bluuebunny/crossref_metadata_2025 huggingface dataset:
Opposing effects of PSD‐93 and PSD‐95 on long‐term potentiation and spike timing‐dependent plasticity
Authors: Carlisle Holly J. , Fink Ann E. , Grant Seth G. N. , O’Dell Thomas J.
Published: October 2008

The membrane‐associated guanylate kinases (MAGUKs) PSD‐95, PSD‐93 and SAP102 are thought to have crucial roles in both AMPA receptor trafficking and formation of NMDA receptor‐associated signalling complexes involved in synaptic plasticity. While PSD‐95, PSD‐93, and SAP102 appear to have similar roles in AMPA receptor trafficking, it is not known whether these MAGUKs also have functionally similar roles in synaptic plasticity. To explore this issue we examined several properties of basal synaptic transmission in the hippocampal CA1 region of PSD‐93 and PSD‐95 mutant mice and compared the ability of a number of different synaptic stimulation protocols to induce long‐term potentiation (LTP) and long‐term depression (LTD) in these mutants. We find that while both AMPA and NMDA receptor‐mediated synaptic transmission are normal in PSD‐93 mutants, PSD‐95 mutant mice exhibit clear deficits in AMPA receptor‐mediated transmission. Moreover, in contrast to the facilitation of LTP induction and disruption of LTD observed in PSD‐95 mutant mice, PSD‐93 mutant mice exhibit deficits in LTP and normal LTD. Our results suggest that PSD‐95 has a unique role in AMPA receptor trafficking at excitatory synapses in the hippocampus of adult mice and indicate that PSD‐93 and PSD‐95 have essentially opposite roles in LTP, perhaps because these MAGUKs form distinct NMDA receptor signalling complexes that differentially regulate the induction of LTP by different patterns of synaptic activity.
Rapid Depletion of Free Vancomycin in Medium in the Presence of β-Lactam Antibiotics and Growth Restoration in
Staphylococcus aureus
Strains with β-Lactam-Induced Vancomycin Resistance
Authors: Yanagisawa Chie , Hanaki Hideaki , Matsui Hidehito , Ikeda Shinsuke , Nakae Taiji , Sunakawa Keisuke
Published: October 2008

A class of methicillin-resistant
Staphylococcus aureus
strains shows vancomycin resistance in the presence of β-lactam antibiotics (β-lactam-induced VAN-resistant methicillin-resistant
S. aureus
[BIVR]). Two possible explanations may be offered: (i) vancomycin in culture medium is depleted, and (ii) the
d
-Ala-
d
-Ala terminal of the peptidoglycan network is replaced with
d
-Ala-
d
-lactate. We tested these hypotheses by quantifying free vancomycin in the medium through the course of cell growth and by PCR amplification of the
van
genes. Growth of the BIVR cells to an absorption level of ∼0.3 at 578 nm required about 24 h in the presence of vancomycin alone at the MIC (4.0 μg/ml). However, growth was achieved in only about 10 h when 1/1,000 to 1/2,000 the MIC of β-lactam antibiotic was added 2 h prior to the addition of vancomycin, suggesting that the β-lactams shortened the time to recovery from vancomycin-mediated growth inhibition. Free vancomycin in the culture medium decreased to 2.3 μg/ml in the first 8 h in the culture containing vancomycin alone, yet cell growth was undetectable. When the vancomycin concentration dropped below ∼1.5 μg/ml at 24 h, the cells began to grow. In the culture supplemented with the β-lactam 2 h prior to the addition of vancomycin, the drug concentration continuously dropped from 4 to 0.5 μg/ml in the first 8 h, and the cells began to grow at a vancomycin concentration of ∼1.7 μg/ml or at 4 h of incubation. The gene encoding the enzyme involved in
d
-Ala-
d
-lactate synthesis was undetectable. Based on these results, we concluded that BIVR is attributable mainly to a rapid depletion of vancomycin in the medium triggered or promoted by β-lactam antibiotics.
Widespread Dissemination of Aminoglycoside Resistance Genes
armA
and
rmtB
in
Klebsiella pneumoniae
Isolates in Taiwan Producing CTX-M-Type Extended-Spectrum β-Lactamases
Authors: Ma Ling , Lin Chi-Jan , Chen Jiun-Han , Fung Chang-Phone , Chang Feng-Yee , Lai Yiu-Kay , Lin Jung-Chung , Siu L. K.
Published: October 2008

Among 235 extended-spectrum β-lactamase-producing
Klebsiella pneumoniae
(ESBL) isolates collected from a nationwide surveillance performed in Taiwan, 102 (43.4%) were resistant to amikacin. Ninety-two of these 102 (90.2%) isolates were carrying CTX-M-type β-lactamases individually or concomitantly with SHV-type or CMY-2 β-lactamases. The
armA
and
rmtB
alleles were individually detected in 44 and 37 of these 92 isolates, respectively. One isolate contained both
armA
and
rmtB
. The coexistence of the
aac(6′)-Il
and
rmtB
genes was detected in three isolates. CTX-M-type β-lactamase genes belonging to either group 1 (CTX-M-3 and CTX-M-15) or group 9 (CTX-M-14) were found in all
armA-
or
rmtB
-bearing ESBL-producing
K. pneumoniae
isolates, and all were conjugatively transferable. All except one of the isolates bearing
armA
produced CTX-M enzymes of group 1, and the remaining isolate bearing
armA
produced a group 9 CTX-M-type β-lactamase. On the contrary, in the majority of
rmtB
carriers, the CTX-M-type β-lactamase belonged to group 9 (62.2%). Molecular typing revealed that the amikacin-resistant ESBL-producing
K. pneumoniae
isolates were epidemiologically unrelated, indicating that the acquisition of resistance was not through the spread of a resistant clone or a resistance plasmid. A tandem repeat or multiple copies of
bla
CTX-M-3
were found in some
armA
-bearing isolates. An IS
Ecp1
insert was found in all CTX-M ESBL-producing
K. pneumoniae
isolates carrying
armA
or
rmtB
. In conclusion, the concomitant presence of a 16S rRNA methylase gene (
armA
or
rmtB
) and
bla
CTX-M
among amikacin-resistant ESBL-producing
K. pneumoniae
isolates is widespread in Taiwan.
High Prevalence of Plasmid-Mediated Quinolone Resistance Determinants
qnr
,
aac(6
′
)
-
Ib-cr
, and
qepA
among Ceftiofur-Resistant
Enterobacteriaceae
Isolates from Companion and Food-Producing Animals
Authors: Ma Junying , Zeng Zhenling , Chen Zhangliu , Xu Xiaogang , Wang Xiaoying , Deng Yuting , Lü Dianhong , Huang Liangzong , Zhang Yunyuan , Liu Jianhua , Wang Minggui
Published: October 2008

