bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric anomalies in (BaxSr1−x)4Nd2Ti4Nb6O30 ceramics with various radius differences between A1- and A2-site ions
Authors: Zhu X. L. , Wu S. Y. , Chen X. M.
Published: October 2007

Dielectric response of tetragonal tungsten bronze dielectrics (BaxSr1−x)4Nd2Ti4Nb6O30 was investigated over a broad temperature and frequency range, and the obvious composition-dependent dielectric anomalies with respect to x value were discussed in detail in association with the radius differences between A1- and A2-site ions. With decreasing the magnitude of radius difference between A1- and A2-site ions, the normal ferroelectric peak above 400K became weaker, and two relaxor peaks at lower temperatures became obvious. The low- and high-temperature relaxor behaviors, which followed well the Vogel-Fulcher relationship, were associated with the polar clusters caused by the off-center Nb∕Ti displacements and the incommensurate tilting modulation, respectively.
Oriented nanotwins induced by electric current pulses in Cu–Zn alloy
Authors: Wang X. L. , Wang Y. B. , Wang Y. M. , Wang B. Q. , Guo J. D.
Published: October 2007

After applying an electrical current pulse (ECP) to samples of Cu–Zn alloy, {111} oriented nanotwins parallel to the ECP direction in α phase grains have been observed at ambient temperature. It seems that (a) these samples have heated up to a temperature much higher than the α to β phase transformation temperature and (b) new β nuclei on the {110} planes have formed in the original α phase. As a result, with the samples being rapidly cooled, these oriented nanotwins will be formed with the β to α martensitic transformation.
White light-emitting diodes based on a single InGaN emission layer
Authors: Wang X. H. , Jia H. Q. , Guo L. W. , Xing Z. G. , Wang Y. , Pei X. J. , Zhou J. M. , Chen H.
Published: October 2007

White light-emitting InGaN∕GaN diode with an InGaN underlying layer grown on the (0001) sapphire substrate was fabricated by low pressure metal-organic vapor phase epitaxy. The electroluminescence measurements show that the emitted white light is composed of blue and yellow lights, centered at around 440 and 570nm, respectively, for an injection current of 20mA. Cross-sectional transmission electron microscopy reveals that In-rich quantum dots were formed in InGaN wells due to phase separation of indium. It is suggested that the yellow and blue lights come from In-rich quantum dots and the low-indium regions, respectively, in InGaN quantum wells.
Submicron metal-semiconductor-metal diamond photodiodes toward improving the responsivity
Authors: Liao Meiyong , Alvarez Jose , Imura Masataka , Koide Yasuo
Published: October 2007

Metal-semiconductor-metal deep-ultraviolet detectors with electrode spacings from 0.14to10μm have been fabricated on a homoepitaxial diamond thin film grown on a Ib-type diamond substrate. A dramatic increase of the deep ultraviolet responsivity is observed when the electrode spacing is scaled down. The reduction in the electrode spacing enables the full depletion of the spacing at low biases, providing a higher responsivity without sacrification of the response speed.
A simple device of generating glow discharge plasma in atmospheric pressure argon
Authors: Li Xuechen , Dong Lifang , Zhao Na , Yin Zengqian , Fang Tongzhen , Wang Long
Published: October 2007

Atmospheric pressure glow discharge is realized in argon by using a plasma needle. With increasing the applied voltage, uniform plasma increases in scale from a small region near the needle tip to a plasma plume with a length of about 20mm. The discharge mechanism is discussed based on the light emission waveforms from the plasma. Optical emission spectroscopy is used to determine excited electron temperature and vibrational temperature, and the results indicate that the excited electron temperature and the molecular vibrational temperature are about 6000 and 2300K, respectively.
High-oxygen-pressure crystal growth of ferroelectric Bi4Ti3O12 single crystals
Authors: Yamamoto Katsuya , Kitanaka Yuuki , Suzuki Muneyasu , Miyayama Masaru , Noguchi Yuji , Moriyoshi Chikako , Kuroiwa Yoshihiro
Published: October 2007

We have investigated the effects of high-oxygen-pressure crystal growth of ferroelectric Bi4Ti3O12 on the polarization properties along the a(b) axis. Domain observations by piezoresponse force microscope demonstrate that a small remanent polarization (Pr) for the crystals grown at 0.02MPa is attributed to the clamping of 90° domain walls by oxygen vacancies. The vacancy formation of Bi and O during crystal growth at high temperatures is suppressed at a higher oxygen pressure, leading to a larger Pr of 47μC∕cm2 for the crystals grown at 1MPa oxygen. High-oxygen-pressure sintering is proposed to be effective for obtaining Bi4Ti3O12-based devices with enhanced polarization properties.
Ba
Fe
12
O
19
thin films grown at the atomic scale from BaFe2O4 and α-Fe2O3 targets
Authors: Geiler A. L. , Yoon S. D. , Chen Y. , Chinnasamy C. N. , Chen Z. , Geiler M. , Harris V. G. , Vittoria C.
Published: October 2007

