1,919 research outputs found

    THE PRE-CUSP PHASE OF TORMAC IV AND V

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    An heuristic analysis of the pre-cusp phase of the present Tormac experiments has been carried out. The immediate goal has been to identify the requirements for producing a stabilized pinch in Tormac V qualitatively similar to that in Tormac IV. Concurrently, V has been modified to increase the pinch current and experimental investigation is underway. The experimental procedure is to introduce a toroidal magnetic field into the gas filled chamber. A toroidal electric field is then induced which ionizes the gas; the associated toroidal current simultaneously pinches the discharge. Uncertainty about the details of this process, in particular, about the amount of toroidal flux trapped within the pinch, has led to a one parameter theory. Speculation about the plasma heating mechanism and the subsequent interaction of pinch and cusp is left aside at this time. The chambers are basically rectangular in cross section; but, for simplicity, an equivalent radius is used. Although the experimental discharge probably evolves into a diffuse pinch, a cylindrical sheet pinch model is studied as a first step in understanding the qualitative features of the experiment. A simple Alfven scaling for instability time scales, appropriate for the previous weak pinch and considered in the design of the ringing frequency of the induction circuit is now supplemented by the sheet pinch model. If merited, a more quantitative numerical diffuse pinch model can be developed later. It should be pointed out that cusp confinement, the central problem of the Tormac program, is not addressed here. The goal is simply to identify the requirements for reproducing this particular phase of the Tormac IV experiment

    Capillary deformations of bendable films

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    We address the partial wetting of liquid drops on ultrathin solid sheets resting on a deformable foundation. Considering the membrane limit of sheets that can relax compression through wrinkling at negligible energetic cost, we revisit the classical theory for the contact of liquid drops on solids. Our calculations and experiments show that the liquid-solid-vapor contact angle is modified from the Young angle, even though the elastic bulk modulus (E) of the sheet is so large that the ratio between the surface tension γ and E is of molecular size. This finding establishes a new type of “soft capillarity” that stems from the bendability of thin elastic bodies rather than from material softness. We also show that the size of the wrinkle pattern that emerges in the sheet is fully predictable, thus resolving a puzzle noticed in several previous attempts to model “drop-on-a-floating-sheet” experiments, and enabling a reliable usage of this setup for the metrology of ultrathin films

    A systematic review of the quality of life of carers of children with cleft lip and/or plate

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    Caring for an infant or child requires a significant amount of time, energy and resources; this burden is further increased when the infant or child has a chronic condition or disability. Prior research has demonstrated that caregiving for a child with special needs impacts upon parents or carers mental health, well-being and quality of life. This article systematically reviews the literature pertaining to the impact of caring for a child with cleft lip and /or palate upon parental quality of life. A search of four databases was conducted with a number of key terms; the titles, abstracts and finally the whole article were read and assessed for relevance. Only articles written in English were included in the review. The results yielded four relevant articles; that displayed inconsistent results. The results of these articles are reviewed. It was evident that the construct of quality of life was narrowly operationalised in all four articles either being assessed as health-related quality of life or as the impact upon the family. Further all four studies emanated from the same country. The limitations are discussed with recommendations made for future research endeavours

    Analyses of the OSU-MASLWR Experimental Test Facility

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    Today, considering the sustainability of the nuclear technology in the energy mix policy of developing and developed countries, the international community starts the development of new advanced reactor designs. In this framework, Oregon State University (OSU) has constructed, a system level test facility to examine natural circulation phenomena of importance to multi-application small light water reactor (MASLWR) design, a small modular pressurized water reactor (PWR), relying on natural circulation during both steady-state and transient operation. The target of this paper is to give a review of the main characteristics of the experimental facility, to analyse the main phenomena characterizing the tests already performed, the potential transients that could be investigated in the facility, and to describe the current IAEA International Collaborative Standard Problem that is being hosted at OSU and the experimental data will be collected at the OSU-MASLWR test facility. A summary of the best estimate thermal hydraulic system code analyses, already performed, to analyze the codes capability in predicting the phenomena typical of the MASLWR prototype, thermal hydraulically characterized in the OSU-MASLWR facility, is presented as well

