bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and Simulation of Transverse Cracks for Rotor-Bearing Systems
Authors: Yang Tachung , Chen Shi-An
Published: January 2015

Undetected cracking of rotating shafts can lead to catastrophic failure of turbomachinery. This paper investigated the dynamic response of rotor-bearing systems containing transverse cracks with a finite element approach. The breathing effect of cracks was analyzed based on the whirling conditions of the rotor, and different crack models were posed for different rotating speeds. The strain energy released due to the cracks was calculated. Then, the finite element for the shaft portion containing cracks was formulated and incorporated into the system matrices of the rotor-bearing system.
The PGT2, a New 2-MW Class Efficient Gas Turbine: Applications and Operating Experience in Cogeneration
Authors: Benvenuti Erio , Sargenti Marco
Published: January 2015

The PGT2 is a single-shaft gas turbine with a 2 MW ISO electric output that, after an extensive factory development program has been launched into industrial service with a number of cogeneration applications in small-medium size industries. The two-stage high pressure ratio compressor combined with the single-can combustor and the two-stage air-cooled transonic turbine provides a compact and rugged architecture. The turbine inlet temperature in the 1050–1100 °C class and the 12.5:1 pressure ratio provide a 25% electrical efficiency and a high exhaust temperature that make this machine attractive for a variety of both civil and industrial applications like hospitals and pulp and paper mills, textile, tiles, cement, glass and food production. The exhaust heat recovery boiler can be either a commercial unit or compact once-through type of proprietary design that is housed in a vertical exhaust duct to substantially reduce powerplant footprint area when space is limited. The first application that has provided the most extensive operating experience so far is cogeneration in a paper mill in central Italy. Detailed studies on the potential energy saving and on the return of investment cycle were made in collaboration with the client, and provided a valuable basis for further studies that led to additional orders for paper mills, textile and tile industries. The first installed unit is a package comprising a once-through-flow boiler that was full-load tested at the factory before shipping. Commissioning of the cogeneration plant was started in 30 days after shipment and the plant was taken over by the client in less than three months. A dedicated telephone line allows the power plant to be monitored directly from Florence, thus making it possible to gather operational data in real time and to provide this first customer with prompt assistance during the 4-year service and maintenance contract period.

This paper describes the PGT2 design and performance features, the technical and economic evaluations made for the first application, the cogeneration plant layout and a summary of the most significant operational data collected in the initial months or regular service in the paper mill.
Combustor Design Trends for Aircraft Gas Turbine Engines
Authors: Sturgess G. J.
Published: January 2015

Advanced performance trends are surveyed for possible future gas turbine engines to power several classes of military and commercial aircraft. The resulting combustor trends are enumerated. Examples of enabling technology are given. Combustion considerations are discussed, and many commonalities between applications are discovered; fuel/air mixing and combustion dynamics emerge as topics of considerable importance.
Industrial Trent Development and Application
Authors: Roberts J. A.
Published: January 2015

The industrial Trent is the largest aeroderivative gas turbine available, at 50+ MW, and the most efficient gas turbine available to industrial and marine operators, at 42%. Its Dry Low Emissions combustion system embodies the features of the similar combustor on the industrial RB211, which is enjoying very successful service experience.

Its design features and derivation from the aero engine are reviewed, together with an assessment of the maintenance aspects of the engine.

The current status of the engine validation programme is discussed, covering both component rig testing and progress on the full engine testing being carried out in Montreal, Canada.

The applications of the industrial Trent are considered by reviewing the major markets and examining its suitability, both technically and economically, for several existing and emerging sectors.

Launched as a power generation machine, the industrial Trent is shown to be well suited to those sectors which have resulted from the growing deregulation of this industry worldwide. In addition it is shown to be attractive for certain applications in the oil and gas industry and, in the marine market, for some large high speed vessel concepts.
On the Application of Variable Camber Blading in Axial Flow Fans and Compressors
Authors: Saha U. K. , Roy B.
Published: January 2015

For land and marine based gas turbine engines, heavy duty industrial axial flow fans and compressors, variable camber tandem blading seems to be an attractive proposition in the pursuit of high pressure ratio machines under design and off-design power settings. In the present investigations, experiments have been carried out in a cascade wind tunnel to explore the variable camber capability of a tandem blade at two extreme camber settings. Aerodynamic performance studies have been made qualitatively on the basis of static pressure coefficient distribution, diffusion factor and mass averaged loss coefficient data. Experimental evidences demonstrate the possible operation of variable camber blading within a wide range of 20° camber variation.
Detection of Unburned Hydrocarbons (UHC) in an Atmospheric Pressure Combustor With Premixing and Prevaporization Using a Tuneable Excimer Laser
Authors: Lachner Rudolf , Theisen Daniel , Kettl Hans , Fink Rainer , Rist Dieter , Schmid Achim , Hönig Rainer , Kappler Günter
Published: January 2015

Gaseous unburned hydrocarbons (UHC) are investigated in an atmospheric pressure combustor with premixing and prevaporization. The rectangular combustion chamber is equipped with silica quartz windows allowing laser-based investigations in the UV regime. A new double shell concept is employed to atomize the fuel (n-heptane) and to stabilize the flame. For the detection of UHC, a tuneable ArF (λ ≈ 193 nm) or KrF (λ ≈ 248 nm) excimer laser is used. The results show that this imaging technique is feasible in an atmospheric pressure, liquid fuelled combustor. Liquid and gaseous fuel is detected inside the vortices induced by the double shell, where the main combustion processes occur. Furthermore, droplets and UHC can be found along the symmetry line of the double shell. Comparing the two approaches used for the visualization of UHC, it turns out that the application of a KrF laser seems to be more suitable.
A Practical Method for Predicting the Windmilling Characteristics of Simple Turbo Jet Engines
Authors: Choi Min Su , Lim Jin Shik , Hong Yong Shik
Published: January 2015

