9,737 research outputs found
Superconductivity from spin fluctuations and long-range interactions in magic-angle twisted bilayer graphene
Magic-angle twisted bilayer graphene (MATBG) has been extensively explored
both theoretically and experimentally as a suitable platform for a rich and
tunable phase diagram that includes ferromagnetism, charge order, broken
symmetries, and unconventional superconductivity. In this work, we investigate
the intricate interplay between long-range electron-electron interactions, spin
fluctuations, and superconductivity in MATBG. By employing a low-energy model
for MATBG that captures the correct shape of the flat bands, we explore the
effects of short- and long-range interactions on spin fluctuations and their
impact on the superconducting (SC) pairing vertex in the Random Phase
Approximation (RPA). We find that the SC state is notably influenced by the
strength of long-range Coulomb interactions. Interestingly, our RPA
calculations indicate that there is a regime where the system can traverse from
a magnetic phase to the SC phase by \emph{increasing} the relative strength of
long-range interactions compared to the on-site ones. These findings underscore
the relevance of electron-electron interactions in shaping the intriguing
properties of MATBG and offer a pathway for designing and controlling its SC
phase.Comment: 9 pages, 5 figure
Predicting In-Hospital Mortality of ICU Patients: The PhysioNet/Computing in Cardiology Challenge 2012
Acuity scores, such as APACHE, SAPS, MPM, and SOFA, are widely used to account for population differ ences in studies aiming to compare how medications, care guidelines, surgery, and other interventions impact mortality in Intensive Care Unit (ICU) patients. By contrast, the focus of the PhysioNet/CinC Challenge 2012 is to develop methods for patient-specific prediction of in-hospital mortality. The data used for the challenge consisted of 5 general descriptors and 36 time series (measurements of vital signs and laboratory results) from the first 48 hours of the first available ICU stay of 12,000 adult patients from the MIMIC II database. The challenge was organized as two events: event 1 measured performance of a binary classifier, and event 2 measured performance of a risk estimator. The score of event 1 was the lower of sensitivity and positive predictive value. The score for event 2 was a range-normalized Hosmer-Lemeshow statistic. A baseline algorithm (using SAPS-1) obtained event 1 and 2 scores of 0.3125 and 68.58 respectively. Most participants submitted entries that outperformed the baseline algorithm. The top final scores for events 1 and 2 were 0.5353 and 17.88 respectively.National Institute for Biomedical Imaging and Bioengineering (U.S.)National Institute of General Medical Sciences (U.S.) (NIH cooperative agreement U01-EB-008577)National Institute of General Medical Sciences (U.S.) (NIH grant R01-EB-001659
Efficient measurement of quantum gate error by interleaved randomized benchmarking
We describe a scalable experimental protocol for obtaining estimates of the
error rate of individual quantum computational gates. This protocol, in which
random Clifford gates are interleaved between a gate of interest, provides a
bounded estimate of the average error of the gate under test so long as the
average variation of the noise affecting the full set of Clifford gates is
small. This technique takes into account both state preparation and measurement
errors and is scalable in the number of qubits. We apply this protocol to a
superconducting qubit system and find gate errors that compare favorably with
the gate errors extracted via quantum process tomography.Comment: 5 pages, 2 figures, published versio
Assessment of Apple Watch Series 6 pulse oximetry and electrocardiograms in a pediatric population
BACKGROUND: Recent technologic advances have resulted in increased development and utilization of direct-to-consumer cardiac wearable devices with various functionality. This study aimed to assess Apple Watch Series 6 (AW6) pulse oximetry and electrocardiography (ECG) in a cohort of pediatric patients.
METHODS: This single-center, prospective study enrolled pediatric patients ≥ 3kg and having an ECG and/or pulse oximetry (SpO2) as part of their planned evaluation. Exclusion criteria: 1) non-English speaking patients and 2) patients in state custody. Simultaneous tracings were obtained for SpO2 and ECG with concurrent standard pulse oximeter and 12-lead ECG. AW6 automated rhythm interpretations were compared to physician over-read and categorized as accurate, accurate with missed findings, inconclusive (automated interpretation: inconclusive ), or inaccurate.
