bluuebunny/crossref_metadata_2025 huggingface dataset:
Renal Artery Stent Bending Fatigue Analysis
Authors: Hsiao H. M. , Prabhu S. , Nikanorov A. , Razavi M.
Published: May 2007

During normal breathing, the kidneys move up and down due to the diaphragm motion and the renal artery subsequently experiences bending. Whether bending of the renal artery during respiration impacts stent bending fatigue was not previously known. This study presents the first evaluation of the effect of the kidney movement on renal stent bending fatigue performance. Measurements of fluoroscopic images demonstrated a minor (1.7deg) change in bending angle between inspiration and expiration for an 18mm long renal stent after removing rigid-body motion. Finite element analysis revealed excellent fatigue resistance of the studied renal stent under simulated respiratory motion.
CCR5Δ32 Protein Expression and Stability Are Critical for Resistance to Human Immunodeficiency Virus Type 1 In Vivo
Authors: Agrawal Lokesh , Jin Qingwen , Altenburg Jeff , Meyer L. , Tubiana R. , Theodorou Ioannis , Alkhatib Ghalib
Published: May 2007

Human immunodeficiency virus type 1 (HIV-1) infection of individuals carrying the two alleles of the CCR5Δ32 mutation (CCR5−/−) has rarely been reported, but how the virus overcomes theCCR5Δ32protective effect in these cases has not been delineated. We have investigated this in 6 infected (HIV+) and 25 HIV−CCR5−/−individuals. CD4+T lymphocytes isolated from HIV−CCR5−/−peripheral blood mononuclear cells (PBMCs) showed lower levels of CXCR4 expression that correlated with lower X4 Env-mediated fusion. Endogenous CCR5Δ32 protein was detected in all HIV−CCR5−/−PBMC samples (n= 25) but not in four of six unrelated HIV+CCR5−/−PBMC samples. Low levels were detected in another two HIV+CCR5−/−PBMC samples. The expression of adenovirus 5 (Ad5)-encoded CCR5Δ32 protein restored the protective effect in PBMCs from three HIV+CCR5−/−individuals but failed to restore the protective effect in PBMCs isolated from another three HIV+CCR5−/−individuals. In the latter samples, pulse-chase analyses demonstrated the disappearance of endogenous Ad5-encoded CCR5Δ32 protein and the accumulation of Ad5-encoded CCR5 during the chase periods. PBMCs isolated from CCR5−/−individuals showed resistance to primary X4 but were readily infected by a lab-adapted X4 strain. Low levels of Ad5-encoded CCR5Δ32 protein conferred resistance to primary X4 but not to lab-adapted X4 virus. These data provide strong support for the hypothesis that the CCR5Δ32 protein actively confers resistance to HIV-1 in vivo and suggest that the loss or reduction of CCR5Δ32 protein expression may account for HIV-1 infection of CCR5−/−individuals. The results also suggest that other cellular or virally induced factors may be involved in the stability of CCR5Δ32 protein.
The Neutralizing Activity of Anti-Hepatitis C Virus Antibodies Is Modulated by Specific Glycans on the E2 Envelope Protein
Authors: Helle François , Goffard Anne , Morel Virginie , Duverlie Gilles , McKeating Jane , Keck Zhen-Yong , Foung Steven , Penin François , Dubuisson Jean , Voisset Cécile
Published: May 2007

Hepatitis C virus (HCV) envelope glycoproteins are highly glycosylated, with up to 5 and 11 N-linked glycans on E1 and E2, respectively. Most of the glycosylation sites on HCV envelope glycoproteins are conserved, and some of the glycans associated with these proteins have been shown to play an essential role in protein folding and HCV entry. Such a high level of glycosylation suggests that these glycans can limit the immunogenicity of HCV envelope proteins and restrict the binding of some antibodies to their epitopes. Here, we investigated whether these glycans can modulate the neutralizing activity of anti-HCV antibodies. HCV pseudoparticles (HCVpp) bearing wild-type glycoproteins or mutants at individual glycosylation sites were evaluated for their sensitivity to neutralization by antibodies from the sera of infected patients and anti-E2 monoclonal antibodies. While we did not find any evidence that N-linked glycans of E1 contribute to the masking of neutralizing epitopes, our data demonstrate that at least three glycans on E2 (denoted E2N1, E2N6, and E2N11) reduce the sensitivity of HCVpp to antibody neutralization. Importantly, these three glycans also reduced the access of CD81 to its E2 binding site, as shown by using a soluble form of the extracellular loop of CD81 in inhibition of entry. These data suggest that glycans E2N1, E2N6, and E2N11 are close to the binding site of CD81 and modulate both CD81 and neutralizing antibody binding to E2. In conclusion, this work indicates that HCV glycans contribute to the evasion of HCV from the humoral immune response.
Inhibition of Interferon Regulatory Factor 7 (IRF7)-Mediated Interferon Signal Transduction by the Kaposi's Sarcoma-Associated Herpesvirus Viral IRF Homolog vIRF3
Authors: Joo Chul Hyun , Shin Young C. , Gack Michaela , Wu Liguo , Levy David , Jung Jae U.
Published: May 2007

