bluuebunny/crossref_metadata_2025 huggingface dataset:
Speaking Out
Authors: Stevens Sharon McKenzie
Published: December 2007

Bijker calls for scholars in science and technology studies (STS) to become public intellectuals by actively working toward “democratizing . . . technological culture.” Many STS scholars have developed practices that support democratic and public activity; yet, these typically require individual commitment with inadequate institutional support. The public work of STS scholars can be better supported through a program that includes (1) using specialist research in nonreproductive educational contexts, (2) redefining and revaluing academic service, (3) developing more accessible ways of writing, and (4) publishing and valuing STS-based texts that circulate among nonacademic audiences.
“You've Got it, You May Have it, You Haven't Got it”
Authors: Corbett Kevin P.
Published: December 2007

This article considers the experiences of health consumers who have undergone testing for human immunodeficiency virus (HIV) antibodies, T cells, and viral load. These HIV-related tests are deployed for the purposes of making definitive diagnoses; yet some test consumers experience ambiguous outcomes. Drawing on an analysis of differing end-user experiences of these tests, where consumers' knowledge reflected the multiplicity and heterogeneity in test design, the author explores how these experiences reflect particular knowledges about these tests. The article contributes to efforts analyzing how health consumers are active end users co-constructing the social meaning of technologies in mutual relationship with other users. The author discusses how this new knowledge can be used to delineate a greater role for consumer evaluation of medical testing within a broader understanding of test design and performance. Relevant links are made to issues such as genetic testing and assessing claims about the efficacy of medical tests.
New Polysaccharide-based Microparticles Crosslinked with Siloxane: Interactions with Biologically Active Substances
Authors: Mocanu Georgeta , Mihai Doina , Legros Mélanie , Picton Luc , Lecerf Didier
Published: December 2007

The interaction of microparticles of carboxymethyl pullulan crosslinked with siloxane (provided by a new crosslinking agent: 3-(glycid oxypropyl) trimethoxysilane) with biologically active molecules, such as enzymes (lysozyme) and drugs (propranolol, quinidine) was studied. The anionic amphiphilic supports retained through electrostatic and/or hydrophobic forces, variable amounts of the substances as a function of their structure, such as crosslinking degree and amount of uncrosslinked alkylsilane chains. The absorption of lysozyme on the supports followed the Langmuir isotherm, which allowed the calculation of constants k1 and k2. Both retention and in vitro release behavior of these support potential applications in controlled drug release as well as immobilization and purification of enzymes.
Anti C-Reactive Protein Immobilization Onto Poly(glycidyl Methacrylate) Microspheres and its Use for Diagnosis
Authors: Ozan E. , Ayhan F. , Ayhan H.
Published: December 2007

A method for a polymeric carrier based test was developed for the diagnosis of C-reactive protein (CRP) as an alternative to commercial kits. Poly(glycidyl methacrylate) (PGMA) particles were synthesized by dispersion polymerization method from the glycidyl methacrylate (GMA) monomer. The monomer transformation value was 88.67% by weight. In the first step the epoxide rings were opened to form amine groups on the particle surfaces. The optimized conditions were found for the antigen to be immobilized onto the surface-modified microspheres. Agglutination tests were carried out under in vitro conditions with the anti-human CRP immobilized microspheres with samples from patient serum. Relatively high sensitivity was obtained with a short reaction time between doing the test after receiving patient serum compared with the selected commercial kit now in use. By referring to the agglutination intensity scores, using only 10 mg/L samples of plasma, the CRP concentration was detectable with these new kits.
Modeling the Behavior of Polymer-layered Silicate Nanocomposites using Factorial and Mixture Designs
Authors: Mittal V.
Published: December 2007

The behavior of polymer-layered silicate nanocomposites is modeled through various factorial and mixtures design methodologies in order to optimize the composite performance and to accurately predict the properties especially for the nonpolar polymer systems. The various factors studied for the factorial design are volume fraction of inorganic clay, cation exchange capacity of the montmorillonite (MMT) substrate, and number of octadecyl chains in the ammonium modification ion exchanged on the clay surface. The constrained mixtures design includes the components as weight percent of polymer matrix, organic modification, and inorganic filler as compared to the total weight of the mixture. The mixtures design for compatibilized nanocomposites is also studied by using the components weight percent of polymer, organically modified clay, and the compatibilizer. The predicted properties from these models narrowly match the experimental results indicating the efficiency of the models to correctly represent the polymer nanocomposites system. The model equations are also used to generate response surfaces to help to achieve the required combinations of the factors or components of the system to obtain optimum composite properties. Unlike conventional models which depend on oversimplified assumptions, which are not applicable in reality, these models do not suffer from these limitations and can still predict the composite properties using a set of simple equations.
Effect of Independent Variables on Mechanical Properties and Maximization of Aspen—Polypropylene Composites
Authors: Ruijun Gu  , Kokta Bohuslav V.
Published: December 2007

