Changes in magnetic scattering anisotropy at a ferromagnetic/superconducting interface

We show that some metals and alloys (X = Cu, Ag, FeMn, or Cu and Ag combined with each other), sputtered between ferromagnetic Co and superconducting Nb, produce no change in current-perpendicular-to-plane magnetoresistance (CPP-MR) in a carefully designed CPP-spin-valve. In contrast, other metals (Ru or Au) or combinations (Cu or Ag combined with Au, Ru, or FeMn) change the CPP-MR, in some cases even reversing its sign. We ascribe these changes to activation of magnetic scattering anisotropies at a ferromagnetic/superconducting interface, apparently by strong spin-flipping between the Co and Nb layers.Comment: 4 pages, 4 figure

Zodiacal Exoplanets in Time (ZEIT). V. A Uniform Search for Transiting Planets in Young Clusters Observed by K2

Detection of transiting exoplanets around young stars is more difficult than for older systems owing to increased stellar variability. Nine young open cluster planets have been found in the K2 data, but no single analysis pipeline identified all planets. We have developed a transit search pipeline for young stars that uses a transit-shaped notch and quadratic continuum in a 12 or 24 hr window to fit both the stellar variability and the presence of a transit. In addition, for the most rapid rotators ( days) we model the variability using a linear combination of observed rotations of each star. To maximally exploit our new pipeline, we update the membership for four stellar populations observed by K2 (Upper Scorpius, Pleiades, Hyades, Praesepe) and conduct a uniform search of the members. We identify all known transiting exoplanets in the clusters, 17 eclipsing binaries, one transiting planet candidate orbiting a potential Pleiades member, and three orbiting unlikely members of the young clusters. Limited injection recovery testing on the known planet hosts indicates that for the older Praesepe systems we are sensitive to additional exoplanets as small as 1-2 R ⊕, and for the larger Upper Scorpius planet host (K2-33) our pipeline is sensitive to ∼4 R ⊕ transiting planets. The lack of detected multiple systems in the young clusters is consistent with the expected frequency from the original Kepler sample, within our detection limits. With a robust pipeline that detects all known planets in the young clusters, occurrence rate testing at young ages is now possible

dS/CFT correspondence on a brane

We study branes moving in an AdS Schwarzschild black hole background. When the brane tension exceeds a critical value, the induced metric on the brane is of FRW type and asymptotically de Sitter. We discuss the relevance of such configurations to dS/CFT correspondence. When the black hole mass reaches a critical value that depends on the brane tension, the brane interpolates in the infinite past and future between a dS space and a finite space of zero Hubble constant. This corresponds to a cosmological evolution without a Big Bang or a Big Crunch. Moreover, the central charge of the CFT dual to the dS brane enters the Cardy-Verlinde formula that gives the entropy of the thermal CFT dual to the bulk AdS black hole.Comment: 15 pages, 1 figure, v2 references adde

The COVID-19 pandemic and OBGYN residency training: We have a problem and it’s not just masks

Background: The COVID-19 pandemic has left no one untouched. Resident trainees have been driven to reconsider virtually every component of their daily lives. The purpose of this pilot study is to evaluate the impact of the COVID-19 pandemic on Obstetrics and Gynecology (OBGYN) residency training and education. Methods: A cross-sectional pilot study was conducted between 2/2022 and 5/2022. A survey was created and distributed to OBGYN residents. The survey queried the effects of the pandemic on OBGYN residents’ procedure skills training and mental health. Results: A total of 95 OBGYN residents across programs affiliated with each American College of Obstetricians and Gynecologists (ACOG) district participated in the survey. Among them, just over half (n = 52, 55%) self-identified as under-represented minorities. A significant majority, 80% (n = 81), felt their gynecological training was inadequate, with 70% of fourth-year residents expressing a lack of confidence in their ability to independently practice gynecology after graduation. This lack of confidence among fourth-year residents suggests a notable disparity in readiness for independent gynecological practice, linked to meeting ACGME requirements before completing their residency (p = 0.013). Among the residents who reported a negative impact of the pandemic on their mental health (n = 76, 80%), about 40% (n = 31) had contemplated self-harm or knew a colleague who considered or attempted suicide (p < 0.001). This issue was especially pronounced in residents experiencing burnout (n = 44, 46%), as nearly half (n = 19, 43%) reported suicidal thoughts or knew someone in their program who had such thoughts or engaged in self-harm (p = 0.048). Conclusions: Residents expressed concerns about reduced hands-on gynecological training and doubts about their readiness for independent practice post-residency, highlighting the need for enhanced support through mentorship and revised training curriculums. Additionally, despite the availability of mental health resources to address pandemic-induced burnout, their underuse suggests a need for more accessible time for residents to use at their discretion and flexible training schedules that encourage mental health support resource utilization

