bluuebunny/crossref_metadata_2025 huggingface dataset:
Bones and beyond: an update on the role of vitamin D in child and adolescent health in Canada
Authors: Roth Daniel E.
Published: July 2007

Knowledge regarding the physiological role and dietary requirements of vitamin D has dramatically expanded over the past several decades. The “new” vitamin D is not only a mediator of calcium homeostasis, but also has important immunomodulatory, anti-microbial, and anti-proliferative actions. Amidst the growing interest in vitamin D as a mediator of many chronic diseases of adulthood such as cancer and type II diabetes, less attention has focused on the implications of the new understanding of vitamin D for child and adolescent health. This article reviews the definition of vitamin D insufficiency (VDI) as it applies to children and adolescents, the current vitamin D status of Canadian children and adolescents, pediatric conditions that may be related to VDI, and the evidence base for current dietary recommendations for vitamin D intake. Pharmacokinetic studies and epidemiologic research that incorporates clinical and functional outcomes are needed to clarify the role of vitamin D in growth and development and the specific dietary vitamin D requirements among Canadian children and adolescents.
NUCLEON PROPERTIES FROM MODIFIED SIGMA MODEL
Authors: RASHDAN M. , ABU-SHADY M. , ALI T. S. T.
Published: July 2007

Birse and Banerjee model is extended to include higher-order mesonic interactions. The field equations have been solved in the mean-field approximation and a good agreement with the data for the nucleon properties has been obtained. The agreement is better than that obtained by the original model of Birse and Banerjee which indicates the important of the inclusion of higher-order meson correlations.
NONPERTURBATIVE QUANTIZATION OF PHANTOM AND GHOST THEORIES: RELATING DEFINITE AND INDEFINITE REPRESENTATIONS
Authors: VAN TONDER ANDRÉ , DORCA MIQUEL
Published: July 2007

We investigate the nonperturbative quantization of phantom and ghost degrees of freedom by relating their representations in definite and indefinite inner product spaces. For a large class of potentials, we argue that the same physical information can be extracted from either representation. We provide a definition of the path integral for these theories, even in cases where the integrand may be exponentially unbounded, thereby removing some previous obstacles to their nonperturbative study. We apply our results to the study of ghost fields of Pauli–Villars and Lee–Wick type, and we show in the context of a toy model how to derive, from an exact nonperturbative path integral calculation, previously ad hoc prescriptions for Feynman diagram contour integrals in the presence of complex energies. We point out that the pole prescriptions obtained in ghost theories are opposite to what would have been expected if one had added conventional i∊ convergence factors in the path integral.
GAUGE BOSON FAMILIES IN GRAND UNIFIED THEORIES OF FERMION MASSES: $E_6^4 \rtimes S_4$
Authors: CARAVAGLIOS FRANCESCO , MORISI STEFANO
Published: July 2007

In third quantization the origin of fermion families is easy to understand: the electron field, the muon field and the tau field are identical fields in precisely the same sense as three electrons are identical and indistinguishable particles of a theory of second quantization. In both cases, the permutation of these fields or particles leaves the Lagrangian invariant. One can also extend the concept of family to gauge bosons. This can be obtained through the semidirect product of the gauge group with the group of permutations of n objects. In this paper we have studied the group [Formula: see text]. We explain why we have chosen E6 as fundamental gauge group factor and why we start with a model with four gauge boson/fermion families to accommodate and to fit the Standard Model with only three fermion families. We suggest a possible symmetry breaking pattern of [Formula: see text] that could explain quark, lepton and neutrino masses and mixings.
EFFECTS OF A MIXED VECTOR-SCALAR KINK-LIKE POTENTIAL FOR SPINLESS PARTICLES IN TWO-DIMENSIONAL SPACE–TIME
Authors: DE CASTRO ANTONIO S.
Published: July 2007

The intrinsically relativistic problem of spinless particles subject to a general mixing of vector and scalar kink-like potentials (~ tanh γx) is investigated. The problem is mapped into the exactly solvable Sturm–Liouville problem with the Rosen–Morse potential and exact bounded solutions for particles and antiparticles are found. The behavior of the spectrum is discussed in some detail. An apparent paradox concerning the uncertainty principle is solved by recurring to the concept of effective Compton wavelength.
PEAK LOOPS UNTYING THE DEGENERACY OF THE NEUTRINO PARAMETERS
Authors: KOIKE MASAFUMI , SAITO MASAKO
Published: July 2007

Systematic analysis of the determination of the value of leptonic CP-violating angle δ and the neutrino mass hierarchy [Formula: see text] by long baseline neutrino oscillation experiments is presented. We note the difficulty to distinguish a pair of oscillation probability spectra that are peaked at the same energy and have the same probability at that energy. We thereby set forth the peak-matching condition as a criterion of the presence of degeneracy, and visualize it by intersections of the trajectories drawn by a peak of an oscillation spectrum while the value of δ is varied from 0 to 2π. We numerically calculate the pairs of the trajectories for both hierarchies and show that the pair becomes disjoint as the baseline gets longer than a critical length, indicating the matter effect resolving the degeneracy on the hierarchy. We formulate the trajectories into analytic expressions and evaluate the critical length. We provide prospects of the following four approaches of resolving the hierarchy: making the baseline longer than the critical length, using both neutrinos and anti-neutrinos, combining experiments with different baseline lengths, and observing two or more oscillation peaks.
LASER IRRADIATED ENHANCEMENT OF THE ATOMIC ELECTRON CAPTURE RATE IN SEARCH OF NEW PHYSICS
Authors: NOMURA TAKAAKI , SATO JOE , SHIMOMURA TAKASHI
Published: July 2007

