bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-Quantum 2D FT Electronic Spectroscopy of Biexcitons in GaAs Quantum Wells
Authors: Stone Katherine W. , Gundogdu Kenan , Turner Daniel B. , Li Xiaoqin , Cundiff Steven T. , Nelson Keith A.
Published: May 2009

Seeing Double

Whereas electrons roam free in a metal, their motion in a semiconductor often correlates with that of the positively charged holes their excitation has left behind. Various spectroscopic techniques have quantified the energetics associated with such electron-hole pairs, termed excitons. However, the higher-order correlations that ensue from exciton-exciton interactions are harder to probe. Now,

Stone
et al.

(p.
1169
) have characterized the dynamics of such exciton pairs, or biexcitons, directly in a gallium arsenide quantum well structure using a sequence of four ultrashort optical pulses with precisely controlled mutual phase relationships.
High-Frequency, Long-Range Coupling Between Prefrontal and Visual Cortex During Attention
Authors: Gregoriou Georgia G. , Gotts Stephen J. , Zhou Huihui , Desimone Robert
Published: May 2009

Attention and Synchrony

Neural activity in the visual cortex becomes synchronized with attention and other behavioral states. However, the source of this synchrony is still unknown.

Gregoriou
et al.

(p.
1207
) tested the hypothesis that synchronized activity from the frontal eye field is one of the causes of the synchrony in monkey visual cortical area V4 during attention. With attention, neural activity in area V4 synchronized with frontal eye field activity when a stimulus fell in a joint receptive field, but did not do so when the fields were not overlapping.
Volcanism, Mass Extinction, and Carbon Isotope Fluctuations in the Middle Permian of China
Authors: Wignall Paul B. , Sun Yadong , Bond David P. G. , Izon Gareth , Newton Robert J. , Védrine Stéphanie , Widdowson Mike , Ali Jason R. , Lai Xulong , Jiang Haishui , Cope Helen , Bottrell Simon H.
Published: May 2009

Middle Permian Extinction

A major extinction in the Middle Permian 260 to 270 million years ago preceded the huge end-Permian extinction.

Wignall
et al.

(p.
1179
) present a detailed analysis of the Middle Permian event from rocks in southwest China. The extinction coincided with extensive nearby volcanic eruptions. A major drop in carbon isotope values followed the extinction event, implying massive disruption of the carbon cycle.
Tenure and the Future of the University
Authors: Clawson Dan
Published: May 2009

Tenure has been eroded by structural pressures, but remains vital to universities that value creativity.
Under the Influence of Hormones

Endocrinology of Social Relationships
Peter T. Ellison and Peter B. Gray, Eds.

Harvard University Press, Cambridge, MA, 2009. 509 pp. $49.95, £36.95, €45. ISBN 9780674031173.
Authors: Adkins-Regan Elizabeth
Published: May 2009

Besides discussing empirical and theoretical findings on the roles of hormones in casual and crucial social interactions, the contributors link their topics to related fields such as reproductive ecology and life-history theory.
Antibody Responses to Recombinant Polyomavirus BK Large T and VP1 Proteins in Young Kidney Transplant Patients
Authors: Bodaghi Sohrab , Comoli Patrizia , Bösch Robert , Azzi Alberta , Gosert Rainer , Leuenberger David , Ginevri Fabrizio , Hirsch Hans H.
Published: May 2009

BK virus (BKV)-specific immunity is critical for polyomavirus-associated nephropathy, but antibody responses are incompletely defined. We compared the hemagglutination inhibition assay (HIA) with immunoglobulin G enzyme immunoassays (EIA) to BKV proteins expressed in baculovirus-infected insect cells. N-terminal, internal, and C-terminal domains of the BKV large T antigen (BKLT) were fused to glutathione
S
-transferase (GST), yielding GST-BKLTD1, GST-BKLTD2, and GST-BKLTD3, respectively. The BKV capsid VP1 was expressed as a GST fusion (BKVP1) or as a native VP1 assembled into viruslike particles (BKVLP). We tested 422 sera from 28 healthy donors (HD), 99 dialysis patients (DP; median age, 15 years; range, 3 to 32 years), and 46 age-matched kidney transplant patients (KTP; median age, 15 years; range, 2 to 33 years). In HD, HIA and BKVLP EIA both yielded a 91.7% seroreactivity, whereas all other EIA responses were lower (BKVP1, 83.3%; BKLTD1, 25%; BKLTD2, 29%; BKLTD3, 40%). HIA titers significantly correlated with EIA levels for BKVLP, BKVP1, and BKLTD1 but not for BKLTD2 or BKLTD3, which were barely above the cutoff. In DP, the seroreactivities of HIA, BKVLP, and BKLTD1 were lower than that in HD (63.6%, 86.9%, and 10.1%, respectively) and they had lower titers (
P
< 0.001). In KTP, seropositivities for BKVLP, BKVP1, and BKLTD1 were 78%, 50%, and 17%, respectively, but anti-BKVLP levels increased significantly in KTP with viruria and viremia, whereas anti-BKLTD1 levels increased after clearing sustained BKV viremia. In conclusion, anti-BKVLP is equivalent to HIA in HD but is more sensitive to determine the BKV serostatus in DP and KTP. In KTP, anti-BKVLP responds to recent BKV viruria and viremia, whereas anti-BKLTD1 may indicate emerging BKV-specific immune control.
A Y526Q Mutation in the Newcastle Disease Virus HN Protein Reduces Its Functional Activities and Attenuates Virus Replication and Pathogenicity
Authors: Khattar Sunil K. , Yan Yongqi , Panda Aruna , Collins Peter L. , Samal Siba K.
Published: May 2009

