bluuebunny/crossref_metadata_2025 huggingface dataset:
Teaching clinical pathology by flexible delivery in rural sites
Authors: Hays Richard , Veitch Jan , Lam Alfred
Published: July 2005

Objective:  To evaluate the implementation of a clinical pathology and clinical skills course designed for delivery at several distributed sites, including a mandatory eight‐week placement in small remote communities.

Design:  All students in the first cohort for the course were invited to complete questionnaires rating the value of their learning experiences and the impact of relying on resources delivered by information technology. Forty‐one of 63 students responded.

Results:  Formal lectures and resources provided at the main campus were most highly valued by the students. Patient presentations in the rural and remote communities were better examples of clinical pathology than those encountered in urban hospitals, and the rural tutors were regarded very highly for their support of student learning. Delivery of resource materials in remote sites was not as successful as planned, due to difficulties with bandwidth and download speeds. Student academic performance appeared unrelated to location of learning.

Conclusion:  Students were able to achieve learning objectives for the course, relying on a richer patient mix, campus‐based core sessions and information technology‐based resources. Curriculum planners should be encouraged to further devolve learning in traditionally campus‐based content to rural and remote communities, but only after careful planning and resource allocation to support learning in rural teaching sites.
Prevalence and correlates of excessive daytime sleepiness in high school students in Korea
Authors: JOO SOONJAE , SHIN CHOL , KIM JINKWAN , YI HYERYEON , AHN YONGKYU , PARK MINKYU , KIM JEHYEONG , LEE SANGDUCK
Published: July 2005

Abstract  The purpose of the present study was to determine the prevalence of excessive daytime sleepiness (EDS) and its associations with sleep habits, sleep problems, and school performance in high school students in South Korea. A total of 3871 students (2703 boys and 1168 girls with a mean age of 16.8 years and 16.9 years, respectively) aged 15–18 years in the 11th grade of high school completed a questionnaire that contained items about individual sociodemographic characteristics, sleep habits, and sleep‐related problems. The overall prevalence of EDS was 15.9% (14.9% for boys and 18.2% for girls). Mean reported total sleep time was similar in EDS and non‐EDS (6.4 ± 1.6 and 6.4 ± 1.3 h/day, respectively). The increased risk of EDS was related to perceived sleep insufficiency (P < 0.001), teeth grinding ≥ 4 days/week (P < 0.001), witnessed apnea ≥1–3 days/week (P < 0.01), nightmares ≥4 days/week (P < 0.05), low school performance (P < 0.01), and two or more insomnia symptoms (P < 0.05). Students with low school performance had a 60% excess in the odds of EDS compared to those whose school performance was high. These findings suggest that EDS is associated with multiple sleep‐related factors in adolescents. Whether interventions to modify associated correlates can alter EDS warrants consideration, especially because it may also improve academic performance in high school students.
Follow‐up on the γ‐glutamyl transpeptidase in patients with severe dysplasia in an area of high incidence of esophageal cancer
Authors: LI Jian , BAI Jing Xiu , ZHAO Zhi Gou , ZHENG Peng Yuan , MA Jun , GUO Min , LIU Yun Yuan
Published: July 2005

OBJECTIVE:  To investigate the clinical value of cytological γ‐glutamyl transpeptidase (γ‐GT) staining in the reduction of the morbidity and mortality of esophageal cancer in an area of China that has a high incidence of esophageal cancer.

METHODS:  The results of pathology, cytological examination with γ‐GT staining in 451 patients with severe dysplasia were analyzed and followed‐up for 3 years.

RESULTS:  At the 1‐year follow‐up, 17 of 231 patients with positive γ‐GT staining (7.4%) had developed esophageal cancer, but no cancer was detected in 95 patients with negative γ‐GT staining. Among 215 patients who were followed‐up for 3 years, the risk of developing cancer in γ‐GT staining positive patients with grade I or II severe dysplasia was 5.7% and 14.3%, respectively. However, esophageal cancer was not found in patients with negative γ‐GT staining or in patients with positive γ‐GT staining who were younger than 40 years.

CONCLUSIONS:  These findings suggest that γ‐GT staining can be used as a cancer risk marker of esophageal epithelial dysplasia. Esophageal dysplasia needs to be further categorized according to γ‐GT staining for esophageal cancer prevention, and intervention is required for γ‐GT staining positive patients with severe dysplasia in order to increase the cost–benefit ratio of esophageal cancer prevention.
CD14 expression on Kupffer cells during the course of carbon tetrachloride‐mediated liver injury
Authors: QIU De Kai , HUA Jing , LI Ji Qiang , LI Eng Ling
Published: July 2005

OBJECTIVE:  To investigate the expression of CD14 on Kupffer cells during the course of carbon tetrachloride (CCl4)‐mediated liver injury and its role in the activation of Kupffer cells.

METHODS:  Rats were administered CCl4 twice weekly for up to 8 weeks. Kupffer cells were isolated from normal and CCl4‐treated rats by the combined ‘collagenase‐pronase’ perfusion method, discontinuous density gradient centrifugation. On the day after isolation, the cells were incubated with RPMI‐1640 containing varying doses of lipopolysaccharide (LPS) for 6 h. Supernatants were then collected for measuring the concentration of tumor necrosis factor‐alpha (TNF‐α) by enzyme‐linked immunosorbent assay (ELISA). The expression of CD14 mRNA on Kupffer cells were determined by RT‐PCR. The plasma concentrations of endotoxin were determined by chromogenic substrate Limulus amebocyte lysate assay.