Hexagonal barium ferrite (BaFe12O19) thin films were grown at the atomic scale by alternating target laser ablation deposition (ATLAD) of orthorhombic BaFe2O4 and rhombohedral α-Fe2O3 on ⟨00l⟩ Al2O3 substrates. Crystallographic, magnetic, and microwave properties of the ATLAD films were determined to be comparable with single crystal quality bulk and films of BaFe12O19 produced by other techniques. The ability to deposit high quality hexagonal ferrite thin films by utilizing multiple targets of different chemical compositions in the deposition routine provides unique opportunities to control the ionic distribution in the unit cell of this important class of ferrite materials.
The metal-insulator transition in VO2 studied using terahertz apertureless near-field microscopy
Authors: Zhan Hui , Astley Victoria , Hvasta Michael , Deibel Jason A. , Mittleman Daniel M. , Lim Yong-Sik
Published: October 2007

We have studied the metal-insulator transition in a vanadium dioxide (VO2) thin film using terahertz apertureless near-field optical microscopy. We observe a variation of the terahertz amplitude due to the phase transition induced by an applied voltage across the sample. The change of the terahertz signal is related to the abrupt change of the conductivity of the VO2 film at the metal-insulator transition. The subwavelength spatial resolution of this near-field microscopy makes it possible to detect signatures of micron-scale metallic domains in inhomogeneous VO2 thin films.
Carbon fiber-based cathodes for magnetically insulated transmission line oscillator operation
Authors: Liu Lie , Li Limin , Zhang Xiaoping , Wen Jianchun , Wan Hong , Zhong Huihuang
Published: October 2007

We report experimental results of carbon fiber cathodes for the magnetically insulated transmission line oscillator (MILO). The fabrication process of carbon fiber cathodes is presented. In experiments employing a 500kV, 100ns high-voltage pulsed accelerator, microwave generation in the C band was obtained with ∼900MW peak power and ∼20ns pulse width at about 4.5% efficiency. The MILO operation exhibited high stability by using carbon fiber cathodes. These results show that carbon fiber cathodes can offer promising applications for high performance MILOs.
Laser-induced fluorescence measurements in an inductively coupled plasma reactor
Authors: Jacobs Brett , Gekelman Walter , Pribyl Pat , Barnes Michael , Kilgore Michael
Published: October 2007

The authors report on laser-induced fluorescence (LIF) measurements of ion velocity distribution functions made in an inductively coupled plasma reactor with a pulsed plasma source. Vertical and radial velocities have been measured at thousands of spatial locations within a plane, and the LIF data have been calibrated to a 96GHz microwave interferometer. The ions are observed to approach the Bohm velocity and the inferred electric potential within the presheath agrees well with theory. A two-dimensional flow pattern of the ion velocity above the substrate is presented.
Straight Lines, ‘Uncurved Lines’, and Helmholtz's ‘Great Circles on the Celestial Sphere’
Authors: Rogers Brian , Brecher Kenneth
Published: October 2007

Helmholtz's famous pincushioned chessboard figure has been used to make the point that straight lines in the world are not always perceived as straight and, conversely, that curved lines in the world can sometimes be seen as straight. However, there is little agreement as to the cause of these perceptual errors. Some authors have attributed the errors to the shape of the retina, or the amount of cortex devoted to the processing of images falling on different parts of the retina, while others have taken the effects to indicate that visual space itself is curved. Helmholtz himself claimed that the ‘uncurved lines on the visual globe’ corresponded to ‘direction circles’ defined as those arcs described by the line of fixation when the eye moves according to Listing's law. Careful re-reading of Helmholtz together with some additional observations lead us to the conclusion that two other factors are also involved in the effect: (i) a lack of information about the distance of peripherally viewed objects and (ii) the preference of the visual system for seeing the pincushion squares as similar in size.
Switchable DNA interfaces for the highly sensitive detection of label-free DNA targets
Authors: Rant Ulrich , Arinaga Kenji , Scherer Simon , Pringsheim Erika , Fujita Shozo , Yokoyama Naoki , Tornow Marc , Abstreiter Gerhard
Published: October 2007

We report a method to detect label-free oligonucleotide targets. The conformation of surface-tethered probe nucleic acids is modulated by alternating electric fields, which cause the molecules to extend away from or fold onto the biased surface. Binding (hybridization) of targets to the single-stranded probes results in a pronounced enhancement of the layer-height modulation amplitude, monitored optically in real time. The method features an exceptional detection limit of <3 × 10
8
bound targets per cm
2
sensor area. Single base-pair mismatches in the sequences of DNA complements may readily be identified; moreover, binding kinetics and binding affinities can be determined with high accuracy. When driving the DNA to oscillate at frequencies in the kHz regime, distinct switching kinetics are revealed for single- and double-stranded DNA. Molecular dynamics are used to identify the binding state of molecules according to their characteristic kinetic fingerprints by using a chip-compatible detection format.
Potential for hydrogen production with inducible chloroplast gene expression in
Chlamydomonas
Authors: Surzycki Raymond , Cournac Laurent , Peltier Gilles , Rochaix Jean-David
Published: October 2007

