bluuebunny/crossref_metadata_2025 huggingface dataset:
On transient growth oscillations in linear models
Authors: Coppola Gennaro , de Luca Luigi
Published: August 2006

The study of oscillating norm behavior in linear systems is addressed. The analysis is carried out by considering a model equation that naturally arises in the context of the linearized formulation of some convection-dominated systems over finite length domains. The occurrence of oscillating patterns in the energy evolution of the solutions is linked to the structure of the spectrum and to the non-normal character of the linear operator involved. A distinction between transient and asymptotic oscillations is made and some relations between the frequency signatures shown in both cases and global characteristics of the spectrum are highlighted. The physical importance of such oscillating behaviors is stressed by reconsidering a model for the linear stability of a falling liquid curtain studied by other authors in a previous work.
Analysis of experimental data for the nucleation rate of water droplets
Authors: Kashchiev Dimo
Published: August 2006

A formula for the stationary nucleation rate J is proposed and used for analysis of experimental data for the dependence of J on the supersaturation ratio S in isothermal homogeneous nucleation of water droplets in vapors. It is found that the experimental data are described quite successfully by the proposed formula which is based on (i) the Gibbs presentation of the nucleation work in terms of overpressure, (ii) the Girshick-Chiu [J. Chem. Phys. 93, 1273 (1990); 94, 826 (1991)] self-consistency correction to the equilibrium cluster size distribution, and (iii) the Reguera-Rubi [J. Chem. Phys. 115, 7100 (2001)] kinetic accounting of the nucleus translational-rotational motion. The formula, like that of Wölk and Strey [J. Phys. Chem. B 105, 11683 (2001)], could be used as a semiempirical relation describing the J(S) dependence for nucleation in vapors of single-component droplets or crystals of substances with insufficiently well known equations of state.
Three-dimensional oscillatory thermocapillary flow in encapsulated liquid bridge
Authors: Li You-Rong , Liu Ying-Jie , Peng Lan , Wang Yan
Published: August 2006

In order to understand the fundamental characteristics of thermocapillary convection in an encapsulated liquid bridge, we conducted a series of unsteady three-dimensional numerical simulations of thermocapillary convection in an encapsulated liquid bridge with either 2 or 3mm inner diameter and 4–7mm outer diameter as well as variable height 1–3 mm heated from the top wall and cooled at the bottom wall with an adiabatic free surface. Simulation conditions correspond to those in the experiments of Majima [S. Majima, Phys. Fluids 13, 1517 (2001)]. The simulation results indicate that thermocapillary convection in an encapsulated liquid bridge is axisymmetric and steady at the small Marangoni number. However, when the Marangoni number exceeds some critical value, the flow will undergo a transition to three-dimensional oscillatory flow, which is characterized by a standing wave type oscillation, i.e., the periodic growth and decay of temperature disturbances from cold disk to heat disk. The critical conditions for the onset oscillatory flow are determined and compared with the experimental results. The details of the flow and temperature fields are discussed, and oscillation frequencies are also exhibited.
Density functional theory of fluids in nanopores: Analysis of the fundamental measures theory in extreme dimensional-crossover situations
Authors: González A. , White J. A. , Román F. L. , Velasco S.
Published: August 2006

Two density functional theories, the fundamental measures theory of Rosenfeld [Phys. Rev. Lett. 63, 980 (1989)] and a subsequent approximation by Tarazona [Phys. Rev. Lett. 84, 694 (2000)] are applied to the study of the hard-sphere fluid in two situations: the cylindrical pore and the spherical cavity. The results are compared with those obtained with grand canonical ensemble Monte Carlo simulations. The differences between both theories are evaluated and interpreted in the terms of the dimensional crossover from three to one and zero dimensions.
White organic light-emitting devices with a phosphorescent multiple emissive layer
Authors: Cheng Gang , Zhang Yingfang , Zhao Yi , Lin Yuanyuan , Ruan Chunyan , Liu Shiyong , Fei Teng , Ma Yuguang , Cheng Yanxiang
Published: August 2006

A phosphorescent multiple emissive layer, in which a blue emissive layer is sandwiched between red and green ones, is employed in a white organic light-emitting device (OLED). This OLED has a maximum luminance of 48000cd∕m2 at 17V, a maximum power efficiency of 9.9lm∕W at 4V, and a color rendering index of 82. In addition, the emission color of this device is fairly stable at high luminances: its Commission Internationale de l′Eclairage coordinate slightly changes from (0.431, 0.436) to (0.400, 0.430) when the luminance ranges from 2000to40000cd∕m2.
A new multisymplectic scheme for generalized Kadomtsev-Petviashvili equation
Authors: Jiang Bin , Wang Yushun , Cai Jiaxiang
Published: August 2006

From the multisymplectic Euler box scheme, we derive a new multisymplectic 16-point scheme for the generalized Kadomtsev-Petviashvili equation by eliminating the auxiliary variables. The new scheme is an explicit scheme in sense that it does not need iteration. The results of backward error analysis for the Euler box scheme show that the modified equation associated with the new scheme is not multisymplectic but of a high order approximation to a multisymplectic partial differential equations with a modified structure. Numerical results on one soliton and lump-type solitary waves are reported to illustrate the efficiency of the multisymplectic scheme.
Marked enhancement of synthetic-antiferromagnetic coupling in subnanocrystalline FeCoB∕Ru∕FeCoB sputtered films
Authors: Hashimoto Atsushi , Saito Shin , Omori Kazumi , Takashima Hiroshi , Ueno Tomonori , Takahashi Migaku
Published: August 2006