Upon viral infection, the major defense mounted by the host immune system is activation of the interferon (IFN)-mediated antiviral pathway that is mediated by IFN regulatory factors (IRFs). In order to complete their life cycle, viruses must modulate the host IFN-mediated immune response. Kaposi's sarcoma-associated herpesvirus (KSHV), a human tumor-inducing herpesvirus, has developed a unique mechanism for antagonizing cellular IFN-mediated antiviral activity by incorporating viral homologs of the cellular IRFs, called vIRFs. Here, we report a novel immune evasion mechanism of KSHV vIRF3 to block cellular IRF7-mediated innate immunity in response to viral infection. KSHV vIRF3 specifically interacts with either the DNA binding domain or the central IRF association domain of IRF7, and this interaction leads to the inhibition of IRF7 DNA binding activity and, therefore, suppression of alpha interferon (IFN-α) production and IFN-mediated immunity. Remarkably, the central 40 amino acids of vIRF3, containing the double α helix motifs, are sufficient not only for binding to IRF7, but also for inhibiting IRF7 DNA binding activity. Consequently, the expression of the double α helix motif-containing peptide effectively suppresses IRF7-mediated IFN-α production. This demonstrates a remarkably efficient means of viral avoidance of host antiviral activity.
Matrix Fibronectin Binds Gammaretrovirus and Assists in Entry: New Light on Viral Infections
Authors: Beer Christiane , Pedersen Lene
Published: May 2007

A major entry route for the gammaretrovirus amphotropic murine leukemia virus (A-MLV) into NIH 3T3 fibroblasts is via caveola-dependent endocytosis. However, during the infection time, few viral particles can be observed intracellularly. Analyzing the dynamics of the A-MLV infection process by using total internal reflection fluorescence microscopy, we show that the majority of viruses are extracellular and bound to the fibronectin matrix. Moreover, the amounts of bound virus and of fibronectin correlated. Using confocal microscopy, nanoparticles targeted to fibronectin by a III1C-fibronectin fragment or anti-fibronectin antibody were detected intracellularly in NIH 3T3 cells; unconjugated nanoparticles neither bound to cells nor were detectable intracellularly. Furthermore, A-MLV colocalized intracellularly with the fibronectin-targeted nanoparticles, suggesting that they were taken up by the same cellular pathway. Both A-MLV entry and fibronectin turnover depend on caveolar endocytosis, and we found that inhibiting viral binding to the extracellular NIH 3T3 fibronectin-matrix dramatically reduced A-MLV infection, indeed, showing an active role of fibronectin in infection. We suggest that binding to the cellular fibronectin matrix provides a new mechanism by which viruses can enter cells.
Guinea Pig-Adapted Foot-and-Mouth Disease Virus with Altered Receptor Recognition Can Productively Infect a Natural Host
Authors: Núñez José I. , Molina Nicolas , Baranowski Eric , Domingo Esteban , Clark Stuart , Burman Alison , Berryman Stephen , Jackson Terry , Sobrino Francisco
Published: May 2007

We report that adaptation to infect the guinea pig did not modify the capacity of foot-and-mouth disease virus (FMDV) to kill suckling mice and to cause an acute and transmissible disease in the pig, an important natural host for this pathogen. Adaptive amino acid replacements (I248→T in 2C, Q44→R in 3A, and L147→P in VP1), selected upon serial passages of a type C FMDV isolated from swine (biological clone C-S8c1) in the guinea pig, were maintained after virus multiplication in swine and suckling mice. However, the adaptive replacement L147→P, next to the integrin-binding RGD motif at the GH loop in VP1, abolished growth of the virus in different established cell lines and modified its antigenicity. In contrast, primary bovine thyroid cell cultures could be productively infected by viruses with replacement L147→P, and this infection was inhibited by antibodies to αvβ6 and by an FMDV-derived RGD-containing peptide, suggesting that integrin αvβ6 may be used as a receptor for these mutants in the animal (porcine, guinea pig, and suckling mice) host. Substitution T248→N in 2C was not detectable in C-S8c1 but was present in a low proportion of the guinea pig-adapted virus. This substitution became rapidly dominant in the viral population after the reintroduction of the guinea pig-adapted virus into pigs. These observations illustrate how the appearance of minority variant viruses in an unnatural host can result in the dominance of these viruses on reinfection of the original host species.
Protein Kinase PKR Plays a Stimulus- and Virus-Dependent Role in Apoptotic Death and Virus Multiplication in Human Cells
Authors: Zhang Ping , Samuel Charles E.
Published: May 2007

The protein kinase regulated by double-stranded RNA (dsRNA), PKR, is implicated in a range of biologic processes, including apoptotic death and interferon antiviral responses, based in part on studies with mouse cells genetically deficient inPkr. To test the role of the PKR protein in human cells, an RNA interference silencing strategy was used to generate stable HeLa cell lines with less than 2% of the PKR protein (PKR deficient) compared to either parental or control knockdown HeLa lines. Phosphorylation of the α subunit of eukaryotic initiation factor 2 on serine 51 was not detectably increased in response to dsRNA in PKR-deficient HeLa cells but was elevated severalfold in PKR-sufficient cells. PKR-deficient cells displayed reduced dsRNA-induced apoptosis compared to PKR-sufficient cell lines, whereas tumor necrosis factor alpha (TNF-α)-induced apoptosis was comparable between the HeLa lines. NF-κB was activated to a comparable extent in PKR-deficient and PKR-sufficient HeLa cells upon treatment with either dsRNA or TNF-α. The antiviral response against vesicular stomatitis virus was reduced in interferon-treated PKR-deficient compared to PKR-sufficient HeLa cells. However, the growth of two human viruses, adenovirus and reovirus, was unaffected by the PKR knockdown. Surprisingly, the yield of mutant adenovirus that fails to encode VAI RNA was not enhanced in PKR-deficient cells, indicating the importance of host factors in addition to PKR in conferring the VAI RNA phenotype.
Identification of Nonessential Regions of the nsp2 Replicase Protein of Porcine Reproductive and Respiratory Syndrome Virus Strain VR-2332 for Replication in Cell Culture
Authors: Han Jun , Liu Gongping , Wang Yue , Faaberg Kay S.
Published: May 2007

