bluuebunny/crossref_metadata_2025 huggingface dataset:
Deep level optical spectroscopy of GaN nanorods
Authors: Armstrong A. , Li Q. , Bogart K. H. A. , Lin Y. , Wang G. T. , Talin A. A.
Published: September 2009

Deep level defects in GaN nanorods (NRs) grown by metal organic chemical vapor deposition were studied using deep level optical spectroscopy (DLOS) and microphotoluminescence (μ-PL). DLOS determines the absolute optical ionization energy, discerns majority versus minority carrier photoemission, and has sensitivity to nonradiative defect centers. These are important aspects of deep level spectroscopy for NRs that are not obtainable using luminescence techniques alone. Deep level defects were observed via DLOS at Ec−2.81 eV, Ec−1.77 eV, and Ec−3.19 eV, where Ec is the conduction band minimum. The μ-PL spectra revealed a dominant defect band peaked near 2.19 eV. The Ec−2.81 eV band gap state and the 2.19 eV PL peak can be attributed to the same defect center within a one-dimensional configuration-coordinate model. The NR DLOS spectra are compared to reports for thin film GaN, and possible physical origins of the deep level defects are discussed.
Scaling of surface roughness in sputter-deposited ZnO:Al thin films
Authors: Mohanty Bhaskar Chandra , Choi Hong-Rak , Cho Yong Soo
Published: September 2009

We have studied surface roughness scaling of ZnO:Al thin films grown by rf magnetron sputtering of a compound target within framework of the dynamic scaling theory using atomic force microscopy. We have observed a crossover in scaling behavior of surface roughness at a deposition time of 25 min. Both the regimes are characterized by power-law dependence of local surface width w(r,t) on deposition time for small r, typical of anomalous scaling. The scaling exponents for the first regime indicate the existence of a new dynamics. For t≥25 min, the films follow super-rough scaling behavior with global exponents α=1.5±0.2 and β=1.03±0.01, and local exponents αlocal=1 and βlocal=0.67±0.05. The anomaly in the scaling behavior of the films is discussed in terms of the shadowing instability and bombardment of energetic particles during growth of the films.
A method for the temperature calibration of an infrared camera using water as a radiative source
Authors: Bower S. M. , Kou J. , Saylor J. R.
Published: September 2009

Presented here is an effective low-cost method for the temperature calibration of infrared cameras, for applications in the 0–100 °C range. The calibration of image gray level intensity to temperature is achieved by imaging an upwelling flow of water, the temperature of which is measured with a thermistor probe. The upwelling flow is created by a diffuser located below the water surface of a constant temperature water bath. The thermistor probe is kept immediately below the surface, and the distance from the diffuser outlet to the surface is adjusted so that the deformation of the water surface on account of the flow is small, yet the difference between the surface temperature seen by the camera and the bulk temperature measured by the thermistor is also small. The benefit of this method compared to typical calibration procedures is that, without sacrificing the quality of the calibration, relatively expensive commercial blackbodies are replaced by water as the radiative source (ε≈0.98 for the wavelengths considered here). A heat transfer analysis is provided, which improves the accuracy of the calibration method and also provides the user with guidance to further increases in accuracy of the method.
Density-functional calculations for self-assembled Bi-nanolines on the InAs(100) surface
Authors: AlZahrani A. Z. , Srivastava G. P.
Published: September 2009

We have performed an ab initio investigation of the stability, atomic geometry, and electronic properties of the self-assembled bismuth (Bi)-nanolines on the Bi-stabilized indium arsenide (InAs)(100) surface. Our calculations were performed within the local density approximation of the density functional theory, using pseudopotentials to describe the electron-ion interactions. We have examined several metastable Bi nanolines arrangements on the top of the Bi-stabilized InAs(100) surface. Our total energy calculations suggest that the most stable configuration of the Bi nanolines is formed by Bi dimers parallel to the Bi dimers on the Bi/InAs(100) surface. We have found that the structure is metallic with several occupied and unoccupied surface states within the bulk InAs gap region. These states are mainly due to the top and first sublayer Bi atoms. Our theoretically simulated scanning tunneling microscope (STM) image shows a very bright line along the [01¯1] direction, which is consistent with the experimental STM images.
One-step preparation of superlattices and nanocrystals using laser ablation
Authors: Tsuji Takeshi , Ozono Shogo , Hirai Takemasa , Mizuki Takeshi , Tsuji Masaharu
Published: September 2009

Superlattices with three-dimensional rodlike or tubular shapes and silver nanocrystals were produced instantaneously using a laser process without ligand reagents. In this laser ablation technique, the nanoparticles (NPs), generated using laser ablation of silver in an evacuated chamber, were deposited directly onto a liquid (ethylene glycol). On the other hand, no such structures were formed by laser ablation without a liquid, indicating that liquid plays an important role for formation of those products. Different from previous studies, in which superlattices of gold and silver NPs were formed using ligand molecules, the colloids prepared using laser ablation contained none. This study shows that superlattices can be formed via spontaneous assembly of spherical NPs using their hydrophobicity. On the other hand, it is suggested that nanocrystals were formed from spherical small NPs via a ripening process.
Design and performance of a flow-through polarization-modulation infrared reflection-absorption spectroscopy cell for time-resolved simultaneous surface and liquid phase detection under concentration and temperature perturbations
Authors: Meier Daniel M. , Urakawa Atsushi , Mäder Roland , Baiker Alfons
Published: September 2009

