393 research outputs found
The Extended Wronskian Determinant Approach and the Iterative Solutions of One-Dimensional Dirac Equation
An approximation method, namely, the Extended Wronskian Determinant Approach,
is suggested to study the one-dimensional Dirac equation. An integral equation
which can be solved by iterative procedure to find the wave functions is
established. We employ this approach to study the one-dimensional Dirac
equation with one-well potential, and give the energy levels and wave functions
up to the first order iterative approximation. For double-well potential, the
energy levels up to the first order approximation are given.Comment: 3 figures, 21 page
GP-Localize: Persistent Mobile Robot Localization using Online Sparse Gaussian Process Observation Model
Central to robot exploration and mapping is the task of persistent
localization in environmental fields characterized by spatially correlated
measurements. This paper presents a Gaussian process localization (GP-Localize)
algorithm that, in contrast to existing works, can exploit the spatially
correlated field measurements taken during a robot's exploration (instead of
relying on prior training data) for efficiently and scalably learning the GP
observation model online through our proposed novel online sparse GP. As a
result, GP-Localize is capable of achieving constant time and memory (i.e.,
independent of the size of the data) per filtering step, which demonstrates the
practical feasibility of using GPs for persistent robot localization and
autonomy. Empirical evaluation via simulated experiments with real-world
datasets and a real robot experiment shows that GP-Localize outperforms
existing GP localization algorithms.Comment: 28th AAAI Conference on Artificial Intelligence (AAAI 2014), Extended
version with proofs, 10 page
Cortical Network Response to Acupuncture and the Effect of the Hegu Point:An FNIRS study
Acupuncture is a practice of treatment based on influencing specific points on the body by inserting needles. According to traditional Chinese medicine, the aim of acupuncture treatment for pain management is to use specific acupoints to relieve excess, activate qi (or vital energy), and improve blood circulation. In this context, the Hegu point is one of the most widely-used acupoints for this purpose, and it has been linked to having an analgesic effect. However, there exists considerable debate as to its scientific validity. In this pilot study, we aim to identify the functional connectivity related to the three main types of acupuncture manipulations and also identify an analgesic effect based on the hemodynamic response as measured by functional near-infrared spectroscopy (fNIRS). The cortical response of eleven healthy subjects was obtained using fNIRS during an acupuncture procedure. A multiscale analysis based on wavelet transform coherence was employed to assess the functional connectivity of corresponding channel pairs within the left and right somatosensory region. The wavelet analysis was focused on the very-low frequency oscillations (VLFO, 0.01–0.08 Hz) and the low frequency oscillations (LFO, 0.08–0.15 Hz). A mixed model analysis of variance was used to appraise statistical differences in the wavelet domain for the different acupuncture stimuli. The hemodynamic response after the acupuncture manipulations exhibited strong activations and distinctive cortical networks in each stimulus. The results of the statistical analysis showed significant differences ( p < 0.05 ) between the tasks in both frequency bands. These results suggest the existence of different stimuli-specific cortical networks in both frequency bands and the anaesthetic effect of the Hegu point as measured by fNIRS
Analysis of Pain Hemodynamic Response Using Near-Infrared Spectroscopy (NIRS)
Despite recent advances in brain research, understanding the various signals
for pain and pain intensities in the brain cortex is still a complex task due
to temporal and spatial variations of brain hemodynamics. In this paper we have
investigated pain based on cerebral hemodynamics via near-infrared spectroscopy
(NIRS). This study presents a pain stimulation experiment that uses three
acupuncture manipulation techniques to safely induce pain in healthy subjects.
