bluuebunny/crossref_metadata_2025 huggingface dataset:
The State of Media Ownership and Media Markets: Competition or Concentration and Why Should We Care?
Authors: Winseck Dwayne
Published: April 2008

This article presents a global overview of the state of communications media ownership and markets. The primary issue at stake is whether or not markets and ownership are becoming more or less concentrated. After reviewing contrasting views on this issue, I suggest that the question turns on whether or not we consider ‘numerical diversity’ (the number of channels available in any given area) versus ‘source diversity’ (a measure of the number of media owners in any given area). Drawing on recent data I suggest that while there is undoubtably greater ‘numerical diversity’, we are seeing – within countries, regionally and globally – greater concentration at the level of ‘source diversity’. While new media, especially the Internet, open up unprecedented opportunities for people to access and distribute information, the emergence of a powerful nexus between both ‘old’ and ‘new’ media means that the character of media ownership and markets still matters greatly. This nexus of ownership and market power spans different segments of the media and is qualitatively different from previous times. These factors have an important influence on the evolution of media technologies and markets, the work of media professionals and the character of information and media content.
From Colonial Pluralism to Postcolonial Multiculturalism: Race, State Formation and the Question of Cultural Diversity in Malaysia and Singapore
Authors: Goh Daniel P. S.
Published: April 2008

In postcolonial societies, multiculturalism is a historical problem conditioned by colonial racial knowledge and state formation on the one hand, and by the ethnic conflicts of decolonization on the other. The reality and legacy of colonial racisms in colonized societies were not straightforward affairs. Anthropological knowledge was crucial for the construction of colonial state institutions, where racial ethnography determined the way each native ethnic group was ruled. In turn, nationalist consciousness developed along communitarian ethnic lines. The inheritance of the colonial racial state by nationalists created the conditions for postcolonial ethnic conflict. Drawing on the acclaimed Malaysia and Singapore cases of successful postcolonial management of ethnic conflict, I show the transition from colonial pluralism to postcolonial multiculturalism, in which nationalist leaders tapped into communitarian practices, scripted cultural identities and transformed themselves into a transcultural elite to maintain authoritarian rule through state multiracialism. However, globalization today is creating a new pluralism that threatens this multiracialism and presenting opportunities for democratization.
Sociological Knowledge and Scientific Knowledge
Authors: David Matthew
Published: April 2008

Some significant insights in relation to science and its claims emerged in early sociology. However, sociologies of knowledge and science remained separate until the late 1960s. Questioning scientific knowledge raised questions about career interests, language, interaction, class and gender in shaping scientific claims. Offering insights, this new sociology tended towards ‘epistemological polarisation’. New waves further distanced themselves from the validity claims of ‘scientists’. Insulating within a self‐referential field of peers, journals, conferences and subdisciplinary norms, epistemological polarisation, emulated natural sciences, but had a marginalising effect. Attention to symmetry in the social study of scientific beliefs, such that social causation of belief is not said to invalidate such belief, was often ignored, and the sociology of scientific knowledge tended towards debunking. This article challenges this spiral and suggests a ‘reflexive epistemological diversity’ that recognises the value of many forms of explanation, promoting interaction between different explanations, at different levels of causation, and across the divide between natural and social sciences. Recent feminist science studies go furthest in developing this trend. In line with recent developments in the natural sciences, such an approach does not suggest that ‘anything goes’, yet opens up explanation beyond narrow conceptions of expertise, reductionism and relativism.
Two different forms of long‐term potentiation at CA1–subiculum synapses
Authors: Wozny Christian , Maier Nikolaus , Schmitz Dietmar , Behr Joachim
Published: April 2008

Distinct functional roles in learning and memory are attributed to certain areas of the hippocampus and the parahippocampal region. The subiculum as a part of the hippocampal formation is the principal target of CA1 pyramidal cell axons and serves as an interface in the information processing between the hippocampus and the neocortex. Subicular pyramidal cells have been classified as bursting and regular firing cells. Here we report fundamental differences in long‐term potentiation (LTP) between both cell types. Prolonged high‐frequency stimulation induced NMDA receptor‐dependent LTP in both cell types. While LTP relied on postsynaptic calcium in regular firing neurons, no increase in postsynaptic calcium was required in bursting cells. Furthermore, paired‐pulse facilitation revealed that the site of LTP expression was postsynaptic in regular firing neurons, while presynaptic in burst firing neurons. Our findings on synaptic plasticity in the subiculum indicate that regular firing and bursting cells represent two functional units with distinct physiological roles in processing hippocampal output.
Selective modulation of interactions between ventral premotor cortex and primary motor cortex during precision grasping in humans
Authors: Davare Marco , Lemon Roger , Olivier Etienne
Published: April 2008