Study on the effect of concentration of maleated polypropylene (MAPP), dicumyl peroxide (DCP), nanoclay (NC), and aspen fiber loading on the mechanical properties of Aspen—PP composites has been undertaken with the objective to protect or increase the impact strength without losing or weakening the tensile strength. The central composite design of Statgraphic plus is used to determine the optimum concentration of additives and to maximize both the impact as well as tensile strength properties to be superior to that of pure PP. Finally, the material price of PP composites with an optimal composition of filler (aspen fiber and NC), coupling agent (MAPP), and initiator (DCP) is compared to that of pure PP and PP reinforced with glass fibers.
Telling the Truth: Turkish Patients' and Nurses' Views
Authors: Demirsoy Nilüfer , Elcioglu Omur , Yildiz Zeki
Published: December 2007

The objective of this study was to investigate nurses' communications with patients, particularly regarding getting accurate and truthful information about their medical diagnosis and prognosis. This survey research involved 166 nurses and 435 patients at the Osmangazi University Hospital, Turkey. Although 90% of the nurses said that patients should be informed about their diagnosis, only 66% of the patients said they wanted to be told this information. For those who wanted to be informed, how they should be informed is also discussed.
Practicing Women's Health with a Simultaneity Worldview in a Medical Model World
Authors: Kostas-Polston Elizabeth A.
Published: December 2007

Practicing from a human becoming perspective is challenging and rewarding for the nurse clinician. In this column, the author discusses the challenges faced when working as a women's health nurse practitioner, with a simultaneity worldview, in a medical model world.
Control System Design for Flexible Rotors Supported by Actively Lubricated Bearings
Authors: Nicoletti R. , Santos I.F.
Published: December 2007

This article presents a methodology for calculating the gains of an output feedback controller for active vibration control of flexible rotors. The methodology is based on modal reduction. The proportional and derivative gains are obtained by adjusting the first two damping factors of the system and keeping the lengths of the two eigenvalues constant in the real-imaginary plane. The methodology is applied to an industrial gas compressor supported by active tilting-pad journal bearings. The unbalance response functions and mode shapes of the flexible rotor with and without active control are presented, showing significative improvement in damping reserve with the control. The importance of sensor location is emphasized, on the basis of the energy necessary to operate the active system over the entire frequency range studied. The best results are obtained by a decentralized controller, observing displacement and velocity of the shaft at the bearing positions.
Performance of Simple and Sophisticated Control in Energy-recycling Semi-active Vibration Suppression
Authors: Onoda Junjiro , Makihara Kanjuro
Published: December 2007

The semi-active energy-recycling methods studied in this article suppress vibration by controlling switches in inductive shunt circuits connected to piezoelectric transducers in vibrating structures. This article compares the performances of simple and sophisticated methods that can be used for multiple-mode vibration. Although it should be obvious that the performance of the latter is superior, we need to know whether the superior performance of the sophisticated method justifies the expense incurred by its complexity. The performance comparisons were done by numerically simulating the vibration suppression of a truss structure with a piezoelectric transducer. We simulated transient free vibrations, forced sinusoidal vibrations, and forced random vibrations. In all cases, both methods were shown to be effective for the first and second modes of vibration. The ways and situations in which the sophisticated method is superior to the simple method were also elucidated. A vibration suppression experiment using a truss was also carried out and demonstrated that the sophisticated method worked well under random excitation.
The Relationship Between Medical Practice Characteristics and Quality of Care for Cardiovascular Disease
Authors: Landon Bruce E. , Normand Sharon Lise T. , Meara Ellen , Qi Zhou  , Simon Steven R. , Frank Richard , McNeil Barbara J.
Published: December 2007

The settings in which health care services are delivered have the potential to influence the quality of health care services in numerous ways, but little is known about the relationship between characteristics of medical practices and quality of care. In this study, the authors studied patients with coronary heart disease (CHD). The authors surveyed 225 medical practices in 2000 and 2001 and obtained information on quality measures from the medical records for more than 1,600 of their patients with CHD. Results suggest that quality of care, at least for common conditions with agreed-on measures, is not strongly influenced by financial characteristics of medical practices, although there does seem to be some relationship with practice structure such as size and quality.
Numerical Study of Fractured Sandwich Composites under Flexural Loading
Authors: Theotokoglou E.E. , Hortis D. , Carlsson L.A. , Mahfuz H.
Published: December 2007

Fatigue crack growth of foam core sandwich beams loaded in flexure has been investigated numerically. Extensive fatigue data from foam core sandwich composites under flexural loading were analyzed. A static finite element analysis is adopted for the uncracked sandwich beam in order to predict crack initiation positions. A face/core debond parallel to the beam axis is considered in accordance with experimental data. A static two-dimensional finite element analysis of the cracked sandwich beam is accounted for the evaluation of stress intensity factors at the crack tips investigating the crack growth behavior. In this way it is succeeded in making a significant contribution to understand the initiation and propagation of a fatigue crack in the foam core of sandwich beams loaded by flexural loading.
Sliding friction wear of hydrogenated pure copper
Authors: Duheisat S. , Al-Rawashdeh S. , El-Amoush A. S.
Published: December 2007

