bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistical mechanics of protein allostery: Roles of backbone and side-chain structural fluctuations
Authors: Itoh Kazuhito , Sasai Masaki
Published: March 2011

A statistical mechanical model of allosteric transition of proteins is developed by extending the structure-based model of protein folding to cases that a protein has two different native conformations. Partition function is calculated exactly within the model and free-energy surfaces associated with allostery are derived. In this paper, the model of allosteric transition proposed in a previous paper [Proc. Natl. Acad. Sci. U.S.A 134, 7775 (2010)] is reformulated to describe both fluctuation in side-chain configurations and that in backbone structures in a balanced way. The model is applied to example proteins, Ras, calmodulin, and CheY: Ras undergoes the allosteric transition between guanosine diphosphate (GDP)-bound and guanosine triphosphate (GTP)-bound forms, and the model results show that the GDP-bound form is stabilized enough to prevent unnecessary signal transmission, but the conformation in the GTP-bound state bears large fluctuation in side-chain configurations, which may help to bind multiple target proteins for multiple pathways of signaling. The calculated results of calmodulin show the scenario of sequential ordering in Ca2 + binding and the associated allosteric conformational change, which are realized though the sequential appearing of pre-existing structural fluctuations, i.e., fluctuations to show structures suitable to bind Ca2 + before its binding. Here, the pre-existing fluctuations to accept the second and third Ca2 + ions are dominated by the side-chain fluctuation. In CheY, the calculated side-chain fluctuation of Tyr106 is coordinated with the backbone structural change in the β4–α4 loop, which explains the pre-existing Y–T coupling process in this protein. Ability of the model to explain allosteric transitions of example proteins supports the view that the large entropic effects lower the free-energy barrier of allosteric transition.
Photoluminescence investigation of high quality GaAs1−xBix on GaAs
Authors: Mohmad A. R. , Bastiman F. , Ng J. S. , Sweeney S. J. , David J. P. R.
Published: March 2011

Photoluminescence (PL) of GaAs0.97Bi0.03 alloy was measured over a wide range of temperatures and excitation powers. Room temperature PL with peak wavelength of 1038 nm and full-width-half-maximum of 75 meV was observed which is relatively low for this composition. The improved quality is believed due to reduced alloy fluctuations by growing at relatively high temperature. The temperature dependence of PL peak energy indicated significant exciton localization at low temperatures. Furthermore, the band gap temperature dependence was found to be weaker than GaAs. An analysis of dominant carrier recombination mechanism(s) was also carried out indicating that radiative recombination is dominant at low temperature.
A new class of sum rules for products of Bessel functions
Authors: Bevilacqua G. , Biancalana V. , Dancheva Y. , Mansour T. , Moi L.
Published: March 2011

We derive a new class of sum rules for products of Bessel functions of the first kind. Using standard algebraic manipulations we extend some of the well known properties of Jn. Some physical applications of the results are also discussed. A comparison with the Newberger [B. S. Newberger, J. Math. Phys. 52, 1278 (1982)] sum rules is performed on a typical example.
Absence of vapor-liquid-solid growth during molecular beam epitaxy of self-induced InAs nanowires on Si
Authors: Hertenberger S. , Rudolph D. , Bolte S. , Döblinger M. , Bichler M. , Spirkoska D. , Finley J. J. , Abstreiter G. , Koblmüller G.
Published: March 2011

The growth mechanism of self-induced InAs nanowires (NWs) grown on Si (111) by molecular beam epitaxy was investigated by in situ reflection high energy electron diffraction and ex situ scanning and transmission electron microscopy. Abrupt morphology transition and in-plane strain relaxation revealed that InAs NWs nucleate without any significant delay and under the absence of indium (In) droplets. These findings are independent of the As/In-flux ratio, revealing entirely linear vertical growth rate and nontapered NWs. No evidence of In droplets nor associated change in the NW apex morphology was observed for various growth termination procedures. These results highlight the absence of vapor-liquid-solid growth, providing substantial benefits for realization of atomically abrupt doping and composition profiles in future axial InAs-based NW heterostructures on Si.
Structure and magnetic properties of three-dimensional (La,Sr)MnO3 nanofilms on ZnO nanorod arrays
Authors: Gao Haiyong , Staruch M. , Jain Menka , Gao Pu-Xian , Shimpi Paresh , Guo Yanbing , Cai Wenjie , Lin Hui-jan
Published: March 2011

Three-dimensional (3D) cubic perovskite (La,Sr)MnO3 (LSMO) nanofilms have been deposited on ZnO nanorod arrays with controlled dimensionality and crystallinity by radio frequency (rf) magnetron sputtering and post thermal annealing. Compared to the two-dimensional (2D) LSMO nanofilm on flat Si, the structure and magnetic properties of 3D LSMO nanofilms on ZnO nanorod arrays have a strong anisotropic morphology and thickness dependence. Ferromagnetic property has been observed in both 2D and 3D LSMO nanofilms while a ferromagnetic–superparamagnetic transition was revaled in 3D LSMO nanofilms on ZnO nanorod array with decreasing nanofilm thickness, due to a large surface dispersion effect. The LSMO/ZnO nanofilm/nanorod structures could open up new avenues for intriguing magnetic properties studies and applications of nanoscale perovskites.
Switching energy-delay of all spin logic devices
Authors: Behin-Aein Behtash , Sarkar Angik , Srinivasan Srikant , Datta Supriyo
Published: March 2011