THE MASS-RADIUS RELATION OF YOUNG STARS. I. USCO 5, AN M4.5 ECLIPSING BINARY IN UPPER SCORPIUS OBSERVED BY K2

We present the discovery that UScoCTIO 5, a known spectroscopic binary in the Upper Scorpius star-forming region (P = 34 days, Mtot sin(i) = 0.64 M⊙), is an eclipsing system with both primary and secondary eclipses apparent in K2 light curves obtained during Campaign 2. We have simultaneously fit the eclipse profiles from the K2 light curves and the existing RV data to demonstrate that UScoCTIO 5 consists of a pair of nearly identical M4.5 stars with MA = 0.329 ± 0.002 M⊙, RA = 0.834 ± 0.006 R⊙, MB = 0.317 ± 0.002 M⊙, and RB = 0.810 ± 0.006 R⊙. The radii are broadly consistent with pre-main-sequence ages predicted by stellar evolutionary models, but none agree to within the uncertainties. All models predict systematically incorrect masses at the 25%-50% level for the HR diagram position of these mid-M dwarfs, suggesting significant modifications to mass-dependent outcomes of star and planet formation. The form of the discrepancy for most model sets is not that they predict luminosities that are too low, but rather that they predict temperatures that are too high, suggesting that the models do not fully encompass the physics of energy transport (via convection and/or missing opacities) and/or a miscalibration of the SpT-Teff scale. The simplest modification to the models (changing Teff to match observations) would yield an older age for this system, in line with the recently proposed older age of Upper Scorpius (τ ∼ 11 Myr)

OA phenotypes, rather than disease stage, drive structural progression – identification of structural progressors from 2 phase III randomized clinical studies with symptomatic knee OA

SummaryBackground/PurposeThe aim of this study was to identify key characteristics of disease progression through investigation of the association of radiographic progression over two years with baseline Joint Space Width (JSW), Kellgren–Lawrence (KL) grade, Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain, Joint Space Narrowing (JSN), and BMI.MethodsData from 2206 subjects (4390 knees) were combined for this post-hoc analysis of two randomized, double-blind, multi-center, placebo-controlled phase III trials (NCT00486434 and NCT00704847) that evaluated the efficacy and safety of 2-years treatment with oral salmon calcitonin of subjects with painful knee osteoarthritis (OA).ResultsThere was a clear positive and significant correlation between KL grade and WOMAC pain and total WOMAC, albeit the variance in pain measures was from min-to-max for all KL categories, emphasizing the heterogeneity of this patient population and pain perception. 32% of target knees did not progress, and only 51% had changes over minimum significant change (MSC). BMI, KL-Score and WOMAC pain was diagnostic, but only KL-score and pain had prognostic value, albeit pain in a non-linear manner.ConclusionThese data clearly describe significant associations between KL grade, JSW, pain and BMI in patients with symptomatic knee OA. KL grade, BMI and WOMAC pain were diagnostically associated with OA based on JSW but only KL-score and pain in a non-linier fashion was prognostic. 50% of patients did not progress more than MSC, highlighting the importance for identification of structural progressors and the phenotypes associated with these. These results suggest that disease phenotypes, rather than disease status, are responsible for disease progression

