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General relativistic calculations for white dwarfs

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Research in Astronomy and Astrophysics 2017年第6期17卷 107-116页

作者： Arun Mathew Malay k. Nandy Department of Physics Indian Institute of Technology Guwahati Guwahati 781 039 India

The mass-radius relations for white dwarfs are investigated by solving the Newtonian as well as Tolman-Oppenheimer-Volk.ff （TOV） equations for hydrostatic equilibrium assuming the electron gas to be non-interacting. We find that the Newtonian limiting mass of 1.4562 M is modified to 1.4166 M in the general relativistic case for 4He （and 12 6C） white dwarfs. Using the same general relativistic treatment, the critical mass for 56 26Fe white dwarfs is obtained as 1.2230 M. In addition, departure from the ideal degenerate equation of state （EoS） is accounted for by considering Salpeter＇s EoS along with the TOV equation, yielding slightly lower values for the critical masses, namely 1.4081 M for 4He, 1.3916M for 12C and 1.1565M for 56 26Fe white dwarfs. We also compare the critical densities for gravitational instability with the neutronization threshold densities to find that 4 2He and 12 6C white dwarfs are stable against neutronization with the critical values of 1.4081 M and 1.3916 M, respectively. However, the critical masses for 16 8O, 20 10Ne, 24 12Mg, 28 14Si,32 16S and 56 26Fewhite dwarfs are 26Fe white lower due to neutronization. Corresponding to their central densities for neutronization thresholds, we obtain their maximum stable masses due to neutronization by solving the TOV equation coupled with the Salpeter EoS.

关键词： equation of state - hydrodynamics-instabilities - relativistic processes - stars whitedwarfs

Design and fabrication of automated sedimentation-based separation and siphon-based extraction for detection of allergic reaction on a centrifugal microfluidic disc

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Chinese Optics Letters 2010年第10期8卷 957-959页

作者： Q. L. Chen H. P. Ho k. L. Cheung S. k. k.ng Y. k. Suen Y. W. k.an C. k. Wong Center for Advanced Research in Photonics and Department of Electronic Engineering The Chinese University of Hong Kong Hong Kong China Department of Biochemistry The Chinese University of Hong Kong Hong Kong China School of Biomedical Sciences The Chinese University of Hong Kong Hong Kong China Department of Chemical Pathology The Chinese University of Hong Kong Hong Kong China

We report the design and fabrication of a novel and fully integrated polymer-based centrifugal microfluidic disc for rapid automatic allergens detection. All essential steps for a single test including flow valving, sequencing, mixing, separation, extraction, and sedimentation for final detection are automatically conducted within 30 min on a centrifugal microfluidic disc. Our design features a siphon-based valving and analyte extraction structure where the released analyte is separated and subsequently extracted by a siphon valve into the detection chamber. Incorporating the siphon valve and a series of capillary valves, we realize automated detection of allergic reaction on a centrifugal microfluidic disc.

关键词： Adaptive optics Diffuse optical imaging Photolithography Polydimethylsiloxane Polymethyl methacrylate

Advances in managing hepatocellular carcinoma

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Frontiers of Medicine 2014年第2期8卷 175-189页

作者： Marielle Reataza David k. Imagawa University of California lrvine Medical Center Orange CA 92868 USA Division of Hepatobiliary and Pancreas Surgery Department of Surgery University of California Irvine Medical Center Orange CA 92868 USA

Multiple modalities for treatment of hepatocellular carcinoma are available, depending on tumor size and number. Surgical resection remains the gold standard, so long as the residual liver function reserve is sufficient. In patients with advanced cirrhosis, liver transplantation is the preferred option, as these patients may not have adequate hepatic reserve after resection. Salvage liver transplantation has also become an option for a select few patients who recur after surgical resection. Ablative techniques have been used for palliation as well as to either completely destroy the tumor, act as an adjunct to resection, or downstage the tumor to meet Milan criteria such that a patient may be a candidate for liver transplantation. Radiofrequency ablation, microwave ablation, chemoembolization, radioembolization, and irreversible electroporation have all been used in this capacity. Currently, sorafenib is the only US Food and Drug Administration-approved chemotherapeutic for hepatocellular carcinoma. The efficacy of sorafenib, in combination with other agents, transarterial chemoembolization, and surgical resection is currently being investigated. Sunitinib and brivanib, tyrosine k.nase inhibitors, have failed as potential first- or second-line options for chemotherapy. Bevacizumab in combination with erlotinib is also currently being studied. Final analysis for ramucirumab and axitinib are pending. Tivantinib, a selective mesenchymai-epithelial transition factor （MET） inhibitor, is also undergoing clinical trials for efficacy in MET- high tumors. This review serves to emphasize the current and new technologies emerging in the treatment of hepatoeellular carcinoma.

