bluuebunny/crossref_metadata_2025 huggingface dataset:
Rare earth distribution in Archean granitoid plutons of the Wabigoon volcanic–plutonic belt, northwestern Ontario
Authors: Birk Dieter , Koljonen Tapio , Rosenberg R. J.
Published: October 2009

Rare earths (La to Lu, Y) are investigated for five Archean granitoid stocks of Kenoran age that intrude the Wabigoon volcanic–plutonic belt. Homogeneous granodiorites are characterized by low total rare earth concentrations (ΣREE), with chondrite-normalized REE patterns that show steep negative slopes, no Eu anomalies, and enrichment of Lu. A hypabyssal porphyry of possible volcanic affiliation displays similar REE patterns, but is more depleted in heavy REE. Zone plutons yield patterns of steep slope, no Eu anomalies, with or without Lu enrichment. REE concentrations decrease from monzodioritic margins, to granodioritic cores, to aplitic apophyses.These plutons carry REE concentrations similar to the Canadian Shield average, but notably lower than some published averages for granitoids. No secular change is evident for the Archean interval.ΣREE decreases during differentiation with no appreciable fractionation of heavy over light REE, until the end stages. Late differentiates suffer depletion in heavy REE by hornblende fractionation. Lu enrichment correlates with deuteric metasomatism, as evidenced by microcline megacrysts. Eu anomalies are absent because fractionation of divalent Eu is prevented by high concentrations of Sr and Ba.Quantitative source modeling should consider the complete magma history of emplacement, crystallization, and deuteric metasomatism.
Down-plunge viewing: a rapid method for estimating the strain ellipsoid for large clasts in deformed rocks
Authors: Stauffer Mel R. , Burnett A. I.
Published: October 2009

The shape of the strain ellipsoid for an aggregate of clasts with initially isotropic fabric can be estimated from measurements made while viewing the clasts along the plunges of at least two of the axes of strain, even though the outcrop faces are not orthogonally related to any of the strain axes. The accuracy of this estimation depends on the shape of the strain ellipsoid and the obliquity between the strain axes and the outcrop faces.Application of the technique to conglomerates of the Missi Group near Flin Flon, Manitoba and Saskatchewan, suggests that in moderately to highly deformed rocks it can be useful for comparing the strain behaviour of clasts with different competences as well as for determining regional strain variations.
Gravity and structure of an active margin—British Columbia and Washington
Authors: Riddihough Robin P.
Published: October 2009

Active subduction zones around the world have a gravity expression characterized by a linear negative gravity anomaly over the trench and a parallel, linear positive anomaly some 100km inland. Although there are local modifications, the same pattern is present in the Pacific northwest across the zone of interaction between the Juan de Fuca and American plates.Previous geophysical interpretations of this region have not specifically used a subduction model but have exposed an apparent conflict between seismic and gravity interpretations of the thickness of the crust under Vancouver Island. The position of Vancouver Island in the arc-trench gap of an active margin suggests that a compromise can be achieved by considering the wedge of material overlying the down-going plate to be of high density and low compressional velocity. Such materials have been documented in the laboratory and are typically amphibolite to granulite facies mafic rocks.Proceeding on this assumption, four structural sections across the margin in southern British Columbia and northern Washington show that both seismic and gravity data can be simply incorporated into models fulfilling the main criteria of a subduction zone. Among the features suggested by the construction of these sections are (1) the density of the material of the down-going slab need not increase beyond that of normal lithosphere to satisfy the gravity observations and (2) the down-going slab may increase in dip approximately beneath Georgia Strait and Puget Sound
Upper Silurian stromatoporoids from Somerset Island, Arctic Canada
Authors: Savelle James M.
Published: October 2009

Plexodictyon katriense Nestor, P. heclae n. sp., Diplostroma sp., Actinostroma furyi n. sp., Actinodictyon netsiliki n. sp., and Vicinostachyodes sokolovi (Riabinin) occur in Upper Silurian (middle to late Ludlovian) strata near Creswell Bay, Somerset Island. Faunal and sedimentological evidence suggests the stromatoporoids inhabited predominantly shallow, high energy, near-shore environments.
A DFT/MM analysis of the effect of ligand substituents on asymmetric hydrogenation catalyzed by rhodium complexes with phosphine–phosphinite ligands
Authors: Donald Steven M. A. , Vidal-Ferran Anton , Maseras Feliu
Published: October 2009

DFT and DFT/MM calculations are carried out on the rate-determining step of the addition of dihydrogen to methyl-(N)-acetylaminoacrylate catalyzed by a rhodium catalyst containing a bidentate phosphine–phosphinite ligand. DFT calculations reproduce the experimental results, while DFT/MM calculations do not. The failure of DFT/MM methods for this particular problem is analyzed through a series of calculations with different partitions between the DFT and MM regions, which show that electronic effects of all ligand substituents considered are critical. The analysis of these electronic effects provides key information on the role of each of the substituents in the outcome of the overall catalytic process.
Comprehensive study of some well-known molecular numerical integration methods
Authors: El-Sherbiny Aisha , Poirier Raymond A.
Published: October 2009