Design and performance of a flow-through cell for polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) suitable for simultaneous monitoring of species on surface and in liquid phase on a molecular level at a high time resolution (ca. 1 s) are presented. In particular, the cell was designed to allow periodic concentration and temperature perturbations and thus excite physicochemical phenomena of interest occurring at solid-liquid interfaces. Utilizing the perturbations and spectral responses of both surface and liquid phase species, their dynamic behavior, kinetics, and correlations can be studied. The detection sensitivity is greatly enhanced by the data processing employed in modulation excitation spectroscopy (MES). The cell design is based on a theoretical model. The IR beam path through a multiple-phase system consisting of air, prism, and liquid as well as light reflection at the surface of a sample were considered in order to maximize the detected IR light intensity and absorption by surface molecules. Its high surface sensitivity was demonstrated by CO adsorption on a thin Pt film in a liquid phase. Combination of the PM-IRRAS with concentration MES led to a significant sensitivity enhancement for the detection of surface and liquid phase species. The temperature, tunable in a wide range from 263–343 K, could be controlled within an accuracy of 0.1 K and also modulated periodically in a completely reversible manner, thus allowing accurate temperature MES experiments. With these capabilities, dynamic physicochemical processes at solid-liquid interfaces can be sensitively investigated.
Surface scattering effect on the electrical resistivity of single crystalline silver nanowires self-assembled on vicinal Si (001)
Authors: Huang Qiaojian , Lilley Carmen M. , Bode Matthias
Published: September 2009

Fundamental questions as to the nature of electron surface scattering in nanoscale materials remain unanswered. In order to isolate the effects of surface scattering from grain boundary scattering, single crystalline trapezoidal silver (Ag) nanowires were self-assembled on vicinal silicon substrate. The well established kinetic theory to model electron surface scattering effects on the electrical resistivity of nanowires was extended to include trapezoidal geometries. The experimentally measured electrical resistivity for Ag nanowires was found to fit the theoretical resistivity for the case of electrons diffusely scattering from the nanowire surface.
Quantum Monte Carlo study of Jastrow perturbation theory. I. Wave function optimization
Authors: Luo Hongjun , Hackbusch Wolfgang , Flad Heinz-Jürgen
Published: September 2009

We have studied an iterative perturbative approach to optimize Jastrow factors in quantum Monte Carlo calculations. For an initial guess of the Jastrow factor we construct a corresponding model Hamiltonian and solve a first-order perturbation equation in order to obtain an improved Jastrow factor. This process is repeated until convergence. Two different types of model Hamiltonians have been studied for both energy and variance minimization. Our approach can be considered as an alternative to Newton’s method. Test calculations revealed the same fast convergence as for Newton’s method sufficiently close to the minimum. However, for a poor initial guess of the Jastrow factor, the perturbative approach is considerably more robust especially for variance minimization. Usually only two iterations are sufficient in order to achieve convergence within the statistical error. This is demonstrated for energy and variance minimization for the first row atoms and some small molecules. Furthermore, our perturbation analysis provides new insight into some recently proposed modifications of Newton’s method for energy minimization. A peculiar feature of the analysis is the continuous use of cumulants which guarantees size-consistency and provides least statistical fluctuations in the Monte Carlo implementation.
Enhanced piezoelectric and ferroelectric properties in Mn-doped Na0.5Bi0.5TiO3–BaTiO3 single crystals
Authors: Zhang Qinhui , Zhang Yaoyao , Wang Feifei , Wang Yaojin , Lin Di , Zhao Xiangyong , Luo Haosu , Ge Wenwei , Viehland D.
Published: September 2009

High piezoelectric and ferroelectric properties have been found in Mn-doped Na0.5Bi0.5TiO3–BaTiO3 single crystals, which were grown by a top-seeded solution method. The electrical resistivity, dielectric constant, and ferroelectric and piezoelectric properties were all found to be notably enhanced by Mn. The piezoelectric constant d33 and electromechanical coupling coefficients kt and k31 were found to be as high as 483 pC/N, 0.56, and 0.40, respectively. These values are much higher than those previously reported for Pb-free piezoelectric crystals, demonstrating the real potential for alternative lead-free systems for sensor and piezoelectric applications.
Frozen state of spiral waves in excitable media
Authors: Luo Jinming , Zhang Bingsheng , Zhan Meng
Published: September 2009

