bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantification of syntrophic acetate‐oxidizing microbial communities in biogas processes
Authors: Westerholm Maria , Dolfing Jan , Sherry Angela , Gray Neil D. , Head Ian M. , Schnürer Anna
Published: March 2011

Changes in communities of syntrophic acetate‐oxidizing bacteria (SAOB) and methanogens caused by elevated ammonia levels were quantified in laboratory‐scale methanogenic biogas reactors operating at moderate temperature (37°C) using quantitative polymerase chain reaction (qPCR). The experimental reactor was subjected to gradually increasing ammonia levels (0.8–6.9 g NH4+‐N l−1), whereas the level of ammonia in the control reactor was kept low (0.65–0.90 g NH4+‐N l−1) during the entire period of operation (660 days). Acetate oxidation in the experimental reactor, indicated by increased production of 14CO2 from acetate labelled in the methyl carbon, occurred when ammonia levels reached 5.5 and 6.9 g NH4+‐N l−1. Syntrophic acetate oxidizers targeted by newly designed qPCR primers were Thermacetogenium phaeum, Clostridium ultunense, Syntrophaceticus schinkii and Tepidanaerobacter acetatoxydans. The results showed a significant increase in abundance of all these bacteria except T. phaeum in the ammonia‐stressed reactor, coincident with the shift to syntrophic acetate oxidation. As the abundance of the bacteria increased, a simultaneous decrease was observed in the abundance of aceticlastic methanogens from the families Methanosaetaceae and Methanosarcinaceae. qPCR analyses of sludge from two additional high ammonia processes, in which methane production from acetate proceeded through syntrophic acetate oxidation (reactor SB) or through aceticlastic degradation (reactor DVX), demonstrated that SAOB were significantly more abundant in the SB reactor than in the DVX reactor.
Creative Thinking for Peace or Blessed are the Peacemakers
Authors: Kässmann Margot
Published: March 2011

Taking as a starting point the debate that began following a televised sermon in which she questioned German military action in Afghanistan, Margot Kässmann reviews the contemporary challenges about war and peace that face society and churches. Drawing on the experience of the ecumenical movement in the 20th century, Kässmann argues for the need for a “just peace” perspective to which religions can contribute by mediating in armed conflicts, engaging in dialogue and promoting trust across national, cultural and religious boundaries. In such a “just peace” perspective, state actors need to invest funds, energy, people and imagination into areas of conflict before the outbreak of violence.
“Peace with the Earth” in the Context of the Decade to Overcome Violence
Authors: Kerber Guillermo
Published: March 2011

Abstract In this article, Guillermo Kerber situates theWorld Council of Churches' Decade to Overcome Violence against the background of debates about war and peace that have taken place within the ecumenical movement since the Second World War. He shows how this initiative has contributed to an understanding of the concept of “just peace” that goes beyond being the opposite of “just war, but rather demands the absence of all forms of structural violence, including gender‐based, cultural and media violence”. Against this background, this article underlines the need for an ecological understanding of “peace with the earth” to be an integral part of such a “just peace”.
Social Ecology: A Hermeneutical Framework for Reading Biblical Texts? A Latin American Perspective
Authors: Sintado Carlos A.
Published: March 2011

Using the concept of “social ecology” developed by Murray Bookchin as a starting point, this article explores the reception of this idea in Latin America before elaborating some key principles derived from this concept for a hermeneutical strategy to approach biblical texts. In particular, the article argues that Bookchin's understanding of the seriousness of the ecological crisis and of its causes, his views on the issues around exploitation, hierarchy and domination, gender and age oppression, and his criticism of the prevailing economic and political dimension could provide a hermeneutical framework that is relevant for an ecologically sound and justice‐centred reading of biblical texts.
Biochemical response to ursodeoxycholic acid predicts long‐term outcome in Japanese patients with primary biliary cirrhosis
Authors: Azemoto Nobuaki , Kumagi Teru , Abe Masanori , Konishi Ichiro , Matsuura Bunzo , Hiasa Yoichi , Onji Morikazu
Published: March 2011

Aim:  There is an ongoing need for predictors of long‐term outcomes for patients with primary biliary cirrhosis (PBC). Biochemical response to ursodeoxycholic acid (UDCA) has been introduced to predict development of symptoms by our group (Ehime criteria) and to predict long‐term outcomes in Western countries (Paris, Barcelona and Rotterdam criteria). The aim of this study was to evaluate whether these criteria are also useful to predict long‐term outcomes in Japanese patients with PBC.

Methods:  A retrospective chart review was conducted for 227 Japanese patients with PBC. Patients taking UDCA with an observation period of more than 6 months were included in the study. Data collection included demographics, biochemical and serological markers, and histological stage. Four different criteria regarding biochemical response to UDCA were compared and evaluated.

Results:  In total, 138 patients met the inclusion criteria and underwent analysis. Using the Ehime criteria, the transplant‐free survival rate was significantly higher in responders than in non‐responders (P = 0.010). The Paris criteria also predicted long‐term outcomes in our population (P = 0.003), whereas the Barcelona and Rotterdam criteria showed no such association (P = 0.282 and P = 0.553, respectively).

