A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors.

Most large (over a kilometre in diameter) near-Earth asteroids are now known, but recognition that airbursts (or fireballs resulting from nuclear-weapon-sized detonations of meteoroids in the atmosphere) have the potential to do greater damage than previously thought has shifted an increasing portion of the residual impact risk (the risk of impact from an unknown object) to smaller objects. Above the threshold size of impactor at which the atmosphere absorbs sufficient energy to prevent a ground impact, most of the damage is thought to be caused by the airburst shock wave, but owing to lack of observations this is uncertain. Here we report an analysis of the damage from the airburst of an asteroid about 19 metres (17 to 20 metres) in diameter southeast of Chelyabinsk, Russia, on 15 February 2013, estimated to have an energy equivalent of approximately 500 (±100) kilotons of trinitrotoluene (TNT, where 1 kiloton of TNT = 4.185×10(12) joules). We show that a widely referenced technique of estimating airburst damage does not reproduce the observations, and that the mathematical relations based on the effects of nuclear weapons--almost always used with this technique--overestimate blast damage. This suggests that earlier damage estimates near the threshold impactor size are too high. We performed a global survey of airbursts of a kiloton or more (including Chelyabinsk), and find that the number of impactors with diameters of tens of metres may be an order of magnitude higher than estimates based on other techniques. This suggests a non-equilibrium (if the population were in a long-term collisional steady state the size-frequency distribution would either follow a single power law or there must be a size-dependent bias in other surveys) in the near-Earth asteroid population for objects 10 to 50 metres in diameter, and shifts more of the residual impact risk to these sizes.

The effect of myocardial revascularization on malignant ventricular arrhythmias in coronary artery disease.

BACKGROUND: Malignant ventricular arrhythmia in coronary artery disease (CAD) is a severe life-threatening disease and a risk factor for sudden cardiac death. Myocardial revascularization influences the arrhythmogenic substrate of the malignant ventricular arrhythmia in the secondary prevention of sudden cardiac death. Its effectivity remains controversial. OBJECTIVES: The aim of this study is to assess the inducibility of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients after myocardial revascularization and to compare the effectivity of complete and incomplete revascularization. PATIENTS: Fifty patients with documented sustained VT or VF and CAD were examined in our department. RESULTS: Conservatively treated patients were significantly older than revascularized patients (68 +/- 8 versus 62 +/- 9 years, p<0.05). We registered a trend towards a lower inducibility of malignant ventricular arrhythmias in the revascularized group and completely revascularized subgroup, but without statistical significance. Incompletely revascularized patients comprised only of men (100% versus 66.6%, p<0.05). Fewer ICDs were implanted in the completely revascularized group (55.6% versus 92.3%, p<0.05). CONCLUSION: Myocardial revascularization has little effect on the inducibility of malignant ventricular arrhythmias after myocardial revascularization. Complete revascularization significantly decreases the need of ICD implantation when compared to incomplete one (Tab. 3, Fig. 4, Ref. 24). Full Text (Free, PDF) www.bmj.sk.

[Rare cases of acute urineous peritonitis as a consequence of a spontaneous rupture of the urinary bladder]. / Raritní prípady akutní urinózní peritonitidy zpusobené spontánní rupturou mocového mechýre.

Perforation of the urinary bladder is, in most cases, caused by a blunt or penetrative trauma, respectively by an iatrogenic trauma. A spontaneous rupture of the urinary bladder is very rare. In the literature, its relation with alcohol abuse is speculated. Due to their minimal frequency rates, the diagnosis is very difficult and, not uncommonly, the diagosis is verified only upon surgical revision. The authors present two cases of urgent diffuse peritonitis originating from spontaneous perforations of the urinary bladder.

[The first case of management of the rectovaginal fistule using transanal endocsopic microsurgery]. / První prípad resení rektovaginální pístele pomocí transanální endoskopické mikrochirurgie.

The authors present an unusual and, according to the available literature data, so far unused method--management of the rectovaginal fistule, using a T.E.M. technique (transanal endoscopic microsurgery). In their case-review of a female patient, they present advantages of this technique in a case of a rare disorder - a benign rectovaginal fistule. All of the following employment of a harmonic scalpel in the T.E.M. method, as well as of a tissue adhesive Tissucol and of a surgical rectoscope in the vaginal phase of the procedure, deserve attention of surgeons and gynaecologists.

Selected hormones levels in individuals with endothelial dysfunction and insulin resistance.

AIM: To determine possible differences in selected serum hormones levels related to endothelial function and insulin sensitivity. METHODS: Ghrelin, insulin, serotonin, growth hormone, IGF-1, leptin and adiponectin serum levels were determined in a group of 83 adults (40 women, 43 men) with a mean age 49.4+/-4.6 years. Total ghrelin, insulin and serotonin levels were measured using RIA, growth hormone and leptin using IRMA and human adiponectin was measured using ELISA. Results were associated with BMI, calculated as kg/ m2, endothelial function, determined by ultrasound measured flow mediated vasodilatation of brachial artery, and with insulin resistance, calculated by IR HOMA index. RESULTS: We found no difference in age comparing subjects with (ED+) and without (ED-) endothelial dysfunction, neither comparing subject with (IR+) and without (IR-) insulin resistance. In individuals ED+ and IR+ a higher BMI, serum leptin and insulin levels and lower ghrelin, growth hormone and adiponectin levels were found. Subject with ED presented with a higher serum serotonin level compared to subjects without ED. This difference was not found in individuals with and without IR. CONCLUSION: Lower ghrelin, growth hormone and adiponectin levels along with higher insulin and leptin levels may contribute to the progression of endothelial dysfunction and insulin resistance.

Disposition of digitoxin in renal failure.

The disposition of digitoxin was studied for a period of 8 days in 6 uremic patients given a single oral dose of 1 mg 3H-digitoxin. In plasma, the time-course of radioactivity indicated a diminished absorption velocity of tritium compared to that of control subjects already reported and, after reaching of a pseudostate-equilibrium at 24 hr, an exponential decline with a mean half-life of 8.0 days. In urine, smaller amounts of tritiated compounds were eliminated in uremic patients (8.7% of the dose) than in controls (22.5%). The average fecal excretion of digitoxin and its metabolites was not significantly increased. Chloroform extraction and thin-layer chromatography in plasma, urine and feces suggested no qualitative alteration in the metabolism of digitoxin. Calculations of the total body tritium content (body stores) after each 24-hr interval and its pharmacokinetic behavior showed that the elimination of digitoxin is determined by the transfer constant from tissue to plasma. The differences in elimination kinetics of digitoxin and its metabolites of uremic patients and healthy subjects were not significant.