The hemagglutinin-neuraminidase (HN) protein of
Newcastle disease virus
(NDV) is a multifunctional protein that plays a crucial role in virus infectivity. In this study, using the mesogenic strain Beaudette C (BC), we mutated three conserved amino acids thought to be part of the binding/catalytic active site in the HN protein. We also mutated five additional residues near the proposed active site that are nonconserved between BC and the avirulent strain LaSota. The eight recovered NDV HN mutants were assessed for effects on biological activities. While most of the mutations had surprisingly little effect, mutation at conserved residue Y526 reduced the neuraminidase, receptor binding, and fusion activities and attenuated viral virulence in eggs and young birds.
The Transmembrane Domain of BST-2 Determines Its Sensitivity to Down-Modulation by Human Immunodeficiency Virus Type 1 Vpu
Authors: Rong Liwei , Zhang Jianyong , Lu Jennifer , Pan Qinghua , Lorgeoux René-Pierre , Aloysius Claudette , Guo Fei , Liu Shan-Lu , Wainberg Mark A. , Liang Chen
Published: May 2009

Bone marrow stromal cell antigen 2 (BST-2, also known as tetherin) restricts the production of a number of enveloped viruses by blocking virus release from the cell surface. This antiviral activity is counteracted by such viral factors as Vpu of human immunodeficiency virus type 1 (HIV-1). Here, we report that Vpu antagonizes human BST-2 but not BST-2 derived from African green monkeys. The determinants of susceptibility to Vpu map to the transmembrane domain of BST-2. In accordance with this, expression of human BST-2 containing a modified transmembrane domain effectively blocks the replication of wild-type Vpu-expressing HIV-1 in CD4
+
T cells. Furthermore, these BST-2 variants, as opposed to wild-type human BST-2, are refractory to Vpu-mediated down-regulation as a result of an attenuated interaction with Vpu. In view of the work by others pointing to a key role of the transmembrane domain of Vpu in promoting virus release, our data suggest that a direct interaction through the transmembrane domain of each of these two proteins is a prerequisite for Vpu to down-modulate BST-2.
Baculovirus Induces Type I Interferon Production through Toll-Like Receptor-Dependent and -Independent Pathways in a Cell-Type-Specific Manner
Authors: Abe Takayuki , Kaname Yuuki , Wen Xiaoyu , Tani Hideki , Moriishi Kohji , Uematsu Satoshi , Takeuchi Osamu , Ishii Ken J. , Kawai Taro , Akira Shizuo , Matsuura Yoshiharu
Published: May 2009

Autographa californica
nuclear polyhedrosis virus (AcNPV) is a double-stranded-DNA virus that is pathogenic to insects. AcNPV was shown to induce an innate immune response in mammalian immune cells and to confer protection of mice from lethal viral infection. In this study, we have shown that production of type I interferon (IFN) by AcNPV in murine plasmacytoid dendritic cells (pDCs) and non-pDCs, such as peritoneal macrophages and splenic CD11c
+
DCs, was mediated by Toll-like receptor (TLR)-dependent and -independent pathways, respectively. IFN regulatory factor 7 (IRF7) was shown to play a crucial role in the production of type I IFN by AcNPV not only in immune cells in vitro but also in vivo. In mouse embryonic fibroblasts (MEFs), AcNPV produced IFN-β and IFN-inducible chemokines through TLR-independent and IRF3-dependent pathways, in contrast to the TLR-dependent and IRF3/IRF7-independent production of proinflammatory cytokines. Although production of IFN-β and IFN-inducible chemokines was severely impaired in IFN promoter-stimulator 1 (IPS-1)-deficient MEFs upon infection with vesicular stomatitis virus, AcNPV produced substantial amounts of the cytokines in IPS-1-deficient MEFs. These results suggest that a novel signaling pathway(s) other than TLR- and IPS-1-dependent pathways participates in the production of type I IFN in response to AcNPV infection.
Evidence that Ecotropic Murine Leukemia Virus Contamination in TZM-bl Cells Does Not Affect the Outcome of Neutralizing Antibody Assays with Human Immunodeficiency Virus Type 1
Authors: Platt Emily J. , Bilska Miroslawa , Kozak Susan L. , Kabat David , Montefiori David C.
Published: May 2009

The TZM-bl cell line that is commonly used to assess neutralizing antibodies against human immunodeficiency virus type 1 (HIV-1) was recently reported to be contaminated with an ecotropic murine leukemia virus (MLV) (Y. Takeuchi, M. O. McClure, and M. Pizzato, J. Virol. 82:12585-12588, 2008), raising questions about the validity of results obtained with this cell line. Here we confirm this observation and show that HIV-1 neutralization assays performed with a variety of serologic reagents in a similar cell line that does not harbor MLV yield results that are equivalent to those obtained in TZM-bl cells. We conclude that MLV contamination has no measurable effect on HIV-1 neutralization when TZM-bl cells are used as targets for infection.
Writing a new code of ethics for sports physicians: principles and challenges
Authors: Anderson L
Published: May 2009

A code of ethics for sports physicians needs to be clear, appropriate and practically useful to clinicians in everyday clinical circumstances and for situations that may be difficult or contentious. For a code of ethics to be so apposite requires that it have some basis in the ethical concerns of clinicians. This article reflects on the recent experience of rewriting the code of ethics for the Australasian College of Sports Physicians, describing the findings from the research, the processes and challenges that arose, and providing suggestions for other code writers in this field.
Sludge pretreatment before aerobic digestion to enhance pathogen destructionA paper submitted to the Journal of Environmental Engineering and Science.
Authors: Seaman L. , Sherif R. , Parker Wayne J. , Kennedy K. , Seto P.
Published: May 2009