关键词： hepatocellular carcinoma radiofrequency ablation microwave ablation chemoembolization radioembolization sorafenib irreversible electroporation

A transverse local feedback.linearization approach to human head movement control

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Control Theory and Technology 2017年第4期15卷 288-300页

作者： Tak.fumi Ok. Bijoy k. Ghosh 1. Department of Mathematics and Statistics Texas Tech University Lubbock Texas 79409-1042 U.S.A.

In the mid-nineteenth century, Donders had proposed that for every human head rotating away from the primary pointing direction, the rotational vectors in the direction of the corresponding axes of rotation, is restricted to lie on a surface. Donders＇ intuition was that under such a restriction, the head orientation would be a function of its pointing direction. In this paper, we revisit Donders＇ Law and show that indeed the proposed intuition is true for a restricted class of head-orientations satisfying a class of quadratic Donders＇ surfaces, if the head points to a suitable neighborhood of the frontal pointing direction. Moreover, on a suitably chosen subspace of the 3D rotation group SO（3）, we describe a head movement dynamical system with input control signals that are the three external torques on the head provided by muscles. Three output signals are also suitably chosen as follows. Two of the output signals are coordinates of the frontal pointing direction. The third signal measures deviation of the state vector from the Donders＇ surface. We claim that the square system is locally feedback.linearizable on the subspace chosen, and the linear dynamics is decomposed into parts, transverse and tangential to the Donders＇ surface. We demonstrate our approach by synthesizing a track.ng and path-following controller. Additionally, for different choices of the Donders＇ surface parameters, head gaits are visualized by simulating different movement patterns of the head-top vector, as the head-pointing vector rotates around a circle.

关键词： Head movement Donders' surface transverse feedback.linearization Fick.Gimbal

Understanding the paleomires of Eocene lignites of k.chchh Basin, Gujarat （Western India）： petrological implications

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International Journal of Coal Science & Technology 2017年第2期4卷 80-101页

作者： Prak.sh k. Singh Vijay k. Singh M. P. Singh P. k. Rajak Coal and Organic Petrology Lab Centre of Advanced Studyin Geology Banaras Hindu University VaranasiUttar Pradesh 221005 India

The present paper entails the results of the investigations carried out on the lignite deposits of k.chchh Basin. The lignite samples were drawn from five lignite seams from Panandhro lignite field （Seam-I to -V） and eight lignite seams （Seam-I to -VIII） from the Matanomadh lignite field which are currently operational. The petrographic analysis of the lignites indicates a dominance of huminite group of macerals which is mainly contributed by ulminite-A, ulminite-B, attrinite, densinite, and phlobaphinite. Liptinite （chiefly sporinite, cutinite, resinite, and liptodetrinite） and inertinite （chiefly fusinite, funginite, and inertodetrinite） groups occur in subordinated amount. The mineral matter occurs in moderate concentration. Though sulfur content is high in these lignites, there is no fixed trend of variation of sulfur from bottom seam to top seam. The investigation reveals a flooded forest swamp having high rate of degradation. However, there were a few drier periods indicated by relatively more inertinite macerals. The petrography-based models indicate that the k.chchh lignites of Gujarat evolved in coastal marshy setting under transgressive phase. However, there were few intermittent fluvial activities giving rise to supratidal flood plain. This led to the formation of the associated carbonaceous shales in the basin.

关键词： k.chchh Basin Eocene lignite Petrography Paleomire

An Analysis of the Invariance and Conservation Laws of Some Classes of Nonlinear Ostrovsk. Equations and Related Systems

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Chinese Physics Letters 2011年第1期28卷 1-4页

作者： k. Fak.ar A. H. k.ra Department of Mathematics Faculty of Science Universiti Teknologi Malaysia 81310 UTM Skudai Johor Malaysia School of Mathematics and Centre for Differential Equations Continuum Mechanics and Applications University of the Witwatersrand Johannesburg P Bag 3 Wits 2050 South Africa

A large class of partial differential equations in the modelling of ocean waves are due to Ostrovsk.. We determine the invariance properties （through the Lie point symmetry generators） and construct classes of conservation laws for some of the models. In the latter case, the method involves finding the ＇multipliers＇ associated with the conservation laws with a stronger emphasis on the ＇higher-order＇ ones. The relationship between the symmetries and conservation laws is investigated by considering the invariance properties of the multipliers.

