bluuebunny/crossref_metadata_2025 huggingface dataset:
Speech Impairment in Down Syndrome: A Review
Authors: Kent Ray D. , Vorperian Houri K.
Published: December 2012

Purpose

This review summarizes research on disorders of speech production in Down syndrome (DS) for the purposes of informing clinical services and guiding future research.

Method

Review of the literature was based on searches using MEDLINE, Google Scholar, PsycINFO, and HighWire Press, as well as consideration of reference lists in retrieved documents (including online sources). Search terms emphasized functions related to voice, articulation, phonology, prosody, fluency, and intelligibility.

Conclusions

The following conclusions pertain to four major areas of review: voice, speech sounds, fluency and prosody, and intelligibility. The first major area is voice. Although a number of studies have reported on vocal abnormalities in DS, major questions remain about the nature and frequency of the phonatory disorder. Results of perceptual and acoustic studies have been mixed, making it difficult to draw firm conclusions or even to identify sensitive measures for future study. The second major area is speech sounds. Articulatory and phonological studies show that speech patterns in DS are a combination of delayed development and errors not seen in typical development. Delayed (i.e., developmental) and disordered (i.e., nondevelopmental) patterns are evident by the age of about 3 years, although DS-related abnormalities possibly appear earlier, even in infant babbling. The third major area is fluency and prosody. Stuttering and/or cluttering occur in DS at rates of 10%–45%, compared with about 1% in the general population. Research also points to significant disturbances in prosody. The fourth major area is intelligibility. Studies consistently show marked limitations in this area, but only recently has the research gone beyond simple rating scales.
Shared Etiology of Phonological Memory and Vocabulary Deficits in School-Age Children
Authors: Peterson Robin L. , Pennington Bruce F. , Samuelsson Stefan , Byrne Brian , Olson Richard K.
Published: December 2012

Purpose

The goal of this study was to investigate the etiologic basis for the association between deficits in phonological memory (PM) and vocabulary in school-age children.

Method

Children with deficits in PM or vocabulary were identified within the International Longitudinal Twin Study (ILTS; Samuelsson et al., 2005). The ILTS includes 1,045 twin pairs (between the ages of 5 and 8 years) from the United States, Australia, and Scandinavia. The authors applied the DeFries-Fulker (DeFries & Fulker, 1985, 1988) regression method to determine whether problems in PM and vocabulary tend to co-occur because of overlapping genes, overlapping environmental risk factors, or both.

Results

Among children with isolated PM deficits, the authors found significant bivariate heritability of PM and vocabulary weaknesses both within and across time. However, when probands were selected for a vocabulary deficit, there was no evidence for bivariate heritability. In this case, it appears that the PM–vocabulary relationship is caused by common shared environmental experiences.

Conclusions

The findings are consistent with previous research on the heritability of specific language impairment and suggest that there are etiologic subgroups of children with low vocabulary for different reasons, 1 being more influenced by genes and another being more influenced by environment.
CODATA Recommended Values of the Fundamental Physical Constants: 2010
Authors: Mohr Peter J. , Taylor Barry N. , Newell David B.
Published: December 2012

This paper gives the 2010 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA) for international use. The 2010 adjustment takes into account the data considered in the 2006 adjustment as well as the data that became available from 1 January 2007, after the closing date of that adjustment, until 31 December 2010, the closing date of the new adjustment. Further, it describes in detail the adjustment of the values of the constants, including the selection of the final set of input data based on the results of least-squares analyses. The 2010 set replaces the previously recommended 2006 CODATA set and may also be found on the World Wide Web at physics.nist.gov/constants.
IUPAC-NIST Solubility Data Series. 96. Amines with Water Part 2. C7–C24 Aliphatic Amines
Authors: Góral Marian , Shaw David G. , Mączyński Andrzej , Wiśniewska-Gocłowska Barbara , Oracz Paweł
Published: December 2012

The mutual solubilities and related liquid-liquid equilibria of 41 binary systems of C7–C24 aliphatic amines with water are exhaustively and critically reviewed. Reports of experimental determination of solubility that appeared in the primary literature prior to the end of 2010 are compiled. For seven systems, sufficient data are available to allow critical evaluation. All data are expressed as mass percent and mole fraction as well as the originally reported units.
Attenuated total reflection study of bulk and surface polaritons in antiferromagnets and hexagonal ferrites: Propagation at arbitrary angles
Authors: Anderson N. R. , Camley R. E.
Published: January 2013

We perform a theoretical study of the reflection of infra-red radiation from antiferromagnets and M-type barium hexagonal ferrite using an attenuated total reflection (ATR) geometry. At an arbitrary angle of propagation, the electromagnetic waves in the magnetic materials cannot be separated into the usual pure transverse electric (TE) and pure transverse magnetic (TM) modes. We develop a method to solve for the ATR reflection for arbitrary angles of propagation. Using reflection maps, one can determine the dispersion relations for both bulk and surface polaritons. We find that surface polariton features in the reflection map are present at all angles for both incident TE and TM polarizations, with the exception of TM polarization when the plane of incidence is perpendicular to the applied magnetic field. We also see that the interaction of the incident electromagnetic wave with surface polaritons can cause significant transfer from TE to TM modes (and vice versa) upon reflection. When the surface modes vanish, we see that the remaining bulk mode displays reciprocal behavior.
Two-dimensional electronic spectroscopy of CdSe nanoparticles at very low pulse power
Authors: Griffin Graham B. , Ithurria Sandrine , Dolzhnikov Dmitriy S. , Linkin Alexander , Talapin Dmitri V. , Engel Gregory S.
Published: January 2013

