bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study of Artificial Features Attenuation in Rolling/Sliding Concentrated Contacts
Authors: Sperka Petr , Krupka Ivan , Hartl Martin
Published: February 2012

A surface roughness attenuation approach based on the Fourier decomposition of surface roughness into harmonic components may allow predictions of the behavior of real rough surfaces within concentrated contacts. Recently the simplified model for rolling/sliding conditions was suggested. A high pressure ball on disk tribometer was complemented by hi-speed digital camera with the aim to observe a progress of roughness feature pass through the contact. The experiments with artificial features were carried out under rolling/sliding conditions, evaluated by thin film colorimetric interferometry and compared with theory. Detail understanding of real roughness behavior inside contact under rolling/sliding conditions can have extensive impact on practical design of machine components.
A Comparative Study of Navier-Stokes Equation and Reynolds Equation in Simulating Spool Valve
Authors: Hong S. H. , Son S. I. , Kim K. W.
Published: February 2012

In order to maintain the accurate and precise movement of the actuator of the hydraulic systems, it is necessary to guarantee smooth function of the fluid flow control valves. Concerning hydraulic valves, the spool type directional control valve has particular lock problem. The hydraulic lock occurs when uneven pressure distribution surrounding the spool in the clearance between spool and sleeve causes the spool to move sideways out of its centered position. And the contact between spool and sleeve causes to increase friction and eventually, the spool is blocked inside the sleeve. To reduce the possibility of hydraulic lock, peripheral grooves balancing uneven pressure distribution in the radial clearance is commonly applied to spool. Reynolds equation is commonly used to investigate the lubrication characteristics of the spool valve. However, some of assumptions used in Reynolds equation are not valid when cavitation occurs or fluid inertia is significant in spool valve. So, the study on the applicability and precision of Reynolds equation for spool valve analysis is needed. In this study, the differences between the results from Navier-Stokes equation and Reynolds equation are compared when the cavitation is considered. Frictional forces, lateral forces and leakage flow rate with various aspect ratio of groove are calculated. Besides, when the number of groove is increased, the forces and leakage flow rate are compared. Based on the comparison the applicability of Reynolds equation in calculating the spool valve is also discussed.
On Polishing and Erosion of Aluminum Substrates by a Jet of Alumina Slurry
Authors: Patel Shreyansh , Mu¨ftu¨ Sinan
Published: February 2012

Polishing of a nominally flat aluminum substrate using a fluid jet, carrying abrasive particles, was investigated. The effects of jet orientation and polishing duration were studied, on a fixed spot on the aluminum substrate. Stylus profilometry was used to examine the final surface along different directions. It was seen that the final erosion contour is strongly dependent on the jet orientation. The surface roughness was found to be dependent on the slurry parameters. On average, the average roughness (Ra) of the aluminum surface was reduced from 430 nm to 139 nm. Best polishing was obtained with the jet orientation of 30°. The process was simulated by using computational fluid dynamics (CFD), and it was concluded that dynamic pressure is the main parameter affecting erosion. Results apply to erosion as well as polishing of metal surfaces.
On the Static-Kinetic Friction Transition in Dry Contact of Rough Surfaces
Authors: Farhang K. , Segalman D. , Starr M.
Published: February 2012

This paper shows that the Mindlin problem involving two spheres in contact under the action of oscillating tangential force can lead to the account of static-kinetic friction transition. In Mindlin’s problem two spheres experience partial slip as a result of application of oscillating tangential load. When the problem is extended to multi-sphere contact, i.e. two rough surfaces, the application of tangential oscillating load results in partial slip for some asperity contacts while others experience full slip. Increase in the amplitude of the oscillating tangential force results in more contacts experiencing full slip, thereby decreasing the number of contacts in parial slip. Constitutive relation proposed by Mindlin at small scale, governing asperity interaction, is used to obtain the large scale slip function through a statistical summation of asperity scale events. The slip function establishes the fraction of asperity contact in full slip. The complement of the slip parameter is a fraction of asperities in partial slip. Through slip function it is shown that it is possible to define a slip condition for the entire surface. The derivation of the slip function allows the account of transition between static friction and kinetic friction.
Catcher Bearing Life Prediction Using a Rainflow Counting Approach
Authors: Lee Jung Gu , Palazzolo Alan
Published: February 2012

Catcher bearings (CB) are an essential component for rotating machine with active magnetic bearings (AMBs) suspensions. The CB’s role is to protect the magnetic bearing and other close clearance component in the event of an AMB failure. The contact load, the Hertzian stress, and the sub/surface shear stress between rotor, races, and balls are calculated, using a nonlinear ball bearing model with thermal growth, during the rotor drop event. Fatigue life of the CB in terms of the number of drop events prior to failure is calculated by applying the Rainflow Counting Algorithm to the sub/surface shear stress-time history. The numerical simulations show that CB life is dramatically reduced when high-speed backward whirl occurs. The life of the CB is seen to be extended by reducing the CB clearances, and by applying static sideloads to the rotor.
Measurement of Pressure Distribution of Shoe Sole During Walking and its Relation to Slippage
Authors: Yoshioka Y. , Iwai T. , Shoukaku Y.
Published: February 2012

