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13 result(s) for "Tigani, K"
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Physical properties of the trans-Neptunian object (38628) Huya from a multi-chord stellar occultation
Within our international program to obtain accurate physical properties of trans-Neptunian objects (TNOs) we predicted a stellar occultation by the TNO (38628) Huya of the star Gaia DR2 4352760586390566400 (mG = 11.5 mag.) for March 18, 2019. After an extensive observational campaign, we updated the prediction and it turned out to be favorable to central Europe. Therefore, we mobilized half a hundred professional and amateur astronomers, and the occultation was finally detected from 21 telescopes located at 18 sites. This makes the Huya event one of the best ever observed stellar occultation by a TNO in terms of the number of chords. We determine accurate size, shape, and geometric albedo, and we also provide constraints on the density and other internal properties of this TNO. The 21 positive detections of the occultation by Huya allowed us to obtain well-separated chords which permitted us to fit an ellipse for the limb of the body at the moment of the occultation (i.e., the instantaneous limb) with kilometric accuracy. The projected semi-major and minor axes of the best ellipse fit obtained using the occultation data are (a', b') = (217.6 \\(\\pm\\) 3.5 km, 194.1 \\(\\pm\\) 6.1 km) with a position angle of the minor axis P' = 55.2 \\(\\pm\\) 9.1 degrees. From this fit, the projected area-equivalent diameter is 411.0 \\(\\pm\\) 7.3 km. This diameter is compatible with the equivalent diameter for Huya obtained from radiometric techniques (D = 406 \\(\\pm\\) 16 km). From this instantaneous limb, we obtained the geometric albedo for Huya (p\\(\\rm_V\\) = 0.079 \\(\\pm\\) 0.004) and we explored possible 3D shapes and constraints to the mass density for this TNO. We did not detect the satellite of Huya through this occultation, but the presence of rings or debris around Huya is constrained using the occultation data. We also derived an upper limit for a putative Pluto-like global atmosphere of about p\\(_{\\rm surf}\\) = 10 nbar.
A large topographic feature on the surface of the trans-Neptunian object (307261) 2002 MS\\(_4\\) measured from stellar occultations
This work aims at constraining the size, shape, and geometric albedo of the dwarf planet candidate 2002 MS4 through the analysis of nine stellar occultation events. Using multichord detection, we also studied the object's topography by analyzing the obtained limb and the residuals between observed chords and the best-fitted ellipse. We predicted and organized the observational campaigns of nine stellar occultations by 2002 MS4 between 2019 and 2022, resulting in two single-chord events, four double-chord detections, and three events with three to up to sixty-one positive chords. Using 13 selected chords from the 8 August 2020 event, we determined the global elliptical limb of 2002 MS4. The best-fitted ellipse, combined with the object's rotational information from the literature, constrains the object's size, shape, and albedo. Additionally, we developed a new method to characterize topography features on the object's limb. The global limb has a semi-major axis of 412 \\(\\pm\\) 10 km, a semi-minor axis of 385 \\(\\pm\\) 17 km, and the position angle of the minor axis is 121 \\(^\\circ\\) \\(\\pm\\) 16\\(^\\circ\\). From this instantaneous limb, we obtained 2002 MS4's geometric albedo and the projected area-equivalent diameter. Significant deviations from the fitted ellipse in the northernmost limb are detected from multiple sites highlighting three distinct topographic features: one 11 km depth depression followed by a 25\\(^{+4}_{-5}\\) km height elevation next to a crater-like depression with an extension of 322 \\(\\pm\\) 39 km and 45.1 \\(\\pm\\) 1.5 km deep. Our results present an object that is \\(\\approx\\)138 km smaller in diameter than derived from thermal data, possibly indicating the presence of a so-far unknown satellite. However, within the error bars, the geometric albedo in the V-band agrees with the results published in the literature, even with the radiometric-derived albedo.