Nanoparticles have been proposed as a promising material for creating devices that harvest, transport, and manipulate energy and electrons. Ultrafast charge carrier dynamics represent a critical design aspect and are dependent on both size and shape of the nanoparticle. Spectroscopic investigation of the electronic structure and dynamics of these systems is complicated by sample inhomogeneity, which broadens peaks and leads to ambiguity in interpretation of both spectra and dynamics. Here, we use two-dimensional electronic spectroscopy to remove inhomogeneous broadening and to clarify interpretation of measured dynamics. We specifically investigate the effect of nanoparticle shape on the electronic structure and ultrafast electronic dynamics in the band-edge exciton states of CdSe quantum dots, nanorods, and nanoplatelets. Particle size was chosen to enable straightforward comparisons of the effects of particle shape on the spectra and dynamics without retuning the laser source. The spectra were measured with low pulse powers (generally <1 nJ/pulse), using short pulses (∼12 fs) to minimize interference from solvent contributions to the spectra, ambiguities in the dynamics due to pulse-overlap effects, and contributions to the dynamics from multi-exciton effects. The lowest two exciton states are clearly resolved in spectra of quantum dots but unresolved for nanorods and nanoplates, in agreement with previous spectroscopic and theoretical results. In all nanoparticles, ultrafast dynamics measurements show strong evidence of electronic relaxation into the lowest energy exciton state within ∼30 fs, a timescale not observable in previous dynamics measurements of similar systems. These dynamics are unambiguously assigned to hole relaxation, as the higher lying electronic excited states are not energetically accessible in these experiments. Clear evidence of coherent superpositions of the lowest two exciton states were not seen in any of the particles studied, in contrast to recent results from work on quantum dots.
Microrheology of supercooled liquids in terms of a continuous time random walk
Authors: Schroer Carsten F. E. , Heuer Andreas
Published: January 2013

Molecular dynamics simulations of a glass-forming model system are performed under application of a microrheological perturbation on a tagged particle. The trajectory of that particle is studied in its underlying potential energy landscape. Discretization of the configuration space is achieved via a metabasin analysis. The linear and nonlinear responses of drift and diffusive behavior can be interpreted and analyzed in terms of a continuous time random walk. In this way, the physical origin of linear and nonlinear response can be identified. Critical forces are determined and compared with predictions from literature.
First-principles study of atomic hydrogen adsorption and initial hydrogenation of Zr(0001) surface
Authors: Zhang Peng , Wang Shuangxi , Zhao Jian , He Chaohui , Zhao Yaolin , Zhang Ping
Published: January 2013

The atomic hydrogen adsorption on Zr(0001) surface is systematically investigated by using density functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics is studied in detail for a wide range from 0.11 to 2.0 monolayer. At low coverage of 0<Θ≤1.0, the most stable adsorption site is identified as the on-surface hcp site followed by the fcc site, and the adsorption energy gradually increases with the coverage, thus, indicating the higher stability of on-surface adsorption and the tendency to form H clusters. The origin of this stability is carefully analyzed by the projected density of states and the charge distribution showing the Zr-H chemical bonding with a mixed ionic/covalent feature during the surface hydrogenation. In addition, the minimum energy paths as well as the activation barriers of the on-surface diffusion and the penetration from on-surface sites to subsurface sites are also calculated. At high coverage of 1.0<Θ≤2.0, it is found that the co-adsorption configuration with 1.0 monolayer H residing on the surface hcp sites and the remaining (Θ-1) monolayer H occupying the sub-surface octahedral sites is most energetically favorable. The electronic structure properties of the resultant H-Zr-H sandwich structures at the coverage range of 1.0<Θ≤2.0 reveal the similar characteristics to the bulk hydride ZrH2, providing a detailed microscopic understanding for the Zr surface hydrogenation phenomenon.
The electronic properties of point defects in earth-abundant photovoltaic material Zn3P2: A hybrid functional method study
Authors: Yin Wan-Jian , Yan Yanfa
Published: January 2013

The electronic properties of intrinsic and extrinsic defects in Zn3P2 are studied by density-functional theory with hybrid functional method. Our results show that undoped Zn3P2 should be intrinsically p-type with Zn vacancies as the responsible shallow acceptors. Na or Cu doping is expected to result in improved p-type conductivity as compared to intrinsic Zn3P2. S or Al doping may lead to weak n-type Zn3P2. Doping of Mg does not produce good n-type Zn3P2, consistent with experimental observations. Contradicting to conventional wisdom, an interstitial P in Zn3P2 is not a triple-hole acceptor and a P vacancy in Zn3P2 is not a triple-electron donor. Instead, we find that the interstitial P is actually a single-hole acceptor, and the P vacancy is a single-electron donor. The origins of these unusual behaviors are discussed.
Low temperature oxidation mechanisms of nanocrystalline magnetite thin film
Authors: Bourgeois F. , Gergaud P. , Renevier H. , Leclere C. , Feuillet G.
Published: January 2013

