bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonrelativistic Lee model in three dimensional Riemannian manifolds
Authors: Erman Fatih , Turgut O. Teoman
Published: December 2007

In this work, we construct the nonrelativistic Lee model on some class of three dimensional Riemannian manifolds by following a novel approach introduced by S. G. Rajeev (e-print hep-th∕9902025). This approach together with the help of heat kernel allows us to perform the renormalization nonperturbatively and explicitly. For completeness, we show that the ground state energy is bounded from below for different classes of manifolds, using the upper bound estimates on the heat kernel. Finally, we apply a kind of mean field approximation to the model for compact and noncompact manifolds separately and discover that the ground state energy grows linearly with the number of bosons n.
Adsorption of gold on TiC(001): Au–C interactions and charge polarization
Authors: Rodriguez J. A. , Viñes F. , Illas F. , Liu P. , Takahashi Y. , Nakamura K.
Published: December 2007

High-resolution photoemission and first-principles density-functional slab calculations were used to study the adsorption of gold on a TiC(001) surface. A positive shift in the binding energy of the C 1s core level is observed after the deposition of Au on the metal carbide surface. The results of the density-functional calculations corroborate the formation of Au–C bonds. In general, the bond between Au and the TiC(001) surface exhibits very little ionic character, but there is a substantial polarization of electrons around Au that affects its chemical properties.
Isochoric heating in heterogeneous solid targets with ultrashort laser pulses
Authors: Sentoku Y. , Kemp A. J. , Presura R. , Bakeman M. S. , Cowan T. E.
Published: December 2007

We study ultrafast heating of thin plastic foils by intense laser irradiation theoretically using collisional two-dimensional particle-in-cell simulations. We find that the laser-generated hot electrons are confined laterally by self-generated resistive magnetic fields, heating the laser focal area beyond keV electron temperatures isochorically in a few picoseconds. Using this confinement one can excite shock waves that compress the plasma beyond solid density and achieve keV thermal plasmas before the plasma disassembles. Such shocks can be launched at material interfaces inside the target where jumps in the average ionization state and thus electron density lead to gigabar pressure. They propagate stably over picoseconds accompanied by multi-megagauss magnetic fields, and thus have a potential for various applications in high energy density physics.
Resistive stability of a plasma with runaway electrons
Authors: Helander P. , Grasso D. , Hastie R. J. , Perona A.
Published: December 2007

In tokamak disruptions the Ohmic current is often replaced by a current of runaway electrons, which is likely to be more peaked in the center of the discharge than the predisruption current. This raises the question of the resistive stability of the postdisruption plasma, where the equilibrium current is entirely carried by the runaway electrons while the cold (∼10eV) background plasma is relatively resistive. It is found that the linear properties of the classical tearing mode are essentially determined by the cold bulk plasma, and the growth rate is approximately the same as in a plasma without runaways but with the same current profile. The nonlinear saturation amplitude is different, however. In a symmetric plasma slab, the saturated island size is larger when the current is carried by runaway electrons than in the Ohmic case, and undergoes a nonlinear bifurcation when the stability index Δ′ exceeds a critical value.
Dielectric relaxation and electrical conductivity in ferroelectric ceramic/polymer composite based on modified lead titanate
Authors: Peláiz-Barranco A. , López-Noda R.
Published: December 2007

The dielectric relaxation and electrical conductivity behavior are studied in the ferroelectric ceramic/polymer composite (Pb0.88Sm0.08)(Ti0.99Mn0.01)O3/polyetherketoneketone 50/50 % vol considering the semiempirical complex Cole–Cole equation and the universal relaxation law. The contribution of conductive processes to the dielectric relaxation for the low frequency range is discussed considering the space charges. For higher frequency range, the dielectric relaxation is analyzed considering the oxygen concentration in the ceramic phase due to the Mn4+ to Mn2+ conversion, which takes places during the sintering process of the ceramic material. The activation energy values suggest the involvement of charge carriers’ motion in the dielectric relaxation process. The relaxation process is associated to the decay of the polarization in the oxygen defect-related dipoles due to their hopping conduction.
Determination of small amplitude perturbations for the electric permittivity from partial dynamic boundary measurements
Authors: Khelifi Abdessatar
Published: December 2007

The paper deals with reconstruction of small perturbation of the uniform isotropic complex electric permittivity from dynamic measurements of the tangential component of the magnetic field on the boundary (or a part of the boundary) of a domain. The method is based on derived asymptotic inverse Fourier transform of the perturbation in the complex permittivity. Through construction of appropriate test functions by a geometrical control method, we provide a rigorous derivation of the inverse Fourier transform of the perturbations in the electric permittivity as the leading order of an appropriate averaging of the partial dynamic boundary perturbations.
Analytical inversion of photothermal measurements: Independent determination of the thermal conductivity and diffusivity of a conductive layer deposited on an insulating substrate
Authors: Frétigny Christian , Roger Jean Paul , Reita Valérie , Fournier Danièle
Published: December 2007

The long distance behavior of the surface temperature wave in a thermoreflectance microscopy experiment is established for a conductive layer deposited on an insulating substrate. At large distance from the point source, heat is confined, so the amplitude decrease is lower than for a bulk sample. From the slopes which appear on the phase and on the log scale amplitude, a procedure is proposed to extract, separately, the thermal diffusivity and conductivity of the layer, taking into account data obtained at different modulation frequencies. Experimental results are presented which confirm the validity of the method.
Study on the crystallization by an electrical resistance measurement in Ge2Sb2Te5 and N-doped Ge2Sb2Te5 films
Authors: Hu D. Z. , Lu X. M. , Zhu J. S. , Yan F.
Published: December 2007

