bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion acoustic soliton in weakly relativistic magnetized electron–positron–ion plasma
Authors: Gill Tarsem Singh , Bains Amandeep Singh , Saini Narsehpal Singh
Published: October 2009

A theoretical investigation was made for the ion acoustic wave in a weakly relativistic magnetized electron-positron-ion warm plasma. A Korteweg-de vries equation (KdV) is derived by using a standard reductive perturbation method. It is found that the presence of ion temperature (σ), ratios of positron-to-electron density (β), electron-to-positron temperature (α), and relativistic factor (Ur) significantly modify solitonic behavior. The authors observed that these parameters considerably change the amplitude and width of the solitary wave.
Comment on Solutions of the Duffin–Kemmer–Petiau equation for a pseudoscalar potential step in (1+1) dimensions
Authors: Cardoso T. R. , Castro L. B. , de Castro A. S.
Published: October 2009

It is shown that the paper Solutions of the Duffin–Kemmer–Petiau equation for a pseudoscalar potential step in (1+1) dimensions by Abdelmalek Boumali has a number of misconceptions.
Aromaticity in pericondensed cyclopenta-fused polycyclic aromatic hydrocarbons determined by density functional theory nucleus-independent chemical shifts and the Y-rule — Implications in oil asphaltene stability
Authors: Ruiz-Morales Yosadara
Published: October 2009

The characterization of the stability of the fused aromatic region (FAR) in oil asphaltenes in terms of kinetic and thermodynamic stability is primary. Such an understanding is important if we are to get the optimal use from the heavy fraction of any crude oil. The FAR region is composed of pericondensed cyclopenta-fused polycyclic aromatic hydrocarbon compounds (CPPAHs) with N, S, and O heteroatoms. The Clar model, which states that the most important representation of a PAH is one having the maximum number of disjoint π-sextets, depicted by inscribed circles, and a minimum number of fixed double bonds, captures the essence of the kinetic and thermodynamic stability arguments. This model is readily employed for complex aromatics of the sort to be considered for asphaltenes. In the present research we prove that the aromaticity of CPPAHs can be assessed by using the qualitative easy-to-apply Y-rule. In the literature, it is proven that the Y-rule is applicable to elucidate the aromaticity of benzenoid PAHs and it has been validated for pericondensed benzenoid PAHs but not for pericondensed CPPAHs. Here, we verify that it is applicable for CPPAHs. The applicability of the Y-rule has been theoretically proven by comparing the π-electronic distribution obtained with it with the one obtained from nucleus-independent chemical shift (NICS) calculations at the density functional theory (DFT) level. The importance of doing this is that due to the polydispersity in the composition of the oil asphaltenes, and to understand their aromatic core structure, it is necessary to be able to asses the aromaticity of many cyclopenta-fused PAHs (possibly more than 500), of different sizes (up to 15 rings between hexagons and pentagons), and different spatial rearrangements in a quick but realistic and effective way. To try to do this with NICS will be very time consuming and computationally expensive, especially in the case of big systems.
Jones and magnetoelectric birefringence of pure substances — A computational study
Authors: Rizzo Antonio , Shcherbin Dmitry , Ruud Kenneth
Published: October 2009

We present the first investigation of condensed-phase effects on the Jones (and magnetoelectric) birefringence of a set of nondipolar (CCl4 and CS2) and dipolar (nitro- and chloro-benzene) molecules using a recent implementation of the polarizable continuum model for cubic response functions at the time-dependent density-functional level of theory. The condensed-phase calculations have been performed on the neat liquids of the sample molecules using a nonequilibrium solvation scheme to properly account for the solute–solvent interactions in the presence of a frequency-dependent electromagnetic field. It is demonstrated that the condensed-phase effects as modelled by the polarizable continuum model can be substantial, increasing the observable birefringence by more than sixty percent in the case of CCl4, and by a factor of more than three for CS2. Solvent effects are also substantial for the dipolar molecules, leading to an enhancement by a factor of roughly five for nitrobenzene and by a bit less than 30% for chlorobenzene. Comparison is made with the results of experiment. Our calculated anisotropies confirm that the effect is below current experimental detection limits for CCl4 and CS2. We compute Jones constants of the same order of magnitude as the upper limits given in experiment for nitro- and chlorobenzene.
The analog of Koopmans’ theorem for virtual Kohn–Sham orbital energies
Authors: Gritsenko Oleg , Baerends Evert Jan
Published: October 2009

An analog of Koopmans’ theorem is formulated for the energies, εa, of virtual Kohn–Sham (KS) molecular orbitals (MOs) from the requirement that the KS theory provides, in principle, not only the exact electron density, but also its exact response. The starting point is the Kohn–Sham analog of Koopmans’ theorem, relating the vertical ionization energies, Ii, to the energies, εi, of the occupied MOs ( Chong, D.P.; Gritsenko, O.V.; Baerends, E.J. J. Chem. Phys. 2002, 116, 1760 ). Combining this with the coupled-perturbed equations of time-dependent density functional theory (TDDFT), exact relations between the energies, εa, of virtual KS MOs and the excitation energies, ωia, and vertical ionization energies (VIPs), Ii, are obtained. In the small matrix approximation for the coupling matrix K of TDDFT, two limiting cases of these relations are considered. In the limit of a negligible matrix element, Kia,ia, the energy, εa, can be interpreted as (minus) the energy of ionization from the ?i → ?a excited state, εa ≈ –Ia, where –Ia is defined from the relation Ii = ωia + Ia. This relation breaks down in special cases, such as charge-transfer transitions and the HOMO–LUMO (highest occupied molecular orbital – lowest unoccupied molecular orbital) transition of a dissociating electron-pair bond (also of charge-transfer character). The present results highlight the important difference between virtual orbital energies in the Kohn–Sham model (εa ≈ –Ia) and in the Hartree–Fock model (εa ≈ –Aa). Kohn–Sham differences εa – εi approximate the excitation energy, ωia, while Hartree–Fock differences [Formula: see text] do not approximate excitation energies but approximate the difference of an ionization energy and an electron affinity, Ii – Aa.
Bis(cyclopentadienyl)dihydrido Mo and W complexes as Lewis bases — A computational study about their adducts with BX3(X = F, Cl) and Al(CH3)3
Authors: Amati Mario , Lelj Francesco
Published: October 2009

