bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Pressure Pulses to an Innovative Turbine Blade Film Cooling System
Authors: Moser Siegfried , Jericha Herbert , Woisetschläger Jakob , Gehrer Arno , Reinalter Werner
Published: December 2014

The evolution of increasing turbine inlet temperature has led to the necessity of full-coverage film cooling for the first turbine vane and blade. This paper deals with the investigation of the aerodynamic behaviour of the transonic wall film on a leading edge with and without leading edge pressure waves. Here these films are used for turbine blade cooling. The pressure waves are produced with a rotating „Pressure Wave Generator“. The numerical simulations have been realised with a commercial CFD-Program. The experimental data were obtained in a linear cascade.
Experimental and Numerical Investigations of Film-Cooling Effects on the Aerodynamic Performance of Transonic Turbine Blades
Authors: Urban Martin F. , Hermeler Juergen , Hosenfeld Hans-Georg
Published: December 2014

This paper presents results of experimental as well as numerical investigations of the aerodynamic performance of film-cooled transonic turbine blades. Taking into consideration to non-dimensional similarity, the experiments were performed on a cascade test rig using superheated steam as fluid. The investigated blading corresponds to a typical high pressure turbine vane used in the high subsonic regime.

In order to determine the effect of the blown-out cooling fluid on the aerodynamic performance of the cascade, the measurements were performed over a wide range of realistic exit Mach numbers, mass flow rate ratios, coolant injection locations and main-to-coolant flow density ratios.

The paper presents the results of the experimental investigation in the form of outlet angles and loss terms, and compares and discusses these for a number of variations. It was found that below a critical mass flow ratio, the kinetic loss coefficient varies only little with flow rate whereas above this critical flow ratio, the loss coefficient increases rapidly.

A comparison of the different injection locations shows that the suction side is very sensitive with regard to main flow disturbances while injection on the pressure side and the trailing edge only has a small effect of the loss terms. Consideration of different coolant-to-mainstream density ratios clarifies that the influence of this parameter on the loss terms can be neglected.

The paper also addresses a simple numerical code which is based on the „TOTLOS“ model of Hansel and adapted to the above-mentioned problem, and compares and discusses the results of the experimental and numerical investigations.
Generation of Five-Axis Cutter Paths for a Ball-End Cutter With Global Interference Checking
Authors: Tsay Der Min , Yan Wei Feng
Published: December 2014

A simple, yet useful procedure is developed to generate tool paths with global interference checking for five-axis machining of turbomachinery components with complex geometries. Based on the projected distance between the surface data and the cutter-axis of a cylindrical ball-end mill, interference between the surface of a workpiece and the cutter can be detected. Given the cutter contact points of the surface and the cutter’s size, it can produce the cutter location data without incurring interference through relatively rotating and tilting the workpiece. Applications of the developed approach to five-axis machining of centrifugal compressor impellers with thirteen and fifteen blades are illustrated to demonstrate the usefulness and reliability of the procedure.
Control of Shock Structure and Secondary Flow Field Inside Transonic Compressor Rotors Through Aerodynamic Sweep
Authors: Hah C. , Puterbaugh S. L. , Wadia A. R.
Published: December 2014

The present paper reports a numerical study on the effects of aerodynamic sweep applied to a low-aspect-ratio, high-through-flow, state-of-the-art, axial transonic compressor design. Numerical analyses based on the Reynolds-averaged Navier-Stokes equations were used to obtain the performance of a conventional unswept rotor, a forward swept rotor, and an aft-swept rotor, at both design and off-design operating conditions. The numerical analyses predicted that the forward-swept rotor has a higher peak efficiency and a substantially larger stall margin than the baseline unswept rotor, and that the aft-swept rotor has a similar peak efficiency as the unswept rotor with a significantly smaller stall margin. The rig test confirmed the numerical assessment of the effects of aerodynamic sweep on the low-aspect-ratio, high-through-flow, transonic compressor rotor. Detailed analyses of the measured and calculated flow fields indicate that two mechanisms are primarily responsible for the differences in aerodynamic performance among these rotors. The first mechanism is a change in the radial shape of the passage shock near the casing by the endwall effect, and the second is the radial migration of low-momentum fluid to the blade tip region. Aerodynamic sweep can be used to control the shock structure near the endwall and the migration of secondary flows and, consequently, flow structures near the tip area for improved performance.
Numerical Investigation of Wake Interaction in a Low Pressure Turbine
Authors: Eulitz Frank , Engel Karl
Published: December 2014

A time-accurate Reynolds-averaged Navier-Stokes solver has been extended for a phenomenological study of wake/bladerow interaction in a low pressure turbine near midspan. To qualitatively account for unsteady laminar-turbulent boundary layer transition, a variant of the Abu-Ghanam Shaw transition correlation has been coupled with the Spalart-Allmaras one-equation turbulence model. The method is shown to be capable of capturing separated-flow and wake-induced transition, as well as becalming and relaminarization effects. The model turbine investigated consists of three stator and two rotor rows. Instantaneous Mach number and eddy-viscosity plots are presented to monitor the wake migration and interaction with downstream boundary layers. Especially on the suction sides, very large fluctuations of the skin friction coefficient are observed. Effects of the near and far wakes are identified.
Feedstock Blending Studies With Laboratory Indirectly Heated Gasifiers
Authors: Green Alex E. S. , Mullin James P.
Published: December 2014