It has long been observed in experiments that frozen state of spiral waves can spontaneously appear in both excitable and oscillatory media, in which several spiral waves coexist and are well separated by thin walls (shocks). In this work, we study the global structure of frozen state of spiral waves in excitable media and find that different from stationary shocks in oscillatory media, in excitable media the shock dynamics actually depends on the status of single spiral, which is also determined by the system parameter, i.e., the shock line can be stationary if the single spiral is rigidly rotating, whereas it can wiggle if the single spiral is meandering, and the wiggling amplitude increases with the degree of meandering. We also find the stationary structure of shock line can still be well predicted by a previous theory, which has been developed for the frozen state of spiral waves in oscillatory media. All these findings are generic and expected to be verified in experiments.
MeV proton beams generated by 3 mJ ultrafast laser pulses at 0.5 kHz
Authors: Hou Bixue , Nees John , Easter James , Davis Jack , Petrov George , Thomas Alexander , Krushelnick Karl
Published: September 2009

Well-collimated proton beams are generated from bulk glass along the target normal direction by tightly focused 55 fs, 3 mJ pulses from a laser operating at 0.5 kHz repetition rate. Proton beams with energies of >265 keV have an emission angle of about 16° full width at half maximum. Spectral measurements indicate proton energies exceeding 0.5 MeV with a flux of 3.2×109 s−1 sr−1 and the flux of measured protons with energies of greater than 90 keV is 8.5×1011 s−1 sr−1 on center.
Density functional calculations on atomic and electronic structures of amorphous HfO2/Si(001) interface
Authors: Chen G. H. , Hou Z. F. , Gong X. G.
Published: September 2009

The interface properties of amorphous hafnium dioxide (a-HfO2) in contact with silicon have been investigated by using the projector augmented wave method within the generalized gradient approximation. The a-HfO2 model structure of the interface is generated by ab initio molecular dynamics simulations in a melt-and-quench scheme. Calculations indicate that the simulated a-HfO2 essentially shows the characteristics of the experimental a-HfO2 structure. The results on a-HfO2/Si interface suggest that atomic coordination of interface Si atoms would significantly affect the interface electronic properties, e.g., the Hf–Si bond formed at the interface could result in metallic behavior. With band lineup of the core level, the valence band offset of a-HfO2/Si interface is determined to be 2.62±0.35 eV, in good agreement with recent experimental data.
The Interaction of Segregation and Suburbanization in an Agent-Based Model of Residential Location
Authors: Jayaprakash Ciriyam , Warren Keith , Irwin Elena , Chen Kan
Published: September 2009

We present a model of the interaction of segregation and suburbanization in determining residential location. The model incorporates differential income between two classes of agents, a simplified market mechanism for the purchase of housing, and a simple geographic structure of one central city and four symmetrically arranged suburbs. Agents derive utility from neighborhood racial composition, the size of their lot, private amenities that are specific to neighborhoods, and public amenities that stretch across municipalities. We find that the public-amenities term leads to a positive-feedback loop in which migration to suburbs increases the public amenities in those municipalities while lowering amenities in the central city, thus sparking further migration. When the minority agents are uniformly less affluent than the majority agents, this dynamic produces discontinuity in segregation as measured by centralization. Such discontinuities are typical of first-order phase transitions. When minority and majority incomes overlap, significant regions appear over which there are multistable equilibria at high and low levels of segregation, along with considerable sensitivity to the initial distribution of minority agents. We discuss the implications of these findings.
The Third Dimension in Urban Geography: The Urban-Volume Approach
Authors: Koomen Eric , Rietveld Piet , Bacao Fernando
Published: September 2009

A new methodology is presented that measures density in urban systems. By combining highly detailed height measurements with, amongst others, topographical data we are able to quantify urban volume. This new approach is demonstrated in two separate case studies that relate to the temporal and spatial dimension of the urban environment, respectively. In the first study the growth of the city of Amsterdam over the past century is studied. The urban-volume indicator is used to visualise and quantify the urban extension and intensification process. To critically analyse the spatiotemporal development of Amsterdam the self-organising-map approach is applied. Special attention is given to highlighting any signs of recent polynuclear development. The second case study compares the building-height frequency and spatial distribution of high-density zones in the four major Dutch cities. Additionally, the presence of built-up areas and the actual urban-volume values are explained simultaneously using a Heckman selection model.
Towards a Better Understanding of Building Regulation
Authors: van der Heijden Jeroen , de Jong Jitske
Published: September 2009

This paper reviews a large body of regulatory literature and applies four major debates to the field of building regulation and control. We find that this field has attracted little attention of regulatory scholars, whilst fields such as the ‘natural’ or ‘occupational’ environment are often addressed in regulatory studies. We furthermore find that studies of building regulation and control often lack theoretical descriptions or applications. We argue that such details are necessary for a better understanding of building regulations and control.
Intrinsic, nondeterministic circadian rhythm generation in identified mammalian neurons
Authors: Webb Alexis B. , Angelo Nikhil , Huettner James E. , Herzog Erik D.
Published: September 2009

