bluuebunny/crossref_metadata_2025 huggingface dataset:
Pharmacological and Biochemical Analysis of Interactions between N‐Acetylcysteine and Some Antiepileptic Drugs on Experimental Seizures in Mice
Authors: Devi P. Uma , Saraogi P. , Manocha A. , Vohora Divya
Published: January 2012

SUMMARY  Purpose: In view of a putative role of oxidative stress in the pathophysiology of seizures, this study addressed the interactions between N‐acetylcysteine (NAC), a potent antioxidant and two antiepileptic drugs sodium valproate (SVP) and phenytoin (PHT) on experimental seizures in mice. Methods: The interaction was studied at three fixed ratio combinations (i.e., 1:1, 1:3, and 3:1) in the mouse maximal electroshock (MES) test using isobolographic analysis. Markers of oxidative stress (reduced glutathione [GSH] and malondialdehyde [MDA]) were estimated in the cortex of mice pretreated with either of these drugs alone or their 3:1 ratio combinations at the experimentally determined ED50 values (ED50 exp values). The grip strength and spontaneous alternation behavior (SAB) were also assessed. In addition, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and calcium levels were estimated. Results: We found an anticonvulsant action of NAC in the MES test. Further, the ED50 exp values for the combinations of PHT and NAC did not differ from the theoretically calculated ED50 values indicating additive effects. In case of SVP and NAC, however, the ED50 exp values were lower than the theoretically calculated ED50 values. The interaction of SVP with NAC at the fixed ratios of 1:3 and 3:1 was found to be synergistic. No significant changes were observed in the grip strength, SAB, cortical GSH and MDA levels, serum AST, ALT, ALP, or calcium levels. Conclusion: Our results thus hold promise for the use of NAC as an adjunct to PHT and SVP therapy.
Seasonal dynamics of above‐ and below‐ground biomass and nitrogen partitioning in Miscanthus × giganteus and Panicum virgatum across three growing seasons
Authors: Dohleman Frank G. , Heaton Emily A. , Arundale Rebecca A. , Long Stephen P.
Published: January 2012

The first replicated productivity trials of the C4 perennial grass Miscanthus × giganteus in the United States showed this emerging ligno‐cellulosic bioenergy feedstock to provide remarkably high annual yields. This covered the 5 years after planting, leaving it uncertain if this high productivity could be maintained in the absence of N fertilization. An expected, but until now unsubstantiated, benefit of both species was investment in roots and perennating rhizomes. This study examines for years 5–7 yields, biomass, C and N in shoots, roots, and rhizomes. The mean peak shoot biomass for M. × giganteus in years 5–7 was 46.5 t ha−1 in October, declining to 38.1 t ha−1 on completion of senescence and at harvest in December, and 20.7 t ha−1 declining to 11.3 t ha−1 for Panicum virgatum. There was no evidence of decline in annual yield with age. Mean rhizome biomass was significantly higher in M. × giganteus at 21.5 t ha−1 compared to 7.2 t ha−1 for P. virgatum, whereas root biomass was similar at 5.6–5.9 t ha−1. M. × giganteus shoots contained 339 kg ha−1 N in August, declining to 193 kg ha−1 in December, compared to 168 and 58 kg ha−1 for P. virgatum. The results suggest substantial remobilization of N to roots and rhizomes, yet still a substantial loss with December harvests. The shoot and rhizome biomass increase of 33.6 t ha−1 during the 2‐month period between June and August for M. × giganteus corresponds to a solar energy conversion of 4.4% of solar energy into biomass, one of the highest recorded and confirming the remarkable productivity potential of this plant.
Bacterial anoxygenic photosynthesis on plant leaf surfaces
Authors: Atamna‐Ismaeel Nof , Finkel Omri , Glaser Fabian , von Mering Christian , Vorholt Julia A. , Koblížek Michal , Belkin Shimshon , Béjà Oded
Published: January 2012

The aerial surface of plants, the phyllosphere, is colonized by numerous bacteria displaying diverse metabolic properties that enable their survival in this specific habitat. Recently, we reported on the presence of microbial rhodopsin harbouring bacteria on the top of leaf surfaces. Here, we report on the presence of additional bacterial populations capable of harvesting light as a means of supplementing their metabolic requirements. An analysis of six phyllosphere metagenomes revealed the presence of a diverse community of anoxygenic phototrophic bacteria, including the previously reported methylobacteria, as well as other known and unknown phototrophs. The presence of anoxygenic phototrophic bacteria was also confirmed in situ by infrared epifluorescence microscopy. The microscopic enumeration correlated with estimates based on metagenomic analyses, confirming both the presence and high abundance of these microorganisms in the phyllosphere. Our data suggest that the phyllosphere contains a phylogenetically diverse assemblage of phototrophic species, including some yet undescribed bacterial clades that appear to be phyllosphere‐unique.
Presynaptic AMPA receptors: more than just ion channels?
Authors: Schenk Ursula , Matteoli Michela
Published: January 2012

Summry— AMPA receptor ion channels are of paramount importance for postsynaptic excitation. Several reports demonstrate that AMPA receptors are present in the presynaptic compartment and point to a role of these receptors in the modulation of presynaptic function. We discuss here the possibility that not only ion influx through the receptor, but also biochemical cascades, activated by ligand binding and independent from ion flux, might contribute to AMPA mediated presynaptic modulation.
Participation of the Adhesive Disc during Karyokinesis in Giardia lamblia
Authors: Benchimol Marlene
Published: January 2012

