bluuebunny/crossref_metadata_2025 huggingface dataset:
A Method for Determining the Asperity Distribution of Contacting Rough Surfaces
Authors: Jones Reese E. , Zeigler David A.
Published: February 2005

The Greenwood and Williamson (1966) model is an elegant and often-cited paradigm for predicting the load-displacement behavior of contacting rough surfaces given the height distribution of the contacting asperities. By use of an inverse technique and available load-displacement data, this work provides an alternative method to determine the asperity distribution directly from topographic measurement and subsequent data reduction. This method produces distributions that are consistent with the Greenwood and Williamson representation of the load-displacement data and demonstrates how the asperity height distribution can evolve with loading.
Analysis of Mixed Lubrication Effects in Simulated Gear Tooth Contacts
Authors: Holmes M. J. A. , Evans H. P. , Snidle R. W.
Published: February 2005

The paper presents results obtained using a transient analysis technique for point contact elastohydrodynamic lubrication (EHL) problems based on a formulation that couples the elastic and hydrodynamic equations. Results are presented for transverse ground surfaces in elliptical point contact that show severe film thinning and asperity contact at the transverse limits of the contact area. This thinning is caused by transverse leakage of the lubricant from the contact in the remaining deep valley features between the surfaces. A comparison is also made between the point contact results on the entrainment center line and the equivalent line contact analysis. The extent of asperity contact is shown to be dependent on the Hertzian contact aspect ratio. It is also shown that transverse waviness (superimposed on the roughness) of even relatively small amplitude can lead to large increases in asperity contact rates over all waviness peaks in the contact.
Probabilistic Designs of Air-Bearing Surface on Manufacturing Tolerances
Authors: Yoon Sang-Joon , Choi Dong-Hoon
Published: February 2005

The focus in this paper is to automatically design the air-bearing surface (ABS) considering the randomness of its geometry as an uncertainty of design variables. Designs determined by the conventional optimization could only provide a low level of confidence in practical products due to the existence of uncertainties in either engineering simulations or manufacturing processes. This calls for a reliability-based approach to the design optimization, which increases product or process quality by addressing randomness or stochastic properties of design problems. In this study, a probabilistic design problem is formulated considering the reliability analysis which is employed to estimate how the fabrication tolerances of individual slider parameters affect the final flying attitude tolerances. The proposed approach first solves the deterministic optimization problem. Beginning with this solution, the reliability-based design optimization (RBDO) is continued with the probabilistic constraints affected by the random variables. Probabilistic constraints overriding the constraints of the deterministic optimization attempt to drive the design to a reliability solution with a minimum increase in the objective. The simulation results of the probabilistic design are directly compared with the values of the initial design and the results of the deterministic optimum design, respectively. In order to show the effectiveness of the proposed approach, the reliability analyses by the Monte Carlo simulation are carried out. And the results demonstrate how efficient the proposed approach is, considering the enormous computation time of the reliability analysis.
Contact Mechanics Approach to Determine Effective Radius in Bolted Joints
Authors: Zou Q. , Sun T. S. , Nassar S. , Barber G. C. , El-Khiamy H. , Zhu D.
Published: February 2005

The effective radius is a very important factor in determining frictional torque under the bolt head and nut in bolted joints. Since the effective radius is hard to be precisely determined in practice, the mean radius, which is the mean value of the inner and outer radii of the contact area under the bolt head and nut, is used. In this paper, contact mechanics analysis is used to determine the real contact pressure distribution between the bolt head and nut and the joint surface. Based on the pressure distribution, the effective radius can be precisely calculated. The effect of the surface roughness, underhead load distribution, underhead load value, and the ratio of the maximum to minimum contact radii are investigated. The results are compared with the result from theoretical formulas and the value of mean radius. These data will be very useful in enhancing the reliability and safety of bolted joints.
A Gas-Surface Interaction Model for Spatial and Time-Dependent Friction Coefficient in Reciprocating Contacts: Applications to Near-Frictionless Carbon
Authors: Dickrell P. L. , Sawyer W. G. , Heimberg J. A. , Singer I. L. , Wahl K. J. , Erdemir A.
Published: February 2005

A closed-form time- and position-dependent model for coverage, based on the adsorption of environmental contaminants and their removal through the pin contact, is developed for reciprocating contacts. The model employs an adsorption fraction and removal ratio to formulate a series expression for the entering coverage at any cycle and location on the wear track. A closed-form solution to the series expression is presented and compared to other coverage models developed for steady-state coverage for pin-on-disk contacts, reciprocating contacts, or the time-dependent center-point model for reciprocating contacts. The friction coefficient is based on the average coverage under the pin contact. The model is compared to position- and time-dependent data collected on near-frictionless carbon self-mated contacts on a reciprocating tribometer in a nitrogen atmosphere. There are many similarities between the model curves and the data, both in magnitude and trends. No new curve fitting was performed in this paper, with all needed parameters coming from previous models of average friction coefficient behavior.
Effect of Low-Frequency Modulation on Lubrication of Chip-Tool Interface in Machining
Authors: Moscoso Wilfredo , Olgun Efe , Compton W. Dale , Chandrasekar Srinivasan
Published: February 2005