Circadian rhythms are modeled as reliable and self-sustained oscillations generated by single cells. The mammalian suprachiasmatic nucleus (SCN) keeps near 24-h time in vivo and in vitro, but the identity of the individual cellular pacemakers is unknown. We tested the hypothesis that circadian cycling is intrinsic to a unique class of SCN neurons by measuring firing rate or
Period2
gene expression in single neurons. We found that fully isolated SCN neurons can sustain circadian cycling for at least 1 week. Plating SCN neurons at <100 cells/mm
2
eliminated synaptic inputs and revealed circadian neurons that contained arginine vasopressin (AVP) or vasoactive intestinal polypeptide (VIP) or neither. Surprisingly, arrhythmic neurons (nearly 80% of recorded neurons) also expressed these neuropeptides. Furthermore, neurons were observed to lose or gain circadian rhythmicity in these dispersed cell cultures, both spontaneously and in response to forskolin stimulation. In SCN explants treated with tetrodotoxin to block spike-dependent signaling, neurons gained or lost circadian cycling over many days. The rate of PERIOD2 protein accumulation on the previous cycle reliably predicted the spontaneous onset of arrhythmicity. We conclude that individual SCN neurons can generate circadian oscillations; however, there is no evidence for a specialized or anatomically localized class of cell-autonomous pacemakers. Instead, these results indicate that AVP, VIP, and other SCN neurons are intrinsic but unstable circadian oscillators that rely on network interactions to stabilize their otherwise noisy cycling.
Dendritic trafficking of BDNF mRNA is mediated by translin and blocked by the G196A (Val66Met) mutation
Authors: Chiaruttini C. , Vicario A. , Li Z. , Baj G. , Braiuca P. , Wu Y. , Lee F. S. , Gardossi L. , Baraban J. M. , Tongiorgi E.
Published: September 2009

Alternatively spliced brain-derived neurotrophic factor (BDNF) transcripts are targeted to distinct cellular compartments in neurons but the mechanisms underlying this sorting are unknown. Although only some BDNF isoforms are targeted to dendrites, we have found that the coding region common to all BDNF transcripts contains a constitutively active dendritic targeting signal and that this signal is suppressed in transcripts containing exons 1 or 4, which are restricted to the cell soma and proximal dendrites. This dendritic targeting signal is mediated by translin, an RNA-binding protein implicated in RNA trafficking, and is disrupted by the G196A mutation associated with memory deficits and psychiatric disorders. Molecular modeling and mutational studies indicate that the G196A mutation blocks dendritic targeting of BDNF mRNA by disrupting its interaction with translin. These findings implicate abnormal dendritic trafficking of BDNF mRNA in the pathophysiology of neuropsychiatric disorders linked to the G196A mutation.
Eukaryote-to-eukaryote gene transfer events revealed by the genome sequence of the wine yeast Saccharomyces cerevisiae EC1118
Authors: Novo Maite , Bigey Frédéric , Beyne Emmanuelle , Galeote Virginie , Gavory Frédérick , Mallet Sandrine , Cambon Brigitte , Legras Jean-Luc , Wincker Patrick , Casaregola Serge , Dequin Sylvie
Published: September 2009

Saccharomyces cerevisiae
has been used for millennia in winemaking, but little is known about the selective forces acting on the wine yeast genome. We sequenced the complete genome of the diploid commercial wine yeast EC1118, resulting in an assembly of 31 scaffolds covering 97% of the S288c reference genome. The wine yeast differed strikingly from the other
S. cerevisiae
isolates in possessing 3 unique large regions, 2 of which were subtelomeric, the other being inserted within an EC1118 chromosome. These regions encompass 34 genes involved in key wine fermentation functions. Phylogeny and synteny analyses showed that 1 of these regions originated from a species closely related to the
Saccharomyces
genus, whereas the 2 other regions were of non-
Saccharomyces
origin. We identified
Zygosaccharomyces bailii
, a major contaminant of wine fermentations, as the donor species for 1 of these 2 regions. Although natural hybridization between
Saccharomyces
strains has been described, this report provides evidence that gene transfer may occur between
Saccharomyces
and non-
Saccharomyces
species. We show that the regions identified are frequent and differentially distributed among
S. cerevisiae
clades, being found almost exclusively in wine strains, suggesting acquisition through recent transfer events. Overall, these data show that the wine yeast genome is subject to constant remodeling through the contribution of exogenous genes. Our results suggest that these processes are favored by ecologic proximity and are involved in the molecular adaptation of wine yeasts to conditions of high sugar, low nitrogen, and high ethanol concentrations.
Biogenesis of glutaminyl-mt tRNA
Gln
in human mitochondria
Authors: Nagao Asuteka , Suzuki Takeo , Katoh Takayuki , Sakaguchi Yuriko , Suzuki Tsutomu
Published: September 2009