Three kinds of plasmid-mediated quinolone resistance (PMQR) determinants have been discovered and have been shown to be widely distributed among clinical isolates:
qnr
genes,
aac(6
′
)-Ib-cr
, and
qepA
. Few data on the prevalence of these determinants in strains from animals are available. The presence of PMQR genes in isolates from animals was determined by PCR amplification and DNA sequencing. The production of extended-spectrum β-lactamases (ESBLs) and AmpC β-lactamases in the strains was detected, and their genotypes were determined. The genetic environment of PMQR determinants in selected plasmids was analyzed. All samples of ceftiofur-resistant (MICs ≥ 8 μg/ml) isolates of the family
Enterobacteriaceae
were selected from 36 companion animals and 65 food-producing animals in Guangdong Province, China, between November 2003 and April 2007, including 89
Escherichia coli
isolates, 9
Klebsiella pneumoniae
isolates, and isolates of three other genera. A total of 68.3% (69/101) of the isolates produced ESBLs and/or AmpC β-lactamases, mainly those of the CTX-M and CMY types. Of the 101 strains, PMQR determinants were present in 35 (34.7%) isolates, with
qnr, aac(6
′
)-Ib
-
cr
, and
qepA
detected alone or in combination in 8 (7.9%), 19 (18.8%), and 16 (15.8%) strains, respectively. The
qnr
genes detected included one
qnrB4
gene, four
qnrB6
genes, and three
qnrS1
genes. Five strains were positive for both
aac(6
′
)-Ib
-
cr
and
qepA
, while one strain was positive for
qnrS1, aac(6
′
)-Ib
-
cr
, and
qepA. qnrB6
was flanked by two copies of IS
CR1
with an intervening
dfr
gene downstream and
sul1
and
qacE
Δ
1
genes upstream. In another plasmid,
aac(6
′
)-Ib-cr
followed
intI1
and
arr-3
was downstream. PMQR determinants are highly prevalent in ceftiofur-resistant
Enterobacteriaceae
strains isolated from animals in China. This is the first report of the occurrence of PMQR determinants among isolates from companion animals.
Posaconazole Mono- or Combination Therapy for Treatment of Murine Zygomycosis
Authors: Ibrahim Ashraf S. , Gebremariam Teclegiorgis , Schwartz Julie A. , Edwards John E. , Spellberg Brad
Published: October 2008

We compared the efficacy of combination posaconazole-liposomal amphotericin B (LAmB) therapy to monotherapy with either drug in diabetic ketoacidotic or neutropenic mice with disseminated zygomycosis caused by
Rhizopus oryzae
. Combination therapy was no better than LAmB alone, and posaconazole monotherapy did not improve survival or reduce fungal burden versus placebo.
Abelson Tyrosine Kinase Facilitates
Salmonella enterica
Serovar Typhimurium Entry into Epithelial Cells
Authors: Ly Kim Thien , Casanova James E.
Published: October 2008

The intracellular gram-negative bacterial pathogen
Salmonella enterica
serovar Typhimurium gains entry into nonphagocytic cells by manipulating the assembly of the host actin cytoskeleton.
S. enterica
serovar Typhimurium entry requires a functional type III secretion system, a conduit through which bacterial effector proteins are directly translocated into the host cytosol. We and others have previously reported the enhancement of tyrosine kinase activities during
Salmonella
serovar Typhimurium infection; however, neither specific kinases nor their targets have been well characterized. In this study, we investigated the roles of the cellular Abelson tyrosine kinase (c-Abl) and the related protein Arg in the context of serovar Typhimurium infection. We found that bacterial internalization was inhibited by more than 70% in cells lacking both c-Abl and Arg and that treatment of wild-type cells with a pharmaceutical inhibitor of the c-Abl kinase, STI571 (imatinib), reduced serovar Typhimurium invasion efficiency to a similar extent. Bacterial infection led to enhanced phosphorylation of two previously identified c-Abl substrates, the adaptor protein CT10 regulator of kinase (CrkII) and the Abelson-interacting protein Abi1, a component of the WAVE2 complex. Furthermore, overexpression of the nonphosphorylatable form of CrkII resulted in decreased invasion. Taken together, these findings indicate that c-Abl is activated during
S. enterica
serovar Typhimurium infection and that its phosphorylation of multiple downstream targets is functionally important in bacterial internalization.
T-Cell Responses to the Trypanosome Variant Surface Glycoprotein Are Not Limited to Hypervariable Subregions
Authors: Dagenais Taylor R. , Demick Karen P. , Bangs James D. , Forest Katrina T. , Paulnock Donna M. , Mansfield John M.
Published: October 2008

