bluuebunny/crossref_metadata_2025 huggingface dataset:
Cytoprotection Following Endoplasmic Reticulum Stress Protein Induction in Continuous Cell Lines
Authors: Bedard Karen , MacDonald Nicole , Collins Jodie , Cribb Alastair
Published: March 2004

Abstract: Prior induction of an endoplasmic reticulum stress response has been associated with an increased tolerance to cellular toxins in in vitro systems, primarily involving renal and neuronal cells. Reactive intermediates are involved in toxicity in many tissues, therefore, we wished to determine if cytoprotection after induction of an endoplasmic reticulum stress response was a general phenomenon in other cell types. A stress response was induced by tunicamycin in a human hepatocyte cell line (HepG2), a rat hepatocyte cell line (H4IIE), a porcine kidney cell line (LLC‐PK1), and a human lymphocyte cell line (K562). Induction of the endoplasmic reticulum stress proteins GRP78, GRP94, calreticulin and protein disulfide isomerase was assessed by immunoblotting. Cytotoxicity was assessed 24 hr after a 3 hr exposure to iodoacetamide, tert‐butylhydrogenperoxide, menadione, or sulfamethoxazole hydroxylamine, or after a 2 hr exposure to N‐acetyl‐p‐benzoquinoneimine, the reactive metabolite of acetaminophen. Induction of endoplasmic reticulum stress proteins in LLC‐PK1 cells resulted in a 2–6 times increase in the concentration of all the cytotoxins required to cause a 50% decrease in cell viability at 24 hr. In contrast, tunicamycin pretreatment only resulted in a 1.7‐times increase for iodoacetamide in HepG2 cells and a 2.2‐times increase for N‐acetyl‐p‐benzoquinoneimine in the H4IIE cells, but had no effect on the other toxins tested. Induction of endoplasmic reticulum stress proteins in K562 cells did not alter susceptibility to any toxins tested. Our results indicate that protection afforded by the induction of an endoplasmic reticulum stress response is dependent on the cell type and may be toxin specific. These results suggest that either the molecular pathways of cell death for individual toxins are different between cell types and toxins, or that the function of endoplasmic reticulum stress proteins are dependent on the cell type.
Involvement of a Glutamatergic Mechanism in δ‐Dendrotoxin‐Induced Hippocampal Neuronal Cell Loss in the Rat
Authors: Bagetta Giacinto , Palma Ernesto , Piccirilli Silvia , Del Duca Claudio , Morrone A. Luigi , Nappi Giuseppe , Corasaniti M. Tiziana , Dolly J. Oliver
Published: March 2004

Abstract: The epileptogenic and neurodegenerative effects of δ‐dendrotoxin, from Dendroaspis angusticeps, a specific blocker of a non‐inactivating, voltage‐sensitive K+ channel, were studied after focal injection into one dorsal hippocampus in rats pretreated with CGP040116, a N‐methyl‐D‐aspartate (NMDA) receptor antagonist, and in rats bearing a monolateral surgical lesion of the Schaffer collaterals whose terminals originate from CA3 pyramids and release glutamate in the CA1 hippocampal area. Administration of 35 pmol δ‐dendrotoxin elicited in all of the treated animals (n=8) bilateral EEG discharges and damage to the hippocampal formation. Quantitation of the damage revealed significant bilateral neuronal cell loss in the CA1, CA3 and CA4 pyramidal cell layers. The lowest dose (0.35 pmol; n=4) of the toxin used did not affect EEG activity and failed to cause significant hippocampal cell loss whereas the 3.5 pmol (n=6) dose caused EEG seizures and hippocampal cell loss limited to the CA1 area. Systemic intraperitoneal administration of CGP040116 (5 mg/kg given 30 min. previously) delayed the onset of EEG seizures and reduced the number of epileptogenic discharges typically observed in rats receiving an injection of δ‐dendrotoxin (35 pmol) alone. Similarly, this treatment prevented the damage inflicted to the hippocampus by the toxin and in no instance was significant neuronal loss observed. Protection against seizures and hippocampal damage was also observed by a monolateral surgical lesion to the Schaffer collaterals. In conclusion, the present data suggest that an excitotoxic, glutamate‐mediated, type of mechanism underlies seizures and hippocampal damage induced by δ‐dendrotoxin in rats.
The Influence of Single or Repeated Low‐Level Sarin Exposure on Immune Functions of Inbred BALB/c Mice
Authors: Kassa Jiří , Kročová Z. , Ševelová L. , Sheshko V. , Kasalová I. , Neubauerová V.
Published: March 2004

