bluuebunny/crossref_metadata_2025 huggingface dataset:
Étude du comportement à l’état frais des bétons autoplaçants à base de matériaux locaux
Authors: Bouhamou N. , Belas N. , Mesbah H. , Mebrouki A. , Ammar Y.
Published: July 2008

Les bétons autoplaçants (BAP), des bétons très fluides dont la mise en place ne nécessite aucune vibration, présentent un intérêt sans cesse croissant auprès des industriels en raison des nombreux avantages qu’ils offrent, tant sur le plan environnemental que technologique ou économique. La présente étude s’inscrit dans le cadre des travaux de recherches menés au Département de génie civil de l’Université Abdelhamid Ibn Badis de Mostaganem, Algérie, en ce qui concerne l’influence des paramètres de composition sur le comportement des BAP à l’état frais. Elle a pour objectif (i) de comprendre les rôles joués par différents composants locaux potentiels, notamment, le sable de mer et le sable de carrière (considéré comme un déchet naturel) et (ii) de mettre en évidence les éventuelles interactions entre constituants. Les résultats obtenus offrent de belles perspectives pour optimiser les BAP en Algérie. Une variété de formulations de BAP répondant aux critères rhéologiques (bonne déformabilité, moins de ressuage, absence de ségrégation) a été développée.
Identifying logical dummy activities in an activity-on-arrow network
Authors: Kim Kyunghwan
Published: July 2008

The activity-on-arrow (AOA) method can be used in construction projects depending on the project condition, although it is relatively inefficient as compared to the activity-on-node (AON) method. The most critical problem of the AOA method that is yet to be resolved is the application of a logical dummy activity (dummy). This paper presents a heuristic method that can be used for systematically identifying and applying logical dummies during the creation of an AOA network based on predefined activity dependencies. The heuristic method first identifies logical dummies of one-to-one relationships, and then detects the other multiple relationships in a stepwise manner to remove the redundancies therein.
Use of nondestructive testing to establish mechanistic-based seasonal load-carrying capacity of thin-paved highways in Saskatchewan
Authors: Berthelot Curtis , Stuber Erin , Podborochynski Diana , Fair Jena , Marjerison Brent
Published: July 2008

It has long been known that increased load-carrying capacity during the winter months is very beneficial to rural road transportation in Saskatchewan. However, it has been observed that rapid weakening of thin-paved roads during spring thaw is highly detrimental to the load-carrying capacity of these roads. Direct measures of the structural integrity of Saskatchewan roads as a function of seasonal changes have not been quantified in the past. The objective of this study was to directly quantify the impact frost action has on the load-carrying capacity of thin-surfaced roads. This study examined the magnitude and rate of change of in situ structural deflection responses of a typical Saskatchewan thin-surfaced road during fall freeze-up and spring thaw in 2006–2007. This study showed that structural deflection responses significantly improved with frost depth greater than 50 cm and that deflection response significantly worsened with minimal thaw depth, as expected. The data obtained also indicated a significant increase in nonlinear strain weakening behavior during fall freeze-up at frost depths less than 50 cm. Therefore, based on the findings of this study, the frost thickness and the rate of change in frost thickness need to be directly considered in the fall and in the spring when calculating seasonal load limits of thin-paved roads.
Review of post-earthquake fire hazard to building structures
Authors: Mousavi Shahab , Bagchi Ashutosh , Kodur Venkatesh K.R.
Published: July 2008

Fire following an earthquake is an important factor causing damage to buildings and life-line structures. Therefore, besides satisfying structural design requirements for normal loads, such as dead and live loads including the seismic hazard, buildings should also be designed to withstand the fire following earthquakes for a certain minimum duration as required for a desired level of performance. This period of time will allow occupants to evacuate the building safely and the emergency crews to cope with the fire. Also, it is essential to reduce the post-earthquake fire (PEF) ignitions and minimize the damage to active fire protection systems as much as possible to prevent the spread of fire. This paper presents a state-of-the-art review on the PEF hazard and discusses the causes, mitigation measures, and performance of building structures under this hazard. Mitigation measures that could be developed based on the experience from the structural engineering field are identified. Both local and global approaches that should be taken to mitigate the PEF hazard, including structural and nonstructural design, various urban planning aspects, and their interactive combinations, are discussed. Based on the review, it is concluded that that there is a strong need for the development of guidelines for structural fire safety design for PEF scenarios. In addition, appropriate analysis and numerical simulation techniques for the evaluation of the structural performance under earthquake-induced fire conditions need to be developed. It is also necessary to conduct experimental studies to validate such numerical models and refine them.
Decalcification mechanism of concrete by organic matters in atmosphere
Authors: Tomoto Takashi , Moriyoshi Akihiro
Published: July 2008

This study confirmed that concrete structures and historical structures made of limestone absorb environmental endocrine disrupters such as anion surfactant and phthalic acid esters contained in windshield washer fluid by using 1H nuclear magnetic resonance (NMR), high-performance liquid chromatography (HPLC), gas chromatograph mass spectrometer (GC–MS), and other analytical techniques. Furthermore, it was confirmed that environmental endocrine disrupting organic matter, including phthalic acid esters, penetrated into concrete and accelerated its deterioration and that calcium salt of phthalic acid esters existed in decalcified concrete by means of solid-state cross polarization magic angle spinning carbon-13 (CPMAS 13C) NMR and electron probe microanalysis (EPMA). This phenomenon was demonstrated in a laboratory experiment. Bone mineral content (BMC) and a specific surface area of decalcified concrete slabs were measured in each layer in the depth direction, and it was revealed that deterioration was more severe and cement paste was more porous in the layers closer to the slab surface.
Modulus−suction−moisture relationship for compacted soils
Authors: Sawangsuriya Auckpath , Edil Tuncer B. , Bosscher Peter J.
Published: July 2008

