bluuebunny/crossref_metadata_2025 huggingface dataset:
Model Identification and Operating Load Characterization for a Small Horizontal Axis Wind Turbine Rotor Using Integrated Blade Sensors
Authors: Dana Scott , Yutzy Joseph , Adams Douglas E.
Published: February 2011

One of the primary challenges in diagnostic health monitoring and control of wind turbines is compensating for the variable nature of wind loads. Given the sometimes large variations in wind speed, direction, and other operational variables (like wind shear), this paper proposes a data-driven, online rotor model identification approach. A 2 m diameter horizontal axis wind turbine rotor is first tested using experimental modal analysis techniques. Through the use of the Complex Mode Indication Function, the dominant natural frequencies and mode shapes of dynamic response of the rotor are estimated (including repeated and pseudo-repeated roots). The free dynamic response properties of the stationary rotor are compared to the forced response of the operational rotor while it is being subjected to wind and rotordynamic loads. It is demonstrated that both narrowband (rotordynamic) and broadband (wind driven) responses are amplified near resonant frequencies of the rotor. Blade loads in the flap direction of the rotor are also estimated through matrix inversion for a simulated set of rotor blade input forces and for the operational loading state of the wind turbine in a steady state condition. The analytical estimates are shown to be accurate at frequencies for which the ordinary coherence functions are near unity. The loads in operation are shown to be largest at points mid-way along the span of the blade and on one of the three blades suggesting this method could be used for usage monitoring. Based on these results, it is proposed that a measurement of upstream wind velocity will provide enhanced models for diagnostics and control by providing a leading indicator of disturbances in the loads.
Mathematical Modeling of Electrostatic MEMS Actuators: A Review
Authors: Wickramasinghe I. P. M. , Berg Jordan M.
Published: February 2011

This review examines recent results on analytical modeling of electrostatic MEMS. Such modeling can include multiple coupled physics domains, including electrostatic forces, and lumped circuit models, structural elasticity, rigid body dynamics, or fluid mechanics. This review focuses on analytical models that provide the benefits of a closed-form expression trade rather than strive for the highest degree of accuracy for. Such models have been used successfully for parametric design, synthesis of dynamical models, and development of control laws. This review considers the role of mathematical modeling in several traditional and emerging areas for electrostatic MEMS: 1) analysis of pull-in, 2) effects of parasitics, 3) parametric resonance, 4) movable gate transistor or NEMFETs, and 5) repulsive actuation.
Development of a DNA Microarray for Enterococcal Species, Virulence, and Antibiotic Resistance Gene Determinations among Isolates from Poultry
Authors: Champagne J. , Diarra M. S. , Rempel H. , Topp E. , Greer C. W. , Harel J. , Masson L.
Published: February 2011

A DNA microarray (Enteroarray) was designed with probes targeting four species-specific taxonomic identifiers to discriminate among 18 different enterococcal species, while other probes were designed to identify 18 virulence factors and 174 antibiotic resistance genes. In total, 262 genes were utilized for rapid species identification of enterococcal isolates, while characterizing their virulence potential through the simultaneous identification of endogenous antibiotic resistance and virulence genes. Enterococcal isolates from broiler chicken farms were initially identified by using the API 20 Strep system, and the results were compared to those obtained with the taxonomic genes
atpA
,
recA
,
pheS
, and
ddl
represented on our microarray. Among the 171 isolates studied, five different enterococcal species were identified by using the API 20 Strep system:
Enterococcus faecium
,
E. faecalis
,
E. durans
,
E. gallinarum
, and
E. avium
. The Enteroarray detected the same species as API 20 Strep, as well as two more:
E. casseliflavus
and
E. hirae
. Species comparisons resulted in 15% (27 isolates) disagreement between the two methods among the five API 20 Strep identifiable species and 24% (42 isolates) disagreement when considering the seven Enteroarray identified species. The species specificity of key antibiotic and virulence genes identified by the Enteroarray were consistent with the literature adding further robustness to the redundant taxonomic probe data. Sequencing of the
cpn60
gene further confirmed the complete accuracy of the microarray results. The new Enteroarray should prove to be a useful tool to accurately genotype strains of enterococci and assess their virulence potential.
Archaeal Populations in Hypersaline Sediments Underlying Orange Microbial Mats in the Napoli Mud Volcano
Authors: Lazar Cassandre Sara , L'Haridon Stéphane , Pignet Patricia , Toffin Laurent
Published: February 2011

Microbial mats in marine cold seeps are known to be associated with ascending sulfide- and methane-rich fluids. Hence, they could be visible indicators of anaerobic oxidation of methane (AOM) and methane cycling processes in underlying sediments. The Napoli mud volcano is situated in the Olimpi Area that lies on saline deposits; from there, brine fluids migrate upward to the seafloor. Sediments associated with a brine pool and microbial orange mats of the Napoli mud volcano were recovered during the Medeco cruise. Based on analysis of RNA-derived sequences, the “active” archaeal community was composed of many uncultured lineages, such as rice cluster V or marine benthic group D. Function methyl coenzyme M reductase (
mcrA
) genes were affiliated with the anaerobic methanotrophic
Archaea
(ANME) of the ANME-1, ANME-2a, and ANME-2c groups, suggesting that AOM occurred in these sediment layers. Enrichment cultures showed the presence of viable marine methylotrophic
Methanococcoides
in shallow sediment layers. Thus, the archaeal community diversity seems to show that active methane cycling took place in the hypersaline microbial mat-associated sediments of the Napoli mud volcano.
d
-2,3-Butanediol Production Due to Heterologous Expression of an Acetoin Reductase in Clostridium acetobutylicum
Authors: Siemerink Marco A. J. , Kuit Wouter , López Contreras Ana M. , Eggink Gerrit , van der Oost John , Kengen Servé W. M.
Published: February 2011

