812 research outputs found
Magnesium Diboride Flexible Flat Cables for Cryogenic Electronics
Magnesium diboride (MgB2) thin films are a potential alternative to
low-temperature superconductors (LTS) due to a higher critical temperature (Tc)
of approximately 39 K. The reactive evaporation deposition technique also
affords relatively simple growth of MgB2 films on flexible substrates compared
to high-temperature superconductors (HTS). We have designed and fabricated a
cable architecture consisting of MgB2 traces on flexible yttria-stabilized
zirconia (YSZ) compatible with commercially available connectors or direct
wirebonds. Key performance metrics such as critical current density (Jc) and Tc
are measured and compared. We discuss thermal conductivity and passivation
schemes for these cables.Comment: 4 pages with 4 figures. Presented at ASC 2010 - submitted to IEEE
Transactions on Superconductivit
Security Issuance, Institutional Investors and Quid Pro Quo: Insights from SPACs
Security issuance is subject to informational and agency-related frictions.
However, their effects on IPO underpricing are difficult to disentangle. We
consider SPACs and use their institutional features to study these effects
separately. To this end, we identify premium investors who produce information
and whose participation is associated with higher SPAC success and
announcement-period returns. In contrast, non-premium investors engage in quid
pro quo, such that their high returns today means higher participation in
weaker future deals. Furthermore, this quid pro quo is not pure agency cost:
rather, it acts as insurance for issuers, enabling marginal firms to access
financial markets
Cycles in the IPO market
We develop a model in which time-varying real investment opportunities lead to time-varying adverse selection in the market for IPOs. The model is consistent with several stylized facts known about the IPO market: economic expansions are associated with a dramatic increase in the number of firms going public, which is in turn positively correlated with underpricing. Adverse selection is procyclical in the sense that dispersion in unobservable quality across firms should be more pronounced during booms. Taking the premise that uncertainty is resolved (and thus private information revealed) over time, we test this hypothesis by looking at long-run abnormal returns and delisting rates. Consistent with the model, we find (a) greater cross-sectional return variance, and (b) higher incidence of delisting for hot-market IPOs
The State of the Art of Information Integration in Space Applications
This paper aims to present a comprehensive survey on information integration (II) in space informatics. With an ever-increasing scale and dynamics of complex space systems, II has become essential in dealing with the complexity, changes, dynamics, and uncertainties of space systems. The applications of space II (SII) require addressing some distinctive functional requirements (FRs) of heterogeneity, networking, communication, security, latency, and resilience; while limited works are available to examine recent advances of SII thoroughly. This survey helps to gain the understanding of the state of the art of SII in sense that (1) technical drivers for SII are discussed and classified; (2) existing works in space system development are analyzed in terms of their contributions to space economy, divisions, activities, and missions; (3) enabling space information technologies are explored at aspects of sensing, communication, networking, data analysis, and system integration; (4) the importance of first-time right (FTR) for implementation of a space system is emphasized, the limitations of digital twin (DT-I) as technological enablers are discussed, and a concept digital-triad (DT-II) is introduced as an information platform to overcome these limitations with a list of fundamental design principles; (5) the research challenges and opportunities are discussed to promote SII and advance space informatics in future
Rapid evolution of novel biotic interactions in the UK Brown Argus butterfly uses genomic variation from across its geographical range
Understanding the rate and extent to which populations can adapt to novel environments at their ecological margins is fundamental to predicting the persistence of biological communities during ongoing and rapid global change. Recent range expansion in response to climate change in the UK butterfly Aricia agestis is associated with the evolution of novel interactions with a larval food plant, and the loss of its ability to use an ancestral host species. Using ddRAD analysis of 61,210 variable SNPs from 261 females from throughout the UK range of this species, we identify genomic regions at multiple chromosomes that are associated with evolutionary responses, and their association with demographic history and ecological variation. Gene flow appears widespread throughout the range, despite the apparently fragmented nature of the habitats used by this species. Patterns of haplotype variation between selected and neutral genomic regions suggest that evolution associated with climate adaptation is polygenic, resulting from the independent spread of alleles throughout the established range of this species, rather than the colonization of pre-adapted genotypes from coastal populations. These data suggest that rapid responses to climate change do not depend on the availability of pre-adapted genotypes. Instead, the evolution of novel forms of biotic interaction in A. agestis has occurred during range expansion, through the assembly of novel genotypes from alleles from multiple localities
Cardiovascular Outcomes in Trials of New Antidiabetic Drug Classes
