bluuebunny/crossref_metadata_2025 huggingface dataset:
Directionally Independent Failure Prediction of End-Milling Tools During Pocketing Maneuvers
Authors: Suprock Christopher A. , Piazza Joseph J. , Roth John T.
Published: August 2007

Tracking the health of cutting tools under typical wear conditions is advantageous to the speed and efficiency of manufacturing processes. Existing techniques monitor tool performance through analyzing force or acceleration signals whereby prognoses are made from a single sensor type. This work proposes to enhance the spectral output of autoregressive (AR) models by combining triaxial accelerometer and triaxial dynamometer signals. Through parallel processing of force and acceleration signals using single six degree of freedom modeling, greater spectral resolution is achieved. Two entirely independent methods of tracking the tool wear are developed and contrasted. First, using the discrete cosine transform, primary component analysis will be applied to the spectral output of each AR auto and cross spectrum (Method 1). Each discrete cosine transform of the six-dimensional spectral data is analyzed to determine the magnitude of the critical (primary) variance energy component of the respective spectrum. The eigenvalues of these selected spectral energies are then observed for trends toward failure. The second method involves monitoring the eigenvalues of the spectral matrices centered at the toothpass frequency (Method 2). The results of the two methodologies are compared. Through the use of the eigenvalue method, it is shown that, for straight and pocketing maneuvers, both methods successfully track the condition of the tool using statistical thresholding. The techniques developed in this work are shown to be robust by multiple life tests conducted on different machine platforms with different operating conditions. Both techniques successfully identify impending fracture or meltdown due to wear, providing sufficient time to remove the tools before failure is realized.
Finite Element Modeling of Hard Roller Burnishing: An Analysis on the Effects of Process Parameters Upon Surface Finish and Residual Stresses
Authors: Sartkulvanich Partchapol , Altan Taylan , Jasso Francisco , Rodriguez Ciro
Published: August 2007

Hard roller burnishing is a cost-effective finishing and surface enhancement process where a ceramic ball rolls on the machined surface to flatten the roughness peaks. The ball is supported and lubricated by hydrostatic fluid in a special tool holder. The process not only improves surface finish but also imposes favorable compressive residual stresses in functional surfaces, which can lead to long fatigue life. Most research in the past focused on experimental studies. There is still a special need for a reliable finite element method (FEM) model that provides a fundamental understanding of the process mechanics. In this study, two-dimensional (2D) and three-dimensional FEM models for hard roller burnishing were established. The developed 2D FEM model was used to study the effects of process parameters (i.e., burnishing pressure, feed rate) on surface finish and residual stresses. The simulation results were evaluated and compared to the experimental data. Results show that the established FEM model could predict the residual stresses and provided useful information for the effect of process parameters. Both FEM and experiments show that burnishing pressure is the most influence, where high burnishing pressure produces less roughness and more compressive residual stress at the surface.
Two Efficient Algorithms of Plastic Integration for Sheet Forming Modeling
Authors: Li Y. M. , Abbès B. , Guo Y. Q.
Published: August 2007

A fast method called the “inverse approach” for sheet forming modeling is based on the assumptions of the proportional loading and simplified tool actions. To improve the stress estimation, the pseudo-inverse approach was recently developed: some realistic intermediate configurations are geometrically determined to consider the deformation paths; two new efficient algorithms of plastic integration are proposed to consider the loading history. In the direct scalar algorithm (DSA), an elastic unloading-reloading factor γ is introduced to deal with the bending-unbending effects; the equation in unknown stress vectors is transformed into a scalar equation using the notion of the equivalent stress, thus the plastic multiplier Δλ can be directly obtained without iterative resolution scheme. In the γ-return mapping algorithm, the equivalent plastic strain increment estimated by DSA is taken as the initial solution in Simo’s return mapping algorithm, leading to a stable, efficient, and accurate plastic integration scheme. The numerical experience has shown that these two algorithms give a considerable reduction of CPU time in the plastic integration.
A Water Evaporation Based Model for Lubricant Dryoff on Die Surfaces Heated Beyond the Leidenfrost Point
Authors: Yang Lin , Shivpuri Rajiv
Published: August 2007

Lubricants in hot forging are applied to the heated die surface by spraying dilute water based graphite suspensions through high-pressure nozzles. To avoid undesirable steam formation, these lubricant droplets need to completely dry before deformation begins. This paper presents an analytical model to estimate evaporation time for the impacting drops at surface temperatures above Leidenfrost, 300–450°C. It is based on the suspension of deformed droplet on a vapor cushion sustained by a continuous supply of water from the drying droplet. Model predictions are validated by single droplet experiments with different surface temperatures, dilution ratios, and impacting speeds.
Determination of Cavity Detachment for Sheet Cavitation
Authors: Amromin Eduard
Published: August 2007

Sheet cavitation has been traditionally analyzed with ideal fluid theory that employs the cavitation number as the single parameter. However, characteristics of cavitation can significantly depend on location of cavity detachment. According to known experimental data, this location is influenced by the freestream speed and the body/hydrofoil size. As shown in this paper, it takes place because of the combined effect of the Reynolds number and Weber number. Here, sheet cavitation is considered as a special kind of viscous separation caused by the cavity itself. The viscous-inviscid interaction concept is employed to analyze the entire flow. Validation of the suggested approach is provided for hydrofoils and bodies of revolution. The effects of flow speed, the body size, and its surface wettability are illustrated by comparison of computed cavity length/shape to the known experimental data. The difference between cavity detachment in laminar and turbulent boundary layers is discussed.
Robust Implicit Multigrid Reynolds-Stress Model Computation of 3D Turbomachinery Flows
Authors: Gerolymos G. A. , Vallet I.
Published: August 2007