In humans, the rostral part of the ventral premotor cortex (PMv), the homologue of F5 in monkeys, is known to be critically involved in shaping the hand to grasp objects. How does information about hand posture, that is processed in PMv, give rise to appropriate motor commands for transmission to spinal circuits controlling the hand? Whereas PMv is crucial for skilled visuomotor control of the hand, PMv sends relatively few direct corticospinal projections to spinal segments innervating hand muscles and the most likely route for PMv to contribute to the control of hand shape is through cortico‐cortical connections with primary motor cortex (M1). If this is the case, we predicted that PMv–M1 interactions should be modulated specifically during precision grasping in humans. To address this issue, we investigated PMv–M1 connections by means of paired‐pulse transcranial magnetic stimulation (TMS) and compared whether they were differentially modulated at rest, and during precision versus power grip. To do so, TMS was applied over M1 either in isolation or after a conditioning stimulus delivered, at different delays, over the ipsilateral PMv. For the parameters of TMS tested, we found that, at rest, PMv exerted a net inhibitory influence on M1 whereas, during power grip, this inhibition disappeared and was converted into a net facilitation during precision grip. The finding that, in humans, PMv–M1 interactions are selectively modulated during specific types of grasp provides further evidence that these connections play an important role in control of the hand.
Modeling of the Flow Rate in the Dispensing-Based Process for Fabricating Tissue Scaffolds
Authors: Chen X. B. , Li M. G. , Ke H.
Published: April 2008

Made from biomaterials, tissue scaffolds are three-dimensional (3D) constructs with highly interconnected pore networks for facilitating cell growth and flow transport of nutrients and metabolic waste. To fabricate the scaffolds with complex structures, dispensing-based rapid prototyping technique has been employed recently. In such a fabrication process, the flow rate of biomaterial dispensed is of importance since it directly contributes to the pore size and porosity of the scaffold fabricated. However, the modeling of the flow rate has proven to be a challenging task due to its complexity. This paper presents the development of a model for the flow rate in the scaffold fabrication process based on the fundamentals of fluid mechanics. To verify the effectiveness of the developed model, experiments were carried out, in which the chitosan solution (2% w/v) in acetic acid was used for dispensing under different applied pressures (50kPa, 100kPa, 150kPa, 200kPa, and 250kPa) and needle heater temperatures (25°C, 35°C, 50°C, and 65°C). The measured flow rates were used to identify the flow behavior of the solution and were compared to the predictions from the developed model to illustrate the model effectiveness. Based on the developed model, simulations were carried out to identify the effects of the needle size and the flow behavior on the flow rate in the scaffold fabrication process. The developed model was also applied to determine the dispensing conditions for fabricating 3D scaffolds from a 50% chitosan-hydroxyapatite colloidal gel. As an example, a scaffold fabricated with a well-controlled internal structure of diameters of 610±43μm and pore sizes of 850±75μm in the horizontal plane and of 430±50μm in the vertical direction is presented in this paper to illustrate the promise of the developed model as applied to the 3D scaffold fabrication.
Projection Microfabrication of Three-Dimensional Scaffolds for Tissue Engineering
Authors: Han Li-Hsin , Mapili Gazell , Chen Shaochen , Roy Krishnendu
Published: April 2008

This article presents a micromanufacturing method for direct projection printing of three-dimensional scaffolds for applications in the field of tissue engineering by using a digital micromirror-array device (DMD) in a layer-by-layer process. Multilayered scaffolds are microfabricated using curable materials through an ultraviolet (UV) photopolymerization process. The prepatterned UV light is projected onto the photocurable polymer solution by creating the “photomask” design with a graphic software. Poly(ethylene glycol) diacrylate is mixed with a small amount of dye (0.3wt%) to enhance the fabrication resolution of the scaffold. The DMD fabrication system is equipped with a purging mechanism to prevent the accumulation of oligomer, which could interfere with the feature resolution of previously polymerized layers. The surfaces of the predesigned multilayered scaffold are covalently conjugated with fibronectin for efficient cellular attachment. Our results show that murine marrow-derived progenitor cells successfully attached to fibronectin-modified scaffolds.
Mechanism of Upgrading Low-Grade Solar Thermal Energy and Experimental Validation
Authors: Hong Hui , Jin Hongguang , Sui Jun , Ji Jun
Published: April 2008

Solar thermochemical processes inherently included the conversion of solar thermal energy into chemical energy. In this paper, a new mechanism of upgrading the energy level of solar thermal energy at around 200°C was revealed based on the second law thermodynamics and was then experimentally proven. An expression was derived to describe the upgrading of the energy level from low-grade solar thermal energy to high-grade chemical energy. The resulting equation explicitly reveals the interrelations of energy levels between middle-temperature solar thermal energy and methanol fuel, and identifies the interactions of mean solar flux and the reactivity of methanol decomposition. The proposed mechanism was experimentally verified by using the fabricated 5kW prototype of the receiver∕reactor. The agreement between the theoretical and the experimental results proves the validity of the mechanism for upgrading the energy level of low-grade solar thermal energy by integrating clean synthetic fuel. Moreover, the application of this new middle-temperature solar∕methanol hybrid thermochemical process into a combined cycle is expected to have a net solar-to-electric efficiency of about 27.8%, which is competitive with other solar-hybrid thermal power plants using high-temperature solar thermal energy. The results obtained here indicate the possibility of utilizing solar thermal energy at around 200°C for electricity generation with high efficiency by upgrading the energy level of solar thermal energy, and provide an enhancement to solar thermal power plants with the development of this low-grade solar thermochemical technology in the near future.
Discharge of Thermal Storage Tanks via Immersed Baffled Heat Exchangers: Numerical Model of Flow and Temperature Fields
Authors: Su Yan , Davidson Jane H.
Published: April 2008