The nonstructural protein 2 (nsp2) of porcine reproductive and respiratory syndrome virus (PRRSV) is a multidomain protein and has been shown to undergo remarkable genetic variation, primarily in its middle region, while exhibiting high conservation in the N-terminal putative protease domain and the C-terminal predicted transmembrane region. A reverse genetics system of PRRSV North American prototype VR-2332 was developed to explore the importance of different regions of nsp2 for viral replication. A series of mutants with in-frame deletions in the nsp2 coding region were engineered, and infectious viruses were subsequently recovered from transfected cells and further characterized. The results demonstrated that the cysteine protease domain (PL2), the PL2 downstream flanking sequence (amino acids [aa] 181 to 323), and the putative transmembrane domain were critical for replication. In contrast, the segment of nsp2 preceding the PL2 domain (aa 13 to 35) was dispensable for viral replication, and the nsp2 middle hypervariable region (aa 324 to 813) tolerated 100-aa or 200-aa deletions but could not be removed as a whole; the largest deletion was about 400 aa (nsp2Δ324-726). Characterization of the mutants demonstrated that those with small deletions possessed growth kinetics and RNA expression profiles similar to those of the parental virus, while the nsp2Δ324-726 mutant displayed decreased cytolytic activity on MARC-145 cells and did not develop visible plaques. Finally, the utilization of the genetic flexibility of nsp2 to express foreign genes was examined by inserting the gene encoding green fluorescent protein (GFP) in frame into one nsp2 deletion mutant construct. The recombinant virus was viable but impaired and unstable and gradually gained parental growth kinetics by the loss of most of the GFP gene.
Human Parainfluenza Viruses hPIV1 and hPIV3 Bind Oligosaccharides with α2-3-Linked Sialic Acids That Are Distinct from Those Bound by H5 Avian Influenza Virus Hemagglutinin
Authors: Amonsen Mary , Smith David F. , Cummings Richard D. , Air Gillian M.
Published: May 2007

We investigated the binding of human parainfluenza virus types 1 and 3 (hPIV1 and hPIV3, respectively) to the glycan array of the Consortium for Functional Glycomics and binding and their release from erythrocytes under conditions where neuraminidase is inactive or active. hPIV1 and hPIV3 bind modifications of Neu5Acα2-3Galβ1-4GlcNAc, including the sialyl-Lewisxmotif and structures containing 6-sulfogalactose. hPIV1 and hPIV3 thus bind typical N-linked glycans, in contrast to avian influenza virus H5 hemagglutinin (J. Stevens, O. Blixt, T. M. Tumpey, J. K. Taubenberger, J. C. Paulson, and I. A. Wilson, Science 312:404-410, 2006), which binds less-common motifs. While the receptor is not the sole determinant of tropism, hPIV or H5 influenza virus infection of specific cells that express receptors may contribute to their different pathologies.
Cytomegalovirus Destruction of Focal Adhesions Revealed in a High-Throughput Western Blot Analysis of Cellular Protein Expression
Authors: Stanton R. J. , McSharry B. P. , Rickards C. R. , Wang E. C. Y. , Tomasec P. , Wilkinson G. W. G.
Published: May 2007

Human cytomegalovirus (HCMV) systematically manages the expression of cellular functions, rather than exerting the global shutoff of host cell protein synthesis commonly observed with other herpesviruses during the lytic cycle. While microarray technology has provided remarkable insights into viral control of the cellular transcriptome, HCMV is known to encode multiple mechanisms for posttranscriptional and posttranslation regulation of cellular gene expression. High-throughput Western blotting (BD Biosciences Powerblot technology) with 1,009 characterized antibodies was therefore used to analyze and compare the effects of infection with attenuated high-passage strain AD169 and virulent low-passage strain Toledo at 72 hpi across gels run in triplicate for each sample. Six hundred ninety-four proteins gave a positive signal in the screen, of which 68 from strain AD169 and 71 from strain Toledo were defined as being either positively or negatively regulated by infection with the highest level of confidence (BD parameters). In follow-up analyses, a subset of proteins was selected on the basis of the magnitude of the observed effect or their potential to contribute to defense against immune recognition. In analyses performed at 24, 72, and 144 hpi, connexin 43 was efficiently downregulated during HCMV infection, implying a breakdown of intercellular communication. Mitosis-associated protein Eg-5 was found to be differentially upregulated in the AD169 and Toledo strains of HCMV. Focal adhesions link the actin cytoskeleton to the extracellular matrix and have key roles in initiating signaling pathways and substrate adhesion and regulating cell migration. HCMV suppressed expression of the focal-adhesion-associated proteins Hic-5, paxillin, and α-actinin. Focal adhesions were clearly disrupted in HCMV-infected fibroblasts, with their associated intracellular and extracellular proteins being dispersed. Powerblot shows potential for rapid screening of the cellular proteome during HCMV infection.
Human Immunodeficiency Virus Type 1 Vif Inhibits Packaging and Antiviral Activity of a Degradation-Resistant APOBEC3G Variant
Authors: Opi Sandrine , Kao Sandra , Goila-Gaur Ritu , Khan Mohammad A. , Miyagi Eri , Takeuchi Hiroaki , Strebel Klaus
Published: May 2007