In a previous study, we compared, both in terms of accuracy and efficiency, the performance of some of the well-known grids, which use the Becke partitioning scheme for molecular numerical integration. We concluded, based on the number of electrons only, that the MultiExp grid performed well compared with the grids proposed by Becke, Gill et al., and Treutler and Ahlrichs. In this work, we re-examine the performance of the same set of grids in addition to the SG-0 grid and a benchmark grid. These grids are evaluated by integrating the Hartree–Fock electron density to calculate the number of electrons, dipole moment, potential energy, and Coulomb repulsion energy. Our results show that, except for the large benchmark grid, none of these grids were completely satisfactory.
Non-empirical derivation of the parameter in the B88 exchange functional
Authors: Elliott Peter , Burke Kieron
Published: October 2009

The B88 exchange energy density functional (created by Becke in 1988) is a crucial part of the most popular density functional in use today, B3LYP. B88 contains one empirical parameter which was fitted to Hartree–Fock exchange energies for the noble gas atoms. We show how local approximations to exchange become relatively exact under a very specific approach to the limit of large numbers, but the usual gradient expansion does not. The leading corrections can be captured by generalized gradient approximations, producing a non-empirical derivation of the parameter in B88.
Experimental and theoretical investigations of selenium nuclear magnetic shielding tensors in Se–N heterocycles
Authors: Sutrisno Andre , Lo Andy Y.H. , Tang Joel A. , Dutton Jason L. , Farrar Gregg J. , Ragogna Paul J. , Zheng Shaohui , Autschbach Jochen , Schurko Robert W.
Published: October 2009

A preliminary study involving solid-state 77Se NMR spectroscopy and first principles calculations of 77Se NMR parameters in Se–N heterocycles is reported. 77Se CP/MAS NMR spectra of the ring systems reveal expansive selenium chemical shift (CS) tensors, which are extremely sensitive to molecular geometry, symmetry, ligand substitution, and intermolecular contacts. For systems with known crystal structures, hybrid density functional theory (DFT) calculations of selenium nuclear magnetic shielding (NMS) tensors were carried out, and tensor orientations in the molecular frames examined. Additional DFT calculations of selenium NMS tensors are presented, along with a detailed analysis of pairs of occupied and virtual molecular orbitals that give rise to the Se NMS tensors. A new naturalized local molecular orbital (NLMO) analysis under the same DFT framework is also discussed. Collectively, the NMR data and first principles calculations provide understanding of the influences of electronic structure, bonding, and intermolecular interactions on the selenium NMS tensors, allowing for (i) prediction of unknown molecular structures and (ii) insight into the positions of the stereochemically active selenium lone pairs.
Charge density reconstitution from approximate exchange-correlation holes
Authors: Gori-Giorgi Paola , Ángyán János G. , Savin Andreas
Published: October 2009

The electronic charge density and the expectation of any monoelectronic operator can be reconstructed by a density-weighted integral of the exchange-correlation hole. This property can be used to test and improve approximate holes that are not spherically averaged. As an example, we test the Becke–Roussel exhange-hole model in its nonspherical formulation on small atoms, finding that it accurately reproduces the density in the core region, while missing some of the features of the valence and core-valence regions. The same test on the local-density approximation shows poor results, as expected.
Carbon–hydrogen vs. carbon–halogen oxidative addition of chlorobenzene to a cationic iridium(I) system — A density functional theory study
Authors: Wu Hong , Hall Michael B.
Published: October 2009

Density functional theory (DFT) is used to explore the competitive C−H and C−Cl oxidative additions (OA) of chlorobenzene to the cationic Ir(I) complex: [(PNP*)IrI]+ [PNP* = 2,6-bis((dimethylphosphino)methyl)pyridine]. Consistent with experimental results, the calculated activation barrier for C−H OA (ΔG‡ = 10.7 kcal mol–1) is lower than that for C−Cl OA (ΔG‡ = 19.7 kcal mol–1). However, the C−Cl OA product is calculated to be thermodynamically preferred as its ΔGo is 14.3 kcal mol–1 below that for the most stable C−H OA product.
Out of one, many — Using moment expansions of the virial relation to deduce universal density functionals from a single system
Authors: Ayers Paul W. , Rodriguez Juan I.
Published: October 2009

Moment expansions for density functionals are revisited. This allows for a simple proof of the equivalence between the integrodifferential virial relation and the coordinate-scaling equation. The virial relation is then used to show how, starting from an exact and explicit form of a functional for one system, one may deduce the exact functional for other systems with the same number of electrons.
Explorations of many-body relativistic wave equations within a one-dimensional model
Authors: Nooijen Marcel
Published: October 2009

A one-dimensional analog that reflects many of the features of the many-body Dirac equation is considered. The model can be solved numerically using a convenient finite basis discrete variable representation. Both an (unbound) harmonic oscillator potential and a (bound) inverse Gaussian one-particle potential are discussed for interacting particles. In a second thread in the paper, the mass term is neglected in the model many-body Dirac equation, and it is shown that the original equation, which has 2N coupled components for N particles can then be reduced to 2N decoupled one-component equations, which can be solved “analytically” for arbitrary many particles interacting through central two-body potentials.
Mapping wildland fuels and forest structure for land management: a comparison of nearest neighbor imputation and other methods
Authors: Pierce Kenneth B. , Ohmann Janet L. , Wimberly Michael C. , Gregory Matthew J. , Fried Jeremy S.
Published: October 2009