Mammalian mitochondrial (mt) tRNAs, which are required for mitochondrial protein synthesis, are all encoded in the mitochondrial genome, while mt aminoacyl-tRNA synthetases (aaRSs) are encoded in the nuclear genome. However, no mitochondrial homolog of glutaminyl-tRNA synthetase (GlnRS) has been identified in mammalian genomes, implying that Gln-tRNA
Gln
is synthesized via an indirect pathway in the mammalian mitochondria. We demonstrate here that human mt glutamyl-tRNA synthetase (mtGluRS) efficiently misaminoacylates mt tRNA
Gln
to form Glu-tRNA
Gln
. In addition, we have identified a human homolog of the Glu-tRNA
Gln
amidotransferase, the hGatCAB heterotrimer. When any of the hGatCAB subunits were inactivated by siRNA-mediated knock down in human cells, the Glu-charged form of tRNA
Gln
accumulated and defects in respiration could be observed. We successfully reconstituted in vitro Gln-tRNA
Gln
formation catalyzed by the recombinant mtGluRS and hGatCAB. The misaminoacylated form of tRNA
Gln
has a weak binding affinity to the mt elongation factor Tu (mtEF-Tu), indicating that the misaminoacylated form of tRNA
Gln
is rejected from the translational apparatus to maintain the accuracy of mitochondrial protein synthesis.
What is ‘competence’ and how should education incorporate new technology's tools to generate ‘competent civic agents’
Authors: Haste Helen
Published: September 2009

This article addresses the competences needed in twenty‐first‐century life, especially in relation to civic participation, and the educational requirements to foster them in young people. New technologies are widely used by young people for informal social interaction, video game‐playing and giving voice to their views. Incorporation of these practices into the classroom has been fairly slow, despite their manifest potential for promoting agency and civic engagement. The article argues that this is in part due to the need for a cultural shift in education to accommodate them. Currently, many competences young people will need for the future world of interactive technology and ‘bottom‐up’ information, communication and democracy are mainly being developed through informal practices. These competences, which include adaptability, managing ambiguity and agency are discussed in relation to civic participation.
Meaning and identities: a visual performative pedagogy for socio‐cultural learning
Authors: Grushka Kathryn
Published: September 2009

In this article I present personalised socio‐cultural inquiry in visual art education as a critical and expressive material praxis. The model of Visual Performative Pedagogy and Communicative Proficiency for the Visual Art Classroom is presented as a legitimate means of manipulating visual codes, communicating meaning and mediating values through imaging technologies. It identifies that visual art studio learning outcomes as exhibition artworks facilitate the mediation and communication of ideas, and support understanding of individual identities, social behaviours, culture and beliefs.

A critical phenomenological methodology was used to explore longitudinal and case‐study learning insights about student learning in a post‐compulsory visual art curriculum in New South Wales, Australia. Through analysis of student artworks, reflective journals and post‐schooling case‐study interviews, the research identified that this unique learning environment developed visual communicative proficiency in the students.

The findings affirm the significance of personalised imaging inquiry strategies to support understandings about the self, society and culture. The studio pedagogies and visual arts education curriculum in NSW represents an alternative approach to a prescribed and explicit values curriculum. This article will identify the key elements of the model of Visual Performative Pedagogy and Communicative Proficiency for the Visual Art Classroom. It will expand on the aesthetic and critical approach in arts learning as studio pedagogy and the exhibition process that generates public benefits through socially embedded and embodied inquiry.
Do humans produce the speed–accuracy trade-off that maximizes reward rate?
Authors: Bogacz Rafal , Hu Peter T. , Holmes Philip J. , Cohen Jonathan D.
Published: September 2009

In this paper we investigate trade-offs between speed and accuracy that are produced by humans when confronted with a sequence of choices between two alternatives. We assume that the choice process is described by the drift diffusion model, in which the speed–accuracy trade-off is primarily controlled by the value of the decision threshold. We test the hypothesis that participants choose the decision threshold that maximizes reward rate, defined as an average number of rewards per unit of time. In particular, we test four predictions derived on the basis of this hypothesis in two behavioural experiments. The data from all participants of our experiments provide support only for some of the predictions, and on average the participants are slower and more accurate than predicted by reward rate maximization. However, when we limit our analysis to subgroups of 30–50% of participants who earned the highest overall rewards, all the predictions are satisfied by the data. This suggests that a substantial subset of participants do select decision thresholds that maximize reward rate. We also discuss possible reasons why the remaining participants select thresholds higher than optimal, including the possibility that participants optimize a combination of reward rate and accuracy or that they compensate for the influence of timing uncertainty, or both.
The time-course of lexical and structural processes in sentence comprehension
Authors: Tily Harry , Fedorenko Evelina , Gibson Edward
Published: September 2009

Online sentence comprehension involves multiple types of cognitive processes: lexical processes such as lexical access, which call on the user's knowledge of the meaning of words in the language, and structural processes such as the integration of incoming words into an emerging representation. In this article, we investigate the temporal dynamics of lexical access and syntactic integration. Unlike much previous work that has relied on temporary ambiguity to investigate this question, we manipulate the frequency of the verb in unambiguous structures involving a well-studied syntactic complexity manipulation (subject- vs. object-extracted clefts). The results demonstrate that for high-frequency verbs, the difficulty of reading a more structurally complex object-extracted cleft structure relative to a less structurally complex subject-extracted cleft structure is largely experienced in the cleft region, whereas for low-frequency verbs this difficulty is largely experienced in the postcleft region. We interpret these results as evidence that some stages of structural processing follow lexical processing. Furthermore, we find evidence that structural processing may be delayed if lexical processing is costly, and that the delay is proportional to the difficulty of the lexical process. Implications of these results for contemporary accounts of sentence comprehension are discussed.
Summary of reports presented to magnetic confinement theory and modelling (TH) section: main ideas and achievements
Authors: Dnestrovskij Yu.N.
Published: September 2009

