bluuebunny/crossref_metadata_2025 huggingface dataset:
Tmevpg1, a Candidate Gene for the Control of Theiler's Virus Persistence, Could Be Implicated in the Regulation of Gamma Interferon
Authors: Vigneau Soline , Rohrlich Pierre-Simon , Brahic Michel , Bureau Jean-François
Published: April 2003

TheTmevp3locus controls the load of Theiler's virus RNA during persistent infection of the mouse central nervous system (CNS). We identified a candidate gene at this locus,Tmevpg1, by using a positional cloning approach.Tmevpg1and its human ortholog,TMEVPG1, are expressed in the immune system and encode what appears to be a noncoding RNA. They are located in a cluster of cytokine genes that includes the genes for gamma interferon and one or two homolog of interleukin-10. We now report thatTmevpg1is expressed in CNS-infiltrating immune cells of resistant B10.S mice, but not in those of susceptible SJL/J mice, following inoculation with Theiler's virus. The pattern of expression ofTmevpg1is the same in B10.S mice and in SJL/J mice congenic for the resistant B10.S haplotype ofTmevp3. Nineteen polymorphisms were identified when theTmevpg1genes of B10.S and SJL/J mice were compared. Interestingly,Tmevpg1is down regulated after in vitro stimulation of murine CD4+or CD8+splenocytes, whereasIfngis up regulated. Similar patterns of expression ofTMEVPG1andIFNGwere observed in human NK cells and CD4+and CD8+T lymphocytes. Therefore,Tmevpg1is a strong candidate gene for theTmevp3locus and may be involved in the control ofIfnggene expression.
Transcriptional Regulatory Properties of Epstein-Barr Virus Nuclear Antigen 3C Are Conserved in Simian Lymphocryptoviruses
Authors: Zhao Bo , Dalbiès-Tran Rozenn , Jiang Hua , Ruf Ingrid K. , Sample Jeffery T. , Wang Fred , Sample Clare E.
Published: April 2003

Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA-3C) is a large transcriptional regulator essential for EBV-mediated immortalization of B lymphocytes. We previously identified interactions between EBNA-3C and two cellular transcription factors, Jκ and Spi proteins, through which EBNA-3C regulates transcription. To better understand the contribution of these interactions to EBNA-3C function and EBV latency, we examined whether they are conserved in the homologous proteins of nonhuman primate lymphocryptoviruses (LCVs), which bear a strong genetic and biological similarity to EBV. The homologue of EBNA-3C encoded by the LCV that infects baboons (BaLCV) was found to be only 35% identical in sequence to its EBV counterpart. Of particular significance, this homology localized predominantly to the N-terminal half of the molecule, which encompasses the domains in EBNA-3C that interact with Jκ and Spi proteins. Like EBNA-3C, both BaLCV and rhesus macaque LCV (RhLCV) 3C proteins bound to Jκ and repressed transcription mediated by EBNA-2 through its interaction with Jκ. Both nonhuman primate 3C proteins were also able to activate transcription mediated by the Spi proteins in the presence of EBNA-2. Like EBNA-3C, a domain encompassing the putative basic leucine zipper motif of the BaLCV-3C protein directly interacted with both Spi-1 and Spi-B. Surprisingly, a recently identified motif in EBNA-3C that mediates repression was not identifiable in the BaLCV-3C protein. Finally, although the C terminus of BaLCV-3C bears minimal homology to EBNA-3C, it nonetheless contains a C-terminal domain rich in glutamine and proline that was able to function as a potent transcriptional activation domain, as does the C terminus of EBNA-3C. The conservation of these functional motifs despite poor overall homology among the LCV 3C proteins strongly suggests that the interactions of EBNA-3C with Jκ and Spi do indeed play significant roles in the life cycle of EBV.
Direct Relationship between Suppression of Virus-Specific Immunity and Emergence of Cytomegalovirus Disease in Simian AIDS
Authors: Kaur Amitinder , Kassis Nadine , Hale Corrina L. , Simon Meredith , Elliott Michelle , Gomez-Yafal Alicia , Lifson Jeffrey D. , Desrosiers Ronald C. , Wang Fred , Barry Peter , Mach Michael , Johnson R. Paul
Published: April 2003

Although opportunistic infections like cytomegalovirus (CMV) are common sequelae of end-stage AIDS, the immune events leading to CMV reactivation in human immunodeficiency virus (HIV)-infected individuals are not well defined. The role of cellular and humoral CMV-specific immune responses in immune control of latent CMV infection was evaluated prospectively in a cohort of 11 simian immunodeficiency virus (SIV)-infected CMV-seropositive rhesus macaques, 6 of whom had histologic evidence of CMV disease at death. Macaques with CMV disease differed from macaques without CMV disease in having significantly higher levels of plasma SIV RNA and CMV DNA and significantly lower titers of anti-CMV binding antibodies (Abs) at the time of death. A significant decline in anti-CMV Abs and CMV-specific CD4+and CD8+T lymphocytes over time was observed in the macaques with CMV disease, but not in the macaques without CMV disease. Reduction in CMV-specific CD8+T lymphocytes and anti-CMV neutralizing Abs was significantly correlated with a decline in CMV-specific CD4+T lymphocytes. Although declines in CMV-specific T lymphocytes alone were sufficient for reactivation of low-level CMV viremia, high-level viremia (>1,000 copies of CMV DNA per ml of plasma) was observed when anti-CMV neutralizing and binding Abs had also declined. Thus, the occurrence of CMV reactivation-associated disease in AIDS is associated with suppression of both cellular and humoral CMV-specific immune responses. The underlying mechanism may be a dysfunction of memory B and CD8+T lymphocytes associated with SIV-induced impairment of CMV-specific CD4+T-cell help.
Positive Regulation of CXCR4 Expression and Signaling by Interleukin-7 in CD4+Mature Thymocytes Correlates with Their Capacity To Favor Human Immunodeficiency X4 Virus Replication
Authors: Schmitt Nathalie , Chêne Laurent , Boutolleau David , Nugeyre Marie-Thérèse , Guillemard Eric , Versmisse Pierre , Jacquemot Catherine , Barré-Sinoussi Françoise , Israël Nicole
Published: April 2003

