7,635 research outputs found

    Hairy binary black holes in Einstein-Maxwell-dilaton theory and their effective-one-body description

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    In General Relativity and many modified theories of gravity, isolated black holes (BHs) cannot source massless scalar fields. Einstein-Maxwell-dilaton (EMd) theory is an exception: through couplings both to electromagnetism and (non-minimally) to gravity, a massless scalar field can be generated by an electrically charged BH. In this work, we analytically model the dynamics of binaries comprised of such scalar-charged ("hairy") BHs. While BHs are not expected to have substantial electric charge within the Standard Model of particle physics, nearly-extremally charged BHs could occur in models of minicharged dark matter and dark photons. We begin by studying the test-body limit for a binary BH in EMd theory, and we argue that only very compact binaries of nearly-extremally charged BHs can manifest non-perturbative phenomena similar to those found in certain scalar-tensor theories. Then, we use the post-Newtonian approximation to study the dynamics of binary BHs with arbitrary mass ratios. We derive the equations governing the conservative and dissipative sectors of the dynamics at next-to-leading order, use our results to compute the Fourier-domain gravitational waveform in the stationary-phase approximation, and compute the number of useful cycles measurable by the Advanced LIGO detector. Finally, we construct two effective-one-body (EOB) Hamiltonians for binary BHs in EMd theory: one that reproduces the exact test-body limit and another whose construction more closely resembles similar models in General Relativity, and thus could be more easily integrated into existing EOB waveform models used in the data analysis of gravitational-wave events by the LIGO and Virgo collaborations.Comment: 36 pages, 12 figures, updated to match published versio

    Contingent task and motion planning under uncertainty for human–robot interactions

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    Manipulation planning under incomplete information is a highly challenging task for mobile manipulators. Uncertainty can be resolved by robot perception modules or using human knowledge in the execution process. Human operators can also collaborate with robots for the execution of some difficult actions or as helpers in sharing the task knowledge. In this scope, a contingent-based task and motion planning is proposed taking into account robot uncertainty and human–robot interactions, resulting a tree-shaped set of geometrically feasible plans. Different sorts of geometric reasoning processes are embedded inside the planner to cope with task constraints like detecting occluding objects when a robot needs to grasp an object. The proposal has been evaluated with different challenging scenarios in simulation and a real environment.Postprint (published version

    Multi-Layer Multi-Configuration Time-Dependent Hartree (ML-MCTDH) Approach to the Correlated Exciton-Vibrational Dynamics in the FMO Complex

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    The coupled quantum dynamics of excitonic and vibrational degrees of freedom is investigated for high-dimensional models of the Fenna-Matthews-Olson (FMO) complex. This includes a seven and an eight-site model with 518 and 592 harmonic vibrational modes, respectively. The coupling between local electronic transitions and vibrations is described within the Huang-Rhys model using parameters that are obtained by discretization of an experimental spectral density. Different pathways of excitation energy flow are analyzed in terms of the reduced one-exciton density matrix, focussing on the role of vibrational and vibronic excitation. Distinct features due to both competing time scales of vibrational and exciton motion and vibronically-assisted transfer are observed. The question of the effect of initial state preparation is addressed by comparing the case of an instantaneous Franck-Condon excitation at a single site with that of a laser field excitation.Comment: revised versio

    How migrating 0.0001% of address space saves 12% of energy in hybrid storage

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    We present a simple, operating-\ud system independent method to reduce the num-\ud ber of seek operations and consequently reduce\ud the energy consumption of a hybrid storage\ud device consisting of a hard disk and a flash\ud memory. Trace-driven simulations show that\ud migrating a tiny amount of the address space\ud (0.0001%) from disk to flash already results\ud in a significant storage energy reduction (12%)\ud at virtually no extra cost. We show that the\ud amount of energy saving depends on which part\ud of the address space is migrated, and we present\ud two indicators for this, namely sequentiality and\ud request frequency. Our simulations show that\ud both are suitable as criterion for energy-saving\ud file placement methods in hybrid storage. We\ud address potential wear problems in the flash\ud subsystem by presenting a simple way to pro-\ud long its expected lifetime.\u

    A randomised trial of an eight-week, once weekly primaquine regimen to prevent relapse of plasmodium vivax in Northwest Frontier Province, Pakistan.