A computational investigation about the Lewis acid–base adducts between bases Cp2MH2(M = Mo, W) and acids BX3(X = F, Cl) and Al(CH3)3is presented. Density functional methods based on pure and hybrid correlation-exchange functionals and relativistic corrections based on the zero order relativistic approximation (ZORA) have been applied. A comparison with experimental data has been addressed to give insights about the nature of the acid–base interaction with the aim to evaluate the role of the transition metal in charge donation toward the acid centre. In this respect, the likelihood of proposed criteria for recognizing the presence of transition-metal direct charge donation has been discussed.
Catalyzed β scission of a carbenium ion III — Scission observed in ab initio molecular dynamics simulations
Authors: Berner Greg M. , East Allan L. L.
Published: October 2009

The β scission (cracking) of branched carbenium ions have been observed in molecular dynamics simulations, possibly for the first time. Simulations were performed with molecular dynamics based on PW91 density functional theory, and which included three-dimensional periodic boundary replication of the unit cell to mimic long-range bulk effects. A rising-temperature algorithm was used to encourage reaction within the narrow time windows (∼10 ps) of the simulations. Twenty-eight simulations were performed, featuring alkyl ions in three different catalytic systems: the ionic liquid, [(C5H5NH+)5(Al2Cl7−)6]−, the chabazite zeolite, [AlSi23O48]−, and the chabazite zeolite, [Al4Si20O45(OH)3]−. Twenty-four runs began with unbranched sec-n-alkyl ions, but only one exhibited β scission, and only after branching to a tertiary ion and under extreme heating. In contrast, the four simulations that began with branched alkyl ions were all successful in demonstrating β scission at lower temperatures: 2,4,4-trimethyl-2-pentyl ion and 2,4-dimethyl-2-hexyl ion in each of the first two catalysts. The lifetimes of desorbed alkyl ions in the chabazite models were < 5 ps at 1000–1500 K. The β scission results support the classical Weitkamp et al. ( Appl. Catal. 1983, 8, 123 ) mechanism over the nonclassical Sie ( Ind. Eng. Chem. Res. 1992, 31, 1881 ) and the chemisorping Kazansky et al. ( J. Catal. 1989, 119, 108 ) mechanisms.
Theoretical prediction of O–H, Si–H, and Si–C σ-bond activation reactions by titanium(IV)–imido complex
Authors: Ochi Noriaki , Nakao Yoshihide , Sato Hirofumi , Sakaki Shigeyoshi
Published: October 2009

The O–H σ-bond activation of methanol, the Si–H σ-bond activation of silane, and the Si–C σ-bond activation of methylsilane by titanium(IV)–imido complex (Me3SiO)2Ti(NSiMe3) were theoretically investigated with DFT and MP2 to MP4(SDQ) methods. The O–H σ-bond activation of methanol occurs with small activation barrier (Ea) of 7.1 (14.6) kcal/mol and large exothermicity (Eexo) of 65.8 (61.4) kcal/mol to afford (Me3SiO)2Ti(OCH3)[NH(SiMe3)], indicating that the O–H σ-bond activation occurs easier than the C–H σ-bond activation (Ea= 14.6 (21.5) kcal/mol and Eexo= 22.7 (16.5) kcal/mol), where DFT- and MP4(SDQ)-calculated values are presented without and in parenthesis hereafter. Though the OCH3group becomes anionic and the H atom becomes proton-like in this activation reaction, population changes more moderately occur than those of the C–H σ-bond activation. This is because the H–OCH3bond is already polarized in methanol. In the Si–H σ-bond activation, two reaction courses were investigated; in one course, the product is (Me3SiO)2Ti(SiH3)[NH(SiMe3)] in which the H atom and the SiH3group are bound to the N atom and the Ti center, respectively, while in the other course the product is (Me3SiO)2Ti(H)[N(SiH3)(SiMe3)] in which the H atom and the SiH3group are bound to the Ti center and the imido N atom, respectively. Though the former reaction occurs with small Eavalue and large exothermicity, the latter reaction occurs easier with further smaller Eavalue of 2.6 (4.3) kcal/mol and larger Eexovalue of 32.5 (34.1) kcal/mol than those of the former reaction. This is because the Ti–H bond energy is much larger than the Ti–SiH3one. The Si–C σ-bond activation occurs with moderate activation barrier of 19.1 (18.6) kcal/mol and considerably large exothermicity of 33.9 (37.7) kcal/mol. Based on these results, we wish to propose the theoretical prediction that the titanium(IV)–imido complex is useful for O–H, Si–H, and Si–C σ-bond activation reactions.
A comparative study on the LDA + U and hybrid functional methods on the description of the electronic structure of YTiO3 under high pressure
Authors: Song Z. , Yang J. J. , Tse J. S.
Published: October 2009