Pluto's lower atmosphere and pressure evolution from ground-based stellar occultations, 1988-2016
Context. Pluto's tenuous nitrogen (N2) atmosphere undergoes strong seasonal effects due to high obliquity and orbital eccentricity, and has been recently (July 2015) observed by the New Horizons spacecraft. Goals are (i) construct a well calibrated record of the seasonal evolution of surface pressure on Pluto and (ii) constrain the structure of the lower atmosphere using a central flash observed in 2015. Method: eleven stellar occultations by Pluto observed between 2002 and 2016 are used to retrieve atmospheric profiles (density, pressure, temperature) between \\(\\sim\\)5 km and \\(\\sim\\)380 km altitude levels (i.e. pressures from about 10 microbar to 10 nanobar). Results: (i) Pressure has suffered a monotonic increase from 1988 to 2016, that is compared to a seasonal volatile transport model, from which tight constraints on a combination of albedo and emissivity of N2 ice are derived; (ii) A central flash observed on 2015 June 29 is consistent with New Horizons REX profiles, provided that (a) large diurnal temperature variations (not expected by current models) occur over Sputnik Planitia and/or (b) hazes with tangential optical depth of about 0.3 are present at 4-7 km altitude levels and/or (c) the nominal REX density values are overestimated by an implausibly large factor of about 20% and/or (d) higher terrains block part of the flash in the Charon facing hemisphere.
Childhood idiopathic steroid-resistant nephrotic syndrome at a single center in Khartoum
Prevalence, clinicopathological features, and outcome of childhood idiopathic steroid-resistant nephrotic syndrome (ISRNS) vary in different countries. We report on these parameters in a single center in Khartoum. We retrospectively reviewed all the records of children with idiopathic nephrotic syndrome (INS) followed up in the pediatric renal unit, Soba Hospital, Khartoum between 2001 and 2012. ISRNS was defined as no remission within four weeks of daily prednisolone at a dose of 60 mg/m2. In 430 children with INS 130 (28%) had SRNS with a mean age of 7.7 ± 4.12 years. Males were 78 (60%). At presentation, hematuria was recorded in 57%, hypertension was recorded in 48%, and renal impairment in 15%. Histopathology showed focal segmental glomerulosclerosis in 40.8%, mesangioproliferative glomerulonephritis (22.3%), mesangiocapillary glomerulonephritis (16.9%), minimal change disease (MCD) (16.2%), and membranous glomerulonephritis (3.8%). Therapy included cyclosporine in 38.5%, additional therapy with cyclophosphamide, mycophenolate mofetil or tacrolimus in 20.8%, and steroids ± diuretics ± angiotensin converting enzyme (ACE) inhibitors in 40.7%. After 3.64 ± 2.84 years, 26.8% had complete remission (CR), 18.6% partial remission (PR), 26.8% were unremitting, 21.5% had chronic kidney disease (CKD), 1.6% died, and 4.6% were lost to follow-up. Non- MCD cases had significantly lower CR and higher CKD rates than MCD (P = 0.047 and 0.041, respectively). Cyclosporine ± additional therapy was significantly associated with higher rate of CR than steroids ± ACE inhibitors ± diuretics (P = 0.001), but the prevalence of CKD between the two groups was not significantly different (P = 0.604). Impaired renal function and hypertension at presentation were risk factors for CKD (P = 0.001 and 0.001, respectively). In Sudanese
Lifestyle and self-rated health: a cross-sectional study of 3,601 citizens of Athens, Greece
Background Self-rated health (SRH) is a popular health measure determined by multiple factors. International literature is increasingly focusing on health-related behaviors such as smoking, dietary habits, physical activity, even religiosity. However, population-based studies taking into account multiple putative determinants of SRH in Greece are scarce. The aim of this study was to clarify possible determinants of SRH with an emphasis on the relationship between SRH and lifestyle variables in a large sample of urban citizens. Methods In this one-year cross-sectional study, a stratified random sample of 3,601 urban citizens was selected. Data were collected using an interview-based questionnaire about various demographic, socioeconomic, disease- and lifestyle related factors such as smoking, physical activity, dietary habits, sleep quality and religiosity. Multivariate logistic regression was used separately in three age groups [15-29 (N = 1,360), 30-49 (N = 1,122) and 50+ (N = 1,119) years old] in order to identify putative lifestyle and other determinants of SRH. Results Reporting of good SRH decreased with age (97.1%, 91.4% and 74.8%, respectively). Overall, possible confounders of the lifestyle-SRH relationship among age groups were sex, education, hospitalization during the last year, daily physical symptoms and disease status. Poor SRH was associated with less physical activity in the 15-29 years old (OR 2.22, 95%CI 1.14-4.33), with past or heavy smoking, along with no sleep satisfaction in the 30-49 years old (OR 3.23, 95%CI 1.35-7.74, OR 2.56, 95%CI 1.29-5.05, OR 1.79, 95%CI 1.1-2.92, respectively) and with obesity and no sleep satisfaction in the 50+ years old individuals (OR 1.83, 95%CI 1.19-2.81, OR 2.54, 95%CI 1.83-3.54). Sleep dissatisfaction of the 50+ years old was the only variable associated with poor SRH at the 0.001 p level of significance (OR 2.45, 99%CI 1.59 to 3.76). Subgroup analyses of the 15-19 years old individuals also revealed sleep dissatisfaction as the only significant variable correlated with SRH. Conclusions Slight differences in lifestyle determinants of SRH were identified among age groups. Sleep quality emerged as an important determinant of SRH in the majority of participants.