An electric resistance measurement was used to study the crystallization process of Ge2Sb2Te5 (GST) and N-doped Ge2Sb2Te5 (N-GST) films. The relation between conductivity and annealing time was investigated and the crystallization parameters were determined directly by resistance measurement during isothermal crystallization process in the amorphous GST and the N-GST films. The results show that the crystallization processes in both GST and N-GST films are layer by layer. Their conductivities satisfy the equation σ=σc−(σc−σa)exp(−ktn), at t>τ, where τ is a temperature-dependent time in the process of crystallization. The activation energy for crystallization of amorphous GST films was 2.11±0.18eV and the Avrami coefficient was between 2 to 4, in close agreement with previous studies using different techniques. After N doping the Avrami coefficient decreased, while the activation energy increased. The formation of a strain induced by the distortion of unit cell after N doping was used to explain the observed results.
Ferromagnetism in Cr substituted SrMoO3 system
Authors: Zhao B. C. , Sun Y. P. , Zhang S. B. , Song W. H. , Dai J. M.
Published: December 2007

Systematic studies of structural, magnetic, electric transport, and specific heat properties have been performed on lightly Cr-doped molybdates SrMo1−xCrxO3 (0⩽x⩽0.10). Based on the analysis of structural parameter variations, the valence state of the doped Cr ions in SrMo1−xCrxO3 system is suggested to be +2. Cr substitution as low as x=0.025 is sufficient to drive SrMo1−xCrxO3 system from the Pauli-paramagnetic state to a ferromagnetic state. The Curie temperature TC increases monotonically with increasing Cr-doping content. All samples exhibit metalliclike transport behavior in the whole studied temperature range except for the x=0.10 sample. The magnitude of the resistivity increases monotonically with increasing Cr-doping level. The evolution of the magnetic and resistive properties with Cr-doping content x may be related to the narrowed d-band width due to Cr substitution. In addition, the temperature dependence of specific heat for all samples has also been studied.
Improvement in threshold of InGaN∕GaN quantum-well lasers by p-type modulation doping
Authors: Huang Shyh-Jer , Yen Shun-Tung
Published: December 2007

The optical properties of modulation-doped InGaN∕GaN laser diodes are theoretically studied with the effects of electron spillover from quantum wells considered. We use a six-band model including the strain effect for calculating valence band states. The continuous subbands are treated by a dense discretization for the electrons spilling from the quantum wells. The calculation results show that the threshold current can be significantly reduced by p-type modulation doping around the wells but not by n-type doping, supposed that the layers are of a perfect quality and the impurity-induced defects are ignored. Also, the p-type modulation doping can make the threshold current more insensitive to the cavity loss compared with other cases. An optimized threshold current density can be achieved for single-quantum-well lasers by introducing p-type dopants. However, the dopant concentration is high and may be inaccessible. For double-quantum-well lasers an optimized low threshold current can be achieved with a slighter and practicable p-type doping level.
Kondo effect in a semiconductor quantum dot coupled to ferromagnetic electrodes
Authors: Hamaya K. , Kitabatake M. , Shibata K. , Jung M. , Kawamura M. , Hirakawa K. , Machida T. , Taniyama T. , Ishida S. , Arakawa Y.
Published: December 2007

Using a laterally fabricated quantum-dot (QD) spin-valve device, we experimentally study the Kondo effect in the electron transport through a semiconductor QD with an odd number of electrons (N). In a parallel magnetic configuration of the ferromagnetic electrodes, the Kondo resonance at N=3 splits clearly without external magnetic fields. With applying magnetic fields (B), the splitting is gradually reduced, and then the Kondo effect is almost restored at B=1.2T. This means that, in the Kondo regime, an inverse effective magnetic field of B∼1.2T can be applied to the QD in the parallel magnetic configuration of the ferromagnetic electrodes.
Stranski-Krastanow growth of tensile strained Si islands on Ge (001)
Authors: Pachinger D. , Groiss H. , Lichtenberger H. , Stangl J. , Hesser G. , Schäffler F.
Published: December 2007

Stranski-Krastanow island growth is demonstrated for tensile strained silicon epilayers on Ge (001) substrates over a wide range of growth temperatures. Small, Si-rich islands show sidewall faces near {1,1,10}, whereas larger islands are {113}-terminated truncated pyramids with an aspect ratio near 0.1. In contrast to compressively strained Ge on Si, we find for Si on Ge a significantly thicker wetting layer of >8 ML and coexistence of islands and dislocations.
Wavelength tuning the photonic band gap in chiral nematic liquid crystals using electrically commanded surfaces
Authors: Choi Su Seok , Morris Stephen M. , Coles Harry J. , Huck Wilhelm T. S.
Published: December 2007

In this letter, the authors demonstrate photonic band gap (PBG) tuning in chiral nematic liquid crystals using electrically commanded surfaces consisting of a ferroelectric liquid crystal. The electrically commanded surfaces generate a contraction of the pitch of the chiral nematic which is manifested as a blueshift of the PBG. Results are presented which demonstrate that tuning can be achieved by either varying the frequency or the amplitude of the electric field. The maximum shift observed for the long-wavelength band edge was 23nm for an electric field strength of 20Vμm−1 and a frequency of 800Hzto1kHz.
Size dependency of the elastic modulus of ZnO nanowires: Surface stress effect
Authors: Wang Guofeng , Li Xiaodong
Published: December 2007

