bluuebunny/crossref_metadata_2025_split huggingface dataset:
REPRESENTATION OF ATOMIC OPERATORS AND EXTENSION PROBLEMS
Authors: Stepanov Eugene 
Published: November 2004

AbstractThe notion of an atomic operator between spaces of measurable functions was introduced in 2002 in a paper by Drakhlin, Ponosov and Stepanov in order to provide a reasonable generalization of local operators useful for applications. It has been shown that, roughly speaking, atomic operators amount to compositions of local operators with shifts. A natural problem is then when a continuous-in-measure atomic operator can be represented as a composition of a Nemytskiiˇ (composition) operator generated by a Carathéodory function, and a shift operator. In this paper we will show that the answer to this question is inherently related to the possibility of extending an atomic operator with continuity from a space of functions measurable with respect to some $\sigma$-algebra to a larger space of functions measurable with respect to a larger $\sigma$-algebra, as well as to the possibility of extending any $\sigma$-homomorphism from a smaller-measure algebra to a $\sigma$-homomorphism on a larger-measure algebra. We characterize precisely the condition on the respective $\sigma$-algebras which provides such possibilities and induces the positive answer to the above representation problem.AMS 2000 Mathematics subject classification: Primary 47B38; 47A67; 34K05
OPERATORS THAT ARE NUCLEAR WHENEVER THEY ARE NUCLEAR FOR A LARGER RANGE SPACE
Authors: Oja Eve 
Published: November 2004

AbstractLet $X$ be a Banach space and let $Y$ be a closed subspace of a Banach space $Z$. The following theorem is proved. Assume that $X^*$ or $Z^*$ has the approximation property. If there exists a bounded linear extension operator from $Y^*$ to $Z^*$, then any bounded linear operator $T:X\rightarrow Y$ is nuclear whenever $T$ is nuclear from $X$ to $Z$. The particular case of the theorem with $Z=Y^{**}$ is due to Grothendieck and Oja and Reinov. Numerous applications are presented. For instance, it is shown that a bounded linear operator $T$ from an arbitrary Banach space $X$ to an $\mathcal{L}_\infty$-space $Y$ is nuclear whenever $T$ is nuclear from $X$ to some Banach space $Z$ containing $Y$ as a subspace.AMS 2000 Mathematics subject classification: Primary 46B20; 46B28; 47B10
PROBABILISTIC INTERPRETATION AND PARTICLE METHOD FOR VORTEX EQUATIONS WITH NEUMANN’S BOUNDARY CONDITION
Authors: Jourdain Benjamin , Méléard Sylvie 
Published: November 2004

AbstractWe are interested in proving the convergence of Monte Carlo approximations for vortex equations in bounded domains of $\mathbb{R}^2$ with Neumann’s condition on the boundary. This work is the first step towards justifying theoretically some numerical algorithms for Navier–Stokes equations in bounded domains with no-slip conditions.We prove that the vortex equation has a unique solution in an appropriate energy space and can be interpreted from a probabilistic point of view through a nonlinear reflected process with space-time random births on the boundary of the domain.Next, we approximate the solution $w$ of this vortex equation by the weighted empirical measure of interacting diffusive particles with normal reflecting boundary conditions and space-time random births on the boundary. The weights are related to the initial data and to the Neumann condition. We prove a trajectorial propagation-of-chaos result for these systems of interacting particles. We can deduce a simple stochastic particle algorithm to simulate $w$.AMS 2000 Mathematics subject classification: Primary 60K35; 76D05
NEW MARTINGALE INEQUALITIES IN REARRANGEMENT-INVARIANT FUNCTION SPACES
Authors: Kikuchi Masato 
Published: November 2004

