bluuebunny/crossref_metadata_2025 huggingface dataset:
Modèle topologique de la structure d’un antiport vacuolaire de type NHX chez la vigne cultivée (Vitis vinifera)
Authors: Hanana Mohsen , Cagnac Olivier , Mliki Ahmed , Blumwald Eduardo
Published: April 2009

After identifying and isolating a grapevine ( Vitis vinifera L.) NHX vacuolar antiporter and before initializing functional genomic studies, we juged necessary to acquire a minimum of knowledge about the VvNHX1 protein. Thus, we realized a bioinformatic analysis to determine its basic characteristics and to get structural informations that could guide us through the functional characterization. We have determined important physico-chemical parameters (molecular mass, isoelectric point, hydrophobic regions, etc.) and obtained interesting structural data (primary, secondary, and tertiary structures; conserved domains and interaction motives; etc.). The VvNHX1 gene, which encodes this 541 amino-acid protein with a predicted molecular mass of 60 kDa, is made of 14 exons and measures 6.5 kb. The amino-acidic composition of this protein is very important, in particular, for the establishment of the α-helix structure, which represents more than 50% of the protein, but also for charge distribution, which generates critical electrostatic interactions for the ionic flux. The secondary structure of VvNHX1 contains multiple transmembrane α-helix segments that are made of hydrophobic amino-acid residues, thus facilitating its insertion in the membrane. Globally, VvNHX1 has one hydrophobic N-terminal region, made of 10 transmembrane segments with 440 amino-acid residues, and one hydrophilic C-terminal region, made of 100 residues. The region located between the fourth and fifth transmembrane segments represents, with its structure mainly helicoidal and the presence of a favourable electrostatic environment, the pore where cation flux is performed across the membrane. VvNHX1 contains various interaction domains as well as several putative posttranslational modification sites, mainly at the C-terminus but also at the N-terminus, that play an important part in regulating protein activities, influence protein structural stability, or interact with other proteins or signalling molecules.
The disinfection efficacy of chlorine and chlorine dioxide as disinfectants of Bacillus globigii, a surrogate for Bacillus anthracis, in water networks: A comparative studyA paper submitted to the Journal of Environmental Engineering and Science.
Authors: Hosni Ahmed A. , Shane William T. , Szabo Jeffery G. , Bishop Paul L.
Published: April 2009

Intentional contamination of drinking water with anthrax spores is a concern to water utilities. The spores may become embedded in the distribution pipe corrosion and biofilm, where they will be protected from residual disinfectants. This paper compares the disinfection effectiveness of chlorine and chlorine dioxide on Bacillus globigii , a surrogate for B. anthracis . Batch experiments were performed using both disinfectants. Data was analyzed using the delayed Chick-Watson model to determine the corresponding CTlag (CT = concentration × time) values and Watson plots, which indicate the dominant factors affecting disinfection kinetics. Chlorine dioxide had CTlag values almost one tenth of those observed for chlorine. However, Watson plots showed that exposure time and disinfectant concentrations have equal weights on the inactivation rate of both disinfectants.
A new type of ductile composite reinforcing bar with high tensile elastic modulus for use in reinforced concrete structures
Authors: Cui Yi-Hua , Tao Jie
Published: April 2009

A new core-shell model of hybrid composite bar has been developed, in which steel and glass fibers are randomly dispersed across the cross section of the core, and Twaron (Teijin Twaron, the Netherlands) and carbon fibers placed within the shell. Compared with glass composite reinforcing bars, the new hybrid composite bars possess characteristics of corrosion resistance, ductility, and high tensile elastic moduli and strength, and have potential for application in concrete structures.
Phase separation behavior of three common alcohols with methoxy-nonafluorobutane or ethoxy-nonafluorobutane in waterA paper submitted to the Journal of Environmental Engineering and Science.
Authors: Lee Kenneth Y. , Ha Duong T.
Published: April 2009

Laboratory experiments are conducted to determine the liquid–liquid phase separation behavior of six three-component systems with each system comprised of a common alcohol (namely ethanol, isopropanol, or methanol), water, and one of two engineered dense nonaqueous phase liquids (DNAPLs) manufactured by the 3M™ Corporation (namely methoxy-nonafluorobutane (HFE-7100) or ethoxy-nonafluorobutane (HFE-7200)). The experimental results are presented on ternary phase diagrams and compared against available published experimental data where tetrachloroethylene (PCE) and (or) trichloroethylene (TCE) is the dense nonaqueous phase liquid (DNAPL). Results show that the two engineered fluids exhibit similar phase separation behavior in the presence of the same alcohol. Furthermore, these engineered fluids exhibit similar phase separation behavior to that of PCE, but relatively dissimilar phase separation behavior to that of TCE.
A novel solution for construction on-site communication – the information booth
Authors: Hewage Kasun N. , Ruwanpura Janaka Y.
Published: April 2009

A recent study on construction productivity improvement at the University of Calgary revealed the direct tool time (working time) of Alberta’s commercial construction to be about 51%. This study exposed inadequate communication and unavailability of required information as the main causes for a relatively lower tool time. Use of information technology (IT) to overcome widely visible communication issues was extremely limited at the construction site level. Construction companies’ hesitation to adopt new technologies was well noted whereas construction workers expressed their willingness and ability to use IT at the site level. The objective of this paper is to discuss the concept and the application of a novel communication tool (called an information booth) developed and pilot tested at a construction project. The concept and the technology presented in this paper have been tested at an actual construction project resulting in improvements in construction productivity, worker satisfaction, and efficiency. This paper also elaborates the rationale for a new technological framework (and the information booth), barriers for technology implementation, research objectives, methodology, and data analysis.
Compression of granular materials
Authors: Mesri Gholamreza , Vardhanabhuti Barames
Published: April 2009