Bench scale experimentation was completed to assess the potential of using a short residence time pretreatment reactor upstream of aerobic digestion to enhance the destruction of pathogens. The impact of aeration, temperature, hydraulic residence time (HRT), solids concentration, and feeding frequency on the pretreatment process was investigated. Subsequent testing evaluated pathogen destruction resulting from the operation of selected pretreatment conditions in a staged configuration with conventional aerobic digesters. Either highly oxidative or highly reductive conditions were observed to be most effective in reducing the concentrations of E. coli. and Salmonella spp. in the pretreatment reactor. When operated in series with the aerobic digesters, the more highly reducing conditions in pretreatment were found to enhance die-off of the microorganisms in subsequent aerobic digestion compared to the control.
Traitement et stabilisation chimique de déchets d’aluminerie contaminés en ions fluoruresArticles envoyés à la Revue du génie et de la science de l'environnement
Authors: Bongo Ghislain , Mercier Guy , Drogui Patrick , Blais Jean-François
Published: May 2009

Aluminium plant production wastes are contaminated by fluoride according to TCLP (toxicity characteristics leaching procedure) and Quebec legislation (>150 mg F–/L). Those wastes contain 2–323 g F–/kg. The extraction of fluoride by acid leaching (H2SO4, pH 1.5) at total solids content between 1% and 16% allows the removal of approximately 33% of F– but does not respect the TCLP regulation. However, the chemical stabilization of aluminium wastes by use of calcium hydroxide (Ca(OH)2) at a concentration varying from 10 to 12 g/L in the suspension of EC (100 g/L) allowed us to record lower concentrations of fluoride ions (110–115 mg F–/L) in the leachate from the TCLP test. The subsequent treatment of the dehydration filtrate of stabilized residues by decreasing the pH from the initial value (pH 11.9 or 12.0) to pH values between 7.0 and 8.5 by addition of an inorganic acid (H2SO4, 10 mol/L) removed up to 98% of fluoride ions by precipitation.
Mill case, simulation, and laboratory plant study of black liquor spill effects on a multiple stage biological treatment plantA paper submitted to the Journal of Environmental Engineering and Science.
Authors: Sandberg Maria
Published: May 2009

In this study, the impact of black liquor shocks on multiple stage biological treatment plant was studied. The tests were carried out in a lab scale plant and using a mathematical simulation model. The results showed good relation to a parallel situation at the Gruvön Mill. The MultiBio concept is persistent to short-term black liquor spills due to the design where the black liquor is diluted between every compartment. According to the lab scale trials, short-term shocks (5 and 10 h) of black liquor addition reduce bio activity in the first part of the MultiBio plant. Oxygen uptake rate and chemical oxygen demand (COD) degradation decreased during high concentrations of black liquor and increased when the black liquor concentration declined. Protozoas disappeared from compartments exposed to high concentrations of black liquor. A long-term trial encompassing 24 h of black liquor addition inhibited the COD reduction in the whole plant for several weeks.
Simultaneous nitrification and denitrification in non-planted pilot-scale modified vertical flow constructed wetland systemA paper submitted to the Journal of Environmental Engineering and Science.
Authors: Xu Zuxin , Du Xiaoli , Wang Sheng
Published: May 2009

Rural wastewater containing low chemical oxygen demand (COD), but relatively high concentration of total nitrogen comprised of dominant ammonia-nitrogen, was treated in two vertical flow wetland systems whose effluent were discharged intermittently. A substantial loss of total nitrogen (30.3%) was found in a modified wetland system, which introduced an air pipe to enhance oxygen transfer, whereas only a minor loss (17.9%) in the conventional wetland. The correlation between pH, nitrite and nitrate concentrations, ammonia-nitrogen and nitrate-nitrogen distribution along with the depth in the wetlands indicated that the removal of total nitrogen did not follow the classic nitrification and denitrification pathway in the modified wetland system. Through mass balance calculation and theoretical analysis, it was found that simultaneous nitrification and denitrification (SND) was responsible for the transformation of soluble nitrogen into gaseous nitrogen in the modified wetland, thereby causing the loss of total nitrogen. The results showed that SND can be stimulated in aerobic wetland systems and its occurrence may depend on the biofilm thickness, the hydraulic detention time, and the type and population of microorganisms present in the wetland systems.
Remedial measures for debris flows at the Agassiz Mountain Institution, British Columbia
Authors: Martin D. C. , Piteau D. R. , Pearce R. A. , Hawley P. M.
Published: May 2009

On the evening of January 23, 1982 a debris flow having an estimated volume of 11 000 m3 occurred in a stream channel on the south slope of Mount Agassiz adjacent to the Mountain Institution of the Correctional Services of Canada. The debris flow was one of many that have contributed to the formation of a large debris fan at the base of the mountain. Debris flows, large rockfalls, and other events can be expected to occur intermittently as part of the ongoing natural erosional processes in steep mountainous terrain.The paper describes the site investigation and analyses carried out and the design and construction of remedial measures to control future debris flows and rockfalls. Remedial measures consisted of improvement of stability of two large rockfall blocks in the debris flow channel using grouted dowels. In addition, two berms and a containment basin were constructed on the debris fan to control future debris flows and rockfalls. Key words: debris flows, debris fan, rockfalls, rock anchors, dowels, containment basin, deflection berm.
Mineralogy, chemistry, and physical properties interrelationships of some sensitive clays from Eastern Canada
Authors: Locat Jacques , Lefebvre Guy , Ballivy Gérard
Published: May 2009