Acetoin reductase (ACR) catalyzes the conversion of acetoin to 2,3-butanediol. Under certain conditions,
Clostridium acetobutylicum
ATCC 824 (and strains derived from it) generates both
d
- and
l
-stereoisomers of acetoin, but because of the absence of an ACR enzyme, it does not produce 2,3-butanediol. A gene encoding ACR from
Clostridium beijerinckii
NCIMB 8052 was functionally expressed in
C. acetobutylicum
under the control of two strong promoters, the constitutive
thl
promoter and the late exponential
adc
promoter. Both ACR-overproducing strains were grown in batch cultures, during which 89 to 90% of the natively produced acetoin was converted to 20 to 22 mM
d
-2,3-butanediol. The addition of a racemic mixture of acetoin led to the production of both
d
-2,3-butanediol and
meso
-2,3-butanediol. A metabolic network that is in agreement with the experimental data is proposed. Native 2,3-butanediol production is a first step toward a potential homofermentative 2-butanol-producing strain of
C. acetobutylicum
.
Acid Stress-Mediated Metabolic Shift in Lactobacillus sanfranciscensis LSCE1
Authors: Serrazanetti Diana I. , Ndagijimana Maurice , Sado-Kamdem Sylvain L. , Corsetti Aldo , Vogel Rudi F. , Ehrmann Matthias , Guerzoni M. Elisabetta
Published: February 2011

Lactobacillus sanfranciscensis
LSCE1 was selected as a target organism originating from recurrently refreshed sourdough to study the metabolic rerouting associated with the acid stress exposure during sourdough fermentation. In particular, the acid stress induced a metabolic shift toward overproduction of 3-methylbutanoic and 2-methylbutanoic acids accompanied by reduced sugar consumption and primary carbohydrate metabolite production. The fate of labeled leucine, the role of different nutrients and precursors, and the expression of the genes involved in branched-chain amino acid (BCAA) catabolism were evaluated at pH 3.6 and 5.8. The novel application of the program XCMS to the solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) data allowed accurate separation and quantification of 2-methylbutanoic and 3-methylbutanoic acids, generally reported as a cumulative datum. The metabolites coming from BCAA catabolism increased up to seven times under acid stress. The gene expression analysis confirmed that some genes associated with BCAA catabolism were overexpressed under acid conditions. The experiment with labeled leucine showed that 2-methylbutanoic acid originated also from leucine. While the overproduction of 3-methylbutanoic acid under acid stress can be attributed to the need to maintain redox balance, the rationale for the production of 2-methylbutanoic acid from leucine can be found in a newly proposed biosynthesis pathway leading to 2-methylbutanoic acid and 3 mol of ATP per mol of leucine. Leucine catabolism to 3-methylbutanoic and 2-methylbutanoic acids suggests that the switch from sugar to amino acid catabolism supports growth in
L. sanfranciscensis
in restricted environments such as sourdough characterized by acid stress and recurrent carbon starvation.
Genomic Potential of Marinobacter aquaeolei, a Biogeochemical “Opportunitroph”
Authors: Singer Esther , Webb Eric A. , Nelson William C. , Heidelberg John F. , Ivanova Natalia , Pati Amrita , Edwards Katrina J.
Published: February 2011

The genus of
Marinobacter
is one of the most ubiquitous in the global oceans and assumed to significantly impact various biogeochemical cycles. The genome structure and content of
Marinobacter aquaeolei
VT8 was analyzed and compared with those from other organisms with diverse adaptive strategies. Here, we report the many “opportunitrophic” genetic characteristics and strategies that
M. aquaeolei
has adopted to promote survival under various environmental conditions. Genome analysis revealed its metabolic potential to utilize oxygen and nitrate as terminal electron acceptors, iron as an electron donor, and urea, phosphonate, and various hydrocarbons as alternative N, P, and C sources, respectively. Miscellaneous sensory and defense mechanisms, apparently acquired via horizontal gene transfer, are involved in the perception of environmental fluctuations and antibiotic, phage, toxin, and heavy metal resistance, enabling survival under adverse conditions, such as oil-polluted water. Multiple putative integrases, transposases, and plasmids appear to have introduced additional metabolic potential, such as phosphonate degradation. The genomic potential of
M. aquaeolei
and its similarity to other opportunitrophs are consistent with its cosmopolitan occurrence in diverse environments and highly variable lifestyles.
Biofilm Formation by and Thermal Niche and Virulence Characteristics of Escherichia spp
Authors: Ingle Danielle J. , Clermont Olivier , Skurnik David , Denamur Erick , Walk Seth T. , Gordon David M.
Published: February 2011

In order to better understand the ecological and virulence characteristics of the various clades of
Escherichia
,
in vitro
and
in vivo
experiments were undertaken. Members of the recently described cryptic clades of
Escherichia
(clades III, IV, and V) were found to have an enhanced ability to form biofilms compared to strains of
Escherichia coli
,
E. fergusonii
, or
E. albertii
. Members of the cryptic clades were also able to replicate at a lower temperature (5°C versus 11°C) than strains of the named species of
Escherichia
. Neither a strain's maximal growth rate nor its optimal temperature for growth varied with respect to the strain's phylogenetic affiliation.
Escherichia
strains not belonging to the species
E. coli
were positive for a mix of traits thought to enhance a strain's ability to cause either intestinal or extraintestinal disease. However, no non-
E. coli
Escherichia
strain was virulent in a mouse model of extraintestinal infection. The frequency of resistance to antibiotics was low, and none of the strains tested harbored class 1, 2, or 3 integrons. The results of these experiments support the hypothesis that members of the cryptic
Escherichia
clades may be better able to persist in the external environment compared to
E. coli
,
E. fergusonii
, or
E. albertii
, isolates.
Influence of Temperature and Backslopping Time on the Microbiota of a Type I Propagated Laboratory Wheat Sourdough Fermentation
Authors: Vrancken Gino , Rimaux Tom , Weckx Stefan , Leroy Frédéric , De Vuyst Luc
Published: February 2011