The electronic structures of YTiO3 under pressure have been studied with LDA + U (local density approximation + Hubbard parameter) and hybrid functional methods. From matching the experimental band gaps, the Hubbard U and hybrid functional mixing parameters were determined. It is found that both parameters vary with the pressure. Analysis of the electronic structures indicates that the description of the chemical bonding is also dependent on the method of choice.
Does a fungal species drive ectomycorrhizal root traits in Alnus spp.?
Authors: Ostonen Ivika , Tedersoo Leho , Suvi Triin , Lõhmus Krista
Published: October 2009

Ectomycorrhizal (EcM) fungi contribute significantly to the shaping of short-root morphology, playing an important role in balancing the costs and benefits of root growth and nutrient uptake and exchange in boreal forests. We aimed to assess the effect of various EcM fungal taxa on root traits at seven sites dominated by grey alder, Alnus incana (L.) Moench, and black alder, Alnus glutinosa (L.) Gaertn. Mean root size, specific root length, specific root area, root tissue density, and root-tip frequency of EcM short roots were measured in EcM anatomotypes in relation to the effects of host species, soil moisture level, and nutrient status. Redundancy analysis revealed that anatomotype, alder species, site, and soil parameters (N, P, K, Ca, and Mg concentrations, pH, organic-matter content) accounted for 42.3% (p < 0.001) of the total variation in EcM root morphology. Variation decreased in the following order: anatomotypes (27.9%) > soil parameters and sites (19.9%) > alder species (5.1%). EcM fungus species had the primary influence on EcM short-root size. EcM roots of the dominant anatomotype, Alnicola spp., had the highest specific root length and specific root area in both alder species. Short-root morphology depends most strongly on the fungal taxa involved, which indicates that the type of mycobiont has an important influence on the functional properties of fine roots.
Canopy and emergent white spruce in “pure” broadleaf stands: frequency, predictive models, and ecological importance
Authors: Cumming Steve , Trindade Mariana , Greene David , Macdonald S. Ellen
Published: October 2009

In mixedwood boreal forests of western Canada, stands classified as “pure deciduous” by forest inventories sometimes contain a few large white spruce (Picea glauca (Moench) Voss) trees among or emerging from the canopy. These trees are important as regeneration seed sources and for habitat structure. Neither their abundance nor the characteristics of stands in which they occur have previously been quantified. Of 275 “pure aspen” stands in northeastern Alberta, 19.6% contained at least one such spruce detectable in an aerial photograph. These trees were found in stands across the range of sampled canopy heights, densities, age classes, and stand sizes and were often present in the interior of stands, not just on the perimeter. The frequency of 3 ha cells containing at least one spruce was related to (i) stand shape and size, (ii) amount of mature white spruce in adjacent forest, (iii) canopy height, (iv) stand age, and (v) stand density. We conclude that such trees are relatively abundant and widely distributed within the boreal mixedwood forests of Alberta. There is presently no provision to maintain this landscape element within managed forests. More information is needed to determine if or how they should be considered in forest management planning.
Quantifying tree and forest bark structure with a bark-fissure index
Authors: MacFarlane David W. , Luo Aidong
Published: October 2009

Tree bark provides habitat for many organisms in forest ecosystems, but forest bark structure is typically not considered when important forest structural attributes are discussed. We describe a new metric for quantifying bark structure: a bark-fissure index (BFI). We examined species-specific changes in the frequency and depth of bark fissures caused by both horizontal and vertical splitting of bark layers for trees of different sizes and found that BFI generally scaled exponentially with stem diameter, with distinctively different patterns for 15 different tree species. We found a strong correlation between BFI and tree species preferences of the white-breasted nuthatch, a bark-foraging bird species. We demonstrate how BFI can be scaled up to define forest-scale bark structure using simple stand structural data, such as stand tables. This research contributes a new, objective, and repeatable way of quantifying tree and forest bark structure using simple bark measurements.
Modeling the effect of changing market conditions on mountain pine beetle salvage harvesting and structural changes in the British Columbia forest products industry
Authors: Schwab Olaf , Maness Thomas , Bull Gary , Roberts Don
Published: October 2009

This paper describes the development and implementation of Cambium, an agent-based forest sector model for strategic analysis. This model is designed as a decision-support tool for assessing the effects that changes in product demand and resource inventories can have on the structure and economic viability of the forest sector. Cambium models aggregate product supply as an emergent property of individual companies’ production decisions and stand-level ecological processes. Modeling the forest-products sector as a group of interacting autonomous economic agents makes it possible to include production capacity dynamics and the potential for mill insolvencies as factors in analyzing the effects of market and forest inventory based disturbances. The utility of this model is tested by assessing the impacts of a market downturn in the US forest products market on forest industry structure and mountain pine beetle ( Dendroctonus ponderosae Hopkins) salvage harvesting in British Columbia, Canada. Simulation results indicate a significant medium-term timber supply shortage; reduced stumpage revenues; intensive cost competition among primary wood-products manufacturers; and a large number of insolvencies in the panel, lumber, and pulp sectors.
Making monitoring manageable: a framework to guide learning
Authors: Price Karen , Daust Dave
Published: October 2009