Extremely large flopping field and saturation field were realized in an FeCoB∕Ru∕FeCoB sputtered film by using subnanocrystalline (Fe65Co35)88B12 soft magnetic material with high saturation magnetization. Phenomenological analysis of synthetic-antiferromagnetic coupling revealed that the bilinear coupling energy induced in this film was three times larger than that in a Co91Zr4Nb5∕Ru∕Co91Zr4Nb5 film. This large bilinear coupling is thought to be the result of not only the suppression of ferromagnetic coupling due to the flat interface between the Ru and FeCoB layers but also the small Ru thickness for the first peak of 0.3nm caused by the Fe-rich soft magnetic material.
Localized and distributed mass detectors with high sensitivity based on thin-film bulk acoustic resonators
Authors: Campanella Humberto , Esteve Jaume , Montserrat Josep , Uranga Arantxa , Abadal Gabriel , Barniol Nuria , Romano-Rodríguez Albert
Published: August 2006

A mass sensor based on thin-film bulk acoustic resonator, intended for biomolecular applications, is presented. The thin film is a (002) AlN membrane, sputtered over Ti∕Pt on a (001) Si wafer, and released by surface micromachining of silicon. Two experiments are proposed to test the mass sensing performance of the resonators: (a) distributed loading with a MgF2 film by means of physical vapor deposition and (b) localized mass growing of a C∕Pt∕Ga composite using focused-ion-beam-assisted deposition, both on the top electrode. For the distributed and localized cases, the minimum detectable mass changes are 1.58×10−8g∕cm2 and 7×10−15g, respectively.
Symmetric H state lifetime in splayed nematic liquid crystal devices
Authors: Brimicombe P. D. , Raynes E. P.
Published: August 2006

The dynamic behavior of splayed nematic devices during sudden voltage application is investigated in detail, both experimentally and through simulation. The symmetric H state forms transiently under such drive conditions, and we show that the lifetime of this state is strongly dependent on the liquid crystal material parameters and the applied voltage. The decay of this state to the asymmetric H states is shown to occur via domain growth: isolated regions of the device form the asymmetric H states, and these domains then grow, taking over the areas containing the symmetric H state.
Dielectric tunability of (110) oriented barium strontium titanate epitaxial films on (100) orthorhombic substrates
Authors: Akcay G. , Misirlioglu I. B. , Alpay S. P.
Published: August 2006

We develop a thermodynamic model to determine the polarization, dielectric permittivity, and tunability of epitaxial ferroelectric films on orthorhombic substrates. In particular, we study the film thickness dependence of the tunability in epitaxial (110) Ba0.6Sr0.4TiO3 films on (001) NdGaO3 substrates. The analysis takes into account the thickness dependence of the internal stress state due to the anisotropic relaxation of epitaxial stresses through the formation of misfit dislocations along the two in-plane directions. We predict significant improvement in the tunability along both in-plane and out-of-plane directions of Ba0.6Sr0.4TiO3 films with increasing film thickness compared to the similar films on cubic substrates.
First-principles modeling of resistance switching in perovskite oxide material
Authors: Jeon Sang Ho , Park Bae Ho , Lee Jaichan , Lee Bora , Han Seungwu
Published: August 2006

We report a first-principles study on SrRuO3∕SrTiO3 interface in the presence of the oxygen vacancy. While the oxygen vacancy on the side of SrTiO3 significantly lowers the Schottky barrier height, the oxygen vacancy close to the interface or inside the metallic electrode results in a Schottky barrier comparable to that of the clean interface. Based on these results, we propose a model for resistance-switching phenomena in perovskite oxide∕metal interfaces where electromigration of the oxygen vacancy plays a key role. Our model provides a consistent explanation of a recent experiment on resistance switching in SrRuO3∕Nb:SrTiO3 interface.
Relaxor behavior of K0.5La0.5Bi2Nb2O9 ceramics
Authors: Karthik C. , Ravishankar N. , Varma K. B. R. , Maglione Mario , Vondermuhll R. , Etourneau J.
Published: August 2006

K 0.5 La 0.5 Bi 2 Nb 2 O 9 , a relaxor, was synthesized and the structural studies confirmed it to be an n=2 member of the Aurivillius oxides. The 12{h00} and 12{hk0} types of superlattice reflections in the electron diffraction patterns reflected the presence of ordered polar regions. A broad dielectric peak with frequency dependent dielectric maximum temperature was observed. The dielectric relaxation obeyed the Vogel-Fulcher relation wherein Ea=0.04eV, Tf=428K,and ωo=1010Hz. The diffuseness parameter γ=2.003 established the relaxor nature and it was attributed to the A-site cationic disorder. The piezoelectric d31 coefficient was 0.5pC∕N at 300K and 2pC∕N at 480K.
Electric readout of magnetization dynamics in a ferromagnet-semiconductor system
Authors: Cywiński Ł. , Dery H. , Sham L. J.
Published: August 2006

We apply an analysis of time-dependent spin-polarized current in a semiconductor channel at room temperature to establish how the magnetization configuration and dynamics of three ferromagnetic terminals, two of them biased and third connected to a capacitor, affect the currents and voltages. In a steady state, the voltage on the capacitor is related to spin accumulation in the channel. When the magnetization of one of the terminals is rotated, a transient current is triggered. This effect can be used for electrical detection of magnetization reversal dynamics of an electrode or for dynamical readout of the alignment of two magnetic contacts.
Scaling behavior of ZnO transparent thin-film transistors
Authors: Hsieh Hsing-Hung , Wu Chung-Chih
Published: August 2006