Relation between the elastic modulus and the diameter (D) of ZnO nanowires was elucidated using a model with the calculated ZnO surface stresses as input. We predict for ZnO nanowires due to surface stress effect: (1) when D>20nm, the elastic modulus would be lower than the bulk modulus and decrease with the decreasing diameter, (2) when 20nm>D>2nm, the nanowires with a longer length and a wurtzite crystal structure could be mechanically unstable, and (3) when D<2nm, the elastic modulus would be higher than that of the bulk value and increase with a decrease in nanowire diameter.
X-ray spectroscopic application of Cr∕Sc periodic multilayers
Authors: Le Guen K. , Maury H. , André J.-M. , Jonnard P. , Hardouin A. , Delmotte F. , Ravet-Krill M.-F.
Published: December 2007

The use of Cr∕Sc multilayer interferential mirrors (MIMs) in optical systems such as x-ray microscopes or telescopes have been reported for the water window (between C K- and O K-absorption edges). However, their possibilities in spectroscopic application have never been described in the literature. The purpose of the paper is to report for the first time on the performances of Cr∕Sc MIMs as Bragg dispersive devices for the analysis in wavelength dispersive spectrometry of samples containing N or Sc atoms. The possibility to distinguish the chemical state of the emitting N or Sc atoms is evidenced by using Johan-type and double-crystal spectrometers.
Assessing the critical sizes for shear band formation in metallic glasses from molecular dynamics simulation
Authors: Li Qi-Kai , Li Mo
Published: December 2007

The size effect on the strength and fracture behavior of metallic glasses reported earlier by the authors is further examined in a mode I fracture from extensive molecular dynamics simulation using multimillion atoms and a method for atomic strain. In sharp contrast to the notch-free and notched samples, with small dimensions, in the large samples, shear bands easily initiate at the notch tips and grow into maturity. We identified two critical length scales for nucleating a shear band: the nucleation zone size d of about 10–20nm and the shear length ξ that is at least twice as large as d. The shape anisotropy of the critical nucleus described by the two length scales d and ξ may contribute to deformation anisotropy.
Control of mitotic exit by PP2A regulation of Cdc25C and Cdk1
Authors: Forester Craig M. , Maddox Jessica , Louis Justin V. , Goris Jozef , Virshup David M.
Published: December 2007

Inactivation of maturation-promoting factor [(MPF) Cdk1/Cyclin B] is a key event in the exit from mitosis. Although degradation of Cyclin B is important for MPF inactivation, recent studies indicate that Cdk1 phosphorylation and inactivation occur before Cyclin B degradation and, therefore, also may be important steps in the exit from mitosis. Cdk1 activity is controlled by the Cdc25C phosphatase, which is turned on at the G
2
/M transition to catalyze Cdk1 activation. PP2A:B56δ is a negative regulator of Cdc25C during interphase. We show here that PP2A:B56δ also regulates Cdc25C at mitosis. Failure of PP2A:B56δ to dephosphorylate Cdc25C at mitosis results in prolonged hyperphosphorylation and activation of Cdc25C, causing persistent dephosphorylation and, hence, activation of Cdk1. This constitutive activation of Cdc25C and Cdk1 leads to a delayed exit from mitosis. Consistent with Cdk1 as a major biological target of B56δ, stable knockdown and germ-line mouse KO of B56δ leads to compensatory transcriptional up-regulation of Wee1 kinase to oppose the Cdc25C activity and permit cell survival. These observations place PP2A:B56δ as a key upstream regulator of Cdk1 activity upon exit from mitosis.
A portrait of copy-number polymorphism in
Drosophila melanogaster
Authors: Dopman Erik B. , Hartl Daniel L.
Published: December 2007

Thomas Hunt Morgan and colleagues identified variation in gene copy number in
Drosophila
in the 1920s and 1930s and linked such variation to phenotypic differences [Bridges CB (1936)
Science
83:210]. Yet the extent of variation in the number of chromosomes, chromosomal regions, or gene copies, and the importance of this variation within species, remain poorly understood. Here, we focus on copy-number variation in
Drosophila melanogaster
. We characterize copy-number polymorphism (CNP) across genomic regions, and we contrast patterns to infer the evolutionary processes acting on this variation. Copy-number variation in
D. melanogaster
is nonrandomly distributed, presumably because of a mutational bias produced by tandem repeats or other mechanisms. Comparisons of coding and noncoding CNPs, however, reveal a strong effect of purifying selection in the removal of structural variation from functionally constrained regions. Most patterns of CNP in
D. melanogaster
suggest that negative selection and mutational biases are the primary agents responsible for shaping structural variation.
Bloodborne Pathogen Exposure Risk Among Surgeons in Sub-Saharan Africa
Authors: Phillips Elayne Kornblatt , Owusu-Ofori Alex , Jagger Janine
Published: December 2007

To document the frequency and circumstances of bloodborne pathogen exposures among surgeons in sub-Saharan Africa, we surveyed surgeons attending the 2006 Pan-African Association of Surgeons conference. During the previous year, surgeons sustained a mean of 3.1 percutaneous injuries, which were typically caused by suture needles. They sustained a mean of 4.1 exposures to blood and body fluid, predominantly from blood splashes to the eyes. Fewer than half of the respondents reported completion of hepatitis B vaccination, and postexposure prophylaxis for human immunodeficiency virus was widely available. Surgeons reported using hands-free passing and blunt suture needles. Non-fluid-resistant cotton gowns and masks were the barrier garments worn most frequently.
Effect of Communication Errors During Calls to an Antimicrobial Stewardship Program
Authors: Linkin Darren R. , Fishman Neil O. , Landis J. Richard , Barton Todd D. , Gluckman Steven , Kostman Jay , Metlay Joshua P.
Published: December 2007

Objective.

