bluuebunny/crossref_metadata_2025 huggingface dataset:
A better presentation of Planck’s radiation law
Authors: Marr Jonathan M. , Wilkin Francis P.
Published: April 2012

Introductory physics and astronomy courses commonly use Wien’s displacement law to explain the colors of blackbodies, including the Sun and other stars, in terms of their temperatures. We argue here that focusing on the peak of the blackbody spectrum is misleading for three reasons. First, the Planck curve is too broad for an individual spectral color to stand out. Second, the location of the peak of the Planck curve depends on the choice of the independent variable in the plot. And third, Wien’s displacement law is seldom used in actual practice to find a temperature and direct fitting to the Planck function is preferable. We discuss these flaws and argue that, at the introductory level, presentation of blackbody radiation in terms of photon statistics would be more effective pedagogically. The average energy of the emitted photons would then be presented in place of Wien’s displacement law, and discussion of the Stefan-Boltzmann law would include the total number of photons emitted per second. Finally, we suggest that the Planck spectrum is most appropriately plotted as a “spectral energy density per fractional bandwidth distribution,” using a logarithmic scale for the wavelength or frequency.
Computing accurate age and distance factors in cosmology
Authors: Christiansen Jodi L. , Siver Andrew
Published: April 2012

As the universe expands astronomical observables such as brightness and angular size on the sky change in ways that differ from our simple Cartesian expectation. We show how observed quantities depend on the expansion of space and demonstrate how to calculate such quantities using the Friedmann equations. The general solution to the Friedmann equations requires a numerical solution, which is easily coded in any computing language (including excel). We use these numerical calculations in four projects that help students build their understanding of high-redshift phenomena and cosmology. Instructions for these projects are available as supplementary materials.
Ballistic motion of dust particles in the Lunar Roving Vehicle dust trails
Authors: Hsu Hsiang-Wen , Horányi Mihály
Published: April 2012

We have selected video images from the Apollo 16 mission and analyzed the motion of dust clouds kicked up by the wheels of the Lunar Roving Vehicle (LRV). Applying the equations of ballistic motion, we estimate both the velocity of the dust and the gravitational field strength at the lunar surface. From measurements of the rotation of an LRV wheel, we estimate the speed of the LRV. Such exercises can be useful when discussing ballistic trajectories and angular motion in a high school or introductory level college physics class.
Stellar temperatures by Wien’s law: Not so simple
Authors: Cenadelli Davide , Potenza Marco , Zeni Mauro
Published: April 2012

A star’s surface temperature is among the most important features that can be deduced from its light. We have made measurements to see how reliably we could determine the surface temperatures of some A to K stars using Wien’s Displacement Law. We took spectra, corrected them for atmospheric extinction and instrumental response, found the wavelengths of their intensity maxima, and then from Wien’s law found the surface temperatures of the observed stars. For F to early K stars, our results agree with temperatures determined in other ways. For A and later K stars, the agreement is poor because the spectra are appreciably different from ideal blackbody spectra and because our equipment responds poorly to the deep red and blue wavelengths where the spectra of these stars have their peak intensities. This paper points out several interesting concepts in and outside the astrophysical domain that can be instructive for undergraduate students.
A Systematic Approach for Analysis of Peptide Array Kinome Data
Authors: Li Yue , Arsenault Ryan J. , Trost Brett , Slind Jillian , Griebel Philip J. , Napper Scott , Kusalik Anthony
Published: April 2012

A new method of analysis of kinome data takes account of the differences between peptide arrays and DNA microarrays.
Starvation and Autophagy
Authors: Ray L. Bryan
Published: April 2012

When the autophagy protein Atg7 is absent, nutrient withdrawal does not stop the cell cycle.
Local Synthesis for Retrograde Signaling
Authors: Gough Nancy R.
Published: April 2012

Axonal synthesis of SMADs triggered by the neurotrophin BDNF enables retrograde signaling by the morphogen BMP4 in trigeminal ganglia neurons.
Adjusting for Stochasticity?
Authors: Gough Nancy R.
Published: April 2012

By changing the abundance of the motor proteins, bacteria can adapt to differences in the abundance of the signaling protein.
A Better Way to Get Fat?
Authors: Wong Wei
Published: April 2012

Increased angiogenesis in white adipose tissue can attenuate some of the metabolic effects of diet-induced obesity.
Activity of Human Immunodeficiency Virus Type 1 Protease Inhibitors against the Initial Autocleavage in Gag-Pol Polyprotein Processing
Authors: Davis David A. , Soule Erin E. , Davidoff Katharine S. , Daniels Sarah I. , Naiman Nicole E. , Yarchoan Robert
Published: April 2012

Inhibitors of HIV protease have proven to be important drugs in combination anti-HIV therapy. These inhibitors were designed to target mature protease and prevent viral particle maturation by blocking Gag and Gag-Pol processing by mature protease. Currently there are few data assessing the ability of these protease inhibitors to block the initial step in autoproteolytic processing of Gag-Pol. This unique step involves the dimerization of two Gag-Pol polyproteins and autocleavage of the Gag-Pol polyprotein by the embedded dimeric protease. We developed a plasmid encoding a modified form of Gag-Pol that can undergo autoprocessing only at the initial cleavage site between p2 and nucleocapsid. Using anin vitrotranscription/translation system, we assessed the ability of six different approved protease inhibitors (darunavir, indinavir, nelfinavir, ritonavir, saquinavir, and tipranavir) to block this initial autocleavage step. Of these inhibitors, darunavir and saquinavir were the most effective. Darunavir and saquinavir were also the most effective at blocking the initial autoprocessing of full-length Gag-Pol in HIV-1-infected T cells. Thus, we have identified at least two HIV-1 protease inhibitors that have activity against the primary autocatalytic step of the embedded HIV-1 protease in Gag-Pol at concentrations that may be attained in HIV-1-infected patients. Due to unique aspects of the initial processing step, it may be possible to develop inhibitors with greater potency against this step, thus halting viral maturation at the earliest stages. The transcription/translation assay could be used to develop more potent inhibitors of this essential first step in viral maturation.
Sontochin as a Guide to the Development of Drugs against Chloroquine-Resistant Malaria
Authors: Pou Sovitj , Winter Rolf W. , Nilsen Aaron , Kelly Jane Xu , Li Yuexin , Doggett J. Stone , Riscoe Erin W. , Wegmann Keith W. , Hinrichs David J. , Riscoe Michael K.
Published: April 2012