A practical method for predicting the windmilling performance of simple turbojet engines in flight has been developed. The method incorporates the available loss correlations and analyses to estimate the major engine component performance and requires only basic geometric data. For a given flight Mach number and ambient conditions the steady-state windmilling performance is obtained by equating the compressor input torque to the turbine output torque. The transient performance is obtained from the excess turbine output torque. The present method’s predictions are compared to the available windmilling test data from a typical small simple turbojet engine. They show good agreement over a wide range of flight conditions. Thus, this method can be used during the preliminary design stage of an engine development when the detailed hardware geometry and the component performance data are not yet available.
Automated and nonbiased regional quantification of functional neuroimaging data
Authors: Parker Jason G. , Speidel Benjamin , Sherwood Matthew S.
Published: January 2015

Purpose:

In the quantification of functional neuroimaging data, region‐of‐interest (ROI) analysis can be used to assess a variety of properties of the activation signal, but taken alone these properties are susceptible to noise and may fail to accurately describe overall regional involvement. Here, the authors present and evaluate an automated method for quantification and localization of functional neuroimaging data that combines multiple properties of the activation signal to generate rank‐order lists of regional activation results.

Methods:

The proposed automated quantification method, referred to as neuroimaging results decomposition (NIRD), begins by decomposing an activation map into a hierarchical list of ROIs using a digital atlas. In an intermediate step, the ROIs are rank‐ordered according to extent, mean intensity, and total intensity. A final rank‐order list (NIRD average rank) is created by sorting the ROIs according to the average of their ranks from the intermediate step. The authors hypothesized that NIRD average rank would have improved regional quantification accuracy compared to all other quantitative metrics, including methods based on properties of statistical clusters. To test their hypothesis, NIRD rankings were directly compared to three common cluster‐based methods using simulated fMRI data both with and without realistic head motion.

Results:

For both the no‐motion and motion datasets, an analysis of variance found that significant differences between the quantification methods existed (F = 64.8, p < 0.0001 for no motion; F = 55.2, p < 0.0001 for motion), and a post‐hoc test found that NIRD average rank was the most accurate quantification method tested (p < 0.05 for both datasets). Furthermore, all variants of the NIRD method were found to be significantly more accurate than the cluster‐based methods in all cases.

Conclusions:

These results confirm their hypothesis and demonstrate that the proposed NIRD methodology provides improved regional quantification accuracy compared to cluster‐based methods.
Leukotriene B
4
–mediated sterile inflammation promotes susceptibility to sepsis in a mouse model of type 1 diabetes
Authors: Filgueiras Luciano Ribeiro , Brandt Stephanie L. , Wang Soujuan , Wang Zhuo , Morris David L. , Evans-Molina Carmella , Mirmira Raghavendra G. , Jancar Sonia , Serezani C. Henrique
Published: January 2015

Inhibiting the production of a leukotriene may help type 1 diabetic patients from succumbing to sepsis.
Phosphorylation of FADD by the kinase CK1α promotes KRAS
G12D
-induced lung cancer
Authors: Bowman Brittany M. , Sebolt Katrina A. , Hoff Benjamin A. , Boes Jennifer L. , Daniels Danette L. , Heist Kevin A. , Galbán Craig J. , Patel Rajiv M. , Zhang Jianke , Beer David G. , Ross Brian D. , Rehemtulla Alnawaz , Galbán Stefanie
Published: January 2015

Mutant KRAS promotes mitosis by stimulating phosphorylation of the adaptor protein FADD.
Mutant KRAS triggers an inflammatory attraction
Authors: Ferrarelli Leslie K.
Published: January 2015

Oncogenic KRAS in the pancreas attracts proinflammatory macrophages by inducing the secretion of a chemokine.
In Vitro
Assessment of Dual Drug Combinations To Inhibit Growth of Neisseria gonorrhoeae
Authors: Pettus Kevin , Sharpe Samera , Papp John R.
Published: January 2015

The development of resistance to first-line antimicrobial therapies has led to recommendations for combination therapies for the treatment of gonorrhea infection. Recent studies have shown the success of combination therapies in treating patients, but few have reported on the
in vitro
activities of these drug combinations. An
in vitro
assessment of azithromycin in combination with gentamicin demonstrated inhibition of growth and suggests that clinical trials may be warranted to assess the utility of this combination in treating gonorrhea infections.
In Vivo
Efficacy of Anuran Trypsin Inhibitory Peptides against Staphylococcal Skin Infection and the Impact of Peptide Cyclization
Authors: Malik U. , Silva O. N. , Fensterseifer I. C. M. , Chan L. Y. , Clark R. J. , Franco O. L. , Daly N. L. , Craik D. J.
Published: January 2015