This is a summary of the reports presented to the 22nd IAEA Fusion Energy Conference, Magnetic confinement theory and modelling section (Geneva, October 2008). Many of the papers are devoted to the investigation of transport processes, in particular to the toroidal momentum transport. Simulation by gyrokinetic codes has been improved in many countries, and the number of available codes reaches several tens. Numerical developments tend to follow the same trend as improvements in the computation power. The timescale for plasma simulations is now comparable to the ion–ion collision time. To improve the predictions for ITER, the near future advances are the combination of gyrokinetic and fluid codes. Reports on stellarators confirm that in these devices the neoclassical transport dominates, but the influence of turbulent transport can play a role in improved confinement regimes and in the resilience of pressure profiles. The resonant magnetic perturbations, mitigating the ELMs, could brake the plasma rotation, increasing the danger of disruption. The problems on the scrape-off layer and the divertor attract a large number of theoretical works that could lead to a better understanding of periphery plasma processes. ITER and reactor studies have been presented, and calculations confirm that ITER can achieve Q = 10 or larger. It has also been shown that the alpha-particle diffusion due to drift driven ITG turbulence will be relatively small in ITER, uncertainty remains in the magnitude of alpha-particle diffusion due to Alfvén waves.
Generalized exponents of small representations. I
Authors: Ion Bogdan
Published: September 2009

This is the first paper in a sequence devoted to giving manifestly non-negative formulas for generalized exponents of small representations in all types. The main part of this paper illustrates the overall structure of the argument on root systems of typeAAand discusses the relationship with the Lascoux-Schützenberger charge formula
Myosin Vc Is a Molecular Motor That Functions in Secretory Granule Trafficking
Authors: Jacobs Damon T. , Weigert Roberto , Grode Kyle D. , Donaldson Julie G. , Cheney Richard E.
Published: September 2009

Class V myosins are actin-based motor proteins that have critical functions in organelle trafficking. Of the three class V myosins expressed in mammals, relatively little is known about Myo5c except that it is abundant in exocrine tissues. Here we use MCF-7 cells to identify the organelles that Myo5c associates with, image the dynamics of Myo5c in living cells, and test the functions of Myo5c. Endogenous Myo5c localizes to two distinct compartments: small puncta and slender tubules. Myo5c often exhibits a highly polarized distribution toward the leading edge in migrating cells and is clearly distinct from the Myo5a or Myo5b compartments. Imaging with GFP-Myo5c reveals that Myo5c puncta move slowly (∼30 nm/s) and microtubule independently, whereas tubules move rapidly (∼440 nm/s) and microtubule dependently. Myo5c puncta colocalize with secretory granule markers such as chromogranin A and Rab27b, whereas Myo5c tubules are labeled by Rab8a. TIRF imaging indicates that the granules can be triggered to undergo secretion. To test if Myo5c functions in granule trafficking, we used the Myo5c tail as a dominant negative and found that it dramatically perturbs the distribution of granule markers. These results provide the first live-cell imaging of Myo5c and indicate that Myo5c functions in secretory granule trafficking.
Cdc42 Regulates FcγReceptor-mediated Phagocytosis through the Activation and Phosphorylation of Wiskott-Aldrich Syndrome Protein (WASP) and Neural-WASP
Authors: Park Haein , Cox Dianne
Published: September 2009

Cdc42 is a key regulator of the actin cytoskeleton and activator of Wiskott-Aldrich syndrome protein (WASP). Although several studies have separately demonstrated the requirement for both Cdc42 and WASP in Fcγreceptor (FcγR)-mediated phagocytosis, their precise roles in the signal cascade leading to engulfment are still unclear. Reduction of endogenous Cdc42 expression by using RNA-mediated interference (short hairpin RNA [shRNA]) severely impaired the phagocytic capacity of RAW/LR5 macrophages, due to defects in phagocytic cup formation, actin assembly, and pseudopod extension. Addition of wiskostatin, a WASP/neural-WASP (N-WASP) inhibitor showed extensive inhibition of phagocytosis, actin assembly, and cell extension identical to the phenotype seen upon reduction of Cdc42 expression. However, using WASP-deficient bone marrow-derived macrophages or shRNA of WASP or N-WASP indicated a requirement for both WASP and N-WASP in phagocytosis. Cdc42 was necessary for WASP/N-WASP activation, as determined using a conformation-sensitive antibody against WASP/N-WASP and partial restoration of phagocytosis in Cdc42 reduced cells by expression of a constitutively activated WASP. In addition, Cdc42 was required for proper WASP tyrosine phosphorylation, which was also necessary for phagocytosis. These results indicate that Cdc42 is essential for the activation of WASP and N-WASP, leading to actin assembly and phagocytic cup formation by macrophages during FcγR-mediated phagocytosis.
6. Assessment of food consumption and nutrient intake
Authors: Nelson Michael , Bingham Sheila A.
Published: September 2009