Sontochin was the original chloroquine replacement drug, arising from research by Hans Andersag 2 years after chloroquine (known as “resochin” at the time) had been shelved due to the mistaken perception that it was too toxic for human use. We were surprised to find that sontochin, i.e., 3-methyl-chloroquine, retains significant activity against chloroquine-resistant strains of
Plasmodium falciparum in vitro
. We prepared derivatives of sontochin, “pharmachins,” with alkyl or aryl substituents at the 3 position and with alterations to the 4-position side chain to enhance activity against drug-resistant strains. Modified with an aryl substituent in the 3 position of the 7-chloro-quinoline ring, Pharmachin 203 (PH-203) exhibits low-nanomolar 50% inhibitory concentrations (IC
50
s) against drug-sensitive and multidrug-resistant strains and
in vivo
efficacy against patent infections of
Plasmodium yoelii
in mice that is superior to chloroquine. Our findings suggest that novel 3-position aryl pharmachin derivatives have the potential for use in treating drug resistant malaria.
Characterizations of Clinical Isolates of Clostridium difficile by Toxin Genotypes and by Susceptibility to 12 Antimicrobial Agents, Including Fidaxomicin (OPT-80) and Rifaximin: a Multicenter Study in Taiwan
Authors: Liao Chun-Hsing , Ko Wen-Chien , Lu Jang-Jih , Hsueh Po-Ren
Published: April 2012

A total of 403 nonduplicate isolates of
Clostridium difficile
were collected at three major teaching hospitals representing northern, central, and southern Taiwan from January 2005 to December 2010. Of these 403 isolates, 170 (42.2%) were presumed to be nontoxigenic due to the absence of genes for toxins A or B or binary toxin. The remaining 233 (57.8%) isolates carried toxin A and B genes, and 39 (16.7%) of these also had binary toxin genes. The MIC
90
of all isolates for fidaxomicin and rifaximin was 0.5 μg/ml (range, ≤0.015 to 0.5 μg/ml) and >128 μg/ml (range, ≤0.015 to >128 μg/ml), respectively. All isolates were susceptible to metronidazole (MIC
90
of 0.5 μg/ml; range, ≤0.03 to 4 μg/ml). Two isolates had reduced susceptibility to vancomycin (MICs, 4 μg/ml). Only 13.6% of isolates were susceptible to clindamycin (MIC of ≤2 μg/ml). Nonsusceptibility to moxifloxacin (
n
= 81, 20.1%) was accompanied by single or multiple mutations in
gyrA
and
gyrB
genes in all but eight moxifloxacin-nonsusceptible isolates. Two previously unreported
gyrB
mutations might independently confer resistance (MIC, 16 μg/ml), Ser416 to Ala and Glu466 to Lys. Moxifloxacin-resistant isolates were cross-resistant to ciprofloxacin and levofloxacin, but some moxifloxacin-nonsusceptible isolates remained susceptible to gemifloxacin or nemonoxacin at 0.5 μg/ml. This study found the diversity of toxigenic and nontoxigenic strains of
C. difficile
in the health care setting in Taiwan. All isolates tested were susceptible to metronidazole and vancomycin. Fidaxomicin exhibited potent
in vitro
activity against all isolates tested, while the more than 10% of Taiwanese isolates with rifaximin MICs of ≥128 μg/ml raises concerns.
Biochemical and Genetic Characterization of Carbapenem-Hydrolyzing β-Lactamase OXA-229 from Acinetobacter bereziniae
Authors: Bonnin Rémy A. , Ocampo-Sosa Alain A. , Poirel Laurent , Guet-Revillet Hélène , Nordmann Patrice
Published: April 2012

Acinetobacter bereziniae
(formerly
Acinetobacter
genomospecies 10) isolate Nec was recovered from a skin sample of a patient hospitalized in Paris, France. It was resistant to penicillins, penicillin-inhibitor combinations, and carbapenems. Cloning and expression in
Escherichia coli
identified the carbapenem-hydrolyzing class D β-lactamase OXA-229, which is weakly related to other oxacillinases (66% amino acid identity with the closest oxacillinase, OXA-58). It hydrolyzed penicillins, oxacillin, and imipenem but not expanded-spectrum cephalosporins. Sequencing of the genetic context of the
bla
OXA-229
gene did not identify an insertion sequence but did identify mutations in the promoter sequences in comparison to the fully susceptible
A. bereziniae
reference strain. The overexpression of
bla
OXA-229
in
A. bereziniae
Nec as a source of carbapenem resistance was identified by quantitative real-time PCR.
Decreased Susceptibility to Noncarbapenem Antimicrobials in Extended-Spectrum-β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Isolates in Toronto, Canada
Authors: Lowe Christopher F. , McGeer Allison , Muller Matthew P. , Katz Kevin
Published: April 2012