Staphylococcus aureus
is a virulent pathogen that is responsible for a wide range of superficial and invasive infections. Its resistance to existing antimicrobial drugs is a global problem, and the development of novel antimicrobial agents is crucial. Antimicrobial peptides from natural resources offer potential as new treatments against staphylococcal infections. In the current study, we have examined the antimicrobial properties of peptides isolated from anuran skin secretions and cyclized synthetic analogues of these peptides. The structures of the peptides were elucidated by nuclear magnetic resonance (NMR) spectroscopy, revealing high structural and sequence similarity with each other and with sunflower trypsin inhibitor 1 (SFTI-1). SFTI-1 is an ultrastable cyclic peptide isolated from sunflower seeds that has subnanomolar trypsin inhibitory activity, and this scaffold offers pharmaceutically relevant characteristics. The five anuran peptides were nonhemolytic and noncytotoxic and had trypsin inhibitory activities similar to that of SFTI-1. They demonstrated weak
in vitro
inhibitory activities against
S. aureus
, but several had strong antibacterial activities against
S. aureus
in an
in vivo
murine wound infection model. pYR, an immunomodulatory peptide from
Rana sevosa
, was the most potent, with complete bacterial clearance at 3 mg · kg
−1
. Cyclization of the peptides improved their stability but was associated with a concomitant decrease in antimicrobial activity. In summary, these anuran peptides are promising as novel therapeutic agents for treating infections from a clinically resistant pathogen.
Neutralization of Staphylococcal Enterotoxin B by an Aptamer Antagonist
Authors: Wang Kaiyu , Gan Longjie , Jiang Li , Zhang Xianhui , Yang Xiangyue , Chen Min , Lan Xiaopeng
Published: January 2015

Staphylococcal enterotoxin B (SEB) is a major virulence factor for staphylococcal toxic shock syndrome (TSS). SEB activates a large subset of the T lymphocytic population, releasing proinflammatory cytokines. Blocking SEB-initiated toxicity may be an effective strategy for treating TSS. Using a process known as systematic evolution of ligands by exponential enrichment (SELEX), we identified an aptamer that can antagonize SEB with nanomolar binding affinity (

K
d

= 64 nM). The aptamer antagonist effectively inhibits SEB-mediated proliferation and cytokine secretion in human peripheral blood mononuclear cells. Moreover, a PEGylated aptamer antagonist significantly reduced mortality in a “double-hit” mouse model of SEB-induced TSS, established via sensitization with
d
-galactosamine followed by SEB challenge. Therefore, our novel aptamer antagonist may offer potential therapeutic efficacy against SEB-mediated TSS.
Safety and Pharmacokinetics of Isavuconazole as Antifungal Prophylaxis in Acute Myeloid Leukemia Patients with Neutropenia: Results of a Phase 2, Dose Escalation Study
Authors: Cornely Oliver A. , Böhme Angelika , Schmitt-Hoffmann Anne , Ullmann Andrew J.
Published: January 2015

Isavuconazole is a novel broad-spectrum triazole antifungal agent. This open-label dose escalation study assessed the safety and pharmacokinetics of intravenous isavuconazole prophylaxis in patients with acute myeloid leukemia who had undergone chemotherapy and had preexisting/expected neutropenia. Twenty-four patients were enrolled, and 20 patients completed the study. The patients in the low-dose cohort (
n
= 11) received isavuconazole loading doses on day 1 (400/200/200 mg, 6 h apart) and day 2 (200/200 mg, 12 h apart), followed by once-daily maintenance dosing (200 mg) on days 3 to 28. The loading and maintenance doses were doubled in the high-dose cohort (
n
= 12). The mean ± standard deviation plasma isavuconazole areas under the concentration-time curves for the dosing period on day 7 were 60.1 ± 22.3 μg · h/ml and 113.1 ± 19.6 μg · h/ml for the patients in the low-dose and high-dose cohorts, respectively. The adverse events in five patients in the low-dose cohort and in eight patients in the high-dose cohort were considered to be drug related. Most were mild to moderate in severity, and the most common adverse events were headache and rash (
n
= 3 each). One patient in the high-dose cohort experienced a serious adverse event (unrelated to isavuconazole treatment), and two patients each in the low-dose and high-dose cohorts discontinued the study due to adverse events. Of the 20 patients who completed the study, 18 were classified as a treatment success. In summary, the results of this analysis support the safety and tolerability of isavuconazole administered at 200 mg and 400 mg once-daily as prophylaxis in immunosuppressed patients at high risk of fungal infections. (This study is registered at ClinicalTrials.gov under registration number NCT00413439.)
Evolutionary Adaptation of an AraC-Like Regulatory Protein in Citrobacter rodentium and Escherichia Species
Authors: Tan Aimee , Petty Nicola K. , Hocking Dianna , Bennett-Wood Vicki , Wakefield Matthew , Praszkier Judyta , Tauschek Marija , Yang Ji , Robins-Browne Roy
Published: January 2015