Electron capture processes are important for new physics searches and therefore a high capture rate is inevitably desired. We investigate a possibility of enhancement of an atomic electron capture rate by irradiating laser beam to "an atom". The possibility of the enhancement is shown as a consequence of an enhanced electron wave function at origin Ψ(0) through an effectively increased mass of the electron. We find that order of magnitude enhancement can be achieved using the laser with intensity 1010 W/mm2, and energy of photon, of [Formula: see text].
CHARGED LEPTON MASS FORMULA — DEVELOPMENT AND PROSPECT
Authors: KOIDE YOSHIO
Published: July 2007

The recent devolopment on the charged lepton mass forumula [Formula: see text] is reviewed. An S 3 or A 4 model will be promising for the mass relation.
DARK ENERGY AND NEUTRINO MODEL IN SUSY
Authors: TAKAHASHI RYO , TANIMOTO MORIMITSU
Published: July 2007

We consider a Mass Varying Neutrinos (MaVaNs) model in supersymmetric theory. The model includes effects of supersymmetry breaking transmitted by the gravitational interaction from the hidden sector, in which supersymmetry was broken, to the dark energy sector. Then evolutions of the neutrino mass and the equation of state parameter of the dark energy are presented in the model. It is remarked that only the mass of a sterile neutrino is variable in the case of the vanishing mixing between the left-handed and a sterile neutrino on cosmological time scale. The finite mixing makes the mass of the left-handed neutrino variable.
Interplay between Electronic Structure and Correlation through the s-d Mixing in Transition Metal Systems
Authors: Kanamori Junjiro
Published: July 2007

The s-d mixing which refers to the mixing between d states of a transition element atom and states of s, p, f,… symmetries of neighboring atoms can be of primary importance even in transition metal systems. A mechanism for enhancing the ferromagnetism of iron atom systems through the s-d mixing with s, p valence atoms such as B, C and N which seems to be operating in Nd2Fe14B and other systems is discussed as an illustrative example of the static perturbation effect. A possible role of the s-d mixing in producing the discrepancies of the band structure calculation from the experimental data on single electron excitations in nickel is discussed by extending the discussion on impurities.
Electronic Structure, Magnetic Order and Interlayer Magnetic Couplings in Metallic Superlattices
Authors: Stoeffler Daniel , Gautier François
Published: July 2007

The general trends for the electronic structure of perfect model superlattices AmBn are calculated using a real-space tight-binding model. The magnetic moments distribution and the interlayer magnetic couplings between ferromagnetic layers Am (A=Fe or Co) coupled by non-magnetic (B=V or Ru), nearly ferromagnetic (B=Pd) or antiferromagnetic (B=Cr) spacer layers Bn are obtained as a function of the spacer thickness n.

In a first part, we present the model we used for the calculation and the crystallographic structure of the considered superlattices (Fe/V, Fe/Cr, Co/Ru and Co/Pd). These considerations will be applied to the non-magnetic and nearly ferromagnetic cases to derive general trends for the magnetic interlayers couplings.

In a second part, we apply the method we presented previously to the superlattices with an antiferromagnetic spacer (Fe3Crn). Using first a “d” band calculation we show that the interlayer coupling energy can be understood in terms of a strong interfacial antiferromagnetic coupling and of a constrained magnetic wall in the Cr layer giving a rapidly oscillating coupling energy. An extension of the previous calculation taking into account the “spd” hybridization does not affect the previous conclusion. Finally we examine the distribution of magnetic moments and the stability of tilted antiferromagnetic Cr layers and we find that this magnetic structure is nearly degenerate with the collinear antiferromagnetic arrangement.
Carrier Distribution and Oxygen Ordering in Oxide Superconductors
Authors: Kondo Jun
Published: July 2007

Based on the ionic-crystal model carrier distribution in several oxide superconductors has been determined. A good agreement of our results with experiments indicates that the Madelung energy is a key factor to determine the carrier distribution in these substances. The correlation between the occurrence of superconductivity and oxygen ordering in the basal plane in some substances of the YBCO system has also been explained from the viewpoint of the ionic-crystal model. Possibilities of doping CuO2 planes of some oxides with electrons are discussed.
Critical Surface Reconstruction of Mesoscopic Particles
Authors: Takayanagi Kunio
Published: July 2007

Particles (gold, tin and germanium) of mesoscopic size have been observed by UHV high-resolution electron microscopy to find critical sizes at which the surface layer has a specific reconstruction. The reconstruction is such that the outer-most surface layer constructs a spherical shell surrounding the core of the particle. From in-situ observations of the melting and solidification of the fine tin particles consisting of a few tens to several hundreds of atoms, an intermediate phase between the liquid and the solid phases has been found for the particles below the critical size (4.5–5 nm).
Intermediate Compounds Formed on Metal Surfaces during Catalysis
Authors: Tanaka Ken-ichi
Published: July 2007