Abstract: To study the influence of single or repeated low‐level sarin inhalation exposure on immune functions, inbred BALB/c mice were exposed to low clinically asymptomatic concentrations of sarin for 60 min. in the inhalation chamber. The evaluation of immune functions was carried out using phenotyping of CD3 (T‐lymphocytes), CD4 (helper T‐lymphocytes), CD8 (cytotoxic T‐lymphocytes) and CD19 cells (B‐lymphocytes) in the lungs, blood and spleen, lymphoproliferation of spleen cells stimulated in vitro by various mitogens (concanavalin A, lipopolysaccharides), phagocyte activity of peritoneal and alveolar macrophages, production of N‐oxides by peritoneal macrophages and the measurement of the natural killer cell activity at one week after sarin exposure. The results were compared to the values obtained from control mice exposed to pure air instead of sarin. The results indicate that an asymptomatic dose of sarin is able to alter the reaction of the immune system at one week after exposure to sarin. While the number of CD3 cells in lung was significantly decreased, a slight increase in CD19 cells was observed especially in the lungs after a single sarin inhalation exposure. Lymphoproliferation was significantly decreased regardless of the mitogen and sarin concentration used and the number of low‐level sarin exposures. The ability of peritoneal and alveolar macrophages to phagocyte the microbes was also decreased regardless of the number of low‐level sarin exposures. The production of N‐oxides by peritoneal macrophages was decreased following a single low‐level sarin exposure but increased following repeated low‐level sarin inhalation exposure. Nevertheless, the changes in the production of N‐oxides that reflects a bactericidal activity of peritoneal macrophages was not significant. The natural killer cell activity was significantly higher in the case of inhalation exposure of mice to low concentration of sarin regardless of the number of exposures. Thus, not only organophosphorous insecticides but also nerve agents such as sarin are able to alter immune functions following a single inhalation exposure even at a dose that does not cause clinically manifested intoxication. Generally, the repeated exposure to low concentrations of sarin does not increase the alteration of immune functions compared to the single low‐level sarin exposure with the exception of phagocyte activity of alveolar macrophages and natural killer cell activity.
The Influence of Amphotericin B and Neomycin on the Effect of Human Relaxin‐2 on Foetal Membranes and Isolated Myometrium
Authors: Vogel Ida , Grønbæk Henning , Uldbjerg Niels , Forman Axel
Published: March 2004

Abstract:In vitrostudies have documented effects of relaxin on utero‐placental tissues. Previously unpublished experiments indicate that neomycin and amphotericin Bin vitroinfluences the effect of human relaxin‐2 on the strength of human foetal membranes. The aim of the current study was to investigate the interaction between neomycin and amphotericin B and human relaxin‐2 using human foetal membranes, human myometrium and rat myometrium. Chloramphenicol, erythromycin and penicillin were also examined. Human foetal membranes were stretched until rupture in a materials‐testing machine while the contractility of rat and human myometrium were examined by myography. Human relaxin‐2 (hrlx‐2, 10−9M) induced a decreased strength in human foetal membranes, although this effect of hrlx‐2 was inhibited after co‐incubation with neomycin and amphotericin B. Hrlx‐2 (10−9M) in combination with chloramphenicol induced a decreased strength of human foetal membranes. Hrlx‐2 (10−9M) decreased myometrial contractility on amplitude and frequency in the rat myometrium, but had no effect on baseline tension. After exposure to amphotericin B, hrlx‐2 induced a more pronounced decrease in amplitude, increased baseline tension and increased the frequency of contractions of the rat myometrium. Hrlx‐2 (10−9M) had no effect on the human myometrium. However, after exposure to amphotericin B or neomycin+amphotericin B, hrlx‐2 induced an increase in baseline tension and a decrease in amplitude. Amphotericin B and neomycin+amphotericin B increased the frequency of contractions and this effect was further enhanced by the addition of hrlx‐2. We therefore conclude that amphotericin B and neomycin + amphotericin B may have an influence on relaxin's effect on isolated foetal membranes and myometrium.
Stimulation of Interleukin-10 Production by Acidic β-Lactoglobulin-Derived Peptides Hydrolyzed withLactobacillus paracaseiNCC2461 Peptidases
Authors: Prioult Guénolée , Pecquet Sophie , Fliss Ismail
Published: March 2004

We have previously demonstrated thatLactobacillus paracaseiNCC2461 may help to prevent cow's milk allergy in mice by inducing oral tolerance to β-lactoglobulin (BLG). To investigate the mechanisms involved in this beneficial effect, we examined the possibility thatL. paracaseiinduces tolerance by hydrolyzing BLG-derived peptides and liberating peptides that stimulate interleukin-10 (IL-10) production.L. paracaseipeptidases have been shown to hydrolyze tryptic-chymotryptic peptides from BLG, releasing numerous small peptides with immunomodulating properties. We have now shown that acidic tryptic-chymotryptic peptides stimulate splenocyte proliferation and gamma interferon (IFN-γ) production in vitro. Hydrolysis of these peptides withL. paracaseipeptidases repressed the lymphocyte stimulation, up-regulated IL-10 production, and down-regulated IFN-γ and IL-4 secretion.L. paracaseiNCC2461 may therefore induce oral tolerance to BLG in vivo by degrading acidic peptides and releasing immunomodulatory peptides stimulating regulatory T cells, which function as major immunosuppressive agents by secreting IL-10.
Development and Evaluation of a Tetraplex Flow Cytometric Assay for Quantitation of Serum Antibodies to
Neisseria meningitidis
Serogroups A, C, Y, and W-135
Authors: Lal Gouri , Balmer Paul , Joseph Helen , Dawson Maureen , Borrow Ray
Published: March 2004

A rapid and simple method for the simultaneous quantitation of serum immunoglobulin G (IgG) antibodies specific for
Neisseria meningitidis
serogroups A, C, Y, and W-135 was developed and evaluated. Four bead sets were generated, each conjugated with one of the meningococcal capsular polysaccharides (A, C, Y, or W-135) and serologically assessed by the use of antimeningococcal international reference sera. Cross-reactivity studies demonstrated no inhibition between monoplex and multiplex assays, and the assay was linear over a 24-fold serum dilution range. Inhibition studies demonstrated that the assay is specific, with <25% heterologous inhibition occurring. The assay was also found to have low intra- and interassay variations and limits of detection ≤650 pg/ml. A comparison of the meningococcal bead assay with the standardized meningococcal enzyme-linked immunosorbent assay showed a good correlation between the IgG concentrations obtained by each assay. The tetraplex assay has the potential to be an important addition to the serologic evaluation of meningococcal capsular polysaccharide conjugate vaccines.
Heterophile Antibody Interference in a Multiplexed Fluorescent Microsphere Immunoassay for Quantitation of Cytokines in Human Serum
Authors: Martins Thomas B. , Pasi Brian M. , Litwin Christine M. , Hill Harry R.
Published: March 2004