To determine how inaccurate communication of patient data by clinicians in telephone calls to the prior-approval antimicrobial stewardship program (ASP) staff affects the incidence of inappropriate antimicrobial recommendations made by ASP practitioners.

Design.

A retrospective cohort design was used. The accuracy of the patient data communicated was evaluated against patients' medical records to identify predetermined, clinically significant inaccuracies. Inappropriate antimicrobial recommendations were defined having been made if an expert panel unanimously rated the actual recommendations as inappropriate after reviewing vignettes derived from inpatients' medical records.

Setting.

The setting was an academic medical center with a prior-approval ASP.

Patients.

All inpatient subjects of ASP prior-approval calls were eligible for inclusion.

Results.

Of 200 ASP telephone calls, the panel agreed about whether or not antimicrobial recommendations were inappropriate for 163 calls (82%); these 163 calls were then used as the basis for further analyses. After controlling for confbunders, inaccurate communication was found to be associated with inappropriate antimicrobial recommendations (odds ratio [OR], of 2.2; P = .03). In secondary analyses of specific data types, only inaccuracies in microbiological data were associated with the study outcome (OR, 7.5; P = .002). The most common reason panelists gave for rating a recommendation as inappropriate was that antimicrobial therapy was not indicated.

Conclusions.

Inaccurate communication of patient data, particularly microbiological data, during prior-approval calls is associated with an increased risk of inappropriate antimicrobial recommendations from the ASP. Clinicians and ASP practitioners should work to confirm that critical data has been communicated accurately prior to use of that data in prescribing decisions.
Impact of Automatic Orders to Discontinue Vancomycin Therapy on Vancomycin Use in an Antimicrobial Stewardship Program
Authors: Connor Denise M. , Binkley Shawn , Fishman Neil O. , Gasink Leanne B. , Linkin Darren , Lautenbach Ebbing
Published: December 2007

We examined the possible unintended consequences of a 72-hour automatic order to discontinue vancomycin therapy in an antimicrobial stewardship program (ASP). Of 120 patients, 11 had vancomycin therapy discontinued at 72 hours without a call to the ASP, and 7 experienced a treatment interruption of 6-36 hours. All discontinuation of therapy was considered appropriate, and the 7 treatment interruptions did not have clear clinical consequences. Only one-third of patients had ASP stickers that warned of impending discontinuation of vancomycin therapy placed appropriately in the medical record.
Case-Control Study of Antibiotic Use and Subsequent Clostridium difficile–Associated Diarrhea in Hospitalized Patients
Authors: Baxter Roger , Ray G. Thomas , Fireman Bruce H.
Published: December 2007

Objective.

To determine which antibiotics increase or decrease the risk of Clostridium difficile-associated diarrhea (CDAD).

Design.

Retrospective case-control study.

Setting.

Nonprofit, integrated healthcare delivery system in Northern California.

Patients.

Study participants included patients with cases of hospital-acquired CDAD that occurred during the period from 1999 through 2005 (n = 1,142) and control patients (n = 3,351) matched for facility, calendar quarter during which hospitalization occurred, diagnosis related group for the index hospitalization, and length of hospital stay. All case and control patients had received antibiotics in the 60 days before the index date. For each antibiotic, the risk of CDAD was examined in relation to whether the patient received the antibiotic, after adjustment for use of other antibiotics, demographic characteristics, selected health conditions, and use of healthcare services.

Results.

The following antibiotics were associated with a significantly increased risk of acquiring CDAD: imipenem-cilastin (odds ratio [OR], 2.77), clindamycin (OR, 2.31), cefuroxime (OR, 2.16), moxifloxacin (OR, 1.88), ceftazidime (OR, 1.82), cefpodoxime (OR, 1.58), ceftizoxime (OR, 1.57), and ceftriaxone (OR, 1.49). Metronidazole and doxycycline were associated with a significantly reduced risk of CDAD (OR for metronidazole, 0.67; OR for doxycycline, 0.41). Other factors associated with an increased risk of CDAD were older age, longer hospital stays, use of proton pump inhibitors, prior gastrointestinal disease, and prior infection (not including C. difficile infection.)

Conclusions.