The emergence of X4 human immunodeficiency virus type 1 (HIV-1) variants in infected individuals is associated with poor prognosis. One of the possible causes of this emergence might be the selection of X4 variants in some specific tissue compartment. We demonstrate that the thymic microenvironment favors the replication of X4 variants by positively modulating the expression and signaling of CXCR4 in mature CD4+CD8−CD3+thymocytes. Here, we show that the interaction of thymic epithelial cells (TEC) with these thymocytes in culture induces an upregulation of CXCR4 expression. The cytokine secreted by TEC, interleukin-7 (IL-7), increases cell surface expression of CXCR4 and efficiently overcomes the downregulation induced by SDF-1α, also produced by TEC. IL-7 also potentiates CXCR4 signaling, leading to actin polymerization, a process necessary for virus entry. In contrast, in intermediate CD4+CD8−CD3−thymocytes, the other subpopulation known to allow virus replication, TEC or IL-7 has little or no effect on CXCR4 expression and signaling. CCR5 is expressed at similarly low levels in the two thymocyte subpopulations, and neither its expression nor its signaling was modified by the cytokines tested. This positive regulation of CXCR4 by IL-7 in mature CD4+thymocytes correlates with their high capacity to favor X4 virus replication compared with intermediate thymocytes or peripheral blood mononuclear cells. Indeed, we observed an enrichment of X4 viruses after replication in thymocytes initially infected with a mixture of X4 (NL4-3) and R5 (NLAD8) HIV strains and after the emergence of X4 variants from an R5 primary isolate during culture in mature thymocytes.
Lentivirus Vectors Pseudotyped with Filoviral Envelope Glycoproteins Transduce Airway Epithelia from the Apical Surface Independently of Folate Receptor Alpha
Authors: Sinn Patrick L. , Hickey Melissa A. , Staber Patrick D. , Dylla Douglas E. , Jeffers Scott A. , Davidson Beverly L. , Sanders David A. , McCray Paul B.
Published: April 2003

The practical application of gene therapy as a treatment for cystic fibrosis is limited by poor gene transfer efficiency with vectors applied to the apical surface of airway epithelia. Recently, folate receptor alpha (FRα), a glycosylphosphatidylinositol-linked surface protein, was reported to be a cellular receptor for the filoviruses. We found that polarized human airway epithelia expressed abundant FRα on their apical surface. In an attempt to target these apical receptors, we pseudotyped feline immunodeficiency virus (FIV)-based vectors by using envelope glycoproteins (GPs) from the filoviruses Marburg virus and Ebola virus. Importantly, primary cultures of well-differentiated human airway epithelia were transduced when filovirus GP-pseudotyped FIV was applied to the apical surface. Furthermore, by deleting a heavily O-glycosylated extracellular domain of the Ebola GP, we improved the titer of concentrated vector severalfold. To investigate the folate receptor dependence of gene transfer with the filovirus pseudotypes, we compared gene transfer efficiency in immortalized airway epithelium cell lines and primary cultures. By utilizing phosphatidylinositol-specific phospholipase C (PI-PLC) treatment and FRα-blocking antibodies, we demonstrated FRα-dependent and -independent entry by filovirus glycoprotein-pseudotyped FIV-based vectors in airway epithelia. Of particular interest, entry independent of FRα was observed in primary cultures of human airway epithelia. Understanding viral vector binding and entry pathways is fundamental for developing cystic fibrosis gene therapy applications.
FEW-BODY ASPECTS OF HYPERNUCLEAR PHYSICS
Authors: HIYAMA E. , KAMIMURA M. , MOTOBA T. , YAMADA T. , YAMAMOTO Y.
Published: April 2003

On the basis of the three- and four-body structure calculations of [Formula: see text] and [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], it is emphasized that there are many interesting and important few-body problems in hypernuclear physics.
HYPERONS IN HIGH-DENSITY NUCLEAR MEDIUM: IS Λ-Σ0 MIXING LARGE OR SMALL?
Authors: SHINMURA SHOJI , AKAISHI YOSHINORI , MYINT KHIN SWE , HARADA TORU
Published: April 2003

The Λ-Σ0 mixing in neutron star matter is discussed in three theoretical models: the G-matrix theory, the relativistic mean field theory and the QCD sum-rule approach. The mixing of 2~8% at the critical baryon density of Λ appearance(2.3 times of the normal nuclear density) is predicted in the G-matrix theory. The second and third models give smaller mixing, 0.2~1.0% and < 0.25%, respectively. Since the G-matrix theory is the most dynamical model among the three, the mixing of 2~10% at 2~3 times of the normal density may be realistic.
NONMESONIC DECAY OF Λ AND ΛΛ HYPERNUCLEI
Authors: SASAKI KENJI , INOUE TAKASHI , OKA MAKOTO
Published: April 2003