Retrospective review from 11 Canadian hospitals showed increasing incidence of extended-spectrum β-lactamase (ESBL)-producing
Escherichia coli
and
Klebsiella pneumoniae
from 0.12 per 1,000 inpatient days during 2005 to 0.47 per 1,000 inpatient days during 2009. By 2009, susceptibility rates of ESBL-positive
E. coli
/
K. pneumoniae
were as follows: ciprofloxacin, 12.8%/9.0%; TMP/SMX, 32.9%/12.2%; and nitrofurantoin, 83.8%/10.3%. Nosocomial and nonnosocomial ESBL-producing
E. coli
isolates had similar susceptibility profiles, while nonnosocomial ESBL-producing
K. pneumoniae
was associated with decreased ciprofloxacin (
P
= 0.03) and nitrofurantoin (
P
< 0.001) susceptibilities.
Resistance Analysis of the Hepatitis C Virus NS3 Protease Inhibitor Asunaprevir
Authors: McPhee Fiona , Friborg Jacques , Levine Steven , Chen Chaoqun , Falk Paul , Yu Fei , Hernandez Dennis , Lee Min S. , Chaniewski Susan , Sheaffer Amy K. , Pasquinelli Claudio
Published: April 2012

Asunaprevir (BMS-650032) is a potent hepatitis C virus (HCV) NS3 protease inhibitor demonstrating efficacy in alfa interferon-sparing, direct-acting antiviral dual-combination regimens (together with the NS5A replication complex inhibitor daclatasvir) in patients chronically infected with HCV genotype 1b. Here, we describe a comprehensive
in vitro
genotypic and phenotypic analysis of asunaprevir-associated resistance against genotypes 1a and 1b using HCV replicons and patient samples obtained from clinical studies of short-term asunaprevir monotherapy. During genotype 1a resistance selection using HCV replicons, the primary NS3 protease substitutions identified were R155K, D168G, and I170T, which conferred low- to moderate-level asunaprevir resistance (5- to 21-fold) in transient-transfection susceptibility assays. For genotype 1b, a higher level of asunaprevir-associated resistance was observed at the same selection pressures, ranging from 170- to 400-fold relative to the wild-type control. The primary NS3 protease substitutions identified occurred predominantly at amino acid residue D168 (D168A/G/H/V/Y) and were associated with high-level asunaprevir resistance (16- to 280-fold) and impaired replication capacity. In asunaprevir single-ascending-dose and 3-day multiple-ascending-dose studies in HCV genotype 1a- or 1b-infected patients, the predominant pre-existing NS3 baseline polymorphism was NS3-Q80K. This substitution impacted initial virologic response rates in a single-ascending-dose study, but its effects after multiple doses were more ambiguous. Interestingly, for patient NS3 protease sequences containing Q80 and those containing K80, susceptibilities to asunaprevir were comparable when tested in an enzyme assay. No resistance-associated variants emerged in these clinical studies that significantly impacted susceptibility to asunaprevir. Importantly, asunaprevir-resistant replicons remained susceptible to an NS5A replication complex inhibitor, consistent with a role for asunaprevir in combination therapies.
Nonspecific Effect of Mycograb on Amphotericin B MIC
Authors: Richie D. L. , Ghannoum M. A. , Isham N. , Thompson K. V. , Ryder N. S.
Published: April 2012

Mycograb C28Y is a recombinant human antibody fragment thought to target HSP-90 and potentiate amphotericin B (AMB). Absence of
in vivo
efficacy led us to reevaluate its
in vitro
activity. Interactions between AMB and Mycograb were investigated using a checkerboard design. Addition of Mycograb or various unrelated proteins, including human serum, resulted in similar decreases in the MIC of AMB. Potentiation of AMB by Mycograb appears to be a nonspecific protein effect.
First Identification of OXA-72 Carbapenemase from Acinetobacter pittii in Colombia
Authors: Montealegre Maria Camila , Maya Juan José , Correa Adriana , Espinal Paula , Mojica Maria F. , Ruiz Sory J. , Rosso Fernando , Vila Jordi , Quinn John P. , Villegas Maria Virginia
Published: April 2012

OXA-72 has been reported in few countries around the world. We report the first case in Colombia in an
Acinetobacter pittii
clinical isolate. The arrival of a new OXA, into a country with high endemic resistance, poses a significant threat, especially because the potential for widespread dissemination is considerable.
Dogs of Nomadic Pastoralists in Northern Kenya Are Reservoirs of Plasmid-Mediated Cephalosporin- and Quinolone-Resistant Escherichia coli, Including Pandemic Clone B2-O25-ST131
Authors: Albrechtova Katerina , Dolejska Monika , Cizek Alois , Tausova Dagmar , Klimes Jiri , Bebora Lily , Literak Ivan
Published: April 2012

Resistance in
Escherichia coli
isolates colonizing gastrointestinal tracts of dogs, cats, and their owners in Northern Kenya was investigated with an emphasis on extended-spectrum beta-lactamases (ESBLs). Totals of 47 (22%,
n
= 216), 2 (4%,
n
= 50), and 4 (17%,
n
= 23) CTX-M-15-producing
E. coli
isolates were obtained from dogs, cats, and humans, respectively. CTX-M-15-producing
E. coli
isolates with identical PFGE profiles were detected in animals and humans living in the same area.
The Spiroindolone Drug Candidate NITD609 Potently Inhibits Gametocytogenesis and Blocks Plasmodium falciparum Transmission to Anopheles Mosquito Vector
Authors: van Pelt-Koops J. C. , Pett H. E. , Graumans W. , van der Vegte-Bolmer M. , van Gemert G. J. , Rottmann M. , Yeung B. K. S. , Diagana T. T. , Sauerwein R. W.
Published: April 2012