The purpose of this paper is to present a numerical methodology for the computation of complex 3D turbomachinery flows using advanced multiequation turbulence closures, including full seven-equation Reynolds-stress transport models. The flow equations are discretized on structured multiblock grids, using an upwind biased (O[ΔxH3]MUSCL reconstruction) finite-volume scheme. Time integration uses a local dual-time-stepping implicit procedure, with internal subiterations. Computational efficiency is achieved by a specific approximate factorization of the implicit subiterations, designed to minimize the computational cost of the turbulence transport equations. Convergence is still accelerated using a mean-flow-multigrid full-approximation-scheme method, where multigrid is applied only on the mean-flow variables. Speed-ups of a factor 3 are obtained using three levels of multigrid (fine plus two coarser grids). Computational examples are presented using two Reynolds-stress models, and also a baseline k−ε model, for various turbomachinery configurations, and compared to available experimental measurements.
Hydraulic Turbine Diffuser Shape Optimization by Multiple Surrogate Model Approximations of Pareto Fronts
Authors: Daniel Marjavaara B. , Staffan Lundström T. , Goel Tushar , Mack Yolanda , Shyy Wei
Published: August 2007

A multiple surrogate-based optimization strategy in conjunction with an evolutionary algorithm has been employed to optimize the shape of a simplified hydraulic turbine diffuser utilizing three-dimensional Reynolds-averaged Navier–Stokes computational fluid dynamics solutions. Specifically, the diffuser performance is optimized by changing five geometric design variables to maximize the average pressure recovery factor for two inlet boundary conditions with different swirl, corresponding to different operating modes of the hydraulic turbine. Polynomial response surfaces and radial basis neural networks are used as surrogates, while a hybrid formulation of the NSGA-IIa evolutionary algorithm and a ϵ-constraint strategy is applied to construct the Pareto front from the two surrogates. The proposed optimization framework drastically reduces the computational load of the problem, compared to solely utilizing an evolutionary algorithm. For the present problem, the radial basis neural networks are more accurate near the Pareto front while the response surface performs better in regions away from it. By using a local resampling updating scheme the fidelity of both surrogates is improved, especially near the Pareto front. The optimal design yields larger wall angles, nonaxisymmetrical shapes, and delay in wall separation, resulting in 14.4% and 8.9% improvement, respectively, for the two inlet boundary conditions.
Crystal Structure of an Ancient Protein: Evolution by Conformational Epistasis
Authors: Ortlund Eric A. , Bridgham Jamie T. , Redinbo Matthew R. , Thornton Joseph W.
Published: August 2007

The structural mechanisms by which proteins have evolved new functions are known only indirectly. We report x-ray crystal structures of a resurrected ancestral protein—the ∼450 million-year-old precursor of vertebrate glucocorticoid (GR) and mineralocorticoid (MR) receptors. Using structural, phylogenetic, and functional analysis, we identify the specific set of historical mutations that recapitulate the evolution of GR's hormone specificity from an MR-like ancestor. These substitutions repositioned crucial residues to create new receptor-ligand and intraprotein contacts. Strong epistatic interactions occur because one substitution changes the conformational position of another site. “Permissive” mutations—substitutions of no immediate consequence, which stabilize specific elements of the protein and allow it to tolerate subsequent function-switching changes—played a major role in determining GR's evolutionary trajectory.
Tales of the Wonder Drug
Authors: Rasmussen Nicolas
Published: August 2007

Penicillin
. Triumph and Tragedy.
By Robert Bud
. Oxford University Press, Oxford, 2007. 340 pp. $55, £30. ISBN 9780199254064.

The author considers the discovery and deployment of penicillin (and related antibiotics) in the context of cultural and social changes over the second half of the 20th century.
Prospective Study To Determine Accuracy of Rapid Serological Assays for Diagnosis of Acute Dengue Virus Infection in Laos
Authors: Blacksell Stuart D. , Bell David , Kelley James , Mammen Mammen P. , Gibbons Robert V. , Jarman Richard G. , Vaughn David W. , Jenjaroen Kemajittra , Nisalak Ananda , Thongpaseuth Soulignasack , Vongsouvath Manivanh , Davong Viengmone , Phouminh Phonelavanh , Phetsouvanh Rattanaphone , Day Nicholas P. J. , Newton Paul N.
Published: August 2007

There is an urgent need for accurate and simple dengue virus infection diagnostic assays in limited-resource settings of dengue endemicity, to assist patient management. Using a panel of reference samples (S. D. Blacksell, P. N. Newton, D. Bell, J. Kelley, M. P. Mammen, D. W. Vaughn, V. Wuthiekanun, A. Sungkakum, A. Nisalak, and N. P. Day, Clin. Infect. Dis. 42:1127-1134, 2006), we recently evaluated eihgt commercially available immunochromatographic rapid diagnostic tests (RDTs) designed to detect dengue virus-specific immunoglobulin M (IgM) and/or IgG. We found that 6/8 RDTs had sensitivities of less than 50% (range, 6 to 65%), but specificities were generally high. Here, in conjuction with dengue virus serotyping by reverse transcriptase PCR and in the limited-resource setting of Laos, where dengue virus is endemic, we evaluated the same eight RDTs against a previously validated dengue IgM/IgG enzyme-linked immunosorbent assay for diagnosis of acute dengue virus infection. Paired serum samples were collected from 87 patients, of whom 38 had confirmed dengue virus infections (4 had primary infections, 33 had secondary infections, and 1 had an infection of indeterminate status). RDT sensitivity was low, with 7/8 RDTs having admission sample sensitivities of less than 20% (range, 4 to 26%). The majority (6/8) of the RDTs, demonstrated high specificity (>95%). Kappa statistic values ranged from 6 to 54% for the RDTs, demonstrating poor to moderate variation between three operators. No RDT adequately differentiated between primary and secondary dengue virus infections. The findings of this study suggest that currently available RDTs based on the detection of IgM antibodies for the diagnosis of acute dengue virus infections are unlikely to be useful for patient management.
Histatin 5 Initiates Osmotic Stress Response in
Candida albicans
via Activation of the Hog1 Mitogen-Activated Protein Kinase Pathway
Authors: Vylkova Slavena , Jang Woong Sik , Li Wansheng , Nayyar Namrata , Edgerton Mira
Published: August 2007