A recent proposal called all spin logic (ASL) proposes to store information in nanomagnets that communicate with spin currents in order to construct spin based digital circuits. We present a coupled magnetodynamics/spin-transport model for ASL devices that is based on established physics and is benchmarked against available experimental data. This model is used to show the linear dependence of switching energy and quadratic dependence of energy-delay of ASL devices on the number of Bohr magnetons comprising a nanomagnet. A scaling scheme that could lower the energy-delay of spin-torque switching while maintaining thermal stability is discussed.
Wall-loss distribution of charge breeding ions in an electron cyclotron resonance ion source
Authors: Jeong S. C. , Oyaizu M. , Imai N. , Hirayama Y. , Ishiyama H. , Miyatake H. , Niki K. , Okada M. , Watanabe Y. X. , Otokawa Y. , Osa A. , Ichikawa S.
Published: March 2011

The ion loss distribution in an electron cyclotron resonance ion source (ECRIS) was investigated to understand the element dependence of the charge breeding efficiency in an electron cyclotron resonance (ECR) charge breeder. The radioactive 111In1+ and 140Xe1+ ions (typical nonvolatile and volatile elements, respectively) were injected into the ECR charge breeder at the Tokai Radioactive Ion Accelerator Complex to breed their charge states. Their respective residual activities on the sidewall of the cylindrical plasma chamber of the source were measured after charge breeding as functions of the azimuthal angle and longitudinal position and two-dimensional distributions of ions lost during charge breeding in the ECRIS were obtained. These distributions had different azimuthal symmetries. The origins of these different azimuthal symmetries are qualitatively discussed by analyzing the differences and similarities in the observed wall-loss patterns. The implications for improving the charge breeding efficiencies of nonvolatile elements in ECR charge breeders are described. The similarities represent universal ion loss characteristics in an ECR charge breeder, which are different from the loss patterns of electrons on the ECRIS wall.
Low-voltage ZnO thin-film transistors based on Y2O3 and Al2O3 high-k dielectrics deposited by spray pyrolysis in air
Authors: Adamopoulos George , Thomas Stuart , Bradley Donal D. C. , McLachlan Martyn A. , Anthopoulos Thomas D.
Published: March 2011

We report the application of ambient spray pyrolysis for the deposition of high-k polycrystalline Y2O3 and amorphous Al2O3 dielectrics and their use in low-voltage ZnO thin-film transistors. The films are studied by means of atomic force microscopy, UV-visible absorption spectroscopy, impedance spectroscopy, and field-effect measurements. ZnO transistors based on spray pyrolysed Y2O3 and Al2O3 dielectrics show low leakage currents, and hysteresis-free operation with a maximum electron mobility of 34 cm2/V s and current on/off ratio on the order of 105. This work is a significant step toward high-performance oxide electronics manufactured using simple and scalable processing methods.
Interdiffusion and barrier layer formation in thermally evaporated Mn/Cu heterostructures on SiO2 substrates
Authors: Lozano J. G. , Lozano-Perez S. , Bogan J. , Wang Y. C. , Brennan B. , Nellist P. D. , Hughes G.
Published: March 2011

Mn/Cu heterostructures thermally evaporated onto SiO2 and, subsequently, annealed were investigated by transmission electron microscopy related techniques in order to study the diffusion interactions which lead to barrier layer formation. Energy dispersive x-ray spectroscopy and electron energy loss spectroscopy provide evidence for the interdiffusion between the Mn and Cu layers following a 450 °C anneal, where the Mn diffuses toward the surface of the structure, while Cu diffuses toward the Mn/SiO2 but does not propagate into the dielectric. The chemical composition of the 2–3 nm interfacial layer is primarily a mixture of +2 and +3 Mn valences, in good agreement with previously reported results.
The effect of ionization on the global minima of small and medium sized silicon and magnesium clusters
Authors: De Sandip , Ghasemi S. Alireza , Willand Alexander , Genovese Luigi , Kanhere Dilip , Goedecker Stefan
Published: March 2011

We re-examine the question of whether the geometrical ground state of neutral and ionized clusters are identical. Using a well defined criterion for being “identical” together, the extensive sampling methods on a potential energy surface calculated by density functional theory, we show that the ground states are in general different. This behavior is to be expected whenever there are metastable configurations which are close in energy to the ground state, but it disagrees with previous studies.
Stability and evolution of low-surface-tension metal catalyzed growth of silicon nanowires
Authors: Yu Linwei , Fortuna Franck , O’Donnell Benedict , Patriache Gilles , Roca i Cabarrocas Pere
Published: March 2011

Low-surface-tension metals were predicted to be insufficient to catalyze the growth of silicon nanowires (SiNWs) in vapor-liquid-solid (VLS) mode while counter examples do exist, for example, in the tin- or indium-catalyzed SiNWs. This puzzle remains largely unresolved. We first examine the local tension-force-balance in a tin-catalyzed SiNW by using a cross-section analysis. We found that the existence of an ultrathin sidewall-spreading catalyst layer helps to stabilize the catalyst drop during growth. The predicted contact-angle evolution, by an energetic balance model, is also supported by the experimental data. These results bring critical understanding on the low-surface-tension catalyzed VLS process.
Enhanced electrocaloric effect in ferroelectric poly(vinylidene-fluoride/trifluoroethylene) 55/45 mol % copolymer at ferroelectric-paraelectric transition
Authors: Lu S. G. , Rožič B. , Zhang Q. M. , Kutnjak Z. , Neese Bret
Published: March 2011