Some antibiotics appear to increase the risk of acquiring CDAD, notably clindamycin, third-generation cephalosporins, and carbapenems, whereas metronidazole and doxycycline appear to be protective, compared with other antibiotics.
Predictors of Mortality Among Patients With Community-Onset Infection Due to Extended-Spectrum β-Lactamase-Producing Escherichia coli in Thailand
Authors: Apisarnthanarak Anucha , Kiratisin Patarachai , Saifon Piyawan , Kitphati Rungrueng , Dejsirilert Surang , Mundy Linda M.
Published: December 2007

A matched case-control study was performed to identify predictors of mortality among patients (n = 46) with community-onset infections due to extended-spectrum β-lactamase-producing Escherichia coli in Thailand. The crude mortality rate was 30%. By multivariable analysis, community-onset bloodstream infection due to extended-spectrum β-lactamase-producing E. coli was the sole predictor of mortality (adjusted odds ratio, 41.3 [95% confidence interval, 4.3-69.4]; P = .001).
Influenza Vaccination Among Medical Residents in a Teaching Hospital
Authors: Bishburg Eliahu , Shah Monica , Mathis A. Scott
Published: December 2007

We assessed the rates of influenza vaccine acceptance and the reasons for acceptance or refusal among medical residents in different disciplines during the 2004-2005 influenza season. Rates varied among disciplines; emergency department residents had the lowest acceptance rate (24%). The perception of a low risk of contracting influenza was the most common reason reported for vaccine refusal.
Budget Impact Analysis of Rapid Screening for Staphylococcus aureus Colonization Among Patients Undergoing Elective Surgery in US Hospitals
Authors: Noskin Gary A. , Rubin Robert J. , Schentag Jerome J. , Kluytmans Jan , Hedblom Edwin C. , Jacobson Cassie , Smulders Maartje , Gemmen Eric , Bharmal Murtuza
Published: December 2007

Objective.

To evaluate the economic impact of performing rapid testing for Staphylococcus aureus colonization before admission for all inpatients who are scheduled to undergo elective surgery and providing subsequent decolonization therapy for those patients found to be colonized with S. aureus.

Methods.

A budget impact model that used probabilistic sensitivity analysis to account for the uncertainties in the input variables was developed. Primary input variables included the marginal effect of S. aureus infection on patient outcomes among patients who underwent elective surgery, patient demographic characteristics, the prevalence of nasal carriage of S. aureus, the sensitivity and specificity of the rapid diagnostic test for S. aureus colonization, the efficacy of decolonization therapy for nasal carriage of S. aureus, and cost data. Data sources for the input variables included the 2003 Nationwide Inpatient Sample data and the published literature.

Results.

In 2003, there were an estimated 7,181,484 patients admitted to US hospitals for elective surgery. Our analysis indicated preadmission testing and subsequent decolonization therapy for patients colonized with S. aureus would have produced a mean annual cost savings to US hospitals of $231,538,400 (95% confidence interval [CI], -$300 million to $1.3 billion). The mean annual number of hospital-days that could have been eliminated was estimated at 364,919 days (95% CI, 67,893-926,983 days), and a mean of 935 in-hospital deaths (95% CI, 88-3,691) could have been avoided per year. Sensitivity analysis indicated a 64.5% probability that there would be cost savings to US hospitals as a result of preadmission testing and subsequent decolonization therapy.

Conclusion.

The addition of preadmission testing and decolonization therapy to standard care would result in significant cost savings, even after accounting for variations in the model input values.
Predictive Factors for the Development of Central Line–Associated Bloodstream Infection Due to Gram-Negative Bacteria in Intensive Care Unit Patients After Surgery
Authors: Sreeramoju Pranavi V. , Tolentino Jocelyn , Garcia-Houchins Sylvia , Weber Stephen G.
Published: December 2007

Objectives.

To examine the relative proportions of central line-associated bloodstream infection (BSI) due to gram-negative bacteria and due to gram-positive bacteria among patients who had undergone surgery and patients who had not. The study also evaluated clinical predictive factors and unadjusted outcomes associated with central line-associated BSI caused by gram-negative bacteria in the postoperative period.

Design.

Observational, case-control study based on a retrospective review of medical records.

Setting.

University of Chicago Medical Center, a 500-bed tertiary care center located on Chicago's south side.

Patients.

Adult intensive care unit (ICU) patients who developed central line-associated BSI.

Results.

There were a total of 142 adult patients who met the Centers for Disease Control and Prevention National Nosocomial Infection Surveillance System definition for central line-associated BSI. Of those, 66 patients (46.5%) had infections due to gram-positive bacteria, 49 patients (34.5%) had infections due to gram-negative bacteria, 23 patients (16.2%) had infections due to yeast, and 4 patients (2.8%) had mixed infections. Patients who underwent surgery were more likely to develop central line-associated BSI due to gram-negative bacteria within 28 days of the surgery, compared with patients who had not had surgery recently (57.6% vs 27.3%; P = .002). On multivariable logistic regression analysis, diabetes mellitus (adjusted odds ratio [OR], 4.6 [95% CI, 1.2-18.1]; P = .03) and the presence of hypotension at the time of the first blood culture positive for a pathogen (adjusted OR, 9.8 [95% CI, 2.5-39.1]; P = .001 ) were found to be independently predictive of central line-associated BSI caused by gram-negative bacteria. Unadjusted outcomes were not different in the group with BSI due to gram-negative pathogens, compared to the group with BSI due to gram-positive pathogens.

Conclusions.