Scaling behaviors of ZnO transparent thin-film transistors (TTFTs) have been studied by fabricating series of miniaturized ZnO TTFTs having various channel widths and lengths. Mobility of >8cm2∕Vs and on/off ratio of up to 107 are achieved with these TTFTs. Results show that these ZnO TTFTs retain rather well-behaved transistor characteristics down to the channel length of ∼5μm, rendering possible high-resolution applications. More apparent short-channel effects (e.g., lowering of threshold voltages, degradation of the subthreshold slope with the decrease of the channel length and the increase of the drain voltage, loss of hard saturation, etc.) are observed when the channel length is reduced below 5μm.
Evidence for magnetism due to oxygen vacancies in Fe-doped HfO2 thin films
Authors: Hong Nguyen Hoa , Poirot Nathalie , Sakai Joe
Published: August 2006

Fe-doped HfO2 thin films are room temperature ferromagnetic. In comparison with results of the undoped HfO2 films, it seems that the Fe doping is not the main cause for the ferromagnetism but only acts as a catalyst. Experimental results of oxygen annealing and vacuum heat treatments have proven that in this family of compounds, magnetism might originate from oxygen vacancies or defects. Removing oxygen enhances the magnetic moment, while reversibly filling up oxygen vacancies can destroy the ferromagnetic ordering of the system.
Adiabatic and nonadiabatic nanofocusing of plasmons by tapered gap plasmon waveguides
Authors: Pile D. F. P. , Gramotnev D. K.
Published: August 2006

Adiabatic and nonadiabatic nanofocusing of plasmons in tapered gap plasmon waveguides is analyzed using the finite-difference time-domain algorithm. Optimal adaptors between two different subwavelength waveguides and conditions for maximal local field enhancement are determined, investigated, and explained on the basis of dissipative and reflective losses in the taper. Nanofocusing of plasmons into a gap of ∼1nm width with more than 20 times increase in the plasmon energy density is demonstrated in a silver-vacuum taper of ∼1μm long. Comparison with the approximate theory based on the geometrical optics approximation is conducted.
Stochastic simulation of Lagrangian trajectories in near-wall turbulence
Authors: Reynolds A. M.
Published: August 2006

A dissipation-conditioned stochastic model for the simulation of marked fluid-particle trajectories is formulated that reproduces the extreme intermittency of Lagrangian accelerations and Lagrangian velocity increments observed in recent direct numerical simulations (DNS) of near-wall turbulence [Lee, Yeo, and Choi, Phys. Rev. Lett. 92, 144502 (2004); Choi, Yeo, and Lee, Phys. Fluids 16, 779 (2004)]. Model agreement with data from the DNS for the mean-square displacements of marked fluid particles is good and significantly better than that which can be obtained with stochastic models formulated in terms of the mean rather than the fluctuating rate of dissipation of turbulent kinetic energy. The model accounts, in part, for the observed extreme intermittency of rotations of the Lagrangian velocity vector.
Influence of electrode separation and gas curtain on extreme ultraviolet emission of a gas jet z-pinch source
Authors: Mohanty S. R. , Sakamoto T. , Kobayashi Y. , Izuka N. , Kishi N. , Song I. , Watanabe M. , Kawamura T. , Okino A. , Horioka K. , Hotta E.
Published: August 2006

Extreme ultraviolet (EUV) emission from a gas jet z-pinch source has been examined by employing a photodiode and pinhole camera. Visible images of the pinched plasma have been also recorded. A current pulse of 10kA is used to heat the gas jet, which emits radiation around 13.5nm. Experimental parameters such as electrode separation and gas flow rate are varied to optimize EUV emission. The maximum EUV energy is obtained for 12mm electrode separation and 20Torr xenon pressure and it is estimated to 10.95mJ∕sr per 2% bandwidth per pulse. The presence of gas curtain improves EUV emission by 30%.
Imaging of liquid crystals confined in carbon nanopipes
Authors: Shah Hemang J. , Fontecchio Adam K. , Rossi Maria Pia , Mattia Davide , Gogotsi Yury
Published: August 2006

This letter investigates the unexplored phenomenon of the wetting of liquid crystals inside carbon nanopipes. Carbon nanopipes are similar to carbon nanotubes but are open ended with straight walls. Using environmental scanning electron microscopy, the authors have observed liquid crystal menisci inside the nanopipes. Raman spectroscopy was used to confirm the presence of liquid crystals confined in the nanopipes and verify the physical interaction between the two materials. In addition, observations from reflection polarized optical microscopy experiments suggest the use of liquid crystals inside carbon nanotubes to develop electro-optic switches.
Hierarchical micro-/nanoscale domain structure in MC phase of (1−x)Pb(Mg1∕3Nb2∕3)O3–xPbTiO3 single crystal
Authors: Wang H. , Zhu J. , Lu N. , Bokov A. A. , Ye Z.-G. , Zhang X. W.
Published: August 2006

A hierarchical micro-/nanoscale domain structure is revealed in MC phase of (1−x)Pb(Mg1∕3Nb2∕3)O3–xPbTiO3 single crystal near the morphotropic phase boundary by combination of analytical electron microscopy and polarized light microscopy. The hierarchical domain structure is a self-assembling of nanodomains with tetragonal structure, submicrodomains appearing as monoclinic, and microdomains exhibiting the same monoclinic state due to an average effect. The outstanding piezoelectric properties may result from the cooperative response of the hierarchical micro-/nanoscale domain structure.
Formation of fivefold deformation twins in nanocrystalline face-centered-cubic copper based on molecular dynamics simulations
Authors: Cao A. J. , Wei Y. G.
Published: August 2006