Variable subregions within the variant surface glycoprotein (VSG) coat displayed by African trypanosomes are predicted sites for T- and B-cell recognition. Hypervariable subregion 1 (HV-1) is localized to an internal amphipathic alpha helix in VSG monomers and may have evolved due to selective pressure by host T-cell responses to epitopes within this subregion. The prediction of T-cell receptor-reactive sites and major histocompatibility complex class II binding motifs within the HV-1 subregion, coupled with the conservation of amino acid residues in other regions of the molecule sufficient to maintain secondary and tertiary VSG structure, prompted us to test the hypothesis that Th cells may preferentially recognize HV-1 subregion peptides. Thus, we examined the fine specificity of VSG-specific T-cell lines, T-cell hybridomas, and Th cells activated during infection. Our results demonstrate that T-cell epitopes are distributed throughout the N-terminal domain of VSG but are not clustered exclusively within HV-1 or other hypervariable subregions. In contrast, T-cell-reactive sites were not detected within the relatively conserved C-terminal domain of VSG. Overall, this study is the first to dissect the fine specificity of T-cell responses to the trypanosome VSG and suggests that evolution of a conserved HV-1 region may be unrelated to selective pressures exerted by host T-cell responses. This study also demonstrates that T cells do not recognize the relatively invariant C-terminal region of the VSG molecule during infection, suggesting that it could serve as a potential subunit vaccine to provide variant cross-specific immunity for African trypanosomiasis.
Identification of Meningococcal Genes Necessary for Colonization of Human Upper Airway Tissue
Authors: Exley Rachel M. , Sim Richard , Goodwin Linda , Winterbotham Megan , Schneider Muriel C. , Read Robert C. , Tang Christoph M.
Published: October 2008

Neisseria meningitidis
is an exclusively human pathogen that has evolved primarily to colonize the nasopharynx rather than to cause systemic disease. Colonization is the most frequent outcome following meningococcal infection and a prerequisite for invasive disease. The mechanism of colonization involves attachment of the organism to epithelial cells via bacterial type IV pili (Tfp), but subsequent events during colonization remain largely unknown. We analyzed 576
N. meningitidis
mutants for their capacity to colonize human nasopharyngeal tissue in an organ culture model to identify bacterial genes required for colonization. Eight colonization-defective mutants were isolated. Two mutants were unable to express Tfp and were defective for adhesion to epithelial cells, which is likely to be the basis of their attenuation in nasopharyngeal tissue. Three other mutants are predicted to have lost previously uncharacterized surface molecules, while the remaining mutants have transposon insertions in genes of unknown function. We have identified novel meningococcal colonization factors, and this should provide insights into the survival of this important pathogen in its natural habitat.
Evidence of a Role for Monocytes in Dissemination and Brain Invasion byCryptococcus neoformans
Authors: Charlier Caroline , Nielsen Kirsten , Daou Samira , Brigitte Madly , Chretien Fabrice , Dromer Françoise
Published: October 2008

The pathogenesis of cryptococcosis, including the events leading to the production of meningoencephalitis, is still largely unknown. Evidence of a transcellular passage ofCryptococcus neoformansacross the blood-brain barrier (BBB) and subsequent BBB disruption exists, but the paracellular passage of free yeasts and the role of monocytes in yeast dissemination and brain invasion (Trojan horse method) remain uncertain. We used our model of disseminated cryptococcosis, in which crossing of the BBB starts 6 h after intravenous inoculation, to study paracellular passage of the BBB. We prepared bone marrow-derived monocytes (BMDM) infected in vitro withC. neoformans(BMDM yeasts) and free yeasts and measured fungal loads in tissues. (i) Spleen and lung CFU were >2-fold higher in mice treated with BMDM yeasts than in those treated with free yeasts for 1 and 24 h (P< 0.05), while brain CFU were increased (3.9 times) only at 24 h (P< 0.05). (ii) By comparing the kinetics of brain invasion in naïve mice and in mice with preestablished cryptococcosis, we found that CFU were lower in the latter case, except at 6 h, when CFU from mice inoculated with BMDM yeasts were comparable to those measured in naïve mice and 2.5-fold higher than those in mice with preestablished cryptococcosis who were inoculated with free yeasts. (iii) Late phagocyte depletion obtained by clodronate injection reduced disease severity and lowered the fungal burden by 40% in all organs studied. These results provide evidence for Trojan horse crossing of the BBB byC. neoformans, together with mechanisms involving free yeasts, and overall for a role of phagocytes in fungal dissemination.
The Cytoplasmic Domain of Anthrax Toxin Receptor 1 Affects Binding of the Protective Antigen
Authors: Go Mandy Y. , Chow Edith M. C. , Mogridge Jeremy
Published: October 2008

The protective antigen (PA) component of anthrax toxin binds the I domain of the receptor ANTXR1. Integrin I domains convert between open and closed conformations that bind ligand with high and low affinities, respectively; this process is regulated by signaling from the cytoplasmic domains. To assess whether intracellular signals might influence the interaction between ANTXR1 and PA, we compared two splice variants of ANTXR1 that differ only in their cytoplasmic domains. We found that cells expressing ANTXR1 splice variant 1 (ANTXR1-sv1) bound markedly less PA than did cells expressing a similar level of the shorter splice variant ANTXR1-sv2. ANTXR1-sv1 but not ANTXR1-sv2 associated with the actin cytoskeleton, although disruption of the cytoskeleton did not affect binding of ANTXR-sv1 to PA. Introduction of a cytoplasmic domain missense mutation found in the related receptor ANTXR2 in a patient with juvenile hyaline fibromatosis impaired actin association and increased binding of PA to ANTXR1-sv1. These results suggest that ANTXR1 has two affinity states that may be modulated by cytoplasmic signals.
EnterotoxigenicEscherichia coliModulates Host Intestinal Cell Membrane Asymmetry and Metabolic Activity
Authors: Johnson Amber M. , Kaushik Radhey S. , Rotella Nicholas J. , Hardwidge Philip R.
Published: October 2008