The evolution of pathogenic bacteria is a multifaceted and complex process, which is strongly influenced by the horizontal acquisition of genetic elements and their subsequent expression in their new hosts. A well-studied example is the RegA regulon of the enteric pathogen
Citrobacter rodentium
. The RegA regulatory protein is a member of the AraC/XylS superfamily, which coordinates the expression of a gene repertoire that is necessary for full pathogenicity of this murine pathogen. Upon stimulation by an exogenous, gut-associated signal, namely, bicarbonate ions, RegA activates the expression of a series of genes, including virulence factors, such as autotransporters, fimbriae, a dispersin-like protein, and the
grlRA
operon on the locus of enterocyte effacement pathogenicity island. Interestingly, the genes encoding RegA homologues are distributed across the genus
Escherichia
, encompassing pathogenic and nonpathogenic subtypes. In this study, we carried out a series of bioinformatic, transcriptional, and functional analyses of the RegA regulons of these bacteria. Our results demonstrated that
regA
has been horizontally transferred to
Escherichia
spp. and
C. rodentium
. Comparative studies of two RegA homologues, namely, those from
C. rodentium
and
E. coli
SMS-3-5, a multiresistant environmental strain of
E. coli
, showed that the two regulators acted similarly
in vitro
but differed in terms of their abilities to activate the virulence of
C. rodentium
in vivo
, which evidently was due to their differential activation of
grlRA
. Our data indicate that RegA from
C. rodentium
has strain-specific adaptations that facilitate infection of its murine host. These findings shed new light on the development of virulence by
C. rodentium
and on the evolution of virulence-regulatory genes of bacterial pathogens in general.
Identification and Characterization of VpsR and VpsT Binding Sites in Vibrio cholerae
Authors: Zamorano-Sánchez David , Fong Jiunn C. N. , Kilic Sefa , Erill Ivan , Yildiz Fitnat H.
Published: January 2015

The ability to form biofilms is critical for environmental survival and transmission ofVibrio cholerae, a facultative human pathogen responsible for the disease cholera. Biofilm formation is controlled by several transcriptional regulators and alternative sigma factors. In this study, we report that the two main positive regulators of biofilm formation, VpsR and VpsT, bind to nonoverlapping target sequences in the regulatory region ofvpsL in vitro. VpsR binds to a proximal site (the R1 box) as well as a distal site (the R2 box) with respect to the transcriptional start site identified upstream ofvpsL. The VpsT binding site (the T box) is located between the R1 and R2 boxes. While mutations in the T and R boxes resulted in a decrease invpsLexpression, deletion of the T and R2 boxes resulted in an increase invpsLexpression. Analysis of the role of H-NS invpsLexpression revealed that deletion ofhnsresulted in enhancedvpsLexpression. The level ofvpsLexpression was higher in anhns vpsTdouble mutant than in the parental strain but lower than that in anhnsmutant.In silicoanalysis of the regulatory regions of the VpsR and VpsT targets resulted in the identification of conserved recognition motifs for VpsR and VpsT and revealed that operons involved in biofilm formation andvpsTare coregulated by VpsR and VpsT. Furthermore, a comparative genomics analysis revealed substantial variability in the promoter region of thevpsTandvpsLgenes among extantV. choleraeisolates, suggesting that regulation of biofilm formation is under active selection.

IMPORTANCEVibrio choleraecauses cholera and is a natural inhabitant of aquatic environments. One critical factor that is important for environmental survival and transmission ofV. choleraeis the microbe's ability to form biofilms, which are surface-associated communities encased in a matrix composed of the exopolysaccharide VPS (Vibriopolysaccharide), proteins, and nucleic acids. Two proteins, VpsR and VpsT, positively regulate VPS production and biofilm formation. We characterized the structural features of the promoter of thevpsLgene, determined the target sequences recognized by VpsT and VpsR, and analyzed their distribution and conservation patterns in multipleV. choleraeisolates. This work fills a fundamental gap in our understanding of the regulatory mechanisms employed by the master regulators VpsR and VpsT in controlling biofilm matrix production.
Association of pulmonary silicosis and systemic sclerosis
Authors: Ben Abdelghani Kaouther , Fazaa Alia , Souabni Leila , Zakraoui Leith
Published: January 2015

The Erasmus syndrome describes the association of generalised systemic sclerosis following exposure to silica with or without silicosis. This is a case report on a male patient presenting with this syndrome. Radiological changes of silicosis have preceded the diagnosis of systemic sclerosis by 6 years and occupational exposure has been stopped. The clinical features did not differ from systemic sclerosis in general. The evolution was marked by a progression of skin lesions whereas pulmonary lesion remained stable.
The kinetics of blood lactate in boys during and following a single and repeated all-out sprints of cycling are different than in men
Authors: Engel Florian Azad , Sperlich Billy , Stockinger Christian , Härtel Sascha , Bös Klaus , Holmberg Hans-Christer
Published: January 2015

This study characterized the impact of high-intensity interval training on the kinetics of blood lactate and performance in trained boys and men. Twenty-one boys (11.4 ± 0.8 years) and 19 men (29.4 ± 5.0 years) performed a set of four 30-s sprints with 2-min of rest and a single 30-s sprint on 2 separate occasions (randomized order) with assessment of performance. Blood lactate was assayed after each sprint and during 30 min of recovery from both tests. The individual time-curves of blood lactate concentration were fitted to the biexponential function as follows: [Formula: see text], where the velocity parameters γ1and γ2reflect the capacity to release lactate from the previously active muscle into the blood and to subsequently eliminate lactate from the organism, respectively. In both tests, peak blood lactate concentration was significantly lower in the boys (four 30-s sprints: 12.2 ± 3.6 mmol·L−1; single 30-s sprint: 8.7 ± 1.8 mmol·L−1) than men (four 30-s sprints: 16.1 ± 3.3 mmol·L−1; single 30-s sprint: 11.5 ± 2.1; p < 0.001). The boys exhibited faster γ1(1.4531 ± 0.65 min; p < 0.001) and γ2(0.059 ± 0.023 min; p = 0.01) in the single 30-s sprint and faster γ2(0.049 ± 0.016 min; p = 0.01) in the four 30-s sprints. The worsening of performance from the first to the last of the four 30-s sprints was less pronounced in boys (9.2% ± 13.9%) than men (19.2% ± 11.5%; p = 0.01). In the present study boys, when compared with men, exhibited lower Peak blood lactate concentration; less pronounced decline in performance during the sprints concomitantly with more rapid release and elimination during the single 30-s sprint; and faster elimination of lactate following the four 30-s sprints.
On the mechanism of phosphoenolpyruvate synthetase (PEPs) and its inhibition by sodium fluoride: potential magnesium and aluminum fluoride complexes of phosphoryl transfer
Authors: McCormick Nicole E. , Jakeman David L.
Published: January 2015