Compression data on over 100 sands were examined to clarify the role of particle rearrangement through interparticle slip and rotation and particle damage on primary compression, including the yield stress, secondary compression, and coefficient of lateral pressure at rest. During the increase in effective vertical stress, mechanisms such as tighter packing that promote particle locking and interparticle slip and particle damage that promote particle unlocking together determine the relationship between void ratio and effective vertical stress. Three levels of particle damage together with interparticle slip and rotation determine three types of compression behavior and a yield stress at the abrupt onset of particle fracturing and splitting. The ratio of secondary compression index to compression index is independent of whether compression results from overcoming interparticle friction through interparticle slip, from overcoming particle strength through particle damage, or both; and therefore it is a constant independent of the effective stress range. The coefficient of lateral pressure at rest of an initially dense sand starts with a value defined by the Jaky equation and the maximum friction angle and remains constant up to the abrupt onset of particle fracturing and splitting, at which point it begins to increase with an increase in effective vertical stress.
Composition of demolition wastes from Chi-Chi earthquake-damaged structures and the properties of their inert materials
Authors: Yang Chau-Ping
Published: April 2009

The disastrous Chi-Chi earthquake struck Taiwan on 21 September 1999 and resulted in the creation of more than 20 million cubic metres of demolition waste, which was stored temporarily at several sites. To reduce the site clearing costs, the inert materials (concrete, brick, pottery, and fines) in the wastes should be reclaimed and recycled immediately; but most of their properties were not known. Therefore, this study investigates the properties of demolition wastes, including inert materials, coarse portions, and fines obtained from two earthquake demolition waste storage sites (Puli and Tali) and one normal urban construction waste storage site (Taichung). It is found that the volumetric content of inert materials from earthquake demolition waste is about 96%. Such inert material is classified as having an excellent subgrade rating and can be reused as subbase and base soils. The abrasion level of the coarse portions of inert materials from the three sites meets the required level of coarse aggregate according to Standard Taiwan Code CNS-490. On the other hand, the maximum dry unit weights of fines of inert materials from the three sites are greater than 14.7 kN/m3, and their shear strengths are higher than that of the same classification group (SW–SM) of natural soils, so they can be reused as construction soils.
Comparative study on the behavior of square foundations resting on confined sand
Authors: Eid Hisham T. , Alansari Omar A. , Odeh Abdelfattah M. , Nasr Mohannad N. , Sadek Husam A.
Published: April 2009

The behavior of shallow foundations resting on laterally and (or) vertically confined sand has been investigated using physical and numerical modeling. The models were designed to simulate the frequently constructed raft foundations that are surrounded by sheet-pile walls to support excavation sides of sand underlain by a rock bed. Laboratory tests were carried out utilizing a square foundation model surrounded by rigid steel walls with different depths, resting on sand that was underlain by a rough rigid layer. Varying sand-layer thicknesses and relative densities were utilized. A three-dimensional finite element analysis was conducted to verify the physical-model test results and to infer the performance of full-scale foundations. Based on the results of the experimental and numerical analyses, charts are presented to estimate the enhanced bearing capacity of square foundations resting on confined sand. These charts are presented in terms of bearing capacity of the surface foundation resting on extended sand, sand relative density, wall width to foundation width ratio, and rigid layer depth. Charts are also presented to estimate settlement reductions due to the bearing sand lateral and (or) vertical confinement.
A simple generalization of the Faustmann formula to tree level
Authors: Heshmatol Vaezin S.M. , Peyron J.-L. , Lecocq F.
Published: April 2009

The economic decision model serving as an objective function in forest economics was conceived originally by Faustmann at the stand level. Nevertheless, the tree level seems to be an appropriate scale for analysis, especially for harvesting decisions and certain estimations both at tree and stand levels. However, the Faustmann formula cannot be directly applied to the tree level. The present research has provided certain tree-level formulations of the Faustmann formula, including, in particular, tree expectation value (TEV) and land expectation value (LEV). TEV and tree-level LEV formulas were developed by analyzing the Faustmann formula under deterministic conditions. Unlike previous tree-level decision models presented in the forest economics literature, TEV and tree-level LEV formulas incorporate the expectation value of the land occupied by trees and its variability over time as well as the interaction between trees and their trajectories (cutting age). The proposed formulas were then compared with the Faustmann formula using the first-order condition of optimal harvest age. The TEV and tree-level LEV formulas appeared to be absolutely compatible with the Faustmann formula. The utility of the proposed formulas was then illustrated with application examples, including target diameter, stand expectation value, TEV, LEV, and the value of damage to beech trees or stands in northeastern France.
Does thinning affect litterfall, litter decomposition, and associated nutrient release inAcacia mangiumstands of Kerala in peninsular India?
Authors: Kunhamu T.K. , Kumar B.M. , Viswanath S.
Published: April 2009

