At least 240 000 individuals experience a transient ischemic attack each year in the United States. Transient ischemic attack is a strong predictor of subsequent stroke. The 90-day stroke risk after ...transient ischemic attack can be as high as 17.8%, with almost half occurring within 2 days of the index event. Diagnosing transient ischemic attack can also be challenging given the transitory nature of symptoms, often reassuring neurological examination at the time of evaluation, and lack of confirmatory testing. Limited resources, such as imaging availability and access to specialists, can further exacerbate this challenge. This scientific statement focuses on the correct clinical diagnosis, risk assessment, and management decisions of patients with suspected transient ischemic attack. Identification of high-risk patients can be achieved through use of comprehensive protocols incorporating acute phase imaging of both the brain and cerebral vasculature, thoughtful use of risk stratification scales, and ancillary testing with the ultimate goal of determining who can be safely discharged home from the emergency department versus admitted to the hospital. We discuss various methods for rapid yet comprehensive evaluations, keeping resource-limited sites in mind. In addition, we discuss strategies for secondary prevention of future cerebrovascular events using maximal medical therapy and patient education.
In this article, a novel current controllable active transient-voltage-compensation circuit (CC-ATVCC) is proposed to mitigate output voltage overshoot and undershoot in voltage regulator module ...(VRM) during load transients. The current difference between the VRM output and the load is compensated by field effect transistors in the proposed CC-ATVCC so that the output voltage spikes are suppressed. In the proposed CC-ATVCC, a high gain analog drive circuit, consisting of an operational amplifier cascaded with a common-source amplification circuit, provides adjustable drive voltage, which flexibly changes the compensation current. Furthermore, a time-domain model is developed in this article to analyze the interaction between VRM and the proposed CC-ATVCC, guiding the circuit design under universal conditions. Finally, the proposed CC-ATVCC has been built and tested in a 12-phase 500 A interleaved buck converter. The results show that the overshoot of the output voltage can be reduced by 34% using the proposed CC-ATVCC and the footprint of CC-ATVCC is only 10% compared with the traditional capacitor-only solution. The proposed CC-ATVCC can reduce the number of output capacitors and greatly increase the power density of VRM.
Due to various controls in voltage-source converters, their impacts and mutual influences on transient stability of new-generation power systems are still obscure. Different from the mature ...different-order transient equations for synchronous generator (SG), fully accepted transient equations of converters still lack. In this article, a novel methodology is proposed to uniformly evaluate the controller effects on the transient stability and then establish the hierarchical transient equations of converters based on the properties of controlling-unstable-equilibrium point (CUEP). The participation factors on unstable eigenvalue of CUEP are applied to measure the contribution of state variables in transient dynamics, and dominant variables and key loops of grid-following and grid-forming converters are determined and compared. It is found that the synchronous loop, e.g., phase-locked loop in grid-following converters and virtual-synchronous loop in grid-forming converters, plays a primary role, and the power balance loop on the DC capacitor, including DC-voltage control and DC capacitor dynamics, plays a secondary role. Additionally, the impacts of synchronization and power balance are compared with the rotor swing of the SG. Analytical results are demonstrated by time-domain simulations and transient stability assessments. The dominant transient models and the CUEP-based participation factor analysis provide an improved physical insight on our understanding of transient dynamics in the new-generation power systems dominated by not only grid-following but also grid-forming converters.
In the SPARCL (Stroke Prevention by Aggressive Reduction in Cholesterol Levels) trial, atorvastatin was compared with placebo in 4,731 participants with recent stroke or transient ischemic attack and ...no known coronary heart disease. Atorvastatin reduced the first occurrence of stroke and the first occurrence of a composite of vascular events.
The aim of this post hoc analysis was to assess the occurrence of all (first and subsequent) vascular events and the effect of atorvastatin to reduce these events by vascular territory (cerebrovascular, coronary, or peripheral) in SPARCL.
Treatment effects on total adjudicated vascular events, overall and by vascular territory, were summarized by marginal proportional hazards models. Vascular event rates were estimated for each treatment group with cumulative incidence functions.
The placebo group had an estimated 41.2 first and 62.7 total vascular events per 100 participants over 6 years. There were 164 fewer first and 390 fewer total vascular events in the atorvastatin group (total events hazard ratio: 0.68; 95% confidence interval: 0.60 to 0.77). The total events reduction included 177 fewer cerebrovascular, 170 fewer coronary, and 43 fewer peripheral events. Over 6 years, an estimated 20 vascular events per 100 participants were avoided with atorvastatin treatment.