An idea of the formation of specific compounds over the metal surfaces has been applied to the metal surfaces during catalysis. One is the formation of c(2 × 2)-N overlayer on Pd (100). Rh(100) and Pt-Rh(100) surfaces during the reaction of NO with H2, that is, these metals make no bulk nitrides and are inactive for the adsorption of N2. These c(2×2)-N overlayers undergo the hydrogénation in the presence of H2, and the high resolution electron energy loss spectrum (HREELS) shows the formation of NHx species. Intensity of the energy loss peak for the N-H vibration depends on a half order in hydrogen pressure which indicates the establishment of an equilibration of N + 1/2H2⇄NH during the hydrogenation reaction. Another example is the formation of carbide overlayer on Ni(100) and Ni(111) surfaces. It was shown that the carbide overlayer on Ni(111) surface takes the same structure as that of the p4g carbide overlayer on Ni(100) surface, which may give a persuasive explanation to the structure insensitive methanation reaction on Ni(100) and Ni(111) surfaces. Finally, more direct evidence for the formation of surface compounds is given by the scanning tunneling microscopy (STM) works on Ag(110) surface. When Ag(110) surface is exposed to O2 at room temperature, rapid growth of AgO chain in parallel to the 〈001〉 direction was observed by STM, and the AgO chains are arranged by making p(n×1) ordered structures over the Ag(110) surface. The ordered phases of AgO chains make one-dimensional phase boundaries, and it was found that the boundary of the two phases necessarily makes a fluctuated structure. The atom model for the two-dimensional arrangement of the AgO chains proves the formation of energetically degenerated sites at the boundary, which is responsible to the fluctuated boundary structures.
Outlook
Authors: Kunihiro Teiji , Muto Takumi , Takatsuka Tatsuyuki , Tamagaki Ryozo , Tatsumi Toshitaka
Published: July 2007

An outlook on theoretical studies on various hadronic and subhadronic phases of high density nuclear matter and their relevance to neutron star problems is given on the basis of the results and considerations described in the preceding chapters.
Chaos with Few Degrees of Freedom
Authors: Gutzwiller Martin C.
Published: July 2007

As a mathematician, astronomer, and physicist, Poincaré was the first to study the phenomenon of chaos in classical mechanics, in particular the three-body-problem of the Moon orbiting around the Earth under the perturbation of the Sun. His work helps us to understand atomic and molecular physics, because our intuition in these areas is always based on a classical picture for the motion of the nuclei and electrons. The Moon's motion was found to be multi-periodic by the early observers; Newton explained the main frequencies and calculated the lowest terms in the corresponding Fourier expansion. But inspite of ingenious efforts, like the work of Hill involving as a starting point a periodic orbit of the full problem, Poincaré showed that perturbation theory is unable to guarantee the convergence of the Fourier expansion. In this traditional representation, the lunar trajectory would be restricted to a four-dimensional invariant torus although the available phase-space has eight dimensions.

The invariant tori are destroyed because of increasing phase-lock due to perturbations, whenever the system is close to a resonance. The KAM-theorem gives a mathematical criterion for this loss, which is best seen in a surface of section for such simple systems as the Anisotropic and the Diamagnetic Kepler Problem (AKP and DKP). Instead of invariant tori, the flow in phase space involves a double foliation where each trajectory is the intersection of one leaf from the unstable foliation with a leaf from the stable foliation. Neighboring trajectories drift exponentially away from each other in the future along the unstable leaf, and approach each another in the stable leaf coming from the past. This situation, called “hard chaos”, also allows for a symbolic description of each trajectory in terms of a simple code like binary sequences in the AKP.

Einstein showed that the usual connection with quantum mechanics is valid only for the case of “regular behavior”, i.e. the presence of invariant tori. For classically chaotic systems, VanVleck's expression for the propagator seems to be the best starting point, provided it is summed over all the classical trajectories that go from the source to the defector. Its trace becomes a sum over periodic orbits, which lends additional weight to Poincaré's emphasis on their importance in classical mechanics. In trying to understand the trace of an operator as a function of time, or the scattering phase-shift as a function of momentum, one runs into almost-periodic functions. They are able to mimic locally any arbitrary smooth function provided the spectrum of frequencies, although discrete, is rich enough. This unexpected, but smooth behavior can be seen as a symptom of quantum chaos, in contrast to the fractal nature of classical chaos.
A Shell Correction Approach for Fission of Charged Metal Clusters
Authors: Koizumi Hiroyasu
Published: July 2007

A shell correction approach for fission of charged metal clusters is discussed and an application to doubly charged silver clusters is presented. In this approach the total energy is expressed as a sum of the liquid drop energy and the shell correction, where the former describes the macroscopic average energy of the system and the latter takes into account the microscopic fluctuation from the average arising from inhomogeneous distribution of valence electron levels. Using this approach we can reduce amount of computation for the complicated fission process and yet describe it quantitatively as well as qualitatively.
Dirac Phenomenology and Hyperon-Nucleus Interactions*)
Authors: MareŠ J. , Jennings B. K. , Cooper E. D.
Published: July 2007