Human immunodeficiency virus type 1 (HIV-1) Vif counteracts the antiviral activity of the human cytidine deaminase APOBEC3G (APO3G) by inhibiting its incorporation into virions. This has been attributed to the Vif-induced degradation of APO3G by cytoplasmic proteasomes. We recently demonstrated that although APO3G has a natural tendency to form RNA-dependent homo-multimers, multimerization was not essential for encapsidation into HIV-1 virions or antiviral activity. We now demonstrate that a multimerization-defective APO3G variant (APO3G C97A) is able to assemble into RNase-sensitive high-molecular-mass (HMM) complexes, suggesting that homo-multimerization of APO3G and assembly into HMM complexes are unrelated RNA-dependent processes. Interestingly, APO3G C97A was highly resistant to Vif-induced degradation even though the two proteins were found to interact in coimmunoprecipitation experiments and exhibited partial colocalization in transfected HeLa cells. Surprisingly, encapsidation and antiviral activity of APO3G C97A were both inhibited by Vif despite resistance to degradation. These results demonstrate that targeting of APO3G to proteasome degradation and interference with viral encapsidation are distinct functional properties of Vif.
Work-related injury among direct care occupations in British Columbia, Canada
Authors: Alamgir Hasanat , Cvitkovich Yuri , Yu Shicheng , Yassi Annalee
Published: May 2007

Objectives:

To examine how injury rates and injury types differ across direct care occupations in relation to the healthcare settings in British Columbia, Canada.

Methods:

Data were derived from a standardised operational database in three BC health regions. Injury rates were defined as the number of injuries per 100 full-time equivalent FTE positions. Poisson regression, with Generalised Estimating Equations, was used to determine injury risks associated with direct care occupations registered nurses RNs, licensed practical nurses LPNs and care aides CAs by healthcare setting acute care, nursing homes and community care.

Results:

CAs had higher injury rates in every setting, with the highest rate in nursing homes 37.0 injuries per 100 FTE. LPNs had higher injury rates 30.0 within acute care than within nursing homes. Few LPNs worked in community care. For RNs, the highest injury rates 21.9 occurred in acute care, but their highest 13.0 musculoskeletal injury MSI rate occurred in nursing homes. MSIs comprised the largest proportion of total injuries in all occupations. In both acute care and nursing homes, CAs had twice the MSI risk of RNs. Across all settings, puncture injuries were more predominant for RNs 21.3 of their total injuries compared with LPNs 14.4 and CAs 3.7. Skin, eye and respiratory irritation injuries comprised a larger proportion of total injuries for RNs 11.1 than for LPNs 7.2 and CAs 5.1.

Conclusions:

Direct care occupations have different risks of occupational injuries based on the particular tasks and roles they fulfil within each healthcare setting. CAs are the most vulnerable for sustaining MSIs since their job mostly entails transferring and repositioning tasks during patient/resident/client care. Strategies should focus on prevention of MSIs for all occupations as well as target puncture and irritation injuries for RNs and LPNs.
External radiation exposure and mortality in a cohort of French nuclear workers
Authors: Telle-Lamberton M , Samson E , Caër S , Bergot D , Bard D , Bermann F , MGélas J , Giraud J M , Hubert P , Metz-Flamant C , Néron M O , Quesne B , Tirmarche M , Hill C
Published: May 2007

Objective:

To analyse the effect of external radiation exposure on the mortality of French nuclear workers.

Methods:

A cohort of 29 204 workers employed between 1950 and 1994 at the French Atomic Energy Commission (Commissariat à l’Energie Atomique (CEA)) or at the General Company of Nuclear Fuel (COmpagnie GEnérale des MAtières nucléaires (Cogema, now Areva NC)) was followed up for an average of 17.8 years. Standardised mortality ratios (SMRs) were computed with reference to French mortality rates. Dose-effect relationship were analysed through trend tests and Poisson regression, with linear and log-linear models.

Results:

The mean exposure to X and gamma radiation was 8.3 mSv (16.9 mSv for exposed worker population). A total of 1842 deaths occurred between 1968 and 1994. A healthy worker effect was observed, the number of deaths in the cohort being 59% of the number expected from national mortality statistics. Among the 21 main cancer sites studied, a statistically significant excess was observed only for skin melanoma, and an excess of borderline statistical significance was observed for multiple myeloma. A dose-effect relationship was observed for leukaemia after exclusion of chronic lymphoid leukaemia (CLL). The relative risk observed for non-CLL leukaemia, n = 20, was 4.1 per 100 mSv (90% CI 1.4 to 12.2), linear model and 2.2 per 100 mSv (90% CI 1.2 to 3.3), log-linear model. Significant dose-effect relationship were also observed for causes of deaths associated with alcohol consumption: mouth and pharynx cancer, cirrhosis and alcoholic psychosis and external causes of death.

Conclusion:

The risk of leukaemia increases with increasing exposure to external radiation; this is consistent with published results on other nuclear workers cohorts.
CARBON NANOTUBE BASED NONVOLATILE MEMORY DEVICES
Authors: ZHANG YUEGANG
Published: May 2007

The technology progress and increasing high density demand have driven the nonvolatile memory devices into nanometer scale region. There is an urgent need of new materials to address the high programming voltage and current leakage problems in the current flash memory devices. As one of the most important nanomaterials with excellent mechanical and electronic properties, carbon nanotube has been explored for various nonvolatile memory applications. While earlier proposals of "bucky shuttle" memories and nanoelectromechanical memories remain as concepts due to fabrication difficulty, recent studies have experimentally demonstrated various prototypes of nonvolatile memory cells based on nanotube field-effect-transistor and discrete charge storage bits, which include nano-floating gate memory cells using metal nanocrystals, oxide-nitride-oxide memory stack, and more simpler trap-in-oxide memory devices. Despite of the very limited research results, distinct advantages of high charging efficiency at low operation voltage has been demonstrated. Single-electron charging effect has been observed in the nanotube memory device with quantum dot floating gates. The good memory performance even with primitive memory cells is attributed to the excellent electrostatic coupling of the unique one-dimensional nanotube channel with the floating gate and the control gate, which gives extraordinary charge sensibility and high current injection efficiency. Further improvement is expected on the retention time at room temperature and programming speed if the most advanced fabrication technology were used to make the nanotube based memory cells.
SINGLE-WALLED CARBON NANOTUBES: APPLICATIONS IN HIGH FREQUENCY ELECTRONICS
Authors: BURKE P. J. , RUTHERGLEN C. , YU Z.
Published: May 2007