Conclusion:  Good biochemical response to UDCA according to the Ehime and Paris criteria is associated with long‐term outcome in Japanese patients with PBC and allows identification of non‐responders who may benefit from further trials. Finally, Ehime criteria should be validated in a different patient cohort.
Alcohol consumption and metabolic syndrome
Authors: Fujita Naoki , Takei Yoshiyuki
Published: March 2011

Drinking excessive amounts of alcohol regularly for years is toxic to almost every tissue of the body. On the other hand, epidemiological and clinical evidence shows that light‐to‐moderate drinking is associated with a reduced risk of coronary heart disease, total and ischemic stroke, and mortality. In the past two decades, metabolic syndrome, the combination of obesity, hypertension, dyslipidemia and hyperglycemia, are all also recognized as major cardiovascular risk factors, has given rise to much clinical and research attention, because of its high prevalence in the world. Therefore, it is of interest to evaluate the overall associations of alcohol consumption with the development of metabolic syndrome. Recently, the protective, detrimental or J‐shaped associations have been reported between alcohol consumption and metabolic syndrome. This controversy may be due to the complex mechanistic relation between alcohol consumption and each component of metabolic syndrome, and almost all studies have various limitations and problem points. Prospective studies are therefore needed to confirm the association between alcohol consumption and prevalence of metabolic syndrome, and to assess the influence of alcohol drinking patterns and other possible factors, such as smoking, physical activity, socioeconomic status, education, occupation, diet and exercise. This article reviews the relation of alcohol consumption and components of metabolic syndrome, and discusses the epidemiological evidence for alcohol's putative vascular protective effects and plausible underlying biological mechanisms.
Hamstring contractures in children with spastic cerebral palsy result from a stiffer extracellular matrix and increased in vivo sarcomere length
Authors: Smith Lucas R. , Lee Ki S. , Ward Samuel R. , Chambers Henry G. , Lieber Richard L.
Published: March 2011

Non‐technical summary  Muscle spasticity, due to an upper motoneuron lesion, often leads to muscle contractures that limit range of motion and cause increased muscle stiffness. However, the elements responsible for this muscle adaption are unknown. Here we show that muscle tissue is stiffer in contracture compared to age‐matched children, implicating the extracellular matrix (ECM). However, titin, the major load‐bearing protein within muscle fibres, is not altered in contracture, and individual fibre stiffness is unaltered. Increased ECM stiffness is even more functionally significant given our finding of long in vivo sarcomeres which leads to much larger in vivo forces in muscle contracture. These results may lead to novel therapeutics for treating spastic muscle contracture.
Knocking down of the KCC2 in rat hippocampal neurons increases intracellular chloride concentration and compromises neuronal survival
Authors: Pellegrino Christophe , Gubkina Olena , Schaefer Michael , Becq Hélène , Ludwig Anastasia , Mukhtarov Marat , Chudotvorova Ilona , Corby Severine , Salyha Yuriy , Salozhin Sergey , Bregestovski Piotr , Medina Igor
Published: March 2011

Non‐technical summary  ‘To be, or not to be’– thousands of neurons are facing this Shakespearean question in the brains of patients suffering from epilepsy or the consequences of a brain traumatism or stroke. The destiny of neurons in damaged brain depends on tiny equilibrium between pro‐survival and pro‐death signalling. Numerous studies have shown that the activity of the neuronal potassium chloride co‐transporter KCC2 strongly decreases during a pathology. However, it remained unclear whether the change of the KCC2 function protects neurons or contributes to neuronal death. Here, using cultures of hippocampal neurons, we show that experimental silencing of endogenous KCC2 using an RNA interference approach or a dominant negative mutant reduces neuronal resistance to toxic insults. In contrast, the artificial gain of KCC2 function in the same neurons protects them from death. This finding highlights KCC2 as a molecule that plays a critical role in the destiny of neurons under toxic conditions and opens new avenues for the development of neuroprotective therapy.
Impaired intestinal afferent nerve satiety signalling and vagal afferent excitability in diet induced obesity in the mouse
Authors: Daly Donna M. , Park Sung Jin , Valinsky William C. , Beyak Michael J.
Published: March 2011

Non‐technical summary  Obesity is known to result from energy intake in excess of expenditure. What is not known is how individuals are able to eat in excess of their energy needs. We show that after chronic consumption of a high fat diet (which causes obesity), intestinal sensory nerves are less responsive to chemicals released from the gut during a meal (cholecystokinin and 5‐hydroxytryptamine) as well as to distension of the gut as might occur during a meal. This appears to be due to the fact that the ability of the nerve cells to be excited is impaired. This suggests that consumption of an unhealthy diet that leads to obesity causes decreased signalling from the intestine, which may lead to increased food intake and contribute to further weight gain, or allow the maintenance of excess weight and obesity.
Functional role of M‐type (KCNQ) K+ channels in adrenergic control of cardiomyocyte contraction rate by sympathetic neurons
Authors: Zaika Oleg , Zhang Jie , Shapiro Mark S.
Published: March 2011