RESULTS:  Basic TNF‐α production of Kupffer cells isolated from CCl4‐treated rats at 4 and 6 weeks was significantly higher than that of normal (P < 0.05). Following LPS stimulation the production of TNF‐α was markedly increased in Kupffer cells from the 2‐, 4‐ and 6‐week treatment groups (P < 0.05). Moreover, LPS‐induced TNF‐α production was dose‐dependent. CD14 mRNA expression on Kupffer cells isolated from CCl4‐treated rats was elevated following 2 weeks of CCl4 administration and the maximum elevation occurred at 6 weeks. Gene expression was decreased in Kupffer cells after 8 weeks of CCl4 treatment. CCl4 administration elicited extensive changes in liver morphology, including steatosis, inflammation and necrosis. The plasma concentrations of endotoxin of CCl4‐treated rats were increased during the time of liver injury.

CONCLUSION:  Up‐regulation of CD14 expression in Kupffer cells during CCl4‐mediated chronic liver injury indicates cell activation and that they are more sensitive to LPS stimulation. Kupffer cells are critical effector cells in the early stage of liver injury.
Increased measures of anxiety and weight gain in mice lacking the group III metabotropic glutamate receptor mGluR8
Authors: Duvoisin Robert M. , Zhang Connie , Pfankuch Timothy F. , O'Connor Heather , Gayet‐Primo Jacqueline , Quraishi Salma , Raber Jacob
Published: July 2005

To study the role of the metabotropic glutamate receptor 8 (mGluR8), mice lacking this receptor were generated by homologous recombination. Homozygous mGluR8‐deficient mice are about 8% heavier than their wild‐type age‐matched controls after reaching 4 weeks of age. This weight difference is not caused by an altered food intake and is not exacerbated by feeding the animals a high‐fat diet. Moreover, mGluR8–/– mice are mildly insulin resistant, possibly as a result of being overweight. Behavioral testing revealed a reduced locomotor activity of mGluR8–/– mice compared with wild‐type mice during the first 3 days in a novel enclosed environment. However after 3 days, the locomotor activities of wild‐type and mGluR8–/– mice were similar, suggesting a reduced exploratory behavior of mGluR8–/– mice in a novel enclosed environment. By contrast, there were no genotype differences in locomotor activity in the open field, plus maze, or in total time spent exploring objects during object recognition tests, indicating that there is a dissociation between effects of mGluR8 deficiency in exploratory activity in a novel safe enclosed environment vs. a more anxiogenic novel open environment. The absence of mGluR8 also leads to increased measures of anxiety in the open field and elevated plus maze. Whether the diverse phenotypic differences observed in mGluR8–/– mice result from the misregulation of a unique neural pathway, possibly in the thalamus or hypothalamus, or whether they are the consequence of multiple developmental and functional alterations in synaptic transmission, remains to be determined.
The robustness of perception
Authors: Reinders A. A. T. S. , Den Boer J. A. , Büchel C.
Published: July 2005

The natural environment around us, which is often crowded, cluttered or even foggy, is subject to a dynamically changing composition of objects and events. The human brain is continuously perceiving, recognizing and evaluating this dynamic scene composition. If the perception of degraded visual objects is important, e.g. in the case of potential threat stimuli, the brain needs to be more sensitive in detecting these objects from the natural environment. It is therefore hypothesized that reacting to the dynamically changing environment involves a robust and quick processing of salient information, which can be either with or without conscious awareness. We investigated the dynamics and robustness of perception using pictures of three salience levels, i.e. fearful faces (most salient), neutral faces (salient) and houses (nonsalient), which appear from dynamically decreasing random visual noise. Stimuli were matched for luminance, contrast, brightness and spatial frequency information. Reaction times show a significantly earlier response for faces than for houses. Fearful faces were significantly more quickly detected than neutral faces. The neural correlates sustaining robust perception were investigated with event‐related functional magnetic resonance imaging (fMRI). The amygdala showed a significant perception‐related response for faces, as compared to houses, that was further enhanced for fearful faces as compared to neutral faces. Our data indicate that emotionally salient information processing is (i) mediated by the amygdala and (ii) more robust than for nonsalient stimuli as it shows a significantly lower perceptual threshold.
A 2‐Year‐Old Girl with Stevens–Johnson Syndrome/Toxic Epidermal Necrolysis Treated with Intravenous Immunoglobulin
Authors: Arca Ercan , Köse Osman , Erbil A. Hakan , Nişancı Mustafa , Akar Ahmet , Gür Ali Rıza
Published: July 2005

Abstract:  Toxic epidermal necrolysis and Stevens–Johnson syndrome are severe skin reactions, usually to drugs, associated with a widespread destruction of the epidermis. Widespread purpuric macules and epidermal detachment of less than 10% of the body surface is indicative of Stevens–Johnson syndrome, whereas epidermal detachment between 10% and 30% is called Stevens–Johnson‐toxic epidermal necrolysis overlap. Epidermal detachment involving more than 30% of the total body surface is designated as toxic epidermal necrolysis. These generalized reactions are known to occur in association with various drugs. Treatment is primarily supportive care, and there are no specific therapy regimens. Therapeutic modalities such as corticosteroids, cyclosporin, thalidomide, cyclophosphamide, and plasmapheresis, usually based on a symptomatic approach, have been tried in single patients or in small series. Intravenous immunoglobulin has recently been shown to provide rapid improvement in all three of these skin reactions. We report a 2‐year‐old girl who developed Stevens–Johnson syndrome‐toxic epidermal necrolysis overlap after receiving ampicillin‐sulbactam for an upper respiratory tract infection. She was treated successfully with a 4‐day course of intravenous immunoglobulin.
Congenital Becker Nevus with Lichen Planus
Authors: Puri Suruchi , Nanda Soni , Grover Chander , Batra Vineeta Vijay , Garg Vijay Kumar , Reddy B. S. N.
Published: July 2005