An inducible chloroplast gene expression system was developed in
Chlamydomonas reinhardtii
by taking advantage of the properties of the copper-sensitive cytochrome
c
6
promoter and of the nucleus-encoded Nac2 chloroplast protein. This protein is specifically required for the stable accumulation of the chloroplast
psbD
RNA and acts on its 5′ UTR. A construct containing the
Nac2
coding sequence fused to the cytochrome
c
6
promoter was introduced into the
nac2-26
mutant strain deficient in
Nac2
. In this transformant,
psbD
is expressed in copper-depleted but not in copper-replete medium. Because
psbD
encodes the D2 reaction center polypeptide of photosystem II (PSII), the repression of
psbD
leads to the loss of PSII. We have tested this system for hydrogen production. Upon addition of copper to cells pregrown in copper-deficient medium, PSII levels declined to a level at which oxygen consumption by respiration exceeded oxygen evolution by PSII. The resulting anaerobic conditions led to the induction of hydrogenase activity. Because the
Cyc6
promoter is also induced under anaerobic conditions, this system opens possibilities for sustained cycling hydrogen production. Moreover, this inducible gene expression system is applicable to any chloroplast gene by replacing its 5′ UTR with the
psbD
5′ UTR in the same genetic background. To make these strains phototrophic, the 5′ UTR of the
psbD
gene was replaced by the
petA
5′ UTR. As an example, we show that the reporter gene
aadA
driven by the
psbD
5′ UTR confers resistance to spectinomycin in the absence of copper and sensitivity in its presence in the culture medium.
GTPase acceleration as the rate-limiting step in
Arabidopsis
G protein-coupled sugar signaling
Authors: Johnston Christopher A. , Taylor J. Philip , Gao Yajun , Kimple Adam J. , Grigston Jeffrey C. , Chen Jin-Gui , Siderovski David P. , Jones Alan M. , Willard Francis S.
Published: October 2007

Heterotrimeric G protein signaling is important for cell-proliferative and glucose-sensing signal transduction pathways in the model plant organism
Arabidopsis thaliana
. AtRGS1 is a seven-transmembrane, RGS domain-containing protein that is a putative membrane receptor for
d
-glucose. Here we show, by using FRET, that
d
-glucose alters the interaction between the AtGPA1 and AtRGS1
in vivo
. AtGPA1 is a unique heterotrimeric G protein α subunit that is constitutively GTP-bound given its high spontaneous nucleotide exchange coupled with slow GTP hydrolysis. Analysis of a point mutation in AtRGS1 that abrogates GTPase-accelerating activity demonstrates that the regulation of AtGPA1 GTP hydrolysis mediates sugar signal transduction during
Arabidopsis
development, in contrast to animals where nucleotide exchange is the limiting step in the heterotrimeric G protein nucleotide cycle.
Invasion, stress, and spinal arthritis in cane toads
Authors: Brown Gregory P. , Shilton Cathy , Phillips Benjamin L. , Shine Richard
Published: October 2007

The impact of invasive species on biodiversity has attracted considerable study, but impacts of the invasion process on the invaders themselves remain less clear. Invading species encounter conditions different from those in their ancestral habitats and are subject to intense selection for rapid dispersal. The end result may be significant stress on individual organisms, with consequent health problems. Our studies on invasive cane toads in Australia reveal severe spinal arthritis in ≈10% of large adult toads, associated with the same factors (large body size, frequent movement, and relatively long legs) that have enabled toads to invade so rapidly across the Australian tropics.
Modulators of the structural dynamics of the retinoid X receptor to reveal receptor function
Authors: Nahoum Virginie , Pérez Efrén , Germain Pierre , Rodrı́guez-Barrios Fátima , Manzo Fabio , Kammerer Sabrina , Lemaire Geraldine , Hirsch Oliver , Royer Catherine A. , Gronemeyer Hinrich , de Lera Angel R. , Bourguet William
Published: October 2007

Retinoid X receptors (RXRα, -β, and -γ) occupy a central position in the nuclear receptor superfamily, because they form heterodimers with many other family members and hence are involved in the control of a variety of (patho)physiologic processes. Selective RXR ligands, referred to as rexinoids, are already used or are being developed for cancer therapy and have promise for the treatment of metabolic diseases. However, important side effects remain associated with existing rexinoids. Here we describe the rational design and functional characterization of a spectrum of RXR modulators ranging from partial to pure antagonists and demonstrate their utility as tools to probe the implication of RXRs in cell biological phenomena. One of these ligands renders RXR activity particularly sensitive to coactivator levels and has the potential to act as a cell-specific RXR modulator. A combination of crystallographic and fluorescence anisotropy studies reveals the molecular details accounting for the agonist-to-antagonist transition and provides direct experimental evidence for a correlation between the pharmacological activity of a ligand and its impact on the structural dynamics of the activation helix H12. Using RXR and its cognate ligands as a model system, our correlative analysis of 3D structures and dynamic data provides an original view on ligand actions and enables the establishment of mechanistic concepts, which will aid in the development of selective nuclear receptor modulators.
Identification of functional paralog shift mutations: Conversion of
Escherichia coli
malate dehydrogenase to a lactate dehydrogenase
Authors: Yin Yifeng , Kirsch Jack F.
Published: October 2007

Five positions in the
Escherichia coli
malate dehydrogenase (eMDH) sequence, which distinguish MDH from lactate dehydrogenase (LDH) activity, were identified through a combination of Venn diagrams constructed from whole genomic data and from unbiased representative sequences from terminal clades. Incorporation of the five changes in eMDH sufficed to convert the enzyme from one with (
k
cat
/
K
m
pyruvate
)/(
k
cat
/
K
m
oxaloacetate
) = 6.1 × 10
−9
to one with that ratio = 28. The substrate specificity was thus changed by a factor of 4.6 × 10
9
. The
k
cat
/
K
m
pyruvate
value for the pentamutant (eMDH I12V/R81Q/M85E/G210A/V214I) is 3,500 M
−1
·s
−1
, which is ≈1/1,000 of the values found for typical wild-type LDHs. The procedure isolates an intersection of “strong forcing sets” that should prove to be of general use in switching paralog function.
On the Reality (and Diversity) of Objective Colors: How Color-Qualia Space Is a Map of Reflectance-Profile Space
Authors: Churchland Paul
Published: October 2007