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    BACKGROUND: Vivax malaria remains a major cause of morbidity in the subtropics. To undermine the stability of the disease, drugs are required that prevent relapse and provide reservoir reduction. A 14-day course of primaquine (PQ) is effective but cannot safely be used in routine practice because of its interaction with glucose-6-phosphate dehydrogenase (G6PD) deficiency for which testing is seldom available. Safe and effective use of PQ without the need for G6PD testing would be ideal. The efficacy and safety of an 8-week, once weekly PQ regimen was compared with current standard treatment (chloroquine alone) and a 14-day PQ regimen. METHODS AND PRINCIPAL FINDINGS: 200 microscopically confirmed Plasmodium vivax patients were randomly assigned to either once weekly 8-week PQ (0.75 mg/kg/week), once weekly 8-week placebo, or 14-day PQ (0.5mg/kg/day) in North West Frontier Province, Pakistan. All patients were treated with a standard chloroquine dose and tested for G6PD deficiency. Deficient patients were assigned to the 8-week PQ group. Failure was defined as any subsequent episode of vivax malaria over 11 months of observation. There were 22/71 (31.0%) failures in the placebo group and 1/55 (1.8%) and 4/75 (5.1%) failures in the 14-day and 8-week PQ groups, respectively. Adjusted odds ratios were: for 8-week PQ vs. placebo-0.05 (95%CI: 0.01-0.2, p<0.001) and for 14-day PQ vs. placebo-0.01 (95%CI: 0.002-0.1, p<0.001). Restricted analysis allowing for a post-treatment prophylactic effect confirmed that the 8-week regimen was superior to current treatment. Only one G6PD deficient patient presented. There were no serious adverse events. CONCLUSIONS: A practical radical treatment for vivax malaria is essential for control and elimination of the disease. The 8-week PQ course is more effective at preventing relapse than current treatment with chloroquine alone. Widespread use of the 8-week regimen could make an important contribution to reservoir reduction or regional elimination where G6PD testing is not available. TRIAL REGISTRATION: ClinicalTrials.gov NCT00158587

    PMK : a knowledge processing framework for autonomous robotics perception and manipulation

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    Autonomous indoor service robots are supposed to accomplish tasks, like serve a cup, which involve manipulation actions. Particularly, for complex manipulation tasks which are subject to geometric constraints, spatial information and a rich semantic knowledge about objects, types, and functionality are required, together with the way in which these objects can be manipulated. In this line, this paper presents an ontological-based reasoning framework called Perception and Manipulation Knowledge (PMK) that includes: (1) the modeling of the environment in a standardized way to provide common vocabularies for information exchange in human-robot or robot-robot collaboration, (2) a sensory module to perceive the objects in the environment and assert the ontological knowledge, (3) an evaluation-based analysis of the situation of the objects in the environment, in order to enhance the planning of manipulation tasks. The paper describes the concepts and the implementation of PMK, and presents an example demonstrating the range of information the framework can provide for autonomous robots.Peer ReviewedPostprint (published version

    Experimental and analytical comparative study of optical coefficient of fresh and frozen rat tissues

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    International audienceOptical properties of fresh and frozen tissues of rat heart, kidney, brain, liver, and muscle were measured in the 450-to 700-nm range. The total reflectance and transmittance were measured using a well-calibrated integral sphere setup. Absorption coefficient μ a and reduced scattering coefficient μ 0 s were derived from the experimental measurements using the inverse adding doubling technique. The influence of cryogenic processing on optical properties was studied. Interindividual and intraindividual variations were assessed. These new data aim at filling the lack of validated optical properties in the visible range especially in the blue-green region of particular interest for fluorescence and optogenetics preclinical studies. Furthermore, we provide a unique comparison of the optical properties of different organs obtained using the same measurement setup for fresh and frozen tissues as well as an estimate of the intraindividual and interindividual variability

    ADHD Awareness Among Medical Students

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    Background: Early recognition of attention deficit hyperactivity disorder (ADHD) is needed to prevent its psychosocial and educational consequences. We aimed to study ADHD awareness among medical students and identify correlating and contributing factors to their lack of knowledge. Methods: nbspA cross sectional study included 5th year medical students attending their pediatric rotation from September 15, 2012 until June 15, 2013 at King Abdulaziz University hospital, Jeddah, Kingdom of Saudi Arabia. A structured 25-item questionnaire was designed to examine their demographics, educational experience, and awareness questions about ADHD. Results: Of 120 approached students, 111 were included with ages ranging from 20-29 years (mean 22) and 69% being females. Most students 69 (62%) were enrolled during their pediatric rotation and 97 (87%) already completed their psychiatry course. Although most students (67%) recognized ADHD, only 13 (12%) categorized their level of knowledge as very good or excellent. Only 24% correctly recognized ADHD subtypes and 58% did not know what is the initial required management step. Only 19 students (17%) correctly recognized all ADHD features based on the DSM IV criteria with a mean correct score of 69% (standard deviation 14). No correlations were found with their age, gender, completing their pediatric/ psychiatry rotation, or specialty interests. Conclusions: Medical studentrsquos level of knowledge about ADHD needs improvement. This has to be corrected in order to improve early recognition and intervention. Increased ADHD education and exposure during pediatric/neuroscience modules are needed in our region

    Eccentric Exercise in Treatment of Patellar Tendinopathy in High Level Basketball Players. A Randomized Clinical Trial.

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    Chronic patellar tendinopathy is a common pathology in sporting population. To date, there is no agreed upon protocol as election treatment. Eccentric exercises have been used with satisfactory outcomes (3). The purpose of this trial was to compare the effects of two eccentric exercise protocols
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