Nonmesonic weak decays of single and double hypernuclei are studied on the basis of two-body baryon-baryon interactions, ΛN → NN and ΛΛ → YN transitions. The two-body weak transition is described by the combination of two processes, i.e., meson exchange and direct quark processes. The result indicates the importance of the direct quark(DQ) contribution. It largely enhances both the total decay rate and Γnn/Γpn ratio, and its property is different from the heavy meson exchanges (i.e. η, ρ, ω, and K*). The quark-meson hybrid picture, such as π+K+ DQ , reproduces the current experimental data except for the asymmetry parameter for light hypernuclei. The ΛΛ → YN transition in ΛΛ hypernucleus is complement of the ΛN → NN transition because it occurs only in the J = 0 channel which is hidden by J = 1 transition in the ΛN → NN case.
AB INITIO CALCULATION OF $^5_\Lambda
{\rm He}$ WITH EXPLICIT Σ ADMIXTURE
Authors: NEMURA H. , AKAISHI Y. , SUZUKI Y.
Published: April 2003

Variational calculations for s-shell hypernuclei are performed by explicitly including Σ degrees of freedom. Two sets of YN interactions (D2 and SC97e(S)) are used. The bound-state solution of [Formula: see text] is obtained by using each of YN potentials, and a large energy expectation value of the tensor ΛN - ΣN transition part is found by using the SC97e(S). The internal energy of 4 He subsystem changes a lot by the presence of a Λ particle with the strong tensor ΛN - ΣN transition potential.
Analysis of light nuclei with the AMD method
Authors: Watanabe T. , Taniguchi Y. , Sawado N. , Oryu S.
Published: April 2003

The AMD simulation for light nuclei with realistic potentials, e.g. the Paris potential, is investigated. The results are in qualitatively good agreement with nuclear ground state energies. The framework provides a powerful tool for studying the structure of nuclei.
PRESENT STATUS OF ELECTROMAGNETIC REACTIONS ON THE DEUTERON ABOVE PION THRESHOLD
Authors: ARENHÖVEL H. , DARWISH E. M. , FIX A. , SCHWAMB M.
Published: April 2003

The present status of the theoretical description of electromagnetic reactions on the deuteron above pion threshold is reviewed. Three major topics are considered: (i) retardation effects in π-meson exchange contributions to NN-interaction and meson exchange currents in deuteron photodisintegration above π-threshold in the Δ-resonance region, (ii) off-shell effects in the one-body current treated in a simple pion cloud model in, deuteron photodisintegration in and above the Δ-resonance region, and (iii) final state interaction effects in photoproduction of π and η mesons on the deuteron.
PROBING Δ STRUCTURE WITH PION ELECTROMAGNETIC PRODUCTION
Authors: YANG SHIN NAN , KAMALOV SABIT S.
Published: April 2003

The Dubna-Mainz-Taipei dynamical model for pion electromagnetic production, which can describe well the existing data from threshold up to 1 GeV photon lab energy, is presented and used to analyze the recent precision data in the Δ region. We find that, within our model, the bare Δ is almost spherical while the physical Δ is oblate. The deformation is almost saturated by the pion cloud effects. We further find that up to Q2 = 4.0(GeV/c)2 the extracted helicity amplitude A3/2 and A1/2 remain comparable with each other, implying that hadronic helicity is not conserved at this range of Q2. The ratio E1+/M1+ obtained show, starting from a small and negative value at the real photon point, a clear tendency to cross zero, and to become positive with increasing Q2. This is a possible indication of a very slow approach toward the pQCD region. Finally, we find that the bare helicity amplitude A1/2 and S1/2, but not A3/2, starts exhibiting the scaling behavior at about Q2 ≥ 2.5(GeV/c)2.
THREE-BODY EFFECTS IN $\vec{p}d$ ELASTIC SCATTERING AT 250 MEV
Authors: SHIMIZU Y. , HATANAKA K. , SAKEMI Y. , WAKASA T. , YOSHIDA H. P. , KAMIYA J. , SAITO T. , SAKAI H. , TAMIL A. , SEKIGUCHI K. , YAKO K. , MAEDA Y. , NORO T. , SAGARA K. , LADYGIN V. P.
Published: April 2003

The angular distributions of the cross section, the proton analyzing power and all of proton polarization transfer coefficients of [Formula: see text] elastic scattering were measured at 250 MeV. The present data are compared with theoretical predictions based on exact solutions of the three-nucleon Faddeev equations and modern realistic nucleon-nucleon potentials combined with three-nucleon forces. These results call for a better understanding of the spin structure of the three-nucleon force and very likely for a full relativistic treatment of the three-nucleon continuum.
HYBRIDS AND GLUEBALLS: A STATUS REPORT
Authors: SETH KAMAL K.
Published: April 2003

QCD predicts that besides the [Formula: see text] mesons and qqq baryons, there should exist hadrons with valence gluons, the [Formula: see text] hybrids and the gg, ggg glueballs. Serious experimental searches for these exotic structures are currently in progress. Their status is reviewed.
NUCLEON PROPERTIES IN THE EXPANDING UNIVERSE
Authors: HWANG W-Y. PAUCHY
Published: April 2003

Our universe expands and cools. The electroweak (EW) phase transition, which endows masses to the various particles, and QCD phase transition, which gives rise to confinement of quarks and gluons within hadrons in the true QCD vacuum, Would presumably have taken place in the early universe, respectively, at around 10-11 sec and at a time between 10-5 sec and 10-4 sec, or at the temperature of about 300 GeV and of about 150 MeV, respectively. It is clear that the nucleon mass [Formula: see text], the axial coupling [Formula: see text], and other nucleon parameters evolve as the universe evolves, thereby serving as an important gauge for understanding the state of the Universe.
$\overline{N}N$ ATOMS IN PARIS POTENTIAL
Authors: SUEBKA P.
Published: April 2003