Non‐technical summary  The heart is widely known to be controlled by the sympathetic nervous system, which uses the neurotransmitter noradrenaline (norepinephrine) to increase the rate and force of heart beating. We used a preparation of sympathetic nerve cells and heart cells cultured together that recapitulates this sympathetic control of the heart. Our goal was to probe the role of a particular nerve cell potassium current, called the M‐current, in the control of neurotransmitter release, using the contraction rate of the co‐cultured heart cells as a functional read‐out of noradrenaline release. Using several drugs and receptor agonists, we manipulated the activity of M‐current in the nerve cells, which were stimulated by nicotine, and monitored its effect on heart cell beating. We find that the M‐type potassium current has a robust role in the control of noradrenaline release from the nerve cells, and in the response of the heart cells to increased beating frequency as a result.
Balance of unidirectional monovalent ion fluxes in cells undergoing apoptosis: why does Na+/K+ pump suppression not cause cell swelling?
Authors: Yurinskaya Valentina E. , Rubashkin Andrey A. , Vereninov Alexey A.
Published: March 2011

Non‐technical summary  Apoptosis is a crucial mechanism for tissue maintenance and deregulation of apoptosis may lead to catastrophic consequences in humans (e.g. cancer). The present work is a first attempt to quantitatively characterize rearrangement of the monovalent ion fluxes in cells during apoptosis. An established model of apoptosis induced by staurosporine in lymphoid U937 cells is used to experimentally measure cellular Cl− content and fluxes, K+, Na+ and water content as well as ouabain‐sensitive and ‐resistant Rb+ fluxes. A mathematical model is developed to account for the unidirectional ion fluxes and water balance in a cell as a whole. A decrease in the channel permeability of the plasma membrane for Na+ proved to be crucial for preventing cell swelling due to the decrease in Na+/K+ pump activity in cells undergoing apoptosis whereas opening of the K+ and Cl− channels is not required. Supplemental Table S1 is given for easy calculating flux balance under specified conditions.
A Computational Parametric Analysis of the Vibration of a Three-Spool Aero-Engine Under Multifrequency Unbalance Excitation
Authors: Hai Pham Minh , Bonello Philip
Published: March 2011

The integration of squeeze-film dampers (SFDs) in aero-engine assemblies is a highly cost-effective means of introducing damping in an otherwise lightly damped structure. However, their deployment requires careful unbalance response calculations that take due account of the SFDs’ nonlinearity, particularly when they are unsupported by a centralizing spring. Until recently, such calculations were prohibitive due to the large number of assembly modes that typically need to be considered. This problem has been overcome by the authors through the novel impulsive receptance method (IRM) and the receptance harmonic balance method (RHBM), which efficiently solve the nonlinear problem in the time and frequency domains, respectively. These methods have been illustrated on a realistic twin-spool engine and have been shown to be effective for both single frequency unbalance excitation (unbalance on a single rotor) and multifrequency unbalance (MFU) excitation (unbalance on both rotors). In the present paper, the methods are applied to a realistic three-spool engine and the aims are twofold: (i) to present some preliminary results of a parametric study into a three-spool aero-engine assembly and (ii) to propose a technique that makes use of both IRM and RHBM in producing the speed responses under MFU excitation (from all three rotors) with a realistic speed relation between the rotors. The latter technique is necessary since the speed ratio will vary along a realistic speed characteristic and the authors have previously solved the twin-spool MFU problem under a constant speed ratio condition. The approach used here is to approximate the speed characteristic by one in which the speed ratios are ratios of low integers, enabling the use of RHBM to finish off (to steady-state) time-transient solutions obtained through IRM. The parameter study shows that the application of simple bump-spring supports to selected, otherwise unsupported, SFDs along with slight sealing should have a beneficial effect on the dynamic response of aero-engines with heavy rotors.
Metallurgical Evaluation and Condition Assessment of FSX 414 Nozzle Segments in Gas Turbines by Metallographic Methods
Authors: Shejale Girish M.
Published: March 2011

Gas turbine components such as nozzle segments, buckets, transition pieces, and combustion liners experience damages such as creep, fatigue, high temperature oxidation, and corrosion. The reliability, availability, and efficiency of high temperature gas turbine parts are based on condition assessment and remaining life analysis. These gas turbine components are normally repaired and refurbished after stipulated operating hours. The decision on the extent of repairs is based on various inspection stages. Among various methodologies of condition assessment, metallography followed by microscopic evaluation has gained wide acceptance since it is cost effective, quick, and reliable. Extensive in-house efforts have been put forth in this field in the development of improved techniques of metallography for accurate determination of material degradation and condition assessment. Experimental studies on frame 6, first stage nozzle segment (FSX 414—cobalt based alloy) were conducted to assess the condition of the nozzle segment by using a laboratory electropolishing technique for metallographic preparation. Sections taken from the nozzle segment were electropolished and examined in light optical microscope (LOM) and scanning electron microscope (SEM). It is concluded that the improved electropolishing technique is effective in assessing creep-fatigue, thermal fatigue, and hot corrosion damage. Based on this, the condition of the nozzle segment is assessed. Typical results of frame 6, first stage nozzle segment are presented and discussed.
Effects of Grease Types on Vibration and Acoustic Emission of Defective Linear-Guideway Type Recirculating Ball Bearings
Authors: Ohta Hiroyuki , Hayashi Shinya , Kato Soichiro , Igarashi Yutaka
Published: March 2011