Every year, many people are injured by slipping and falling accidents when walking. Clarification of the mechanism of slipping and falling may provide insight into possible solutions. The purpose of this study was to reveal the behavior of the shoe sole contact during walking by measuring both contact pressure distribution and the slippage of shoe sole blocks. A force plate with a walkway made of glass was produced to observe the contact area between the walkway and the shoe sole. The total internal reflection of light was used to distinguish the contact area and noncontact area of the shoe sole. The slippage of the shoe sole was measured by time-sequence position variations of each block. As a result, a large traction coefficient and a large slippage of the shoe sole block were found to occur immediately after the heel strike. Slippage was also detected at the period of toe off. Moreover, the maximum contact pressure of each block varied from 1.0MPa to 3.0MPa in the contact area.
Friction and Wear Properties of PTFE Composites Against 6061-T6 Aluminum Alloy Under Hydrogen Atmosphere
Authors: Sakano Y. , Iwai T. , Shoukaku Y.
Published: February 2012

The friction and wear properties of polymer were investigated under a hydrogen atmosphere, by using PTFE (polytetrafluoroethylene) and two kinds of PTFE composites. Experiments were also conducted in air, nitrogen, and vacuum environment. The experiment carried out by pin-on-disk friction and wears apparatus in the vacuum chamber. Pin specimens are no filling PTFE, Gr-filled PTFE (Gr filled with 25 wt%) and MoS2–filled PTFE (MoS2 filled with 25 wt%). Friction disk is aluminum alloy 6061-T6 with 0.02μm surface roughness. Aluminum alloy 6061-T6 is able to use for apparatus for hydrogen. After experiments, specific wear rate was calculated, specimen surface, wear track and wear debris were observed, surface profile of the wear track were measured. The specific wear rate of unfilled PTFE and PTFE/MoS2 of in air was lower than the other atmospheres. The A6061-T6 disk was worn by PTFE pin specimens and in the case of wear track was much rougher, the specific wear rate of pin specimens tended to increase without unfilled PTFE in air and PTFE/Gr.
Work function extraction of metal gates with alternate channel materials
Authors: Coan Mary , Johnson Derek , Hwan Woo Jung , Biswas Nivedita , Misra Veena , Majhi Prashant , Rusty Harris H.
Published: February 2012

The effects of a heterojunction on the effective work function in a metal/high κ gate stack are studied and a new structure developed for the extraction of the work function. It is found that when a Ge/Si heterostructure on silicon is low doped and sufficiently thin, then the work function can be extracted in a manner similar to that on a simple silicon substrate. Modifications to the terraced oxide structure are proposed to remove oxidation effects of the alternate channel materials. The extracted work function of thickness variation of TiN is found to be in agreement with that of TiN on a silicon substrate.
Aerial ultrasonic micro Doppler sonar detection range in outdoor environments
Authors: Bradley Marshall , Sabatier James M.
Published: February 2012

Current research demonstrates that micro Doppler sonar has the capability to uniquely identify the presence of a moving human, making it an attractive component in surveillance systems for border security applications. Primary environmental factors that limit sonar performance are two-way spreading losses, ultrasonic absorption, and backscattered energy from the ground that appears at zero Doppler shift in the sonar signal processor. Spectral leakage from the backscatter component has a significant effect on sonar performance for slow moving targets. Sonar performance is shown to rapidly decay as the sensor is moved closer to the ground due to increasing surface backscatter levels.
Analysis of acoustic parameters for consonant voicing classification in clean and telephone speech
Authors: Lee Suk-Myung , Choi Jeung-Yoon
Published: February 2012

This paper describes acoustic cues for classification of consonant voicing in a distinctive feature-based speech recognition system. Initial acoustic cues are selected by studying consonant production mechanisms. Spectral representations, band-limited energies, and correlation values, along with Mel-frequency cepstral coefficients features (MFCCs) are also examined. Analysis of variance is performed to assess relative significance of features. Overall, 82.2 %, 80.6 %, and 78.4 % classification rates are obtained on the TIMIT database for stops, fricatives, and affricates, respectively. Combining acoustic parameters with MFCCs shows performance improvement in all cases. Also, performance in the NTIMIT telephone channel speech shows that acoustic parameters are more robust than MFCCs.
Genotypes, Exotoxin Gene Content, and Antimicrobial Resistance of Staphylococcus aureus Strains Recovered from Foods and Food Handlers
Authors: Argudín M. A. , Mendoza M. C. , González-Hevia M. A. , Bances M. , Guerra B. , Rodicio M. R.
Published: February 2012

