Identification of Radiopure Titanium for the LZ Dark Matter Experiment and Future Rare Event Searches

The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a detector containing a total of 10 tonnes of liquid xenon within a double-vessel cryostat. The large mass and proximity of the cryostat to the active detector volume demand the use of material with extremely low intrinsic radioactivity. We report on the radioassay campaign conducted to identify suitable metals, the determination of factors limiting radiopure production, and the selection of titanium for construction of the LZ cryostat and other detector components. This titanium has been measured with activities of $^{238}$U$_{e}$~$<$1.6~mBq/kg, $^{238}$U$_{l}$~$<$0.09~mBq/kg, $^{232}$Th$_{e}$~$=0.28\pm 0.03$~mBq/kg, $^{232}$Th$_{l}$~$=0.25\pm 0.02$~mBq/kg, $^{40}$K~$<$0.54~mBq/kg, and $^{60}$Co~$<$0.02~mBq/kg (68\% CL). Such low intrinsic activities, which are some of the lowest ever reported for titanium, enable its use for future dark matter and other rare event searches. Monte Carlo simulations have been performed to assess the expected background contribution from the LZ cryostat with this radioactivity. In 1,000 days of WIMP search exposure of a 5.6-tonne fiducial mass, the cryostat will contribute only a mean background of $0.160\pm0.001$(stat)$\pm0.030$(sys) counts

LUX-ZEPLIN (LZ) Technical Design Report

In this Technical Design Report (TDR) we describe the LZ detector to be built at the Sanford Underground Research Facility (SURF). The LZ dark matter experiment is designed to achieve sensitivity to a WIMP-nucleon spin-independent cross section of three times ten to the negative forty-eighth square centimeters

Depression and anxiety in relation to catechol-O-methyltransferase Val158Met genotype in the general population: The Nord-Trøndelag Health Study (HUNT)

<p>Abstract</p> <p>Background</p> <p>The catechol-O-methyltransferase (COMT) gene contains a functional polymorphism, Val158Met, which has been linked to anxiety and depression, but previous results are not conclusive. The aim of the present study was to examine the relationship between the Val158Met COMT gene polymorphism and anxiety and depression measured by the Hospital Anxiety and Depression Scale (HADS) in the general adult population.</p> <p>Methods</p> <p>In the Nord-Trøndelag Health Study (HUNT) the association between the Val158Met polymorphism and anxiety and depression was evaluated in a random sample of 5531 individuals. Two different cut off scores (≥ 8 and ≥ 11) were used to identify cases with anxiety (HADS-A) and depression (HADS-D), whereas controls had HADS-A <8 and HADS-D <8.</p> <p>Results</p> <p>The COMT genotype distribution was similar between controls and individuals in the groups with anxiety and depression using cut-off scores of ≥ 8. When utilizing the alternative cut-off score HADS-D ≥ 11, Met/Met genotype and Met allele were less common among men with depression compared to the controls (genotype: p = 0.017, allele: p = 0.006). In the multivariate analysis, adjusting for age and heart disease, depression (HADS-D ≥ 11) was less likely among men with the Met/Met genotype than among men with the Val/Val genotype (OR = 0.37, 95% CI = 0.18–0.76).</p> <p>Conclusion</p> <p>In this population-based study, no clear association between the Val158Met polymorphism and depression and anxiety was revealed. The Met/Met genotype was less likely among men with depression defined as HADS-D ≥ 11, but this may be an incidental finding.</p

Chronic dialysis in the infant less than 1 year of age

Dialysis in the infant carries a mortality rate of 16%. Institution of dialysis may be the result of adequate nutritional intake, but avoidance of nutritional intake should never be seen as a way to prevent dialysis. Increased caloric intake, usually via enteral feeding tubes, is needed for optimal growth in the infant with end-stage renal disease (ESRD) in order to attain adequate nutrition with resulting good growth. “Renal” formulae may be constituted as dilute (as in the polyuric infant) or concentrated (as in the anuric infant) to fit the infants needs. Peritoneal dialysis (PD) is the usual mode of renal replacement therapy (97%), with access via a surgically placed cuffed catheter with attention to the placement of the exit site in order to avoid fecal or urinary contamination. PD volumes of 30–40 ml/kg per pass or 800–1,200 ml/m 2 per pass usually result in dialysis adequacy. Additional dietary sodium (3–5 mEq/kg per day) and protein (3–4 g/kg per day) are needed, due to sodium and protein losses in the dialysate. Protein losses are associated with significant infectious morbidity and nonresponsiveness to routine immunizations. Hemodialysis (HD) can be performed either as single- or dual-needle access that have minimal dead space (less then 2 ml) and recirculation rate (less then 5%). Attnetion to extracorporeal blood volume (<10% of intravascular volume), blood flow rates (3–5 ml/kg per min), heparinization (activated clotting times), ultrafiltration (ultrafiltration monitor), and temperature control is imperative during each treatment. Because infants' nutrition is mostly fluid, HD may be needed 4–6 days/week (especially in the oligoanuric infant) to avoid excessive volume overload between treatments. At the end of the treatment a slow blood return with minimal saline rinse is needed to avoid hemodynamic compromise. Infant dialysis, although technically challenging with a significant morbidity and mortality rate, can be safely carried out in the infant with ESRD but requires infant-specific equipment and trained personnel.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47836/1/467_2004_Article_BF00867678.pd