3,846 research outputs found

    Study made of large amplitude fuel sloshing

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    Study of resonant oscillations of an ideal fluid in a cylindrical tank is used to obtain a better understanding of fuel sloshing in large liquid booster. More realistic structural design criteria may be formulated when the dynamic response of the liquid in a cylindrical tank can be predicted analytically

    An integrated analysis of micro- and macro-habitat features as a tool to detect weather-driven constraints: a case study with cavity nesters

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    The effects of climate change on animal populations may be shaped by habitat characteristics at both micro- and macro-habitat level, however, empirical studies integrating these two scales of observation are lacking. As analyses of the effects of climate change commonly rely on data from a much larger scale than the microhabitat level organisms are affected at, this mismatch risks hampering progress in developing understanding of the details of the ecological and evolutionary responses of organisms and, ultimately, effective actions to preserve their populations. Cavity nesters, often with a conservation status of concern, are an ideal model because the cavity is a microenvironment potentially different from the macroenvironment but nonetheless inevitably interacting with it. The lesser kestrel (Falco naumanni) is a cavity nester which was until recently classified by as Vulnerable species. Since 2004, for nine years, we collected detailed biotic and abiotic data at both micro- and macro-scales of observation in a kestrel population breeding in the Gela Plain (Italy), a Mediterranean area where high temperatures may reach lethal values for the nest content. We show that macroclimatic features needed to be integrated with both abiotic and biotic factors recorded at a microscale before reliably predicting nest temperatures. Among the nest types used by lesser kestrels, we detected a preferential occupation of the cooler nest types, roof tiles, by early breeders whereas, paradoxically, late breeders nesting with hotter temperatures occupied the overheated nest holes. Not consistent with such a suggested nest selection, the coolest nest type did not host a higher reproductive success than the overheated nests. We discussed our findings in the light of cavity temperatures and nest types deployed within conservation actions assessed by integrating selected factors at different observation scales

    UNILATERAL SENSORINEURAL HEARING LOSS IN SCHOLASTIC AGE SUBJECTS: PSYCHOPEDAGOGICAL ASPECTS

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    The Authors want to assess a probable significant relation between the unilateral sensorineural hearing loss and some learning difficulties and language acquisitions, often found, through our observation, in impaired children. The Authors have examined a group of subjects in their scholastic age who have this kind of hearing loss and, through several dialogues with them, they have gathered some relevant data about the difficulties that children have at school, and drawn up a questionnaire

    A Design Heritage-Based Forecasting Methodology for Risk Informed Management of Advanced Systems

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    The development of next generation systems often carries with it the promise of improved performance, greater reliability, and reduced operational costs. These expectations arise from the use of novel designs, new materials, advanced integration and production technologies intended for functionality replacing the previous generation. However, the novelty of these nascent technologies is accompanied by lack of operational experience and, in many cases, no actual testing as well. Therefore some of the enthusiasm surrounding most new technologies may be due to inflated aspirations from lack of knowledge rather than actual future expectations. This paper proposes a design heritage approach for improved reliability forecasting of advanced system components. The basis of the design heritage approach is to relate advanced system components to similar designs currently in operation. The demonstrated performance of these components could then be used to forecast the expected performance and reliability of comparable advanced technology components. In this approach the greater the divergence of the advanced component designs from the current systems the higher the uncertainty that accompanies the associated failure estimates. Designers of advanced systems are faced with many difficult decisions. One of the most common and more difficult types of these decisions are those related to the choice between design alternatives. In the past decision-makers have found these decisions to be extremely difficult to make because they often involve the trade-off between a known performing fielded design and a promising paper design. When it comes to expected reliability performance the paper design always looks better because it is on paper and it addresses all the know failure modes of the fielded design. On the other hand there is a long, and sometimes very difficult road, between the promise of a paper design and its fulfillment; with the possibility that sometimes the reliability promise is not fulfilled at all. Decision makers in advanced technology areas have always known to discount the performance claims of a design to a degree in proportion to its stage of development, and at times have preferred the more mature design over the one of lesser maturity even with the latter promising substantially better performance once fielded. As with the broader measures of performance this has also been true for projected reliability performance. Paper estimates of potential advances in design reliability are to a degree uncertain in proportion to the maturity of the features being proposed to secure those advances. This is especially true when performance-enhancing features in other areas are also planned to be part of the development program