Land managers need consistent information about the geographic distribution of wildland fuels and forest structure over large areas to evaluate fire risk and plan fuel treatments. We compared spatial predictions for 12 fuel and forest structure variables across three regions in the western United States using gradient nearest neighbor (GNN) imputation, linear models (LMs), classification and regression trees (CART), and geostatistical methods (kriging and universal kriging (UK)). Local-scale map accuracy varied considerably across sites, variables, and methods. GNN performed best for forest structure variables in Oregon, but LMs and UK were better for canopy variables and for forest structure variables in Washington and California. Kriging performed poorly throughout, and kriging did not improve prediction accuracy when added to LMs as UK. GNN outperformed CART in predicting vegetation classes and fuel models, complex variables defined by multiple attributes. Regional distributions of vegetation classes and fuel models were accurately represented by GNN and very poorly by CART and LMs. Despite their often limited accuracy at the local scale, GNN maps are useful when information on a wide range of forest attributes is needed for analysis and forest management at intermediate, i.e., landscape to ecoregional, scales.
Predicting volumes by log grades in standing sugar maple and yellow birch trees in southern Quebec, Canada
Authors: Fortin Mathieu , Guillemette François , Bédard Steve
Published: October 2009

Modelling volumes by log grades in standing hardwood trees is often hindered by the nature of the response variable. In this paper, we used a two-part conditional model to account for the excess of zero responses for some log grades. Moreover, this approach was used as a framework to compare three different tree classifications in their ability to predict volumes by log grades in standing yellow birch ( Betula alleghaniensis Britton) and sugar maple ( Acer saccharum Marsh.) trees. A tree grade classification was compared with two preharvest tree classifications based on mortality risk assessment. A cross-validation was also carried out to evaluate the two parts of the model. The results showed that the two-part conditional approach was efficient in this case study. Compared with a general model, the three classifications improved the maximum likelihood. According to the Akaike and Bayesian information criteria, the tree grade classification was the “best” one. All three classifications proved to be better able to distinguish log grade occurrence than log grade volume. Although it implies additional cost, the implementation of the tree grade classification into the preharvest inventories would improve the prediction of volumes by log grades for yellow birch and sugar maple trees.
SU(2) KINETIC MIXING TERMS AND SPONTANEOUS SYMMETRY BREAKING
Authors: LÓPEZ-SARRIÓN J. , ARIAS PAOLA , GAMBOA J.
Published: October 2009

The non-Abelian generalization of the Holdom model, i.e. a theory with two gauge fields coupled to the kinetic mixing term g tr (Fμν(A)Fμν(B)) is considered. Contrarily to the Abelian case, the group structure G×G is explicitly broken to G. For SU(2) this fact implies that the residual gauge symmetry as well as the Lorentz symmetry is spontaneously broken. We show that this mechanism provides masses for the involved particles. Also, the model presents instanton solutions with a redefined coupling constant.
INVERSE SEESAW NEUTRINO MASS FROM LEPTON TRIPLETS IN THE U(1)Σ MODEL
Authors: MA ERNEST
Published: October 2009

The inverse seesaw mechanism of neutrino mass, i.e. [Formula: see text], where ∊L is small, is discussed in the context of the U(1)Σ model. This is a gauge extension of the Standard Model of particle interactions with lepton triplets (Σ+, Σ0, Σ-) as (Type III) seesaw anchors for obtaining small Majorana neutrino masses.
CANONICAL TRANSFORMATIONS IN THREE-DIMENSIONAL PHASE-SPACE
Authors: DERELİ TEKİN , TEĞMEN ADNAN , HAKİOĞLU TUĞRUL
Published: October 2009

Canonical transformation in a three-dimensional phase-space endowed with Nambu bracket is discussed in a general framework. Definition of the canonical transformations is constructed based on canonoid transformations. It is shown that generating functions, transformed Hamilton functions and the transformation itself for given generating functions can be determined by solving Pfaffian differential equations corresponding to that quantities. Types of the generating functions are introduced and all of them are listed. Infinitesimal canonical transformations are also discussed. Finally, we show that the decomposition of canonical transformations is also possible in three-dimensional phase space as in the usual two-dimensional one.
MASS RENORMALIZATION IN A HAMILTONIAN APPROACH
Authors: WEBER AXEL
Published: October 2009

We consider the energies of the one-particle states of relativistic quantum field theories in old-fashioned perturbation theory, and treat their regularization and renormalization from a strictly Hamiltonian perspective. We show that the one-loop diagrams lead to the renormalization of the mass for bosons and fermions identically to covariant perturbation theory, provided an appropriate regularization scheme is used. In particular, we show that a naive spatial momentum cutoff breaks covariance (in the limit where the cutoff is removed) in the case of the one-fermion states.
RAINBOW STATISTICS
Authors: ARZANO MICHELE , BENEDETTI DARIO
Published: October 2009

Noncommutative quantum field theories and their global quantum group symmetries provide an intriguing attempt to go beyond the realm of standard local quantum field theory. A common feature of these models is that the quantum group symmetry of their Hilbert spaces induces additional structure in the multiparticle states which reflects a nontrivial momentum-dependent statistics. We investigate the properties of this "rainbow statistics" in the particular context of κ-quantum fields and discuss the analogies/differences with models with twisted statistics.
META-STABLE BRANE CONFIGURATIONS OF TRIPLE PRODUCT GAUGE GROUPS
Authors: AHN CHANGHYUN
Published: October 2009