Resource managers, planners, and the public are unified in their calls for monitoring of land-use plans. Unfortunately, many monitoring initiatives fall short of their potential for several reasons: indicators are not explicitly linked to objectives, hindering feedback to planning; knowledge is not represented in a manner that facilitates learning; and monitoring priorities are driven subjectively. We describe a framework that links indicators to existing objectives, presenting knowledge as hypotheses about the probability of achieving an objective as a function of various indicator levels. Uncertainty is explicitly included in the models. The framework can be used for management decision support and to prioritize objectives for implementation, effectiveness, and validation monitoring, and research. Monitoring priority is determined first by probability of success and uncertainty and then by the importance of an objective. We present a case study for the Babine Watershed, an area in the interior of British Columbia with high resource values and decades of controversy and ineffective monitoring. The framework sifted through existing objectives to focus effort on those most critical to monitor. By concentrating on publicly derived, regionally applicable objectives and strategies taken from existing land-use plans, the framework provided relevant results and enabled rapid feedback.
Determining factor of xylem maturation in Eucalyptus grandis planted in different latitudes and climatic divisions of South America: a view based on fiber length
Authors: Kojima Miho , Yamaji Fabio Minoru , Yamamoto Hiroyuki , Yoshida Masato , Saegusa Kouichiro
Published: October 2009

The objective of this study was to determine the factor of xylem maturation in Eucalyptus grandis W. Hill ex Maid. planted in four different latitudes and climatic divisions of South America, based on the pattern of the radial distribution of fiber length. In the plantation closest to the equator, the extent of juvenile wood is determined by distance from the pith and is consistent from tree to tree, regardless of growth rate. In contrast, in the plantation farthest from the equator, xylem maturation is controlled by cambial age and varies from tree to tree, depending on growth rate. To produce as much mature wood as early as possible in E. grandis planted closer to the equator, lateral growth should be accelerated from the early growing stage, because the formation of mature wood starts after a certain trunk diameter is reached. Conversely, in plantations far from the equator, it is necessary to first arrest lateral growth at an early growth stage and then accelerate lateral growth after a certain cambium age is reached.
Genetic analysis of longitudinal height data using random regression
Authors: Wang Chunkao , Andersson Bengt , Waldmann Patrik
Published: October 2009

Genetic analysis of forest longitudinal height data using random regression (RR) has the potential to be attractive to tree breeders because of its advantages for selection at early ages. Our study provides an example of implementation of RR to forest tree height growth data. The data set comes from the Swedish Scots pine ( Pinus sylvestris L.) breeding program with a pedigree over three generations and consists of 899 trees with reconstructed phenotypic height records for 16 years. Legendre polynomials and B-splines were used as base functions in RR models. The restricted maximum likelihood method was employed to estimate (co)variance parameters. Results show that heritability increased with age, except for early ages (years 1 to 4). In general, slightly higher heritabilities were found for the RR model than for the single-trait and paired-trait analyses for most ages. Moreover, the heritabilities obtained with B-splines as the base function tended to be somewhat higher than those obtained with Legendre polynomials. The RR method provides a promising approach for estimating genetic parameters of longitudinal data that can be used in early selection. However, application to real data from other species and to simulated data is needed before general breeding recommendations can be established.
Comparing indices of understory light availability between hemlock and hardwood forest patches
Authors: Tobin Michael F. , Reich Peter B.
Published: October 2009

We evaluated whether two indices of light availability resolved differences among microsites within deeply shaded understories (<12% of above-canopy photosynthetic photon flux density (PPFD)) and also whether marked differences in forest canopy structure affected how the two indices related to direct measures of incident photosynthetically active radiation (PAR). Incident PAR was measured with gallium–arsenide–phosphide photodiodes at numerous points in two adjacent forest patches in Michigan, USA: one dominated by the evergreen conifer eastern hemlock ( Tsuga canadensis (L.) Carrière), and the other by the deciduous hardwood sugar maple ( Acer saccharum Marsh.). The two indices tested were canopy openness, measured with the LI-COR LAI-2000 plant canopy analyzer, and the percentage of above-canopy PPFD measured in the understory during overcast conditions (%PPFD). Canopy openness and %PPFD did not effectively predict the long-term mean of daily PPFD. However, both indices reliably predicted the long-term mean of daily median PPFD, an alternative standard of directly measured incident PAR that reduces the relative contribution of sunflecks. The relationships of both indices with mean daily median PPFD differed between hemlock and hardwood patches. Hence, the effect of canopy structure should be considered when using these indices to draw conclusions about differences in light availability between forest patches, particularly when narrow ranges of light availability in deep shade are important.
APPROACH OF THE AZIMUTHAL AND MAGNETIC QUANTUM NUMBERS l AND m TO REPRESENTATION OF A CUBIC DEFORMATION OF su(2) ALGEBRA
Authors: FAKHRI H. , HASHEMZADEH R.
Published: October 2009

It is shown that the space of spherical harmonics [Formula: see text] whose 2l - m = p - 1 is given, represent irreducibly a cubic deformation of su(2) algebra, the so-called su Φp(2), with deformation function as [Formula: see text]. The irreducible representation spaces are classified in three different bunches, depending on one of values 3k - 2, 3k - 1 and 3k, with k as a positive integer, to be chosen for p. So, three different methods for generating the spectrum of spherical harmonics are presented by using the cubic deformation of su(2). Moreover, it is shown that p plays the role of deformation parameter.
META-STABLE BRANE CONFIGURATIONS OF MULTIPLE PRODUCT GAUGE GROUPS WITH ORIENTIFOLD 6 PLANE
Authors: AHN CHANGHYUN
Published: October 2009