Acupuncture pain response was presented and hemodynamic pain signal analysis
showed the presence of dominant channels and their relationship among
surrounding channels, which contribute the further pain research area.Comment: 11 pages, 11 figure
Airborne dispersion of droplets during coughing: a physical model of viral transmission
The Covid-19 pandemic has focused attention on airborne transmission of
viruses. Using realistic air flow simulation, we model droplet dispersion from
coughing and study the transmission risk related to SARS-CoV-2. Although most
airborne droplets are 8-16 m in diameter, the droplets with the highest
transmission potential are, in fact, 32-40 m. Use of face masks is
therefore recommended for both personal and social protection. We found social
distancing effective at reducing transmission potential across all droplet
sizes. However, the presence of a human body 1 m away modifies the aerodynamics
so that downstream droplet dispersion is enhanced, which has implications on
safe distancing in queues. Based on median viral load, we found that an average
of 0.55 viral copies is inhaled at 1 m distance per cough. Droplet evaporation
results in significant reduction in droplet counts, but airborne transmission
remains possible even under low humidity conditions
Risk factors for in-hospital mortality after total arch procedure in patients with acute type A aortic dissection
ObjectKnowledge about the risk factors of in-hospital mortality for acute type A aortic dissection (ATAAD) patients who received total arch procedure is limited. This study aims to investigate preoperative and intraoperative risk factors of in-hospital mortality of these patients.MethodsFrom May 2014 to June 2018, 372 ATAAD patients received the total arch procedure in our institution. These patients were divided into survival and death groups, and patients` in-hospital data were retrospectively collected. Receiver operating characteristic curve analysis was adopted to determine the optimal cut-off value of continuous variables. Univariate and multivariable logistic regression analyses were used to detect independent risk factors for in-hospital mortality.ResultsA total of 321 patients were included in the survival group and 51 in the death group. Preoperative details showed that patients in the death group were older (55.4 ± 11.7 vs. 49.3 ± 12.6, P = 0.001), had more renal dysfunction (29.4% vs. 10.9%, P = 0.001) and coronary ostia dissection (29.4% vs. 12.2%, P = 0.001), and decreased left ventricular ejection fraction (LVEF) (57.5 ± 7.9% vs. 59.8 ± 7.3%, P = 0.032). Intraoperative results showed that more patients in the death group experienced concomitant coronary artery bypass grafting (35.3% vs. 15.3%, P = 0.001) with increased cardiopulmonary bypass (CPB) time (165.7 ± 39.0 vs. 149.4 ± 35.8 min, P = 0.003), cross-clamp time (98.4 ± 24.5 vs. 90.2 ± 26.9 min, P = 0.044), and red blood cell transfusion (913.7 ± 629.0 vs. 709.7 ± 686.6 ml, P = 0.047). Logistic regression analysis showed that age >55 years, renal dysfunction, CPB time >144 min, and RBC transfusion >1,300 ml were independent risk factors for in-hospital mortality in patients with ATAAD.ConclusionIn the present study, we identified that older age, preoperative renal dysfunction, long CPB time, and intraoperative massive transfusion were risk factors for in-hospital mortality in ATAAD patients with the total arch procedure
One-Dimensional Zinc Oxide Decorated Cobalt Oxide Nanospheres for Enhanced Gas-Sensing Properties
In this study, one-dimensional (1D) zinc oxide was loaded on the surface of cobalt oxide microspheres, which were assembled by single-crystalline porous nanosheets, via a simple heteroepitaxial growth process. This elaborate structure possessed an excellent transducer function from the single-crystalline feature of Co3O4 nanosheets and the receptor function from the zinc oxide nanorods. The structure of the as-prepared hybrid was confirmed via a Scanning Electron Microscope (SEM), X-ray diffraction (XRD), and a Transmission Electron Microscope (TEM). Gas-sensing tests showed that the gas-sensing properties of the as-designed hybrid were largely improved. The response was about 161 (Ra/Rg) to 100 ppm ethanol, which is 110 and 10 times higher than that of Co3O4 (Rg/Ra = 1.47) and ZnO (Ra/Rg = 15), respectively. And the as-designed ZnO/Co3O4 hybrid also showed a high selectivity to ethanol. The superior gas-sensing properties were mainly attributed to the as-designed nanostructures that contained a super transducer function and a super receptor function. The design strategy for gas-sensing materials in this work shed a new light on the exploration of high-performance gas sensors
Testing the viability of the interacting holographic dark energy model by using combined observational constraints
Using the data coming from the new 182 Gold type Ia supernova samples, the
shift parameter of the Cosmic Microwave Background given by the three-year
Wilkinson Microwave Anisotropy Probe observations, and the baryon acoustic
oscillation measurement from the Sloan Digital Sky Survey, and lookback
time measurements, we have performed a statistical joint analysis of the
interacting holographic dark energy model. Consistent parameter estimations
show us that the interacting holographic dark energy model is a viable
candidate to explain the observed acceleration of our universe.Comment: 15 pages, 9 figures, accepted for publication in JCA
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