bluuebunny/crossref_metadata_2025 huggingface dataset:
40Ar/39Ar Dating of Xuebaoding Granite in the Songpan‐Garzê Orogenic Belt, Southwest China, and its Geological Significance
Authors: LIU Yan , DENG Jun , ZHANG Guibin , SHI Guanghai , YANG Liqiang , WANG Qingfei
Published: August 2010

Thus far, our understanding of the emplacement of Xuebaoding granite and the occurrence and evolution of the Songpan‐Garzê Orogenic Belt has been complicated by differing age spectra results. Therefore, in this study, the 40Ar/39Ar and sensitive high resolution ion micro‐probe (SHRIMP) U‐Pb dating methods were both used and the results compared, particularly with respect to dating data for Pankou and Pukouling granites from Xuebaoding, to establish ages that are close to the real emplacements. The results of SHRIMP U‐Pb dating for zircon showed a high amount of U, but a very low value for Th/U. The high U amount, coupled with characteristics of inclusions in zircons, indicates that Xuebaoding granites are not suitable for U‐Pb dating. Therefore, muscovite in the same granite samples was selected for 40Ar/39Ar dating. The 40Ar/39Ar age spectrum obtained on bulk muscovite from Pukouling granite in the Xuebaoding, gave a plateau age of 200.1±1.2 Ma and an inverse isochron age of 200.6±1.2 Ma. The 40Ar/39Ar age spectrum obtained on bulk muscovite from Pankou granite in the Xuebaoding gave another plateau age of 193.4± 1.1 Ma and an inverse isochron age of 193.7±1.1 Ma. The 40Ar/39Ar intercept of 277.0±23.4 (2σ) was very close to the air ratio, indicating that no apparent excess argon contamination was present These age dating spectra indicate that both granites were emplaced at 200.6±1.3 Ma and 193.7±1.1 Ma, respectively. Through comparison of both dating methods and their results, we can conclude that it is feasible that the muscovite in the granite bearing high U could be used for 40Ar/39Ar dating without extra Ar. Based on this evidence, as well as the geological characteristics of the Xuebaoding W‐Sn‐Be deposit and petrology of granites, it can be concluded that the material origin of the Xuebaoding W‐Sn‐Be deposit might partially originate from the Xuebaoding granite group emplacement at about 200 Ma. Moreover, compared with other granites and deposits distributed in various positions in the Songpan‐Garzê Orogenic Belt, the Xuebaoding emplacement ages further show that the main rare metal deposits and granites in peripheral regions occurred earlier than those in the inner Songpan‐Garzê. Therefore, 40Ar/39Ar dating of Xuebaoding granite will lay a solid foundation for studying the occurrence and evolution of granite and rare earth element deposits in the Songpan‐Garzê Orogenic Belt.
Hydrocarbon Generation Evolution of Permo‐Carboniferous Rocks of the Bohai Bay Basin in China
Authors: ZHU Yanming , QIN Yong , SANG Shuxun , CHEN Shangbin , LAN Xiaodong
Published: August 2010

The Bohai Bay Basin is a Mesozoic subsidence and Cenozoic rift basin in the North China Craton. Since the deposition of the Permo‐Carboniferous hydrocarbon source rock, the basin has undergone many tectonic events. The source rocks have undergone non‐uniform uplift, twisting, deep burying, and magmatism and that led to an interrupted or stepwise during the evolution of hydrocarbon source rocks. We have investigated the Permo‐Carboniferous hydrocarbon source rocks history of burying, heating, and hydrocarbon generation, not only on the basis of tectonic disturbance and deeply buried but also with new studies on apatite fission track analysis, fluid inclusion measurements, and the application of the numerical simulation of EASY %Ro. The heating temperature of the source rocks continued to rise from the Indosinian to Himalayan stage and reached a maximum at the Late Himalayan. This led to the stepwise increases during organic maturation and multiple stages of hydrocarbon generation. The study delineated the tectonic stages, the intensity of hydrocarbon generation and spatial and temporal distribution of hydrocarbon generations. The hydrocarbon generation occurred during the Indosinian, Yanshanian, and particularly Late Himalayan. The hydrocarbon generation during the late Himalayan stage is the most important one for the Permo‐Carboniferous source rocks of the Bohai Bay Basin in China.
Normal Faulting Type Earthquake Activities in the Tibetan Plateau and Its Tectonic Implication
Authors: XU Jiren , ZHAO Zhixin
Published: August 2010

This paper analyzes various earthquake fault types, mechanism solutions, stress field as well as other geophysical data to study the crust movement in the Tibetan plateau and its tectonic implications. The results show that a lot of normal faulting type earthquakes concentrate in the central Tibetan plateau. Many of them are nearly perfect normal fault events. The strikes of the fault planes of the normal faulting earthquakes are almost in the N‐S direction based on the analyses of the equal area projection diagrams of fault plane solutions. It implies that the dislocation slip vectors of the normal faulting type events have quite great components in the E‐W direction. The extension is probably an eastward extensional motion, mainly a tectonic active regime in the altitudes of the plateau. The tensional stress in the E‐W or WNW‐ESE direction predominates the earthquake occurrence in the normal event region of the central plateau. A number of thrust fault and strike‐slip fault type earthquakes with strong compressive stress nearly in the NNE‐SSW direction occurred on the edges of the plateau. The eastward extensional motion in the Tibetan plateau is attributable to the eastward movement of materials in the upper mantle based onseismo‐tomographic results. The eastward extensional motion in the Tibetan plateau may be related to the eastward extrusion of hotter mantle materials beneath the east boundary of the plateau. The northward motion of the Tibetan plateau shortened in the N‐S direction probably encounters strong obstructions at the western and northern margins. Extensional motions from the relaxation of the topography and/or gravitational collapse in the altitudes of the plateau occur hardly in the N‐S direction. The obstruction for the plateau to move eastward is rather weak
A New Boreopterid Pterodactyloid Pterosaur from the Early Cretaceous Yixian Formation of Liaoning Province, Northeastern China
Authors: LÜ Junchang
Published: August 2010

