bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanoresolution profiling of metal-metal interfaces from x-ray Fraunhofer diffraction data
Authors: Darahanau A. V. , Nikulin A. Y. , Dilanian R. A. , Muddle B. C. , Souvorov A. , Nishino Y. , Ishikawa T.
Published: July 2006

High-angular-resolution Fraunhofer diffraction data were collected from several samples with interfaces between dissimilar metals using synchrotron x-radiation. The refractive index profile in the vicinity of the interface of each sample was reconstructed with spatial resolution of about 80nm by the phase retrieval x-ray diffractometry technique, using only limited a priori knowledge of the sample. These studies have demonstrated the viability of the technique as a nondestructive method of characterization of internal interfaces within multiphase materials.
Coercivity enhancement in the SrRuO3∕SrMnO3 superlattices
Authors: Padhan P. , Prellier W.
Published: July 2006

Magnetic superlattices consisting of ferromagnetic SrRuO3 and antiferromagnetic SrMnO3 have been grown on (001)-oriented SrTiO3 substrates using the pulsed laser deposition technique. Zero-field-cooled and field-cooled out-of-plane hysteresis loops with different range of magnetic fields have been measured for the series of superlattices. The coercive field of the ferromagnetic layer in SrRuO3–SrMnO3 superlattices is 12 times larger than that of the thin film of SrRuO3. This enhancement in the coercive field can be explained using the concept of the interplay of the pinning energy and the microscopic biased field.
Modeling heterostructures of nanophononic crystals by continuum model with microstructures
Authors: Huang G. L. , Sun C. T.
Published: July 2006

The application of nanophononic heterogeneous materials requires efficient and accurate modeling and analysis tools. For nanostructured materials, the use of atomistic simulation may be a potential solution. However, it is well known that this approach is beset with prohibitive computing time and an astronomical amount of data generated. In this letter, a microstructure continuum theory is employed to describe wave propagation in these materials. The key step in this approach is the establishment of a relationship between the local kinematics and the global continuum variables so that the characteristics of the nanostructure are captured. Propagation of longitudinal harmonic waves in nanophononic media is considered and the resulting dispersion curves are used to evaluate the accuracy of the microstructure continuum model.
Low power scaling using parallel coupling for toggle magnetic random access memory
Authors: Abraham David W. , Worledge D. C.
Published: July 2006

Toggle-switched magnetic random access memory devices offer wide write margins and robustness against thermally activated switching but are as yet unproven regarding the feasibility of scaling down from present sizes with acceptable write currents. We present a strategy for reducing switching fields by using parallel coupling between the two magnetic free layers, in contrast to the usual antiferromagnetic coupling previously discussed. Combined with the proper free layer magnetic material and offset fields from a carefully imbalanced pinned layer, we present experimental verification of toggling of 130nm diameter magnetic tunnel junctions at fields of less than 50Oe.
Large room temperature magnetization in nanocrystalline zinc ferrite thin films
Authors: Bohra Murtaza , Prasad Shiva , Kumar Naresh , Misra D. S. , Sahoo S. C. , Venkataramani N. , Krishnan R.
Published: July 2006

Zinc ferrite films were deposited on fused quartz substrate at different temperatures using pulsed laser ablation (PLA) and rf sputtering. X-ray diffraction indicated that all the films were single phase ZnFe2O4 with grain growing in the range of 8–80nm with substrate temperature. The nanocrystalline films were found to be magnetic and the spontaneous magnetization showed a strong dependence on the grain size, dropping sharply for films with larger grains. A PLA thin film deposited in vacuum at 500°C exhibited a room temperature magnetization value of 5560G.
Ferroelectric behavior in nominally relaxor lead lanthanum zirconate titanate thin films prepared by chemical solution deposition on copper foil
Authors: Kim Taeyun , Hanson Jacqueline N. , Gruverman Alexei , Kingon Angus I. , Streiffer S. K.
Published: July 2006

We demonstrate that (Pb0.9La0.1)(Zr0.65Ti0.35)0.975O3 (PLZT) (10∕65∕35) thin films that have a nominally relaxor composition and that are deposited by chemical solution deposition onto copper foil show polarization hysteresis. Ferroelectric domain switching and a shift in Curie temperature are also observed. This is in contrast to the non-hysteretic behavior of films with identical composition prepared on Pt∕SiO2∕Si substrates. This suggests that the mismatch in coefficient of thermal expansion between PLZT and copper induces a compressive strain in the PLZT during cooling after high temperature crystallization under low pO2, and causes an out-of-plane polarization.
Selecting the growth sites of carbon nanotubes on silicon substrates by ion implantation
Authors: Yue Yang , Zhang Zhengjun , Liu Chao
Published: July 2006

Surface modification by xenon ion implantation could significantly influence the growth of carbon nanotubes on silicon substrates. By chemical vapor deposition using a mixture of ferrocene and xylene as the precursor, carbon nanotubes preferably grew on silicon substrates at areas implanted by xenon ions, leaving the unimplanted areas blank. This is due to the nanometer-scale (4–5nm) surface roughness induced by ion implantation and oxidation of the roughened surface during implantation and carbon nanotube growth. This study provides an alternative idea to predetermine the growth sites of nanotubes in fabricating arrays of aligned nanotubes on silicon substrates.
Size dependence of photoluminescence and resonant Raman scattering from ZnO quantum dots
Authors: Cheng Hsin-Ming , Lin Kuo-Feng , Hsu Hsu-Cheng , Hsieh Wen-Feng
Published: July 2006