While modern immunoassays provide sensitive and specific means for the quantitation of cytokines in biological fluids, heterophile antibodies are still a well-recognized cause of interference in the measurement of cytokines in these assays. We have developed a multiplexed fluorescent microsphere immunoassay for the simultaneous quantification of 10 cytokines in only 75 μl of serum. During the development of this multiplexed assay, the amount of assay interference due to heterophile antibodies was also determined, and methods for detecting heterophile interference and minimizing its effect were incorporated into the assay. Heterophile antibodies resulted in significantly elevated cytokine values compared to those of normal blood bank samples. These falsely elevated values, and thus the components of the assay the heterophile antibodies were binding to, were identified through the use of internal controls. This information was then used to design assay-specific blockers and absorbents that were shown to significantly reduce falsely elevated cytokine values while not affecting the standard and control values. The fluorescent multiplexed microsphere-based immunoassay can be used to quantitate multiple cytokines from a single sample and should be a useful tool in furthering our understanding of the role of cytokines in disease processes.
Circulating β (1-3) Glucan and Immunoglobulin G Subclass Antibodies toCandida albicansCell Wall Antigens in Patients with Systemic Candidiasis
Authors: Kondori N. , Edebo L. , Mattsby-Baltzer I.
Published: March 2004

Invasive candidiasis in patients who are immunocompromised or in intensive care units (ICUs) presents both diagnostic and therapeutic problems. We previously described antibodies that were directed againstCandida albicanscell wall fragments (CW), periodate-treated CW (CWIO4), phosphopeptidomannan (PPM), and β(1-3) glucan. In this study, circulating fungal antigens [mannan and β(1-3) glucan] and immunoglobulin G (IgG) subclass antibodies to these cell wall antigens (anti-CW) were analyzed in patients with systemic candidiasis. Sera were collected from 14 patients on two or three consecutive occasions, starting on the day when candidiasis was culture proven. The sera were analyzed by enzyme-linked immunosorbent assay. The control groups consisted of lactating mothers (n= 9) (group I) who had breast milk that was positive forC. albicansand also had acute inflammation of the nipples, and age-matched blood donors (n= 10) (group II). Within the first 3 weeks ofCandidainfection all of the patients were positive for β(1-3) glucan by the Gluspecy test, but no patients were positive for mannan in the less-sensitive PastorexCandidatest. The controls were negative for both β(1-3) glucan (<20 pg/ml) and mannan (<2.5 ng/ml). IgG1 anti-CW and IgG2 anti-PPM antibodies were the most discriminatory antibodies. The ratio of IgG1 anti-CW to IgG2 anti-PPM was significantly lower in nonsurviving patients than in the other patients within the first week of candidiasis (P= 0.019). The IgG2 levels of anti-CWIO4and antiglucan antibodies correlated strongly (r= 0.681;P< 0.0001), and the absence of these antibodies was associated with increased levels of β(1-3) glucan. Increased levels of IgG1 anti-CW or IgG2 anti-PPM antibodies (titer of ≥3 logs) or of a combination of the two antibodies (log sum, ≥5) showed 92% sensitivity, 100% specificity, and positive predictive values. In conclusion, β(1-3) glucan and the two subclass antibodies appear to be early specific markers for the laboratory diagnosis of candidiasis. Furthermore, the kinetics of β(1-3) glucan appearance in serum may assist in evaluating the therapeutic efficacy of antifungal treatments.
Establishment of an Animal Model Using Recombinant NOD.B10.D2Mice To Study Initial Adhesion of Oral Streptococci
Authors: Salam Mohammad Abdus , Matsumoto Naoko , Matin Khairul , Tsuha Yuzo , Nakao Ryoma , Hanada Nobuhiro , Senpuku Hidenobu
Published: March 2004

An oral biofilm is a community of surface-attached microorganisms that coats the oral cavity, including the teeth, and provides a protective reservoir for oral microbial pathogens, which are the primary cause of persistent and chronic infectious diseases in patients with dry mouth or Sjögren's syndrome (SS). The purpose of this study was to establish an animal model for studying the initial adhesion of oral streptococci that cause biofilm formation in patients with dry mouth and SS in an attempt to decrease the influence of cariogenic organisms and their substrates. In nonobese diabetogenic (NOD) mice that spontaneously develop insulin-dependent diabetes mellitus (IDDM) and SS, we replaced major histocompatibility complex (MHC) class II (Ag7Eg7) and class IDbwith MHC class II (AdEd) and class IDdfrom nondiabetic B10.D2 mice to produce an animal model that inhibited IDDM without affecting SS. The adhesion of oral streptococci, includingStreptococcus mutans, onto tooth surfaces was then investigated and quantified in homologous recombinant N5 (NOD.B10.D2) and N9 (NOD.B10.D2) mice. We found that a higher number of oral streptococci adhered to the tooth surfaces of N5 (NOD.B10.D2) and N9 (NOD.B10.D2) mice than to those of the control C57BL/6 and B10.D2 mice. On the basis of our observation, we concluded that these mouse models might be useful as animal models of dry mouth and SS for in vivo biological studies of oral biofilm formation on the tooth surfaces.
Molecular Expression of a Cysteine Proteinase of
Clonorchis sinensis
and Its Application to an Enzyme-Linked Immunosorbent Assay for Immunodiagnosis of Clonorchiasis
Authors: Nagano Isao , Pei Fuquan , Wu Zhiliang , Wu Jun , Cui Huier , Boonmars Thidarut , Takahashi Yuzo
Published: March 2004