RESULTS: A total of 84 patients were enrolled over a 5-week period. 68 patients (81%) were placed into the SpO2 and ECG arm, with 16 patients (19%) placed into the SpO2 only arm. Pulse oximetry data was successfully collected in 71/84 (85%) patients and ECG data in 61/68 (90%). ΔSpO2 between modalities was 2.0±2.6% (r = 0.76). ΔRR was 43±44msec (r = 0.96), ΔPR 19±23msec (r = 0.79), ΔQRS 12±13msec (r = 0.78), and ΔQT 20±19msec (r = 0.9). The AW6 automated rhythm analysis yielded a 75% specificity and found: 1) 40/61 (65.6%) accurate , 2) 6/61 (9.8%) accurate with missed findings , 3) 14/61 (23%) inconclusive , and 4) 1/61 (1.6%) incorrect.
CONCLUSION: The AW6 can accurately measure oxygen saturation when compared to hospital pulse oximeters in pediatric patients and provide good quality single lead ECGs that allow for accurate measurement of RR, PR, QRS, and QT intervals with manual interpretation. The AW6-automated rhythm interpretation algorithm has limitations for smaller pediatric patients and patients with abnormal ECGs
A survey for Fe 6.4 keV emission in young stellar objects in rho Oph: the strong fluorescence from Elias 29
We report the results of a search for 6.4 keV Fe fluorescent emission in
Young Stellar Objects (YSOs) with measured accretion luminosities in the rho
Oph cloud, using all existing chandra and XMM-Newton observations of the
region. A total of nine such YSOs have X-ray data with sufficiently high S/N
for the 6.4 keV line to be potentially detected if present. A positive
detection of the Fe 6.4 keV line is reported for one object, Elias 29, in both
the XMM-Newton and the chandra data. The 6.4 keV line is detected in Elias 29
both during quiescent and flaring emission, unlikely all previously reported
detections of 6.4 keV Fe fluorescence in YSOs which were made during intense
flaring. The observed equivalent width of the fluorescent line is large, at
W_alpha approx 140 eV, ruling out fluorescence from diffuse circumstellar
material. It is also larger than expected for simple reflection from a
solar-composition photosphere or circumstellar disk, but it is compatible with
being due to fluorescence from a centrally illuminated circumstellar disk. The
X-ray spectrum of Elias 29 is also peculiar in terms of its high (ionized) Fe
abundance, as evident from the very intense Fe xxv 6.7 keV line emission; we
speculate on the possible mechanism leading to the observed high abundance.Comment: Accepted by A&
In utero exposure to cigarette smoke dysregulates human fetal ovarian developmental signalling
STUDY QUESTION How does maternal cigarette smoking disturb development of the human fetal ovary?<p></p>
SUMMARY ANSWER Maternal smoking increases fetal estrogen titres and dysregulates several developmental processes in the fetal ovary.<p></p>
WHAT IS KNOWN ALREADY Exposure to maternal cigarette smoking during gestation reduces human fetal ovarian cell numbers, germ cell proliferation and subsequent adult fecundity.<p></p>
STUDY DESIGN, SIZE, DURATION The effects of maternal cigarette smoking on the second trimester human fetal ovary, fetal endocrine signalling and fetal chemical burden were studied. A total of 105 fetuses were studied, 56 from mothers who smoked during pregnancy and 49 from those who did not.<p></p>
PARTICIPANTS/MATERIALS, SETTING METHODS Ovary, liver and plasma samples were collected from electively terminated, normally progressing, second trimester human fetuses. Circulating fetal hormones, levels of 73 fetal ovarian transcripts, protein localization, density of oocytes/primordial follicles and levels of 16 polycyclic aromatic hydrocarbons (PAHs) in the fetal liver were determined.<p></p>