The [Formula: see text] atomic state problem is solved in a suitable numerical approach based on Sturmian functions, which is able to account for both the strong short range nuclear potential (for both the local and nonlocal) and the long range Coulomb force and to provide directly the wave function of protonium with complex eigenvalues [Formula: see text]. The small hyperfine-splittings and decay widths of the 1s and 2p levels of the [Formula: see text] atomic states are studied in the latest version of the Paris [Formula: see text] potential. It is found that the potential needs to be modified at energies around the [Formula: see text] threshold.
LOW-LYING DIBARYON STATES IN A SYMMETRY ANALYSIS
Authors: LIU YUXIN , LI JINGSHENG , Bao Chengguang
Published: April 2003

The dibaryon states as six-quark clusters of exotic QCD states are investigated in this talk. With the inherent nodal surface structure analysis, the wave functions of the six-quark clusters (in another word, the dibaryons) are classified. The contribution of the hidden color channels are discussed. The quantum numbers of the low-lying dibaryon states are obtained. The States [ΩΩ](0,0+), [ΩΩ](0,2-), [Ξ* Ω](1/2,0+), [ΞΩ](1/2,1+), [Σ* Σ*](0,4-) and the hidden color channel states with the same quantum numbers are proposed to be the candidates of dibaryons, which may be observed in experiments.
ANALYSES OF THREE-BODY S-WAVE RESONANCES WITH ANALYTIC CONTINUATION IN THE COUPLING CONSTANT
Authors: AOYAMA SHIGEYOSHI
Published: April 2003

Using the method of analytic continuation in the coupling constant (ACCC) with a 8 He +n+n model, we investigated the three-body S-wave resonances in 10He. In addition to a solution of the two valence neutrons in the p-orbit ([p1/2 p1/2]0+), we newly obtained a solution of the two valence neutrons in the s-orbit ([s1/2s1/2]0+) as the ground state.
PHASE-SHIFT ANALYSES OF ELASTIC pp SCATTERING IN COSY REGION
Authors: NAGATA JUNICHI , YOSHINO HIRO , MATSUDA MASANORI
Published: April 2003

The phase-shift solutions in the single-energy analysis of elastic pp scattering in COSY region at TL= 1~2.4 GeV are presented, and differences of solutions obtained among ours, GWU and Saclay groups are discussed.
AN IMAGE-BASED INEXPENSIVE 3D SCANNER
Authors: YILMAZ ULAŞ , MÜLAYİM ADEM YAŞAR , ATALAY VOLKAN
Published: April 2003

An image-based model reconstruction system is described in this paper where real images of a rigid object acquired under a simple but controlled environment are used to recover its three dimensional geometry and its surface texture. Based on a multi-image calibration method, an algorithm to extract the rotation axis of a turn-table has been developed. Furthermore, this algorithm can be extended to estimate robustly the initial bounding volume of the object to be modeled. The coarse volume obtained is then carved using a stereo correction method which removes the disadvantages of silhouette-based reconstruction by photoconsistency. The concept of surface particles is adapted in order to extract a texture map for the model. Some existing metrics are used to measure the quality of the reconstructed models.
VIEW-DEPENDENT RENDERING FOR LARGE POLYGONAL MODELS OVER NETWORKS
Authors: EL-SANA JIHAD , SOKOLOVSKY NETA
Published: April 2003

In this paper we are presenting a novel approach that enables the rendering of large-shared datasets at interactive rates using inexpensive workstations. Our algorithm is based on view-dependent rendering and client-server technology — servers host large datasets and manage the selection of the various levels of detail, while clients receive blocks of update operations which are used to generate the appropriate level of detail in an incremental manner. We assume that servers are capable machines in terms of storage capacity and computational power and clients are inexpensive workstations which have limited 3D rendering capabilities. For optimization purposes we have developed two similar approaches — one for local area networks and the other for wide area networks. For the second approach we have performed several changes to adapt to the limitation of the wide area networks. To avoid network latency we have developed two powerful mechanisms that cache the adapt operation blocks on the clients' side and predict the future view-parameters of clients based on their recent behavior. Our approach dramatically reduces the amount of memory used by each client and the entire computing system since the dataset is stored only once in the local memory of the server. In addition, it decreases the load on the network as a result of the incremental update contributed by view-dependent rendering.
PERSONALIZED FACE ANIMATION IN SHOWFACE SYSTEM
Authors: ARYA ALI , HAMIDZADEH BABAK
Published: April 2003

The problem of Personalized Face Animation is addressed in this paper by proposing the ShowFace streaming structure. This structure is based on most widely accepted industry standards in multimedia presentation like MPEG-4 and SMIL, extending them by defining image transformations required for certain facial movements, and also by providing a higher level Face Modeling Language (FML) for modeling and control purposes. It defines a comprehensive framework for face animation consisting of components for parsing the input script, generating and splitting the audio and video "behaviors", creating the required images and sounds, and eventually displaying or writing the data to files. This component-based design and scripted behavior make the framework suitable for many purposes including web-based applications. Various examples illustrate the efficiency of our method.
PERCEPTUAL USER INTERFACE IN VIRTUAL SHOPPING ENVIRONMENT
Authors: GENG WEIDONG , STRAUSS WOLFGANG , FLEISCHMANN MONIKA , ELISTRATOV VLADIMIR , KOLESNIK MARINA
Published: April 2003

In this paper we present our effort towards the goal of perceptual user interface for main interaction tasks, such as navigation/travel, selection/picking and personal data access in a virtual shopping environment. A set of 3D navigation devices, vision-based pointing and personal access system are mainly discussed. The motivation and design principles behind these interfaces are also described. A prototype integration solution which brings these devices together in a virtual shopping environment, is given. These interfaces and interaction devices have been implemented and are tested for evaluation.
RECOGNIZING COMPLEX, ASYMMETRIC FUNCTIONAL SITES IN PROTEIN STRUCTURES USING A BAYESIAN SCORING FUNCTION
Authors: WEI LIPING , ALTMAN RUSS B.
Published: April 2003