A new boreopterid pterosaur: Zhenyuanopterus longirostris gen. et sp. nov. from the Yixian Formation of western Liaoning is erected, based on the complete skeleton with a skull and lower jaws preserved. It is characterized by: a large boreopterid pterosaur with a high number of teeth, where the anterior teeth are much larger than posterior ones; the length of the dorsal + sacral vertebrae is nearly half the length of the skull; ratio of the length of the humerus to metacarpal IV is approximately 91% and the, humerus, femur and third wing phalanx are all equal in length and the feet are specially small. It represents the largest boroepterid pterosaur discovered from western Liaoning and its surrounding areas so far
Musik im Deutschunterricht: Der gezielte Einsatz1
Authors: Esa Mohamed
Published: August 2010

Nach allgemeinen Betrachtungen zur Popularität deutschsprachiger Musik, zur Rolle und zu den Funktionen von Musik und zum Stand der Forschung wird in diesem Artikel ein Didaktisierungsmodell zum effektiven und gezielten Einsatz von Musik im Deutschunterricht beschrieben und anhand des Liedes “Jetzt ist Sommer” von der derzeit berühmtesten deutschen a‐cappella Gruppe “Wise Guys” aus Köln schrittweise veranschaulicht.
Exploring Otherness through Pepe Danquart's Schwarzfahrer: A Lesson in Cultural Sensitivity
Authors: Libbon Stephanie E.
Published: August 2010

Culture has not always played a major role in foreign language instruction. Indeed, it was only in the 1980s that educators began giving serious thought to employing culture for language learning purposes. Exploring issues of otherness in Pepe Danquart's film Schwarzfahrer, this article illustrates how one can address the more controversial aspects of a culture in a manner that promotes cultural sensitivity at the same time that it prompts students to gain a greater knowledge of other cultures and acquire more insight into their own cultures.
Student Expectations, Motivations, Target Language Use, and Perceived Learning Progress in a Summer Study Abroad Program in Germany
Authors: Badstübner Tina , Ecke Peter
Published: August 2010

This study investigated students' motives for participating in a short‐term study abroad program in Germany, their expectations about learning progress at the beginning of the program, and their perceived progress in various language skills at the end of the program. Findings indicated that students' expectations were higher than their perceived progress in all skills with the exception of cultural learning. Correlations were found between reported frequency of listening in the L2 and gains in L2 listening proficiency, and between the goals “to be in contact with Germans” and “cultural enrichment” with expected gains in speaking and listening skills.
Using Computer‐Mediated Communication (CMC) in Language Teaching
Authors: Goertler Senta
Published: August 2010

This article discusses how new and familiar computer technology tools can be used in a communicative language classroom. It begins by outlining the benefits and challenges of using such technology for language teaching in general, and it describes some sample activities that the author has used. Readers are shown how to implement various computer tools in their own classrooms in order to create a Computer‐Mediated Communication environment in a communicative language classroom.
Hey, you! The Germans! Using Literary Pragmatics to Teach Language as Culture
Authors: Warner Chantelle
Published: August 2010

In this paper the author outlines a sample lesson that has been developed for second‐ or third‐year German students using the short satirical vignette “Hurra, ich lebe in Deutschland” from the Turkish‐German author Şinasi Dikmen's book of the same name. The lesson draws heavily from literary pragmatics, an area of applied linguistics which studies the relationships between literary language use and its users, and which can promote the awareness of language as culture needed in the more advanced levels of language study.
A Depository Institution's Optimal Currency Supply Network Under the Fed's New Guidelines: Operating Policies, Logistics, and Impact
Authors: Mehrotra Mili , Dawande Milind , Sriskandarajah Chelliah
Published: August 2010

The overuse of its currency processing operations by depository institutions (DIs) has motivated the Federal Reserve (Fed) to propose new currency recirculation guidelines. The Fed believes that DIs should play a more active role in recirculating fit (i.e., usable) currency so that the societal cost of providing currency to the public is minimized. The Fed characterizes the overuse by the extent of cross shipping, a practice in which the same DI deposits and withdraws currency of the same denomination within five business days in the same geographic region. The Fed's proposal encourages DIs to fit sort and reuse deposited currency through two components: a custodial inventory program and a recirculation fee that would be charged on withdrawals of cross‐shipped currency. Given the geographical network of the various branches of a DI, the extent of its participation in the proposed programs depends on a variety of factors: the nature of demand and supply of currency, number and locations of the processing centers, and the resulting fit‐sorting, holding, and transportation costs. The interrelated nature of these decisions motivates the need for an integrated model that captures the flow of currency in the entire network of the DI. Based on our work with Brink's Inc., a leading secure‐logistics provider, we develop a mixed‐integer linear programming (MILP) model to provide managers of DIs with a decision‐making tool under the Fed's new guidelines. Broadly, we analyze the following questions: (i) Over all typical practical realizations of the demand for currency that a DI may face, and over all reasonable cost implications, is there a menu of “good” operating policies? (ii) What is the monetary impact of fit‐sorting and custodial inventories on a DI? and (iii) To what extent will the Fed's new guidelines address its main goal, namely, a reduction in the practice of cross shipping by encouraging DIs to recirculate currency?
Fatigue Crack Growth Model for Part-Through Flaws in Plates and Pipes
Authors: Nair P. K.
Published: August 2010