How, if at all, does the internal structure of human phenomenological color space map onto the internal structure of objective reflectance-profile space, in such a fashion as to provide a useful and accurate representation of that objective feature space? A prominent argument (due to Hardin, among others) proposes to eliminate colors as real, objective properties of objects, on grounds that nothing in the external world (and especially not surface-reflectance-profiles) answers to the well-known and quite determinate internal structure of human phenomenological color space. The present paper proposes a novel way to construe the objective space of possible reflectance profiles so that (1) its internal structure becomes evident, and (2) that structure's homomorphism with the internal structure of human phenomenological color space becomes obvious. The path is thus reopened to salvage the objective reality of colors, in the same way that we preserved the objective reality of such features as temperature, pitch, and sourness—by identifying them with some objective feature recognized in modern physical theory.
Computer Simulation: The Cooperation between Experimenting and Modeling
Authors: Lenhard Johannes
Published: October 2007

The goal of the present article is to contribute to the epistemology and methodology of computer simulations. The central thesis is that the process of simulation modeling takes the form of an explorative cooperation between experimenting and modeling. This characteristic mode of modeling turns simulations into autonomous mediators in a specific way; namely, it makes it possible for the phenomena and the data to exert a direct influence on the model. The argumentation will be illustrated by a case study of the general circulation models of meteorology, the major simulation models in climate research.
Changing Epidemiology ofClostridium difficile-Associated Disease in Children
Authors: Benson Lacey , Song Xiaoyan , Campos Joseph , Singh Nalini
Published: October 2007

Objective.

To determine temporal trends in the incidence rate forClostridium difficile-associated disease (CDAD) in a pediatric patient population.

Methods.

We performed an observational, retrospective cohort study that included children who visited or were admitted to Children's National Medical Center during the period from July 2001 through June 2006. The CDAD incidence rates were determined and examined for changes over time using the Poisson regression method.

Results.

A total of 513 patients whose stool specimens tested positive forC. difficiletoxin were identified. Of these patients, 61% were children aged 2 years or older. The proportion of patients with CDAD in this age group has steadily increased from 46% in 2001 to 64% in 2006. Largely as a result of an increasing number of cases of community-associated CDAD, the incidence of CDAD increased significantly in the outpatient setting, particularly in the emergency department (1.18 cases per 1,000 visits in 2001 vs 2.47 cases per 1,000 visits in 2006;P= .02). The incidence among inpatients decreased during the study period (1.024 cases per 1,000 patient-days in 2001 vs 0.680 cases per 1,000 patient-days in 2006;P= .004). In the neonatal intensive care unit,C. difficile toxinwas detected in stool specimens collected from 22 patients aged from 15 days to 6 months.

Conclusion.

This study revealed a steady increase in the number of patients seen in the emergency department with community-acquired CDAD. Findings from this study suggest that the characteristics of CDAD in children—a population that has not been considered to be at high risk for this disease in the past—are changing. Further investigations are warranted to explore deviations from the established burdens of the disease and patient risk factors.
Skin, Soft Tissue, Bone, and Joint Infections in Hospitalized Patients: Epidemiology and Microbiological, Clinical, and Economic Outcomes
Authors: Lipsky Benjamin A. , Weigelt John A. , Gupta Vikas , Killian Aaron , Peng Michael M.
Published: October 2007

Background.

Infections involving skin, soft tissue, bone, or joint (SSTBJ) are common and often require hospitalization. There are currently few published studies on the epidemiology and clinical and economic outcomes of these infections, whether acquired in the community or healthcare setting, in a large population.

Objective.

To characterize outcomes of culture-proven SSTBJ infection in hospitalized patients, using information from a large database.

Design.

We identified patients hospitalized in 134 institutions during 2002-2003 for whom specific International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes and a culture-positive SSTBJ specimen were recorded. Patients were classified into 4 clinical groups based on the type and clinical severity of infection. Patients in each group were further classified on the basis of whether their infection was community acquired or healthcare associated and whether it was complicated or uncomplicated.

Results.

We identified 12,506 patients with culture-positive infections and categorized them as having cellulitis (37.3%), osteomyelitis or septic arthritis (22.4%), surgical wound infection (26.1%), device-associated or prosthesis infection (7.2%), or other SSTBJ infection (6.9%). Monomicrobial infection was reported for 59% of patients, 54.6% of whom had Staphylococcus aureus as the etiologic agent. Of all S. aureus isolates recovered, 1,121 (28.0%) of 4,007 were resistant to methicillin. Healthcare-associated infections accounted for 27.2% of cases and were associated with a significantly greater mortality rate, a longer length of stay, and greater hospital charges, compared with community-acquired infections. Patients with a complicated infection (78.4%) had a significantly greater mortality rate, a longer length of stay, and greater hospital charges, compared with patients with an uncomplicated infection.

Conclusions.

SSTBJ infections are frequent among hospitalized patients. S. aureus caused infection in more than 50% of the patients studied, and 28.0% of the S. aureus isolates recovered were resistant to methicillin. Healthcare-associated and complicated infections are associated with a significantly higher mortality rate and more prolonged and expensive hospitalizations. These findings could assist in projects to revise current management strategies in order to optimize outcomes while restraining costs.
Case-Control Study of Surgical Site Infections Associated With Pacemakers and Implantable Cardioverter-Defibrillators
Authors: Marschall Jonas , Hopkins-Broyles Diane , Jones Marilyn , Fraser Victoria J. , Warren David K.
Published: October 2007

Objective.