A study has been made of the effect of an externally imposed, low-frequency modulation ⩽100Hz on the action of a fluid in machining. It is shown that in conventional machining, fluid action in terms of lubrication is essentially confined to the edges of the chip-tool contact along the tool rake face, with little or no change in the friction condition over much of this face. However, the effectiveness of the lubricating action is significantly enhanced when a controlled low-frequency modulation of sufficient amplitude, such as to break the chip-tool contact, is imposed in the direction of cutting. Measurements show that the friction coefficient between tool and chip is reduced by a factor of up to three in the presence of such a modulation. The extent of the secondary deformation zone in the chip material close to the rake face is also significantly reduced. Direct observations of the tool rake face show that when the modulation is applied, the fluid penetrates into much of the intimate contact region between chip and tool.
Experimental Investigation of the Elastic–Plastic Contact Area and Static Friction of a Sphere on Flat
Authors: Etsion I. , Levinson O. , Halperin G. , Varenberg M.
Published: February 2005

An experimental investigation is presented to evaluate recently published models for the contact and sliding inception of a deformable sphere loaded against a smooth rigid flat. The effects of the normal load on the contact area, junction growth, and the static friction force in the elastic–plastic contact regime are presented. Very good correlation is found between the predicted and measured contact area. A dramatic decrease of the static friction coefficient with increasing normal loading is observed, similar to the trend predicted by the model. The quantitative agreement is, however, less satisfying. Some possible reasons for the poor agreement are pointed out.
Quantitative PCR-Enhanced Immunoassay for Measurement of Enteroviral Immunoglobulin M Antibody and Diagnosis of Aseptic Meningitis
Authors: Elfaitouri Amal , Mohamed Nahla , Fohlman Jan , Aspholm Robert , Frisk Gun , Friman Göran , Magnius Lars , Blomberg Jonas
Published: February 2005

A PCR-enhanced immunoassay (PIA) to detect enterovirus (EV) immunoglobulin M (IgM) for diagnosis of recent EV infection was recently developed. This test was compared with another EV IgM capture technique, the solid-phase reverse immunosorbent test (SPRIST). Fourteen of 43 serum samples from aseptic meningitis patients were positive by PIA, whereas 10 were positive by SPRIST. One of 39 control serum samples was weakly positive by PIA. A single-serum-dilution real-time PCR-based PIA for EV IgM (quantitative PIA [QPIA]) was also developed and evaluated against PIA, SPRIST, an EV IgM radioimmunoassay (RIA), and clinical data. A mixture of 12 EVs was used as the antigen. Results from investigating four groups of serum samples were as follows. (i) The nine PIA-positive serum samples in group 1 were all positive by QPIA. (ii) Group 2 consisted of 59 serum samples from aseptic meningitis patients. Nineteen of 30 serum samples (63%) taken at hospital admission were positive by QPIA. Of these, 17 were positive in EV PCR. (iii) None of the 30 control serum samples in group 3 were positive by QPIA. (iv) For the 24 serum samples in group 4, of which 11 were positive and 13 were negative by RIA, the QPIA results were completely concordant. The sensitivity and specificity of QPIA for diagnosis of EV infection were 70 and 80%, respectively. QPIA provides a rational strategy for the detection of EV IgM, allows the use of viral antigens with minimal purification, and needs no virus-specific reagents apart from those in the PCR. QPIA is a generally applicable method for the detection of viral IgM in IgM capture assays.
Development and Validation of an Enzyme-Linked Immunosorbent Assay for Human Metapneumovirus Serology Based on a Recombinant Viral Protein
Authors: Hamelin Marie-Ève , Boivin Guy
Published: February 2005

The human metapneumovirus (hMPV) is a newly reported respiratory virus belonging to the
Paramyxoviridae
family that has been associated with bronchiolitis and pneumonia in young children. We developed a simple enzyme-linked immunosorbent assay (ELISA) for hMPV serological testing using the nucleoprotein (N) from group A or B (N-A or N-B) as the antigen, and we evaluated it in both children and adults. The N proteins were first used in a Western immunoblot assay to identify hMPV-negative sera, which were then used to determine the cutoff value of the ELISA test. Subsequent evaluation of the ELISA-N test revealed that the mean reciprocal antibody titer of 20 randomly selected seropositive children was 143, compared to 69 for 20 seropositive adults. In a prospective evaluation of 71 adults with acute exacerbations of chronic obstructive pulmonary disease, 58 (81.6%) had prior hMPV antibodies and 3 (4.2%) had evidence of recent hMPV infection. In testing paired sera from adults (
n
= 4) with recent hMPV group A infection confirmed by reverse transcriptase PCR (RT-PCR), ELISAs using the N-A or N-B proteins were able to detect hMPV seroconversion. Moreover, testing of paired sera from three adults with a recent infection by the human respiratory syncytial virus confirmed by RT-PCR and serology did not reveal any increase in hMPV antibodies over time. The ELISA-N is a simple, objective, and specific serological test useful for detecting anti-hMPV antibodies following group A or B viral infections, which should permit a better understanding of the epidemiology of this virus.
Characterization of Heat Shock Protein-Specific T Cells in Atherosclerosis
Authors: Ford Pauline , Gemmell Erica , Walker Philip , West Malcolm , Cullinan Mary , Seymour Gregory
Published: February 2005