Histatin 5 (Hst 5) is a salivary cationic peptide that has toxicity for
Candida albicans
by inducing rapid cellular ion imbalance and cell volume loss. Microarray analyses of peptide-treated cells were used to evaluate global gene responses elicited by Hst 5. The major transcriptional response of
C. albicans
to Hst 5 was expression of genes involved in adaptation to osmotic stress, including production of glycerol (
RHR2
,
SKO1
, and
PDC11
) and the general stress response (
CTA1
and
HSP70
). The oxidative-stress genes
AHP1
,
TRX1
, and
GPX1
were mildly induced by Hst 5. Cell defense against Hst 5 was dependent on the Hog1 mitogen-activated protein kinase (MAPK) pathway, since
C. albicans hog1/hog1
mutants were significantly hypersensitive to Hst 5 but not to Mkc1 MAPK or Cek1 MAPK mutants. Activation of the high-osmolarity glycerol (HOG) pathway was demonstrated by phosphorylation of Hog1 MAPK as well as by glycerol production following Hst 5 treatment in a dose-dependent manner.
C. albicans
cells prestressed with sorbitol were less sensitive to subsequent Hst 5 treatment; however, cells treated concurrently with osmotic stress and Hst 5 were hypersensitive to Hst 5. In contrast, cells subjected to oxidative stress had no difference in sensitivity to Hst 5. These results suggest a common underlying cellular response to osmotic stress and Hst 5. The HOG stress response pathway likely represents a significant and effective challenge to physiological levels of Hst 5 and other toxic peptides in fungal cells.
Regulatory T-Cell Markers, Indoleamine 2,3-Dioxygenase, and Virus Levels in Spleen and Gut during Progressive Simian Immunodeficiency Virus Infection
Authors: Boasso Adriano , Vaccari Monica , Hryniewicz Anna , Fuchs Dietmar , Nacsa Janos , Cecchinato Valentina , Andersson Jan , Franchini Genoveffa , Shearer Gene M. , Chougnet Claire
Published: August 2007

High levels of viral replication occur in gut-associated lymphoid tissue (GALT) and other lymphoid tissues (LT) since the early phase of human/simian immunodeficiency virus (HIV/SIV) infection. Regulatory T cells (T
reg
), a subset of immunosuppressive T cells expressing CTLA-4 and the FoxP3 transcription factor, accumulate in LT during HIV/SIV infection. Here we show that FoxP3 and CTLA-4 mRNA are increased in leukocytes from the spleens, lymph nodes (LN), and mucosal sites of chronically SIV-infected macaques with high viremia (SIV
HI
) compared to animals with low viremia (SIV
LO
). FoxP3 and CTLA-4 correlated with SIV RNA levels in tissues; SIV virus levels in the spleen, inguinal LN, mesenteric LN, colon, and jejunum directly correlated with the plasma virus level. Importantly, CTLA-4 and FoxP3 mRNA were predominantly increased in the CD25
−
subpopulation of leukocytes from SIV
HI
, further challenging the classical definition of T
reg
as CD4
+
CD25
+
T cells. Similar to CTLA-4 and FoxP3, expression of indoleamine 2,3-dioxygenase (IDO), an immunosuppressive enzyme induced by T
reg
in antigen-presenting cells, was increased in the spleens, mesenteric LN, colons, and jejuna from SIV
HI
compared to SIV
LO
and directly correlated to SIV RNA in the same tissues. Accordingly, plasma kynurenine/tryptophan, a marker for IDO enzymatic activity, was significantly higher in SIV
HI
compared to SIV
LO
and correlated with plasma viral levels. Increased T
reg
and IDO in LT of SIV-infected macaques may be the consequence of increased tissue inflammation and/or may favor virus replication during the chronic phase of SIV infection.
The Efficacy of Chinese Medicine for SARS: A Review of Chinese Publications After the Crisis
Authors: Leung Ping-Chung
Published: August 2007

During the SARS crisis in China, 40–60% infected patients, at some stages of their treatment, received Chinese medicine treatment on top of the standard modern medicine treatment. This practice was endorsed and encouraged by the Chinese Center for Disease Control and Prevention, and some details of the herbal treatment were recommended. A review of the publications during and after the SARS crisis enabled us to get an objective view of the true value of the adjuvant therapy using Chinese medicinal herbs. Of the 130 articles searched, 90 were of reasonable quality and contained sufficient information for the enlightenment of the situation. These were reviewed. The results revealed positive but inconclusive indications about the efficacy of the combined treatments using Chinese medicine as an adjuvant. Positive effects using adjuvant herbal therapy included better control of fever, quicker clearance of chest infection, lesser consumption of steroids and other symptoms relief. In a few reports, some evidences of immunological boosterings were also found. More caution is required on the allegation about the efficacy of herbal medicine for the treatment or prevention of viral infection affecting the respiratory tract, while more clinical studies are indicated.
Relationship between Iris Constitution Analysis and TNF-Alpha Gene Polymorphism in Hypertensives
Authors: Yoo Chun-Sang , Hwang Woo-Jun , Hong Seung-Heon , Lee Hye-Jung , Jeong Hyun-Ja , Kim Su-Jin , Kim Hyung-Min , Um Jae-Young
Published: August 2007