Fivefold deformation twins were reported recently to be observed in the experiment of the nanocrystalline face-centered-cubic metals and alloys. However, they were not predicted previously based on the molecular dynamics (MD) simulations and the reason was thought to be a uniaxial tension considered in the simulations. In the present investigation, through introducing pretwins in grain regions, using the MD simulations, the authors predict out the fivefold deformation twins in the grain regions of the nanocrystal grain cell, which undergoes a uniaxial tension. It is shown in their simulation results that series of Shockley partial dislocations emitted from grain boundaries provide sequential twining mechanism, which results in fivefold deformation twins.
How much charge is there on a pulsating Taylor cone?
Authors: Marginean Ioan , Nemes Peter , Parvin Lida , Vertes Akos
Published: August 2006

The authors show that the capillary wave frequency spectrum of a charged droplet also gives an accurate estimate for the Taylor cone [Proc. R. Soc. London A 280, 383 (1964)] pulsation frequency. For low conductivity liquids and relatively large radius emitters, this frequency is mainly influenced by the anchoring radius at the emitter tip. For smaller tips the net amount of charge on the Taylor cone becomes increasingly significant. For example, the charge on pulsating Taylor cones with anchoring radii of 65 and 50μm increases from 57% to 74%, when expressed as a percentage of the Rayleigh limit [Philos. Mag. 14, 184 (1882)] of the corresponding droplets with the same radii.
In situ electrode manipulation for three terminal field emission characterization of individual carbon nanotubes
Authors: Smith R. C. , Carey J. D. , Cox D. C. , Silva S. R. P.
Published: August 2006

In situ three terminal electron field emission characterization of an isolated multiwalled carbon nanotube has been performed, where both anode and gate electrodes are attached to high precision piezodrivers. All measurements are performed in a scanning electron microscope allowing accurate knowledge of the local environment of the nanotube to be obtained. It is shown that the presence of the grounded gate electrode screens the applied field by approximately 32%. This technique in positioning the gate and anode electrodes allows for an estimate of the gate transparency factor and demonstrates characterization of individual carbon nanotubes without the need for fabrication of arrays of emitters.
Low-power magnetized microdischarge ion source
Authors: Ito Tsuyohito , Cappelli Mark A.
Published: August 2006

The authors report on the design and operation of a magnetized microdischarge ion source. The discharge is a coaxial (E×B) configuration with a closed-electron drift. Conditions are selected such that the ions are nonmagnetized and the electrons strongly magnetized. The operating characteristics of this ion source are studied in the 10–40W power range, generating a total ion current as high as 0.15A and a peak ion energy of ∼150eV at an operating voltage of 200V. The ionization efficiency approaches 100%, although the present design has a fairly large ion beam divergence (∼80° half-angle). The compact nature of this ion source is suitable for localized processing or can be easily clustered for multi-ion processing.
Lack of dependence of the Raman frequency of optical vibrational modes on excitation wavelength in polar nanosemiconductors
Authors: Zhang Shu-Lin , Zhang Yanbin , Liu Wei , Fu Zhengdong , Yan Yan , Chen Jing , Ma Rui , Song Yang , Zhao Jun , Xu Lv-Shun , Wu Songnan , Gao Min , Li Hongdong , Li Yadong , Yuan Fangli
Published: August 2006

A lack of dependence of the Raman frequency of optical vibrational modes on excitation wavelength in polar nanosemiconductors was observed. This is in contrast to the earlier observed dependence in nonpolar nanomaterials: carbon nanotubes and Si nanowires. This difference has been ascribed to the different crystallographic natures of their Raman spectra: crystalline for nonpolar and amorphous for polar nanosemiconductors. The result has been explored theoretically to the Raman spectra being insensitive to sample sizes and thus indicates that the size confinement effect, a basic effect in nanomaterials, does not exhibit in the optical vibrational modes of polar nanosemiconductors.
Folding field emission from GaN onto polymer microtip array by femtosecond pulsed laser deposition
Authors: Tong X. L. , Jiang D. S. , Li Y. , Liu Z. M. , Luo M. Z.
Published: August 2006

Microtip field-emitter array (FEA) has been formed using femtosecond pulsed laser deposited GaN thin film onto polymer microtip array. X-ray diffraction, scanning electronic microscope, and field emission measurements were carried out to analyze the profile, crystalline structures, and field emission properties of the emission array. The results indicate that the GaN thin film deposited on a like-conical-type polymer microtip array is hexagonal polycrystalline, and the GaN microtip FEA has uniform size, sharp tip, and well-defined profile, which shows a field emission characteristics.
Phosphate acquisition genes in
Prochlorococcus
ecotypes: Evidence for genome-wide adaptation
Authors: Martiny Adam C. , Coleman Maureen L. , Chisholm Sallie W.
Published: August 2006

