Constraining the Mass of the Photon with Gamma-Ray Bursts

One of the cornerstones of modern physics is Einstein's special relativity, with its constant speed of light and zero photon mass assumptions. Constraint on the rest mass m_{\gamma} of photons is a fundamental way to test Einstein's theory, as well as other essential electromagnetic and particle theories. Since non-zero photon mass can give rise to frequency-(or energy-) dependent dispersions, measuring the time delay of photons with different frequencies emitted from explosive astrophysical events is an important and model-independent method to put such a constraint. The cosmological gamma-ray bursts (GRBs), with short time scales, high redshifts as well as broadband prompt and afterglow emissions, provide an ideal testbed for m_{\gamma} constraints. In this paper we calculate the upper limits of the photon mass with GRB early time radio afterglow observations as well as multi-band radio peaks, thus improve the results of Schaefer (1999) by nearly half an order of magnitude.Comment: 25 pages, 2 tables, Accepted by Journal of High Energy Astrophysic

Automatic grammar enhancement for virtual assistant

Grammar rule generation for virtual assistant applications is difficult to scale due to the need for manual labeling. This disclosure describes a scalable solution to automatically generate enhanced grammar rules in predefined verticals. The techniques enable incremental improvements to interpretations of voice commands by a virtual assistant application. Queries that have not already been processed for a target vertical are identified and extracted from a corpus of user queries, e.g., a time-limited corpus in a particular language. Queries are analyzed to discover arguments and patterns that are specific to the vertical. Grammar rules are generated based on the arguments and patterns

Vibration control of super tall buildings subjected to wind loads

Excessive vibration due to wind loads is a major obstacle in design and construction of a super tall building. The authors recently introduced an innovative method for controlling the wind response of super tall buildings, which takes advantage of the so-called mega-sub structural configuration. Preliminary investigation was performed under the assumption that the wind load is a white noise and the building can be modeled as a shear structure. In this paper, a more reasonable tall building model (a cantilever beam) and a more realistic wind load model (a non-white stochastic process in time and space) are employed to design passive and hybrid mega-sub control systems and to examine the performance of such controlled buildings. Building vibration in both along-wind and across-wind directions is examined. The control parameters of the proposed systems, including the frequency ratio of the sub to the mega structures, the damping ratio of the sub structure, and the feedback gains of the actuator force, are studied and their optimal values are obtained. For comparison, a tall building without control and one with the conventional tuned-mass-damper control are also studied under the same load conditions. The significant cost-effectiveness of the proposed mega-sub systems is demonstrated in reducing the acceleration and deformation responses of tall buildings to wind loads, not only enhancing the safety of structure and its contents but also improving the comfort of occupants

Design of a mega-sub-controlled building system under stochastic wind loads

Vibration control of high-rise buildings under wind loads with application of the mega-sub-control method is studied in this paper. A building with a megasub-configuration consists of two major structural components - a megastructure as the main structural frame and several sub-structures for residential and/or commercial usage. The authors have previously proposed a ‘megasub-control method’ in which the sub-structures are designed to serve as vibration control dampers. The control objective is to suppress certain critical building responses such as inter-story drifts of the mega-structure for the purpose of structural safety and acceleration response of the sub-structures for the purpose of protecting contents and improving human comfort. The feasibility of this method has been explored by the authors in previous publications. In this study, the procedure of optimally designing dynamic parameters of a megasub-controlled building under stochastic wind loads is developed, together with two possible structural configurations which provide a mega-sub-control mechanism. The mega-structure of a mega-sub-building is modeled as a cantilever beam to retain the dominant bending mode characteristics of highrise buildings, and the sub-structure as a shear building to retain the shear mode. The fluctuating wind speed is modeled as a non-white random process in both time and space domains. The power spectral density (PSD) of critical building responses is obtained using the random vibration theory. The mean square value (MSV) of those responses, as functions of the dynamic parameters including the stiffness and damping ratio of the sub-structures, are evaluated from their PSD by numerical integration in the frequency domain. The optimal values of the dynamic parameters are determined by minimizing the MSV of certain critical building responses. An example building is used to demonstrate the design procedure and the numerical simulation of the response quantities in the time domain is carried out to verify the MSV of the building responses obtained from the random vibration theory in the frequency domain. The results show that the proposed design procedure is suitable to apply to a mega-sub-building with different sub-structural configurations. The MSV obtained from the random vibration theory in the frequency domain and from the numerical simulation in the time domain exhibit an excellent agreement. It is also found that the megasub-control method is robust in the sense that slight change in the dynamic parameters affects the building's performance very little. With the design procedure developed, and the corresponding favorable building response demonstrated, this paper has enhanced the feasibility of application of the mega-sub-control method to actual high-rise buildings for wind vibration suppression