Clinicians caring for critically ill patients after surgery should be especially concerned about the possibility of central line-associated BSI caused by gram-negative pathogens. The presence of diabetes and hypotension appear to be significant associated factors.
Polyphyletic origin of toxic Pitohui birds suggests widespread occurrence of toxicity in corvoid birds
Authors: Jønsson Knud A , Bowie Rauri C.K , Norman Janette A , Christidis Les , Fjeldså Jon
Published: December 2007

Pitohui birds from New Guinea have been found to contain a toxin otherwise only found in neotropical poison arrow frogs. Pitohuis have been considered to be monophyletic and thus toxicity is thought to have evolved once in birds. Here, we show that Pitohuis, rather than being a tight-knit group, are polyphyletic and represent several lineages among the corvoid families of passerine birds. This finding demonstrates that the ability to be toxic is widespread among corvoid birds and suggests that additional members of this radiation, comprising more than 700 species, could prove to be toxic. It is postulated that toxic birds ingest the toxin through their insect diet and excrete it through the uropygial gland, from where it is applied to the skin and feathers. Thus, the ability to become toxic is most likely an ancestral condition but variation in diet determines the extent to which toxicity is expressed among corvoid birds. Variability in toxicity levels further suggests that the main function of the toxin is that of a deterrent against ectoparasites and bacterial infection rather than being a defence against predators as initially proposed.
Driving a hard bargain: sex ratio and male marriage success in a historical US population
Authors: Pollet Thomas V , Nettle Daniel
Published: December 2007

Evolutionary psychologists have documented a widespread female preference for men of high status and resources, and evidence from several populations suggests that this preference has real effects on marriage success. Here, we show that in the US population of 1910, socioeconomic status (SES) had a positive effect on men's chances of marrying. We also test a further prediction from the biological markets theory, namely that where the local sex ratio produces an oversupply of men, women will be able to drive a harder bargain. As the sex ratio of the states increases, the effect of SES on marriage success becomes stronger, indicating increased competition between men and an increased ability to choose on the part of women.
The effect of network mixing patterns on epidemic dynamics and the efficacy of disease contact tracing
Authors: Kiss Istvan Z , Green Darren M , Kao Rowland R
Published: December 2007

In networks, nodes may preferentially contact other nodes with similar (assortatively mixed) or dissimilar (disassortatively mixed) numbers of contacts. Different patterns of contact support different epidemic dynamics, potentially affecting the efficacy of control measures such as contact tracing, which aims to identify and isolate nodes with infectious contacts. We used stochastic simulations to investigate the effects of mixing patterns on epidemic dynamics and contact-tracing efficacy. For uncontrolled epidemics, outbreaks occur at lower infection rates for more assortatively mixed networks, with faster initial epidemic growth rate and shorter epidemic duration than for disassortatively mixed networks. Contact tracing performs better for assortative mixing where epidemic size is large and tracing rate low, but it performs better for disassortative mixing at higher contact rates. For assortatively mixed networks, disease spreads first to highly connected nodes, but this is balanced by contact tracing quickly identifying these same nodes. The converse is true for disassortative mixing, where both disease and tracing are less likely to target highly connected nodes. For small epidemics, contact tracing is more effective on disassortative networks due to the greater resilience of assortative networks to link removal. Multi-step contact tracing is more effective than single-step tracing for assortative mixing, but this effect is smaller for disassortatively mixed networks.
Evolution of aquatic insect behaviours across a gradient of disturbance predictability
Authors: Lytle David A , Bogan Michael T , Finn Debra S
Published: December 2007

Natural disturbance regimes—cycles of fire, flood, drought or other events—range from highly predictable (disturbances occur regularly in time or in concert with a proximate cue) to highly unpredictable. While theory predicts how populations should evolve under different degrees of disturbance predictability, there is little empirical evidence of how this occurs in nature. Here, we demonstrate local adaptation in populations of an aquatic insect occupying sites along a natural gradient of disturbance predictability, where predictability was defined as the ability of a proximate cue (rainfall) to signal a disturbance (flash flood). In controlled behavioural experiments, populations from predictable environments responded to rainfall events by quickly exiting the water and moving sufficiently far from the stream to escape flash floods. By contrast, populations from less predictable environments had longer response times and lower response rates, reflecting the uncertainty inherent to these environments. Analysis with signal detection theory showed that for 13 out of 15 populations, observed response times were an optimal compromise between the competing risks of abandoning versus remaining in the stream, mediated by the rainfall–flood correlation of the local environment. Our study provides the first demonstration that populations can evolve in response to differences in disturbance predictability, and provides evidence that populations can adapt to among-stream differences in flow regime.
International Trade and Growth Miracles: the Implications of Nonhomothetic Preferences
Authors: Mountford Andrew
Published: December 2007

If the rate of saving increases with income then a low per capita level of the capital stock may be self‐sustaining. In these circumstances international trade may allow an economy to quickly increase its per capita capital stock in a self‐reinforcing “growth miracle” process. A labor‐abundant economy trading with a capital‐abundant economy will see its wage rate rise relative to autarky. This rise in the wage rate also increases the savings rate and so raises the following period’s per capita capital stock. In this way a low‐income economy may exhibit large and permanent increases in its level of GDP per capita after opening its markets to international trade.
Imperfect Labor Mobility and Unemployment in a Dual Economy*
Authors: Wei Gu , Yabuuchi Shigemi
Published: December 2007

This paper examines the implications of imperfect labor mobility and unemployment in developing countries. We analyze the effects of wage subsidy policies, factor growth, and the change in labor mobility on unemployment and national income in an economy that is characterized by the existence of both imperfect labor mobility and urban unemployment.
Heat-Transfer Characteristics and Design Optimization for a Small-Sized Plate-Fin Heat Sink Array
Authors: Xu Gaowei , Cheng Yingjun , Luo Le
Published: December 2007