Summry— Evidence is presented for a potential involvement of the adhesive disc on the nucleus division in Giardia lamblia. The trophozoite mitotic nucleus was studied by transmission electron microscopy, freeze‐fracture, freeze‐substitution and also by immunofluorescence microscopy using anti‐tubulin antibodies specific to spindle microtubules and Panotic staining. Prior to cell division the nucleus elongated and a displaced disc fragment, established contact with the nucleus. A progressive nucleus indentation was coincident with the concomitant presence of a disc fragment at the constricted region. One nucleus each time progressively divided until the karyokinesis was finished and two daughter‐nuclei were observed. After the first karyokinesis a second karyokinesis takes place following the same procedure. When Giardia gets the four nuclei, cytokinesis occurs. Duplicated basal bodies were seen in between the first and the second karyokinesis. Immunofluorescence microscopy, using a panel of anti‐tubulin antibodies, and electron microscopy of cells processed using microtubule stabilizer buffers, or cells fast‐frozen and freeze‐substituted, did not reveal the presence of a typical spindle. We propose that Giardia lamblia presents an uncommon mitotic behavior where the adhesive disc, a microtubular structure, seems to participate in the karyokinesis process.
Structural determinants involved in the activation and regulation of G protein‐coupled receptors: lessons from the alpha1‐adrenegic receptor subtypes
Authors: Cotecchia Susanna , Stanasila Laura , Diviani Dario , Björklöf Katja , Rossier Olivier , Fanelli Francesca
Published: January 2012

Summry— The aim of a large number of studies on G protein‐coupled receptors was centered on understanding the structural basis of their main functional properties. Here, we will briefly review the results obtained on the α1‐adrenergic receptor subtypes belonging to the rhodopsin‐like family of receptors. These findings contribute, on the one hand, to further understand the molecular basis of adrenergic transmission and, on the other, to provide some generalities on the structure‐functional relationship of G protein‐coupled receptors.
Modeling Cell Signaling Networks
Authors: Eungdamrong Narat J , Iyengar Ravi
Published: January 2012

Summry— Cell signaling pathways interact with one another to form networks in mammalian systems. Such networks are complex in their organization and exhibit emergent properties such as bistability and ultrasensitivity. Analysis of signaling networks requires a combination of experimental and theoretical approaches including the development and analysis of models. This review focuses on theoretical approaches to understanding cell signaling networks. Using heterotrimeric G protein pathways an example, we demonstrate how interactions between two pathways can result in a network that contains a positive feedback loop and function as a switch. Different mathematical approaches that are currently used to model signaling networks are described, and future challenges including the need for databases as well as enhanced computing environments are discussed.
Molecular and Functional Characterization of Proteins Interacting with the C‐Terminal Domains of 5‐HT2 Receptors: Emergence of 5‐HT2 “Receptosomes”
Authors: Gavarini Sophie , Bécamel Carine , Chanrion Benjamin , Bockaert Joël , Marin Philippe
Published: January 2012

Summry— Many cellular functions are carried out by multiprotein complexes. The last five years of research have revealed that many G‐protein coupled receptor (GPCR) functions that are not mediated by G proteins involve protein networks, which interact with their intracellular domains. This review focuses on one family of GPCRs activated by serotonin, the 5‐HT2 receptor family, which comprises three closely related subtypes, the 5‐HT2A, the 5‐HT2B and the 5‐HT2c receptors. These receptors still raise particular interest, because a large number of psychoactive drugs including hallucinogens, anti‐psychotics, anxiolytics and anti‐depressants, mediate their action, at least in part, through activation of 5‐HT2 receptors. Recent studies based on two‐hybrid screens, proteomic, biochemical and cell biology approaches, have shown that the C‐terminal domains of 5‐HT2 receptors interact with intracellular proteins. To date, the protein network associated with the C‐terminus of the 5‐HT2C receptor has been the most extensively characterized, using a proteomic approach combining affinity chromatography, mass spectrometry and immunoblotting. It includes scaffolding proteins containing one or several PDZ domains, signalling proteins and proteins of the cytoskeleton. Data indicating that the protein complexes interacting with 5‐HT2 receptor C‐termini tightly control receptor trafficking and receptor‐mediated signalling will also be reviewed.
Japanese case of Budd‐Chiari syndrome due to hepatic vein thrombosis successfully treated with liver transplantation
Authors: Iwasaki Tomohiro , Kawai Hirokazu , Oseki Koushi , Togashi Tadayuki , Shioji Kazuhiko , Yamamoto Satoshi , Sato Yoshinobu , Suzuki Kenji , Toba Ken , Nomoto Minoru , Hatakeyama Katsuyoshi , Aoyagi Yutaka
Published: January 2012