A detailed investigation of the mechanisms related to the low temperature oxidation of nanocrystalline magnetite thin films into maghemite is presented. Despite strong differences in the functional properties of these two phases, structural similarities make it difficult to distinguish between them, and to quantify the oxidation process, particularly in the case of nanostructured polycrystalline layers. Contrary to the case of bulk materials or monocrystalline films and particles, the oxidation processes in nanocrystalline thin film have only scarcely been studied. In this work, structural and optical techniques, including X-ray diffraction (XRD), EXAFS/X-ray absorption near edge structure, FTIR, and Raman scattering, have been used to estimate the oxidation rate of magnetite. The overall oxidation reaction rates are discussed in the framework of two limiting cases corresponding to intra grain diffusion and to grain boundary diffusion. SIMS profiling and electrical measurements were also carried out to better assess the oxidation quantification in order to conclude on the predominant oxidation mechanisms in this heterogeneous material. We propose a qualitative model for the structure, in terms of insulating zone distribution, for partially oxidized films.
Schottky barrier at the AlN/metal junction
Authors: Slepko Alexander , Ramdani Jamal , Demkov Alexander A.
Published: January 2013

We report a first princples study of the Schottky barrier of zinc blende (zb) AlN to Pt, Au, Al, W, In, and Cs. We find good agreement with the Schottky model for Pt, Au, Al, W, and In contacts. However, in the case of Cs, a spatially extended interface dipole formation results in significant deviation from the Schottky rule. Moreover, for the “cesiated” AlN surface, the electron affinity shifts from positive 2.0 eV for clean AlN to negative 1.8 eV in qualitative agreement with recent experiments by Wu and Kahn [C. I. Wu and A. Kahn, Appl. Surf. Sci. 162, 250 (2000)].
High-temperature, high-pressure Raman spectra and their intrinsic anharmonic effects in the perovskite Pb1−xLaxTiO3
Authors: Joya Miryam R. , Barba-Ortega J. , Pizani P. S.
Published: January 2013

Raman spectra of ferroelectric Pb1−xLaxTiO3, in the tetragonal phase of the material and for different La concentrations, were studied for different temperatures and pressures. While temperature was varied from 8 K to transition temperature (Tc) at atmospheric pressure, applied hydrostatic pressure was increased from zero to transition pressure (Pc) at room temperature. Isobaric and isothermal mode-Grüneisen parameters were calculated from the measured Raman spectra, and previously reported coefficients of thermal expansion [Chen et al., J. Am. Ceram. Soc. 88, 1356 (2005)] and bulk moduli. Also the coefficient of intrinsic anharmonicity was calculated. Although the absolute value of Grüneisen parameters strongly depends on the Raman mode under study, all of them grow as La concentration increases.
Annealing effect on surface morphology and electrical transport of PbPdO2 and Pb(Pd,Co)O2
Authors: Choo S. M. , Lee K. J. , Park S. M. , Park G. S. , Jung M. H.
Published: January 2013

We have studied the ex-situ annealing effects on the surface morphology and electrical transport of gapless semiconductors, PbPdO2 and Pb(Pd,Co)O2 thin films, with varying annealing temperature and time. The annealing process gives rise to better surface morphology in both samples. The optimal annealing conditions are obtained to be 650  °C and 12 h. On the other hand, the electrical properties are differently found for both samples. The electrical conduction is improved for PbPdO2 film by annealing, while it is lowered for Pb(Pd,Co)O2 film. The improvement of electrical conduction for PbPdO2 is well explained by the reduction of lattice imperfections of PdO droplets and Pd or O deficiencies, which is related with the hybridization between the Pd 4d and O 2p bands. However, this tendency is not applied for Pb(Pd,Co)O2 because of the trivalent Co state, which generates the monovalent Pd state, leading to the decrease of electrical conduction as a result of the reduction of Pd(4d)-O(2p) hybridization.
Growth of highly crystalline nickel particles by diffusional capture of atoms
Authors: Sevonkaev Igor , Privman Vladimir , Goia Dan
Published: January 2013

We report a new approach to achieve growth of highly crystalline nickel nanoparticles over an extended range of sizes (up to 100 nm in diameter) and time scales (up to several hours) by diffusional transport of constituent atoms. The experimental procedure presented offers control of the morphology of the resulting particles and yields base metal nanocrystals suitable for epitaxial deposition of noble metal shells and the preparation of materials with improved catalytic properties. The reported precipitation system also provides a good model for testing a diffusion-driven growth mechanism developed specifically for the reduction process described.
Magnetoelectric coupling in a ferroelectric/ferromagnetic chain revealed by ferromagnetic resonance
Authors: Sukhov A. , Horley P. P. , Jia C.-L. , Berakdar J.
Published: January 2013

Understanding the multiferroic coupling is one of the key issues in the field of multiferroics. As shown here theoretically, the ferromagnetic resonance (FMR) renders possibly an access to the magnetoelectric coupling coefficient in composite multiferroics. This we evidence by a detailed analysis and numerical calculations of FMR in an unstrained chain of BaTiO3 in the tetragonal phase in contact with Fe, including the effect of depolarizing field. The spectra of the absorbed power in FMR are found to be sensitive to the orientation of the interface electric polarization and to an applied static electric field. Here, we propose a method for measuring the magnetoelectric coupling coefficient by means of FMR.
Competition of 3d/4f orbitals due to competing conductivity and ferromagnetism in Fe/CoAs layers in Eu(Fe0.89Co0.11)2As2
Authors: Rumble Christopher , Itou M. , Jiang Shuai , Xu Zhu'an , Cao Guanghan , Sakurai Y. , Penner-Hahn James , Deb Aniruddha
Published: January 2013