Staphylococcal food poisoning, one of the most common food-borne diseases, results from ingestion of one or more staphylococcal enterotoxins (SEs) produced by
Staphylococcus aureus
in foods. In the present study, 64
S. aureus
isolates recovered from foods and food handlers, associated or not associated with food-poisoning outbreaks in Spain, were investigated. They were assigned to 31 strains by
spa
typing, multilocus sequence typing (MLST), exotoxin gene content, and antimicrobial resistance. The strains belonged to 10 clonal complexes (CCs): CC5 (29.0%), CC30 (25.8%), CC45 (16.1%), CC8, CC15 (two strains each), CC1, CC22, CC25, CC59, and CC121 (one strain each). They contained hemolysin genes (90.3%);
lukED
(77.4%); exfoliatin genes
eta
,
etd
(6.5% each), and
etb
(3.2%);
tst
(25.8%); and the following enterotoxin or enterotoxin-like genes or clusters:
sea
(38.7%),
seb
(12.9%),
sec
(16.1%),
sed-selj
with or without
ser
(22.9%),
selk-selq
(6.5%),
seh
,
sell
,
selp
(9.7% each),
egc1
(32.3%), and
egc2
(48.4%). The number of
se
and
sel
genes ranged from zero to 12. All isolates carrying
tst
, and most isolates with genes encoding classical enterotoxins (SEA, SEB, SEC, and SED), expressed the corresponding toxin(s). Two CC5 isolates from hamburgers (
spa
type t002, sequence type 5 [ST5];
spa
type t2173, ST5) were methicillin resistant and harbored staphylococcal cassette chromosome
mec
(SCC
mec
) IVd. Six (19.4%) were mupirocin resistant, and one (
spa
type t120, ST15) from a food handler carried
mupA
(MIC, 1,250 μg/ml). Resistance to ampicillin (
blaZ
) (61.3%), erythromycin (
ermA-ermC
or
ermC
) (25.8%), clindamycin (
msrA-msrB or msrB
) (16.1%), tetracycline (
tetK
) (3.2%), and amikacin-gentamicin-kanamycin-tobramycin (
aphA
with
aacA
plus
aphD
or
aadD
) (6.5%) was also observed. The presence of
S. aureus
strains with an important repertoire of virulence and resistance determinants in the food chain represents a potential health hazard for consumers and merits further observation.
Involvement of Two Latex-Clearing Proteins during Rubber Degradation and Insights into the Subsequent Degradation Pathway Revealed by the Genome Sequence of Gordonia polyisoprenivorans Strain VH2
Authors: Hiessl Sebastian , Schuldes Jörg , Thürmer Andrea , Halbsguth Tobias , Bröker Daniel , Angelov Angel , Liebl Wolfgang , Daniel Rolf , Steinbüchel Alexander
Published: February 2012

The increasing production of synthetic and natural poly(
cis
-1,4-isoprene) rubber leads to huge challenges in waste management. Only a few bacteria are known to degrade rubber, and little is known about the mechanism of microbial rubber degradation. The genome of
Gordonia polyisoprenivorans
strain VH2, which is one of the most effective rubber-degrading bacteria, was sequenced and annotated to elucidate the degradation pathway and other features of this actinomycete. The genome consists of a circular chromosome of 5,669,805 bp and a circular plasmid of 174,494 bp with average GC contents of 67.0% and 65.7%, respectively. It contains 5,110 putative protein-coding sequences, including many candidate genes responsible for rubber degradation and other biotechnically relevant pathways. Furthermore, we detected two homologues of a latex-clearing protein, which is supposed to be a key enzyme in rubber degradation. The deletion of these two genes for the first time revealed clear evidence that latex-clearing protein is essential for the microbial utilization of rubber. Based on the genome sequence, we predict a pathway for the microbial degradation of rubber which is supported by previous and current data on transposon mutagenesis, deletion mutants, applied comparative genomics, and literature search.
Escherichia coli Serotype O55:H7 Diversity Supports Parallel Acquisition of Bacteriophage at Shiga Toxin Phage Insertion Sites during Evolution of the O157:H7 Lineage
Authors: Kyle Jennifer L. , Cummings Craig A. , Parker Craig T. , Quiñones Beatriz , Vatta Paolo , Newton Elizabeth , Huynh Steven , Swimley Michelle , Degoricija Lovorka , Barker Melissa , Fontanoz Samar , Nguyen Kimberly , Patel Ronak , Fang Rixun , Tebbs Robert , Petrauskene Olga , Furtado Manohar , Mandrell Robert E.
Published: February 2012

EnteropathogenicEscherichia coli(EPEC) continues to be a leading cause of mortality and morbidity in children around the world. Two EPEC genomes have been fully sequenced: those of EPEC O127:H6 strain E2348/69 (United Kingdom, 1969) and EPEC O55:H7 strain CB9615 (Germany, 2003). The O55:H7 serotype is a recent precursor to the virulent enterohemorrhagicE. coliO157:H7. To explore the diversity of O55:H7 and better understand the clonal evolution of O157:H7, we fully sequenced EPEC O55:H7 strain RM12579 (California, 1974), which was collected 1 year before the first U.S. isolate of O157:H7 was identified in California. Phage-related sequences accounted for nearly all differences between the two O55:H7 strains. Additionally, O55:H7 and O157:H7 strains were tested for the presence and insertion sites of Shiga toxin gene (stx)-containing bacteriophages. Analysis of non-phage-associated genes supported core elements of previous O157:H7 stepwise evolutionary models, whereas phage composition and insertion analyses suggested a key refinement. Specifically, the placement and presence of lambda-like bacteriophages (including those containingstx) should not be considered stable evolutionary markers or be required in placing O55:H7 and O157:H7 strains within the stepwise evolutionary models. Additionally, we suggest that a 10.9-kb region (block 172) previously believed unique to O55:H7 strains can be used to identify early O157:H7 strains. Finally, we defined two subsets of O55:H7 strains that share an as-yet-unobserved or extinct common ancestor with O157:H7 strains. Exploration of O55:H7 diversity improved our understanding of the evolution ofE. coliO157:H7 and suggested a key revision to accommodate existing and future configurations ofstx-containing bacteriophages into current models.
Transcriptional Response of the Sulfur Chemolithoautotroph Thiomicrospira crunogena to Dissolved Inorganic Carbon Limitation
Authors: Dobrinski Kimberly P. , Enkemann Steven A. , Yoder Sean J. , Haller Edward , Scott Kathleen M.
Published: February 2012