In participants with recent stroke or transient ischemic attack, the total number of vascular events prevented with atorvastatin was more than twice the number of first events prevented. Total event reduction provides a comprehensive metric to capture the totality of atorvastatin clinical efficacy in reducing disease burden after stroke or transient ischemic attack. (Lipitor in the Prevention of Stroke, for Patients Who Have Had a Previous Stroke SPARCL; NCT00147602).
This article presents an area-efficient and fast-transient capless low-dropout regulator (LDO) with satisfactory static and dynamic performance in the full load current range. Active-capacitor ...frequency compensation strategy with push-pull charging ability is employed to reduce on-chip compensation cap without degrading loop stability at light load and improve transient response speed simultaneously. Moreover, in order to drive this compensation capacitance, it makes use of an adaptively biased signal- and transient-current boosting error amplifier as well as transient enhancement circuit with nonlinear control to achieve high loop gain/bandwidth and slew rate. The proposed LDO is implemented in a 0.35-μm 5V-CMOS process and occupies an active chip area of 0.077 mm 2 . Experimental results demonstrate that it can deliver 100-mA load current at 200-mV dropout voltage ( V IN = 2.7-3.3 V, C load ≤100 pF). It consumes 66- μ A quiescent current at light load and can recover within 0.7 μ s for load transient. The voltage spikes at the output, undergoing a maximum load current change, are controlled well below 260 mV and good line/load regulation is achieved synchronously.
The short-term incidence of ischemic stroke after a transient ischemic attack (TIA) is high. However, data on the long-term incidence are not well known but are needed to guide preventive strategies.
...Patients with first-time TIA (index date) in the Danish Stroke Registry (January 2014-December 2020) were included and matched 1:4 with individuals from the background population and 1:1 with patients with a first-time ischemic stroke on the basis of age, sex, and calendar year. The incidences of ischemic stroke and mortality from index date were estimated by Aalen-Johansen and Kaplan-Meier estimators, respectively, and compared between groups using multivariable Cox regression.
We included 21 500 patients with TIA, 86 000 patients from the background population, and 21 500 patients with ischemic stroke (median age, 70.8 years 25th-75th percentile, 60.8-78.7; 53.1% males). Patients with TIA had more comorbidities than the background population, yet less than the control stroke population. The 5-year incidence of ischemic stroke after TIA (6.1% 95% CI, 5.7-6.5) was higher than the background population (1.5% 95% CI, 1.4-1.6,
<0.01; hazard ratio, 5.14 95% CI, 4.65-5.69) but lower than the control stroke population (8.9% 95% CI, 8.4-9.4,
<0.01; hazard ratio, 0.58 95% CI, 0.53-0.64). The 5-year mortality for patients with TIA (18.6% 95% CI, 17.9-19.3) was higher than the background population (14.8% 95% CI, 14.5-15.1,
<0.01; hazard ratio, 1.26 95% CI, 1.20-1.32) but lower than the control stroke population (30.1% 95% CI, 29.3-30.9,
<0.01; hazard ratio, 0.41 95% CI, 0.39-0.44).
Patients with first-time TIA had an ischemic stroke incidence of 6.1% during the 5-year follow-up period. After adjustment for relevant comorbidities, this incidence was approximately 5-fold higher than what was found for controls in the background population and 40% lower than for patients with recurrent ischemic stroke.
Atopic dermatitis (AD) is a multifaceted, chronic relapsing inflammatory skin disease that affects people of all ages. It is characterized by chronic eczema, constant pruritus, and severe discomfort. ...AD often progresses from mild annoyance to intractable pruritic inflammatory lesions associated with exacerbated skin sensitivity. The T helper-2 (Th2) response is mainly linked to the acute and subacute phase, whereas Th1 response has been associated in addition with the chronic phase. IL-17, IL-22, TSLP, and IL-31 also play a role in AD. Transient receptor potential (TRP) cation channels play a significant role in neuroinflammation, itch and pain, indicating neuroimmune circuits in AD. However, the Th2-driven cutaneous sensitization of TRP channels is underappreciated. Emerging findings suggest that critical Th2-related cytokines cause potentiation of TRP channels, thereby exaggerating inflammation and itch sensation. Evidence involves the following: (i) IL-13 enhances TRPV1 and TRPA1 transcription levels; (ii) IL-31 sensitizes TRPV1
transcriptional and channel modulation, and indirectly modulates TRPV3 in keratinocytes; (iii) The Th2-cytokine TSLP increases TRPA1 synthesis in sensory neurons. These changes could be further enhanced by other Th2 cytokines, including IL-4, IL-25, and IL-33, which are inducers for IL-13, IL-31, or TSLP in skin. Taken together, this review highlights that Th2 cytokines potentiate TRP channels through diverse mechanisms under different inflammatory and pruritic conditions, and link this effect to distinct signaling cascades in AD. This review strengthens the notion that interrupting Th2-driven modulation of TRP channels will inhibit transition from acute to chronic AD, thereby aiding the development of effective therapeutics and treatment optimization.