A fatigue crack growth model is developed to evaluate the behavior of planar elliptic flaws in structural components under cyclic loadings. The model is applied to plates with cyclic tensile load and nuclear piping under cyclic pressure loading. It is found that small flaws in plates tend to grow to a fixed aspect ratio, b/a≃0.9 (b is the through thickness direction). The trend checks well with available experimental data. For an axial part-through flaw in piping there is no fixed aspect ratio for growth. However, the flaws in piping are found to grow to a definite axial length. An evaluation is made of the applicability of the model to nuclear primary piping.
The Strain-Rate and Temperature Dependence of 18Ni(350) Maraging Steel Tensile Properties
Authors: Rack H. J. , Beitscher S. , Kalish David
Published: August 2010

The influence of microstructure, strain rate, and test temperature on the tensile properties of 18Ni(350) maraging steel was examined. The strain-rate and temperature dependence of the yield strength is less than that observed in low-strength carbon steels. The results suggest that the thermally activated flow process involves both the by-passing of a linear barrier, i.e., the disruption associated with a dislocation core, and the by-passing of a localized obstacle, the latter being specific to the microstructure being examined. The tensile ductility of aged 18Ni(350) maraging steel also undergoes a ductile-brittle transition. The extent of this ductility loss depends upon the matrix solute content and the presence of either reverted austenite or a highly dislocated substructure.
Fatigue Crack Growth Behavior of Four Structural Alloys in High Temperature High Purity Oxygenated Water
Authors: Hale D. A. , Jewett C. W. , Kass J. N.
Published: August 2010

The fatigue crack growth behavior of four structural alloys was studied and the effects of high temperature (288°C), high purity oxygenated water, cycle frequency, and mean stress were evaluated. The results for carbon and low alloy steel show that while crack growth rates are affected by the water environment, modified ASME code procedures result in conservative predictions of growth. Often, higher crack growth rates are found for shallow cracks than for deep cracks. For stainless steels and Inconel the measured growth rates in water were similar to data obtained in air over the range of cycle frequencies studied.
Fatigue Crack Growth Behavior of Stainless Steel Type 316 Plate and 16-8-2 Weldments in Air and High-Carbon Liquid Sodium
Authors: Yuen J. L. , Copeland J. F.
Published: August 2010

The fatigue crack growth rates of Type 316 stainless steel and 16-3-2 gas tungsten are welds were measured in air and high-carbon liquid sodium at 510°C (950°F) for secondary sodium loop Liquid Metal Fast Breeder Reactor applications. Loading variables such as low frequency, load ratio, and hold time at peak load were studied, Supporting studies show that carburization of crack faces occurs prior to any crack tip carburization for the crack sizes and load frequencies of this study. Thus, a carburization effect on da/dN is not shown for relatively short-term tests. Low stress intensity, ultra-tow frequency tests to simulate service would be required to show this effect. The crack growth rate curve for 16-8-2 welds was below Type 316 base metal curves for both air and high-carbon sodium at 510°C (950°F). Crack growth rate curves for Type 316 and 16-8-2 welds in high-carbon sodium were below the corresponding curves for air.
The Effect of Loading Rate and Temperature on the Initiation of Fracture in a Mild, Rate-Sensitive Steel
Authors: Costin L. S. , Duffy J.
Published: August 2010

An experimental study is presented of the effect of loading rate and temperature on the fracture initiation toughness of a rate-sensitive steel. Dynamic and static fracture tests were performed on specimens of a 1018 cold-rolled steel at selected temperatures over the range −157°C to 107°C; the dynamic tests being conducted with a Kolsky (split-Hopkinson) bar adapted to tensile fracture. The results are used to assess the influence of local plastic deformation on the fracture process. In addition, microstructural models of both cleavage and ductile fracture initiation mechanisms are presented and the local fracture criteria which result from these models are discussed. It is shown finally, that the macroscopic fracture behavior of 1018 cold-rolled steel as predicted from these local criteria is consistent with experimental results.
An Engineering Approach for Cumulative Damage in Metals Under Creep Loading
Authors: Bui-Quoc T.
Published: August 2010

A concept of cumulative damage is developed for an evaluation of the damage incurred under creep loading at high temperature. The damage is essentially stress-dependent and is a non-linear function of the exposure time. The development results in equations which permit the determination of the creep-rupture curve under loading with constant stress as well as the evaluation of the remaining life under loading with several stress levels. The order effect of creep loading is taken into consideration. The theoretical sum of time-ratios is greater than unity for two decreasing stresses; the reverse is obtained for two increasing levels. This trend is in agreement with observations obtained in cumulative creep damage tests. The correlation between the proposed relations and some available experimental data is discussed.
Techniques Developed for Elevated Temperature Fracture Toughness Testing of Irradiated Materials in Thin Sections
Authors: Huang F. H. , Wire G. L.
Published: August 2010