The ultimate parameter of interest in engineering design of compacted subgrades and support fills for highways, railroads, airfields, parking lots, and mat foundations is often the soil modulus. Modulus of compacted soils depends not only on dry unit weight and moisture but also on matric suction and soil structure (or fabric) resulting from the compaction process. However, these relationships in the as-compacted state (i.e., immediately after compaction) have not yet been extensively explored. This paper presents an experimental laboratory study of the shear modulus – matric suction – moisture content-dry unit weight relationship using three compacted subgrade soils. Compacted subgrade specimens were prepared over a range of molding water contents from dry to wet of optimum using enhanced, standard, and reduced Proctor efforts. A nondestructive elastic wave propagation technique, known as bender elements, was used to assess the shear wave velocity and corresponding small-strain shear modulus (Go) of the compacted subgrade specimens. The matric suctions were measured with the filter paper method. An empirical relation that takes into account the effect of compaction conditions is proposed for the Go– matric suction – molding water content relationship of compacted subgrade soils.
Experimental study of interaction and coupling effects in pile groups subjected to torsion
Authors: Kong L. G. , Zhang L. M.
Published: July 2008

Piles in a pile group subjected to torsion simultaneously mobilize lateral and torsional resistances. Hence, complicated pile–soil–pile interaction effects and load deformation coupling effects occur in the pile group. In this study, a series of centrifuge model tests were carried out to investigate these effects in three-diameter spaced 1 × 2, 2 × 2, and 3 × 3 pile groups subjected to torsion in both loose and dense sands. The test results showed that the effect of horizontal movement of a pile on lateral behaviors of its adjacent piles is significant in 3 × 3 pile groups and such effect varies with group configuration and pile position. The p-multiplier concept can be used to quantify the effect and values for the p-multiplier are suggested. The effect of lateral movement of a pile on the torsional resistances of its adjacent piles and the effect of torsional movement of a pile on the lateral resistances of its adjacent piles were found to be minor in these tests. For an individual pile in a pile group subjected to torsion, the mobilized lateral resistance was found to substantially increase the torsional resistance of the pile. Such a coupling effect is quantified by a coupling coefficient, β, which describes the contribution of subgrade reaction to the increase of torsional shear resistance.
Carbon and silicon substitution in (4, 4) aluminum nitride nanotube — Density functional study of27Al and14N electric field gradient tensors
Authors: Seif Ahmad , Aghaie Mehran , Aghaie Hossein
Published: July 2008

A computational study at the level of density functional theory (DFT) was performed to investigate the influence of Si and C substitution on the14N and27Al quadrupole coupling constants (CQ) in the armchair single-walled aluminum nitride nanotube (SWAlNNT). To this aim, a 1 nm AlNNT consisting of 28 Al and 28 N atoms was considered in which both mouths of the nanotube are capped by hydrogen atoms. Additionally, two other forms of this model of AlNNT were considered in which five Si and five C atoms were substituted in place of the five Al and five N atoms, with two rings in the length of nanotube, like a wire, in the first form; and three Si and three C atoms were substituted in place of three Al and three N atoms as a central ring on the surface of the AlNNT in the second form. The calculated CQvalues for three optimized AlNNT systems (raw and Si- and C-substituted) reveal diverse electronic environments in the above-mentioned systems. All the calculations were carried out using the Gaussian 98 software package.Key words: armchair nanotube, density functional theory, nuclear quadrupole resonance.
Glycine-promoted rapid synthesis of novel xanthene derivatives in ionic liquid
Authors: Kidwai Mazaahir , Singhal Kavita , Kukreja Shuchi
Published: July 2008

A green route for the synthesis of multi-substituted 2,3-dihydro-xanthenone derivatives using ionic liquid as solvent and amino acid as promoter is described. The reaction is simple and proceeds well at room temperature and devoid of the use of any harmful catalyst or solvent. This is an efficient technique.Key words: xanthene, ionic liquid, glycine, room temperature.
F 1s spectroscopy and ionic fragmentation of trifluoropropyne
Authors: Neville John J , Appathurai Narayana P , Fan Yongheng , Odoh Samuel , Yang Liu
Published: July 2008

The F 1s excitation spectroscopy and ionic fragmentation of 3,3,3-trifluoro-1-propyne have been studied using synchrotron radiation and ion time-of-flight mass spectrometry. The total ion yield spectrum and photoionization branching ratios in the vicinity of the F 1s ionization threshold are reported. Core excited state calculations using the static exchange approximation are used to aid in the interpretation of the experimental results. The F 1s excitation spectrum consists of a number of broad overlapping bands below threshold, attributed to excitations to mixed σ*(C-F)/π*(C-C) molecular orbitals and unresolved Rydberg states, and a continuum shape resonance 12.5 eV above threshold. Ionic fragmentation following F 1s excitation or ionization results overwhelmingly in singly charged ionic fragments, primarily via cleavage of bonds to the fluorinated carbon atom adjacent to the core-excited atom.Key words: F 1s excitation, XANES, photoelectron-photoion coincidence, ionic fragmentation, static exchange approximation.
The photochemistry of trans-isohumulone, a bitter flavouring component of beer
Authors: Weedon Alan C , Morrison John S
Published: July 2008