Starting from an [Formula: see text] supersymmetric electric gauge theory with the gauge group [Formula: see text] with fundamentals for each gauge group, the bifundamentals, a symmetric flavor and a conjugate symmetric flavor for SU (Nc), we apply Seiberg dual to each gauge group, obtain the [Formula: see text] supersymmetric dual magnetic gauge theories with dual matters including the gauge singlets, and describe the intersecting brane configurations of type IIA string theory corresponding to the meta-stable nonsupersymmetric vacua of this gauge theory. We also discuss the case where a symmetric flavor is replaced by an antisymmetric flavor. Next we apply to the case for [Formula: see text] supersymmetric electric gauge theory with the gauge group [Formula: see text] with flavors for each gauge group and the bifundamentals. Finally, we describe the case where the orientifold 6-plane charge is reversed.
ELECTROWEAKSU(4)L⊗U(1)YMODELS WITHOUT EXOTIC ELECTRIC CHARGES
Authors: PALCU ADRIAN
Published: October 2009

For the particular class of SU (4)L⊗ U (1)Yelectroweak models without exotic electric charges, some plausible phenomenological predictions — such as the boson mass spectrum and charges of all the fermions involved therein — are made by using the algebraical approach of the exactly solving method for gauge models with high symmetries. Along with the one-parameter resulting mass scale (to be confirmed at TeV scale in LHC) our approach predicts the exact expressions of the charges (both electric and neutral) in the fermion sector, while all the Standard Model phenomenology is naturally recovered.
MATRIX FORMULATION OF SUPERSPACE ON 1D LATTICE WITH TWO SUPERCHARGES
Authors: ARIANOS SERGIO , D'ADDA ALESSANDRO , FEO ALESSANDRA , KAWAMOTO NOBORU , SAITO JUN
Published: October 2009

Following the approach developed by some of the authors in recent papers and using a matrix representation for the superfields, we formulate an exact supersymmetric theory with two supercharges on a one-dimensional lattice. In the superfield formalism supersymmetry transformations are uniquely defined and do not suffer of the ambiguities recently pointed out by some authors. The action can be written in a unique way and it is invariant under all supercharges. A modified Leibniz rule applies when supercharges act on a superfield product and the corresponding Ward identities take a modified form but hold exactly at least at the tree level, while their validity in presence of radiative corrections is still an open problem and is not considered here.
Punitive Damages
Authors: Vidmar Neil , Wolfe Matthew W.
Published: October 2009

Punitive damages is a controversial topic in American law. Defenders of punitive damages see these awards as a useful mechanism for sanctioning and deterring egregious conduct, particularly the conduct of corporations not subject to the sanctions of the criminal law but still harmful to society. Opponents of punitive damages argue that they are capriciously and unfairly awarded by juries and that the threats of large punitive awards stifle the invention of new products and harm America's business competitiveness in the world. Much of the focus of the controversy involves the role of the jury in awarding punitive damages. This article presents the historical and doctrinal background to punitive damages and then reviews the empirical evidence bearing on the subject. It concludes by presenting future research issues.
Neurophysiological evaluation of convergent afferents innervating the human esophagus and area of referred pain on the anterior chest wall
Authors: Hobson Anthony R. , Chizh Boris , Hicks Kirsty , Aziz Qasim , Worthen Sian , Lawrence Philip , Dewit Odile , Boyle Yvonne , Dukes George
Published: October 2009

Noxious stimuli in the esophagus cause pain that is referred to the anterior chest wall because of convergence of visceral and somatic afferents within the spinal cord. We sought to characterize the neurophysiological responses of these convergent spinal pain pathways in humans by studying 12 healthy subjects over three visits (V1, V2, and V3). Esophageal pain thresholds (Eso-PT) were assessed by electrical stimulation and anterior chest wall pain thresholds (ACW-PT) by use of a contact heat thermode. Esophageal evoked potentials (EEP) were recorded from the vertex following 200 electrical stimuli, and anterior chest wall evoked potentials (ACWEP) were recorded following 40 heat pulses. The fear of pain questionnaire (FPQ) was administered on V1. Statistical data are shown as point estimates of difference ± 95% confidence interval. Pain thresholds increased between V1 and V3 [Eso-PT: V1-V3 = −17.9 mA (−27.9, −7.9) P < 0.001; ACW-PT: V1-V3 = −3.38°C (−5.33, −1.42) P = 0.001]. The morphology of cortical responses from both sites was consistent and equivalent [P1, N1, P2, N2 complex, where P1 and P2 are is the first and second positive (downward) components of the CEP waveform, respectively, and N1 and N2 are the first and second negative (upward) components, respectively], indicating activation of similar cortical networks. For EEP, N1 and P2 latencies decreased between V1 and V3 [N1: V1-V3 = 13.7 (1.8, 25.4) P = 0.02; P2: V1-V3 = 32.5 (11.7, 53.2) P = 0.003], whereas amplitudes did not differ. For ACWEP, P2 latency increased between V1 and V3 [−35.9 (−60, −11.8) P = 0.005] and amplitudes decreased [P1-N1: V1-V3 = 5.4 (2.4, 8.4) P = 0.01; P2-N2: 6.8 (3.4, 10.3) P < 0.001]. The mean P1 latency of EEP over three visits was 126.6 ms and that of ACWEP was 101.6 ms, reflecting afferent transmission via Aδ fibers. There was a significant negative correlation between FPQ scores and Eso-PT on V1 ( r = −0.57, P = 0.05). These data provide the first neurophysiological evidence of convergent esophageal and somatic pain pathways in humans.
Inflammatory cells regulate p53 and caspases in acute pancreatitis
Authors: Nakamura Yuji , Do Jae Hyuk , Yuan Jingzhen , Odinokova Irina V. , Mareninova Olga , Gukovskaya Anna S. , Pandol Stephen J.
Published: October 2009