The spin-polarized electron momentum density along the [100] direction of Eu(Fe0.89Co0.11)2As2 was measured using Magnetic Compton Scattering (MCS). Measurements were performed at different temperatures and applied external magnetic fields. These results provide the first direct insight into the orbital interactions that are responsible for the competing conductivity and ferromagnetism (FM) in this iron pnictide system. The orbital-wise decompositions of the density distribution show that at low applied magnetic field (0.1 T), the spin-polarized average Fe/Co-3d character is enhanced between 15 K and 19 K with a maximum at 17 K, the temperature at which the resistivity shows a local maximum, followed by re-entrant SC (superconducting)-like character. This clearly shows the dominance of the ferromagnetic character over conducting character in this temperature region where the resistivity shows a maximum. At higher applied magnetic field, we do not see this enhancement and subsequent collapse of the Fe/Co-3d character as the temperature decreases, consistent with the disappearance of the re-entrant SC-like feature at higher applied magnetic field. These data support a model in which the spin-polarization of the Fe/Co-3d orbitals is enhanced by the ferromagnetic Eu-ions, leading to the suppression of conductivity at ∼17 K (for 0.1 T), while at lower temperature the conductivity recovers and the Fe/Co-3d spin-polarization collapses.
Highly conductive die attach adhesive from percolation control and its applications in light-emitting device thermal management
Authors: Zhang Xinfeng , Zhang Kai , Zhang Min , Yang Chen , Sun Hongye , Gao Zhaoli , Yuen Matthew M. F. , Yang Shihe
Published: January 2013

Herein, we reported on the study of percolation dynamics in thermoset-based die attach (DA) materials and its effect on percolation conductivity. Two types of percolation mechanism in thermoset based DA were discovered, i.e., the curing reaction-induced percolation and the physical aging-induced percolation. The former features in a fast percolation network growth rate, which is one order of magnitude higher than the latter. It is demonstrated that the percolation kinetics largely affects the apparent percolation conductivity under the traditional packaging conditions; and reaction-induced percolation allows ultrahigh efficiency in reaching the volume fraction-limiting percolation conductance, resulting in enhanced thermal performance of DA.
New insights in the passivation of high-k/InP through interface characterization and metal–oxide–semiconductor field effect transistor demonstration: Impact of crystal orientation
Authors: Xu Min , Gu Jiangjiang J. , Wang Chen , Zhernokletov D. M. , Wallace R. M. , Ye Peide D.
Published: January 2013

We have systematically studied the passivation of InP (100) and (111)A substrate using atomic-layer-deposited Al2O3 as gate dielectric. Modified high- and low-frequency method and full conductance method has been applied to evaluate the interface trap density (Dit) distribution at Al2O3/InP interface through MOS capacitor (MOSCAP) and MOSFET measurements. Lower Dit towards conduction band is obtained from (111)A surface, accompanied by an increase in midgap Dit. This leads to the demonstration of record-high drive current (Ids=600 μA/μm) for a InP (111)A NMOSFET with gate length (LG) of 1 μm and relatively large subthreshold swing of 230 mV/dec at off-state. Detailed DC IV and current drift measurements confirm the trap distribution from capacitance-voltage characterization. A trap neutral level (E0) model is proposed to explain all observations from MOSCAP and MOSFET characterizations. A universal behavior of the E0 shift on III-V (111)A surface is also analyzed and this observation can play a pivotal role in interface engineering for future III-V CMOS technology with 3D structures.
Theoretical and simulation research on self-stabilizing secondary electron emission process across solid dielectrics in vacuum
Authors: Zhan Jiang-Yang , Mu Hai-Bao , Huang Xue-Zeng , Zhang Guan-Jun
Published: January 2013

Recently, the cathode-like luminescence phenomena are observed from the surface of solid dielectrics under steady-state high voltage excitation in vacuum, which is closely related to the self-stabilizing secondary electron emission (SSEE) occurring on insulator surface. In this paper, the theoretical analysis about surface charging based on the SSEE is made, and a one-dimensional Mont Carlo simulation on surface charge accumulation under DC voltage excitation is provided. The results reveal that surface charging process can be divided into three stages including initial accumulation, fast multiplication, and final stable stage. In the final stage, the SSEE phenomena are achieved and surface charges are invariable and reach up to a stable distribution. The simulated stable surface charge distribution is consistent with the theoretical deduction results, which confirms the existence of SSEE process.
Infrared light management in high-efficiency silicon heterojunction and rear-passivated solar cells
Authors: Holman Zachary C. , Filipič Miha , Descoeudres Antoine , De Wolf Stefaan , Smole Franc , Topič Marko , Ballif Christophe
Published: January 2013

Silicon heterojunction solar cells have record-high open-circuit voltages but suffer from reduced short-circuit currents due in large part to parasitic absorption in the amorphous silicon, transparent conductive oxide (TCO), and metal layers. We previously identified and quantified visible and ultraviolet parasitic absorption in heterojunctions; here, we extend the analysis to infrared light in heterojunction solar cells with efficiencies exceeding 20%. An extensive experimental investigation of the TCO layers indicates that the rear layer serves as a crucial electrical contact between amorphous silicon and the metal reflector. If very transparent and at least 150 nm thick, the rear TCO layer also maximizes infrared response. An optical model that combines a ray-tracing algorithm and a thin-film simulator reveals why: parallel-polarized light arriving at the rear surface at oblique incidence excites surface plasmons in the metal reflector, and this parasitic absorption in the metal can exceed the absorption in the TCO layer itself. Thick TCO layers—or dielectric layers, in rear-passivated diffused-junction silicon solar cells—reduce the penetration of the evanescent waves to the metal, thereby increasing internal reflectance at the rear surface. With an optimized rear TCO layer, the front TCO dominates the infrared losses in heterojunction solar cells. As its thickness and carrier density are constrained by anti-reflection and lateral conduction requirements, the front TCO can be improved only by increasing its electron mobility. Cell results attest to the power of TCO optimization: With a high-mobility front TCO and a 150-nm-thick, highly transparent rear ITO layer, we recently reported a 4-cm2 silicon heterojunction solar cell with an active-area short-circuit current density of nearly 39 mA/cm2 and a certified efficiency of over 22%.
Field emission properties of single crystal chromium disilicide nanowires
Authors: Valentín L. A. , Carpena-Nuñez J. , Yang D. , Fonseca L. F.
Published: January 2013