    Associations Between Major Depression, Health-risk Behaviors, and Medication Adherence Among Hiv-positive Adults Receiving Medical Care in Georgia

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    Background: There are approximately 1.2 million people in the United States living with HIV, and 25.6% of HIV-positive adults suffer from depression. The purpose of this study is to examine the contribution of depression to substance use and medication adherence among HIV-positive adults receiving medical care for HIV in Georgia. Methods: Secondary data with a probability sample of 775 HIV-positive adults who took part in the 2009-2013 Georgia Medical Monitoring Project (MMP) were analyzed. Descriptive analyses and multivariate logistic regressions were conducted to assess relationships between depression and current cigarette smoking, injection drug use, other non-injection drug use, and medication adherence, adjusting for sociodemographic covariates (age, gender, race, and education). All analyses accounted for non-response and complex sampling design. Results: Among HIV-positive adults in Georgia, 8.5% met the criteria for major depression, including 13.7% of women and 6.5% of men. Heterosexual adults had a higher percentage of major depression (10.7%) compared to adults who identified as bisexual (7.4%) or homosexual (5.8%). Major depression was also higher among adults with a high school diploma or GED (12.7%) compared to adults with a higher level of education (5.2%). Major depression was associated with a greater odds of current cigarette smoking (AOR 2.7; 95% CI: 1.5, 5.2) and other non-injection drug use (2.5; 95% CI: 1.4, 4.4), after adjusting for sociodemographic variables. The three measures of medication adherence were not statistically significantly associated with major depression. Conclusions: As previously observed for the general population, we found, among HIV-positive adults, significant associations between depression and smoking and other non-injection drug use. Because HIVpositive adults have ongoing encounters with healthcare providers, screening and treatment for depression and other co-morbid substance use is needed to reduce an additional health burden in this population

    Kawasaki disease in Sicily: clinical description and markers of disease severity

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    Background: Kawasaki disease (KD) is an acute systemic vasculitis of small and middle size arteries; 15-25 % of untreated patients and 5 % of patients treated with intravenous immunoglobulin (IVIG) develop coronary artery lesions (CAL). Many studies tried to find the most effective treatment in the management of resistant KD and to select the risk factors for CAL. Our data are assessed on children from west Sicily, characterized by a genetic heterogeneity. Methods: We studied the clinical data of 70 KD Sicilian children (36 males: 51 %; 34 females: 49 %), analysed retrospectively, including: demographic and laboratory parameters; echocardiographic findings at diagnosis, at 2, 6 and 8 weeks, and at 1 year after the onset of the illness. Results: Forty-seven had Typical KD, three Atypical KD and twenty Incomplete KD. Age at the disease onset ranged from 0.1 to 8.9 years. IVIG were administered 5 \ub1 2 days after the fever started. Defervescence occurred 39 \ub1 26 hours after the first IVIG infusion. Fifty-six patients (80 %) received 1 dose of IVIG (responders); 14 patients (20 %) had a resistant KD, with persistent fever after the first IVIG dose (non responders). Ten (14 %) non responders responded to the second dose, 4 (5 %) responded to three doses; one needed treatment with high doses of steroids and Infliximab. Cardiac involvement was documented in twenty-two cases (eighteen with transient dilatation/ectasia, fifteen with aneurysms). Pericardial effusion, documented in eleven, was associated with coronaritis and aneurysms, and was present earlier than coronary involvement in seven. Hypoalbuminemia, D-dimer pre-IVIG, gamma-GT pre-IVIG showed a statistically significant direct correlation with IVIG doses, highlighting the role of these parameters as predictor markers of refractory disease. The persistence of elevated CRP, AST, ALT levels, a persistent hyponatremia and hypoalbuminemia after IVIG therapy, also had a statistical significant correlation with IVIG doses. Non responders showed higher levels of D-dimer and gamma-GT pre-IVIG, persistent high levels of D-dimer, CRP, AST, ALT, hypoalbuminemia and hyponatremia after IVIG. Conclusions: This is the first study on KD in Sicily. We suggest some laboratory parameters as predictive criteria for resistant KD. Patients who show early pericarditis need careful surveillance for coronary lesions