The effect of cathodically charged hydrogen on the wear characteristics of pure copper has been investigated using pin on disc wear tests. Sliding distance and applied normal load were taken as wear test variables, while sliding velocity was kept constant. The tests revealed that cathodic hydrogen charging resulted in a reduction of the coefficient of sliding friction of copper. The coefficient of sliding friction was found to decrease with increasing charging time. Most of the wear debris of the hydrogen charged copper had a particle like shape and presented features of brittle fracture, whereas the wear debris of the uncharged copper was indicative of mechanical shearing and plastic deformation. The amount of copper wear debris was found to be a uniform function of charging time. A long time of charging produced more wear debris. The wear track of the hydrogen charged copper showed discontinuous smearing of copper and oxide particles, whereas the uncharged copper showed very smooth and uniform smearing of copper and oxide particles. Microcracks were observed in the wear tracks of the charged copper. Cathodic hydrogen charging was found to cause hardening in copper and the severity of hardening increased with increasing time.
Effect of La2O3 on microstructure and sliding wear properties of TiC4 ceramic coating produced by electrical discharge method
Authors: Cheng X.-Y. , Shi L.
Published: December 2007

The method of electrical discharge coating with TiC4 ceramic layer in an ordinary electrical discharge machining (EDM) tool was studied. TiC4 ceramic layer was deposited on No. 45 carbon steel substrate by EDM technique. TiC4 ceramic coatings with different contents of lanthanum oxide were fabricated on No. 45 carbon steel substrate. The microstructures of the clad coatings were examined and tested for chemical composition, phase structure, friction and wear properties. Scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, hardness testing, block on ring friction and wear testing were carried out separately. Experimental results show that TiC4 ceramic coating can be deposited on a substrate of carbon steel, and the electrode doped with rare earth lanthanum oxide helps to refine coating's microstructure and enhance the coating's density. When the content of lanthanum oxide is increased to 0˙5%, the clad coating shows the best antiwear ability, wear resistance can be increased by three times and the friction coefficient can be decreased by 10%. If the content of lanthanum oxide exceeds that proportion, the coating's wear resistance decreases significantly.
Finite element model for unified EB–PVD machine dynamics
Authors: Baek S. , Prabhu V.
Published: December 2007

The present paper presents finite element models to describe machine dynamics, such as electron beam (EB) generation in an EB gun, EB scanning on the surface of an ingot, melting process of the ingot, and vaporisation and deposition on the surface of a substrate during EB–PVD process. Based on physical models, the finite element models relate the input power to the EB gun and the temperature profile of the ingot surface, the temperature profile to the shape of vapour plume, and the vapour distribution to the coating thickness. The two deposition process models have been investigated for predicting the coating thickness and compared to experiments performed for simple shaped substrates. With preliminary studies, it is found that the presented models are suitable for a cost efficient computation and can aid in assessing process parameters.
Effects of equal channel angular extrusion and subsequent heat treatment on tribological properties of TiNi alloy
Authors: Li Z. H. , Cheng X. H.
Published: December 2007

The friction and wear properties of TiNi alloy processed by equal channel angular extrusion (ECAE) and subsequent heat treatment processing under dry sliding condition were evaluated on a block on ring M-2000 tribometer. The effects of ECAE and heat treatment on the tribological properties of TiNi alloy were investigated. The worn surface morphologies of TiNi alloy were examined by scanning electron microscopy (SEM) and the wear mechanisms were discussed. The results showed that ECAE and heat treatment contributed to improve the friction and wear behaviours of TiNi alloy remarkably. The friction coefficient and wear loss of TiNi alloy decreased after ECAE and heat treatment. The maximum wear reduction was obtained when the heat treatment temperature after ECAE was 773 K. Adhesion wear and delamination were notable for the initial TiNi alloy. The material delamination was greatly abated when the heat treatment temperature of TiNi alloy processed by ECAE was 773 K.
Fabrication of functionally graded 3A/5A zeolites by electrophoretic deposition
Authors: Wang X. , Olevsky E. A. , Bruce E. , Stern M. B. , Hayhurst D. T.
Published: December 2007

Functionally graded zeolites of molecular sieve type 3A and 5A are deposited by electrophoretic deposition (EPD) from acetone suspension with 8% volume concentration of n-butylamine as particle charging agent. The EPD characteristics of both 3A and 5A suspensions are studied. Functionally graded zeolite 3A/5A deposits are obtained at 200 V DC. Energy dispersive X-ray dispersion (EDX) analysis results confirm the graded structure. The deposited zeolites are also analysed by scanning electron microscopy (SEM). The factors influencing the deposition process are discussed.
Fundamental and practical evaluation of plasma electrolytic oxidation coatings of titanium
Authors: Matykina E. , Skeldon P. , Thompson G. E.
Published: December 2007

