1,226 research outputs found

    Experimental quantum teleportation over a high-loss free-space channel

    Full text link
    We present a high-fidelity quantum teleportation experiment over a high-loss free-space channel between two laboratories. We teleported six states of three mutually unbiased bases and obtained an average state fidelity of 0.82(1), well beyond the classical limit of 2/3. With the obtained data, we tomographically reconstructed the process matrices of quantum teleportation. The free-space channel attenuation of 31 dB corresponds to the estimated attenuation regime for a down-link from a low-earth-orbit satellite to a ground station. We also discussed various important technical issues for future experiments, including the dark counts of single-photon detectors, coincidence-window width etc. Our experiment tested the limit of performing quantum teleportation with state-of-the-art resources. It is an important step towards future satellite-based quantum teleportation and paves the way for establishing a worldwide quantum communication network

    A review of forward-dynamics simulation models for predicting optimal technique in maximal effort sporting movements

    Get PDF
    The identification of optimum technique for maximal effort sporting tasks is one of the greatest challenges within sports biomechanics. A theoretical approach using forward-dynamics simulation allows individual parameters to be systematically perturbed independently of potentially confounding variables. Each study typically follows a four-stage process of model construction, parameter determination, model evaluation, and model optimization. This review critically evaluates forward-dynamics simulation models of maximal effort sporting movements using a dynamical systems theory framework. Organismic, environmental, and task constraints applied within such models are critically evaluated, and recommendations are made regarding future directions and best practices. The incorporation of self-organizational processes representing movement variability and "intrinsic dynamics" remains limited. In the future, forward-dynamics simulation models predicting individual-specific optimal techniques of sporting movements may be used as indicative rather than prescriptive tools within a coaching framework to aid applied practice and understanding, although researchers and practitioners should continue to consider concerns resulting from dynamical systems theory regarding the complexity of models and particularly regarding self-organization processes

    Identifying young stars in massive star-forming regions for the MYStIX project

    Get PDF
    The Massive Young star-forming Complex Study in Infrared and X-rays (MYStIX) project requires samples of young stars that are likely members of 20 nearby Galactic massive star-forming regions. Membership is inferred from statistical classification of X-ray sources, from detection of a robust infrared excess that is best explained by circumstellar dust in a disk or infalling envelope and from published spectral types that are unlikely to be found among field stars. We present the MYStIX membership lists here, and describe in detail the statistical classification of X-ray sources via a "Naive Bayes Classifier." These membership lists provide the empirical foundation for later MYStIX science studies. © 2013. The American Astronomical Society. All rights reserved.We appreciate the significant time our anonymous referee devoted to this long paper and the useful suggestions offered. The MYStIX project is supported at Penn State by NASA grant NNX09AC74G, NSF grant AST-0908038, and the Chandra ACIS Team contract SV4-74018 (G. Garmire & L. Townsley, Principal Investigators), issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. M. S. Povich was supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-0901646. We thank Steve Majewski and Remy Indebetouw for access to results from the Spitzer Vela-Carina survey. This research made use of data products from the Chandra Data Archive and the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory (California Institute of Technology) under a contract with NASA. This research used data products from the United Kingdom Infrared Telescope (UKIRT), which is operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the U.K.; some UKIRT data were obtained as part of the UKIRT Infrared Deep Sky Survey (Lawrence et al. 2007) and some were obtained via UKIRT director's discretionary time. This research used data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. The HAWK-I near-infrared observations were collected with the High Acuity Wide-field K-band Imager instrument on the ESO 8 m Very Large Telescope at Paranal Observatory, Chile, under ESO programme 60.A-9284(K). This research has also made use of NASA's Astrophysics Data System Bibliographic Services, the SIMBAD database operated at the Centre de Données Astronomique de Strasbourg, and SAOImage DS9 software developed by Smithsonian Astrophysical Observatory

    Age Gradients in the Stellar Populations of Massive Star Forming Regions Based on a New Stellar Chronometer