This paper deals with effects of grease types on vibrations and acoustic emissions (AEs) of linear-guideway type recirculating ball bearings with a millimeter-sized artificial defect in the carriage. First, the vibration and AE of one normal bearing without a defect (Type N) and six defective bearings (Types D1–D6) were measured using a linear velocity of 1 m/s. Three types of grease are used for the lubrication of test bearings. The experimental results show that the vibration and AE amplitudes (the pulse amplitudes, the root-mean-square (RMS) values, and component amplitudes in the spectra) of both the normal and defective bearings have a tendency to be reduced when a grease with higher base oil viscosity is used. Under the same type of grease, the RMS values of the vibrations and AE of the defective bearings increase as the defect angle increases. However, the increases of the RMS values due to increased defect angle (the increasing rates of the RMS values) are reduced when a grease with higher base oil viscosity is used. To explain these experimental results, grease impact tests are carried out. The grease impact tests show that a grease with higher base oil viscosity reduces the impact velocity and the maximum impact forces. This implies that a grease with higher base oil viscosity generate greater viscous resistance to balls in the test bearings then reduces the ball impact forces in the ball circulation collisions and ball-defect collisions. Because of the reduction of the ball impact forces, both the vibration and AE amplitudes as well as the increasing rate of the RMS values are reduced.
Model for the Effect of Fiber Bridging on the Fracture Resistance of Reinforced-Carbon-Carbon
Authors: Chan K. S. , Lee Y.-D. , Hudak S. J.
Published: March 2011

A micromechanical methodology has been developed for analyzing fiber bridging and resistance-curve behavior in reinforced-carbon-carbon (RCC) panels with a 3D composite architecture and a SiC surface coating. The methodology involves treating fiber bridging traction on the crack surfaces in terms of a weight function approach and a bridging law that relates the bridging stress to the crack opening displacement. A procedure has been developed to deduce material constants in the bridging law from the linear portion of the K-resistance curve. This approach has been applied to analyzing R-curves of RCC generated using double cantilever beam and single cantilever bend specimens to establish a bridging law for RCC. The bridging law has been implemented into a micromechanical code for computing the fracture response of a bridged crack in a structural analysis. The crack geometries considered in the structural analysis include the penetration of a craze crack in SiC into the RCC as a single-edge crack under bending and the deflection of a craze crack in SiC along the SiC/RCC interface as a T-shaped crack under bending. The proposed methodology has been validated by comparing the computed R-curves against experimental measurements. The analyses revealed substantial variations in the bridging stress (σo ranges from 11 kPa to 986 kPa, where σo is the limiting bridging stress) and the R-curve response for RCC due to the varying number of bridging ligaments in individual specimens. Furthermore, the R-curve response is predicted to depend on crack geometry. Thus, the initiation toughness at the onset of crack growth is recommended as a conservative estimate of the fracture resistance in RCC. If this bounding structural integrity analysis gives unacceptably conservative predictions, it would be possible to employ the current fiber bridging model to take credit for extra fracture resistance in the RCC. However, due to the large scatter of the inferred bridging stress in RCC, such an implementation would need to be probabilistically based.
Understanding Friction Behavior in Automatic Transmission Fluid LVFA Test: A New Positive Curve Parameter to Friction Coefficient Ratio Index Evaluation
Authors: Zhao Hongyuan , Morina Ardian , Neville Anne , Durham John , Vickerman Richard
Published: March 2011

The frictional characteristics of some basic additive systems used in automatic transmission fluids (ATFs) were assessed using a variable speed friction test machine. The test evaluates the coefficient of friction in unidirectional sliding contact over a range of speeds, loads, and temperatures. Tests were performed on a steel-versus-clutch friction material tribocouple, mainly to establish the link between the lubricant/surface interactions and additive system performance. A new parameter that measures the positive μ-v curve slope speed range was applied, together with friction coefficient ratio index, to show the antishudder property. It is suggested that this is a good complimentary method to the friction coefficient ratio index evaluation. Lubricant formulation is important to the overall friction performance. Both friction modifiers and detergents are shown to be important to the ATF antishudder performance. Oil absorption ability of the post-test friction material surface is proposed to be an important parameter to indicate the antishudder durability in the test. The detergent and antiwear agents are also suggested to be responsible for the decreased oil absorption and pore plugging of the friction material surface.
Improvement of the Fatigue Behavior of Stainless Steel Substrates by Low Pressure Fluidized Bed Peening (FBP)
Authors: Barletta M.
Published: March 2011

This study investigates the effectiveness of fluidized bed peening (FBP) to improve the fatigue behavior of axial-symmetric stainless steel substrates. The substrates were rotated at moderate speed inside a fluidized bed of stainless steel media. Their fatigue failure was determined by rotating bending testing procedure. The number of cycles to fracture was plotted versus the maximum amplitude of alternating stress for fluidized bed peened and unpeened substrates. The effect of peening time was also looked into. FBP was found to definitely improve the number of cycles to fracture. Fatigue life was normally increased of four to five times, although improvements up to an order of magnitude were detected. Hardness measurements, profilometry, scanning electron microscopy, and X-ray diffractometry allowed interpreting the improvement of the fatigue behavior of the peened substrates. After FBP, the substrates surface was characterized by a higher hardness, a smoother and less defective morphology, as well as a beneficial compressive residual stress. Therefore, the improvement in surface and microstructural properties of the peened substrates induced a related increase in their fatigue life. Peening time was also found to influence the fatigue behavior of the substrates, although the sharpest variations in the number of cycles to fracture were observed at the beginning of the fluidized bed process. Based on the previous experimental findings, approximate analytical models, very useful for automation and process control, were proposed, thus providing to the practitioners first hints on how to best set FBP process parameters.
Mechanical Behavior of a Rephosphorized Steel for Car Body Applications: Effects of Temperature, Strain Rate, and Pretreatment
Authors: Cao Yu , Ahlström Johan , Karlsson Birger
Published: March 2011