Methanolic solutions of trans-isohumulone (2), a major bitter flavouring component in beer, were irradiated with UV light of 313 nm wavelength and yielded four primary products containing an enolized cyclic β-triketone moiety: cis-isohumulone (3), humulone (1), dehydro-isohumulone (7), and dehydro-humulinic acid (5). The last of these products results from loss of the 4-methyl-3-pentenoyl side chain of trans-isohumulone. Nine volatile products derived from this side chain were identified and quantitated. The identifications of all photoproducts were confirmed by independent preparation of authentic samples. No evidence of either intramolecular or intermolecular 2+2 cyclo-addition was observed. This work clarifies previous contradictory reports of the products of isohumulone photolysis and provides an example of unexpected photochemistry of an alkenyl-substituted enolized cyclic β-triketone.Key words: trans-isohumulone, photo-degradation, cyclic β-triketone.
Amine-tetheredN-heterocyclic carbene complexes of rhodium(I)
Authors: Jong Howard , Patrick Brian O , Fryzuk Michael D
Published: July 2008

A new family of rhodium-diene based complexes has been developed that incorporates an N-heterocyclic carbene ligand with an N-donor tether. The ligand is denotedMes[CNH] 2 (whereMes[CNH] is 2,4,6-Me3C6H2NC3H2NCH2CH2NH-2,4,6-Me3C6H2) andMes[CN] for the amido form. The synthesis of theMes[CNH] ligand involves reaction of N-mesitylimidazole with 2-chloroethyl-N-mesitylamine under melt conditions, followed by deprotonation with KN(SiMe3)2. The reaction ofMes[CNH] with [(diene)RhCl]2results in the formation of the monodentate complexes,Mes[CNH]Rh(diene)Cl (where diene = 1,5-cyclooctadiene (COD): 3a; diene = 2,5-norbornadiene (NBD): 3b). Bidentate variants could be isolated as either a neutral species,Mes[CN]Rh(diene) 4a–4b, via deprotonation, or an ionic analogue such as [Mes[CNH]Rh(diene)]BF45a–5b by reaction with NaBF4. Compounds 4–5 are the first examples of rhodium compounds that contained a bidentate NHC ligand with a pendant amino or amido donor. Complexes 3–5 were characterized fully and the solid-state single crystal X-ray structures of 3a, 4a, and 5b are discussed. The utility of these complexes as catalyst precursors for hydrogenation reactions was examined and it was determined that these systems are not significantly more active than colloidal rhodium when parallel reactions were run. Various methods of transfer hydrogenations were also investigated with 3a, which did not yield an appreciable conversion of either benzophenone or N-benzylideneaniline as substrates.Key words: rhodium, N-heterocyclic carbene, catalysis, hydrogenation.
Mass spectrometric detection of proteins in non-aqueous media — The case of prion proteins in biodiesel
Authors: Douma Michelle D , Kerr Gina M , Brown R Stephen , Keller Bernd O , Oleschuk Richard D
Published: July 2008

Limitations in efficient extraction, minimization of media interferences, and suitable sample preparation methods pose significant challenges to the successful detection of protein traces in non-aqueous media. Here we present a filtration method, employing filter disks with embedded C8-modified silica particles, that allows the capture of proteins from non-aqueous sample volumes. The extraction process is followed by elution of the protein from the filter disk and by either direct mass spectrometric detection or tryptic digestion followed by peptide mapping and MS/MS fragmentation of protein-specific peptides. The method is applied to spiked biodiesel samples for the detection of prion proteins. The tryptic peptide with sequence YPGQGSPGGNR is specific for prion proteins and can be used for unambiguous identification. The developed extraction method has the potential application to be used for large-scale testing of protein impurities in non-aqueous media, for instance as a safety and quality control tool in the animal tallow-based biodiesel production process.Key words: protein detection, MALDI, non-aqueous media, filtration
An efficient method for the silylation of hydroxyl groups with hexamethyldisilazane (HMDS) catalyzed by aluminum tris(dihydrogen phosphate) under solvent-free and ambient conditions
Authors: Shaterian Hamid Reza , Ghashang Majid , Riki Nassrin Tajbakhsh , Asadi Manijeh
Published: July 2008

A highly efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, benzylic, secondary, hindered secondary, tertiary, phenols, and oximes with hexamethyldisilazane (HMDS), using Al(H2PO4)3 as a recyclable heterogeneous catalyst at room temperature in a few minutes with excellent yields under solvent-free conditions is described.Key words: trimethylsilylation, hexamethyldisilazane, aluminum tris(dihydrogen phosphate) [Al(H2PO4)3], solvent-free, hydroxyl groups.
Variation in yeast mitochondrial activity associated with asci
Authors: Swart Chantel W. , van Wyk Pieter W.J. , Pohl Carolina H. , Kock Johan L.F.
Published: July 2008