The global malaria agenda has undergone a reorientation from control of clinical cases to entirely eradicating malaria. For that purpose, a key objective is blocking transmission of malaria parasites from humans to mosquito vectors. The new antimalarial drug candidate NITD609 was evaluated for its transmission-reducing potential and compared to a few established antimalarials (lumefantrine, artemether, primaquine), using a suite of
in vitro
assays. By the use of a microscopic readout, NITD609 was found to inhibit the early and late development of
Plasmodium falciparum
gametocytes
in vitro
in a dose-dependent fashion over a range of 5 to 500 nM. In addition, using the standard membrane feeding assay, NITD609 was also found to be a very effective drug in reducing transmission to the
Anopheles stephensi
mosquito vector. Collectively, our data suggest a strong transmission-reducing effect of NITD609 acting against different
P. falciparum
transmission stages.
Members of the Francisella tularensis Phagosomal Transporter Subfamily of Major Facilitator Superfamily Transporters Are Critical for Pathogenesis
Authors: Marohn Mark E. , Santiago Araceli E. , Shirey Kari Ann , Lipsky Michael , Vogel Stefanie N. , Barry Eileen M.
Published: April 2012

Francisella tularensis
is the causative agent of tularemia. Due to its aerosolizable nature and low infectious dose,
F. tularensis
is classified as a category A select agent and, therefore, is a priority for vaccine development. Survival and replication in macrophages and other cell types are critical to
F. tularensis
pathogenesis, and impaired intracellular survival has been linked to a reduction in virulence. The
F. tularensis
genome is predicted to encode 31 major facilitator superfamily (MFS) transporters, and the nine-member
Francisella
phagosomal transporter (Fpt) subfamily possesses homology with virulence factors in other intracellular pathogens. We hypothesized that these MFS transporters may play an important role in
F. tularensis
pathogenesis and serve as good targets for attenuation and vaccine development. Here we show altered intracellular replication kinetics and attenuation of virulence in mice infected with three of the nine Fpt mutant strains compared with wild-type (WT)
F. tularensis
LVS. The vaccination of mice with these mutant strains was protective against a lethal intraperitoneal challenge. Additionally, we observed pronounced differences in cytokine profiles in the livers of mutant-infected mice, suggesting that alterations in
in vivo
cytokine responses are a major contributor to the attenuation observed for these mutant strains. These results confirm that this subset of MFS transporters plays an important role in the pathogenesis of
F. tularensis
and suggest that a focus on the development of attenuated Fpt subfamily MFS transporter mutants is a viable strategy toward the development of an efficacious vaccine.
Cj1136 Is Required for Lipooligosaccharide Biosynthesis, Hyperinvasion, and Chick Colonization by Campylobacter jejuni
Authors: Javed Muhammad Afzal , Cawthraw Shaun A. , Baig Abiyad , Li Jianjun , McNally Alan , Oldfield Neil J. , Newell Diane G. , Manning Georgina
Published: April 2012

Campylobacter jejuni
is a major cause of bacterial food-borne enteritis worldwide, and invasion into intestinal epithelial cells is an important virulence mechanism. Recently we reported the identification of hyperinvasive
C. jejuni
strains and created a number of transposon mutants of one of these strains, some of which exhibited reduced invasion into INT-407 and Caco-2 cells. In one such mutant the transposon had inserted into a homologue of
cj1136
, which encodes a putative galactosyltransferase according to the annotation of the
C. jejuni
NCTC11168 genome. In the current study, we investigated the role of
cj1136
in
C. jejuni
virulence, lipooligosaccharide (LOS) biosynthesis, and host colonization by targeted mutagenesis and complementation of the mutation. The
cj1136
mutant showed a significant reduction in invasion into human intestinal epithelial cells compared to the wild-type strain 01/51. Invasion levels were partially restored on complementing the mutation. The inactivation of
cj1136
resulted in the production of truncated LOS, while biosynthesis of a full-length LOS molecule was restored in the complemented strain. The
cj1136
mutant showed an increase in sensitivity to the bile salts sodium taurocholate and sodium deoxycholate and significantly increased sensitivity to polymyxin B compared to the parental strain. Importantly, the ability of the mutant to colonize 1-day-old chicks was also significantly impaired. This study confirms that a putative galactosyltransferase encoded by
cj1136
is involved in LOS biosynthesis and is important for
C. jejuni
virulence, as disruption of this gene and the resultant truncation of LOS affect both colonization
in vivo
and invasiveness
in vitro
.
E-Selectin Mediates Porphyromonas gingivalis Adherence to Human Endothelial Cells
Authors: Komatsu Toshinori , Nagano Keiji , Sugiura Shinsuke , Hagiwara Makoto , Tanigawa Naomi , Abiko Yuki , Yoshimura Fuminobu , Furuichi Yasushi , Matsushita Kenji
Published: April 2012

Porphyromonas gingivalis, a major periodontal pathogen, may contribute to atherogenesis and other inflammatory cardiovascular diseases. However, little is known about interactions betweenP. gingivalisand endothelial cells. E-selectin is a membrane protein on endothelial cells that initiates recruitment of leukocytes to inflamed tissue, and it may also play a role in pathogen attachment. In the present study, we examined the role of E-selectin inP. gingivalisadherence to endothelial cells. Human umbilical vein endothelial cells (HUVECs) were stimulated with tumor necrosis factor alpha (TNF-α) to induce E-selectin expression. Adherence ofP. gingivalisto HUVECs was measured by fluorescence microscopy. TNF-α increased adherence of wild-typeP. gingivalisto HUVECs. Antibodies to E-selectin and sialyl Lewis X suppressedP. gingivalisadherence to stimulated HUVECs.P. gingivalismutants lacking OmpA-like proteins Pgm6 and -7 had reduced adherence to stimulated HUVECs, but fimbria-deficient mutants were not affected. E-selectin-mediatedP. gingivalisadherence activated endothelial exocytosis. These results suggest that the interaction between host E-selectin and pathogen Pgm6/7 mediatesP. gingivalisadherence to endothelial cells and may trigger vascular inflammation.
Listeria monocytogenes Strain-Specific Impairment of the TetR Regulator Underlies the Drastic Increase in Cyclic di-AMP Secretion and Beta Interferon-Inducing Ability
Authors: Yamamoto Takeshi , Hara Hideki , Tsuchiya Kohsuke , Sakai Shunsuke , Fang Rendong , Matsuura Motohiro , Nomura Takamasa , Sato Fumihiko , Mitsuyama Masao , Kawamura Ikuo
Published: April 2012

