43,991 research outputs found
Heisenberg and Modular Invariance of N=2 Conformal Field Theory
We present a theta function representation of the twisted characters for the
rational N=2 superconformal field theory, and discuss the Jacobi-form like
functional properties of these characters for a fixed central charge under the
action of a finite Heisenberg group and modular transformations.Comment: 21 pages, Latex, 1 figure; minor typos corrected--Journal versio
New Method for Numerically Solving the Chemical Potential Dependence of the Dressed Quark Propagator
Based on the rainbow approximation of Dyson-Schwinger equation and the
assumption that the inverse dressed quark propagator at finite chemical
potential is analytic in the neighborhood of , a new method for
obtaining the dressed quark propagator at finite chemical potential from
the one at zero chemical potential is developed. Using this method the dressed
quark propagator at finite chemical potential can be obtained directly from the
one at zero chemical potential without the necessity of numerically solving the
corresponding coupled integral equations by iteration methods. A comparison
with previous results is given.Comment: Revtex, 14 pages, 5 figure
Pocket2Drug: An Encoder-Decoder Deep Neural Network For The Target-Based Drug Design
Computational modeling is an essential component of modern drug discovery. One of its most important applications is to select promising drug candidates for pharmacologically relevant target proteins. Because of continuing advances in structural biology, putative binding sites for small organic molecules are being discovered in numerous proteins linked to various diseases. These valuable data offer new opportunities to build efficient computational models predicting binding molecules for target sites through the application of data mining and machine learning. In particular, deep neural networks are powerful techniques capable of learning from complex data in order to make informed drug binding predictions. In this communication, we describe Pocket2Drug, a deep graph neural network model to predict binding molecules for a given a ligand binding site. This approach first learns the conditional probability distribution of small molecules from a large dataset of pocket structures with supervised training, followed by the sampling of drug candidates from the trained model. Comprehensive benchmarking simulations show that using Pocket2Drug significantly improves the chances of finding molecules binding to target pockets compared to traditional drug selection procedures. Specifically, known binders are generated for as many as 80.5% of targets present in the testing set consisting of dissimilar data from that used to train the deep graph neural network model. Overall, Pocket2Drug is a promising computational approach to inform the discovery of novel biopharmaceuticals
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Application and research of wireless laser methane sensor in drainage pipeline monitoring
Laser methane sensor has been widely promoted and successfully applied in coal mines as a new and effective technology building on the approach of laser-based absorption detection. Compared with the traditional catalytic methane sensor, the laser methane sensor discussed offers the important advantages of a long calibration period, high detection precision, the absence of zero drift and low power consumption, all of which are significant advantages for use in coal mining applications. By compensating for the temperature and pressure of the gases present, the accuracy of the methane sensor is evident across a wide range of temperatures and pressures, making it suitable for gas detection, including methane, in pipelines as well. The wireless laser approach which is incorporated into the methane sensor allows wireless transmission and data uploading to a cloud server through NB-IoT. This tackles the problem in gas pipeline monitoring of the length of many pipelines and thus the wide distribution of the sensors, avoiding complicated wiring and thus high associated cost. Further, remote data management can then be achieved, all of which greatly improves the flexibility and security of the management of the pipeline and the data generated
The non-centrosymmetric lamellar phase in blends of ABC triblock and ac diblock copolymers
The phase behaviour of blends of ABC triblock and ac diblock copolymers is
examined using self-consistent field theory. Several equilibrium lamellar
structures are observed, depending on the volume fraction of the diblocks,
phi_2, the monomer interactions, and the degrees of polymerization of the
copolymers. For segregations just above the order-disorder transition the
triblocks and diblocks mix together to form centrosymmetric lamellae. As the
segregation is increased the triblocks and diblocks spatially separate either
by macrophase-separating, or by forming a non-centrosymmetric (NCS) phase of
alternating layers of triblock and diblock (...ABCcaABCca...). The NCS phase is
stable over a narrow region near phi_2=0.4. This region is widest near the
critical point on the phase coexistence curve and narrows to terminate at a
triple point at higher segregation. Above the triple point there is two-phase
coexistence between almost pure triblock and diblock phases. The theoretical
phase diagram is consistent with experiments.Comment: 9 pages, 8 figures, submitted to Macromolecule
The shape of disorder broadened Landau subbands in graphene
Density of states (DOS) of graphene under a high uniform magnetic field and
white-noise random potential is numerically calculated. The disorder broadened
zero-energy Landau band has a Gaussian shape whose width is proportional to the
random potential variance and the square root of magnetic field. Wegner-type
calculation is used to justify the results
Energy transfer, pressure tensor and heating of kinetic plasma
Kinetic plasma turbulence cascade spans multiple scales ranging from
macroscopic fluid flow to sub-electron scales. Mechanisms that dissipate large
scale energy, terminate the inertial range cascade and convert kinetic energy
into heat are hotly debated. Here we revisit these puzzles using fully kinetic
simulation. By performing scale-dependent spatial filtering on the Vlasov
equation, we extract information at prescribed scales and introduce several
energy transfer functions. This approach allows highly inhomogeneous energy
cascade to be quantified as it proceeds down to kinetic scales. The pressure
work, , can
trigger a channel of the energy conversion between fluid flow and random
motions, which is a collision-free generalization of the viscous dissipation in
collisional fluid. Both the energy transfer and the pressure work are strongly
correlated with velocity gradients.Comment: 28 pages, 10 figure
Pentaquark Magnetic Moments In Different Models
We calculate the magnetic moments of the pentaquark states from different
models and compare our results with predictions of other groups.Comment: 17 pages, no figur
Microbubble Cavitation Imaging
Ultrasound cavitation of microbubble contrast agents has a potential for therapeutic applications such as sonothrombolysis (STL) in acute ischemic stroke. For safety, efficacy, and reproducibility of treatment, it is critical to evaluate the cavitation state (moderate oscillations, stable cavitation, and inertial cavitation) and activity level in and around a treatment area. Acoustic passive cavitation detectors (PCDs) have been used to this end but do not provide spatial information. This paper presents a prototype of a 2-D cavitation imager capable of producing images of the dominant cavitation state and activity level in a region of interest. Similar to PCDs, the cavitation imaging described here is based on the spectral analysis of the acoustic signal radiated by the cavitating microbubbles: ultraharmonics of the excitation frequency indicate stable cavitation, whereas elevated noise bands indicate inertial cavitation; the absence of both indicates moderate oscillations. The prototype system is a modified commercially available ultrasound scanner with a sector imaging probe. The lateral resolution of the system is 1.5 mm at a focal depth of 3 cm, and the axial resolution is 3 cm for a therapy pulse length of 20 mu s. The maximum frame rate of the prototype is 2 Hz. The system has been used for assessing and mapping the relative importance of the different cavitation states of a microbubble contrast agent. In vitro (tissue-mimicking flow phantom) and in vivo (heart, liver, and brain of two swine) results for cavitation states and their changes as a function of acoustic amplitude are presented
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