Sourdough fermentation is a cereal fermentation that is characterized by the formation of stable yeast/lactic acid bacteria (LAB) associations. It is a unique process among food fermentations in that the LAB that mostly dominate these fermentations are heterofermentative. In the present study, four wheat sourdough fermentations were carried out under different conditions of temperature and backslopping time to determine their effect on the composition of the microbiota of the final sourdoughs. A substantial effect of temperature was observed. A fermentation with 10 backsloppings (once every 24 h) at 23°C resulted in a microbiota composed ofLeuconostoc citreumas the dominant species, whereas fermentations at 30 and 37°C with backslopping every 24 h resulted in ecosystems dominated byLactobacillus fermentum. Longer backslopping times (every 48 h at 30°C) resulted in a combination ofLactobacillus fermentumandLactobacillus plantarum. Residual maltose remained present in all fermentations, except those with longer backslopping times, and ornithine was found in almost all fermentations, indicating enhanced sourdough-typical LAB activity. The sourdough-typical speciesLactobacillus sanfranciscensiswas not found. Finally, a nonflour origin for this species was hypothesized.
Screening for Antimicrobial Resistance Genes and Virulence Factors via Genome Sequencing
Authors: Bennedsen Mads , Stuer-Lauridsen Birgitte , Danielsen Morten , Johansen Eric
Published: February 2011

Second-generation genome sequencing and alignment of the resulting reads to
in silico
genomes containing antimicrobial resistance and virulence factor genes were used to screen for undesirable genes in 28 strains which could be used in human nutrition. No virulence factor genes were detected, while several isolates contained antimicrobial resistance genes.
Activity and Diversity of Methanotrophic Bacteria at Methane Seeps in Eastern Lake Constance Sediments
Authors: Deutzmann Jörg S. , Wörner Susanne , Schink Bernhard
Published: February 2011

The activity and community structure of aerobic methanotrophic communities were investigated at methane seeps (pockmarks) in the littoral and profundal zones of an oligotrophic freshwater lake (Lake Constance, Germany). Measurements of potential methane oxidation rates showed that sediments inside littoral pockmarks are hot spots of methane oxidation. Potential methane oxidation rates at littoral pockmark sites exceeded the rates of the surrounding sediment by 2 orders of magnitude. Terminal restriction fragment length polymorphism (T-RFLP) analysis of the
pmoA
gene revealed major differences in the methanotrophic community composition between littoral pockmarks and the surrounding sediments. Clone library analysis confirmed that one distinct
Methylobacter
-related group dominates the community at littoral pockmarks. In profundal sediments, the differences between pockmarks and surrounding sediments were found to be less pronounced.
Evolution of Mating within the Candida parapsilosis Species Group
Authors: Sai Sixiang , Holland Linda M. , McGee Conor F. , Lynch Denise B. , Butler Geraldine
Published: February 2011

Candida orthopsilosis
and
Candida metapsilosis
are closely related to
Candida parapsilosis
, a major cause of infection in premature neonates. Mating has not been observed in these species. We show that ∼190 isolates of
C. parapsilosis
contain only an
MTL
a
idiomorph at the mating-type-like locus. Here, we describe the isolation and characterization of the
MTL
loci from
C. orthopsilosis
and
C. metapsilosis
. Among 16
C. orthopsilosis
isolates, 9 were homozygous for
MTL
a
, 5 were homozygous for
MTL
α, and 2 were
MTL
a
/α heterozygotes. The
C. orthopsilosis
isolates belonged to two divergent groups, as characterized by restriction patterns at
MTL
, which probably represent subspecies. We sequenced both idiomorphs from each group and showed that they are 95% identical and that the regulatory genes are intact. In contrast, 18 isolates of
C. metapsilosis
contain only
MTL
α idiomorphs. Our results suggest that the role of
MTL
in determining cell type is being eroded in the
C. parapsilosis
species complex. The population structure of
C. orthopsilosis
indicates that mating may occur. However, expression of genes in the mating signal transduction pathway does not respond to exposure to alpha factor.
C. parapsilosis
is also nonresponsive, even when the GTPase-activating protein gene
SST2
is deleted. In addition, splicing of introns in
MTL
a
1
and
MTL
a
2
is defective in
C. orthopsilosis
. Mating is not detected. The alpha factor peptide, which is the same sequence in
C. parapsilosis
,
C. orthopsilosis
, and
C. metapsilosis
, can induce a mating response in
Candida albicans
. It is therefore likely either that mating of
C. orthopsilosis
takes place under certain unidentified conditions or that the mating pathway has been adapted for other functions, such as cross-species communication.
Degeneration in Codon Usage within the Region of Suppressed Recombination in the Mating-Type Chromosomes of Neurospora tetrasperma
Authors: Whittle C. A. , Sun Y. , Johannesson H.
Published: February 2011