Abstract:  We report an interesting and rare association of congenital Becker nevus with lichen planus occurring in an 11‐year‐old boy. Both conditions were confirmed histopathologically.
Large Atypical Melanocytic Nevi in Recessive Dystrophic Epidermolysis Bullosa: Clinicopathological, Ultrastructural, and Dermoscopic Study
Authors: Gallardo Fernando , Toll Agustí , Malvehy Josep , Mascaró‐Galy Jose Manuel , Lloreta Josep , Barranco Carles , Pujol Ramon M.
Published: July 2005

Abstract:  A 3‐year‐old boy with recessive dystrophic epidermolysis bullosa developed a rapidly growing, large, acquired irregular melanocytic nevus on the lower aspect of the back. The lesion was clinically atypical and fulfilled the criteria for a malignant melanocytic proliferation. A complete surgical excision was performed. Histopathologic examination disclosed a compound melanocytic nevus without melanocytic atypia. Ultrastructural examination showed melanocytic cells located both at the roof and the floor of the blister. Several months later, three pigmentary lesions with a similar clinical appearance developed. Periodic clinical and dermoscopic examinations were recommended. Dermoscopic examination disclosed a globular pattern with brown globules and black dots distributed all over the lesions. The lesions also exhibited blue‐greyish dots and multiple rounded white structures corresponding to milia‐like cysts. No dermoscopic features suggestive of malignancy were noted. Acquired melanocytic nevi showing atypical clinical features have been reported to occur in areas of blistering in patients with epidermolysis bullosa. These nevi appear as large, asymmetrical pigmentary lesions with irregular borders. Initially, they are very dark in pigmentation, with color variegation and loss of pigment, and even becoming papillomatous over time. Histopathologic examination can show features of compound/junctional nevus as well as persistent/recurrent nevus. The concept of “epidermolysis bullosa nevus” has been proposed to define these peculiar lesions. The clinical, histopathologic and ultrastructural features of these nevi are reviewed. The usefulness of dermoscopic examination in the routine diagnosis and follow‐up of these lesions are stressed.
Autosomal Dominant Precalcaneal Congenital Fibrolipomatous Hamartoma
Authors: Meyer Peter , Soennichsen Karsten , Buchenau Wolfgang
Published: July 2005

Abstract:  Precalcaneal congenital fibrolipomatous hamartoma is a rare minor malformation previously reported only as sporadic. We report this finding in three family members from two generations, suggesting autosomal dominant inheritance.
Severe Acne Infantum Successfully Treated with Isotretinoin
Authors: Torrelo Antonio , Pastor M. Antonia , Zambrano Antonio
Published: July 2005

Abstract:  Treatment of severe nodular infantile acne with oral isotretinoin has been effective and well tolerated in a small number of patients. We present another instance of successful treatment of severe acne with oral isotretinoin in a young infant and suggest that isotretinoin should be the treatment of choice for severe nodular acne in children and infants, especially if topical treatments or oral antibiotics have failed.
Non‐synaptic mechanisms underlie the after‐effects of cathodal transcutaneous direct current stimulation of the human brain
Authors: Ardolino G. , Bossi B. , Barbieri S. , Priori A.
Published: July 2005

Although cathodal transcranial direct current stimulation (tDCS) decreases cortical excitability, the mechanisms underlying DC‐induced changes remain largely unclear. In this study we investigated the effect of cathodal DC stimulation on spontaneous neural activity and on motor responses evoked by stimulation of the central and peripheral nervous system. We studied 17 healthy volunteers. Transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES) of the motor area were used to study the effects of cathodal tDCS (1.5 mA, 10 min) on resting motor threshold and motor evoked potentials (MEPs) recorded from the contralateral first dorsal interosseous muscle (FDI). The electroencephalographic (EEG) activity in response to cathodal tDCS was analysed by power spectral density (PSD). Motor axonal excitability changes in response to transcutaneous DC stimulation of the ulnar nerve (0.3 mA, 10 min) were assessed by testing changes in the size of the compound muscle action potential (CMAP) elicited by submaximal nerve stimulation. Cathodal tDCS over the motor area for 10 min increased the motor threshold and decreased the size of MEPs evoked by TMS for at least 60 min after current offset (t0 71.7 ± 5%, t20 50.8 ± 11%, t40 47.7 ± 7.7%, and t60 39.7 ± 6.4%, P < 0.01). The tDCS also significantly decreased the size of MEPs elicited by TES (t0 64 ± 16.4%, P= 0.09; t20 67.6 ± 10.8%, P= 0.06; and t40 58.3 ± 9.9%, P < 0.05). At the same time in the EEG the power of delta (2–4 Hz) and theta (4–7 Hz) rhythms increased (delta 181.1 ± 40.2, P < 0.05; and theta 138.7 ± 27.6, P= 0.07). At the peripheral level cathodal DC stimulation increased the size of the ulnar nerve CMAP (175 ± 34.3%, P < 0.05). Our findings demonstrate that the after‐effects of tDCS have a non‐synaptic mechanism of action based upon changes in neural membrane function. These changes apart from reflecting local changes in ionic concentrations, could arise from alterations in transmembrane proteins and from electrolysis‐related changes in [H+] induced by exposure to constant electric field.
Presynaptic N‐type and P/Q‐type Ca2+ channels mediating synaptic transmission at the calyx of Held of mice
Authors: Ishikawa Taro , Kaneko Masahiro , Shin Hee‐Sup , Takahashi Tomoyuki
Published: July 2005