EnterotoxigenicEscherichia coli(ETEC) is a common cause of travelers' and postweaning diarrhea in humans and swine, respectively. The extent to which ETEC damages host cells is unclear. Experiments are presented that probe the ability of porcine ETEC isolates to induce apoptosis and cell death in porcine intestinal epithelial cells. Quantification of host phosphatidylserine exposure following ETEC infection suggested that ETEC induced changes in plasma membrane asymmetry, independent of the expression of the heat-labile enterotoxin. Significant host cell death was not observed. ETEC infection also caused a drastic inhibition of host esterase activity, as measured by calcein fluorescence. While ETEC infection resulted in activation of host caspase 3, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling of DNA double-strand breakage, indicative of late stages of apoptosis, was not observed. Camptothecin-induced apoptosis markedly increased subsequent ETEC adherence. Transfer of cell-free supernatants from apoptotic cells to bacterial inocula prior to infection of naïve cells increased the transcriptional activity of the regulatory region upstream of the K88ac operon and promoted subsequent adherence to host cells.
Urinary 1-hydroxypyrene and malondialdehyde in male workers in Chinese restaurants
Authors: Pan C-H , Chan C-C , Huang Y-L , Wu K-Y
Published: October 2008

Objectives:

To assess internal dose and oxidative stress in male restaurant workers exposed to polycyclic aromatic hydrocarbons (PAHs) from cooking oil fumes (COFs) in Chinese restaurants.

Methods:

The study participants included 288 male restaurant workers (171 kitchen and 117 service staff) in Chinese restaurants in Taiwan. Airborne particulate PAHs were measured over 12 h on each of two consecutive work days and then identified using high performance liquid chromatography. Urinary 1-hydroxypyrene (1-OHP) measurements were used to indicate COF exposure, and urinary malondialdehyde (MDA) was adopted as an oxidative stress marker. Multiple regression models were used to assess the relationship between MDA and 1-OHP levels after adjusting for key personal covariates.

Results:

Summed particulate PAH levels in kitchens (median 23.9 ng/m3) were significantly higher than those in dining areas (median 4.9 ng/m3). For non-smoking kitchen staff, mean MDA and 1-OHP levels were 344.2 (SD 243.7) and 6.0 (SD 8.0) μmol/mol creatinine, respectively. These levels were significantly higher than those for non-smoking service staff, which were 244.2 (SD 164.4) and 2.4 (SD 4.3) μmol/mol creatinine, respectively. Urinary 1-OHP levels were significantly associated with work in kitchens (p<0.05). Furthermore, urinary MDA levels were significantly associated with urinary 1-OHP levels (p<0.001) and working hours per day (p<0.05).

Conclusions:

These findings indicate that urinary 1-OHP and MDA levels reflect occupational exposure to PAHs from COFs and oxidative stress in workers in Chinese restaurants.
The risk of asthma mortality with inhaled long acting β-agonists
Authors: Wijesinghe M , Perrin K , Harwood M , Weatherall M , Beasley R
Published: October 2008

This article reviews the available evidence as to whether inhaled long acting β-agonists (LABA) increase the risk of asthma mortality and considers the implications for the use of this treatment in the management of asthma. Randomised controlled trials suggest that LABAs prescribed as monotherapy may increase the risk of asthma death in certain circumstances, such as the unsupervised “off-label” use without concomitant inhaled corticosteroid (ICS) treatment in patients with unstable asthma. However, there is also evidence that the use of LABAs in conjunction with ICS treatment in adult asthma as recommended in current guidelines is not associated with an increased risk of asthma mortality. The only way in which a prescriber can ensure that a patient with asthma takes LABA treatment in conjunction with ICS is through a combination ICS/LABA product, an approach which may have additional therapeutic advantages. We propose that in the management of asthma, a case can now be made to limit the availability of LABAs to combination LABA/ICS therapy.
Primary care research and clinical practice: gastroenterology
Authors: Jones R
Published: October 2008

Gastrointestinal problems account for a significant proportion of general practitioners' workload, and gastrointestinal cancers, taken together, make up the largest group of malignancies. Approximately 10% of consultations in general practice in the UK are for gastrointestinal symptoms or problems, split roughly equally between the upper and lower gastrointestinal tract. Gastroenterology represents about 10% of the work of hospital specialists and the prescribing costs involved in the management of gastrointestinal disorders in general practice are around 14% of the drug budget. These disorders range from relatively minor and self limiting conditions such as acute gastritis and acute gastroenteritis, through the more significant, chronic digestive disorders such as gastro-oesophageal reflux disease (GORD), irritable bowel syndrome (IBS) and coeliac disease, to much more serious problems including inflammatory bowel disease (IBD) and upper gastrointestinal and colorectal cancer.
Explaining the social gradient in smoking cessation: it’s not in the trying, but in the succeeding: Table 1
Authors: Kotz D , West R
Published: October 2008

Objective:

Smokers from more deprived socioeconomic groups are less likely to become ex-smokers. This study examined how far this is attributable in England to a social gradient in quit attempts, use of aids to cessation and/or the success of quit attempts.

Design:

Cross-sectional household survey.

Setting:

England.

Participants:

6950 respondents aged 16+ who had smoked in the past year, of whom 2983 had tried to stop in the past year and 469 reported having stopped at the time of the survey.