To support the further development of indirectly heated gasifiers, intended to provide fuels for advanced gas turbines, several laboratory indirectly heated gasifiers were constructed. During many comparative tests advantages and problems with each system were observed. The most useful systems make use of laboratory tube furnaces in conjunction with temperature, time and pressure or volume yield measuring systems and a gas chromatograph with a thermal conductivity detector. In this paper high temperature pyrolysis results obtained with the latest system are presented. Contrasting feedstocks suitable for commercial systems separately or in blends are used. Yield vs. time measurements are used to determine relevant rate constants and outputs. Since the rate constants are mainly reflective of heat transfer effects, cylindrical dowel sticks of varying radii were volatilized. The data set leads to an analytic heat transfer model that considers the hemicellulose, cellulose, and lignin components of the dowels. Also developed from the dowel experiments is an approximate procedure for estimating the proportionate releases of CO, CO2, CH4 and H2 for any type of biomass whose component proportions are known.
Sweep in a Transonic Fan Rotor: Part 1 — 3D Geometry Package
Authors: Abdelhamid Hazem F. , Shreeve Raymond P.
Published: December 2014

A geometry package was developed which uses six Bezier surfaces to describe an axial compressor blade. The blade is defined by 32 control points and two parameters, which determine the leading and trailing edge extensions. The package was used to represent a reference transonic fan rotor to within machining tolerances, and then to introduce forward and backward sweep holding blade-element design parameters fixed. Blade lean and point geometry manipulations were also demonstrated. All geometries produced by the package are machinable without approximation. The Bezier-surface representation was chosen in order to minimize the number of control points required to specify the blade shape and eventually enable aero-structural-manufacturing optimization.
Combustion Oscillation Analysis of Premixed Flames at Elevated Pressures
Authors: Ohtsuka Masaya , Yoshida Shohei , Inage Shin’ichi , Kobayashi Nariyoshi
Published: December 2014

A new analytical time lag flame model based on Bloxidge’s flame model was introduced for calculating combustion oscillation of premixed flame to take into account the distribution of heat release rate and flame speed which was calculated by analytical formulas dependent on pressure, temperature, fuel-to-air ratio and velocity. The transfer matrix technique using the new flame model was applied to the calculation of acoustic resonance. To verify the model, combustion oscillation experiments were performed for methane-air premixed flames stabilized by a swirl burner at elevated pressures between 0.6–0.9MPa. Fluctuating pressure had the maximum peak at the specific value of fτf. Here f is the frequency of resonance and τf is the passing time of premixed gas through flame length. The analysis could simulate the dependency of fuel-to-air ratio and static pressure for dynamic pressure local peak.
Role of Blade Passage Flow Structures in Axial Compressor Rotating Stall Inception
Authors: Hoying Donald A. , Tan Choon S. , Vo Huu Duc , Greitzer Edward M.
Published: December 2014

The influence of three-dimensional flow structures within a compressor blade passage has been examined computationally to determine their role in rotating stall inception. The computations displayed a short length-scale (or spike) type of stall inception similar to that seen in experiments; to the authors’ knowledge this is the first time such a feature has been simulated. A central feature observed during the rotating stall inception was the tip clearance vortex moving forward of the blade row leading edge. Vortex kinematic arguments are used to provide a physical explanation of this motion as well as to motivate the conditions for its occurrence. The resulting criterion for this type of stall inception (which appears generic for axial compressors with tip-critical flow fields) depends upon local flow phenomena related to the tip clearance and it is thus concluded that the flow structure within the blade passages must be addressed to explain the stability of an axial compression system which exhibits such short length-scale disturbances.
Exogenous contrast agents for thermoacoustic imaging: An investigation into the underlying sources of contrast
Authors: Ogunlade Olumide , Beard Paul
Published: December 2014

Purpose:

Thermoacoustic imaging at microwave excitation frequencies is limited by the low differential contrast exhibited by high water content tissues. To overcome this, exogenous thermoacoustic contrast agents based on gadolinium compounds, iron oxide, and single wall carbon nanotubes have previously been suggested and investigated. However, these previous studies did not fully characterize the electric, magnetic, and thermodynamic properties of these agents thus precluding identification of the underlying sources of contrast. To address this, measurements of the complex permittivity, complex permeability, DC conductivity, and Grüneisen parameter have been made. These measurements allowed the origins of the contrast provided by each substance to be identified.

Methods:

The electric and magnetic properties of the contrast agents were characterized at 3 GHz using two rectangular waveguide cavities. The DC conductivity was measured separately using a conductivity meter. Thermoacoustic signals were then acquired and compared to those generated in water. Finally, 3D electromagnetic simulations were used to decouple the different contributions to the absorbed power density.

Results:

It was found that the gadolinium compounds provided appreciable electric contrast but not originating from the gadolinium itself. The contrast was either due to dissociation of the gadolinium salt which increased ionic conductivity or its nondissociated polar fraction which increased dielectric polarization loss or a combination of both. In addition, very high concentrations were required to achieve appreciable contrast, to the extent that the Grüneisen parameter increased significantly and became a source of contrast. Iron oxide particles were found to produce low but measurable dielectric contrast due to dielectric polarization loss, but this is attributed to the coating of the particles not the iron oxide. Single wall carbon nanotubes did not provide measurable contrast of any type.