Among a number of laboratory strains of
Listeria monocytogenes
used in experimental infection, strain LO28 is highly capable of inducing robust beta interferon (IFN-β) production in infected macrophages. In this study, we investigated the molecular mechanism of the IFN-β-inducing ability of LO28 by comparing it with that of strain EGD, a low-IFN-β-inducing strain. It was found that LO28 secretes a large amount of IFN-β-inducing factor, which turned out to be cyclic di-AMP. The secretion of cyclic di-AMP was dependent on MdrT, a multidrug resistance transporter, and LO28 exhibited a very high level of
mdrT
expression. The introduction of a null mutation into
mdrT
abolished the ability of LO28 to induce IFN-β production. Examination of genes responsible for the regulation of
mdrT
expression revealed a spontaneous 188-bp deletion in
tetR
of LO28. By constructing recombinant strains of LO28 and EGD in which
tetR
from each strain was replaced, it was confirmed that the distinct ability of LO28 is attributable mostly to
tetR
mutation. We concluded that the strong IFN-β-inducing ability of LO28 is due to a genetic defect in
tetR
resulting in the overexpression of
mdrT
and a concomitant increase in the secretion of cyclic di-AMP through MdrT.
Loss of Meningococcal PilU Delays Microcolony Formation and Attenuates Virulence
In Vivo
Authors: Eriksson Jens , Eriksson Olaspers Sara , Jonsson Ann-Beth
Published: April 2012

Neisseria meningitidis
is a major cause of sepsis and bacterial meningitis worldwide. This bacterium expresses type IV pili (Tfp), which mediate important virulence traits such as the formation of bacterial aggregates, host cell adhesion, twitching motility, and DNA uptake. The meningococcal PilT protein is a hexameric ATPase that mediates pilus retraction. The PilU protein is produced from the
pilT-pilU
operon and shares a high degree of homology with PilT. The function of PilT in Tfp biology has been studied extensively, whereas the role of PilU remains poorly understood. Here we show that
pilU
mutants have delayed microcolony formation on host epithelial cells compared to the wild type, indicating that bacterium-bacterium interactions are affected. In normal human serum, the
pilU
mutant survived at a higher rate than that for wild-type bacteria. However, in a murine model of disease, mice infected with the
pilT
mutant demonstrated significantly reduced bacterial blood counts and survived at a higher rate than that for mice infected with the wild type. Infection of mice with the
pilU
mutant resulted in a trend of lower bacteremia, and still a significant increase in survival, than that of the wild type. In conclusion, these data suggest that PilU promotes timely microcolony formation and that both PilU and PilT are required for full bacterial virulence.
Do pacifiers increase the risk of nosocomial diarrhoea? A cohort study
Authors: Sette Gabriela Cunha Schechtman , Mello Maria Júlia Gonçalves , Correia Jailson Barros , Sette Ioram Schechtman , Pontes da Silva Gisélia Alves , Soares de Lima Luciane
Published: April 2012

Design

Prospective cohort study.

Setting

Teaching paediatric hospital—Instituto de Medicina Integral Prof. Fernando Figueira (IMIP), Recife, Northeast Brazil.

Participants

378 of 536 infants admitted in paediatric wards from April to October 2009 were daily assessed during hospital stay until the first episode of nosocomial diarrhoea (ND), death or discharge. Infants with community-acquired diarrhoea, respiratory or haemodynamic instability and who stayed in hospital for <24 h were excluded.

Primary and secondary outcome measures

Incidence and risk factors for ND and rates of pacifier faecal contamination.

Results

33 ND episodes occurred in 378 infants, with a cumulative incidence of 8.7% and density of 11.25/1000 patients-day. ND occurred in 8.2% (16/194) of pacifier users compared with 9.2% (17/184) in non-users (adjusted OR=0.88, 95% CI 0.43 to 1.80). In multivariate logistic regression analysis, duration of oxygen use (OR=1.61; 95% CI 1.18 to 2.20) and days of antimicrobial use (OR=1.62, 95% CI 1.34 to 1.94) were associated with higher risk of ND, whereas being breast fed (OR=0.40, 95% CI 0.17 to 0.93) and each day of hospital stay (OR=0.65, 95% CI 0.53 to 0.80) were protective factors. Faecal coliforms were isolated in 16% (27/169) of tested pacifiers, 77.8% of which had more than 100 000 CFU/ml. The probability of a child remaining free of an episode of diarrhoea up to the seventh day of hospitalisation in the ward was 91.2% (95% CI 87.7% to 94.9%). The log-rank test showed no statistical difference between pacifier users and non-users.

Conclusions

ND is a frequent healthcare-associated infection in paediatric wards, but the use of pacifiers during the stay in hospital does not seem to affect the incidence of ND in infants in many settings where the burden of diarrhoea is still high.
NEUTRINOLESS DOUBLE-BETA DECAY: A BRIEF REVIEW
Authors: BILENKY S. M. , GIUNTI C.
Published: April 2012

In this brief review we discuss the generation of Majorana neutrino masses through the seesaw mechanism, the theory of neutrinoless double-beta decay, the implications of neutrino oscillation data for the effective Majorana mass, taking into account the recent Daya Bay measurement of ϑ13, and the interpretation of the results of neutrinoless double-beta decay experiments.
PHASE TRANSITIONS AND QUANTUM EFFECTS IN ANHARMONIC CRYSTALS
Authors: ALBEVERIO SERGIO , KONDRATIEV YURI , KOZITSKY YURI , RÖCKNER MICHAEL
Published: April 2012