This paper describes the use of quantitative mineralogy and specific surface area in interpreting the index properties of clayey soils from nine sites in Eastern Canada. Samples representative of the Tyrrell, Laflamme, Champlain, and Goldthwait marine seas and Lac Barlow–Ojibway have been studied.Quantitative X-ray diffraction analyses may be satisfactorily obtained using potassium metaperiodate (Foscal-Mella 1976) as an internal standard in these soils. Determination of contained amorphous matter requires extraction procedures less brutal than those employed in the Ségalen method.Correlations between Atterberg limits and specific surface area are believed to be more useful than those between specific surface area and the grain size or clay fraction. Increases in plasticity and specific surface area are related to increases in the amount of contained phyllosilicates and amorphous matter.The mineralogical composition of the soils studied is dominated, even in the clay fraction, by felsic minerals (plagioclase, quartz, microcline, and hornblende). Samples close to the Canadian Shield contain relatively more felsic minerals than those away from it. Key words: mineralogy, index properties, sensitive clays, physicochemistry.
Diffusion of nonreactive and reactive solutes through fine-grained barrier materials
Authors: Gillham R. W. , Robin M. J. L. , Dytynyshyn D. J. , Johnston H. M.
Published: May 2009

In many cases where fine-grained geologic materials are used as barriers to the migration of contaminated fluids, the principal mechanism of contaminant transport is molecular diffusion. Thus the effective molecular diffusion coefficient is the parameter of greatest importance when predicting migration rates and contaminant fluxes. Diffusion coefficients were measured for two non-reactive solutes (36Cl and 3H) and one reactive solute (85Sr) in seven mixtures of bentonite and silica sand ranging from 0 to 100% bentonite by weight. Tortuosity factors were calculated from the results of the nonreactive diffusion experiments, and retardation factors for the reactive solute from measured distribution coefficient (Kd), bulk density, and porosity values. The results showed the diffusive transport of both the reactive and nonreactive solutes to be consistent with a Fickian diffusion equation. For practical purposes, and at the low values of bulk density used in the experiments, the effective diffusion coefficient of the reactive solute could be calculated with a reasonable degree of certainty from the measured retardation factor and an estimated value of tortuosity. The results showed that because of the interaction between the distribution coefficient, bulk density, and porosity, an increase in clay content beyond about 5–10% did not result in a further reduction of the diffusion coefficient of the reactive solute. Key words: diffusion, adsorption, retardation, tortuosity, clay liners.
DNA passage to nuclei: role of endo-lysosomal circuit in eukaryoticDictyostelium
Authors: Vats Bhavesh , Padh Harish
Published: May 2009

The understanding of DNA passage in eukaryotic cells is still very ambiguous. The route to the nucleus is difficult owing to the barriers, metabolic as well as membranous, posed by the eukaryotic cells. Endocytosis appears to be the most likely process responsible for the transport but is also the major culprit of low transfection efficiencies. Here, we report a study on a eukaryotic amoeba, Dictyostelium discoideum , where by disruption of the endocytic process at the opportune moment, the transformant number increased. We have observed that by disruption of fluid-phase uptake of calcium phosphate DNA nanoparticles, the number of clones increased with the probable increase in number of foreign genes integrating in the host genome. The method described here leads to the possibility of safe and inexpensive methods for transfer of genes required for heterologous recombinant protein production as well as generating therapeutic recombinant cells.
TEMPERATURE DEPENDENCE OF THERMODYNAMIC PROPERTIES OF IONIC SOLIDS
Authors: SHARMA S. K.
Published: May 2009

The present paper proposes a computing model for temperature dependence of volume thermal expansivity, volume expansion ratio and second order temperature derivative of volume based on the assumption that the product αKTremains constant at high temperatures and zero pressure. We have taken NaCl and KCl to testify the validity of the present model. A fairly close agreement between the calculated results and experimental data strongly supports the present model.
BÄCKLUND TRANSFORMATIONS AND LAX PAIRS FOR THE NONLINEAR KLEIN–GORDON EQUATION WITH SYMBOLIC COMPUTATION
Authors: XU XIAO-GE , GAO YI-TIAN , WEI GUANG-MEI
Published: May 2009

In this paper, the nonlinear Klein–Gordon equation describing the propagation of pulse waves in plasma or waveguide is investigated. With symbolic computation, the generalized Bäcklund Transformations (BTs) for this equation are constructed under different conditions. It is shown that the BTs published in the previous literature for the Sine–Gordon equation, Sinh–Gordon equation, and Liouville equation all turn out to be special cases of the results in the present paper. Moreover, the corresponding Lax pairs are explicitly derived from the obtained BTs through some transformations.
PHASE PORTRAITS OF THE QUADRATIC SYSTEMS WITH A POLYNOMIAL INVERSE INTEGRATING FACTOR
Authors: COLL BARTOMEU , FERRAGUT ANTONI , LLIBRE JAUME
Published: May 2009

We classify the phase portraits of all planar quadratic polynomial differential systems having a polynomial inverse integrating factor.
DIFFERENCE EQUATIONS FOR CELLULAR AUTOMATA
Authors: ITOH MAKOTO , CHUA LEON O.
Published: May 2009

In this paper, we propose new difference equations which can generate the evolution rules of cellular automata.
CONVERGENCE OF C0 COMPLEXITY
Authors: CAI ZHIJIE , SUN JIE
Published: May 2009

In this paper, the convergence of C0 complexity is proved, some examples and applications are given to verify the results. From these examples, we can see that C0 complexity can also obtain robust results with short signals, and consequently it can be applied to the nonstationary signals, such as EEG signals.
DYNAMICS OF ELECTROSTATICALLY ACTUATED MICRO-ELECTRO-MECHANICAL SYSTEMS: SINGLE DEVICE AND ARRAYS OF DEVICES
Authors: TAFFOTI YOLONG V. Y. , WOAFO P.
Published: May 2009

