384 research outputs found

    Unmanned Vehicle Systems & Operations on Air, Sea, Land

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    Unmanned Vehicle Systems & Operations On Air, Sea, Land is our fourth textbook in a series covering the world of Unmanned Aircraft Systems (UAS) and Counter Unmanned Aircraft Systems (CUAS). (Nichols R. K., 2018) (Nichols R. K., et al., 2019) (Nichols R. , et al., 2020)The authors have expanded their purview beyond UAS / CUAS systems. Our title shows our concern for growth and unique cyber security unmanned vehicle technology and operations for unmanned vehicles in all theaters: Air, Sea and Land – especially maritime cybersecurity and China proliferation issues. Topics include: Information Advances, Remote ID, and Extreme Persistence ISR; Unmanned Aerial Vehicles & How They Can Augment Mesonet Weather Tower Data Collection; Tour de Drones for the Discerning Palate; Underwater Autonomous Navigation & other UUV Advances; Autonomous Maritime Asymmetric Systems; UUV Integrated Autonomous Missions & Drone Management; Principles of Naval Architecture Applied to UUV’s; Unmanned Logistics Operating Safely and Efficiently Across Multiple Domains; Chinese Advances in Stealth UAV Penetration Path Planning in Combat Environment; UAS, the Fourth Amendment and Privacy; UV & Disinformation / Misinformation Channels; Chinese UAS Proliferation along New Silk Road Sea / Land Routes; Automaton, AI, Law, Ethics, Crossing the Machine – Human Barrier and Maritime Cybersecurity.Unmanned Vehicle Systems are an integral part of the US national critical infrastructure The authors have endeavored to bring a breadth and quality of information to the reader that is unparalleled in the unclassified sphere. Unmanned Vehicle (UV) Systems & Operations On Air, Sea, Land discusses state-of-the-art technology / issues facing U.S. UV system researchers / designers / manufacturers / testers. We trust our newest look at Unmanned Vehicles in Air, Sea, and Land will enrich our students and readers understanding of the purview of this wonderful technology we call UV.https://newprairiepress.org/ebooks/1035/thumbnail.jp

    Treatment patterns and overall survival outcomes among patients aged 80 yr or older with high-risk prostate cancer

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    BACKGROUND: Elderly patients diagnosed with high-risk prostate cancer (PCa) present a therapeutic dilemma of balancing treatment of a potentially lethal malignancy with overtreatment of a cancer that may not threaten life expectancy. OBJECTIVE: To investigate treatment patterns and overall survival outcomes in this group of patients. DESIGN SETTING AND PARTICIPANTS: A retrospective cohort study was conducted. We queried the National Cancer Database for high-risk PCa in patients aged 80 yr or older diagnosed during 2004-2016. INTERVENTION: Eligible patients underwent no treatment following biopsy (ie, observation), androgen deprivation therapy (ADT) alone, radiation therapy (RT) alone, RT + ADT, or surgery. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Kaplan-Meier, log rank, and multivariate Cox proportional hazard regression was performed to compare overall survival (OS). RESULTS AND LIMITATIONS: A total of 19 920 men were eligible for analysis, and the most common treatment approach was RT + ADT (7401 patients; 37.2%). Observation and ADT alone declined over time (59.3% in 2004 vs 47.5% in 2016). There was no observed difference in OS between observation and ADT alone (adjusted hazard ratio [HR] 1.04, 95% confidence interval [CI], 0.99-1.09; CONCLUSIONS: This analysis demonstrates that the use of definitive local therapy, including surgery or RT ± ADT, is increasing and is associated with a 50% reduction in overall mortality compared with observation or ADT alone. While prospective validation is warranted, elderly men with high-risk disease eligible for definitive management should be counseled on the risks, including a possible compromise in OS, with deferring definitive management. PATIENT SUMMARY: Elderly men are more often diagnosed with higher-risk prostate cancer but are less likely to receive curative treatment options than younger men. Our analysis demonstrates that for men ≥80 yr of age with high-risk prostate cancer, definitive local therapy, including surgery or radiation therapy and/or androgen deprivation therapy, is associated with a 50% reduction in overall mortality compared with observation or androgen deprivation therapy alone. We therefore recommend that life expectancy (ie, physiologic age) be taken into account, over chronologic age, and that elderly men with good life expectancy (eg, \u3e5 yr; minimal comorbidity) should be offered definitive, life-prolonging therapy