The most important recent results in the theory of phase transitions and quantum effects in quantum anharmonic crystals are presented and discussed. In particular, necessary and sufficient conditions for a phase transition to occur at some temperature are given in the form of simple inequalities involving the interaction strength and the parameters describing a single oscillator. The main characteristic feature of the theory is that both mentioned phenomena are described in one and the same setting, in which thermodynamic phases of the model appear as probability measures on path spaces. Then the possibility of a phase transition to occur is related to the existence of multiple phases at the same values of the relevant parameters. Other definitions of phase transitions, based on the nondifferentiability of the free energy density and on the appearance of ordering, are also discussed.
UPDATED LAGRANGIAN FORMULATION FOR NONLINEAR STABILITY ANALYSIS OF THIN-WALLED FRAMES WITH SEMI-RIGID CONNECTIONS
Authors: TURKALJ GORAN , BRNIC JOSIP , LANC DOMAGOJ , KRAVANJA STOJAN
Published: April 2012

This paper presents a one-dimensional (1D) finite element formulation for the nonlinear stability analysis of framed structures with semi-rigid (SR) connections. By applying the updated Lagrangian incremental formulation and the nonlinear displacement field of thin-walled cross sections, the equilibrium equations of a straight beam element are first developed. Force recovering is performed according to the external stiffness approach. Material nonlinearity is introduced for an elastic-perfectly plastic material through the plastic hinge formation at finite element ends. To account for the SR connection behavior, a special transformation procedure is developed. The effectiveness of the numerical algorithm discussed is validated through the test problems.
A COMPARATIVE STUDY ON THE DISPERSION PROPERTIES OF HRK AND RK MESHFREE APPROXIMATIONS FOR KIRCHHOFF PLATE PROBLEM
Authors: WANG DONGDONG , LIN ZHENTING
Published: April 2012

Dispersion analysis provides a rational way to examine the dynamic properties of numerical methods through comparing the numerical and continuum frequencies. In this paper a detailed comparative investigation is presented on the dispersion features of the Hermite reproducing kernel (HRK) and the conventional reproducing kernel (RK) meshfree methods for Kirchhoff plate problem with particular reference to the spatial discretizations. In the analysis the nodal variables of the semi-discretized meshfree Kirchhoff plate equations are assumed as harmonic wave functions to extract the numerical frequency. For the RK approximation, only the deflectional nodal variables are expressed by the harmonic wave functions, while unlike RK approximation, both deflectional and rotational nodal variables should be expressed by the harmonic wave functions for the HRK approximation. The dispersion analysis results uniformly evince that the HRK meshfree discretization has much smaller dispersion errors and performs superiorly compared to the conventional RK meshfree discretization for Kirchhoff plate problem.
RECENT PROGRESS IN MODELING CRACK PROPAGATION USING THE SCALED BOUNDARY FINITE ELEMENT METHOD
Authors: YANG Z. J. , OOI E. T.
Published: April 2012

This study reviews our recent efforts in the development and application of crack propagation modeling approaches based on the scaled boundary finite element method (SBFEM). These include models for linear and nonlinear, static and dynamic, and single and multiple crack propagation problems, and application to efficient prediction of deterministic size effect laws and complicated fracture behavior of reinforced concrete structures. The advantages and disadvantages of these approaches are compared with the FEM.
EXPONENTIAL–POLYNOMIAL CLOSURE METHOD FOR SOLVING TRUNCATED KOLMOGOROV–FELLER EQUATION
Authors: ZHU H. T. , ER G. K. , IU V. P. , KOU K. P.
Published: April 2012

The probability density function (PDF) solution of the response is formulated for nonlinear systems under discrete Poisson impulse excitation. The PDF solution is governed by the Kolmogorov–Feller (KF) equation, which is approximately solved by the exponential–polynomial closure (EPC) method. A Duffing oscillator is further investigated in the case of either Gaussian or non-Gaussian distributed amplitude of Poisson impulse to show the effectiveness of the EPC method in these cases. The numerical analysis shows that the EPC method with the polynomial order being 6 presents a good result compared with the simulated result, even in the tails of the PDF of the oscillator response.
Carbon Nanotube Research: Past and Future
Authors: Endo Morinobu
Published: April 2012

In this paper, my experience of over 30 years in carbon materials and carbon nanotube (CNT) researches is reported. Moreover, an overview of the background of the development of CNT synthesis, the present status of CNT science and technology, and the future prospect of CNTs are described.
Ultrathin Reflective Flexible Liquid Crystal Display Film
Authors: Liu Kang-Hung , Shieh Han-Ping D.
Published: April 2012

In this investigation, we present a thin reflective liquid crystal film with a mixed-mode twisted nematic mode. A low-temperature alignment process is used to obtain good orientation of the liquid crystal molecules. A microcell process is utilized to maintain a uniform cell gap of the flexible display under various bending conditions. To simplify the structure of a flexible mixed-mode twisted nematic liquid crystal display film, a layer of Zeonor optical plastic material is used in place of conventional plastic substrates; this material exhibits quarter wave retardation. The ultrathin device exhibits good cell gap uniformity, a high reflectivity of 35%, and a short response time of 6.67 ms.
Microscopic Structure of Stepwise Threading Dislocation in 4H-SiC Substrate
Authors: Ishikawa Yukari , Sugawara Yoshihiro , Saitoh Hiroaki , Danno Katsunori , Suzuki Hiroshi , Bessho Takeshi , Kawai Yoichiro , Shibata Noriyoshi
Published: April 2012

