5,063 research outputs found
NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results
The NEOWISE dataset offers the opportunity to study the variations in albedo
for asteroid classification schemes based on visible and near-infrared
observations for a large sample of minor planets. We have determined the
albedos for nearly 1900 asteroids classified by the Tholen, Bus and Bus-DeMeo
taxonomic classification schemes. We find that the S-complex spans a broad
range of bright albedos, partially overlapping the low albedo C-complex at
small sizes. As expected, the X-complex covers a wide range of albedos. The
multi-wavelength infrared coverage provided by NEOWISE allows determination of
the reflectivity at 3.4 and 4.6 m relative to the visible albedo. The
direct computation of the reflectivity at 3.4 and 4.6 m enables a new
means of comparing the various taxonomic classes. Although C, B, D and T
asteroids all have similarly low visible albedos, the D and T types can be
distinguished from the C and B types by examining their relative reflectance at
3.4 and 4.6 m. All of the albedo distributions are strongly affected by
selection biases against small, low albedo objects, as all objects selected for
taxonomic classification were chosen according to their visible light
brightness. Due to these strong selection biases, we are unable to determine
whether or not there are correlations between size, albedo and space
weathering. We argue that the current set of classified asteroids makes any
such correlations difficult to verify. A sample of taxonomically classified
asteroids drawn without significant albedo bias is needed in order to perform
such an analysis.Comment: Accepted to Ap
Towards distributed diagnosis of the Tennessee Eastman process benchmark
A distributed hybrid strategy is outlined for the isolation of faults and disturbances in the Tennessee Eastman process, which would build on existing structures for distributed control systems, so should be easy to implement, be cheap and be widely applicable. The main emphasis in the paper is on one component of the strategy, a steady-state-based approach. Results obtained by applying this approach are presented and knowledge limitations are discussed. In particular a way in which a knowledge-base might evolve to improve isolation capabilities is suggested and the role of the operator is briefly discussed
Local Skin Inflammation in Cutaneous Leishmaniasis as a Source of Variable Pharmacokinetics and Therapeutic Efficacy of Liposomal Amphotericin B.
Disfiguring skin lesions caused by several species of the Leishmania parasite characterize cutaneous leishmaniasis (CL). Successful treatment of CL with intravenous (i.v.) liposomal amphotericin B (LAmB) relies on the presence of adequate antibiotic concentrations at the dermal site of infection within the inflamed skin. Here, we have investigated the impact of the local skin inflammation on the pharmacokinetics (PK) and efficacy of LAmB in two murine models of localized CL (Leishmania major and Leishmania mexicana) at three different stages of disease (papule, initial nodule, and established nodule). Twenty-four hours after the administration of one 25 mg/kg of body weight LAmB (i.v.) dose to infected BALB/c mice (n = 5), drug accumulation in the skin was found to be dependent on the causative parasite species (L. major > L. mexicana) and the disease stage (papule > initial nodule > established nodule > healthy skin). Elevated tissue drug levels were associated with increased vascular permeability (Evans blue assay) and macrophage infiltration (histomorphometry) in the infected skin, two pathophysiological parameters linked to tissue inflammation. After identical treatment of CL in the two models with 5 × 25 mg/kg LAmB (i.v.), intralesional drug concentrations and reductions in lesion size and parasite load (quantitative PCR [qPCR]) were all ≥2-fold higher for L. major than for L. mexicana In conclusion, drug penetration of LAmB into CL skin lesions could depend on the disease stage and the causative Leishmania species due to the influence of local tissue inflammation
Upgrade of Beam Energy Measurement System at BEPC-II
The beam energy measurement system is of great importance and profit for both
BEPC-II accelerator and BES-III detector. The system is based on measuring the
energies of Compton back-scattered photons. Many advanced techniques and
precise instruments are employed to realize the highly accurate measurement of
positron/electron beam energy. During five year's running period, in order to
meet the requirement of data taking and improve the capacity of measurement
itself, the upgradation of system is continued, which involve the component
reformation of laser and optics subsystem, replacement of view-port of the
laser to vacuum insertion subsystem, the purchase of electric cooling system
for high purity germanium detector, and the improvement of data acquisition and
processing subsystem. The upgrading of system guarantees the smooth and
efficient measuring of beam energy at BEPC-II and accommodates the accurate
offline energy values for further physics analysis at BES-III.Comment: 10 pages, 9 figures. Submitted to Chinese Physics