A model of a thermal storage tank in which stored energy is extracted via an immersed heat exchanger is presented and used to predict transient temperature and velocity fields in tanks with and without baffles. The heat exchanger is modeled as a porous medium within the storage fluid. A simple cylindrical baffle that creates an annular space in which a coiled tube heat exchanger is positioned provides a modest increase in the rate of energy extraction compared to a tank with no baffle. The improved discharge rate is attributed to an increase in the flow speed across the heat exchanger. A baffle with greater hydraulic resistance slows the flow and reduces performance.
Thermal Properties of Metal-Coated Vertically Aligned Single-Wall Nanotube Arrays
Authors: Panzer M. A. , Zhang G. , Mann D. , Hu X. , Pop E. , Dai H. , Goodson K. E.
Published: April 2008

Owing to their high thermal conductivities, carbon nanotubes (CNTs) are promising for use in advanced thermal interface materials. While there has been much previous research on the properties of isolated CNTs, there are few thermal data for aligned films of single wall nanotubes. Furthermore, such data for nanotube films do not separate volume from interface thermal resistances. This paper uses a thermoreflectance technique to measure the volumetric heat capacity and thermal interface resistance and to place a lower bound on the internal volume resistance of a vertically aligned single wall CNT array capped with an aluminum film and palladium adhesion layer. The total thermal resistance of the structure, including volume and interface contributions, is 12m2KMW−1. The data show that the top and bottom interfaces of the CNT array strongly reduce its effective vertical thermal conductivity. A low measured value for the effective volumetric heat capacity of the CNT array shows that only a small volume fraction of the CNTs participate in thermal transport by bridging the two interfaces. A thermal model of transport in the array exploits the volumetric heat capacity to extract an individual CNT-metal contact resistance of 10m2K1GW−1 (based on the annular area Aa=πdb), which is equivalent to the volume resistance of 14nm of thermal SiO2. This work strongly indicates that increasing the fraction of CNT-metal contacts can reduce the total thermal resistance below 1m2KMW−1.
Heat Transport Characteristics in a Miniature Flat Heat Pipe With Wire Core Wicks
Authors: Jiao A. J. , Ma H. B. , Critser J. K.
Published: April 2008

A mathematical model predicting the heat transport capability in a miniature flat heat pipe (FHP) with a wired wick structure was developed to analytically determine its maximum heat transport rate including the capillary limit. The effects of gravity on the profile of the thin-film-evaporation region and the distribution of the heat flux along a curved surface were investigated. The heat transfer characteristics of the thin-film evaporation on the curved surface were also analyzed and compared with that on a flat surface. Combining the analysis on the thin-film-condensation heat transfer in the condenser, the model can be used to predict the total temperature drop between the evaporator and condenser in the FHP. In order to verify the model, an experimental investigation was conducted. The theoretical results predicted by the model agree well with the experimental data for the heat transfer process occurring in the FHP with the wired wick structure. Results of the investigation will assist in the optimum design of the curved-surface wicks to enlarge the thin-film-evaporation region and a better understanding of heat transfer mechanisms in heat pipes.
Experimental Analysis of Overall Thermal Properties of Parabolic Trough Receivers
Authors: Lüpfert Eckhard , Riffelmann Klaus-J. , Price Henry , Burkholder Frank , Moss Tim
Published: April 2008

The heat loss of a receiver in a parabolic trough collector plays an important role in collector performance. A number of methods have been used to measure the thermal loss of a receiver tube depending on its operating temperature. This paper presents methods for measuring receiver heat losses including field measurements and laboratory setups both based on energy balances from the hot inside of the receiver tube to the ambient. Further approaches are presented to measure and analyze the temperature of the glass envelope of evacuated receivers and to model overall heat losses and emissivity coefficients of the receiver. Good agreement can be found between very different approaches and independent installations. For solar parabolic trough plants operating in the usual 390°C temperature range, the thermal loss is around 300W∕m receiver length.
Optimal Heat Collection Element Shapes for Parabolic Trough Concentrators
Authors: Bennett Charles L.
Published: April 2008

For nearly 150years, the cross section of the heat collection tubes used at the focus of parabolic trough solar concentrators has been circular. This type of tube is obviously simple and easily fabricated, but it is not optimal. It is shown in this article that the optimal shape, assuming a perfect parabolic figure for the concentrating mirror, is instead oblong and is approximately given by a pair of facing parabolic segments.
Formation of Highly Aligned Grooves on Inner Surface of Semipermeable Hollow Fiber Membrane for Directional Axonal Outgrowth
Authors: Long Yu , Zhang Ning , Huang Yong , Wen Xuejun
Published: April 2008