MAIN RESULTS AND THE ROLE OF CHANCE Circulating fetal estrogen levels were very high and were increased by maternal smoking (ANOVA, P = 0.055–0.004 versus control). Smoke exposure also dysregulated (two-way ANOVA, smoking versus gestation weeks interaction, P = 0.046–0.023) four fetal ovarian genes (cytochrome P450 scc [CYP11A1], NOBOX oogenesis homeobox [NOBOX], activator of apoptosis harakiri [HRK], nuclear receptor subfamily 2, group E, member 1 [NR2E1]), shifted the ovarian Inhibin βA/inhibin α ratio (NHBA/INHA) transcript ratio in favour of activin (ANOVA, P = 0.049 versus control) and reduced the proportion of dominant-negative estrogen receptor 2 (ERβ: ESR2) isoforms in half the exposed fetuses. PAHs, ligands for the aryl hydrocarbon receptor (AHR), were increased nearly 6-fold by maternal smoking (ANOVA, P = 0.011 versus control). A fifth transcript, COUP transcription factor 1 (nuclear receptor subfamily 2, group F, member 1: NR2F1, which contains multiple AHR-binding sites), was both significantly increased (ANOVA, P = 0.026 versus control) and dysregulated by (two-way ANOVA, smoking versus gestation weeks interaction, P = 0.021) maternal smoking. NR2F1 is associated with repression of FSHR expression and smoke-exposed ovaries failed to show the normal increase in FSHR expression during the second trimester. There was a significantly higher number of DEAD (Asp-Glu-Ala-Asp) box polypeptide 4 (DDX4) VASA-positive (ANOVA, P = 0.016 versus control), but not POU domain, class 1, transcription factor 1 (POU5F1) OCT3/4-positive, oocytes in smoke-exposed fetuses and this matched with a significantly higher number of primordial follicles (ANOVA, P = 0.024 versus control).<p></p>
LIMITATIONS, REASONS FOR CAUTION The effects of maternal smoking on establishment of the maximum fetal primordial follicle pool cannot be reliably studied in our population since the process is not completed until 28 weeks of gestation and normal fetuses older than 21 weeks of gestation are not available for study. Our data suggest that some fetal ovaries are affected by smoke exposure while others are not, indicating that additional studies, with larger numbers, may show more significant effects.<p></p>
WIDER IMPLICATIONS OF THE FINDINGS Fetal exposure to chemicals in cigarette smoke is known to lead to reduced fecundity in women. Our study suggests, for the first time, that this occurs via mechanisms involving activation of AHR, disruption of inhibin/activin and estrogen signalling, increased exposure to estrogen and dysregulation of multiple molecular pathways in the exposed human fetal ovary. Our data also suggest that alterations in the ESR2 positive and dominant negative isoforms may be associated with reduced sensitivity of some fetuses to increased estrogens and maternal smoking
The dynamics of animal social networks: Analytical, conceptual, and theoretical advances
Social network analysis provides a broad and complex perspective on animal sociality that is widely applicable to almost any species. Recent applications demonstrate the utility of network analysis for advancing our understanding of the dynamics, selection pressures, development, and evolution of complex social systems. However, most studies of animal social networks rely primarily on a descriptive approach. To propel the field of animal social networks beyond exploratory analyses and to facilitate the integration of quantitative methods that allow for the testing of ecologically and evolutionarily relevant hypotheses, we review methodological and conceptual advances in network science, which are underutilized in studies of animal sociality. First, we highlight how the use of statistical model- ing and triadic motifs analysis can advance our understanding of the processes that structure networks. Second, we discuss how the consideration of temporal changes and spatial constraints can shed light on the dynamics of social networks. Third, we consider how the study of variation at multiple scales can potentially transform our understanding of the structure and function of animal networks. We direct readers to analytical tools that facilitate the adoption of these new concepts and methods. Our goal is to provide behavioral ecologists with a toolbox of current methods that can stimulate novel insights into the ecological influences and evolutionary pressures structuring networks and advance our understanding of the proximate and ultimate processes that drive animal sociality
The dynamics of animal social networks: Analytical, conceptual, and theoretical advances