In this paper, we review the potential applications of single-walled carbon nanotubes in three areas: passives (interconnects), actives (transistors), and antennas. In the area of actives, potential applications include transistors for RF and microwave amplifiers, mixers, detectors, and filters. We review the experimental state of the art, and present the theoretical predictions (where available) for ultimate device performance. In addition, we discuss fundamental parameters such as dc resistance as a function of length for individual, single-walled carbon nanotubes.
SPLITTING OF MACROSCOPIC FUNDAMENTAL STRINGS IN FLAT SPACE AND HOLOGRAPHIC HADRON DECAYS
Authors: BIGAZZI F. , COTRONE A. L. , MARTUCCI L. , TROOST W.
Published: May 2007

In this review we present the calculation of the splitting rate in flat space of a macroscopic fundamental string either intersecting at a generic angle a Dp-brane or lying on it. The result is then applied, in the context of the string/gauge theory correspondence, to the study of exclusive decay rates of large spin mesons into mesons. As examples, we discuss the cases of [Formula: see text] SYM with a small number of flavors, and of QCD-like theories in the quenched approximation. In the latter context, explicit analytic formulas are given for decay rates of mesons formed either by heavy quarks or by massless quarks.
EXPONENTIAL STABILIZATION OF THE INERTIA WHEEL PENDULUM USING DYNAMIC SURFACE CONTROL
Authors: QAISER NADEEM , IQBAL NAEEM , HUSSAIN AMIR , QAISER NAEEM
Published: May 2007

This paper considers the stabilization problem of Inertia Wheel Pendulum, a widely studied benchmark nonlinear system. It is a classical example of a flat underactuated mechanical system, for which the design of control law becomes a challenging task owing to its underactuated nature. A novel nonlinear controller design, fusing the recently introduced Dynamic Surface Control and the Control Lyapunov Function method, is presented as the solution. Stability is analyzed using concepts from Singular Perturbation Theory. The proposed design procedure is shown to be simpler and more intuitive than existing designs. Advantages over conventional Energy Shaping and Backstepping controllers are analyzed theoretically and verified using numerical simulations.
A NEW ACTIVE NETWORK SUITABLE FOR REALIZING LADDER FILTERS AND TRANSFORMER SIMULATOR
Authors: YUCE ERKAN , MINAEI SHAHRAM
Published: May 2007

A general configuration suitable for realizing low-pass and high-pass ladder filters and transformer simulator, depending on the passive element selection is proposed. The proposed network employs only grounded passive components without requiring matching conditions. The values of the synthetic inductances of the transformer and low-pass ladder filter can be changed independently. SPICE simulation results confirming the theoretical analysis are included.
THE DIRICHLET HOPF ALGEBRA OF ARITHMETICS
Authors: FAUSER BERTFRIED , JARVIS P. D.
Published: May 2007

Many constructs in mathematical physics entail notational complexities, deriving from the manipulation of various types of index sets which often can be reduced to labelling by various multisets of integers. In this work, we develop systematically the "Dirichlet Hopf algebra of arithmetics" by dualizing the addition and multiplication maps. Then we study the additive and multiplicative antipodal convolutions which fail to give rise to Hopf algebra structures, but form only a weaker Hopf gebra obeying a weakened homomorphism axiom. A careful identification of the algebraic structures involved is done featuring subtraction, division and derivations derived from coproducts and chochains using branching operators. The consequences of the weakened structure of a Hopf gebra on cohomology are explored, showing this has major impact on number theory. This features multiplicativity versus complete multiplicativity of number theoretic arithmetic functions. The deficiency of not being a Hopf algebra is then cured by introducing an "unrenormalized" coproduct and an "unrenormalized" pairing. It is then argued that exactly the failure of the homomorphism property (complete multiplicativity) for non-coprime integers is a blueprint for the problems in quantum field theory (QFT) leading to the need for renormalization. Renormalization turns out to be the morphism from the algebraically sound Hopf algebra to the physical and number theoretically meaningful Hopf gebra (literally: antipodal convolution). This can be modelled alternatively by employing Rota–Baxter operators. We stress the need for a characteristic-free development where possible, to have a sound starting point for generalizations of the algebraic structures. The last section provides three key applications: symmetric function theory, quantum (matrix) mechanics, and the combinatorics of renormalization in QFT which can be discerned as functorially inherited from the development at the number-theoretic level as outlined here. Hence the occurrence of number theoretic functions in QFT becomes natural.
CASSON KNOT INVARIANTS OF PERIODIC KNOTS WITH RATIONAL QUOTIENTS
Authors: JANG HEE JEONG , LEE SANG YOUL , SEO MYOUNGSOO
Published: May 2007

We give a formula for the Casson knot invariant of a p-periodic knot in S3 whose quotient link is a 2-bridge link with Conway's normal form C(2, 2n1, -2, 2n2, …, 2n2m, 2) via the integers p, n1, n2, …, n2m(p ≥ 2 and m ≥ 1). As an application, for any integers n1, n2, ≥, n2m with the same sign, we determine the Δ-unknotting number of a p-periodic knot in S3 whose quotient is a 2-bridge link C(2, 2n1, -2, 2n2, ≥, 2n2m, 2) in terms of p, n1, n2, ≥, n2m. In addition, a recurrence formula for calculating the Alexander polynomial of the 2-bridge knot with Conway's normal form C(2n1, 2n2, ≥, 2nm) via the integers n1,n2, ≥, nm is included.
MULTI-VARIABLE ALEXANDER POLYNOMIAL OF A PLAT
Authors: YUN KI-HEON
Published: May 2007