The inflammatory response during pancreatitis regulates necrotic and apoptotic rates of parenchymal cells. Neutrophil depletion by use of anti-polymorphonuclear serum (anti-PMN) increases apoptosis in experimental pancreatitis but the mechanism has not been determined. Our study was designed to investigate signaling mechanisms in pancreatic parenchymal cells regulating death responses with neutrophil depletion. Rats were neutrophil depleted with anti-PMN treatment. Then cerulein pancreatitis was induced, followed by measurements of apoptosis signaling pathways. There was greater activation of executioner caspases-3 in the pancreas with anti-PMN treatment compared with control. There were no differences between these groups of animals in mitochondrial cytochrome c release or in activities of initiator caspase-8 and -9. However, there was greater activation of caspase-2 with anti-PMN treatment during cerulein pancreatitis. The upstream regulation of caspases-2 includes p53, which was increased; the p53 negative regulator, Mdm2, was decreased by anti-PMN treatment during cerulein pancreatitis. In vitro experiments using isolated pancreatic acinar cells a pharmacological inhibitor of Mdm2 increased caspase-2/-3 activities, and an inhibitor of p53 decreased these activities during cholecystokinin-8 treatment. Furthermore, experiments using the AR42J cell line Mdm2 small interfering RNA (siRNA) increased caspase-2/-3 activities, and p53 siRNA decreased these activities during cholecystokinin-8 treatment. These results suggest that during acute pancreatitis the inflammatory response inhibits apoptosis. The mechanism of this inhibition involves caspase-2 and its upstream regulation by p53 and Mdm2. Because previous findings indicate that promotion of apoptosis decreases necrosis and severity of pancreatitis, these results suggest that strategies to inhibit Mdm2 or activate p53 will have beneficial effects for treatment of pancreatitis.
Stress-induced senescence exaggerates postinjury neointimal formation in the old vasculature
Authors: Khan Sheik J. , Pham Si , Wei Yunteo , Mateo Dania , St-Pierre Melissa , Fletcher Terace M. , Vazquez-Padron Roberto I.
Published: October 2009

This study aims to demonstrate the role of stress-induced senescence in aged-related neointimal formation. We demonstrated that aging increases senescence-associated β-galactosidase activity (SA-β-Gal) after vascular injury and the subsequent neointimal formation (neointima-to-media ratio: 0.8 ± 0.2 vs. 0.54 ± 0.15) in rats. We found that senescent cells (SA-β-Gal+ p21+) were scattered throughout the media and adventitia of the vascular wall at day 7 after injury and reached their maximum number at day 14. However, senescent cells only persisted in the injured arteries of aged animals until day 30. No senescent cells were observed in the noninjured, contralateral artery. Interestingly, vascular senescent cells accumulated genomic 8-oxo-7,8-dihydrodeoxyguanine, indicating that these cells were under intense oxidative stress. To demonstrate whether senescence worsens intimal hyperplasia after injury, we seeded matrigel-embedded senescent and nonsenescent vascular smooth muscle cells around injured vessels. The neointima was thicker in arteries treated with senescent cells with respect to those that received normal cells (neointima-to-media ratio: 0.41 ± 0.105 vs. 0.26 ± 0.04). In conclusion, these results demonstrate that vascular senescence is not only a consequence of postinjury oxidative stress but is also a worsening factor for neointimal development in the aging vasculature.
Control of gluconeogenic genes during intense/prolonged exercise: hormone-independent effect of muscle-derived IL-6 on hepatic tissue and PEPCK mRNA
Authors: Banzet Sébastien , Koulmann Nathalie , Simler Nadine , Sanchez Hervé , Chapot Rachel , Serrurier Bernard , Peinnequin André , Bigard Xavier
Published: October 2009

Prolonged intense exercise is challenging for the liver to maintain plasma glucose levels. Hormonal changes cannot fully account for exercise-induced hepatic glucose production (HGP). Contracting skeletal muscles release interleukin-6 (IL-6), a cytokine able to increase endogenous glucose production during exercise. However, whether this is attributable to a direct effect of IL-6 on liver remains unknown. Here, we studied hepatic glycogen, gluconeogenic genes, and IL-6 signaling in response to one bout of exhaustive running exercise in rats. To determine whether IL-6 can modulate gluconeogenic gene mRNA independently of exercise, we injected resting rats with recombinant IL-6. Exhaustive exercise resulted in a profound decrease in liver glycogen and an increase in gluconeogenic gene mRNA levels, phosphoenolpyruvate-carboxykinase (PEPCK), glucose-6-phosphatase (G6P), and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), suggesting a key role for gluconeogenesis in hepatic glucose production. This was associated to an active IL-6 signaling in liver tissue, as shown by signal transducer and activator of transcription and CAAT/enhancer binding protein-β phosphorylation and IL-6-responsive gene mRNA levels at the end of exercise. Recombinant IL-6 injection resulted in an increase in IL-6-responsive gene mRNA levels in the liver. We found a dose-dependent increase in PEPCK gene mRNA strongly correlated with IL-6-induced gene mRNA levels. No changes in G6P and PGC-1α mRNA levels were found. Taken together, our results suggest that, during very demanding exercise, muscle-derived IL-6 could help increase HGP by directly upregulating PEPCK mRNA abundance.
Endurance exercise training effects on body fatness, V̇o2max, HDL-C subfractions, and glucose tolerance are influenced by aPLINhaplotype in older Caucasians
Authors: Jenkins Nathan T. , McKenzie Jennifer A. , Damcott Coleen M. , Witkowski Sarah , Hagberg James M.
Published: October 2009