A 22‐year‐old Japanese woman was found to have severe esophageal varices and then suffered from hepatic encephalopathy. She was diagnosed with Budd‐Chiari syndrome (BCS) due to hepatic vein (HV) thrombosis accompanied by portal vein thrombosis without inferior vena cava (IVC) obstruction. Latent myeloproliferative neoplasm (MPN) lacking the JAK2‐V617F mutation was considered to be the underlying disease. Liver transplantation was strikingly effective for treating the clinical symptoms attributable to portal hypertension. Although thrombosis of the internal jugular vein occurred due to thrombocythemia, which manifested after transplantation despite anticoagulation therapy with warfarin, the thrombus immediately disappeared with the addition of aspirin. Neither thrombosis nor BCS has recurred in more than 4 years since the amelioration of the last thrombotic event, and post‐transplant immunosuppression with tacrolimus has not accelerated the progression of MPN. In Japan, IVC obstruction, which was a predominant type of BCS, is suggested to have decreased in incidence with recent improvements in hygiene. The precise diagnosis of BCS and causative underlying diseases should be made with attention to the current trend of the disease spectrum, which fluctuates with environmental sanitation levels. Because the stepwise strategy, including liver transplantation, has been proven effective for patients with pure HV obstruction in Western countries, this strategy should also be validated for utilization in Japan and in developing countries where HV obstruction potentially predominates.
The Critical Role of Ocean Container Transport in Global Supply Chain Performance
Authors: Fransoo Jan C. , Lee Chung‐Yee
Published: January 2012

With supply chains distributed across global markets, ocean container transport now is a critical element of any such supply chain. We identify key characteristics of ocean container transport from a supply chain perspective. We find that unlike continental (road) transport, service offerings tend to be consolidated in few service providers, and a strong focus exists on maximization of capital intensive resources. Based on the characteristics of ocean container transport as part of global supply chains, we list a number of relevant and challenging research areas and associated questions.
A LEVEL-SET METHOD BASED ON GLOBAL AND LOCAL REGIONS FOR IMAGE SEGMENTATION
Authors: ZHAO YU QIAN , WANG XIAO FANG , SHIH FRANK Y. , YU GANG
Published: January 2012

This paper presents a new level-set method based on global and local regions for image segmentation. First, the image fitting term of Chan and Vese (CV) model is adapted to detect the image's local information by convolving a Gaussian kernel function. Then, a global term is proposed to detect large gradient amplitude at the outer region. The new energy function consists of both local and global terms, and is minimized by the gradient descent method. Experimental results on both synthetic and real images show that the proposed method can detect objects in inhomogeneous, low-contrast, and noisy images more accurately than the CV model, the local binary fitting model, and the Lankton and Tannenbaum model.
A NOVEL METHOD USING VIDEOS FOR FINGERPRINT VERIFICATION
Authors: QIN WEI , YIN YILONG
Published: January 2012

Traditional fingerprint verifications use single image for matching. However, the verification accuracy cannot meet the need of some application domains. In this paper, we propose to use videos for fingerprint verification. To take full use of the information contained in fingerprint videos, we present a novel method to use the dynamic as well as the static information in fingerprint videos. After preprocessing and aligning processes, the Inclusion Ratio of two matching fingerprint videos is calculated and used to represent the similarity between these two videos. Experimental results show that video-based method can access better accuracy than the method based on single fingerprint.
NEW FACIAL FEATURE LOCALIZATION ALGORITHM USING ADAPTIVE ACTIVE SHAPE MODEL
Authors: ALEMY ROGHAYEH , SHIRI MOHAMMAD EBRAHIM , DIDEHVAR FARZAD , HAJIMOHAMMADI ZEYNAB
Published: January 2012

One of the important steps in/towards face recognition is facial feature localization which is difficult. The variety of human faces, expressions, facial hair, race, glasses, poses, and lighting contribute to the complexity of the problem. We systematically varied some of these factors to test the performance of the original active shape model (ASM) and in the next step we modified original ASM that improved accuracy of ASM. Due to these modifications, a new scheme of active shape model for facial feature extraction is proposed in this paper which is named adaptive active shape model. In this scheme, the improvement of the performance of the original ASM focuses on the following three aspects. First, the profile of the original ASM is extended from 1D to 2D. Second, a new face model is constructed in three expressions (natural, smiling, and screaming). Third, in ASM search step, the expression of face is recognized, and the profile model of expression which extracted is used to localize landmark. An extensive experimental investigation is conducted using AR, FERET, JAFFE, YaleB, and Indian face databases. The average improvement of the landmark localization accuracy for proposed method in comparison to the original ASM, under different facial expressions, different illumination conditions, and race variations respectively are 1.85, 0.66 and 7.96.
ROBUST EYE FEATURE EXTRACTION FROM FACIAL COLOR IMAGE USING IRIS COLOR COMPENSATION
Authors: NGUYEN VAN HUAN , KIM HAKIL
Published: January 2012

This paper presents a novel method of robust eye feature extraction from facial color images by considering the variety of iris colors. Given an eye window containing a single eye, the proposed method assesses the iris color tone based on the difference images between the red and the green channels and the red and the blue channels. A weighted scaling compensation method is then proposed for increasing the separability and homogeneity of the iris region. The extraction of the eye features is performed by an unsupervised K-means clustering on the compensated feature spaces. The eye corners are detected after eyelid fitting using a least mean square cost function. Experiments on a collection of eye images extracted from the FERET face database show evidence of promising performance from color facial images with variation in illumination, pose, eye gazing direction, and race.
ERROR RECOVERY IN CONTINUOUS VALUED NUMBER SYSTEM
Authors: MIRHASSANI MITRA , AHMADI MAJID , JULLIEN GRAHAM A.
Published: January 2012