The electrocaloric effect (ECE) of the ferroelectric poly(vinylidene-fluoride/trifluoroethylene) 55/45 mol % copolymer was directly measured over a broad temperature range using a specially designed calorimetry method. The data reveal a large ECE occurring at the ferroelectric-paraelectric (FE–PE) phase transition where an adiabatic temperature change ∼12 °C was induced under a field of 120 MV/m, which is much higher than that previously observed at above the FE–PE transition. The directly measured ECE also confirms the earlier results deduced from the indirect method. The experimental data also show that there are secondary effects contributing to the observed ECE in the polymer.
Nanostructured carbon films with oriented graphitic planes
Authors: Teo E. H. T. , Kulik J. , Kauffmann Y. , Kalish R. , Lifshitz Y.
Published: March 2011

Nanostructured carbon films with oriented graphitic planes can be deposited by applying energetic carbon bombardment. The present work shows the possibility of structuring graphitic planes perpendicular to the substrate in following two distinct ways: (i) applying sufficiently large carbon energies for deposition at room temperature (E>10 keV), (ii) utilizing much lower energies for deposition at elevated substrate temperatures (T>200 °C). High resolution transmission electron microscopy is used to probe the graphitic planes. The alignment achieved at elevated temperatures does not depend on the deposition angle. The data provides insight into the mechanisms leading to the growth of oriented graphitic planes under different conditions.
First principles prediction of a morphotropic phase boundary in the Bi(Zn1/2Ti1/2)O3−(Bi1/2Sr1/2)(Zn1/2Nb1/2)O3 alloy
Authors: Cooper Valentino R. , Henry Asegun S. , Takagi Shigeyuki , Singh David J.
Published: March 2011

The magnitude and direction of polarization within alloys of the tetragonally distorted Bi(Zn1/2Ti1/2)O3 (BZT) and the rhombohedrally oriented (Bi1/2Sr1/2)(Zn1/2Nb1/2)O3 are explored using density functional theory. For compositions with ≥50% of BZT, we find that the polarization is mainly in the [001] direction. Conversely, for low concentrations of BZT the polarization is rhombohedrally oriented. Based on these results we propose a phase diagram with a monoclinic phase that appears when the BZT concentration is roughly 50%. At this concentration, the material may have a useful piezoelectric response.
Tunable electronic transport properties of DyScO3/SrTiO3 polar heterointerface
Authors: Li D. F. , Wang Yan , Dai J. Y.
Published: March 2011

Electronic transport properties of DyScO3/SrTiO3 polar heterointerface grown at different oxygen pressures are studied. This DyScO3/SrTiO3 polar heterointerface exhibits much higher charge mobility, up to 104 cm2 V−1 s−1, compared to the LaAlO3/SrTiO3 system due to relatively lower lattice mismatch between the film and substrate. More significantly, the DyScO3 film deposited under 10−4 mbar oxygen pressure presents an interfacial metal-to-semiconductor conducting mechanism transition at 90 K. Field effect transport measurement results reveal that this transition can be modulated by field effect through controlling the electron doping level of the interface originated from interfacial electronic reconstruction.
Strain-induced –π transition in a zigzag graphene nanoribbon Josephson junction
Authors: Zou Jianfei , Jin Guojun
Published: March 2011

We study theoretically the supercurrent through a superconductor/ferromagnetic zigzag graphene nanoribbon/superconductor junction by the Matsubara Green function method. The transformation of the supercurrent between the 0 and π states is remarkably realized in this Josephson junction by the combination of the uniaxial strain and gate-controlled barrier potential. Such strain-induced 0–π transition is found to result from the dependence of the effective Fermi velocity on the uniaxial strain in the graphene nanoribbon modulated by mechanical approaches.
Guided Bloch surface wave polaritons
Authors: Liscidini Marco , Gerace Dario , Sanvitto Daniele , Bajoni Daniele
Published: March 2011

The authors report on a theoretical investigation of guided polariton states arising from the strong coupling between quantum-well excitons and a Bloch surface wave confined at the interface between a uniform dielectric medium and a Bragg mirror. It is shown that the exciton–photon coupling is almost doubled as compared to a similar structure made in a conventional planar microcavity. It is also shown that, by simple engineering of the sample surface with silicon oxide deposition, one can efficiently produce one-dimensional polaritons propagating within the structure with extremely low losses. The latter result evidences the usefulness of Bloch surface waves as a key component for the realization of “polaritonic integrated circuits.”
Estimating the age structure of a population of brushtail possums (Trichosurus vulpecula) by comparing tooth wear and cementum lines
Authors: Lohr Cheryl A. , Esmaili Tammy , Mills Harriet , Bencini Roberta
Published: March 2011

