Gaseous and dual-phase time projection chambers for imaging rare processes

Modern approaches to the detection and imaging of rare particle interactions through gaseous and dual-phase time projection chambers are discussed. We introduce and examine their basic working principles and enabling technological assets.Comment: Version accepted in NIM after small modifications. Quality of figures slightly reduced in pre-print due to arXiv restrictions on file siz

Megawatt solar power systems for lunar surface operations

The work presented here shows that a solar power system can provide power on the order of one megawatt to a lunar base with a fairly high specific power. The main drawback to using solar power is still the high mass, and therefore, cost of supplying energy storage through the solar night. The use of cryogenic reactant storage in a fuel cell system, however, greatly reduces the total system mass over conventional energy storage schemes

Numerical investigation of high-speed droplet impact using a multiscale two-fluid approach

A single droplet impact onto solid surfaces remains a fundamental and challenging topic in both experimental and numerical studies with significant importance in a plethora of industrial applications, ranging from printing technologies to fuel injection in internal combustion engines. Under high-speed impact conditions, additional complexities arise as a result of the prompt droplet splashing and the subsequent violent fragmentation; thus, different flow regimes and a vast spectrum of sizes for the produced secondary flow structures coexist in the flow field. The present work introduces a numerical methodology to capture the multiscale processes involved with respect to local topological characteristics. The proposed methodology concerns a compressible Σ-Υ two-fluid model with dynamic interface sharpening based on an advanced flow topology detection algorithm. The model has been developed in OpenFOAM® and provides the flexibility of dealing with the multiscale character of droplet splashing, by switching between a sharp and a diffuse interface within the Eulerian-Eulerian framework in segregated and dispersed flow regions, respectively. An additional transport equation for the interface surface area density (Σ) introduces important information for the sub-grid scale phenomena, which is exploited in the dispersed flow regions to provide an insight into the extended cloud of secondary droplets after impact on the target. A high-speed water droplet impact case has been examined and evaluated against new experimental data; these refer to a millimetre size droplet impacting a solid dry smooth surface at velocity as high as 150m/s, which corresponds to a Weber number of ~7.6×10^5. At the investigated impact conditions compressibility effects dominate the early stages of droplet splashing. A strong shock wave forms and propagates inside the droplet, where transonic Mach numbers occur; local Mach numbers up to 2.5 are observed for the expelled surrounding gas outside the droplet. The proposed numerical approach is found to capture relatively accurately the phenomena and provide significant information regarding the produced flow structure dimensions, which is not available from the experiment

Non-Equilibrium Dynamics and Superfluid Ring Excitations in Binary Bose-Einstein Condensates

We revisit a classic study [D. S. Hall {\it et al.}, Phys. Rev. Lett. {\bf 81}, 1539 (1998)] of interpenetrating Bose-Einstein condensates in the hyperfine states $\ket{F = 1, m_f = -1}\equiv\ket{1}$ and $\ket{F = 2, m_f = +1}\equiv\ket{2}$ of ${}^{87}$Rb and observe striking new non-equilibrium component separation dynamics in the form of oscillating ring-like structures. The process of component separation is not significantly damped, a finding that also contrasts sharply with earlier experimental work, allowing a clean first look at a collective excitation of a binary superfluid. We further demonstrate extraordinary quantitative agreement between theoretical and experimental results using a multi-component mean-field model with key additional features: the inclusion of atomic losses and the careful characterization of trap potentials (at the level of a fraction of a percent).Comment: 4 pages, 3 figures (low res.), to appear in PR

Effects of human recombinant growth hormone on exercise capacity, cardiac structure, and cardiac function in patients with adult-onset growth hormone deficiency

Objective Epidemiological studies suggest that adult-onset growth hormone deficiency (AGHD) might increase the risk of death from cardiovascular causes. Methods This was a 6-month double-blind, placebo-controlled, randomised, cross-over trial followed by a 6-month open-label phase. Seventeen patients with AGHD received either recombinant human growth hormone (rGH) (0.4 mg injection daily) or placebo for 12 weeks, underwent washout for 2 weeks, and were then crossed over to the alternative treatment for a further 12 weeks. Cardiac magnetic resonance imaging, echocardiography, and cardiopulmonary exercise testing were performed at baseline, 12 weeks, 26 weeks, and the end of the open phase (12 months). The results were compared with those of 16 age- and sex-matched control subjects. Results At baseline, patients with AGHD had a significantly higher systolic blood pressure, ejection fraction, and left ventricular mass than the control group, even when corrected for body surface area. Treatment with rGH normalised the insulin-like growth factor 1 concentration without an effect on exercise capacity, cardiac structure, or cardiac function. Conclusion Administration of rGH therapy for 6 to 9 months failed to normalise the functional and structural cardiac differences observed in patients with AGHD when compared with a control group

Erupciones Volcánicas de la Cuenca de México y sus effectos en poblaciones humanas tempranas del Pleistoceno Superior-Holoceno Temprano.

La Cuenca de México esta situada a una altura de 2,500 metros y se localiza dentro del Eje Volcánico Transmexicano. Todas las montañas que rodean a la Cuenca son de origen volcánico. En particular 3 erupciones volcánicas importantes de tipo Pliniano produjeron depósitos volcánicos asociados con cenizas volcánicas “marcadoras” en la Cuenca producidas durante la transición del Pleistoceno Superior – Holoceno Temprano. Estas son: 1) Gran Ceniza Basáltica, producida por la Sierra de Santa Catarina, con una edad de 28,600 años; 2) Pómez con Andesita producida por el Volcán Popocatépetl hace14,600 años 3) Pómez Toluca Superior (Tripatita) producida por el Volcán Nevado de Toluca, hace 10,500 años. Durante este intervalo de tiempo se tienen fechados varios sitios Paleoindios con la presencia tanto de esqueletos humanos embebidos en ceniza volcánica asociada con la Pómez Toluca Superior (Hombre del Metro Balderas), asi como sitios con megafauna asociada con lahares (flujos de lodo volcánico) en el sitio de Mamuts de Tocuila. Las erupciones volcánicas tuvieron un impacto muy importante tanto en el medio ambiente de la Cuenca asi como en las poblaciones humanas Paleoindias y la megafauna asociada (mamuts, camellos, caballos, gliptodontes) durante la transición del Pleistoceno-Holoceno Temprano