Conclusions:

It is concluded that gadolinium based contrast agents, iron oxide particles, and single walled carbon nanotubes have little intrinsic merit as thermoacoustic contrast agents. Simple electrolytes such as saline which yield high contrast based on ionic conductivity provide much higher dielectric contrast per unit solute concentration and are likely to be significantly more effective as contrast agents.
Research as a guide for curriculum development: An example from introductory spectroscopy. I. Identifying student difficulties with atomic emission spectra
Authors: Ivanjek L. , Shaffer P. S. , McDermott L. C. , Planinic M. , Veza D.
Published: December 2014

This is the first of two closely related articles (Paper I and Paper II) that together illustrate how research in physics education has helped guide the design of instruction that has proved effective in improving student understanding of atomic spectroscopy. Most of the more than 1000 students who participated in this four-year investigation were science majors enrolled in the introductory calculus-based physics course at the University of Washington (UW) in Seattle, WA, USA. The others included graduate and undergraduate teaching assistants at UW and physics majors in introductory and advanced physics courses at the University of Zagreb, Zagreb, Croatia. About half of the latter group were preservice high school physics teachers. This article (Paper I) describes how several serious conceptual and reasoning difficulties were identified among students as they tried to relate a discrete line spectrum to the energy levels of atoms in a light source. Paper II illustrates how findings from this research informed the development of a tutorial that led to significant improvement in student understanding of atomic emission spectra.
Propagation of time-reversed Lamb waves in bovine cortical bone in vitro
Authors: Lee Kang Il , Yoon Suk Wang
Published: December 2014

The present study aims to investigate the propagation of time-reversed Lamb waves in bovine cortical bone in vitro. The time-reversed Lamb waves were successfully launched at 200 kHz in 18 bovine tibiae through a time reversal process of Lamb waves. The group velocities of the time-reversed Lamb waves in the bovine tibiae were measured using the axial transmission technique. They showed a significant correlation with the cortical thickness and tended to follow the theoretical group velocity of the lowest order antisymmetrical Lamb wave fairly well, consistent with the behavior of the slow guided wave in long cortical bones.
Preservice Physical Educators’ Self-Efficacy Beliefs Toward Inclusion: The Impact of Coursework and Practicum
Authors: Taliaferro Andrea R. , Hammond Lindsay , Wyant Kristi
Published: December 2014

The purpose of this study was to investigate the effect of completion of an adapted physical education (APE) course with an associated on-campus practicum on preservice physical educators’ self-efficacy beliefs toward the inclusion of individuals with specific disabilities (autism, intellectual disabilities, physical disabilities, and visual impairments). Preservice students in physical education teacher education (N = 98) at a large U.S. Midwestern university enrolled in 1 of 2 separate 15-wk APE courses with an associated 9-wk practicum experience were surveyed at the beginning, middle, and conclusion of each course. Results of 4 separate 2-factor fixed-effect split-plot ANOVAs revealed significant improvements in self-efficacy beliefs from Wk 1 to Wk 8 and from Wk 1 to Wk 15 across all disability categories. Significant differences between courses were found only for autism in Time 1.
The Effect of a Prefabricated Foot Orthotic on Frontal Plane Joint Mechanics in Healthy Runners
Authors: Almonroeder Thomas G. , Benson Lauren C. , O’Connor Kristian M.
Published: December 2014

The mechanism of action of a foot orthotic is poorly understood. The purpose of this study was to use principal components analysis (PCA) to analyze the effects of a prefabricated foot orthotic on frontal plane knee and ankle mechanics during running. Thirty-one healthy subjects performed running trials with and without a foot orthotic and PCA was performed on the knee and ankle joint angles and moments to identify the dominant modes of variation. MANOVAs were conducted on the retained principal components of each waveform and dependent t tests (P < .05) were performed in the case of significance. Mechanics of the ankle were not affected by the foot orthotic. However, mechanics of the knee were significantly altered as subjects demonstrated an increase in the magnitude of the knee abduction moment waveform in an orthotic condition. Subjects also demonstrated a significant shift in the timing of the knee abduction moment waveform toward later in the stance phase in the orthotic condition. These orthotic effects were not related to subject’s foot mobility, measured using the navicular drop test. The mechanism of action of a foot orthotic may be related to their effect on the timing of frontal plane knee loading.
A Novel Device to Preserve Physical Activities of Daily Living in Healthy Older People
Authors: Haslinger Wolfram , Müller Lisa , Sarabon Nejc , Raschner Christian , Kern Helmut , Löfler Stefan
Published: December 2014

Objective:

To determine the effectiveness of exercise in improving sensorimotor function and functional performance, crucial parts of activities of daily living in healthy older adults.

Design:

RCT.

Setting:

Laboratory.

Participants:

39 subjects (M = 71.8 years, range: 61–89 years).

Intervention:

Task-oriented visual feedback balance training.

Primary outcome measure:

Timed Up & Go (TUG).

Secondary outcome measures:

Chair stand test (CST), self-paced walk test, maximum isometric torque, quiet stand posturography, and dynamic balance (DB).