Main outcome measures:

Reported attempts to stop smoking in the past year; the use of stop-smoking medications (nicotine replacement therapy, bupropion or varenicline); use of behavioural support offered by the National Health Service Stop Smoking Services; current smoking status.

Results:

There was a large difference in success rates of quit attempts: 20.4% in social grade AB versus 11.4% in social grade E of those who made attempts were still not smoking by the time of the survey (p<0.001). However, there was no difference across social grades in the rate of attempts to stop (42.7% in social grade AB to 41.3% in E), use of medications to aid cessation (46.7% of those making quit attempts in AB to 50.9% in E) or use of NHS Stop Smoking Services (7.0% of those making quit attempts in AB to 4.8% in E).

Conclusions:

Smokers in more deprived socioeconomic groups are just as likely as those in higher groups to try to stop and use aids to cessation but there is a strong gradient across socioeconomic groups in success, with those in the lowest group being half as likely to succeed compared with the highest. Determining the cause of, and counteracting, this gradient is paramount in reducing health inequalities.
TRILLION-ATOM MOLECULAR DYNAMICS BECOMES A REALITY
Authors: GERMANN TIMOTHY C. , KADAU KAI
Published: October 2008

By utilizing the molecular dynamics code SPaSM on Livermore's BlueGene/L architecture, consisting of 212 992 IBM PowerPC440 700 MHz processors, a molecular dynamics simulation was run with one trillion atoms. To demonstrate the practicality and future potential of such ultra large-scale simulations, the onset of the mechanical shear instability occurring in a system of Lennard-Jones particles arranged in a simple cubic lattice was simulated. The evolution of the instability was analyzed on-the-fly using the in-house developed massively parallel graphical object-rendering code MD_render.
CHAOS AND FRACTALS IN C–K MAP
Authors: WANG XING-YUAN , LIANG QING-YONG , MENG JUAN
Published: October 2008

The characteristic of the fixed points of the Carotid–Kundalini (C–K) map is investigated and the boundary equation of the first bifurcation of the C–K map in the parameter plane is given. Based on the studies of the phase graph, the power spectrum, the correlation dimension and the Lyapunov exponents, the paper reveals the general features of the C–K map transforming from regularity. Meanwhile, using the periodic scanning technology proposed by Welstead and Cromer, a series of Mandelbrot–Julia (M–J) sets of the complex C–K map are constructed. The symmetry of M–J set and the topological inflexibility of distributing of periodic region in the Mandelbrot set are investigated. By founding the whole portray of Julia sets based on Mandelbrot set qualitatively, we find out that Mandelbrot sets contain abundant information of structure of Julia sets.
STABILITY ANALYSIS FOR TRAFFIC FLOW WITH PERTURBATIONS
Authors: TANG TIE-QIAO , HUANG HAI-JUN , ZHANG YING , XU XIANG-YANG
Published: October 2008

In this paper, we use the speed-gradient model proposed by Jiang et al. [Transp. Res. B36, 405 (2002)] to study the effects that various perturbations have on the stability of traffic flow. Our numerical tests show that the effects of perturbations on the stability of traffic flow are related to the initial density, i.e., when the initial density is very low (ρ0≤ 0.02) or very high (ρ0> 0.08), any perturbation has little effect on the stability of traffic flow; when the initial density is relatively low (0.02 < ρ0≤ 0.04), small perturbations have little effect on the stability of traffic flow and large perturbations will have effect on it and produce local cluster; when the initial density is relatively high (0.04 < ρ0≤ 0.08), any perturbation will have great effect on the stability of traffic flow and produce stop-and-go traffic. These results are completely accordant with the real traffic, which just shows that the speed-gradient model can be used to perfectly explore the consequences caused by various perturbations.
STRUCTURAL EFFECTS ON SYNCHRONIZABILITY OF SCALE-FREE NETWORKS
Authors: LIU JIAN-GUO , ZHOU TAO , GUO QIANG , WANG BING-HONG
Published: October 2008

In this paper, we numerically investigate the structural characteristics that affect the synchronizability of coupled identical oscillators on scale-free networks. By using the edge-exchange method, we can change the network structure with degree sequence fixed. An optimal algorithm, namely Tabu Search, is applied, respectively, to enhance and weaken the synchronizability. The numerical results indicate that the synchronizability is most sensitive to the maximal betweenness. By tracking the optimization process, most previous works suggest that the synchonizability can be enhanced by reducing assortative coefficient and clustering coefficient; however, interestingly, our numerical simulations show that the depression of synchronizability also corresponds to the reduction process of those two coefficients.
EFFECTS OF LEARNING ACTIVITY ON COOPERATION IN EVOLUTIONARY PRISONER'S DILEMMA GAME
Authors: CHEN XIAOJIE , FU FENG , WANG LONG
Published: October 2008

We study the evolutionary Prisoner's Dilemma game under individual learning activity mechanism on small-world and scale-free networks, respectively. Each player updates its strategy with quenched learning rate which characterizes the strength of individual learning activity during the evolutionary process. Simulation results show that the mechanism of learning activity presents nontrivial phenomena on both the two networks: optimal intermediate levels of learning activity can promote or sustain cooperation. Specifically, there exists an interesting resonance-like manner in the evolutionary game when the intermediate level of learning activity promotes cooperation, and there exists a plateau for cooperation in the favorable moderate region of learning activity when the intermediate level of learning activity sustains cooperation. Moreover, these interesting phenomena are not sensitive to the two networks with other topological parameters. Our work can be helpful in reflecting the effects of individual learning mechanism on cooperative behavior in social systems.
MOLECULAR DYNAMICS APPROACH TO CORRELATION CLUSTERING
Authors: SUMI R. , NÉDA Z.
Published: October 2008