Continuous valued number system is a novel number system which can be employed for developing analog signal processing units. It is a continuous number system which is represented by a set of continuous digits. One of the main features of this system is that digits share information, and have a digit-level redundancy. This redundancy is used to protect the digits against environment imperfections when implemented by analog circuits. In this paper, integrity of this number system in representing real values is explored. The study is required to show the effect of implementation imperfections which is an indicative of its feasibility. Effects of possible errors and error threshold for implementing this system are studied in this paper. An error recovery method is proposed, which enhances this number system representation. An efficient error recovery method extends the application of this number system in high density memory and storage devices for hardware implementations of neural networks.
SAMPLING CORRELATION SOURCES FOR TIMING YIELD ANALYSIS OF SEQUENTIAL CIRCUITS WITH CLOCK NETWORKS
Authors: YU LEE-EUN , SHIN CHANGSIK , PAIK SEUNGWHUN , LIOU JING-JIA , SHIN YOUNGSOO
Published: January 2012

Analyzing timing yield under process variations is difficult because of the presence of correlations. Reconvergent fan-out nodes (RFONs) within combinational subcircuits are a major source of topological correlation. We identify two more sources of topological correlation in clocked sequential circuit: sequential RFONs, which are nodes within a clock network where the clock paths to more than one flip-flop branch out; and sequential branch-points, which are nodes within a combinational block where combinational paths to more than one capturing flip-flop branch out. Dealing with all sources of correlation is unacceptably complicated, and we therefore show how to sample a handful of correlation sources without sacrificing significant accuracy in the yield. A further reduction in computation time can be obtained by sampling only those nodes that are likely to affect the yield. These techniques are applied to yield analysis using statistical static timing analysis based on discrete random variables and also to yield analysis based on Monte Carlo simulation; the accuracy and efficiency of both methods are assessed using example circuits. The sequential RFONs suggest that timing yield may be improved by optimizing the clock network, and we address this possibility.
ROUTING BETWEEN NODES AND MULTIPLE GATEWAYS IN WIRELESS MESH SENSOR NETWORK
Authors: GUO WENJING , ZHANG WEI
Published: January 2012

Aiming at such an application of wireless mesh sensor network (WMSN) so that continuous flow is transmitted, this paper proposes a model "maximum lifetime maximum throughput" based on the ant colony algorithm and minimum cost maximum flow method to address the routing issue between sensor nodes and multiple gateways in WMSN. In the proposed model, a sensor node is allowed to connect through more than one of the available gateways to the Internet. Between the source node and each gateway, a routing path with minimum link cost and maximum available bandwidth is attempted to be found. Then, considering the bandwidth demand of the flow originating from the sensor node and the available bandwidth on each optimal path, the flow traffic is allocated to appropriate gateways. Simulation results have shown that the proposed model not only prolongs network lifetime, but also improves network throughput.
CHUA'S OSCILLATOR IN INTEGRATED CIRCUIT FORM WITH INBUILT CONTROL OPTION
Authors: GOPAKUMAR K. , PREMLET B. , GOPCHANDRAN K. G.
Published: January 2012

The famous chaotic circuit known as Chua's oscillator, despite the robustness of the chaotic behavior to parametric mismatches, requires the construction of noncommercial valued inductor. A low cost inductorless version of Chua's oscillator is presented. The chaotic behavior of the circuit is verified by PSpice simulation and also by experimental study on a circuit breadboard. The results lead to excellent agreement with each other and with the results of previous investigators. Experimental results on the possibility of controlling chaos in the modified Chua's oscillator by the inherent feedback mechanism are also reported.
SPY-TEC+ : AN INTEGRATED INDEX STRUCTURE FOR k-NEAREST NEIGHBOR QUERIES WITH SEMANTIC PREDICATES IN MULTIMEDIA DATABASE
Authors: PARK DONG-JOO , LEE DONG-HO
Published: January 2012

Recently, advanced multimedia applications, such as geographic information system, and content-based multimedia retrieval system, require the efficient processing of k-nearest neighbor queries over large collection of multimedia objects. These queries usually include the semantic information that is represented by text, as well as the visual information that is represented by a high-dimensional feature vector. Among the available techniques for processing such queries, the incremental nearest neighbor algorithm proposed by Hjaltason and Samet is known as the best choice. However, the R-tree used in their algorithm has no facility capable of partially pruning the candidate tuples that will turn out not to satisfy the semantic predicate. Also, the R-tree does not perform sufficiently well on high-dimensional data even though it provides good results on low or middle-dimensional data. These drawbacks may lead to a poor performance when processing the query. In this paper, we propose an integrated index structure, so-called SPY-TEC+, that provides an efficient method for indexing the visual and semantic feature at the same time using the SPY-TEC that was proposed for indexing high-dimensional data, and the signature file. We also propose an efficient incremental nearest neighbor algorithm for processing k-nearest neighbor queries with visual and semantic predicates on the SPY-TEC+. Finally, we show that the SPY-TEC+ enhances the performance of the SPY-TEC for processing k-nearest neighbor queries with visual and semantic predicates through various experiments.
A P2P BASED ARCHITECTURE FOR SEMANTIC WEB SERVICE DISCOVERY
Authors: DI MODICA GIUSEPPE , TOMARCHIO ORAZIO , VITA LORENZO
Published: January 2012

