Early recurrent ischemic stroke complicating intravenous thrombolysis for stroke: incidence and association with atrial fibrillation

<p><b>Background and Purpose:</b> Mechanisms of early neurologic deterioration after treatment with intravenous, recombinant, tissue-type plasminogen activator (IV rt-PA) include symptomatic intracerebral hemorrhage (SICH) and early recurrent ischemic stroke. We observed a number of cases of acute deterioration due to recurrent ischemic events.</p> <p><b>Methods:</b> We undertook a single-center, retrospective analysis of consecutive acute stroke patients treated with IV rt-PA between January 2006 and December 2008 to define the incidence of early neurologic deterioration (>= 4-point drop on the National Institutes of Health Stroke Scale within 72 hours) and its mechanism. Deterioration was attributed to SICH when associated with a PH1 or PH2 hemorrhage on postdeterioration computed tomography scans, to recurrent ischemic stroke when there was clinical and radiologic evidence of a new territorial infarction or new vessel occlusion, and otherwise to evolution of the incident stroke.</p> <p><b>Results:</b> Of 228 consecutive IV rt-PA-treated patients, 34 (15%) developed early neurologic deterioration, 18 (8%) secondary to incident strokes 10 (4.4%) due to SICH, and 6 (2.6%) due to early recurrent ischemic events, which were significantly associated with atrial fibrillation (present in 5 of 6 patients; 4 paroxysmal, 1 permanent). In 4 patients, sudden clinical deterioration developed during or shortly after IV rt-PA infusion, and in 2, deterioration developed 3 days later. All died 2 days to 2 weeks later. The single case without atrial fibrillation had a recurrent, contralateral, middle cerebral artery stroke during IV rt-PA infusion and multiple high-signal emboli detected by transcranial Doppler. Early recurrent ischemic stroke accounted for 5 of 12 (42%) cases of early neurologic deterioration in patients with atrial fibrillation.</p> <p><b>Conclusion:</b> In this single-center series, the incidence of early recurrent ischemic stroke after IV rt-PA was 2.6% and was associated with previous atrial fibrillation.</p&gt

Antiferromagnetic transitions in `T-like' BiFeO3

Recent studies have reported the existence of an epitaxially-stabilized tetragonal-like ('T-like') monoclinic phase in BiFeO3 thin-films with high levels of compressive strain. While their structural and ferroelectric properties are different than those of rhombohedral-like ('R-like') films with lower levels of strain, little information exists on magnetic properties. Here, we report a detailed neutron scattering study of a nearly phase-pure film of T-like BiFeO3. By tracking the temperature dependence and relative intensity of several superstructure peaks in the reciprocal lattice cell, we confirm antiferromagnetism with largely G-type character and TN = 324 K, significantly below a structural phase transition at 375 K, contrary to previous reports. Evidence for a second transition, possibly a minority magnetic phase with C-type character is also reported with TN = 260 K. The co-existence of the two magnetic phases in T-like BiFeO3 and the difference in ordering temperatures between R-like and T-like systems is explained through simple Fe-O-Fe bond distance considerations.Comment: 9 pages, 7 figures. Slight modifications to introductory text and presentation of data. Supplementary Material section adde

Static and Dynamic Magnetism in Underdoped Superconductor BaFe1.92_{1.92}Co0.08_{0.08}As2_2

We report neutron scattering measurements on single crystals of BaFe$_{1.92}$Co$_{0.08}$As$_2$. The magnetic Bragg peak intensity is reduced by 6 % upon cooling through T$_C$. The spin dynamics exhibit a gap of 8 meV with anisotropic three-dimensional (3d) interactions. Below T$_C$ additional intensity appears at an energy of $\sim$4.5(0.5) meV similar to previous observations of a spin resonance in other Fe-based superconductors. No further gapping of the spin excitations is observed below T$_C$ for energies down to 2 meV. These observations suggest the redistribution of spectral weight from the magnetic Bragg position to a spin resonance demonstrating the direct competition between static magnetic order and superconductivity.Comment: 4 pages, 4 figure

Service-level variation, patient-level factors, and treatment outcome in those seen by child mental health services

Service comparison is a policy priority but is not without controversy. This paper aims to investigate the amount of service-level variation in outcomes in child mental health, whether it differed when examining outcomes unadjusted vs. adjusted for expected change over time, and which patient-level characteristics were associated with the difference observed between services. Multilevel regressions were used on N = 3256 young people (53% male, mean age 11.33 years) from 13 child mental health services. Outcome was measured using the parent-reported Strengths and Difficulties Questionnaire. The results showed there was 4-5% service-level variation in outcomes. Findings were broadly consistent across unadjusted vs. adjusted outcomes. Young people with autism or infrequent case characteristics (e.g., substance misuse) had greater risk of poor outcomes. Comparison of services with high proportions of young people with autism or infrequent case characteristics requiring specialist input needs particular caution as these young people may be at greater risk of poor outcomes

Muon Spin Relaxation Studies of Magnetic-Field-Induced Effects in High-TcT_{c} Superconductors

Muon spin relaxation ($\mu$SR) measurements in high transverse magnetic fields ($\parallel \hat c$) revealed strong field-induced quasi-static magnetism in the underdoped and Eu doped (La,Sr)$_{2}$CuO$_{4}$ and La$_{1.875}$Ba$_{0.125}$CuO$_{4}$, existing well above $T_{c}$ and $T_{N}$. The susceptibility-counterpart of Cu spin polarization, derived from the muon spin relaxation rate, exhibits a divergent behavior towards $T \sim 25$ K. No field-induced magnetism was detected in overdoped La$_{1.81}$Sr$_{0.19}$CuO$_{4}$, optimally doped Bi2212, and Zn-doped YBa$_{2}$Cu$_{3}$O$_{7}$.Comment: 4 pages, 4 color figure

Ionospheric response to the corotating interaction region-driven geomagnetic storm of October 2002

Unlike the geomagnetic storms produced by coronal mass ejections (CMEs), the storms generated by corotating interaction regions (CIRs) are not manifested by dramatic enhancements of the ring current. The CIR-driven storms are however capable of producing other phenomena typical for the magnetic storms such as relativistic particle acceleration, enhanced magnetospheric convection and ionospheric heating. This paper examines ionospheric plasma anomalies produced by a CIR-driven storm in the middle- and high-latitude ionosphere with a specific focus on the polar cap region. The moderate magnetic storm which took place on 14–17 October 2002 has been used as an example of the CIR-driven event. Four-dimensional tomographic reconstructions of the ionospheric plasma density using measurements of the total electron content along ray paths of GPS signals allow us to reveal the large-scale structure of storm-induced ionospheric anomalies. The tomographic reconstructions are compared with the data obtained by digital ionosonde located at Eureka station near the geomagnetic north pole. The morphology and dynamics of the observed ionospheric anomalies is compared qualitatively to the ionospheric anomalies produced by major CME-driven storms. It is demonstrated that the CIR-driven storm of October 2002 was able to produce ionospheric anomalies comparable to those produced by CME-driven storms of much greater Dst magnitude. This study represents an important step in linking the tomographic GPS reconstructions with the data from ground-based network of digital ionosondes