Results:

Postintervention comparison of the treatment group (TG) and control group (CG) showed better TUG (p < .01), CST (p < .001), and DB (p < .025) for the TG. Pre–post intervention comparison of the TG showed better clinically-relevant outcomes in TUG (p < .001), CST (p < .001), and DB (p < .001).

Conclusion:

Active driven visual feedback balance training is effective in improving functional performance and dynamic balance in older adults.
RAS signaling promotes resistance to JAK inhibitors by suppressing BAD-mediated apoptosis
Authors: Winter Peter S. , Sarosiek Kristopher A. , Lin Kevin H. , Meggendorfer Manja , Schnittger Susanne , Letai Anthony , Wood Kris C.
Published: December 2014

Targeting a protein that prevents cell death may overcome drug resistance in some blood cancers.
Doripenem MICs and
ompK36
Porin Genotypes of Sequence Type 258, KPC-Producing Klebsiella pneumoniae May Predict Responses to Carbapenem-Colistin Combination Therapy among Patients with Bacteremia
Authors: Shields Ryan K. , Nguyen M. Hong , Potoski Brian A. , Press Ellen G. , Chen Liang , Kreiswirth Barry N. , Clarke Lloyd G. , Eschenauer Gregory A. , Clancy Cornelius J.
Published: December 2014

Treatment failures of a carbapenem-colistin regimen among patients with bacteremia due to sequence type 258 (ST258), KPC-2-producing
Klebsiella pneumoniae
were significantly more likely if both agents were inactive
in vitro
, as defined by a colistin MIC of >2 μg/ml and the presence of either a major
ompK36
porin mutation (guanine and alanine insertions at amino acids 134 and 135 [ins aa 134–135 GD], IS
5
promoter insertion [
P
= 0.007]) or a doripenem MIC of >8 μg/ml (
P
= 0.01). Major
ompK36
mutations among KPC-
K. pneumoniae
strains are important determinants of carbapenem-colistin responses
in vitro
and
in vivo
.
Fluoroquinolone Resistance Does Not Impose a Cost on the Fitness of Clostridium difficile In Vitro
Authors: Wasels François , Kuehne Sarah A. , Cartman Stephen T. , Spigaglia Patrizia , Barbanti Fabrizio , Minton Nigel P. , Mastrantonio Paola
Published: December 2014

Point mutations conferring resistance to fluoroquinolones were introduced in the
gyr
genes of the reference strain
Clostridium difficile
630. Only mutants with the substitution Thr-82→Ile in GyrA, which characterizes the hypervirulent epidemic clone III/027/NAP1, were resistant to all fluoroquinolones tested. The absence of a fitness cost
in vitro
for the most frequent mutations detected in resistant clinical isolates suggests that resistance will be maintained even in the absence of antibiotic pressure.
Targeting Mycobacterium tuberculosis Topoisomerase I by Small-Molecule Inhibitors
Authors: Godbole Adwait Anand , Ahmed Wareed , Bhat Rajeshwari Subray , Bradley Erin K. , Ekins Sean , Nagaraja Valakunja
Published: December 2014

We describe inhibition of
Mycobacterium tuberculosis
topoisomerase I (MttopoI), an essential mycobacterial enzyme, by two related compounds, imipramine and norclomipramine, of which imipramine is clinically used as an antidepressant. These molecules showed growth inhibition of both
Mycobacterium smegmatis
and
M. tuberculosis
cells. The mechanism of action of these two molecules was investigated by analyzing the individual steps of the topoisomerase I (topoI) reaction cycle. The compounds stimulated cleavage, thereby perturbing the cleavage-religation equilibrium. Consequently, these molecules inhibited the growth of the cells overexpressing topoI at a low MIC. Docking of the molecules on the MttopoI model suggested that they bind near the metal binding site of the enzyme. The DNA relaxation activity of the metal binding mutants harboring mutations in the DxDxE motif was differentially affected by the molecules, suggesting that the metal coordinating residues contribute to the interaction of the enzyme with the drug. Taken together, the results highlight the potential of these small molecules, which poison the
M. tuberculosis
and
M. smegmatis
topoisomerase I, as leads for the development of improved molecules to combat mycobacterial infections. Moreover, targeting metal coordination in topoisomerases might be a general strategy to develop new lead molecules.
In Vitro
Activity and Resistance Profile of Dasabuvir, a Nonnucleoside Hepatitis C Virus Polymerase Inhibitor
Authors: Kati Warren , Koev Gennadiy , Irvin Michelle , Beyer Jill , Liu Yaya , Krishnan Preethi , Reisch Thomas , Mondal Rubina , Wagner Rolf , Molla Akhteruzzaman , Maring Clarence , Collins Christine
Published: December 2014