In SOA environments, as the number of published Web Services grows, the provision of a robust, scalable and efficient discovery service is still an unresolved issue. In this paper we present a P2P-based infrastructure that leverages the semantic technologies to support a scalable and accurate service discovery process. The key concept of the presented idea is the creation of an overlay network organized in several semantic groups of peers, each specialized in answering queries pertaining to specific applicative domains. Groups are formed by clustering together peers offering services that are semantically related. A semantic query routing mechanism ensures the delivery of queries to the groups that are semantically "worth" to respond. In this paper the architecture details of the proposed solution is presented. A system prototype has also been implemented and validated through a case study deployed on the PlanetLab testbed.
FINITE MODULES OVER ℤ[t, t-1]
Authors: HOU XIANG-DONG
Published: January 2012

Let Λ = ℤ[t, t-1] be the ring of Laurent polynomials over ℤ. We classify all Λ-modules M with |M| = pn, where p is a prime and n ≤ 4. Consequently, we have a classification of Alexander quandles of order pn for n ≤ 4.
MAGNETARS: FACT OR FICTION?
Authors: TONG HAO , XU REN-XIN
Published: January 2012

Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are enigmatic pulsar-like objects. The energy budget is the fundamental problem in their studies. In the magnetar model, they are supposed to be powered by the extremely strong magnetic fields (≳ 1014 G ) of neutron stars. Observations for and against the magnetar model are both summarized. Considering the difficulties encountered by the magnetar model to comfortably understand more and more observations, one may doubt that AXPs and SGRs are really magnetars. If they are not magnetar candidates (including magnetar-based models), then they must be "quark star/fallback disk" systems.
ENVIRONMENTAL EFFECTS OF FLARES FROM RED DWARF STARS
Authors: PEÑATE LIUBA , CÁRDENAS ROLANDO , MARTÍN OSMEL
Published: January 2012

We examine some environmental effects appearing on exoplanets in the habitable zone of red dwarfs, during the first billion years of the star evolution. We focus on the radiative perturbation that the frequent stellar flares would cause on the planet surface and down the assumed planetary ocean, with some insight on the affectation of potential life forms.
ESTIMATIONS OF THE DISTANCES OF STELLAR COLLAPSES IN THE GALAXY BY ANALYZING THE ENERGY SPECTRUM OF NEUTRINO BURSTS
Authors: KEMP ERNESTO , MIGUEZ BRUNO , FULGIONE WALTER
Published: January 2012

The neutrino telescopes of the present generation, depending on their specific features, can reconstruct the neutrino spectra from a galactic burst. Since the optical counterpart could be not available, it is desirable to have at hand alternative methods to estimate the distance of the supernova explosion using only the neutrino data. In this work we present preliminary results on the method we are proposing to estimate the distance from a galactic supernova based only on the spectral shape of the neutrino burst and assumptions on the gravitational binding energy released an a typical supernova explosion due to stellar collapses.
GRAVITATIONAL MODEL OF THE THREE ELEMENTS THEORY
Authors: LASSIAILLE FREDERIC
Published: January 2012

The gravitational model of the three elements theory is an alternative theory to dark matter. It uses a modification of Newton's law in order to explain gravitational mysteries. The results of this model are explanations for the dark matter mysteries, the Pioneer anomaly, and the disparities of the measurements of G. Concerning the earth flyby anomalies, the theoretical order of magnitude is the same as the experimental one. A very small change of the perihelion advance of the planet orbits is calculated by this model. Meanwhile, this gravitational model is perfectly compatible with restricted relativity and general relativity, and is part of the three element theory, a unifying theory.
FINITE TEMPERATURE MATTER SUBJECT TO STRONG MAGNETIC FIELDS
Authors: MENEZES DÉBORA PERES , AVANCINI SIDNEY SANTOS , PROVIDÊNCIA CONSTANÇA
Published: January 2012

Quark matter at finite temperature and subject to strong magnetic fields is possibly present in the early stages of heavy ion collisions and in the interior of protoneutron stars. We use the mean field approximation to investigate this type of quark matter described by the Nambu–Jona-Lasinio model. The effect of the magnetic field on the effective quark masses and chemical potentials is only felt for quite strong magnetic fields, above 5 × 1018 G , with larger effects for the lower densities. Spin polarizations are more sensitive to weaker magnetic fields and are larger for lower temperatures and lower densities.
ACCRETION OF DARK MATTER IN NEUTRON STARS
Authors: RAZEIRA MOISÉS , MESQUITA ALEXANDRE , VASCONCELLOS CÉSAR A. Z. , GOMES ROSANA O.
Published: January 2012

In this work we study the effect of the accretion of dark matter into neutron stars. We have considered two relativistic nuclear effective models for the structure of neutron stars (ZM and Boguta-Bodmer) and three profiles for dark matter (Navarro-Frenk-White, Einasto, and Burkert). We have analyzed the effects of these effective models and profiles in the equation of state of nuclear matter and in the capture rate of dark matter by neutron stars. Our results confirm that the capture rate of dark matter by neutron stars is strongly model dependent. This leads to more questions than answers due to the uncertainties in the significance of the results, requiring therefore for its elucidation new signatures of capture of dark matter by these stellar objects.
A 2M⊙ PULSAR: IMPLICATIONS FOR QUARK MATTER
Authors: LAI XIAOYU , XU RENXIN
Published: January 2012