Large changes in strength and ductility of metals after irradiation are known to occur. The fracture toughness of irradiated metals, which is related to the combined strength and ductility of a material, may be significantly reduced and the potential for unstable crack extension increased. For relatively thin materials which retain substantial ductility, even after irradiation, the fracture behavior cannot be analyzed by linear elastic fracture mechanics techniques. Instead, the multispecimen R-curve method and J-integral analysis were used to develop an experimental approach to evaluate the fracture toughness of thin breeder reactor materials irradiated at elevated temperatures. Alloy A-286 was chosen for this work because the alloy exhibits elastic/plastic behavior and the fracture toughness data of thicker (12 mm) specimens were available for comparison. Technical problems associated with specimen buckling and remote handling were treated in this work. The results are discussed in terms of thickness criterion for plane strain.
Capitalizing on Heterogeneity and Anisotropy to Design Desirable Hardware That is Difficult to Reverse Engineer
Authors: Harston Stephen P. , Mattson Christopher A. , Adams Brent L.
Published: August 2010

This paper presents a method for treating material microstructure (crystallographic grain size, orientation, and distribution) as design variables that can be manipulated—for common or exotic materials—to identify the unusual material properties and to design devices that are difficult to reverse engineer. A practical approach, carefully tied to proven manufacturing strategies, is used to tailor the material microstructures by strategically orienting and laminating thin anisotropic metallic sheets. The approach, coupled with numerical optimization, manipulates the material microstructures to obtain the desired material properties at designer-specified locations (heterogeneously) or across the entire part (homogeneously). A comparative study is provided, which examines various microstructures for a simple fixed geometry. These cases show how the proposed approach can provide hardware with enhanced mechanical performance in a way that is disguised within the microscopic features of the material microstructure.
Design of Single-Input-Single-Output Compliant Mechanisms for Practical Applications Using Selection Maps
Authors: Hegde Sudarshan , Ananthasuresh G. K.
Published: August 2010

We present an interactive map-based technique for designing single-input-single-output compliant mechanisms that meet the requirements of practical applications. Our map juxtaposes user-specifications with the attributes of real compliant mechanisms stored in a database so that not only the practical feasibility of the specifications can be discerned quickly but also modifications can be done interactively to the existing compliant mechanisms. The practical utility of the method presented here exceeds that of shape and size optimizations because it accounts for manufacturing considerations, stress limits, and material selection. The premise for the method is the spring-leverage (SL) model, which characterizes the kinematic and elastostatic behavior of compliant mechanisms with only three SL constants. The user-specifications are met interactively using the beam-based 2D models of compliant mechanisms by changing their attributes such as: (i) overall size in two planar orthogonal directions, separately and together, (ii) uniform resizing of the in-plane widths of all the beam elements, (iii) uniform resizing of the out-of-plane thicknesses of the beam elements, and (iv) the material. We present a design software program with a graphical user interface for interactive design. A case-study that describes the design procedure in detail is also presented while additional case-studies are posted on a website.
Simulation of the Inferior Mirage
Authors: Branca Mario
Published: August 2010

A mirage can occur when a continuous variation in the refractive index of the air causes light rays to follow a curved path. As a result, the image we see is displaced from the location of the object.1 If the image appears higher in the air than the object, it is called a “superior” mirage, while if it appears lower it is called an “inferior” mirage.2 The most common example of an inferior mirage is when, on a hot day, a stretch of dry road off in the distance appears to be wet (see Fig. 1). Many lab activities have been described that simulate the formation of superior mirages. In these demonstrations light beams curve downward as they pass through a nonuni-form fluid.3–6 Much less common are laboratory demonstrations of upward-curving light rays of the kind responsible for inferior mirages. This paper describes a simple version of such a demonstration.
Calibration of a Horizontal Sundial
Authors: Rovšek Barbara
Published: August 2010

This paper describes how a horizontal sundial can be calibrated in a classroom without using the nontrivial equations of projective geometry. If one understands how a simple equatorial sundial works, one will also understand the procedure of calibrating a horizontal (or “garden,” as it is also called) sundial.
Demonstrating the sign of a static charge using an inexpensive oscilloscope
Authors: Mitschele Jonathan
Published: August 2010

If you have an inexpensive oscilloscope, such as the Hameg HM 203–4 and Hitachi V-222 oscilloscopes I happen to have in my lab (expensive models are well-shielded from external fields and will not work), you can use them for a vivid determination of the sign of the static charge on an object. To do this, turn the instrument on and adjust the settings so that the beam is not moving, is near the center of the CRT screen, and is quite dim. With a means of putting a static charge on an object—an electrophorus, silk and a glass rod, fur and amber, a comb and your hair (I should note that it is a law of nature that combs become negatively charged when run through dry hair), etc.— have your students gather around the front of the oscilloscope so that each student can see the point of light on the screen (for large classes, a videocam can be used to display what happens on the CRT screen), then darken the room enough that the beam can be seen easily.
Cosmological Constraints from Strong Gravitational Lensing in Clusters of Galaxies
Authors: Jullo Eric , Natarajan Priyamvada , Kneib Jean-Paul , D’Aloisio Anson , Limousin Marceau , Richard Johan , Schimd Carlo
Published: August 2010

Through a Lens Darkly

According to recent measurements, 72% of the energy content in the universe is in the form of dark energy, a gravitationally repulsive constituent that is powering the accelerating expansion of the universe but whose nature is unknown. Now,

Jullo
et al.