Dasabuvir (ABT-333) is a nonnucleoside inhibitor of the RNA-dependent RNA polymerase encoded by the hepatitis C virus (HCV) NS5B gene. Dasabuvir inhibited recombinant NS5B polymerases derived from HCV genotype 1a and 1b clinical isolates, with 50% inhibitory concentration (IC
50
) values between 2.2 and 10.7 nM, and was at least 7,000-fold selective for the inhibition of HCV genotype 1 polymerases over human/mammalian polymerases. In the HCV subgenomic replicon system, dasabuvir inhibited genotype 1a (strain H77) and 1b (strain Con1) replicons with 50% effective concentration (EC
50
) values of 7.7 and 1.8 nM, respectively, with a 13-fold decrease in inhibitory activity in the presence of 40% human plasma. This level of activity was retained against a panel of chimeric subgenomic replicons that contained HCV NS5B genes from 22 genotype 1 clinical isolates from treatment-naive patients, with EC
50
s ranging between 0.15 and 8.57 nM. Maintenance of replicon-containing cells in medium containing dasabuvir at concentrations 10-fold or 100-fold greater than the EC
50
resulted in selection of resistant replicon clones. Sequencing of the NS5B coding regions from these clones revealed the presence of variants, including C316Y, M414T, Y448C, Y448H, and S556G, that are consistent with binding to the palm I site of HCV polymerase. Consequently, dasabuvir retained full activity against replicons known to confer resistance to other polymerase inhibitors, including the S282T variant in the nucleoside binding site and the M423T, P495A, P495S, and V499A single variants in the thumb domain. The use of dasabuvir in combination with inhibitors targeting HCV NS3/NS4A protease (ABT-450 with ritonavir) and NS5A (ombitasvir) is in development for the treatment of HCV genotype 1 infections.
Activity of Eravacycline against Enterobacteriaceae and Acinetobacter baumannii, Including Multidrug-Resistant Isolates, from New York City
Authors: Abdallah Marie , Olafisoye Olawole , Cortes Christopher , Urban Carl , Landman David , Quale John
Published: December 2014

Eravacycline demonstrated
in vitro
activity against a contemporary collection of more than 4,000 Gram-negative pathogens from New York City hospitals, with MIC
50
/MIC
90
values, respectively, for
Escherichia coli
of 0.12/0.5 μg/ml,
Klebsiella pneumoniae
of 0.25/1 μg/ml,
Enterobacter aerogenes
of 0.25/1 μg/ml,
Enterobacter cloacae
0.5/1 μg/ml, and
Acinetobacter baumannii
of 0.5/1 μg/ml. Activity was retained against multidrug-resistant isolates, including those expressing KPC and OXA carbapenemases. For
A. baumannii
, eravacycline MICs correlated with increased expression of the
adeB
gene.
A Cronobacter turicensis O1 Antigen-Specific Monoclonal Antibody Inhibits Bacterial Motility and Entry into Epithelial Cells
Authors: Schauer Kristina , Lehner Angelika , Dietrich Richard , Kleinsteuber Ina , Canals Rocío , Zurfluh Katrin , Weiner Kerstin , Märtlbauer Erwin
Published: December 2014

Cronobacter turicensis
is an opportunistic foodborne pathogen that can cause a rare but sometimes lethal infection in neonates. Little is known about the virulence mechanisms and intracellular lifestyle of this pathogen. In this study, we developed an IgG monoclonal antibody (MAb; MAb 2G4) that specifically recognizes the O1 antigen of
C. turicensis
cells. The antilipopolysaccharide antibody bound predominantly monovalently to the O antigen and reduced bacterial growth without causing cell agglutination. Furthermore, binding of the antibody to the O1 antigen of
C. turicensis
cells caused a significant reduction of the membrane potential which is required to energize flagellar rotation, accompanied by a decreased flagellum-based motility. These results indicate that binding of IgG to the O antigen of
C. turicensis
causes a direct antimicrobial effect. In addition, this feature of the antibody enabled new insight into the pathogenicity of
C. turicensis
. In a tissue culture infection model, pretreatment of
C. turicensis
with MAb 2G4 showed no difference in adhesion to human epithelial cells, whereas invasion of bacteria into Caco-2 cells was significantly inhibited.
Protective and Pathological Functions of CD8+T Cells in Leishmania braziliensis Infection
Authors: Cardoso Thiago Marconi , Machado Álvaro , Costa Diego Luiz , Carvalho Lucas P. , Queiroz Adriano , Machado Paulo , Scott Phillip , Carvalho Edgar M. , Bacellar Olívia
Published: December 2014

Cutaneous leishmaniasis (CL) caused byLeishmania braziliensisis characterized by a strong Th1 response that leads to skin lesion development. In areas whereL. braziliensistransmission is endemic, up to 15% of healthy subjects have tested positive for delayed-type hypersensitivity to soluble leishmania antigen (SLA) and are considered to have subclinical (SC) infection. SC subjects produce less gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α) than do CL patients, but they are able to control the infection. The aim of this study was to characterized the role of CD8+T cells in SC infection and in CL. Peripheral blood mononuclear cells (PBMC) were stimulated with SLA to determine the frequencies of CD4+IFN-γ+and CD8+IFN-γ+T cells. Monocytes from PBMC were infected withL. braziliensisand cocultured with CD8+T cells, and the frequencies of infected monocytes and levels of cytotoxicity markers, target cell apoptosis, and granzyme B were determined. The frequency of CD8+IFN-γ+cells after SLA stimulation was higher for SC individuals than for CL patients. The frequency of infected monocytes in SC cells was lower than that in CL cells. CL CD8+T cells induced more apoptosis of infected monocytes than did SC CD8+T cells. Granzyme B production in CD8+T cells was higher in CL than in SC cells. While the use of a granzyme B inhibitor decreased the number of apoptotic cells in the CL group, the use of z-VAD-FMK had no effect on the frequency of these cells. These results suggest that CL CD8+T cells are more cytotoxic and may be involved in pathology.
Divergent Targets of Aspergillus fumigatus AcuK and AcuM Transcription Factors during Growth
In Vitro
versus Invasive Disease
Authors: Pongpom Monsicha , Liu Hong , Xu Wenjie , Snarr Brendan D. , Sheppard Donald C. , Mitchell Aaron P. , Filler Scott G.
Published: December 2014