We produced a recombinant cysteine proteinase of
Clonorchis sinensis
and tested its value as an antigen for serologic diagnosis of
C. sinensis
infections. The predicted amino acid sequence of the cysteine proteinase of
C. sinensis
was 58, 48, and 40% identical to those of cathepsin L cysteine proteinases from
Paragonimus westermani
,
Schistosoma japonicum
, and
Fasciola hepatica
, respectively. Western blotting analysis showed that sera from patients infected with
C. sinensis
strongly reacted with the recombinant protein and that sera from patients infected with
S. japonicum
weakly reacted with the recombinant protein. Antibody against the recombinant protein stained proteins migrating at about 37 and 28 kDa in
C. sinensis
adult worm crude extracts. Immunostaining revealed that the cysteine proteinase of
C. sinensis
was located in the intestinal epithelial cells of the adult parasite and in intrauterine eggs. The specificity and sensitivity of the recombinant antigen or
C. sinensis
adult worm crude extracts were assessed by an enzyme-linked immunosorbent assay (ELISA) using serum samples from humans infected with different parasites, including 50 patients with clonorchiasis, and negative controls. The sensitivities of the ELISA with the recombinant antigen and
C. sinensis
adult worm crude extracts were 96 and 88%, respectively. The specificities of the ELISA with the recombinant antigen and
C. sinensis
adult worm crude extracts were 96.2 and 100%, respectively. The results suggested that the recombinant cysteine proteinase-based ELISA could provide a highly sensitive and specific assay for diagnosis of clonorchiasis.
Development of a Western Blot Assay for Detection of Antibodies against Coronavirus Causing Severe Acute Respiratory Syndrome
Authors: He Qigai , Chong Kooi Hoong , Chng Hiok Hee , Leung Bernard , Ling Ai Ee , Wei Ting , Chan Shzu-Wei , Ooi Eng Eong , Kwang Jimmy
Published: March 2004

To identify a major antigenic determinant for use in the development of a rapid serological diagnostic test for severe acute respiratory syndrome (SARS) coronavirus infection and to study the immune response during SARS coronavirus infection in humans, we cloned the full length and six truncated fragments of the nucleocapsid gene, expressed them, and purified them as glutathione
S
-transferase-tagged recombinant proteins. The reactivities of the recombinant proteins to a panel of antibodies containing 33 SARS coronavirus-positive sera and 66 negative sera and to antibodies against other animal coronaviruses were screened. A truncated 195-amino-acid fragment from the C terminus of the nucleocapsid protein (N195) was identified that had a strong ability to detect antibodies against SARS coronavirus. No cross-reaction was found between the N195 protein and antibodies against chicken, pig, and canine coronaviruses. The N195 protein was used to develop a Western blot assay to detect antibodies against SARS coronavirus in 274 clinically blinded samples. The specificity and sensitivity of this test were 98.3 and 90.9%, respectively. The correlation between our Western blotting assay and an immunofluorescence assay (IFA) was also analyzed. The results of our Western blot assay and IFA for the detection of SARS coronavirus-positive sera were the same. Thus, the N195 protein was identified as a suitable protein to be used as an antigen in Western blot and other possible assays for the detection of SARS coronavirus infection.
Extracellular Calcium and Magnesium, but Not Iron, Are Needed for Optimal Growth ofBlastomyces dermatitidisYeast Form Cells In Vitro
Authors: Giles Steven S. , Czuprynski Charles J.
Published: March 2004

In the present study, we demonstrate that the yeast form ofBlastomyces dermatitidiscan proliferate for short periods of time in the absence of ferric iron but not in the absence of calcium or magnesium. The results of this study shed light on the resistance ofB. dermatitidisto chelating agents, such as deferoxamine, and may explain howB. dermatitidisresists the iron-binding activity of serum transferrin.
Use of hospitals, physician visits, and hospice care during last six months of life among cohorts loyal to highly respected hospitals in the United States
Authors: Wennberg John E , Fisher Elliott S , Stukel Thérèse A , Skinner Jonathan S , Sharp Sandra M , Bronner Kristen K
Published: March 2004

Objective To evaluate the use of healthcare resources during the last six months of life among patients of US hospitals with strong reputations for high quality care in managing chronic illness.

Design Retrospective cohort study based on claims data from the US Medicare programme.

Participants Cohorts receiving most of their hospital care from 77 hospitals that appeared on the 2001 US News and World Report “best hospitals” list for heart and pulmonary disease, cancer, and geriatric services.

Main outcome measures Use of healthcare resources in the last six months of life: number of days spent in hospital and in intensive care units; number of physician visits; percentage of patients seeing 10 or more physicians; percentage enrolled in hospice. Terminal care: percentage of deaths occurring in hospital; percentage of deaths occurring in association with a stay in an intensive care unit.

