Abstract
Picosecond strain pulses are a versatile tool for investigation of mechanical properties of meso- and nano-scale objects with high temporal and spatial resolutions. Generation of such pulses ...is traditionally realized via ultrafast laser excitation of a light-to-strain transducer involving thermoelastic, deformation potential, or inverse piezoelectric effects. These approaches unavoidably lead to heat dissipation and a temperature rise, which can modify delicate specimens, like biological tissues, and ultimately destroy the transducer itself limiting the amplitude of generated picosecond strain. Here we propose a non-thermal mechanism for generating picosecond strain pulses via ultrafast photo-induced first-order phase transitions (PIPTs). We perform experiments on vanadium dioxide VO
2
films, which exhibit a first-order PIPT accompanied by a lattice change. We demonstrate that during femtosecond optical excitation of VO
2
the PIPT alone contributes to ultrafast expansion of this material as large as 0.45%, which is not accompanied by heat dissipation, and, for excitation density of 8 mJ cm
−2
, exceeds the contribution from thermoelastic effect by a factor of five.
The interplay between the strong intralayer covalent‐ionic bonds and the weak interlayer van der Waals (vdW) forces between the neighboring layers of vdW crystals gives rise to unique physical and ...chemical properties. Here, the intralayer and interlayer bondings in α and β polytypes of In2Se3 are studied, a vdW material with potential applications in advanced electronic and optical devices. Picosecond ultrasonic experiments are conducted to probe the sound velocity in the direction perpendicular to the vdW layers. The measured sound velocities are different in α‐ and β‐In2Se3, suggesting a significant difference in their elastic properties. Density functional theory and an effective spring model are used to calculate the elastic stiffness of the layer and vdW gap in α‐ and β‐In2Se3. The calculated elastic moduli show good agreement with experimental values and reveal the dominant contribution of interlayer atomic bonding to the different elastic properties of the two polytypes. The findings show the power of picosecond ultrasonics for probing the fundamental elastic properties of vdW materials. The data and analysis also provide a reliable description of the intra‐ and interlayer forces in complex crystal structures, such as the polytype phases of In2Se3.
The atomic bonding in the van der Waals crystal In2Se3 is studied using picosecond ultrasonics and density functional theory. A significant difference in the sound velocities in the direction perpendicular to the van der Waals layers of α‐ and β‐In2Se3 is revealed and assigned to the different elastic properties of the two polytypes.
Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used medications that can potentially increase the risk of bleeding and thrombosis.
This study quantified the effect of NSAIDs in the RE-LY ...(Randomized Evaluation of Long Term Anticoagulant Therapy) trial.
This was a post hoc analysis of NSAIDs in the RE-LY study, which compared dabigatran etexilate (DE) 150 and 110 mg twice daily (b.i.d.) with warfarin in patients with atrial fibrillation. Treatment-independent, multivariate-adjusted Cox regression analysis assessed clinical outcomes by comparing NSAID use with no NSAID use. Interaction analysis was obtained from treatment-dependent Cox regression modeling. Time-varying covariate analysis for NSAID use was applied to the Cox model.
Among 18,113 patients in the RE-LY study, 2,279 patients used NSAIDs at least once during the trial. Major bleeding was significantly elevated with NSAID use (hazard ratio HR: 1.68; 95% confidence interval CI: 1.40 to 2.02; p < 0.0001). NSAID use did not significantly alter the risk of major bleeding for DE 150 or 110 mg b.i.d. relative to warfarin (pinteraction = 0.63 and 0.93, respectively). Gastrointestinal major bleeding was significantly elevated with NSAID use (HR: 1.81; 95% CI: 1.35 to 2.43; p < 0.0001). The rate of stroke or systemic embolism (stroke/SE) with NSAID use was significantly elevated (HR: 1.50; 95% CI: 1.12 to 2.01; p = 0.007). The use of NSAIDs did not significantly alter the relative efficacy on stroke/SE for DE 150 or 110 mg b.i.d. relative to warfarin (pinteraction = 0.59 and 0.54, respectively). Myocardial infarction rates were similar with NSAID use compared with no NSAID use (HR: 1.22; 95% CI: 0.77 to 1.93; p = 0.40). Patients were more frequently hospitalized if they used an NSAID (HR: 1.64; 95% CI: 1.51 to 1.77; p < 0.0001).