Dynamical Symmetry and Quantum Information Processing with Electromagnetically Induced Transparency
We study in detail the interesting dynamical symmetry and its applications in
various atomic systems with electromagnetically induced transparency (EIT) in
this paper. By discovering the symmetrical Lie group of various atomic systems,
such as single-atomic-ensemble composed of complex -level atoms, and
-atomic-ensemble and even multi-atomic-ensemble system composed of of
-level atoms etc., one can obtain the general definition of dark-state
polaritons (DSPs), and then the dark-states of these different systems. The
symmetrical properties of the multi-level system and multi-atomic-ensemble
system are shown to be dependent on some characteristic parameters of the EIT
system. Furthermore, a controllable scheme to generate quantum entanglement
between lights or atoms via quantized DSPs theory is discussed and the
robustness of this scheme is analyzed by confirming the validity of adiabatic
passage conditions in this paper.Comment: 14pages, 2figures, Phys. Lett. A, In prin
Cloning and sequence analysis of cDNAs encoding the cytosolic precursors of subunits GapA and GapB of chloroplast glyceraldehyde-3-phosphate dehydrogenase from pea and spinach
Chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is composed of two different subunits, GapA and GapB. cDNA clones containing the entire coding sequences of the cytosolic precursors for GapA from pea and for GapB from pea and spinach have been identified, sequenced and the derived amino acid sequences have been compared to the corresponding sequences from tobacco, maize and mustard. These comparisons show that GapB differs from GapA in about 20% of its amino acid residues and by the presence of a flexible and negatively charged C-terminal extension, possibly responsible for the observed association of the enzyme with chloroplast envelopes in vitro. This C-terminal extension (29 or 30 residues) may be susceptible to proteolytic cleavage thereby leading to a conversion of chloroplast GAPDH isoenzyme I into isoenzyme II. Evolutionary rate comparisons at the amino acid sequence level show that chloroplast GapA and GapB evolve roughly two-fold slower than their cytosolic counterpart GapC. GapA and GapB transit peptides evolve about 10 times faster than the corresponding mature subunits. They are relatively long (68 and 83 residues for pea GapA and spinach GapB respectively) and share a similar amino acid framework with other chloroplast transit peptides
Video-tracking and On-plant Tests Show Cry1Ab Resistance Influences Behavior and Survival of Neonate Ostrinia nubilalis Following Exposure to Bt Maize
To examine how resistance to Bacillus thuringiensis (Bt) toxins influences movement and survival of European corn borer (Ostrinia nubilalis [Hübner]) neonates, the responses of Cry1Ab-resistant , -susceptible, and hybrid (F1) larvae were examined using two different techniques. First, using an automated video-tracking system, aspects of O. nubilalis movement were quantified in the presence of artificial diet incorporating 50% non-Bt or insect-resistant Cry1Ab maize tissue. Second, O. nubilalis dispersal and survival were measured 48–72 h after hatching on a Cry1Ab maize plant surrounded by two non-Bt maize plants. Video tracking indicated the presence of Cry1Ab tissue increased the total distance moved (m), time moving (%), and time away from the diet (%) for O. nubilalis while decreasing meander (degrees/cm). However, resistant larvae showed reduced movement and increased meander (≈localized searching) relative to susceptible or hybrid larvae on diet incorporating Cry1Ab tissue. Conversely, when placed onto Cry1Ab maize plants, resistant larvae were more likely than susceptible O. nubilalis to disperse onto adjacent non-Bt plants. The difference in on-plant dispersal seems to reflect greater survival after toxin exposure for resistant larvae rather than increased activity. These results suggest that simplified ‘Petri dish’ tests may not be predictive of larval movement among non-Bt and insect-resistant Bt maize plants. Because models of O. nubilalis resistance evolution incorporate various movement and survival parameters, improved data for on-plant behavior and survival of Bt- resistant , -susceptible, and hybrid larvae should help preserve the efficacy of transgenic insect-resistant maize
The Kennicutt-Schmidt Star Formation Relation at z~2
Recent observations of excited CO emission lines from z~2 disc galaxies have
shed light on the Kennicutt-Schmidt relation at high-z via observed SFR-CO
(J=2-1) and (J=3-2) relations. Here, we describe a novel methodology for
utilising these observations of high-excitation CO to derive the underlying
Schmidt (SFR-rho^N) relationship. To do this requires an understanding of the
potential effects of differential CO excitation with SFR. If the most heavily
star-forming galaxies have a larger fraction of their gas in highly excited CO
states than the lower SFR galaxies, then the observed molecular SFR-CO^alpha
index, alpha, will be less than the underlying (volumetric) Schmidt index, N.