Results Extensive variation in each measure existed among the 77 hospital cohorts. Days in hospital per decedent ranged from 9.4 to 27.1 (interquartile range 11.6-16.1); days in intensive care units ranged from 1.6 to 9.5 (2.6-4.5); number of physician visits ranged from 17.6 to 76.2 (25.5-39.5); percentage of patients seeing 10 or more physicians ranged from 16.9% to 58.5% (29.4-43.4%); and hospice enrolment ranged from 10.8% to 43.8% (22.0-32.0%). The percentage of deaths occurring in hospital ranged from 15.9% to 55.6% (35.4-43.1%), and the percentage of deaths associated with a stay in intensive care ranged from 8.4% to 36.8% (20.2-27.1%).

Conclusion Striking variation exists in the utilisation of end of life care among US medical centres with strong national reputations for clinical care.
Association between depression and abuse by partners of women attending general practice: descriptive, cross sectional survey
Authors: Hegarty Kelsey , Gunn Jane , Chondros Patty , Small Rhonda
Published: March 2004

Objective To explore the association between depression and physical, emotional, and sexual abuse by partners or ex-partners of women attending general practice.

Design Descriptive, cross sectional survey.

Setting 30 general practitioners in Victoria, Australia.

Participants 1257 consecutive female patients.

Main outcome measures Some type of abuse in an adult intimate relationship (composite abuse scale), depression (Beck depression inventory or Edinburgh postnatal depression scale), and physical health (SF-36).

Results 18.0% (218/1213) of women scored as currently probably depressed and 24.1% (277/1147) had experienced some type of abuse in an adult intimate relationship. Depressed women were significantly more likely to have experienced severe combined abuse than women who were not depressed after adjusting for other significant sociodemographic variables (odds ratio 5.8, 95% confidence interval 2.8 to 12.0). These variables included not being married, having a poor education, being on a low income, being unemployed or receiving a pension, pregnancy status, or being abused as a child.

Conclusion Physical, emotional, and sexual abuse are strongly associated with depression in women attending general practice. Doctors should sensitively ask depressed women about their experiences of violence and abuse in intimate relationships. Research into depression should include measures of partner abuse in longitudinal and intervention studies.
Radiative effects on forced convection flows in micropolar fluids with variable viscosity
Authors: El-Kabeir S M
Published: March 2004

The interaction of forced convection and thermal radiation during the flow of a surface moving continuously in a flowing stream of micropolar fluid with variable viscosity is studied. Two cases are considered: one corresponding to a plane surface moving in parallel with the free stream, the other to a surface moving in the opposite direction to the free stream. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The viscosity of the fluid is taken as a function of temperature. PACS No.: 44.27.+g
Density matrix renormalization group studies on the stability of quasi-1-D undoped and doped polymer ferromagnets
Authors: Yao K L , Liu X W , Liu Q M , Sun G Y , Liu Z L
Published: March 2004

We study the ferromagnetic ground state of the theoretical model proposed for quasi-one-dimensional organic polymer ferromagnets by using the density matrix renormalization group method. We find that the chainradical interaction, the on-site electronelectron repulsion, and the electronphonon coupling play important roles in the stability of the ferromagnetic state, whether in doped systems or not. We are convinced that when the system is doped by one electron, a polaron appears, diminishing the stability of the high-spin state.PACS No.: 75.10.Jm
Radiation characteristics of N axially slotted antenna on a lossy dielectric-coated elliptic cylinder
Authors: Hussein M I , Hamid A -K
Published: March 2004

The radiation properties of N axially slotted antenna on a lossy dielectric-coated elliptic cylinder are investigated. The analysis is carried out by expressing the fields inside and outside the antenna structure in terms of elliptic waves using complex Mathieu functions. The boundary conditions at various surfaces are employed to obtain the unknown field expansion coefficients. Numerical results are presented graphically for the radiation pattern, aperture conductance, and antenna gain for the transverse magnetic field case. PACS No.: 84.40.Ba
Particule de spin 0 dans un potentiel d'AharonovBohm
Authors: Boumali A
Published: March 2004

Dans ce présent article, nous discutons l'interaction de la particule de spin 0 avec un potentiel d'AharonovBohm à deux et trois dimensions par l'application de l'équation de DuffinKemmerPetiau. Le spectre d'énergie et sa dépendance avec l'intensité du potentiel d'AharonovBohm sont analysés.PACS Nos : 03.65.Pm, 03.65.Ge
An attempt to close the EinsteinPodolskyRosen debate
Authors: Krüger T
Published: March 2004

Based on a new rigorous ensemble approach to quantum mechanics, and without stressing any idea or concept of reality, the entire EinsteinPodolskyRosen (EPR) problem can be boiled down to the question of whether the separability principle of the natural sciences is universally valid. To give a precise answer first of all Bell's inequality is deduced from said ensemble point of view and with minimal requirements only. (In the final discussion of the results it turns out that Bell's inequality defines the upper bound for those basic correlations that are due to a mere conservation law.) Then, by use of Wheeler's gedanken experiment with coin halves, I show that the statistical operator representing an ensemble under investigation may be either separable (in a simplified sense) or not. The conceptual consequences of nonseparability are explained, and a general EPR-type experiment is re-examined. Thereby, it is proven that, if and only if, the statistical operator is nonseparable, Bell's inequality may be violated. Experimental evidence demands nonseparable operators. So, if quantum mechanics is assumed to make statistical statements on the results of measurements on ensembles only, there is no way to avoid acceptance of its (operationally) holistic character, and the question posed at the outset must be negated. PACS Nos : 03.65.Ta, 03.65.Ud
The 2S1/22P1/2 Lamb shift in He+
Authors: Jentschura U D , Drake G WF
Published: March 2004