Perilipins are lipid droplet-coating proteins that regulate intracellular lipolysis in adipocytes. A haplotype of two perilipin gene ( PLIN) single nucleotide polymorphisms, 13041A>G and 14995A>T, has been previously associated with obesity risk. Furthermore, the available data indicate that this association may be modified by sex. We hypothesized that this haplotype would associate with body fatness, aerobic fitness, and a number of cardiovascular (CV) risk factor phenotypes before and after a 6-mo endurance exercise training program in sedentary older Caucasians. The major haplotype group (13041A/14995A; n = 57) had significantly lower body mass index (BMI) and body fatness compared with noncarriers of the AA haplotype ( n = 44) before the training intervention. Training improved body composition in both groups, but fatness remained higher in noncarriers than AA carriers after training. This fat retention in noncarriers blunted their maximal oxygen uptake (V̇o2max) adaptation to training. Female noncarriers had substantially higher concentrations of several conventionally and NMR-measured HDL-C subfractions than male noncarriers before and after training, but only minimal differences were found between the sexes in the AA haplotype group. Haplotype group differences in baseline and after-training responses to an oral glucose tolerance test (OGTT) also differed by sex, as noncarrier men had the highest baseline area under the insulin curve (insulin AUC), but were the only group to significantly improve insulin AUC with training. The insulin sensitivity index and plasma glucose responses to the OGTT were more favorable in AA carriers than noncarriers before and after training. Overall, our findings suggest that PLIN variation explains some of the interindividual differences in the response of obesity and CV phenotypes to exercise training. Furthermore, these data contribute to the growing understanding of PLIN as a candidate gene for human obesity and the cardiometabolic consequences of excess adiposity.
Bubble-induced platelet aggregation in a rat model of decompression sickness
Authors: Pontier Jean-Michel , Vallée Nicolas , Bourdon Lionel
Published: October 2009

Previous studies have highlighted that bubble-induced platelet aggregation is a predictor index of decompression sickness (DCS) severity in animals and bubble formation after a single air dive in humans. The present study attempted to investigate plasmatic indexes of the coagulation system and platelet activation in our rat model of DCS. Male Sprague-Dawley rats were assigned to one experimental group with a hyperbaric exposure and one control group maintained at atmospheric pressure. Rats were compressed to 1,000 kPa (90 m saltwater) for 45 min while breathing air. The onset of death time and DCS symptoms were recorded during a 30-min observed period after rats had surfaced. Plasmatic indexes were platelet factor 4 (PF4) for platelet activation, soluble glycoprotein V (sGPV) for thrombin generation, and thrombin-antithrombin complexes for the coagulation system. Blood samples for a platelet count and markers were taken 3 wk before the experimental protocol and within the 30 min after rats had surfaced. We confirmed a correlation between the percent fall in platelet count and DCS severity. Plasmatic levels of sGPV and PF4 were significantly increased after the hyperbaric exposure, with no change in the control group. The present study confirms platelet consumption as a potential index for evaluating decompression stress and DCS severity. The results point to the participation of thrombin generation in the coagulation cascade and platelet activation in bubble-induced platelet aggregation. In our animal model of DCS, the results cannot prejudge the mechanisms of platelet activation between bubble-induced vessel wall injury and bubble-blood component interactions.
Basic Clinical Assessment of Pediatric Malnutrition
Authors: Hartman Corina , Shamir Raanan
Published: October 2009

Screening and assessment for nutritional risk should be a routine part of clinical evaluation. Goals of nutritional assessment are to determine the risk or presence of malnutrition and to provide guidelines for short- and long-term therapy. Nutritional status is assessed through a simple, mainly clinical approach based on medical history, physical examination, anthropometric measurements, dietary intake, body composition and biological parameters. Nutritional status assessment should start by history and physical examination combined with dietary record. When a child is assumed to be at risk of malnutrition, evaluation for inadequate intake, reduced absorption, excessive losses, impaired utilization or increased requirements is needed. Growth is the best indicator of nutritional status. Analysis of growth (weight gain and growth velocity) using growth curves remains the simplest tool for assessing changes in nutritional status. Other anthropometric indices used for the assessment of nutritional status are body mass index, skinfold thickness and mid-arm circumference (MAC). Several classifications are used to define malnutrition, but none has been properly validated for diagnosing malnutrition in children. To date, routine nutritional screening is rarely carried out in pediatric patients due to the lack of a simple and valid nutritional screening tool. An easy-to-use screening tool that has been validated in a variety of pediatric conditions is yet to be developed.
Endocrine Regulation of Feto-Placental Growth
Authors: Fowden Abigail L. , Forhead Alison J.
Published: October 2009