Iridology is a complementary and alternative medicine that involves the diagnosis of medical conditions by noting irregularities of the pigmentation in the iris. Iris constitution has a strong hereditary component. Tumor necrosis factor-alpha (TNFα), a pleiotropic cytokine, has been implicated in many pathological processes including hypertension. In this paper, the relationship between iris constitution and TNFα gene polymorphism in those with hypertension is investigated. Eighty seven hypertensive individuals and 79 controls were classified according to iris constitution and the TNFα genotype of each individual determined. Compared to the controls, the frequency of the TNFα GA heterozygote was lower in the hypertensive group, although the statistical significance was marginal (p = 0.08). This result implies an association with resistance to the disease. In addition, the frequency of the cardio-renal connective tissue weakness type was significantly higher in the hypertensive group with the TNFα GG genotype, as compared to the controls (p = 0.001). An association is demonstrated among TNFα gene polymorphism, Koreans with hypertension, and iris constitution.
Ginkgo bilobaExtract Prevents Ethanol Induced Dyslipidemia
Authors: Yao Ping , Song Fangfang , Li Ke , Zhou Shaoliang , Liu Shuang , Sun Xiufa , Nussler Andreas K. , Liu Liegang
Published: August 2007

Ginkgo biloba extract (EGB) functions as a natural substantial antioxidant and hypolipidemic. Chronic alcohol abuse leads to sustained dyslipidemia characterized by hyperlipidemia and lipid peroxidation. Thus, the present study investigates the effect of EGB on lipid disorders induced by ethanol in rats. Male Sprague-Dawley rats were fed with ethanol (2.4 g/kg), and pretreated with a daily dose of low or high EGB (48 or 96 mg/kg, respectively). During the experiment, serum was collected on day 30, 60, and 90. Serum lipid profile, including lipid peroxidation, was determined by colorimetric methods. Our data showed that ethanol intake resulted in a time-dependent increase in serum levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and malondialdehyde (MDA), and a decrease of the ratio of high-density lipoprotein cholesterol (HDL-C) against TC. EGB prophylactic medication (48 and 96 mg/kg), especially at the high dose, significantly increased HDL-C content, and normalized the abnormal lipid profile and peroxidation in comparison to ethanol-fed only rats. These results suggest that ethanol results in time-dependent hypercholesterolemia, hypertriglyceridemia and promotes serum lipid peroxidation. EGB pretreatment prevents hyperlipidemia and ameliorates lipid peroxidation induced by ethanol.
Protective Effect of Pharmacological Preconditioning of Total Flavones of Abelmoschl Manihot on Cerebral Ischemic Reperfusion Injury in Rats
Authors: Wen Ji-Yue , Chen Zhi-Wu
Published: August 2007

The present study was to investigate the effect of pharmacological preconditioning of total flavones of Abelmoschl Manihot (TFA) on cerebral ischemic reperfusion injury in rats. Rat cerebral ischemia/reperfusion injury was induced by occluding the right middle cerebral artery (MCA). The infarct size was determined by staining with 2,3,5-triphenyl tetrazalium chloride (TTC). The serum malonaldehyde (MDA), nitric oxide (NO) and lactate dehydrogenase (LDH) levels were measured by using spectrophotometry; Inducible NO synthase (iNOS) mRNA expression was detected by RT-PCR method. The percentage of cerebral infarction volume was 28.1 ± 0.8 in the model group, while TFA or nimodipine (Nim) pretreatment 36 hours prior to the ischemic insult significantly decreased the infarction volume. Increases of serum LDH activity and MDA level were observed after ischemia/reperfusion, but these changes were inhibited in rats pretreated with either TFA (20, 40, 80, 160 mg/kg) or Nim, indicating a delayed protective effect of TFA preconditioning on cerebral ischemic reperfusion injury. In addition, the serum NO level and the cerebral iNOS mRNA were up-regulated, suggesting a possible mechanism for the protective effect of TFA pretreatment on cerebral ischemic reperfusion injury.
Pharmacological Studies on Anti-Hyperglycemic Effect of Folium Eriobotryae
Authors: Li Wei-Lin , Wu Ju-Lan , Ren Bing-Ru , Chen Jian , Lu Chang-Gen
Published: August 2007