Social network analysis provides a broad and complex perspective on animal sociality that is widely applicable to almost any species. Recent applications demonstrate the utility of network analysis for advancing our understanding of the dynamics, selection pressures, development, and evolution of complex social systems. However, most studies of animal social networks rely primarily on a descriptive approach. To propel the field of animal social networks beyond exploratory analyses and to facilitate the integration of quantitative methods that allow for the testing of ecologically and evolutionarily relevant hypotheses, we review methodological and conceptual advances in network science, which are underutilized in studies of animal sociality. First, we highlight how the use of statistical model- ing and triadic motifs analysis can advance our understanding of the processes that structure networks. Second, we discuss how the consideration of temporal changes and spatial constraints can shed light on the dynamics of social networks. Third, we consider how the study of variation at multiple scales can potentially transform our understanding of the structure and function of animal networks. We direct readers to analytical tools that facilitate the adoption of these new concepts and methods. Our goal is to provide behavioral ecologists with a toolbox of current methods that can stimulate novel insights into the ecological influences and evolutionary pressures structuring networks and advance our understanding of the proximate and ultimate processes that drive animal sociality
Scalar radiation emitted from a rotating source around a Reissner-Nordstrom black hole
We investigate the radiation emitted from a scalar source in circular orbit
around a Reissner-Nordstrom black hole. Particle and energy emission rates are
analytically calculated in the low- and high-frequency regimes and shown to be
in full agreement with a numerical calculation. Our investigation is connected
with the recent discussion on the validity of the cosmic censorship conjecture
in the quantum realm.Comment: 7 pages, 9 figures, submitted to Phys. Rev.
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Mycolactone-dependent depletion of endothelial cell thrombomodulin is strongly associated with fibrin deposition in Buruli ulcer lesions
A well-known histopathological feature of diseased skin in Buruli ulcer (BU) is coagulative necrosis caused by the Mycobacterium ulcerans macrolide exotoxin mycolactone. Since the underlying mechanism is not known, we have investigated the effect of mycolactone on endothelial cells, focussing on the expression of surface anticoagulant molecules involved in the protein C anticoagulant pathway. Congenital deficiencies in this natural anticoagulant pathway are known to induce thrombotic complications such as purpura fulimans and spontaneous necrosis. Mycolactone profoundly decreased thrombomodulin (TM) expression on the surface of human dermal microvascular endothelial cells (HDMVEC) at doses as low as 2ng/ml and as early as 8hrs after exposure. TM activates protein C by altering thrombin's substrate specificity, and exposure of HDMVEC to mycolactone for 24 hours resulted in an almost complete loss of the cells' ability to produce activated protein C. Loss of TM was shown to be due to a previously described mechanism involving mycolactone-dependent blockade of Sec61 translocation that results in proteasome-dependent degradation of newly synthesised ER-transiting proteins. Indeed, depletion from cells determined by live-cell imaging of cells stably expressing a recombinant TM-GFP fusion protein occurred at the known turnover rate. In order to determine the relevance of these findings to BU disease, immunohistochemistry of punch biopsies from 40 BU lesions (31 ulcers, nine plaques) was performed. TM abundance was profoundly reduced in the subcutis of 78% of biopsies. Furthermore, it was confirmed that fibrin deposition is a common feature of BU lesions, particularly in the necrotic areas. These findings indicate that there is decreased ability to control thrombin generation in BU skin. Mycolactone's effects on normal endothelial cell function, including its ability to activate the protein C anticoagulant pathway are strongly associated with this. Fibrin-driven tisischemia could contribute to the development of the tissue necrosis seen in BU lesions
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