The increase in known three-dimensional protein structures enables us to build statistical profiles of important functional sites in protein molecules. These profiles can then be used to recognize sites in large-scale automated annotations of new protein structures. We report an improved FEATURE system which recognizes functional sites in protein structures. FEATURE defines multi-level physico-chemical properties and recognizes sites based on the spatial distribution of these properties in the sites' microenvironments. It uses a Bayesian scoring function to compare a query region with the statistical profile built from known examples of sites and control nonsites. We have previously shown that FEATURE can accurately recognize calcium-binding sites and have reported interesting results scanning for calcium-binding sites in the entire Protein Data Bank. Here we report the ability of the improved FEATURE to characterize and recognize geometrically complex and asymmetric sites such as ATP-binding sites and disulfide bond-forming sites. FEATURE does not rely on conserved residues or conserved residue geometry of the sites. We also demonstrate that, in the absence of a statistical profile of the sites, FEATURE can use an artificially constructed profile based on a priori knowledge to recognize the sites in new structures, using redoxin active sites as an example.
Remarks on embeddable semigroups in groups and a generalizationof some Cuthbert′s results
Authors: Latrach Khalid , Dehici Abdelkader
Published: April 2003

Let (U(t)) t≥0 be a C0‐semigroup of bounded linear operators on a Banach space X. In this paper, we establish that if, for some t0 > 0, U(t0) is a Fredholm (resp., semi‐Fredholm) operator, then (U(t)) t≥0 is a Fredholm (resp., semi‐Fredholm) semigroup. Moreover, we give a necessary
and sufficient condition guaranteeing that (U(t)) t≥0 can be imbedded in a C0‐group on X. Also we study semigroups
which are near the identity in the sense that there exists
t0 > 0 such that U(t0) − I ∈ 𝒥(X), where 𝒥(X) is an arbitrary closed two‐sided ideal contained in the set
of Fredholm perturbations. We close this paper by discussing the
case where 𝒥(X) is replaced by some subsets of the set
of polynomially compact perturbations.
Stochastic processes on non‐Archimedean Banach spaces
Authors: Ludkovsky S. V.
Published: April 2003

Non‐Archimedean analogs of Markov quasimeasures and stochastic processes are investigated. They are used for the development of stochastic antiderivations. The non‐Archimedean analog of the Itô formula is
proved.
A rationality condition for the existence of odd perfect numbers
Authors: Davis Simon
Published: April 2003

A rationality condition for the existence of odd perfect numbers
is used to derive an upper bound for the density of odd integers
such that σ(N) could be equal to 2N, where N belongs to a fixed interval with a lower limit greater than 10300. The rationality of the square root expression consisting of a product
of repunits multiplied by twice the base of one of the repunits
depends on the characteristics of the prime divisors, and it is
shown that the arithmetic primitive factors of the repunits with
different prime bases can be equal only when the exponents are
different, with possible exceptions derived from solutions of a
prime equation. This equation is one example of a more general
prime equation, , and the demonstration of the nonexistence of solutions when h ≥ 2 requires the proof of a special case of Catalan′s conjecture.
General theorems on the nonexistence of prime divisors satisfying
the rationality condition and odd perfect numbers N subject to a condition on the repunits in factorization of σ(N) are proven.
Lorentz‐invariant quantum fields in the space‐time tangent bundle
Authors: Brandt Howard E.
Published: April 2003

A maximal‐acceleration invariant quantum field is defined on the
space‐time tangent bundle with vanishing eigenvalue when acted on
by the Laplace‐Beltrami operator of the bundle, and the case is
addressed in which the space‐time is Minkowskian, and
the field is Lorentz invariant. In this case, the field is shown
to be automatically regularized at the Planck scale, and particle
spectra are cut off at extremely high energies. The microcausality
is addressed by calculating the appropriate field commutators;
and it is shown that provided the adjoint field is consistently
generalized, the necessary commutators are vanishing and the
field is microcausal, but that there are Planck‐scale
modifications of the boundary of the causal domain that are
significant for extremely large relative four‐velocities between
the separated space‐time points. For vanishing relative
four‐velocity, the causal domain is canonical. The geometry of the
causal domain indicates that near the Planck scale, causal
connectivity may occur between spacelike separated points, and
also at larger scales for extremely large relative
four‐velocities.
On conformal dilatation in space
Authors: Bishop Christopher J. , Gutlyanskiĭ Vladimir Ya. , Martio Olli , Vuorinen Matti
Published: April 2003

We study the conformality problems associated with quasiregular
mappings in space. Our approach is based on the concept of the
infinitesimal space and some new Grötzsch‐Teichmüller type
modulus estimates that are expressed in terms of the mean value
of the dilatation coefficients.
Universal connections on Lie groupoids
Authors: Vassiliou Efstathios , Nikolopoulos Apostolos
Published: April 2003

Given a Lie groupoid Ω, we construct a groupoid J1Ω equipped with a universal connection from which all the
connections of Ω are obtained by certain pullbacks. We show
that this general construction leads to universal connections on
principal bundles (considered by García (1972)) and
universal linear connections on vector bundles (ultimately
related with those of Cordero et al. (1989)).
The category of long exact sequences and the homotopy exactsequence of modules
Authors: Su C. Joanna
Published: April 2003