A role for infection and inflammation in atherogenesis is widely accepted. Arterial endothelium has been shown to express heat shock protein 60 (HSP60) and, since human (hHSP60) and bacterial (GroEL) HSP60s are highly conserved, the immune response to bacteria may result in cross-reactivity, leading to endothelial damage and thus contribute to the pathogenesis of atherosclerosis. In this study, GroEL-specific T-cell lines from peripheral blood and GroEL-, hHSP60-, andPorphyromonas gingivalis-specific T-cell lines from atherosclerotic plaques were established and characterized in terms of their cross-reactive proliferative responses, cytokine and chemokine profiles, and T-cell receptor (TCR) Vβ expression by flow cytometry. The cross-reactivity of several lines was demonstrated. The cytokine profiles of the artery T-cell lines specific for GroEL, hHSP60, andP. gingivalisdemonstrated Th2 phenotype predominance in the CD4 subset and Tc0 phenotype predominance in the CD8 subset. A higher proportion of CD4 cells were positive for interferon-inducible protein 10 and RANTES, with low percentages of cells positive for monocyte chemoattractant protein 1 and macrophage inflammatory protein 1α, whereas a high percentage of CD8 cells expressed all four chemokines. Finally, there was overexpression of the TCR Vβ5.2 family in all lines. These cytokine, chemokine, and Vβ profiles are similar to those demonstrated previously forP. gingivalis-specific lines established from periodontal disease patients. These results support the hypothesis that in some patients cross-reactivity of the immune response to bacterial HSPs, including those of periodontal pathogens, with arterial endothelial cells expressing hHSP60 may explain the apparent association between atherosclerosis and periodontal infection.
Evaluation of Recombinant Oocyst Protein CP41 for Detection of
Cryptosporidium-
Specific Antibodies
Authors: Kjos Sonia A. , Jenkins Mark , Okhuysen Pablo C. , Chappell Cynthia L.
Published: February 2005

Cryptosporidium
is an important cause of diarrhea in developed and developing countries, and its epidemiology is of interest. The methodologies used in the detection of
Cryptosporidium
-specific antibodies vary widely, which complicates comparison of results. This study assesses the performance of a
Cryptosporidium
recombinant protein (rCP41) in a serological assay compared to that of a crude antigen preparation. The 41-kDa protein from the oocyst wall was previously cloned and expressed in
Escherichia coli
. Sera from 192 healthy adults from the Texas Medical Center (Houston) were tested for anti-
Cryptosporidium
antibody reactivity using both crude and recombinant antigen preparations in an enzyme-linked immunosorbent assay. Immunoglobulin G reactivity was highly concordant (88%;
P
< 0.0001) between the two antigen preparations, with 110 positive (57%) and 59 negative (31%) by both tests. Regression analysis revealed a high correlation between the absorbance values generated with both antigen preparations and suggests that the rCP41 may be used in place of crude antigen. These results indicate that the use of the recombinant CP41 antigen in a standardized serodiagnostic assay could provide a reliable and cost-effective method for assessing human exposure to
Cryptosporidium
.
Detection of
Schistosoma mansoni
Membrane Antigens by Immunoblot Analysis of Sera of Patients from Low-Transmission Areas
Authors: Cesari Italo M. , Ballen Diana E. , Mendoza Leydi , Matos César
Published: February 2005

Schistosoma mansoni
surface membrane components play a relevant role in the host-parasite interaction, and some are released in vivo as circulating antigens.
n
-Butanol extraction favors the release of membrane antigens like alkaline phosphatase, which has been shown to be specifically recognized by antibodies from
S. mansoni
-infected humans and animals. In the present study, components in the
n
-butanol extract (BE) of the adult
S. mansoni
worm membrane fraction were separated by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1D SDS-PAGE [15%]) and further analyzed by immunoblotting (immunoglobulin G) using defined sera.
S. mansoni
-infected patient sera, but not sera of uninfected patients or sera obtained from patients infected with other parasite species, specifically and variably recognized up to 20 polypeptides in the molecular mass range of ∼8 to >80 kDa. There were some differences in the number, intensity, and frequency of recognition of the BE antigens among sera from Venezuelan sites of endemicity with a different status of schistosomiasis transmission. Antigens in the 28- to 24-kDa molecular mass range appeared as immunodominants and were recognized by
S. mansoni
-positive sera from all the sites, with recognition frequencies varying between 57.5 and 97.5%. Immunoblotting with BE membrane antigens resulted in a highly sensitive (98.1%), specific (96.1.0%), and confirmatory test for the immunodiagnosis of schistosomiasis in low-transmission areas.
Proteomic Approach for Characterization of Immunodominant Membrane-Associated 30- to 36-Kilodalton Fraction Antigens ofLeishmania infantumPromastigotes, Reacting with Sera from Mediterranean Visceral Leishmaniasis Patients
Authors: Kamoun-Essghaier Sayda , Guizani Ikram , Strub Jean Marc , Van Dorsselaer Alain , Mabrouk Kamel , Ouelhazi Lazhar , Dellagi Koussay
Published: February 2005