The current theoretical status of the Lamb shift in He+ is discussed. Recent calculations of two-loop binding corrections to the Lamb shift significantly shift the theoretical value of the "classic" Lamb shift in He+, i.e., of the 2S1/22P1/2 interval. In this brief article, we present a new (theoretical) value for this interval that reads 14 041.474(42) MHz. The theoretical uncertainty is reduced as well as the discrepancy between theory and experiment. Planned measurements should be of help in further elucidating the situation.PACS Nos.: 31.15.p, 12.20.Ds
Unsteady Hartmann flow with heat transfer of a viscoelastic fluid considering the Hall effect
Authors: Attia H A
Published: March 2004

The unsteady Hartmann flow, with heat transfer, of an electrically conducting incompressible non-Newtonian viscoelastic fluid between two parallel horizontal nonconducting porous plates is studied taking into consideration the Hall effect. A sudden uniform and constant-pressure gradient, an external uniform magnetic field that is perpendicular to the plates, and uniform suction and injection through the surface of the plates are applied. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are taken into consideration. Numerical solutions for the governing momentum and energy equations are obtained using finite-difference approximations. The effect of the Hall term, the parameter describing the non-Newtonian behavior, and the velocity of suction and injection on both the velocity and temperature distributions is examined.PACS No.: 47.27.-i
Azimuthal distribution and transverse flow in high-energy nucleusnucleus collisions
Authors: Liu F -H
Published: March 2004

We use a new formula to describe the azimuthal distribution of final-state particles in high-energy nucleusnucleus collisions. The transverse flow (directed flow and elliptic flow) characteristics are obtained. The corresponding deformed and moving emission source in the momentum space in the transverse plane are given. PACS Nos.: 25.75.q; 24.10.Pa
Time reversal and a stochastic model of the Dirac equation in an electromagnetic field
Authors: McKeon D.G.C. , Ord G N
Published: March 2004

We extend a stochastic model underlying the Dirac equation in 1+1 dimensions to include the electromagnetic field. The model obtains the Dirac equation without requiring a formal analytic continuation. The mechanism, which produces quantum behaviour, is the allowed Brownian motion in time. The microscopic time reversals in the Brownian motion are the source of quantum interference. The electromagnetic field is also obtained from a stochastic model and the interaction with Dirac particles is treated as a scattering process.PACS Nos.: 03.65.-w, 03.20.+i, 05.40.+j
Détermination du coefficient d'absorption des rayons X à partir des mesures de réflectométrie X
Authors: Ech-chamikh E , Aboudihab I , Azizan M , Essafti A , Ijdiyaou Y
Published: March 2004

In this paper, we present a simple method that allows, among other things, to determine the absorption coefficient of X-rays from reflectivity measurements. This method is applicable if the analysed material is deposited on a substrate denser than the material layer, so that the X-rays reflectivity spectra exhibit two well-resolved descents. In such cases, the amplitude of the first descent (characteristic of the material layer) is directly related to the linear absorption coefficient of the material constituting the layer. We have been able to clarify this relationship and apply it successfully for several cases of materials, especially amorphous carbon and silicon. Values of thus obtained mass absorption coefficients are in very good agreement with those tabulated in the literature.[Journal translation]
Towards the consistent histories approach to quantum mechanics
Authors: Sarkardei M R
Published: March 2004

We introduce and review the consistent (decoherent) histories approach to quantum mechanics due to Griffiths, to Gell-Mann and Hartle, and to Omnes. We will not attempt an in depth look at this approach as it would be impossible to treat it in such a short review. The emphasis is on understanding the broader meaning of the consistency and decoherence. The consistent history approach to quantum mechanics provides a precise conceptual framework for describing how a closed quantum system develops in time. The approach also provides a framework from which we may observe the emergence of an approximately classical domain for macroscopic systems, together with the conventional Copenhagen quantum mechanics for microscopic subsystems. We will study the formalism of decoherence and look at several approaches to decoherence. In examining a system of quantum Brownian motion and using the methods of Feynman and Vernon, we derive an equation of motion for the density matrix, the master equation of the system. This leads us to a brief overview of decoherence. PACS Nos.: 03.65.Ta, 03.65.w, 03.65.Yz, 04.60.m, 05.30.d
Nonlocal equation of state in anisotropic static fluid spheres in general relativity
Authors: Hernández H , Núñez L A
Published: March 2004

We show that it is possible to obtain, at least certain regions within spherically symmetric static matter configurations, credible anisotropic fluids satisfying a nonlocal equation of state. This particular type of equation of state provides, at a given point, the radial pressure not only as a function of the density at that point, but its functional throughout the enclosed distribution. To establish the physical plausibility of the proposed family of solutions satisfying a nonlocal equation of state, we study the constraints imposed by the junction, energy, and some intuitive physical conditions. We show that these static fluids having this particular equation of state are "naturally" anisotropic in the sense that they satisfy, identically, the anisotropic TolmanOppenheimerVolkov equation. We also show that it is possible to obtain physically plausible static anisotropic spherically symmetric matter configurations starting from known density profiles, and also for configurations where tangential pressures vanish. This very particular type of relativistic sphere with vanishing tangential stresses is inspired by some of the models proposed to describe extremely magnetized neutron stars (magnetars) during the transverse quantum collapse.
BoseEinstein condensation in a QUIC trap
Authors: Lu B , van Wijngaarden W A
Published: March 2004