Phosphoenolpyruvate synthase (PEPs) catalyzes the conversion of pyruvate to phosphoenolpyruvate (PEP) using a two-step mechanism invoking a phosphorylated-His intermediate. Formation of PEP is an initial step in gluconeogenesis, and PEPs is essential for growth of Escherichia coli on 3-carbon sources such as pyruvate. The production of PEPs has also been linked to bacterial virulence and antibiotic resistance. As such, PEPs is of interest as a target for antibiotic development, and initial investigations of PEPs have indicated inhibition by sodium fluoride. Similar inhibition has been observed in a variety of phospho-transfer enzymes through the formation of metal fluoride complexes within the active site. Herein we quantify the inhibitory capacity of sodium fluoride through a coupled spectrophotometric assay. The observed inhibition provides indirect evidence for the formation of a MgF3−complex within the enzyme active site and insight into the phospho-transfer mechanism of PEPs. The effect of AlCl3on PEPs enzyme activity was also assessed and found to decrease substrate binding and turnover.
Parametric study of buried steel and high density polyethylene gas pipelines due to oblique-reverse faulting
Authors: Rofooei Fayaz Rahimzadeh , Jalali Himan Hojat , Attari Nader Khajeh Ahmad , Kenarangi Hadi , Samadian Masoud
Published: January 2015

A numerical study is carried out on buried steel and high density polyethylene (HDPE) pipelines subjected to oblique-reverse faulting. The components of the oblique-reverse offset along the horizontal and normal directions in the fault plane are determined using well-known empirical equations. The numerical model is validated using the experimental results and detailed finite element model of a 114.3 mm (4″) steel gas pipe subjected to a reverse fault offset up to 0.6 m along the faulting direction. Different parameters such as the pipe material, the burial depth to the pipe diameter ratio (H/D), the pipe diameter to wall thickness ratio (D/t), and the fault–pipe crossing angle are considered and their effects on the response parameters are discussed. The maximum and minimum compressive strains are observed at crossing angles of 30° and 90°, respectively. It is found that the dimensionless parameters alone are not sufficient for comparison purposes. Comparing steel and HDPE pipes, it is observed that HDPE pipes show larger compressive strains due to their lower strength and stiffness. For both steel and HDPE pipes, peak strains increase with increasing D/t and H/D ratio for a constant pipe diameter and fault offset. For a given H/D ratio, compressive strains increase with increasing D/t ratio in HDPE pipes, while in steel pipes considered in this study, this effect is negligible. Finally, the peak strains of the pipes are compared to those suggested by Canadian Standard Association for Oil and Gas Pipeline System, CSA Z662.
Lu–Hf zircon and Sm–Nd whole-rock isotope constraints on the extent of juvenile arc crust in Avalonia: examples from Newfoundland and Nova Scotia, Canada
Authors: Pollock J.C. , Sylvester P.J. , Barr S.M.
Published: January 2015

Avalonia, the largest accreted crustal block in the Appalachian orogen, consists of Neoproterozoic magmatic arc sequences that represent protracted and episodic subduction-related magmatism before deposition of an Ediacaran–Ordovician cover sequence including siliciclastic rocks. Zircon crystals were obtained from arc-related magmatic rocks and from clastic sedimentary sequences and analyzed in situ for their Hf-isotope composition. The majority of magmatic and detrital zircons are dominated by initial 176Hf/177Hf values that are more radiogenic than chondritic uniform reservoir (CHUR) with calculated crust formation Hf–TDM model ages that range from 0.84 to 1.30 Ga. These results suggest formation by partial melting of juvenile mantle in a Neoproterozoic continental arc. Some zircons have Hf–TDM model ages ca. 1.39–3.09 Ga with εHf values of –33.9 to –0.5 and more clearly indicate involvement of older lithosphere in their petrogenesis. Whole-rock Sm–Nd isotopic compositions from felsic volcanic rocks are characterized by positive initial εNd values with Mesoproterozoic depleted mantle model ages consistent with juvenile extraction. Results suggest a dominant mantle component with long-term light rare earth element (LREE) depletion mixed with an older crustal component with long-term LREE enrichment. The pattern of TDM model ages and variations in Lu–Hf and Sm–Nd isotopic character are compatible with a ca. 1.0–1.2 Ga igneous tectonomagmatic event that formed basement to Neoproterozoic magmatic arcs in Avalonia. The presence of evolved isotopic signatures, however, indicates that significant older Proterozoic crust is present locally beneath Avalonia, suggesting that Avalonia formed in a single Neoproterozoic arc system that generated juvenile mantle-derived crust, coupled with lesser anatectic reworking of significantly older crust.
Early co-expression of cyclooxygenase-2 and renin in the rat kidney cortex contributes to the development ofNG-nitro-l-arginine methyl ester induced hypertension
Authors: Guzmán-Hernández Elizabeth Alejandrina , Villalobos-Molina Rafael , Sánchez-Mendoza María Alicia , Del Valle-Mondragón Leonardo , Pastelín-Hernández Gustavo , Ibarra-Barajas Maximiliano
Published: January 2015