ZnO quantum dots (QDs) of controlled sizes have been fabricated by a simple sol-gel method. The blueshift of room-temperature photoluminescence measurement from free exciton transition are observed decreasing with the QD size that is ascribed to the quantum confinement effect. From the resonant Raman scattering, the coupling strength between electron and longitudinal optical phonon, deduced from the ratio of the second- to the first-order Raman scattering intensity, diminishes with reducing the ZnO QD diameter. The size dependence of electron-phonon coupling is principally a result of the Fröhlich interaction.
Electrocoalescence of drops synchronized by size-dependent flow in microfluidic channels
Authors: Ahn Keunho , Agresti Jeremy , Chong Henry , Marquez Manuel , Weitz D. A.
Published: July 2006

The use of microfluidic devices to control drops of water in a carrier oil is a promising means of performing biological and chemical assays. An essential requirement for this is the controlled coalescence of pairs of drops to mix reagents together. We show that this can be accomplished through electrocoalescence of drops synchronized by size-dependent flow in microfluidic channels. Smaller drops move faster due to the Poiseuille flow, allowing pairs of surfactant-stabilized drops to be brought into contact where they are coalesced with an electric field. We apply this method to an enzyme assay to measure enzyme kinetic constants.
Study of pore structure and stability in porous low-k interconnects using electrolyte voltammetry
Authors: Meng D. M. , Michael N. L. , Kim Choong-Un , Park Young-Joon
Published: July 2006

This letter presents a step-mode voltammetry method which uses ion diffusivity to characterize pore structure in both dense and porous low dielectric constant materials (low k) in patterned interconnect structures. Findings reveal that the intramolecular space in dense low k acts like a small physical pore network. It is determined that electrolyte ions can migrate through such space in dense low k, but with higher activation energy than in porous low k or the bulk solution, 0.31eV vs 0.18–0.19eV. Also, this study finds that the pores in ultralow k are not stable but can either coalesce or collapse depending on stress conditions.
Vertical alignment of liquid crystal on a-SiOx thin film using the ion beam exposure
Authors: Son Phil Kook , Park Jeung Hun , Cha Sung Su , Kim Jae Chang , Yoon Tae-Hoon , Rho Soon Joon , Jeon Baek Kyun , Kim Jang Sub , Lim Soon Kwon , Kim Kyeong Hyeon
Published: July 2006

In this letter we demonstrate the vertical alignment of liquid crystal on inorganic thin film surfaces using the ion beam exposure. Nematic liquid crystal can be aligned vertically by the rotational oblique evaporation of a-SiOx thin films. However, the electro-optic switching behavior of liquid crystal along random directions results in disclination lines. By using the ion beam exposure, we can achieve highly uniform alignment without disclination lines. We found from x-ray diffraction and x-ray photoemission spectroscopy data that the vertical alignment can be achieved when x approaches 1.5 at the a-SiOx film surface. We have shown that the pretilt angle can be controlled by changing ion beam parameters, such as the ion beam energy, the angle of incidence, and the exposure time. We also have shown that a liquid crystal cell aligned vertically by the ion beam exposure exhibits the voltage-transmittance curve similar to that of a rubbed polyimide cell.
Ge-dot/Si multilayered structures through Ni-induced lateral crystallization
Authors: Yan Bo , Shi Yi , Pu Lin , Zhu Jianmin , Zhang Kuangji , Ma Guobin , Han Ping , Zhang Rong , Zheng Youdou
Published: July 2006

We demonstrate a method for fabricating high-quality Ge-dot/Si multilayered structures. High-density self-assembled Ge dots are grown on amorphous Si layer periodically by low-pressure chemical vapor deposition, and then the amorphous Si are crystallized through Ni-based metal-induced lateral crystallization. Optical microscopy, micro-Raman spectroscopy, and electron microscopy observations reveal that the crystallized Si film has large leaflike grains elongated along the lateral crystallization direction, which shows (110) preference. Furthermore, this preference is found to deliver to different Si layers. The strain shift of Ge dots deduced from Raman spectroscopy reveals a formation of a high-quality interface between the crystallized Si and Ge dot.
Influence of vibrational wave form on intruder clustering
Authors: Sanders D. A. , Swift Michael R. , Bowley R. M. , King P. J.
Published: July 2006

It has recently been shown that, within a two-dimensional granular bed subjected to sinusoidal, vertical vibration, neutrally buoyant intruders attract each other over a distance of up to five intruder diameters. The interaction between these intruders is the net result of attractive and repulsive forces which occur at different parts of the vibration cycle. Here we show that these forces may be manipulated by altering the vibration wave form to vary the strength of the overall attraction, or even to produce a weak repulsion. This ability is important for controlling the mixing of larger grains held within a granular bed.
Effect of collisions in the stratified presheath in electronegative plasmas
Authors: Fernández Palop J. I. , Ballesteros J. , Morales Crespo R. , Hernández M. A.
Published: July 2006

The effect of collisions in the formation of a stratified presheath in electronegative plasmas is analyzed. Collisions do not affect to the sheath-presheath structure in pure electropositive plasmas; however, in the case of electronegative plasmas, they can produce a large effect, changing the electric potential distribution in the presheath from monotonic to oscillatory, and viceversa. The influence of the collision rate on the plasma parameter space region in which the presheath becomes stratified is analyzed.
Facets evolution and surface electrical properties of nonpolar m-plane ZnO thin films
Authors: Zúñiga-Pérez J. , Muñoz-Sanjosé V. , Palacios-Lidón E. , Colchero J.
Published: July 2006