Litter plays a vital role in the nutrient cycling of plantations and agroforests. Silvicultural interventions can alter litter production and decay rates, thereby varying nutrient fluxes. We evaluated the effect of various thinning densities on litter dynamics of 9-year-old Acacia mangium Willd. stands. To quantify litterfall, we placed traps at four random grid points in 24 plots in which none, one-third, one-half, or two-thirds of stems had been removed. In each plot, 48 litterbags were also placed to evaluate litter decay. Annual litterfall ranged from 5.73 (two-thirds thinning) to 11.18 Mg·ha−1(unthinned) and showed a significant linear relationship to basal area (p < 0.0001). Nitrogen (N), phosphorus (P), and potassium (K) concentrations were highest during the wet season, when litterfall production was low, implying an inverse relationship between litterfall quality and quantity. The highest annual N, P, and K additions (82.9, 3.3, and 71.9 kg·ha−1, respectively) occurred in the unthinned stands. High thinning intensities resulted in accelerated decay rates, which we attribute to changes in microenvironment. Soil N concentrations were highest in the one-half thinning treatment, followed by the two-thirds treatment, signifying a trade-off between litterfall production and decay. The highest soil organic C concentrations were in the unthinned stands, reflecting the potential of high stand densities for promoting C sequestration.
Basal medium improvement for routine micropropagation of Olea maderensis: physiological comparative studies
Authors: Brito Gina , Santos Conceição
Published: April 2009

The routine micropropagation of Olea maderensis (Lowe) Rivas Mart. & Del Arco requires an adequate basal medium. To find the optimal basal medium, shoots were grown on four different media: olive medium (OM) and three modified OM media enriched with 2, 4, and 10 times the iron (Fe), magnesium (Mg), and manganese (Mn) concentrations of the OM medium, respectively (OMG, OMG4, and OMG10). For the elongation–proliferation stage, media were supplemented with 9.12 µmol·L–1 zeatin. Doubling the Fe, Mg, and Mn concentrations (OMG) provided green and healthy shoots, while in other media leaf chlorosis or necrosis and abscission occurred because of either deficiency (OM) or toxicity of the elements (OMG4 and OMG10). Shoots grown in the OMG medium also had the highest elongation–proliferation rates. Physiological studies were then performed only between OMG- and OM-grown shoots. Chlorophyll a and b contents and fluorescence (Fv, Fm) were higher in OMG-grown shoots. Doubling the concentration of Fe, Mg, and Mn (which are important in photosynthesis) stimulated leaf survival and photosynthesis. OMG-grown leaves had higher Mg, Fe, and Mn levels. Compared with field leaves, in vitro leaves had higher protein contents. Other physiological parameters (membrane integrity, water content, and osmolality) did not differ between the two media. The best rooting rates were obtained for shoots grown in OMG (>85%), and plants were successfully acclimatized. These studies improved the efficiency and quality of micropropagation of O. maderensis, thereby allowing germplasm preservation of this endangered species.
The effect of site quality on growth efficiency of upper crown class Picea rubens and Abies balsamea in Maine, USAPublication 3046 of the Maine Agricultural and Forestry Experiment Station.
Authors: DeRose R. Justin , Seymour Robert S.
Published: April 2009

The influence of site index on growth efficiency was studied for 411 dominant and codominant Abies balsamea (L.) Mill. and Picea rubens Sarg. from 10 sites across Maine, USA. Young A. balsamea (n = 204) were from stands precommercially thinned 15–20 years ago and ranged in site index from 18.4 to 24.3, while the older P. rubens (n = 207) were from stands that were not precommercially thinned and ranged in site index from 13.1 to 17.8. We hypothesized that site index positively influences growth efficiency. The results showed that volume increment – leaf area relationships and growth efficiency increased significantly with site index for A. balsamea but were unaffected by site index for P. rubens. A monotonic decreasing pattern of growth efficiency over increasing leaf area was found for both species. When standardized per unit site index, growth efficiency behaved nonlinearly for both species.
Development of a standardized methodology for quantifying total chlorophyll and carotenoids from foliage of hardwood and conifer tree species
Authors: Minocha Rakesh , Martinez Gabriela , Lyons Benjamin , Long Stephanie
Published: April 2009

Despite the availability of several protocols for the extraction of chlorophylls and carotenoids from foliage of forest trees, information regarding their respective extraction efficiencies is scarce. We compared the efficiencies of acetone, ethanol, dimethyl sulfoxide (DMSO), and N, N-dimethylformamide (DMF) over a range of incubation times for the extraction of chlorophylls and carotenoids using small amounts of unmacerated tissue. Of the 11 species studied, comparable amounts of chlorophyll were extracted by all four solvents from three species and by ethanol and DMF from nine species. In four species, acetone, ethanol, and DMF extracted comparable chlorophyll amounts, while in another two species comparable amounts were extracted by ethanol, DMSO, and DMF. In one species, ethanol extracted significantly greater amounts of chlorophyll compared with all other solvents. The brown coloration of DMSO extracts for some species compromised the calculations of chlorophylls and carotenoids, making DMSO a poor choice. Overall, extraction efficiencies of ethanol and DMF were comparable for analyzing chlorophyll concentrations. However, because DMF is more toxic than ethanol, we recommend ethanol as the better option of these two for chlorophyll extractions. On the other hand, DMF is the most efficient solvent among the four tested for the extraction of carotenoids from these species. The results presented will facilitate the design of multispecies local- and regional-scale ecological studies to evaluate forest health. Additionally, they will enable reliable comparisons of results from multiple laboratories and (or) studies that used different solvents and help validate chlorophyll estimates obtained by remote sensing.
INTERPRETING THE M2-BRANE ACTION
Authors: BANERJEE SHAMIK , SEN ASHOKE
Published: April 2009