We investigated the involvement of cyclooxygenase-2 (COX-2) and the renin–angiotensin system in NG-nitro-l-arginine methyl ester (l-NAME)-induced hypertension. Male Wistar rats were treated with l-NAME (75.0 mg·(kg body mass)−1·day−1, in their drinking water) for different durations (1–33 days). COX-2 and renin mRNA were measured using real-time PCR in the renal cortex, and prostanoids were assessed in the renal perfusate, whereas angiotensin II (Ang II) and Ang (1-7) were quantified in plasma. In some rats, nitric oxide synthase inhibition was carried out in conjunction with oral administration of captopril (30.0 mg·kg−1·day−1) or celecoxib (1.0 mg·kg−1·day−1) for 2 or 19 days. We found a parallel increase in renocortical COX-2 and renin mRNA starting at day 2 of treatment with l-NAME, and both peaked at 19–25 days. In addition, l-NAME increased renal 6-Keto-PGF1α(prostacyclin (PGI2) metabolite) and plasma Ang II from day 2, but reduced plasma Ang (1-7) at day 19. Captopril prevented the increase in blood pressure, which was associated with lower plasma Ang II and increased COX-2-derived 6-Keto-PGF1αat day 2 and plasma Ang (1-7) at day 19. Celecoxib partially prevented the increase in blood pressure; this effect was associated with a reduction in plasma Ang II. These findings indicate that renal COX-2 expression increased in parallel with renin expression, renal PGI2synthesis, and plasma Ang II in l-NAME-induced hypertension.
An update on the association of vitamin D deficiency with common infectious diseases
Authors: Watkins Richard R. , Lemonovich Tracy L. , Salata Robert A.
Published: January 2015

Vitamin D plays an important role in modulating the immune response to infections. Deficiency of vitamin D is a common condition, affecting both the general population and patients in health care facilities. Over the last decade, an increasing body of evidence has shown an association between vitamin D deficiency and an increased risk for acquiring several infectious diseases, as well as poorer outcomes in vitamin D deficient patients with infections. This review details recent developments in understanding the role of vitamin D in immunity, the antibacterial actions of vitamin D, the association between vitamin D deficiency and common infections (like sepsis, pneumonia, influenza, methicillin-resistant Staphylococcus aureus, human immunodeficiency virus type-1 (HIV), and hepatitis C virus (HCV)), potential therapeutic implications for vitamin D replacement, and future research directions.
A generalized Potts model for confocal microscopy images
Authors: Máté Gabriell , Heermann Dieter W.
Published: January 2015

Much as being among the least invasive mainstream imaging technologies in life sciences, the resolution of confocal microscopy is limited. Imaged structures, e.g., chromatin-fiber loops, have diameters around or beyond the diffraction limit, and microscopy images show seemingly random spatial density distributions only. While such images are important because the organization of the chromosomes influences different cell mechanisms, many interesting questions can also be related to the observed patterns. These concern their spatial aspects, the role of randomness, the possibility of modeling these images with a random generative process, the interaction between the densities of adjacent loci, the length-scales of these influences, etc. We answer these questions by implementing a generalization of the Potts model. We show how to estimate the model parameters, test the performance of the estimation process and numerically prove that the obtained values converge to the ground truth. Finally, we generate images with a trained model and show that they compare well to real cell images.
Frequency measurement using Rayleigh scattering from a BEC
Authors: Bhattacherjee A. B. , De S.
Published: January 2015

We propose to use superradiant Rayleigh scattering from degenerate Bose gas to detect unknown frequencies coupled to the pump laser beam. Theoretically we show a measurement of the time evolution of population at the initial momentum state could determine the unknown frequency with respect to a known one at which the pump laser's frequency modulates. We show a range of frequencies from kHz to MHz could be determined with this method at the currently available state-of-the-art technology.
Study of strong-coupling impurity bound polaron in a quantum pseudodot
Authors: Khordad R.
Published: January 2015

In the present work, we have studied the first internal excited state energy and transition frequency of strong-coupling impurity bound polaron in a quantum pseudodot using the well-known Lee–Low–Pines (LLP) unitary transformation method. We show the effect of Coulomb bound potential, electron–phonon (e–p) coupling strength, the quantum dot radius and potential height on first internal excited state energy and the transition frequency of the impurity bound polaron. According to the results, it is found that the first internal excited state energy is decreased with increasing quantum dot radius. Also, this energy is increased with enhancing potential height. The transition frequency is increased with increasing the e–p coupling strength. Also, the first internal excited state energy is increased with decreasing the e–p coupling strength. The transition frequency is enhanced with increasing the Coulomb bound potential.
Prediction for the cosmological constant in resummed quantum gravity and constraints on susy GUTs
Authors: Ward B. F. L.
Published: January 2015