The relative homotopy theory of modules, including the (module)
homotopy exact sequence, was developed by Peter Hilton (1965). Our
thrust is to produce an alternative proof of the existence of the
injective homotopy exact sequence with no reference to elements
of sets, so that one can define the necessary homotopy concepts in
arbitrary abelian categories with enough injectives and
projectives, and obtain, automatically, the projective relative
homotopy theory as the dual. Furthermore, we pursue the relative
(module) homotopy theory analogously to the absolute (module)
homotopy theory. For these purposes, we embed the relative
category into the category of long exact sequences, as a full
subcategory, in our search for suitable notions of monomorphisms
and injectives in the relative category.
Nonlinear dynamical boundary‐value problem of hydrogen thermaldesorption
Authors: Zaika Yu. V. , Chernov I. A.
Published: April 2003

The nonlinear boundary‐value problem for the diffusion equation,
which models gas interaction with solids, is considered. The
model includes diffusion and the sorption/desorption processes on
the surface, which leads to dynamical nonlinear boundary
conditions. The boundary‐value problem is reduced to an
integro‐differential equation of a special kind; existence and
uniqueness of the classical (differentiable) solution theorems
are proved. The results of numerical experiments are presented.
On centralizers of elements of groups acting on trees withinversions
Authors: Mahmood R. M. S.
Published: April 2003

A subgroup H of a group G is called malnormal in G if it satisfies the condition that if g ∈ G and h ∈ H, h ≠ 1
such that ghg−1 ∈ H, then g ∈ H. In this paper, we show
that if G is a group acting on a tree X with inversions such
that each edge stabilizer is malnormal in G, then the
centralizer C(g) of each nontrivial element g of G is in a
vertex stabilizer if g is in that vertex stabilizer. If g is
not in any vertex stabilizer, then C(g) is an infinite cyclic
if g does not transfer an edge of X to its inverse. Otherwise,
C(g) is a finite cyclic of order 2.
Group method analysis of two‐dimensional plate in heat flux
Authors: Abd-el-Malek Mina B. , Michael Fayez H. , El-Mansi Samy M. A.
Published: April 2003

The group transformation theoretic approach is applied to present
an analytic study of the temperature distribution in a triangular
plate, Ω, placed in the field of heat flux, along one
boundary, in a form of polynomial functions of any degree “n.” The Laplace′s equation has been reduced to second‐order
linear ordinary differential equation with an appropriate
boundary conditions. Exact solution has been obtained for general
shape of Ω and different boundary conditions.
Foliations by minimal surfaces and contact structures on certain closed 3‐manifolds
Authors: Escobales Richard H.
Published: April 2003

Let (M, g) be a closed, connected, oriented C∞
Riemannian 3‐manifold with tangentially oriented flow F. Suppose that F admits a basic transverse
volume form μ and mean curvature one‐form κ which is horizontally closed. Let {X, Y} be any pair of basic vector fields, so μ(X, Y) = 1. Suppose further that the globally defined vector 𝒱[X, Y] tangent to the flow satisfies
[Z.𝒱[X, Y]] = fZ𝒱[X, Y] for any basic vector
field Z and for some function fZ depending on Z. Then, 𝒱[X, Y] is either always zero and H, the distribution orthogonal to the flow in T(M), is integrable with minimal leaves, or 𝒱[X, Y] never vanishes and H is a contact structure. If additionally, M has a finite‐fundamental group, then 𝒱[X, Y] never vanishes
on M, by the above together with a theorem of Sullivan (1979).
In this case H is always a contact structure. We
conclude with some simple examples.
Some properties of maximal open sets
Authors: Nakaoka Fumie , Oda Nobuyuki
Published: April 2003

Some fundamental properties of maximal open sets are obtained,
such as decomposition theorem for a maximal open set. Basic properties of intersections of maximal open sets are established, such as the law of radical closure.
Biharmonic curves in Minkowski 3‐space
Authors: Inoguchi Jun-Ichi
Published: April 2003

We give a differential geometric interpretation for the classification
of biharmonic curves in semi‐Euclidean 3‐space due to Chen and Ishikawa (1991).
A general scheme for constructing inversion algorithms for conebeam CT
Authors: Katsevich Alexander
Published: April 2003

Given a rather general weight function n0, we derive a new cone beam transform inversion formula. The derivation is explicitly based on Grangeat′s formula (1990) and the classical 3D Radon
transform inversion. The new formula is theoretically exact and is
represented by a 2D integral. We show that if the source
trajectory C is complete in the sense of Tuy (1983) (and
satisfies two other very mild assumptions), then substituting the
simplest weight n0 ≡ 1 gives a convolution‐based FBP
algorithm. However, this easy choice is not always optimal from
the point of view of practical applications. The weight
n0 ≡ 1 works well for closed trajectories, but the
resulting algorithm does not solve the long object problem if C
is not closed. In the latter case one has to use the flexibility
in choosing n0 and find the weight that gives an inversion
formula with the desired properties. We show how this can be done
for spiral CT. It turns out that the two inversion algorithms for
spiral CT proposed earlier by the author are particular cases of
the new formula. For general trajectories the choice of weight
should be done on a case‐by‐case basis.
Lp‐inverse theorem for modified beta operators
Authors: Gupta Vijay , Maheshwari Prerna , Jain V. K.
Published: April 2003

We obtain a converse theorem for the linear combinations of
modified beta operators whose weight function is the Baskakov
operators. To prove our inverse theorem, we use the technique of
linear approximating method, namely, Steklov mean.
Attractors of iterated function systems and Markov operators
Authors: Myjak Józef , Szarek Tomasz
Published: April 2003