The origin and early evolution of sex chromosomes are currently poorly understood. The
Neurospora tetrasperma
mating-type (
mat
) chromosomes have recently emerged as a model system for the study of early sex chromosome evolution, since they contain a young (<6 million years ago [Mya]), large (>6.6-Mb) region of suppressed recombination. Here we examined preferred-codon usage in 290 genes (121,831 codon positions) in order to test for early signs of genomic degeneration in
N. tetrasperma
mat
chromosomes. We report several key findings about codon usage in the region of recombination suppression, including the following: (i) this region has been subjected to marked and largely independent degeneration among gene alleles; (ii) the level of degeneration is magnified over longer periods of recombination suppression; and (iii) both
mat a
and
mat A
chromosomes have been subjected to deterioration. The frequency of shifts from preferred codons to nonpreferred codons is greater for shorter genes than for longer genes, suggesting that short genes play an especially significant role in early sex chromosome evolution. Furthermore, we show that these degenerative changes in codon usage are best explained by altered selection efficiency in the recombinationally suppressed region. These findings demonstrate that the fungus
N. tetrasperma
provides an effective system for the study of degenerative genomic changes in young regions of recombination suppression in sex-regulating chromosomes.
The Gα Subunit Signals through the Ste50 Protein during the Mating Pheromone Response in the Yeast Kluyveromyces lactis
Authors: Sánchez-Paredes Edith , Kawasaki Laura , Ongay-Larios Laura , Coria Roberto
Published: February 2011

Yeast mating signal transduction pathways require a heterotrimeric G protein composed of Gα, Gβ, and Gγ subunits connected to a mitogen-activated protein kinase (MAPK) module. While in
Saccharomyces cerevisiae
elimination of Gα induces constitutive activation of the mating pathway, in
Kluyveromyces lactis
it produces partial sterility, which indicates that
K. lactis
Gα (KlGα) is required to positively activate mating. We use physical interaction experiments to determine that KlGα interacts with the adaptor protein KlSte50p. The Ras association (RA) domain of KlSte50p favored interaction with the GDP-bound KlGα subunit, and when the KlGα protein is constitutively activated, the interaction drops significantly. Additionally, KlSte50p strongly associates with the MAPK kinase kinase (MAPKKK) KlSte11p through its sterile alpha motif (SAM) domain. Genetic experiments placed KlSte50p downstream of the G protein α subunit, indicating that KlGα may stimulate the mating pathway via KlSte50p. Fusion of KlSte50p to the KlGβ subunit partially eliminated the requirement of KlGα for mating, indicating that one contribution of KlGα to the mating pathway is to facilitate plasma membrane anchoring of KlSte50p.
Sch9 Kinase Integrates Hypoxia and CO
2
Sensing To Suppress Hyphal Morphogenesis in Candida albicans
Authors: Stichternoth Catrin , Fraund Alida , Setiadi Eleonora , Giasson Luc , Vecchiarelli Anna , Ernst Joachim F.
Published: February 2011

The yeast-hypha transition is an important virulence trait of
Candida albicans
. We report that the AGC kinase Sch9 prevents hypha formation specifically under hypoxia at high CO
2
levels.
sch9
mutants showed no major defects in growth and stress resistance but a striking hyperfilamentous phenotype under hypoxia (<10% O
2
), although only in the presence of elevated CO
2
levels (>1%) and at temperatures of <37°C during surface growth. The
sch9
hyperfilamentous phenotype was independent of Rim15 kinase and was recreated by inhibition of Tor1 kinase by rapamycin or caffeine in a wild-type strain, suggesting that Sch9 suppression requires Tor1. Caffeine inhibition also revealed that both protein kinase A isoforms, as well as transcription factors Czf1 and Ace2, are required to generate the
sch9
mutant phenotype. Transcriptomal analyses showed that Sch9 regulates most genes solely under hypoxia and in the presence of elevated CO
2
. In this environment, Sch9 downregulates genes encoding cell wall proteins and nutrient transporters, while under normoxia Sch9 and Tor1 coregulate a minor fraction of Sch9-regulated genes, e.g., by inducing glycolytic genes. Other than in
Saccharomyces cerevisiae
, both
sch9
and
rim15
mutants showed decreased chronological aging under normoxia but not under hypoxia, indicating significant rewiring of the Tor1-Sch9-Rim15 pathway in
C. albicans
. The results stress the importance of environmental conditions on Sch9 function and establish a novel response circuitry to both hypoxia and CO
2
in
C. albicans
, which suppresses hypha formation but also allows efficient nutrient uptake, metabolism, and virulence.
Organic Hydroperoxide Resistance Protein and Ergothioneine Compensate for Loss of Mycothiol in Mycobacterium smegmatis Mutants
Authors: Ta Philong , Buchmeier Nancy , Newton Gerald L. , Rawat Mamta , Fahey Robert C.
Published: February 2011

The
mshA
::Tn
5
mutant of
Mycobacterium smegmatis
does not produce mycothiol (MSH) and was found to markedly overproduce both ergothioneine and an ∼15-kDa protein determined to be organic hydroperoxide resistance protein (Ohr). An
mshA
(
G32D
) mutant lacking MSH overproduced ergothioneine but not Ohr. Comparison of the mutant phenotypes with those of the wild-type strain indicated the following: Ohr protects against organic hydroperoxide toxicity, whereas ergothioneine does not; an additional MSH-dependent organic hydroperoxide peroxidase exists; and elevated isoniazid resistance in the mutant is associated with both Ohr and the absence of MSH. Purified Ohr showed high activity with linoleic acid hydroperoxide, indicating lipid hydroperoxides as the likely physiologic targets. The reduction of oxidized Ohr by NADH was shown to be catalyzed by lipoamide dehydrogenase and either lipoamide or DlaT (SucB). Since free lipoamide and lipoic acid levels were shown to be undetectable in
M. smegmatis
, the bound lipoyl residues of DlaT are the likely source of the physiological dithiol reductant for Ohr. The pattern of occurrence of homologs of Ohr among bacteria suggests that the
ohr
gene has been distributed by lateral transfer. The finding of multiple Ohr homologs with various sequence identities in some bacterial genomes indicates that there may be multiple physiologic targets for Ohr proteins.
Insight into Bacterial Phosphotransferase System-Mediated Signaling by Interspecies Transplantation of a Transcriptional Regulator
Authors: Bahr Thomas , Lüttmann Denise , März Walter , Rak Bodo , Görke Boris
Published: February 2011