The aim of the present study was to identify and characterize proteins of a 30- to 36-kDa fraction ofLeishmania infantumpromastigote membranes previously shown to be an immunodominant antigen(s) in Mediterranean visceral leishmaniasis (MVL) and a consistent and reliable serological marker of this disease. By the first approach, Coomassie-stained protein bands (32- and 33-kDa fractions) that specifically reacted by immunoblotting with sera from MVL patients were excised from the gel and submitted to enzymatic digestion to generate peptides. Four peptides were sequenced, three of which were shown to be definitely associated with MVL-reactive antigens and ascribed to a mitochondrial integral ADP-ATP carrier protein fromL. major, a putative NADH cytochromeb5reductase, and a putative mitochondrial carrier protein, respectively. The second approach combined two-dimensional gel electrophoresis of membrane antigens and mass spectrometry (liquid chromatography-mass spectrometry/mass spectrometry) by using a quadrupole time-of-flight analysis. Six immunoreactive spots that resolved within a molecular mass range of 30 to 36 kDa and a pH range of 6.7 to 7.4 corresponded to fourLeishmaniaproducts. The sequences derived from two spots were ascribed to a beta subunit-like guanine nucleotide binding protein, known as the activated protein kinase C receptor homolog antigen LACK, and to a probable member of the aldehyde reductase family. One spot was identified as a probable ubiquinol-cytochromecreductase (EC 1.10.2.2) Rieske iron-sulfur protein precursor. The remaining three spots were identified as truncated forms of elongation factor 1α. These antigens correspond to conserved proteins ubiquitously expressed in eukaryotic cells and represent potential candidates for the design of a reliable tool for the diagnosis of this disease.
Mapping of B-Cell Epitopes in a
Trypanosoma cruzi
Immunodominant Antigen Expressed in Natural Infections
Authors: Lesénéchal Mylène , Becquart Laurence , Lacoux Xavier , Ladavière Laurent , Baida Renata C. P. , Paranhos-Baccalà Glaucia , da Silveira José Franco
Published: February 2005

Tc40 is an immunodominant antigen present in natural
Trypanosoma cruzi
infections. This immunogen was thoroughly mapped by using overlapping amino acid sequences identified by gene cloning and chemical peptide synthesis. To map continuous epitopes of the Tc40 antigen, an epitope expression library was constructed and screened with sera from human chagasic patients. A major, linear B-cell epitope spanning residues 403 to 426 (PAKAAAPPAA) was identified in the central domain of Tc40. A synthetic peptide spanning this region reacted strongly with 89.8% of the serum samples from
T. cruzi
-infected individuals. This indicates that the main antigenic site is defined by the linear sequence of the peptide rather than a conformation-dependent structure. The major B-cell epitope of Tc40 shares a high degree of sequence identity with
T. cruzi
ribosomal and RNA binding proteins, suggesting the existence of cross-reactivity among these molecules.
Long-Term Infection of Mongolian Gerbils withHelicobacter pylori:Microbiological, Histopathological, and Serological Analyses
Authors: Nakagawa Shigehito , Osaki Takako , Fujioka Yasunori , Yamaguchi Hiroyuki , Kamiya Shigeru
Published: February 2005

The effects of long-term infection withHelicobacter pylorion the gastric mucosa of Mongolian gerbils were examined. Colonization byH. pyloriwas evaluated by both microaerobic cultivation and real-time reverse transcriptase PCR (RT-PCR). Persistent infection withH. pyloriin gastric mucosa was detected by real-time RT-PCR during 6 months after infection, but noH. pyloriwas isolated 4 months after infection by cultivation. Infiltration with neutrophils and mononuclear cells was observed from 2 months after infection. Both intestinal metaplasia and gastric atrophy were also detected from 2 months after infection. The results by enzyme-linked immunosorbent assay indicated that antibody titers against wholeH. pyloriantigens,H. pyloriheat shock protein 60 (HSP60), andEscherichia coliGroEL were significantly higher in the infected gerbils than in noninfected gerbils. After long-term infection withH. pylorifor 18 months, marked atrophy of gastric mucosa and multiple cysts in the submucosa were observed in the glandular stomach of the infected gerbils. In addition, squamous cell papilloma with hyperkeratosis was observed in cardia of all the infected gerbils. These results indicate that evaluation of bacterial colonization during long-term infection can be done by real-time RT-PCR and that mucosal damage might be induced by host immune response against wholeH. pyloriantigen.
EFFECT OF ELEY–RIDEAL PROCESS ON THE PHASE DIAGRAM OF A MONOMER–DIMER CATALYTIC REACTION ON (001) SURFACE AND SUBSURFACE OF A SIMPLE CUBIC STRUCTURE
Authors: QAISRANI A. U. , KHAN K. M. , KHALID M.
Published: February 2005

We have investigated the effects of the Eley–Rideal (ER) process on the phase diagram of the Langmuir–Hinshelwood (LH) type monomer–dimer ( CO – O 2) catalytic reaction on (001) surface and subsurface of a simple cubic structure. With the consideration of a new pathway in which a dimer is adsorbed in such a way that it takes one surface site whereas second site may be from a surface or from a subsurface, a situation close to experiments is observed, i.e., with slight introduction of the monomer ( CO ), the production of AB2 starts. In this case, the qualitative trend of surface oxygen coverage is consistent with the experimental situation.
REINFORCEMENT LEARNING WITH GOAL-DIRECTED ELIGIBILITY TRACES
Authors: ANDRECUT M. , ALI M. K.
Published: February 2005