In the article we study the multi-variable Alexander polynomial of a link in a plat form or in a closed braid form. By using the method, we find an algorithm how to compute the multi-variable Alexander polynomial of the 2a-fold dihedral cover and the a-fold irregular cover of a two bridge knot K(a,b).
MAGNETIC FIELDS IN QUANTUM DEGENERATE SYSTEMS AND IN VACUUM
Authors: ROJAS H. PÉREZ , QUERTS E. RODRÍGUEZ
Published: May 2007

We consider self-magnetization of charged and neutral vector bosons bearing a magnetic moment in a gas and in vacuum. For charged vector bosons (W bosons) a divergence of the magnetization in both the medium and the electroweak vacuum occurs for the critical field [Formula: see text]. For B > Bwc the system is unstable. This behavior suggests the occurrence of a phase transition at B = Bc, where the field is self-consistently maintained. This mechanism actually prevents B from reaching the critical value Bc. For virtual neutral vector bosons bearing an anomalous magnetic moment, the ground state behavior for [Formula: see text] have a similar behavior. The magnetization in the medium is associated to a Bose–Einstein condensate and we conjecture a similar condensate occurs also in the case of vacuum. The model is applied to virtual electron-positron pairs bosonization in a magnetic field [Formula: see text], where me is the electron mass. This would lead also to vacuum self-magnetization in QED, where in both cases the symmetry breaking is due to a condensate of quasi-massless particles.
STABLE TeV BLACK HOLE REMNANTS AT THE LHC: DISCOVERY THROUGH DI-JET SUPPRESSION, MONO-JET EMISSION AND A SUPERSONIC BOOM IN THE QUARK–GLUON PLASMA
Authors: STÖCKER H.
Published: May 2007

The production of large extra dimension (LXD) black holes (BHs), with a new, fundamental mass scale of Mf = 1 TeV , has been predicted to occur at the Large Hadron Collider, LHC, with the formidable rate of 108 per year in p-p collisions at full energy, 14 TeV, and at full luminosity. We show that such LXD-BH formation will be experimentally observable at the LHC by the complete disappearance of all very high pt (> 500 GeV) back-to-back correlated Di-Jets of total mass M > Mf = 1 TeV , in the large detectors ALICE, ATLAS and CMS. We suggest complementing this clear cut-off signal at M > 2*500 GeV in the di-jet-correlation function by detecting the subsequent, Hawking-decay products of the LXD-BHs, namely either multiple high energy (> 100 GeV) SM Mono-Jets (i.e. away-side jet missing), sprayed off the evaporating BHs isentropically into all directions or the thermalization of the multiple overlapping Hawking-radiation in a Heckler–Kapusta-plasma: The extreme energy density of the Hawking Radiation may yield a Heckler–Kapusta–Hawking quark–gluon plasma of SM — and SUSY — particles at temperatures above the electroweak phase transition, which hydrodynamically (isentropically) evolves and cools until the quark–hadron phasetransition and chemical freezeout at T ~ 100 MeV is reached. Microcanonical quantum statistical calculations of the Hawking evaporation process for these LXD-BHs show that cold black hole remnants (BHRs) of mass ~ Mf remain leftover as the ashes of these spectacular di-jet-suppressed events. The BHRs are charged and can be detected as a track in the Central TPC of ALICE. Strong di-jet suppression is also expected with heavy ion beams at the LHC, due to quark–gluon-plasma induced jet attenuation at medium to low jet energies, pt < 200 GeV . The (mono-) jets in these events can be used to trigger tsunami-emission of secondary compressed QCD-matter at well defined Mach-angles, both at the trigger side and at the awayside (missing) jet. The Machshock angles allow for a direct measurement of both the equation of state EoS and the speed of sound cs via supersonic bang in the "big bang" matter. We discuss the importance of the underlying strong collective flow — the gluon storm — of the QCD matter for the formation and evolution of these Machshock cones. We predict a significant deformation of Mach shocks from the gluon storm in central Au + Au collisions at RHIC and LHC energies, as compared to the case of weakly coupled jets propagating through a static medium. A possible complete stopping of pt > 50 GeV jets at the LHC in 2–3 fm yields nonlinear high density Mach shocks in the quark–gluon plasma, which can be studied in the complex emission and disintegration pattern of the possibly supercooled matter. We report on first full three-dimensional fluid dynamical studies of the strong effects of a first order phase transition on the evolution and the tsunami-like Mach shock emission of the QCD matter.
ASPECTS OF MATTER–ANTIMATTER ASYMMETRY AND STATES FOR ASTROPHYSICS AND COSMOLOGY (AND VERY HIGH ENERGY DENSITIES PHYSICS)
Authors: BRAGHIN FÁBIO L.
Published: May 2007

Matter–antimatter asymmetry observed in our Universe is discussed with attention to different effects which are (or may be) present in the phase diagram of matter. Some implications which can possibly be present in astrophysical objects are also discussed. They may not rely on non-equilibrium conditions. For this, spontaneous (or not) symmetry breakings expected and/or envisaged to occur in the phase diagram of matter are briefly discussed and different scenarios for particular periods of the early Universe are proposed, which can also yield aspects of relevance for formation of large structures. Issues which can also be of relevance for the Hubble's Law are raised.
ISOVECTOR COMPONENTS OF THE SCALAR σ-MESON FAMILY AS NEW INGREDIENTS FOR NUCLEAR MATTER MODELS
Authors: LÜTZ EDUARDO , RAZEIRA MOISÉS , VASCONCELLOS CÉSAR A. Z. , BODMANN BARDO E. J. , PILOTTO FERNANDO
Published: May 2007