The composition, crystal structure, and field emission properties of high-crystallinity chromium disilicide (CrSi2) nanowires synthesized by a vapor deposition method have been studied. High resolution transmission electron microscopy, energy dispersive spectroscopy, and selected area electron diffraction studies confirm the single-crystalline structure and composition of the CrSi2 nanowires. Field emission measurements show that an emission current density of 0.1 μA/cm2 was obtained at a turn-on electric field intensity of 2.80 V/μm. The maximum emission current measured was 1.86 mA/cm2 at 3.6 V/μm. The relation between the emission current density and the electric field obtained follows the Fowler–Nordheim equation, with an enhancement coefficient of 1140. The electrical conductivity of single nanowires was measured by using four-point-probe specialized microdevices at different temperatures, and the calculated values are close to those reported in previous studies for highly conductive single crystal bulk CrSi2. The thermal tolerance of the nanowires was studied up to a temperature of 1100 °C. The stability of the field emission current, the I-E values, their thermal tolerance, and high electrical conductivity make CrSi2 nanowires a promising material for field emission applications.
Sub-millisecond nematic liquid crystal switches using patterned command layer
Authors: Cattaneo L. , Kouwer P. H. J. , Rowan A. E. , Rasing Th.
Published: January 2013

Switching speeds of nematic liquid crystal (LC) cells in the sub-millisecond range are observed for 3-D patterned self assembled monolayers (SAMs) on indium-tin-oxide (ITO) substrates. To achieve such fast LC response and relaxation times, thermal treatments of the patterned SAM-on-ITO are required, increasing the relative anchoring energy experienced by the interacting LC molecules.
Terahertz time-domain measurement of non-Drude conductivity in silver nanowire thin films for transparent electrode applications
Authors: Kim Jaeseok , Maeng Inhee , Jung Jongwook , Song Hyunjoon , Son Joo-Hiuk , Kim Kilsuk , Lee Jaeik , Kim Chul-Hong , Chae Geesung , Jun Myungchul , Hwang YongKee , Jeong Lee Su , Myoung Jae-Min , Choi Hyunyong
Published: January 2013

We have investigated the complex conductivity of silver nanowire thin films using terahertz time-domain spectroscopy. Maxwell-Garnett effective medium theory, which accounts for the effective complex conductivity of silver nanowires, is presented in detail theoretically and experimentally. The conductivity of nanowires exhibits a characteristic non-Drude response in which the applied terahertz field is polarized in the longitudinal nanowire direction. The non-Drude responses of the silver nanowires are explained by the Gans approximation and the Drude-Smith model, and both agree well with the experimental data. Our results provide a basis for further explorations of charge carrier dynamics in nanowire-based transparent electrode applications.
A View Through Novel Process Windows
Authors: Stouten Stefan C. , Noël Timothy , Wang Qi , Hessel Volker
Published: January 2013

This mini-review discusses some of the recent work on novel process windows by the Micro Flow Chemistry and Process Technology group at the Eindhoven University of Technology, and their associates. Novel process windows consist of unconventional approaches to boost chemical production, often requiring harsh reaction conditions at short to very short time-scales. These approaches are divided into six routes: the use of high temperatures, high pressures, and high concentrations (or solvent-free), new chemical transformations, explosive conditions, and process simplification and integration. Microstructured reactors, due to their inherent safety, short time-scales, and the high degree of process control, are the means that make such extreme chemistry possible.
Reversal of end-stage retinal degeneration and restoration of visual function by photoreceptor transplantation
Authors: Singh Mandeep S. , Charbel Issa Peter , Butler Rachel , Martin Chris , Lipinski Daniel M. , Sekaran Sumathi , Barnard Alun R. , MacLaren Robert E.
Published: January 2013

One strategy to restore vision in retinitis pigmentosa and age-related macular degeneration is cell replacement. Typically, patients lose vision when the outer retinal photoreceptor layer is lost, and so the therapeutic goal would be to restore vision at this stage of disease. It is not currently known if a degenerate retina lacking the outer nuclear layer of photoreceptor cells would allow the survival, maturation, and reconnection of replacement photoreceptors, as prior studies used hosts with a preexisting outer nuclear layer at the time of treatment. Here, using a murine model of severe human retinitis pigmentosa at a stage when no host rod cells remain, we show that transplanted rod precursors can reform an anatomically distinct and appropriately polarized outer nuclear layer. A trilaminar organization was returned to
rd1
hosts that had only two retinal layers before treatment. The newly introduced precursors were able to resume their developmental program in the degenerate host niche to become mature rods with light-sensitive outer segments, reconnecting with host neurons downstream. Visual function, assayed in the same animals before and after transplantation, was restored in animals with zero rod function at baseline. These observations suggest that a cell therapy approach may reconstitute a light-sensitive cell layer de novo and hence repair a structurally damaged visual circuit. Rather than placing discrete photoreceptors among preexisting host outer retinal cells, total photoreceptor layer reconstruction may provide a clinically relevant model to investigate cell-based strategies for retinal repair.
Intrinsic acyl-CoA thioesterase activity of a peroxisomal ATP binding cassette transporter is required for transport and metabolism of fatty acids
Authors: De Marcos Lousa Carine , van Roermund Carlo W. T. , Postis Vincent L. G. , Dietrich Daniela , Kerr Ian D. , Wanders Ronald J. A. , Baldwin Stephen A. , Baker Alison , Theodoulou Frederica L.
Published: January 2013