Safety and efficacy of the RTS,S/AS01E candidate malaria vaccine given with expanded-programme-on-immunisation vaccines: 19 month follow-up of a randomised, open-label, phase 2 trial
The RTS,S/AS01E candidate malaria vaccine is being developed for immunisation of infants in Africa through the expanded programme on immunisation (EPI). 8 month follow-up data have been reported for safety and immunogenicity of RTS,S/AS01E when integrated into the EPI. We report extended follow-up to 19 months, including efficacy results. We did a randomised, open-label, phase 2 trial of safety and efficacy of the RTS,S/AS01E candidate malaria vaccine given with EPI vaccines between April 30, 2007, and Oct 7, 2009, in Ghana, Tanzania, and Gabon. Eligible children were 6–10 weeks of age at first vaccination, without serious acute or chronic illness. All children received the EPI diphtheria, tetanus, pertussis (inactivated whole-cell), and hepatitis-B vaccines, Haemophilus influenzae type b vaccine, and oral polio vaccine at study months 0, 1, and 2, and measles vaccine and yellow fever vaccines at study month 7. Participants were randomly assigned (1:1:1) to receive three doses of RTS,S/AS01E at 6, 10, and 14 weeks (0, 1, 2 month schedule) or at 6 weeks, 10 weeks, and 9 months (0, 2, 7 month schedule) or placebo. Randomisation was according to a predefined block list with a computer-generated randomisation code. Detection of serious adverse events and malaria was by passive case detection. Antibodies against Plasmodium falciparum circumsporozoite protein and HBsAg were monitored for 19 months. This study is registered with ClinicalTrials.gov, number NCT00436007. 511 children were enrolled. Serious adverse events occurred in 57 participants in the RTS,S/AS01E 0, 1, 2 month group (34%, 95% CI 27–41), 47 in the 0, 1, 7 month group (28%, 21–35), and 49 (29%, 22–36) in the control group; none were judged to be related to study vaccination. At month 19, anticircumsporozoite immune responses were significantly higher in the RTS,S/AS01E groups than in the control group. Vaccine efficacy for the 0, 1, 2 month schedule (2 weeks after dose three to month 19, site-adjusted according-to-protocol analysis) was 53% (95% CI 26–70; p=0·0012) against first malaria episodes and 59% (36–74; p=0·0001) against all malaria episodes. For the entire study period, (total vaccinated cohort) vaccine efficacy against all malaria episodes was higher with the 0, 1, 2 month schedule (57%, 95% CI 33–73; p=0·0002) than with the 0, 1, 7 month schedule (32% CI 16–45; p=0·0003). 1 year after dose three, vaccine efficacy against first malaria episodes was similar for both schedules (0, 1, 2 month group, 61·6% [95% CI 35·6–77·1], p<0·001; 0, 1, 7 month group, 63·8% [40·4–78·0], p<0·001, according-to-protocol cohort). Vaccine efficacy was consistent with the target put forward by the WHO-sponsored malaria vaccine technology roadmap for a first-generation malaria vaccine. The 0, 1, 2 month vaccine schedule has been selected for phase 3 candidate vaccine assessment. Program for Appropriate Technology in Health Malaria Vaccine Initiative; GlaxoSmithKline Biologicals.