This paper contains a review of results concerning “generalized”
attractors for a large class of iterated function systems {wi : i ∈ I} acting on a complete separable metric space.
This generalization, which originates in the Banach contraction
principle, allows us to consider a new class of sets, which we
call semi‐attractors (or semifractals). These sets have many
interesting properties. Moreover, we give some fixed‐point
results for Markov operators acting on the space of Borel
measures, and we show some relations between semi‐attractors and
supports of invariant measures for such Markov operators.
Finally, we also show some relations between multifunctions and
transition functions appearing in the theory of Markov operators.
An iterative approach to a constrained least squares problem
Authors: Reich Simeon , Xu Hong-Kun
Published: April 2003

A constrained least squares problem in a Hilbert space H is considered. The standard Tikhonov regularization method is used.
In the case where the set of the constraints is the nonempty intersection of a finite collection of closed convex subsets of H, an iterative algorithm is designed. The resulting sequence is shown to converge strongly to the unique solution of the regularized problem. The net of the solutions to the regularized problems strongly converges to the minimum norm solution of the least squares problem if its solution set is nonempty.
Baculoviruses as Vectors for Gene Therapy against Human Prostate Cancer
Authors: Stanbridge Lindsay J. , Dussupt Vincent , Maitland Norman J.
Published: April 2003

Current curative strategies for prostate cancer are restricted to the primary tumour, and the effect of treatments to control metastatic disease is not sustained. Therefore, the application of gene therapy to prostate cancer is an attractive alternative. Baculoviruses are highly restricted insect viruses, which can enter, but not replicate in mammalian cells. Baculoviruses can incorporate large amounts of extra genetic material, and will express transgenes in mammalian cells when under the control of a mammalian or strong viral promoter. Successful gene delivery has been achieved both in vitro and in vivo and into both dividing and nondividing cells, which is important since prostate cancers divide relatively slowly. In addition, the envelope protein gp64 is sufficiently mutable to allow targeted transduction of particular cell types. In this review, the advantages of using baculoviruses for prostate cancer gene therapy are explored, and the mechanisms of viral entry and transgene expression are described.
In Vivo Noninvasive Imaging for Gene Therapy
Authors: Vassaux Georges , Groot-Wassink Thomas
Published: April 2003

Gene therapy is reaching a stage where some clinical benefits have been demonstrated on patients involved in phase I/II clinical trials. However, in many cases, the clinical benefit is hardly measurable and progress in the improvement of gene therapy
formulations is hampered by the lack of objective clinical endpoints to measure transgene delivery and to quantitate transgene expression. However, these endpoints rely almost exclusively on the analysis of biopsies by molecular and histopathological methods. These methods provide only a limited picture of the situation. Therefore, there is a need for a technology that would allow precise, spacio‐temporal measurement of gene expression on a whole body scale upon administration of the gene delivery vector. In the field of gene therapy, a considerable effort is being invested in the development of noninvasive imaging of gene expression and this review presents the various strategies currently being developed.
Targeting Radiotherapy to Cancer by Gene Transfer
Authors: Mairs R. J. , Boyd M.
Published: April 2003

Targeted radionuclide therapy is an alternative method of radiation treatment which uses a tumor‐seeking agent carrying a radioactive atom to deposits of tumor, wherever in the body they may be located. Recent experimental data signifies promise for the amalgamation of gene transfer with radionuclide targeting. This review encompasses aspects of the integration of gene
manipulation and targeted radiotherapy, highlighting the possibilities of gene transfer to assist the targeting of cancer with low molecular weight radiopharmaceuticals.
Gene Therapy for Cardiovascular Disease
Authors: Dishart Kate L. , Work Lorraine M. , Denby Laura , Baker Andrew H.
Published: April 2003

The last decade has seen substantial advances in the development of gene therapy strategies and vector technology for the treatment of a diverse number of diseases, with a view to translating the successes observed in animal models into the clinic. Perhaps the overwhelming drive for the increase in vascular gene transfer studies is the current lack of successful long‐term pharmacological treatments for complex cardiovascular diseases. The increase in cardiovascular disease to epidemic proportions has also led many to conclude that drug therapy may have reached a plateau in its efficacy and that gene therapy may represent a realistic solution to a long‐term problem. Here, we discuss gene delivery approaches and target diseases.
Targeting of Synthetic Gene Delivery Systems
Authors: Schätzlein Andreas G.
Published: April 2003

Safe, efficient, and specific delivery of therapeutic genes remains an important bottleneck for the development of gene therapy. Synthetic, nonviral systems have a unique pharmaceutical profile with potential advantages for certain applications. Targeting of the synthetic vector improves the specificity of gene medicines through a modulation of the carriers′ biodistribution, thus creating a dose differential between healthy tissue and the target site. The biodistribution of current carrier systems is being influenced to a large extent by intrinsic physicochemical characteristics, such as charge and size. Consequently, such nonspecific interactions can interfere with specific targeting, for example, by ligands. Therefore, a
carrier complex should ideally be inert, that is, free from intrinsic properties that would bias its distribution away from the target site. Strategies such as coating of DNA carrier complexes with hydrophilic polymers have been used to mask some of these intrinsic targeting effects and avoid nonspecific interactions. Preexisting endogenous ligand‐receptor interactions
have frequently been used for targeting to certain cell types or tumours. Recently exogenous ligands have been derived from microorganisms or, like antibodies or phage‐derived peptides,
developed de novo. In animal models, such synthetic vectors have targeted remote sites such as a tumour. Furthermore, the therapeutic proof of the concept has been demonstrated for
fitting combinations of synthetic vectors and therapeutic gene.
Arterial Stiffness Increases With Deteriorating Glucose Tolerance Status
Authors: Henry Ronald M.A. , Kostense Piet J. , Spijkerman Annemieke M.W. , Dekker Jacqueline M. , Nijpels Giel , Heine Robert J. , Kamp Otto , Westerhof Nico , Bouter Lex M. , Stehouwer Coen D.A.
Published: April 2003

Background—

Type 2 diabetes (DM-2) and impaired glucose metabolism (IGM) are associated with an increased cardiovascular disease risk. In nondiabetic individuals, increased arterial stiffness is an important cause of cardiovascular disease. Associations between DM-2 and IGM and arterial stiffness have not been systematically investigated.