From an [Formula: see text] supersymmetric electric gauge theory with the gauge group [Formula: see text] with fundamentals for each gauge group and the bifundamentals, we apply Seiberg dual to each gauge group and obtain the [Formula: see text] supersymmetric dual magnetic gauge theories with dual matters including the additional gauge singlets. By analyzing the F-term equations of the dual magnetic superpotentials, we describe the intersecting brane configurations of type IIA string theory corresponding to the meta-stable nonsupersymmetric vacua of this gauge theory. We apply also 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 meta-stable brane configurations of multiple product gauge groups.
SEMIRELATIVISTIC HAMILTONIANS AND THE AUXILIARY FIELD METHOD
Authors: SILVESTRE-BRAC BERNARD , SEMAY CLAUDE , BUISSERET FABIEN
Published: October 2009

Approximate analytical closed energy formulas for semirelativistic Hamiltonians of the form [Formula: see text] are obtained within the framework of the auxiliary field method. This method, which is equivalent to the envelope theory, has been recently proposed as a powerful tool to get approximate analytical solutions of the Schrödinger equation. Various shapes for the potential V(r) are investigated: power-law, funnel, square root, and Yukawa. A comparison with the exact results is discussed in detail.
ENTANGLED STATE REPRESENTATIONS IN NONCOMMUTATIVE PHASE SPACE
Authors: GUO GUANG-JIE , LONG CHAO-YUN , QIN SHUI-JIE , ZHANG ZHENG-REN , CHEN HUA-XIONG
Published: October 2009

The entangled state representation has been constructed on noncommutative phase space. Using this appropriate representation, the energy spectrum of general two-dimensional harmonic oscillator has been obtained exactly.
QED ON THE GROENEWOLD–MOYAL PLANE
Authors: BALACHANDRAN A. P. , PINZUL A. , QURESHI B. A. , VAIDYA S.
Published: October 2009

We investigate a version of noncommutative QED where the interaction term, although natural, breaks the spin-statistics connection. We calculate e- + e- → e- + e- and γ + e- → γ + e- cross-sections in the tree approximation and explicitly display their dependence on θμν. Remarkably the zero of the elastic e- + e- → e- + e- cross-section at 90° in the center-of-mass system, which is due to Pauli principle, is shifted away as a function of θμν and energy.
Lineups and Eyewitness Identification
Authors: Leach Amy-May , Cutler Brian L. , Van Wallendael Lori
Published: October 2009

Research on eyewitnesses has led to the development of a knowledge base about the factors that influence eyewitness identification accuracy and to changes to criminal justice policies concerning the collection of eyewitness identification evidence. In this review, we provide an overview of the field of eyewitness identifications and suggest future directions for research. First, we provide the context for the study of eyewitness identifications. Second, we review a sample of factors that affect the accuracy of eyewitness identifications, with attention to both the conditions under which crimes occur and the manner in which identification tests are conducted. Third, we review several findings about which there is some contemporary debate or controversy. Finally, we highlight opportunities for further research on eyewitness identifications by drawing upon basic research in social and cognitive psychology and lessons from actual cases.
Organization and collateralization of a subendocardial plexus in end-stage human heart failure
Authors: van den Wijngaard Jeroen P. H. M. , van Horssen Pepijn , ter Wee Rene , Coronel Ruben , de Bakker Jacques MT , de Jonge Nicolaas , Siebes Maria , Spaan Jos A. E.
Published: October 2009

In the failing myocardium a subendocardial plexus can develop. Detection of the presence or function, however, of such a plexus does not form part of the present diagnostic spectrum for heart failure. This may now change as new methods for high-resolution imaging of myocardial perfusion distribution are being developed. A severely hypertrophic heart was harvested during transplantation and analyzed for morphology of the intramural coronary arterial vasculature. The heart only had one coronary ostium, and the main branches of the coronary artery were cannulated. A fluorescent casting material was infused that was allowed to harden under physiological pressure. The entire heart was frozen and placed in a novel imaging cryomicrotome and sequentially cut in 25-μm slices. High-resolution images of each cutting plane were acquired, allowing a detailed three-dimensional reconstruction of the arterial vasculature. The epicardial layer of the free wall demonstrated a normal vasculature with penetrating branching arteries. The endocardial layer and the septum revealed a highly interconnected vascular plexus with large vessels oriented parallel to the apicobasal axis. An extensive endocardial network with collaterals was detected, forming connections between the main epicardial branches. We conclude that an outward remodeling of transmural vessels did not prevent the generation and growth of subendocardial conduit arteries. The orientation and vascular volume in the plexus provides an opportunity for detection by novel techniques of MRI contrast imaging currently developed. Knowledge of the effect on perfusion studies is required to prevent a misinterpretation of subendocardial perfusion images in heart failure.
Major role for ACE-independent intrarenal ANG II formation in type II diabetes
Authors: Park Sungmi , Bivona Benjamin J. , Kobori Hiroyuki , Seth Dale M. , Chappell Mark C. , Lazartigues Eric , Harrison-Bernard Lisa M.
Published: October 2009