At the nerve terminal, both N‐ and P/Q‐type Ca2+ channels mediate synaptic transmission, with their relative contribution varying between synapses and with postnatal age. To clarify functional significance of different presynaptic Ca2+ channel subtypes, we recorded N‐type and P/Q‐type Ca2+ currents directly from calyces of Held nerve terminals in α1A‐subunit‐deficient mice and wild‐type (WT) mice, respectively. The most prominent feature of P/Q‐type Ca2+ currents was activity‐dependent facilitation, which was absent for N‐type Ca2+ currents. EPSCs mediated by P/Q‐type Ca2+ currents showed less depression during high‐frequency stimulation compared with those mediated by N‐type Ca2+ currents. In addition, the maximal inhibition by the GABAB receptor agonist baclofen was greater for EPSCs mediated by N‐type channels than for those mediated by P/Q‐type channels. These results suggest that the developmental switch of presynaptic Ca2+ channels from N‐ to P/Q‐type may serve to increase synaptic efficacy at high frequencies of activity, securing high‐fidelity synaptic transmission.
Formation of Catalytic Metal-Molecule Contacts
Authors: Tulevski George S. , Myers Matt B. , Hybertsen Mark S. , Steigerwald Michael L. , Nuckolls Colin
Published: July 2005

We describe a new strategy for the in situ growth of molecular wires predicated on the synthesis of a trifunctional “primed” contact formed from metal-carbon multiple bonds. The ruthenium-carbon π bond provides structural stability to the molecular linkages under ambient conditions, and density functional calculations indicate the formation of an efficient conduit for charge carriers to pass between the metal and the molecule. Moreover, the metal-carbon π bond provides a chemically reactive site from which a conjugated molecular wire can be grown in situ through an olefin metathesis reaction.
Identification of a
d
-
glycero
-
d
-
manno
-Heptosyltransferase Gene from
Helicobacter pylori
Authors: Hiratsuka Koji , Logan Susan M. , Conlan J. Wayne , Chandan Vandana , Aubry Annie , Smirnova Natalia , Ulrichsen Heather , Chan Kenneth H. N. , Griffith Douglas W. , Harrison Blair A. , Li Jianjun , Altman Eleonora
Published: July 2005

We have identified a
Helicobacter pylori
d
-
glycero
-
d
-
manno
-heptosyltransferase gene, HP0479, which is involved in the biosynthesis of the outer core region of
H. pylori
lipopolysaccharide (LPS). Insertional inactivation of HP0479 resulted in formation of a truncated LPS molecule lacking an α-1,6-glucan-,
dd
-heptose-containing outer core region and O-chain polysaccharide. Detailed structural analysis of purified LPS from HP0479 mutants of strains SS1, 26695, O:3, and PJ1 by a combination of chemical and mass spectrometric methods showed that HP0479 likely encodes α-1,2-
d
-
glycero
-
d
-
manno
-heptosyltransferase, which adds a
d
-
glycero
-
d
-
manno
-heptose residue (DDHepII) to a distal
dd
-heptose of the core oligosaccharide backbone of
H. pylori
LPS. When the wild-type HP0479 gene was reintegrated into the chromosome of strain 26695 by using an “antibiotic cassette swapping” method, the complete LPS structure was restored. Introduction of the HP0479 mutation into the
H. pylori
mouse-colonizing Sydney (SS1) strain and the clinical isolate PJ1, which expresses
dd
-heptoglycan, resulted in the loss of colonization in a mouse model. This indicates that
H. pylori
expressing a deeply truncated LPS is unable to successfully colonize the murine stomach and provides evidence for a critical role of the outer core region of
H. pylori
LPS in colonization.
Fire disturbance of larch woodlands in string fens in northern Québec
Authors: Busque Daniel , Arseneault Dominique
Published: July 2005

In this study, dendrochronology was used to reconstruct the fire history and associated dynamics of the last 350 years in three larch (Larix laricina [Du Roi] K. Koch) woodlands in string fens of the northern boreal forest of Quebec. Fire scars were also sampled to reconstruct the fire history across the surrounding uplands. Our results show that string fens are more likely to experience partial disturbance than complete removal of the tree cover during fire. Although large fires burned across the studied landscape in 1733, 1787, 1865, and 1941, no stand-replacing fire has occurred in any of the studied woodlands. At all sites, the oldest larch trees became established around 16401680, and several individuals survived each fire identified across the uplands. However, partial disturbance during the most recent 1941 fire, which was associated with severe fire weather, decreased tree density and released the growth of several trees. Although signs of previous fire may have been lost through wood decay, no fire impacted larch growth as severely as the 1941 fire, further emphasizing the modest influence of fire in string fens as compared with uplands. The low fire influence in these minerotrophic peatlands helps explain the high occurrence of the fire-sensitive eastern larch.Key words: boreal forest, fire disturbance, larch woodland, Larix laricina, northern Quebec, string fen.
A floating aquatic system employing water hyacinth for municipal landfill leachate treatment: effect of leachate characteristics on the plant growth
Authors: El-Gendy A S , Biswas N , Bewtra J K
Published: July 2005