AbstractWe establish various martingale inequalities in a rearrangement-invariant (RI) Banach function space. If $X$ is an RI space that is not too small, we associate with it RI spaces $\mathcal{H}_p(X)$ $(1\leq p\lt\infty)$ and $K(X)$, and discuss martingale inequalities in these spaces. One of our results is as follows. Let $1\leq p\lt\infty$, let $f=(f_n)$ be an $L_p$-bounded martingale, and let $|f|^p=g+h$ be the Doob decomposition of the submartingale $|f|^p=(|f_n|^p)$ into a martingale $g=(g_n)$ and a predictable non-decreasing process $h=(h_n)$ with $h_0=0$. Then, in the case where $1\ltp\lt\infty$, we obtain the inequalities$$ \|h_{\infty}^{1/p}\|_X\leq2\|f_{\infty}\|_{\mathcal{H}_p(X)}\quad\text{and}\quad \Big\|\sup_n|g_n|^{1/p}\Big\|_X\leq4\|f_{\infty}\|_{\mathcal{H}_p(X)}, $$and, in the case where $p=1$, we obtain the inequalities$$ \|h_{\infty}\|_X\leq\sup_{n\in\mathbb{Z}_{+}}\|f_n\|_{K(X)}\quad\text{and}\quad \sup_{n\in\mathbb{Z}_{+}}\|g_n\|_X\leq2\sup_{n\in\mathbb{Z}_{+}}\|f_n\|_{K(X)}. $$For some specific choices of $X$, we can give explicit expressions for $\mathcal{H}_p(X)$ and $K(X)$. For example, $\mathcal{H}_1(L_1)=L\log L$, $\mathcal{H}_p(L_{p,\infty})=L_{p,1}$, and so on. Furthermore, if the Boyd indices of $X$ satisfy $0\lt\alpha_{X}\leq\beta_{X}\lt1/p$ (respectively, $0\lt\alpha_{X}$), then $\mathcal{H}_p(X)=X$ (respectively, $K(X)=X$). In any case, $\mathcal{H}_p(X)$ is embedded in $K(X)$, and $K(X)$ is embedded in $X$.AMS 2000 Mathematics subject classification: Primary 60G42; 60G46. Secondary 46E30
THE ANALYSIS OF WARNER BOUNDEDNESS
Authors: Kaķol Jerzy , Saxon Stephen A. , Todd Aaron R. 
Published: November 2004

AbstractIn answer to Jarchow’s 1981 text, we recently characterized when $C_{\textrm{c}}(X)$ is a $df$-space, finding along the way attractive analytic characterizations of when the Tychonov space $X$ is pseudocompact. Analogues now reveal how exquisitely Warner boundedness lies between these two notions. To illustrate, $X$ is pseudocompact, $X$ is Warner bounded or $C_{\textrm{c}}(X)$ is a $df$-space if and only if for each sequence $(\mu_{n})_{n}\subset C_{\textrm{c}}(X)'$ there exists a sequence $(\varepsilon_{n})_{n}\subset(0,1]$ such that $(\varepsilon_{n}\mu_{n})_{n}$ is weakly bounded, is strongly bounded or is equicontinuous, respectively. Our characterizations and proofs add to and simplify Warner’s.AMS 2000 Mathematics subject classification: Primary 46A08; 46A30; 54C35
CONVOLUTION SUMS INVOLVING THE DIVISOR FUNCTION
Authors: Cheng Nathalie , Williams Kenneth S. 
Published: November 2004

AbstractThe series\begin{alignat*}{2} L_{r,4}(q)\amp=\sum_{n=0}^\infty\sigma(4n+r)q^{4n+r},\amp\quad r\amp=0,1,2,3, \\ M_{r,4}(q)\amp=\sum_{n=0}^\infty\sigma_3(4n+r)q^{4n+r},\amp\quad r\amp=0,1,2,3, \\ N_{r,4}(q)\amp=\sum_{n=0}^\infty\sigma_5(4n+r)q^{4n+r},\amp\quad r\amp=0,1,2,3, \end{alignat*}are evaluated and used to prove convolution formulae such as$$ \sum_{m\le n}\sigma(4m-3)\sigma(4n-(4m-3))=4\sigma_3(n)-4\sigma_3(\tfrac12n). $$AMS 2000 Mathematics subject classification: Primary 11A25
GW9662, a potent antagonist of PPARγ, inhibits growth of breast tumour cells and promotes the anticancer effects of the PPARγ agonist rosiglitazone, independently of PPARγ activation
Authors: Seargent Jill M , Yates Elisabeth A , Gill Jason H 
Published: November 2004

