The increase in the resistivity with decreasing temperature followed by a drop by more than one order of magnitude is observed on the metallic side near the zero-magnetic-field metal-insulator ...transition in a strongly interacting two-dimensional electron system in ultra-clean SiGe/Si/SiGe quantum wells. We find that the temperature Formula: see text, at which the resistivity exhibits a maximum, is close to the renormalized Fermi temperature. However, rather than increasing along with the Fermi temperature, the value Formula: see text decreases appreciably for spinless electrons in spin-polarizing (parallel) magnetic fields. The observed behaviour of Formula: see text cannot be described by existing theories. The results indicate the spin-related origin of the effect.
Intravenous thrombolysis is a standard of care treatment for patients with acute ischemic stroke. Tissue plasminogen activator (tPA) has been the main thrombolytic agent used since the publication of ...the seminal National Institutes of Neurological Disorders and Stroke trial in 1995. There is now mounting evidence to support the routine use of Tenecteplase (TNK) to treat acute ischemic stroke. TNK is a genetically modified tPA with higher fibrin specificity, longer half‐life, and reduced systemic coagulopathy. In this illustrated review, we compare the indications, doses, mechanisms of action, efficacy and safety of TNK and tPA. We provide an overview of published clinical trials studying TNK in acute ischemic stroke, including dose‐escalation studies and head‐to‐head comparisons with tPA. Finally, we summarize current acute stroke guideline recommendations and suggest treatment algorithms to manage the two main complications of intravenous thrombolysis: symptomatic intracerebral hemorrhage and angioedema.
The metal-insulator transition (MIT) is an exceptional test bed for studying strong electron correlations in two dimensions in the presence of disorder. In the present study, it is found that in ...contrast to previous experiments on lower mobility samples, in ultrahigh mobility SiGe/Si/SiGe quantum wells the critical electron density nc of the MIT becomes smaller than the density nm, where the effective mass at the Fermi level tends to diverge. Near the topological phase transition expected at nm, the metallic temperature dependence of the resistance should be strengthened, which is consistent with the experimental observation of more than an order of magnitude resistance drop with decreasing temperature below ~1 K.
We have studied the strongly interacting, two-valley two-dimensional (2D) electron system in ultrahigh mobility SiGe/Si/SiGe quantum wells in parallel magnetic fields strong enough to completely ...polarize the electron spins thus making the electron system "spinless." It occurs that the metallic temperature dependence of the resistivity, although weaker than that in the absence of magnetic field, still remains strong even when the spin degree of freedom is removed. Several independent methods have been used to establish the existence of the genuine MIT in the spinless two-valley 2D system. This is in contrast to the previous results obtained on more disordered silicon samples, where the polarizing magnetic field causes a complete quench of the metallic temperature behavior.
We observe that in a strongly interacting two-dimensional electron system in ultraclean SiGe/Si/SiGe quantum wells, the resistivity on the metallic side near the metal-insulator transition increases ...with decreasing temperature, reaches a maximum at some temperature, and then decreases by more than one order of magnitude. We scale the resistivity data in line with expectations for the transport of strongly correlated Fermi systems and find a nearly perfect agreement with theory over a wide range of electron densities.
Eukaryotic transcriptional activators function, at least in part, by promoting assembly of the preinitiation complex, which comprises RNA polymerase II and its general transcription factors (GTFs). ...Activator-mediated stimulation of the assembly of the preinitiation complex has been studied in vitro but has been relatively refractory to in vivo analysis. Here we use a DNA-crosslinking/immunoprecipitation assay to study in living cells the first step in the assembly of the preinitiation complex, the interaction between the TATA-box-binding protein (TBP) and its binding site, the TATA box. Analysis of a variety of endogenous yeast genes, and of a series of activators of differing strength, reveals a general correlation between TBP binding and transcriptional activity. Using mutant yeast strains, we show that Mot1 prevents the binding of TBP to inactive promoters and that activator-mediated stimulation of TBP binding requires additional GTFs, including TFIIB and Srb4. Taken together, our results indicate that TBP binding in vivo is stringently controlled, and that the ability of activators to stimulate this step in the assembly of the preinitiation complex is a highly cooperative process involving multiple transcription factors.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The clinical impact of blood pressure (BP) and of antihypertensive therapy (AHT) in acute ischemic stroke remains uncertain.
We reviewed the charts of patients admitted to the Montreal General ...Hospital between April 1, 2002 and October 15, 2005. Ischemic stroke was considered severe if the Canadian Neurological Scale at presentation was < or =7. Poor outcome at 10 days after onset was defined as a modified Rankin Scale >3. Acute change in BP was defined as the percent difference between the mean 24-hour mean arterial pressure (MAP) and the baseline MAP. AHT was considered present if administered > or =5 days during the first week after stroke onset. The association between predictors and outcome was assessed using unconditional multivariable logistic regression. Covariates used included age, stroke severity, diabetes mellitus, coronary artery disease, atrial fibrillation, premorbid hypertension and hyperlipidemia.
Three hundred and sixty-four patients were included. Compared to patients with intermediate baseline BP, those with a MAP >130 mm Hg OR = 2.47 (95% CI, 1.04-5.85) or a MAP <90 mm Hg OR = 2.94 (95% CI, 1.28-6.77) were found to have an increased risk of poor outcome after covariate adjustment. A 15% increase in MAP was associated with an increased risk of poor outcome OR = 5.34 (95% CI, 1.18-24.3) while AHT in the first week after stroke onset was found to result in a decreased risk OR = 0.39 (95% CI, 0.17-0.90). However, neither of these findings remained significant after adjustment for the described covariates.
Both high and low MAP at presentation are associated with worse short-term outcome after ischemic stroke.
The effect of pre-stroke use of antihypertensives, antiplatelets, and statins on initial severity and early outcome of ischemic stroke is uncertain.
We performed a retrospective chart review of 553 ...consecutive acute ischemic stroke patients presenting to the Montreal General Hospital between April 1st 2002 and October 15th 2005. We defined a severe stroke as a Canadian Neurological Scale score of < or =7 and a poor early outcome as a modified Rankin Scale score of >3 at 10 days post-stroke.
In total, 339 patients were included. Superior early functional outcome was associated with the premorbid use of statins (OR = 0.50, 95% CI: 0.25-1.00) and the combination of all 3 medications (OR = 0.37, 95% CI: 0.16-0.87). Angiotensin-II-decreasing agents were associated with an increased risk of severe strokes (OR = 2.13, 95% CI: 1.00-4.52).
Pre-stroke use of statins and the combination of antihypertensives, antiplatelets, and statins were both associated with a favorable functional outcome at 10 days post-stroke. Angiotensin-II-decreasing agents were associated with increased initial stroke severity.
The increase in the resistivity with decreasing temperature followed by a drop by more than one order of magnitude is observed on the metallic side near the zero-magnetic-field metal-insulator ...transition in a strongly interacting two-dimensional electron system in ultra-clean SiGe/Si/SiGe quantum wells. We find that the temperature \(T_{\text{max}}\), at which the resistivity exhibits a maximum, is close to the renormalized Fermi temperature. However, rather than increasing along with the Fermi temperature, the value \(T_{\text{max}}\) decreases appreciably for spinless electrons in spin-polarizing (parallel) magnetic fields. The observed behaviour of \(T_{\text{max}}\) cannot be described by existing theories. The results indicate the spin-related origin of the effect.
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