We use our resummed quantum gravity approach to Einstein's general theory of relativity in the context of the Planck scale cosmology formulation of Bonanno and Reuter to estimate the value of the cosmological constant such that ρΛ = (0.0024 eV)4. We argue that the closeness of this estimate to experiment constrains Supersymmetric Grand Unified Theory (susy GUT) models. We discuss in turn various theoretical issues that have been raised about the approach itself as well as about the application to estimate the cosmological constant. Given the closeness of the estimate to the currently observed value, we also discuss the theoretical uncertainty in the estimate-at this time, we argue it is still large.
Nematicons routing through two types of disclination lines in chiral nematic liquid crystals
Authors: Kwaśny Michał , Laudyn Urszula A. , Rutkowska Katarzyna A. , Karpierz Mirosław A.
Published: January 2015

In this work, we study nematicons propagation at the disclination lines in a wedge-shaped planarly oriented sample. Using optimal beam parameters for light self-trapping and varying the input beam position and direction of the wave vector k with respect to the z-axis, we gain insight in the nematicons propagation in the highly disturbed area around two different types of disclination lines in chiral nematic.
Optical properties of the different tapered silicon nanowires based on KK relation
Authors: Guo Zhongyi , Zhou Keya , Zhang Anjun , Lee Jung-Ho
Published: January 2015

The optical properties of the various types of tapered silicon nanowires (SiNWs) have been investigated by the phase retrieving method of utilizing the experimental reflection spectra with the aid of the Kramers–Kronig (KK) relation. The effective refractive index (n) and the extinction coefficient (K) of each tapered SiNWs and combined silicon nanowires and microwires (CNMW) array samples can be obtained from concrete simulation by the KK relation. At the same time, we can also obtain the real part (ε′) and imaginary part (ε″) of the effective complex dielectric constant from the relation between the refractive index and the complex dielectric constant of samples. And the simulated results show that the relative material parameters (effective complex refractive index, effective complex dielectric function) can be modulated from a concrete material processing.
INVESTIGATION ON THE KNEE STIFFNESS UNDER THE LATERAL IMPACT FOR THE DESIGN OF PEDESTRIAN LEGFORM IMPACTOR
Authors: MO FUHAO , ARNOUX PIERRE JEAN , KONG CHUNYU , MASSON CATHERINE , MASSENZIO MICHEL , RONEL SYLVIE
Published: January 2015

The objective of the present study is to investigate the stiffness of the knee joint, in order to provide a basis for developing a biofidelic pedestrian legform impactor. A biofidelic lower limb model was employed to replicate structural responses of the human knee joint by finite element simulations. In the simulation, a single displacement was imposed on the thigh or leg, and constrained six freedoms of the other part. As a result, nonlinear load-displacement data were approximated by a linear regression to determine the stiffness. Considering knee joint kinematics under lateral car-pedestrian impacts, a stiffness matrix was established including lateral bending, lateral shearing and torsion effects that significantly influence pedestrian lower limb injuries. Then, this stiffness matrix was applied in a developed legform model. The structural responses of the legform were obtained by the impact with a family car model. Finally, the legform biofidelity was evaluated by comparing the global kinematics of the pedestrian lower limb.
Well-Aligned Graphene Oxide Nanosheets Decorated with Zinc Oxide Nanocrystals for High Performance Photocatalytic Application
Authors: Kaviyarasu K. , Magdalane C. Maria , Manikandan E. , Jayachandran M. , Ladchumananandasivam R. , Neelamani S. , Maaza M.
Published: January 2015

Graphene oxide (GO) nanosheets modified with zinc oxide nanocrystals were achieved by a green wet-chemical approach. As-obtained products were characterized by XRD, Raman spectra, XPS, HR-TEM, EDS, PL and Photocatalytic studies. XRD studies indicate that the GO nanosheet have the same crystal structure found in hexagonal form of ZnO . The enhanced Raman spectrum of 2D bands confirmed formation of single layer graphene oxides. The gradual photocatalytic reduction of the GO nanosheet in the GO : ZnO suspension of ethanol was studied by using X-ray photoelectron (XPS) spectroscopy. The nanoscale structures were observed and confirmed using high resolution transmission electron microscopy (HR-TEM). The evolution of the elemental composition, especially the various numbers of layers were determined from energy dispersive X-ray spectra (EDS). PL properties of GO : ZnO nanosheet were found to be dependent on the growth condition and the resultant morphology revealed that GO nanosheet were highly transparent in the visible region. The photocatalytic performance of GO : ZnO nanocomposites was performed under UV irradiation. Therefore, the ZnO nanocrystals in the GO : ZnO composite could be applied in gradual chemical reduction and consequently tuning the electrical conductivity of the graphene oxide nanosheet.
Geometric foundations of Cartan gauge gravity
Authors: Catren Gabriel
Published: January 2015

We use the theory of Cartan connections to analyze the geometrical structures underpinning the gauge-theoretical descriptions of the gravitational interaction. According to the theory of Cartan connections, the spin connection ω and the soldering form θ that define the fundamental variables of the Palatini formulation of general relativity can be understood as different components of a single field, namely a Cartan connection A = ω + θ. In order to stress both the similarities and the differences between the notions of Ehresmann connection and Cartan connection, we explain in detail how a Cartan geometry (PH→ M, A) can be obtained from a G-principal bundle PG→ M endowed with an Ehresmann connection (being the Lorentz group H a subgroup of G) by means of a bundle reduction mechanism. We claim that this reduction must be understood as a partial gauge fixing of the local gauge symmetries of PG, i.e. as a gauge fixing that leaves "unbroken" the local Lorentz invariance. We then argue that the "broken" part of the symmetry — that is the internal local translational invariance — is implicitly preserved by the invariance under the external diffeomorphisms of M.
Synthesis and photodynamics of diphenylethynyl-bridged porphyrin-quinoidal porphyrin hybrids
Authors: Sakatani Shuhei , Kamimura Takuya , Ohkubo Kei , Fukuzumi Shunichi , Tani Fumito
Published: January 2015