The eligibility trace is the most important mechanism used so far in reinforcement learning to handle delayed reward. Here, we introduce a new kind of eligibility trace, the goal-directed trace, and show that it results in more reliable learning than the conventional trace. In addition, we also propose a new efficient algorithm for solving the goal-directed reinforcement learning problem.
UNIVERSALITY OF THE THRESHOLD FOR COMPLETE CONSENSUS FOR THE OPINION DYNAMICS OF DEFFUANTet al.
Authors: FORTUNATO SANTO
Published: February 2005

In the compromise model of Deffuant et al., opinions are real numbers between 0 and 1, and two agents are compatible if the difference of their opinions is smaller than the confidence bound parameter ∊. The opinions of a randomly chosen pair of compatible agents get closer to each other. We provide strong numerical evidence that the threshold value of ∊ above which all agents share the same opinion in the final configuration is 1/2, independently of the underlying social topology.
PREDICTING BIOLOGICAL AGE FROM A SKIN SURFACE CAPACITIVE ANALYSIS
Authors: BEVILACQUA ALESSANDRO , GHERARDI ALESSANDRO , FERRI MASSIMO
Published: February 2005

The skin is the largest (and the most exposed) organ of the body both in terms of surface area and weight. Its care is of great importance for both aesthetics and health issues. Often, the skin appearance gives us information about the skin health status as well as hints at the biological age. Therefore, the skin surface characterization is of great significance for dermatologists as well as for cosmetic scientists in order to evaluate the effectiveness of medical or cosmetic treatments. So far, no in vivo measurements regarding skin topography characterization could be achieved routinely to evaluate skin aging. This work describes how a portable capacitive device, normally used for fingerprint acquisition, can be utilized to achieve measures of skin aging routinely. The capacitive images give a high resolution (50 μm) representation of skin topography, in terms of wrinkles and cells. In this work, we have addressed the latter: through image segmentation techniques, cells have been localized and identified and a feature related to their area distribution has been generated. Accurate experiments accomplished in vivo show how the feature we conceived is linearly related to skin aging. Besides, since this finding has been achieved using a low cost portable device, this could boost research in this field as well as open doors to an application based on an embedded system.
PERCOLATION AND FINITE SIZE SCALING IN SEVEN DIMENSIONS
Authors: ZEKRI LOTFI
Published: February 2005

Numerical investigation of critical exponents on a hypercubic lattice with Ld random sites with L up to 33 and d up to 7 showed that above the critical dimension the phase transitions in Ising model and percolation are not alike.
EFFECT OF MEAN ION SIZE AND SPATIAL SPIN DISORDERS FOR (La1-xYx)2/3Ca1/3MnO3 MANGANITES
Authors: ZHANG JINCANG , ZHANG YUFENG , CAO SHIXUN , JING CHAO
Published: February 2005

The structure and transport properties of perovskite ( La 1-x Y x)2/3 Ca 1/3 MnO 3 (0≤x≤0.3) systems are systematically investigated. It is found that all the specimens show a single-phase structure and reveal a direct relationship between the Curie temperature Tc and the average ionic radius  of La site. With increasing Y 3+ doped content, the metal-insulator transition temperature T MI (M-I) shifts to lower temperature. While the relevant resistivity peak ρp is sharp increased, for the specimens with large doping content, x=0.3, it has enhanced eight orders of magnitudes larger than the non-doped samples (x=0.0). At high concentration area, that is to say, when x>0.1, magnetic studies show a gradual increase of antiferromagnetic interaction with an increase of x, ultimately leading to a spatial-spin disorders, that is, spin-glass-like state for x=0.2 and x=0.3 compounds at about 35 K. The results show that it has connected a reduction of Tc and an increase in magnetoresistance with a decrease in the microstructural Mn - O - Mn bond angle.
SU(1,1) LIE ALGEBRA APPLIED TO THE TIME-DEPENDENT QUADRATIC HAMILTONIAN SYSTEM PERTURBED BY A SINGULARITY
Authors: CHOI JEONG RYEOL , CHOI SEONG SOO
Published: February 2005

We realized SU (1,1) Lie algebra in terms of the appropriate SU (1,1) generators for the time-dependent quadratic Hamiltonian system perturbed by a singularity. Exact quantum states of the system are investigated using SU (1,1) Lie algebra. Various expectation values in two kinds of the generalized SU (1,1) coherent states, that is, BG coherent states and Perelomov coherent states are derived. We applied our study to the CKOPS (Caldirola–Kanai oscillator perturbed by a singularity). Due to the damping constant γ, the probability density of the SU (1,1) coherent states for the CKOPS converged to the center with time. The time evolution of the probability density in SU (1,1) coherent states for the CKOPS are very similar to the classical trajectory.
VERTEX CORRECTIONS AND TIME-DEPENDENT GW APPROXIMATION
Authors: KARLSSON K.
Published: February 2005

In a many-body perturbation treatment of electronic excitations, one has to solve the so-called Bethe–Salpeter equation (BSE) for the kernel (vertex) describing the interaction between electrons. In general, the BSE exhibits a non-local and frequency-dependent screened interaction and consequently it is extremely difficult to solve. We have developed a scheme that solves the BSE equation iteratively, including dynamically screening, by considering the change in the electron self-energy upon applying a time-dependent field. The BSE is obtained from the self-energy in the GW approximation (GWA) using the Schwinger functional technique. We apply our formalism to a simple model system and discuss briefly changes in the charge response, when dynamical screening is taken into account.
IMPACT OF PRECURSOR SOURCE ON THE STRUCTURAL AND SUPERCONDUCTING PROPERTIES OF (Hg,Cr)Sr2CuO4+δ
Authors: BALAMURUGAN S. , SELVAM P.
Published: February 2005