It is generally believed that organized neural architecture is essential for nervous system development, function, and regeneration. In the absence of guidance cues, regenerating axons may lose their directions and become misaligned, resulting in the formation of neuromas and/or misappropriate connections. To help regenerate axons across damaged regions and guide them to appropriate targets, some bridging devices such as microgrooves are being intensively researched to achieve a better directional axonal growth. This paper reports a novel fabrication process to generate a highly aligned groove texture on the inner surface of semipermeable hollow fiber membranes (HFMs). HFMs have demonstrated promising results in guiding axonal regeneration. The fabrication process utilized a wet phase-inversion procedure with polyurethane (PU) as model polymer, dimethyl sulfoxide (DMSO) as solvent, and water as nonsolvent. Data indicated that highly aligned groove texture could be formed on the HFM inner surface by carefully controlling phase-inversion conditions such as the polymer solution flow rate, and/or nonsolvent flow rate, and/or polymer solution concentration ratio. The texture forming mechanism is qualitatively explained using a PU-DMSO-water ternary phase diagram and the dynamics of fluid instability. Axonal outgrowth on the HFM with aligned grooves showed the highly aligned orientation and improved axonal outgrowth length. This study may eventually lead to a new and effective way to fabricate nerve grafts for the spinal cord injury and nerve damage treatment based on this highly aligned three dimensional scaffold.
Study of Impact-Induced Mechanical Effects in Cell Direct Writing Using Smooth Particle Hydrodynamic Method
Authors: Wang Wei , Huang Yong , Grujicic Mica , Chrisey Douglas B.
Published: April 2008

Biomaterial direct-write technologies have been receiving more and more attention as rapid prototyping innovations in the area of tissue engineering, regenerative medicine, and biosensor∕actuator fabrication based on computer-aided designs. However, cell damage due to the mechanical impact during cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to investigate the impact-induced cell mechanical loading profile in cell landing in terms of stress, acceleration, and maximum shear strain component during cell direct writing using a mesh-free smooth particle hydrodynamic method. Such cell mechanical loading profile information can be used to understand and predict possible impact-induced cell damage. It is found that the cell membrane usually undergoes a relatively severe deformation and the cell mechanical loading profile is dependent on the cell droplet initial velocity and the substrate coating thickness. Two important impact processes may occur during cell direct writing: the first impact between the cell droplet and the substrate coating and the second impact between the cell and the substrate. It is concluded that the impact-induced cell damage depends not only on the magnitudes of stress, acceleration, and∕or shear strain but also the loading history that a cell experiences.
Replication Quality of Flow-Through Microfilters in Microfluidic Lab-on-a-Chip for Blood Typing by Microinjection Molding
Authors: Lee Bong-Kee , Hwang Chul Jin , Kim Dong Sung , Kwon Tai Hun
Published: April 2008

In the present study, replication of flow-through microfilters in the newly developed microfluidic lab-on-a-chip for blood typing by microinjection molding process was experimentally investigated. As a precise replication of the microfilters was required in order to effectively filter out agglutinated red blood cells, the effects of important processing conditions on the replication of the flow-through microfilters were investigated. By using a mold insert fabricated by a nickel electroplating process and a newly designed mold base, microinjection molding experiments were carried out. A three-dimensional solid model reconstruction method was proposed with the help of specific features characterizing the geometry of microfilters, and accordingly, the feature values of the replicated microfilters were measured by a noncontact optical measurement system. So reconstructed solid modeling result was then used to investigate the effects of various processing conditions, such as a flow rate, a mold temperature, and a packing pressure. Amongst the processing conditions investigated in the present study, the flow rate was found to be the most important one.
Innate Immune Activation Through Nalp3 Inflammasome Sensing of Asbestos and Silica
Authors: Dostert Catherine , Pétrilli Virginie , Van Bruggen Robin , Steele Chad , Mossman Brooke T. , Tschopp Jürg
Published: April 2008

The inhalation of airborne pollutants, such as asbestos or silica, is linked to inflammation of the lung, fibrosis, and lung cancer. How the presence of pathogenic dust is recognized and how chronic inflammatory diseases are triggered are poorly understood. Here, we show that asbestos and silica are sensed by the Nalp3 inflammasome, whose subsequent activation leads to interleukin-1β secretion. Inflammasome activation is triggered by reactive oxygen species, which are generated by a NADPH oxidase upon particle phagocytosis. (NADPH is the reduced form of nicotinamide adenine dinucleotide phosphate.) In a model of asbestos inhalation, Nalp3
–/–
mice showed diminished recruitment of inflammatory cells to the lungs, paralleled by lower cytokine production. Our findings implicate the Nalp3 inflammasome in particulate matter–related pulmonary diseases and support its role as a major proinflammatory “danger” receptor.
Evaluation of Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry in Comparison to 16S rRNA Gene Sequencing for Species Identification of Nonfermenting Bacteria
Authors: Mellmann A. , Cloud J. , Maier T. , Keckevoet U. , Ramminger I. , Iwen P. , Dunn J. , Hall G. , Wilson D. , LaSala P. , Kostrzewa M. , Harmsen D.
Published: April 2008