The world-volume theory of multiple M2-branes proposed recently has a free scalar field. For large vev of this scalar field the world-volume action reduces to that of multiple D2-branes with Yang–Mills coupling proportional to the vev. We suggest that the correct interpretation of this scalar field is as the radial position of the M2-brane center of mass in a cylindrical polar coordinate system. Regarding the azimuthal angle as compact we can regard this as a set of coincident D2-branes in type IIA string theory with varying dilaton and metric. We find that the effective world-volume theory on the D2-branes has Yang–Mills coupling proportional to the radial coordinate; furthermore the radial coordinate satisfies free field equations of motion. This agrees with the corresponding results derived from the M2-brane world-volume theory.
GRAVITATIONAL OBSERVABLES, INTRINSIC COORDINATES, AND CANONICAL MAPS
Authors: PONS J. M. , SALISBURY D. C. , SUNDERMEYER K. A.
Published: April 2009

It is well known that in a generally covariant gravitational theory the choice of spacetime scalars as coordinates yields phase-space observables (or "invariants"). However, their relation to the symmetry group of diffeomorphism transformations has remained obscure. In a symmetry-inspired approach we construct invariants out of canonically induced active gauge transformations. These invariants may be interpreted as the full set of dynamical variables evaluated in the intrinsic coordinate system. The functional invariants can explicitly be written as a Taylor expansion in the coordinates of any observer, and the coefficients have a physical and geometrical interpretation. Surprisingly, all invariants can be obtained as limits of a family of canonical transformations. This permits a short (again geometric) proof that all invariants, including the lapse and shift, satisfy Poisson brackets that are equal to the invariants of their corresponding Dirac brackets.
EINSTEIN–MAXWELL–DILATON BLACK BRANES WITH ARBITRARY TENSION AND DILATON CHARGE
Authors: SHIN IKJAE , YUN SANGHEON
Published: April 2009

In this note, we show that special choice of the metric ansatz simplifies the equations of motion for black branes. Then we use the trick to construct charged, dilatonic black branes of Einstein–Maxwell–dilaton gravity in D = n + p + 2 dimensions, which are invariant under translation along p directions and have spherical symmetry of Sn. The solutions are characterized by mass density and tension, magnetic charges, dilaton charge and coupling constant.
MODERN ARCHITECTURES FOR EMBEDDED RECONFIGURABLE SYSTEMS — A SURVEY
Authors: JÓZWIAK LECH , NEDJAH NADIA
Published: April 2009

Reconfigurable systems, exploiting a mixture of the traditional CPU-centric instruction-stream-based processing with the decentralized parallel application-specific data-dominated processing, provide a drastically higher performance and lower power consumption than the traditional CPU-centric systems. They do it at much lower costs and shorter times to market than the not reconfigurable hardware solutions. They also provide the flexibility that is often required for engineering of modern robust and adaptive systems. Due to their heterogeneity, flexibility and potential for highly optimized application-specific instantiation, the reconfigurable computing (RC) systems are adequate for a very broad class of applications across different industry sectors. In this paper, the basic definitions, concepts and features of reconfigurable systems are discussed, as well as their role, purposes they serve and applications that can significantly benefit from them. Also, a comparison of the hardwired systems, RC systems and CPU-centric systems is made, and some main concepts of an effective and efficient reconfigurable computing are discussed. Subsequently, the classification of the RC systems is introduced and their various architecture classes are overviewed. This is followed by a discussion of some major drivers and requirements of the recent and future developments in the modern RC system area, and an overview of the recent and future development trends in the RC architectures. The reconfigurable system area is a very promising, but quite a new field. New opportunities have been opened for this field through introduction of the system-on-a-chip technology, and a big progress has been made in the recent years. Many different reconfigurable devices and computers became commercially available. Nevertheless, multiple aspects of the RC systems, their development and their supporting tools still belong to the open research or development topics.
PERFORMANCE IMPACT OF TASK-TO-TASK COMMUNICATION PROTOCOL IN NETWORK-ON-CHIP
Authors: BAGHERZADEH NADER , MATSUURA MASARU
Published: April 2009

Network-on-Chip (NoC) is a strong candidate for scalable interconnect design of Multi-Processor System-on-Chip (MPSoC). Software tasks of MPSoC require a certain protocol to communicate with each other. In NoC such a communication protocol should be handled at Network Interface and/or Processor Element level and it is expected that different protocols show their trade-offs. In consideration of the above, we employed two types of basic protocol and investigated their performance impact. The contribution of this work is to quantitatively evaluate effectiveness of using separate communication protocols depending on the task structure.
BEHAVIORAL MODELING OF RF POWER AMPLIFIERS USING MODIFIED VOLTERRA SERIES
Authors: JIN ZHE , ZHOU YANWEI , SONG ZHIHUAN
Published: April 2009