We discuss various aspects of hyperon-nucleus interactions in the relativistic mean field theory. First, characteristics of Λ, Σ and Ξ hypernuclei, as well as multi-strange baryonic objects, are investigated. The spin-orbit splittings and magnetic moments are shown to be very sensitive to the value of the tensor coupling fωY. Second, optical potentials for Λ and Σ scattering off nuclei are developed based on a global nucleon-nucleus Dirac optical potential and SU(3) symmetry. The tensor coupling has a large effect on the predictions for the analyzing power. Third, the Dirac approach is used in the calculations of the non-mesonic decay of Λ hypernuclei. The large discrepancy between the decay rates and data suggests the need for additional meson exchanges.
Natural History of the Scuttle Fly,Megaselia scalaris
Authors: Disney R.H.L.
Published: July 2007

The larvae of Megaselia scalaris (Diptera: Phoridae) exploit a broad spectrum of larval pabula. Consequently, the species features in a range of situations that affect the resources or well-being of humans. Furthermore, M. scalaris is readily cultured in the laboratory and is therefore favored as an experimental species for genetic, developmental, and bioassay studies. However, the extensive but widely scattered literature, reviewed herein, is frequently ignored by specialists, which gives rise to the unwitting repetition of previous work as well as insupportable proposals.
Enhanced External Counterpulsation Inhibits Intimal Hyperplasia by Modifying Shear Stress–Responsive Gene Expression in Hypercholesterolemic Pigs
Authors: Zhang Yan , He Xiaohong , Chen Xiaolin , Ma Hong , Liu Donghong , Luo Jinyun , Du Zhimin , Jin Yafei , Xiong Yan , He Jiangui , Fang Dianqiu , Wang Kuijian , Lawson William E. , Hui John C.K. , Zheng Zhensheng , Wu Guifu
Published: July 2007

Background—

Enhanced external counterpulsation (EECP) is a circulation assist device that may improve endothelial dysfunction by increasing shear stress. Chronic exposure of vascular endothelial cells and vascular smooth muscle cells to relatively high physiological shear stress has antiproliferative and vasoprotective effects. The present study hypothesizes that EECP inhibits intimal hyperplasia and atherogenesis by modifying shear stress–responsive gene expression.

Methods and Results—

Thirty-five male pigs were randomly assigned to 3 groups: high-cholesterol diet (n=11), high-cholesterol diet plus EECP (n=17), and usual diet (control; n=7). The coronary arteries and aortas were collected for histopathological study and immunohistochemical and Western blot analysis. The peak diastolic arterial wall shear stress during EECP increased significantly compared with before EECP (49.62±10.71 versus 23.92±7.28 dyne/cm
2
;
P
<0.001). Intimal hyperplasia was observed in the coronary arteries of the high-cholesterol diet group, whereas in animals receiving EECP, the intima-to-media area ratio was significantly decreased by 41.59% (21.27±10.00% versus 36.41±16.69%;
P
=0.008). Hypercholesterolemia attenuated the protein expression of endothelial NO synthase and enhanced the phosphorylation of extracellular signal-regulated kinases 1/2. EECP treatment alleviated these adverse changes.

Conclusions—

EECP reduces hypercholesterolemia-induced endothelial damage, arrests vascular smooth muscle cell proliferation and migration, decreases proliferating cell nuclear antigen proliferative index, suppresses extracellular matrix formation, and eventually inhibits intimal hyperplasia and the development of atherosclerosis by increasing the arterial wall shear stress, which in turn activates the endothelial NO synthase/NO pathway and probably suppresses extracellular signal-regulated kinases 1/2 overactivation.
Systemic Lupus Erythematosus Predicts Increased Left Ventricular Mass
Authors: Pieretti Janice , Roman Mary J. , Devereux Richard B. , Lockshin Michael D. , Crow Mary K. , Paget Stephen A. , Schwartz Joseph E. , Sammaritano Lisa , Levine Daniel M. , Salmon Jane E.
Published: July 2007

Background—

Systemic lupus erythematosus (SLE) is associated with premature atherosclerosis and vascular stiffening. Whether SLE alters left ventricular (LV) structure and function in the absence of valvular and clinical coronary artery disease is unknown.

Methods and Results—

SLE patients without clinical or echocardiographic evidence of valvular or coronary disease were age and gender matched to a reference group (n=173 in both groups). Subjects underwent echocardiography to quantify LV structure and function and carotid ultrasonography to detect atherosclerosis. Disease characteristics and radial applanation tonometry to measure arterial stiffness were evaluated in SLE patients. The 2 groups were similar in subjects’ body size, hypertension and diabetes status, smoking status, and cholesterol levels. LV mass (38.3 versus 32.8 g/m
2.7
), ejection fraction (71% versus 67%), and prevalence of LV hypertrophy (17.9% versus 6.4%) were higher in SLE patients than in referent subjects (all
P
<0.001). The combination of SLE and hypertension further increased LV mass. In multivariable analysis, LV mass was associated with SLE (
P
<0.001) in addition to body mass index, diabetes mellitus, and hypertension. Among SLE patients, LV mass was associated with arterial stiffness (
P
<0.001). Carotid atherosclerosis, SLE duration, damage index, serum creatinine, and homocysteine were significantly related to LV mass in univariate but not multivariable analyses.

