LArGe: Background suppression using liquid argon (LAr) scintillation for 0νββ\nu\beta\beta decay search with enriched germanium (Ge) detectors

Measurements with a bare p-type high purity germanium diode (HPGe) submerged in a 19 kg liquid argon (LAr) scintillation detector at MPIK Heidelberg are reported. The liquid argon--germanium system (LArGe) is operated as a 4$\pi$ anti-Compton spectrometer to suppress backgrounds in the HPGe. This R&D is carried out in the framework of the GERDA experiment which searches for 0$\nu\beta\beta$ decays with HPGe detectors enriched in $^{76}$Ge. The goal of this work is to develop a novel method to discriminate backgrounds in 0$\nu\beta\beta$ search which would ultimately allow to investigate the effective neutrino mass free of background events down to the inverse mass hierarchy scale. Other applications in low-background counting are expected.Comment: 3 pages, 6 figures, conference proceedings of the 10th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD06) 1 - 5 October 2006 Siena, Ital

Щоденники експедиційної роботи Григорія Дем'яна (Вступна стаття та підготовка текстів Василя Сокола)

The interaction between S(-II) and ferric oxides exerts a major control for the sulphur and iron cycle and in particular for the carbon and electron flow in many aquatic systems. It is regarded to be a key reaction leading ultimately to pyrite formation, the pathways still remaining unresolved. We have studied the reaction between lepidocrocite (γ-FeOOH, 21–42 mmol L−1) and dissolved S(-II) (3–9 mmol L−1) in batch experiments at pH 7 in a glove box using TEM, XRD, Mössbauer spectroscopy, and wet chemistry extraction to explore the nanocrystalline products forming at different time steps in close contact to the lepidocrocitesurface. S(0) and acid extractable Fe(II) (Fe(II)HCl) were the main products detected by wet chemistry extraction. The reaction could be divided into three steps: a rapid (<15 min) consumption of dissolved S(-II), formationof S(0) and the build-up of an Fe(II)HCl pool. Then in the absence of dissolved S(-II) concentrations of S(0) and Fe(II)HCl increased only slightly. TEM measurements revealed the occurrence of a mackinawite rim covering the lepidocrocite crystals and being separated from the lepidocrocitesurface by an interfacial magnetite layer that can be regarded as a steady state product of the interaction between lepidocrocite and mackinawite. A significant fraction of Fe(II) was formed in excess to FeS within the first 2 h. The amount of this fraction increased with decreasing ratio between dissolved S(-II) concentration and the concentration ofsurface sites, which we attributed to a kinetic decoupling of S(-II) oxidation and Fe(II) detachment from the lepidocrocitesurface. At low ratios, S(-II) seems to transfer electrons to lepidocrocite faster then stoichiometric amounts of FeS could. After 2 days Fe(II)HCl and S(0) started to decrease resulting in pyrite formation accompanied by traces of magnetite. TEM measurements indicated that mackinawite completely dissolved and precipitation of pyrite occurred dislocated from the lepidocrocitesurface. The absence of dissolved sulphide under these conditions suggest that excess Fe(II) is involved in the formationof polysulphides which are key precursors during pyrite formation. We propose that the occurrence of excess Fe(II) is a common phenomenon particularly in low sulphide – high iron environments attributing significant reactivity to ferric (hydr)oxide

Factors influencing pacing in triathlon

Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing) within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon

Microphase separation in a model graft copolymer

We present a preliminary overview of our work on a series of graft copolymers having poly(ethyl acrylate) backbones with pendant chains of polystyrene (PS). The copolymer system appeared to be in the strong segregation limit and exhibited evidence of ordered structures. The morphology of these structures can apparently be very different from what would be expected. For instance, we observed a lamellar structure in a material containing 28 wt.% PS grafts. Samples under uniaxial strain showed either conventional (i.e., affine deformation) and anomalous ({open_quotes}butterfly{close_quotes} isointensity patterns) behavior in small-angle neutron scattering

Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase

Insulin resistance (IR), an impaired cellular, tissue and whole body response to insulin, is a major pathophysiological defect of type 2 diabetes mellitus. Although IR is closely associated with obesity, the identity of the molecular defect(s) underlying obesity-induced IR in skeletal muscle remains controversial; reduced post-receptor signalling of the insulin receptor substrate 1 (IRS1) adaptor protein and downstream effectors such as protein kinase B (PKB) have previously been implicated. We examined expression and/or activation of a number of components of the insulin-signalling cascade in skeletal muscle of 22 healthy young men (with body mass index (BMI) range, 20–37 kg/m2). Whole body insulin sensitivity (M value) and body composition was determined by the hyperinsulinaemic (40 mU. min−1.m−2.), euglycaemic clamp and by dual energy X-ray absorptiometry (DEXA) respectively. Skeletal muscle (vastus lateralis) biopsies were taken before and after one hour of hyperinsulinaemia and the muscle insulin signalling proteins examined by western blot and immunoprecipitation assay. There was a strong inverse relationship between M-value and BMI. The most striking abnormality was significantly reduced insulin-induced activation of p42/44 MAP kinase, measured by specific assay, in the volunteers with poor insulin sensitivity. However, there was no relationship between individuals' BMI or M-value and protein expression/phosphorylation of IRS1, PKB, or p42/44 MAP kinase protein, under basal or hyperinsulinaemic conditions. In the few individuals with poor insulin sensitivity but preserved p42/44 MAP kinase activation, other signalling defects were evident. These findings implicate defective p42/44 MAP kinase signalling as a potential contributor to obesity-related IR in a non-diabetic population, although clearly multiple signalling defects underlie obesity associated IR