There has been intensive research in memoryless nonlinear behavioral modeling of power amplifiers (PAs). But in broadband communication systems, memory effects of PAs can no longer be ignored and traditional memoryless model cannot accurately characterize the input-output relationship of PAs. In order to treat memory effects and reduce the complexity of general Volterra model, a new behavioral PA model based on modified Volterra series is proposed. Since the characteristics of power amplifiers change during transmission time, a recursive least squares algorithm with size-fixed observation matrices is developed to update the parameters of the PA model. This identification algorithm, which uses only the latest sample data to identify the parameters, can decrease computational complexity and data storage space needed for identification. Simulations are carried out to validate the performances of the proposed PA model and identification algorithm.
ON THE GENERALIZATION OF SECOND-ORDER FILTERS TO THE FRACTIONAL-ORDER DOMAIN
Authors: RADWAN A. G. , ELWAKIL A. S. , SOLIMAN A. M.
Published: April 2009

This work is aimed at generalizing the design of continuous-time second-order filters to the non-integer-order (fractional-order) domain. In particular, we consider here the case where a filter is constructed using two fractional-order capacitors both of the same order α. A fractional-order capacitor is one whose impedance is Zc = 1/C(jω)α, C is the capacitance and α (0 < α ≤ 1) is its order. We generalize the design equations for low-pass, high-pass, band-pass, all-pass and notch filters with stability constraints considered. Several practical active filter design examples are then illustrated supported with numerical and PSpice simulations. Further, we show for the first time experimental results using the fractional capacitive probe described in Ref. 1.
STRAIN-ORDER COUPLING IN NEMATIC ELASTOMERS: EQUILIBRIUM CONFIGURATIONS
Authors: CESANA PIERLUIGI , DESIMONE ANTONIO
Published: April 2009

We consider models that describe liquid crystal elastomers either in a biaxial or in a uniaxial phase and in the framework of Frank's director theory. We prove the existence of static equilibrium solutions in the presence of frustrations due to electro-mechanical boundary conditions and to applied loads and fields. We find explicit solutions arising in connection with special boundary conditions and the corresponding phase diagrams, leading to significant implications on possible experimental observations.
ASYMPTOTIC ANALYSIS OF AN ISOTHERMAL GAS FLOW THROUGH A LONG OR THIN PIPE
Authors: MARUŠIĆ-PALOKA EDUARD , STARČEVIĆ MAJA
Published: April 2009

In this paper we study the compressible stationary isothermal flow through a thin (or long) straight pipe. Starting from the compressible Stokes system, via rigorous asymptotic analysis, as the pipe's thickness tends to zero, we obtain the 1D model describing the effective behavior of the flow. The uniqueness of the solution for such model is proved, if the first component of the function g, appearing on the right-hand side of the system, does not change its sign. If it does change the sign, an example of non-uniqueness of the solution is given.
J-COHERENT RINGS
Authors: DING NANQING , LI YUANLIN , MAO LIXIN
Published: April 2009

Let R be a ring. Recall that a left R-module M is coherent if every finitely generated submodule of M is finitely presented. R is a left coherent ring if the left R-module RR is coherent. In this paper, we say that R is left J-coherent if its Jacobson radical J(R) is a coherent left R-module. J-injective and J-flat modules are introduced to investigate J-coherent rings. Necessary and sufficient conditions for R to be left J-coherent are given. It is shown that there are many similarities between coherent and J-coherent rings. J-injective and J-flat dimensions are also studied.
ANTI-COMMUTATIVE ALGEBRAS WITH SKEW-SYMMETRIC IDENTITIES
Authors: DZHUMADIL'DAEV A. S.
Published: April 2009

Generalizing Lie algebras, we consider anti-commutative algebras with skew-symmetric identities of degree > 3. Given a skew-symmetric polynomial f, we call an anti-commutative algebra f-Lie if it satisfies the identity f = 0. If sn is a standard skew-symmetric polynomial of degree n, then any s4-Lie algebra is f-Lie if deg f ≥ 4. We describe a free anti-commutative super-algebra with one odd generator. We exhibit various constructions of generalized Lie algebras, for example: given any derivations D, F of an associative commutative algebra U, the algebras (U, D ∧ F) and (U, id ∧ D2) are s4-Lie. An algebra (U, id ∧ D3 - 2D ∧ D2) is s'5-Lie, where s'5 is a non-standard skew-symmetric polynomial of degree 5.
ON n-PERFECT RINGS AND COTORSION DIMENSION
Authors: BENNIS DRISS , MAHDOU NAJIB
Published: April 2009

A ring is called n-perfect (n ≥ 0), if every flat module has projective dimension less or equal than n.

In this paper, we show that the n-perfectness relates, via homological approach, some homological dimensions of rings. We study n-perfectness in some known ring construction. Finally, several examples of n-perfect rings satisfying special conditions are given.
FINITE GROUPS ALL OF WHOSE SECOND MAXIMAL SUBGROUPS ARE PSC-GROUPS
Authors: SHEN ZHENCAI , LI SHIRONG , SHI WUJIE
Published: April 2009

A subgroup H of G is said to be self-conjugate-permutable if HHx = HxH implies Hx = H. A finite group G is called PSC-group if every cyclic subgroup of group G of prime order or order 4 is self-conjugate-permutable. In the paper, first we give the structure of finite group G, all of whose maximal subgroups are PSC-groups. Then we also classified that finite group G all of whose second maximal subgroups are PSC-groups.
Listeriolysin O affects barrier function and induces chloride secretion in HT-29/B6 colon epithelial cells
Authors: Richter Jan F. , Gitter Alfred H. , Günzel Dorothee , Weiss Siegfried , Mohamed Walid , Chakraborty Trinad , Fromm Michael , Schulzke Jörg D.
Published: April 2009