The current research demonstrates the effects of certain parameters, usually present in municipal landfill leachate, on the growth of water hyacinth (Eichhornia crassipes), a floating aquatic plant, when used for treatment of leachate. Experiments were carried out to investigate the ability of water hyacinth to grow in leachate with different salinity ions concentrations, nutrients, pH, and heavy metals concentrations. The ability of water hyacinth to remove some parameters such as nitrogen, potassium, phosphorus, total solids, and chloride were also investigated. All experiments were conducted in batch reactors in a greenhouse environment. The leachate samples were collected from Essex–Windsor Regional Landfill, Windsor, Ontario. It was found that this treatment system required the presence of sufficient amount of nutrients (N, P, and K) to ensure plant growth. Optimum growth took place when the initial chloride and sodium concentrations were 560 mg L–1 and 330 mg L–1, respectively. The leachate pH for optimum water hyacinth growth was found to be in the range of 5.8 to 6.0. Total heavy metal concentrations below 0.10 mequiv L–1 supported the plant growth; concentrations above 0.91 mequiv L–1 inhibited the plant growth. Removal efficiencies of nitrogen, potassium, phosphorus, chloride, and total solids from leachate were found to be affected by the growth of water hyacinth. Higher removals were obtained with higher plant growth. Key words: water hyacinth, municipal landfill leachate, chloride, sodium, heavy metals, water hyacinth growth, leachate treatment, bioconcentration factor.
Efficacy of lime mud residues from kraft mills to amend oxidized mine tailings before permanent flooding
Authors: Catalan Lionel J.J , Kumari Abha
Published: July 2005

Flooding mine tailings that have partially oxidized is a rehabilitation method commonly practiced at sites having a positive hydrologic balance and a suitable topography to limit further oxidation of the remaining sulfide minerals. The purpose of this study was to assess the efficacy of amending oxidized mine tailings with lime mud residue (LMR) before flooding to reduce the release of acidity and heavy metals to the water cover and the pore water. Series of LMR samples from three kraft pulp mills were collected over several weeks and characterized to evaluate their variability in composition and physical characteristics. All LMR samples consisted of silt-sized aggregates of CaCO3 crystals and contained very low concentrations of legislated heavy metals. Flow-through column tests were carried out with the following three configurations: (i) water cover over oxidized tailings; (ii) water cover over LMR layer over oxidized tailings; and (iii) water cover over LMR + oxidized tailings mixtures over oxidized tailings. A permanent water cover was maintained at the top of all the columns to simulate flooded conditions. The LMR amendment was effective for maintaining the pH at neutral or slightly alkaline values and dissolved heavy metal concentrations below regulatory limits in the water cover and in the pore water of the mixed LMR + tailings layer. However, the pH remained acidic and heavy metal concentrations were elevated in the pore water of the underlying oxidized tailings layer, even after hundreds of pore volumes of water had infiltrated through the columns. The behavior of pore water pH in the underlying oxidized tailings was attributed to the low solubility of CaCO3 and the consumption of bicarbonate ions by reaction with Fe-oxyhydroxysulfate minerals. Key words: lime mud residue, recaust, tailings, acid mine drainage, flooding, water cover.
Electroosmotic introduction of methacrylate polycations to dehydrate clayey soil
Authors: Pączkowska Bożena
Published: July 2005

The results of research on highly swelling and contractible Pliocene clays are presented in this paper. The introduction of the polymer poly(methyl methacrylate) (with pendant chains possessing organic cations (poly-DEAH+Cl)) into the clay and the dewatering of the clay were performed using the electroosmosis technique. The measurements were made using a simple electroosmosis apparatus equipped with a specially designed anode, with an electric field equal to 0.5 V/cm applied during the process. After the introduction of the polymeric materials into the clay, a more uniform distribution of the water content and a shortening of the dewatering time were observed in the tested samples. In some cases, dehydration in the presence of poly-DEAH+Cl was four times more effective than dewatering carried out without a polymeric additive. Additionally, as pilot measurements have shown, the introduction of a proper amount of poly-DEAH+Cl into the host layers of the clay causes: (i) a decrease in the expansion index, EI, of about 60%; (ii) an increase in the strength parameter, Cu (cohesion), of about 50%; (iii) an increase in the internal friction angle, ϕu, of about 100%; and (iv) a very high decrease in soaking. The claypolymer composite demonstrates high resistance against moisture.Key words: electroosmosis, polymeric additive, electroosmotic dewatering, clay physical properties.
Physical clogging of soil filters under constant flow rate versus constant head
Authors: Reddi Lakshmi N , Xiao Ming , Hajra Malay G , Lee In Mo
Published: July 2005

In this study, the differences in soil filter clogging are evaluated under two operating conditions: constant head and constant flow rate. Whereas filters placed around well screens and leachate collection systems are subjected to a constant flow rate, filters in earth dams and pavement drainage systems operate under constant or slightly varying heads. In this study, the experiments revealed similar permeability reductions with respect to time in both cases; however, the permeability reduction under the condition of constant head occurred in much fewer pore volumes than under the condition of constant flow rate. Self-filtration appeared to be greater under the condition of constant head. The physical clogging model developed for the conditions of constant flow rate and constant head showed good qualitative agreement with experimental observations.Key words: particle, clogging, filter, constant, head, flow.
Regression model for evaluating liquefaction potential by discriminant analysis of the SPTNvalue
Authors: Lai Sheng-Yao , Lin Ping-Sien , Hsieh Ming-Jyh , Jim Hoi-Fung
Published: July 2005

