The 2016-2017 peak luminosity of the pre-main sequence variable V2492 Cyg

V2492 Cyg is a young pre-main sequence star presenting repetitive brightness variations of significant amplitude (Delta R > 5 mag) whose physical origin has been ascribed to both extinction (UXor-type) and accretion (EXor-type) variability, although their mutual proportion has not been clarified yet. Recently, V2492 Cyg has reached a level of brightness ever registered in the period of its documented activity. Optical and near-infrared photometry and spectroscopy have been obtained in October 2016 and between March and July 2017. The source has remained bright until the end of May 2017, then it started to rapidly fade since the beginning of June at a rate of about 0.08 mag/day. On mid-July 2017 the source has reached the same low-brightness level as two years before. Extinction and mass accretion rate were derived by means of the luminosity of the brightest lines, in particular Halpha and Hbeta. A couple of optical high-resolution spectra are also presented to derive information on the gas kinematics. Visual extinction variations do not exceed a few magnitudes, while the mass accretion rate is estimated to vary from less than 10^-8 up to a few 10^-7 M_sun/yr. This latter is comparable to that estimated on the previous high-state in 2010, likely occurred under more severe extinction conditions. The combined analysis of the optical and near-infrared (NIR) observations extends to the present event the original suggestion that the V2492 Cyg variability is a combination of changing extinction and accretion.Comment: Accepted by A&

Anti-infective surface coatings: design and therapeutic promise against device-associated infections

Patient safety and well-being are under increasing threat from hospital-acquired infections [1]. The root cause of a large number of these infections arises from microbial biofilms that colonise on surfaces of medical devices such as the millions of catheters, endotracheal tubes, and prosthetics implanted every year [2]. Biofilm infections are accompanied by increased resistance to antimicrobial therapy and immune clearance, severely limiting treatment options and leading to life-threatening disease [3,4]. Device-associated infections are caused by both bacteria and fungi and, while most studies have focused on single-species biofilms, biofilm-related infections are often polymicrobial [5–8]. Multi-species biofilms, particularly those involving bacterial and fungal pathogens, are more challenging to treat, likely as a consequence of their combined architecture, protective extracellular matrix, and potential synergism in protecting against antimicrobials and host immunity [9–11]. Among the fungi, Candida species are the most important biofilm pathogens [12,13] and the fourth leading cause of blood-stream infections in United States hospitals [7]. Fungal diseases remain difficult to diagnose, mortality rates remain high, and antifungal drug resistance continues to limit therapeutic options [14,15]. We are in desperate need of innovative strategies that target the mechanisms of pathogenesis of polymicrobial biofilms on medical devices. This is a grand challenge because it requires multidisciplinary collaboration and breakthrough research involving physical chemistry, materials science, and microbiology. Communication between these disciplines has not been common, but recent advances show greater convergence in the development of anti-infective devices. At this nexus, we outline the therapeutic promise of anti-infective coatings for medical devices and discuss pitfalls and strategies for overcoming them.Bryan R. Coad, Hans J. Griesser, Anton Y. Peleg, Ana Trave

Navy and the HARV: High angle of attack tactical utility issues

This presentation will highlight results from the latest Navy evaluation of the HARV (March 1994) and focus primarily on the impressions from a piloting standpoint of the tactical utility of thrust vectoring. Issue to be addressed will be mission suitability of high AOA flight, visual and motion feedback cues associated with operating at high AOA, and the adaptability of a pilot to effectively use the increased control power provided by the thrust vectoring system

High-Energy and High-Power-Density Potassium Ion Batteries Using Dihydrophenazine-Based Polymer as Active Cathode Material