The dynamical behavior of micro-electro-mechanical systems (MEMS) with electrostatic coupling is studied. A nonlinear modal analysis approach is applied to decompose the partial differential equation into a set of ordinary differential equations. The stability analysis of the equilibrium points is investigated. The amplitudes of the harmonic oscillatory states in the triple resonant states are obtained and discussed. Chaotic behavior is investigated using bifurcations diagram and the largest Lyapunov exponent. The dynamics of the MEMS with multiple functions in series is also investigated as well as the transitions boundaries for the complete synchronization state in a shift-invariant set of coupled MEMS devices.
IMPROVED CLUSTERING THROUGH HETEROGENEITY IN PREFERENTIAL ATTACHMENT NETWORKS
Authors: SANTIAGO ANTONIO , BENITO ROSA M.
Published: May 2009

In this paper we present a study of the influence of heterogeneity on the clustering of preferential attachment networks. The study is performed by the numerical analysis of the threshold preferential attachment model, a generalization of the Barabási—Albert model to heterogeneous complex networks. Heterogeneous networks are characterized by the existence of intrinsic properties of the nodes which induce specific affinities in their interactions. We analyze the influence of the affinity parameters on the distribution of degree-averaged clustering coefficients of the threshold model. We show that the introduction of heterogeneity increases the inverse correlation between clustering and connectivity of the nodes, inducing a power-law scaling in the clustering distribution. We also show that a higher level of heterogeneity increases the overall clustering coefficients irrespective of the node degrees. These results exhibit a better agreement of the extended model with the empirical observations of clustering in real networks.
LOCAL STABILITY OF CONTINUOUS DYNAMICAL SYSTEMS IN THE PRESENCE OF NONHYPERBOLIC EQUILIBRIA
Authors: BALIBREA F. , MARTINEZ A. , VALVERDE J. C.
Published: May 2009

In this work we analyze what happens when the generalized conditions given in [Balibrea et al., 2008], which produce the appearance of local bifurcations of continuous dynamical systems, fail. As a result, we are able to find out some situations of local stability in the presence of nonhyperbolic equilibria.
HOPF BIFURCATION ANALYSIS OF DIFFUSIVE BASS MODEL WITH DELAY UNDER "NEGATIVE-WORD-OF-MOUTH"
Authors: WIJERATNE A. W. , SU YING , WEI JUNJIE
Published: May 2009

The original Bass product growth model has been modified in this paper by incorporating a diffusion term and a delay. The imitation parameter β is assumed to be negative which represents the effect of "negative-word-of-mouth" (NWOM). The occurrence of Hopf bifurcation at the positive equilibrium of the remaining market growth u* was proved as β passes through a critical value. The analysis of the distribution of eigenvalues led to the following conclusion. The unstable positive equilibrium state at zero diffusion (d = 0) under NWOM becomes stable when d > 0 for a wide range of β. This observation suggests that when there is a critical NWOM, favorable conditions for the future stable state of u* could be achieved by promoting the product in space (new geographical areas).
LOCAL HOPF BIFURCATION OF COMPLEX NONLINEAR SYSTEMS WITH TIME-DELAY
Authors: LI JUN YU , WANG ZAI HUA
Published: May 2009

A Hopf bifurcation can occur commonly in the time-delay systems described by delay differential equations (DDEs), even in first order autonomous DDEs. Compared with the intensive study of Hopf bifurcation for DDEs with real coefficients, which was mainly done using the center manifold reduction, perturbation methods and so on, little effort has been made directly for the Hopf bifurcation of DDEs with complex coefficients. In this paper, a generalization of the newly developed "pseudo-oscillator analysis" for the Hopf bifurcation of scalar real nonlinear DDEs is presented for scalar complex nonlinear DDEs. The main idea of the pseudo-oscillator analysis is to construct a pseudo-oscillator associated with the original system so that the local dynamics near the Hopf bifurcation can be justified by the pseudo-power function of the generated oscillator, in particular, the stability of the bifurcated periodic solution can be determined by the averaged power function. The pseudo-oscillator analysis involves easy computation only and it is more tractable than the current methods. As an application of the method, the Hopf bifurcation of a first order complex DDE and a second order complex DDE is investigated in detail, illustrated with numerical simulation.
A NOVEL APPROACH OF REQUIREMENT GATHERING AND ANALYSIS FOR AGENT ORIENTED SOFTWARE ENGINEERING (AOSE)
Authors: RANJAN PRABHAT , MISRA A. K.
Published: May 2009

In this paper, an agent-based open and adaptive system development process has been proposed which continuously change and evolve to meet new requirements. The proposed methodology is based on a model-based technique that provides a specific model for the type of information to be gathered and uses this model to drive the domain specific analysis process. The focus is on a clear separtion between the requirement gathering and analysis phases. The analysis methodology further splits the analysis phase into the user_centric analysis and the system_centric analysis phases. Optimization of the system performance has also been proposed by exploiting the relationships and dependencies among roles and mapping criteria between roles to agents. The Gaia and ROADMAP models have been used as a basis to the proposed agent-based modeling method.
CHARGED MEMBRANE AS A SOURCE FOR REPULSIVE GRAVITY
Authors: BELINSKI V. A. , PIZZI M. , PAOLINO A.
Published: May 2009

We demonstrate an alternative (with respect to the ones existing in the literature) and more-typical-for-physicists derivation of an exact solution to the Einstein–Maxwell equations for the motion of a charged spherical membrane with tangential tension. We stress that there exists physically acceptable range of parameters for which the static and stable state of the membrane producing the Reissner–Nordstrom (RN) repulsive gravity effect exists. The concrete realization of such a state for the Nambu–Goto membrane is described. The point is that the membrane is able to cut out the central naked singularity region and at the same time join in an appropriate way the RN repulsive region.