(p.
924
) show how observations of systems of multiple images produced by the strong gravitational lensing effect of a single mass distribution can be used to constrain the properties of dark energy. Applied to the cluster Abel 1689—a galaxy cluster that is known for its lensing properties—and combined with the results of other techniques, this method brings down the overall error in the equation of state parameter of dark energy by 30%.
Cell Lineage Reconstruction of Early Zebrafish Embryos Using Label-Free Nonlinear Microscopy
Authors: Olivier Nicolas , Luengo-Oroz Miguel A. , Duloquin Louise , Faure Emmanuel , Savy Thierry , Veilleux Israël , Solinas Xavier , Débarre Delphine , Bourgine Paul , Santos Andrés , Peyriéras Nadine , Beaurepaire Emmanuel
Published: August 2010

Zebrafish Development in 3D

Vertebrate development has classically been characterized qualitatively, but—by combining expertise in physics, mathematics, and biology—

Olivier
et al.

(p.
967
) used label-free conformal nonlinear time-lapse microscopy and image analysis to calculate the spatiotemporal cell lineage of zebrafish embryos throughout their first 10 division cycles. The work reconstructs complete lineage trees, annotated with cell-shape measurements, and allows for visualization with interactive tools.
Dual Jets from Binary Black Holes
Authors: Palenzuela Carlos , Lehner Luis , Liebling Steven L.
Published: August 2010

When Black Holes Collide

When galaxies merge, their central black holes interact, initially coming together in a binary system and eventually coalescing into one single black hole. The dynamics of orbiting binary black holes in vacuum is well understood; however, when black holes merge, their accretion disks are expected to combine into a circumbinary disk anchoring a magnetic field. Numerical simulations from

Palenzuela
et al.

(p.
927
; see the Perspective by

Yunes

) now show that when this surrounding environment is taken into account, the black holes effectively stir the plasma that surrounds them, generating collimated beams of electromagnetic radiation that then transition to a single jet as the black holes merge due to the emission of gravitational waves.
Ceria Maintains Smaller Metal Catalyst Particles by Strong Metal-Support Bonding
Authors: Farmer Jason A. , Campbell Charles T.
Published: August 2010

Keeping Nanoparticles Small

Heterogeneous catalysts that consist of small metal nanoparticles absorbed on oxide supports can deactivate over time through a process called sintering. Elevated temperatures increase the rate of diffusion of metal atoms over the support, and larger, less reactive particles grow at the expense of smaller ones. Some supports that contain reducible metals, such as cerium oxide, tend to resist sintering better than oxides such as alumina.
Farmer and Campbell
(p.
933
) present an analysis of previous calorimetry data for silver nanoparticles on magnesium oxides and cerium oxide surfaces and show that nanoparticles smaller than 1000 atoms are bound much more strongly to reduced cerium oxide. The energetic driving force for creating larger particles is quite low on these surfaces and increases the lifetime of smaller particles.
A Glutamate Pathway to Faster-Acting Antidepressants?
Authors: Cryan John F. , O'Leary Olivia F.
Published: August 2010

Activation of mTOR, a ubiquitous protein, in the prefrontal cortex could be a key goal of new drugs.
Nurturing Young Scientists
Authors: Gentile James , Boehlert Sherwood
Published: August 2010

The United States National Academies has convened a blue-ribbon committee to recommend ways to keep research universities healthy.
*
It will be important for this panel, and for universities, to recognize the value of early career scientists—the transformative discoveries they will make and the students they will influence—as key to America's future. The good news is that federal and private funding for breakthrough research and innovative approaches in science education are growing for early career researchers. Now, universities must step up to the plate and create frameworks in which interdisciplinary research and synergistic teaching can thrive. Achieving these goals will require a fundamental cultural change.
TPL-2–Mediated Activation of MAPK Downstream of TLR4 Signaling Is Coupled to Arginine Availability
Authors: Mieulet Virginie , Yan Lijun , Choisy Caroline , Sully Katherine , Procter Julia , Kouroumalis Andreas , Krywawych Steve , Pende Mario , Ley Steven C. , Moinard Christophe , Lamb Richard F.
Published: August 2010

Arginine is an essential nutrient that enables mice to produce proinflammatory cytokines.
Riboswitch Revealed
Authors: Riddihough Guy
Published: August 2010

A metabolite-sensing riboswitch regulates the splicing of a “selfish” group I self-splicing ribozyme.
Lots of LATs
Authors: Ray L. Bryan
Published: August 2010

Immunoglobulin receptors and T cell receptors use similar components, but with critical differences in coupling to intracellular signaling.
Synergy Testing by Etest, Microdilution Checkerboard, and Time-Kill Methods for Pan-Drug-Resistant
Acinetobacter baumannii
Authors: Sopirala Madhuri M. , Mangino Julie E. , Gebreyes Wondwossen A. , Biller Beth , Bannerman Tammy , Balada-Llasat Joan-Miquel , Pancholi Preeti
Published: August 2010