Listeria monocytogenes is a food-borne pathogen, which is able to induce diarrhea when residing in the intestine. We studied the effect of listeriolysin O (LLO), an extracellular virulence factor of L. monocytogenes, on intestinal transport and barrier function in monolayers of HT-29/B6 human colon cells using the Ussing technique to understand the pathomechanisms involved. Mucosal addition of LLO, but not a LLO mutant, induced a dose- and pH-dependent increase in short-circuit current ( ISC). Sodium and chloride tracer flux and DIDS sensitivity studies revealed that ISCwas mainly due to electrogenic chloride secretion. Barrier function was impaired by LLO, as assessed by transepithelial resistance ( Rt) and mannitol flux measurements. Intracellular signal transduction occurred through Ca2+release from intracellular stores and PKC activation. In conclusion, listeriolysin induces chloride secretion and perturbs epithelial barrier function, thus potentially contributing to Listeria-induced diarrhea.
Temperature alters solute transport in growth plate cartilage measured by in vivo multiphoton microscopy
Authors: Serrat Maria A. , Williams Rebecca M. , Farnum Cornelia E.
Published: April 2009

Solute delivery to avascular cartilaginous plates is critical to bone elongation, and impaired transport of nutrients and growth factors in cartilage matrix could underlie many skeletal abnormalities. Advances in imaging technology have revolutionized our ability to visualize growth plates in vivo, but quantitative methods are still needed. We developed analytical standards for measuring solute delivery, defined by amount and rate of intravenous tracer entry, in murine growth plates using multiphoton microscopy. We employed an acute temperature model because of its well-established impact on bone circulation and tested the hypothesis that solute delivery changes positively with limb temperature when body core and respiration are held constant (36°C, 120 breaths/min). Tibial growth plates were surgically exposed in anesthetized 5-wk-old mice, and their hindlimbs were immersed in warm (36°C) or cool (23°C) saline ( n = 6/group). After 30 min of thermal equilibration, we administered an intracardiac injection of fluorescein (50 μl, 0.5%) and captured sequentially timed growth plate images spanning 10 min at standardized depth. Absolute growth plate fluorescence was normalized to vascular concentrations for interanimal comparisons. As predicted, more fluorescein infiltrated growth plates at 36°C, with standardized values nearly double those at 23°C. Changing initial limb temperature did not alter baseline values, suggesting a sustained response period. These data validate the sensitivity of our system and have relevance to strategies for enhancing localized delivery of therapeutic agents to growth plates of children. Applications of this technique include assessment of solute transport in models of growth plate dysfunction, particularly chondrodysplasias with matrix irregularities.
Augmentation of Megakaryocyte Expression of FcγRIIa by Interferon γ
Authors: Schneider David J. , Taatjes-Sommer Heidi S.
Published: April 2009

Objective—

The purpose of this study was to identify factors that alter expression of FcγRIIa by megakaryocytes.

Methods and Results—

Effects of selected cytokines and growth factors on megakaryocyte expression of FcγRIIa were assessed with phorbol 12-myristate 13-acetate (PMA)-differentiated human erythroleukemia (HEL) cells and with thrombopoietin-differentiated CD34 stem cells and compared with those obtained with myelocytic cell lines and a monocytic cell lines. Expression of FcγRIIa was quantified with the use of Western blots and real-time reverse transcriptase-polymerase chain reaction. Megakaryocyte differentiation was identified by expression of CD41, CD42, and von Willebrand factor with the use of flow cytometry. Interferon (IFN) γ increased protein expression of FcγRIIa by HEL cells and CD34 stem cells after megakaryocyte differentiation (maximal ≈4-fold,
P
<0.001 for each). IFNγ did not increase expression of FcγRIIa by undifferentiated HEL and CD34 cells. Expression of FcγRIIa mRNA was increased (2-fold,
P
<0.001) in megakaryocyte-differentiated HEL cells. IFNγ did not increase expression of FcγRIIa by undifferentiated myelocytic or monocytic cell lines.

Conclusions—

IFNγ appears to selectively increase expression of FcγRIIa by cells exhibiting characteristics of megakaryocytes. This effect of IFNγ may contribute to greater platelet expression of FcγRIIa in patients with atherosclerotic vascular disease.
Acute Vascular Disruption and Aquaporin 4 Loss After Stroke
Authors: Friedman Beth , Schachtrup Christian , Tsai Philbert S. , Shih Andy Y. , Akassoglou Katerina , Kleinfeld David , Lyden Patrick D.
Published: April 2009

Background and Purpose—

Ischemic protection has been demonstrated by a decrease in stroke-infarct size in transgenic mice with deficient Aquaporin 4 (AQP4) expression. However, it is not known whether AQP4 is rapidly reduced during acute stroke in animals with normal AQP4 phenotype, which may provide a potential self-protective mechanism.

Methods—

Adult male rats underwent transient occlusion of the middle cerebral artery (tMCAo) for 1 to 8 hours followed by reperfusion for 30 minutes. Protein and mRNA expression of AQP4 and glial fibrillary acidic protein (GFAP) were determined by Western blot and rtPCR. Fluorescence quantitation was obtained with laser scanning cytometery (LSC) for Cy5-tagged immunoreactivity along with fluorescein signals from pathological uptake of plasma-borne high-molecular-weight fluorescein-dextran. Cell death was assessed with in vivo Propidium Iodide (PI) nucleus labeling.