The hydrothermal vent gammaproteobacterium
Thiomicrospira crunogena
inhabits an unstable environment and must endure dramatic changes in habitat chemistry. This sulfur chemolithoautotroph responds to changes in dissolved inorganic carbon (DIC) (DIC = CO
2
+ HCO
3
−
+ CO
3
−2
) availability with a carbon-concentrating mechanism (CCM) in which whole-cell affinity for DIC, as well as the intracellular DIC concentration, increases substantially under DIC limitation. To determine whether this CCM is regulated at the level of transcription, we resuspended cells that were cultivated under high-DIC conditions in chemostats in growth medium with low concentrations of DIC and tracked CCM development in the presence and absence of the RNA polymerase inhibitor rifampin. Induction of the CCM, as measured by silicone oil centrifugation, was hindered in the presence of rifampin. Similar results were observed for carboxysome gene transcription and assembly, as assayed by quantitative reverse transcription-PCR (qRT-PCR) and transmission electron microscopy, respectively. Genome-wide transcription patterns for cells grown under DIC limitation and those grown under ammonia limitation were assayed via microarrays and compared. In addition to carboxysome genes, two novel genes (
Tcr_1019
and
Tcr_1315
) present in other organisms, including chemolithoautotrophs, but whose function(s) has not been elucidated in any organism were found to be upregulated under low-DIC conditions. Likewise, under ammonia limitation, in addition to the expected enhancement of ammonia transporter and P
II
gene transcription, the transcription of two novel genes (
Tcr_0466
and
Tcr_2018
) was measurably enhanced. Upregulation of all four genes (
Tcr_1019
, 4-fold;
Tcr_131
, ∼7-fold;
Tcr_0466
, >200-fold;
Tcr_2018
, 7-fold), which suggests that novel components are part of the response to nutrient limitation by this organism, was verified via qRT-PCR.
Major cultural-compatibility complex: considerations on cross-cultural dissemination of patient safety programmes: Figure 1
Authors: Jeong Heon-Jae , Pham Julius C , Kim Minji , Engineer Cyrus , Pronovost Peter J
Published: February 2012

As the importance of patient safety has been broadly acknowledged, various improvement programmes have been developed. Many of the programmes with proven efficacy have been disseminated internationally. However, some of those attempts may encounter unexpected cross-cultural obstacles and may fail to harvest the expected success. Each country has different cultural background that has shaped the behavior of the constituents for centuries. It is crucial to take into account these cultural differences in effectively disseminating these programmes. As an organ transplantation requires tissue-compatibility between the donor and the recipient, there needs to be compatibility between the country where the program was originally developed and the nation implementing the program. Though no detailed guidelines exist to predict success, small-scale pilot tests can help evaluate whether a safety programme will work in a new cultural environment. Furthermore, a pilot programme helps reveal the source of potential conflict, so we can modify the original programme accordingly to better suit the culture to which it is to be applied. In addition to programme protocols, information about the cultural context of the disseminated programme should be conveyed during dissemination. Original programme designers should work closely with partnering countries to ensure that modifications do not jeopardise the original intention of the programme. By following this approach, we might limit barriers originating from cultural differences and increase the likelihood of success in cross-cultural dissemination.
Management of acute paracetamol (acetaminophen) toxicity: a standardised proforma improves risk assessment and overall risk stratification by emergency medicine doctors
Authors: McQuade David J , Aknuri Srikanth , Dargan Paul I , Wood David M
Published: February 2012

Background

Paracetamol (acetaminophen) poisoning is the most common toxicological presentation in the UK. Doctors managing patients with paracetamol poisoning need to assess the risk of their patient developing hepatotoxicity before determining appropriate treatment. Patients deemed to be at ‘high risk’ of hepatotoxicity have lower treatment thresholds than those deemed to be at ‘normal risk’. Errors in this process can lead to harmful or potentially fatal under or over treatment.

Aim

To determine how well treating doctors assess risk factor status and whether a standardised proforma is useful in the risk stratification process.

Methods

Retrospective 12-month case note review of all patients presenting with paracetamol poisoning to our large inner-city emergency department. Data were collected on the documentation of risk factors, the presence of a local hospital proforma and treatment outcomes.

Results

249 presentations were analysed and only 59 (23.7%) had full documentation of all the risk factors required to make a complete risk assessment. 56 of the 59 (94.9%) had the local hospital proforma included in the notes; the remaining 3 (5.1%) had full documentation of risk factors despite the absence of a proforma. A local hospital proforma was more likely to be included in the emergency department notes in those with ‘adequate documentation’ (78 out of 120 (65%)) than for those with ‘inadequate documentation’ (16 out of 129 (12.4%)); X2, p<0.001.

Conclusions

Despite a low overall uptake of the proforma, use of a standardised proforma significantly increased the likelihood of documentation of the risk factors which increase risk for hepatotoxicity following paracetamol poisoning.
Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes: an important cause of stroke in young people
Authors: Goodfellow John Aaron , Dani Krishna , Stewart Willie , Santosh Celestine , McLean John , Mulhern Sharon , Razvi Saif
Published: February 2012

Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes is a progressive, multisystem mitochondrial disease affecting children and young adults. Patients acquire disability through stroke-like episodes and have an increased mortality. Eighty per cent of cases have the mitochondrial mutation m.3243A>G which is linked to respiratory transport chain dysfunction and oxidative stress in energy demanding organs, particularly muscle and brain. It typically presents with seizures, headaches and acute neurological deficits mimicking stroke. It is an important differential in patients presenting with stroke, seizures, or suspected central nervous system infection or vasculitis. Investigations should exclude other aetiologies and include neuroimaging and cerebrospinal fluid analysis. Mutation analysis can be performed on urine samples. There is no high quality evidence to support the use of any of the agents reported in small studies. This article summarises the core clinical, biochemical, radiological and genetic features and discusses the evidence for a number of potential therapies.
HIV and sexually transmitted infections at the borderlands: situational analysis of sexual health in the Brazilian Amazon
Authors: Benzaken Adele , Sabidó Meritxell , Galban Enrique , Rodrigues Dutra Daniel Lúcio , Leturiondo André Luiz , Mayaud Philippe
Published: February 2012

Objectives

The borderlands are considered areas of increased vulnerability to HIV and sexually transmitted infections (STI). The study aimed to determine the STI/HIV prevalence and risk factors in the triple-border area of the Brazilian Amazon.