The heat-transfer characteristics of 128 small-sized plate-fin heat sinks in a supercomputer chassis are investigated with CFD simulation. The V-shaped curves of the chip temperature versus fin pitch and fin thickness are derived and a thermal resistance model is built to explore the profile and obtain the convective heat-transfer coefficient of the heat sinks. It turns out that the V-shaped profile arises from the joint action of the thermal conduction and convection of heat sink, which can be attributed to the intricacy of the dependencies of thermal resistances on either fin pitch or thickness. It can be further concluded that Biot criterion is applicable to estimate the Biot number of large-scale plate-fin heat sink but not applicable for the small-sized one. The convective heat-transfer coefficient is a complicated function of fin pitch and fin thickness. The empirical formulas of heat transfer are obtained and the fin pitch and fin thickness are optimized.
Non-invasive treatment of ST elevation myocardial infarction
Authors: Jones J B , Docherty A
Published: December 2007

There is good evidence that timely restoration of coronary blood flow in obstructed infarct related arteries is a significant determinant of both short and long term mortality and morbidity. This is irrespective of whether it is achieved using fibrinolytic therapy or percutaneous coronary intervention (PCI). Despite the clear advantages of primary PCI, it is thrombolysis that remains the main reperfusion strategy in the UK. Recent data have highlighted mortality benefits when antiplatelet treatment and anticoagulation are used as adjuncts to thrombolysis. Moreover, of those who receive thrombolysis, 60% proceed to coronary arteriography within 6 months of their index event. Recent studies have been published clarifying the timing of coronary arteriography in patients who receive thrombolysis as reperfusion therapy.
The risk of antimalarials in patients with renal failure
Authors: Thorogood N , Atwal S , Mills W , Jenner M , Lewis D A , Cavenagh J D , Agrawal S G
Published: December 2007

We present here a patient with end stage renal failure who received two weeks antimalarial prophylaxis at full dose leading to life threatening toxicity with severe acute megaloblastic anaemia, symptomatic pancytopenia and exfoliative dermatitis. Prompt recognition and treatment can rapidly reverse these fatal effects but more importantly, education of patients before travel is imperative in preventing such events.
Early structured core training of junior trainees in ophthalmology
Authors: Patel N , Zia R , Dewitd D , Morris S , Ionides A
Published: December 2007

The implementation of modernising medical careers (MMC) has resulted in some specialties being allocated very inexperienced trainees such as ophthalmology. We aim to describe the process of implementation of MMC and how it may affect the service provision in smaller specialities such as ophthalmology. A methodical approach in a district hospital setting was used to provide early core training to such trainees involving managerial support. The quality of service provided by newer trainees can be enhanced by providing early structured training during induction to create an atmosphere of enthusiasm and continued learning. This example can be used in other units and specialties.
FROM SEMANTICOBJECTS TO STRUCTURED NATURAL LANGUAGE
Authors: SHEU PHILLIP C-Y. , KITAZAWA ATSUSHI , ISHII CHIHIRO , KANEKO KENICHI , XIE FEI
Published: December 2007

This paper presents a structured natural language (SNL) based on an object-relational algebra that allows users pose database queries whose scope is much wider than that of the relational algebra. We also discuss how queries expressed in natural language (NL) may be translated into SNL using meta-information.
Regulation of Kruppel-like factor 4, 9, and 13 genes and the steroidogenic genes LDLR, StAR, and CYP11A in ovarian granulosa cells
Authors: Natesampillai Sekar , Kerkvliet Jason , Leung Peter C. K. , Veldhuis Johannes D.
Published: December 2007

Kruppel-like factors (KLFs) are important Sp1-like eukaryotic transcriptional proteins. The LDLR, StAR, and CYP11A genes exhibit GC-rich Sp1-like sites, which have the potential to bind KLFs in multiprotein complexes. We now report that KLF4, KLF9, and KLF13 transcripts are expressed in and regulate ovarian cells. KLF4 and 13, but not KLF9, mRNA expression was induced and then repressed over time ( P < 0.001). Combined LH and IGF-I stimulation increased KLF4 mRNA at 2 h ( P < 0.01), whereas LH decreased KLF13 mRNA at 6 h ( P < 0.05), and IGF-I reduced KLF13 at 24 h ( P < 0.01) compared with untreated control. KLF9 was not regulated by either hormone. Transient transfection of KLF4, KLF9, and KLF13 suppressed LDLR/luc, StAR/luc, and CYP11A/luc by 80–90% ( P < 0.001). Histone-deacetylase (HDAC) inhibitors stimulated LDLR/luc five- to sixfold and StAR/luc and CYP11A/luc activity twofold ( P < 0.001) and partially reversed suppression by all three KLFs ( P < 0.001). Deletion of the zinc finger domain of KLF13 abrogated repression of LDLR/luc. Lentiviral overexpression of the KLF13 gene suppressed LDLR mRNA ( P < 0.001) and CYP11A mRNA ( P = 0.003) but increased StAR mRNA ( P = 0.007). Collectively, these data suggest that KLFs may recruit inhibitory complexes containing HDAC corepressors, thereby repressing LDLR and CYP11A transcription. Conversely, KLF13 may recruit unknown coactivators or stabilize StAR mRNA, thereby explaining enhancement of in situ StAR gene expression. These data introduce new potent gonadal transregulators of genes encoding proteins that mediate sterol uptake and steroid biosynthesis.
The Functional TiO2-Biodegradable Plastic Composite Material Produced by HVOF Spraying Process
Authors: Bang Hee-Seon , Bang Han-Sur , Lee Yoon-Ki
Published: December 2007