Plasma electrolytic oxidation (PEO) is a unique coating technology, which enables fabrication of high performance ceramic surfaces on the light metals, with thickness, topography, composition and structure controllable by the process parameters. Here the growth of anodic coatings on titanium, important due to their biocompatibility and potential use in dental and orthopaedic implants, is investigated at a fundamental level. The work has achieved major impact in understanding coating growth from original tracer studies. For the first time discrete thickening at sites of dielectric breakdown, local growth at the metal/oxide interface and destruction of earlier formed oxide were shown, which offered a new perspective on coating processes, including those aspects affecting coating efficiency – a critical feature in a relatively high cost technology. Furthermore, based on the fundamental findings, routes to tailored coating compositions for enhanced biocompatibility have been developed, and carried through to in vitro evaluation. Fabrication of amorphous oxide, which is beneficial to biocompatibility, was achieved through anodising at controlled current densities and with use of complexing agents. These promote uniform coating composition, with major increase in both the electrolyte element content in the coating and the coating pore size. Corrosion tests of the coatings revealed low titanium release into physiological solution, which is important to avoid adverse tissue reaction. In vitro tests confirmed good attachment of human osteoblast cells to the fabricated titanium oxide coatings, expressed as a well spread cell morphology with cytoplasmic projection development. The work is proceeding with a focus on optimising coatings for in vivo implant trials.
Study on residual stress of laser shock processing based on numerical simulation and orthogonal experimental design
Authors: Hu Y. X. , Yao Z. Q. , Wang F. , Hu J.
Published: December 2007

Laser shock processing (LSP) is a competitive alternative surface enhancement process. Shock pressure with high magnitude and short duration induced by LSP is one key parameter to induce a residual stress field in the material. Finite element method (FEM) simulation based on the orthogonal experimental design is adopted to analyse the interaction of different shock pressure profiles with the material. It can give a relatively accurate description of the effect of shock pressure profile on the residual stress field induced in the material with a representative coverage of all parameters by less calculation cost. The analysis results show that laser shock conditions should be selected carefully to ensure a favourable shock pressure to obtain an optimised residual stress field. The simulation on the overlapping laser shock is also presented and indicates that it is an effective method to settle the residual stress drop on the top surface and can obtain a much more favourable residual compressive stress field to enhance the fatigue resistance of the material.
Investigation of hydroabrasive erosion of laser alloyed nickel and titanium based intermetallic matrix composites with TiC reinforcement
Authors: Duraiselvam M. , Galun R. , Siegmann S. , Wesling V. , Mordike B. L.
Published: December 2007

B2–NiTi and Ti3Al based single and dual phase intermetallic matrix composites (IMC) with TiC reinforcement were laser alloyed using Ni/Al–VC, Al–VC and Al–Cr3C2 powder mixtures. A sufficient amount of Ti from the substrate reacted with the injected alloy powder mixture to form Ti based intermetallics and TiC. The coatings were characterised by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD) and energy dispersive spectroscopy (EDS). The erosion resistance of the alloyed layers was characterised by high speed particle laden liquid impact erosion tests. The high work hardening ability of Ti3Al IMC strengthened by TiC reinforcement improved the erosion resistance up to a factor of 1˙39. Compared to the single phase IMC, the dual phase IMC coatings were found not to be suitable for applications similar to the present test conditions due to possibly preferential removal of secondary precipitates. An attempt has been made to identify the influence of different depth sensing indentation (DSI) derived mechanical properties to the erosion resistance of the alloyed layers. The correlation indicates the combined contribution of hardness, strain hardening exponent, surface elasticity and yield strength on improving the erosion resistance.
Impact of cytogenetics on the outcome of adult acute lymphoblastic leukemia: results of Southwest Oncology Group 9400 study
Authors: Pullarkat Vinod , Slovak Marilyn L. , Kopecky Kenneth J. , Forman Stephen J. , Appelbaum Frederick R.
Published: December 2007

We examined the prognostic impact of cytogenetics on the outcome of 200 acute lymphoblastic leukemia (ALL) patients 15 to 65 years of age enrolled in Southwest Oncology Group (SWOG)–9400 study. Evaluable cytogenetics or fluorescence in situ hybridization studies were available in 140 (70%) patients. Four karyotype categories (normal [n = 31, 22%], t(9;22)/BCR/ABL1 [n = 36, 26%], other unfavorable [−7, +8, or 11q23 rearrangement, n = 19, 13%], and miscellaneous [n = 54, 39%]) and the biologically and clinically relevant ALL ploidy subgroups were prospectively defined. Overall survival (OS) decreased significantly with increasing age (P = .009) and varied with karyotype category (P < .001). OS was worst for t(9;22)/BCR/ABL1 followed by other unfavorable karyotypes, with hazard ratios (HR) of 3.45 (95% confidence interval [CI], 1.88-6.31) and 2.14 (95% CI, 1.04-4.04), respectively, compared with normal diploid group. OS of the miscellaneous group was similar to that of the normal diploid group (HR = 0.82; 95% CI, 0.44-1.53). Relapse-free survival (RFS) was not significantly associated with age (P = .30) but was heterogeneous among karyotype categories (P < .001) primarily because of poor RFS in t(9;22)/BCR/ABL1 (HR = 3.49; 95% CI, 1.80-6.75) compared with the normal diploid group. After accounting for the variation among karyotype groups, age was not a significant prognostic factor for OS or RFS, highlighting cytogenetics as the most important prognostic factor in adult ALL. This trial was registered at www.ClinicalTrials.gov as #NCT00002665.
Analyzing in situ gene expression in the mouse brain with image registration, feature extraction and block clustering
Authors: Jagalur Manjunatha , Pal Chris , Learned-Miller Erik , Zoeller R Thomas , Kulp David
Published: December 2007

Background

Many important high throughput projects usein situhybridization and may require the analysis of images of spatial cross sections of organisms taken with cellular level resolution. Projects creating gene expression atlases at unprecedented scales for the embryonic fruit fly as well as the embryonic and adult mouse already involve the analysis of hundreds of thousands of high resolution experimental images mapping mRNA expression patterns. Challenges include accurate registration of highly deformed tissues, associating cells with known anatomical regions, and identifying groups of genes whose expression is coordinately regulated with respect to both concentration and spatial location. Solutions to these and other challenges will lead to a richer understanding of the complex system aspects of gene regulation in heterogeneous tissue.