The apparatus and procedure required to generate a pure Bose-Einstein condensate (BEC) consisting of about half a million 87Rb atoms at a temperature of <60 nK with a phase density of >54 is described. The atoms are first laser cooled in a vapour cell magneto-optical trap (MOT) and subsequently transferred to an ultra-low pressure MOT. The atoms are loaded into a QUIC trap consisting of a pair of quadrupole coils and a Ioffe coil that generates a small finite magnetic field at the trap energy minimum to suppress Majorana transitions. Evaporation induced by an RF field lowers the temperature permitting the transition to BEC to be observed by monitoring the free expansion of the atoms after the trapping fields have been switched off.PACS Nos.: 03.75.Fi, 05.30.Jp, 32.80.Pj, 64.60.i
ESSENTIAL PROPERTIES OF THE VACUUM SECTOR FOR A THEORY OF SUPERSELECTION SECTORS
Authors: RUZZI GIUSEPPE
Published: March 2004

As a generalization of DHR analysis, the superselection sectors are studied in the absence of the spectrum condition for the reference representation. Considering a net of local observables in 4-dimensional Minkowski spacetime, we associate to a set of representations, that are local excitations of a reference representation fulfilling Haag duality, a symmetric tensor C*-category [Formula: see text] of bimodules of the net, with subobjects and direct sums. The existence of conjugates is studied introducing an equivalent formulation of the theory in terms of the presheaf associated with the observable net. This allows us to find, under the assumption that the local algebras in the reference representation are properly infinite, necessary and sufficient conditions for the existence of conjugates. Moreover, we present several results that suggest how the mentioned assumption on the reference representation can be considered essential also in the case of theories in curved spacetimes.
ASPECTS OF NONCOMMUTATIVE LORENTZIAN GEOMETRY FOR GLOBALLY HYPERBOLIC SPACETIMES
Authors: MORETTI VALTER
Published: March 2004

Connes' functional formula of the Riemannian distance is generalized to the Lorentzian case using the so-called Lorentzian distance, the d'Alembert operator and the causal functions of a globally-hyperbolic spacetime. As a step of the presented machinery, a proof of the almost-everywhere smoothness of the Lorentzian distance considered as a function of one of the two arguments is given. Afterwards, using a C*-algebra approach, the spacetime causal structure and the Lorentzian distance are generalized into noncommutative structures giving rise to a Lorentzian version of part of Connes' noncommutative geometry. The generalized noncommutative spacetime consists of a direct set of Hilbert spaces and a related class of C*-algebras of operators. In each algebra a convex cone made of self-adjoint elements is selected which generalizes the class of causal functions. The generalized events, called loci, are realized as the elements of the inductive limit of the spaces of the algebraic states on the C*-algebras. A partial-ordering relation between pairs of loci generalizes the causal order relation in spacetime. A generalized Lorentz distance of loci is defined by means of a class of densely-defined operators which play the role of a Lorentzian metric. Specializing back the formalism to the usual globally-hyperbolic spacetime, it is found that compactly-supported probability measures give rise to a non-pointwise extension of the concept of events.
CONFINEMENT TO LOWEST LANDAU BAND AND APPLICATION TO QUANTUM CURRENT
Authors: FOURNAIS S.
Published: March 2004

In this paper we study neutral atoms of nuclear charge Z in a strong constant magnetic field of strength B. We improve the bound on confinement to the lowest Landau band given by Lieb, Solovej and Yngvason in [1]. This permits the calculation of the asymptotic form of the quantum current of atoms in the parameter region [Formula: see text].
WIGNER MEASURES AND MOLECULAR PROPAGATION THROUGH GENERIC ENERGY LEVEL CROSSINGS
Authors: FERMANIAN KAMMERER CLOTILDE
Published: March 2004

We study the time-dependent Schrödinger equation with matrix-valued potential presenting a generic crossing of type B, I, J or K in Hagedorn's classification. We use two-scale Wigner measures for describing the Landau–Zener energy transfer which occurs at the crossing. In particular, in the case of multiplicity 2 eigenvalues, we calculate precisely the change of polarization at the crossing. Our method provides a unified framework in which codimension 2, 3 or 5 crossings can be discussed. We recover Hagedorn's result for wave packets, from Wigner measure point of view, and extend them to any data uniformly bounded in L2. The proof is based on a normal form theorem which reduces the problem to an operator-valued Landau–Zener formula.
FREQUENCY-RESPONSE MASKING BASED FIR FILTER DESIGN WITH POWER-OF-TWO COEFFICIENTS AND SUBOPTIMUM PWR
Authors: LEE W. R. , REHBOCK V. , TEO K. L. , CACCETTA L.
Published: March 2004

This paper presents a new method for designing sharp linear phase FIR filters with power-of-two coefficients. The method is based on a frequency-response masking technique. In this method, the power-of-two coefficients and continuous scaling parameters of the subfilters are taken to be decision variables, and minimizing peak weighted ripple (PWR) is taken to be the design objective. The resulting nonlinear mixed integer optimization problem for each subfilter is first reduced to an equivalent discrete optimization problem whose search region is then cropped for efficiency of computation, similar to the approach in Ref. 1, although a different cropping strategy is used here. The effectiveness of the method is demonstrated through a lowpass linear phase sharp FIR digital filter example.
EFFICIENT DESIGN OF NARROWBAND COSINE-MODULATED FILTER BANKS USING A TWO-STAGE FREQUENCY-RESPONSE MASKING APPROACH
Authors: NETTO SERGIO L. , de BARCELLOS LUIZ C. R. , DINIZ PAULO S. R.
Published: March 2004