Temperature and strain rate effects on the mechanical behavior of commercial rephosphorized, interstitial free steel have been investigated by uniaxial tensile testing, covering temperatures ranging from −60°C to +100°C and strain rates from 1×10−4 s−1 to 1×102 s−1 encompassing most conditions experienced in automotive crash situations. The effect of prestraining to 3.5% with or without successive annealing at 180°C for 30 min has also been evaluated. These treatments were used to simulate pressing of the plates and the paint-bake cycle in the production of car bodies. Yield and ultimate tensile strengths, ductility including uniform and total elongation and area reduction, thermal softening effect at high strain rate, and strain rate sensitivity of stress were determined and discussed in all cases. It was found that the Voce equation [σ=σs−(σs−σ0)exp(ε/ε0)] can be fitted to the experimental true stress-true plastic strain data with good precision. The parameter values in this equation were evaluated and discussed. Furthermore, temperature and strain rate effects were examined in terms of thermal and athermal components of the flow stresses. Finally, a thermal activation analysis was performed.
Hole-Within-a-Hole Method for Determining Residual Stresses
Authors: Makino A. , Nelson D. V. , Hill M. R.
Published: March 2011

The strain gauge rosette hole drilling method is often used for determining residual stresses versus depth to depths on the order of 0.5–1.5 mm. Frequently, it is of interest to find stress profiles to greater depths. To provide such a capability, a new approach is presented. Residual stresses versus depth are found by drilling a small diameter hole incrementally to a depth of half of its diameter. The profile of stresses versus depth is found from changes in surface displacements associated with the stress relief from introducing the hole, observed by optical means. Next, a larger diameter, square-bottomed hole is milled directly over the small hole to a depth equaling that of the smaller diameter hole. The bottom of the larger hole provides a fresh surface for optical observation and incremental drilling of a new small hole. This procedure is repeated until a desired total depth is reached. A computational approach is described for correcting the stresses found from the small holes to account for the perturbation of stresses by the material removed by the larger diameter hole. Results of applying this method to find stresses versus depth in a plate subject to uniaxial bending stress and a plate with biaxial residual stresses that vary from compression to tension through the thickness are shown.
Transient Thermal Behavior of Preloaded Three-Pad Foil Bearings: Modeling and Experiments
Authors: Lee Donghyun , Kim Daejong , Sadashiva Ramesh P.
Published: March 2011

Oil-free turbomachinery have emerged as one of the core technologies for the future green power generation systems as stand-alone systems or hybridized with high temperature fuel cells or solar systems. Oil-free technology allows compact, clean, and maintenance-free operation, and foil bearings are at the center of the technology. Since their first commercial applications in the air cycle machines and auxiliary power units in 1970s, significant improvement has been made to the computational models for rotordynamic behavior. However, many technical issues still remain unsolved or poorly understood, and one of them is thermal management. This paper presents transient three-dimensional thermohydrodynamic (3D THD) model of radial foil bearings to predict transient thermal behavior of the bearing-rotor system. The transient model involves transient energy equations applied to all the mechanical structures and gas film. The model was verified through extensive experimental measurements of transient thermal behavior of three-pad foil bearing for various cooling air pressures, external loads, and speeds. The predictions showed very good agreements with the experiments, and also the 3D THD model could predict potential thermal instability observed in the experimental measurements.
Numerical Investigation of Natural Convection Loss From Cavity Receivers in Solar Dish Applications
Authors: Paitoonsurikarn S. , Lovegrove K. , Hughes G. , Pye J.
Published: March 2011

In open cavity receivers employed in solar paraboloidal dish applications, natural convection occurs and contributes a significant fraction of energy loss. Its characteristics hence need to be clarified so that it can be effectively minimized in order to improve the system efficiency. The investigation of natural convection loss from cavity receivers was undertaken numerically and was validated using the published experimental results for four different receiver geometries. A good agreement between experimental and numerical results was obtained. Furthermore, the numerical results of all receivers were qualitatively comparable to the predictions by other available correlations hitherto, although it was found that each correlation has a limited range of applicability arising from the particular cavity geometry and experimental conditions used to derive it. To address this shortcoming, a new correlation based on the numerical results for three of the above four receivers has been proposed. The correlation employs a new concept of an ensemble cavity length scale, to take into account the combined effects of cavity geometry and inclination. Despite a wide variety of cavity geometries and operating conditions, the proposed correlation predicts approximately 50% of the data within ±20% and 90% of the data within ±50%. This is better than any of the other correlations published to date. The new correlation is also simpler to use than the most accurate of those previously published.
Evaluation and Validation of Equivalent Circuit Photovoltaic Solar Cell Performance Models
Authors: Boyd Matthew T. , Klein Sanford A. , Reindl Douglas T. , Dougherty Brian P.
Published: March 2011