Peroxisomes are organelles that perform diverse metabolic functions in different organisms, but a common function is β-oxidation of a variety of long chain aliphatic, branched, and aromatic carboxylic acids. Import of substrates into peroxisomes for β-oxidation is mediated by ATP binding cassette (ABC) transporter proteins of subfamily D, which includes the human adrenoleukodystropy protein (ALDP) defective in X-linked adrenoleukodystrophy (X-ALD). Whether substrates are transported as CoA esters or free acids has been a matter of debate. Using COMATOSE (CTS), a plant representative of the ABCD family, we demonstrate that there is a functional and physical interaction between the ABC transporter and the peroxisomal long chain acyl-CoA synthetases (LACS)6 and -7. We expressed recombinant CTS in insect cells and showed that membranes from infected cells possess fatty acyl-CoA thioesterase activity, which is stimulated by ATP. A mutant, in which Serine 810 is replaced by asparagine (S810N) is defective in fatty acid degradation in vivo, retains ATPase activity but has strongly reduced thioesterase activity, providing strong evidence for the biological relevance of this activity. Thus, CTS, and most likely the other ABCD family members, represent rare examples of polytopic membrane proteins with an intrinsic additional enzymatic function that may regulate the entry of substrates into the β-oxidation pathway. The cleavage of CoA raises questions about the side of the membrane where this occurs and this is discussed in the context of the peroxisomal coenzyme A (CoA) budget.
S
-nitrosoglutathione reductase (GSNOR) enhances vasculogenesis by mesenchymal stem cells
Authors: Gomes Samirah A. , Rangel Erika B. , Premer Courtney , Dulce Raul A. , Cao Yenong , Florea Victoria , Balkan Wayne , Rodrigues Claudia O. , Schally Andrew V. , Hare Joshua M.
Published: January 2013

Although nitric oxide (NO) signaling promotes differentiation and maturation of endothelial progenitor cells, its role in the differentiation of mesenchymal stem cells (MSCs) into endothelial cells remains controversial. We tested the role of NO signaling in MSCs derived from WT mice and mice homozygous for a deletion of
S
-nitrosoglutathione reductase (GSNOR
−/−
), a denitrosylase that regulates
S
-nitrosylation. GSNOR
−/−
MSCs exhibited markedly diminished capacity for vasculogenesis in an in vitro Matrigel tube–forming assay and in vivo relative to WT MSCs. This decrease was associated with down-regulation of the PDGF receptorα (PDGFRα) in GSNOR
−/−
MSCs, a receptor essential for VEGF-A action in MSCs. Pharmacologic inhibition of NO synthase with L-N
G
-nitroarginine methyl ester (
L
-NAME) and stimulation of growth hormone–releasing hormone receptor (GHRHR) with GHRH agonists augmented VEGF-A production and normalized tube formation in GSNOR
−/−
MSCs, whereas NO donors or PDGFR antagonist reduced tube formation ∼50% by murine and human MSCs. The antagonist also blocked the rescue of tube formation in GSNOR
−/−
MSCs by
L
-NAME or the GHRH agonists JI-38, MR-409, and MR-356. Therefore, GSNOR
−/−
MSCs have a deficient capacity for endothelial differentiation due to downregulation of PDGFRα related to NO/GSNOR imbalance. These findings unravel important aspects of modulation of MSCs by VEGF-A activation of the PDGFR and illustrate a paradoxical inhibitory role of
S
-nitrosylation signaling in MSC vasculogenesis. Accordingly, disease states characterized by NO deficiency may trigger MSC-mediated vasculogenesis. These findings have important implications for therapeutic application of GHRH agonists to ischemic disorders.
Paced QRS duration as a predictor for clinical heart failure events during right ventricular apical pacing in patients with idiopathic complete atrioventricular block: results from an observational cohort study (PREDICT‐HF)
Authors: Chen Shaojie , Yin Yuehui , Lan Xianbin , Liu Zengzhang , Ling Zhiyu , Su Li , Kiuchi Márcio Galindo , Li Xiaoli , Zhong Bin , Krucoff Mitchell W. ,   The PREDICT‐Heart Failure study international group
Published: December 2012

Aims

The aim of this study was to investigate the predictive ability of paced QRS duration (pQRSd) for heart failure events among patients receiving right ventricular apical pacing (RVAP).