Folium Eriobotryae, dried leaves of Eriobotrya japonica (Thunb.) Lindl. is a traditional Chinese medicine with rich resources in China. This research investigated the anti-hyperglycemic effect of Folium Eriobotryae on normal and alloxan-diabetic mice. The 70% ethanol extract of Folium Eriobotryae (EJA-0) in doses of 15, 30 and 60 g (crude drug)/kg exerted a significant hypoglycemic effect on alloxan-diabetic mice, among which 30 g/kg of EJA-0 was more effective than 100 mg/kg of phenformin. The total sesquiterpenes (EJA-1) 30 g (crude drug)/kg had significant effect on lowering blood glucose level in normal or/and alloxan-diabetic mice. The tests of maximum dosage and acute toxicity showed that EJA-1 was safe (MD = 360 g/kg, LD50 = 400.1 g/kg). The pharmacological tests on anti-hyperglycemic effects of EJA-0 and EJA-1 prove that Folium Eriobotryae is an outstanding material to develop medicine for treatment of diabetes mellitus.
SYNTHESIS AND CHARACTERIZATION OF FeRh NANOPARTICLES
Authors: CIUCULESCU DIANA , AMIENS CATHERINE , RESPAUD MARC , LECANTE PIERRE , FALQUI ANDREA , CHAUDRET BRUNO
Published: August 2007

Fe 0.8 Rh 0.2 nanoparticles with an average size of 1.8 nm have been synthesized by simultaneous decomposition of stoichiometric quantities of Fe[N(Si(CH 3)3)2]2 and Rh(C 3 H 5)3 in mild conditions of temperature and hydrogen pressure, using hexadecylamine as stabilizer. These nanoparticles display a magnetization of 1.13 μ B per iron atom, which is more than two times smaller than the bulk value with the same composition. No surface contamination with iron oxides was detected by Mössbauer spectroscopy. Superconducting quantum interference device and Mössbauer spectroscopy investigations reveal that the origin of this variation may be a core-shell Rh/Fe chemical arrangement.
EFFECT OF AIR EXPOSURE ON STRUCTURAL AND MAGNETIC FEATURES OF FeCo NANOPARTICLES
Authors: MOURDIKOUDIS S. , SIMEONIDIS K. , ANGELAKERIS M. , TSIAOUSSIS I. , KALOGIROU O. , DESVAUX C. , AMIENS C. , CHAUDRET B.
Published: August 2007

Monodisperse FeCo nanoparticles were synthesized via thermal decomposition of appropriate organometallic complexes in heated toluene containing surfactants, aiming to a soft magnetic nanomaterial with a high metal percent. The particles were characterized by X-ray powder diffraction, electron microscopy, and static magnetometry techniques. The effect of air exposure on the structural and magnetic properties was examined. Portions of the dried nanoparticles were mixed with additional surfactants or polyvinylpyrrolidone, followed by redispersion into tetrahydrofuran, so as to study arrangement features in the first case, while the use of polyvinylpyrrolidone intended to the expansion of the interparticle distances in order to get more "isolated" nanoparticles.
MAGNETIC CORE SHELL NANOPARTICLES CHARACTERIZED BY X-RAY ABSORPTION AND MAGNETIC CIRCULAR DICHROISM
Authors: FAUTH KAI
Published: August 2007

X-ray absorption spectroscopy is a powerful spectroscopic tool in analytical nanoscience. Its application to nanoparticles with core shell geometry requires careful consideration, in particular when quantitative evaluations are attempted. The present article shows that well chosen experimental conditions, supported by Monte Carlo simulations of X-ray absorption allow a detailed analysis of experimental data and provide valuable insight into magnetic properties of transition metal and alloy nanoparticles.
ANNEALING EFFECT ON THE INDUCED MAGNETISM OF PLATINUM IN FePt NANOPARTICLES
Authors: WILHELM F. , ROGALEV A. , POULOPOULOS P. , ANGELAKERIS M. , TSIAOUSSIS J. , SIMEONIDIS K. , MOURDIKOUDIS S. , KALOGIROU O.
Published: August 2007

Effect of annealing on structural and magnetic properties of non-equatomic chemically synthesized FePt nanoparticles with an average size of 3.2 nm diameter is reported. Annealing of the particles at 700°C resulted in the increase of particles size and the enhancement of total magnetization and coercivity, the latter could be attributed to a transformation from disordered to ordered crystallographic phase. Although the system is far from optimum "equatomic" stoichiometry, coercivity field of 1.1 kOe was obtained at 10 K together with remanence ratio of 0.55. X-ray magnetic circular dichroism spectra recorded at the Pt L 2,3 edges on annealed samples revealed the enhancement of magnetic moment induced on Pt atom.
FMR IN NANOSYSTEMS — DISCONTINUOUS MULTILAYERS Fe/SiO2/Fe
Authors: MAJCHRÁK P. , VÁVRA I. , LOBOTKA P. , DÉRER J. , FRAIT Z. , HORVÁTH D.
Published: August 2007

We present the study on the interlayer and intergranular exchange and dipolar coupling in [Fe 97 Si 3/ SiO 2]5 discontinuous multilayers by means of ferromagnetic resonance. Due to strong ferromagnetic exchange coupling (J~-3 erg/cm 2) the precessional motions of magnetic moments of granules are coupled and results in an acoustic and optical mode. Moreover there is notable line splitting in optical mode under external field normal to the layer, which is explained by an interlayer dipolar coupling, only possible for discontinuous layer. Some aspects of the damping processes in discontinuous multilayers are discussed as well.
COPULAS WITH GIVEN DIAGONAL SECTIONS: NOVEL CONSTRUCTIONS AND APPLICATIONS
Authors: DURANTE FABRIZIO , KOLESÁROVÁ ANNA , MESIAR RADKO , SEMPI CARLO
Published: August 2007

In this paper, we present some methods for constructing copulas with a given diagonal section that are not necessarily symmetric. An interesting application for the construction of copulas with given tail dependence coefficients is, hence, provided.
A MODIFICATION OF THE INDEX OF LIOU AND WANG FOR RANKING FUZZY NUMBER
Authors: SOCORRO GARCIA M. , TERESA LAMATA M.
Published: August 2007