An increase in mitochondrial membrane potential (ΔΨm) and mitochondrially produced 3-hydroxy (3-OH) oxylipins was experienced in asci of the nonfermentative yeasts Galactomyces reessii and Lipomyces starkeyi and the fermentative yeasts Pichia farinosa and Schizosaccharomyces octosporus . Strikingly, asci of Zygosaccharomyces bailii showed no increase in mitochondrial activity (ΔΨm and oxylipin production). As expected, oxygen deprivation only inhibited ascus formation in those yeasts with increased ascus mitochondrial activity. We conclude that ascus formation in yeasts is not always dependent on mitochondrial activity. In this case, fermentation may provide enough energy for ascus formation in Z. bailii.
Helicobacter pylori produces unique filaments upon host contact in vitro
Authors: Couturier Marc Roger , Stein Markus
Published: July 2008

Helicobacter pylori exists in 2 distinct morphological states, helicoid and coccoid. Both have been observed in in vitro culture and in gastric biopsies. We visualized H. pylori during AGS cell infections using immunofluorescence microscopy. Anti-H. pylori mouse serum as well as human serum from H. pylori-positive patients recognized long, thin bacterial filaments, which formed on helicoids and more frequently on coccoids. These filaments reached lengths of 59 μm and often connected bacteria. Periodate oxidation abolished antibody recognition, suggesting that carbohydrates compose a major antigenic component of the filaments. Similar to results obtained using immunofluorescence microscopy, scanning electron microscopy imaging revealed thin filamentous structures, which were absent on uninfected cells. Both coccoid conversion and filament development increased over the time course of infection with peak filament formation at 4 h. The number of visible filaments then decreased as bacteria clustered on the apical surface of AGS cells. Since the observed filaments were clearly distinct from previously described surface structures, including flagella and the cag type IV secretion system, our results demonstrate that these filaments represent a unique, previously unrecognized, organelle.
A compensatory increase in trehalose synthesis in response to desiccation stress in Saccharomyces cerevisiae cells lacking the heat shock protein Hsp12p
Authors: Shamrock Vanessa J. , Lindsey George G.
Published: July 2008

The effect of HSP12 deletion on the response of yeast to desiccation was investigated. The Δhsp12 strain was found to be more desiccation tolerant than the wild-type strain. Furthermore, the increased intracellular trehalose levels in the Δhsp12 strain suggested that this strain compensated for the lack of Hsp12p synthesis by increasing trehalose synthesis, which facilitated increased desiccation tolerance. Results obtained from flow cytometry using the membrane exclusion dye propidium iodide suggested that Hsp12p helped maintain plasma membrane integrity during desiccation. Analysis of the oxidative loads experienced by the wild-type and Δhsp12 strains showed that during mid-exponential phase, the increased trehalose levels present in the Δhsp12 cells resulted in increased protection of these cells against reactive oxygen species compared with wild-type cells. During stationary phase, lower levels of reactive oxygen species reduction by reduced glutathione was enhanced in the wild-type strain, which displayed lower intracellular trehalose concentrations. Comparison of the tolerance of the wild-type and Δhsp12 strains with applied oxidative stress showed that the Δhsp12 strain was more tolerant to exogenously applied H2O2, which we attributed to the higher intracellular trehalose concentration. Flow cytometry demonstrated that Hsp12p played a role in maintaining plasma membrane integrity during applied oxidative stress.
Virulence properties and antimicrobial susceptibility of Shiga toxin-producing Escherichia coli strains isolated from healthy cattle from Paraná State, Brazil
Authors: Pigatto Caroline P. , Schocken-Iturrino Ruben P. , Souza Emanuel M. , Pedrosa Fábio O. , Comarella Larissa , Irino Kinue , Kato Maria Aidê M.F. , Farah Sônia M.S.S. , Warth José F. , Fadel-Picheth Cyntia M.T.
Published: July 2008

The presence of Shiga toxin-producing Escherichia coli (STEC) strains in feces samples of cattle was determined using the cytotoxicity assay on Vero cells and a screening PCR system to detect stx genes. The STEC isolates were serotyped, tested for antimicrobial susceptibility, and analyzed for virulence genes using multiplex PCR. The verocytotoxin-producing E. coli – reverse passive latex agglutination (VTEC–RPLA) assay was also used to detect Shiga toxin production. The frequency of cattle shedding STEC was 36%. The isolates belonged to 33 different serotypes, of which O10:H42, O98:H41, and O159:H21 had not previously been associated with STEC. The most frequent serotypes were ONT:H7 (10%), O22:H8 (7%), O22:H16 (7%), and ONT:H21 (7%). Most of the strains (96%) were susceptible to all antimicrobial agents tested. Shiga toxin was detected by the VTEC–RPLA assay in most (89%) of the STEC strains. The frequency of virulence markers was as follows: stx1, 10%; stx2, 43%; stx1 plus stx2, 47%; ehxA, 44%; eae, 1%; and saa, 38%. Several strains belong to serotypes associated with human disease, and most of them carried a stx2-type gene, suggesting that they represent a risk to human health. The screening PCR assay showed fewer false-negative results for STEC than the Vero-cell assay and is suitable for laboratory routine.
ON THE EXISTENCE OF BRANCHED COVERINGS BETWEEN SURFACES WITH PRESCRIBED BRANCH DATA, II
Authors: PERVOVA EKATERINA , PETRONIO CARLO
Published: July 2008

If [Formula: see text] is a branched covering between closed surfaces, there are several easy relations one can establish between the Euler characteristics [Formula: see text] and χ(Σ), orientability of Σ and [Formula: see text], the total degree, and the local degrees at the branching points, including the classical Riemann–Hurwitz formula. These necessary relations have been shown to be also sufficient for the existence of the covering except when Σ is the sphere 𝕊 (and when Σ is the projective plane, but this case reduces to the case Σ = 𝕊). For Σ = 𝕊 many exceptions are known to occur and the problem is widely open.