The state of cold quark matter at supra-nuclear density, depending on the non-perturbative nature of quantum chromo-dynamics (QCD), is essential for modelling pulsars. It is conventionally thought that the state equation of dense matter softens and thus cannot result in high maximum mass if pulsars are quark stars. However, this standard point of view would be revisited and updated if the strong coupling between quarks at realistic baryon densities of compact stars could render quarks grouped in quark-clusters, because the state equation of clustering quark matter stiffs to support compact stars with maximum mass M max > 2M⊙. Although the hypothetical quark-clusters has not been confirmed due to the lack of both theoretical and experimental evidence, the astrophysical observations of pulsars (e.g. pulsar-mass) could help us to explore the properties of cold quark matter.
NUCLEAR MATTER AND NEUTRON STARS IN A QUARK-HADRON MODEL
Authors: SCHRAMM STEFAN , NEGREIROS RODRIGO P. , SCHÜRHOFF T. , DEXHEIMER VERONICA
Published: January 2012

One of the difficulties in describing chiral symmetry and deconfinement phase transitions in strongly interacting matter at high temperatures as well as at high densities stems from the fact that one has to deal with very different degrees of freedom on both sides of the phase transition. Hadrons exist at low temperatures/densities whereas quarks and gluons occur in the other extreme. Gluing two separate equations of state together will necessarily lead to first-order phase transitions (which are not expected, at least not at small densities and high temperatures). In order to remedy this problem a unified model of quarks and hadrons (the QH model) has been developed that integrates both degrees of freedom in an effective chiral flavor-SU(3) ansatz. Results for nuclear matter and neutron stars for the purely hadronic part of the theory and then results for excited matter and stars for the full QH model are presented. Various extensions of this approach are discussed.
A FINITE NUCLEON EXTENDED VOLUME MODEL FOR NUCLEAR MATTER
Authors: ROCHA ALBERTO S. S. , VASCONCELLOS CÉSAR A. Z. , COELHO HELIO T.
Published: January 2012

We investigate the effects of a finite volume extension for nucleons immersed in nuclear matter. We wish in this way to explore the role played by this non-vanishing (but fixed) volume in shaping nuclear matter properties, in contrast with other models of nuclear physics in which nucleons are treated as point-like particles. We introduce a model characterized by an exclusion volume à la Van der Waals, as well as an effective non-relativistic approximation to model meson-exchange interactions between nucleons. The model is consistent with experimental values of saturation density and binding energy of nuclear matter in the domain of typical densities for neutron stars.
ABOUT THE PHOTON REDSHIFT IN A MAGNETIC FIELD
Authors: PÉREZ ROJAS HUGO , RODRÍGUEZ QUERTS ELIZABETH , HELAYËL-NETO JOSÉ A.
Published: January 2012

Previous results concerning the arising a tiny photon anomalous paramagnetic moment are also interpreted as a red-shift in analogy to the gravitational known effect. It is due to the photon interaction with the magnetized virtual electron-positron background which withdraw transverse momentum from photons and is polarization-dependent. The photon frequency red-shift implies a change in time and a clock would go faster for increasing magnetic field intensity.
PHOTON PROPAGATION IN THE CASIMIR VACUUM
Authors: PARDO VEGA JAVIER , PÉREZ ROJAS HUGO
Published: January 2012

A transformation that relates the Minkowskian space of Quantum Electrodynamics (QED) vacuum between parallel conducting plates and QED at finite temperature is obtained. From this formal analogy, the eigenvalues and eigenvectors of the photon self-energy for the QED vacuum between parallel conducting plates (Casimir vacuum) are found in an approximation independent form. It leads to two different physical eigenvalues and three eigenmodes. We also apply the transformation to derive the low energy photons phase velocity in the Casimir vacuum from its expression in the QED vacuum at finite temperature.
CONSERVED QUANTITIES AND DUALITIES FOR PARTICLES IN CURVED SPACE-TIME
Authors: CABRAL LUÍS A. , CAPISTRANO ABRAÃO J. S.
Published: January 2012

We consider particles moving in curved space-time and associated symmetries. We use a generalized Killing equation and search for solutions involving Killing tensors associated with space-time metric. With these tensors some conserved quantities are constructed and they are valid along particles geodesic. In the Hamiltonian formalism for these particles, the conserved quantities can generate a dual description of the metric. We construct nontrivial dual metrics and consider a kind of geometric duality that involves a completely different space-time. From these metrics we calculate geometric invariants and examine the singularity structure of the dual space-time.
SIMILARITY RENORMALIZATION GROUP EVOLUTION OF NUCLEAR FORCES
Authors: SZPIGEL SÉRGIO , TIMÓTEO VARESE S.
Published: January 2012

In this work we study the similarity renormalization group (SRG) evolution of chiral effective field theory (ChEFT) nucleon-nucleon (NN) interactions derived within the framework of the subtracted kernel method (SKM) approach. We apply the SRG transformation to evolve the leading-order (LO) ChEFT NN potential in the 1S0 and the 3S1-3D1 partial-wave channels and calculate the corresponding phase-shifts.
PROCESS MODEL ONTOLOGY-BASED MATCHMAKING OF SEMANTIC WEB SERVICES
Authors: PAULRAJ D. , SWAMYNATHAN S. , MADHAIYAN M.
Published: January 2012