A many-body system with co-existing attractive and repulsive interactions is considered on a ring. The competing interactions lead to a frustration similar with the one existing in Correlation Clustering (CC). The optimal mechanical equilibrium of the system is searched by molecular dynamics simulations. As a function of the disorder quenched in the interactions, the system exhibits the phase-transition recently reported in CC. The simulated system can be considered as a continuous and efficient approach to the otherwise discrete, NP hard CC problem.
ON MAXIMAL NON-UNIVERSALLY CATENARIAN SUBRINGS
Authors: NASR MABROUK BEN , JARBOUI NOÔMEN
Published: October 2008

An integral domain R with field of fractions K is called a maximal non-1-catenarian subring of K if the polynomial ring in one variable, R[X] is not catenarian and for each proper intermediate ring T (that is each ring T such that R ⊂ T ⊆ K) T[X] is catenarian. The main purpose of this paper is to prove that the concept of maximal non-1-catenarian subrings and that of maximal non-universally catenarian subrings are equivalent.
POLYNOMIAL AND GROUP IDENTITIES IN ALTERNATIVE LOOP ALGEBRAS
Authors: GOODAIRE EDGAR G. , MILIES CÉSAR POLCINO
Published: October 2008

We investigate polynomial identities on an alternative loop algebra and group identities on its (Moufang) unit loop. An alternative loop ring always satisfies a polynomial identity, whereas whether or not a unit loop satisfies a group identity depends on factors such as characteristic and centrality of certain kinds of idempotents.
A CHARACTERIZATION OF THE COMMUTATIVE UNITAL RINGS WITH ONLY FINITELY MANY UNITAL SUBRINGS
Authors: DOBBS DAVID E. , PICAVET GABRIEL , PICAVET-L'HERMITTE MARTINE
Published: October 2008

A (commutative unital) ring is said to have FSP if it has only finitely many unital subrings. The singly generated rings that have FSP have been classified. Thus, a characterization of the rings satisfying FSP is obtained by proving that a ring R has FSP if and only if either R is finite or R = ℤ[t1, …, tn] ⊇ ℤ where ℤ[ti] has FSP for each i = 1, …, n. Also, the following characterization is given for the nontrivial ring direct products Πi ∈ I Ri that have FSP: I is finite, each Ri has FSP, and there is at most one i ∈ I such that Ri has characteristic 0.
REGULAR LOCAL ALGEBRAS OVER VALUATION DOMAINS: WEAK DIMENSION AND REGULAR SEQUENCES
Authors: KNAF HAGEN
Published: October 2008

A local ring O is called regular if every finitely generated ideal I ◃ O possesses finite projective dimension. In the article localizations O = Aq, q ∈ Spec A, of a finitely presented, flat algebra A over a Prüfer domain R are investigated with respect to regularity: this property of O is shown to be equivalent to the finiteness of the weak homological dimension wdim O. A formula to compute wdim O is provided. Furthermore regular sequences within the maximal ideal M ◃ O are studied: it is shown that regularity of O implies the existence of a maximal regular sequence of length wdim O. If q ∩ R has finite height, then this sequence can be chosen such that the radical of the ideal generated by its members equals M. As a consequence it is proved that if O is regular, then the factor ring O/(q ∩ R)O, which is noetherian, is Cohen–Macaulay. If in addition (q ∩ R)Rq ∩ R is not finitely generated, then O/(q ∩ R)O itself is regular.
GRÖBNER–SHIRSHOV BASIS FOR THE CHINESE MONOID
Authors: CHEN YUQUN , QIU JIANJUN
Published: October 2008

In this paper, a Gröbner–Shirshov basis for the Chinese monoid is obtained and an algorithm for the normal form of the Chinese monoid is given.
EXPLOSIVE INSTABILITY DUE TO 3-WAVE OR 4-WAVE MIXING, WITH OR WITHOUT DISSIPATION
Authors: SEGUR HARVEY
Published: October 2008

It is known that an "explosive instability" can occur when nonlinear waves propagate in certain media that admit 3-wave mixing. In that context, three resonantly interacting wavetrains all gain energy from a background source, and all blow up together, in finite time. A recent paper [17] showed that explosive instabilities can occur even in media that admit no 3-wave mixing. Instead, the instability is caused by 4-wave mixing, and results in four resonantly interacting wavetrains all blowing up in finite time. In both cases, the instability occurs in systems with no dissipation. This paper reviews the earlier work, and shows that adding a common form of dissipation to the system, with either 3-wave or 4-wave mixing, provides an effective threshold for blow-up. Only initial data that exceed the respective thresholds blow up in finite time.
NEW EXACT SOLUTIONS OF SPATIALLY AND TEMPORALLY VARYING REACTION-DIFFUSION EQUATIONS
Authors: JOSHI NALINI , MORRISON TEGAN
Published: October 2008

This paper considers reaction-diffusion equations from a new point of view, by including spatiotemporal dependence in the source terms. We show for the first time that solutions are given in terms of the classical Painlevé transcendents. We consider reaction-diffusion equations with cubic and quadratic source terms. A new feature of our analysis is that the coefficient functions are also solutions of differential equations, including the Painlevé equations. Special cases arise with elliptic functions as solutions. Additional solutions given in terms of equations that are not integrable are also considered. Solutions are constructed using a Lie symmetry approach.
Warm-water mollusc assemblages from northern Chile (Mejillones Peninsula): new evidence for permanent El Niño-like conditions during Pliocene warmth?
Authors: RAGAINI LUCA , DI CELMA CLAUDIO , CANTALAMESSA GINO
Published: October 2008