A new cosine-modulated filter bank (CMFB) structure is proposed based on the frequency-response masking (FRM) approach using masking filter decomposition. The resulting structure, the so-called FRM2-CMFB, presents reasonable computational complexity (number of arithmetic operations per output sample) and allows one to design filter banks with extremely large number of bands. The examples include the use of M=1024 bands, where the standard minimax method cannot be employed. These examples indicate that the reduction in computational complexity can be as high as 60% of the original FRM-CMFB structure, which does not use masking filter decomposition.
A MODIFIED FREQUENCY-RESPONSE MASKING STRUCTURE FOR HIGH-SPEED FPGA IMPLEMENTATION OF SHARP FIR FILTERS
Authors: LIAN YONG
Published: March 2004

This paper presents the design and implementation of high-speed, multiplierless, arbitrary bandwidth sharp FIR filters based on frequency-response masking (FRM) technique. The FRM filter structure has been modified to improve the throughput rate by replacing long band-edge shaping filter in the original FRM approach with two to three cascaded short filters. The proposed structure is suitable for FPGA as well as VLSI implementation for sharp digital FIR filters. It is shown by an example that a near 200-tap equivalent Remez FIR filter can be implemented in a single Xilinx XC4044XLA device that operates at sampling frequency of 5.5 MHz.
OPTIMIZATION OF FREQUENCY-RESPONSE MASKING BASED FIR FILTERS
Authors: SARAMÄKI TAPIO , YLI-KAAKINEN JUHA , JOHANSSON HÅKAN
Published: March 2004

A very efficient technique to drastically reduce the number of multipliers and adders in implementing linear-phase finite-impulse response (FIR) digital filters in applications demanding a narrow transition band is to use the frequency-response masking (FRM) approach originally introduced by Lim. The arithmetic complexity can be even further reduced using a common filter part for constructing the masking filters originally proposed by Lim and Lian. A drawback in the above-mentioned original FRM synthesis techniques is that the subfilters in the overall implementations are separately designed. In order to further reduce the arithmetic complexity in these two FRM approaches, the following two-step optimization technique is proposed for simultaneously optimizing the subfilters. At the first step, a good suboptimal solution is found by using a simple iterative algorithm. At the second step, this solution is then used as a start-up solution for further optimization being carried out by using an efficient unconstrained nonlinear optimization algorithm. An example taken from the literature illustrates that both the number of multipliers and the number of adders for the resulting optimized filter are less than 80% compared with those of the FRM filter obtained using the original FRM design schemes in the case where the masking filters are separately implemented. If a common filter part is used for realizing the masking filters, then an additional reduction of more than 10% is achieved compared with the optimized design with separately implemented masking filters.
APPLICATION OF FAST FILTER BANK FOR TRANSCRIPTION OF POLYPHONIC SIGNALS
Authors: FOO SAY WEI , LEE EDWIN WEI THAI
Published: March 2004

In this paper, a novel approach to the transcription of polyphonic signals is investigated. The method makes use of top–down analysis algorithm and bottom–up reconstruction of frequency contents of musical signals using a reference database that contains the spectral profiles of all single notes. Recognition accuracy is enhanced by analyzing the time-frequency contents using a bank of narrow band filters with very sharp transition band. The filters are designed using the Frequency-Response Masking technique. The high selectivity of the filters has enhanced the frequency analysis and increased the accuracy of identification. The method was tested with musical notes generated from an acoustic piano. The results show that for single notes and chords up to four notes, perfect identification can be achieved.
SINGLE FILTER FREQUENCY-RESPONSE MASKING FIR FILTERS
Authors: GUSTAFSSON OSCAR , JOHANSSON HÅKAN , WANHAMMAR LARS
Published: March 2004

In this work filter structures that decrease the required number of multipliers and adders for implementation of linear-phase FIR filters using frequency-response masking techniques are introduced. The basic idea of the proposed structures is that identical subfilters are used. This leads to the same arithmetic structure can be multiplexed in the implementation, reducing the number of required multipliers and adders. The subfilters are mapped using the folding transformation to obtain an area-efficient time-multiplexed (or pipeline/interleaved) implementation. Both narrow-band and wide-band frequency-response masking as well as arbitrary bandwidth frequency-response masking techniques are considered. The filter design is discussed and for each filter structure the limits on the specifications are derived. Designed examples show the usefulness of the proposed structures.
ON WANDERING AND BAKER DOMAINS OF TRANSCENDENTAL ENTIRE FUNCTIONS
Authors: WANG XIAOLING , YANG CHUNG-CHUN
Published: March 2004

Let f denote a transcendental entire function, and I(f), I0(f), T(f) and A(f) be denoted as follows: [Formula: see text][Formula: see text] Let D denote a Fatou component of F(f). We have established the relationships between D and I(f), I0(f), T(f) or A(f), when D is a Baker domain or a multiply-connected wandering domain or a simply-connected infinitely wandering domain.
DYNAMICS AND MODULATED CHAOS FOR TWO COUPLED OSCILLATORS
Authors: BI QINSHENG
Published: March 2004

The dynamical behavior of two coupled parametrically excited van der Pol oscillators is investigated in this paper. A special road to chaos is explored in detail. Period-doubling bifurcation associated with one of the frequencies of the system may be observed, the other frequency of the coupled oscillators plays a role in the evolution. It is found that one of the frequencies of the system contributes to the cascade of period-doubling bifurcations associated with the other frequency, which leads to a generalized modulated chaos.