Results

We present an end-to-end approach for processing rawin situexpression imagery and performing subsequent analysis. We use a non-linear, information theoretic based image registration technique specifically adapted for mapping expression images to anatomical annotations and a method for extracting expression information within an anatomical region. Our method consists of coarse registration, fine registration, and expression feature extraction steps. From this we obtain a matrix for expression characteristics with rows corresponding to genes and columns corresponding to anatomical sub-structures. We perform matrix block cluster analysis using a novel row-column mixture model and we relate clustered patterns to Gene Ontology (GO) annotations.

Conclusion

Resulting registrations suggest that our method is robust over intensity levels and shape variations in ISH imagery. Functional enrichment studies from both simple analysis and block clustering indicate that gene relationships consistent with biological knowledge of neuronal gene functions can be extracted from large ISH image databases such as the Allen Brain Atlas [1] and the Max-Planck Institute [2] using our method. While we focus here on imagery and experiments of the mouse brain our approach should be applicable to a variety ofin situexperiments.
Mitochondrial DNA heteroplasmy in ovine fetuses and sheep cloned by somatic cell nuclear transfer
Authors: Burgstaller Jörg P , Schinogl Pamela , Dinnyes Andras , Müller Mathias , Steinborn Ralf
Published: December 2007

Background

The mitochondrial DNA (mtDNA) of the cloned sheep "Dolly" and nine other ovine clones produced by somatic cell nuclear transfer (SCNT) was reported to consist only of recipient oocyte mtDNA without any detectable mtDNA contribution from the nucleus donor cell. In cattle, mouse and pig several or most of the clones showed transmission of nuclear donor mtDNA resulting in mitochondrial heteroplasmy. To clarify the discrepant transmission pattern of donor mtDNA in sheep clones we analysed the mtDNA composition of seven fetuses and five lambs cloned from fetal fibroblasts.

Results

The three fetal fibroblast donor cells used for SCNT harboured low mtDNA copy numbers per cell (A: 753 ± 54, B: 292 ± 33 and C: 561 ± 88). The ratio of donor to recipient oocyte mtDNAs was determined using a quantitative amplification refractory mutation system (ARMS) PCR (i.e. ARMS-qPCR). For quantification of SNP variants with frequencies below 0.1% we developed a restriction endonuclease-mediated selective quantitative PCR (REMS-qPCR). We report the first cases (n = 4 fetuses, n = 3 lambs) of recipient oocyte/nuclear donor mtDNA heteroplasmy in SCNT-derived ovine clones demonstrating that there is no species-effect hindering ovine nucleus-donor mtDNA from being transmitted to the somatic clonal offspring. Most of the heteroplasmic clones exhibited low-level heteroplasmy (0.1% to 0.9%, n = 6) indicating neutral transmission of parental mtDNAs. High-level heteroplasmy (6.8% to 46.5%) was observed in one case. This clone possessed a divergent recipient oocyte-derived mtDNA genotype with three rare amino acid changes compared to the donor including one substitution at an evolutionary conserved site.

Conclusion

Our study using state-of-the-art techniques for mtDNA quantification, like ARMS-qPCR and the novel REMS-qPCR, documents for the first time the transmission of donor mtDNA into somatic sheep clones. MtDNA heteroplasmy was detected in seven of 12 clones tested, whereby all but one case revealed less than 1% mtDNA contribution from the nuclear donor cell suggesting neutral segregation.
Comparative genomic characterization of citrus-associated Xylella fastidiosa strains
Authors: da Silva Vivian S , Shida Cláudio S , Rodrigues Fabiana B , Ribeiro Diógenes CD , de Souza Alessandra A , Coletta-Filho Helvécio D , Machado Marcos A , Nunes Luiz R , de Oliveira Regina Costa
Published: December 2007

Background

The xylem-inhabiting bacterium Xylella fastidiosa (Xf) is the causal agent of Pierce's disease (PD) in vineyards and citrus variegated chlorosis (CVC) in orange trees. Both of these economically-devastating diseases are caused by distinct strains of this complex group of microorganisms, which has motivated researchers to conduct extensive genomic sequencing projects with Xf strains. This sequence information, along with other molecular tools, have been used to estimate the evolutionary history of the group and provide clues to understand the capacity of Xf to infect different hosts, causing a variety of symptoms. Nonetheless, although significant amounts of information have been generated from Xf strains, a large proportion of these efforts has concentrated on the study of North American strains, limiting our understanding about the genomic composition of South American strains – which is particularly important for CVC-associated strains.