Combination therapy of angiotensin-converting enzyme (ACE) inhibition and AT1receptor blockade has been shown to provide greater renoprotection than ACE inhibitor alone in human diabetic nephropathy, suggesting that ACE-independent pathways for ANG II formation are of major significance in disease progression. Studies were performed to determine the magnitude of intrarenal ACE-independent formation of ANG II in type II diabetes. Although renal cortical ACE protein activity [2.1 ± 0.8 vs. 9.2 ± 2.1 arbitrary fluorescence units (AFU)·mg−1·min−1] and intensity of immunohistochemical staining were significantly reduced and ACE2 protein activity (16.7 ± 3.2 vs. 7.2 ± 2.4 AFU·mg−1·min−1) and intensity elevated, kidney ANG I (113 ± 24 vs. 110 ± 45 fmol/g) and ANG II (1,017 ± 165 vs. 788 ± 99 fmol/g) levels were not different between diabetic and control mice. Afferent arteriole vasoconstriction due to conversion of ANG I to ANG II was similar in magnitude in kidneys of diabetic (−28 ± 3% at 1 μM) and control (−23 ± 3% at 1 μM) mice; a response completely inhibited by AT1receptor blockade. In control kidneys, afferent arteriole vasoconstriction produced by ANG I was significantly attenuated by ACE inhibition, but not by serine protease inhibition. In contrast, afferent arteriole vasoconstriction produced by intrarenal conversion of ANG I to ANG II was significantly attenuated by serine protease inhibition, but not by ACE inhibition in diabetic kidneys. In conclusion, there is a switch from ACE-dependent to serine protease-dependent ANG II formation in the type II diabetic kidney. Pharmacological targeting of these serine protease-dependent pathways may provide further protection from diabetic renal vascular disease.
Effect of oxygen breathing and perfluorocarbon emulsion treatment on air bubbles in adipose tissue during decompression sickness
Authors: Randsoe T. , Hyldegaard O.
Published: October 2009

Decompression sickness (DCS) after air diving has been treated with success by means of combined normobaric oxygen breathing and intravascular perfluorocarbon (PFC) emulsions causing increased survival rate and faster bubble clearance from the intravascular compartment. The beneficial PFC effect has been explained by the increased transport capacity of oxygen and inert gases in blood. However, previous reports have shown that extravascular bubbles in lipid tissue of rats suffering from DCS will initially grow during oxygen breathing at normobaric conditions. We hypothesize that the combined effect of normobaric oxygen breathing and intravascular PFC infusion could lead to either enhanced extravascular bubble growth on decompression due to the increased oxygen supply, or that PFC infusion could lead to faster bubble elimination due to the increased solubility and transport capacity in blood for nitrogen causing faster nitrogen tissue desaturation. In anesthetized rats decompressed from a 60-min hyperbaric exposure breathing air at 385 kPa, we visually followed the resolution of micro-air bubbles injected into abdominal adipose tissue while the rats breathed either air, oxygen, or oxygen breathing combined with PFC infusion. All bubble observations were done at 101.3 kPa pressure. During oxygen breathing with or without combined PFC infusion, bubbles disappeared faster compared with air breathing. Combined oxygen breathing and PFC infusion caused faster bubble disappearance compared with oxygen breathing. The combined effect of oxygen breathing and PFC infusion neither prevented nor increased transient bubble growth time, rate, or growth ratio compared with oxygen breathing alone. We conclude that oxygen breathing in combination with PFC infusion causes faster bubble disappearance and does not exacerbate transient bubble growth. PFC infusion may be a valuable adjunct therapy during the first-aid treatment of DCS at normobaric conditions.
Involvement of matrix metalloproteinases in the growth plate response to physiological mechanical load
Authors: Reich Adi , Maziel Stav Simsa , Ashkenazi Ziv , Ornan Efrat Monsonego
Published: October 2009

Enzymes from the matrix metalloproteinase (MMP) family play a crucial role in growth-plate vascularization and ossification via proteolytic cleavage and remodeling of the extracellular matrix. Their regulation in the growth plate is crucial for normal matrix assembly. Endochondral ossification, which takes place at the growth plates, is influenced by mechanical loading. Using an in vivo avian model for mechanical loading, we have found increased blood penetration into the growth plates of loaded chicks. The purpose of this work was to study the involvement of MMP-2, -3, -9, -13, and -16 in the growth plate's response to loading and in the catch-up growth resulting from load release. We found that mechanical loading, as well as release from load, upregulated MMP-2, -9, and -13 expressions. In contrast, MMP-3, associated with cartilage injuries, and its associated protein connective tissue growth factor (CTGF), were downregulated by the load. However, after release from load, MMP-3 was upregulated and CTGF levels were elevated and caught up with the control. MMP-3 and CTGF were also downregulated after 60 min of mechanical stretching in vitro. These results demonstrate the central role of MMPs in the growth plate's response to mechanical loading, as well as in the catch-up growth followed load release.
Perception of Auditory, Visual, and Egocentric Spatial Alignment Adapts Differently to Changes in Eye Position
Authors: Cui Qi N. , Razavi Babak , O'Neill William E. , Paige Gary D.
Published: October 2009

