Strings in gravity with torsion

A theory of gravitation in 4D is presented with strings used in the material action in $U_4$ spacetime. It is shown that the string naturally gives rise to torsion. It is also shown that the equation of motion a string follows from the Bianchi identity, gives the identical result as the Noether conservation laws, and follows a geodesic only in the lowest order approximation. In addition, the conservation laws show that strings naturally have spin, which arises not from their motion but from their one dimensional structure.Comment: 16 page

Tensor-Scalar Torsion

A theory of gravity with torsion is examined in which the torsion tensor is constructed from the exterior derivative of an antisymmetric rank two potential plus the dual of the gradient of a scalar field. Field equations for the theory are derived by demanding that the action be stationary under variations with respect to the metric, the antisymmetric potential, and the scalar field. A material action is introduced and the equations of motion are derived. The correct conservation law for rotational angular momentum plus spin is observed to hold in this theory.Comment: 10 pages, LaTeX, Mod. Phys. Lett. A accepte

Polypharmacy and Falls in the Elderly: A Literature Review

Context: Medications are taken to ease, control or cure ailments. They are effective and safe if used correctly. In the elderly, disorders that occur as a result of ageing, frequently require treatment, resulting in increased use of medications. Polypharmacy is common among the elderly and although it can be therapeutic in nature, is linked to adverse events such as falls. Evidence Acquisition: A review of the literature was conducted. English articles in Cinahl, Medline and Healthsource (2000-2012) were searched for links between polypharmacy and falls in older adults aged 65 years old and over. Articles not meeting the age criterion were excluded. Results: Sixteen articles were included in the literature review. Four literature reviews, three observational prospective cohort, three cross-sectional, three case-control, one longitudinal study and two retrospective cohort studies were examined. Many studies were able to demonstrate a link between the number of medications taken and risk of falls however the potential for bias resulting from confounding by indication was high due to study design in many cases. Conclusions: Polypharmacy as an independent variable has been linked to falls in older people, however there appears to be a stronger link between falls and the type of medications taken (e.g. medications known to increase risk of falls), rather than polypharmacy on its own. Polypharmacy can sometimes be therapeutic and it may be more beneficial to consider terms such as ‘inappropriate prescribing’ or potentially inappropriate medications’ when considering the effects of medication on falls in older adults. Polypharmacy in older people is often viewed in a negative light due to the increased risk of adverse events, including falls. This article examined current knowledge on the characteristics that define polypharmacy, its effect on falls in elderly people and provided recommendations for future research. Further research utilizing prospective and intervention studies are needed to clarify the causal relationship between polypharmacy, comorbidities and fall risk

Electrical characterization of a Mapham inverter using pulse testing techniques

Electric power requirements for aerospace missions have reached megawatt power levels. Within the next few decades, it is anticipated that a manned lunar base, interplanetary travel, and surface exploration of the Martian surface will become reality. Several research and development projects aimed at demonstrating megawatt power level converters for space applications are currently underway at the NASA Lewis Research Center. Innovative testing techniques will be required to evaluate the components and converters, when developed, at their rated power in the absence of costly power sources, loads, and cooling systems. Facilities capable of testing these components and systems at full power are available, but their use may be cost prohibitive. The use of a multiple pulse testing technique is proposed to determine the electrical characteristics of large megawatt level power systems. Characterization of a Mapham inverter is made using the proposed technique and conclusions are drawn concerning its suitability as an experimental tool to evaluate megawatt level power systems

Ride quality systems for commuter aircraft

The state-of-the-art in Active Ride Augmentation, specifically in terms of its feasibility for commuter aircraft applications. A literature survey was done, and the principal results are presented here through discussion of different Ride Quality Augmentation System (RQAS) designs and advances in related technologies. Recommended follow-on research areas are discussed, and a preliminary RQAS configuration for detailed design and development is proposed

Design of a digital ride quality augmentation system for commuter aircraft

Commuter aircraft typically have low wing loadings, and fly at low altitudes, and so they are susceptible to undesirable accelerations caused by random atmospheric turbulence. Larger commercial aircraft typically have higher wing loadings and fly at altitudes where the turbulence level is lower, and so they provide smoother rides. This project was initiated based on the goal of making the ride of the commuter aircraft as smooth as the ride experienced on the major commercial airliners. The objectives of this project were to design a digital, longitudinal mode ride quality augmentation system (RQAS) for a commuter aircraft, and to investigate the effect of selected parameters on those designs

Leech Parasitism of the Gulf Coast Box Turtle, Terrapene carolina major (Testudines:Emydidae) in Mississippi, USA

Ten leeches were collected from a Gulf Coast box turtle, Terrapene carolina major, found crossing a road in Gulfport, Harrison County, Mississippi, USA. Eight of the leeches were identified as Placobdella multilineata and 2 were identified as Helobdella europaea. This represents the second vouchered report of leeches from a box turtle. Helobdella europaea is reported for the first time associated with a turtle and for the second time from the New World

Experimental and numerical study of error fields in the CNT stellarator

Sources of error fields were indirectly inferred in a stellarator by reconciling computed and numerical flux surfaces. Sources considered so far include the displacements and tilts (but not the deformations, yet) of the four circular coils featured in the simple CNT stellarator. The flux surfaces were measured by means of an electron beam and phosphor rod, and were computed by means of a Biot-Savart field-line tracing code. If the ideal coil locations and orientations are used in the computation, agreement with measurements is poor. Discrepancies are ascribed to errors in the positioning and orientation of the in-vessel interlocked coils. To that end, an iterative numerical method was developed. A Newton-Raphson algorithm searches for the coils' displacements and tilts that minimize the discrepancy between the measured and computed flux surfaces. This method was verified by misplacing and tilting the coils in a numerical model of CNT, calculating the flux surfaces that they generated, and testing the algorithm's ability to deduce the coils' displacements and tilts. Subsequently, the numerical method was applied to the experimental data, arriving at a set of coil displacements whose resulting field errors exhibited significantly improved quantitative and qualitative agreement with experimental results.Comment: Special Issue on the 20th International Stellarator-Heliotron Worksho

A CRISPR-Cas9 sex-ratio distortion system for genetic control.

Genetic control aims to reduce the ability of insect pest populations to cause harm via the release of modified insects. One strategy is to bias the reproductive sex ratio towards males so that a population decreases in size or is eliminated altogether due to a lack of females. We have shown previously that sex ratio distortion can be generated synthetically in the main human malaria vector Anopheles gambiae, by selectively destroying the X-chromosome during spermatogenesis, through the activity of a naturally-occurring endonuclease that targets a repetitive rDNA sequence highly-conserved in a wide range of organisms. Here we describe a CRISPR-Cas9 sex distortion system that targets ribosomal sequences restricted to the member species of the Anopheles gambiae complex. Expression of Cas9 during spermatogenesis resulted in RNA-guided shredding of the X-chromosome during male meiosis and produced extreme male bias among progeny in the absence of any significant reduction in fertility. The flexibility of CRISPR-Cas9 combined with the availability of genomic data for a range of insects renders this strategy broadly applicable for the species-specific control of any pest or vector species with an XY sex-determination system by targeting sequences exclusive to the female sex chromosome