The bacterial sugar:phosphotransferase system (PTS) delivers phosphoryl groups via proteins EI and HPr to the EII sugar transporters. The antitermination protein LicT controls β-glucoside utilization in
Bacillus subtilis
and belongs to a family of bacterial transcriptional regulators that are antagonistically controlled by PTS-catalyzed phosphorylations at two homologous PTS regulation domains (PRDs). LicT is inhibited by phosphorylation of PRD1, which is mediated by the β-glucoside transporter EII
Bgl
. Phosphorylation of PRD2 is catalyzed by HPr and stimulates LicT activity. Here, we report that LicT, when artificially expressed in the nonrelated bacterium
Escherichia coli
, is likewise phosphorylated at both PRDs, but the phosphoryl group donors differ. Surprisingly,
E. coli
HPr phosphorylates PRD1 rather than PRD2, while the stimulatory phosphorylation of PRD2 is carried out by the HPr homolog NPr. This demonstrates that subtle differences in the interaction surface of HPr can switch its affinities toward the PRDs. NPr transfers phosphoryl groups from EI
Ntr
to EIIA
Ntr
. Together these proteins form the paralogous PTS
Ntr
, which controls the activity of K
+
transporters in response to unknown signals. This is achieved by binding of dephosphorylated EIIA
Ntr
to other proteins. We generated LicT mutants that were controlled either negatively by HPr or positively by NPr and were suitable bio-bricks, in order to monitor or to couple gene expression to the phosphorylation states of these two proteins. With the aid of these tools, we identified the stringent starvation protein SspA as a regulator of EIIA
Ntr
phosphorylation, indicating that PTS
Ntr
represents a stress-related system in
E. coli
.
Spectrophotometric determination of atorvastatin and amlodipine by H-point standard addition method with simultaneous addition of both analytes in nonaqueous solution
Authors: Ahmadi Farhad , Ramin Ghordoie-Milan
Published: February 2011

H-point standard addition method(HPSAM) with simultaneous addition of both analytes in nonaqueous solution was applied for determination of Atorvastatin (AT) and Amlodipine (AML). The results showed that simultaneous determination could be performed with the ratio 0.16 to 4.3 of AT–AML. The corresponding values of LOD were obtained for AT and AML 1.2 × 10–6 and 9 × 10–7 mol l–1, respectively, and the corresponding values of LOQ were obtained for AT and AML 4 × 10–6 and 3 × 10–6 mol l–1, respectively. Underworking conditions, the proposed method was successfully applied for simultaneous determination of AT and AML in several synthetic mixtures and Amostatine tablets.
Observations of caregiver supervision of children at beaches: identification of factors associated with high supervision
Authors: Petrass Lauren A , Blitvich Jennifer D , Finch Caroline F
Published: February 2011

Objective

To identify independent factors associated with caregiver supervision levels at beaches.

Methods

Children (aged 1–14 years) engaged in beach play and their caregivers were observed at Australian beaches during September–April, 2008/09. Caregiver, child, and environmental factor data were collected and recorded on a validated observation instrument. The main outcome of interest was a continuous measure of supervision. After adjusting for potential clustering by beach/state, multivariable linear regression was used to identify independent factors associated with caregiver supervision.

Results

Four independent predictors of supervision and one interaction effect (child age by the caregiver and child position on beach) were identified. Caregivers who were supervising from a different position to where the child was playing were less likely to provide high supervision, as were older caregivers (>35 years) compared to younger caregivers (≤34 years). Compared to children playing alone, children playing with one, or two or more others were less likely to receive high supervision, and children aged 1–4 years were likely to receive higher supervision than older children.

Conclusion

This study provides new knowledge about underlying factors associated with the level of caregiver supervision in beach settings. Future studies should continue to explore independent predictors of supervision so that effective programmes, which focus on caregiver supervision, can be targeted to address poor supervision practices.
Strong's objections to the future of value account
Authors: Marquis Don
Published: February 2011

According to Carson Strong, the future of value account of the wrongness of killing is subject to counterexamples. Ezio Di Nucci has disagreed. Their disagreement turns on whether the concepts of a future of value and a future like ours are equivalent. Unfortunately, both concepts are fuzzy, which explains, at least in part, the disagreement. I suggest that both concepts can be clarified in ways that seem plausible and that makes them equivalent. Strong claims that better accounts of the wrongness of killing exist. I show that those alternative accounts are unsatisfactory.
Conscientious refusals to refer: findings from a national physician survey
Authors: Combs Michael P , Antiel Ryan M , Tilburt Jon C , Mueller Paul S , Curlin Farr A
Published: February 2011

Background

Regarding controversial medical services, many have argued that if physicians cannot in good conscience provide a legal medical intervention for which a patient is a candidate, they should refer the requesting patient to an accommodating provider. This study examines what US physicians think a doctor is obligated to do when the doctor thinks it would be immoral to provide a referral.