The “five-parameter model” is a performance model for photovoltaic solar cells that predicts the voltage and current output by representing the cells as an equivalent electrical circuit with radiation and temperature-dependent components. An important feature of the five-parameter model is that its parameters can be determined using data commonly provided by module manufacturers on their published datasheets. This paper documents the predictive capability of the five-parameter model and proposes modifications to improve its performance using approximately 30 days of field-measured meteorological and module data from a wide range of cell technologies, including monocrystalline, polycrystalline, amorphous silicon, and copper indium diselenide (CIS). The standard five-parameter model is capable of predicting the performance of monocrystalline and polycrystalline silicon modules within approximately 6% RMS but is slightly less accurate for a thin-film CIS and an amorphous silicon array. Errors for the amorphous technology are reduced to approximately 5% RMS by using input data obtained after the module underwent an initial degradation in output due to aging. The robustness and possible improvements to the five-parameter model were also evaluated. A sensitivity analysis of the five-parameter model shows that all model inputs that are difficult to determine and not provided by manufacturer datasheets such as the glazing material properties, the semiconductor band gap energy, and the ground reflectance may be represented by approximate values independent of the PV technology. Modifications to the five-parameter model tested during this research did not appreciably improve the overall model performance. Additional dependence introduced by a seven-parameter model had a less than 1% RMS effect on maximum power predictions for the amorphous technology and increased the modeling errors for this array 4% RMS at open-circuit conditions. Adding a current sink to the equivalent circuit to better model recombination currents had little effect on the model behavior.
State Dependent Regenerative Effect in Milling Processes
Authors: Bachrathy Dániel , Stépán Gábor , Turi János
Published: March 2011

The governing equation of milling processes is generalized with the help of accurate chip thickness derivation resulting in a state dependent delay model. This model is valid for large amplitude machine tool vibrations and uses accurate nonlinear screen functions describing the entrance and exit positions of the cutting edges of the milling tool relative to the workpiece. The periodic motions of this nonlinear system are calculated by a shooting method. The stability calculation is based on the linearization around these periodic solutions by means of the semidiscretization method applied for the corresponding time-periodic delay system. Predictor-corrector method is developed to continue the periodic solutions as the bifurcation parameter, that is, the axial immersion is varied. It is observed that the influence of the state dependent delay on linear stability can be significant close to resonance where large amplitude forced vibrations occur. The existence of an unusual fold bifurcation is shown where a kind of hysteresis phenomenon appears between two different stable periodic motions.
Versatile approach to Rb vapor cell construction
Authors: Hulbert John F. , Hurd Katie B. , Carroll Brandon T. , Hawkins Aaron R. , Wu Bin , Schmidt Holger
Published: March 2011

A versatile approach to Rb atomic vapor cell construction is proposed and tested. The construction method employs pinch-off copper cold-welds and epoxy to create hermetic seals between dissimilar geometries and materials. Accelerated testing revealed expected lifetimes of 3 days at 90 °C operation and in excess of 1 yr at 25 °C operation. The reaction of Rb with epoxy was determined to be the largest contributor to failure.
Analysis of organic pollutant degradation in pulsed plasma by coherent anti-Stokes Raman spectroscopy
Authors: Bratescu Maria Antoneta , Hieda Junko , Umemura Tomonari , Saito Nagahiro , Takai Osamu
Published: March 2011

The degradation of p-benzoquinone (p-BQ) in water was investigated by the coherent anti-Stokes Raman spectroscopy (CARS) method, in which the change of the anti-Stokes signal intensity corresponding to the vibrational transitions of the molecule is monitored during and after solution plasma processing (SPP). In the beginning of SPP treatment, the CARS signal intensity of the ring vibrational molecular transitions at 1233 and 1660 cm−1 increases under the influence of the electric field of the plasma, depending on the delay time between the plasma pulse and the laser firing pulse. At the same time, the plasma contributes to the degradation of p-BQ molecules by generating hydrogen and hydroxyl radicals, which decompose p-BQ into different carboxylic acids. After SPP, the CARS signal intensity of the vibrational bands of p-BQ ceased and the degradation of p-BQ was confirmed by UV-visible absorption spectroscopy and liquid chromatography analysis.
In Vivo Systems Analysis Identifies Spatial and Temporal Aspects of the Modulation of TNF-α–Induced Apoptosis and Proliferation by MAPKs
Authors: Lau Ken S. , Juchheim Alwin M. , Cavaliere Kimberly R. , Philips Sarah R. , Lauffenburger Douglas A. , Haigis Kevin M.
Published: March 2011

A systems-level analysis of signaling in the mouse intestine identifies critical mediators of inflammation and regionally specific responses.
The Yin and Yang of Signaling in T
regs
and T
H
17 CellsA report on the Second International Conference on Regulatory T Cells and T
H
17 Cells and Clinical Application in Human Diseases: “China Tregs/Th17 2010 Shanghai Conference,” Shanghai, China, 17 to 20 July 2010.
Authors: Pan Fan , Fan Huimin , Lu Ling , Liu Zhongmin , Jiang Shuiping
Published: March 2011

This meeting in Shanghai focused on the relationship between regulatory and inflammatory T cells.
Getting Rid of Unwanted Neighbors
Authors: Wong Wei
Published: March 2011

JNK signaling promotes the elimination of neoplastic cells in
Drosophila
epithelia.
Unexpected Inhibition
Authors: VanHook Annalisa M.
Published: March 2011

Ras-MAPK signaling modulates innate immunity in the fly.
Off-Target Gene Regulation Mediated by Transcriptional Repressors of Antimicrobial Efflux Pump Genes in Neisseria gonorrhoeae
Authors: Johnson Paul J. T. , Stringer Virginia A. , Shafer William M.
Published: March 2011