Type 2 diabetes is among the most prevalent chronic diseases worldwide and the prevention of associated cardiovascular complications is an important treatment goal. Sodium–glucose co-transporter 2 (SGLT2) inhibitors, glucagon-like peptide 1 (GLP-1) receptor agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors are second-line options after metformin, while cardiovascular outcome trials have been conducted to establish the cardiovascular safety of these antidiabetic drug classes. SGLT2 inhibitors have been shown to have the best overall mortality, renal and cardiovascular outcomes. Reduction in hospitalisation for heart failure is particularly consistent. GLP-1 receptor agonists have also showed some benefits, especially in stroke prevention. DPP-4 inhibitors showed neutral effects on cardiovascular outcomes, but may increase the incidence of heart failure. Favourable outcomes observed in trials of SGLT2 inhibitors mean that these should be the preferred second-line option. DPP-4 inhibitors are useful for patients with diabetes at low cardiovascular risk
Comparative Maps of Safety Features for Fission and Fusion Reactors
Abstract
The differences between nuclear fission and fusion have been discussed widely in the literature. However, little has been done to investigate the key differences in safety designs and regulatory requirements between the nuclear reactor types. In this study, an innovative methodology was successfully developed to map nuclear safety features to the fundamental safety principles set out by the nuclear regulators. Three safety cases were assessed in the mapping study, a research fusion reactor (Joint European Torus), a research fission reactor (Tsing Hua Open-pool Reactor) and a commercial fission reactor (Hinkley Point C). The graphical representation allowed a comparative analysis of the safety features and fundamental principles which revealed differences between the hazard profiles of fission and fusion reactors and provided important insights for the creation of a similar map for a future commercial fusion device.</jats:p
Predicting hospital admission and discharge with symptom or function scores in patients with schizophrenia: pooled analysis of a clinical trial extension
<p>Abstract</p> <p>Background</p> <p>The purpose of this analysis was to evaluate relationships between hospital admission or discharge and scores for symptom or functioning in patients with schizophrenia.</p> <p>Methods</p> <p>Data were from three 52-week open-label extensions of the double-blind pivotal trials of paliperidone extended-release (ER). Symptoms and patient function were measured every 4 weeks using the Personal and Social Performance (PSP) scale and the Positive and Negative Syndrome Scale (PANSS). The intent-to-treat analysis set was defined as open-label patients who had at least one post-baseline PSP and PANSS measurement. Time until first hospitalization was evaluated using the Cox proportional hazard model with categorical time-dependent measures for the PSP (1 to 30, 31 to 70, 71 to 100) or PANSS (< 75, ≥ 75 to < 95, ≥ 95), as well as age, gender, schizophrenia duration, and country. Similar analyses were performed for time to discharge.</p> <p>Results</p> <p>Of the 1,077 enrolled patients, 1,028 (95.5%) met study criteria; of these, 382 (37.2%) were hospitalized at open-label baseline. Compared with patients with PSP ≥ 71 group, the hazard for new hospitalization was 8.351 times greater (<it>P </it>= 0.0001) for patients with the poorest functioning (PSP 1 to 30) and 1.977 times greater (<it>P </it>= 0.0295) for patients with PSP of 31-70 compared to the ≥ 71 group. The hazard for new hospitalization was 5.457 times greater (<it>P </it>< 0.0001) for patients PANSS ≥ 95 and 2.316 times greater (<it>P </it>= 0.0027) for the ≥ 75 to < 95 group compared with the < 75 group. For patients hospitalized at baseline, the PANSS ≥ 95 patients had a discharge hazard that was 0.456 times lower than for the < 75 patients (<it>P </it>< 0.0001). The hazard for discharge was 0.646 times lower (<it>P = </it>0.0012) for the PANSS ≥ 75 to < 95 group compared with the < 75 group. A patient's country was a significant predictor variable, with US patients being admitted and discharged faster.</p> <p>Conclusions</p> <p>Better functioning or being less symptomatic is associated with reduced risk for hospitalization and greater chance for early discharge. Treatments or programs that reduce symptoms or improve function decrease the risk of hospitalization in community patients or increase the chance of discharge for hospitalized patients.</p
Probing the Optical Dynamics of Quantum Emitters in Hexagonal Boron Nitride
Hexagonal boron nitride is a van der Waals material that hosts
visible-wavelength quantum emitters at room temperature. However, experimental
identification of the quantum emitters' electronic structure is lacking, and
key details of their charge and spin properties remain unknown. Here, we probe
the optical dynamics of quantum emitters in hexagonal boron nitride using
photon emission correlation spectroscopy. Several quantum emitters exhibit
ideal single-photon emission with noise-limited photon antibunching,
. The photoluminescence emission lineshapes are consistent with
individual vibronic transitions. However, polarization-resolved excitation and
emission suggests the role of multiple optical transitions, and photon emission
correlation spectroscopy reveals complicated optical dynamics associated with
excitation and relaxation through multiple electronic excited states. We
compare the experimental results to quantitative optical dynamics simulations,
develop electronic structure models that are consistent with the observations,
and discuss the results in the context of ab initio theoretical calculations.Comment: 31 pages, 16 figures, 6 table
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