Different methods have been proposed for ranking fuzzy numbers. These include methods based on distances, centroid point, coefficient of variation, and weighted mean value. However, there is still no method that can always give a satisfactory result to every situation; some are counterintuitive and not discriminating. This paper presents an approach for ranking fuzzy numbers with integral value that is an extension of the index of Liou and Wang. This method, that is independent of the type of membership function used, can rank more than two fuzzy numbers simultaneously. This ranking method use an index of optimism to reflect the decision maker's optimistic attitude, but rather it also contains an index of modality that represents the neutrality of the decision maker. The approach is illustrated with numerical examples.
STOCHASTIC STABILITY OF NON-UNIFORMLY HYPERBOLIC DIFFEOMORPHISMS
Authors: ALVES JOSÉ F. , ARAÚJO VÍTOR , VÁSQUEZ CARLOS H.
Published: August 2007

We prove that the statistical properties of random perturbations of a diffeomorphism with dominated splitting having mostly contracting center-stable direction and non-uniformly expanding center-unstable direction are described by a finite number of stationary measures. We also give necessary and sufficient conditions for the stochastic stability of such dynamical systems. We show that a certain C2-open class of non-uniformly hyperbolic diffeomorphisms introduced by Alves, Bonatti and Viana in [2] are stochastically stable.
A NEW PROOF OF NONEXISTENCE OF PROBABILISTIC QUANTUM CLONING MACHINE
Authors: KUNKRI SAMIR , CHOUDHARY SUJIT K.
Published: August 2007

We give a simple proof of the impossibility of probabilistic exact 1 → 2 cloning for any three different states of a qubit. The simplicity of the proof is due to the use of a stronger version of no violation of the causality principle. The proof is also extended to higher-dimensional Hilbert space, but for a special ensemble of states.
Gene Flow and Local Adaptation in Trees
Authors: Savolainen Outi , Pyhäjärvi Tanja , Knürr Timo
Published: August 2007

Populations are locally adapted when populations have the highest relative fitness at their home sites, and lower fitness in other parts of the range. Results from the extensive experimental plantations of populations of forest trees from different parts of the range show that populations can survive and grow in broad areas outside the home site. However, intra- and interspecific competition limit the distribution of genotypes. For populations from large parts of the range, relative fitness, compared with the local population, is often highest at the home site. At the edges of the range, this local adaptation may break down. The extent of local adaptation is determined by the balance between gene flow and selection. Genetic differentiation and strong natural selection occur over a range of tens or hundreds of kilometers, but reliable measurements of gene flow are available only for much shorter distances. Current models of spatially varying selection could be made more realistic by the incorporation of strong selection and isolation-by-distance characteristic of tree populations. Many studies suggest that most variation in adaptive traits is based on loci with small effects. Association genetics methods and improved genomic resources are useful for the identification of the loci responsible for this variation. The potential for adaptation to current climate change depends on genetic variation and dispersal and establishment rates.
Visual Perception and the Statistical Properties of Natural Scenes
Authors: Geisler Wilson S.
Published: August 2007

The environments in which we live and the tasks we must perform to survive and reproduce have shaped the design of our perceptual systems through evolution and experience. Therefore, direct measurement of the statistical regularities in natural environments (scenes) has great potential value for advancing our understanding of visual perception. This review begins with a general discussion of the natural scene statistics approach, of the different kinds of statistics that can be measured, and of some existing measurement techniques. This is followed by a summary of the natural scene statistics measured over the past 20 years. Finally, there is a summary of the hypotheses, models, and experiments that have emerged from the analysis of natural scene statistics.
The cardioprotection of the late phase of ischemic preconditioning is enhanced by postconditioning via a COX-2-mediated mechanism in conscious rats
Authors: Sato Hiroshi , Bolli Roberto , Rokosh Gregg D. , Bi Qiuli , Dai Shujing , Shirk Gregg , Tang Xian-Liang
Published: August 2007

The present study sought to determine whether the combination of late preconditioning (PC) with postconditioning enhances the reduction in infarct size. Chronically instrumented rats were assigned to a 45-min ( subset 1) or 60-min ( subset 2) coronary occlusion followed by 24 h of reperfusion. In each subset, rats received no further intervention (control) or were preconditioned 24 h before occlusion (PC), postconditioned at the onset of reperfusion following occlusion, or preconditioned and postconditioned without (PC + postconditioning) or with the COX-2 inhibitor celecoxib (3 mg/kg ip; PC + postconditioning + celecoxib) 10 min before postconditioning. Myocardial cyclooxygenase-2 (COX-2) protein expression and COX-2 activity (assessed as myocardial levels of PGE2) were measured 6 min after reperfusion in an additional five groups (control, PC, postconditioning, PC + postconditioning, and PC + postconditioning + celecoxib) subjected to a 45-min occlusion. PC alone reduced infarct size after a 45-min occlusion but not after a 60-min occlusion. Postconditioning alone did not reduce infarct size in either setting. However, the combination of late PC and postconditioning resulted in a robust infarct-sparing effect in both settings, suggesting additive cardioprotection. Celecoxib completely abrogated the infarct-sparing effect of the combined interventions in both settings. Late PC increased COX-2 protein expression and PGE2 content. PGE2 content (but not COX-2 protein) was further increased by the combination of both interventions, suggesting that postconditioning increases the activity of COX-2 induced by late PC. In conclusion, the combination of late PC and postconditioning produces additive protection, likely due to a postconditioning-induced enhancement of COX-2 activity.
Molecular expression of SLC4-derived Na+-dependent anion transporters in selected human tissues
Authors: Damkier Helle Hasager , Nielsen Søren , Praetorius Jeppe
Published: August 2007