ZnO thin films have been grown along the nonpolar [101¯0] direction by metal organic vapor phase epitaxy. The ZnO (101¯0) surface develops well defined facets. The orientation of the topographic normals reveals that the inclination angle of the facets increases as thicker films are considered, attaining a maximum value of about 28.4°. This angle corresponds to {101¯1}- and {101¯1¯}-type facets. The origin of this faceting is discussed in terms of thermodynamic stability and kinetics arguments. The surface electrical properties of the facets have been studied by Kelvin probe microscopy, showing that the surface has different contact potential domains that alternate along the polar [0001] direction.
Thermal stability and its prediction of bulk metallic glass systems
Authors: Xia Mingxu , Zhang Shuguang , Li Jianguo , Ma Chaoli
Published: July 2006

We report a linear relationship between the thermal stability (ΔTx) and the amorphous formation enthalpy (ΔHam) of typical bulk metallic glasses (BMGs). The value of the slope of ΔTx vs ΔHam reflects the sensitivity of thermal stability to composition and the sign of the slope implies whether the local atomic structure of amorphous phase is similar to that of primary crystalline phase. A positive slope suggests a similarity between them and vice versa. We also demonstrate that the thermal stability can be fastly assessed and predicted by ΔHam at less cost using Ti53Cu15Ni18.5Al7M3Si3B0.5 (M=Hf,Sc,Ta,Nb) BMGs.
Ordering Fe nanowire on stepped Cu (111) surface
Authors: Tan X. , Ouyang G. , Yang G. W.
Published: July 2006

We describe formation of Fe nanowires with varying widths at the upper step edges on a vicinal Cu (111) surface via kinetic Monte Carlo simulations on the basis of step decoration effects. The existence of an optimal temperature and deposition flux for the formation of the well-ordered Fe nanowires on stepped Cu (111) surface is found. The physical origin of the formation of Fe nanowires on stepped Cu (111) surfaces is pursued.
Linear signal-compensated amplifier for reactor power measuring channels
Authors: Khaleeq M. Tahir , Atique-ur-Rahman  , Ahmed Eijaz
Published: July 2006

A linear amplifier with automatic signal compensation has been developed for nuclear channels. The amplifier controls its sensitivity automatically according to the reference input within the desired settings and has automatic signal compensation capability for use in the nuclear channels. The amplifier will be used in the existing safety channel of Pakistan Research Reactor-1, where the system has an independent sensitivity control unit for manual compensation of xenon effect. The new amplifier will improve the safety of the system. The amplifier is tested and the results found are in very good agreement with the designed specifications. This article presents design and construction of the amplifier and test results.
Floral ontogeny of Hardenbergia violacea (Fabaceae: Faboideae: Phaseoleae) and taxa of tribes Bossiaeeae and Mirbelieae, with emphasis on presence of pseudoraceme inflorescences
Authors: Tucker Shirley C.
Published: June 2006

The floral ontogeny of several Australian papilionoid taxa has been studied in Hardenbergia violacea L. (Phaseoleae); Kennedia rubicunda (Phaseoleae; inflorescences only); Bossiaea cordigera (Bossiaeeae); Gastrolobium truncatum, Mirbelia oxylobioides, and Pultenaea daphnoides (Mirbelieae). Species studied of Hardenbergia, Pultenaea, and Brachysema have pseudoracemose inflorescences comprised of triads of flowers, Kennedia rubicunda has paired flowers that resemble reduced pseudoracemes, while Gastrolobium truncatum and Mirbelia oxylobioides have pseudoracemes comprised of 2–10 flowers per ultimate unit. Pseudoracemes are a significant and overlooked feature in many taxa of tribes Bossiaeeae and Mirbelieae. Hardenbergia violacea has ultimate axillary units of three flowers, each with a subtending bract but no bracteoles. Floral ontogeny in H. violacea and P. daphnoides shows acropetal order among whorls, and unidirectional order starting from the abaxial side in sepal, petal, and stamen whorls, as in most papilionoid flowers. The carpel is initiated concurrently with the first antesepalous stamen primordium. Pultenaea daphnoides and Bossiaea cordigera have unidirectional sepal initiation starting abaxially, but simultaneous petal initiation, an unusual feature among papilionoids. In late stages of H. violacea and B. cordigera, a diadelphous stamen tube or sheath is formed, while in taxa of Mirbelieae the stamens remain free. The flowers in all taxa studied become strongly zygomorphic as evidenced by three petal morphs and upturning of the free portions of style and stamens late in development.
Australia's wasp-pollinated flying duck orchids revised (Paracaleana: Orchidaceae)
Authors: Hopper Stephen D. , Brown Andrew P.
Published: June 2006

We uphold the generic rank of Paracaleana on the basis of its divergent pollination syndrome (sexual deception of male thynnid wasps compared with pollination of Caleana by male sawflies), recent DNA sequence data demonstrating monophyly, and nomenclatural stability. Ten of the 13 species recognised herein are new, all endemic to the South-west Australian Floristic Region: Paracaleana alcockii, P. brockmanii, P. dixonii, P. gracilicordata, P. granitica, P. hortiorum, P. lyonsii, P. parvula, P. terminalis and P. triens. Although some of these taxa have subtle morphological differences, primarily of labellum morphology, evidence from other Australian orchid genera whose flowers sexually deceive wasp pollinators indicates that reproductive isolation is probable among close sister taxa in Paracaleana. Moreover, phenological, ecological and geographical differences help separate morphologically close sister taxa. P. disjuncta D.L. Jones is considered to extend from Victoria and South Australia west into the South-west Australian Floristic Region, where James Drummond first collected the species, probably in 1838. Additional research is needed on pollinators, molecular phylogeny, possibly undescribed taxa within P. nigrita and on the few putative hybrids identified in the genus.
Dendrobium speciosum (Dendrocoryne: Orchidaceae) complex in north Queensland
Authors: Adams Peter B. , Burke Jacinta M. , Lawson Sheryl D.
Published: June 2006