Pan-drug-resistant (PDR)
Acinetobacter baumannii
is an important nosocomial pathogen that poses therapeutic challenges. Tigecycline alone or in combination with agents such as colestimethate, imipenem, and/or amikacin is being used clinically to treat PDR
A. baumannii
infections. The purpose of this study was to compare
in vitro
susceptibility testing by epsilometric (Etest) methods and the checkerboard (CB) method with testing by time-kill analysis. PDR
A. baumannii
clinical strains representing eight unique pulsed-field gel electrophoresis clones selected from a total of 32 isolates were tested
in vitro
with tigecycline, colestimethate, imipenem, and amikacin in single- and two-drug combinations by using two different methods of Etest (with a fixed ratio method [method 1] and with the incorporation of the active drug in medium [method 2]) and by using CB. The three-drug combination of imipenem, tigecycline, and amikacin was also tested by CB. These results were compared to time-kill results. Synergy was consistently detected with the imipenem plus colestimethate and tigecycline plus imipenem combinations. The Etest method with active drug incorporated into the agar allowed us to detect synergy even in the presence of the active drug and was more comparable to CB and time-kill tests. Synergy was detected with the three-drug combination of imipenem, tigecycline, and amikacin by both CB and time-kill methods among several tested clones. These findings indicate the utility of synergy testing to predict activity of specific antibiotic combinations against PDR
A. baumannii
.
Low Frequency of Intermittent HIV-1 Semen Excretion in Patients Treated with Darunavir-Ritonavir at 600/100 Milligrams Twice a Day plus Two Nucleoside Reverse Transcriptase Inhibitors or Monotherapy
Authors: Lambert-Niclot Sidonie , Peytavin Gilles , Duvivier Claudine , Poirot Catherine , Algarte-Genin Michèle , Pakianather Sophie , Meynard Jean-Luc , Valantin Marc-Antoine , Molina Jean-Michel , Flandre Philippe , Katlama Christine , Calvez Vincent , Marcelin Anne-Geneviève
Published: August 2010

HIV-1 RNA level and darunavir concentration in the genital tract were measured in 45 men receiving darunavir-ritonavir mono- or tritherapy. At week 48, a low frequency (3/45) of HIV-1 RNA shedding was observed in patients (1 on monotherapy and 2 on triple therapy), although they had undetectable HIV-1 RNA in plasma. The median darunavir seminal plasma concentration was close to the blood plasma free fraction, demonstrating a good penetration of darunavir into the male genital tract.
Characterization of Two Newly Identified Genes,
vgaD
and
vatG
, Conferring Resistance to Streptogramin A in
Enterococcus faecium
Authors: Jung Young-Hee , Shin Eun Shim , Kim Okgene , Yoo Jung Sik , Lee Kyeong Min , Yoo Jae Il , Chung Gyung Tae , Lee Yeong Seon
Published: August 2010

We characterized two new streptogramin A resistance genes from quinupristin-dalfopristin-resistant
Enterococcus faecium
JS79, which was selected from 79
E. faecium
isolates lacking known genes encoding streptogramin A acetyltransferase. A 5,650-bp fragment of HindIII-digested plasmid DNA from
E. faecium
JS79 was cloned and sequenced. The fragment contained two open reading frames carrying resistance genes related to streptogramin A, namely, genes for an acetyltransferase and an ATP efflux pump. The first open reading frame comprised 648 bp encoding 216 amino acids with a predicted left-handed parallel β-helix domain structure; this new gene was designated
vatG
. The second open reading frame consisted of 1,575 bp encoding 525 amino acids with two predicted ATPase binding cassette transporters comprised of Walker A, Walker B, and LSSG motifs; this gene was designated
vgaD
.
vgaD
is located 65 bp upstream from
vatG
, was detected together with
vatG
in 12 of 179 quinupristin-dalfopristin-resistant
E. faecium
isolates, and was located on the same plasmid. Also, the 5.6-kb HindIII-digested fragment which was observed in JS79 was detected in nine
vgaD
- and
vatG
-containing
E. faecium
isolates by Southern hybridization. Therefore, it was expected that these two genes were strongly correlated with each other and that they may be composed of a transposon. Importantly,
vgaD
is the first identified ABC transporter conferring resistance to streptogramin A in
E. faecium
. Pulsed-field gel electrophoresis patterns and sequence types of
vgaD
- and
vatG
-containing
E. faecium
isolates differed for isolates from humans and nonhumans.
Monofunctional and Polyfunctional CD8+T Cell Responses to Human Herpesvirus 8 Lytic and Latency Proteins
Authors: Lepone Lauren , Rappocciolo Giovanna , Knowlton Emilee , Jais Mariel , Piazza Paolo , Jenkins Frank J. , Rinaldo Charles R.
Published: August 2010

Human herpesvirus 8 (HHV-8) is the etiological agent of Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. It is postulated that CD8+T cell responses play an important role in controlling HHV-8 infection and preventing development of disease. In this study, we investigated monofunctional and polyfunctional CD8+T cell responses to HHV-8 lytic proteins gB (glycoprotein B) and K8.1 and latency proteins LANA-1 (latency-associated nuclear antigen-1) and K12. On the basis of our previous findings that dendritic cells (DC) reveal major histocompatibility complex (MHC) class I epitopes in gB, we used a DC-based system to identify 2 novel epitopes in gB, 2 in K8.1, 5 in LANA-1, and 1 in K12. These new HHV-8 epitopes activated monofunctional and polyfunctional CD8+T cells that produced various combinations of gamma interferon, interleukin 2, tumor necrosis factor alpha, macrophage inhibitory protein 1β, and cytotoxic degranulation marker CD107a in healthy HHV-8-seropositive individuals. We were also able to detect HHV-8-specific CD8+T cells in peripheral blood samples using HLA A*0201 pentamer complexes for one gB epitope, one K8.1 epitope, two LANA-1 epitopes, and one K12 epitope. These immunogenic regions of viral lytic and latency proteins could be important in T cell control of HHV-8 infection.
Field Evaluation of the Efficacy of
Mycobacterium bovis
Bacillus Calmette-Guérin against Bovine Tuberculosis in Neonatal Calves in Ethiopia
Authors: Ameni Gobena , Vordermeier Martin , Aseffa Abraham , Young Douglas B. , Hewinson R. Glyn
Published: August 2010