Utilising a combination of SPH models of galaxy evolution and molecular line
radiative transfer, we present the first calculations of CO excitation in z~2
disc galaxies with the aim of developing a mapping between various observed
SFR-CO relationships and the underlying Schmidt relation. We find that even in
relatively luminous z~2 discs, differential excitation does indeed exist,
resulting in alpha < N for highly excited CO lines. This means that an observed
(e.g.) SFR-CO (J=3-2) relation does not map linearly to SFR-H2 relation. We
utilise our model results to provide a mapping from alpha to N for the range of
Schmidt indices N=1-2. By comparing to recent observational surveys, we find
that the observed SFR-CO (J=2-1) and SFR-CO (J=3-2) relations suggest that an
underlying SFR rho^1.5 relation describes z~2 disc galaxies.Comment: Accepted by MNRAS, a few figure additions in response to referee
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Interaction of perceptual grouping and crossmodal temporal capture in tactile apparent-motion
Previous studies have shown that in tasks requiring participants to report the direction of apparent motion, task-irrelevant mono-beeps can "capture'' visual motion perception when the beeps occur temporally close to the visual stimuli. However, the contributions of the relative timing of multimodal events and the event structure, modulating uni- and/or crossmodal perceptual grouping, remain unclear. To examine this question and extend the investigation to the tactile modality, the current experiments presented tactile two-tap apparent-motion streams, with an SOA of 400 ms between successive, left-/right-hand middle-finger taps, accompanied by task-irrelevant, non-spatial auditory stimuli. The streams were shown for 90 seconds, and participants' task was to continuously report the perceived (left-or rightward) direction of tactile motion. In Experiment 1, each tactile stimulus was paired with an auditory beep, though odd-numbered taps were paired with an asynchronous beep, with audiotactile SOAs ranging from -75 ms to 75 ms. Perceived direction of tactile motion varied systematically with audiotactile SOA, indicative of a temporal-capture effect. In Experiment 2, two audiotactile SOAs-one short (75 ms), one long (325 ms)-were compared. The long-SOA condition preserved the crossmodal event structure (so the temporal-capture dynamics should have been similar to that in Experiment 1), but both beeps now occurred temporally close to the taps on one side (even-numbered taps). The two SOAs were found to produce opposite modulations of apparent motion, indicative of an influence of crossmodal grouping. In Experiment 3, only odd-numbered, but not even-numbered, taps were paired with auditory beeps. This abolished the temporal-capture effect and, instead, a dominant percept of apparent motion from the audiotactile side to the tactile-only side was observed independently of the SOA variation. These findings suggest that asymmetric crossmodal grouping leads to an attentional modulation of apparent motion, which inhibits crossmodal temporal-capture effects
A self-validating control system based approach to plant fault detection and diagnosis
An approach is proposed in which fault detection and diagnosis (FDD) tasks are distributed to separate FDD modules associated with each control system located throughout a plant. Intended specifically for those control systems that inherently eliminate steady state error, it is modular, steady state based, requires very little process specific information and therefore should be attractive to control systems implementers who seek economies of scale. The approach is applicable to virtually all types of process plant, whether they are open loop stable or not, have a type or class number of zero or not and so on. Based on qualitative reasoning, the approach is founded on the application of control systems theory to single and cascade control systems with integral action. This results in the derivation of cause-effect knowledge and fault isolation procedures that take into account factors like interactions between control systems, and the availability of non-control-loop-based sensors
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