As a result we have a model of an everywhere-regular material source exhibiting a repulsive gravitational force in the vicinity of its surface: this construction gives a more sensible physical status to the RN solution in the naked singularity case.
FAMILY FIRM IPO PERFORMANCE AND MARKET SIGNALS
Authors: DING HUNG-BIN , PUKTHUANTHONG-LE KUNTARA
Published: May 2009

Recently, the interests in the performance of family firms in the capital market are on the rise. However studies on long-term performance give us little information about the performance of family firms in the initial public offering (IPO) markets. Building on agency theory, we investigated the effect of three IPO signals in family firm IPOs. Practices such as the appointment of outside non-family directors and waiting longer before going public significantly reduce underpricing. In addition, family owners' intent to retain large percentage of share in the long run is an indication of original shareholders' level of confidence in their own companies. Such confidence helps reduce after market investors' uncertainty and thus underpricing. On the other hand, family ownership at the IPO positively moderates the impact of non-family directors on underpricing.
PERFECT TELEPORTATION OF UNKNOWN QUDIT BY A d-LEVEL GHZ CHANNEL
Authors: LONG YINXIANG , QIU DAOWEN , LONG DONGYANG
Published: May 2009

In the past decades, various schemes of teleportation of quantum states through different types of quantum channels (a prior shared entangled state between the sender and the receiver), e.g. EPR pairs, generalized Bell states, qubit GHZ states, standard W states and its variations, genuine multiqubit entanglement states, etc., have been developed. Recently, three-qutrit quantum states and two-qudit quantum states have also been considered as quantum channels for teleportation. In this paper, we investigate the teleportation of an unknown qudit using a d level GHZ state, i.e. a three-qudit maximally entangled state, as quantum channel. We design a general scheme of faithful teleportation of an unknown qudit using a d-level GHZ state shared between the sender and the receiver, or among the sender, the receiver and the controller; an unknown two-qudit of Schmidt form using a d level GHZ state shared between the sender and the receiver; as well as an unknown arbitrary two-qudit using two shared d level GHZ states between the sender, the receiver and the controller, or using one shared d level GHZ state and one shared generalized Bell state. We obtain the general formulas of Alice's measurement basis, Charlie's measurement basis and Bob's unitary operations to recover the input state of Alice. It is intuitionistic to generalize the protocols of teleporting an arbitrary two-qudit state to teleporting an arbitrary n-qudit state.
ENTANGLEMENT CONTROLLING OF A THREE-LEVEL CASCADE ATOM INTERACTING WITH A TIME-DEPENDENT COHERENT FIELD
Authors: XIE SHUANGYUAN , JIA FEI , YANG YAPING
Published: May 2009

The interaction between a three-level cascade atom and an initial coherent field with a time-varying frequency has been investigated, including the dynamic behavior of the atomic level occupation probabilities and the entanglement between the atom and the field. The frequency of the field is modulated in the forms of sine and rectangle. It is found that the field-frequency variation has a great influence on the properties of the generalized Jaynes-Cummings model. Appropriate frequency modulation can enhance and stabilize the degree of entanglement between the atom and the field.
THE EXCEPTIONAL E8 GEOMETRY OF CLIFFORD (16) SUPERSPACE AND CONFORMAL GRAVITY YANG–MILLS GRAND UNIFICATION
Authors: CASTRO PERELMAN CARLOS
Published: May 2009

We continue to study the Chern–Simons E8 Gauge theory of Gravity developed by the author which is a unified field theory (at the Planck scale) of a Lanczos–Lovelock Gravitational theory with a E8 Generalized Yang–Mills (GYM) field theory, and is defined in the 15D boundary of a 16D bulk space. The Exceptional E8 Geometry of the 256-dim slice of the 256 × 256-dimensional flat Clifford (16) space is explicitly constructed based on a spin connection [Formula: see text], that gauges the generalized Lorentz transformations in the tangent space of the 256-dim curved slice, and the 256 × 256 components of the vielbein field [Formula: see text], that gauge the nonabelian translations. Thus, in one-scoop, the vielbein [Formula: see text] encodes all of the 248 (nonabelian) E8 generators and 8 additional (abelian) translations associated with the vectorial parts of the generators of the diagonal subalgebra [Cl(8) ⊗ Cl(8)] diag ⊂ Cl(16). The generalized curvature, Ricci tensor, Ricci scalar, torsion, torsion vector and the Einstein–Hilbert–Cartan action is constructed. A preliminary analysis of how to construct a Clifford Superspace (that is far richer than ordinary superspace) based on orthogonal and symplectic Clifford algebras is presented. Finally, it is shown how an E8 ordinary Yang–Mills in 8D, after a sequence of symmetry breaking processes E8 → E7 → E6 → SO(8, 2), and performing a Kaluza–Klein–Batakis compactification on CP2, involving a nontrivial torsion, leads to a (Conformal) Gravity and Yang–Mills theory based on the Standard Model in 4D. The conclusion is devoted to explaining how Conformal (super) Gravity and (super) Yang–Mills theory in any dimension can be embedded into a (super) Clifford-algebra-valued gauge field theory.
ISOMETRIES IN HIGHER-DIMENSIONAL CCNV SPACETIMES
Authors: MCNUTT D. , COLEY A. , PELAVAS N.
Published: May 2009