We used cementum lines from a sample of possums to calibrate tooth wear patterns in free-ranging common brushtail possums (Trichosurus vulpecula) to estimate of the age structure of a wild population of the species living at the Perth Zoo, Western Australia. We assessed patterns of tooth wear and incremental cementum lines in teeth extracted from 40 possums via necropsy. Rank regression for non-parametric data revealed a weak relationship between the number of cementum lines per tooth (y), which was assumed to correspond to the age of the possums (in years), and tooth wear (males: age = 0.51x + 3.4, r2 = 0.098, n = 27; females: age = 1.17x + 0.35, r2 = 0.345, n = 45). We used these relationships and the tooth wear pattern of 149 live possums caught at Perth Zoo to develop an estimate of the age structure of the population. Most (63.1%) possums were between 4 and 6 years of age. Very few young (1–2 years) or old (6–8 years) possums were caught at Perth Zoo. These results yielded an approximate age distribution for possums within Perth Zoo and should be used with caution because the relationship between the number of cementum lines and tooth wear was weak.
Using canopy bridges to link habitat for arboreal mammals: successful trials in the Wet Tropics of Queensland
Authors: Weston Nigel , Goosem Miriam , Marsh Helene , Cohen Martin , Wilson Robyn
Published: March 2011

We investigated the use of inexpensive aerial bridges (rope canopy bridges) above roads and a highway by arboreal mammals in the Wet Tropics of Queensland, Australia. Three rope bridge designs were trialed, including a single rope, ladder-like bridges and tunnel-shaped bridges. Nine mammal species were recorded using canopy bridges, including five species or subspecies endemic to the Wet Tropics and three species listed as rare under State nature conservation legislation. Most of these species suffer severely from either the fragmentation or mortality impacts caused by roads. Over 50 crossings above a 15-m-wide tourist road were observed on an elevated ladder-like bridge. Longer (~40 m) rope bridges were used on several occasions by four species. Our observations suggest that canopy bridges can assist rare arboreal mammals to cross roads in the Wet Tropics, thereby reducing both the risk of road-kill and the potential for subpopulation isolation. Further research is required to ascertain the level of benefit afforded by canopy bridges for arboreal mammal populations. It is likely that rope canopy bridges will have broad application for a range of arboreal mammal species.
Making connections between ultrafast protein folding kinetics and molecular dynamics simulations
Authors: Cellmer Troy , Buscaglia Marco , Henry Eric R. , Hofrichter James , Eaton William A.
Published: March 2011

Determining the rate of forming the truly folded conformation of ultrafast folding proteins is an important issue for both experiments and simulations. The double-norleucine mutant of the 35-residue villin subdomain is the focus of recent computer simulations with atomistic molecular dynamics because it is currently the fastest folding protein. The folding kinetics of this protein have been measured in laser temperature-jump experiments using tryptophan fluorescence as a probe of overall folding. The conclusion from the simulations, however, is that the rate determined by fluorescence is significantly larger than the rate of overall folding. We have therefore employed an independent experimental method to determine the folding rate. The decay of the tryptophan triplet-state in photoselection experiments was used to monitor the change in the unfolded population for a sequence of the villin subdomain with one amino acid difference from that of the laser temperature-jump experiments, but with almost identical equilibrium properties. Folding times obtained in a two-state analysis of the results from the two methods at denaturant concentrations varying from 1.5–6.0 M guanidinium chloride are in excellent agreement, with an average difference of only 20%. Polynomial extrapolation of all the data to zero denaturant yields a folding time of 220 (+100,-70) ns at 283 K, suggesting that under these conditions the barrier between folded and unfolded states has effectively disappeared—the so-called “downhill scenario.”
On the strong and selective isotope effect in the UV excitation of N
2
with implications toward the nebula and Martian atmosphere
Authors: Muskatel B. H. , Remacle F. , Thiemens Mark H. , Levine R. D.
Published: March 2011

Isotopic effects associated with molecular absorption are discussed with reference to natural phenomena including early solar system processes, Titan and terrestrial atmospheric chemistry, and Martian atmospheric evolution. Quantification of the physicochemical aspects of the excitation and dissociation processes may lead to enhanced understanding of these environments. Here we examine a physical basis for an additional isotope effect during photolysis of molecular nitrogen due to the coupling of valence and Rydberg excited states. The origin of this isotope effect is shown to be the coupling of diabatic electronic states of different bonding nature that occurs after the excitation of these states. This coupling is characteristic of energy regimes where two or more excited states are nearly crossing or osculating. A signature of the resultant isotope effect is a window of rapid variation in the otherwise smooth distribution of oscillator strengths vs. frequency. The reference for the discussion is the numerical solution of the time dependent Schrödinger equation for both the electronic and nuclear modes with the light field included as part of the Hamiltonian. Pumping is to all extreme UV dipole-allowed, valence and Rydberg, excited states of N
2
. The computed absorption spectra are convoluted with the solar spectrum to demonstrate the importance of including this isotope effect in planetary, interstellar molecular cloud, and nebular photochemical models. It is suggested that accidental resonance with strong discrete lines in the solar spectrum such as the CIII line at 97.703 nm can also have a marked effect.
Gender stereotypes in management: A comparative study of communist and postcommunist Romania
Authors: Curşeu Petru Lucian , Boroş Smaranda
Published: March 2011

This study sets out to investigate the changes in the perception of women in leading positions in communist and postcommunist Romania. The study uses a noninvasive paradigm of analyzing the content of obituaries for women and men in leading positions published in a national journal, and shows that the gender gap in management widened during the postcommunist period. In postcommunist Romania, women are perceived as being less able to lead/manage and more relational in their leadership style as compared to men, while in the communist period the gender differences were not significant.
Changes of attachment status among women with personality disorders undergoing inpatient treatment
Authors: Strauss Bernhard M. , Mestel Robert , Kirchmann Helmut A.
Published: March 2011