Vision and audition represent the outside world in spatial synergy that is crucial for guiding natural activities. Input conveying eye-in-head position is needed to maintain spatial congruence because the eyes move in the head while the ears remain head-fixed. Recently, we reported that the human perception of auditory space shifts with changes in eye position. In this study, we examined whether this phenomenon is 1) dependent on a visual fixation reference, 2) selective for frequency bands (high-pass and low-pass noise) related to specific auditory spatial channels, 3) matched by a shift in the perceived straight-ahead (PSA), and 4) accompanied by a spatial shift for visual and/or bimodal (visual and auditory) targets. Subjects were tested in a dark echo-attenuated chamber with their heads fixed facing a cylindrical screen, behind which a mobile speaker/LED presented targets across the frontal field. Subjects fixated alternating reference spots (0, ±20°) horizontally or vertically while either localizing targets or indicating PSA using a laser pointer. Results showed that the spatial shift induced by ocular eccentricity is 1) preserved for auditory targets without a visual fixation reference, 2) generalized for all frequency bands, and thus all auditory spatial channels, 3) paralleled by a shift in PSA, and 4) restricted to auditory space. Findings are consistent with a set-point control strategy by which eye position governs multimodal spatial alignment. The phenomenon is robust for auditory space and egocentric perception, and highlights the importance of controlling for eye position in the examination of spatial perception and behavior.
Sensory Reweighting in Targeted Reaching: Effects of Conscious Effort, Error History, and Target Salience
Authors: Block Hannah J. , Bastian Amy J.
Published: October 2009

When both visual and proprioceptive information are available about the position of a part of the body, the brain weights and combines these sources to form a single estimate, often modeled by minimum variance integration. These weights are known to vary with different circumstances, but the type of information causing the brain to change weights (reweight) is unknown. Here we studied reweighting in the context of estimating the position of a hand for the purpose of reaching it with the other hand. Subjects reached to visual (V), proprioceptive (P), or combined (VP) targets in a virtual reality setup. We calculated weights for vision and proprioception by comparing endpoints on VP reaches with endpoints on P and V reaches. Endpoint visual feedback was manipulated to control completely for the error history seen by subjects. In different experiments, we manipulated target salience, conscious effort, or statistics of the visual error history to see if these cues could cause reweighting. Most subjects could reweight strongly by conscious effort. Changes in target salience reliably caused reweighting, but seen error history alone did not. We also found that experimental weights can be predicted by minimizing the variance of visual and proprioceptive estimates, supporting the idea that minimum variance integration is an important principle of sensorimotor processing.
Hybrid Mammogram Classification Using Rough Set and Fuzzy Classifier
Authors: Abu-Amara Fadi , Abdel-Qader Ikhlas
Published: October 2009

We propose a computer aided detection (CAD) system for the detection and classification of suspicious regions in mammographic images. This system combines a dimensionality reduction module (using principal component analysis), a feature extraction module (using independent component analysis), and a feature subset selection module (using rough set model). Rough set model is used to reduce the effect of data inconsistency while a fuzzy classifier is integrated into the system to label subimages into normal or abnormal regions. The experimental results show that this system has an accuracy of 84.03% and a recall percentage of 87.28%.
Effects of Neurotrophic Factors on Growth and Glial Cell Alignment of Cultured Adult Spiral Ganglion Cells
Authors: Boström Marja , Khalifa Shaden , Boström Henrik , Liu Wei , Friberg Ulla , Rask-Andersen Helge
Published: October 2009

Adult spiral ganglion cells were cultured in chorus to assess the influence of the neurotrophins brain-derived neurotrophic factor, neurotrophin 3 and glial cell line-derived neurotrophic factor (GDNF) on neurite growth and Schwann cell alignment. Over 1500 measurements were collected using each factor at 10 ng/ml and all three in combination. Evaluation was made with GDNF at concentrations of up to 100 ng/ml. Neurite dimensions were assessed at days 5, 7, 9 and 11 using a computer-based program (Axon Analyzer). GDNF had a strong effect on spiral ganglion cell growth almost attaining the level of all three factors in combination. GDNF increased glial cell alignment and nerve bundle formation. Results show the potential of GDNF to maintain and possibly restore auditory nerve integrity.
Willingness to Pay for Genetic Testing: A Study of Attitudes in a Canadian Population
Authors: Ries N.M. , Hyde-Lay R. , Caulfield T.
Published: October 2009

Background: This article reports results of a 2008 telephone survey of approximately 1,200 residents of the Province of Alberta, Canada. The majority of respondents reside in urban centers, have some post-secondary education, and report annual family income near or above the Canadian average. The goal was to explore attitudes and interest regarding different types of genetic tests. Methods: Respondents were asked about their willingness to pay for tests to gain information about genetic factors related to manageable conditions, serious, unpreventable disease, healthy food choices, psychiatric conditions, going bald (asked of men only), and gaining weight. The price categories were CAD 0, CAD 1–499, CAD 500–1,999 and CAD 2,000+. Respondents were also asked about factors that would motivate interest in genetic testing, such as availability of treatment, curiosity, and reproductive decision-making. They were also asked if the public health insurance system should pay for certain types of tests. Results: Across all test categories, few respondents expressed willingness to pay more than CAD 500 out of their own pocket. 62% stated that the public health insurance system should pay for genetic tests for manageable conditions and opinion was divided about whether the government should fund tests for serious, unpreventable conditions and tests to inform healthy eating choices. Conclusion: The principal motivator for interest in genetic testing was to learn clinically relevant details to inform health-related decisions. Curiosity about genetic risk had only a modest impact on consumer interest. In general, younger respondents (18–35 years) expressed somewhat greater willingness to pay than older respondents, especially those 65 and older.
Assessing the Potential Success of Cystic Fibrosis Carrier Screening: Lessons Learned from Tay-Sachs Disease and β-Thalassemia
Authors: Laberge A.-M. , Watts C. , Porter K. , Burke W.
Published: October 2009