Discriminant models are developed for evaluating soil liquefaction potential, using standard penetration test (SPT) data for 592 occurrences of liquefaction and nonliquefaction. The discriminant model used is a multivariate statistical method. The square root of the SPT N value, (N1)601/2, and the logarithm of the cyclic stress ratio, ln CSR7.5, are adopted as the major parameters for analyses. Two models measuring liquefaction resistance through the SPT N value are also established in this study, which allows calculated results to be compared with the empirical curves. Key words: liquefaction, discriminant analysis, misclassified probability.
Performance of cement-stabilized retaining walls
Authors: Ismail M A
Published: July 2005

This paper investigates the performance of a cement-stabilized retaining wall as a potentially economic solution for supporting vertical cuts in roads and embankments. This investigation was carried out through a comprehensive numerical and experimental program in which the stabilized wall was treated as a c′ϕ soil. To optimize the design of the stabilized wall, a plane-strain finite element analysis was carried out, using the PLAXIS code, in a parametric study that varied the wall geometry and the shear strength parameters for both the wall and its surrounding soil. The performance of the stabilized retaining wall was verified by a centrifuge model test carried out at an equivalent acceleration of 67g for a sand treated with 3% Portland cement. The results have shown that the load-carrying capacity of the wall is affected primarily by both the cementation of the wall and the friction angle of the surrounding soil. There exists a threshold of cementation beyond which the stability does not increase when the failure mechanism is located completely inside the in situ soil. This critical cementation appears to be a crucial factor in maintaining an economic design for this type of wall. Centrifuge test results confirmed the satisfactory behaviour of cement-stabilized retaining walls.Key words: cement stabilization, retaining wall, cohesion, finite element, centrifuge testing.
OVERHEAD COMPENSATION IN PERFORMANCE PROFILING
Authors: Malony Allen D. , Shende Sameer S.
Published: July 2005

Measurement-based profiling introduces intrusion in program execution. Intrusion effects can be mitigated by compensating for measurement overhead. Techniques for compensation analysis in performance profiling are presented and their implementation in the TAU performance system described. Experimental results on the NAS parallel benchmarks demonstrate that overhead compensation can be effective in improving the accuracy of performance profiling. However, parallel time profiling requires the execution delay introduced by measurement on individual processes to be communicated between processes when they interact. Parallel execution scenarios are given to model the effects and to determine the analysis procedures to be applied online.
ADAPTING A PURE DECENTRALIZED PEER-TO-PEER PROTOCOL FOR GRID SERVICES INVOCATION
Authors: TALIA DOMENICO , TRUNFIO PAOLO
Published: July 2005

Several aspects of today's Grids are based on centralized or hierarchical services. However, as Grids increase their size from tens to thousands of hosts, functionalities should be decentralized to avoid bottlenecks and guarantee scalability. A way to ensure Grid scalability is to adopt Peer-to-Peer (P2P) models and techniques to implement non-hierarchical decentralized Grid services and systems. Pure decentralized P2P protocols based on a pervasive exchange of messages, such as Gnutella, appear to be inadequate for OGSA Grids, where peers communicate among them through Grid Services mechanisms. On the other hand, this class of protocols offers useful properties in dealing with Grid resources heterogeneity and dynamicity. This paper proposes a modified Gnutella discovery protocol, named Gridnut, which makes it suitable for OGSA Grids. In particular, Gridnut uses appropriate message buffering and merging techniques to make Grid Services effective as a way to exchange messages in a P2P fashion. We present the design of Gridnut and compare Gnutella and Gridnut performances under different network and load conditions.
EXPERIMENTAL RESULTS ABOUT MPI COLLECTIVE COMMUNICATION OPERATIONS
Authors: BERNASCHI MASSIMO , IANNELLO GIULIO , CREA SAVERIO
Published: July 2005

Collective communication performance is critical in a number of MPI applications. In this paper we focus on two widely used primitives, broadcast and reduce, and present experimental results obtained on a cluster of PC connected by InfiniBand. We integrated our algorithms in the MPICH library and we used MPICH implementation of broadcast and reduce primitives to compare the performance of our algorithms based on α-trees. Our tests show that the MPICH implementation can be improved.
SIGNATURES OF ACCRETION SHOCKS IN BROADBAND SPECTRUM OF ADVECTIVE FLOWS AROUND BLACK HOLES
Authors: MANDAL SAMIR , CHAKRABARTI SANDIP K.
Published: July 2005

We compute the effects of the centrifugal pressure supported shock waves on the emitted spectrum from an accretion disk primarily consisting of low angular momentum matter. Electrons are very efficiently accelerated by the accretion shock and acquire power-law distribution. The accelerated particles in turn emit synchrotron radiation in the presence of a stochastic magnetic field in equipartition with the gas. Efficient cooling of the electrons by these soft photons reduces its temperature in comparison to the protons. We explore the nature of the broadband spectra by using Comptonization, bremsstrahlung and synchrotron emission. We then show that there could be two crossing points in a broadband spectrum, one near ~10 keV and the other ~300–400 keV.
VAN DER WAALS FORCES IN CURVED SPACE AS A QUANTUM TOOL TO TEST GENERAL RELATIVITY THEORY
Authors: PINTO FABRIZIO
Published: July 2005

It has been known shortly after the introduction of the general relativity theory that the electrostatic Coulomb potential of a point charge supported in a gravitational field is not spherically symmetric and becomes warped in curved space. Under ordinary laboratory conditions, this effect is quite small and has never been directly observed. Surprisingly, this distortion causes the appearance of a hitherto unknown, topologically complex non-central van der Waals force whose detection is well within range of existing trapped atom interferometry techniques. This will allow for an unexpected experimental test of gravity theory by means of quantum-electro-dynamical interatomic forces.
DENSITY FUNTIONAL STUDY OF THE STRUCTURE OF THE FeMo COFACTOR WITH AN INTERSTITIAL ATOM AND HOMOCITRATE LIGAND RING OPENING
Authors: CAO ZEXING , JIN XI , ZHANG QIANER
Published: July 2005