Dendrobium speciosum Sm. has received insufficient taxonomic study north of St Lawrence, Queensland, where plants display much morphological variation in diverse habitats. Two varieties have been described previously, variety pedunculatum, occurring north of Townsville, and variety curvicaule for plants between the Connors Range south of Mackay and Annan River, south of Cooktown. In this multivariate analysis of 107 representative plants sampled from areas between St Lawrence and Cooktown, cluster analysis and principal coordinates analysis, were used to categorise the variation. Three overlapping varieties are revealed. North of Townsville variety pedunculatum intergrades with a medium-to-tall rainforest form, which separates with a small overlap in analyses from variety curvicaule plants south of Townsville. We formally describe these rainforest forms, previously referred to as variety curvicaule, as a new variety, Dendrobium speciosum variety boreale, which occurs between Cooktown and Mt Elliot, south of Townsville. Variety boreale is characterised by the presence of a collum in most individuals, medium to long pseudobulbs, large, wide leaves, long pedicels, and fairly uniform off-white to cream flowers. Dendrobium speciosum variety curvicaule Bailey is shown to be a name of uncertain application, and is neotypified to apply to the southern group of north Queensland plants, which occur between St Lawrence and Mt Dryander and on the Whitsunday Islands. Variety curvicaule is characterised by pseudobulbs that are of medium length, wide base and have an inconspicuous collum. The flowers have relatively wide segments in relation to all other varieties, long wide petals and incurving lateral sepals.
Interaction of two hereditary spastic paraplegia gene products, spastin and atlastin, suggests a common pathway for axonal maintenance
Authors: Evans Katia , Keller Christian , Pavur Karen , Glasgow Kristen , Conn Bryan , Lauring Brett
Published: July 2006

Hereditary spastic paraplegia (HSP) is a neurodegenerative disorder that is characterized by retrograde axonal degeneration that primarily affects long spinal neurons. The disease is clinically heterogeneous, and there are >20 genetic loci identified. Here, we show a physical interaction between spastin and atlastin, two autosomal dominant HSP gene products. Spastin encodes a microtubule (MT)-severing AAA ATPase (ATPase associated with various activities), and atlastin encodes a Golgi-localized integral membrane protein GTPase. Atlastin does not regulate the enzymatic activity of spastin. We also identified a clinical mutation in atlastin outside of the GTPase domain that prevents interaction with spastin in cells. Therefore, we hypothesize that failure of appropriate interaction between these two HSP gene products may be pathogenetically relevant. These data indicate that at least a subset of HSP genes may define a cellular biological pathway that is important in axonal maintenance.
CTCF binding at the
H19
imprinting control region mediates maternally inherited higher-order chromatin conformation to restrict enhancer access to
Igf2
Authors: Kurukuti Sreenivasulu , Tiwari Vijay Kumar , Tavoosidana Gholamreza , Pugacheva Elena , Murrell Adele , Zhao Zhihu , Lobanenkov Victor , Reik Wolf , Ohlsson Rolf
Published: July 2006

It is thought that the
H19
imprinting control region (ICR) directs the silencing of the maternally inherited
Igf2
allele through a CTCF-dependent chromatin insulator. The ICR has been shown to interact physically with a silencer region in
Igf2
, differentially methylated region (DMR)1, but the role of CTCF in this chromatin loop and whether it restricts the physical access of distal enhancers to
Igf2
is not known. We performed systematic chromosome conformation capture analyses in the
Igf2
/
H19
region over >160 kb, identifying sequences that interact physically with the distal enhancers and the ICR. We found that, on the paternal chromosome, enhancers interact with the
Igf2
promoters but that, on the maternal allele, this is prevented by CTCF binding within the
H19
ICR. CTCF binding in the maternal ICR regulates its interaction with matrix attachment region (MAR)3 and DMR1 at
Igf2
, thus forming a tight loop around the maternal
Igf2
locus, which may contribute to its silencing. Mutation of CTCF binding sites in the
H19
ICR leads to loss of CTCF binding and
de novo
methylation of a CTCF target site within
Igf2
DMR1, showing that CTCF can coordinate regional epigenetic marks. This systematic chromosome conformation capture analysis of an imprinting cluster reveals that CTCF has a critical role in the epigenetic regulation of higher-order chromatin structure and gene silencing over considerable distances in the genome.
Discovery of protein phosphatase inhibitor classes by biology-oriented synthesis
Authors: Nören-Müller Andrea , Reis-Corrêa Ivan , Prinz Heino , Rosenbaum Claudia , Saxena Krishna , Schwalbe Harald J. , Vestweber Dietmar , Cagna Guiseppe , Schunk Stefan , Schwarz Oliver , Schiewe Hajo , Waldmann Herbert
Published: June 2006