Although results have been controversial, understanding the tropical Pacific climatic state during the Pliocene warm interval (
c
. 4.5–3.0 Ma) is crucial if insight is to be gained into the dynamic processes of present and future global warming. In the multi-proxy effort to reconstruct ancient climates, a critical role can be played by palaeoclimatic evidence provided by the spatial and temporal distribution of temperature-sensitive marine molluscs. Shallow-water strata of the Mejillones Peninsula, northern Chile (23°S), contain dense faunal assemblages in which molluscs exclusive to, or characteristic of, Pliocene deposits (
Chlamys simpsoni
,
Chlamys vidali
,
Chorus blainvillei
,
Concholepas nodosa
,
Fusinus remondi
,
Herminespina mirabilis
) coexist with surprisingly abundant and varied populations of extant warm-water species (
Bulla punctulata
,
Cerithium stercusmuscarum
,
Olivella
sp.,
Turbo
cf.
fluctuosus
,
Anomia peruviana
,
Argopecten ventricosus
,
Donax peruvianus
,
Dosinia ponderosa
,
Mexicardia procera
,
Undulostrea megodon
), most of which have their current southern zoogeographical limit at 6°S. These tropical elements are reliable indicators of nearshore marine conditions and their abundant occurrence implies that sea surface temperatures (SST) along the northern Chile coast were at least 2 °C warmer in the mid-Pliocene than at present, and that these very different conditions lasted long enough to allow stable colonization of the area. Such a significantly warmer SST pattern strongly resembles general climatic conditions accompanying modern El Niño events, when warm tropical waters propagate southward along the western margin of South America; this supports the existence in this area of persistently El Niño-like conditions during the mid-Pliocene.
The mechanical relationship between strike-slip faults and salt diapirs in the Zagros fold–thrust belt
Authors: KOYI HEMIN A. , GHASEMI ABBAS , HESSAMI KHALED , DIETL CARLO
Published: October 2008

Analogue models are used to study the mechanical relationship between basement strike-slip faults and salt diapirs. Displacement along a strike-slip fault in 1
g
models resulted in extension along pre-existing jogs and the formation of oblique extensional faults, where reactive diapirs were triggered in some models. In the centrifuge models, prescribed cuts, simulating pre-existing structures, were reactivated during simple shear deformation of the models, resulting in formation of pull-apart basins, which were intruded by diapirs. The models show that because of the low ratio of salt to overburden thickness in the Zagros (0.15–0.35), it is unlikely that diapirs have formed solely, if at all, as a result of movement along basement strike-slip faults. Two mechanisms are suggested. First, pre-kinematic thin overburden and continuous movement along a releasing bend in the cover units may have triggered some of the diapirs in the Zagros, which were later downbuilt to their current geometry by additional sedimentation. Second, movement along the strike-slip faults (e.g. the Kazerun and Mangarak faults) induced oblique movement along NW–SE Zagros structures (folds or thrusts) resulting in the formation of pull-apart basins where diapirs were eventually intruded. Fault plane solution of shallow earthquakes supports the second scenario, which is also in agreement with previous interpretations that some of the salt diapirs associated with basement faults are younger than Zagros shortening and young southwestwards.
Provenance of the Tertiary sedimentary rocks of the Indo-Burman Ranges, Burma (Myanmar): Burman arc or Himalayan-derived?
Authors: ALLEN R. , NAJMAN Y. , CARTER A. , BARFOD D. , BICKLE M.J. , CHAPMAN H.J. , GARZANTI E. , VEZZOLI G. , ANDÒ S. , PARRISH R.R.
Published: October 2008

The Indo-Burman Ranges in western Myanmar extend along the Sunda Arc subduction zone and may be divided into a western portion of Neogene sedimentary rocks and an eastern portion of Palaeogene sedimentary rocks, separated by the Kaladan Fault. Both Himalayan and Burman sources have been proposed for these sediments. Our thermochronological analyses on detrital grains, isotopic analyses on bulk rock, and petrographic and heavy mineral data indicate that the Palaeogene Indo-Burman Ranges contain a significant component of arc-derived material, interpreted as derived from the Burmese portion of the Mesozoic–Tertiary arc to the east. And older crustal component is also identifiable, which may have been sourced from the Himalaya or the Burmese margin. By contrast, the Neogene Indo-Burman Ranges show dominant derivation from the Himalaya. A minor arc-derived component may have been sourced from the Trans-Himalaya, or recycled from the arc-derived Paleogene Indo-Burman Ranges.
Palaeoecological and possible evolutionary effects of early Namurian (Serpukhovian, Carboniferous) glacioeustatic cyclicity
Authors: STEPHENSON M.H. , MILLWARD D. , LENG M.J. , VANE C.H.
Published: October 2008

Early Namurian (Serpukhovian, Carboniferous), sedimentary cycles in the Throckley and Rowlands Gill boreholes, near Newcastle upon Tyne, UK, consist of fossiliferous limestones overlain by (usually unfossiliferous) black mudstone, followed by sandstones and often by thin coal seams. Sedimentological and regional geological evidence suggests that the largest are high-amplitude cycles, probably of glacioeustatic origin. δ
13
C (bulk organic matter) delineates marine and non-marine conditions because of the large difference between terrestrial and marine δ
13
C, and indicates that full marine salinity was only intermittent and resulted from glacioeustatic marine transgression superimposed on a background of inundation by freshwater from large rivers, which killed off the marine biota. Palynology suggests that plant groups, including ferns and putative pteridosperms, were affected by changing sea level, and that there is a theoretical possibility of connection between cyclicity and the first appearance of walchiacean conifer-like monosaccate pollen such as
Potonieisporites
. Long-term terrestrial and marine increasing δ
13
C (organic) may reflect the onset of major glaciation in Gondwana, as there is evidence to suggest that the two are coeval, but no specific mechanism can be suggested to link the trends.
Forecasting Methods in Crime and Justice
Authors: Berk Richard
Published: October 2008

