587 research outputs found

    The bactericidal activity of moxifloxacin in patients with pulmonary tuberculosis

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    Patients in whom acid-fast bacilli smear-positive pulmonary tuberculosis was newly diagnosed were randomized to receive 400 mg moxifloxacin, 300 mg isonaizid, or 600 mg rifampin daily for 5 days. Sixteen-hour overnight sputa collections were made for the 2 days before and for 5 days of monotherapy. Bactericidal activity was estimated by the time taken to kill 50% of viable bacilli (vt(50)) and the fall in sputum viable count during the first 2 days designated as the early bactericidal activity (EBA). The mean vt(50) of moxifloxacin was 0.88 days (95% confidence interval [Cl], 0.43-1.33 days) and the mean EBA was 0.53 (95% CI 0.28-0.79). For the isoniazid group, the mean vt(50) was 0.46 days (95% Cl, 0.31-0.61 days) and the mean EBA was 0.77 (95% Cl, 0.54-1.00). For rifampin, the mean vt(50) was 0.71 days (95% Cl, 0.48-0.95 days) and the mean EBA was 0.28 (95% Cl, 0.15-0.41). Using the EBA method, isoniazid was significantly more active than rifampin (p < 0.01) but not moxifloxacin. Using the vt(50) method, isoniazid was more active than both rifampin and moxifloxacin (p = 0.03). Moxifloxacin has an activity similar to rifampin in human subjects with pulmonary tuberculosis, suggesting that it should undergo further assessment as part of a short course regimen for the treatment of drug-susceptible tuberculosis

    Quantitative Spectroscopy of Supernovae for Dark Energy Studies

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    Detailed quantitative spectroscopy of Type Ia supernovae (SNe~Ia) provides crucial information needed to minimize systematic effects in both ongoing SNe Ia observational programs such as the Nearby Supernova Factory, ESSENCE, and the SuperNova Legacy Survey (SNLS) and in proposed JDEM missions such as SNAP, JEDI, and DESTINY. Quantitative spectroscopy is mandatory to quantify and understand the observational strategy of comparing ``like versus like''. It allows us to explore evolutionary effects, from variations in progenitor metallicity to variations in progenitor age, to variations in dust with cosmological epoch. It also allows us to interpret and quantify the effects of asphericity, as well as different amounts of mixing in the thermonuclear explosion.Comment: White paper submitted to the Dark Energy Task Force, 13 pages, 5 figure

    Multi-layered Spectral Formation in SNe Ia Around Maximum Light

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    We use the radiative transfer code PHOENIX to study the line formation of the wavelength region 5000-7000 Angstroms. This is the region where the SNe Ia defining Si II feature occurs. This region is important since the ratio of the two nearby silicon lines has been shown to correlate with the absolute blue magnitude. We use a grid of LTE synthetic spectral models to investigate the formation of line features in the spectra of SNe Ia. By isolating the main contributors to the spectral formation we show that the ions that drive the spectral ratio are Fe III, Fe II, Si II, and S II. While the first two strongly dominate the flux transfer, the latter two form in the same physical region inside of the supernova. We also show that the naive blackbody that one would derive from a fit to the observed spectrum is far different than the true underlying continuum.Comment: 35 pages, 15 figures, ApJ (2008) 684 in pres

    Effects of Age and Gender on Physical Performance

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    Our purpose was to examine the effects of age and gender on physical performance. We assessed a one-hour swimming performance and participation of 4,271 presumably healthy men and women, aged 19–91 years, from the 2001–2003 United States Masters Swimming long-distance (1 h) national competition. The decline in performance with increasing age was found to be quadratic rather than linear. The equation which best fit variation in 1 h swimming distance in meters (m) according to variations in age in years (y) in men was: distance (m) = 4058 + 2.18 age−0.29 age (http://www.acsmmsse.org/pt/re/msse/positionstandards.htm;jsessionid=DiRVACC7YS3mq27s5kV3vwpEVSokmmD1ZJLC7pdnol3KcfoSu0t!1096311956!-949856145!9001!-1), with the same equation for women except that 380 m needed to be subtracted from the calculated value at all ages (about a 10% difference). There was a large overlap in performance between men and women. The overall mean decline in performance with age was about 50% and was parallel in men and women. The mean difference in distance for a 1-year increment in age was −9.7 m at 21 y of age, −21.3 m at 40 y, and −44.5 m at 80 y. Far greater declines of about 96% in numbers participating with advanced age (80 y and over, 4% of peak numbers) were observed than in the 40–49 y age group. In conclusion, the declines in performance were parallel in men and women at all ages, and the 1-year age-related declines in performance were about twice as great at 40 y and more than four-times as great at 80 y than at 20 y of age, with even greater age-related declines in participation being noted for both men and women

    Time-dependent radiative transfer with PHOENIX

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    Aims. We present first results and tests of a time-dependent extension to the general purpose model atmosphere code PHOENIX. We aim to produce light curves and spectra of hydro models for all types of supernovae. Methods. We extend our model atmosphere code PHOENIX to solve time-dependent non-grey, NLTE, radiative transfer in a special relativistic framework. A simple hydrodynamics solver was implemented to keep track of the energy conservation of the atmosphere during free expansion. Results. The correct operation of the new additions to PHOENIX were verified in test calculations. Conclusions. We have shown the correct operation of our extension to time-dependent radiative transfer and will be able to calculate supernova light curves and spectra in future work.Comment: 7 pages, 12 figure