    Exotic Differentiable Structures and General Relativity

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    We review recent developments in differential topology with special concern for their possible significance to physical theories, especially general relativity. In particular we are concerned here with the discovery of the existence of non-standard (``fake'' or ``exotic'') differentiable structures on topologically simple manifolds such as S7S^7, \R and S3Ă—R1.S^3\times {\bf R^1}. Because of the technical difficulties involved in the smooth case, we begin with an easily understood toy example looking at the role which the choice of complex structures plays in the formulation of two-dimensional vacuum electrostatics. We then briefly review the mathematical formalisms involved with differentiable structures on topological manifolds, diffeomorphisms and their significance for physics. We summarize the important work of Milnor, Freedman, Donaldson, and others in developing exotic differentiable structures on well known topological manifolds. Finally, we discuss some of the geometric implications of these results and propose some conjectures on possible physical implications of these new manifolds which have never before been considered as physical models.Comment: 11 pages, LaTe

    Early-universe constraints on a time-varying fine structure constant

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    Higher-dimensional theories have the remarkable feature of predicting a time (and hence redshift) dependence of the `fundamental' four dimensional constants on cosmological timescales. In this paper we update the bounds on a possible variation of the fine structure constant alpha at the time of BBN (z =10^10) and CMB (z=10^3). Using the recently-released high-resolution CMB anisotropy data and the latest estimates of primordial abundances of 4He and D, we do not find evidence for a varying alpha at more than one-sigma level at either epoch.Comment: 5 pages, 1 figure, minor misprints corrected, references added. The analysis has been updated using new BOOMERanG and DASI data on CMB anisotrop

    The Host Galaxy of FRB 20171020A Revisited

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    The putative host galaxy of FRB 20171020A was first identified as ESO 601-G036 in 2018, but as no repeat bursts have been detected, direct confirmation of the host remains elusive. In light of recent developments in the field, we re-examine this host and determine a new association confidence level of 98%. At 37 Mpc, this makes ESO 601-G036 the third closest FRB host galaxy to be identified to date and the closest to host an apparently non-repeating FRB (with an estimated repetition rate limit of < 0.011 bursts per day above 10 erg). Due to its close distance, we are able to perform detailed multi-wavelength analysis on the ESO 601-G036 system. Follow-up observations confirm ESO 601-G036 to be a typical star-forming galaxy with HI and stellar masses of log(M_HI/M_sol) ~ 9.2 and log(M_*/M_sol) = 8.64, and a star formation rate of SFR = 0.09 +/- 0.01 M_sol/yr. We detect, for the first time, a diffuse gaseous tail (log(M_HI/M_sol) ~ 8.3) extending to the south-west that suggests recent interactions, likely with the confirmed nearby companion ESO 601-G037. ESO 601-G037 is a stellar shred located to the south of ESO 601-G036 that has an arc-like morphology, is about an order of magnitude less massive, and has a lower gas metallicity that is indicative of a younger stellar population. The properties of the ESO 601-G036 system indicate an ongoing minor merger event, which is affecting the overall gaseous component of the system and the stars within ESO 601-G037. Such activity is consistent with current FRB progenitor models involving magnetars and the signs of recent interactions in other nearby FRB host galaxies.Comment: 16 pages, 9 figures, accepted for publication in PAS

    The On-Orbit Performance of the Galaxy Evolution Explorer

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    We report the first year on-orbit performance results for the Galaxy Evolution Explorer (GALEX), a NASA Small Explorer that is performing a survey of the sky in two ultraviolet bands. The instrument comprises a 50 cm diameter modified Ritchey-Chretien telescope with a 1.25 degree field of view, selectable imaging and objective grism spectroscopic modes, and an innovative optical system with a thin-film multilayer dichroic beam splitter that enables simultaneous imaging by a pair of photon counting, microchannel plate, delay line readout detectors. Initial measurements demonstrate that GALEX is performing well, meeting its requirements for resolution, efficiency, astrometry, bandpass definition and survey sensitivity.Comment: This paper will be published as part of the Galaxy Evolution Explorer (GALEX) Astrophysical Journal Letters Special Issu
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