We study the class of higher-dimensional Kundt metrics admitting a covariantly constant null vector, known as CCNV spacetimes. We pay particular attention to those CCNV spacetimes with constant (polynomial) curvature invariants (CSI). We investigate the existence of an additional isometry in CCNV spacetimes, by studying the Killing equations for the general form of the CCNV metric. In particular, we list all CCNV spacetimes allowing an additional non-spacelike isometry for all values of the light-cone coordinate v, which are of interest due to the invariance of the metric under a translation in v. As an application we use our results to find all CSICCNV spacetimes with an additional isometry as well as the subset of these spacetimes in which the isometry is non-spacelike for all values v.
ON 3D HAMILTONIAN SYSTEMS VIA DARBOUX–WEINSTEIN COORDINATES
Authors: TUDORAN RĂZVAN M. , TUDORAN RAMONA A.
Published: May 2009

In this paper we are analyzing the stability of equilibria and also the existence of periodic solutions of three dimensional Hamiltonian systems using Darboux–Weinstein coordinates.
TOPOLOGICAL QUANTUM NUMBERS AND CURVATURE — EXAMPLES AND APPLICATIONS
Authors: SZCZȨSNY JERZY , BIESIADA MAREK , SZYDŁOWSKI MAREK
Published: May 2009

Using the idea of the degree of a smooth mapping between two manifolds of the same dimension we present here the topological (homotopical) classification of the mappings between spheres of the same dimension, vector fields, monopole and instanton solutions. Starting with a review of the elements of Riemannian geometry we also present an original elementary proof of the Gauss–Bonnet theorem and also one of the Poincaré–Hopf theorem.
CONTRASTING E-COMMERCE BUSINESS MODELS: PERFORMANCE IMPLICATIONS FOR SMALL ENTERPRISES
Authors: RASHEED HOWARD S.
Published: May 2009

Pure plays use the Internet as a market entry strategy, and brick and clicks use the Internet as an alternate channel of distribution. Theoretical frameworks from entrepreneurship, marketing, and electronic commerce are used to explore performance differences between these business models. This study uses a geographically diverse sample of 240 small enterprises engaged in Internet-based consumer marketing. Results suggest brick and clicks enjoy performance advantages over pure plays in international revenue growth. Higher Internet promotional expenditures positively impact revenue growth. Firms using the Internet for sales transactions experience negative profit expectations and revenue growth. Firms using the Internet for product distribution experience significant international sales growth. Product depth influences profit expectations and domestic revenue growth. These results should provide a basis for building theory relative to performance implications of Internet-based commerce for small enterprises.
BIOMIMETIC SYSTEMS SHED LIGHT ON ACTIN-BASED MOTILITY DOWN TO THE MOLECULAR SCALE
Authors: ROMET-LEMONNE GUILLAUME , HELFER EMMANUELE , DELATOUR VINCENT , BUGYI BEATA , BOSCH MONTSERRAT , ROMERO STEPHANE , CARLIER MARIE-FRANCE , SCHMIDT STEPHAN , FERY ANDREAS
Published: May 2009

Cell motility, one of the modular activities of living cells, elicits the response of the cell to extra-cellular signals, to move directionally, feed, divide or transport materials. The combined actions of molecular motors and re-modeling of the cytoskeleton generate forces and movement. Here we describe mechanistic approaches of force and movement produced by site-directed assembly of actin filaments. The insight derived from a biochemical analysis of the protein machineries involved in "actin-based motile processes" like cell protrusions, invaginations, organelle propulsion, is used to build reconstituted assays that mimic cellular processes, using several protein machineries known to initiate filament assembly by different mechanisms. Reconstitution of complex self-organized systems presents a broad variety of interests. Reconstituting actin-based movement of a functionalized particle from a minimum number of pure proteins, first used to prove the general thermodynamic principles at work in motility, then was the basis for fully controlled physical measurements of forces produced by polymerization of actin against an obstacle and of the mechanical properties of the resulting polymer arrays. In addition, measurements at the mesoscopic scale (trajectories, velocity, polymer mechanics, fluorescence of specifically labeled components of the actin array, use of mutated proteins) can provide further insight into the molecular mechanisms underlying motility.
THE CYTOSKELETON: AN ACTIVE POLYMER-BASED SCAFFOLD
Authors: SMITH DAVID , GENTRY BRIAN , STUHRMANN BJÖRN , HUBER FLORIAN , STREHLE DAN , BRUNNER CLAUDIA , KOCH DANIEL , STEINBECK MATTHIAS , BETZ TIMO , KÄS JOSEF A.
Published: May 2009

The motility of cells is a multifaceted and complicated cytoskeletal process. Significant inroads can be made into gaining a more detailed understanding, however, by focusing on the smaller, more simple subunits of the motile system in an effort to isolate the essential protein components necessary to perform a certain task. Identification of such functional modules has proven to be an effective means of working towards a comprehensive understanding of complex, interacting systems. By following a bottom-up approach in studying minimal actin-related sub-systems for keratocyte motility, we revealed several fundamentally important effects ranging from an estimation of the force generated by the polymerization of a single actin filament, to assembly dynamics and the production of force and tension of composite actin networks, to the contraction of actin networks or smaller bundled structures by the motor myosin II. While even motile keratocyte fragments represent a far more complex situation than the simple reconstituted systems presented here, clear parallels can be seen between in vivo cell motility and the idealized in vitro functional modules presented here, giving more weight to their continued focus.
S1P5is required for sphingosine 1-phosphate-induced autophagy in human prostate cancer PC-3 cells
Authors: Chang Chi-Lun , Ho Ming-Chih , Lee Po-Huang , Hsu Chi-Yen , Huang Wei-Pang , Lee Hsinyu
Published: May 2009

