Spin entanglement induced by spin-orbit interactions in coupled quantum dots

We theoretically explore the possibility of creating spin quantum entanglement in a system of two electrons confined respectively in two vertically coupled quantum dots in the presence of Rashba type spin-orbit coupling. We find that the system can be described by a generalized Jaynes - Cummings model of two modes bosons interacting with two spins. The lower excitation states of this model are calculated to reveal the underlying physics of the far infrared absorption spectra. The analytic perturbation approach shows that an effective transverse coupling of spins can be obtained by eliminating the orbital degrees of freedom in the large detuning limit. Here, the orbital degrees of freedom of the two electrons, which are described by two modes of bosons, serve as a quantized data bus to exchange the quantum information between two electrons. Then a nontrivial two-qubit logic gate is realized and spin entanglement between the two electrons is created by virtue of spin-orbit coupling.Comment: 7 pages, 5 figure

Magic wavelengths for the np-ns transitions in alkali-metal atoms

Extensive calculations of the electric-dipole matrix elements in alkali-metal atoms are conducted using the relativistic all-order method. This approach is a linearized version of the coupled-cluster method, which sums infinite sets of many-body perturbation theory terms. All allowed transitions between the lowest ns, np_1/2, np_3/2 states and a large number of excited states are considered in these calculations and their accuracy is evaluated. The resulting electric-dipole matrix elements are used for the high-precision calculation of frequency-dependent polarizabilities of the excited states of alkali-metal atoms. We find magic wavelengths in alkali-metal atoms for which the ns and np_1/2 and np_3/2 atomic levels have the same ac Stark shifts, which facilitates state-insensitive optical cooling and trapping.Comment: 12 pages, 8 figure

2-(2-p-Tolyl­benzo[g]quinolin-3-yl)ethanol

In the title compound, C22H19NO, the pyridine ring and the adjacent naphthalene ring system are nearly coplanar, making a dihedral angle of 3.3 (1)°, while the pyridine and benzene rings are perpendicular to each other, with a dihedral angle of 89.9 (1)°. The crystal packing is stabilized by inter­molecular O—H⋯N hydrogen bonds and C—H⋯π inter­actions

Rapid serum tube technology overcomes problems associated with use of anticoagulants

Introduction: Failure to obtain complete blood clotting in serum is a common laboratory problem. Our aim was to determine whether snake prothrombin activators are effective in clotting blood and producing quality serum for analyte measurement in anticoagulated patients. Materials and methods: Whole blood clotting was studied in a total of 64 blood samples (41 controls, 20 Warfarin patients, 3 anticoagulated patients using snake venom prothrombin activator (OsPA)) with plain tubes. Coagulation was analysed using a visual assay, Hyland-Clotek and thromboelastography. Healthy control blood was spiked with a range of anticoagulants to determine the effectiveness of OsPa-induced clotting. A paired analysis of a Dabigatran patient and a control investigated the effectiveness of the OsPA clotting tubes. Biochemical analytes (N = 31) were determined for 7 samples on chemistry and immunoassay analysers and compared with commercial tubes. Results: Snake venom prothrombin activators efficiently coagulated blood and plasma spiked with heparin and commonly used anticoagulants. Clotting was observed in the presence of anticoagulants whereas no clotting was observed in BDRST tubes containing 3 U/mL of heparin. Snake venom prothrombin activator enhanced heparinised blood clotting by shortening substantially the clotting time and improving significantly the strength of the clot. Comparison of 31 analytes from the blood of five healthy and two anticoagulated participants gave very good agreement between the analyte concentrations determined. Conclusions: Our results showed that the snake venom prothrombin activators OsPA and PtPA efficiently coagulated recalcified and fresh bloods with or without added anticoagulants. These procoagulants produced high quality serum for accurate analyte measurement

Loss of HIF-1α in endothelial cells disrupts a hypoxia-driven VEGF autocrine loop necessary for tumorigenesis

AbstractWe deleted the hypoxia-responsive transcription factor HIF-1α in endothelial cells (EC) to determine its role during neovascularization. We found that loss of HIF-1α inhibits a number of important parameters of EC behavior during angiogenesis: these include proliferation, chemotaxis, extracellular matrix penetration, and wound healing. Most strikingly, loss of HIF-1α in EC results in a profound inhibition of blood vessel growth in solid tumors. These phenomena are all linked to a decreased level of VEGF expression and loss of autocrine response of VEGFR-2 in HIF-1α null EC. We thus show that a HIF-1α-driven, VEGF-mediated autocrine loop in EC is an essential component of solid tumor angiogenesis