Objective: The objective of this study was to identify factors involved in the success of 2 well-established population-based carrier screening programs – Tay-Sachs disease (TSD) in Ashkenazi Jews and β-thalassemia in Sardinia and Cyprus – and to assess the potential for success of a population-based cystic fibrosis (CF) carrier screening strategy using these factors. Methods: We performed a literature review and key informant interviews. Results: Factors involved in the success of TSD and β-thalassemia carrier screening programs include disease characteristics (well-defined population at risk, severe disease with predictable course, availability of effective treatment), test characteristics (high sensitivity, straightforward interpretation of results), and community characteristics (involvement of community, support of families and advocacy groups, consensus in favor of avoiding affected births). Current CF screening strategies include few of the factors listed above. Unlike TSD and β-thalassemia, the purpose of current CF carrier screening strategies is informed reproductive decision-making, without an explicit goal of reducing disease incidence. Conclusion: When compared to TSD and β-thalassemia, CF is a less favorable candidate for population-based carrier screening. Because of its different purpose, CF carrier screening will require different measures of success than those used for TSD and β-thalassemia carrier screening, and a consensus on the value or success of CF carrier screening may be difficult to achieve.
Left Ventricular Diastolic Function in Type 2 Diabetes Mellitus
Authors: Poulsen Mikael Kjaer , Henriksen Jan Erik , Dahl Jordi , Johansen Allan , Gerke Oke , Vach Werner , Haghfelt Torben , H�ilund-Carlsen Poul Flemming , Beck-Nielsen Henning , M�ller Jacob Eifer
Published: October 2009

Background—

Although type 2 diabetes mellitus is a risk factor for developing congestive heart failure, the mechanism leading to heart failure is unclear. We examined the prevalence of left ventricular (LV) systolic and diastolic dysfunction in patients with type 2 diabetes mellitus in relation to vascular function and myocardial perfusion.

Methods and Results—

A prospective observational study of 305 patients with type 2 diabetes mellitus (diabetes duration, 4.5�5.3 years) referred consecutively to a diabetes clinic were screened for LV systolic and diastolic function by echocardiography. Vascular function was estimated using noninvasive estimation of pulse pressure, carotid arterial compliance, total arterial compliance, and valvulo-arterial impedance. The prevalences of LV diastolic dysfunction and left atrial (LA) volume index >32 mL/m
2
were 40% and 32%, respectively. The prevalence of myocardial ischemia on myocardial perfusion scintigraphy was more frequent in patients with grade 2 diastolic dysfunction and LA volume index >32 mL/m
2
compared with those having normal or grade 1 diastolic dysfunction (
P
=0.002) or LA volume index ≤32 mL/m
2
(
P
<0.001), respectively. Predictors of grade 2 diastolic dysfunction and LA dilation were summed stress score on myocardial perfusion scintigraphy, total arterial compliance, and valvulo-arterial impedance, whereas pulse pressure and carotid arterial compliance were not, after adjusting for age, sex, and diabetes duration. On multivariable modeling, summed stress score (
P
<0.001) and valvulo-arterial impedance (
P
=0.027) remained predictors of grade 2 diastolic dysfunction, and only summed stress score (
P
<0.001) was a predictor of LA dilation.

Conclusions—

Abnormal LV filling is closely associated with abnormal myocardial perfusion on myocardial perfusion scintigraphy, whereas the association of LV filling with vascular function is less prominent.

Clinical Trial Registration—

The trial has been registered at www.clinicaltrial.gov with Identifier: NCT00298844.
Left Ventricular and Myocardial Function in Mice Expressing Constitutively Pseudophosphorylated Cardiac Troponin I
Authors: Kirk Jonathan A. , MacGowan Guy A. , Evans Caroline , Smith Stephen H. , Warren Chad M. , Mamidi Ranganath , Chandra Murali , Stewart Alexandre F.R. , Solaro R. John , Shroff Sanjeev G.
Published: October 2009

Rationale:

Protein kinase (PK)C-induced phosphorylation of cardiac troponin (cTn)I has been shown to regulate cardiac contraction.

Objective:

Characterize functional effects of increased PKC-induced cTnI phosphorylation and identify underlying mechanisms using a transgenic mouse model (cTnI
PKC-P
) expressing mutant cTnI (S43E, S45E, T144E).

Methods and Results:

Two-dimensional gel analysis showed 7.2±0.5% replacement of endogenous cTnI with the mutant form. Experiments included: mechanical measurements (perfused isolated hearts, isolated papillary muscles, and skinned fiber preparations), biochemical and molecular biological measurements, and a mathematical model–based analysis for integrative interpretation. Compared to wild-type mice, cTnI
PKC-P
mice exhibited negative inotropy in isolated hearts (14% decrease in peak developed pressure), papillary muscles (53% decrease in maximum developed force), and skinned fibers (14% decrease in maximally activated force, F
max
). Additionally, cTnI
PKC-P
mice exhibited slowed relaxation in both isolated hearts and intact papillary muscles. The cTnI
PKC-P
mice showed no differences in calcium sensitivity, cooperativity, steady-state force-MgATPase relationship, calcium transient (amplitude and relaxation), or baseline phosphorylation of other myofilamental proteins. The model-based analysis revealed that experimental observations in cTnI
PKC-P
mice could be reproduced by 2 simultaneous perturbations: a decrease in the rate of cross-bridge formation and an increase in calcium-independent persistence of the myofilament active state.