In 2000, the rate of surgical site infections (SSIs) associated with pacemaker and implantable cardioverter-defibrillator (ICD) procedures performed in the cardiothoracic operating rooms of hospital A was 16% (19 of 116 procedures resulted in infections). This study investigates risks for SSI associated with these procedures in the cardiothoracic operating room.

Design.

Unmatched 1: 3 case-control study performed over a 12-month period among patients who had undergone implantation of a pacemaker and/or ICD. A standardized observation scrutinized infection control practices in the area where the procedures were performed.

Setting.

The cardiothoracic operating rooms of hospital A, which belongs to a hospital consortium in the midwestern United States.

Patients.

Patients with SSI were identified as case patients. Control patients were chosen from the group of uninfected patients who had procedures performed during the same period as case patients.

Results.

A total of 19 SSIs associated with pacemaker and ICD procedures were retrospectively identified among the patients who underwent procedures in these cardiothoracic operating rooms. Culture samples were obtained from 7 patients; 2 yielded coagulase-negativeStaphylococcuson culture, 2 yieldedStaphylococcus aureus, 1 yieldedSerratia marcescens, and 2 showed no growth. In the case-control study, age, race, sex, diabetes mellitus, smoking history, timing of antibiotic therapy, and hair removal did not differ significantly between case patients and control patients. Case patients were more likely to have an abdominal device in place (odds ratio [OR], 5.5 [95% confidence interval {CI}, 1.6-19.3];P= .006) and less likely to have received a new implant (OR 0.3 [95% CI, 0.1-0.8];P= .02) or to have had new leads placed (OR, 0.2 [95% CI, 0.1-0.6];P= .003).

Conclusions.

Abdominal placement of implanted devices was associated with occurrence of an SSI after pacemaker and/or ICD procedures.
Infection Control Policies and Practices for Iowa Long-Term Care Facility Residents With Clostridium difficile Infection
Authors: Quinn Laura K. , Chen Yiyi , Herwaldt Loreen A.
Published: October 2007

Objective.

To identify infection control policies and practices used by Iowa long-term care facilities (LTCFs) for residents with Clostridium difficile infection or C. difficile-associated diarrhea and to assess use of antimicrobial agents.

Design.

Survey.

Setting.

LTCFs in Iowa that responded between March 25, 2005 (ie, when surveys were mailed), and July 2005.

Results.

Of the 418 LTCFs in Iowa, 263 (62.9%) responded. Most facilities (94.3%) reported that they accept persons known to have C. difficile infection. Few LTCFs reported that clusters of C. difficile infection had been identified. However, only 111 facilities (42.2%) had a protocol to identify residents with C. difficile infection, and most (77.5%) did not test for C. difficile unless a resident had severe diarrhea. Only 58.5% of the facilities placed residents with C. difficile infection in private rooms, and 60.9% cohorted residents infected with C. difficile with other residents with C. difficile colonization or infection. Only 66 facilities (25.1%) have a program to control the use of antimicrobial agents. Staff could use alcohol-based hand gel products after contact with residents known to have C. difficile infection (in 188 facilities [71.5%]) or diarrhea (in 173 [65.8%]). However, the survey did not ask whether the staff used alcohol-based products instead of soap and water.

Conclusions.

C. difficile is present in Iowa LTCFs, but many C. difficile infections probably remain undiagnosed. Staff in LTCFs should be educated about this organism so that they can implement appropriate testing and preventive strategies.
Where Have All the Theories Gone?
Authors: Morrison Margaret
Published: October 2007

Although the recent emphasis on models in philosophy of science has been an important development, the consequence has been a shift away from more traditional notions of theory. Because the semantic view defines theories as families of models and because much of the literature on “scientific” modeling has emphasized various degrees of independence from theory, little attention has been paid to the role that theory has in articulating scientific knowledge. This paper is the beginning of what I hope will be a redress of the imbalance. I begin with a discussion of some of the difficulties faced by various formulations of the semantic view not only with respect to their account of models but also with their definition of a theory. From there I go on to articulate reasons why a notion of theory is necessary for capturing the structure of scientific knowledge and how one might go about formulating such a notion in terms of different levels of representation and explanation. The context for my discussion is the BCS account of superconductivity, a ‘theory’ that was, and still is, sometimes referred to as a `model'. BCS provides a nice focus for the discussion because it illuminates various features of the theory/model relationship that seem to require a robust notion of theory that is not easily captured by the semantic account.
On Bayesian Measures of Evidential Support: Theoretical and Empirical Issues
Authors: Crupi Vincenzo , Tentori Katya , Gonzalez Michel
Published: October 2007

Epistemologists and philosophers of science have often attempted to express formally the impact of a piece of evidence on the credibility of a hypothesis. In this paper we will focus on the Bayesian approach to evidential support. We will propose a new formal treatment of the notion of degree of confirmation and we will argue that it overcomes some limitations of the currently available approaches on two grounds: (i) a theoretical analysis of the confirmation relation seen as an extension of logical deduction and (ii) an empirical comparison of competing measures in an experimental inquiry concerning inductive reasoning in a probabilistic setting.
Healthcare Workers' Knowledge and Attitudes About Pertussis and Pertussis Vaccination
Authors: Goins William P. , Schaffner William , Edwards Kathryn M. , Talbot Thomas R.
Published: October 2007

Objective.