Method

The authors conducted a cross-sectional survey of a random sample of 2000 US physicians from all specialties. The primary criterion variable was agreement that physicians have a professional obligation to refer patients for all legal medical services for which the patients are candidates, even if the physician believes that such a referral is immoral.

Results

Of 1895 eligible physicians, 1032 (55%) responded. 57% of physicians agreed that doctors must refer patients regardless of whether or not the doctor believes the referral itself is immoral. Holding this opinion was independently associated with being more theologically pluralistic, describing oneself as sociopolitically liberal, and indicating that respect for patient autonomy is the most important bioethical principle in one's practice (multivariable ORs, 1.6–2.4).

Conclusions

Physicians are divided about a professional obligation to refer when the physician believes that referral itself is immoral. These data suggest there is no uncontroversial way to resolve conflicts posed when patients request interventions that their physicians cannot in good conscience provide.
Embolization of intracranial aneurysms with second-generation Matrix-2 detachable coils: mid-term and long-term results
Authors: Ansari Sameer A , Dueweke Eric J , Kanaan Yassine , Chaudhary Neeraj , Gandhi Dheeraj , Thompson B Gregory , Gemmete Joseph J
Published: February 2011

Background

Bioactive polyglycolic/polylactic acid (PGLA)-coated Matrix detachable coils were reported to incite intra-aneurysmal inflammation and fibrosis. Multiple large case series with Matrix-1 coils have shown no advantage with respect to aneurysm recurrence. Second-generation Matrix-2 coils were designed with improved platinum support and reduced copolymer friction. We assessed the safety and efficacy of Matrix-2 coil embolization.

Methods

84 aneurysms were embolized primarily with Matrix-2 coils. Anatomic results were evaluated using a modified Raymond scale with progressive occlusion or recanalization/recurrence strictly defined as any interval change in intra-aneurysmal opacification.

Results

Mid-term (8.9±3.4 months) and long-term (23.0±7.4 months) follow-up was available for 65 aneurysms. At mid-term, 55 (85%) aneurysms remained stable (or progressed to occlusion) versus 10 (15%) recurrent aneurysms, 7 (11%) requiring retreatment. At long term, 49 (75%) aneurysms remained stable versus 16 (25%) recurrent aneurysms, 12 (18%) requiring retreatment. Statistically significant factors affecting recanalization included ruptured aneurysms 9/20 (45%), large aneurysms 5/8 (71%), post-procedure residual aneurysms 6/12 (50%) and differential coil packing density of recurrent (21%) versus stable (28%) aneurysms. Patient morbidity (5%) was limited to thromboembolic complications (n=4) or aneurysm rerupture (n=1). Patient mortality (5%) was secondary to subarachnoid hemorrhage complications (n=4) with no procedure-related deaths (0%).

Conclusion

Coil embolization with Matrix-2 coils is safe and effective, preventing recanalization in small aneurysms at mid-term. Although these aneurysm recurrence rates initially appeared lower than previous reports with Matrix-1 or platinum coils, significant late recanalization was observed on long-term follow-up. We postulate that any derived benefit from Matrix-2 coils is directly dependent on post-procedure outcomes and coil packing density.
Novel use of prasugrel for intracranial stent thrombosis: Figure 1
Authors: Leslie-Mazwi Thabele M , Chandra Ronil V , Oh Daniel C , Nogueira Raul G
Published: February 2011

Dual antiplatelet therapy is established for prevention of stent thrombosis in cardiac patients, and widely utilized in neurointerventional stent cases. Aspirin and clopidogrel are typically synergistic. We present a case of clopidogrel resistance due to genetic polymorphism resulting in acute stent thrombosis during elective stent-assisted coiling, with novel use of prasugrel as an alternative platelet inhibitor in the neurovascular setting.
‘One cigarette for you and one for me’: children of smoking and non-smoking parents during pretend play
Authors: de Leeuw Rebecca N H , Verhagen Maaike , de Wit Cindy , Scholte Ron H J , Engels Rutger C M E
Published: February 2011

Objective

To investigate whether perceived parental smoking is related to pretend smoking in young children and whether children influence each other in pretend smoking.

Methods

Children who reported to have at least one smoking parent were coupled with children who had non-smoking parents. Both children were then asked to pretend that they were adults having a barbeque party. During their role playing, the children were observed in order to assess their pretend smoking behaviours and to examine whether children of smoking parents were more likely to initiate pretend smoking. Children were tested at their schools; the sample consisted of 206 children between 4 and 7 years of age (mean age=5.14, SD=0.87), of which 54.4% were girls. The main outcome was whether a child pretended to be smoking and whether the child initiated or followed the other child in this behaviour.

Results

During their play, 63.6% (n=131) of the children pretended to smoke. Children of smoking parents were more likely to initiate pretend smoking than to follow.