On the basis of a chiral symmetry transformation, we predict an isovector component for the family of light scalar mesons, i.e. partners of the σ-meson. Such a contribution may be necessary to tune the equation of state of nuclear matter in order to comply with severe constraints from a recent analysis of observational macroscopic properties of neutron stars.
SOLUTIONS OF COSMOLOGICAL MODELS WITH VARYING SPEED OF LIGHT
Authors: CÂMARA C. S. , NASCIMENTO R. B. , CARVALHO J. C. , DE GARCIA MAIA M. R.
Published: May 2007

In recent years, there has been some renewed interest in cosmological models in which the constants of nature vary with time. In one of these, one supposes a dependence on the redshift of the fine structure constant as suggested by some astronomical observations of quasars. This has led, among others, to the proposal that the speed of light varies with the cosmological time. A Varying Speed of Light (VSL) would be able to solve some long standing problems of the standard cosmological model, without the need for inflation. In this work we study two models in which (1) c varies according to a power law of the scale factor c(t) ∝ a-r and (2) c is proportional to the Hubble parameter c(t) ∝ Hu. We present solutions for these two types of VSL cosmologies. We find that for a flat (k = 0) Friedmann–Robertson–Walker (FRW) universe, the variation of c is coupled to a cosmological Λ-term and both singular and non-singular solutions are possible.
STRUCTURE FORMATION IN DARK MATTER/DARK ENERGY DOMINATED UNIVERSES
Authors: PIRES NILZA , DE SOUZA HIDALYN T. C. M.
Published: May 2007

In this work we present preliminary results of an analysis on the evolution of primordial baryonic and dark matter density perturbations. A top-hat hydrodynamic code has been utilized to analyze the evolution of these primordial perturbations, from the beginning of the recombination era until the redshift when the collapse occurs. All the relevant processes are included in the calculations, which includes the effect of a dark energy in the expanding universe. In particular, we find that the perturbations with dark matter collapse at very high redshift, which could explain the existence of old galaxies at high redshift. As a general result we find that the distribution of the non-baryonic dark matter is more concentrated than the baryonic one.
AGE CONSTRAINTS ON THE COSMIC EQUATION OF STATE
Authors: PIRES N. , ALCANIZ J. S.
Published: May 2007

A large amount of recent observational evidence strongly suggests that we live in a flat, accelerating universe composed of ≃ 1/3 of matter (barionic + dark) and ≃ 2/3 of an exotic component with large negative pressure, usually called dark energy or "quintessence." In this contribution, we investigate observational constraints on the equation of state of the dark energy from age estimates of galaxy clusters, supernovae observations and CMB measurements. Our results are based on a flat Friedmann–Robertson–Walker (FRW) type models driven by non-relativistic matter plus a smooth dark energy component parametrized by a constant equation of state px = ωωx (ω < 0).
DYNAMICS OF A SELF-GRAVITATING MAGNETIZED SOURCE
Authors: REY A. ULACIA , MARTÍNEZ A. PÉREZ , SUSSMAN ROBERTO A.
Published: May 2007

We consider a magnetized degenerate gas of fermions as the matter source of a homogeneous but anisotropic Bianchi I space–time with a Kasner-like metric. We examine the dynamics of this system by means of a qualitative and numerical study of Einstein–Maxwell field equations which reduce to a non-linear autonomous system. For all initial conditions and combinations of free parameters, the gas evolves from an initial anisotropic singularity into an asymptotic state that is completely determined by a stable attractor. Depending on the initial conditions the anisotropic singularity is of the "cigar" or "plate" types.
A FRACTAL-DISCRETE SCHEME FOR COSMIC PARTICLE ACCELERATION
Authors: SANTOS A. L. DOS , DE OLIVEIRA L. P. L. , BODMANN B. E. J. , VILHENA M. T.
Published: May 2007

The present article is an attempt to provide a parametrization for particle acceleration probabilities in the very high energy range combining a discrete fractal scheme for interaction probabilities and the observational fact of a power law energy spectrum for cosmic ray particles.
A SUFFICIENT AND NECESSARY CONDITION FOR CHANCE DISTRIBUTIONS OF RANDOM FUZZY VARIABLES
Authors: ZHU YUANGUO , LIU BAODING
Published: May 2007

A random fuzzy variable is a function from a credibility space to the set of random variables. Chance distribution is a type of mathematical description of random fuzzy variables. This paper presents a sufficient and necessary condition for chance distributions of random fuzzy variables.
NEW STATISTICAL APPROACHES FOR FUZZY DATA
Authors: SUN CHING-MIN , WU BERLIN
Published: May 2007

Real observations of qualities (continuous or discrete types) are not precise numbers but more or less non-precise. The best description of such data is by so-called fuzzy numbers. The fuzziness is different from measurement errors and stochastic uncertainty. In this paper we propose definitions of fuzzy mode, fuzzy median and fuzzy mean as well as investigation of their related properties and employ these techniques in the practical applications of real life. Empirical result shows that fuzzy statistics with soft computing is more realistic and reasonable for the statistical research. Finally certain comments are suggested for the further studies. We hope that this reformation will make the corresponding fuzzy techniques more appropriate and efficient to researchers whose only experience with statistics is using the traditional methods.
The TTX metabolite 4,9-anhydro-TTX is a highly specific blocker of the Nav1.6voltage-dependent sodium channel
Authors: Rosker Christian , Lohberger Birgit , Hofer Doris , Steinecker Bibiane , Quasthoff Stefan , Schreibmayer Wolfgang
Published: May 2007