To determine knowledge and attitudes about pertussis and pertussis vaccination among healthcare workers (HCWs).

Design.

Self-administered, Web-based survey.

Setting.

Tertiary-care academic medical center.

Participants.

Medical center employees who participated in direct patient care were recruited to complete the survey through institutional e-mail.

Results.

Of 14,893 potentially eligible employees, 1,819 (12%) completed the survey. Most respondents (87%) did not plan to receive the pertussis vaccine. Intent to receive vaccination (which included recent history of vaccination) was associated with the following 4 factors: receipt of a physician recommendation for vaccination (odds ratio [OR], 9.01), awareness of Centers for Disease Control and Prevention recommendations for pertussis vaccination for HCWs (OR, 6.89), receipt of encouragement to be vaccinated from a coworker (OR, 4.72), the belief that HCWs may spread pertussis to patients and family (OR, 1.80). Two factors were negatively associated with intent to receive vaccination: the presence of children in the HCW's home (OR, 0.69) and employment as a nurse (OR, 0.59). Reasons cited by those who did not intend to receive vaccination included lack of a personal recommendation for vaccination (78%), receipt of vaccination as a child (51%), and perception that there was no significant risk for contracting pertussis (38%).

Conclusions.

Of the HCWs surveyed, only 13% intended to receive the pertussis vaccine. A perceived lack of recommendation for vaccination and inaccurate conceptions about pertussis and pertussis vaccination were cited as reasons HCWs did not intend to be vaccinated. Institutional pertussis vaccination campaigns should focus on the risks of healthcare-associated pertussis and new recommendations for pertussis vaccination.
Impact of Contact and Droplet Precautions on the Incidence of Hospital-Acquired Methicillin-Resistant Staphylococcus aureus Infection
Authors: Mangini Ed , Segal-Maurer Sorana , Burns Janice , Avicolli Annette , Urban Carl , Mariano Noriel , Grenner Louise , Rosenberg Carl , Rahal James J.
Published: October 2007

Objective.

To evaluate the efficacy of contact and droplet precautions in reducing the incidence of hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections.

Design.

Before-after study.

Setting.

A 439-bed, university-affiliated community hospital.

Methods.

To identify inpatients infected or colonized with MRSA, we conducted surveillance of S. aureus isolates recovered from clinical culture and processed by the hospital's clinical microbiology laboratory. We then reviewed patient records for all individuals from whom MRSA was recovered. The rates of hospital-acquired MRSA infection were tabulated for each area where patients received nursing care. After a baseline period, contact and droplet precautions were implemented in all intensive care units (ICUs). Reductions in the incidence of hospital-acquired MRSA infection in ICUs led to the implementation of contact precautions in non-ICU patient care areas (hereafter, “non-ICU areas”), as well. Droplet precautions were discontinued. An analysis comparing the rates of hospital-acquired MRSA infection during different intervention periods was performed.

Results.

The combined baseline rate of hospital-acquired MRSA infection was 10.0 infections per 1,000 patient-days in the medical ICU (MICU) and surgical ICU (SICU) and 0.7 infections per 1,000 patient-days in other ICUs. Following the implementation of contact and droplet precautions, combined rates of hospital-acquired MRSA infection in the MICU and SICU decreased to 4.3 infections per 1,000 patient-days (95% confidence interval [CI], 0.17-0.97; P = .03). There was no significant change in hospital-acquired MRSA infection rates in other ICUs. After the discontinuation of droplet precautions, the combined rate in the MICU and SICU decreased further to 2.5 infections per 1,000 patient-days. This finding was not significant (P = .43). In the non-ICU areas that had a high incidence of hospital-acquired MRSA infection, the rate prior to implementation of contact precautions was 1.3 infections per 1,000 patient-days. After the implementation of contact precautions, the rate in these areas decreased to 0.9 infections per 1,000 patient-days (95% CI, 0.47-0.94; P = .02).

Conclusion.

The implementation of contact precautions significantly decreased the rate of hospital-acquired MRSA infection, and discontinuation of droplet precautions in the ICUs led to a further reduction. Additional studies evaluating specific infection control strategies are needed.
Outcome ofEscherichia coliand/orKlebsiellaBloodstream Infection in Children With Central Venous Catheters
Authors: Buckley Jessica , Coffin Susan E. , Lautenbach Ebbing , Prasad Priya , Chu Jaclyn , Goyal Monika , Zaoutis Theoklis E.
Published: October 2007

We conducted a retrospective cohort study of children with catheter-associated bloodstream infections (BSIs) due toEscherichia coliand/orKlebsiella. Risk factors for poor outcome (ie, death or recurrence of infection) were receipt of mechanical ventilation (adjusted odds ratio [aOR], 4.6 [95% confidence interval {CI}, 1.39-16.30]) and receipt of total parenteral nutrition (aOR, 3.5 [95% CI, 1.1-10.8]). A significant proportion of children with catheter-associated BSI were treated successfully without catheter removal.
Epidemiologic, Clinical, and Economic Evaluation of an Outbreak of Clonal Multidrug-ResistantAcinetobacter baumanniiInfection in a Surgical Intensive Care Unit
Authors: Young Lisa S. , Sabel Allison L. , Price Connie S.
Published: October 2007

Objectives.