Polymeric aromatic amines were shown to be very promising cathodes for lithium-ion batteries. Surprisingly, these materials are scarcely used for designing post-lithium batteries. In this Letter, we investigate the application of the high-voltage poly(N-phenyl-5,10-dihydrophenazine) (p-DPPZ) cathodes for K-ion batteries. The designed batteries demonstrate an impressive specific capacity of 162 mAh g-1 at the current density of 200 mA g-1, operate efficiently at high current densities of 2-10 A g-1, enabling charge and discharge within ∼1-4 min, and deliver the specific capacity of 125-145 mAh g-1 with a retention of 96 and 79% after 100 and 1000 charge-discharge cycles, respectively. Finally, these K-ion batteries with polymeric p-DPPZ cathodes showed rather outstanding specific power of >3 × 104 W kg-1, thus paving a way to the design of ultrafast and durable high-capacity metal-ion batteries matching the increasing demand for high power and high energy density electrochemical energy storage devices. © 2019 American Chemical Society.Government Council on Grants, Russian Federation: 02.Russian Science Foundation, RSF: 16-13-00111This work was supported by Russian Science Foundation, project 16-13-00111. We acknowledge the support of Dr. A. Mumyatov with FTIR spectroscopy measurements. The XPS measurements were supported by the Government of Russian Federation (Act 211, Agreement No. 02.A03.21.0006) and Theme “Electron” (no. AAAA-A18-118020190098-5)

Concurrent validity and reliability of a semi-automated approach to measuring the magnetic resonance imaging morphology of the knee joint in active youth

Post-traumatic knee osteoarthritis is attributed to alterations in joint morphology, alignment, and biomechanics triggered by injury. While magnetic resonance (MR) imaging-based measures of joint morphology and alignment are relevant to understanding osteoarthritis risk, time consuming manual data extraction and measurement limit the number of outcomes that can be considered and deter widespread use. This paper describes the development and evaluation of a semi-automated software for measuring tibiofemoral and patellofemoral joint architecture using MR images from youth with and without a previous sport-related knee injury. After prompting users to identify and select key anatomical landmarks, the software can calculate 37 (14 tibiofemoral, 23 patellofemoral) relevant geometric features (morphology and alignment) based on established methods. To assess validity and reliability, 11 common geometric features were calculated from the knee MR images (proton density and proton density fat saturation sequences; 1.5 T) of 76 individuals with a 3-10-year history of youth sport-related knee injury and 76 uninjured controls. Spearman's or Pearson's correlation coefficients (95% CI) and Bland-Altman plots were used to assess the concurrent validity of the semi-automated software (novice rater) versus expert manual measurements, while intra-class correlation coefficients (ICC 2,1; 95%CI), standard error of measurement (95%CI), 95% minimal detectable change, and Bland-Altman plots were used to assess the inter-rater reliability of the semi-automated software (novice vs resident radiologist rater). Correlation coefficients ranged between 0.89 (0.84, 0.92; Lateral Trochlear Inclination) and 0.97 (0.96, 0.98; Patellar Tilt Angle). ICC estimates ranged between 0.79 (0.63, 0.88; Lateral Patellar Tilt Angle) and 0.98 (0.95, 0.99; Bisect Offset). Bland-Altman plots did not reveal systematic bias. These measurement properties estimates are equal, if not better than previously reported methods suggesting that this novel semi-automated software is an accurate, reliable, and efficient alternative method for measuring large numbers of geometric features of the tibiofemoral and patellofemoral joints from MR studies. </p

Two-dimensional Bose-Einstein Condensation in Cuprate Superconductors

Transition temperatures $T_{c}$ calculated using the BCS model electron-phonon interaction without any adjustable parameters agree with empirical values for quasi-2D cuprate superconductors. They follow from a two-dimensional gas of temperature-dependent Cooper pairs in chemical and thermal equilibrium with unpaired fermions in a boson-fermion (BF) statistical model as the Bose-Einstein condensation (BEC) singularity temperature is approached from above. The {\it linear} (as opposed to quadratic) boson dispersion relation due to the Fermi sea yields substantially higher $T_{c}$'s with the BF model than with BCS or pure-boson BEC theories.Comment: 7 pages including 2 figure