Peroxisome proliferator‐activated receptor gamma (PPARγ), a member of the nuclear receptor superfamily, is activated by several compounds, including the thiazolidinediones. In addition to being a therapeutic target for obesity, hypolipidaemia and diabetes, perturbation of PPARγ signalling is now believed to be a strategy for treatment of several cancers, including breast. Although differential expression of PPARγ is observed in tumours compared to normal tissues and PPARγ agonists have been shown to inhibit tumour cell growth and survival, the interdependence of these observations is unclear. This study demonstrated that the potent, irreversible and selective PPARγ antagonist GW9662 prevented activation of PPARγ and inhibited growth of human mammary tumour cell lines. Controversially, GW9662 prevented rosiglitazone‐mediated PPARγ activation, but enhanced rather than reversed rosiglitazone‐induced growth inhibition. As such, these data support the existence of PPARγ‐independent pathways and question the central belief that PPARγ ligands mediate their anticancer effects via activation of PPARγ.British Journal of Pharmacology (2004) 143, 933–937. doi:10.1038/sj.bjp.0705973
Inhibition of ATP‐sensitive potassium channels by haloperidol
Authors: Yang Shi‐Bing , Proks Peter , Ashcroft Frances M , Rupnik Marjan 
Published: November 2004

Chronic haloperidol treatment has been associated with an increased incidence of glucose intolerance and type‐II diabetes mellitus. We studied the effects of haloperidol on native ATP‐sensitive potassium (KATP) channels in mouse pancreatic β cells and on cloned Kir6.2/SUR1 channels expressed in HEK293 cells.
The inhibitory effect of haloperidol on the KATP channel was not mediated via the D2 receptor signaling pathway, as both D2 agonists and antagonists blocked the channel.
KATP currents were studied using the patch‐clamp technique in whole‐cell and outside‐out patch configurations. Addition of haloperidol to the extracellular solution inhibited the KATP conductance immediately, in a reversible and voltage‐independent manner. Haloperidol did not block the channel when applied intracellularly in whole‐cell recordings.
Haloperidol blocked cloned Kir6.2/SUR1 and Kir6.2ΔC36 KATP channels expressed in HEK cells. This suggests that the drug interacts with the Kir6.2 subunit of the channel.
The IC50 for inhibition of the KATP current by haloperidol was 1.6 μM in 2 mM extracellular K+ concentration ([K+]o) and increased to 23.9 μM in 150 mM [K+]o. The Hill coefficient was close to unity, suggesting that the binding of a single molecule of haloperidol is sufficient to close the channel.
Haloperidol block of KATP channels may contribute to the side effects of this drug when used therapeutically.

British Journal of Pharmacology (2004) 143, 960–967. doi:10.1038/sj.bjp.0706017
Characterization of a transport and detoxification pathway for the antitumour drug bleomycin in Saccharomyces cerevisiae
Authors: AOUIDA Mustapha , LEDUC Anick , WANG Huijie , RAMOTAR Dindial 
Published: November 2004