To determine risk factors for acquisition of multidrug-resistant (MDR)Acinetobacter baumanniiinfection during an outbreak, to describe the clinical manifestations of infection, and to ascertain the cost of infection.

Design.

Case-control study.

Setting.

Surgical intensive care unit in a 400-bed urban teaching hospital and level 1 trauma center.

Patients.

Case patients received a diagnosis of infection due toA. baumanniiisolates with a unique pattern of drug resistance (ie, susceptible to imipenem, variably susceptible to aminoglycosides, and resistant to all other antibiotics) between December 1, 2004, and August 31, 2005. Case patients were matched 1 : 1 with concurrently hospitalized control patients. Isolates' genetic relatedness was established by pulsed-field gel electrophoresis.

Results.

Sixty-seven patients met the inclusion criteria. Case and control patients were similar with respect to age, duration of hospitalization, and Charlson comorbidity score. MDRA. baumanniiinfections included ventilator-associated pneumonia (in 56.7% of patients), bacteremia (in 25.4%), postoperative wound infections (in 25.4%), central venous catheter-associated infections (in 20.9%), and urinary tract infections (in 10.4%). Conditional multiple logistic regression was used to determine statistically significant risk factors on the basis of results from the bivariate analyses. The duration of hospitalization and healthcare charges were modeled by multiple linear regression. Significant risk factors included higher Acute Physiology and Chronic Health Evaluation II score (odds ratio [OR], 1.1 per point increase;P= .06), duration of intubation (OR, 1.4 per day intubated;P<.01), exposure to bronchoscopy (OR, 22.7;P= .03), presence of chronic pulmonary disease (OR, 77.7;P= .02), receipt of fluconazole (OR, 73.3;P<.01), and receipt of levofloxacin (OR, 11.5;P= .02). Case patients had a mean of $60,913 in attributable excess patient charges and a mean of 13 excess hospital days.

Interventions.

Infection control measures included the following: limitations on the performance of pulsatile lavage wound debridement, the removal of items with upholstered surfaces, and the implementation of contact isolation for patients with suspected MDRA. baumanniiinfection.

Conclusions.

This large outbreak of infection due to clonal MDRA. baumanniicaused significant morbidity and expense. Aerosolization of MDRA. baumanniiduring pulsatile lavage debridement of infected wounds and during the management of respiratory secretions from colonized and infected patients may promote widespread environmental contamination. Multifaceted infection control interventions were associated with a decrease in the number of MDRA. baumanniiisolates recovered from patients.
Factors Associated With Critical-Care Healthcare Workers' Adherence to Recommended Barrier Precautions During the Toronto Severe Acute Respiratory Syndrome Outbreak
Authors: Shigayeva A. , Green K. , Raboud J. M. , Henry B. , Simor A. E. , Vearncombe M. , Zoutman D. , Loeb M. , McGeer A. ,   SARS Hospital Investigation Team
Published: October 2007

Objective.

To assess factors associated with adherence to recommended barrier precautions among healthcare workers (HCWs) providing care to critically ill patients with severe acute respiratory syndrome (SARS).

Setting.

Fifteen acute care hospitals in Ontario, Canada

Design.

Retrospective cohort study.

Patients.

All patients with SARS who required intubation during the Toronto SARS outbreak in 2003.

Participants.

HCWS who provided care to or entered the room of a SARS patient during the period from 24 hours before intubation until 4 hours after intubation.

Methods.

Standardized interviews were conducted with eligible HCWs to assess their interactions with the SARS patient, their use of barrier precautions, their practices for removing personal protective equipment, and the infection control training they received.

Results.

Of 879 eligible HCWs, 795 (90%) participated. In multivariate analysis, the following predictors of consistent adherence to recommended barrier precautions were identified: recognition of the patient as a SARS case (odds ratio [OR], 2.5 [95% confidence interval {CI}, 1.5-4.5); recent infection control training (OR for interactive training, 2.7 [95% CI, 1.7-4.4]; OR for passive training, 1.7 [95% CI, 1.0-3.0]), and working in a SARS unit (OR, 4.0 [95% CI, 1.8-8.9]) or intensive care unit (OR, 4.3 [95% CI, 2.0-9.0]). Two factors were associated with significantly lower rates of consistent adherence: the provision of care for patients with higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores (OR for score APACHE II of 20 or greater, 0.4 [95% CI, 0.28-0.68]) and work on shifts that required more frequent room entry (OR for 6 or more entries per shift, 0.5 [95% CI, 0.32-0.86]).

Conclusions.

There were significant deficits in knowledge about self-protection that were partially corrected by education programs during the SARS outbreak. HCWs' adherence to self-protection guidelines was most closely associated with whether they provided care to patients who had received a definite diagnosis of SARS.
Risk of Clostridium difficile-Associated Disease Among Patients Receiving Proton-Pump Inhibitors in a Quebec Medical Intensive Care Unit
Authors: Beaulieu Mathieu , Williamson David , Pichette Gilbert , Lachaine Jean
Published: October 2007

Our study was conducted to determine whether use of gastric acid-suppressive agents increased the risk of Clostridium difficile-associated disease (CDAD) in a medical intensive care unit of one of the first hospitals to be threatened by the current CDAD epidemic in Quebec, Canada. Our findings suggest that efforts to determine risk factors for CDAD should focus on other areas, such as older age and antibiotic use.
Epidemiology of Multidrug-Resistant Bacteria in Patients With Long Hospital Stays
Authors: Buke Cagri , Armand-Lefevre Laurence , Lolom Isabelle , Guerinot Waafa , Deblangy Claude , Ruimy Raymond , Andremont Antoine , Lucet Jean-Christophe
Published: October 2007

Objective.