4MOST Consortium Survey 3: Milky Way Disc and Bulge Low-Resolution Survey (4MIDABLE-LR)

The mechanisms of the formation and evolution of the Milky Way are encoded in the orbits, chemistry and ages of its stars. With the 4MOST MIlky way Disk And BuLgE Low-Resolution Survey (4MIDABLE-LR) we aim to study kinematic and chemical substructures in the Milky Way disc and bulge region with samples of unprecedented size out to larger distances and greater precision than conceivable with Gaia alone or any other ongoing or planned survey. Gaia gives us the unique opportunity for target selection based almost entirely on parallax and magnitude range, hence increasing the efficiency in sampling larger Milky Way volumes with well-defined and effective selection functions. Our main goal is to provide a detailed chrono-chemo-kinematical extended map of our Galaxy and the largest Gaia follow-up down to $G = 19$ magnitudes (Vega). The complex nature of the disc components (for example, large target densities and highly structured extinction distribution in the Milky Way bulge and disc area), prompted us to develop a survey strategy with five main sub-surveys that are tailored to answer the still open questions about the assembly and evolution of our Galaxy, while taking full advantage of the Gaia data.Comment: Part of the 4MOST issue of The Messenger, published in preparation of 4MOST Community Workshop, see http://www.eso.org/sci/meetings/2019/4MOST.htm

Pseudogap phase formation in the crossover from Bose-Einstein condensation to BCS superconductivity

A phase diagram for a 2D metal with variable carrier density has been derived. It consists of a normal phase, where the order parameter is absent; a so-called ``abnormal normal'' phase where this parameter is also absent but the mean number of composite bosons (bound pairs) exceeds the mean number of free fermions; a pseudogap phase where the absolute value of the order parameter gradually increases but its phase is a random value, and finally a superconducting (here Berezinskii-Kosterlitz-Thouless) phase. The characteristic transition temperatures between these phases are found. The chemical potential and paramagnetic susceptibility behavior as functions of the fermion density and the temperature are also studied. An attempt is made to qualitatively compare the resulting phase diagram with the features of underdoped high-$T_{c}$ superconducting compounds above their critical temperature.Comment: 26 pages, revtex, 5 EMTeX figures; more discussion and references added; to be published in JET

Flight validation of ground-based assessment for control power requirements at high angles of attack

A review is presented in viewgraph format of an ongoing NASA/U.S. Navy study to determine control power requirements at high angles of attack for the next generation high-performance aircraft. This paper focuses on recent flight test activities using the NASA High Alpha Research Vehicle (HARV), which are intended to validate results of previous ground-based simulation studies. The purpose of this study is discussed, and the overall program structure, approach, and objectives are described. Results from two areas of investigation are presented: (1) nose-down control power requirements and (2) lateral-directional control power requirements. Selected results which illustrate issues and challenges that are being addressed in the study are discussed including test methodology, comparisons between simulation and flight, and general lessons learned

Ginzburg-Landau theory of superconductors with short coherence length

We consider Fermions in two dimensions with an attractive interaction in the singlet d-wave channel of arbitrary strength. By means of a Hubbard-Stratonovich transformation a statistical Ginzburg-Landau theory is derived, which describes the smooth crossover from a weak-coupling BCS superconductor to a condensate of composite Bosons. Adjusting the interaction strength to the observed slope of H_c2 at T_c in the optimally doped high-T_c compounds YBCO and BSCCO, we determine the associated values of the Ginzburg-Landau correlation length xi and the London penetration depth lambda. The resulting dimensionless ratio k_F xi(0) approx 5-8 and the Ginzburg-Landau parameter kappa=lambda xi approx 90-100 agree well with the experimentally observed values. These parameters indicate that the optimally doped materials are still on the weak coupling side of the crossover to a Bose regime.Comment: 12 pages, RevTeX, 6 postscript figures, resubmitted with minor changes in section III, to appear in Physical Review