One of the key challenges of the Service Oriented Architecture is the discovery of relevant services for a given task. In Semantic Web Services, service discovery is generally achieved by using the service profile ontology of OWL-S. Profile of a service is a derived, concise description and not a functional part of the semantic web service. There is no schema present in the service profile to describe the input, output (IO), and the IOs in the service profile are not always annotated with ontology concepts, whereas the process model has such a schema to describe the IOs which are always annotated with ontology concepts. In this paper, we propose a complementary sophisticated matchmaking approach which uses the concrete process model ontology of OWL-S instead of the concise service profile ontology. Empirical analysis shows that high precision and recall can be achieved by using the process model-based service discovery.
MAXIMUM DRAWDOWN INSURANCE
Authors: CARR PETER , ZHANG HONGZHONG , HADJILIADIS OLYMPIA
Published: January 2012

The drawdown of an asset is a risk measure defined in terms of the running maximum of the asset's spot price over some period [0, T]. The asset price is said to have drawn down by at least $K over this period if there exists a time at which the underlying is at least $K below its maximum-to-date. We introduce insurance against a large realization of maximum drawdown and a novel way to hedge the liability incurred by underwriting this insurance. Our proposed insurance pays a fixed amount should the maximum drawdown exceed some fixed threshold over a specified period. The need for this drawdown insurance would diminish should markets rise before they fall. Consequently, we propose a second kind of cheaper maximum drawdown insurance that pays a fixed amount contingent on the drawdown preceding a drawup. We propose double barrier options as hedges for both kinds of insurance against large maximum drawdowns. In fact for the second kind of insurance we show that the hedge is model-free. Since double barrier options do not trade liquidly in all markets, we examine the assumptions under which alternative hedges using either single barrier options or standard vanilla options can be used.
STATISTICAL CAUSES FOR THE EPPS EFFECT IN MICROSTRUCTURE NOISE
Authors: MÜNNIX MICHAEL C. , SCHÄFER RUDI , GUHR THOMAS
Published: January 2012

We present two statistical causes for the distortion of correlations on high-frequency financial data. We demonstrate that the asynchrony of trades as well as the decimalization of stock prices has a large impact on the decline of the correlation coefficients towards smaller return intervals (Epps effect). These distortions depend on the properties of the time series and are of purely statistical origin. We are able to present parameter-free compensation methods, which we validate in a model setup. Furthermore, the compensation methods are applied to high-frequency empirical data from the NYSE's TAQ database. A major fraction of the Epps effect can be compensated. The contribution of the presented causes is particularly high for stocks that are traded at low prices.
FIXED-MIX RULES IN AN EVOLUTIONARY MARKET USING A FACTOR MODEL FOR DIVIDENDS
Authors: MAVROUDIS KONSTANTINOS , NOLDER CRAIG A.
Published: January 2012

In this paper we explore the impact of various constant-proportions investment strategies (or Fixed-Mix Rules) in an economic evolutionary market. Dividends are generated according to a new Dividend Factor Model. Furthermore, dividends are estimated and calibrated from data using Principal Component Analysis. Moreover, we perform simulations to study the long-run outcome of an evolutionary competition with several well diversified constant-proportions strategies, among them some innovative strategies. We present and compare a variety of simulations with dividends being artificially generated according to our Dividend Model. Our simulation results are important for both theoretical and practical reasons. In theoretical terms we extend the existing numerical studies with the estimation and application of a more realistic model for the dividend process. In practical terms we suggest new constant-proportions strategies that could be superior for investors at least in the short run.
COUNTERPARTY RISK FOR CREDIT DEFAULT SWAP WITH STATES RELATED DEFAULT INTENSITY PROCESSES
Authors: TANG DAN , WANG YONGJIN , ZHOU YUZHEN
Published: January 2012

In this paper, the counterparty risk is considered in pricing a Credit Default Swap (abbr. CDS). We adopt an intensity-based reduced form model, in which the default intensity processes of the counterpart and the reference credit are modulated by the credit states of the firms. Two Markov chains are used to describe the credit state processes. We set up a model where the default correlation between the counterpart and the reference is described through the Markov chains. A semi-explicit formula for the pricing of CDS with counterparty risk is obtained. We analyze the impacts of default correlations and the state changes on the CDS price through some numerical experiments.
INTELLIGENT FUZZY WEIGHTED INPUT ESTIMATION METHOD FOR THE DYNAMIC FORCE INPUTS OF A CANTILEVER BEAM MOUNTED WITH CONCENTRATED MASSES
Authors: LEE MING-HUI
Published: January 2012

This study proposes an intelligent fuzzy weighted input estimation method for the force inputs of a cantilever beam structural system. The finite element scheme is employed to discretize the problem in space, allowing multi-dimensional problems of various geometries to be treated. The Kalman filter (KF) and the recursive least square estimator (RLSE) are two main portions of this method. In this method, the efficient estimator is weighted by the fuzzy weighting factor proposed based on the fuzzy logic inference system. By directly synthesizing the Kalman filter with the estimator, this work presents an efficient robust forgetting zone, which is capable of providing a reasonable tradeoff between the tracking capability and the flexibility against noises. The input forces of structural sytem can be estimated by this method to promote the analysis reliability of the dynamic performance. The simulation results are compared by alternating between the constant and adaptive weighting factors. The results demonstrate that the application of the presented method is successful in coping with the dynamic system of cantilever beam.
A PHENOMENOLOGICAL MODEL FOR HYDROGELS WITH RIGID SKIN FORMATION
Authors: KURNIA JUNDIKA CANDRA , BIRGERSSON ERIK , MUJUMDAR ARUN S.
Published: January 2012