Differing from synchronous generators, there are lack of physical laws governing the synchronization dynamics of voltage-source converters (VSCs). The widely used phase-locked loop (PLL) plays a ...critical role in maintaining the synchronism of current-controlled VSCs, whose dynamics are highly affected by the power exchange between VSCs and the grid. This article presents a design-oriented analysis on the transient stability of PLL-synchronized VSCs, i.e., the synchronization stability of VSCs under large disturbances, by employing the phase portrait approach. Insights into the stabilizing effects of the first- and second-order PLLs are provided with the quantitative analysis. It is revealed that simply increasing the damping ratio of the second-order PLL may fail to stabilize VSCs during severe grid faults, whereas the first-order PLL can always guarantee the transient stability of VSCs when equilibrium operation points exist. An adaptive PLL that switches between the second-order and the first-order PLL during the fault-occurring/-clearing transient is proposed for preserving both the transient stability and the phase-tracking accuracy. Time-domain simulations and experimental tests, considering both the grid fault and the fault recovery, are performed, and the obtained results validate the theoretical findings.
By definition, the symptoms of a transient ischemic attack (TIA) subside completely within 24 hours. Imaging studies show signs of persistent ischemic tissue damage in a substantial amount of ...patients with TIA. Cerebral infarction can cause permanent cognitive impairment. Whether permanent cognitive impairment occurs after TIA is unclear, as is its profile.
Patients with TIA aged 45 to 65 years without prior stroke or dementia underwent comprehensive neuropsychological testing within 3 months. Z scores per cognitive domain were obtained, based on the mean of a control group within the same age range. Cognitive impairment was defined as a domain z score <-1.65. Patients underwent either computed tomography or MRI brain imaging.
One hundred seven patients with TIA (63% women, mean age, 56.6 years) were included and compared with 81 controls (56% women, mean age, 52.9 years). Patients performed worse on all cognitive domains except episodic memory. Working memory (25%), attention (22%), and information processing speed (16%) were most frequently impaired and more often than in the control group (age- and sex-adjusted odds ratios, respectively, 22.5 95% confidence interval, 2.9-174.3, 6.8 1.9-24.3, 7.1 1.5-32.5). More than 35% of patients with TIA had impairment of ≥1 cognitive domain. Presence of silent brain infarcts was related to worse executive functioning but did not explain the whole relationship between TIA and cognitive impairment.
More than a third of patients with TIA have impairment of ≥1 cognitive domain within 3 months after their TIA. The affected domains fit in the vascular cognitive impairment profile.
We previously observed a high frequency of psychopathological features in transient global amnesia (TGA). We aimed at assessing differences in risk factor profile and prognosis between TGA and ...transient ischemic attack (TIA) patients with a focus on aspects with possible psychopathological relevance. We studied 51 TGA patients (mean age ± SD, 62.7 ± 6.7 years; M/F = 24/27) and 51 control patients with TIA (mean age ± SD, 63.8 ± 6.7 years; M/F = 41/10) and followed them up for about 7 years. Compared with TIA controls, TGA patients more frequently had a history of psychiatric diseases (age and sex‐corrected OR = 2.86, 95% CI: 1.01–8.05) and alcohol use (OR = 3.26, 95% CI: 1.10–9.66) and less frequently a history of cardiac (OR = 0.29, 95% CI: 0.11–0.76) or peripheral artery disease (OR = 0.11, 95% CI: 0.01–0.96). A family history of psychiatric diseases was reported more frequently by TGA than TIA patients (OR = 2.99, 95% CI: 1.04–8.59). On follow‐up, in comparison with TIA patients, TGA patients had a significantly lower risk of combined stroke, myocardial infarct, and death (log‐rank test, P = 0.0059). In the multivariate analysis, the dissimilar baseline risk factor profile explained most of the difference in prognosis between the two groups. In comparison with TIA patients, patients with TGA have more frequently a personal or family history of psychiatric diseases and a more favorable vascular risk factor profile and prognosis. These results have therapeutic implications and reinforce the hypothesis that TGA is a benign disorder.
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