BLM (bleomycin) is effective in combination therapy against various cancers including testicular cancer. However, several other cancers such as colon cancer are refractory to BLM treatment. The exact mechanism for this differential response of cancer cells to the drug is not known. In the present study, we created fluorescently labelled BLM-A5, which retained nearly full genotoxic potential, and used this molecule to conduct the first study to understand the transport pathway of the drug in Saccharomyces cerevisiae. Uptake studies revealed that fluoro-BLM-A5 is transported into the cell in a concentration-dependent manner. Transport of a non-saturating concentration of fluoro-BLM-A5 was modest for the first 90 min, but thereafter it was sharply induced until 300 min. The inducible transport was completely abolished by the addition of cycloheximide, suggesting that BLM-A5 uptake into the cell is dependent on new protein synthesis. Interestingly, transport of fluoro-BLM-A5 was blocked if the cells were preincubated with increasing concentrations of spermine. Moreover, a mutant lacking the Ptk2 kinase, necessary for positively regulating polyamine transport, was defective in fluoro-BLM-A5 uptake and exhibited extreme resistance to the drug. A simple interpretation of these results is that BLM-A5 may enter the cell through the polyamine transport system. We showed further that after the uptake, fluoro-BLM-A5 accumulated into the vacuole of the parent, but localized to the cytoplasm of mutants disrupted for the END3 gene required for an early step of the endocytotic pathway. In general, mutants with a defect in the endocytic pathway to the vacuole were hypersensitive to BLM-A5. We suggest that BLM-A5 is transported across the yeast plasma membrane and sequestered into the vacuole for detoxification.
Effects of deletions at the C-terminus of tobacco acetohydroxyacid synthase on the enzyme activity and cofactor binding
Authors: KIM Joungmok , BEAK Dong-Gil , KIM Young-Tae , CHOI Jung-Do , YOON Moon-Young 
Published: November 2004

AHAS (acetohydroxyacid synthase) catalyses the first committed step in the biosynthesis of branched-chain amino acids, such as valine, leucine and isoleucine. Owing to the unique presence of these biosynthetic pathways in plants and micro-organisms, AHAS has been widely investigated as an attractive target of several classes of herbicides. Recently, the crystal structure of the catalytic subunit of yeast AHAS has been resolved at 2.8 Å (1 Å=0.1 nm), showing that the active site is located at the dimer interface and is near the herbicide-binding site. In this structure, the existence of two disordered regions, a ‘mobile loop’ and a C-terminal ‘lid’, is worth notice. Although these regions contain the residues that are known to be important in substrate specificity and in herbicide resistance, they are poorly folded into any distinct secondary structure and are not within contact distance of the cofactors. In the present study, we have tried to demonstrate the role of these regions of tobacco AHAS by constructing variants with serial deletions, based on the structure of yeast AHAS. In contrast with the wild-type AHAS, the truncated mutant which removes the C-terminal lid, Δ630, and the internal deletion mutant without the mobile loop, Δ567–582, impaired the binding affinity for ThDP (thiamine diphosphate), and showed different elution profiles representing a monomeric form in gel-filtration chromatography. Our results suggest that these regions are involved in the binding/stabilization of the active dimer and ThDP binding.
Guanidinium chloride denaturation of the dimeric Bacillus licheniformis BlaI repressor highlights an independent domain unfolding pathway
Authors: VREULS Christelle , FILÉE Patrice , VAN MELCKEBEKE Hélène , AERTS Tony , DE DEYN Peter , LLABRÈS Gabriel , MATAGNE André , SIMORRE Jean-Pierre , FRÈRE Jean-Marie , JORIS Bernard 
Published: November 2004

The Bacillus licheniformis 749/I BlaI repressor is a prokaryotic regulator that, in the absence of a β-lactam antibiotic, prevents the transcription of the blaP gene, which encodes the BlaP β-lactamase. The BlaI repressor is composed of two structural domains. The 82-residue NTD (N-terminal domain) is a DNA-binding domain, and the CTD (C-terminal domain) containing the next 46 residues is a dimerization domain. Recent studies have shown the existence of the monomeric, dimeric and tetrameric forms of BlaI in solution. In the present study, we analyse the equilibrium unfolding of BlaI in the presence of GdmCl (guanidinium chloride) using different techniques: intrinsic and ANS (8-anilinonaphthalene-l-sulphonic acid) fluorescence, far- and near-UV CD spectroscopy, cross-linking, analytical ultracentrifugation, size exclusion chromatography and NMR spectroscopy. In addition, the intact NTD and CTD were purified after proteolysis of BlaI by papain, and their unfolding by GdmCl was also studied. GdmCl-induced equilibrium unfolding was shown to be fully reversible for BlaI and for the two isolated fragments. The results demonstrate that the NTD and CTD of BlaI fold/unfold independently in a four-step process, with no significant co-operative interactions between them. During the first step, the unfolding of the BlaI CTD occurs, followed in the second step by the formation of an ‘ANS-bound’ intermediate state. Cross-linking and analytical ultracentrifugation experiments suggest that the dissociation of the dimer into two partially unfolded monomers takes place in the third step. Finally, the unfolding of the BlaI NTD occurs at a GdmCl concentration of approx. 4 M. In summary, it is shown that the BlaI CTD is structured, more flexible and less stable than the NTD upon GdmCl denaturation. These results contribute to the characterization of the BlaI dimerization domain (i.e. CTD) involved in the induction process.
Regulation of actin cytoskeleton by mDab1 through N-WASP and ubiquitination of mDab1
Authors: SUETSUGU Shiro , TEZUKA Tohru , MORIMURA Toshifumi , HATTORI Mitsuharu , MIKOSHIBA Katsuhiko , YAMAMOTO Tadashi , TAKENAWA Tadaomi 
Published: November 2004