We have investigated the structural/phase and superconducting properties of ( Hg , Cr )/ Sr -1201 [( Hg , Cr ) Sr 2 CuO 4+δ] samples prepared by two different precursor routes. It was observed that the quality of the ( Hg , Cr )/ Sr -1201 samples depends strongly on the precursor quality and the nature of starting materials. The ( Hg , Cr )/ Sr -1201 samples were synthesized in partial vacuum at 1153 K for 12 h, and characterized by power XRD, FT-IR, χ ac -T and dc-magnetization. A good quality ( Hg , Cr )/ Sr -1201 sample with higher superconducting transition temperature [Formula: see text] was obtained for the sample prepared from nitrate source as compared to that obtained from the sample prepared from the carbonate source [Formula: see text].
VORTICES IN BOSE–EINSTEIN CONDENSATES: SOME RECENT DEVELOPMENTS
Authors: KEVREKIDIS P. G. , CARRETERO-GONZÁLEZ R. , FRANTZESKAKIS D. J. , KEVREKIDIS I. G.
Published: February 2005

In this brief review we summarize a number of recent developments in the study of vortices in Bose–Einstein condensates, a topic of considerable theoretical and experimental interest in the past few years. We examine the generation of vortices by means of phase imprinting, as well as via dynamical instabilities. Their stability is subsequently examined in the presence of purely magnetic trapping, and in the combined presence of magnetic and optical trapping. We then study pairs of vortices and their interactions, illustrating a reduced description in terms of ordinary differential equations for the vortex centers. In the realm of two vortices we also consider the existence of stable dipole clusters for two-component condensates. Last but not least, we discuss mesoscopic patterns formed by vortices, the so-called vortex lattices and analyze some of their intriguing dynamical features. A number of interesting future directions are highlighted.
THE UPPER CRITICAL FIELD OF THIN FILMS OF TWO-BAND SUPERCONDUCTORS: AN APPLICATION TO MgB2
Authors: ASKERZADE I. N.
Published: February 2005

Temperature dependence of the upper critical field [Formula: see text] of thin films of two-band superconductors is studied using the two-band Ginzburg–Landau (G–L) theory. The results are shown to be in qualitative agreement with experimental data for the superconducting magnesium diboride MgB 2 films.
Viroids and Viroid-Host Interactions
Authors: Flores Ricardo , Hernández Carmen , Alba A. Emilio Martínez de , Daròs José-Antonio , Serio Francesco Di
Published: February 2005

Although they induce symptoms in plants similar to those accompanying virus infections, viroids have unique structural, functional, and evolutionary characteristics. They are composed of a small, nonprotein-coding, single-stranded, circular RNA, with autonomous replication. Viroid species are clustered into the families Pospiviroidae and Avsunviroidae, whose members replicate (and accumulate) in the nucleus and chloroplast, respectively. Viroids replicate in three steps through an RNA-based rolling-circle mechanism: synthesis of longer-than-unit strands catalyzed by host RNA polymerases; processing to unit-length, which in the family Avsunviroidae is mediated by hammerhead ribozymes; and circularization. Within the initially infected cells, viroid RNA must move to its replication organelle, with the resulting progeny then invading adjacent cells through plasmodesmata and reaching distal parts via the vasculature. To carry out these movements, viroids must interact with host factors. The mature viroid RNA could be the primary pathogenic effector or, alternatively, viroids could exert their pathogenic effects via RNA silencing.
Gender-related long-term effects in adult rats by perinatal dietary ratio of n-6/n-3 fatty acids
Authors: Korotkova Marina , Gabrielsson Britt G. , Holmäng Agneta , Larsson Britt-Marie , Hanson Lars Å. , Strandvik Birgitta
Published: February 2005

Epidemiological studies in humans have shown that perinatal nutrition affects health later in life. We have previously shown that the ratio of n-6 to n-3 polyunsaturated fatty acids (PUFA) in the maternal diet affects serum leptin levels and growth of the suckling pups. The aim of the present study was to investigate the long-term effects of various ratios of the dietary n-6 and n-3 PUFA during the perinatal period on serum leptin, insulin, and triacylglycerol, as well as body growth in the adult offspring. During late gestation and throughout lactation, rats were fed an isocaloric diet containing 7 wt% fat, either as linseed oil (n-3 diet), soybean oil (n-6/n-3 diet), or sunflower oil (n-6 diet). At 3 wk of age, the n-6/n-3 PUFA ratios in the serum phospholipids of the offspring were 2.5, 8.3, and 17.5, respectively. After weaning, all pups were given a standard chow. At the 28th postnatal wk, mean body weight and fasting insulin levels were significantly increased in the rats fed the n-6/n-3 diet perinatally compared with the other groups. The systolic blood pressure and serum triacylglycerol levels were only increased in adult male rats of the same group. These data suggest that the balance between n-6 and n-3 PUFA during perinatal development affects several metabolic parameters in adulthood, especially in the male animals.
Genetic Databases and Consent for Use of Medical Records
Authors: Gevers J.K.M.
Published: February 2005