Photocatalytic TiO2 coatings on bio-degradable plastic(polybutylene succinate: PBS) were prepared by HVOF spraying using three kinds of agglomerated powders (P200: 200 nm, P30: 30 nm, P7: 7 nm). The microstructures of the coatings were characterized
with SEM and XRD analysis, and the photocatalytic efficiency of the coatings was evaluated by photo degradation of gaseous acetaldehyde. For both the HVOF sprayed P200 and P30 coatings, high anatase ratio of 100% was achieved, regardless of the fuel gas pressure. On the
other hand, for the HVOF sprayed P7 coating, the anatase ratio decreased from 100% to 49.1% with increasing fuel gas pressure. This decrease may be attributed to the much higher susceptibility to heat of the 7 nm agglomerated powders than the 30 nm and 200 nm agglomerated powders.
In terms of the photocatalytic efficiency, HVOF sprayed P200 and P30 coatings seemed to outperform the P7 coatings because of their higher anatase ratios. However, the HVOF sprayed P7 coatings did not show photocatalytic activity possibly because
of the extremely small reaction surface area to the photo-catalytic activity and low anatase ratio. Therefore, the present study found that functional PBS plastic with photocatalytic performance could be produced by spraying of ceramics such as TiO2.
Positional Isomerization of Butene-2 over Nanoporous MCM-48 Catalysts
Authors: You Nansuk , Yim Jin-Heong , Lee Seong Jun , Lee Jae Ho , Park Young-Kwon , Jeon Jong-Ki
Published: December 2007

Positional isomerization of butene-2 to butene-1 was investigated over nanoporous MCM-48 catalysts. The effects of the method and the amount of aluminum incorporation into MCM-48 on the catalyst characteristics were studied, with respect to the butene-2 isomerization reaction. Incorporation
of aluminum into MCM-48 using a post-synthetic grafting method (P) or direct sol–gel method (D) increases the total acid amount due to the increase in the Lewis acidity level. From the results of butene-2 isomerization, the yield of butene-1 was increased although the selectivity of
butene-1 was decreased due to an increase of byproducts such as i-butene, cracked fraction, and C5+ hydrocarbons. This trend is nearly identical over both catalyst preparation methods; the effect of Al incorporation method on the butene-1 yield and the selectivity appeared negligible.
The maximum yield of butene-1 was 27.1 wt% by feeding pure butene-2 in the reaction condition as follows: a temperature of 450 °C, atmospheric pressure, and with the WHSV at 70 h−1.
Synthesis and Electrical Property of Indium Tin Oxide Nanofibers Using Electrospinning Method
Authors: Lee Young-In , Lee Kun-Jae , Kim Ki Do , Kim Hee Taik , Chang Young-Wook , Kang Shin-Choon , Choa Yong-Ho
Published: December 2007

In this study indium tin oxide (ITO) nanofibers were synthesized using an electrospinning method. The morphological properties of the ITO nanofibers were considered and their specific resistances were measured to determine their applicability as filler for a transparent conducting film.
ITO/PVP composite nanofibers were successfully obtained by electrospinning using a precursor solution containing indium nitrate, tin chloride, and poly(vinlypyrrolidone). After the heat treatment of ITO/PVP composite nanofibers at 600 °C and 1000 °C, ITO nanofibers with an average
diameter of about 168 nm and 165 nm were synthesized, respectively.
Surface Energy Heterogeneity and Heterogeneous Adsorption of Benzene on Double-Walled Carbon Nanotubes
Authors: Shim Wang-Geun , Lee Min-Joo , Kang Hyun-Chul , Kim Chan , Lee Jae-Wook , Kim Sang-Chai , Moon Hee
Published: December 2007

We examined the adsorption properties of double walled carbon nanotubes (DWCNTs) synthesized by using a catalytic chemical decomposition vapor method. To analyze the structural and energetical surface characteristics of the DWCNTs, nitrogen and benzene adsorption isotherms were measured.
The Toth isotherm equation was used to correlate the adsorption data and evaluate the thermodynamic properties such as Henry's constant and the adsorption second virial coefficient. The existence of heterogeneous surface in DWCNTs was confirmed by the analysis of pore size distribution, the
isosteric heat of adsorption, and the adsorption energy distribution determined for nitrogen and benzene.
Nanosized Hydroxyapatite Powder Synthesized from Eggshell and Phosphoric Acid
Authors: Lee Sang-Jin , Yoon Young-Soo , Lee Myung-Hyun , Oh Nam-Sik
Published: December 2007

The present research describes synthesis of highly sinterable, nano-sized hydroxyapatite (HAp) powders using a wet chemical route with recycled eggshell and phosphoric acid as calcium and phosphorous sources. The raw eggshell was easily turned to CaO by the calcining process, and phosphoric
acid was mixed with the calcined eggshell by the wet, ball-milling method. The crystalline development and microstructures of the synthesized powders and sintered samples were examined by X-ray diffractometry and scanning electron microscopy, respectively. The observed phases on the powder
synthesis process were dependent on the mixing ratio (wt%) of the calcined eggshell to phosphoric acid and the heating temperature. The ball-milled, nano-sized HAp powder, which has an average particle size of 70 nm, was fully densified at 1300 °C for 1h. The Ca/P ratio for stoichiometric
composition of HAp was controlled by adjustment of the mixing ratio.