Migration of cells is critical to development of the central nervous system. Reelin, which was identified from the reeler mutant mice having a defect in the multilamellar structure of the brain, is thought to be a key signalling molecule that functions as a cue for determination of cell position. mDab1 (mouse Disabled homologue 1) functions downstream of Reelin. However, the mechanism by which mDab1 regulates cell migration during brain development is unknown. In the present paper, we show that mDab1 associates with N-WASP (neuronal Wiskott–Aldrich syndrome protein) in vitro and in brains of embryonic mice. mDab1 activates N-WASP directly, and induces actin polymerization through the Arp2/3 (actin-related protein 2/3) complex. mDab1 induces formation of filopodia when it is overexpressed in COS-7 cells. This filopodium formation is dependent on N-WASP, because expression of an N-WASP mutant that cannot induce Arp2/3-complex-mediated actin polymerization suppressed filopodium formation. The PTB (phosphotyrosine-binding) domain of mDab1 binds to N-WASP via the NRFY (Asn-Arg-Phe-Tyr) sequence close to the CRIB (Cdc42/Rac-interactive binding) motif of N-WASP and activates N-WASP in vitro. When mDab1 is phosphorylated by Fyn kinase in COS-7 cells, mDab1 is ubiquitinated in a Cbl-dependent manner, and mDab1 does not induce filopodium in the presence of activated Fyn. These findings suggest that mDab1 regulates the actin cytoskeleton through N-WASP, which is negatively regulated by phosphorylation-mediated ubiquitination of mDab1.
Tc1/Tc2 ratio in the inflammatory process in patients with Behçet′s disease
Authors: Houman Habib , Hamzaoui Agnes , Ghorbal Imed Ben , Khanfir Monia Smiti , Feki Moncef , Hamzaoui Kamel 
Published: November 2004

BACKGROUND: Peripheral blood CD8+ T cells expressing interferon gamma and interleukin‐4 (IL‐4), and lacking CD28 molecules, were responsible for the dynamic interplay between peripheral blood and inflammatory sites.Introduction: The aim of the current study was to define in Behçet′s disease (BD), CD8+ T‐cell subsets using CD28 and CD11b monoclonal antibodies, and the characterization of the Tc1/Tc2 ratio and perforin expression.Methods: Flow cytometry was used for intracytoplasmic cytokines and perforin expression. Effector cells were investigated by adhesion of CD8+ T cells to human microvascular endothelial cells and by chemotaxis using β‐chemokine.Results: Interferon‐gamma‐producing CD8+ T cells in active and remission BD patients were increased, which induce a significant increase of the Tc1:Tc2 ratio in BD. CD8+CD28−CD11b+ T cells were found to be more expanded in BD patients than in age‐matched healthy controls. The expression of CD11b molecules in active BD allowed to CD8+CD28+/CD8+CD28− subsets to adhere to human microvascular endothelial cells, with more efficiency in BD. Using MIP‐1α, we observed that the migratory process of CD28−CD11b+ is more important in BD. CD28−CD11b+ exhibited an increased perforin expression in BD patients.Conclusion: Taken together these results suggest the presence of immune activation, probably in response to a profound inflammation affecting BD patients. The physiopathological significance of these results were toward autoimmune diseases and/or infectious process.
A PROGRAMMABLE ACTIVE MEMORY IMPLEMENTATION OF A NEURAL NETWORK FOR SECOND LEVEL TRIGGERING IN ATLAS
Authors: LUNDHEIM LARS , LEGRAND IOSIF , MOLL LAURENT 
Published: November 2004