Protein phosphatases have very recently emerged as important targets for chemical biology and medicinal chemistry research, and new phosphatase inhibitor classes are in high demand. The underlying frameworks of natural products represent the evolutionarily selected fractions of chemical space explored by nature so far and meet the criteria of relevance to nature and biological prevalidation most crucial to inhibitor development. We refer to synthesis efforts and compound collection development based on these criteria as biology-oriented synthesis. For the discovery of phosphatase inhibitor classes by means of this approach, four natural product-derived or -inspired medium-sized compound collections were synthesized and investigated for inhibition of the tyrosine phosphatases VE-PTP, Shp-2, PTP1B, MptpA, and MptpB and the dual-specificity phosphatases Cdc25A and VHR. The screen yielded four unprecedented and selective phosphatase inhibitor classes for four phosphatases with high hit rates. For VE-PTP and MptpB the first inhibitors were discovered. These results demonstrate that biology-oriented synthesis is an efficient approach to the discovery of new compound classes for medicinal chemistry and chemical biology research that opens up new opportunities for the study of phosphatases, which may lead to the development of new drug candidates.
Naive CD4 T cells constitutively express CD40L and augment autoreactive B cell survival
Authors: Lesley Robin , Kelly Lisa M. , Xu Ying , Cyster Jason G.
Published: July 2006

Chronic engagement of the B cell receptor by soluble autoantigen leads to reduced B cell survival. Using the Ig and hen egg lysozyme double transgenic mouse model, we demonstrate that the survival of soluble autoantigen-engaged B cells is further reduced in mice lacking CD4 T cells or deficient in CD40. Mixed bone marrow chimera experiments reveal that, under homeostatic conditions, the CD40L–CD40 pathway can augment autoreactive B cell survival in a non-cell-autonomous manner. Naive CD4 T cells are shown to constitutively express CD40L mRNA and protein, although cell surface CD40L abundance is low because of engagement with CD40 on other cells. These observations indicate that the CD40L–CD40 pathway can augment the survival of autoantigen-engaged B cells in the absence of T cell activation. We propose that constitutive CD40L expression by naive CD4 T cells influences the composition of the B cell repertoire and may also affect the homeostasis of other cell types such as regulatory T cells in lymphoid organs.
Abrupt tropical climate change: Past and present
Authors: Thompson Lonnie G. , Mosley-Thompson Ellen , Brecher Henry , Davis Mary , León Blanca , Les Don , Lin Ping-Nan , Mashiotta Tracy , Mountain Keith
Published: July 2006

Three lines of evidence for abrupt tropical climate change, both past and present, are presented. First, annually and decadally averaged δ
18
O and net mass-balance histories for the last 400 and 2,000 yr, respectively, demonstrate that the current warming at high elevations in the mid- to low latitudes is unprecedented for at least the last 2 millennia. Second, the continuing retreat of most mid- to low-latitude glaciers, many having persisted for thousands of years, signals a recent and abrupt change in the Earth’s climate system. Finally, rooted, soft-bodied wetland plants, now exposed along the margins as the Quelccaya ice cap (Peru) retreats, have been radiocarbon dated and, when coupled with other widespread proxy evidence, provide strong evidence for an abrupt mid-Holocene climate event that marked the transition from early Holocene (pre-5,000-yr-B.P.) conditions to cooler, late Holocene (post-5,000-yr-B.P.) conditions. This abrupt event, ≈5,200 yr ago, was widespread and spatially coherent through much of the tropics and was coincident with structural changes in several civilizations. These three lines of evidence argue that the present warming and associated glacier retreat are unprecedented in some areas for at least 5,200 yr. The ongoing global-scale, rapid retreat of mountain glaciers is not only contributing to global sea-level rise but also threatening freshwater supplies in many of the world’s most populous regions.
Pancreatic β cells lack a low glucose and O
2
-inducible mitochondrial protein that augments cell survival
Authors: Wang Jie , Cao Yun , Chen Ying , Chen Yimei , Gardner Paul , Steiner Donald F.
Published: July 2006

β cell failure is a common denominator of diabetes. Susceptibility to stress-induced apoptosis may underlie β cell failure and/or hamper islet transplantation therapy. The causal basis is not well understood. In efforts to identify important differences in gene expression in α vs. β cells, a gene termed
HIMP1
(Hypoglycemia/hypoxia Inducible Mitochondrial Protein, or
HIG1
) has been cloned from an α cell cDNA library. It is a member of a well conserved eukaryote protein family. In mice, its two alternatively spliced products each form a transmembrane loop, having an N
outside
–C
outside
orientation and are expressed highly in the mitochondrial inner membrane in several tissues including heart and pancreatic α cells, but not in β cells. Ectopic expression of HIMP1 in MIN6 β cells protects the cells from apoptosis induced by several stimuli and prolongs their survival. These results suggest an important role for HIMP1 in stress protective programs in mitochondria.
Arithmetic processing in the brain shaped by cultures
Authors: Tang Yiyuan , Zhang Wutian , Chen Kewei , Feng Shigang , Ji Ye , Shen Junxian , Reiman Eric M. , Liu Yijun
Published: July 2006

The universal use of Arabic numbers in mathematics raises a question whether these digits are processed the same way in people speaking various languages, such as Chinese and English, which reflect differences in Eastern and Western cultures. Using functional MRI, we demonstrated a differential cortical representation of numbers between native Chinese and English speakers. Contrasting to native English speakers, who largely employ a language process that relies on the left perisylvian cortices for mental calculation such as a simple addition task, native Chinese speakers, instead, engage a visuo-premotor association network for the same task. Whereas in both groups the inferior parietal cortex was activated by a task for numerical quantity comparison, functional MRI connectivity analyses revealed a functional distinction between Chinese and English groups among the brain networks involved in the task. Our results further indicate that the different biological encoding of numbers may be shaped by visual reading experience during language acquisition and other cultural factors such as mathematics learning strategies and education systems, which cannot be explained completely by the differences in languages
per se
.
Perforation of the colon: a rare complication of hepatocellular carcinoma
Authors: Zech C. J. , Bilzer M. , Mueller-Lisse U. G. , Steitz H. O. , Haraida S. , Reiser M. F.
Published: June 2006