The cyanobacterium
Prochlorococcus
is the numerically dominant phototroph in the oligotrophic oceans. This group consists of multiple ecotypes that are physiologically and phylogenetically distinct and occur in different abundances along environmental gradients. Here we examine adaptations to phosphate (P) limitation among ecotypes. First, we used DNA microarrays to identify genes involved in the P-starvation response in two strains belonging to different ecotypes, MED4 (high-light-adapted) and MIT9313 (low-light-adapted). Most of the up-regulated genes under P starvation were unique to one strain. In MIT9313, many ribosomal genes were down-regulated, suggesting a general stress response in this strain. We also observed major differences in regulation. The P-starvation-induced genes comprise two clusters on the chromosome, the first containing the P master regulator
phoB
and most known P-acquisition genes and the second, absent in MIT9313, containing genes of unknown function. We examined the organization of the
phoB
gene cluster in 11
Prochlorococcus
strains belonging to diverse ecotypes and found high variability in gene content that was not congruent with rRNA phylogeny. We hypothesize that this genome variability is related to differences in P availability in the oceans from which the strains were isolated. Analysis of a metagenomic library from the Sargasso Sea supports this hypothesis; most
Prochlorococcus
cells in this low-P environment contain the P-acquisition genes seen in MED4, although a number of previously undescribed gene combinations were observed.
Self‐Engagement Magnifies the Relationship Between Qualitative Overload and Performance in a Training Setting1
Authors: Britt Thomas W. , Thomas Jeffrey L. , Dawson Craig R.
Published: August 2006

The present study examined whether personal engagement in a leadership course would predict rated performance for the course, and whether qualitative overload would moderate the relationship. Participants were Army Reserve Officer Training Corps (ROTC) cadets participating in a 5‐week long leadership assessment course. Participants completed measures of qualitative overload (the extent to which they felt they lacked the skills and expertise required for effective performance) and the degree to which they were engaged in the course during the 4th week. Results revealed that course engagement was a significant predictor of rated leadership performance, even after controlling for the personality variable of conscientiousness. Course engagement interacted with qualitative overload to predict rated performance, indicating that qualitative overload was a stronger predictor of rated performance for those cadets engaged in the course. Discussion of the results focuses on engagement as a predictor of performance, and how work‐related impediments matter more for engaged individuals.
Adults Rule? Children, Advocacy and Complaints to Social Services
Authors: Pithouse Andrew , Crowley Anne
Published: August 2006

This article sets out results from a Welsh Assembly government‐funded study of complaints involving children and their use of advocacy services commissioned by local authorities in Wales. As this is the first study of its kind in Wales there is no baseline against which to compare the findings, hence we discuss the data in the context of a wider UK research literature and in relation to two key themes. These are (a) the number of complaints to social services involving children and the main characteristics of these complaints, particularly the involvement of an advocacy service and (b) the views of children about making a complaint and their experience of independent advocacy. The article reveals the adult‐dominated nature of the children's complaints system and the limited involvement of advocacy in supporting children who make a complaint. The pressing need for a more child‐focused approach that gives authentic voice to children and their rights is the key conclusion drawn from the evidence gathered in this study.
Stromal‐derived factor‐1 abolishes constitutive apoptosis of WHIM syndrome neutrophils harbouring a truncating CXCR4 mutation
Authors: Sanmun Duangmanee , Garwicz Daniel , Edvard Smith C. I. , Palmblad Jan , Fadeel Bengt
Published: August 2006

Warts, hypogammaglobulinaemia, infections, myelokathexis (WHIM) syndrome is an inherited immune disorder associated with CXCR4 gene mutations. Recent studies suggested that impaired receptor downregulation and enhanced chemotactic responsiveness to stromal‐derived factor‐1 (SDF‐1), the sole cognate ligand for CXCR4, may account for the characteristic features of WHIM patients. This study evaluated whether the interaction of SDF‐1 with CXCR4 could block constitutive apoptosis of peripheral blood neutrophils from congenital neutropenia patients and controls. SDF‐1 was found to be a potent anti‐apoptotic factor for WHIM neutrophils harbouring a truncating CXCR4 mutation, but not for neutrophils from control individuals, thus supporting the notion that such mutations may confer enhanced functional responses.
Outcomes among newborns with total serum Bilirubin levels of 25 mg per deciliter or more
Authors: Reading Richard
Published: August 2006

.
 
Newman, T.B.,
Liljestrand, P.,
Jeremy, R.J.,
Ferriero, D.M.,
Wu, Y.W.,
Hudes, E.S.,
Escobar, G.J.
,

(
2006
)

,
354
,
1889
–
1900
.

Background  The neurodevelopmental risks associated with high total serum bilirubin levels in newborns are not well defined.

Methods  We identified 140 infants with neonatal total serum bilirubin levels of at least 25 mg per deciliter (428 µmol per litre) and 419 randomly selected controls from a cohort of 106 627 term and near‐term infants born from 1995 to 1998 in Kaiser Permanente hospitals in northern California. Data on outcomes were obtained from electronic records, interviews, responses to questionnaires and neurodevelopmental evaluations that had been performed in a blinded fashion.

Results  Peak bilirubin levels were between 25 and 29.9 mg per deciliter (511 µmol per litre) in 130 of the newborns with hyperbilirubinemia and 30 mg per deciliter (513 µmol per litre) or more in 10 newborns; treatment involved phototherapy in 136 cases and exchange transfusion in five. Follow‐up data to the age of at least 2 years were available for 132 of 140 children with a history of hyperbilirubinemia (94%) and 372 of 419 controls (89%) and included formal evaluation at a mean (±SD) age of 5.1 ± 0.12 years for 82 children (59%) and 168 children (40%) respectively. There were no cases of kernicterus. Neither crude nor adjusted scores on cognitive tests differed significantly between the two groups; on most tests, 95% confidence intervals excluded a 3‐point (0.2 SD) decrease in adjusted scores in the hyperbilirubinemia group. There was no significant difference between groups in the proportion of children with abnormal neurologic findings on physical examination or with documented diagnoses of neurologic abnormalities. Fourteen of the children with hyperbilirubinemia (17%) had ‘questionable’ or abnormal findings on neurologic examination, as compared with 48 controls (29%; P = 0.05; adjusted odds ratio, 0.47; 95% confidence interval, 0.23–0.98; P = 0.04). The frequencies of parental concern and reported behavioural problems also were not significantly different between the two groups. Within the hyperbilirubinemia group, those with positive direct antiglobulin tests had lower scores on cognitive testing but not more neurologic or behavioural problems.