Results

This paper describes the first genome-wide comparison among South American Xf strains, involving 6 distinct citrus-associated bacteria. Comparative analyses performed through a microarray-based approach allowed identification and characterization of large mobile genetic elements that seem to be exclusive to South American strains. Moreover, a large-scale sequencing effort, based on Suppressive Subtraction Hybridization (SSH), identified 290 new ORFs, distributed in 135 Groups of Orthologous Elements, throughout the genomes of these bacteria.

Conclusion

Results from microarray-based comparisons provide further evidence concerning activity of horizontally transferred elements, reinforcing their importance as major mediators in the evolution of Xf. Moreover, the microarray-based genomic profiles showed similarity between Xf strains 9a5c and Fb7, which is unexpected, given the geographical and chronological differences associated with the isolation of these microorganisms. The newly identified ORFs, obtained by SSH, represent an approximately 10% increase in our current knowledge of the South American Xf gene pool and include new putative virulence factors, as well as novel potential markers for strain identification. Surprisingly, this list of novel elements include sequences previously believed to be unique to North American strains, pointing to the necessity of revising the list of specific markers that may be used for identification of distinct Xf strains.
Simulating non-small cell lung cancer with a multiscale agent-based model
Authors: Wang Zhihui , Zhang Le , Sagotsky Jonathan , Deisboeck Thomas S
Published: December 2007

Background

The epidermal growth factor receptor (EGFR) is frequently overexpressed in many cancers, including non-small cell lung cancer (NSCLC). In silico modeling is considered to be an increasingly promising tool to add useful insights into the dynamics of the EGFR signal transduction pathway. However, most of the previous modeling work focused on the molecular or the cellular level only, neglecting the crucial feedback between these scales as well as the interaction with the heterogeneous biochemical microenvironment.

Results

We developed a multiscale model for investigating expansion dynamics of NSCLC within a two-dimensional in silico microenvironment. At the molecular level, a specific EGFR-ERK intracellular signal transduction pathway was implemented. Dynamical alterations of these molecules were used to trigger phenotypic changes at the cellular level. Examining the relationship between extrinsic ligand concentrations, intrinsic molecular profiles and microscopic patterns, the results confirmed that increasing the amount of available growth factor leads to a spatially more aggressive cancer system. Moreover, for the cell closest to nutrient abundance, a phase-transition emerges where a minimal increase in extrinsic ligand abolishes the proliferative phenotype altogether.

Conclusion

Our in silico results indicate that in NSCLC, in the presence of a strong extrinsic chemotactic stimulus (and depending on the cell's location) downstream EGFR-ERK signaling may be processed more efficiently, thereby yielding a migration-dominant cell phenotype and overall, an accelerated spatio-temporal expansion rate.
Neuronal Activity Related to Anticipated Reward in Frontal Cortex
Authors: ROESCH MATTHEW R. , OLSON CARL R.
Published: December 2007

Abstract: It is thought that neuronal activity in orbitofrontal cortex (OFC) represents the value of anticipated reward; however activity in many other brain areas also seems to reflect expected reward value. For example, we have shown that in monkeys performing a memory‐guided saccade task for a reward of variable size, activity in numerous areas of frontal cortex is stronger when the monkey anticipates a larger reward.
The activity of these neurons might be related to the value of the expected reward or to the degree of motivation induced by expectation of the reward. Anticipation of a more valued reward leads to stronger motivation, as evidenced by measures of arousal, attention, and intensity of motor output. On the assumption that motivated behavior depends on influences arising in the limbic system and acting on the motor system, we hypothesized that neuronal signals representing reward value are unique to OFC, whereas signals arising from other frontal areas, those more closely tied the motor system, reflect the degree of motivation. To test this hypothesis, we recorded from single neurons in OFC and premotor cortex while two monkeys performed a task in which we dissociated value from motivation.
Neuronal activity in premotor cortex reflected the monkey's degree of motivation, presumably related to the monkey's level of motor readiness and movement preparation, whereas neuronal activity in OFC represented the value of expected reward.
Orbitofrontal Cortex and Cognitive‐Motivational Impairments in Psychostimulant Addiction
Authors: OLAUSSON PETER , JENTSCH J. DAVID , KRUEGER DILJA D. , TRONSON NATALIE C. , NAIRN ANGUS C. , TAYLOR JANE R.
Published: December 2007

Abstract: Addiction is characterized by compulsive drug use despite adverse consequences. The precise psychobiological changes that underlie the progression from casual use to loss of control over drug‐seeking and drug‐taking behavior are not well understood. Here we report that short‐term cocaine exposure in monkeys is sufficient to produce both selective deficits in cognitive functions dependent on the orbitofrontal cortex (OFC) concurrent with enhancements in motivational processes involving limbic‐striatal regions. Additional findings from behavioral studies and analyses of the synaptic proteome provide new behavioral and biochemical evidence that cocaine‐induced neuroadaptations in cortical and subcortical brain regions result in dysfunctional decision‐making abilities and loss of impulse control that in combination with enhancements of incentive motivation may contribute to the development of compulsive behavior in addiction.
Dysfunctions of Medial and Lateral Orbitofrontal Cortex in Psychopathy
Authors: BLAIR R. J. R.
Published: December 2007