Effect of ice slushy ingestion and cold water immersion on thermoregulatory behavior

Two studies were conducted to examine the effects of ice slushy ingestion (ICE) and cold water immersion (CWI) on thermoregulatory and sweat responses during constant (study 1) and self-paced (study 2) exercise. In study 1, 11 men cycled at 40–50% of peak aerobic power for 60 min (33.2 ± 0.3C, 45.9 ± 0.5% relative humidity, RH). In study 2, 11 men cycled for 60 min at perceived exertion (RPE) equivalent to 15 (33.9 ± 0.2C and 42.5 ± 3.9%RH). In both studies, each trial was preceded by 30 min of CWI (~22C), ICE or no cooling (CON). Rectal temperature (T re ), skin temperature (T sk ), thermal sensation, and sweat responses were measured. In study 1, ICE decreased T re- T sk gradient versus CON (p = 0.005) during first 5 min of exercise, while CWI increased T re- T sk gradient versus CON and ICE for up to 20 min during the exercise (p0.05). Increased T re -T sk gradient by CWI improved MPO while ICE reduced T re but did not confer any ergogenic effect. Both precooling treatments attenuated the thermal efferent signals until a specific body temperature threshold was reached. © 2019 Choo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Oval Domes: History, Geometry and Mechanics

An oval dome may be defined as a dome whose plan or profile (or both) has an oval form. The word Aoval@ comes from the latin Aovum@, egg. Then, an oval dome has an egg-shaped geometry. The first buildings with oval plans were built without a predetermined form, just trying to close an space in the most economical form. Eventually, the geometry was defined by using arcs of circle with common tangents in the points of change of curvature. Later the oval acquired a more regular form with two axis of symmetry. Therefore, an “oval” may be defined as an egg-shaped form, doubly symmetric, constructed with arcs of circle; an oval needs a minimum of four centres, but it is possible also to build polycentric ovals. The above definition corresponds with the origin and the use of oval forms in building and may be applied without problem until, say, the XVIIIth century. Since then, the teaching of conics in the elementary courses of geometry made the cultivated people to define the oval as an approximation to the ellipse, an “imperfect ellipse”: an oval was, then, a curve formed with arcs of circles which tries to approximate to the ellipse of the same axes. As we shall see, the ellipse has very rarely been used in building. Finally, in modern geometrical textbooks an oval is defined as a smooth closed convex curve, a more general definition which embraces the two previous, but which is of no particular use in the study of the employment of oval forms in building. The present paper contains the following parts: 1) an outline the origin and application of the oval in historical architecture; 2) a discussion of the spatial geometry of oval domes, i. e., the different methods employed to trace them; 3) a brief exposition of the mechanics of oval arches and domes; and 4) a final discussion of the role of Geometry in oval arch and dome design

Pulse-shape discrimination and energy resolution of a liquid-argon scintillator with xenon doping

Liquid-argon scintillation detectors are used in fundamental physics experiments and are being considered for security applications. Previous studies have suggested that the addition of small amounts of xenon dopant improves performance in light or signal yield, energy resolution, and particle discrimination. In this study, we investigate the detector response for xenon dopant concentrations from 9 +/- 5 ppm to 1100 +/- 500 ppm xenon (by weight) in 6 steps. The 3.14-liter detector uses tetraphenyl butadiene (TPB) wavelength shifter with dual photomultiplier tubes and is operated in single-phase mode. Gamma-ray-interaction signal yield of 4.0 +/- 0.1 photoelectrons/keV improved to 5.0 +/- 0.1 photoelectrons/keV with dopant. Energy resolution at 662 keV improved from (4.4 +/- 0.2)% ({\sigma}) to (3.5 +/- 0.2)% ({\sigma}) with dopant. Pulse-shape discrimination performance degraded greatly at the first addition of dopant, slightly improved with additional additions, then rapidly improved near the end of our dopant range, with performance becoming slightly better than pure argon at the highest tested dopant concentration. Some evidence of reduced neutron scintillation efficiency with increasing dopant concentration was observed. Finally, the waveform shape outside the TPB region is discussed, suggesting that the contribution to the waveform from xenon-produced light is primarily in the last portion of the slow component