In the second level triggering for ATLAS “Regions of Interest” (RoIs) are defined in (etha, phi) corresponding to possibly interesting particles. For each RoI physically meaningful parameters are extracted for each subdetector. Based on these parameters a classification of the particle type is made. A feed-forward neural net with 12 input variables, a 6-node intermediate layer, and 4 output nodes has earlier been suggested for this task. The reported work consists of an implementation of this neural net using a DECPeRLe-1, a Programmable Active Memory (PAM). This is a reconfigurable processor based on Field Programmable Gate Arrays (FPGAs), which has also been used for real-time implementation of feature extraction algorithms for second level triggering. The implementation is pipelined, runs with a clock of 25 MHz, and uses 0.64 microseconds for one particle classification. Integer arithmetic is used, and the performance is comparable to a floating point version.
ON NON-SUPERSYMMETRIC FINITE QUANTUM FIELD THEORIES
Authors: GRANDITS PETER 
Published: November 2004

In a previous paper, requiring finiteness of Yukawa couplings in one-loop approximation, a no-go theorem for the finiteness of non-supersymmetric gauge theories with gauge group SU (n) was proven. Interestingly enough the gauge group SU(5), prominent in GUT models, was not covered by this proof. However, with somewhat more effort the no-go theorem can be extended to this case. Considering an even larger class of particle contents, we show that the number of possibly finite theories is greatly reduced. It should be stressed that our results are based upon two-loop finiteness of the gauge coupling, although in order to find really finite theories the finiteness conditions on the quartic scalar couplings have to be considered too.
TACHYONS AND HIGHER ORDER WAVE EQUATIONS
Authors: BARCI D.G. , BOLLINI C.G. , ROCCA M.C. 
Published: November 2004

We consider a fourth order wave equation having normal as well as tachyonic solutions. The propagators are, respectively, the Feynman causal function and the Wheeler-Green function (half advanced and half retarded). The latter is consistent with the elimination of tachyons from free asymptotic states. We verify the absence of absorptive parts from convolutions involving the tachyon propagator.
KINETIC ENERGY AND PHASE SEPARATION IN A DOPED ANTIFERROMAGNET
Authors: XU XIN , SONG YUN , FENG SHIPING 
Published: November 2004

The ground-state kinetic energy of the t-J model is studied within the mean field approximation by using the fermion-spin transformation, the results show that the mean field ground-state kinetic energy is close to the numerical result at under dopings, and roughly consistent with the numerical result at optimal dopings. It is also shown that the frustration term J′ is favourable to diminish the range of the phase seperation in the t-J model.
NETWORKS OF RESONANT GRAVITATIONAL WAVE ANTENNAS
Authors: FRASCA S. , PAPA M.A. 
Published: November 2004

There are many reasons, other than that of excluding local disturbances, for using more gravitational antennas at the same time. In fact a network of resonant antennas allows — the detection of radiation coming from any direction and in any polarization state (sky coverage problem). — the estimate of some parameters of the source (information gain). — the verification of the predictions of general relativity regarding the features of gravitational waves (e.g. their propagation velocity, their quadrupole nature etc.) and the existence of celestial objects which cannot be observed other than through the gravitational effects they produce (e.g. black holes). — the enhancement of the noise rejection capability of the instrument thus enhancing its sensitivity (network filtering). Regarding this feature, some very interesting characteristics are exhibited by local networks of equal antennas (gravitational arrays). In this paper the major issues related to these problems will be presented and discussed and the experimental and theoretical results will briefly be reviewed. Some new ideas will also be introduced.