Conclusions  When treated with phototherapy or exchange transfusion, total serum bilirubin levels in the range included in this study were not associated with adverse neurodevelopmental outcomes in infants born at or near term.
Why is compliance with occlusion therapy for amblyopia so hard? A qualitative study
Authors: Reading Richard
Published: August 2006

.
 
Dixon‐Woods, M.,
Awan, M. &
Gottlob, I.
(
2006
)

,
91
,
491
–
494
.

Objective  To explore parents’ perceptions and experiences of occlusion (patching) therapy for treatment of amblyopia in children.

Methods  Qualitative study involving semi‐structured interviews with 25 families of a child with amblyopia being treated at a specialist clinic. Interviews were tape‐recorded and transcribed verbatim. Data analysis was based on the constant comparative method, assisted by qualitative analysis software.

Results  Parents of children prescribed patching treatment found themselves obliged to manage the treatment. This involved dilemmas and tensions, with many parents describing children’s distress, particularly in the early stages of patching treatment. Parents were highly sensitive to the credibility of the treatment, but were sometimes confused by information given in the clinic or did not see clinic staff as authoritative. There was evidence that parents were likely to abandon or modify treatment if no improvement could be detected or if the child continued to suffer socially or educationally. Parents described a range of strategies for facilitating patching, including explanation; normalization; rewards; customizing the patch; establishing a routine; and enlisting the help of others. Whatever their practices in relation to patching, parents were keen to defend their behaviour as that of a ‘good parent’.

Conclusions  Interventions that aim to improve compliance should take account of the difficulties and tensions experienced by parents, rather than simply treating non‐compliance as resulting from information deficits. Practical support that builds on strategies described by parents is likely to be of benefit.
Impact of adverse publicity on MMR vaccine uptake: a population based analysis of vaccine uptake records for one million children, born 1987–2004
Authors: Reading Richard
Published: August 2006

.
 
Friederichs, V.,
Cameron, J.C. &
Robertson, C.
(
2006
)

,
91
,
465
–
468
.

Aims  To determine the impact of adverse publicity on MMR uptake and measles susceptibility, including whether vaccination is delayed and the role of deprivation.

Methods  A population database for all Scotland containing immunization records for over one million children (n = 1 079 327) born 1987–2004 was analysed. MMR uptake was determined by birth cohort and deprivation category. ‘Final’ uptake (at approximately age 6 years) was predicted by linear regression by birth cohort. Measles susceptibility in 1998 and 2003 was determined by postcode sector and district for cohorts combined to construct nursery and primary school age groups.

Results  There is evidence of a slight rise in late uptake, but insufficient to compensate for underlying declines. Late vaccination continues to be associated with deprivation, while the most affluent tend to be vaccinated promptly, or not at all. Predicted figures for ‘final’ MMR1 uptake are over 90%, but under 95%. Measles susceptibility has increased significantly in nursery children, with an eightfold rise in the number of districts with greater than 20% susceptibility in this group (from 3 to 25).

Conclusions  Increased measles susceptibility in nursery children is concerning, particularly in the most vulnerable areas. These figures are likely to increase in the future, as MMR uptake has not yet returned to the previous higher level. Increased susceptibility levels can also be expected in primary schools in the future, as levels of late uptake are insufficient to compensate. Predicted figures for ‘final’ MMR1 uptake are under the herd immunity threshold and campaigns may be required to increase uptake among future primary school children.
Association of interferon-γ and interleukin 10 genotypes and serum levels with partial clinical remission in type 1 diabetes
Authors: Alizadeh B Z , Hanifi-Moghaddam P , Eerligh P , Van Der Slik A R , Kolb H , Kharagjitsingh A V , Arias A M Pereira , Ronkainen M , Knip M , Bonfanti R , Bonifacio E , Devendra D , Wilkin T , Giphart M J , Koeleman B P C , Nolsøe R , Poulsen T Mandrup , Schloot N C , Roep B O
Published: August 2006

We studied whether serum interferon (IFN)-γ or interleukin (IL)-10 levels and their corresponding functional polymorphic genotypes are associated with partial remission of type 1 diabetes (T1D). A multi-centre study was undertaken in patients with newly diagnosed T1D and matched controls. T1D patients were followed for 3 months and characterized for remission status. Partial clinical remission was defined as a daily insulin dose ≤ 0.38 units/kg/24 h with an HbA1c ≤ 7.5%. Thirty-three patients and 32 controls were phenotyped for serum concentrations of IFN-γ and IL-10 and genotyped for functional polymorphisms of the IFN-γ and IL-10 genes. Sixteen of 25 informative patients (63%) remitted. Serum IFN-γ concentrations were significantly decreased in remitters but increased in non-remitters compared to controls, and did not change over time in any group. IFN-γ genotypes corresponded with serum levels in controls and non-remitters, but not in remitters who displayed the lowest serum IFN-γ levels despite more often carrying high-producing IFN-γ genotypes. Neither the frequency of IL-10 genotypes nor serum IL-10 concentration differed between patients and controls. The combination of high-producing IFN-γ genotype together with low serum IFN-γ concentration at the time of diagnosis provided a strong positive predictive value for remission. Serum IFN-γ concentrations predicted by genotype and observed serum levels were discordant in remitters, suggestive of regulation overruling genetic predisposition. Although high-producing genotypes were less frequent in remitters, they were predictive of remission in combination with low serum IFN-γ levels. These data imply that remission is partially immune-mediated and involves regulation of IFN-γ transcription.
Severe endothelial dysfunction in young women with polycystic ovary syndrome is only partially explained by known cardiovascular risk factors
Authors: Sorensen Morten B. , Franks Stephen , Robertson Carole , Pennell Dudley J. , Collins Peter
Published: August 2006

Objective  We aimed to assess whether metabolic abnormalities can explain endothelial dysfunction and associated cardiovascular disease risk (CVDr) in polycystic ovary syndrome (PCOS). Endothelial function, a recognized composite marker of CVDr, may be reduced in PCOS and can be precisely and noninvasively assessed by cardiovascular magnetic resonance (CMR).