Direct infiltration of the colon by hepatocellular carcinoma (HCC) is a rare condition. Only a few reports can be found in the literature. Here we present a case of direct infiltration of the ascending colon by an exophytic growing HCC of the right posterior liver lobe, in which treatment with transarterial chemoembolization (TACE) had been performed. Tumor invasion became evident by abdominal pain and lower gastrointestinal bleeding. Diagnosis was established by contrast-enhanced multidetector computed tomography (CE-MDCT), demonstrating the direct tumor invasion with concomitant perforation of the infiltrated colon segment. Based on these findings, rapid and effective surgical treatment could be achieved.
Low-fat angiomyolipoma of the liver studied with contrast-enhanced ultrasound and multidetector computed tomography
Authors: Flor N. , Sardanelli F. , Serantoni S. , Brovelli F. , Cornalba G. P.
Published: June 2006

We report the case of a 30-year-old woman with persistent pain at the right hypochondrium, relapsing fever, and normal serum tests. Ultrasound showed a hyperechoic inhomogeneous mass; following sulfur hexafluoride injection, uniform enhancement at 14–16 s and rapid wash-out at 26 s was found. Multidetector computed tomography showed an inhomogeneously hypodense mass, with no detectable negative density values, characterized by inhomogeneous enhancement at the arterial phase and wash-out at the portal phase. Histopathology demonstrated a hepithelioid angiomyolipoma with a poor fatty component. This diagnosis should always be considered in the presence of a very rapid wash-out after intravenous contrast injection. However, a hepatocellular carcinoma cannot be excluded and the final diagnosis of low-fat angiomyolipoma must be pathologically proved based on immunohistochemistry.
Recovery of ovarian function after detorsion: doppler findings
Authors: Cil A. P. , Akgul M. A. , Tulunay G. , Atayar Y. Y.
Published: June 2006

Adnexal torsion is one of the most common surgical gynecologic emergencies and needs prompt diagnosis. It usually occurs during reproductive age, which makes the early diagnosis all the more important in attempting to preserve ovarian function. If adnexal torsion is suspected from the clinical findings, Doppler ultrasound can be the best tool in diagnosis. It can also be helpful in assessing recovery of the ovary after surgical treatment. We present a case of adnexal torsion successfully diagnosed with power Doppler ultrasound and managed by detorsion. The postoperative gray-scale and power Doppler examination confirmed the recovery of ovarian follicles and stoma.
Visualization of cervical nerve roots and their distal nerve fibers by diffusion-weighted scanning using parallel imaging
Authors: Tsuchiya K. , Fujikawa A. , Tateishi H. , Nitatori T.
Published: June 2006

Purpose: To report a technique developed for visualizing cervical nerve roots and distal nerve fibers using diffusion-weighted magnetic resonance imaging employing parallel imaging.

Material and Methods: We performed maximum intensity projection for a stack of isotropic axial diffusion-weighted images obtained with parallel imaging applying a motion-probing gradient in six directions with a b-value of 500 s/mm2 in a preliminary series of 13 subjects.

Results: This method worked well for visualizing the spinal cord and most of the nerve roots, the dorsal root ganglia, and proximal peripheral nerves.

Conclusion: Although the technique remains limited in depicting the brachial plexus and distal nerves, the ability to visualize the proximal peripheral nervous system at the cervical level is promising.
Magnetic resonance imaging comparison of intra-articular cavernous synovial hemangioma and cystic synovial hyperplasia of the knee
Authors: De Filippo M. , Rovani C. , Sudberry J. J. , Rossi F. , Pogliacomi F. , Zompatori M.
Published: June 2006

Purpose: To identify and compare magnetic resonance imaging (MRI) characteristics, with and without intravenous contrast medium, of cavernous synovial hemangiomas and cystic synovial hyperplasia.

Material and Methods: Four cases of cavernous synovial hemangioma and five of cystic synovial hyperplasia of the knee were studied retrospectively. The patients (5 F and 4 M; 15–25 years of age) all had long-standing knee pain. At clinical examination we observed elastic swelling and pain without significant joint effusion. The patients underwent conventional radiography and MRI without and following intravenous contrast medium before arthroscopic biopsy.

Results: The radiographs were interpreted as negative in all patients. MRI examination without contrast medium revealed a similar multicystic appearance for both lesions. Following intravenous contrast agent administration, cavernous synovial hemangiomas demonstrated avid, rather homogenous enhancement, whereas cystic synovial hyperplasia demonstrated less intense, peripheral enhancement only. Arthroscopy with histological examination of the lesions confirmed the MRI diagnosis in every case.