The structure of the FeMo cofactor with the central X ligand ( X = C 4-, C 2-, N 3-, N -, or O 2-) has been determined by the density functional approach. The FeMo cluster with one of the proposed central atoms C 4-, C 2-, N 3-, or N - has an optimized geometry, comparable with the high-resolution X-Ray crystallographic structure of the nitrogenase FeMo cofactor. When the O 2- species is present, the FeMo cofactor has an expanded cage. Calculations in the gas phase show that an >Fe 4 facet of the FeMo cluster binds NO and CO in end-on coordination with an exothermicity of 25 and 8 kcal mol-1, respectively, while the singlet O 2 coordinates to the FeMo cluster with an endothermicity of 12 kcal mol-1. Deoxygenization of the bound NO and CO by the proton-electron addition is favored energetically, which leads to penetration of the C or N atom into the FeMo cage and yields the FeMo (μ6- X ) cluster. Antiferromagnetic coupling between the Fe sites and vibrational properties of the FeMo (μ6- X ) cluster, as well as the Mo-bound homocitrate ligand ring opening, have been explored theoretically. Present results suggest that O 2- is unlikely as a central anion and the central ligands are identifiable by their IR spectra. Predicted energetics indicates that the protonation opening of the homocitrate ligand ring at the Mo site is feasible.
CORRELATION BETWEEN ELECTRONIC STRUCTURES OF METAL-INTERCALATED SINGLE WALL CARBON NANOTUBES WITH THEIR FIELD EMISSION PROPERTIES
Authors: WANG YAN , TRUONG THANH N.
Published: July 2005

The effects of various metal intercalations ( Li , Na and Be ) on the electronic structures and the field emission properties of single-wall carbon nanotubes (SWNT) were investigated using the periodic plane-wave DFT method. We found that intercalations of metal tend to shift the conductive characteristics of the SWNT from those of a semiconductor to those of a quasi-metallic conductor. The Fermi levels for all metal-intercalated in SWNT are moved toward the conduction band, induced by the charge transfer from the metal to the SWNT. Intercalations of Li and Na atoms increase the field emission current, whereas Be intercalation does not affect the field emission current due to the absence of high density of states around the Fermi level. The correlation between the electronic structures for the metal-intercalated nanowires with field emission properties is further discussed in light of the above results.
THEORETICAL STUDY ON THE UNIMOLECULAR REACTIONS OF GLYOXYLIC ACID
Authors: DING WAN-JIAN , NI LING-YAN , FANG WEI-HAI , YU JIAN-GUO
Published: July 2005

The potential energy surfaces of isomerization, decarboxylation, and decarbonylation reactions of glyoxylic acid have been characterized by the B3LYP/cc-pVTZ, B3LYP/aug-cc-pVTZ, and MP2/cc-pVTZ calculations. There is a relatively high barrier on the isomerization pathway from Tc to Tt , due to existence of the intramolecular H-bond in the Tc to Tt structures. The decarboxylation reaction proceeds mainly through a stepwise mechanism. The singlet hydroxyl carbene and carbon dioxide are formed in the first step, which is followed by isomerization of the carbene to formaldehyde in the second step. The thermal decarbonylation reaction of glyoxylic acid may take place at high temperature, due to a barrier of ~52 kcal/mol on the pathway.
A THEORETICAL STUDY ON THE INTERMOLECULAR HYDROACYLATION OF ALKYNE CATALYZED BY CATIONIC RHODIUM COMPLEX
Authors: CHUNG LUNG WA , WU YUN-DONG
Published: July 2005

Theoretical calculations have been carried out to study the mechanism of intermolecular hydroacylation of acetylene with acetaldehyde. The results indicate that the generally accepted mechanism, C–H oxidative addition followed by hydrometallation and reductive elimination, is the most favorable pathway. The intermolecular hydroacylation reaction of acetylene is shown to suffer from three problems: (1) the formation of a stable bis-acetylene intermediate, which leads to a facile dimerization side-reaction; (2) higher activation barrier of the rate-determining C–H (carbonyl) bond activation; and (3) "fatal" easy decarbonylation from hydrometalated intermediate and subsequent reductive elimination to give decarbonylation product. Our calculations indicate that the above three problems can all be overcome by the use of a tethered carbonyl substrate with a chelation-forming basic donor ligand such as alkylthio group.
MODELING VIBRATIONAL SPECTRA USING THE SELF-CONSISTENT CHARGE DENSITY-FUNCTIONAL TIGHT-BINDING METHOD II: INFRARED SPECTRA
Authors: WITEK HENRYK A. , MOROKUMA KEIJI , STRADOMSKA ANNA
Published: July 2005

We present an extended self-consistent charge density-functional tight-binding (SCC-DFTB) method that allows for computing vibrational infrared spectra. The extension is based on introducing an additional term in the SCC-DFTB energy formula that describes effectively the interaction of external electric field with molecular electron density distribution. The extended SCC-DFTB method is employed to model vibrational infrared spectra of 16 organic molecules. The calculated spectra are compared to experiment and to spectra obtained with density functional theory. For most of the molecules, the SCC-DFTB method reproduces the experimental spectra in a very satisfactory manner. We discuss the drawbacks and possible applications of this new scheme.
Expression and function of 5-HT4receptors in the mouse enteric nervous system
Authors: Liu Mintsai , Geddis Matthew S. , Wen Ying , Setlik Wanda , Gershon Michael D.
Published: July 2005