Nonfermenting bacteria are ubiquitous environmental opportunists that cause infections in humans, especially compromised patients. Due to their limited biochemical reactivity and different morphotypes, misidentification by classical phenotypic means occurs frequently. Therefore, we evaluated the use of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) for species identification. By using 248 nonfermenting culture collection strains composed of 37 genera most relevant to human infections, a reference database was established for MALDI-TOF MS-based species identification according to the manufacturer's recommendations for microflex measurement and MALDI BioTyper software (Bruker Daltonik GmbH, Leipzig, Germany), i.e., by using a mass range of 2,000 to 20,000 Da and a new pattern-matching algorithm. To evaluate the database, 80 blind-coded clinical nonfermenting bacterial strains were analyzed. As a reference method for species designation, partial 16S rRNA gene sequencing was applied. By 16S rRNA gene sequencing, 57 of the 80 isolates produced a unique species identification (≥99% sequence similarity); 11 further isolates gave ambiguous results at this threshold and were rated as identified to the genus level only. Ten isolates were identified to the genus level (≥97% similarity); and two isolates had similarity values below this threshold, were counted as not identified, and were excluded from further analysis. MALDI-TOF MS identified 67 of the 78 isolates (85.9%) included, in agreement with the results of the reference method; 9 were misidentified and 2 were unidentified. The identities of 10 randomly selected strains were 100% correct when three different mass spectrometers and four different cultivation media were used. Thus, MALDI-TOF MS-based species identification of nonfermenting bacteria provided accurate and reproducible results within 10 min without any substantial costs for consumables.
The FUSE Binding Protein Is a Cellular Factor Required for Efficient Replication of Hepatitis C Virus
Authors: Zhang Zhengbin , Harris Dylan , Pandey Virendra N.
Published: April 2008

Hepatitis C virus (HCV) infection is the leading cause of liver cirrhosis and hepatocellular carcinoma and one of the primary indications for liver transplantation. The molecular mechanisms underlying the actions of host factors in HCV replication remain poorly defined. FUSE (far upstream element of the c-
myc
proto-oncogene) binding protein (FBP) is a cellular factor that we have identified as a binder of HCV 3′ nontranslated region (3′NTR). Mapping of the binding site showed that FBP specifically interacts with the poly(U) tract within the poly(U/UC) region of the 3′NTR. Silencing of FBP expression by small interfering RNA in cells carrying HCV subgenomic replicons severely reduced viral replication, while overexpression of FBP significantly enhanced viral replication. We confirmed these observations by an in vitro HCV replication assay in the cell-free replicative lysate, which suggested that there is a direct correlation between the cellular FBP level and HCV replication. FBP immunoprecipitation coprecipitated HCV nonstructural protein 5A (NS5A), indicating that FBP interacts with HCV NS5A, which is known to function as a link between HCV translation and replication. Although FBP is mainly localized in the nucleus, we found that in MH14 cells a significant level of this protein is colocalized with NS5A in the cytosol, a site of HCV replication. While the mechanism of FBP involvement in HCV replication is yet to be delineated, our findings suggest that it may be an important regulatory component that is essential for efficient replication of HCV.
In Vitro and In Vivo Gene Therapy Vector Evolution via Multispecies Interbreeding and Retargeting of Adeno-Associated Viruses
Authors: Grimm Dirk , Lee Joyce S. , Wang Lora , Desai Tushar , Akache Bassel , Storm Theresa A. , Kay Mark A.
Published: April 2008

Adeno-associated virus (AAV) serotypes differ broadly in transduction efficacies and tissue tropisms and thus hold enormous potential as vectors for human gene therapy. In reality, however, their use in patients is restricted by prevalent anti-AAV immunity or by their inadequate performance in specific targets, exemplified by the AAV type 2 (AAV-2) prototype in the liver. Here, we attempted to merge desirable qualities of multiple natural AAV isolates by an adapted DNA family shuffling technology to create a complex library of hybrid capsids from eight different wild-type viruses. Selection on primary or transformed human hepatocytes yielded pools of hybrids from five of the starting serotypes: 2, 4, 5, 8, and 9. More stringent selection with pooled human antisera (intravenous immunoglobulin [IVIG]) then led to the selection of a single type 2/type 8/type 9 chimera, AAV-DJ, distinguished from its closest natural relative (AAV-2) by 60 capsid amino acids. Recombinant AAV-DJ vectors outperformed eight standard AAV serotypes in culture and greatly surpassed AAV-2 in livers of naïve and IVIG-immunized mice. A heparin binding domain in AAV-DJ was found to limit biodistribution to the liver (and a few other tissues) and to affect vector dose response and antibody neutralization. Moreover, we report the first successful in vivo biopanning of AAV capsids by using a new AAV-DJ-derived viral peptide display library. Two peptides enriched after serial passaging in mouse lungs mediated the retargeting of AAV-DJ vectors to distinct alveolar cells. Our study validates DNA family shuffling and viral peptide display as two powerful and compatible approaches to the molecular evolution of novel AAV vectors for human gene therapy applications.
Partial Functional Complementation of a Pseudorabies Virus UL25 Deletion Mutant by Herpes Simplex Virus Type 1 pUL25 Indicates Overlapping Functions of Alphaherpesvirus pUL25 Proteins
Authors: Kuhn Jana , Leege Tobias , Klupp Barbara G. , Granzow Harald , Fuchs Walter , Mettenleiter Thomas C.
Published: April 2008