Methods

A situational analysis of sexual health was conducted in three cities of the Alto Solimões region. This multicomponent research approach included key informant interviews, participant observations and mapping of places where people meet sexual partners. Volunteers recruited from the ‘hot spots’ in each city were invited for interview and STI/HIV testing.

Results

Over 6 months, 598 participants were recruited, 285 men of median age 28 years (IQR, 23–37) and 313 women of median age 29 years (IQR, 24–37). Overall, 49.3% reported a casual partner during the past 3 months, but only 38.5% reported consistent condom use. The respective prevalences in men and women wereNeisseria gonorrhoeae(1.1% and 0.3%),Chlamydia trachomatis(1.4% and 4.8%), high-risk human papillomavirus (14.4% and 24.0%), active syphilis (3.2% and 2.6%), herpes simplex virus type-2 (51.1% and 72.1%), hepatitis B virus (by hepatitis B virus surface antigen) (7.5% and 4.6%), hepatitis C virus (0.7% and 0.7%) and HIV (1.4% and 0.0%). Risk factors for viral STIs included female sex and age.

Conclusions

While the main conditions that contribute to the spread of HIV are in place in the triple-border area, the prevalence of bacterial STIs and HIV are still relatively low, providing a window of opportunity for interventions.
Population dynamics and asynchrony at fine spatial scales: a case history of sockeye salmon (Oncorhynchus nerka) population structure in Alaska, USA
Authors: Quinn Thomas P. , Rich Harry B. , Gosse Dido , Schtickzelle Nicolas
Published: February 2012

Pacific salmon (Oncorhynchus spp.) exemplify the ways in which populations are structured by homing and the abiotic factors affecting their dynamics in discrete breeding and rearing habitats. What is the finest spatial scale of their population structure, and where do clusters of spatially proximate breeding groups lie along the continuum from isolated populations – metapopulation – patchy panmictic population? To investigate these questions, we monitored sockeye salmon, Oncorhynchus nerka, spawning in a complex of habitats ~1 km apart, joining to form a single stream flowing into Iliamna Lake, Alaska, USA. Annual surveys revealed levels of asynchrony in productivity that were comparable with values reported for sockeye salmon spawning in separate streams flowing into lakes elsewhere in Bristol Bay. A mark–recapture study revealed very little movement of spawning adults among habitats. The ponds occupied at highest density varied among years, and salmon consistently arrived and spawned later in one pond than the others. These results are consistent with the hypothesis that the salmon structured as a small-scale metapopulation rather than a single panmictic population.
Estimating the relationship between abundance and distribution
Authors: Rindorf Anna , Lewy Peter
Published: February 2012

Numerous studies investigate the relationship between abundance and distribution using indices reflecting one of the three aspects of distribution: proportion of area occupied, aggregation, and geographical range. Using simulations and analytical derivations, we examine whether these indices provide unbiased estimates of the relationship when estimated from count data. The indices investigated include the proportion of empty samples, the proportion of structurally empty samples, Lloyds index of patchiness, measures derived from Lorenz curves (such as D95 and the Gini index), and measures based on Euclidean distance to the centre of gravity of the spatial distribution. Only the proportion of structurally empty areas, Lloyds index, and indices of the distance to the centre of gravity of the spatial distribution are unbiased at all levels of abundance. The remaining indices generate relationships between abundance and distribution even in cases where no underlying relationships exists, although the problem decreases for measures derived from Lorenz curves when samples contain more than four individuals on average. To illustrate the problem, the indices are applied to juvenile North Sea cod, Gadus morhua .
A probabilistic cellular automata approach for predator–prey interactions of arrowtooth flounder (Atheresthes stomias) and walleye pollock (Theragra chalcogramma) in the eastern Bering Sea
Authors: Chen Kun , Chan Kung-Sik , Bailey Kevin M. , Aydin Kerim , Ciannelli Lorenzo
Published: February 2012

We developed a hybrid cellular automata (CA) modelling approach to explore the dynamics of a key predator–prey interaction in a marine system; our study is motivated by the quest for better understanding of the scale and heterogeneity-related effects on the arrowtooth flounder (Atheresthes stomias) and walleye pollock (Theragra chalcogramma) dynamics during the summer feeding season in the eastern Bering Sea (EBS), but can be readily extended to other systems. The spatially explicit and probabilistic CA model incorporates individual behaviours and strategies and local interactions among species, as well as spatial and temporal heterogeneity due to geographical and (or) environmental changes in the physical environment. The model is hybridized, with an individual-based model (IBM) approach for increasing its capacity and continuum and for balancing between computational efficiency and model validity, which makes it suitable for simulating predator–prey dynamics in a large, complex ecological environment. We focus on the functional and aggregative responses of predators to prey density at different spatial scales, the effects of individual behaviours, and the impacts of systematic heterogeneity. Simulations from the model with suitable parameter values share qualitatively similar features found in field observations, e.g., local aggregations around hydrographical features. Spatial heterogeneity is an important aspect of whether local-scale functional and aggregative responses reflect those operating over large, or global, scales.
Update on adipose tissue blood flow regulation
Authors: Sotornik Richard , Brassard Pascal , Martin Elizabeth , Yale Philippe , Carpentier André C. , Ardilouze Jean-Luc
Published: February 2012