In
Aspergillus nidulans
, the AcuK and AcuM transcription factors form a complex that regulates gluconeogenesis. In
Aspergillus fumigatus
, AcuM governs gluconeogenesis and iron acquisition
in vitro
and virulence in immunosuppressed mice. However, the function of AcuK was previously unknown. Through
in vitro
studies, we found that
A. fumigatus
Δ
acuK
single and Δ
acuK
Δ
acuM
double mutants had impaired gluconeogenesis and iron acquisition, similar to the Δ
acuM
mutant. Also, the Δ
acuK
, Δ
acuM
, and Δ
acuK
Δ
acuM
mutants had similar virulence defects in mice. However, the Δ
acuK
mutant had a milder defect in extracellular siderophore activity and induction of epithelial cell damage
in vitro
than did the Δ
acuM
mutant. Moreover, overexpression of
acuM
in the Δ
acuK
mutant altered expression of 3 genes and partially restored growth under iron-limited conditions, suggesting that AcuM can govern some genes independently of AcuK. Although the Δ
acuK
and Δ
acuM
mutants had very similar transcriptional profiles
in vitro
, their transcriptional profiles during murine pulmonary infection differed both from their
in vitro
profiles and from each other. While AcuK and AcuM governed the expression of only a few iron-responsive genes
in vivo
, they influenced the expression of other virulence-related genes, such as
hexA
and
dvrA
. Therefore, in
A. fumigatus
, while AcuK and AcuM likely function as part of the same complex, they can also function independently of each other. Furthermore, AcuK and AcuM have different target genes
in vivo
than
in vitro
, suggesting that
in vivo
infection stimulates unique transcriptional regulatory pathways in
A. fumigatus
.
Pathogenic Leptospira Species Acquire Factor H and Vitronectin via the Surface Protein LcpA
Authors: da Silva Ludmila Bezerra , Miragaia Lidia dos Santos , Breda Leandro Carvalho Dantas , Abe Cecilia Mari , Schmidt Mariana Costa Braga , Moro Ana Maria , Monaris Denize , Conde Jonas Nascimento , Józsi Mihály , Isaac Lourdes , Abreu Patrícia Antônia Estima , Barbosa Angela Silva
Published: December 2014

Upon infection, pathogenic
Leptospira
species bind several complement regulators in order to overcome host innate immunity. We previously characterized a 20-kDa leptospiral surface protein which interacts with C4b binding protein (C4BP):
l
eptospiral
c
omplement regulator-acquiring
p
rotein A (LcpA). Here we show that LcpA also interacts with human factor H (FH), which remains functionally active once bound to the protein. Antibodies directed against short consensus repeat 20 (SCR20) inhibited binding of FH to LcpA by approximately 90%, thus confirming that this particular domain is involved in the interaction. We have also shown for the first time that leptospires bind human vitronectin and that the interaction is mediated by LcpA. Coincubation with heparin blocked LcpA-vitronectin interaction in a dose-dependent manner, strongly suggesting that binding may occur through the heparin binding domains of vitronectin. LcpA also bound to the terminal pathway component C9 and inhibited Zn
2+
-induced polymerization and membrane attack complex (MAC) formation. Competitive binding assays indicated that LcpA interacts with C4BP, FH, and vitronectin through distinct sites. Taken together, our findings indicate that LcpA may play a role in leptospiral immune evasion.
A Novel DNA-Binding Protein Plays an Important Role in Helicobacter pylori Stress Tolerance and Survival in the Host
Authors: Wang Ge , Maier Robert J.
Published: December 2014

The gastric pathogen
Helicobacter pylori
must combat chronic acid and oxidative stress. It does so via many mechanisms, including macromolecule repair and gene regulation. Mitomycin C-sensitive clones from a transposon mutagenesis library were screened. One sensitive strain contained the insertion element at the locus of
hp119
, a hypothetical gene. No homologous gene exists in any (non-
H. pylori
) organism. Nevertheless, the predicted protein has some features characteristic of histone-like proteins, and we showed that purified HP119 protein is a DNA-binding protein. A Δ
hp119
strain was markedly more sensitive (viability loss) to acid or to air exposure, and these phenotypes were restored to wild-type (WT) attributes upon complementation of the mutant with the wild-type version of
hp119
at a separate chromosomal locus. The mutant strain was approximately10-fold more sensitive to macrophage-mediated killing than the parent or the complemented strain. Of 12 mice inoculated with the wild type, all contained
H. pylori
, whereas 5 of 12 mice contained the mutant strain; the mean colonization numbers were 158-fold less for the mutant strain. A proteomic (two-dimensional PAGE with mass spectrometric analysis) comparison between the Δ
hp119
mutant and the WT strain under oxidative stress conditions revealed a number of important antioxidant protein differences; SodB, Tpx, TrxR, and NapA, as well as the peptidoglycan deacetylase PgdA, were significantly less expressed in the Δ
hp119
mutant than in the WT strain. This study identified HP119 as a putative histone-like DNA-binding protein and showed that it plays an important role in
Helicobacter pylori
stress tolerance and survival in the host.
Chronic meningitis with intracranial hypertension and bilateral neuroretinitis followingMycoplasma pneumoniaeinfection
Authors: Karampatsas Konstantinos , Patel Himanshu , Basheer Sheikh N , Prendergast Andrew J
Published: December 2014