Conclusions—

SLE predicts increased LV mass, possibly because of inflammation-related arterial stiffening. Excess LV hypertrophy may contribute to the increased cardiac morbidity and mortality observed in SLE patients.
Soluble Receptor Activator of Nuclear Factor-κB Ligand and Risk for Cardiovascular Disease
Authors: Kiechl Stefan , Schett Georg , Schwaiger Judith , Seppi Klaus , Eder Paula , Egger Georg , Santer Peter , Mayr Agnes , Xu Qingbo , Willeit Johann
Published: July 2007

Background—

Overexpression of receptor activator of nuclear factor-κB ligand (RANKL) is a prominent feature of vulnerable atherosclerotic lesions prone to rupture and was thought to contribute to the transition from a stable to an unstable plaque phenotype in both human and murine atherosclerosis because of its ability to promote matrix degradation, monocyte/macrophage chemotaxis, and vascular calcification.

Methods and Results—

The Bruneck Study is a prospective, population-based survey of men and women 40 to 79 years of age at the 1990 baseline examination. Levels of soluble RANKL and other variables were assessed in 909 subjects (1990). All cases of cardiovascular disease were carefully recorded between 1990 and 2005. During follow-up, cardiovascular disease (defined as ischemic stroke and transient ischemic attack, myocardial infarction, and vascular death) manifested in 124 of the 909 subjects. Baseline serum level of RANKL emerged as a highly significant predictor of vascular risk (adjusted hazard ratio per 1-unit increase in soluble RANKL, 1.27; 95% confidence interval, 1.16 to 1.40;
P
<0.001). Predictive significance was independent of that afforded by the classic vascular risk factors, C-reactive protein, osteoprotegerin concentration, and severity of carotid atherosclerosis. Findings were internally consistent and robust in a variety of sensitivity analyses. Notably, soluble RANKL was not associated with carotid or femoral artery atherosclerosis.

Conclusions—

Our study lends large-scale epidemiological support to a role for RANKL in cardiovascular disease. In the absence of a significant association between RANKL and atherosclerosis, the idea that RANKL promotes plaque destabilization and rupture is a highly appealing concept.
Reshaping the Methodological Identity of Education Research
Authors: Constas Mark A.
Published: July 2007

The purpose of the present article is to assess the impact that recent federal policies have had on education research. Using published journal articles as a data source, the study examines reports on the frequency of use for terms representing federal priorities for education research ( experimental, randomization, hypothesis, and quantitative) compared to the frequency of use for terms representing methodologies that are granted a lower priority within federal policy ( ethnographic, narrative, postmodern, and qualitative). A comparison between the data for 2001 (pre-policy period) and data for 2005 (policy enactment period) shows increased use of all four terms representing federal priorities, whereas three of the four terms representing nonexperimental research are associated with decreased numbers of articles. Some of the ways in which the findings may be interpreted are discussed and additional analyses that may be conducted to help track the impact of federal policy on education research are described.
When Do Simpler Sexual Behavior Data Collection Techniques Suffice?
Authors: Pinkerton Steven D. , Benotsch Eric G. , Mikytuck John
Published: July 2007

The “gold standard” for evaluating human immunodeficiency virus (HIV) prevention programs is a partner-by-partner sexual behavior assessment that elicits information about each sex partner and the activities engaged in with that partner. When collection of detailed partner-by-partner data is not feasible, aggregate data (e.g., total numbers of partners and acts of various types) must suffice. Lack of specificity in the primary data often translates into uncertainty in modeled outcomes, such as participants' risk of HIV acquisition. To our knowledge, no previous study has attempted to quantify this uncertainty. The results of the present analysis of the risk of HIV acquisition by men vacationing in Key West indicate that the use of aggregate rather than partner-by-partner data introduced relatively little uncertainty into the HIV risk estimates. Collection of aggregate data is a viable alternative to detailed partner-by-partner data, at least in some circumstances.
Performance Comparison of Zone Models with Compartment Fire Tests
Authors: Remesh K. , Tan K.H.
Published: July 2007

Prediction accuracy of zone models is attributed to the sophistication of the mathematical model, as well as the numerical methods applied in their implementation. Well-known zone models CFAST and OZone have gained world-wide acceptance among the fire engineering community in predicting enclosure fire dynamics. Despite these models serving similar purpose, the level of accuracy and applicability range are still a field of active research. This study compares an in-house developed zone model CFMFAN with CFAST and OZone in their modeling concepts, prediction capability, and accuracy. The sub-models for gas flow, heat transfer, and heat release rate are examined. Performance comparisons of these zone models with published experimental results for 20 single compartment fire tests are carried out in the blind mode. The test parameters used are the fire size (330—980 kW) and the fire location (center or side). For performance comparisons, the upper- and lower-layer temperatures, interface and neutral plane heights, pressure difference at the floor, wall temperatures, plume flow, and vent flow rates are compared. Upon comparison with compartment fire test results, the study shows that CFAST consistently overpredicts the upper-layer temperature whereas OZone and CFMFAN underpredict it for all fire sizes. All the models underpredict the lower-layer temperature. Explanations are given for the deviations of the three models from the test results and from one another.
Influence of the Structure of Acrylate Groups on the Flame Retardant Behavior of Ethylene Acrylate Copolymers Modified with Chalk and Silicone Elastomer
Authors: Lundgren Anna , Hjertberg Thomas , Sultan Bernt-Ake
Published: July 2007