Methods and results

A total of 194 patients with complete atrioventricular block receiving pacemaker treatment were enrolled and stratified to group 1, pQRSd < 160 ms, n = 53; group 2, 160 ≤ pQRSd < 190 ms, n = 97; and group 3, pQRSd ≥ 190 ms, n = 44. Study outcomes were heart failure events, changes in pQRSd, and changes in left ventricular ejection fraction (LVEF). During the 3‐year follow‐up, the incidence of heart failure events was 9.4, 27.8, and 56.8% in groups 1, 2, and 3, respectively (P < 0.001). Among the patients without heart failure events, the pQRSd at 3 years remained longer than that at baseline (162.1 ± 22.6 vs. 160.9 ± 22.1 ms, P < 0.05), whereas among patients who experienced heart failure events, the prolonged pQRSd at 3 years seemed more pronounced as compared with baseline (184.1 ± 21.1 vs. 179.8 ± 21 ms, P < 0.001). Linear regression demonstrated that a decrease in LVEF was positively correlated with pQRSd over time (relative risk 0.423; P < 0.05). The receiver operating charactersitic curve showed that the cut‐off value of pQRSd was 165 ms with a sensitivity of 0.789.

Conclusion

A prolonged pQRSd has a detrimental effect on long‐term cardiac function during RVAP in patients with complete atrioventricular block. pQRSd could be a useful predictor to identify patients who are at risk for heart failure events during RVAP.
Primary (tropical) pyomyositis
Authors: Warrell D A
Published: January 2013

Abstracts and keywords to be supplied.
Infections in pregnancy
Authors: Impey Lawrence
Published: January 2013

Maternal illness is often more severe in pregnancy, e.g. varicella, malaria, and the treatment of infections in pregnancy is complicated by potential effects of drugs on the fetus. Peri- and postpartum maternal infection is a major cause of maternal mortality.

The effects of infection in pregnancy can be broadly categorized as follows (these are not mutually exclusive): (1) transplacental infection causing fetal malformation, e.g. treponema pallidum, rubella; (2) transplacental infection causing severe in utero illness, e.g. parvovirus; (3) neonatal infection / carrier status as a result of transplacental or intrapartum infection, e.g. HIV, herpes zoster; such neonatal infection may be severe; (4) preterm delivery, late miscarriage, perinatal death and cerebral palsy at term delivery are more common in the presence of in utero and placental infection (chorioamnionitis), e.g. Group B streptococcus....
Tumours of the pancreas
Authors: Britton Edward , Lombard Martin
Published: January 2013

Pancreatic cancer, most commonly in the form of a solid ductal adenocarcinoma, accounts for 3% of all cancers but ranks in the top five leading causes of cancer deaths in most developed countries, reflecting the fact that it has a very poor prognosis (median survival 6 to 9 months). It is a disease of old age (85% of patients >65 years), and commoner in smokers....
Visual pathways
Authors: Kennard Christopher , Ajina Sara
Published: January 2013

Visual disturbances may be caused by diseases of the optic disc, optic nerve, optic chiasm, optic tract, lateral geniculate nucleus, optic radiations, and occipital lobe of the brain, as well as other brain areas involved in complex visual processing.

Diagnosis of disturbances of the visual pathways requires both knowledge of their anatomy and physiology, and the ability to carry out a thorough neuro-ophthalmological examination which should enable (1) documentation of the character and extent of the visual disturbance, and (2) topographic localization of the lesion, so that the relevant investigative techniques, such as radiological imaging, can be appropriately requested....
Diseases of the peripheral nerves
Authors: Hadden R.D.M. , Thomas P.K. , Hughes R.A.C.
Published: January 2013

Case History—A 34 yr old man presenting with jaundice, lymphadenopathy, sensory symptoms and muscular weakness.

Disorders of peripheral nerve function can be categorized in terms of the site of the primary disturbance. (1) Neuronopathies—conditions that lead to death of the neuron cell body and axon. (2) Axonal neuropathies—conditions that affect axons which may be focal, as in local injury, multifocal, as in vasculitis, or diffuse as in metabolic or toxic disorders often cause selective degeneration of the axons towards the cell bodies (‘dying-back’); (3) Demyelinating neuropathies—conditions in which the myelin sheaths are supporting Schwann cells damaged and the axons are relatively preserved. Combinations of axonal and demyelinating pathology are common. (4) Interstitial neuropathies—conditions in which there is infiltration of the endoneurium for instance by granuloma or amyloid....
Electrophysiology of the central and peripheral nervous systems
Authors: Krarup Christian
Published: January 2013

Electrophysiological studies of the central nervous system and peripheral nervous system—the core investigations in clinical neurophysiology—include electroencephalography, evoked potentials, electromyography, and nerve conduction studies. These provide information from anatomical regions which may not be accessible to direct pathological examination, and are good for tracking changes over time. However, they do not provide direct information about pathological changes in the nervous system, hence it is often necessary to supplement electrophysiological findings by imaging or other laboratory studies, and it is mandatory to view all results in their clinical context....
Headache
Authors: Kernick David , Goadsby Peter
Published: January 2013

This resource is a pragmatic, succinct and authoritative text aimed at GPs, general neurologists and other primary care healthcare professionals dealing with patients with headache, advocating a multi-disciplinary team approach to care.
The migraine attack
Authors: Kernick David , Goadsby Peter J.
Published: January 2013

This chapter covers the epidemiology of migraine, making the diagnosis of migraine, co-morbidity and associations, the migraine attack, migraine variants and complications, and when to investigate.
Headache attributed to head or neck trauma
Authors: Kernick David , Goadsby Peter J.
Published: January 2013

This chapter covers headache attributed to head or neck trauma, and covers establishing a relationship of headache with the trauma, classification of post-traumatic headache, prognosis, investigation of post-traumatic headache, and the treatment of post-traumatic headache.
Headache due to disorders of CSF pressure
Authors: Kernick David , Goadsby Peter J.
Published: January 2013