Researchers who study crime and justice have been forecasting a variety of outcomes for nearly a century. Perhaps the most well known are forecasts of behavior after release from prison. Other examples include forecasts of prison populations and time trends in crime. However, it is very difficult to determine how accurate such forecasts have been because few forecasts have been properly evaluated. In the hope of improving crime and justice forecasts in the future, this article reviews modern forecasting methods and their applications to crime and justice questions. Among the key challenges for researchers are how best to arrive at useful forecasting models, taking the costs of forecasting errors into account, and estimating nonlinear relationships.
Convicting the Innocent
Authors: Gross Samuel R.
Published: October 2008

Almost everything we know about false convictions is based on exonerations in rape and murder cases, which together account for only 2% of felony convictions. Within that important but limited sphere we have learned a lot in the past 30 years; outside it, our ignorance is nearly complete. This review describes what we now know about convicting the innocent: estimates of the rate of false convictions among death sentences; common causes of false conviction for rape or murder; demographic and procedural predictors of such errors. It also explores some of the types of false convictions that almost never come to light—innocent defendants who plead guilty rather than go to trial, who receive comparatively light sentences, who are convicted of crimes that did not occur (as opposed to crimes committed by other people), who are sentenced in juvenile court—in fact, almost all innocent defendants who are convicted of any crimes other than rape or murder. Judging from what we can piece together, the vast majority of false convictions fall in these categories. They are commonplace events, inconspicuous mistakes in ordinary criminal investigations that never get anything close to the level of attention that sometimes leads to exoneration.
Women in the Legal Profession
Authors: Kay Fiona , Gorman Elizabeth
Published: October 2008

In recent years, the legal profession has undergone significant change, with rapidly rising numbers of women among its membership. Scholars of legal history, sociology, economics, organizational behavior, and law have examined various dimensions of the feminization of the legal profession. This review traces the parameters of integration and inequality in the careers of women and men in the contemporary legal profession. We document and assess the theoretical explanations of gender inequalities that persist across legal education, hiring, remuneration, promotions, and other professional opportunities in law. We also examine women's responses to their experiences and women's impact on the law and the profession.
Home Away from Home: Collaborative Research Networks and Interdisciplinary Socio-Legal Scholarship
Authors: Scheingold Stuart A.
Published: October 2008

Interdisciplinary research has long been suspect within the disciplines. Because the disciplines control recruitment, tenure, and promotion, it is difficult for interdisciplinary scholarship to gain traction in the academic world. Within socio-legal scholarship, the Law and Society Association has been instrumental in fostering interdisciplinary and, more recently, transnational research. The association's latest and certainly one of its most promising interdisciplinary and international initiatives is the creation of Collaborative Research Networks (CRNs). These CRNs, while of relatively recent origin, have already contributed impressively. On the one hand, they have established structures and processes that provide opportunities, training, and rewards for interdisciplinary scholars. On the other hand, the CRNs have demonstrated the multiplicity of ways in which socio-legal scholarship can bring all manner of research tools to bear on topics that cross disciplinary and national boundaries—incorporating the global and the local as well as the mediating forces and institutions betwixt and between.
The Countermajoritarian Difficulty: From Courts to Congress to Constitutional Order
Authors: Graber Mark A.
Published: October 2008

This review documents how scholarly concern with democratic deficits in American constitutionalism has shifted from the courts to electoral institutions. Prominent political scientists are increasingly rejecting the countermajoritarian difficulty as the proper framework for studying and evaluating judicial power. Political scientists, who study Congress and the presidency, however, have recently emphasized countermajoritarian difficulties with electoral institutions. Realistic normative appraisals of American political institutions, this emerging literature on constitutional politics in the United States maintains, should begin by postulating a set of democratic and constitutional goods, determine the extent to which American institutions as a whole are delivering those goods, and either explain how the political system as a whole might be redesigned to better deliver those goods or accept second-best constitutional goods that can actually be delivered by some attainable combination of political institutions.
An Embedded Reconfigurable IP Core with Variable Grain Logic Cell Architecture
Authors: Amagasaki Motoki , Yamaguchi Ryoichi , Koga Masahiro , Iida Masahiro , Sueyoshi Toshinori
Published: October 2008

Reconfigurable logic devices (RLDs) are classified as the fine-grained or coarse-grained type based on their basic logic cell architecture. In general, each architecture has its own advantage. Therefore, it is difficult to achieve a balance between the operation speed and implementation area in various applications. In the present paper, we propose a variable grain logic cell (VGLC) architecture, which consists of a 4-bit ripple carry adder with configuration memory bits and develop a technology mapping tool. The key feature of the VGLC architecture is that the variable granularity is a tradeoff between coarse-grained and fine-grained types required for the implementation arithmetic and random logic, respectively. Finally, we evaluate the proposed logic cell using the newly developed technology mapping tool, which improves logic depth by 31% and reduces the number of configuration data by 55% on average, as compared to the Virtex-4 logic cell architecture.
Synthesis, Sintering, and Electrical Properties of BaCe0.9−xZrxY0.1O3−δ
Authors: Ricote S. , Caboche G. , Estournes C. , Bonanos N.
Published: October 2008

BaCe0.9−xZrxY0.1O3−δ powders were synthesized by a solid‐state reaction. Different contents of cerium and zirconium were studied. Pellets were sintered using either conventional sintering in air at 1700∘C or the Spark Plasma Sintering (SPS) technique. The density of the samples sintered by SPS is much higher than by conventional sintering. Higher values of ionic conductivity were obtained for the SPS sample.