Sphingosine 1-phosphate (S1P) is a platelet- and endothelial cell-released lysophospholipid that regulates various cellular functions through activating a specific family of G protein-coupled receptors. Both platelet activation and angiogenesis play important roles in cancer development, implying that cancer cells might encounter a large amount of S1P during these processes. Cancer cells, in the meantime, may experience nutrient deprivation and rely on autophagy for early development. Whether extracellular S1P regulates autophagy remains to be tested. In the present work, we investigated whether autophagy is regulated by S1P in PC-3 cells. Through monitoring the modification patterns of LC3 by Western blotting, we demonstrated that autophagy was induced by exogenously applied S1P in PC-3 cells. This observation was further confirmed by fluorescence microscopy using PC-3 cells stably expressing enhanced green fluorescent protein-LC3. By applying small interfering RNA and dihydro-S1P, S1P5activation was found to be involved in this process. Besides, mammalian target of rapamycin signaling was inhibited upon S1P treatment. Taken together, our results suggest that, under serum-starved conditions, S1P further upregulates autophagic activity through S1P5-dependent pathways in PC-3 cells.
Hydrogen sulfide ameliorates hyperhomocysteinemia-associated chronic renal failure
Authors: Sen Utpal , Basu Poulami , Abe Oluwasegun A. , Givvimani Srikanth , Tyagi Neetu , Metreveli Naira , Shah Karan S. , Passmore John C. , Tyagi Suresh C.
Published: May 2009

Elevated level of homocysteine (Hcy), known as hyperhomocysteinemia (HHcy), is associated with end-stage renal diseases. Hcy metabolizes in the body to produce hydrogen sulfide (H2S), and studies have demonstrated a protective role of H2S in end-stage organ failure. However, the role of H2S in HHcy-associated renal diseases is unclear. The present study was aimed to determine the role of H2S in HHcy-associated renal damage. Cystathionine-β-synthase heterozygous (CBS+/−) and wild-type (WT, C57BL/6J) mice with two kidney (2-K) were used in this study and supplemented with or without NaHS (30 μmol/l, H2S donor) in the drinking water. To expedite the HHcy-associated glomerular damage, uninephrectomized (1-K) CBS(+/−) and 1-K WT mice were also used with or without NaHS supplementation. Plasma Hcy levels were elevated in CBS(+/−) 2-K and 1-K and WT 1-K mice along with increased proteinuria, whereas, plasma levels of H2S were attenuated in these groups compared with WT 2-K mice. Interestingly, H2S supplementation increased plasma H2S level and normalized the urinary protein secretion in the similar groups of animals as above. Increased activity of matrix metalloproteinase (MMP)-2 and -9 and apoptotic cells were observed in the renal cortical tissues of CBS(+/−) 2-K and 1-K and WT 1-K mice; however, H2S prevented apoptotic cell death and normalized increased MMP activities. Increased expression of desmin and downregulation of nephrin in the cortical tissue of CBS(+/−) 2-K and 1-K and WT 1-K mice were ameliorated with H2S supplementation. Additionally, in the kidney tissues of CBS(+/−) 2-K and 1-K and WT 1-K mice, increased superoxide (O2•−) production and reduced glutathione (GSH)-to-oxidized glutathione (GSSG) ratio were normalized with exogenous H2S supplementation. These results demonstrate that HHcy-associated renal damage is related to decreased endogenous H2S generation in the body. Additionally, here we demonstrate with evidence that H2S supplementation prevents HHcy-associated renal damage, in part, through its antioxidant properties.
S6 kinase 1 knockout inhibits uninephrectomy- or diabetes-induced renal hypertrophy
Authors: Chen Jian-Kang , Chen Jianchun , Thomas George , Kozma Sara C. , Harris Raymond C.
Published: May 2009

Removal of one kidney stimulates synthesis of RNA and protein, with minimal DNA replication, in all nephron segments of the remaining kidney, resulting in cell growth (increase in cell size) with minimal cell proliferation (increase in cell number). In addition to the compensatory renal hypertrophy caused by nephron loss, pathophysiological renal hypertrophy can occur as a consequence of early uncontrolled diabetes. However, the molecular mechanism underlying renal hypertrophy in these conditions remains unclear. In the present study, we report that deletion of S6 kinase 1 (S6K1) inhibited renal hypertrophy seen following either contralateral nephrectomy or induction of diabetes. In wild-type mice, hypertrophic stimuli increased phosphorylation of 40S ribosomal protein S6 (rpS6), a known target of S6K1. Immunoblotting analysis revealed that S6K1−/−mice exhibited moderately elevated basal levels of rpS6, which did not increase further in response to the hypertrophic stimuli. Northern blotting indicated a moderate upregulation of S6K2 expression in the kidneys of S6K1−/−mice. Phosphorylation of the eukaryotic translation initiation factor 4E-binding protein 1, another downstream target of the mammalian target of rapamycin (mTOR), was stimulated to equivalent levels in S6K1−/−and S6K1+/+littermates during renal hypertrophy, indicating that mTOR was still activated in the S6K1−/−mice. The highly selective mTOR inhibitor, rapamycin, inhibited increased phosphorylation of rpS6 and blocked 60–70% of the hypertrophy seen in wild-type mice but failed to prevent the ∼10% hypertrophy seen in S6K1−/−mice in response to uninephrectomy (UNX) although it did inhibit the basal rpS6 phosphorylation. Thus the present study provides the first genetic evidence that S6K1 plays a major role in the development of compensatory renal hypertrophy as well as diabetic renal hypertrophy and indicates that UNX- and diabetes-mediated mTOR activation can selectively activate S6K1 without activating S6K2.