Generalizing methods of Baránski, we prove in this paper that the necessary relations are actually sufficient in a specific but rather interesting situation. Namely under the assumption that Σ = 𝕊, that there are three branching points, that one of these branching points has only two pre-images with one being a double point, and either that [Formula: see text] and that the degree is odd, or that [Formula: see text] has genus at least one, with a single specific exception. For the case of [Formula: see text] we also show that for each even degree there are precisely two exceptions.
A Cn-MOVE FOR A KNOT AND THE COEFFICIENTS OF THE CONWAY POLYNOMIAL
Authors: OHYAMA YOSHIYUKI , YAMADA HARUMI
Published: July 2008

It is shown that two knots can be transformed into each other by Cn-moves if and only if they have the same Vassiliev invariants of order less than n. Consequently, a Cn-move cannot change the Vassiliev invariants of order less than n and may change those of order more than or equal to n. In this paper, we consider the coefficient of the Conway polynomial as a Vassiliev invariant and show that a Cn-move changes the nth coefficient of the Conway polynomial by ±2, or 0. And for the 2mth coefficient (2m > n), it can change by p or p + 1 for any given integer p.
BRAID FAMILY REPRESENTATIVES
Authors: JABLAN SLAVIK , SAZDANOVIĆ RADMILA
Published: July 2008

Imposing different conditions on minimality of reduced braid words and new criteria on their representatives, we define braid family representatives and establish one-to-one correspondence with families of knots and links given in Conway notation.
MASSEY–MILNOR LINKING = CHERN–SIMONS–WITTEN GRAPHS
Authors: HSIEH CHUN-CHUNG
Published: July 2008

We express the first non-vanishing Massey–Milnor linkings in terms of Chern–Simons–Witten configuration space integrals in perturbative quantum field theory.
Insulin as a physiological modulator of glucagon secretion
Authors: Bansal Pritpal , Wang Qinghua
Published: July 2008

Glucose homeostasis is regulated primarily by the opposing actions of insulin and glucagon, hormones that are secreted by pancreatic islets from β-cells and α-cells, respectively. Insulin secretion is increased in response to elevated blood glucose to maintain normoglycemia by stimulating glucose transport in muscle and adipocytes and reducing glucose production by inhibiting gluconeogenesis in the liver. Whereas glucagon secretion is suppressed by hyperglycemia, it is stimulated during hypoglycemia, promoting hepatic glucose production and ultimately raising blood glucose levels. Diabetic hyperglycemia occurs as the result of insufficient insulin secretion from the β-cells and/or lack of insulin action due to peripheral insulin resistance. Remarkably, excessive secretion of glucagon from the α-cells is also a major contributor to the development of diabetic hyperglycemia. Insulin is a physiological suppressor of glucagon secretion; however, at the cellular and molecular levels, how intraislet insulin exerts its suppressive effect on the α-cells is not very clear. Although the inhibitory effect of insulin on glucagon gene expression is an important means to regulate glucagon secretion, recent studies suggest that the underlying mechanisms of the intraislet insulin on suppression of glucagon secretion involve the modulation of KATPchannel activity and the activation of the GABA-GABAAreceptor system. Nevertheless, regulation of glucagon secretion is multifactorial and yet to be fully understood.
Cardiac metabolic compensation to hypertension requires lipoprotein lipase
Authors: Yamashita Haruyo , Bharadwaj Kalyani G. , Ikeda Shota , Park Tae-Sik , Goldberg Ira J.
Published: July 2008

Fatty acids (FAs) are acquired from free FA associated with albumin and lipoprotein triglyceride that is hydrolyzed by lipoprotein lipase (LpL). Hypertrophied hearts shift their substrate usage pattern to more glucose and less FA. However, FAs may still be an important source of energy in hypertrophied hearts. The aim of this study was to examine the importance of LpL-derived FAs in hypertensive hypertrophied hearts. We followed cardiac function and metabolic changes during 2 wk of angiotensin II (ANG II)-induced hypertension in control and heart-specific lipoprotein lipase knockout (hLpL0) mice. Glucose metabolism was increased in ANG II-treated control (control/ANG II) hearts, raising it to the same level as hLpL0 hearts. FA uptake-related genes, CD36 and FATP1, were reduced in control/ANG II hearts to levels found in hLpL0 hearts. ANG II did not alter these metabolic genes in hLpL0 mice. LpL activity was preserved, and mitochondrial FA oxidation-related genes were not altered in control/ANG II hearts. In control/ANG II hearts, triglyceride stores were consumed and reached the same levels as in hLpL0/ANG II hearts. Intracellular ATP content was reduced only in hLpL0/ANG II hearts. Both ANG II and deoxycorticosterone acetate-salt induced hypertension caused heart failure only in hLpL0 mice. Our data suggest that LpL activity is required for normal cardiac metabolic compensation to hypertensive stress.
Decreasing intramuscular phosphagen content simultaneously increases plasma membrane FAT/CD36 and GLUT4 transporter abundance
Authors: Pandke Kristin E. , Mullen Kerry L. , Snook Laelie A. , Bonen Arend , Dyck David J.
Published: July 2008