Background: Attachment has increasingly received attention in psychotherapy and has been used as a predictor of process and outcome. Studies investigating changes of attachment styles during psychotherapy are very rare. Method: Forty women with either borderline (BPD) or avoidant personality disorders (AVPD), treated as inpatients, were investigated using an attachment interview (interpersonal relations assessment (IRA)), and questionnaires to determine therapy outcome at the beginning and after seven weeks of therapy. The IRA uses similar questions as the adult attachment interview (AAI) and is used as the basis for the adult attachment prototype rating (AAPR), a procedure to assign individuals to prototypical categories of attachment. Results: The study showed that the therapy in general was effective. In contrast to other studies, we did not find many women classified as secure at the end of their therapy. Comparisons of pre‐post‐ratings revealed instead that clients within both subgroups received higher ratings for the avoidant prototypes at the end of therapy, indicating deactivation of attachment. Changes from ambivalent to avoidant attachment were linked with better outcome among women with borderline personality disorder (BPD). Conclusions: This study adds further evidence to the result that attachment styles do not change dramatically during a time‐limited psychological treatment of personality disorder. Instead, the study showed that features of preoccupied/ambivalent attachment were less significant after seven weeks of therapy. For women with BPD, these changes were linked with a more favourable outcome which might reflect a more structured and deactivated attachment status as a result of inpatient therapy.
Mechanisms, Laws, and Regularities
Authors: Andersen Holly K.
Published: March 2011

Leuridan argued that mechanisms cannot provide a genuine alternative to laws of nature as a model of explanation in the sciences, and he advocates Mitchell's pragmatic account of laws. I first demonstrate that Leuridan gets the order of priority wrong among mechanisms, regularity, and laws, and then make some clarifying remarks about how laws and mechanisms relate to regularities. Mechanisms are not an explanatory alternative to regularities; they are an alternative to laws. The existence of stable regularities in nature is necessary for either model of explanation: regularities are what laws describe and what mechanisms explain.
Szilard's Perpetuum Mobile
Authors: Hemmo Meir , Shenker Orly
Published: March 2011

In a previous article, we have demonstrated by a general phase space argument that a Maxwellian Demon is compatible with statistical mechanics. In this article, we show how this idea can be put to work in the prevalent model of the Demon, namely, a particle-in-a-box, used, for example, by Szilard and Bennett. In the literature, this model is used in order to show that a Demon is incompatible with statistical mechanics, either classical or quantum. However, we show that a detailed phase space analysis of this model illustrates that a Maxwellian Demon is compatible with statistical mechanics.
Plasma kinetics in ethanol/water/air mixture in a ‘tornado’-type electrical discharge
Authors: Levko D , Shchedrin A , Chernyak V , Olszewski S , Nedybaliuk O
Published: March 2011

This paper presents the results of a theoretical and experimental study of plasma-assisted reforming of ethanol into molecular hydrogen in a modified ‘tornado’-type electrical discharge. Numerical modelling clarifies the nature of non-thermal conversion and explains the kinetic mechanism of non-equilibrium plasma chemical transformations in the gas–liquid system and the evolution of hydrogen during the reforming as a function of discharge parameters and ethanol-to-water ratio in the mixture. We also propose a scheme of chemical reactions for plasma kinetics description. It is shown that some characteristics of the investigated reactor are at least not inferior to the characteristics of other plasma chemical reactors.
Silicon sub-micron-gap deep trench Pirani vacuum gauge for operation at atmospheric pressure
Authors: Kubota Masanori , Mita Yoshio , Sugiyama Masakazu
Published: March 2011

The operation of a bulk micromachined Pirani vacuum gauge at atmospheric pressure is demonstrated. The device is fabricated on a silicon-on-insulator (SOI) wafer with a 5 µm thick device layer by using a one-mask, deep etching process. The 250 nm wide vertical gap fabricated by the deep etching of silicon has made operation at atmospheric pressure possible. The pressure range dependence on the change in the length of the heater and the length of the gap is discussed. Further, the performance dependence on different gaps is measured using 1.5 µm and 5.5 µm wide gaps. Measurement from 4 to 101 300 Pa is performed, and high sensitivity from 1000 to 101 300 Pa is confirmed.
Regularity theory for parabolic nonlinear integral operators
Authors: Caffarelli Luis , Chan Chi Hin , Vasseur Alexis
Published: March 2011

This article is dedicated to the regularity theory for solutions to a class of nonlinear integral variational problems. Those problems are involved in nonlocal image and signal processing.
Management of Button Battery–induced Hemorrhage in Children
Authors: Brumbaugh David E , Colson Steven B , Sandoval John A , Karrer Frederick M , Bealer John F , Litovitz Toby , Kramer Robert E
Published: March 2011

Objectives:

Button battery ingestions are potentially life threatening for children. Catastrophic and fatal injuries can occur when the battery becomes lodged in the esophagus, where battery‐induced injury can extend beyond the esophagus to the trachea or aorta. Increased production of larger, more powerful button batteries has coincided with more frequent reporting of fatal hemorrhage secondary to esophageal battery impaction, but no recommendations exist for the management of button battery–induced hemorrhage in children.

Materials and Methods:

We reviewed all of the reported pediatric fatalities due to button battery–associated hemorrhage. Our institution engaged subspecialists from a wide range of disciplines to develop an institutional plan for the management of complicated button battery ingestions.