Patients  Fourteen women with anovulatory PCOS (age [mean ± SD] 33 ± 4 years) and 13 controls (age: 33 ± 6 years) with similar body mass index and regular menses.

Methods  Endothelium‐dependent (flow‐mediated dilatation – FMD) and ‐independent (glyceryl trinitrate – GTN) changes in the brachial artery area were measured using CMR in women with PCOS and controls. Arterial function was assessed twice, in the early follicular phase and mid cycle in controls and after an interval of 2 weeks in PCOS subjects. Fasting lipids, glucose, insulin and sex hormones were measured at the first visit.

Results  FMD was greatly reduced in women with PCOS compared to controls (−1%vs 5% and 2%vs 12%, P < 0·01) without differences in GTN responses. Risk factors were more prevalent in PCOS women and displayed significant linear relationships with FMD. PCOS status was the strongest predictor of FMD. Linear regression between PCOS and FMD remained significant after correction for all CVD risk markers linked to the metabolic syndrome.

Conclusion  PCOS is associated with changes in CVD risk markers and pronounced endothelial dysfunction. However endothelial dysfunction with PCOS is only partly explained by recognized CVD risk markers.
Visfatin concentration in Asian Indians is correlated with high density lipoprotein cholesterol and apolipoprotein A1
Authors: Smith Jessica , Al‐Amri Maha , Sniderman Allan , Cianflone Katherine
Published: August 2006

Background  Visfatin is a recently described adipose tissue derived hormone whose role in humans remains largely unknown.

Objectives  To determine visfatin's relationship to lipoproteins and body composition parameters in Asian Indians and Caucasians.

Design  A cross‐sectional study.

Patients  Men and women living in Montreal, Canada between the ages of 20 and 60 years were recruited for participation in this study. Subjects were excluded if they had a history of CVD or were taking lipid lowering medication. Individuals identified themselves as Asian Indian or Caucasian.

Measurements  Anthropometric measurements were collected including weight, height, waist circumference, hip circumference and body fat percentage (BF%). Serum samples were analysed for total cholesterol, HDL‐C, apoA1, apoB and visfatin.

Results  There was no difference in visfatin levels between Indian and Caucasian men (64·50 ± 3·98 ng/ml vs 73·01 ± 6·45 ng/ml, ns, respectively) and Indian and Caucasian women (59·03 ± 5·71 ng/ml vs 77·70 ± 7·63 ng/ml, ns, respectively), despite large differences in BF%, apoB and the apoB/apoA1 ratio. Visfatin correlated positively to HDL‐C and apoA1 in the Indian men (R = 0·42, P = 0·004 and R = 0·48, P = 0·003) and Indian women (R = 0·46, P = 0·05 and R = 0·59, P = 0·01).

Conclusion  Visfatin concentrations may be related to HDL metabolism in Asian Indian immigrants.
Dehydroepiandrosterone (DHEA) replacement reduces growth hormone (GH) dose requirement in female hypopituitary patients on GH replacement
Authors: Brooke Antonia M. , Kalingag Leonila A. , Miraki‐Moud Farideh , Camacho‐Hübner Cecilia , Maher Katharine T. , Walker Dorothy M. , Hinson Joy P. , Monson John P.
Published: August 2006

Objective  GH dose requirement is lower in ACTH replete compared with ACTH deficient hypopituitary patients suggesting that adrenal androgens may augment IGF‐I generation for a given GH dose. This study aimed to determine the effect of dehydroepiandrosterone (DHEA) administration on GH dose requirements in hypopituitary adults.

Design  A double blind placebo controlled trial was conducted adding 50 mg DHEA to the standard replacement of hypopituitary patients, including GH, over an initial 6 months, followed by an open phase study of 6 months DHEA replacement and a final 2 month washout phase after DHEA withdrawal. The dose of GH was adjusted to achieve a constant serum IGF‐I.

Patients  Thirty female and 21 male hypopituitary patients were enrolled. Data from 26 women and 18 men were analysed after patient withdrawal.

Measurements  The primary outcome objective was the GH dose required to achieve a stable serum IGF‐I. Secondary outcome measures were lipoprotein profiles, insulin, insulin sensitivity, IGFBP‐3, waist/hip ratio and indices of bone remodelling.

Results  DHEA replacement in female patients lead to a 14·6 ± 20% reduction in the dose of GH for a constant serum IGF‐I (P < 0·05, 95% CI: 1·8, 32·7). This was maintained for 12 months and there was a significant fall in serum IGF‐I two months after withdrawal of DHEA. There was no change in the male group.