Decreasing muscle phosphagen content through dietary administration of the creatine analog β-guanidinopropionic acid (β-GPA) improves skeletal muscle oxidative capacity and resistance to fatigue during aerobic exercise in rodents, similar to that observed with endurance training. Surprisingly, the effect of β-GPA on muscle substrate metabolism has been relatively unexamined, with only a few reports of increased muscle GLUT4 content and insulin-stimulated glucose uptake/clearance in rodent muscle. The effect of chronically decreasing muscle phophagen content on muscle fatty acid (FA) metabolism (transport, oxidation, esterification) is virtually unknown. The purpose of the present study was to examine changes in muscle substrate metabolism in response to 8 wk feeding of β-GPA. Consistent with other reports, β-GPA feeding decreased muscle ATP and total creatine content by ∼50 and 90%, respectively. This decline in energy charge was associated with simultaneous increases in both glucose (GLUT4; +33 to 45%, P < 0.01) and FA (FAT/CD36; +28 to 33%, P < 0.05) transporters in the sarcolemma of red and white muscle. Accordingly, we also observed significant increases in insulin-stimulated glucose transport (+47%, P < 0.05) and AICAR-stimulated palmitate oxidation (+77%, P < 0.01) in the soleus muscle of β-GPA-fed animals. Phosphorylation of AMPK (+20%, P < 0.05), but not total protein, was significantly increased in both fiber types in response to muscle phosphagen reduction. Thus the content of sarcolemmal transporters for both of the major energy substrates for muscle increased in response to a reduced energy charge. Increased phosphorylation of AMPK may be one of the triggers for this response.
Interlimb Coordination in Rhythmic Leg Movements: Spontaneous and Training-Induced Manifestations in Human Infants
Authors: Musselman Kristin E. , Yang Jaynie F.
Published: July 2008

Different rhythmic leg movements in vertebrates can share coordinating neural circuitry. These movements are often similar kinematically, and smooth transitions between the different movements are common. We focused on interlimb coordination of the legs in young infants to determine whether weight bearing and non–weight bearing movements might share coordinating circuitry. If interlimb coordination is controlled by the same circuitry, the same coordination (i.e., either synchronous or alternate) should be seen in different rhythmic movements. Moreover, if we altered the interlimb coordination in one movement through exercise, it should translate to a change in coordination in another rhythmic movement that received no exercise. Video and electrogoniometry were recorded while 46 infants (age, 6.2 ± 1.4 mo) performed non–weight bearing and weight bearing movements. Interlimb coordination was quantified by the phase lag between the movement cycles of each leg. Most infants (83%) showed the same coordination in weight bearing and non–weight bearing movements. Ten infants practiced the form of coordination they did not exhibit in the first visit, in weight bearing for 4 wk. Following practice, 8 of 10 infants changed their interlimb coordination in weight bearing to that practiced. Some who practiced synchronous coordination also changed their coordination in non–weight bearing activity. More infants showed both forms of coordination after practice and smooth transitions between the two forms. The results suggest that interlimb coordination is malleable in infants, and there is a partial sharing of the neural substrates for interlimb coordination between different rhythmic leg movements in infants.
Common MMP-7 Polymorphisms and Breast Cancer Susceptibility: A Multistage Study of Association and Functionality
Authors: Beeghly-Fadiel Alicia , Long Ji-Rong , Gao Yu-Tang , Li Chun , Qu Shimian , Cai Qiuyin , Zheng Ying , Ruan Zhi-Xian , Levy Shawn E. , Deming Sandra L. , Snoddy Jay R. , Shu Xiao-ou , Lu Wei , Zheng Wei
Published: July 2008

Matrix metalloproteinase-7 (MMP-7) is a small secreted proteolytic enzyme with broad substrate specificity against ECM and non-ECM components. Known to be vital for tumor invasion and metastasis, accumulating evidence also implicates MMP-7 in cancer development. Using data from the Shanghai Breast Cancer Study, we conducted a two-stage study to evaluate the association of MMP-7 single nucleotide polymorphisms (SNPs) with breast cancer risk. Additionally, associated SNPs were characterized by laboratory assays. In stage 1, 11 SNPs were genotyped among 1,079 incident cases and 1,082 community controls using an Affymetrix Genotyping System. Promising SNPs were selected for stage 2 evaluation and genotyped by TaqMan allelic discrimination assays in an independent set of 1,911 cases and 1,811 controls. Three SNPs were selected for stage 2 validation (rs880197, rs10895304, and rs12184413); one had highly consistent results between the two stages of the study. In combined analysis, homozygosity for the variant T allele for rs12184413 was associated with an odds ratio (OR) of 0.7 [95% confidence interval (95% CI), 0.6–0.9] compared with the common C allele. This effect was slightly more pronounced in postmenopausal women (OR, 0.6; 95% CI, 0.4–0.8) than in premenopausal women (OR, 0.8; 95% CI, 0.6–1.1). This SNP is located 3′ of the MMP-7 gene, in an area enriched with CTCF binding sites. In silico analysis suggested a regulatory role for this region, and our in vitro assays showed an allelic difference in nuclear protein binding capacity. Results from our study suggest that common MMP-7 genetic polymorphisms may contribute to breast cancer susceptibility. [Cancer Res 2008;68(15):6453–9]
Plasma Triglycerides as Predictors of Platelet Responsiveness to Aspirin in Patients after First Ischemic Stroke
Authors: Karepov Vadim , Tolpina Galina , Kuliczkowski Wiktor , Serebruany Victor
Published: July 2008