This chapter takes a comprehensive look at the techniques, strengths, and weaknesses of approaches to estimating food consumption and nutrient intake at the household and individual level. At the household level, it provides a detailed description of the methods available and the ways in which the data can be interpreted for epidemiological purposes, including techniques for estimating the distribution of food consumption and nutrient intake in individuals when data are collected at the household level. Similarly, it describes in detail the techniques for estimating food consumption and nutrient intake at the individual level, and focuses strongly on the repeatability and validity of measures, including an analysis of the sources of error such as portion size estimation, day-to-day variations in diet, estimates of the frequency of consumption, and the determination of current and past (relevant) diet. It addresses issues of under-reporting and energy adjustment, and concludes with an analysis of the effects of measurement error on validity.
7. Biochemical markers of nutrient intake
Authors: Bates Chris J. , Thurnham David I. , Bingham Sheila A. , Margetts Barrie M. , Nelson Michael
Published: September 2009

This chapter takes a look at the utility of biochemical measurements in different body tissues for estimating dietary exposures (as opposed to the determination of nutritional status). Validity (accuracy) and reproducibility (precision) are defined in relation to biomarkers in light of natural variations in physiological levels within and between individuals. Definitions are given of measures of nutrients in blood, urine, and other tissues, and compartments (e.g., hair, saliva, adipose tissue, finger nails, toe nails), and the feasibility of predicting intake from each measure. The chapter then describes relevant measures, nutrient by nutrient, for vitamins, minerals, lipids, protein, and energy, and the problems relating to dietary fibre.
8. The validation of dietary assessment
Authors: Nelson Michael
Published: September 2009

Validation considers the context within which measures are being made (national, household, individual) and helps to describe the extent to which observed values differ from the truth. This chapter outlines the general principles that should be applied in the design of validation studies of dietary measurements, and considers some of the statistical techniques that have been developed to overcome the problems which arise from the absence of a reference measure of ‘true’ dietary intakes. The concepts of validity and reproducibility are reviewed. The context of validation is considered (current or past intake; food consumption or nutrient intake; absolute or relative intakes; group versus individual intakes). Validation techniques, including the identification of relevant reference measures, validation procedures, and factors affecting the design of validation studies are considered. Statistical techniques for interpreting findings from validation studies are described in detail.
15. Case-control studies
Authors: Inskip Hazel , Coggon David
Published: September 2009

Case-control (or case-referent) studies compare patients with a disease or health outcome of interest (a case) with controls who do not have the disease or outcome. Their relevant past exposures are assessed retrospectively, and an estimate of relative risk (odds ratio) determined. This chapter describes the choice of study population, and the key features of selection of cases and determination of their relevant exposures. Selection of controls is a vexed subject, and the chapter considers in detail the associated issues, including matching, loss of controls from the study, and controls who go on to become cases. The chapter concludes with a discussion of study size and statistical power, and the appropriate statistical techniques for estimating and interpreting odds ratio, attributable risk percent, and population attributable risk percent. The problem of interpreting an association as evidence of causation is discussed.
Tests using multiple markers
Authors: Wald Nicholas , Hackshaw Allan
Published: September 2009

This chapter describes the methodology behind screening using multiple markers together in a single test. The method is based on estimating an individual's risk of having the disorder being screened for. This is the most efficient method for screening with multiple markers because it maximizes the detection rate for a given false-positive rate. Risk replaces component markers as the screening variable.
Down’s syndrome
Authors: Wald Nicholas
Published: September 2009

This chapter discusses screening and diagnosis for Down's syndrome. Down's syndrome is the most common cause of severe mental retardation. The disorder can be diagnosed antenatally by examining the chromosomes in fetal cells from amniotic fluid or the placenta. The birth prevalence of Down's syndrome is associated with maternal age and various biochemical and ultrasound markers. Screening methods based on maternal age and these markers can be used to identify women with a high enough risk of having an affected pregnancy to be offered a diagnostic amniocentesis or chorionic villus sampling.
X-linked disorders
Authors: Bundey Sarah
Published: September 2009

This chapter describes the screening for three X-linked disorders: Duchenne muscular dystrophy, the Fragile X syndrome, and X-linked retinitis pigmentosa. The primary screening test for these disorders is the family history, which is followed when positive by molecular studies, or by retinal function assessment if these is a history of X-linked retinitis pigmentosa. Only minorities of fetuses with the three diseases are detected by this approach.
Tay–Sachs disease
Authors: Kaplan Feige , Scriver Charles R.
Published: September 2009

This chapter describes screening for Tay–Sachs disease (TSD) in pregnancy. TSD is an example of a fatal metabolic genetic disease which is rare but for which it is realistic to screen because cases occur primarily within a well-defined subpopulation on which biochemical testing can be focused. The primary screening test for TSD is to ask an individual whether he or she is Jewish or has a Jewish parent. The second screening test involves the measurement of heat-labile Hex A activity, from which carrier status can be inferred.
Infections
Authors: Peckham Catherine S. , Newell Marie-Louise
Published: September 2009