According to Fick's principle, any metabolic or hormonal exchange through a given tissue depends on the product of the blood flow to that tissue and the arteriovenous difference. The proper function of adipose tissue relies on adequate adipose tissue blood flow (ATBF), which determines the influx and efflux of metabolites as well as regulatory endocrine signals. Adequate functioning of adipose tissue in intermediary metabolism requires finely tuned perfusion. Because metabolic and vascular processes are so tightly interconnected, any disruption in one will necessarily impact the other. Although altered ATBF is one consequence of expanding fat tissue, it may also aggravate the negative impacts of obesity on the body's metabolic milieu. This review attempts to summarize the current state of knowledge on adipose tissue vascular bed behavior under physiological conditions and the various factors that contribute to its regulation as well as the possible participation of altered ATBF in the pathophysiology of metabolic syndrome.
Deficiency of lymphotoxin-α does not exacerbate high-fat diet-induced obesity but does enhance inflammation in mice
Authors: Pamir Nathalie , McMillen Timothy S. , Edgel Kimberly A. , Kim Francis , LeBoeuf Renée C.
Published: February 2012

Lymphotoxin-α (LTα) is secreted by lymphocytes and acts through tumor necrosis factor-α receptors and the LTβ receptor. Our goals were to determine whether LT has a role in obesity and investigate whether LT contributes to the link between obesity and adipose tissue lymphocyte accumulation. LT deficient (LT−/−) and wild-type (WT) mice were fed standard pelleted rodent chow or a high-fat/high-sucrose diet (HFHS) for 13 wk. Body weight, body composition, and food intake were measured. Glucose tolerance was assessed. Systemic and adipose tissue inflammatory statuses were evaluated by quantifying plasma adipokine levels and tissue macrophage and T cell-specific gene expression in abdominal fat. LT−/−mice were smaller (20%) and leaner (25%) than WT controls after 13 wk of HFHS diet feeding. LT−/−mice showed improved glucose tolerance, suggesting that, in WT mice, LT may impair glucose metabolism. Surprisingly, adipose tissue from rodent chow- and HFHS-fed LT−/−mice exhibited increased T lymphocyte and macrophage infiltration compared with WT mice. Despite the fact that LT−/−mice exhibited an enhanced inflammatory status at the systemic and tissue level even when fed rodent chow, they were protected from enhanced diet-induced obesity and insulin resistance. Thus, LT contributes to body weight and adiposity and is required to modulate the accumulation of immune cells in adipose tissue.
Mass spectrometry for the molecular imaging of angiotensin metabolism in kidney
Authors: Grobe Nadja , Elased Khalid M. , Cool David R. , Morris Mariana
Published: February 2012

To better understand the tissue distribution and activity of enzymes involved in angiotensin II (Ang II) processing, we developed a novel molecular imaging method using matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry. Mouse kidney sections (12 μm) were incubated with 10–1,000 μmol/l Ang II for 5–15 min at 37°C. The formed peptides Ang III and Ang-(1–7) were identified by MALDI-TOF/TOF. A third metabolite, Ang-(1–4), was generated from further degradation of Ang-(1–7). Enzymatic processing of Ang II was dose and time dependent and absent in heat-treated kidney sections. Distinct spatial distribution patterns (pseudocolor images) were observed for the peptides. Ang III was localized in renal medulla, whereas Ang-(1–7)/Ang-(1–4) was present in cortex. Regional specific peptide formation was confirmed using microdissected cortical and medullary biopsies. In vitro studies with recombinant enzymes confirmed activity of peptidases known to generate Ang III or Ang-(1–7) from Ang II: aminopeptidase A (APA), Ang-converting enzyme 2 (ACE2), prolyl carboxypeptidase (PCP), and prolyl endopeptidase (PEP). Renal medullary Ang III generation was blocked by APA inhibitor glutamate phosphonate. The ACE2 inhibitor MLN-4760 and PCP/PEP inhibitor Z-pro-prolinal reduced cortical Ang-(1–7) formation. Our results establish the power of MALDI imaging as a highly specific and information-rich analytical technique that will further aid our understanding of the role and site of Ang II processing in cardiovascular and renal pathologies.
Lack of myostatin alters intermyofibrillar mitochondria activity, unbalances redox status, and impairs tolerance to chronic repetitive contractions in muscle
Authors: Ploquin Claire , Chabi Béatrice , Fouret Gilles , Vernus Barbara , Feillet-Coudray Christine , Coudray Charles , Bonnieu Anne , Ramonatxo Christelle
Published: February 2012