The legislation on the Icelandic genetic database provides for an opting-out system for the collection of encoded medical information from individual medical records. From the beginning this has raised criticism, in Iceland itself and abroad. The Supreme Court has now decided that this approach of presumed consent is not unconstitutional per se, but that there are not sufficient safeguards to ensure that the information collected is not traceable to individuals. The decision of the court is of importance for the debate (at national and international level) on the legal and ethical aspects of population-based genetic databases. Furthermore, it is interesting because it recognizes the right of close relatives of a deceased person to oppose the collection and use of his or her medical data for genetic research, at least as long as these data may still be identifiable.
Of Biotechnology and Man
Authors: Knoppers Bartha Maria
Published: February 2005

Lessons learned from the arena of other genetic ‘resources’ (such as plants and animals) together with the past decade of experience in human genetic research requires a rethinking of policy approaches. Whether at the level of whole populations, the family or the individual, the determination of rights and responsibilities is necessarily situated in the context of relationships. From an appreciation of these relationships emerge ethical principles that reflect the complexity of both the human person and new technologies. The elaboration of principles such as individuality, mutuality, reciprocity, solidarity, equity, citizenry and universality foster the possibility that traditional human rights and bioethic principles can be interpreted in a new way so as to promote and protect human well-being.
Lay Understandings of Race: Cultural and Genetic Definitions
Authors: Dubriwny Tasha N. , Bates Benjamin R. , Bevan Jennifer L.
Published: February 2005

Objective: To examine lay understandings of race. Method: Fifteen focus groups were held in the southeastern United States from July to October of 2001. Results: The lay understanding of race is multifactorial, conceptualizing race as defined in part by genetics and in part by culture. Conclusions: The multifactorial understanding of race used by lay people is important to geneticists for two reasons. First, within the multifactorial definition of race, genetic variation is interpreted as phenotypic differences among individuals. Second, racial differences are apparent in understandings of race. African-American participants held a more fluid understanding of race that included ideas of self-definition and culture, while European-Americans were more likely to rely on physical characteristics to understand race.
Personal Characteristics of Older Primary Care Patients Who Provide a Buccal Swab for Apolipoprotein E Testing and Banking of Genetic Material: The Spectrum Study
Authors: Bogner Hillary R. , Wittink Marsha N. , Merz Jon F. , Straton Joseph B. , Cronholm Peter F. , Rabins Peter V. , Gallo Joseph J.
Published: February 2005

Objective: To determine the personal characteristics and reasons associated with providing a buccal swab for apolipoprotein E (APOE) genetic testing in a primary care study. Methods: The study sample consisted of 342 adults aged 65 years and older recruited from primary care settings. Results: In all, 88% of patients agreed to provide a DNA sample for APOE genotyping and 78% of persons providing a sample agreed to banking of the DNA. Persons aged 80 years and older and African-Americans were less likely to participate in APOE genotyping. Concern about confidentiality was the most common reason for not wanting to provide a DNA sample or to have DNA banked. Conclusion: We found stronger relationships between sociodemographic variables of age and ethnicity with participation in genetic testing than we did between level of educational attainment, gender, function, cognition, and affect.
The Use of Ultrasound Measurement of Fetal Lung Length to Predict Neonatal Respiratory Outcome after Prolonged Premature Rupture of the Membranes
Authors: Stone Peter , Grant Steven , Sadler Lynn , Battin Malcolm , Mitchell Jenny
Published: February 2005

Objective: The purpose of this study was to investigate the use of fetal lung length estimation by ultrasound in the prediction of adverse neonatal respiratory outcome after prolonged preterm rupture of the membranes. Methods: From the hospital database of all cases of spontaneous membrane rupture ≤28 weeks’ gestation, normal singleton pregnancies with membrane rupture for at least 7 days and delivery after 24 weeks’ gestation where lung length measurements were available were studied. The study period was 5 years. At least one lung length measurement ≧7 days after membrane rupture needed to be available and the last lung length prior to delivery was used to predict adverse respiratory outcome. Complete neonatal follow-up was available on all babies. Neonatal outcome measures included survival, bronchopulmonary dysplasia defined as an oxygen requirement at 36 weeks’ gestation, and neonatal respiratory death in non-survivors. Two groups, good and poor outcomes, were defined. A comparison of the last lung length before delivery (corrected for gestation) between the good and poor outcome groups was made to determine whether lung length could predict neonatal outcome. Results: There were 43 live births. All had received antenatal corticosteroids as part of the management of prematurity. There were no differences in maternal age, ethnicity, parity and the incidence of antepartum haemorrhage between the good and poor outcome groups. Parameters significantly associated with good outcome included gestation at membrane rupture, large pool of amniotic fluid and gestation at delivery. The last fetal lung length did not predict adverse neonatal respiratory outcome. In the 28 babies where membrane rupture was ≧21 days the findings were the same. Conclusion: Fetal lung length determined by antenatal ultrasound does not predict adverse neonatal respiratory outcome and the prediction of pulmonary hypoplasia in live borns after prolonged preterm rupture of the membranes remains an elusive goal.
Effects of Chronic Social Stress on Neuroendocrine Responsiveness to Challenge with Ethanol, Dexamethasone and Corticotropin-Releasing Hormone
Authors: Pohorecky Larissa A. , Baumann Michael H. , Benjamin Daniel
Published: February 2005