Homologs of the UL25 gene product of herpes simplex virus 1 (HSV-1) are highly conserved among the
Herpesviridae
. However, their exact function during viral replication is unknown. Current evidence suggests that in the alphaherpesvirus pseudorabies virus (PrV) the capsid-associated pUL25 plays a role in primary envelopment of DNA-containing mature capsids at the inner nuclear membrane. In the absence of pUL25, capsids were found in close association with the inner nuclear membrane, but nuclear egress was not observed (B. G. Klupp, H. Granzow, G. M. Keil, and T. C. Mettenleiter, J. Virol. 80:6235-6246, 2006). In contrast, HSV-1 pUL25 has been assigned a role in stable packaging of viral genomes (N. Stow, J. Virol. 75:10755-10765, 2001). Despite these apparently divergent functions, we wanted to assess whether the high sequence homology translates into functional homology. Therefore, we first analyzed a newly constructed HSV-1 UL25 deletion mutant in our assay system and observed a similar phenotype as in PrV. In the nuclei of infected cells, numerous electron-dense C capsids were detected, whereas primary envelopment of these capsids did not ensue. In agreement with results from PrV, vesicles were observed in the perinuclear space. Since these data indicated functional homology, we analyzed the ability of pUL25 of HSV-1 to complement a PrV UL25 deletion mutant and vice versa. Whereas a HSV-1 pUL25-expressing cell line partially complemented the pUL25 defect in PrV, reciprocal complementation of a HSV-1 UL25 deletion mutant by PrV pUL25 was not observed. Thus, our data demonstrate overlapping, although not identical functions of these two conserved herpesvirus proteins, and point to a conserved functional role in herpes virion formation.
During Herpes Simplex Virus Type 1 Infection of Rabbits, the Ability To Express the Latency-Associated Transcript Increases Latent-Phase Transcription of Lytic Genes
Authors: Giordani Nicole V. , Neumann Donna M. , Kwiatkowski Dacia L. , Bhattacharjee Partha S. , McAnany Peterjon K. , Hill James M. , Bloom David C.
Published: April 2008

Trigeminal ganglia (TG) from rabbits latently infected with either wild-type herpes simplex virus type 1 (HSV-1) or the latency-associated transcript (LAT) promoter deletion mutant 17ΔPst were assessed for their viral chromatin profile and transcript abundance. The wild-type 17
syn
+ genomes were more enriched in the transcriptionally permissive mark dimethyl H3 K4 than were the 17ΔPst genomes at the 5′ exon and ICP0 and ICP27 promoters. Reverse transcription-PCR analysis revealed significantly more ICP4,
tk
, and glycoprotein C lytic transcripts in 17
syn
+ than in 17ΔPst. These results suggest that, for efficient reactivation from latency in rabbits, the LAT is important for increased transcription of lytic genes during latency.
Scaffolding Proteins Altered in the Ability To Perform a Conformational Switch Confer Dominant Lethal Assembly Defects
Authors: Cherwa James E. , Uchiyama Asako , Fane Bentley A.
Published: April 2008

In the φX174 procapsid crystal structure, 240 external scaffolding protein D subunits form 60 pairs of asymmetric dimers, D
1
D
2
and D
3
D
4
, in a non-quasi-equivalent structure. To achieve this arrangement, α-helix 3 assumes two different conformations: (i) kinked 30° at glycine residue 61 in subunits D
1
and D
3
and (ii) straight in subunits D
2
and D
4
. Substitutions for G61 may inhibit viral assembly by preventing the protein from achieving its fully kinked conformation while still allowing it to interact with other scaffolding and structural proteins. Mutations designed to inhibit conformational switching in α-helix 3 were introduced into a cloned gene, and expression was demonstrated to inhibit wild-type morphogenesis. The severity of inhibition appears to be related to the size of the substituted amino acid. For infections in which only the mutant protein is present, morphogenesis does not proceed past the first step that requires the wild-type external scaffolding protein. Thus, mutant subunits alone appear to have little or no morphogenetic function. In contrast, assembly in the presence of wild-type and mutant subunits is blocked prematurely, before D protein is required in a wild-type infection, or channeled into an off-pathway reaction. These data suggest that the wild-type protein transports the inhibitory protein to the pathway. Viruses resistant to the lethal dominant proteins were isolated, and mutations were mapped to the coat and internal scaffolding proteins. The affected amino acids cluster in the atomic structure and may act to exclude mutant subunits from occupying particular positions atop pentamers of the viral coat protein.
International conference on physical activity and obesity in children: summary statement and recommendationsThis summary statement and recommendations from the International Conference on Physical Activity and Obesity in Children is being published simultaneously in the International Journal of Pediatric Obesity and Applied Physiology, Nutrition, and Metabolism.For the International Association for the Study of Obesity Physical Activity Task Force and the Conference Speaker Panel (the conference speaker panel includes Tom Baranowski, Claude Bouchard, Kelly Brownell, Deborah Cohen, William H. Dietz, Rod Dishman, Mary Flynn, William Haskell, James O. Hill, W.P.T. (Philip) James, Russell Pate, John Peters, Michael Pratt, Harry Rutter, James Sallis, Jo Salmon, Chantal Simon, and Boyd Swinburn).
Authors: Katzmarzyk Peter T. , Baur Louise A. , Blair Steven N. , Lambert Estelle V. , Oppert Jean-Michel , Riddoch Chris
Published: April 2008