    Get PDF
    Accepted for publication in ApJ; 89 pages, 23 figures, 2 Tables; High quality version is at http://astro.psu.edu/mystixAuthor's accepted version of article published at http://dx.doi.org/10.1088/0004-637X/787/2/108A major impediment to understanding star formation in massive star forming regions (MSFRs) is the absence of a reliable stellar chronometer to unravel their complex star formation histories. We present a new estimation of stellar ages using a new method that employs near-infrared (NIR) and X-ray photometry, AgeJX. Stellar masses are derived from X-ray luminosities using the Lx - Mass relation from the Taurus cloud. J-band luminosities are compared to mass-dependent pre-main-sequence evolutionary models to estimate ages. AgeJX is sensitive to a wide range of evolutionary stages, from disk-bearing stars embedded in a cloud to widely dispersed older pre-main sequence stars. The MYStIX (Massive Young Star-Forming Complex Study in Infrared and X-ray) project characterizes 20 OB-dominated MSFRs using X-ray, mid-infrared, and NIR catalogs. The AgeJX method has been applied to 5525 out of 31,784 MYStIX Probable Complex Members. We provide a homogeneous set of median ages for over a hundred subclusters in 15 MSFRs; median subcluster ages range between 0.5 Myr and 5 Myr. The important science result is the discovery of age gradients across MYStIX regions. The wide MSFR age distribution appears as spatially segregated structures with different ages. The AgeJX ages are youngest in obscured locations in molecular clouds, intermediate in revealed stellar clusters, and oldest in distributed populations. The NIR color index J-H, a surrogate measure of extinction, can serve as an approximate age predictor for young embedded clusters

    The MYStIX infrared-excess source catalog

    Get PDF
    The Massive Young Star-Forming Complex Study in Infrared and X-rays (MYStIX) project provides a comparative study of 20 Galactic massive star-forming complexes (d = 0.4-3.6 kpc). Probable stellar members in each target complex are identified using X-ray and/or infrared data via two pathways: (1) X-ray detections of young/massive stars with coronal activity/strong winds or (2) infrared excess (IRE) selection of young stellar objects (YSOs) with circumstellar disks and/or protostellar envelopes. We present the methodology for the second pathway using Spitzer/IRAC, 2MASS, and UKIRT imaging and photometry. Although IRE selection of YSOs is well-trodden territory, MYStIX presents unique challenges. The target complexes range from relatively nearby clouds in uncrowded fields located toward the outer Galaxy (e.g., NGC 2264, the Flame Nebula) to more distant, massive complexes situated along complicated, inner Galaxy sightlines (e.g., NGC 6357, M17). We combine IR spectral energy distribution (SED) fitting with IR color cuts and spatial clustering analysis to identify IRE sources and isolate probable YSO members in each MYStIX target field from the myriad types of contaminating sources that can resemble YSOs: extragalactic sources, evolved stars, nebular knots, and even unassociated foreground/background YSOs. Applying our methodology consistently across 18 of the target complexes, we produce the MYStIX IRE Source (MIRES) Catalog comprising 20,719 sources, including 8686 probable stellar members of the MYStIX target complexes. We also classify the SEDs of 9365 IR counterparts to MYStIX X-ray sources to assist the first pathway, the identification of X-ray-detected stellar members. The MIRES Catalog provides a foundation for follow-up studies of diverse phenomena related to massive star cluster formation, including protostellar outflows, circumstellar disks, and sequential star formation triggered by massive star feedback processes. © 2013. The American Astronomical Society. All rights reserved.M.S.P. was supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-0901646 during the main analysis phase of this project. The MIRES Catalog is based on observations from the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory (California Institute of Technology) under contract with NASA. This publication makes use of data products from the Two Micron All-Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by NASA and the NSF. This work is based in part on data obtained as part of the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey and in part by data obtained in UKIRT Director's Discretionary Time. UKIRT is operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the U.K. The MYStIX project is supported at Penn State by NASA grant NNX09AC74G, NSF grant AST-0908038, and the Chandra ACIS Team contract SV4-74018 (PIs: G. Garmire and L. Townsley), issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060

    Comparing power hitting kinematics between skilled male and female cricket batters

    Get PDF
    Organismic, task, and environmental constraints are known to differ between skilled male and female cricket batters during power hitting tasks. Despite these influences, the techniques used in such tasks have only been investigated in male cricket batters. This study compared power hitting kinematics between 15 male and 15 female batters ranging from university to international standard. General linear models were used to assess the effect of gender on kinematic parameters describing technique, with height and body mass as covariates. Male batters generated greater maximum bat speeds, ball launch speeds, and ball carry distances than female batters on average. Male batters had greater pelvis-thorax separation in the transverse plane at the commencement of the downswing (β = 1.14; p = 0.030) and extended their lead elbows more during the downswing (β = 1.28; p = 0.008) compared to female batters. The hypothesised effect of gender on the magnitude of wrist uncocking during the downswing was not observed (β = −0.14; p = 0.819). The causes of these differences are likely to be multi-factorial, involving aspects relating to the individual players, their history of training experiences and coaching practices, and the task of power hitting in male or female cricket