Loss of myostatin (mstn) function leads to a decrease in mitochondrial content, a reduced expression of cytochrome c oxidase, and a lower citrate synthase activity in skeletal muscle. These data suggest functional or ultrastructural mitochondrial abnormalities that can impact on muscle endurance characteristics in such phenotype. To address this issue, we investigated subsarcolemmal and intermyofibrillar (IMF) mitochondrial activities, skeletal muscle redox homeostasis, and muscle fiber endurance quality in mstn-deficient mice [mstn knockout (KO)]. We report that lack of mstn induced a decrease in the coupling of IMF mitochondria respiration, with significantly higher basal oxygen consumption. No lysis of mitochondrial cristae or excessive swelling were observed in mstn KO mice compared with wild-type (WT) mice. Concerning redox status, mstn KO gastrocnemius exhibited a significant decrease in lipid peroxidation levels (−56%; P < 0.01 vs. WT) together with a significant upregulation of the antioxidant glutathione system. In contrast, superoxide dismutase and catalase activities were altered in mstn KO, gastrocnemius and soleus with a reduction of up to 80% compared with WT animals. The force production observed after contractile endurance test was significantly lower in extensor digitorum longus and soleus muscles of mstn KO mice compared with the controls (17 ± 3 and 36 ± 5% vs. 28 ± 4 and 56 ± 5%, respectively, P < 0.05). Together, these findings indicate that, besides an increased skeletal muscle mass, genetic mstn inhibition has differential effects on redox homeostasis and mitochondrial function that would have functional consequences on muscle response to endurance exercise.
Mammary gland serotonin regulates parathyroid hormone-related protein and other bone-related signals
Authors: Hernandez Laura L. , Gregerson Karen A. , Horseman Nelson D.
Published: February 2012

Breast cells drive bone demineralization during lactation and metastatic cancers. A shared mechanism among these physiological and pathological states is endocrine secretion of parathyroid hormone-related protein (PTHrP), which acts through osteoblasts to stimulate osteoclastic bone demineralization. The regulation of PTHrP has not been accounted for fully by any conventional mammotropic stimuli or tumor growth factors. Serotonin (5-HT) synthesis within breast epithelial cells is induced during lactation and in advancing breast cancer. Here we report that serotonin deficiency (knockout of tryptophan hydroxylase-1) results in a reduction of mammary PTHrP expression during lactation, which is rescued by restoring 5-HT synthesis. 5-HT induced PTHrP expression in lactogen-primed mammary epithelial cells from either mouse or cow. In human breast cancer cells 5-HT induced both PTHrP and the metastasis-associated transcription factor Runx2/Cbfa1. Based on receptor expression and pharmacological evidence, the 5-HT2 receptor type was implicated as being critical for induction of PTHrP and Runx2. These results connect 5-HT synthesis to the induction of bone-regulating factors in the normal mammary gland and in breast cancer cells.
Protective role of adiponectin against ethanol-induced gastric injury in mice
Authors: Yamamoto Shunsuke , Watabe Kenji , Araki Hiroshi , Kamada Yoshihiro , Kato Motohiko , Kizu Takashi , Kiso Shinichi , Tsutsui Shusaku , Tsujii Masahiko , Kihara Shinji , Funahashi Tohru , Shimomura Iichiro , Hayashi Norio , Takehara Tetsuo
Published: February 2012

Adiponectin is an anti-inflammatory molecule released from adipocytes, and serum adiponectin concentrations are reduced in obesity. We previously reported that gastric erosion occurs in association with obesity and low serum adiponectin levels. In the present study, we examined adiponectin-knockout (APN-KO) mice to elucidate the role of adiponectin in gastric mucosal injury. Gastric injury was induced by oral administration of ethanol in wild-type (WT) and APN-KO mice. Ethanol treatment induced severe gastric injury in APN-KO mice compared with WT mice. In APN-KO mice, increased apoptotic cells and decreased expression of prostaglandin E2(PGE2) were detected in the injured stomach. We next assessed the effect of adiponectin on the cellular response to ethanol treatment and wound repair in rat gastric mucosal cells (RGM1). Adiponectin induced the expression of PGE2and cyclooxygenase 2 (COX-2) in ethanol-treated RGM1 cells. RGM1 cells exhibited efficient wound repair accompanied by increased PGE2expression in the presence of adiponectin. Coadministration of adiponectin with celecoxib, a COX-2 inhibitor, inhibited efficient wound repair. These findings indicate that adiponectin has a protective role against ethanol-induced gastric mucosal injury in mice. This effect may be partially mediated by the efficient wound repair of epithelial cells via increased PGE2expression.
Testosterone and interleukin-1β increase cardiac remodeling during coxsackievirus B3 myocarditis via serpin A 3n
Authors: Coronado Michael J. , Brandt Jessica E. , Kim Eunyong , Bucek Adriana , Bedja Djahida , Abston Eric D. , Shin Jaewook , Gabrielson Kathleen L. , Mitzner Wayne , Fairweather DeLisa
Published: February 2012

Myocarditis and dilated cardiomyopathy (DCM) are often caused by viral infections and occur more frequently in men than in women, but the reasons for the sex difference remain unclear. The aim of this study was to assess whether gene changes in the heart during coxsackievirus B3 (CVB3) myocarditis in male and female BALB/c mice predicted worse DCM in males. Although myocarditis ( P = 4.2 × 10−5) and cardiac dilation ( P = 0.008) were worse in males, there was no difference in viral replication in the heart. Fibrotic remodeling genes, such as tissue inhibitor of metalloproteinase (TIMP)-1 and serpin A 3n, were upregulated in males during myocarditis rather than during DCM. Using gonadectomy and testosterone replacement, we showed that testosterone increased cardiac TIMP-1 ( P = 0.04), serpin A 3n ( P = 0.007), and matrix metalloproteinase (MMP)-8 ( P = 0.04) during myocarditis. Testosterone increased IL-1β levels in the heart ( P = 0.02), a cytokine known to regulate cardiovascular remodeling, and IL-1β in turn increased cardiac serpin A 3n mRNA ( P = 0.005). We found that 39 of 118 (33%) genes identified in acute DCM patients were significantly altered in the heart during CVB3 myocarditis in mice, including serpin A 3n (3.3-fold change, P = 0.0001). Recombinant serpin A 3n treatment induced cardiac fibrosis during CVB3 myocarditis ( P = 0.0008) while decreasing MMP-3 ( P = 0.04) and MMP-9 ( P = 0.03) levels in the heart. Thus, serpin A 3n was identified as a gene associated with fibrotic cardiac remodeling and progression to DCM in male myocarditis patients and mice.
Bronchioalveolar stem cells increase after mesenchymal stromal cell treatment in a mouse model of bronchopulmonary dysplasia
Authors: Tropea Kristen A. , Leder Eva , Aslam Muhammad , Lau Allison N. , Raiser David M. , Lee Joo-Hyeon , Balasubramaniam Vivek , Fredenburgh Laura E. , Alex Mitsialis S. , Kourembanas Stella , Kim Carla F.
Published: February 2012