    Coronal properties of active G-type stars in different evolutionary phases

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    We report on the analysis of XMM-Newton observations of three G-type stars in very different evolutionary phases: the "weak-line" T Tauri star HD 283572, the Zero Age Main Sequence star EK Dra and the Hertzsprung-gap giant star 31 Corn. The X-ray luminosities of the three stars are all in the range 10(30) - 10(31) erg/s. We compare the Emission Measure Distributions of these bright sources, derived from high-resolution X-ray spectra, as well as the pattern of elemental abundances vs. First Ionization Potential (FIP). The results of our analysis suggest that the coronae of these stars are very similar in terms of dominant coronal magnetic structures, in spite of differences in their evolutionary phases, surface gravities and metallicities

    Systemic lupus erythematosus and bullous pemphigoid with dramatic response to dapsone

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    Objective: Unusual clinical course Background: Bullous pemphigoid is an autoimmune blistering disease, with relapses, isolated or associated with other autoimmune diseases such as systemic lupus erythematosus (SLE). Joint manifestations rapidly respond to small or moderate doses of corticosteroids, whereas skin manifestations usually respond to antimalarial drugs. Case Report: We describe the clinical case of an 11-year-old girl with SLE. She showed bullous skin lesions with arthralgia, mild proteinuria, resolved after steroid treatment. At the tapering of her prednisone dose, the patient had new skin lesions requiring an increased dose of prednisone. She started dapsone at the dosage of 1 mg/kg/day, maintaining low dose prednisone; this treatment was successfully followed by the dramatic disappearance of skin lesions and limb pain. Conclusions: Bullous skin lesions can represent the first clinical presentation of pediatric SLE and could influence the treatment and the outcome of these patients. This case showed an atypical course as both skin manifestations and arthritis promptly and persistently resolved with dapsone without the use of high-dose glucocorticoids. Only a few cases of patients with SLE associated with bullous pemphigoid have been reported in the literature, and very few in the pediatric population

    Scaling laws of solar and stellar flares

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    In this study we compile for the first time comprehensive data sets of solar and stellar flare parameters, including flare peak temperatures T_p, flare peak volume emission measures EM_p, and flare durations t_f from both solar and stellar data, as well as flare length scales L from solar data. Key results are that both the solar and stellar data are consistent with a common scaling law of EM_p ~ T_p^4.7, but the stellar flares exhibit ~250 times higher emission measures (at the same flare peak temperature). For solar flares we observe also systematic trends for the flare length scale L(T_p) ~ T_p^0.9 and the flare duration t_F(T_p) ~ T_p^0.9 as a function of the flare peak temperature. Using the theoretical RTV scaling law and the fractal volume scaling observed for solar flares, i.e., V(L) ~ L^2.4, we predict a scaling law of EM_p ~ T_p^4.3, which is consistent with observations, and a scaling law for electron densities in flare loops, n_p ~ T_p^2/L ~ T_p^1.1. The RTV-predicted electron densities were also found to be consistent with densities inferred from total emission measures, n_p=(EM_p/q_V*V)^1/2, using volume filling factors of q_V=0.03-0.08 constrained by fractal dimensions measured in solar flares. Our results affect also the determination of radiative and conductive cooling times, thermal energies, and frequency distributions of solar and stellar flare energies.Comment: 9 Figs., (paper in press, The Astrophsycial Journal
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