Conclusion: In our experience, cavernous synovial hemangioma and cystic synovial hyperplasia have a similar appearance on unenhanced MRI, but can be reliably differentiated on the basis of enhancement characteristics following intravenous contrast administration.
Ichthyotherapy as Alternative Treatment for Patients with Psoriasis: A Pilot Study
Authors: Grassberger Martin , Hoch W.
Published: July 2006

Ichthyotherapy (therapy with the so‐called ‘Doctorfish of Kangal’, Garra rufa) has been shown to be effective in patients with psoriasis in the Kangal hot springs in Turkey. This study evaluates the efficacy and safety of ichthyotherapy in combination with short‐term ultraviolet A sunbed radiation in the treatment of psoriasis under controlled conditions. We retrospectively analyzed 67 patients diagnosed with psoriasis who underwent 3 weeks of ichthyotherapy at an outpatient treatment facility in Lower Austria between 2002 and 2004. Main outcome measures are as follows: overall relative reduction in Psoriasis Area Severity Index (PASI) score; proportion of patients with an improvement in their PASI score of ≥75% (PASI‐75) and ≥50% (PASI‐50); patient‐reported outcomes assessed with a custom questionnaire; and patient follow‐up with a questionnaire sent out in March 2005. Safety was evaluated by reviewing adverse events and vital signs. Overall there was a 71.7% reduction in PASI score compared to baseline (P < 0.0001). Of the 67 patients studied, 31 (46.3%) achieved PASI‐75 and 61 patients (91%) achieved at least PASI‐50. Patients reported substantial satisfaction with the treatment. The reported mean remission period was 8.58 months [95% confidence interval (CI) 6.05–11.11]. A total of 87.5% of patients reported a more favorable outcome with ichthyotherapy, when asked to compare ichthyotherapy to other previously tried therapies. Sixty‐five percent stated that after the relapse their symptoms were less severe than before treatment. There were no significant adverse events. The benefit demonstrated in this study along with the favorable safety profile suggests that ichthyotherapy could provide a viable treatment option for patients with psoriasis.
Connecting the Congress: A Study of Cosponsorship Networks
Authors: Fowler James H.
Published: July 2006

Using large-scale network analysis I map the cosponsorship networks of all 280,000 pieces of legislation proposed in the U.S. House and Senate from 1973 to 2004. In these networks, a directional link can be drawn from each cosponsor of a piece of legislation to its sponsor. I use a number of statistics to describe these networks such as the quantity of legislation sponsored and cosponsored by each legislator, the number of legislators cosponsoring each piece of legislation, the total number of legislators who have cosponsored bills written by a given legislator, and network measures of closeness, betweenness, and eigenvector centrality. I then introduce a new measure I call “connectedness” which uses information about the frequency of cosponsorship and the number of cosponsors on each bill to make inferences about the social distance between legislators. Connectedness predicts which members will pass more amendments on the floor, a measure that is commonly used as a proxy for legislative influence. It also predicts roll call vote choice even after controlling for ideology and partisanship.
Specification Issues in Proximity Models of Candidate Evaluation (with Issue Importance)
Authors: Grynaviski Jeffrey D. , Corrigan Bryce E.
Published: June 2006

The use of the proximity model to represent the relationship between citizens' policy attitudes and the positions of candidates on the issues of the day has considerable appeal because it offers a bridge between theoretical models of political behavior and empirical work. However, there is little consensus among applied researchers about the appropriate representation of voter behavior with respect to the measurement of issue distance, candidate location, or whether to allow heterogeneity in the weight that each individual places on particular issues. Each of these choices suggests a different, and reasonably complicated, nonlinear relationship between voter utility and candidate and voter issue positions which may have a meaningful influence on the substantive conclusions drawn by the researcher. Yet, little attention has been given to the best way to represent the proximity model in applied work. The purpose of this paper is to identify which forms of the proximity model work best, with particular consideration given to the identification of functional forms that are invariant to the choice of scale for the independent variables.
Long‐Term Results of Boerema Anterior Gastropexy in Children
Authors: Kloek J.J. , van de Laar G.A.G. , Deurloo J.A. , Aronson D.C. , Benninga M.A. , Taminiau J.A.J.M. , Heij H.A.
Published: July 2006

Objectives:

To analyze the long‐term results of Boerema anterior gastropexy using the Visick grading system in a university teaching hospital.

Methods:

Retrospective review of 247 children with severe or complicated gastroesophageal reflux disease (GERD). Patients who underwent primary gastropexy between 1990 and 2001 were divided in 3 groups: (A) neurologic impaired patients (n = 83); (B) esophageal atresia patients (n = 36); and (C) patients without underlying disease (n = 128). The median length of follow‐up after gastropexy was 7 years and 8 months (range, 1.5‐13 years). Follow‐up was carried out using a standardized questionnaire and was obtained by telephone. Postoperative recurrence of symptoms during follow‐up was considered as failure of the operation.

Results:

Postoperative complications occurred in 20 patients (24%) in group A, in 13 patients (36%) in group B and in 23 patients (18%) in group C. Thirty‐three patients died during the follow‐up period, 5 of whom during the postoperative period. Six children could not be traced; thus, 208 were available for long‐term follow‐up. Postoperative failures occurred in 12 patients (23%) in group A, in 11 patients (31%) in group B and in 17 patients in group C (14%). Reoperation for recurrence of symptoms due to GERD was performed in 6 patients in group A, in 7 patients in group B and in 2 patients in group C. The final outcome at the time of interview was successful in 81% of group A, in 88% of group B and in 91% of group C.