Hormones are both growth stimulatory and growth inhibitory in utero. They regulate tissue growth and development by controlling the rates of cell proliferation, apoptosis and differentiation in many fetal tissues. They also signal the level of resources available for intrauterine growth to the fe- tal tissues and relay back to the placenta the degree of mismatch between the actual fetal nutrient supply and the fetal nutrient demands for growth. They affect intrauterine growth by anabolic and catabolic actions on fetal metabolism and by altering the nutrient transfer capacity and endocrine function of the placenta. By modifying the fetal growth trajectory, hormones have a central role in programming development in utero and in determining the phenotypic outcome of changes in feto-placental growth during adverse intrauterine conditions. This review examines the role of hormones in feto-placental growth with particular emphasis on insulin, the insulin-like growth factors and glucocorticoids.
Future Target Molecules in Antiglaucoma Therapy: TGF-β May Have a Role to Play
Authors: Agarwal Renu , Agarwal Puneet
Published: October 2009

Glaucoma, a leading cause of irreversible blindness, is often associated with increased resistance to aqueous outflow in trabecular tissue. Increased outflow resistance has been attributed to increased extracellular matrix (ECM) deposition in trabecular tissue. A critical balance between the synthesis and breakdown of the components of extracellular tissue is important in keeping the intraocular pressure within the normal range. Multiple mechanisms have been shown to affect ECM turnover in trabecular tissue. In this review, we examine the related literature to understand the role of TGF-β in ECM turnover, in the development and progression of glaucoma, and in possible therapeutic strategies that can be devised by targeting the TGF-β signaling pathways.
Attitudes towards Diagnostic Tests and Therapies for Dry Eye Disease
Authors: Graham Joanna E. , McGilligan Victoria E. , Berrar Daniel , Leccisotti Antonio , Moore Jonathan E. , Bron Anthony J. , Moore Tara C.B.
Published: October 2009

Aim: The purpose of this study was to survey the attitudes of optometrists and ophthalmologists, located in a number of different countries, towards diagnostic tests and therapies for dry eye disease. Methods: A web-based questionnaire was used to survey attitudes using forced-choice questions and Likert scales. Results: Sixty-one respondents (23 ophthalmologists and 38 optometrists) reported a wide range of patient dry eye symptoms. A large variation in use of diagnostic tests was noted. Patient symptoms and fluorescein staining were reported to be significantly more valuable and more frequently performed than any other test. Artificial tear supplements and improved lid hygiene were the preferred therapeutic options selected by the entire group. The results demonstrated a wide variation in attitudes in relation to satisfaction with the range of available diagnostic and therapeutic options. Conclusions: This study indicates that the interest for the issue of dry eye is relatively limited amongst eye professionals, as demonstrated by the poor participation in the questionnaire.
Frequency of Congenital Nevi, Nevi spili and Café-au-Lait Spots and Their Relation to Nevus Count and Skin Complexion in 939 Children
Authors: Sigg Christian , Pelloni Francesco , Schnyder Urs W.
Published: October 2009

To determine the prevalence of congenital melanonevocytic nevi (CMN), of so-called congenital nevus-like nevi (CNLN), nevi spili (NS) and café-au-lait spots (CLS) in childhood, a series of 939 children aged 8–16 years had total skin examination. CMN/CNLN were observed in a frequency of 5.9% NS in 2.1 % and CLS even in 32.7%. Except CLS (which occurred more frequently in boys) all of these lesions were equally represented in both sexes. According to the classification of Kopf and coworkers, 44/55 CMN/CNLN were small and 11/55 medium-sized. CMN/CNLN affected preferentially trunk and upper limbs while head and neck were spared. Such nevi occurred more frequently in dark types of skin complexion and showed a tendency to be more frequent in groups of patients with increased average number of acquired melanonevocytic nevi. Remarkably, CLS were also found in 23/55 (41.7%) children with CMN/CNLN and in 12/20 (60%) children with NS (in a higher frequency than such combinations have to be expected). Compared with the data from other studies both CMN/CNLN and CLS in our patients were observed in highest prevalence in the literature. Since the frequency of CLS in adults is much lower, it cannot be ruled out that some of the CLS disappear in adolescence.
Cutaneous Necrosis Associated with the Lupus Anticoagulant
Authors: Francès C. , Tribout B. , Boisnic S. , Drouet L. , Piette A.M. , Piette J.C. , Blétry O. , Wechsler B. , Godeau P.
Published: October 2009

Extensive cutaneous necrosis of the limbs with sudden onset was observed in 3 women suffering from benign systemic lupus erythematosus. All 3 had a circulating anticoagulant and a positive venereal diseases reference laboratory test without anticardiolipin antibodies.They were successfully treated with pulse methylprednisolone therapy and plasmapheresis. The necrosis-lupus anticoagulant relationship is discussed due to the absence of another possible etiology for cutaneous necrosis and the latter’s histological aspect, i.e. thromboses of the dermal and hypodermal vessels without vasculitis. This cutaneous necrosis resembles that observed in congenital protein C deficiencies and favors the hypothesis of interaction between the lupus anticoagulant and the protein C-S complex.
Sea-Blue Histiocyte Syndrome with Cutaneous Involvement
Authors: Zina A.M. , Bundino S. , Pippione M.
Published: October 2009

A patient with infiltration of the skin resulting in eyelid swelling and facial nodules was recognized as a case of sea-blue histiocyte syndrome with cutaneous involvement. Typical sea-blue histiocytes were found in the skin and confirmation was provided by electron microscopy. Hepatosplenomegaly, lung infiltrates and bone marrow involvement were the other symptoms. The relationship between sea-blue histiocyte syndrome and adult Niemann-Pick disease is also discussed.