NaHCO3transporters are involved in maintenance of intracellular pH and transepithelial HCO3−movement in many rodent tissues. To establish the human relevance of the many investigations on rodents, this study aimed to map these transporters and a related polypeptide, NaBC1 [solute carrier 4 (SLC4)A11], to several human tissues by using PCR on reverse transcribed human mRNA and immunoperoxidase histochemistry. The mRNA encoding the electroneutral Na+:HCO3−cotransporter (NBCe1; SLC4A4), was expressed in renal cortex, renal medulla, stomach, duodenum, jejunum, ileum, colon, pancreas, choroid plexus, cerebellum, cerebrum, and hippocampus. NBCe2 (SLC4A5) and NBCn1 (SLC4A7) mRNAs were mainly found in kidney and brain tissues, as was mRNA encoding the Na+-dependent anion exchangers NCBE (SLC4A10) and NDCBE1 (SLC4A8). In addition to previous findings, NBCn1 protein was localized to human renal medullary thick ascending limbs and duodenal epithelial villus cells and NBCe2 protein to renal collecting ducts. Finally, the message encoding NaBC1 was found in kidney, stomach, duodenum, pancreas, and brain, and the corresponding protein in the anterior and posterior corneal epithelia, renal corpuscules, proximal tubules, collecting ducts, pancreatic ducts, and the choroid plexus epithelium. In conclusion, the selected human tissues display distinct expression patterns of HCO3−transporters, which closely resemble that of rodent tissues.
Suppressing the excitability of spinal motoneurons by extracellularly applied electrical fields: insights from computer simulations
Authors: ElBasiouny Sherif M. , Mushahwar Vivian K.
Published: August 2007

The effect of extracellularly applied electrical fields on neuronal excitability and firing behavior is attributed to the interaction between neuronal morphology and the spatial distribution and level of differential polarization induced by the applied field in different elements of the neuron. The presence of voltage-gated ion channels that mediate persistent inward currents (PICs) on the dendrites of spinal motoneurons enhances the influence of electrical fields on the motoneuronal firing behavior. The goal of the present study was to investigate, with a realistic motoneuron computer model, the effects of extracellularly applied electrical fields on the excitability of spinal motoneurons with the aim of reducing the increased motoneuronal excitability after spinal cord injury (SCI). Our results suggest that electrical fields could suppress the excitability of motoneurons and reduce their firing rate significantly by modulating the magnitude of their dendritic PIC. This effect was achieved at different field directions, intensities, and polarities. The reduction in motoneuronal firing rate resulted from the reduction in the magnitude of the dendritic PIC reaching the soma by the effect of the applied electrical field. This reduction in PIC was attributed to the dendritic field-induced differential polarization and the nonlinear current-voltage relationship of the dendritic PIC-mediating channels. Because of the location of the motoneuronal somata and initial segment with respect to the dendrites, these structures were minimally polarized by the applied field compared with the extended dendrites. In conclusion, electrical fields could be used for suppressing the hyperexcitability of spinal motoneurons after SCI and reducing the level of spasticity.
α5GABAA Receptors Regulate the Intrinsic Excitability of Mouse Hippocampal Pyramidal Neurons
Authors: Bonin Robert P. , Martin Loren J. , MacDonald John F. , Orser Beverley A.
Published: August 2007

GABAA receptors generate both phasic and tonic forms of inhibition. In hippocampal pyramidal neurons, GABAA receptors that contain the α5 subunit generate a tonic inhibitory conductance. The physiological role of this tonic inhibition is uncertain, although α5GABAA receptors are known to influence hippocampal-dependent learning and memory processes. Here we provide evidence that α5GABAA receptors regulate the strength of the depolarizing stimulus that is required to generate an action potential in pyramidal neurons. Neurons from α5 knock-out (α5−/−) and wild-type (WT) mice were studied in brain slices and cell cultures using whole cell and perforated-patch-clamp techniques. Membrane resistance was 1.6-fold greater in α5−/− than in WT neurons, but the resting membrane potential and chloride equilibrium potential were similar. Membrane hyperpolarization evoked by an application of exogenous GABA was greater in WT neurons. Inhibiting the function of α5GABAA receptor with nonselective (picrotoxin) or α5 subunit-selective (L-655,708) compounds depolarized WT neurons by ∼3 mV, whereas no change was detected in α5−/− neurons. The depolarizing current required to generate an action potential was twofold greater in WT than in α5−/− neurons, whereas the slope of the input-output relationship for action potential firing was similar. We conclude that shunting inhibition mediated by α5GABAA receptors regulates the firing of action potentials and may synchronize network activity that underlies hippocampal-dependent behavior.
Providing Human Tissue for Research: 1996–2006
Authors: Womack Christopher , Gray Neil M.
Published: August 2007

This article details the authors’ experience establishing infrastructure for tissue collection, storage and distribution for biomedical research, firstly within a public healthcare service and latterly in the pharmaceutical industry. Access to human tissue in the context of public-private collaboration in research and development is essential to the provision of high-quality medicines and healthcare and is now supported by a new legal framework in England and Wales. Through collaborations there are opportunities for mutual benefit for patients and professionals alike. Attention to the wishes of tissue donors through informed consent at the outset ensured confidence and continued activity when so-called ‘organ retention scandals’ emerged midway through this period. The overwhelming majority of potential donors support the use of their tissues in biomedical research irrespective of where the research is carried out.
A Virtual Tissue Bank for Primary Central Nervous System Lymphomas in Immunocompetent Individuals
Authors: Ponzoni Maurilio , Kwee Ivo , Mazzucchelli Luca , Ferreri Andrés J.M. , Zucca Emanuele , Doglioni Claudio , Cavalli Franco , Bertoni Francesco
Published: August 2007