Results:

Ten fatal cases of button battery–associated hemorrhage were identified. Seven of the 10 cases have occurred since 2004. Seventy percent of cases presented with a sentinel bleeding event. Fatal hemorrhage can occur up to 18 days after endoscopic removal of the battery. Guidelines for the management of button battery–associated hemorrhage were developed.

Conclusions:

Pediatric care facilities must be prepared to act quickly and concertedly in the case of button battery–associated esophageal hemorrhage, which is most likely to present as a “sentinel bleed” in a toddler.
Effect of Age on Fructose Malabsorption in Children Presenting With Gastrointestinal Symptoms
Authors: Jones Hilary F , Burt Esther , Dowling Kate , Davidson Geoff , Brooks Doug A , Butler Ross N
Published: March 2011

Objectives:

Fructose malabsorption can produce symptoms such as chronic diarrhoea and abdominal pain. Here, we retrospectively review breath hydrogen test (BHT) results to determine whether age has an effect on the clinical application of the fructose BHT and compare this with the lactose BHT.

Patients and Methods:

Patients were referred to a gastroenterology breath‐testing clinic (2003–2008) to investigate carbohydrate malabsorption as a cause of gastrointestinal symptoms. Patients received either 0.5 g/kg body weight of fructose (maximum of 10 g) or 2 g/kg of lactose (maximum of 20 g), in water, and were tested for 2.5 hours.

Results:

Patient age showed a significant effect on the fructose BHT results (P < 0.001, 0.1–79 years old, n = 1093). The odds of testing positive for fructose malabsorption in paediatric patients (15 years old or younger, n = 760) decreased by a factor of 0.82/year (95% confidence interval 0.79–0.86, P < 0.001). There were 88.2% positive in younger than 1‐year‐olds, 66.6% in 1‐ to 5‐year‐olds, 40.4% in 6‐ to 10‐year‐olds, and 27.1% in 10‐ to 15‐year‐olds. In contrast, 39.3% of lactose BHTs were positive, with no significant relation between patient age and test result (P = 0.115, 0.1–89 years old, n = 3073).

Conclusions:

The majority of infants with gastrointestinal symptoms exhibited fructose malabsorption, but the capacity to absorb fructose increased with patient age up to 10 years old. The low threshold for fructose absorption in younger children has significant implications for the performance and interpretation of the fructose BHT and for the dietary consumption of fructose in infants with gastrointestinal symptoms.
Cisapride Improves Enteral Tolerance in Pediatric Short‐bowel Syndrome With Dysmotility
Authors: Raphael Bram P , Nurko Samuel , Jiang Hongyu , Hart Kristen , Kamin Daniel S , Jaksic Tom , Duggan Christopher
Published: March 2011

Background and Objectives:

Gastrointestinal dysmotility is common in pediatric short‐bowel syndrome, leading to prolonged parenteral nutrition dependence. There is limited literature regarding the safety and efficacy of cisapride for this indication. The aim of the study was to describe the safety and efficacy of cisapride for enteral intolerance in pediatric short‐bowel syndrome.

Methods:

Open‐labeled pilot study in a limited access program for cisapride. Indications were short‐bowel syndrome with underlying dysmotility and difficulty advancing enteral feeds despite standard therapies and without evidence of anatomic obstruction. Patients received cisapride 0.1 to 0.2 mg/kg per dose for 3 to 4 doses per day. We collected electrocardiogram, nutrition, and anthropometric data prospectively at study visits.

Results:

Ten patients with mean (SD) age of 30.3 (30.5) months were enrolled in our multidisciplinary pediatric intestinal rehabilitation program. Median (interquartile range [IQR]) duration of follow‐up was 8.7 (3.1–14.3) months. Median (IQR) residual bowel length was 102 (85–130) cm. Median (IQR) citrulline level was 14.5 (10.5–31.3) μmol/L. Diagnoses included isolated gastroschisis (n = 3), gastroschisis with intestinal atresia (n = 4), necrotizing enterocolitis (n = 2), and long‐segment Hirschsprung disease (n = 1). Six subjects had at least 1 prior bowel‐lengthening procedure. Median (IQR) change in percentage enteral energy intake was 19.9% (15.4%–29.8%) during follow‐up (P = 0.01). Seven patients improved in enteral tolerance during treatment and 2 were weaned completely from parenteral nutrition. Complications during therapy were prolonged corrected QT interval (n = 2), gastrointestinal bleeding (n = 2), D‐lactic acidosis (n = 1), and death due to presumed sepsis (n = 1). Longitudinal analysis (general estimating equation model) showed a strong positive association between cisapride duration and improved enteral tolerance. Mean percentage of enteral intake increased by 2.9% for every month of cisapride treatment (P < 0.0001).

Conclusions:

Cisapride is a potentially useful therapy in patients with pediatric short‐bowel syndrome with gastrointestinal dysmotility. We observed modest improvement in feeding tolerance where prior treatments failed; however, patients treated with cisapride require careful cardiac monitoring because corrected QT prolongation occurred in 20% of our cohort.
Do Children and Adolescents With Type 1 Diabetes Mellitus Have a Higher Frequency of Parietal Cell Antibodies Than Healthy Controls?
Authors: Fröhlich‐Reiterer Elke E , Huber Julia , Katz Hermann , Suppan Elisabeth , Obermayer‐Pietsch Barbara , Deutschmann Andrea , Demel Ulrike , Acham‐Roschitz Birgit , Weinhandl Gudrun , Ambros‐Rudolph Christina M , Hauer Almuth , Borkenstein Martin H
Published: March 2011

Objectives:

Parietal cell antibodies (PCA) are markers of autoimmune gastritis (AG). AG can lead to hypergastrinemia and iron‐deficiency anaemia (IDA). Compared to healthy controls, adults with type 1 diabetes mellitus (T1DM) show a higher prevalence of PCA (1% vs 20%). The aim of the present study was to evaluate the frequency of PCA in children and adolescents with T1DM compared to healthy controls and the clinical and biochemical markers.