A previously well 12-year-old boy presented with a 2-week history of headache, nausea, vomiting and left-sided weakness. He subsequently developed meningism, right abducens nerve palsy, persistent papilloedema and reduced visual acuity in association with a bilateral macular star, consistent with neuroretinitis. Cerebrospinal fluid (CSF) examination indicated chronic meningitis and serological testing confirmed recentMycoplasma pneumoniaeinfection, although PCR in CSF was negative. He was treated for aseptic meningitis with ceftriaxone, aciclovir, azithromycin and acetazolamide for intracranial hypertension, with gradual improvement in clinical condition and visual acuity over several weeks. This is the first report ofM. pneumoniaechronic meningitis further complicated with bilateral neuroretinitis and intracranial hypertension. Evidence of central nervous system inflammation in the absence of direct infection suggests an immune-mediated pathophysiology. Although the use of macrolides with antibiotic and immunomodulatory activity might be beneficial, it was not possible to ascertain whether it influenced clinical recovery in this case.
The impact of dreissenid mussels on growth of the fragile papershell (Leptodea fragilis), the most abundant unionid species in Lake Erie
Authors: Krebs Robert A. , Barkett Elizabeth M. , Begley Matthew T.
Published: December 2014

The arrival of zebra mussels (Dreissena polymorpha (Pallas, 1771)) and subsequently quagga mussels (Dreissena bugensis Andrusov, 1897) (Dreissenidae) in the Great Lakes in the 1980s induced many changes, most notably the devastation of native freshwater mussel species. Recently, empty shells of the fragile papershell (Leptodea fragilis (Rafinesque, 1820)) have become common, particularly in the western basin of Lake Erie, suggesting that this fast-growing species may be increasing in numbers in the lake. To examine continued competition with dreissenids, shell age and length of L. fragilis were used to contrast lifespan and growth rate, estimated as the slope of age on shell length, for shells from two beach localities where byssal threads were present on most shells and two sites where dreissenids were rare or absent. Few recent shells from Lake Erie beaches exceeded 5 years of age, and byssal thread counts were more numerous on older shells. Growth and lifespan were estimated to be significantly lower where dreissenid mussels remained numerous than when measured either from historic collections along Lake Erie or from protected populations. Therefore, even for this early-reproducing species, competition from dreissenids may continue to interfere with growth and shorten lifespan, which are effects few other unionid species can likely tolerate sufficiently to sustain population growth.
The local structure and crystallization of FeB nanoparticle
Authors: Kien P. H. , Thao N. T. , Hung P. K.
Published: December 2014

Using molecular dynamics simulation, we have studied the structural evolution of FeB nanoparticle under annealing and the physical properties of its polymorphs such as crystalline, amorphous and mixed samples. The main focus of present work is the crystallization mechanism and the local structure of polymorphs of FeB nanoparticle. The simulation result shows that the amorphous sample undergoes the crystallization via the nucleation mechanism. During the crystallization, B atoms move out the places where the Fe crystal locates, and diffuse to the boundary region of Fe crystal. The crystal growth proceeds when this boundary region attains specific properties which are defined by the fraction of B atoms and the energies of AB -atoms and CB -atoms. Further our study indicates that unlike amorphous sample, the crystalline and mixed samples consist of three distinct parts including Fe crystalline and two FeB amorphous parts ( B -poor and B -rich amorphous part). The different polymorphs of FeB nanoparticle differ in the local structure, size of Fe crystal and energies of different type atoms.
ASAP: An Automatic Algorithm Selection Approach for Planning
Authors: Vallati Mauro , Chrpa Lukáš , Kitchin Diane
Published: December 2014

Despite the advances made in the last decade in automated planning, no planner outperforms all the others in every known benchmark domain. This observation motivates the idea of selecting different planning algorithms for different domains. Moreover, the planners' performances are affected by the structure of the search space, which depends on the encoding of the considered domain. In many domains, the performance of a planner can be improved by exploiting additional knowledge, for instance, in the form of macro-operators or entanglements.

In this paper we propose ASAP, an automatic Algorithm Selection Approach for Planning that: (i) for a given domain initially learns additional knowledge, in the form of macro-operators and entanglements, which is used for creating different encodings of the given planning domain and problems, and (ii) explores the 2 dimensional space of available algorithms, defined as encodings–planners couples, and then (iii) selects the most promising algorithm for optimising either the runtimes or the quality of the solution plans.
Planck stars
Authors: Rovelli Carlo , Vidotto Francesca
Published: December 2014