Conclusions

Through their own smoking, parents appear to be able to influence the way in which their children interact with peers regarding pretend smoking. More specifically, children of smoking parents might instigate smoking among their peers.
CLOSURES IN FORMAL LANGUAGES AND KURATOWSKI'S THEOREM
Authors: BRZOZOWSKI JANUSZ , GRANT ELYOT , SHALLIT JEFFREY
Published: February 2011

A famous theorem of Kuratowski states that, in a topological space, at most 14 distinct sets can be produced by repeatedly applying the operations of closure and complement to a given set. We re-examine this theorem in the setting of formal languages, where by "closure" we mean either Kleene closure or positive closure. We classify languages according to the structure of the algebras they generate under iterations of complement and closure. There are precisely 9 such algebras in the case of positive closure, and 12 in the case of Kleene closure. We study how the properties of being open and closed are preserved under concatenation. We investigate analogues, in formal languages, of the separation axioms in topological spaces; one of our main results is that there is a clopen partition separating two words if and only if the words do not commute. We can decide in quadratic time if the language specified by a DFA is closed, but if the language is specified by an NFA, the problem is PSPACE-complete.
Tata Steel: Financing the Corus Acquisition
Authors: Vishwanath S. R.
Published: February 2011

Tata Steel announced the acquisition of Corus group in October 2006. After a prolonged bidding war with the Brazilian steelmaker CSN, Tata Steel purchased Corus group for about $13b. The case considers the financing package put together by Tata Steel to fund the Corus acquisition. Students are asked to value the different securities offered and evaluate the financing package.

This case can be used in a Corporate Finance course in a module on Financing or in a Mergers and Acquisitions course or in a Financial Instruments and Markets course. The case has the following objectives:

1. To introduce students to the characteristics of preferred stocks and convertible instruments.

2. To consider the factors relevant to the selection of different types of securities in financing.

3. To introduce concepts like dilution, leverage, debt capacity.

4. To introduce credit ratings.

5. To introduce valuation of contingent claims.

6. To build skills in designing and implementing an integrated acquisition and financing strategy.

Instructors teaching this case could consider teaching Tata Steel (A): The Bid for Corus case first although these cases can be taught independently.
Effect of Annealing on Optical Absorption of LaAlO3 at Terahertz Frequencies
Authors: Nomura Ken-ichi , Okami Shimpei , Xie Xiaojun , Mizuno Maya , Fukunaga Kaori , Ohki Yoshimichi
Published: February 2011

Absorption spectra of LaAlO3(100) single crystals were measured at frequencies from 1.0 to 3.5 THz. A new absorption peak appears at ∼3.0 THz after annealing at temperatures above 500 °C. Simultaneously, striped domains with widths ranging from about 20 to about 300 µm in the original samples completely disappeared. Since oxygen vacancies are assumed to play an important role in the formation of domains, the absorption peak at ∼3.0 THz seems to be related to oxygen vacancies.
First-Principles Study on Structural Properties of GeO2 and SiO2 under Compression and Expansion Pressure
Authors: Saito Shoichiro , Ono Tomoya
Published: February 2011

The detailed analysis of the structural variations of three GeO2 and SiO2 polymorphs (α-quartz, α-cristobalite, and rutile) under compression and expansion pressure is reported. First-principles total-energy calculations reveal that the rutile structure is the most stable phase among the phases of GeO2, while SiO2 preferentially forms quartz. GeO4 tetrahedras of quartz and cristobalite GeO2 phases at the equilibrium volume are more significantly distorted than those of SiO2. Moreover, in the case of quartz GeO2 and cristobalite GeO2, all O–Ge–O bond angles vary when the volume of the GeO2 bulk changes from the equilibrium point, which causes further deformation of tetrahedra. In contrast, the tilt angle formed by Si–O–Si in SiO2 markedly changes. This flexibility of the O–Ge–O bonds reduces the stress at the Ge/GeO2 interface due to the lattice-constant mismatch and results in the low defective interface observed in the experiments [Matsubara et al.: Appl. Phys. Lett. 93 (2008) 032104; Hosoi et al.: Appl. Phys. Lett. 94 (2009) 202112].
Effects of Surface Free Energy on Orientational Assembly of Hexaazatrinaphtalene-Based Discotic Mesogen in Sandwich-Type Structure
Authors: Zheng Wenjun , Chiang Cheng-Yan , Hu Ya-Ting , Ong Chi Wi
Published: February 2011

The molecular stacking of a hexaazatrinaphtalene-based discogen sandwiched between two flat glass substrates has been studied. The surface free energy of the substrates was found to significantly influence the way the discotic molecules anchor on the surface. The surface free energy of the substrates was changed by means of O2 plasma buffing. The discotic molecules tend to anchor with their disc-face toward the substrates with high surface free energy, and the other molecules stack on to form the homeotropically aligned columnar phase. A decrease in the surface free energy of the substrate leads to the discotic columns tilting away from the normal to the substrate.
High-Speed Imaging of Broadband Multiplex Coherent Anti-Stokes Raman Scattering Microscopy Using a Supercontinuum Source
Authors: Choi Dae Sik , Lee Jang Hyuk , Oh Myoung-Kyu , Eom Tae Jung , Kim Hoon Sup , Kang Hoon Soo , Ko Do-Kyeong
Published: February 2011

We combined broadband multiplex coherent anti-Stokes Raman scattering (CARS) microspectroscopy with CARS microscopy using a femtosecond laser and a photonic crystal fiber. Broadband multiplex CARS microspectroscopy, which simultaneously measures broadband range (including significant Raman vibrational modes) from 500 to 3500 cm-1at a high spectral resolution was subsequently performed. Also, via multiplex CARS microscopy using a pair of galvanometer mirrors we successfully demonstrated the high-speed imaging of polymer beads and a lily pollen grain for the study of cell biology dynamics. The imaging speed was 37 s per image, which is 30–40 times faster than that previously reported in broadband CARS microscopy.
Bending Effects of Thermally-Expanded-Core Fiber and Its Application as Variable Optical Attenuator
Authors: Kwon Hyung Woo , Song Jae Won , Kim Kwang Taek
Published: February 2011