Primary central nervous system lymphoma (PCNSL) is a rare form of extranodal non-Hodgkin’s lymphoma with continuously increasing incidence in both immunosuppressed and immunocompetent individuals. PCNSL is a very aggressive tumor with a poor outcome, and its clinical outcome is much worse than for nodal lymphomas. Differently from lymphomas arising in lymph nodes or in other extranodal sites, the treatment of PCNSL remains very unsatisfactory. Current biologic knowledge of PCNSL is still limited and several fundamental questions remain to be answered. This is mainly due to the paucity of PCNSL material for adequate translational research. With the aim of providing biologic material to investigators interested in PCNSL, we have implemented a virtual tissue bank (VTB) for PCNSL in immunocompetent patients. After registration, the VTB is accessible via any web browser at www.ielsg.org. Only anonymous data are centralized at the website of the International Extranodal Lymphoma Study Group, whilst the pathologic material is maintained at the local pathology institutes.
Effect of a Fluoridated Food Item on Enamel in situ
Authors: Meyer-Lueckel H. , Bitter K. , Kielbassa A.M.
Published: August 2007

After the consumption of food items prepared with fluoridated salt elevated fluoride concentrations can be observed in saliva, whereby enamel mineralization is supposed to be positively affected. The aim of this double-blind (with respect to fluoride), placebo-controlled, randomized, cross-over study was to evaluate the effects of the consumption of either a fluoridated (effect) or a placebo food item on the mineral content of sound and pre-demineralized human enamel in situ. During both phases of the study 8 enamel specimens in each of 10 intraoral appliances were positioned, either recessed or flush with the acrylic surface. One of the flanges was brushed twice daily with fluoride-free toothpaste prior to the storage of the appliance in sucrose solution. The subjects were asked to refrain from other sources of fluorides except for the consumption of either a highly fluoride-containing (0.5 mg) or a placebo cookie (3 times daily) during the respective study phase. Mineral content and lesion depth were measured in the enamel specimens and fluoride concentrations in saliva and urine. Significantly increased urinary and salivary (immediately after food consumption) fluoride concentrations compared to baseline were observed during the effect phase. In the absence of fluorides more pronounced demineralization was observed, especially for the recessed specimens of both surface conditions. Brushing was shown to inhibit demineralization, particularly during the placebo phase. In conclusion, fluorides added to food items seem to be efficacious to inhibit enamel demineralization in plaque-covered enamel but might be less effective if oral hygiene is adequate.
Histological and Ultrastructural Changes of Cardiomyocytes in Experimental Rats with Tail Thrombosis following Subplantar Application of Carrageenin
Authors: Kod’ousek Rostislav , Jezdínský Jaroslav , Krajčí Dimitrolos
Published: August 2007

Objective: To describe histological and ultrastructural changes of cardiomyocytes in experimental rats following subplantar administration of carrageenin. Material and Methods: In adult rats, an acute inflammatory reaction was induced by subplantar injection of 0.1 ml of 1% sterile carrageenin solution. In a total of 10 rats, which developed gangrene of tails in 5- to 12-cm-long segments, were killed and their internal organs fixed in 10% formaldehyde solution and subsequently processed for paraffin embedding. Later, blocks of the ventricular heart tissue were refixed and reprocessed for Araldite embedding and ultrastructure observation. Similarly, the cardiac muscle of control, carrageenin-injected rats which did not develop vascular thrombosis was processed. Results: The cardiomyocytes of rats injected with carrageenin showed focal dystrophic alterations, enlarged mitochondria with densely packed concentrically oriented cristae, and many dense and irregularly shaped deposits with microgranular helicoid organization. Normal cardiomyocytes were observed in control rats. Complicating thrombosis of tail blood vessels leading to extensive tail necroses were also histologically confirmed. Conclusion: These findings demonstrate specific pathogenic effect in the cardiovascular system of the carrageenin-treated rats.
Association between an AluI Polymorphism in the Calcitonin Receptor Gene and Quantitative Ultrasound Parameters in Korean Men
Authors: Kang Byung Yong , Kim Ji Young , Lee Kang Oh
Published: August 2007

Objective: The purpose of this study was to investigate the association between an AluI RFLP of the calcitonin receptor (CTR) gene and quantitative ultrasound (QUS) parameters in Korean men, and the interaction with nutrition as a lifestyle factor. Materials and Methods: Broadband ultrasound attenuation, speed of sound and stiffness index of the calcaneus were measured using an ultrasound bone densitometer in 201 Korean men (mean age ± SD: 51.6 ± 11.7 years). The PCR-RFLP method was used to analyze an AluI polymorphism in the CTR gene. Results: In all subjects, the distribution of CC, CT and TT genotypes occurred with frequencies of 87.1, 12.4 and 0.5%, respectively. When stratified by omnivore and vegetarian groups, there was a significant association between an AluI polymorphism in the CTR gene and QUS parameters such as speed of sound and stiffness index in only vegetarian subjects. Conclusion: Our data suggest that the AluI polymorphism of the CTR gene can be useful as a genetic marker in the interindividual susceptibility of QUS parameters by the interaction with nutritional status as a lifestyle factor.