The dislocation structure that forms the caterpillar-shaped etch pit upon molten KOH etching is investigated by transmission electron microscopy employing a weak-beam dark-field method. The observed dislocation has the Burgers vector 1/3[1̄21̄0], and its structure was transformed from a basal plane dislocation to a threading edge dislocation. In the basal plane dislocation region, it propagated parallel to the [101̄0] direction. On the basis of the measured dislocation structure, the caterpillar pit formation is explained. The process of dislocation formation is discussed by analyzing the relationship between sample types and the detection of the caterpillar pits.
Low-Voltage Mach–Zehnder Modulator with InGaAs/InAlAs Five-Layer Asymmetric Coupled Quantum Well
Authors: Arakawa Taro , Hariki Takehiro , Amma Yoshimichi , Fukuoka Masayasu , Ushigome Motoki , Tada Kunio
Published: April 2012

We have demonstrated a low-voltage Mach–Zehnder (MZ) modulator with a multiple InGaAs/InAlAs five-layer asymmetric coupled quantum well (FACQW) for 1.55 µm wavelength. The FACQW is expected to exhibit a large electrorefractive index change owing to its unique behavior of the quantum-confined Stark effect. The MZ modulator with ridge waveguides was fabricated by molecular beam epitaxy and wet etching. The product of a half-wave voltage and a phase shifter length (V
π
L) was as low as 1.2 V·mm in DC modulation. In addition, we discussed the degradation of the electrorefractive index change due to the nonuniformity of an electric field in the core layer and proposed a novel combined multiple FACQW structure to prevent the degradation.
Characterization of Photoexcited Carriers and Thermal Properties of Nanoparticulate TiO2 Film Using Heterodyne Transient Grating Method
Authors: Hata Hiroaki , Katayama Kenji , Shen Qing , Toyoda Taro
Published: April 2012

Diffusion of photoexcited carriers and the subsequent thermal diffusion by photoexcitation of a nanoparticulate TiO2 thin film were observed by the heterodyne transient grating (HD-TG) method. The observed HD-TG signal showed that the photoexcited carriers were generated inhomogeneously in the depth direction and they diffused both in the depth and parallel directions of the film. The diffusion processes were analyzed using a two-dimensional diffusion model. The thermal profile generated by the relaxation of the photoexcited carriers was treated by the same model. It was found that the effective diffusivities of the photoexcited carriers and heat decreased as the size of the nanoparticles in the film increased. It is suggested that the transport properties of the photoexcited carriers and heat are dominated by the inter-particulate resistance.
Effects of Electrospun TiO2Nanowires Mixed in Nanoparticle-Based Electrode for Dye-Sensitized Solar Cells
Authors: Shimada Chieko , Kitamura Koji , Shiratori Seimei
Published: April 2012

In this article, we report the improvement of energy conversion efficiency by a simple process for dye-sensitized solar cells (DSSCs). Some previous studies were reported in which TiO2nanowires were used in the place of TiO2nanoparticles as a TiO2electrode because nanowires possess a good electron transport property. However, if larger sizes of nanowires are used for the TiO2electrode, a large void between nanowires and a decrease in surface area are observed. To solve this problem, we report a TiO2nanoparticle/nanowire hybrid electrode for DSSCs, which showed both a good electron transport property and dye adsorption. TiO2nanofibers were fabricated by an electrospinning method and sol–gel techniques. TiO2nanowires, whose diameters were controlled by varying the polymer concentration in the electrospinning solution, were successfully applied to DSSCs. We examine how TiO2nanowires can work in the TiO2electrode. In this study, we demonstrated that this hybrid electrode has an advantage in the efficiency of DSSCs.
Unidirectional Liquid Crystal Pretilt Generation on Asymmetric Nanoscaled Groove Pattern Driven by Atomic Force Microscopic Tip
Authors: Gwag Jin Seog , Jo Soo In , Lee You-Jin , Kim Jae-Hoon
Published: April 2012

We demonstrate uniformly and unidirectionally distributed pretilt characteristics of a liquid crystal cell fabricated via a substrate with a scan-directional slant nanosized surface groove pattern driven through an atomic force microscopic (AFM) tip that is continuously modulating the contact force in the scanning line direction. The resultant electro-optic characteristics of the liquid crystal (LC) cell made by our advanced AFM lithography technique show that it generates a unidirectional pretilt that guarantees wider LC applications.
Investigation of Optical and Electrochromic Properties of Tungsten Oxide Deposited with Horizontal DC and DC Pulse Magnetron Sputtering
Authors: Chen Hsi-Chao , Jan Der-Jun , Chen Chien-Han
Published: April 2012

The proposal of this research was to compare the optical and electrochromic properties of tungsten oxide (WO3) thin films deposited with a horizontal direct current (DC) and DC pulse magnetron sputtering. These WO3 thin films were deposited onto indium tin oxide (ITO) glass and p-type silicon substrate at different gas ratios of oxygen and argon. The variation in the transmittance between the coloring and bleaching was important for the smart window. WO3 thin films have good electrochromic properties at gas ratios of oxygen/argon (O2/Ar) of 0.7 and 0.6 for DC and DC pulse magnetron sputtering, respectively. However, WO3 thin films deposited by DC pulse magnetron sputtering have better optical and electrochromic properties than the films deposited by DC magnetron sputtering.
Effect of Nucleation Layer of Photocatalytic TiO2 Thin Film Prepared by Two-Step Deposition Using Radical-Assisted Sputtering
Authors: Noguchi Daisuke , Higashimaru Yukie , Eto Tomohiro , Kodama Kazuya , Fukudome Shoji , Kawano Yoshihiko , Sei Fumihiro , Siono Ichiro
Published: April 2012

A nucleation layer forms in the nucleation step (the first step) of a two-step deposition method that we have developed for forming TiO2 thin films. We found that the nucleation layer affects the crystallinity of TiO2 thin films during the growth step (the second step). The crystallinity of the growth layer can be controlled by varying the kinetic energy of the sputter particles when they arrive at the substrate in the nucleation step. Since the nucleation density varies with the kinetic energy, the crystallinity is thought to improve, owing to the improvement in the nucleation density.
Properties of Inductively Coupled Radio Frequency CH4/H2 Plasmas: Experiments and Global Model
Authors: Kimura Takashi , Kasugai Hiroki
Published: April 2012