    Decision-making in percutaneous coronary intervention: a survey

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Few researchers have examined the perceptions of physicians referring cases for angiography regarding the degree to which collaboration occurs during percutaneous coronary intervention (PCI) decision-making. We sought to determine perceptions of physicians concerning their involvement in PCI decisions in cases they had referred to the cardiac catheterization laboratory at a major academic medical center.</p> <p>Methods</p> <p>An anonymous survey was mailed to internal medicine faculty members at a major academic medical center. The survey elicited whether responders perceived that they were included in decision-making regarding PCI, and whether they considered such collaboration to be the best process of decision-making.</p> <p>Results</p> <p>Of the 378 surveys mailed, 35% (133) were returned. Among responding non-cardiologists, 89% indicated that in most cases, PCI decisions were made solely by the interventionalist at the time of the angiogram. Among cardiologists, 92% indicated that they discussed the findings with the interventionalist prior to any PCI decisions. When asked what they considered the best process by which PCI decisions are made, 66% of non-cardiologists answered that they would prefer collaboration between either themselves or a non-interventional cardiologist and the interventionalist. Among cardiologists, 95% agreed that a collaborative approach is best.</p> <p>Conclusion</p> <p>Both non-cardiologists and cardiologists felt that involving another decision-maker, either the referring physician or a non-interventional cardiologist, would be the best way to make PCI decisions. Among cardiologists, there was more concordance between what they believed was the best process for making decisions regarding PCI and what they perceived to be the actual process.</p

    Immunomodulation by imiquimod in patients with high-risk primary melanoma.

    Get PDF
    Imiquimod is a synthetic Toll-like receptor 7 (TLR7) agonist approved for the topical treatment of actinic keratoses, superficial basal cell carcinoma, and genital warts. Imiquimod leads to an 80-100% cure rate of lentigo maligna; however, studies of invasive melanoma are lacking. We conducted a pilot study to characterize the local, regional, and systemic immune responses induced by imiquimod in patients with high-risk melanoma. After treatment of the primary melanoma biopsy site with placebo or imiquimod cream, we measured immune responses in the treated skin, sentinel lymph nodes (SLNs), and peripheral blood. Treatment of primary melanomas with 5% imiquimod cream was associated with an increase in both CD4+ and CD8+ T cells in the skin, and CD4+ T cells in the SLN. Most of the CD8+ T cells in the skin were CD25 negative. We could not detect any increases in CD8+ T cells specifically recognizing HLA-A(*)0201-restricted melanoma epitopes in the peripheral blood. The findings from this small pilot study demonstrate that topical imiquimod treatment results in enhanced local and regional T-cell numbers in both the skin and SLN. Further research into TLR7 immunomodulating pathways as a basis for effective immunotherapy against melanoma in conjunction with surgery is warranted

    Response of bone turnover markers to raloxifene treatment in postmenopausal women with osteopenia.

    Get PDF
    Introduction: The change in bone turnover markers (BTM) in response to osteoporosis therapy can be assessed by a decrease beyond the least significant change (LSC) or below the mean of the reference interval (RI). We compared the performance of these two approaches in women treated with raloxifene. Methods: Fifty postmenopausal osteopenic women, (age 51-72y) were randomised to raloxifene or no treatment for 2 years. Blood samples were collected for the measurement of BTM. The LSC for each marker was calculated from the untreated women and the RI obtained from healthy premenopausal women (age 35-40y). Bone mineral density (BMD) was measured at the spine and hip. Results: There was a decrease in BTM in response to raloxifene treatment; percentage change at 12 weeks, CTX -39% (95% CI -48 to -28) and PINP -32% (95% CI -40 to -23) P<0.001. The proportion of women classified as responding to treatment using LSC at 12 weeks was: CTX 38%, PINP 52%, at 48 weeks CTX 60%, PINP 65%. For the RI approach; at 12 weeks CTX and PINP 38%, at 48 weeks CTX 40%, PINP 45%. There was a significant difference in the change in spine BMD in the raloxifene treated group compared to the no-treatment group at week 48; difference 0.031 g/cm2, (95% CI 0.016 to 0.046, P<0.001). Conclusions: The two approaches identified women that reached the target for treatment using BTM. Both LSC and RI criteria appear useful in identifying treatment response but the two approaches do not fully overlap and may be complementary
    • …
    corecore