    State-Dependent Computation Using Coupled Recurrent Networks

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    Although conditional branching between possible behavioral states is a hallmark of intelligent behavior, very little is known about the neuronal mechanisms that support this processing. In a step toward solving this problem, we demonstrate by theoretical analysis and simulation how networks of richly interconnected neurons, such as those observed in the superficial layers of the neocortex, can embed reliable, robust finite state machines. We show how a multistable neuronal network containing a number of states can be created very simply by coupling two recurrent networks whose synaptic weights have been configured for soft winner-take-all (sWTA) performance. These two sWTAs have simple, homogeneous, locally recurrent connectivity except for a small fraction of recurrent cross-connections between them, which are used to embed the required states. This coupling between the maps allows the network to continue to express the current state even after the input that elicited that state iswithdrawn. In addition, a small number of transition neurons implement the necessary input-driven transitions between the embedded states. We provide simple rules to systematically design and construct neuronal state machines of this kind. The significance of our finding is that it offers a method whereby the cortex could construct networks supporting a broad range of sophisticated processing by applying only small specializations to the same generic neuronal circuit

    Evolving Monolithic Robot Controllers through Incremental Shaping

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    Evolutionary robotics has been shown to be an effective technique for generating robot behaviors that are difficult to derive analytically from the robot’s mechanics and task environment. Moreover, augmenting evolutionary algorithms with environmental scaffolding via an incremental shaping method makes it possible to evolve controllers for complex tasks that would otherwise be infeasible. In this paper we present a summary of two recent publications in the evolutionary robotics literature demonstrating how these methods can be used to evolve robot controllers for non-trivial tasks, what the obstacles are in evolving controllers in this way, and present a novel research question that can be investigated under this framework

    Environmental Influence on the Evolution of Morphological Complexity in Machines

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    Whether, when, how, and why increased complexity evolves in biological populations is a longstanding open question. In this work we combine a recently developed method for evolving virtual organisms with an information-theoretic metric of morphological complexity in order to investigate how the complexity of morphologies, which are evolved for locomotion, varies across different environments. We first demonstrate that selection for locomotion results in the evolution of organisms with morphologies that increase in complexity over evolutionary time beyond what would be expected due to random chance. This provides evidence that the increase in complexity observed is a result of a driven rather than a passive trend. In subsequent experiments we demonstrate that morphologies having greater complexity evolve in complex environments, when compared to a simple environment when a cost of complexity is imposed. This suggests that in some niches, evolution may act to complexify the body plans of organisms while in other niches selection favors simpler body plans

    Spectral Modeling of SNe Ia Near Maximum Light: Probing the Characteristics of Hydro Models

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    We have performed detailed NLTE spectral synthesis modeling of 2 types of 1-D hydro models: the very highly parameterized deflagration model W7, and two delayed detonation models. We find that overall both models do about equally well at fitting well observed SNe Ia near to maximum light. However, the Si II 6150 feature of W7 is systematically too fast, whereas for the delayed detonation models it is also somewhat too fast, but significantly better than that of W7. We find that a parameterized mixed model does the best job of reproducing the Si II 6150 line near maximum light and we study the differences in the models that lead to better fits to normal SNe Ia. We discuss what is required of a hydro model to fit the spectra of observed SNe Ia near maximum light.Comment: 29 pages, 14 figures, ApJ, in pres

    The DICE calibration project: design, characterization, and first results

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    We describe the design, operation, and first results of a photometric calibration project, called DICE (Direct Illumination Calibration Experiment), aiming at achieving precise instrumental calibration of optical telescopes. The heart of DICE is an illumination device composed of 24 narrow-spectrum, high-intensity, light-emitting diodes (LED) chosen to cover the ultraviolet-to-near-infrared spectral range. It implements a point-like source placed at a finite distance from the telescope entrance pupil, yielding a flat field illumination that covers the entire field of view of the imager. The purpose of this system is to perform a lightweight routine monitoring of the imager passbands with a precision better than 5 per-mil on the relative passband normalisations and about 3{\AA} on the filter cutoff positions. The light source is calibrated on a spectrophotometric bench. As our fundamental metrology standard, we use a photodiode calibrated at NIST. The radiant intensity of each beam is mapped, and spectra are measured for each LED. All measurements are conducted at temperatures ranging from 0{\deg}C to 25{\deg}C in order to study the temperature dependence of the system. The photometric and spectroscopic measurements are combined into a model that predicts the spectral intensity of the source as a function of temperature. We find that the calibration beams are stable at the 10410^{-4} level -- after taking the slight temperature dependence of the LED emission properties into account. We show that the spectral intensity of the source can be characterised with a precision of 3{\AA} in wavelength. In flux, we reach an accuracy of about 0.2-0.5% depending on how we understand the off-diagonal terms of the error budget affecting the calibration of the NIST photodiode. With a routine 60-mn calibration program, the apparatus is able to constrain the passbands at the targeted precision levels.Comment: 25 pages, 27 figures, accepted for publication in A&
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