To determine rates of colonization with multidrug-resistant (MDR) bacteria (ie, methicillin-resistantStaphylococcus aureus[MRSA], vancomycin-resistantEnterococcus[VRE], extended-spectrum β-lactamase [ESBL]-producing Enterobacteriaceae, andAcinetobacter baumannii) after prolonged hospitalization and to assess the yield of surveillance cultures and variables associated with colonization with MDR bacteria.

Design.

Prospective observational cohort study conducted from February 6 to May 26, 2006.

Methods.

All patients who spent more than 30 days in our university hospital (Paris, France) were included. Rectal and nasal swab samples obtained during day 30 screening were examined for MRSA, VRE, ESBL-producing Enterobacteriaceae, andA. baumannii.

Results.

Of 470 eligible patients, 439 had surveillance culture samples available for analysis, including 51 patients (11.6%) with a history of colonization or infection due to 1 or more types of MDR bacteria (MRSA, recovered from 35 patients; ESBL-producing Enterobacteriaceae, from 16 patients;A. baumannii, from 6 patients; and VRE, from 0 patients) and 37 patients (9.5% of the 388 patients not known to have any of the 4 MDR bacteria before day 30 screening) newly identified as colonized by 1 or more MDR bacteria (MRSA, recovered from 20 patients; ESBL-producing Enterobacteriaceae, from 16 patients;A. baumannii, from 1 patient; and VRE, from 0 patients). A total of 87 (19.8%) of 439 patients were identified as colonized or infected with MDR bacteria at day 30. Factors that differed between patients with and without MRSA colonization included age, McCabe score, comorbidity score, receipt of surgery, and receipt of fluoroquinolone treatment. Patients with ESBL-producing Enterobacteriaceae colonization were younger than patients with MRSA colonization.

Conclusions.

Differences in the variables associated with MRSA colonization and ESBL-producing Enterobacteriaceae colonization suggest differences in the epidemiology of these 2 organisms. Day 30 screening resulted in a 72.5% increase in the number of patients identified as colonized with at least 1 type of MDR bacteria.
i-ADHoRe 2.0: an improved tool to detect degenerated genomic homology using genomic profiles
Authors: Simillion Cedric , Janssens Koen , Sterck Lieven , Van de Peer Yves
Published: October 2007

Summary: i-ADHoRe is a software tool that combines gene content and gene order information of homologous genomic segments into profiles to detect highly degenerated homology relations within and between genomes. The new version offers, besides a significant increase in performance, several optimizations to the algorithm, most importantly to the profile alignment routine. As a result, the annotations of multiple genomes, or parts thereof, can be fed simultaneously into the program, after which it will report all regions of homology, both within and between genomes.

Availability: The i-ADHoRe 2.0 package contains the C++ source code for the main program as well as various Perl scripts and a fully documented Perl API to facilitate post-processing. The software runs on any Linux- or -UNIX based platform. The package is freely available for academic users and can be downloaded from http://bioinformatics.psb.ugent.be/

Contact:  yves.vandepeer@psb.ugent.be

Supplementary information: Supplementary data are available at Bioinformatics online.
Converting Academic Expertize into Industrial Innovation: University-based Research at Solvay and Gevaert, 1900–1970
Authors: Bertrams Kenneth
Published: October 2007

The question this article seeks to address relates to the strategies deployed by the chemical firms Solvay & Co. and Gevaert N.V.—two multinationals operating in a highly innovative sector and depending on Belgium's national system of innovation—by taking advantage from the research capabilities located in the surrounding academic landscape. The two companies adopted different methods to capture the knowledge produced in university laboratories, which corresponded best to the kind of research they wished to explore. It will be argued that, instead of conforming to any previous blueprint for linear innovation, industrialists and academics have sought to overcome their conflicting interests and cultural divergence by bringing out mutual opportunities that eventually led to unexpected forms of utilitarian cooperation. In the long run, informal linkages and social networks helped shaping the patterns of increasingly coordinated and elaborated procedures of innovation.
Investigation of a multi-ball, automatic dynamic balancing mechanism for eccentric rotors
Authors: Green K , Champneys A.R , Friswell M.I , Muñoz A.M
Published: October 2007

This paper concerns an analytical and experimental investigation into the dynamics of an automatic dynamic balancer (ADB) designed to quench vibration in eccentric rotors. This fundamentally nonlinear device incorporates several balancing masses that are free to rotate in a circumferentially mounted ball race. An earlier study into the steady state and transient response of the device with two balls is extended to the case of an arbitrary number of balls. Using bifurcation analysis allied to numerical simulation of a fully nonlinear model, the question is addressed of whether increasing the number of balls is advantageous. It is found that it is never possible to perfectly balance the device at rotation speeds comparable with or below the first natural, bending frequency of the rotor. When considering practical implementation of the device, a modification is suggested where individual balls are contained in separate arcs of the ball race, with rigid partitions separating each arc. Simulation results for a partitioned ADB are compared with those from an experimental rig. Close qualitative and quantitative match is found between the theory and the experiment, confirming that for sub-resonant rotation speeds, the ADB at best makes no difference to the imbalance, and can make things substantially worse. Further related configurations worthy of experimental and numerical investigation are proposed.