong association between PD, ALS, and ANG variants. ANG is a genetic link between ALS and PD. ANN NEUROL 2011;70:964-973.1 december 201110 p