This study treats the flame retardant effects of different ethylene acrylate copolymers used in a chalk and silicone elastomer system, specifically the flame retardant chemistry and behavior at lower temperatures. The presence or absence of ester pyrolysis, formation of ionomers or other crosslinks, viscosity, and the effects of these factors on the formation and stability of the intumescent structure formed during heating are discussed. The effects of the acrylate content and melt flow rate in flame retardant compounds based on ethylene butyl acrylate copolymer and ethylene ethyl acrylate copolymer are examined. Results of oxygen index, cone calorimetry (including visual observations), dripping, viscosity measurement, thermogravimetric analysis, and infrared spectroscopy are reported.
Feasibility Study of the Social Enterprise Intervention With Homeless Youth
Authors: Ferguson Kristin M. , Xie Bin
Published: July 2007

Objective: To reduce mental health symptoms and high-risk behaviors and increase social support and service utilization among street-living youth, the authors conducted a pilot study to assess the feasibility of the social enterprise intervention (SEI) at a homeless youth agency. Method: Convenience sampling was used to recruit 16 street-living youth from the agency. SEI participants received 7 months of vocational and small business training and service referrals. A comparison sample of 12 agency youth was used. Results: Findings from independent sample t tests demonstrate that SEI participants displayed significant improvements at 9 months in life satisfaction, family contact, peer support, and depressive symptoms. Conclusions: Preliminary findings suggest that the SEI was feasible within the agency setting and associated with higher mental health and social outcomes.
Psychosocial Determinants of the Early Introduction of Complementary Foods
Authors: Tatone-Tokuda Fabiola , Dubois Lise , Girard Manon
Published: July 2007

Infant feeding guidelines recommend exclusive breast-feeding to the age of 6 months; complementary foods should not be introduced before this age. This study examined parent and infant psychosocial determinants of the early introduction of complementary foods. Analyses were conducted on a representative sample of children born in Québec (Canada) in 1998 ( n = 2,223), surveyed through the Québec Longitudinal Study of Child Development. Of the children, 61% received complementary foods prior to the age of 4 months. A multiple logistic regression analysis revealed the early introduction of complementary foods was more likely when mothers were younger, less educated, of lower socioeconomic class, and when they felt they had little influence on their child's development. Higher parental confidence in caring for the infant was also associated with the early introduction of complementary foods ( p ≤ .05). Future research must carefully consider the psychosocial aspects involved in adhering to infant feeding guidelines.
Symbolic resources and responsibility in transitions
Authors: ZITTOUN TANIA
Published: July 2007

Since youth transitions have been redefined as flexible periods of change, it becomes difficult to conceptually distinguish them from any other transition period in people's life. Transitions are here defined as involving three types of interdependent processes (social relocation, knowledge construction and meaning-making). From a cultural psychological perspective, youth transitions can be qualified by young people's access to symbolic responsibility. Through a case study, the article shows how cultural elements chosen and used by a person can support processes of transition. Finally, the article sketches a model of uses of symbolic resources enabled by symbolic responsibility.
Remembering the House
Authors: Morton Christopher
Published: July 2007

Although both anthropology and archaeology have long been interested in the relationship between the built environment and social forms, relatively little attention has been paid to the way in which the material home is implicated in processes of memory. Drawing on case studies from fieldwork in northern Botswana, this article argues that memory, or more especially processes of remembering, is importantly related to the spatial and temporal fluidity of the Tswana home and its inherent divisibility. The article argues that understandings of the house as a container for memory or biography have not sufficiently understood the way in which the materiality of the house, as well as its spatial configurations over time, are involved with the way in which such memories are formed and articulated. It also suggests that, in its connectedness to memory and community, building activity is an important material basis for cultural understandings of relatedness.
Mixtures and diagnostic plots in modelling road traffic vehicle headways
Authors: Cowburn Gerard J , Farrow Malcolm
Published: July 2007

We consider Bayesian modelling of the inter-arrival times of vehicles on a road. We give particular attention to model checking and propose diagnostic plots to assess whether the model captures features observed in the data. Models for such processes are important in predicting the behaviour of road junctions. Two-component mixtures have often been used, with a variety of distributions for the components and non-Bayesian methods for fitting. The components are often regarded as representing ‘free flowing’ and ‘congested’ vehicles. We propose a gamma-exponential mixture and compare this with some other models. To allow for the serial dependence of headways, we consider the use of a hidden Markov chain for the mixture component allocation.
Floating Bombs Encircling Our Shores: Post-9/11 Rhetorics of Piracy and Terrorism
Authors: Engels Jeremy
Published: July 2007

This essay considers the relationship between piracy, terrorism, and post-9/11 U.S. foreign policy as it is outlined in the National Security Strategy of the United States (NSSUS). The NSSUS's discursive formation undertakes two noteworthy rhetorical maneuvers: It confuses piracy with terrorism, thereby shifting focus away from piracy as theft toward the threat of terrorism at sea, or "floating bombs," and it nationalizes terrorism, thereby making terrorists subject to retaliation by the U.S. military. Because post-9/11 distinctions between terrorists, those who pursue violence for political ends, and pirates, those who pursue violence for profiteering ends, have become increasingly difficult to substantiate in the American social imaginary, the collapse of these two categories signifies a final conflation of state power and economic power into one homogenizing, all-consuming force called empire. At the same time, piracy has become a formidable form of global capitalism sharing many characteristics with the doctrines enumerated by the NSSUS.
Postcolonialism and Globalization in Education
Authors: Rizvi Fazal
Published: July 2007