In developing countries, the conventional test and slaughter strategy for the control of bovine tuberculosis is prohibitively expensive, and alternative control methods such as vaccination are urgently required. In this study, the efficacy of
Mycobacterium bovis
bacillus Calmette-Guérin (BCG) for protection against bovine tuberculosis (bTB) was evaluated in Holstein calves under field conditions in Ethiopia. Thirteen neonatally vaccinated and 14 control calves were exposed for 10 to 23 months to skin test reactor cows. Gamma interferon (IFN-γ) testing, comparative intradermal tuberculin testing, postmortem examination, and bacteriological culture were used for the evaluation of BCG efficacy. The overall mean pathology score was significantly (
P
< 0.05) higher in control calves than in vaccinated calves. Culture positivity for
Mycobacterium bovis
was higher in the control calves than in the vaccinated calves, and significantly more BCG-vaccinated animals would have passed a standard meat inspection (
P
= 0.021). Overall, the protective efficacy of BCG was between 56% and 68%, depending on the parameters selected. Moreover, by measuring gamma interferon responses to the antigens ESAT-6 and CFP-10, which are present in
M. bovis
but absent from BCG, throughout the experiment, we were able to distinguish between vaccinated animals that were protected against bTB and those animals that were not protected. In conclusion, the present trial demonstrated an encouraging protective effect of BCG against bTB in a natural transmission setting in Ethiopia.
Helicobacter pylori
Exploits Cholesterol-Rich Microdomains for Induction of NF-κB-Dependent Responses and Peptidoglycan Delivery in Epithelial Cells
Authors: Hutton Melanie L. , Kaparakis-Liaskos Maria , Turner Lorinda , Cardona Ana , Kwok Terry , Ferrero Richard L.
Published: August 2010

Infection with
Helicobacter pylori cag
pathogenicity island (
cag
PAI)-positive strains is associated with more destructive tissue damage and an increased risk of severe disease. The
cag
PAI encodes a type IV secretion system (TFSS) that delivers the bacterial effector molecules CagA and peptidoglycan into the host cell cytoplasm, thereby inducing responses in host cells. It was previously shown that interactions between CagL, present on the TFSS pilus, and host α
5
β
1
integrin molecules were critical for CagA translocation and the induction of cytoskeletal rearrangements in epithelial cells. As the α
5
β
1
integrin is found in cholesterol-rich microdomains (known as lipid rafts), we hypothesized that these domains may also be involved in the induction of proinflammatory responses mediated by NOD1 recognition of
H. pylori
peptidoglycan. Indeed, not only did methyl-β-cyclodextrin depletion of cholesterol from cultured epithelial cells have a significant effect on the levels of NF-κB and interleukin-8 (IL-8) responses induced by
H. pylori
bacteria with an intact TFSS (
P
< 0.05), but it also interfered with TFSS-mediated peptidoglycan delivery to cells. Both of these effects could be restored by cholesterol replenishment of the cells. Furthermore, we demonstrated for the first time the involvement of α
5
β
1
integrin in the induction of proinflammatory responses by
H. pylori.
Taking the results together, we propose that α
5
β
1
integrin, which is associated with cholesterol-rich microdomains at the host cell surface, is required for NOD1 recognition of peptidoglycan and subsequent induction of NF-κB-dependent responses to
H. pylori
. These data implicate cholesterol-rich microdomains as a novel platform for TFSS-dependent delivery of bacterial products to cytosolic pathogen recognition molecules.
CsrA and Cra Influence
Shigella flexneri
Pathogenesis
Authors: Gore Aja L. , Payne Shelley M.
Published: August 2010

Shigella flexneri
is a facultative intracellular pathogen that invades and disrupts the colonic epithelium. In order to thrive in the host,
S. flexneri
must adapt to environmental conditions in the gut and within the eukaryotic cytosol, including variability in the available carbon sources and other nutrients. We examined the roles of the carbon consumption regulators CsrA and Cra in a cell culture model of
S. flexneri
virulence. CsrA is an activator of glycolysis and a repressor of gluconeogenesis, and a
csrA
mutant had decreased attachment and invasion of cultured cells. Conversely, Cra represses glycolysis and activates gluconeogenesis, and the
cra
mutant had an increase in both attachment and invasion compared to the wild-type strain. Both mutants were defective in plaque formation. The importance of the glycolytic pathway in invasion and plaque formation was confirmed by testing the effect of a mutation in the glycolysis gene
pfkA
. The
pfkA
mutant was noninvasive and had cell surface alterations as indicated by decreased sensitivity to SDS and an altered lipopolysaccharide profile. The loss of invasion by the
csrA
and
pfkA
mutants was due to decreased expression of the
S. flexneri
virulence factor regulators
virF
and
virB
, resulting in decreased production of
Shigella
invasion plasmid antigens (Ipa). These data indicate that regulation of carbon metabolism and expression of the glycolysis gene
pfkA
are critical for synthesis of the virulence gene regulators VirF and VirB, and both the glycolytic and gluconeogenic pathways influence steps in
S. flexneri
invasion and plaque formation.
Assessment of
Clostridium difficile
Infections by Quantitative Detection of
tcdB
Toxin by Use of a Real-Time Cell Analysis System
Authors: Ryder Alex B. , Huang Ying , Li Haijing , Zheng Min , Wang Xiaobo , Stratton Charles W. , Xu Xiao , Tang Yi-Wei
Published: August 2010

