The complex circumstellar environment of supernova 2023ixf.

The early evolution of a supernova (SN) can reveal information about the environment and the progenitor star. When a star explodes in vacuum, the first photons to escape from its surface appear as a brief, hours-long shock-breakout flare1,2, followed by a cooling phase of emission. However, for stars exploding within a distribution of dense, optically thick circumstellar material (CSM), the first photons escape from the material beyond the stellar edge and the duration of the initial flare can extend to several days, during which the escaping emission indicates photospheric heating3. Early serendipitous observations2,4 that lacked ultraviolet (UV) data were unable to determine whether the early emission is heating or cooling and hence the nature of the early explosion event. Here we report UV spectra of the nearby SN 2023ixf in the galaxy Messier 101 (M101). Using the UV data as well as a comprehensive set of further multiwavelength observations, we temporally resolve the emergence of the explosion shock from a thick medium heated by the SN emission. We derive a reliable bolometric light curve that indicates that the shock breaks out from a dense layer with a radius substantially larger than typical supergiants.

Wide-angle static and dynamic light scattering under shear.

We develop and characterize a wide angle static and dynamic light scattering under shear setup. The apparatus is suitable for the study of the structure and the dynamics of soft materials systems with a sub-micron characteristic length scale. The shear device consists in two parallel plates, and the optical setup allows us to perform light scattering measurements in any plane that contains the gradient of the velocity field direction. We demonstrate several capabilities of our apparatus: a measurement of the evolution with shear of the first peak of the structure factor of a concentrated suspension of spherical particles, both in the compression and extension quadrants of the shear flow, and the measurement of the velocity profile in dynamic light scattering. We present a theoretical treatment of light scattering under flow that takes into account the Gaussian character of the illumination and detection optical paths, in the case where the scattering volume extension is smaller than the gap of the flow cell, and compare with experimental measurements.

Dental status, visits, and functional ability and dietary intake of elderly in Israel.

BACKGROUND: Epidemiological studies have shown deterioration in dental health accompanying the ageing process. Tooth loss increases with age. Chewing ability is closely correlated with number of natural teeth present: there is a threshold of 20-21 teeth, below which chewing ability declines. The government of Israel is currently considering adding dental treatment for elderly to the basket of services of the National Health Insurance Law. Information on the influence of elderly's dental health on nutrition and general health status can contribute to the decision making process. METHODS: Secondary analysis of data collected on a subsample (N = 1776) of the cross-sectional Mabat Zahav - National Health and Nutrition Survey of the Elderly was done. Intakes of energy, fiber, protein, fruits and vegetables, associations with dental visits, dentures presence and functional ability were analyzed. Linear regression adjusted for confounders was performed. RESULTS: Statistically significant differences in dietary intake of energy, fiber, protein and vegetables were found between elderly who visited a dentist in the last year and those who did not. Elderly who possessed dentures had lower dietary intakes than their dentate counterparts. Elderly with functional problems such as impaired chewing had worse dietary intakes than the others. This was so after controlling for education, degree of interest in the relationship between nutrition and health and reading the nutrition label. CONCLUSIONS: The findings in our study suggest that those who visited a dentist in the last year, had natural teeth and no denture/s and reported no chewing problems had better dietary intake. The results emphasize the importance of maintaining adequate dental health, preserving natural teeth and regular dental visits in the elderly to assure adequate nutrient status in this age group.

Effects of oxygen on regional hemodynamics in hemorrhagic shock.

This study investigated mechanisms of the hemodynamic effects of oxygen in hemorrhagic shock induced by bleeding 30% of the total blood volume in anesthetized rats. An ultrasonic flowmeter was used to monitor regional blood flow. Changes in tissue perfusion were assessed by the laser-Doppler technique. The inhalation of 100% oxygen induced a significant increase in mean arterial blood pressure (MABP) and vascular resistance in the hindquarters, with a concomitant decrease in blood flow in the distal aorta and biceps femoris muscle. In contrast, oxygen did not change vascular resistance in the superior mesenteric artery (SMA) and renal beds and induced a significant increase in blood flow to the renal artery, SMA, and small bowel in hemorrhaged rats. L-Arginine (100 mg/kg iv) but not D-arginine or the vehicle (0.9% NaCl) completely abolished the effects of oxygen on blood pressure and reversed its effects on blood flow and resistance in the hindquarters and biceps femoris muscle. Administration of the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester (50 mg/kg iv) significantly increased MABP and the resistance in the three vascular beds. Pretreatment of hemorrhaged rats with a superoxide dismutase mimic, the NO-stable radical 2,2,6,6-tetramethylpiperidine-N-oxyl (5 mg/kg iv), resulted in significantly diminished effects of oxygen on hindquarter hemodynamics. These results demonstrate a differential effect of oxygen, which increases vascular resistance in the hindquarters without a significant effect in the splanchnic and renal beds, thus favoring an increase in splanchnic and renal perfusion. It is suggested that inactivation of NO by reactive oxygen species may underlie the effects of oxygen on hindquarter vascular tone during shock.

Vasoactive therapy versus placebo in the treatment of sudden hearing loss: a double-blind clinical study.

Twenty-seven patients suffering from sudden sensorineural hearing loss (SHL) were randomly assigned to one of two groups: a treatment group (n = 13) receiving intravenous procaine and low-molecular-weight dextran, and a placebo control group (n = 14). The effect of treatment was analyzed by means of an analysis of variance and covariance procedures. Results indicated nonsignificant differences between the groups on all outcome indices measured. Sex, age, time since the onset of symptoms to the initiation of therapy, audiogram configuration, and initial severity of hearing loss did not significantly affect the results. These findings suggest that the therapeutic effects of this vasodilator are not superior to a placebo.

The use of patients as student evaluators.

Current evaluation of medical students in their clinical clerkships is usually performed by their clinical tutors, and emphasizes knowledge, skills and behavior. However, it is not at all certain that the clinical tutors adequately appreciate the behavioral aspects of the student-patient interrelationship. Since these interactions are not directly observed by the tutors, their evaluation is based largely on second hand information. In the present study, patient opinion regarding student behavior was collected and compared to tutors' evaluation of the student. One hundred and eighty one patients and 31 clinical tutors evaluated 41 medical students during a 6 week internal medicine clerkship, using a specially designed patient questionnaire and tutors' rating form. An analysis of the correlation between tutors' individual rating parameters and the global score revealed high correlation for those parameters associated with clinical knowledge and skills, but lower correlations for parameters associated with students' relationship to patients. The study reveals difficulties associated with the evaluation of students by patients. The process is time-consuming, and introduces tension between students and patients. In addition the patients appeared to be poor discriminators in evaluating medical students. Finally, the study points out that tutors do not assign sufficient importance to the student-patient relationship in the global clerkship score.