Abstract: Psychopathy is a developmental disorder marked by emotional hypo‐responsiveness and an increased risk for instrumental and reactive aggression. In this paper, it will be argued that the developmental origins of psychopathy do not lie in orbitofrontal cortex (OFC) dysfunction. This is because the key functional impairments seen in psychopathy are associated with amygdala damage, not with OFC damage. However, it will be argued that the role played by the integrated functioning of the amygdala and medial OFC in stimulus–reinforcement learning and decision making is disrupted in psychopathy. Impaired learning of stimulus–reinforcement associations and representation of reinforcement expectations are thought to underlie the impairments in socialization and appropriate decision making seen in psychopathy. It is suggested that the impairment in the role of medial OFC in prediction error signaling and the detection of contingency change may underlie the impairments in flexible behavioral change seen in psychopathy.
The Role of Orbitofrontal Cortex in Decision Making
Authors: FELLOWS LESLEY K.
Published: December 2007

Abstract:  Clinical accounts of the effects of damage to orbitofrontal cortex (OFC) have provided important clues about the functions of this region in humans. Patients with OFC injury can demonstrate relatively isolated difficulties with decision making, and the development of laboratory tasks that captured these difficulties was an important advance. However, much of the work to date has been limited by the use of a single, complex decision‐making task and by a narrow focus on risky decisions. A fuller understanding of the neural basis of decision making requires identification of the simpler components that underlie this complex behavior. Here, I review evidence that OFC lesions disrupt reversal learning in humans, as in animals, and show that this deficit in reversal learning is an important mechanism underlying the difficulties of such patients in the Iowa gambling task. Reversal learning, in turn, can be decomposed into simpler processes: a failure to rapidly learn from negative feedback may be the critical difficulty for OFC patients. OFC damage can also affect forms of decision making that do not require trial‐by‐trial learning. Preference judgment is a simple form of decision making that requires comparing the relative value of options. Humans with OFC lesions are more inconsistent in their choices, even in very simple preference judgment tasks. These results are broadly consistent with the view that OFC is critically involved in representing the relative value of stimuli, but also raise the possibility that this region plays distinct roles in reinforcement learning and value‐based judgment.
Vulnerability of the Orbitofrontal Cortex to Age‐Associated Structural and Functional Brain Changes
Authors: RESNICK SUSAN M. , LAMAR MELISSA , DRISCOLL IRA
Published: December 2007

Abstract: Cross‐sectional and longitudinal findings from the Baltimore Longitudinal Study of Aging (BLSA) neuroimaging study indicate that the orbitofrontal cortex (OFC) is among those regions vulnerable to age‐associated tissue loss in older adults without dementia. Neuropathologic and recentin vivoamyloid imaging studies indicate that the OFC is also among the earliest neocortical regions to show deposition of amyloid plaques in aging and Alzheimer's disease. We performed behavioral and imaging studies to investigate age effects on specific aspects of OFC function. We compared performance in young (age 20–40) and old (age 60 and older) adults on cognitive tasks selected for differential sensitivity to OFC versus dorsolateral prefrontal cortex (DLPFC). Overall, greater age differences were seen in the OFC tasks compared to DLPFC tasks, with Delayed Match and Non‐Match to Sample tasks showing the greatest effect size among OFC tasks and Self‐Ordered Pointing Task showing the greatest effect size among DLPFC tasks. A functional magnetic resonance imaging study was conducted in parallel to probe the neural underpinnings of age differences in OFC function using the Delayed Match and Non‐Match to Sample paradigm. Young but not old adults showed the expected OFC activation. Older compared with young adults showed greater activation in association with successful performance for several posterior regions, perhaps indicating compensation in the face of OFC deficits. Together, these findings indicate a vulnerability of the OFC to age‐related decline in brain structure and function. Future studies using newin vivoimaging probes will help determine whether neuropathologic changes underlie the structural and functional changes.
The Contribution of Orbitofrontal Cortex to Action Selection
Authors: OSTLUND SEAN B. , BALLEINE BERNARD W.
Published: December 2007

Abstract:  A number of recent findings suggest that the orbitofrontal cortex (OFC) influences action selection by providing information about the incentive value of behavioral goals or outcomes. However, much of this evidence has been derived from experiments using Pavlovian conditioning preparations of one form or another, making it difficult to determine whether the OFC is selectively involved in stimulus–outcome learning or whether it plays a more general role in processing reward value. Although many theorists have argued that these are fundamentally similar processes (i.e., that stimulus‐reward learning provides the basis for choosing between actions based on anticipated reward value), several behavioral findings indicate that they are, in fact, dissociable. We have recently investigated the role of the OFC in the control of free operant lever pressing using tests that independently target the effect of stimulus–outcome learning and outcome devaluation on performance. We found that OFC lesions disrupted the tendency of Pavlovian cues to facilitate instrumental performance but left intact the suppressive effects of outcome devaluation. Rather than processing goal value, therefore, we hypothesize that the contribution of the OFC to goal‐directed action is limited to encoding predictive stimulus–outcome relationships that can bias instrumental response selection.
The Cell-Specific Pattern of Cholecystokinin Peptides in Endocrine Cells Versus Neurons Is Governed by the Expression of Prohormone Convertases 1/3, 2, and 5/6
Authors: Rehfeld Jens F. , Bundgaard Jens R. , Hannibal Jens , Zhu Xiaorong , Norrbom Christina , Steiner Donald F. , Friis-Hansen Lennart
Published: December 2007