Methods and Results—

In a population-based cohort (n=747; 278 with normal glucose metabolism, 168 with IGM, and 301 with DM-2; mean age, 68.5 years), arterial stiffness was ultrasonically estimated by distensibility and compliance of the carotid, femoral, and brachial arteries and by the carotid elastic modulus. After adjustment for age, sex, and mean arterial pressure, DM-2 was associated with increased carotid, femoral, and brachial stiffness, whereas IGM was associated only with increased femoral and brachial stiffness. Carotid but not femoral or brachial stiffness increased from IGM to DM-2. Standardized βs (95% CI) for IGM and DM-2, compared with normal glucose metabolism, were −0.06 (−0.23 to 0.10) and −0.37 (−0.51 to −0.23) for carotid distensibility; −0.02 (−0.18 to 0.18) and −0.25 (−0.40 to −0.09) for carotid compliance; −0.05 (−0.23 to 0.13) and 0.25 (0.10 to 0.40) for carotid elastic modulus; −0.70 (−0.89 to −0.51) and −0.67 (−0.83 to −0.52) for femoral distensibility; and −0.62 (−0.80 to −0.44) and −0.79 (−0.94 to −0.63) for femoral compliance. The brachial artery followed a pattern similar to that of the femoral artery. Increases in stiffness indices were explained by decreases in distension, increases in pulse pressure, an increase in carotid intima-media thickness, and, for the femoral artery, a decrease in diameter. Hyperglycemia or hyperinsulinemia explained only 30% of the arterial changes associated with glucose tolerance. Adjustment for conventional cardiovascular risk factors did not affect these findings.

Conclusions—

IGM and DM-2 are associated with increased arterial stiffness. An important part of the increased stiffness occurs before the onset of DM-2 and is explained neither by conventional cardiovascular risk factors nor by hyperglycemia or hyperinsulinemia.
Different Differentiation Kinetics of Vascular Progenitor Cells in Primate and Mouse Embryonic Stem Cells
Authors: Sone Masakatsu , Itoh Hiroshi , Yamashita Jun , Yurugi-Kobayashi Takami , Suzuki Yutaka , Kondo Yasushi , Nonoguchi Akane , Sawada Naoki , Yamahara Kenichi , Miyashita Kazutoshi , Park Kwijun , Shibuya Masabumi , Nito Shinji , Nishikawa Shin-Ichi , Nakao Kazuwa
Published: April 2003

Background—

We demonstrated that vascular endothelial growth factor receptor 2 (VEGF-R2)-positive cells derived from mouse embryonic stem (ES) cells can differentiate into both endothelial cells and mural cells to suffice as vascular progenitor cells (VPCs). Here we examined whether VPCs occur in primate ES cells and investigated the differences in VPC differentiation kinetics between primate and mouse ES cells.

Methods and Results—

In contrast to mouse ES cells, undifferentiated monkey ES cells expressed VEGF-R2. By culturing these undifferentiated ES cells for 4 days on OP9 feeder layer, VEGF-R2 expression disappeared, and then reappeared after 8 days of differentiation. We then isolated these VEGF-R2–positive and vascular endothelial cadherin (VEcadherin)-negative cells by flow cytometry sorting. Additional 5-day reculture of these VEGF-R2
+
VEcadherin
−
cells on OP9 feeder layer resulted in the appearance of platelet endothelial cell adhesion molecule-1 (PECAM1)-positive, VEcadherin-positive, endothelial nitric oxide synthase (eNOS)-positive endothelial cells. On a collagen IV-coated dish in the presence of serum, these cells differentiated into smooth muscle actin (SMA)-positive and calponin-positive mural cells (pericytes or vascular smooth muscle cells). Addition of 50ng/mL VEGF to the culture on a collagen IV-coated dish resulted in the appearance of PECAM1
+
cells surrounded by SMA
+
cells. In addition, these differentiated VEGF-R2
+
cells can form tube-like structures in a 3-dimensional culture.

Conclusion—

Our findings indicate that differentiation kinetics of VPCs derived from primate and mouse ES cells were different. Differentiated VEGF-R2
+
VEcadherin
−
cells can act as VPCs in primates. To seek the clinical potential of VPCs for vascular regeneration, investigations of primate ES cells are indispensable.
Engaged Universities: Lessons from the Land-Grant Universities and Extension
Authors: Mcdowell George R.
Published: April 2003

Engagement is the vogue of relevant scholars into the twenty-first century. Yet there are concerns that scholarly objectivity requires detachment from society. The American experience with scholarly engagement comes from Land-Grant universities and extension. The Land-Grant principle emerged from the mandate to the Land-Grant colleges to improve the nation’s agriculture. Agricultural science has been hugely productive because of the Land-Grant principle. The principle is general to all scholarship. The Land-Grant principle gives both intellectual and political power to engagement. Scholarship is made better substantially through the test of workability, a dimension of scholarly objectivity. The scholar is also made more skillful. The engagement making possible the test of workability makes the scholarship more relevant. Institutionalized access to the workable, relevant knowledge for those who need it generates substantial political power. At a time when universities, particularly public research universities, are seeking public support for more than their teaching, the strategies suggested by the Land-Grant principle are instructive.