DNA-binding proteins that control expression of drug efflux pump genes have been termed “local regulators” as their encoding gene is often located adjacent to the gene(s) that they regulate. However, results from recent studies indicate that they can control genes outside efflux pump-encoding loci, which we term as being “off target.” For example, the MtrR repressor was initially recognized for its ability to repress transcription of the
mtrCDE
-encoded efflux pump operon in the strict human pathogen
Neisseria gonorrhoeae
, but recent results from genetic and microarray studies have shown that it can control expression of nearly 70 genes scattered throughout the chromosome. One of the off-target MtrR-repressed genes is
glnA
, which encodes glutamine synthetase. Herein, we confirm the capacity of MtrR to repress
glnA
expression and provide evidence that such repression is due to its ability to negatively influence the binding of a second DNA-binding protein (FarR), which activates
glnA
. FarR was previously recognized as a transcriptional repressor of the
farAB
-encoded efflux pump operon. Thus, two DNA-binding proteins previously characterized as repressors of genes encoding efflux pumps that contribute to gonococcal resistance to antimicrobials can act in an opposing manner to modulate expression of a gene involved in basic metabolism.
Sequential Population Pharmacokinetic Modeling of Lopinavir and Ritonavir in Healthy Volunteers and Assessment of Different Dosing Strategies
Authors: Dickinson Laura , Boffito Marta , Back David , Else Laura , von Hentig Nils , Davies Geraint , Khoo Saye , Pozniak Anton , Moyle Graeme , Aarons Leon
Published: March 2011

Nonlinear mixed-effects modeling was applied to explore the relationship between lopinavir and ritonavir concentrations over 72 h following drug cessation and also to assess other lopinavir and ritonavir dosing strategies compared to the standard 400-mg–100-mg twice-daily dose. Data from 16 healthy volunteers were included. Possible covariates influencing lopinavir and ritonavir pharmacokinetics were also assessed. Data were modeled first separately and then together by using individually predicted ritonavir pharmacokinetic parameters in the final lopinavir model. The model was evaluated by means of a visual predictive check and external validation. A maximum-effect model in which ritonavir inhibited the elimination of lopinavir best described the relationship between ritonavir concentrations and lopinavir clearance (CL/F). A ritonavir concentration of 0.06 mg/liter was associated with a 50% maximum inhibition of the lopinavir CL/F. The population prediction of the lopinavir CL/Fin the absence of ritonavir was 21.6 liters/h (relative standard error, 14.0%), and the apparent volume of distribution and absorption rate constant were 55.3 liters (relative standard error, 10.2%) and 0.57 h−1(relative standard error, 0.39%), respectively. Overall, 92% and 94% of the observed concentrations were encompassed by the 95% prediction intervals for lopinavir and ritonavir, respectively, which is indicative of an adequate model. Predictions of concentrations from an external data set (HIV infected) (n= 12) satisfied predictive performance criteria. Simulated lopinavir exposures at lopinavir-ritonavir doses of 200 mg-150 mg and 200 mg-50 mg twice daily were 38% and 65% lower, respectively, than that of the standard dose. The model allows a better understanding of the interaction between lopinavir and ritonavir and may allow a better prediction of lopinavir concentrations and assessments of different dosing strategies.
Paradoxical Effect of Caspofungin against Candida Bloodstream Isolates Is Mediated by Multiple Pathways but Eliminated in Human Serum
Authors: Shields Ryan K. , Nguyen M. Hong , Du Chen , Press Ellen , Cheng Shaoji , Clancy Cornelius J.
Published: March 2011

Paradoxical growth of
Candida in vitro
at echinocandin concentrations exceeding the MIC is well described, but the clinical relevance is unknown. We assessed echinocandin paradoxical effects against
Candida
bloodstream isolates (BSI) in the presence or absence of human serum and investigated regulatory mechanisms. As determined by broth microdilution, a paradoxical effect was evident for 60% (18/30), 23% (7/30), and 13% (4/30) of
Candida albicans
BSI exposed to caspofungin, anidulafungin, and micafungin, respectively, at achievable human serum concentrations (≤8 μg/ml). A paradoxical effect was not evident among 34
C. glabrata
BSI and was observed only for caspofungin against
C. parapsilosis
(4%, 1/23). As determined in time-kill studies, a caspofungin paradoxical effect was demonstrated by
C. albicans
(2/3),
C. glabrata
(1/3), and
C. parapsilosis
(1/3), including BSI that were determined to be negative by microdilution. In 50% human serum, a paradoxical effect was eliminated at caspofungin concentrations up to 64 μg/ml for 100% (8/8) of the
C. albicans
BSI. A caspofungin paradoxical effect was also eliminated by chitin synthase inhibitor nikkomycin Z and at achievable concentrations of calcineurin pathway inhibitors, tacrolimus and cyclosporine. Moreover, these agents were synergistic with caspofungin against 100, 100, and 88% (7/8) of
C. albicans
, respectively, and exerted their own paradoxical effects. Finally, paradoxical growth was eliminated in
C. albicans irs4
- and
inp51
-null mutants, which lack phosphatidylinositol-(4,5)-bisphosphate 5′-phosphatase. Our findings suggest that the paradoxical effect is unlikely to be important
in vivo
but remains an important tool to study cell wall stress responses. We implicate the Irs4-Inp51 phosphatidylinositol-(4,5)-bisphosphate 5′-phosphatase as a novel regulator of paradoxical growth.
Decrease in Penicillin Susceptibility Due to Heat Shock Protein ClpL in Streptococcus pneumoniae
Authors: Tran Thao Dang-Hien , Kwon Hyog-Young , Kim Eun-Hye , Kim Ki-Woo , Briles David E. , Pyo Suhkneung , Rhee Dong-Kwon
Published: March 2011