We explored the use of a real-time cell analysis (RTCA) system for the assessment of
Clostridium difficile
toxins in human stool specimens by monitoring the dynamic responses of the HS27 cells to
tcdB
toxins. The
C. difficile
toxin caused cytotoxic effects on the cells, which resulted in a dose-dependent and time-dependent decrease in cell impedance. The RTCA assay possessed an analytical sensitivity of 0.2 ng/ml for
C. difficile
toxin B with no cross-reactions with other enterotoxins, nontoxigenic
C. difficile
, or other
Clostridum
species. Clinical validation was performed on 300 consecutively collected stool specimens from patients with suspected
C. difficile
infection (CDI). Each stool specimen was tested in parallel by a real-time PCR assay (PCR), a dual glutamate dehydrogenase and toxin A/B enzyme immunoassay (EIA), and the RTCA assay. In comparison to a reference standard in a combination of the three assays, the RTCA had a specificity of 99.6% and a sensitivity of 87.5% (28 of 32), which was higher than the EIA result (
P
= 0.005) but lower than the PCR result (
P
= 0.057). In addition, the RTCA assay allowed for quantification of toxin protein concentration in a given specimen. Among RTCA-positive specimens collected prior to treatment with metronidazole and/or vancomycin, a significant correlation between toxin protein concentrations and clinical CDI severities was observed (
R
2
= 0.732,
P
= 0.0004). Toxin concentrations after treatment (0.89 ng/ml) were significantly lower than those prior to the treatment (15.68 ng/ml, Wilcoxon
P
= 0.01). The study demonstrates that the RTCA assay provides a functional tool for the potential assessment of
C. difficile
infections.
Poor Positive Accuracy of QuickVue Rapid Antigen Tests during the Influenza A (H1N1) 2009 Pandemic
Authors: Stevenson Heather L. , Loeffelholz Michael J.
Published: August 2010

We assessed the accuracy of positive QuickVue rapid influenza virus antigen test results. Using reverse transcription (RT)-PCR as the gold standard, 17 (37.8%) of 45 QuickVue-positive specimens were determined to be false positives. We report an unexpectedly high rate of false-positive QuickVue results during a period of high influenza A (H1N1) 2009 virus prevalence.
Histone Deacetylases and the Nuclear Receptor Corepressor Regulate Lytic-Latent Switch Gene 50 in Murine Gammaherpesvirus 68-Infected Macrophages
Authors: Goodwin Megan M. , Molleston Jerome M. , Canny Susan , Abou El Hassan Mohamed , Willert Erin K. , Bremner Rod , Virgin Herbert W.
Published: August 2010

Gammaherpesviruses are important oncogenic pathogens that transit between lytic and latent life cycles. Silencing the lytic gene expression program enables the establishment of latency and a lifelong chronic infection of the host. In murine gammaherpesvirus 68 (MHV68, γHV68), essential lytic switch gene 50 controls the interchange between lytic and latent gene expression programs. However, negative regulators of gene 50 expression remain largely undefined. We report that the MHV68 lytic cycle is silenced in infected macrophages but not fibroblasts and that histone deacetylases (HDACs) mediate silencing. The HDAC inhibitor trichostatin A (TSA) acts on the gene 50 promoter to induce lytic replication of MHV68. HDAC3, HDAC4, and the nuclear receptor corepressor (NCoR) are required for efficient silencing of gene 50 expression. NCoR is critical for transcriptional repression of cellular genes by unliganded nuclear receptors. Retinoic acid, a known ligand for the NCoR complex, derepresses gene 50 expression and enhances MHV68 lytic replication. Moreover, HDAC3, HDAC4, and NCoR act on the gene 50 promoter and are recruited to this promoter in a retinoic acid-responsive manner. We provide the first example of NCoR-mediated, HDAC-dependent regulation of viral gene expression.
Kaposi's Sarcoma-Associated Herpesvirus Inhibits Interleukin-4-Mediated STAT6 Phosphorylation To Regulate Apoptosis and Maintain Latency
Authors: Cai Qiliang , Verma Subhash C. , Choi Ji-Young , Ma Michelle , Robertson Erle S.
Published: August 2010

Cytokine-mediated JAK/STAT signaling controls numerous important biologic responses like immune function, cellular growth, and differentiation. Inappropriate activation of this signaling pathway is associated with a range of malignancies. Kaposi's sarcoma-associated herpesvirus (KSHV) is the infectious viral agent associated with Kaposi's sarcoma and may also contribute to B-cell disorders, which include primary effusion lymphoma (PEL) and multicentric Castleman's disease. However, regulation of cytokine-mediated lymphocytic immune response by KSHV is not fully understood. In this report, we demonstrate that KSHV suppresses the interleukin-4 (IL-4)-stimulated immune response of B-lymphocyte activation and cell proliferation. Moreover, we show that the latency-associated nuclear antigen (LANA) encoded by KSHV is essential for viral blocking of IL-4-induced signaling. LANA reduces phosphorylation of the signal transducers and activators of transcription 6 (STAT6) on Y-641 and concomitantly its DNA binding ability. Importantly, knockdown of endogenous STAT6 dramatically increases the sensitivity of PEL cells to low-serum stress or chemical-mediated cellular apoptosis and reactivation of KSHV from latent replication. Thus, these findings suggest that the IL-4/STAT6 signaling network is precisely controlled by KSHV for survival, maintenance of latency, and suppression of the host cytokine immune response of the virus-infected cells.