In this short article, the author explores the complex relationship between globalization and postcolonialism. He argues that the contemporary processes of globalization are often described in ahistorical terms, whereas much of recent literature on postcolonialism is reduced largely to apolitical analyses of literary texts, disconnected from issues of current and shifting configurations of power. The author argues for the need to understand global processes in education historically and suggests that intellectual postcolonial resources of postcolonialism can be most helpful, but only if postcolonialism is viewed as a political intervention.
TIM-1 and TIM-3 enhancement of Th2 cytokine production by mast cells
Authors: Nakae Susumu , Iikura Motoyasu , Suto Hajime , Akiba Hisaya , Umetsu Dale T. , DeKruyff Rosemarie H. , Saito Hirohisa , Galli Stephen J.
Published: July 2007

Members of the T-cell immunoglobulin– and mucin-domain–containing molecule (TIM) family have roles in T-cell–mediated immune responses. TIM-1 and TIM-2 are predominantly expressed on T helper type 2 (Th2) cells, whereas TIM-3 is preferentially expressed on Th1 and Th17 cells. We found that TIM-1 and TIM-3, but neither TIM-2 nor TIM-4, were constitutively expressed on mouse peritoneal mast cells and bone marrow–derived cultured mast cells (BMCMCs). After IgE + Ag stimulation, TIM-1 expression was down-regulated on BMCMCs, whereas TIM-3 expression was up-regulated. We also found that recombinant mouse TIM-4 (rmTIM-4), which is a ligand for TIM-1, as well as an anti–TIM-3 polyclonal Ab, can promote interleukin-4 (IL-4), IL-6, and IL-13 production without enhancing degranulation in BMCMCs stimulated with IgE + Ag. Moreover, the anti–TIM-3 Ab, but neither anti–TIM-1 Ab nor rmTIM-4, suppressed mast-cell apoptosis. These observations suggest that TIM-1 and TIM-3 may be able to influence T-cell–mediated immune responses in part through effects on mast cells.
Chick Hairy1 protein interacts with Sap18, a component of the Sin3/HDAC transcriptional repressor complex
Authors: Sheeba Caroline J , Palmeirim Isabel , Andrade Raquel P
Published: July 2007

Background

The vertebrate adult axial skeleton, trunk and limb skeletal muscles and dermis of the back all arise from early embryonic structures called somites. Somites are symmetrically positioned flanking the embryo axial structures (neural tube and notochord) and are periodically formed in a anterior-posterior direction from the presomitic mesoderm. The time required to form a somite pair is constant and species-specific. This extraordinary periodicity is proposed to depend on an underlying somitogenesis molecular clock, firstly evidenced by the cyclic expression of the chick hairy1 gene in the unsegmented presomitic mesoderm with a 90 min periodicity, corresponding to the time required to form a somite pair in the chick embryo. The number of hairy1 oscillations at any given moment is proposed to provide the cell with both temporal and positional information along the embryo's anterior-posterior axis. Nevertheless, how this is accomplished and what biological processes are involved is still unknown. Aiming at understanding the molecular events triggered by the somitogenesis clock Hairy1 protein, we have employed the yeast two-hybrid system to identify Hairy1 interaction partners.

Results

Sap18, an adaptor molecule of the Sin3/HDAC transcriptional repressor complex, was found to interact with the C-terminal portion of the Hairy1 protein in a yeast two-hybrid assay and the Hairy1/Sap18 interaction was independently confirmed by co-immunoprecipitation experiments. We have characterized the expression patterns of both sap18 and sin3a genes during chick embryo development, using in situ hybridization experiments. We found that both sap18 and sin3a expression patterns co-localize in vivo with hairy1 expression domains in chick rostral presomitic mesoderm and caudal region of somites.

Conclusion

Hairy1 belongs to the hairy-enhancer-of-split family of transcriptional repressor proteins. Our results indicate that during chick somitogenesis Hairy1 may mediate gene transcriptional repression by recruiting the Sin3/HDAC complex, through a direct interaction with the Sap18 adaptor molecule. Moreover, since sap18 and sin3a are not expressed in the PSM territory where hairy1 presents cyclic expression, our study strongly points to different roles for Hairy1 throughout the PSM and in the prospective somite and caudal region of already formed somites.
Collective properties of evolving molecular quasispecies
Authors: Stich Michael , Briones Carlos , Manrubia Susanna C
Published: July 2007

Background

RNA molecules, through their dual appearance as sequence and structure, represent a suitable model to study evolutionary properties of quasispecies. The essential ingredient in this model is the differentiation between genotype (molecular sequences which are affected by mutation) and phenotype (molecular structure, affected by selection). This framework allows a quantitative analysis of organizational properties of quasispecies as they adapt to different environments, such as their robustness, the effect of the degeneration of the sequence space, or the adaptation under different mutation rates and the error threshold associated.

Results

We describe and analyze the structural properties of molecular quasispecies adapting to different environments both during the transient time before adaptation takes place and in the asymptotic state, once optimization has occurred. We observe a minimum in the adaptation time at values of the mutation rate relatively far from the phenotypic error threshold. Through the definition of a consensus structure, it is shown that the quasispecies retains relevant structural information in a distributed fashion even above the error threshold. This structural robustness depends on the precise shape of the secondary structure used as target of selection. Experimental results available for natural RNA populations are in qualitative agreement with our observations.