The blocking efficacy of 4,9-anhydro-TTX (4,9-ah-TTX) and TTX on several isoforms of voltage-dependent sodium channels, expressed in Xenopus laevis oocytes, was tested (Nav1.2, Nav1.3, Nav1.4, Nav1.5, Nav1.6, Nav1.7, and Nav1.8). Generally, TTX was 40–231 times more effective, when compared with 4,9-ah-TTX, on a given isoform. An exception was Nav1.6, where 4,9-ah-TTX in nanomole per liter concentrations sufficed to result in substantial block, indicating that 4,9-ah-TTX acts specifically at this peculiar isoform. The IC50values for TTX/4,9-ah-TTX were as follows (in nmol/l): 7.8 ± 1.3/1,260 ± 121 (Nav1.2), 2.8 ± 2.3/341 ± 36 (Nav1.3), 4.5 ± 1.0/988 ± 62 (Nav1.4), 1,970 ± 565/78,500 ± 11,600 (Nav1.5), 3.8 ± 1.5/7.8 ± 2.3 (Nav1.6), 5.5 ± 1.4/1,270 ± 251 (Nav1.7), and 1,330 ± 459/>30,000 (Nav1.8). Analysis of approximal half-maximal doses of both compounds revealed minor effects on voltage-dependent activation only, whereas steady-state inactivation was shifted to more negative potentials by both TTX and 4,9-ah-TTX in the case of the Nav1.6subunit, but not in the case of other TTX-sensitive ones. TTX shifted steady-state inactivation also to more negative potentials in case of the TTX-insensitive Nav1.5subunit, where it also exerted profound effects on the time course of recovery from inactivation. Isoform-specific interaction of toxins with ion channels is frequently observed in the case of proteinaceous toxins. Although the sensitivity of Nav1.1to 4,9-ah-TTX is not known, here we report evidence on a highly isoform-specific TTX analog that may well turn out to be an invaluable tool in research for the identification of Nav1.6-mediated function, but also for therapeutic intervention.
Purinergic agonists stimulate lens Na-K-ATPase-mediated transport via a Src tyrosine kinase-dependent pathway
Authors: Tamiya Shigeo , Okafor Mansim C. , Delamere Nicholas A.
Published: May 2007

The Na-K-ATPase is vital for maintenance of lens transparency. Past studies using intact lens suggested the involvement of tyrosine kinases in short-term regulation of Na-K-ATPase. Furthermore, in vitro phosphorylation of a lens epithelial membrane preparation by Src family kinases (SFKs), a family of nonreceptor tyrosine kinases, resulted in modification of Na-K-ATPase activity. Here, the effect of purinergic agonists, ATP and UTP, on Na-K-ATPase function and SFK activation was examined in the rabbit lens. Na-K-ATPase function was examined using two different approaches, measurement of ouabain-sensitive potassium (86Rb) uptake by the intact lens, and Na-K-ATPase activity in lens epithelial homogenates. ATP and UTP caused a significant increase in ouabain-sensitive potassium (86Rb) uptake. Na-K-ATPase activity was increased in the epithelium of lenses pretreated with ATP. Lenses treated with ATP or UTP displayed activation of SFKs as evidenced by increased Western blot band density of active SFK (phosphorylated at the active loop Y416) and decreased band density of inactive SFKs (phosphorylated at the COOH terminal). A single PY416-Src immunoreactive band at ∼60 kDa was observed, suggesting not all Src family members are activated. Immunoprecipitation studies showed that band density of active Src, and to a lesser extent active Fyn, was significantly increased, while active Yes did not change. Preincubation of the lenses with SFK inhibitor PP2 abolished the ATP-induced increase in ouabain-sensitive potassium (86Rb) uptake. The results suggest selective activation of Src and/or Fyn is part of a signaling mechanism initiated by purinergic agonists that increases Na-K-ATPase-mediated transport in the organ-cultured lens.
Delayed angiogenesis and VEGF production in CCR2−/− mice during impaired skeletal muscle regeneration
Authors: Ochoa Oscar , Sun Dongxu , Reyes-Reyna Sara M. , Waite Lindsay L. , Michalek Joel E. , McManus Linda M. , Shireman Paula K.
Published: May 2007

The regulation of vascular endothelial growth factor (VEGF) levels and angiogenic events during skeletal muscle regeneration remains largely unknown. This study examined angiogenesis, VEGF levels, and muscle regeneration after cardiotoxin (CT)-induced injury in mice lacking the CC chemokine receptor 2 (CCR2). Muscle regeneration was significantly decreased in CCR2−/− mice as was the early accumulation of macrophages after injury. In both mouse strains, tissue VEGF was similar at baseline (no injections) and significantly decreased at day 3 post-CT. Tissue VEGF in wild-type (WT) mice was restored within 7 days postinjury but remained significantly reduced in CCR2−/− mice until day 21. Capillary density (capillaries/mm2) within regenerating muscle was maximal in WT mice at day 7 and double that of baseline muscle. In comparison, maximal capillary density in CCR2−/− mice occurred at 21 days postinjury. Maximal capillary density developed concurrent with the restoration of tissue VEGF in both strains. A highly significant, inverse relationship existed between the size of regenerated muscle fibers and capillaries per square millimeter. Although this relationship was comparable in WT and CCR2−/− animals, there was a significant decrease in the magnitude of this response in the absence of CCR2, reflecting the observation that regenerated muscle fiber size in CCR2−/− mice was only 50% of baseline at 42 days postinjury, whereas WT mice had attained baseline fiber size by day 21. Thus CCR2-dependent events in injured skeletal muscle, including impaired macrophage recruitment, contribute to restoration of tissue VEGF levels and the dynamic processes of capillary formation and muscle regeneration.