Background: Although aspirin (ASA) remains the most popular and accepted agent for secondary stroke prevention, its efficacy does not exceed 25%. Platelet function monitoring in ASA users suggests that some individuals exhibit a reduced or even absent antiplatelet response after ASA. This phenomenon, also known as ‘resistance’, is prevalent in stroke survivors. We sought to evaluate the blood lipid profile in poststroke ASA users dependent on their antiplatelet response to ASA. Methods: Ninety-six consecutive ASA users after first-ever ischemic stroke confirmed by imaging were prospectively enrolled. The platelet function analyzer (PFA-100, Dade Behring, USA) was utilized to assess the response after ASA. The lipid profile (total cholesterol, high-density lipoprotein, low-density lipoprotein and triglycerides) was measured using the Cardiochek instrument (Polymer Technology, USA) from the autologuos blood samples. Results: The poststroke duration was 3–26 months, and all patients were treated with ASA for at least 3 months. The allowed daily ASA doses were from 75 up to 325 mg, with a mean of 158 mg. The mean age of the patients was 71 years, almost 60% were women, and over 85% of the patients were treated with statins. Thirty-seven patients were identified as low ASA responders, while 59 patients exhibited an adequate response. There were no differences between ASA responders and nonresponders with regard to demographics, clinical characteristics, risk factors and concomitant medications. The lipid profile biomarkers were similar between groups with the exception of triglycerides, which were significantly increased in the patients with ASA resistance, compared with ASA responders. Conclusion: The fact that hypertriglyceridemia affects platelet response to ASA has potential practical implications in light of growing evidence that ASA may exert antiplatelet properties beyond the cyclooxygenase pathway. The mechanism of such an association is unclear but may be related to the diminished platelet membrane fluidity and inability of ASA to downregulate such ‘strong’ protected platelets.
Predictors of New Onset of Diabetes after Transplantation in Stable Renal Recipients
Authors: Shehab-Eldin Walid , Shoker Ahmed
Published: July 2008

Background: Several groups identified pre-transplant factors which contribute to the development of new onset of diabetes after transplantation (NODAT). Aim: To identify post-transplant risk factors for NODAT. Methods: 55 stable renal transplant patients were divided into group A of 34 recipients with normoglycemia and group B of 21 recipients with impaired fasting glucose. Markers including insulin, pro-insulin, soluble receptors for advanced glycated end products (sRAGE), adiponectin, malondialdehyde, homeostasis model assessment of insulin resistance (HOMA-IR), and β-cell function were calculated at the outset and correlated, thereafter, with the later development of NODAT after a follow-up duration of 14.98 ± 3.97 months. Results: 11.8 and 19% of groups A and B respectively developed NODAT. Insulin, sRAGE, HOMA-IR and basal fasting plasma glucose correlated with the development of NODAT in univariate analysis. A baseline insulin level of 54.54 mU/l predicted the development of NODAT with a specificity of 95.45% and was the only significant factor in the multivariate analysis. β-Cell function was not different among the three groups. Conclusions: A long prodrome of insulin resistance (IR) exists prior to development of NODAT. 50% of patients with NODAT will remit to a normoglycemic state. IR, rather than β-cell dysfunction, precedes the development of NODAT. Serum insulin in stable non-diabetic renal transplant patients can be used as a confirmatory test to the development of future NODAT.
Tomographic Left Ventricular Volumetric Emptying Analysis by Real-Time 3-Dimensional Echocardiography
Authors: De Castro Stefano , Faletra Francesco , Di Angelantonio Emanuele , Conca Cristina , Marcantonio Andrea , Francone Marco , Cartoni Domenico , Mirabelli Francesca , Gaudio Carlo , Caselli Stefano , Carbone Iacopo , Auricchio Angelo , Pandian Natesa G.
Published: July 2008

Background—

The sequence of left ventricular (LV) systolic emptying is not completely understood. Using real-time 3-dimensional echocardiography, we investigated this sequence and LV synchronicity in physiological and pathological conditions.

Methods and Results—

The study population consisted of 116 healthy volunteers, 20 top-level athletes, 35 patients with LV dysfunction, and 84 patients with LV dysfunction and left bundle-branch block (LBBB). We subdivided the LV into 16 volumetric segments for regional analysis and into apical, middle, and basal regions to calculate the mean of end-systolic times and the time to minimum systolic volume of each region. In healthy volunteers and in top-level athletes, the emptying systolic times increased smoothly from apex to base. These differences determined an apex-to-base time gradient in the LV emptying sequence. In patients with LV dysfunction and without LBBB, this gradient was maintained with a relatively higher LV dyssynchrony. However, in patients with LV dysfunction and LBBB, there was no clear sequence in LV emptying volumes, and this group had the highest LV dyssynchrony.