SeaWiFS Technical Report Series

This document provides brief reports, or case studies, on a number of investigations sponsored by the Calibration and Validation Team (CVT) within the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project. Chapter I describes the calibration and characterization of the GSFC sphere, which was used in the recent recalibration of the SeaWiFS instrument. Chapter 2 presents a revision of the diffuse attenuation coefficient, K(490), algorithm based on the SeaWiFS wavelengths. Chapter 3 provides an implementation scheme for an algorithm to remove out-of-band radiance when using a sensor calibration based on a finite width (truncated) spectral response function, e.g., between the 1% transmission points. Chapter 4 describes the implementation schemes for the stray light quality flag (local area coverage [LAC] and global area coverage [GAC]) and the LAC stray light correction

Design and formative evaluation of a virtual voice-based coach for problem-solving treatment: Observational study

BACKGROUND: Artificial intelligence has provided new opportunities for human interactions with technology for the practice of medicine. Among the recent artificial intelligence innovations, personal voice assistants have been broadly adopted. This highlights their potential for health care-related applications such as behavioral counseling to promote healthy lifestyle habits and emotional well-being. However, the use of voice-based applications for behavioral therapy has not been previously evaluated. OBJECTIVE: This study aimed to conduct a formative user evaluation of Lumen, a virtual voice-based coach developed as an Alexa skill that delivers evidence-based, problem-solving treatment for patients with mild to moderate depression and/or anxiety. METHODS: A total of 26 participants completed 2 therapy sessions-an introductory (session 1) and a problem-solving (session 2)-with Lumen. Following each session with Lumen, participants completed user experience, task-related workload, and work alliance surveys. They also participated in semistructured interviews addressing the benefits, challenges and barriers to Lumen use, and design recommendations. We evaluated the differences in user experience, task load, and work alliance between sessions using 2-tailed paired t tests. Interview transcripts were coded using an inductive thematic analysis to characterize the participants\u27 perspectives regarding Lumen use. RESULTS: Participants found Lumen to provide high pragmatic usability and favorable user experience, with marginal task load during interactions for both Lumen sessions. However, participants experienced a higher temporal workload during the problem-solving session, suggesting a feeling of being rushed during their communicative interactions. On the basis of the qualitative analysis, the following themes were identified: Lumen\u27s on-demand accessibility and the delivery of a complex problem-solving treatment task with a simplistic structure for achieving therapy goals; themes related to Lumen improvements included streamlining and improved personalization of conversations, slower pacing of conversations, and providing additional context during therapy sessions. CONCLUSIONS: On the basis of an in-depth formative evaluation, we found that Lumen supported the ability to conduct cognitively plausible interactions for the delivery of behavioral therapy. Several design suggestions identified from the study including reducing temporal and cognitive load during conversational interactions, developing more natural conversations, and expanding privacy and security features were incorporated in the revised version of Lumen. Although further research is needed, the promising findings from this study highlight the potential for using Lumen to deliver personalized and accessible mental health care, filling a gap in traditional mental health services

Isolation of MECP2-null Rett Syndrome patient hiPS cells and isogenic controls through X-chromosome inactivation

Rett syndrome (RTT) is a neurodevelopmental autism spectrum disorder that affects girls due primarily to mutations in the gene encoding methyl-CpG binding protein 2 (MECP2). The majority of RTT patients carry missense and nonsense mutations leading to a hypomorphic MECP2, while null mutations leading to the complete absence of a functional protein are rare. MECP2 is an X-linked gene subject to random X-chromosome inactivation resulting in mosaic expression of mutant MECP2. The lack of human brain tissue motivates the need for alternative human cellular models to study RTT. Here we report the characterization of a MECP2 mutation in a classic female RTT patient involving rearrangements that remove exons 3 and 4 creating a functionally null mutation. To generate human neuron models of RTT, we isolated human induced pluripotent stem (hiPS) cells from RTT patient fibroblasts. RTT-hiPS cells retained the MECP2 mutation, are pluripotent and fully reprogrammed, and retained an inactive X-chromosome in a nonrandom pattern. Taking advantage of the latter characteristic, we obtained a pair of isogenic wild-type and mutant MECP2 expressing RTT-hiPS cell lines that retained this MECP2 expression pattern upon differentiation into neurons. Phenotypic analysis of mutant RTT-hiPS cell-derived neurons demonstrated a reduction in soma size compared with the isogenic control RTT-hiPS cell-derived neurons from the same RTT patient. Analysis of isogenic control and mutant hiPS cell-derived neurons represents a promising source for understanding the pathogenesis of RTT and the role of MECP2 in human neurons