This chapter covers headache due to disorders of CSF pressure, focusing first on idiopathic intracranial hypertension and then intracranial hypotension.
Acute post-infectious glomerulonephritis
Authors: Moroni Gabriella , Ponticelli Claudio
Published: January 2013

Acute post-infectious glomerulonephritis (APIGN) is a primary glomerular disease characterized by intra-glomerular inflammation and cellular proliferation resulting from immunological events triggered by a variety of bacterial, viral, and protozoal infections. We use the term ‘primary’ to describe this disease since the kidney is the only organ directly involved in the disease, and extra-renal manifestations are generally the consequence of disturbed kidney function. The prototype of APIGN is post-streptococcal glomerulonephritis (PSGN) which most often occurs in children following a pharyngeal infection caused by a particular strain of streptococci and has a favorable outcome.

However in the last few decades the spectrum of APIGN has changed. The incidence of PSGN, particularly in its epidemic form, has progressively declined in industrialized countries. In many cases APIGN is caused today by other Gram-positive bacteria such as staphylococci or by Gram-negative bacteria. Moreover the disease tends to affect more and at a higher frequently adults with an immunocompromised background, due to alcoholism, diabetes, drug addiction, and/or viral hepatitis. Finally, while spontaneous recovery within few weeks is still the rule in children affected by the typical PSGN, the prognosis in immunodeficient adults is often severe and the response to treatment is uncommon. Therefore we will treat separately these two sub-types of acute glomerulonephritis.
Focal and segmental glomerular sclerosis
Authors: Scolari Francesco , Ponticelli Claudio
Published: January 2013

Focal and segmental glomerular sclerosis (FSGS) is a glomerular lesion which is associated with distinctive clinical features. Because it may be pathogenetically heterogeneous, it is not yet appropriate to call it a disease, yet its discovery in a renal biopsy in a patient with the nephrotic syndrome does have important connotations with respect to response to treatment and to long-term outcome. By light microscopy the characteristic finding is segmental areas of sclerosis (and hyalinosis) involving only some glomeruli. Patients with the FSGS lesion typically have proteinuria which is usually in the nephrotic range (〉3.5g/d in an adult), accompanied by the typical constellation of signs and symptoms of the nephrotic syndrome and arterial hypertension. A minority of patients may have only asymptomatic proteinuria and these patients usually do not progress to end-stage renal disease (ESRD) but the natural course of FSGS is ominous in most patients with nephrotic syndrome. However, numerous observational studies have shown that about 50–70% of patients may respond completely or partially to prolonged glucocorticoid therapy or other ‘immunosuppressive’ treatments and thus have a fair outcome in the long term.
Crescentic glomerulonephritis
Authors: Nachman Patrick , Glassock Richard J.
Published: January 2013

The term crescentic glomerulonephritis (CrGN) refers to a diverse collection of disorders of widely different etiology and pathogenesis having in common the development of extensive proliferation of cells within Bowman's space (Couser, 1988; Glassock et al., 1995; Nachman et al., 1998; Pusey and Rees, 1998; Morgan et al., 2006; Lionaki, et al., 2007). The resulting accumulation of cells gives rise to a ‘crescent’ enveloping the glomerular tuft itself. Polymerization of fibrinogen in Bowman's space due to passage of fibrinogen through gaps in the capillary wall, the elaboration of procoagulant factors by infiltrating monocytes and impaired fibrinolysis all contribute to the pathogenesis of the crescent (Couser, 1988, Glassock et al., 1995). Usually 〉50% of glomeruli are involved with crescentic lesions. Such patients also frequently manifest rapid and progressive deterioration of renal function leading to the clinical syndrome of rapidly progressive glomerulonephritis. Early and aggressive treatment can often delay or prevent the development of end-stage renal disease (ESRD). See Table 10.1 for an etiologic and pathogenetic classification of CrGN.
Other primary glomerular diseases
Authors: Ponticelli Claudio , Glassock Richard
Published: January 2013

Fibrillary glomerulonephritis (FGN) and immunotactoid glomerulopathy (ITG) are both glomerular diseases characterized histologically by a diffuse increase in mesangial matrix due to deposits having a fibrillary structure by electron microscopy, which are negative for Congo-red stains but positive for immunoglobulin deposition. Most patients present with proteinuria, often in a nephrotic range, microhematuria, and hypertension. Almost half of patients have a reduced renal function at presentation. Although FGN and ITG have quite similar light microscopical and clinical features the current opinion is that they represent two separate diseases. FGN is an idiopathic (primary) condition characterized by polyclonal immune deposits with restricted gamma isotypes. Most patients present with significant renal insufficiency and have a poor outcome despite immunosuppressive therapy. By contrast, ITG very often contains monoclonal IgG deposits and has a significant association with underlying monoclonal paraproteinemia and hypocomplementemia. ITG is more properly classified as a mono-clonal immunoglobulin deposition disease (MIDD). Differentiation of FGN from the much more rare entity ITG appears justified on immunopathologic, ultrastructural, and clinical grounds (Fogo et al., 1993; Bridoux et al., 2002; Rosenstock et al., 2003). Both will be discussed together, although only FGN should be regarded as a primary glomerular disease, as defined in this monograph.
L
Authors: Dickman Andrew
Published: January 2013

This chapter includes drugs beginning with the letter L