Conclusions:

In the long term, Boerema anterior gastropexy is an effective operation for complicated GERD in children without underlying disease as well as in neurologically impaired children and patients with esophageal atresia.
Genetic Predisposition to Colorectal Cancer
Authors: Durno Carol A. , Gallinger Steven
Published: July 2006

Colorectal cancer is rare in childhood. The 2 best characterized familial syndromes, hereditary nonpolyposis colorectal cancer (HNPCC, Lynch syndrome) and familial adenomatous polyposis (FAP), are autosomal dominant inherited disorders. HNPCC is relevant to pediatric gastroenterology practice because children and adolescents with underlying colorectal cancer can have germ‐line mutations of mismatch repair genes. Recent attention has focused on characterizing genetic predisposition to attenuated FAP in individuals who do not have germ‐line mutations in the APC gene. The identification of a second mechanistic explanation called MYH‐associated polyposis (MAP), which is an autosomal‐recessive condition, has important implications for both screening and management strategies. Hereditary colorectal cancer including HNPCC, FAP, attenuated FAP and MYH‐associated polyposis in children are the subject of this review.
Variable Degree of Liver Involvement in Siblings With PiZZ Alpha‐1‐Antitrypsin Deficiency‐related Liver Disease
Authors: Hinds R. , Hadchouel A. , Shanmugham N.P. , Al‐Hussaini A. , Chambers S. , Cheeseman P. , Mieli‐Vergani G. , Hadžić N.
Published: July 2006

PiZZ alpha‐1‐antitrypsin deficiency is the commonest genetic cause of chronic liver disease, but only 10‐15% of PiZZ individuals develop liver disease in childhood. Studies have demonstrated varying patterns of disease progression within siblings with the PiZZ phenotype. We retrospectively analysed the case‐notes of all patients diagnosed with PiZZ A1ATD between 1978‐2002 and compared the pattern of liver disease between affected siblings. We identified 29 families with more than 1 child with the PiZZ phenotype. Twenty‐one (72%) PiZZ siblings of the 29 probands had liver disease, which was concordant for severity in 6 (29%), while 8 (28%) had no liver involvement. Five of 7 children requiring liver transplantation had siblings with no persistent liver dysfunction. This study suggests that there is a variable degree of liver involvement in siblings with PiZZ A1ATD‐related liver disease and environmental and/or other genetic factors must be involved in determining disease severity.
Treatment of Nonorganic Recurrent Abdominal Pain
Authors: Duarte Marco Antônio , Penna Francisco José , Andrade Eugênio Marcos Goulart , Cancela Camila Silva Peres , Neto Joaquim Caetano Aguirre , Barbosa Terezinha Facury
Published: July 2006

Objectives:

We evaluated the efficacy of cognitive‐behavioral family intervention in the treatment of crises of pain in children with nonorganic recurrent abdominal pain (RAP) and the thresholds of pain for 17 body surface areas in these children.

Methods:

A randomized clinical trial was undertaken with 32 children between the ages of 5.1 and 13.9 years with nonorganic RAP. A group of 15 patients, aged 9.9 ± 2.2 years (11 girls), received standard pediatric care and cognitive‐behavioral family intervention for treatment of pain crises. The control group of 17 children, aged 8.4 ± 2.0 years (11 girls), received only standard pediatric care. These procedures were undertaken by general pediatricians over 4 monthly sessions. An analog visual scale was used to measure the frequency and intensity of the pain crises per month and a mechanical pressure algometer for the measurement of pain threshold.

Results:

The median frequency of pain crises per month reported by patients at the 3 monthly cognitive‐behavioral family intervention sessions was 15, 5, 2 and 2, respectively. In contrast, the median frequency for pain crises per month reported by the control group was 12, 8, 10 and 8, respectively. The difference between the intervention group and the controls was statistically significant for frequency of pain at the second, third and fourth visits. There was no statistical difference for intensity of pain or for measured pain thresholds between the control and the intervention group.

Conclusions:

The cognitive‐behavioral family intervention reduced the frequency of pain crises of children with nonorganic RAP. This successful intervention was carried out by the intervention of general pediatricians.
Treatment of Faecal Impaction with Polyethelene Glycol Plus Electrolytes (PGE + E) Followed by a Double‐blind Comparison of PEG + E Versus Lactulose as Maintenance Therapy
Authors: Candy David C.A. , Edwards Diane , Geraint Mike
Published: July 2006

Objectives:

To assess the efficacy of polyethylene glycol 3350 plus electrolytes (PEG + E; Movicol®) as oral monotherapy in the treatment of faecal impaction in children, and to compare PEG + E with lactulose as maintenance therapy in a randomised trial.

Patients and Methods:

An initial open‐label study of PEG + E in the inpatient treatment of faecal impaction (phase 1), followed by a randomised, double‐blind comparison between PEG + E and lactulose for maintenance treatment of constipation over a 3‐month period (phase 2) in children aged 2 to 11 years with a clinical diagnosis of faecal impaction.

Results:

Disimpaction on PEG + E was achieved in 58 (92%) of 63 of children (89% of 2‐4 year olds and 94% of 5‐11 year olds) without additional interventions. A maximum dose of 4 sachets (for 2‐4 year olds) or 6 sachets (for 5‐11 year olds) was required; median time to disimpaction was 6 days (range, 3‐7 days). Seven children (23%) reimpacted whilst taking lactulose, whereas no children reimpacted while taking PEG + E (P = 0.011). The total incidence rate of adverse events seen was higher in the lactulose group (83%) than in the PEG + E group (64%).

Conclusions:

PEG + E is safe and highly effective in the management of childhood constipation. It allows a single orally administered laxative to be used for disimpaction without recourse to invasive interventions. It is significantly more effective than lactulose as maintenance therapy, both in efficacy in treating constipation and efficacy in preventing the recurrence of faecal impaction.