Conclusions  DHEA replacement may reduce GH dose requirements in female hypopituitary patients.
Partial defects in transcriptional activity of two novel DAX‐1 mutations in childhood‐onset adrenal hypoplasia congenita
Authors: Laissue Paul , Copelli Silvia , Bergada Ignacio , Bergada Cesar , Barrio Gabriel , Karaboga Sinan , Wurtz Jean Marie , Fellous Marc , Lalli Enzo , Veitia Reiner A.
Published: August 2006

Objective  Mutations in DAX‐1, an X‐linked gene encoding an orphan nuclear receptor, have been associated with adrenal hypoplasia congenita and hypogonadotropic hypogonadism. Here we describe two novel DAX‐1 mutations, Y214X and I361T, associated with childhood‐onset primary adrenal failure. We aimed at analysing their effects on protein localization, transcriptional activity and propose a structural‐function relationship.

Design  We have directly sequenced the DAX‐1 gene from PCR‐amplified DNA. The effect of the mutations on protein localization was assessed by immunocytochemistry in transfected cells. The impact of mutations on transcriptional activity was determined by transfection using a StAR promoter‐luciferase reporter system.

Results  The mutation Y214X produces a protein lacking the C‐terminal half of DAX‐1. The other one, I361T, affects a highly conserved amino acid within the putative ligand‐binding domain. The mutant Y214X displayed a wild‐type subcellular localization while I361T was partially retained in the cytoplasm. Both mutants retained subtantial transcriptional repressive activity, compared to mutants producing early onset adrenal failure. Interestingly, I361T displayed similar in vitro transcriptional repressive activity to the mutant I439S previously described in a case of late‐onset AHC. This shows that molecular alterations of DAX‐1 leading to similar in vitro activities may result in very different ages of onset of adrenal failure, which suggests that additional genetic and epigenetic factors are important in determining the clinical course of AHC.

Conclusions  Our results help the understanding of structure–function relationships in the DAX‐1 molecule, suggesting that the N‐terminal domain is relatively autonomous and add credence to presumed molecular interactions within ligand binding domain of the protein.
Antithrombotic action of annexin V proved as efficient as direct inhibition of tissue factor or thrombin
Authors: Galán A. M. , Van Heerde W. L. , Escolar G. , Ordinas A. , Sixma J. , De Groot P. G.
Published: August 2006

Background  The role of phospholipid platelet membrane and tissue factor in thrombin generation and thrombus formation is accepted. In the present study we have explored antithrombotic action of strategies aimed to block exposure of negatively charged phospholipids and we compared effects with those obtained through tissue factor or a direct thrombin inhibition.

Materials and methods  Type III collagen was exposed to flowing blood (5 min, 300 s−1). Effects of inhibition of platelet deposition by annexin A5 (ANXA5), hirudin (HIR) or by an antibody against tissue factor (TF) were evaluated. Prothrombin fragment F1 + 2 (F1 + 2) was monitored.

Results  Pre‐incubation of whole blood with HIR or ANXA5 resulted in a statistically significant reduction of platelet deposition (12·2 ± 0·6% in control experiments vs. 8·3 ± 0·4% and 8·5 ± 0·5%, respectively, P < 0·05). A similar decrease was found when blood was incubated with an antibody against TF. Furthermore, ANXA5 and HIR inhibited the recruitment of platelets into forming aggregates. The height of platelet aggregates generated was decreased in the presence of HIR or ANXA5, but only incubation with both inhibitors reached levels of statistical significance. The presence of ANXA5 or HIR decreased levels of F1 + 2 suggesting a reduced activation of the coagulation system.

Conclusions  In our experimental studies, the inhibitory potential of ANXA5 on platelet‐thrombus formation was as effective as that of a direct thrombin inhibitor, as HIR, or an antibody against TF. Negatively charged phospholipids exposed on activated platelets potentiate the formation of platelet aggregates on a collagen surface and further suggest that inhibition of platelet procoagulant activity might be a specific target for antithrombotic drugs.
High‐density lipoprotein apolipoprotein A‐I kinetics: comparison of radioactive and stable isotope studies
Authors: Ooi E. M. M. , Watts G. F. , Farvid M. S. , Chan D. C. , Allen M. C. , Zilko S. R. , Barrett P. H. R.
Published: August 2006

Background  To compare the kinetic determinants of high‐density lipoprotein (HDL) apolipoprotein A‐I (apoA‐I) concentration in lean normolipidaemic subjects using radioisotope and stable isotope studies.

Materials and methods  We pooled data from 16 radioisotope and 13 stable isotope studies to investigate the kinetics of apoA‐I in lean normolipidemic individuals. We also examined the associations of HDL kinetic parameters with age, sex, body mass index (BMI) and concentrations of apoA‐I, triglycerides, HDL cholesterol and low‐density lipoprotein (LDL) cholesterol.

Results  Lean subjects from radioisotope and stable isotope studies were matched for age, gender, BMI and lipid profile. The apoA‐I concentration was significantly lower in the radioisotope group than the stable isotope group (P = 0·031). There was no significant difference in HDL apoA‐I fractional catabolic rate (FCR) and production rate (PR) between the groups. In the radioisotope group, HDL apoA‐I FCR was significantly associated with apoA‐I and HDL cholesterol concentrations (r = −0·681, P < 0·001 and r = −0·542, P < 0·001, respectively), whereas in the stable isotope group, only HDL apoA‐I PR was significantly associated with apoA‐I concentration (r = 0·455, P = 0·004).

Conclusions  Our findings suggest that HDL apoA‐I FCR is the primary determinant of apoA‐I concentrations in lean subjects in studies using radiotracer techniques. By contrast, HDL apoA‐I PR is the primary determinant of apoA‐I concentration in lean subject in studies employing stable isotope methods. These discrepancies may be reconciled by differences in methodologies and/or study population characteristics.