Antibiotic resistance and tolerance are increasing threats to global health as antibiotic-resistant bacteria can cause severe morbidity and mortality and can increase treatment cost 10-fold. Although several genes contributing to antibiotic tolerance among pneumococci have been identified, we report here that ClpL, a major heat shock protein, could modulate cell wall biosynthetic enzymes and lead to decreased penicillin susceptibility. On capsular type 1, 2, and 19 genetic backgrounds, mutants lacking ClpL were more susceptible to penicillin and had thinner cell walls than the parental strains, whereas a ClpL-overexpressing strain showed a higher resistance to penicillin and a thicker cell wall. Although exposure of
Streptococcus pneumoniae
D39 to penicillin inhibited expression of the major cell wall synthesis gene
pbp2x
, heat shock induced a ClpL-dependent increase in the mRNA levels and protein synthesized by
pbp2x
. Inducible ClpL expression correlated with PBP2x expression and penicillin susceptibility. Fractionation and electron micrograph data revealed that ClpL induced by heat shock is localized at the cell wall, and the Δ
clpL
showed significantly reduced net translocation of PBP2x into the cell wall. Moreover, coimmunoprecipitation with either ClpL or PBP2x antibody followed by reprobing with ClpL or PBP2x antibody showed an interaction between ClpL and PBP2x after heat stress. This interaction was confirmed by His tag pulldown assay with either ClpLHis
6
or PBP2xHis
6
. Thus, ClpL stabilized
pbp2x
expression, interacted with PBP2x, and facilitated translocation of PBP2x, a key protein of cell wall synthesis process, contributing to the decrease of antibiotic susceptibility in
S. pneumoniae
.
Double-Carbapenem Therapy for Carbapenemase-Producing Klebsiella pneumoniae
Authors: Bulik Catharine C. , Nicolau David P.
Published: March 2011

The limited treatment options available for carbapenemase-producing
Klebsiella pneumoniae
(KPC) have made it a formidable pathogen. Previously we have shown the enhanced activity of pharmacodynamically optimized doripenem against KPC. Capitalizing on KPC's increased affinity for ertapenem, we evaluated the efficacy of a combination of ertapenem and doripenem in both an
in vitro
chemostat and an
in vivo
murine thigh infection model. Overall, the combination of doripenem plus ertapenem demonstrated enhanced efficacy over either agent alone.
Novel Types of Staphylococcal Cassette Chromosome
mec
Elements Identified in Clonal Complex 398 Methicillin-Resistant Staphylococcus aureus Strains
Authors: Li Shanshuang , Skov Robert Leo , Han Xiao , Larsen Anders Rhod , Larsen Jesper , Sørum Marit , Wulf Mireille , Voss Andreas , Hiramatsu Keiichi , Ito Teruyo
Published: March 2011

The structures of staphylococcal cassette chromosome
mec
(SCC
mec
) elements carried by 31 clonal complex 398 (CC398) methicillin-resistant
Staphylococcus aureus
(MRSA) strains isolated from the participants at a conference were analyzed. The SCC
mec
s were classified into novel types, namely, IX, X, V(5C2&5) subtype c, and IVa. Type V(5C2&5) subtype c, IX, and X SCC
mec
s carried genes conferring resistance to metals. The structures of SCC
mec
s from CC398 strains were distinct from those normally found in humans, adding to the evidence that humans are not the original host for CC398.
Antimicrobial Peptoids Are Effective against Pseudomonas aeruginosa Biofilms
Authors: Kapoor Rinki , Wadman Mayken W. , Dohm Michelle T. , Czyzewski Ann M. , Spormann Alfred M. , Barron Annelise E.
Published: March 2011

The resistance of biofilms to conventional antibiotics complicates the treatment of chronic cystic fibrosis (CF). We investigated the effects of peptoids, peptides, and conventional antibiotics on the biomass and cell viability within
Pseudomonas aeruginosa
biofilms. At their MICs, peptoids 1 and 1-C13
4mer
caused maximum reductions in biomass and cell viability, respectively. These results suggest that peptoids of this class could be worth exploring for the treatment of pulmonary infections occurring in CF patients.
In Vitro Activities of Anidulafungin and Other Antifungal Agents against Biofilms Formed by Clinical Isolates of Different Candida and Aspergillus Species
Authors: Fiori Barbara , Posteraro Brunella , Torelli Riccardo , Tumbarello Mario , Perlin David S. , Fadda Giovanni , Sanguinetti Maurizio
Published: March 2011

We tested the activities of anidulafungin and other antifungal agents against clinical isolates of different fungal species. For
Candida
species, high sessile MIC
90
s (SMIC
90
s) were obtained for fluconazole, voriconazole, and amphotericin B, whereas the anidulafungin SMIC
90
s were very low, as were those for caspofungin. Comparatively, for
Aspergillus
species, higher SMIC
90
values were obtained not only for amphotericin B and voriconazole but also for the echinocandins.