TESTING the BINARY TRIGGER HYPOTHESIS in FUors

We present observations of three FU Orionis objects (hereafter, FUors) with nonredundant aperture-mask interferometry at 1.59 μm and 2.12 μm that probe for binary companions on the scale of the protoplanetary disk that feeds their accretion outbursts. We do not identify any companions to V1515 Cyg or HBC 722, but we do resolve a close binary companion to V1057 Cyg that is at the diffraction limit ( mas or 30 5 au) and currently much fainter than the outbursting star ( mag). Given the flux excess of the outbursting star, we estimate that the mass of the companion () is similar to or slightly below that of the FUor itself, and therefore it resembles a typical T Tauri binary system. Our observations only achieve contrast limits of mag, and hence we are only sensitive to companions that were near or above the pre-outburst luminosity of the FUors. It remains plausible that FUor outbursts could be tied to the presence of a close binary companion. However, we argue from the system geometry and mass reservoir considerations that these outbursts are not directly tied to the orbital period (i.e., occurring at periastron passage), but instead must only occur infrequently

Orbital architectures of planet-hosting binaries - II. Low mutual inclinations between planetary and stellar orbits

Planet formation is often considered in the context of one circumstellar disc around one star. Yet, stellar binary systems are ubiquitous, and thus a substantial fraction of all potential planets must form and evolve in more complex, dynamical environments. We present the results of a 5 yr astrometric monitoring campaign studying 45 binary star systems that host Kepler planet candidates. The planet-forming environments in these systems would have literally been shaped by the binary orbits that persist to the present day. Crucially, the mutual inclinations of star-planet orbits can only be addressed by a statistical sample. We describe in detail our sample selection and Keck/NIRC2 laser guide star adaptive optics observations collected from 2012 to 2017. We measure orbital arcs, with a typical accuracy of ∼0.1 mas yr-1, that test whether the binary orbits tend to be aligned with the edge-on transiting planet orbits. We rule out randomly distributed binary orbits at 4.7σ, and we show that low mutual inclinations are required to explain the observed orbital arcs. If the stellar orbits have a field binary-like eccentricity distribution, then the best match to our observed orbital arcs is a distribution of mutual inclinations ranging from 0° to 30°. We discuss the implications of such widespread planet-binary alignment in the theoretical context of planet formation and circumstellar disc evolution

Holographic principle in the BDL brane cosmology

We study the holographic principle in the brane cosmology. Especially we describe how to accommodate the 5D anti de Sitter Schwarzschild (AdSS$_5$) black hole in the Binetruy-Deffayet-Langlois (BDL) approach of brane cosmology. It is easy to make a connection between a mass $M$ of the AdSS$_5$ black hole and a conformal field theory (CFT)-radiation dominated universe on the brane in the moving domain wall approach. But this is not established in the BDL approach. In this case we use two parameters $C_1, C_2$ in the Friedmann equation. These arise from integration and are really related to the choice of initial bulk matter. If one chooses a bulk energy density $\rho_B$ to account for a mass $M$ of the AdSS$_5$ black hole and the static fifth dimension, a CFT-radiation term with $\rho_{CFT} \sim M/a^{4}$ comes out from the bulk matter without introducing a localized matter distribution on the brane. This means that the holographic principle can be established in the BDL brane cosmology.Comment: 9 pages, a version to appear in PR

Zodiacal Exoplanets in Time (ZEIT). VIII. A Two-planet System in Praesepe from K2 Campaign 16

Young planets offer a direct view of the formation and evolution processes that produced the diverse population of mature exoplanet systems known today. The repurposed Kepler mission K2 is providing the first sample of young transiting planets by observing populations of stars in nearby, young clusters and stellar associations. We report the detection and confirmation of two planets transiting K2-264, an M2.5 dwarf in the 650 Myr old Praesepe open cluster. Using our notch-filter search method on the K2 light curve, we identify planets with periods of 5.84 and 19.66 days. This is currently the second known multi-transit system in open clusters younger than 1 Gyr. The inner planet has a radius of 2.27+0.20 -0.16 R⊕ and the outer planet has a radius of 2.27+0.20 -0.18 R ⊕. Both planets are likely mini-Neptunes. These planets are expected to produce radial velocity signals of 3.4 and 2.7 m s-1, respectively, which is smaller than the expected stellar variability in the optical (≃30 m s-1), making mass measurements unlikely in the optical but possible with future near-infrared spectrographs. We use an injection-recovery test to place robust limits on additional planets in the system and find that planets larger than 2 R ⊕ with periods of 1-20 days are unlikely