Conclusion

Adaptation time of molecular quasispecies to a given environment is optimized at values of the mutation rate well below the phenotypic error threshold. The optimal value results from a trade-off between diversity generation and fixation of advantageous mutants. The critical value of the mutation rate is a function not only of the sequence length, but also of the specific properties of the environment, in this case the selection pressure and the shape of the secondary structure used as target phenotype. Certain functional motifs of RNA secondary structure that withstand high mutation rates (as the ubiquitous hairpin motif) might appear early in evolution and be actually frozen evolutionary accidents.
EuMicroSatdb: A database for microsatellites in the sequenced genomes of eukaryotes
Authors: Aishwarya Veenu , Grover Atul , Sharma Prakash C
Published: July 2007

Background

Microsatellites have immense utility as molecular markers in different fields like genome characterization and mapping, phylogeny and evolutionary biology. Existing microsatellite databases are of limited utility for experimental and computational biologists with regard to their content and information output. EuMicroSatdb (Eu karyotic MicroSat ellite
d
ata
b
ase) http://ipu.ac.in/usbt/EuMicroSatdb.htm is a web based relational database for easy and efficient positional mining of microsatellites from sequenced eukaryotic genomes.

Description

A user friendly web interface has been developed for microsatellite data retrieval using Active Server Pages (ASP). The backend database codes for data extraction and assembly have been written using Perl based scripts and C++. Precise need based microsatellites data retrieval is possible using different input parameters like microsatellite type (simple perfect or compound perfect), repeat unit length (mono- to hexa-nucleotide), repeat number, microsatellite length and chromosomal location in the genome. Furthermore, information about clustering of different microsatellites in the genome can also be retrieved. Finally, to facilitate primer designing for PCR amplification of any desired microsatellite locus, 200 bp upstream and downstream sequences are provided.

Conclusion

The database allows easy systematic retrieval of comprehensive information about simple and compound microsatellites, microsatellite clusters and their locus coordinates in 31 sequenced eukaryotic genomes. The information content of the database is useful in different areas of research like gene tagging, genome mapping, population genetics, germplasm characterization and in understanding microsatellite dynamics in eukaryotic genomes.
11C-choline vs. 18F-FDG PET/CT in assessing bone involvement in patients with multiple myeloma
Authors: Nanni Cristina , Zamagni Elena , Cavo Michele , Rubello Domenico , Tacchetti Paola , Pettinato Cinzia , Farsad Mohsen , Castellucci Paolo , Ambrosini Valentina , Montini Gian Carlo , Al-Nahhas Adil , Franchi Roberto , Fanti Stefano
Published: July 2007

Background

Multiple Myeloma (MM) is a B cell neoplasm causing lytic or osteopenic bone abnormalities. Whole body skeletal survey (WBSS), Magnetic resonance (MR) and 18F-FDG PET/CT are imaging techniques routinely used for the evaluation of bone involvement in MM patients.

Aim

As MM bone lesions may present low 18F-FDG uptake; the aim of this study was to assess the possible added value and limitations of 11C-Choline to that of 18F-FDG PET/CT in patients affected with MM.

Methods

Ten patients affected with MM underwent a standard 11C-Choline PET/CT and an 18F-FDG PET/CT within one week. The results of the two scans were compared in terms of number, sites and SUVmax of lesions.

Results

Four patients (40%) had a negative concordant 11C-Choline and 18F-FDG PET/CT scans. Two patients (20%) had a positive 11C-Choline and 18F-FDG PET/CT scans that identified the same number and sites of bone lesions. The remaining four patients (40%) had a positive 11C-Choline and 18F-FDG PET/CT scan, but the two exams identified different number of lesions. Choline showed a mean SUVmax of 5 while FDG showed a mean SUVmax of 3.8 (P = 0.042). Overall, 11C-Choline PET/CT scans detected 37 bone lesions and 18F-FDG PET/CT scans detected 22 bone lesions but the difference was not significant (P = 0.8).

Conclusion

According to these preliminary data, 11C-Choline PET/CT appears to be more sensitive than 18F-FDG PET/CT for the detection of bony myelomatous lesions. If these data are confirmed in larger series of patients, 11C-Choline may be considered a more appropriate functional imaging in association with MRI for MM bone staging.
Simian virus 40 in humans
Authors: Martini Fernanda , Corallini Alfredo , Balatti Veronica , Sabbioni Silvia , Pancaldi Cecilia , Tognon Mauro
Published: July 2007

Simian virus 40 (SV40) is a monkey virus that was administered to human populations by contaminated vaccines which were produced in SV40 naturally infected monkey cells.

Recent molecular biology and epidemiological studies suggest that SV40 may be contagiously transmitted in humans by horizontal infection, independently from the earlier administration of SV40-contaminated vaccines.

SV40 footprints in humans have been found associated at high prevalence with specific tumor types such as brain and bone tumors, mesotheliomas and lymphomas and with kidney diseases, and at lower prevalence in blood samples from healthy donors.

Contrasting reports appeared in the literature on the circulation of SV40 in humans by contagious transmission and its association, as a possible etiologic cofactor, with specific human tumors. As a consequence of the conflicting results, a considerable debate has developed in the scientific community. In the present review we consider the main results obtained by different groups investigating SV40 sequences in human tumors and in blood specimens, the putative role of SV40 in the onset/progression of specific human tumors, and comment on the hypotheses arising from these data.