关键词： Mathematical physics Statistical physics and nonlinear systems

Petrographic characteristics and paleoenvironmental history of Eocene lignites of Cambay basin, Western India

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International Journal of Coal Science & Technology 2017年第3期4卷 214-233页

作者： Prak.sh k. Singh Vijay k. Singh M. P. Singh P. k. Rajak Coal and Organic Petrology Lab Centre of Advanced Study in Geology Banaras Hindu University Varanasi Uttar Pradesh 221005 India

Lignite samples collected from Vastan, Rajpardi and Tadk.shwar lignite mines of Cambay basin （Gujarat） were subjected to organic petrographic investigations and geochemical analyses and the data, thus generated, is used to reconstruct the paleodepositional history of these lignite sequences. The lignites of Cambay basin dominantly comprise huminite maceral group （71.6%-86.3%） followed by liptinite （10.1%-19.3%） and inertinite （3.6%-11.0%） maceral groups. The mineral matter varies from 9.0% to 20.0%. The petrography based facies model indicates that these lignites have high values of gelification index （GI） and low tissue preservation index revealing a continuous wet condition in the basin and a relatively slower rate of subsidence during the decay of organic matter. On several occasions, during the formation of seams in Tadk.shwar, Rajpardi and Vastan mines, the value of GI exceeded 10 which indicates a forest permanently flooded and the cause of pronounced degree of degradation. However, few sections in Tadk.shwar seam had relatively drier spells of environmental conditions due to fluctuation in the water table as revealed by moderately high content of inertinite macerals. This is specially indicated by the occurrence of funginite which normally thrives in the upper oxy- genated peatigenic layer and indicates prevalence of oxic conditions during plant deposition. Such conditions prevailed during a transgressive phase but there were intermittent fluvial activities also giving rise to supratidal flood plain as reflected in the form of associated carbonaceous shales in the basin.

关键词： Cambay basin Western India Lignite Maceral Paleodepositional environment

Post-failure behavior of tunnel heading collapse by MPM simulation

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Science China(Technological Sciences) 2015年第12期58卷 2139-2152页

作者： CHENG XueSong ZHENG Gang SOGA k. BANDARA S.S. k.MAR k. DIAO Yu XU Jie MOE k.y Laboratory of Coast Civil Structure Safety Tianjin University Department of Civil Engineering Tianjin University Department of Engineering University of Cambridge

Tunnel collapse presents a serious threat to the safety of urban construction. The traditional approach adopted to assess this risk.is to evaluate the factor of safety against failure. However, this analysis only determines on whether the tunnel will collapse or not, and does not provide information on the magnitude of the post-failure behavior(for example, catastrophic or progressive) if the tunnel collapse occurs. In this study, a meshless method based on the material point method(MPM) was used to investigate the post-failure behavior of tunnel heading collapse in two-dimensional plane-strain conditions. The capability and accuracy of MPM were verified by comparing the elicited results to centrifuge test data and to analytical solutions obtained from limit state methods. MPM simulations were conducted at different soil conditions(clay or sand) and profiles(homogenous or linear increasing strength) as well as at different tunnel geometries(i.e. tunnel depth and unlined length). The differences in the post-failure behavior and mechanisms are examined and reported.

关键词： tunnel stability collapse mechanism material point method large deformation

Effect of Discharge Voltage on an Ion Sheath Formed at a Grid in a Multi-Dipole Discharge Plasma

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Chinese Physics Letters 2008年第3期25卷 1011-1014页

作者： M. k. Mishra A. Phuk.n Centre of Plasma Physics.Tepesia Kamrup-782402 Assam INDIA

It is experimentally demonstrated that a relatively strong ion-rich sheath formed at a fixed negative bias of the grid can be changed to a rather weak.ion sheath （sheath potential weak.y retards electrons） only by increasing the discharge voltage in the system. At sufficiently high negative grid bias, an increase of discharge voltage enhances the ion collection current at the grid. An explanation is put forward in support of this experimental observation. A slight density enhancement with a fall in plasma electron temperature is also observed with the increasing negative grid bias.

关键词： supernova explosion proto-neutron star shock.wave