A phenomenological model for stimuli sensitive hydrogels immersed in water subject to changes in temperature is presented and analyzed. In short, the model takes into account conservation of mass and momentum for polymer network and interstitial fluid with an expression for permeability to capture the rigid skin formation during shrinking. The nature of this expression is secured from the observation of and validation with experimental deformation kinetics. Overall, good agreement is achieved between model predictions and their experimental counterparts; the rigid skin formation and rigid core presence are also captured reasonably well. The model can be extended to account for arbitrary-shaped hydrogels as well as for other types of stimuli-sensitive hydrogels that exhibit rigid-skin formation during shrinking.
A SPECTRAL/hp NONLINEAR FINITE ELEMENT ANALYSIS OF HIGHER-ORDER BEAM THEORY WITH VISCOELASTICITY
Authors: VALLALA V. P. , PAYETTE G. S. , REDDY J. N.
Published: January 2012

In this paper, a finite element model for efficient nonlinear analysis of the mechanical response of viscoelastic beams is presented. The principle of virtual work is utilized in conjunction with the third-order beam theory to develop displacement-based, weak-form Galerkin finite element model for both quasi-static and fully-transient analysis. The displacement field is assumed such that the third-order beam theory admits C0Lagrange interpolation of all dependent variables and the constitutive equation can be that of an isotropic material. Also, higher-order interpolation functions of spectral/hp type are employed to efficiently eliminate numerical locking. The mechanical properties are considered to be linear viscoelastic while the beam may undergo von Kármán nonlinear geometric deformations. The constitutive equations are modeled using Prony exponential series with general n-parameter Kelvin chain as its mechanical analogy for quasi-static cases and a simple two-element Maxwell model for dynamic cases. The fully discretized finite element equations are obtained by approximating the convolution integrals from the viscous part of the constitutive relations using a trapezoidal rule. A two-point recurrence scheme is developed that uses the approximation of relaxation moduli with Prony series. This necessitates the data storage for only the last time step and not for the entire deformation history.
Telomeres, Atherosclerosis, and the Hemothelium: The Longer View
Authors: Aviv Abraham , Levy Daniel
Published: January 2012

The model we propose to explain the links between atherosclerosis and telomere dynamics (birth telomere length and its age-dependent shortening) in leukocytes takes cues from three facts: atherosclerosis is a disease of the vascular endothelium; the hematopoietic system and the vascular endothelium share a common embryonic origin; interindividual variation in leukocyte telomere length (LTL) in the general population has a genetic explanation. The model posits that LTL dynamics mirror telomere dynamics in hematopoietic stem cells (HSCs), where telomere length is an index of HSC reserves. Diminished HSC reserves at birth, their accelerated attrition rate afterward, or both are are reflected in shortened LTL during adulthood—a phenomenon that confers increased risk for atherosclerosis. We explain how telomere length in HSCs serves as both a biomarker of atherosclerosis and a determinant of its development. Our model comes down to this proposition: Shortened LTL predicts increased atherosclerotic risk because the injurious component of atherosclerosis exceeds the repair capacity of HSC reserves, which largely depend on HSC telomere length.
Stellar Populations and the Star Formation Histories of LSB Galaxies—Part I: Optical and HαImaging
Authors: Schombert James , Maciel Tamela , McGaugh Stacy
Published: January 2012

This paper presents optical and Hαimaging for a large sample of LSB galaxies selected from the PSS-II catalogs (Schombert et al., 1992). As noted in previous work, LSB galaxies span a range of luminosities () and sizes (), although they are consistent in their irregular morphology. Their Hαluminosities (L(Hα)) range from 1036to 1041 ergs s−1(corresponding to a range in star formation, using canonical prescriptions, from 10−5to 1  yr−1). Although their optical colors are at the extreme blue edge for galaxies, they are similar to the colors of dwarf galaxies (Van Zee, 2001) and gas-rich irregulars (Hunter and Elmegreen, 2006). However, their star formation rates per unit stellar mass are a factor of ten less than other galaxies of the same baryonic mass, indicating that they are not simply quiescent versions of more active star-forming galaxies. This paper presents the data, reduction techniques, and new philosophy of data storage and presentation. Later papers in this series will explore the stellar population and star formation history of LSB galaxies using this dataset.
Analysis of the M/M/N/N Queue with Two Types of Arrival Process: Applications to Future Mobile Radio Systems
Authors: Smith Peter J. , Firag Abdulla , Dmochowski Pawel A. , Shafi Mansoor
Published: January 2012

The queueing system considered is essentially a M/M/N/N queue where two types of users compete for the N resources. The users may have different arrival and service rates and are denoted as primary or secondary users. The primary users have priority access to the resources, and three levels of priority are considered: perfect priority, partial priority, and no priority. This system models the recently developed cognitive radio concept, a methodology that has been proposed for future mobile radio systems. In this context, the primary users have certain rights to use the resources, whereas the secondary users must make opportunistic use of the resources without impacting too much on the performance of the primary users. For all priority settings, the mean number of primary and secondary users is derived as are the blocking probabilities for both users. When no priority is given to the primary user, the system collapses to a truncated form of two independent M/M/∞ queues. The product form solution for this special case is known, and, here, these results are given in a novel, compact form. In the case of nonzero priority, the dropping probability for the secondary users is also derived.