Patients and Methods:

We studied 170 patients (87 boys) with T1DM (mean age 12.9 years) and 101 healthy controls (49 boys; mean age 13.0 years). PCA, free T4, free T3, thyroid‐stimulating hormone (TSH), and thyroid antibodies were measured in all of the patients. In addition, gastrin, pepsinogen I, iron, ferritin, vitamin B12, and folate were measured in patients with T1DM only. Gastroscopy was carried out in patients with T1DM having high (>100 U/mL) PCA levels.

Results:

The frequency of PCA in patients with T1DM was 5.29% compared to 1.98% in healthy controls (not significant). PCA was strongly correlated to both thyroid peroxidase antibodies (TPOAb) and gastrin levels (P = 0.001). IDA was present in 4 of 9 patients from the PCA‐positive group compared to 4 of 160 patients from the PCA‐negative group. Hypergastrinemia was found in 2 PCA‐positive patients. Histopathologically, 1 of 4 patients showed early symptoms of AG.

Conclusions:

Children and adolescents with T1DM have a lower frequency of PCA than is reported for adults. Compared to healthy controls, they seem to be at increased risk for developing PCA, in particular if positive for TPOAb, but overt clinical disease is rare in children with T1DM.
A sterol C-14 reductase encoded by FgERG24B is responsible for the intrinsic resistance of Fusarium graminearum to amine fungicides
Authors: Liu Xin , Fu Jing , Yun Yingzi , Yin Yanni , Ma Zhonghua
Published: March 2011

Fusarium graminearum, the causal agent of wheat head blight, shows intrinsic resistance to amine fungicides. It is commonly accepted that the amines target sterol C-14 reductase and sterol Δ8–Δ7isomerase of ergosterol biosynthesis, encoded by the genesERG24andERG2, respectively. Analysis of the genome sequence ofF. graminearumrevealed that the fungus contains two paralogousFgERG24genes (FgERG24AandFgERG24B), which are homologous to theERG24ofSaccharomyces cerevisiae. In this study, we disruptedFgERG24AandFgERG24BinF. graminearum. Compared to the wild-type strain HN9-1,FgERG24AandFgERG24Bdeletion mutants did not show recognizable phenotypic changes in mycelial growth on potato dextrose agar or in virulence on wheat heads. HPLC analysis showed that the amount of ergosterol inFgERG24AorFgERG24Bdeletion mutants was not significantly different from that in the wild-type strain. These results indicate that neither of the two genes is essential for growth, pathogenicity or ergosterol biosynthesis inF. graminearum.FgERG24Bdeletion mutants exhibited significantly increased sensitivity to amine fungicides, including tridemorph, fenpropidin and spiroxamine, but not to non-amine fungicides. In contrast,FgERG24Adeletion mutants did not show changed sensitivity to any amine tested. The resistance of theFgERG24Bdeletion mutant to amines was restored by genetic complementation of the mutant with wild-typeFgERG24B. These results indicate thatFgERG24Bcontrols the intrinsic resistance ofF. graminearumto amines. The finding of this study provides new insights into amine resistance in filamentous fungi.
Fragile X mental retardation protein regulates heterosynaptic plasticity in the hippocampus
Authors: Connor Steven A. , Hoeffer Charles A. , Klann Eric , Nguyen Peter V.
Published: March 2011

Silencing of a single gene, FMR1, is linked to a highly prevalent form of mental retardation, characterized by social and cognitive impairments, known as fragile X syndrome (FXS). The FMR1 gene encodes fragile X mental retardation protein (FMRP), which negatively regulates translation. Knockout of Fmr1 in mice results in enhanced long-term depression (LTD) induced by metabotropic glutamate receptor (mGluR) activation. Despite the evidence implicating FMRP in LTD, the role of FMRP in long-term potentiation (LTP) is less clear. Synaptic strength can be augmented heterosynaptically through the generation and sequestration of plasticity-related proteins, in a cell-wide manner. If heterosynaptic plasticity is altered in Fmr1 knockout (KO) mice, this may explain the cognitive deficits associated with FXS. We induced homosynaptic plasticity using the β-adrenergic receptor (β-AR) agonist, isoproterenol (ISO), which facilitated heterosynaptic LTP that was enhanced in Fmr1 KO mice relative to wild-type (WT) controls. To determine if enhanced heterosynaptic LTP in Fmr1 KO mouse hippocampus requires protein synthesis, we applied a translation inhibitor, emetine (EME). EME blocked homo- and heterosynaptic LTP in both genotypes. We also probed the roles of mTOR and ERK in boosting heterosynaptic LTP in Fmr1 KO mice. Although heterosynaptic LTP was blocked in both WT and KOs by inhibitors of mTOR and ERK, homosynaptic LTP was still enhanced following mTOR inhibition in slices from Fmr1 KO mice. Because mTOR will normally stimulate translation initiation, our results suggest that β-AR stimulation paired with derepression of translation results in enhanced heterosynaptic plasticity.
Randomized controlled trials in pregnancy: scientific and ethical aspects. Exposure to different opioid medications during pregnancy in an intra‐individual comparison
Authors: Unger Annemarie , Jagsch Reinhold , Jones Hendree , Arria Amelia , Leitich Harald , Rohrmeister Klaudia , Aschauer Constantin , Winklbaur Berndadette , Bäwert Andjela , Fischer Gabriele
Published: March 2011