The use of NSAIDs was associated with increased risk of major bleeding, stroke/SE, and hospitalization. The safety and efficacy of DE 150 and 110 mg b.i.d. relative to warfarin were not altered. (Randomized Evaluation of Long Term Anticoagulant Therapy RE-LY; NCT00262600)
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OBJECT Patients presenting with large-territory ischemic strokes may develop intractable cerebral edema that puts them at risk of death unless intervention is performed. The purpose of this study was ...to identify predictors of outcome for decompressive hemicraniectomy (DH) in ischemic stroke. METHODS The authors conducted a retrospective electronic medical record review of 1624 patients from 2006 to 2014. Subjects were screened for DH secondary to ischemic stroke involving the middle cerebral artery, internal carotid artery, or both. Ninety-five individuals were identified. Univariate and multivariate analyses were performed for an array of clinical variables in relationship to functional outcome according to the modified Rankin Scale (mRS). Clinical outcome was assessed at 90 days and at the latest follow-up (mean duration 16.5 months). RESULTS The mean mRS score at 90 days and at the latest follow-up post-DH was 4. Good functional outcome was observed in 40% of patients at 90 days and in 48% of patient at the latest follow-up. The mortality rate at 90 days was 18% and at the last follow-up 20%. Univariate analysis identified a greater likelihood of poor functional outcome (mRS scores of 4-6) in patients with a history of stroke (OR 6.54 95% CI1.39-30.66; p = 0.017), peak midline shift (MLS) > 10 mm (OR 3.35 95% CI 1.33-8.47; p = 0.011), or a history of myocardial infarction (OR 8.95 95% CI1.10-72.76; p = 0.04). Multivariate analysis demonstrated elevated odds of poor functional outcome associated with a history of stroke (OR 9.14 95% CI 1.78-47.05; p = 0.008), MLS > 10 mm (OR 5.15 95% CI 1.58-16.79; p = 0.007), a history of diabetes (OR 5.63 95% CI 1.52-20.88; p = 0.01), delayed time from onset of stroke to DH (OR 1.32 95% CI 1.02-1.72; p = 0.037), and evidence of pupillary dilation prior to DH (OR 4.19 95% CI 1.06-16.51; p = 0.04). Patients with infarction involving the dominant hemisphere had higher odds of unfavorable functional outcome at 90 days (OR 4.73 95% CI 1.36-16.44; p = 0.014), but at the latest follow-up, cerebral dominance was not significantly related to outcome (OR 1.63 95% CI 0.61-4.34; p = 0.328). CONCLUSIONS History of stroke, diabetes, myocardial infarction, peak MLS > 10 mm, increasing duration from onset of stroke to DH, and presence of pupillary dilation prior to intervention are associated with a worse functional outcome.
The impact of IMPACT-AF Ezekowitz, Michael D; Kent, Anthony P
The Lancet (British edition),
10/2017, Letnik:
390, Številka:
10104
Journal Article
Recenzirano
With a global burden in excess of 30 million people, atrial fibrillation could be considered a modern-day epidemic.1 The underuse of anticoagulation in patients with atrial fibrillation for stroke ...prevention is an important illustration of the suboptimal translation of scientific advances into clinical practice.3,4
The fast modulation of lasers is a fundamental requirement for applications in optical communications, high-resolution spectroscopy and metrology. In the terahertz-frequency range, the ...quantum-cascade laser (QCL) is a high-power source with the potential for high-frequency modulation. However, conventional electronic modulation is limited fundamentally by parasitic device impedance, and so alternative physical processes must be exploited to modulate the QCL gain on ultrafast timescales. Here, we demonstrate an alternative mechanism to modulate the emission from a QCL device, whereby optically-generated acoustic phonon pulses are used to perturb the QCL bandstructure, enabling fast amplitude modulation that can be controlled using the QCL drive current or strain pulse amplitude, to a maximum modulation depth of 6% in our experiment. We show that this modulation can be explained using perturbation theory analysis. While the modulation rise-time was limited to ~800 ps by our measurement system, theoretical considerations suggest considerably faster modulation could be possible.
This paper explores changes in technology-enabled omnichannel customer experiences in stores over a five-year period (2014–2019). It contributes to the omnichannel-experience-management literature ...through customer technology-enabled touchpoints within fashion retail. Adopting an exploratory qualitative approach, primary data were obtained using semi-structured interviews with millennial consumers. The findings demonstrate the growing importance of implementing and integrating in-store technologies to improve customer experience. From these, two models are developed: “technology-induced customer experience in-store”; and “technology-enabled customer shopping journey in-store”.
Fashion Industry practices globally are considered to have major negative impacts on both the environment and society. Production and consumption have increasingly moved towards the industry’s model ...of take-create-dispose. As this phenomenon is observed to take center stage in more industrialized and advanced nations, developing countries including Ghana, also contribute directly or indirectly to the negative impacts. Fashion production in Ghana is predominantly centered on small to medium-scale enterprises, and their mode of operation allows for customized small runs tailored to specific end-customers, thereby providing an avenue for exploring sustainable strategies that may have a positive impact on the environment and society. This paper takes a narrative review approach to how the fashion industry in Ghana impacts sustainability and the opportunities to make positive impacts on sustainability at a global level. It demonstrates how Ghana, as a developing country, imports raw materials for both textile and apparel production from counterparts in developing and developed countries and contributes to negative environmental impacts associated with sourcing countries. However, with the emergence of sustainable strategies, local contemporary fashion designers can embrace culturally friendly sustainable models to enhance their practice toward industry sustainability.
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