The increasing prevalence of obesity among the world’s children and youth was the impetus for an international conference convened in Toronto, Canada, to examine issues related to physical activity and obesity in children (24–27 June 2007). The goal of the conference was to assimilate, interpret, and share scientific evidence with key stakeholders to develop recommendations concerning effective physical activity policies and programs to address obesity in children. The conference was attended by approximately 1000 delegates from 33 countries who gathered to listen to the invited speakers and to share information on promising practices related to the promotion of physical activity with the aim of reducing the burden of obesity in children. The major topics addressed at the conference included the biological and behavioural causes of obesity, current and past levels of physical activity and sedentarism in children, the role of the social, family, and built environments in addressing the physical activity deficit, and the role of legislation and industry in promoting physical activity. Promising physical activity interventions among children were presented, and important research, policy, and practice recommendations to address the issue of physical inactivity and obesity were provided.
Acute physical activity and sports injuries in children
Authors: Collard Dorine C.M. , Verhagen Evert A.L.M. , Chin A Paw Marijke J.M. , van Mechelen Willem
Published: April 2008

An increase in the physical activity of individuals has many health benefits, but a drawback of an increase in physical activity is the risk of related injuries. To reduce the short- and long-term effects in terms of social and economic consequences, prevention of physical activity injuries is an important challenge. A sequence of prevention model has been proposed that aims to prevent physical activity injuries in different steps. The model includes (i) identification of the problem in terms of incidence and severity of physical activity injuries, (ii) identification of the risk factors and injury mechanisms that play a role in the occurrence of physical activity injuries, (iii) introduction of measures that are likely to reduce the future risk and (or) severity of physical activity injuries, and (iv) evaluation of the effectiveness of the measures by conducting a randomized controlled trial (RCT). This review describes what is currently known about all of the various aspects of the sequence of prevention in children (steps i–iv).
A pediatric perspective on inflammation and oxidative stress in response to exercise
Authors: Timmons Brian W. , Raha Sandeep
Published: April 2008

Dr. Oded Bar-Or was a giant in the area of pediatric exercise science and made numerous contributions to the health of children around the world. He also had a significant impact on a relatively new area of pediatric exercise science — pediatric exercise immunology. Under his supervision, some aspects of the immunobiology of exercise have been unravelled from a pediatric perspective. In general, healthy children experience less inflammatory stress in response to standardized exercise, while demonstrating an exercise-induced elevation in the anabolic cytokine IL-8. Mechanisms for the maturity- and age-dependent changes in cytokine responses to exercise are unknown, but may involve oxidative stress. Studies of oxidative stress and exercise in children are scant, but preliminary data suggests that, like the inflammatory cytokine response to exercise, children may experience less oxidative stress in response to intense exercise. We propose that the links between exercise, inflammatory and oxidative stress, and growth factors will be important to understand in the context of how exercise contributes to optimal growth and development during childhood. This understanding will be particularly relevant for childhood diseases that restrict growth.
Reproducibility of short-term food intake and subjective appetite scores after a glucose preload, ventilation threshold, and body composition in boys
Authors: Bellissimo Nick , Thomas Scott G. , Pencharz Paul B. , Goode Robert C. , Anderson G. Harvey
Published: April 2008

The objective of these studies was to assess the reproducibility of (i) short-term food intake (FI) and subjective appetite following a glucose preload, (ii) ventilation threshold (VT) and subjective appetite after short-duration exercise, and (iii) body composition assessed by bioelectrical impedance (BIA). On two separate weekend mornings, boys (n = 11; aged 9–14 years) received drinks containing 50 g glucose made up to 250 mL with water 2 h after a standardized breakfast. FI from a pizza meal was measured 30 min later. Subjective appetite was measured before and after the glucose loads and the VT measures. VTs were measured on 2 weekday evenings, 1 week apart. BIA was measured during the FI assessment sessions. Short-term FI after the glucose preload was highly reproducible. Mean energy intake was 925 ± 139 kcal on the first day and 988 ± 147 kcal on the second day (coefficient of repeatability (CR) = 259 kcal; intra-class correlation coefficient (ICC) = 0.96). Moderate reproducibility of the average appetite score was found at 30 min (CR = 24 mm; ICC = 0.82). Subjective appetite was increased similarly by short-duration exercise on both days (CR = 19 mm). Absolute VT was more highly reproducible (CR = 359 mL O2·min–1, ICC = 0.85) than VT expressed on the basis of body weight (CR = 8.0 mL O2·kg–1·min–1, ICC = 0.59). Fat mass (FM) estimated from BIA was highly reproducible (CR = 2.7 kg, ICC = 0.95), but underestimated FM compared with skinfolds. In conclusion, FI and subjective appetite scores in response to glucose preloads, VT, subjective appetite after short-duration exercise, and estimates of FM from BIA are reproducible in boys.
Parents report intrapersonal, interpersonal, and environmental barriers to supporting healthy eating and physical activity among their preschoolers
Authors: Dwyer John , Needham Lisa , Simpson Janis Randall , Heeney Elizabeth Shaver
Published: April 2008

