First Results from the DEAP-3600 Dark Matter Search with Argon at SNOLAB.

This Letter reports the first results of a direct dark matter search with the DEAP-3600 single-phase liquid argon (LAr) detector. The experiment was performed 2 km underground at SNOLAB (Sudbury, Canada) utilizing a large target mass, with the LAr target contained in a spherical acrylic vessel of 3600 kg capacity. The LAr is viewed by an array of PMTs, which would register scintillation light produced by rare nuclear recoil signals induced by dark matter particle scattering. An analysis of 4.44 live days (fiducial exposure of 9.87 ton day) of data taken during the initial filling phase demonstrates the best electronic recoil rejection using pulse-shape discrimination in argon, with leakage <1.2×10^{-7} (90% C.L.) between 15 and 31 keV_{ee}. No candidate signal events are observed, which results in the leading limit on weakly interacting massive particle (WIMP)-nucleon spin-independent cross section on argon, <1.2×10^{-44} cm^{2} for a 100 GeV/c^{2} WIMP mass (90% C.L.).

Epidural analgesia decreases intraabdominal pressure in postoperative patients with primary intra-abdominal hypertension.

INTRODUCTION: Surgical decompression is a lifesaving procedure in patients with severe intraabdominal hypertension. However, it involves subsequent management of an open abdomen. Therefore, it is not recommended for moderate intra-abdominal hypertension. Our literature search did not show any studies relating the efficacy of epidural analgesia in decreasing elevated intraabdominal pressure (IAP) in critically-ill surgical patients with primary intra-abdominal hypertension. MATERIAL AND METHODS: Through a blinded prospective study, we investigated postoperative critically-ill surgical and trauma patients with primary intra-abdominal hypertension, who received postoperative thoracic epidural analgesia (n = 58) or intravenous opioid analgesia (n = 130). Patients in the epidural group received ropivacaine 0.2% 10 ml, followed by an infusion of 5 ml/h for 96 hours. Patients in the opioid group could receive morphine hydrochloride (0.1 mg/kg IV for every 4-6 hours as needed) with or without ketorolac trometamol (up to 90 mg/day IV). IAP was measured transvesically, for every 6 hours. Additionally, measurements immediately before and 1 hour after the initiation of epidural analgesia were taken. Abdominal Perfusion Pressure (APP) was calculated for each IAP measurement as APP = MAP - IAP where MAP is the mean arterial pressure. RESULTS: In the epidural group we found a consistent decrease in IAP from 16.82 +/- 4.56 to 6.30 +/- 3.11 mmHg and an increase in APP from 60.26 +/- 21.893 to 76.10 +/- 17.54 mmHg between baseline values until the second day of epidural analgesia, which remained stable afterwards. There were no significant differences of IAP and APP in the opioid group. CONCLUSION: Continuous thoracic epidural analgesia decreases IAP and improves APP without haemodynamic compromise in postoperative critically-ill patients with primary intra-abdominal hypertension.

Thermomechanical oscillations in hybrid nematic liquid crystals.

Thermomechanical oscillations observed previously in hybrid oriented nematic liquid crystals (NLCs) are explained theoretically. The effect is conditioned by the hydrodynamic flow tendency to reduce the curvature of the "flexible ribbon" of hybrid NLCs. There is qualitative agreement between the theoretical calculations and the experimental results.

Transverse-momentum fluctuations in pi(+)p and K(+)p Collisions at 250 GeV/c.

We report results on event-by-event fluctuations of transverse momentum, Phi(p(t)), in pi(+)p and K(+)p collisions at 250 GeV/c. For the first time, their dependence on rapidity region, transverse momentum acceptance, multiplicity, mean transverse momentum per event, and on the correlation between transverse momentum and multiplicity are systematically presented. The results are compared with those from the PYTHIA Monte Carlo generator. The fluctuations under the same acceptance cuts as used in current heavy-ion experiments are also presented.