    A prototypical model for tensional wrinkling in thin sheets

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    The buckling and wrinkling of thin films has recently seen a surge of interest among physicists, biologists, mathematicians and engineers. This has been triggered by the growing interest in developing technologies at ever decreasing scales and the resulting necessity to control the mechanics of tiny structures, as well as by the realization that morphogenetic processes, such as the tissue-shaping instabilities occurring in animal epithelia or plant leaves, often emerge from mechanical instabilities of cell sheets. While the most basic buckling instability of uniaxially compressed plates was understood by Euler more than 200 years ago, recent experiments on nanometrically thin (ultrathin) films have shown significant deviations from predictions of standard buckling theory. Motivated by this puzzle, we introduce here a theoretical model that allows for a systematic analysis of wrinkling in sheets far from their instability threshold. We focus on the simplest extension of Euler buckling that exhibits wrinkles of finite length - a sheet under axisymmetric tensile loads. This geometry, whose first study is attributed to Lam´e, allows us to construct\ud a phase diagram that demonstrates the dramatic variation of wrinkling patterns from near-threshold to far-from-threshold conditions. Theoretical arguments and comparison to experiments show that for thin sheets the far-from-threshold regime is expected to emerge under extremely small compressive loads, emphasizing the relevance of our analysis for nanomechanics applications

    Assessing chronological age of unaccompanied minors in Southern Italy

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    The increasing volume of, and subsequent complexities resulting from, migratory flows in the broader context of globalization has led to a range of problems, not only the protection of human rights and disease control but also the identification of those with the right to apply for refugee status and the age assessment of unaccompanied minors. Italy is a magnet for immigration from other countries bordering the Mediterranean Sea because the Italian coasts are within easy reach. In Italy, as in other western countries, unaccompanied asylum seekers deemed to be younger than 18 years face a very different path through the immigration system from that experienced by adults. Generally, adults are subject to immediate deportation or detention in jail. Minors are processed through the juvenile system, where detection is not mandatory; they will often have access to educational programs and may be granted a residency permit. The Section of Legal Medicine of the University of Bari was approached by immigration police authorities and judges to explore the possibility of examining unaccompanied asylum seekers, who claim do be younger than 18 years, to assess their age. A group of forensic pathologists and odontologists performed this evaluation relying on the skeletal maturation as seen on radiographs of the wrist and the pelvis for iliac crests and on an orthopantomograph, together with background information and clinical examination of each individual. Case studies are presented. This article does not attempt to give a definitive account of the different scientific methods for the assessment of age. It is important to understand some of the methods that may be used in an attempt to assess developmental maturity and from which it may be possible to ''read off'' an approximate chronological age. © 2011 by Lippincott Williams & Wilkins

    Radiographic dental implants recognition for geographic evaluation in human identification

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    Dental implants for prosthetic rehabilitation with fixed crown or mobile partial/total dentures is a very common oral treatment among the population in Italy as elsewhere. There is a great number of implant systems of different designs. However, a catalogue of radiographic images and a description of the dental implants available in Italy would be useful in order to identify the manufacturer and the type of implant encountered in forensic casework. When an unidentified body is found with one or more implants in the jaws, and no dental record is available, clues gleaned from the type of implants used could give direction to the investigation. In this study Italian implant manufactures were contacted and asked to provide specimen implants. Digital radiographs were taken of all the implants donated at 0°, 30°, and 60° horizontal rotation, combined with -20°, -10°, 0°, +10°, and +20° vertical inclination relative to the radiographic beam and the X-ray sensor. A total of 15 images per implant were taken and examined to identify consistent, unique features that would aid in implant recognition. Only those observations made from radiographs between -10° and +10° vertical inclination would ever be used for definite identification of any implant. The information from this study should be considered a survey of the commercial distribution of dental implants in Italy through their digital radiographic images. It is also a starting point for a wider geographical evaluation of different manufacturers in other countries and continents. The radiographic images provided should help both the forensic odontologist and the prosthodontist to identify pre-existing implants which they may discover from their radiographic images

    Hostile mood and social strain during daily life: A test of the transactional model.

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    Hostility is a multidimensional construct related to cardiovascular (CV) disease risk. Daily hostile mood and social interactions may precipitate stress-related CV responses in hostile individuals. Purpose: Determine whether trait cognitive hostility best predicts daily hostile mood and social interactions relative to other trait hostility factors and explore the temporal links between these daily measure
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