The aim of the current study was to identify enteric 5-HT4splice variants, locate enteric 5-HT4receptors, determine the relationship, if any, of the 5-HT4receptor to 5-HT1Pactivity, and to ascertain the function of 5-HT4receptors in enteric neurophysiology. 5-HT4a, 5-HT4b, 5-HT4e, and 5-HT4fisoforms were found in mouse brain and gut. The ratio of 5-HT4expression to that of the neural marker, synaptophysin, was higher in gut than in brain but was similar in small and large intestines. Submucosal 5-HT4expression was higher than myenteric. Although transcripts encoding 5-HT4aand 5-HT4bisoforms were more abundant, those encoding 5-HT4eand 5-HT4fwere myenteric plexus specific. In situ hybridization revealed the presence of transcripts encoding 5-HT4receptors in subsets of enteric neurons, interstitial cells of Cajal, and smooth muscle cells. IgY antibodies to mouse 5-HT4receptors were raised, affinity purified, and characterized. Nerve fibers in the circular muscle and the neuropil in ganglia of both plexuses were highly 5-HT4immunoreactive, although only a small subset of neurons contained 5-HT4immunoreactivity. No 5-HT4-immunoreactive nerves were detected in the mucosa. 5-HT and 5-HT1Pagonists evoked a G protein-mediated long-lasting inward current that was neither mimicked by 5-HT4agonists nor blocked by 5-HT4antagonists. In contrast, the 5-HT4agonists renzapride and tegaserod increased the amplitudes of nicotinic evoked excitatory postsynaptic currents. Enteric neuronal 5-HT4receptors thus are presynaptic and probably exert their prokinetic effects by strengthening excitatory neurotransmission.
Flow inhibits inward remodeling in cannulated porcine small coronary arteries
Authors: Pistea Adrian , Bakker Erik N. T. P. , Spaan Jos A. E. , VanBavel Ed
Published: July 2005

The mechanisms of flow-induced vascular remodeling are poorly understood, especially in the coronary microcirculation. We hypothesized that application of flow in small coronary arteries in organoid culture would cause a nitric oxide (NO)-mediated dilation and inhibit inward remodeling. We developed an organoid culture setup to drive a flow through cannulated arterioles at constant luminal pressure via a pressure gradient between the pipettes. Subepicardial porcine coronary arterioles with diameter at full dilation and 60 mmHg ( D0) of 168 ± 10 (SE) μm were cannulated. Vessels treated with Nω-nitro-l-arginine (l-NNA) to block NO production and untreated vessels were pressurized at 60 mmHg for 3 days with and without flow. Endothelium-dependent dilation to 10−7M bradykinin was preserved in all groups. Tone was significantly less in vessels cultured under flow conditions in the last half of the culture period. Untreated and l-NNA-treated vessels regulated their diameter to yield shear stresses of 10.3 ± 2.1 and 14.0 ± 2.4 (SE) dyn/cm2, respectively (not significantly different). Without l-NNA, passive pressure-diameter curves at the end of the culture period revealed inward remodeling in the control group [to 92.3 ± 1.3% of D0(SE)] and no remodeling in the vessels cultured under flow conditions (100.2 ± 1.3% of D0); with l-NNA, the group subjected to flow showed inward remodeling (92.1 ± 2.5% of D0). We conclude that pressurized coronary resistance arteries could be maintained in culture for several days with flow. Vessels cultured under flow conditions remained more dilated when NO synthesis was blocked. Inward remodeling occurred in vessels cultured under no-flow conditions and was inhibited by flow-dependent NO synthesis.
Dimethylarginine dimethylaminohydrolase and endothelial dysfunction in failing hearts
Authors: Chen YingJie , Li Yunfang , Zhang Ping , Traverse Jay H. , Hou Mingxiao , Xu Xin , Kimoto Masumi , Bache Robert J.
Published: July 2005

Congestive heart failure (CHF) is associated with impaired endothelium-dependent nitric oxide (NO)-mediated vasodilation (endothelial dysfunction). We hypothesized that coronary endothelial dysfunction in CHF may be due in part to decreased dimethylarginine dimethylaminohydrolase (DDAH), the enzyme that degrades endogenous inhibitors of NO synthase (NOS), including asymmetric dimethylarginine. Coronary blood flow and the endothelium-dependent vasodilator response to acetylcholine were studied in dogs in which CHF was produced by rapid ventricular pacing for 4 wk. Coronary flow and myocardial O2consumption at rest and during treadmill exercise were decreased after development of CHF, and the vasodilator response to intracoronary acetylcholine (75 μg/min) was decreased by 39 ± 5%. DDAH activity and DDAH isoform 2 (DDAH-2) protein content were decreased by 53 ± 13% and 58 ± 14%, respectively, in hearts with CHF, whereas endothelial NOS and DDAH isoform 1 (DDAH-1) were increased. Caveolin-1 and protein arginine N-methyltransferase 1, the enzyme that produces asymmetric dimethylarginine, were unchanged. Immunohistochemical staining showed DDAH-1 strongly expressed in coronary endothelium and smooth muscle and in the sarcolemma of cardiac myocytes. In cultured human endothelial cells, DDAH-1 was uniformly distributed in the cytosol and nucleus, whereas DDAH-2 was found only in the cytosol. Decreased DDAH activity and DDAH-2 protein expression may cause accumulation of endogenous inhibitors of endothelial NOS, thereby contributing to endothelial dysfunction in the failing heart.