Theoretical analysis of the elastic Kelvin-Helmholtz instability in explosive weldings

By considering the joint effects of the Kelvin-Helmholtz(KH) and Rayleigh-Taylor(RT) instabilities, this paper presents an interpretation of the wavy patterns that occur in explosive welding. It is assumed that the elasticity of the material at the interface effectively determines the wavelength, because explosive welding is basically a solid-state welding process. To this end, an analytical model of elastic hydrodynamic instabilities is proposed, and the most unstable mode is selected in the solid phase. Similar approaches have been widely used to study the interfacial behavior of solid metals in high-energy-density physics. By comparing the experimental and theoretical results, it is concluded that thermal softening,which significantly reduces the shear modulus, is necessary and sufficient for successful welding. The thermal softening is verified by theoretical analysis of the increase in temperature due to the impacting and sliding of the flyer and base plates, and some experimental observations are qualitatively validated.In summary, the combined effect of the KH and RT instabilities in solids determines the wavy morphology, and our theoretical results are in good qualitative agreement with experimental and numerical observations.

Clinical Types and Outcome of Minor Ischemic Stroke in Northern China: A Retrospective Cohort Study

Background: As a common and high incidence of disease, the minor ischemic stroke (MIS) has become an important public health problem. The aim of this study was to address whether patients with MIS have different types and outcome in the elderly in northern China. Methods: A retrospective cohort of consecutive patients was selected for study;all registered neurologic outpatients of the tertiary teaching hospital in northern Jiangsu, China between February, 2011 and February, 2012. A total of 433 outpatients, clinically only having had an initial visit and a MRI study of the brain, were enrolled. Results: Of 433 outpatients, 247 (57.0%) patients with MIS were diagnosed. The clinical types of MIS included stable MIS in 58.3%, acute progressive MIS in 5.3%, and chronic progressive MIS in 36.4% of patients. After adjusted Odd ratio (OR), only aged (OR, 1.0;95% confidence interval [CI], 1.007 - 1.087, p = 0.021), episode duration (OR, 1.8;95% CI, 1.011 - 1.024, p = 0.001), initial number of MIS (OR, 1.1;95% CI, 1.047 - 1.207, p = 0.001), and infarcts volume (OR, 1.8;95% CI, 1.253 - 2.681, p = 0.002) were independently associated with stable MIS and progressive MIS. Total survival was favorable among groups (p = 0.094), but the followed mRS score was significantly higher among those progressive MIS than those stable MIS (2.3 ± 1.0 vs 0.1 ± 0.3, p Conclusion: MIS had a very high prevalence and different clinical types. Stable MIS is a benign stroke, whereas those progressive MIS may have long-term instability or acute and chronic progressive trend. This information is important in prospectively determining outcome of MIS and in patient treatment.

Hemichorea in nonketotic hyperglycemia: Putamenal and cerebellum lesion on MR imaging

Hemichorea with corresponding putamenal T1 hyper-intensity and T2 hypointensity on MR imaging has occasionally been reported in diabetes mellitus with nonketotic hyperglycemia. However, the signal intensity in pu-tamenal and cerebellum lesion on MR imaging, which is believed to be pathogenetically related to hemichorea, is rarely documented in diabetes mellitus with nonketotic hyperglycemia. We describe a 57-year-old man with nonketotic hyperglycemic hemichorea on his right arm and legs, whose signal intensity in putamenal and cerebellum lesion was demonstrated by MR imaging.

Rare Huge Congenital Intracranial Silent Teratoma in Older People: A Case Report

The huge?congenital?intracranial teratoma is very rare. We report a case of a 77 years old male with giant congenital brain teratoma without clinical symptoms. His computed tomography (CT) scan showed a massive tumor (6 × 5 × 6 cm) of irregular high density (inside with some point flaky low density) in left temporal lobe region, the lower corner of the left ventricle downward shift, and enhanced CT scan no enhancement. Magnetic resonance imaging (MRI) on brain showed an irregular huge tumor in the left temporal lobe area, with multiple nodular or lobulated mixd high and low or equal signal changes, in which the liquid signal based. The midline was shift to the right, and the posterior horn of the left ventricle was compressed and downward shift, expansion, and hydrocephalus. After follow-up 12 months, the patient presents a normal daily life and work and no neurological signs as usual. Our observations show that the huge tumor in brain with multiple nodular or lobulated variety of mixed signal changes on MRI without symptoms is a congenital intracranial silent teratoma.

Acute headache in general neurology of China: Cause changes and predictors of short-term outcome

Background: Although patients with acute headache frequently present in emergency department, the causes and predictors of short-term outcome in patients with acute headache in general neurology have not been adequately investigated. Methods: We prospectively reviewed the medical records of 130 hospitalized acute headache pa-tients in general neurology of China. Their initial CT scan was assessed, as was their lumbar puncture (LP) examination if performed. Results: The main cause of acute headache was acute secondary headache (80.8%), which was mainly attributable to acute cerebrovascular events (72.4%) followed by intracranial infection (19.0%). Among the 10.8% of patients who died during hospitalization most (85.7%) had subarachnoid hemorrhage (SAH). Significant predictors of survival were severe headache versus thunderclap headache, meningismus, de-layed loss of consciousness, and hypertension (all p < 0.05). Multiple logistic regression analyses showed significant differences in severe headache or thunderclap headache (OR, 0.255;95%CI, 0.066 - 0.990;p = 0.048) and delayed loss of consciousness (OR, 0.060;95%CI, 0.016 - 0.224, p = 0.000) between patients who died and those who survived. Conclusions: The main underlying cause of hospitalized acute headache was acute cerebrovascular events. Severe headache and delayed loss of consciousness are predictors for poor outcome of acute headache.