Background  Chronic medical conditions such as opioid dependence require evidence‐based treatment recommendations. However, pregnant women are under‐represented in clinical trials. We describe the first within‐subject comparison of maternal and neonatal outcomes for methadone‐ versus buprenorphine‐exposed pregnancies. Although methadone is the established treatment of pregnant opioid‐dependent women, recent investigations have shown a trend for a milder neonatal abstinence syndrome (NAS) under buprenorphine. However, it is not only the choice of maintenance medication that determines the occurrence of NAS; other factors such as maternal metabolism, illicit substance abuse and nicotine consumption also influence its severity and duration and represent confounding factors in the assessment of randomized clinical trials.

Case series description  Three women who were part of the European cohort of a randomized, double‐blind multi‐center trial with a contingency management tool [the Maternal Opioid Treatment: Human Experimental Research (MOTHER) study], each had two consecutive pregnancies and were maintained on either methadone or buprenorphine for their first and then the respective opposite, still‐blinded medication for their second pregnancy. Birth measurements, the total neonatal abstinence score, the total amounts of medication used to treat NAS and the days of NAS treatment duration were assessed.

Results  Both medications were effective and safe in reducing illicit opioid relapse and avoiding preterm labor. Methadone maintenance yielded to a significantly higher neonatal birth weight. Data patterns suggest that buprenorphine exposure was associated with lower neonatal abstinence syndrome (NAS) scores. Findings from this unique case series are consistent with earlier reports using between‐group analyses.

Conclusions  Buprenorphine has the potential to become an established treatment alternative to methadone for pregnant opioid‐dependent women. Under special consideration of ethical boundaries, psychopharmacological treatment during pregnancy must be addressed as an integral part of clinical research projects in order to optimize treatment for women and neonates.
Is ideal body image related to obesity and lifestyle behaviours in African American adolescents?
Authors: Chen X. , Wang Y.
Published: March 2011

Background  Childhood obesity epidemic has become a public health issue in the USA, especially among African American youths. Research on the association between ideal body image (IBI) and obesity and related lifestyle factors among African American children and adolescents is limited.

Methods  Data collected from 402 low‐income African American adolescents aged 10–14 years in four Chicago public schools were used. Questionnaires were used to assess IBI, weight perception, weight control practices, and self‐efficacy towards food and physical activity. Body mass index was calculated using measured weight and height. Associations between IBI and weight perception, overweight/obesity and lifestyle behaviours were assessed using linear and logistic regression models.

Results  The most frequently chosen ideal body size was the fourth of eight silhouettes (from thinnest to heaviest) for boys (55%) and girls (49%). Overweight and obese girls selected larger ideal body figures than the others (trend test: P < 0.001). Compared with those with middle ideal body figures, girls who selected smaller ones were twice as likely to have an unhealthy diet as indicated by less fruit and milk consumption; the odds ratios (ORs) and 95% confidence intervals (95% CIs) were 2.40 (1.15–5.02) for fruits intake (<once/week) and 2.13 (1.06–4.29) for milk consumption (<once/day), respectively. Boys with larger IBI were less likely to eat snack often [≥once/day; OR = 0.11 (0.02–0.50)]. Girls with larger IBI were less likely to spend more screen time [OR = 0.12 (0.02–0.70)] and reported better food choice intentions (P < 0.05). Overweight and obese boys and girls appeared to have better food choice intentions and food self‐efficacy than their non‐overweight peers (trend test: both P < 0.01).

Conclusions  Ideal body image is associated with weight status, food self‐efficacy and lifestyle behaviours among low‐income African American adolescents.
Eosinophilic oesophagitis: latest intelligence
Authors: Schoepfer A. M. , Simon D. , Straumann A.
Published: March 2011

Eosinophilic oesophagitis (EoE), first described in the early 1990s, has rapidly evolved as a distinctive chronic inflammatory oesophageal disease with increasing incidence and prevalence in the westernized countries. Currently, EoE represents the main cause of dysphagia in adult patients. This disease is more prevalent in males and is frequently associated with allergies. The diagnosis is established based on the presence of oesophageal symptoms and dense eosinophilic oesophageal infiltration once other conditions leading to oesophageal eosinophilia are excluded. It is currently under discussion to what extent and by which methods allergic testing should be performed. Topical corticosteroids lead to a rapid improvement of active EoE clinically and histologically. Especially in children, elimination diets can have similar efficacy as topical corticosteroids. Oesophageal dilation of EoE‐induced oesophageal strictures can also be effective in improving symptoms, but this therapy has no effect on the underlying inflammation. Neither the diagnostic nor the long‐term therapeutic strategies are as yet defined.

Cite this as: A. M. Schoepfer, D. Simon and A. Straumann, Clinical & Experimental Allergy, 2011 (41) 630–639.