Results—

In the ischemic hemisphere in tissue sections, patches of fluorescein-dextran uptake were overlapped with sites of focal loss of AQP4 immunoreactivity after tMCAo of 1 to 8 hours duration. However, the average levels of AQP4 protein and mRNA, determined in homogenates of whole striatum, were not significantly reduced after 8 hours of tMCAo. Tissue section cytometry (LSC) of immunoreactivity in scan areas with high densities of fluorescein-dextran uptake demonstrated reductions in AQP4, but not in IgG or GFAP, after tMCAo of 2 hours or longer. Scan areas with low densities of fluorescein-dextran did not lose AQP4. There was sparse astrocyte cell death as only 1.7±0.85% (mean, SD) of DAPI labeled cells were PI- and GFAP-labeled after 8 hours of tMCAo.

Conclusions—

During acute tMCAo, a rapid loss of AQP4 immunoreactivity from viable astrocytes can occur. However, AQP4 loss is spatially selective and occurs primarily in regions of vascular damage.
Ethnicity Does Not Affect the Homocysteine-Lowering Effect of B-Vitamin Therapy in Singaporean Stroke Patients
Authors: Kasiman Katherine , Eikelboom John W. , Hankey Graeme J. , Lee Samantha P.-K. , Lim Joanna P.-Z. , Lee Jasinda H.-Q. , Chang Hui-Meng , Wong Meng-Cheong , Chen Christopher P.L.-H.
Published: April 2009

Background and Purpose—

Increased total homocysteine (tHcy) is a risk factor for stroke. This study examines whether the efficacy of B-vitamins in reducing tHcy is modified by ethnicity in a Singaporean ischemic stroke population.

Methods—

505 patients (419 Chinese, 41 Malays and 45 Indians) with ischemic stroke were randomized to receive placebo or B-vitamins. Fasting blood samples collected at baseline and 1 year were assayed for tHcy.
MTHFR
polymorphisms were genotyped.

Results—

Ethnicity did not independently determine tHcy at baseline. The magnitude of tHcy reduction by B-vitamin treatment was consistent across ethnic groups (Chinese −3.8±4.5, Malay −4.9±4.2, and Indian −3.3±3.6μmol/L) despite ethnic differences in
MTHFR
genotype and baseline folic acid (FA) and vitamin B
12
(vitB
12
) concentrations.

Conclusions—

Ethnicity does not appear to affect the tHcy-lowering effect of B-vitamins, despite differences in dietary intake and prevalence of
MTHFR
polymorphisms. This suggests that the effect of B-vitamins in lowering tHcy is generalizable across Asian populations. However, due to relatively small numbers of non-Chinese studied, confirmation in other populations is required.
Oxidative-Nitrosative Stress in a Rabbit Pup Model of Germinal Matrix Hemorrhage
Authors: Zia Muhammad T. , Csiszar Anna , Labinskyy Nazar , Hu Furong , Vinukonda Govindaiah , LaGamma Edmund F. , Ungvari Zoltan , Ballabh Praveen
Published: April 2009

Background and Purpose—

Germinal matrix hemorrhage-intraventricular hemorrhage is the most common neurological problem of premature infants. Despite this, mechanisms of brain injury from intraventricular hemorrhage are elusive. We hypothesized that germinal matrix hemorrhage-intraventricular hemorrhage, by induction of NAD(P)H oxidases, might cause oxidative/nitrosative stress contributing to brain injuries and that NAD(P)H oxidase inhibition could offer neuroprotection.

Methods—

To test this hypothesis, we exploited our rabbit pup model of glycerol-induced germinal matrix hemorrhage-intraventricular hemorrhage. We delivered rabbit pups prematurely (E29) by cesarean section and administered intraperitoneal glycerol at 2 hours postnatal age. Free-radical adducts, including nitrotyrosine, 4-hyroxynonenal, and 8-hydroxy-deoxyguanosine as well as O
2
.−
and H
2
O
2
levels were measured in the forebrain. To determine the source of free-radical generation, we used inhibitors for NAD(P)H oxidase (apocynin), xanthine oxidase (allopurinol), cyclo-oxygenase-2 (indomethacin), or nitric oxide synthases (L-NAME). Intraventricular hemorrhage pups were treated with apocynin and cell death was compared between apocynin-treated and vehicle-treated pups.

Results—

Nitrotyrosine, 4-hyroxynonenal, and 8-hydroxy-deoxyguanosine levels were higher in pups with intraventricular hemorrhage than controls. Likewise, O
2
.−
and H
2
O
2
levels were significantly greater in both the periventricular area and cerebral cortex of pups with intraventricular hemorrhage than controls. In pups with intraventricular hemorrhage, reactive oxygen species production was more in the periventricular area than in the cortex. Apocynin, but not allopurinol, indomethacin, or nitric oxide synthases, inhibited reactive oxygen species generation. Importantly, apocynin reduced cell death in pups with intraventricular hemorrhage.

Conclusion—

Activation of NAD(P)H oxidase was the predominant mechanism of free-radical generation in pups with intraventricular hemorrhage. NAD(P)H oxidase inhibition by apocynin might suppress reactive oxygen species production and confer neuroprotection in premature infants with intraventricular hemorrhage.
Stroke Presentation and Hospital Management
Authors: Crawford Vivienne L.S. , Dinsmore John G. , Stout Robert W. , Donnellan Claire , O'Neill Desmond , McGee Hannah
Published: April 2009

Background and Purpose—

Acute stroke care is shaped by healthcare policies. Differing policies in similar populations allow for assessment of policy impact on health and healthcare outcomes. The purpose of this study was to compare stroke presentation and hospital care in two adjacent healthcare systems with differing healthcare policies.