Frozen Gaussian Sampling for Scalar Wave Equations

In this article, we introduce the frozen Gaussian sampling (FGS) algorithm to solve the scalar wave equation in the high-frequency regime. The FGS algorithm is a Monte Carlo sampling strategy based on the frozen Gaussian approximation, which greatly reduces the computation workload in the wave propagation and reconstruction. In this work, we propose feasible and detailed procedures to implement the FGS algorithm to approximate scalar wave equations with Gaussian initial conditions and WKB initial conditions respectively. For both initial data cases, we rigorously analyze the error of applying this algorithm to wave equations of dimensionality $d \geq 3$. In Gaussian initial data cases, we prove that the sampling error due to the Monte Carlo method is independent of the typical wave number. We also derive a quantitative bound of the sampling error in WKB initial data cases. Finally, we validate the performance of the FGS and the theoretical estimates about the sampling error through various numerical examples, which include using the FGS to solve wave equations with both Gaussian and WKB initial data of dimensionality $d = 1, 2$, and $3$

Oral cancer cells may rewire alternative metabolic pathways to survive from siRNA silencing of metabolic enzymes.

BackgroundCancer cells may undergo metabolic adaptations that support their growth as well as drug resistance properties. The purpose of this study is to test if oral cancer cells can overcome the metabolic defects introduced by using small interfering RNA (siRNA) to knock down their expression of important metabolic enzymes.MethodsUM1 and UM2 oral cancer cells were transfected with siRNA to transketolase (TKT) or siRNA to adenylate kinase (AK2), and Western blotting was used to confirm the knockdown. Cellular uptake of glucose and glutamine and production of lactate were compared between the cancer cells with either TKT or AK2 knockdown and those transfected with control siRNA. Statistical analysis was performed with student T-test.ResultsDespite the defect in the pentose phosphate pathway caused by siRNA knockdown of TKT, the survived UM1 or UM2 cells utilized more glucose and glutamine and secreted a significantly higher amount of lactate than the cells transferred with control siRNA. We also demonstrated that siRNA knockdown of AK2 constrained the proliferation of UM1 and UM2 cells but similarly led to an increased uptake of glucose/glutamine and production of lactate by the UM1 or UM2 cells survived from siRNA silencing of AK2.ConclusionsOur results indicate that the metabolic defects introduced by siRNA silencing of metabolic enzymes TKT or AK2 may be compensated by alternative feedback metabolic mechanisms, suggesting that cancer cells may overcome single defective pathways through secondary metabolic network adaptations. The highly robust nature of oral cancer cell metabolism implies that a systematic medical approach targeting multiple metabolic pathways may be needed to accomplish the continued improvement of cancer treatment

New Management for the New Economy

ABSTRAC

Quantum electric-dipole liquid on a triangular lattice

Geometric frustrations and quantum mechanical fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets that represents an exotic phase of matter and is attracting enormous interests. Geometric frustrations and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogs to quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled small electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19, in which small electric dipoles originated from the off-center displacement of Fe3+ in the FeO5 bipyramids constitute a two-dimensional triangular lattice, represents a promising candidate to generate the anticipated electric-dipole liquid. We present a series of experimental evidences, including dielectric permittivity, heat capacity, and thermal conductivity measured down to 66 mK, to reveal the existence of a nontrivial ground state in BaFe12O19, characterized by itinerant low-energy excitations with a small gap, to which we interpret as an exotic liquid-like quantum phase. The quantum electric-dipole liquids in frustrated dielectrics open up a fresh playground for fundamental physics and may find applications in quantum information and computation as well.Comment: 13 pages, 6 figure

初期特发性脊柱侧弯患者的补硒膳食指导

The study found that there was a correlation between trace element Se and idiopathic scoliosis, and selenium deficiency was probably one of the precipitating factor. According to Chinese dietary reference intakes and selenium content in different food, the plan for filling selenium is conducted, the dietary guidance of filing selenium for incipient idiopathic scoliotic patients is provided, and the disease development is observed so that the basis for etiology and prevention of idiopathic scoliosis can be provided.研究发现微量元素硒与特发性脊柱侧弯具有相关性,硒缺乏可能是诱发因素之一。根据中国居民膳食营养素参考摄入量和不同食物中硒含量制定补硒方案,为初期特发性脊柱侧弯患者提供补硒的膳食指导，观察特发性脊柱侧弯畸形进展情况，为特发性脊柱侧弯的病因学研究和疾病预防提供依据

A double salt of iodo­bis­muthate: cis-aqua­iodidobis(1,10-phenanthroline)cobalt(II) tris­(1,10-phenanthroline)cobalt(II) trans-hexa-μ2-iodido-hexa­iodidotribismuthate(III)

In the title complex, [Co(C12H8N2)3][CoI(C12H8N2)2(H2O)][Bi3I12], conventionally abbreviated [Co(phen)3][CoI(phen)2(H2O)][Bi3I12], where phen is 1,10-phenanthroline, the CoII atom in one cation is coordinated by six N atoms from three phen ligands in an octa­hedral coordination while the CoII atom in the other cation is coordinated octa­hedrally by four N atoms from two phen ligands, one water O atom and one I atom. In the anion, three BiIII ions adopt an octa­hedral coordination constructed by six I− ligands. The three BiI6 octa­hedra are fused together through trans face-sharing