Conclusions:

A modest increase in PKC-induced cTnI phosphorylation (≈7%) can significantly alter cardiac muscle contraction: negative inotropy via decreased cross-bridge formation and negative lusitropy via persistence of myofilament active state. Based on our data and data from the literature we speculate that effects of PKC-mediated cTnI phosphorylation are site-specific (S43/S45 versus T144).
Neuroimaging Demonstration of Evolving Small Vessel Ischemic Injury in Cerebral Amyloid Angiopathy
Authors: Menon Ravi S. , Kidwell Chelsea S.
Published: October 2009

Background and Purpose—

Cerebral amyloid angiopathy is a small to medium vasculopathy most commonly associated with symptomatic intracerebral hemorrhage and microbleeds.

Summary of Case—

We present a patient with cerebral microbleeds and likely amyloid angiopathy with evolving ischemic lesions visualized on diffusion-weighted imaging.

Conclusions—

This case captures with serial MRI the evolving and dynamic nature of cerebral amyloid angiopathy and particularly illustrates the subclinical, yet progressive, ischemic aspects of this vasculopathic process.
Systematic Fluctuation Expansion for Neural Network Activity Equations
Authors: Buice Michael A. , Cowan Jack D. , Chow Carson C.
Published: October 2009

Population rate or activity equations are the foundation of a common approach to modeling for neural networks. These equations provide mean field dynamics for the firing rate or activity of neurons within a network given some connectivity. The shortcoming of these equations is that they take into account only the average firing rate, while leaving out higher-order statistics like correlations between firing. A stochastic theory of neural networks that includes statistics at all orders was recently formulated. We describe how this theory yields a systematic extension to population rate equations by introducing equations for correlations and appropriate coupling terms. Each level of the approximation yields closed equations; they depend only on the mean and specific correlations of interest, without an ad hoc criterion for doing so. We show in an example of an all-to-all connected network how our system of generalized activity equations captures phenomena missed by the mean field rate equations alone.
Modeling the Thermal Effects of Artificial Turf on the Urban Environment
Authors: Yaghoobian Neda , Kleissl Jan , Krayenhoff E. Scott
Published: October 2009

The effects of artificial turf (AT) on the urban canopy layer energy balance, air and surface temperatures, and building cooling loads are compared to those of other common ground surface materials (asphalt, concrete, and grass) through heat transfer modeling of radiation, convection, and conduction. The authors apply the Temperatures of Urban Facets in 3D (TUF3D) model—modified to account for latent heat fluxes—to a clear summer day at a latitude of 33° over a typical coastal suburban area in Southern California. The low albedo of artificial turf relative to the other materials under investigation results in a reduction in shortwave radiation incident on nearby building walls and an approximately equal increase in longwave radiation. Consequently, building walls remain at a relatively cool temperature that is similar to those that are adjacent to irrigated grass surfaces. Using a simple offline convection model, replacing grass ground cover with artificial turf was found to add 2.3 kW h m−2 day−1 of heat to the atmosphere, which could result in urban air temperature increases of up to 4°C. Local effects of AT on building design cooling loads were estimated. The increased canopy air temperatures with AT increase heat conduction through the building envelope and ventilation in comparison with a building near irrigated grass. However, in this temperate climate these loads are small relative to the reduction in radiative cooling load through windows. Consequently, overall building design cooling loads near AT decrease by 15%–20%. In addition, the irrigation water conservation with AT causes an embodied energy savings of 10 W h m−2 day−1. Locally, this study points to a win–win situation for AT use for urban landscaping as it results in water and energy conservation.
Optimally Merging Precipitation to Minimize Land Surface Modeling Errors
Authors: Yilmaz M. Tugrul , Houser Paul , Shrestha Roshan , Anantharaj Valentine G.
Published: October 2009

This paper introduces a new method to improve land surface model skill by merging different available precipitation datasets, given that an accurate land surface parameter ground truth is available. Precipitation datasets are merged with the objective of improving terrestrial water and energy cycle simulation skill, unlike most common methods in which the merging skills are evaluated by comparing the results with gauge data or selected reference data. The optimal merging method developed in this study minimizes the simulated land surface parameter (soil moisture, temperature, etc.) errors using the Noah land surface model with the Nelder–Mead (downhill simplex) method. In addition to improving the simulation skills, this method also impedes the adverse impacts of single-source precipitation data errors. Analysis has indicated that the results from the optimally merged precipitation product have fewer errors in other land surface states and fluxes such as evapotranspiration (ET), discharge R, and skin temperature T than do simulation results obtained by forcing the model using the precipitation products individually. It is also found that, using this method, the true knowledge of soil moisture information minimized land surface modeling errors better than the knowledge of other land surface parameters (ET, R, and T). Results have also shown that, although it does not have the true precipitation information, the method has associated heavier weights with the precipitation product that has intensity, amount, and frequency that are similar to those of the true precipitation.