Methods—

Interviews and chart review of consecutive acute stroke admissions in Northern Ireland (n=103) and the Republic of Ireland (n=100).

Results—

Marked regional contrasts were evident for key aspects of hospital care. Northern Ireland performed significantly better on 15 of 16 quality of care (Sentinel Audit) items. Delivery on standards was significantly better in Northern Ireland for early assessment (Northern Ireland 72%; Republic of Ireland 54%,
P
<0.01), multidisciplinary review (Northern Ireland 69%; Republic of Ireland 31%,
P
<0.001), medications review (Northern Ireland 54%; Republic of Ireland 19%,
P
<0.001), and for discharge-rehabilitation planning (Northern Ireland 83%; Republic of Ireland 8%,
P
<0.001). Preadmission prescription of advised cardiovascular medications was similar between regions for antihypertensives and anticoagulants but significantly higher in Northern Ireland for antiplatelets (Northern Ireland 65%; Republic of Ireland 38%,
P
=0.001) and lipid-regulating medication (Northern Ireland 44%; Republic of Ireland 26%;
P
=0.006). Prescribing levels increased in both regions and all medication categories by discharge but with significantly lower levels in Northern Ireland for antihypertensives (Northern Ireland 60%; Republic of Ireland 75%,
P
=0.025). Northern Ireland patients were more functionally dependent (mean Barthel Index 10.5 versus 12.7 [Republic of Ireland],
P
=0.013) and less aphasic (mean Frenchay Aphasia Screening Test 17.8 versus 16.8 [Republic of Ireland],
P
=0.022).

Conclusions—

In similar neighboring acute stroke populations, differing healthcare policies were associated with significant differences in processes of patient care. Policy reform is an important tool in ensuring optimal stroke care delivery.
Effect Sizes in Gifted Education Research
Authors: Gentry Marcia , Peters Scott J.
Published: April 2009

Recent calls for reporting and interpreting effect sizes have been numerous, with the 5th edition of the Publication Manual of the American Psychological Association (2001) calling for the inclusion of effect sizes to interpret quantitative findings. Many top journals have required that effect sizes accompany claims of statistical significance. However, too often reports of data analyses in gifted education rely on statistical significance without reporting effect size indices to help interpret quantitative findings. Without a supporting effect size index, erroneous interpretation of results can occur. This Methodological Brief addresses this concern and provides examples and guidance concerning using effect sizes in gifted education quantitative research.
At the Critical Moment: Conditions and Prospects for Critical Management Studies
Authors: Fournier Valerie , Grey Chris
Published: April 2009

We have recently witnessed a growing, if still arguably marginal, interest in `Critical Management Studies' (CMS). Our aim in this paper is to reflect upon the popularization of CMS; more specifically, we propose to examine the various factors that have contributed to its emergence, and to review the significance of its project. We start by exploring the conditions of possibility for CMS and point to a combination of political, institutional and epistemological trends. In the second part of the paper, we consider what constitutes `CMS' and suggest that whilst it draws upon a plurality of intellectual traditions, CMS is unified by an anti performative stance, and a commitment to (some form of) denaturalization and reflexivity. Finally, we articulate the polemics around which CMS politics have been contested, in particular we review the debates between neo-Marxism and post-structuralism, and discuss the issue of engagement with management practice.
The Meaning Professionals Give to Management... and Strategy
Authors: McAuley John , Duberley Joanne , Cohen Laurie
Published: April 2009

The relationship between professionals and the organizations in which they work has been seen over the years as problematic. There is literature which suggests that the type of organization in which they work and are allowed to flourish is the quintessential form of organization for our times. There is also literature which suggests that professionals are reluctant, idiosyncratic members of the organizations in which they work, related to this perspective, there is literature which suggests that they are essentially placed in reactive mode as they are exposed to the cut and thrust of management agendas that are designed to control their activities. In all these strands of literature, there is a strong suggestion that professionals take little interest in the activity known as managing. This paper is primarily concerned to explore the issues that confront one particular group of professionals - research scientists who work in the public sector-as they experience a particular approach to management known as managerialism. We have taken this phenomenon as an extension of the modernist project which has as its heart the transcendence of professional management as a means of achieving control in organizations. This is seen to be a matter of general application in professional organizations. Taking findings from qualitative research in two laboratories we have used the promotion of the managerialist agenda as an opportunity to examine scientists' understandings of the nature of strategy and management, and consider what they understand to be the nature of competent management. It is our finding that these professionals display a lively and sometimes critical understanding of the issues involved in management, and that on occasion they will adapt and absorb `new' approaches to management in order to progress their professional work, they articulate a number of lay discourses that capture, at least to their own satisfaction, the essence of management. It is our belief that this paper will be of interest at two levels. At a specific level, little appears to exist with regard to understanding of the management of research scientists working in the public sector environment. At the more general level, although there has been a great deal of debate regarding the management of professionals, there has been little substantive research into the ways in which professionals locate management into their understanding of the world. This study whilst illuminating the understandings of management of one group of people also illuminates the lives of professionals working in organizations as they are exposed to new approaches to management.