There is an increasing trend in childhood obesity in Canada and many preschool children are overweight or obese. The objective of this study was to explore parents’ experiences and challenges in supporting healthy eating and physical activity among their preschool children. A qualitative descriptive study involving 5 focus groups was conducted. A convenience sample of 39 parents from 3 childcare centres in Hamilton, Ontario, participated. Parents were English speaking and had a child aged 2–5 years attending the childcare centre for at least 3 months. The research team read transcripts of the audio-taped sessions and used a constant comparison approach to develop themes, which involved coding comments by continually referring to previously coded comments for comparison. The social ecological model was used to organize the themes into 3 higher-level categories: (i) intrapersonal (individual): preschoolers’ preferences and health; (ii) interpersonal (interactions): parents’ and others’ different views and practices, influence of the childcare centre, parents’ lack of time, and family structure; and (iii) physical environment: accessibility of healthy foods, preschoolers with special needs, media influence, weather, lack of safety, and inaccessible resources. Parents perceived that there are various intrapersonal, interpersonal, and environmental barriers to supporting healthy eating and physical activity among their children. Program planners and health professionals can consider these barriers when developing interventions to promote healthy bodyweights among preschoolers.
Rheological modelling of masonry creepThis article is one of a selection of papers published in this Special Issue on Masonry.
Authors: Choi Kyoung-Kyu , Lissel Shelley L. , Reda Taha Mahmoud M.
Published: April 2008

In the present study, masonry creep was experimentally investigated. Creep tests were performed on masonry prisms, which were produced using standard fired clay brick and standard Type S mortar. A total of 11 sets of loaded and unloaded masonry specimens were tested under sustained load with three main parameters: stress level, masonry age at loading, and relative humidity. The unloaded prisms compensated for the effects of shrinkage. In this article, the ability of a number of rheological models reported in the literature are examined for their ability to predict masonry creep. Moreover, a new rheological model, one that considers the effect of stress level and masonry age at loading, is proposed. The system parameters of the proposed model were identified using the experimental data. The proposed model was then validated using masonry creep data that was reported by other researchers, but not used in model development. It is shown that the creep behaviour of masonry can be modelled with good accuracy using the proposed rheological model.
Approaches to the discovery of new antibacterial agents based on bacteriocinsThis paper is one of a selection of papers published in this Special Issue, entitled CSBMCB — Systems and Chemical Biology, and has undergone the Journal's usual peer review process.
Authors: Sit Clarissa S. , Vederas John C.
Published: April 2008

The development of antibiotic resistance in pathogenic bacteria has led to a search for novel classes of antimicrobial drugs. Bacteriocins are peptides that are naturally produced by bacteria and have considerable potential to fulfill the need for more effective bacteriocidal agents. In this mini-review, we describe research aimed at generating analogues of bacteriocins from lactic acid bacteria, with the goal of gaining a better understanding of structure–activity relationships in these peptides. In particular, we report recent findings on synthetic analogues of leucocin A, pediocin PA1, and lacticin 3147 A2, as well as on the significance of these results for the design and production of new antibiotics.
Plastic anisotropy of soft reconstituted clays
Authors: Karstunen Minna , Koskinen Mirva
Published: April 2008

The aim of the paper is to extend the experimental validation of the S-CLAY1 model, which is a recently proposed elastoplastic constitutive model that accounts for initial and plastic strain-induced anisotropy. Drained stress path controlled tests were performed on reconstituted samples of four Finnish clays to study the effects of anisotropy in the absence of the complexities of structure present in natural undisturbed clays. Each test involved several loading, unloading, and reloading stages with different values of stress ratio and, hence, induced noticeable changes in the fabric anisotropy. Comparisons between test results and model predictions with the S-CLAY1 model and the modified Cam clay model demonstrate that despite its simplicity, the S-CLAY1 model can provide excellent predictions of the behaviour of unstructured soil.
Finite element analysis of highway construction in peat bog
Authors: Tan Yong
Published: April 2008

Parts of a U.S. Route 44 relocation project span across cranberry bog areas with deep peat deposits. The peat in the proposed roadway side was completely excavated and backfilled with granular soils, and using sheet pile walls as retaining structures. As peat exhibits low strength, high compressibility, and significant creep behavior, the long-term performance of the sheet pile walls was a great concern. To monitor the development of sheet pile deflections and total lateral earth pressures in peat, selected sheet piles located in peat deposits were instrumented with pressure cells and inclinometer casings. Furthermore, to understand the soil–structure interaction mechanism during roadway construction, the finite element (FE) code PLAXIS was employed to continuously model roadway construction in peat deposits. Peat was simulated by a soft soil creep (SSC) model, which can account for creep effects. One of the challenges in this simulation was how to model deep dynamic compaction (DDC), since the enormous momentum induced by DDC would cause local failure of the soil body and consequently result in termination of the program. This problem was satisfactorily solved by using a dynamic approach presented in this paper, and the FE-calculated results were compared with the field measurements. The comparison indicated that FE modeling yields predictions in a good agreement with field measurements and also could provide some reasonable explanations for the field observations.