Neuroendocrine and behavioral profiles of group-housed rodents differ from those of singly-housed ones. Subordinate rats have elevated plasma corticosterone (CORT) concentration and impaired activity of the hypothalamic-pituitary-adrenal (HPA) axis compared to dominant cagemates. However, little is known about the effects of social hierarchy on other stress-related hormones. We examined plasma prolactin (PRL) and CORT responses to saline and ethanol (EtOH) injections, and 1 month later to dexamethasone (DEX) and corticotropin-releasing hormone (CRH) challenges of group- (triad) and single-housed male rats over a period of 225 days. Social status was determined from behaviors displayed upon initial triad housing. Subordinate rats had lower basal PRL and higher CORT compared to dominant rats. The injection of EtOH (1.25 g/kg) depressed PRL and elevated CORT levels significantly more than the saline injection only in dominant and singly-housed rats. DEX increased PRL levels, most strikingly in dominant rats, and suppressed CORT only in dominant rats. After CRH challenge, plasma CORT increased in all groups, subdominant and subordinate rats displaying blunted responses. Our data demonstrate that social rank and housing conditions affect plasma PRL and CORT concentrations, and modify responses to EtOH, possibly reflecting impairments of HPA axis regulation in socially-housed rats.
Herbal Extracts Modulate the Amplitude and Frequency of Slow Waves in Circular Smooth Muscle of Mouse Small Intestine
Authors: Storr M. , Sibaev A. , Weiser D. , Kelber O. , Schirra J. , Göke B. , Allescher H.D.
Published: February 2005

Background: Herbal preparations like STW 5 (Iberogast®) are widely used drugs in the treatment of dyspepsia and motility-related disorders of the gastrointestinal tract. STW 5 is a phytotherapeutic agent consisting of a fixed mixture of 9 individual plant extracts. The electrophysiological mechanisms of action of STW 5 remain obscure. Aim: The aim of the present study was to investigate whether herbal extracts influence electrophysiological parameters of the small intestine. For this purpose, the resting membrane potential (RMP) and the slow wave rhythmicity of smooth muscle cells of mouse small intestine were observed. Methods: Intracellular recordings of smooth muscle cells of the circular muscle layer of mouse small intestine were performed using standard microelectrode techniques. After dissection of the mucosa, the small intestine was placed in an organ bath and a microelectrode was applied on a circular smooth muscle cell. The RMP and the amplitude of slow waves were measured in millivolts. Results: The RMP of smooth muscle cells was –59 ± 1.3 mV. This RMP was significantly depolarized by STW 5 (9.6 ± 1.6 mV); the depolarizing effects can be mainly attributed to the constituents of matricariae flos, angelicae radix and chelidonii herba. The basal frequency of small intestinal slow waves was 39.5 ± 1.4 min–1 and the amplitude was 23.1 ± 0.9 mV. STW 5 significantly reduced the amplitude and frequency of the slow waves (11.7 ± 0.8 mV; 33.5 ± 3.4 min–1). This effect on slow waves represents the sum of the effects of the 9 phytoextracts. Whereas angelicae radix and matricariae flos completely blocked slow wave activity, Iberis amara increased the frequency and amplitude, chelidonii herba reduced the frequency and amplitude of the slow waves, mentae piperitae folium reduced the frequency and left amplitude unchanged and liquiritae radix, carvi fructus and melissae folium had no effects. Conclusion: Herbal extracts cause changes in smooth muscle RMP and slow wave rhythmicity, up to reversible abolition, by blockade of large conductance Ca2+ channels and other not yet identified mechanisms. In herbal preparations like STW 5 these effects add up to a total effect and this study indicates that herbal preparations which are widely used in dyspepsia and motility-related disorders have characteristic, reproducible, reversible effects on small intestinal electrophysiology.
Analysis of the Golden Syrian Hamster Anterior Pituitary Gland Proteome by Ion Trap Mass Spectrometry
Authors: Blake Charles A. , Kakhniashvili David G. , Goodman Steven R.
Published: February 2005

We utilized mass spectrometry (MS) and bioinformatics to investigate the proteome of the anterior pituitary gland (AP). Subcellular fractions of APs from 2-month-old male Golden Syrian hamsters were prepared for protein denaturation, treatment with trypsin and analyses utilizing micro liquid chromatography MS/MS and the database search software SEQUEST. In the nuclear, non-nuclear 100,000 × g and cytosolic fractions we identified 76, 52 and 52 different proteins, respectively. A total of 145 distinct proteins were detected. We identified growth hormone, prolactin, pro-opiomelanocortin, the α-subunit for the glycoprotein hormones, luteinizing hormone-β and follicle-stimulating hormone-β. Groups of other identified proteins included hormone processing, secretion granule associated, non-hormonal endoplasmic reticulum associated, calcium binding, protein kinase C associated histone and non-histone chromosomal material, other RNA-binding, splicing factors, heterogeneous nuclear ribonucleoproteins, helicases, lamins, microfilament associated, microtubule associated, adenosine triphosphate and guanosine diphosphate associated, keratins, lysosomal, ribosomal, enzymes in glycolysis and the tricarboxylic and pentose phosphate paths, glutathione associated, transmethylation, catabolic and unknown protein products as well as blood hemoglobins. Proteins previously not reported in the AP, such as fertility protein SP22, were identified. The proteins identified in the present study form a foundation for defining the proteome in normal adult male AP.