Conclusions—

Real-time 3-dimensional echocardiography tomographic slicing of the LV enables accurate analysis of LV emptying in physiological conditions and in conditions of LV dysfunction with and without electrical dyssynchrony. Progressive dilation of LV produces deterioration in LV synchronicity. However, it is the presence of LV dysfunction in combination with LBBB that determines the loss of the apex-to-base time gradient in LV emptying.
A Bulk Turbulent Air–Sea Flux Algorithm for High-Wind, Spray Conditions
Authors: Andreas Edgar L. , Persson P. Ola G. , Hare Jeffrey E.
Published: July 2008

Sensible and latent heat can cross the air–sea interface by two routes: as interfacial fluxes controlled by molecular processes right at the interface, and as spray fluxes from the surface of sea spray droplets. Once the 10-m wind speed over the ocean reaches approximately 11–13 m s−1, the spray sensible and latent heat fluxes become significant fractions (i.e., 10% or greater) of the corresponding interfacial fluxes. The analysis here establishes that result by combining the Tropical Ocean-Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (COARE) version 2.6 bulk interfacial flux algorithm with a microphysical spray model to partition measured heat fluxes from two good high-wind datasets into spray and interfacial flux contributions. The measurements come from the Humidity Exchange over the Sea (HEXOS) experiment and the Fronts and Atlantic Storm-Tracks Experiment (FASTEX); wind speeds in these two datasets span 5 to 20 m s−1.

After the measured heat fluxes are separated into spray and interfacial contributions, the spray fluxes are used to develop a fast spray flux algorithm to combine with the COARE version 2.6 interfacial flux algorithm in a unified turbulent surface flux algorithm for use in large-scale and ocean storm models. A sensitivity analysis of the spray and interfacial components of this unified flux algorithm demonstrates how the two component fluxes scale differently with the mean meteorological variables and why they must therefore be parameterized separately in models intended to treat air–sea fluxes in high winds.
Large-Eddy Simulation of Langmuir Turbulence in Pure Wind Seas
Authors: Harcourt Ramsey R. , D’Asaro Eric A.
Published: July 2008

The scaling of turbulent kinetic energy (TKE) and its vertical component (VKE) in the upper ocean boundary layer, forced by realistic wind stress and surface waves including the effects of Langmuir circulations, is investigated using large-eddy simulations (LESs). The interaction of waves and turbulence is modeled by the Craik–Leibovich vortex force. Horizontally uniform surface stress τ0 and Stokes drift profiles uS(z) are specified from the 10-m wind speed U10 and the surface wave age CP/U10, where CP is the spectral peak phase speed, using an empirical surface wave spectra and an associated wave age–dependent neutral drag coefficient CD. Wave-breaking effects are not otherwise included. Mixed layer depths HML vary from 30 to 120 m, with 0.6 ≤ CP/U10 ≤ 1.2 and 8 m s−1 < U10 < 70 m s−1, thereby addressing most possible oceanic conditions where TKE production is dominated by wind and wave forcing.

The mixed layer–averaged “bulk” VKE 〈w2〉/u*2 is equally sensitive to the nondimensional Stokes e-folding depth D*S/HML and to the turbulent Langmuir number Lat = u*/US, where u* = |τ0|/ρw in water density ρw and US = |uS|z=0. Use of a D*S scale-equivalent monochromatic wave does not accurately reproduce the results using a full-surface wave spectrum with the same e-folding depth. The bulk VKE for both monochromatic and broadband spectra is accurately predicted using a surface layer (SL) Langmuir number LaSL = u*/〈uS〉SL, where 〈uS〉SL is the average Stokes drift in a surface layer 0 > z > − 0.2HML relative to that near the bottom of the mixed layer. In the wave-dominated limit LaSL → 0, turbulent vertical velocity scales as wrms ∼ u*La−2/3SL. The mean profile (z) of VKE is characterized by a subsurface peak, the depth of which increases with D*S/HML to a maximum near 0.22HML as its relative magnitude /〈w2〉 decreases. Modestly accurate scalings for these variations are presented. The magnitude of the crosswind velocity convergence scales differently from VKE. These results predict that for pure wind seas and HML ≅ 50 m, 〈w2〉/u*2 varies from less than 1 for young waves at U10 = 10 m s−1 to about 2 for mature seas at winds greater than U10 = 30 m s−1. Preliminary comparisons with Lagrangian float data account for invariance in 〈w2〉/u*2 measurements as resulting from an inverse relationship between U10 and CP/U10 in observed regimes.
Vorticity and Divergence of Surface Velocities Near Shore
Authors: Smith Jerome A.
Published: July 2008

The nearshore environment is complex, with many competing dynamical elements. Surface waves and edge waves (a form of surface wave trapped to the shore) can generally be separated from other forms of motion because of their fast propagation speeds. However, other motions such as internal waves, shear waves, density flows, and isolated vortex pairs can move at comparable speeds. A tool to help separate these dynamical elements is decomposition of the surface 2D flow into two parts, one nondivergent and the other irrotational (solenoidal and potential flows, respectively). Here, an efficient algorithm for this separation is developed and applied, and two examples are examined from data taken at Duck, North Carolina, in 1997 as part of the SandyDuck experiment. The first example is a fresher-water density flow propagating downcoast (probably from the Chesapeake Bay). It is seen that 1) the wave-driven alongshore flow leads the flow, generating a “surge” of offshore surface flow in its wake; 2) the isolation of the irrotational (2D divergent) part of the flow permits estimates of some dynamical characteristics of the flow; and 3) the nondivergent part of the flow indicates a meander in the alongshore flow that moves downcoast with the surge. The second example is a hypothesized form of isolated vortical structure, such as might be generated by a pulsed rip current that detaches from the shore and bottom and coasts offshore some distance before dissipating. A kinematically self-consistent structure is formulated that would have both divergence and vorticity fields associated with it. However, the observations inspiring the hypothesis are inconclusive, so the existence of such a structure has not been verified.