Quantum-gravitational pressure can stop gravitational collapse and cause a bounce. We observe that: (i) due to the huge time dilation, the process can last micro-seconds in local proper time and billions of years observed from the outside; (ii) the bounce volume can be much larger than planckian, because the onset of quantum-gravity effects is governed by density, not size; (iii) the emerging object can then be bigger than planckian by a factor (m/mP)n, where m is the initial mass, mP is the Planck mass, and n positive; (iv) the interior of an evaporating hole can keep memory of the initial mass, providing an independent scale for the physics of the final explosion. If so, primordial black holes could produce a detectable signal of quantum gravitational origin, which we estimate, under some hypotheses, around the wavelength 10-14 cm.
Stable FLRW solutions in generalized massive gravity
Authors: de Rham Claudia , Fasiello Matteo , Tolley Andrew J.
Published: December 2014

We present exact Friedmann Lemaítre Robertson Walkers (FLRW) solutions in generalized massive gravity where the mass parameters are naturally promoted to Lorentz-invariant functions of the Stückelberg fields. This new dependence relaxes the constraint that would otherwise prevent massive gravity from possessing exact FLRW solutions. It does so without the need to introduce additional degrees of freedom. We find self-accelerating cosmological solutions and show that, with a mild restriction on the region of phase space, these cosmological solutions exhibit full stability, i.e. absence of ghosts and gradient instabilities for all the tensor, vector and scalar modes, for all cosmic time. We perform the full decoupling limit analysis, including vector degrees of freedom, which can be used to confirm the existence of an active Vainshtein mechanism about these solutions.
Genetic Mechanisms of Prebiotic Oligosaccharide Metabolism in Probiotic Microbes
Authors: Goh Yong Jun , Klaenhammer Todd R.
Published: December 2014

Recent insights into the relationship between the human gut and its resident microbiota have revolutionized our appreciation of this symbiosis and its impact on health and disease development. Accumulating evidence on probiotic and prebiotic interventions has demonstrated promising effects on promoting gastrointestinal health by modulating the microbiota toward the enrichment of beneficial microorganisms. However, the precise mechanisms of how prebiotic nondigestible oligosaccharides are metabolized by these beneficial microbes in vivo remain largely unknown. Genome sequencing of probiotic lactobacilli and bifidobacteria has revealed versatile carbohydrate metabolic gene repertoires dedicated to the catabolism of various oligosaccharides. In this review, we highlight recent findings on the genetic mechanisms involved in the utilization of prebiotic fructooligosaccharides, β-galactooligosaccharides, human milk oligosaccharides, and other prebiotic candidates by these probiotic microbes.
What Have We Learned about the Resource Curse?
Authors: Ross Michael L.
Published: December 2014

Since 2001, hundreds of academic studies have examined the “political resource curse,” meaning the claim that natural resource wealth tends to adversely affect a country's governance. There is now robust evidence that one type of mineral wealth, petroleum, has at least three harmful effects: It tends to make authoritarian regimes more durable, to increase certain types of corruption, and to help trigger violent conflict in low- and middle-income countries. Scholars have also made progress toward understanding the mechanisms that lead to these outcomes and the conditions that make them more likely. This essay reviews the evidence behind these claims, the debates over their validity, and some of the unresolved puzzles for future research.
Should We Leave Behind the Subfield of International Relations?
Authors: Reiter Dan
Published: December 2014

This article considers whether political science should abandon the subfields of American politics, comparative politics, and international relations (IR), for new subfields of conflict, political economy, institutions, and behavior. The focus here is whether the field should abandon IR. The article lays out the arguments in favor of abandoning IR, describing scholarly trends that cross conventional subfield lines and are pushing to dissolve IR. Next, it argues that the costs of abandoning IR exceed the benefits, as new subfield divisions would remove some artificial walls but create new ones. Abandoning IR might undermine objective theory testing, would disadvantage the study of international system and structure, and would undermine the ability of political science to inform foreign policy debates. The article concludes by recommending that the field keep IR and its current subfield boundaries but that the walls between subfields should be kept low and porous.
A Hybrid Structure for Data Aggregation in Wireless Sensor Network
Authors: Sajedi Hedieh , Saadati Zahra
Published: December 2014

In recent years, wireless sensor networks have been used for various applications such as environmental monitoring, military and medical applications. A wireless sensor network uses a large number of sensor nodes that continuously collect and send data from a specific region to a base station. Data from sensors are collected from the study area in the common scenario of sensor networks. Afterward, sensed data is sent to the base station. However, neighboring sensors often lead to redundancy of data. Transmission of redundant data to the base station consumes energy and produces traffic, because process is run in a large network. Data aggregation was proposed in order to reduce redundancy in data transformation and traffic. The most popular communication protocol in this field is cluster based data aggregation. Clustering causes energy balance, but sometimes energy consumption is not efficient due to the long distance between cluster heads and base station. In another communication protocol, which is based on a tree construction, because of the short distance between the sensors, energy consumption is low. In this data aggregation approach, since each sensor node is considered as one of the vertices of a tree, the depth of tree is usually high. In this paper, an efficient hierarchical hybrid approach for data aggregation is presented. It reduces energy consumption based on clustering and minimum spanning tree. The benefit of combining clustering and tree structure is reducing the disadvantages of previous structures. The proposed method firstly employs clustering algorithm and then a minimum spanning tree is constructed based on cluster heads. Our proposed method was compared to LEACH which is a well-known data aggregation method in terms of energy consumption and the amount of energy remaining in each sensor network lifetime. Simulation results indicate that our proposed method is more efficient than LEACH algorithm considering energy consumption.