The Generation of Higher-order Laguerre-Gauss Optical Beams for High-precision Interferometry

Thermal noise in high-reflectivity mirrors is a major impediment for several types of high-precision interferometric experiments that aim to reach the standard quantum limit or to cool mechanical systems to their quantum ground state. This is for example the case of future gravitational wave observatories, whose sensitivity to gravitational wave signals is expected to be limited in the most sensitive frequency band, by atomic vibration of their mirror masses. One promising approach being pursued to overcome this limitation is to employ higher-order Laguerre-Gauss (LG) optical beams in place of the conventionally used fundamental mode. Owing to their more homogeneous light intensity distribution these beams average more effectively over the thermally driven fluctuations of the mirror surface, which in turn reduces the uncertainty in the mirror position sensed by the laser light.We demonstrate a promising method to generate higher-order LG beams by shaping a fundamental Gaussian beam with the help of diffractive optical elements. We show that with conventional sensing and control techniques that are known for stabilizing fundamental laser beams, higher-order LG modes can be purified and stabilized just as well at a comparably high level. A set of diagnostic tools allows us to control and tailor the properties of generated LG beams. This enabled us to produce an LG beam with the highest purity reported to date. The demonstrated compatibility of higher-order LG modes with standard interferometry techniques and with the use of standard spherical optics makes them an ideal candidate for application in a future generation of high-precision interferometry.     

Enabling richer statistical MANET simulations through cluster computing

The wide-scale adoption of modern smart phones and other multi-radio mobile devices, has begun to provide pragmatic deployment environments for non-cellular mobile ad hoc network (MANET) services (i.e., for disaster recovery scenarios, peered mobile games, social networking applications, etc.). User perceptions of the quality of such MANET services will be driven, in part, by standard network-level quality of service (QoS) metrics such as delay, jitter, throughput, etc. Much of the existing MANET literature has explored these issues, as well as MANET routing protocol design, through single computer Monte Carlo simulations (e.g., via ns-2, ns-3, OMNeT++, or OpNet). Results are then reported as the averages of these Monte Carlo runs. As is well known from probability and statistics, such averaging is only meaningful when applied across statistically ergodic data (i.e., data drawn from the same underlying distribution). But, assessing the validity of this underlying ergodic assumption requires transitioning to more rigorous cluster-based MANET simulation frameworks. This work highlights the theoretical rationale for such ergodicity testing, the developments of a cluster-based framework, the STARs framework, to support such testing, and the results and insights obtained by using this framework to evaluate the popular DYMO and OLSR MANET routing protocols. This work also discusses why the insights ergodic testing provides are of interest to potential real-world MANET deployments.     

Geochemical assessment of fluoride enriched groundwater and health implications from a part of Yavtmal District,India

Abstract

A comprehensive study was conducted from a semi-arid part of Yavtmal District, Maharashtra, India through combination approaches of geochemical modeling and its health consequences. The groundwater quality assessment shows that 55% of groundwater samples have the concentration of fluoride above the desirable limit. The high Na⁺/Ca⁺ ratio (>1.0) suggest the occurrence of cation exchange, which is further supported by Scholler’ chloro-alkaline indices. The geochemical modeling reveals that the existence of CaCO₃ precipitation and CaF₂ in groundwater. Simulation analysis indicates the dissolution of calcite, gypsum, and albite and precipitation of dolomite, fluorite, halite, and K-feldspar along with cation exchange as the main water–rock interactions influencing the groundwater chemistry. This is further significantly supported by pollution index of groundwater (PIG). PIG indicates about 18% of total samples fall in very high pollution zone, 3% in high pollution zone, 8% in moderate pollution zone, 24% in low pollution zone, and remaining (47%) express insignificant pollution. The 28% of subject studied have skeletal fluorosis varying from mild to severe type. In different pollution zones, the affected persons by dental fluorosis are varying from 15% to 41%. A proper monitoring and treatment are required for high fluoride water before its use for drinking and cooking.     

Studies on ontogeny and reproductive behaviour of Lepisorus nudus (Hook.) Ching (Polypodiaceae)

Journal of Plant Research - In-vitro studies of the ontogeny and mating system of the gametophytes of Lepisorus nudus were carried out through multispore and isolate cultures lasting...     

Effect of a Selective Cyclooxygenase Type 2 Inhibitor Celecoxib on Depression Associated with Obesity in Mice: An Approach Using Behavioral Tests

The biological mechanisms that link the development of depression to metabolic disorders such as obesity and diabetes remain ambiguous. In the present study the potential of a selective cyclooxygenase inhibitor celecoxib (15 mg/kg p.o.) was investigated in depression associated with obesity in mice. Behavioral tests used to assess depressive-like behavior were sucrose preference test, forced swim test (FST), tail suspension test (TST) and elevated plus maze (EPM). The basal locomotor score in obese mice was not altered. Furthermore, estimation of biochemical parameters was performed for plasma glucose, total cholesterol, triglycerides and total proteins. Escitalopram (10 mg/kg p.o.) served as reference standard drug. In the results, chronic treatment with celecoxib for 28 days significantly attenuated the behavioral alterations as indicated by increased the sucrose consumption, reduced the immobility time in FST and TST, increased the percent open arm time and entries in EPM in obese mice. In the biochemical parameters celecoxib significantly reversed the increased plasma glucose, total cholesterol, triglycerides and total proteins in obese mice. In conclusion, celecoxib exhibited potential antidepressant-like effect in depression associated with obesity, which to some extent is mediated by reversing the altered plasma glucose in obese mice.