The Healthy Lifestyle and Personal Control Questionnaire (HLPCQ): a novel tool for assessing self-empowerment through a constellation of daily activities
Background The main goal of stress management and health promotion programs is to improve health by empowering people to take control over their lives. Daily health-related lifestyle choices are integral targets of these interventions and critical to evaluating their efficacy. To date, concepts such as self-efficacy, self-control and empowerment are assessed by tools that only partially address daily lifestyle choices. The aim of this study is to validate a novel measurement tool, the Healthy Lifestyle and Personal Control Questionnaire (HLPCQ), which aims to assess the concept of empowerment through a constellation of daily activities. Methods Therefore, we performed principal component analysis (PCA) of 26 items that were derived from the qualitative data of several stress management programs conducted by our research team. Results The PCA resulted in the following five-factor solution: 1) Dietary Healthy Choices, 2) Dietary Harm Avoidance, 3) Daily Routine, 4) Organized Physical Exercise and 5) Social and Mental Balance. All subscales showed satisfactory internal consistency and variance, relative to theoretical score ranges. Subscale scores and the total score were significantly correlated with perceived stress and health locus of control, implying good criterion validity. Associations with sociodemographic data and other variables, such as sleep quality and health assessments, were also found. Conclusions The HLPCQ is a good tool for assessing the efficacy of future health-promoting interventions to improve individuals’ lifestyle and wellbeing.
Determinants of Self-Rated Health in a Representative Sample of a Rural Population: A Cross-Sectional Study in Greece
Self-rated health (SRH) is a health measure related to future health, mortality, healthcare services utilization and quality of life. Various sociodemographic, health and lifestyle determinants of SRH have been identified in different populations. The aim of this study is to extend SRH literature in the Greek population. This is a cross-sectional study conducted in rural communities between 2001 and 2003. Interviews eliciting basic demographic, health-related and lifestyle information (smoking, physical activity, diet, quality of sleep and religiosity) were conducted. The sample consisted of 1,519 participants, representative of the rural population of Tripoli. Multinomial regression analysis was conducted to identify putative SRH determinants. Among the 1,519 participants, 489 (32.2%), 790 (52%) and 237 (15.6%) rated their health as “very good”, “good” and “poor” respectively. Female gender, older age, lower level of education and impaired health were all associated with worse SRH, accounting for 16.6% of SRH variance. Regular exercise, healthier diet, better sleep quality and better adherence to religious habits were related with better health ratings, after adjusting for sociodemographic and health-related factors. BMI and smoking did not reach significance while exercise and physical activity exhibited significant correlations but not consistently across SRH categories. Our results support previous findings indicating that people following a more proactive lifestyle pattern tend to rate their health better. The role of stress-related neuroendocrinologic mechanisms on SRH and health in general is also discussed.
Gender differences in Greek centenarians. A cross-sectional nation-wide study, examining multiple socio-demographic and personality factors and health locus of control
Background Centenarians are exceptional ageing paradigms, offering valuable information on achieving longevity. Although, there are several studies examining different biomedical factors as determinants of longevity in centenarians, little is known about gender differences with respect to personality traits and health locus of control. Methods Nation -wide study carried out in Greece, between 2007 and 2010. Our final sample of analysis consisted of 400 centenarians who reported on sociodemographic, disease-related and personality factors and health locus of control (HLC). Gender differences were investigated by simple nonparametric comparisons. Bivariate correlations between personality factors and internal and external HLC were obtained. Results Women centenarians outnumbered men by a ratio of 1.68 to 1. Significant gender sociodemographic differences were noted, with men reporting less often widowhood, more often centenarian 1st degree relatives and smoking. Higher BMI score was measured in males than females. Concerning personality variables, females were more reward-dependent and adaptable than men, while men were more optimistic than women. No differences were found on health locus of control profile between the genders. Positive correlations between self-directness and spirituality with internal locus of control in men and negative correlations between optimism and external locus of control in women emerged as the main gender disparities in the correlation analyses. Self-directness in men and optimism in women were consistently correlated with the two HLC subscales. Conclusions Gender differences should be incorporated in future basic research and epidemiological studies of longevity. Informed policies on ageing and wellbeing programs should also take into account gender issues to increase efficacy by targeting health locus of control.
Different strokes : a management dilemma
Stroke is a common medical emergency resulting from numerous pathophysiological mechanisms and with varied clinical manifestations; as such, the diagnosis of stroke requires diligent clinical assessment. When different stroke syndromes occur in the same patient, it may cause a dilemma in terms of diagnosis and management. This continuing medical education article describes an interesting patient with recurrent neurological events, highlighting the complex pathophysiological processes associated with cerebrovascular syndromes. It offers readers the opportunity to apply their own basic neuroscience knowledge and clinical skills to solve the challenges encountered during the course of diagnosing and treating this patient. Specifically, the article aims to familiarise readers with an approach to diagnosing brainstem strokes and the diverse manifestations of a common stroke syndrome.