Bronchopulmonary dysplasia (BPD) remains a major complication of prematurity resulting in significant morbidity and mortality. The pathology of BPD is multifactorial and leads to alveolar simplification and distal lung injury. Previous studies have shown a beneficial effect of systemic treatment with bone marrow-derived mesenchymal stromal cells (MSCs) and MSC-conditioned media (MSC-CM) leading to amelioration of the lung parenchymal and vascular injury in vivo in the hyperoxia murine model of BPD. It is possible that the beneficial response from the MSCs is at least in part due to activation of endogenous lung epithelial stem cells. Bronchioalveolar stem cells (BASCs) are an adult lung stem cell population capable of self-renewal and differentiation in culture, and BASCs proliferate in response to bronchiolar and alveolar lung injury in vivo. Systemic treatment of neonatal hyperoxia-exposed mice with MSCs or MSC-CM led to a significant increase in BASCs compared with untreated controls. Treatment of BASCs with MSC-CM in culture showed an increase in growth efficiency, indicating a direct effect of MSCs on BASCs. Lineage tracing data in bleomycin-treated adult mice showed that Clara cell secretory protein-expressing cells including BASCs are capable of contributing to alveolar repair after lung injury. MSCs and MSC-derived factors may stimulate BASCs to play a role in the repair of alveolar lung injury found in BPD and in the restoration of distal lung cell epithelia. This work highlights the potential important role of endogenous lung stem cells in the repair of chronic lung diseases.
Development of orientation tuning in simple cells of primary visual cortex
Authors: Moore Bartlett D. , Freeman Ralph D.
Published: February 2012

Orientation selectivity and its development are basic features of visual cortex. The original model of orientation selectivity proposes that elongated simple cell receptive fields are constructed from convergent input of an array of lateral geniculate nucleus neurons. However, orientation selectivity of simple cells in the visual cortex is generally greater than the linear contributions based on projections from spatial receptive field profiles. This implies that additional selectivity may arise from intracortical mechanisms. The hierarchical processing idea implies mainly linear connections, whereas cortical contributions are generally considered to be nonlinear. We have explored development of orientation selectivity in visual cortex with a focus on linear and nonlinear factors in a population of anesthetized 4-wk postnatal kittens and adult cats. Linear contributions are estimated from receptive field maps by which orientation tuning curves are generated and bandwidth is quantified. Nonlinear components are estimated as the magnitude of the power function relationship between responses measured from drifting sinusoidal gratings and those predicted from the spatial receptive field. Measured bandwidths for kittens are slightly larger than those in adults, whereas predicted bandwidths are substantially broader. These results suggest that relatively strong nonlinearities in early postnatal stages are substantially involved in the development of orientation tuning in visual cortex.
Interleukin-1β modulates smooth muscle cell phenotype to a distinct inflammatory state relative to PDGF-DD via NF-κB-dependent mechanisms
Authors: Alexander Matthew R. , Murgai Meera , Moehle Christopher W. , Owens Gary K.
Published: February 2012

Smooth muscle cell (SMC) phenotypic modulation in atherosclerosis and in response to PDGF in vitro involves repression of differentiation marker genes and increases in SMC proliferation, migration, and matrix synthesis. However, SMCs within atherosclerotic plaques can also express a number of proinflammatory genes, and in cultured SMCs the inflammatory cytokine IL-1β represses SMC marker gene expression and induces inflammatory gene expression. Studies herein tested the hypothesis that IL-1β modulates SMC phenotype to a distinct inflammatory state relative to PDGF-DD. Genome-wide gene expression analysis of IL-1β- or PDGF-DD-treated SMCs revealed that although both stimuli repressed SMC differentiation marker gene expression, IL-1β distinctly induced expression of proinflammatory genes, while PDGF-DD primarily induced genes involved in cell proliferation. Promoters of inflammatory genes distinctly induced by IL-1β exhibited over-representation of NF-κB binding sites, and NF-κB inhibition in SMCs reduced IL-1β-induced upregulation of proinflammatory genes as well as repression of SMC differentiation marker genes. Interestingly, PDGF-DD-induced SMC marker gene repression was not NF-κB dependent. Finally, immunofluorescent staining of mouse atherosclerotic lesions revealed the presence of cells positive for the marker of an IL-1β-stimulated inflammatory SMC, chemokine (C-C motif) ligand 20 (CCL20), but not the PDGF-DD-induced gene, regulator of G protein signaling 17 (RGS17). Results demonstrate that IL-1β- but not PDGF-DD-induced phenotypic modulation of SMC is characterized by NF-κB-dependent activation of proinflammatory genes, suggesting the existence of a distinct inflammatory SMC phenotype. In addition, studies provide evidence for the possible utility of CCL20 and RGS17 as markers of inflammatory and proliferative state SMCs within atherosclerotic plaques in vivo.