As new donor–acceptor hybrids for energy and/or electron transfer, zinc complex and free-base of a porphyrin-quinoidal porphyrin dyad linked by a diphenylethynyl bridge were prepared via Sonogashira and subsequent Takahashi coupling reactions. The quinoidal porphyrin units have two dicyanomethylene groups at the opposite meso-positions. The UV-vis absorption spectra of the dyads were almost linear summations of the absorption spectra of each component in comparison with those of the monomeric reference compounds, indicating very weak electronic interactions between the chromophores at the ground state. Both zinc complex and free-base of the reference porphyrin exhibited fluorescence in the range of ca. 600–700 nm upon photoexcitation, while the quinoidal porphyrin monomers showed no fluorescence. The considerable quenching (more than 99%) of the porphyrin fluorescence in the dyads suggested significant electronic communications between the subunits of the excited state. The electrochemical analysis confirmed that the first oxidations of the dyads occur at the porphyrin units and the first reductions take place at the quinoidal porphyrin units. Femtosecond laser flash photolysis of the zinc dyad with photoexcitation at 393 nm showed both ultrafast (<1 ps) energy and electron transfer from the porphyrin unit to the quinoidal porphyrin one, which processes resulted in the quenching of the porphyrin fluorescence. On the other hand, the free-base dyad underwent only energy transfer.
Plant Adaptation to Acid Soils: The Molecular Basis for Crop Aluminum Resistance
Authors: Kochian Leon V. , Piñeros Miguel A. , Liu Jiping , Magalhaes Jurandir V.
Published: January 2015

Aluminum (Al) toxicity in acid soils is a significant limitation to crop production worldwide, as approximately 50% of the world's potentially arable soil is acidic. Because acid soils are such an important constraint to agriculture, understanding the mechanisms and genes conferring resistance to Al toxicity has been a focus of intense research interest in the decade since the last article on crop acid soil tolerance was published in this journal. An impressive amount of progress has been made during that time that has greatly increased our understanding of the diversity of Al resistance genes and mechanisms, how resistance gene expression is regulated and triggered by Al and Al-induced signals, and how the proteins encoded by these genes function and are regulated. This review examines the state of our understanding of the physiological, genetic, and molecular bases for crop Al tolerance, looking at the novel Al resistance genes and mechanisms that have been identified over the past ten years. Additionally, it examines how the integration of molecular and genetic analyses of crop Al resistance is starting to be exploited for the improvement of crop plants grown on acid soils via both molecular-assisted breeding and biotechnology approaches.
Terrestrial Ecosystems in a Changing Environment: A Dominant Role for Water
Authors: Bernacchi Carl J. , VanLoocke Andy
Published: January 2015

Transpiration—the movement of water from the soil, through plants, and into the atmosphere—is the dominant water flux from the earth's terrestrial surface. The evolution of vascular plants, while increasing terrestrial primary productivity, led to higher transpiration rates and widespread alterations in the global climate system. Similarly, anthropogenic influences on transpiration rates are already influencing terrestrial hydrologic cycles, with an even greater potential for changes lying ahead. Intricate linkages among anthropogenic activities, terrestrial productivity, the hydrologic cycle, and global demand for ecosystem services will lead to increased pressures on ecosystem water demands. Here, we focus on identifying the key drivers of ecosystem water use as they relate to plant physiological function, the role of predicted global changes in ecosystem water uses, trade-offs between ecosystem water use and carbon uptake, and knowledge gaps.
A Structural Perspective on the Regulation of the Epidermal Growth Factor Receptor
Authors: Kovacs Erika , Zorn Julie Anne , Huang Yongjian , Barros Tiago , Kuriyan John
Published: January 2015

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that plays a critical role in the pathogenesis of many cancers. The structure of intact forms of this receptor has yet to be determined, but intense investigations of fragments of the receptor have provided a detailed view of its activation mechanism, which we review here. Ligand binding converts the receptor to a dimeric form, in which contacts are restricted to the receptor itself, allowing heterodimerization of the four EGFR family members without direct ligand involvement. Activation of the receptor depends on the formation of an asymmetric dimer of kinase domains, in which one kinase domain allosterically activates the other. Coupling between the extracellular and intracellular domains may involve a switch between alternative crossings of the transmembrane helices, which form dimeric structures. We also discuss how receptor regulation is compromised by oncogenic mutations and the structural basis for negative cooperativity in ligand binding.
Symmetry-Protected Topological Phases of Quantum Matter
Authors: Senthil T.
Published: January 2015

We describe recent progress in our understanding of the interplay between interactions, symmetry, and topology in states of quantum matter. We focus on a minimal generalization of the celebrated topological band insulators (TBIs) to interacting many-particle systems known as symmetry-protected topological (SPT) phases. As with the TBIs, these states have a bulk gap and no exotic excitations but have nontrivial surface states that are protected by symmetry. We describe the various possible phases and their properties in three-dimensional systems with realistic symmetries. We develop many key ideas for the theory of these states using simple examples. The emphasis is on physical rather than mathematical properties. We survey insights obtained from the study of SPT phases for a number of other theoretical problems.