This study examined the bending effects of a thermally-expanded-core (TEC) fiber for an application as an in-line variable optical attenuator (VOA). The effects of the structural parameters of the TEC fiber and the refractive index of the external medium surrounding the clad layer on the bending loss are experimentally investigated and the device structure and fabrication process of the VOA are presented. The desired attenuation is obtained by mechanical bending of the TEC fiber. A wide range of attenuation exceeding 55 dB and low excess loss of <0.2 dB at 1550 nm are achieved.
Effect of O- Ion Beam Irradiation during RF-Magnetron Sputtering on Characteristics of CoFeB–MgO Magnetic Tunnel Junctions
Authors: Ono Kazunaga , Ohshima Norikazu , Goto Kazuya , Yamamoto Hiroki , Morita Tadashi , Kinoshita Keizo , Ishijima Tatsuo , Toyoda Hirotaka
Published: February 2011

The relevance between electrical properties of CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) and the crystalline orientation of MgO layer was investigated within a large-scale substrate. The tunnel magnetoresistance characteristics and the resistance-area product in CoFeB/MgO/CoFeB MTJs are degraded by deterioration of the crystalline orientation of MgO layer, which depends on sputtering conditions. That deterioration originates from damage caused by high-energy oxygen negative-ion irradiation during RF-magnetron sputtering of the MgO layer.
Influence of Surrounding Dielectrics on the Data Retention Time of Doped Sb2Te Phase Change Material
Authors: Jedema Friso , Zandt Micha in `t , Wolters Rob , Gravesteijn Dirk
Published: February 2011

The crystallization properties of as-deposited and laser written amorphous marks of doped Sb2Te phase change material are found to be only dependent on the top dielectric layer. A ZnS:SiO2 top dielectric layer yields a higher crystallization temperature and a larger crystal growth activation energy as compared to a SiO2 top dielectric layer, leading to superior data retention times at ambient temperatures. The observed correlation between the larger crystallization temperatures and larger crystal growth activation energies indicates that the viscosity of the phase change material in the amorphous state is dependent on the interfacial energy between the phase change material and the top dielectric layer.
A 128×96 Pixel Stack-Type Color Image Sensor: Stack of Individual Blue-, Green-, and Red-Sensitive Organic Photoconductive Films Integrated with a ZnO Thin Film Transistor Readout Circuit
Authors: Seo Hokuto , Aihara Satoshi , Watabe Toshihisa , Ohtake Hiroshi , Sakai Toshikatsu , Kubota Misao , Egami Norifumi , Hiramatsu Takahiro , Matsuda Tokiyoshi , Furuta Mamoru , Hirao Takashi
Published: February 2011

A color image was produced by a vertically stacked image sensor with blue (B)-, green (G)-, and red (R)-sensitive organic photoconductive films, each having a thin-film transistor (TFT) array that uses a zinc oxide (ZnO) channel to read out the signal generated in each organic film. The number of the pixels of the fabricated image sensor is 128×96 for each color, and the pixel size is 100×100 µm2. The current on/off ratio of the ZnO TFT is over 106, and the B-, G-, and R-sensitive organic photoconductive films show excellent wavelength selectivity. The stacked image sensor can produce a color image at 10 frames per second with a resolution corresponding to the pixel number. This result clearly shows that color separation is achieved without using any conventional color separation optical system such as a color filter array or a prism.
Selective Synthesis of SiC and SiOx Nanowires by Direct Microwave Irradiation
Authors: Oh Eugene , Jung Seung-Ho , Lee Jaegeun , Cho Seungho , Kim Hye-Jin , Lee Bo-Ram , Lee Kun-Hong , Song Kyong-Hwa , Choi Chi-Hoon , Han Do-Suck
Published: February 2011

We report a facile and novel method for the selective growth of SiC and SiO
x
nanowires by direct microwave irradiation on a Si substrate under atmospheric pressure. Selective synthesis of the amorphous SiO
x
or crystalline SiC nanowires was achieved by varying the gas composition in the reactor. The proposed method requires a short reaction time (2 min) with no need for vacuum equipment because the reaction is carried out under atmospheric pressure. High-resolution transmission electron microscope images revealed that the SiO
x
nanowires were amorphous and that the SiC nanowires were crystalline. Raman spectra showed features typical of nano-sized SiC. On the basis of our results, we propose a growth mechanism of SiC and SiO
x
nanowires synthesized by direct microwave irradiation.
Effect of Evaporation on Protein Crystals Grown in Semi-Solid Agarose Hydrogel
Authors: Sugiyama Shigeru , Hirose Mika , Shimizu Noriko , Niiyama Mayumi , Maruyama Mihoko , Sazaki Gen , Murai Ryota , Adachi Hiroaki , Takano Kazufumi , Murakami Satoshi , Inoue Tsuyoshi , Mori Yusuke , Matsumura Hiroyoshi
Published: February 2011

High-accuracy X-ray diffraction measurements of protein crystals are an important process to determine three-dimensional structures. Investigators must manipulate crystals in X-ray diffraction measurement. Protein crystals are exposed to evaporation during manipulation, and their exposure to evaporation for a long time causes serious damage. Recently, we have developed a novel technique of protein crystallization using a semi-solid agarose gel (SSAG), which demonstrated several desirable merits such as the growth of crystals with high quality, growth with a high nucleation rate, and the possibility of automated crystal capture. To further assess the merits of SSAG-grown crystals, we evaluated the effects of evaporation on the quality of SSAG-grown crystals using X-ray diffraction and subsequent structural analyses. The results demonstrate that the SSAG-grown crystals showed a high tolerance to evaporation, compared with the solution-grown crystals. These comparative experiments also demonstrate the practical advantages of efficient protection by the SSAG surrounding the protein crystals.