Although the majority of infections in pregnancy have no effect on the developing fetus, some can lead to severe damage and disability. This chapter discsses screening for infections: rubella, syphilis, human immunodeficiency virus, hepatitis B, cytomegalovirus, toxoplasmosis, herpes simplex virus, chlamydia, and group B streptococcal infection.
Congenital dislocation of the hip
Authors: Leck Ian
Published: September 2009

This chapter describes screening for congenital dislocation of the hip. The aim of screening is to prevent persistent hip dislocation (PHD). In PHD, the head of the femur remains located either totally outside the acetabulum or only partially within in. This causes increasing disability once the child begins to walk. Neonatal screening and treatment of those who test positive is widely practised but has been poorly evaluated. Its value remains uncertain, although observational studies suggest that it reduces the incidence of PHD when competently performed.
Ethics of antenatal and neonatal screening
Authors: Wald Nicholas , Leck Ian , Gray J. A. Muir
Published: September 2009

This chapter reflects on the ethics of antenatal and neonatal screening, concluding that they are not fundamentally different from ethics in other areas of medicine. Topics covered include the benefits and hazards of screening and the rights of those offered screening to be appropriately informed and counselled about the services provided, to choose whether to use these services, and to receive on-going support regardless of their choice. The need for equity is also discussed, as are other implications that providing screening services has for the community.
Rose's Strategy of Preventive Medicine
Authors: Rose Geoffrey , Khaw Kay-Tee , Marmot Michael
Published: September 2009

The Strategy of Preventive Medicine, by Geoffrey Rose, first published in 1993 remains a key text for anyone involved in preventive medicine. Rose's insights into the inextricable relationship between ill health, or deviance, in individuals and populations they come from, have transformed our whole approach to strategies for improving health. His personal and unique book, based on many years of research, sets out the case that the essential determinants of the health of society are to be found in its mass characteristics. The deviant minority can only be understood when seen in its societal context, and effective prevention requires changes which involve the population as a whole. Rose's book explores the options for prevention, considering them from various viewpoints — theoretical and scientific, sociological and political, practical, and ethical. The applications of Rose's book's ideas are illustrated by a variety of examples ranging from heart disease to alcoholism to road accidents. The book's pioneering work focused on a population wide approach to the prevention of common medical and behavioural disorders has become the classic text on the subject. This reissue of that text brings the original book to a new generation. This book retains the original text intact, but it includes new perspectives on the work. It examines what relevance Rose's ideas might have in the era of the human genome project and other major scientific advances, it considers examples of how the theory might be applied and generalized in medicine and beyond, and discusses what implications it holds for the future. There is also an explanation of the population perspective, clarifying the often confused thinking and arguments about determinants of individual cases and determinants of population incidence.
The relation of risk to exposure
Authors: Rose Geoffrey
Published: September 2009

This chapter discusses the dose-effect relationship. It identifies two issues concerning the shape of the dose-effect relationship that are critical for preventive policy: How much of the burden of ill health is compressed within an identifiable group where high exposure carries a high personal risk? Is there an exposure threshold below which risk is negligible and can be ignored? Both these questions require us to look at the whole ranges of both exposure to causes and health outcomes.
Some implications of population change
Authors: Rose Geoffrey
Published: September 2009

Society seeks to distance itself from its deviants, either physically (as by segregating those with mental illness or AIDS), or by categorizing them (‘hypertensives’, ‘depressives’, ‘hooligans’), or by denying responsibility for their problems (such as obesity, poverty-related illness, alcoholism, or violence). Yet in truth the deviants are simply the tail of the population's own distribution; they belong to each other and society is one, whether it likes it or not. This chapter explains the interrelations between the population and its deviants, and the health implications for the deviants of changes in the population. It then considers the health implications of such changes for the population as a whole.
Psychiatric Epidemiology
Authors: Susser Ezra , Schwartz Sharon , Morabia Alfredo , Bromet Evelyn
Published: September 2009

Searching for the causes of mental disorders is as exciting as it is complex. The relationship between pathophysiology and its overt manifestations is exceedingly intricate, and often the causes of a disorder are elusive at best. This book provides a resource for anyone trying to track these causes. Uniting theory and practice and rather than attempting to review the descriptive epidemiology of mental disorders, this book gives a dynamic exposition of the thinking and techniques used to establish it. The book starts out by tracing the brief history of psychiatric epidemiology, then describes the study of risk factors as causes of mental disorders. Subsequent sections discuss approaches to investigation of biologic, genetic, or social causes and the statistical analysis of study results. The book concludes by following some of the problems involved in the search for genetic causes of mental disorders, and more complex casual relationships.
The Burden of Mental Illness
Authors: Susser Ezra , Schwartz Sharon , Morabia Alfredo , Bromet Evelyn J.
Published: September 2009

This chapter traces the roots of psychiatric epidemiology in medical sociology and the emergence of the community survey as its predominant research design, especially in the United States. It also follows the steps taken in psychiatric epidemiology to document the burden of disease due to mental disorders. Over a fifty-year period, psychiatric morbidity surveys have brought remarkable advances in knowledge. Ultimately, these studies helped to fulfill an overarching mission of psychiatric epidemiology: to bring about the recognition of mental disorders in public health.