Most peptide hormone genes are, in addition to endocrine cells, also expressed in neurons. The peptide hormone cholecystokinin (CCK) is expressed in different molecular forms in cerebral neurons and intestinal endocrine cells. To understand this difference, we examined the roles of the neuroendocrine prohormone convertases (PC) 1/3, PC2, and PC5/6 by measurement of proCCK, processing intermediates and bioactive, α-amidated, and O-sulfated CCK peptides in cerebral and jejunal extracts of null mice, controls, and in the PC5/6-expressing SK-N-MC cell-line. In PC1/3 null mice, the synthesis of bioactive CCK peptide in the gut was reduced to 3% of the translational product, all of which was in the form of α-amidated and tyrosine O-sulfated CCK-22, whereas the neuronal synthesis in the brain was largely unaffected. This is opposite to the PC2 null mice in which only the cerebral synthesis was affected. SK-N-MC cells, which express neither PC1/3 nor PC2, synthesized alone the processing intermediate, glycine-extended CCK-22. Immunocytochemistry confirmed that intestinal endocrine CCK cells in wild-type mice express PC1/3 but not PC2. In contrast, cerebral CCK neurons contain PC2 and only little, if any, PC1/3. Taken together, the data indicate that PC1/3 governs the endocrine and PC2 the neuronal processing of proCCK, whereas PC5/6 contributes only to a modest endocrine synthesis of CCK-22. The results suggest that the different peptide patterns in the brain and the gut are due to different expression of PCs.
Is Visfatin an Adipokine or Myokine? Evidence for Greater Visfatin Expression in Skeletal Muscle than Visceral Fat in Chickens
Authors: Krzysik-Walker Susan M. , Ocón-Grove Olga M. , Maddineni Sreenivasa R. , Hendricks Gilbert L. , Ramachandran Ramesh
Published: December 2007

Visfatin, an adipokine hormone produced primarily by visceral adipose tissue in mammals, has been implicated in the immune system, cellular aging, and glucose metabolism. Increased visceral adiposity and hyperglycemia have been correlated with elevated plasma visfatin levels in humans. The present study investigated visfatin cDNA and protein expression as well as plasma visfatin levels in chickens that are selected for rapid growth and are naturally hyperglycemic relative to mammals. By RT-PCR, we detected visfatin cDNA in multiple tissues in the chicken. The deduced amino acid sequence of full-length chicken visfatin was 92–93% homologous to mammalian visfatin. Using real-time quantitative PCR and Western blotting, chicken skeletal muscle was found to contain 5- and 3-fold greater quantities of visfatin mRNA and protein than abdominal fat pad, respectively. Visfatin mRNA and protein quantities were not significantly different among sc and visceral adipose tissue depots. Skeletal muscle visfatin mRNA and protein quantities as well as plasma visfatin levels determined by enzyme immunoassay were significantly higher in 8-wk-old compared with 4-wk-old chickens, possibly due to rapid skeletal muscle growth and visceral fat accretion occurring in broiler chickens during this period. However, fasting and refeeding did not affect plasma visfatin levels in the chicken. Collectively, our results provide novel evidence that skeletal muscle, not the visceral adipose tissue, is the primary source of visfatin in chickens, thereby raising the possibility that visfatin may be acting as a myokine affecting skeletal muscle growth and metabolism.
Islet1 cardiovascular progenitors: a single source for heart lineages?
Authors: Laugwitz Karl-Ludwig , Moretti Alessandra , Caron Leslie , Nakano Atsushi , Chien Kenneth R.
Published: December 2007

The creation of regenerative stem cell therapies for heart disease requires that we understand the molecular mechanisms that govern the fates and differentiation of the diverse muscle and non-muscle cell lineages of the heart. Recently, different cardiac cell types have been reported to arise from a common, multipotent Islet1 (Isl1)-positive progenitor, suggesting that a clonal model of heart lineage diversification might occur that is analogous to hematopoiesis. The ability to isolate, renew and differentiate Isl1+ precursors from postnatal and embryonic hearts and from embryonic stem cells provides a powerful cell-based system for characterizing the signaling pathways that control cardiovascular progenitor formation, renewal, lineage specification and conversion to specific differentiated progeny.
Percentage of harmful discharges for surface current density monitoring in electrical discharge machining process
Authors: Blatnik O , Valentincic J , Junkar M
Published: December 2007

Electrical discharge machining (EDM) is performed in the gap between the workpiece (usually the anode) and the electrode (usually the cathode). The gap is filled with a dielectric and the pulses generated by a special generator cause an electrical breakdown in the gap. A breakdown discharge occurs which removes material from the workpiece. The EDM process has been used for more than 50 years, but the influence of the surface current density on the process stability is not well understood. The surface current density is very important in the case of the machining of rough surfaces where the highest material removal rate (MRR) is preferred. For a given eroding surface there exists an optimal electrical current at which the highest MRR is achieved. It is reported in the literature that the percentage of the discharges that are harmful to the EDM process depends on the surface current density in the gap. Thus, experiments were performed to find out the possibility of using the percentage of harmful discharges to monitor the surface current density of the EDM process.