Experiments with a Langmuir probe and optical emission spectroscopy combined with actinometry are carried out in inductively coupled rf (13.56 MHz) CH4/H2 plasmas at three total pressures of 25, 50, and 100 mTorr for hydrogen fractions ranging from 0 to 80%. The measured electron density gradually decreases with increasing hydrogen fraction, whereas the measured effective electron temperature slightly increases with hydrogen fraction. The density of hydrogen atoms estimated by actinometry does not strongly depend on hydrogen fraction. The high density of hydrogen molecules can be expected even in CH4 plasmas from the optical intensity emitted from the excited hydrogen molecules. A global model is analyzed in order to understand the plasma chemistry in CH4/H2 plasmas. In the model, the dominant neutral species are always hydrogen and CH4 molecules, followed by hydrogen atoms and hydrocarbons, such as C2H
n
(n=1, 2, and 4). On the other hand, the dominant ions are CH5
+, C2H+, C2H3
+, C2H5
+, and C3H5
+ at low hydrogen fraction, whereas H3
+ ions become dominant ion species as hydrogen fraction increases.
Mn2O3 Slurry Achieving Reduction of Slurry Waste
Authors: Kishii Sadahiro , Nakamura Ko , Hanawa Kenzo , Watanabe Satoru , Arimoto Yoshihiro , Kurokawa Syuhei , Doi Toshiro K.
Published: April 2012

Fumed silica is widely used for SiO2 chemical mechanical polishing (CMP). In semiconductor processes, only fresh slurry is used, the used slurry being disposed of. We have demonstrated that Mn2O3 abrasive slurry polishes dielectric SiO2 film, giving 4 times the removal rate of conventional fumed silica slurry. The higher removal rate reduces the total amount of slurry used, consequently reducing the amount of used slurry waste. The removal rate of Mn2O3 slurry remains constant for solid concentrations between l and 10 wt %, and stays constant without pad conditioning. These characteristics are very useful for slurry reuse. Remanufacture of Mn2O3 slurry from used slurry has been demonstrated, and the removal rates of the remanufactured and fresh slurries are the same. Reuse and remanufacturing drastically reduce the amount of waste.
A New Collinear-Type Energy-Filtered X-ray Photoemission Electron Microscope Equipped with a Multi-Pole Aberration-Corrected Air-Core Coil Wien Filter
Authors: Miyamoto Takeshi , Wada Takahiro , Niimi Hironobu , Suzuki Shushi , Kato Makoto , Kudo Masato , Asakura Kiyotaka
Published: April 2012

We present the prototype of a new, collinear-type energy-filtered X-ray photoemission electron microscope (EXPEEM) using a multi-pole, aberration-corrected air-core coil Wien filter (WF) analyzer. We have designed the new WF with 12-pole electrodes and magnetic poles to reduce spherical aberrations and fringe effects. We assess the performance of the WF using an electron energy analyzer for PEEM. The sensitivity is enhanced 10–100 fold compared with a simple, two electrodes plus two magnetic poles type WF. Cu 2p3/2 and Au 4f7/2 photoelectron energy selected images are obtained in a laboratory-scale source within several minutes. The energy and spatial resolutions of our prototype EXPEEM are estimated to be 3 eV and 7 µm, respectively.
Study of Active Micromixer Driven by Electrothermal Force
Authors: Huang Kuan-Rong , Chang Jeng-Shian , Chao Sheng D. , Wung Tzong-Shyan , Wu Kuang-Chong
Published: April 2012

Biochemical applications of microchips often require a rapid mixing of different fluid samples. At the microscale level, fluid flow is usually a highly ordered laminar flow and diffusion is the primary mechanism for mixing owing to the lack of disturbances, yielding inefficiency for practical biochemical analysis. In this work, we design a prototype active micromixer by employing the electrothermal effect. We apply to the flow microchannel a non-uniform AC electric field, which can generate an electrothermal force on the fluid flow and induce vortex pairs for enhancing mixing efficiency. The performance of this active micromixer is studied and compared, under the same mixing quality, with that of a conventional passive micromixer of the same size with obstacles in the flow channel by three-dimensional finite element simulations. The numerical results show that the pressure drop between the inlet and the outlet for the active micromixer is much less than (only 3000th) that for the passive micro-mixer with the same mixing quality. To obtain an optimal mixing quality, we have systematically studied the mixing quality by varying the geometrical arrangements of the electrodes. An almost complete mixing can be obtained using a specific design. Moreover, the temperature increases around the electrodes are lower than 3 K, which does not adversely affect the biochemical analysis. It is suggested that the prototype active micromixer designed is promising and effective and useful for biochemical analysis.
Comprehensive Study of the X-Ray Photoelectron Spectroscopy Peak Shift of La-Incorporated Hf Oxide for Gate Dielectrics
Authors: Yamamoto Takashi , Ogawa Shingo , Tsuji Jun-ichi , Kita Koji , Tagami Katsunori , Uda Tsuyoshi , Hosoi Takuji , Shimura Takayoshi , Watanabe Heiji
Published: April 2012

We measured the X-ray photoelectron spectroscopy spectra of the La-incorporated Hf oxide and observed the apparent Hf 4f peak shift toward a lower energy as La concentration increased. To investigate the origin of these peak shifts, we performed first-principles calculations, in which the degree and direction of the obtained peak shifts agreed well with the above-mentioned experimentally observed spectra. Also, we found that the main reason for these peak shifts was the charge-transfer effect. Estimation of the degree of the interface dipole was made possible by a comparison between the experimental values and the theoretical values of the peak shifts.