bluuebunny/crossref_metadata_2025 huggingface dataset:
Self-organized ZnO nanodot arrays: Effective control using SiNx interlayers and low-temperature plasmas
Authors: Huang S. Y. , Cheng Q. J. , Xu S. , Wei D. Y. , Zhou H. P. , Long J. D. , Levchenko I. , Ostrikov K.
Published: February 2012

An advanced inductively coupled plasma (ICP)-assisted rf magnetron sputtering deposition method is developed to synthesize regular arrays of pear-shaped ZnO nanodots on a thin SiNx buffer layer pre-deposited onto a silicon substrate. It is shown that the growth of ZnO nanodots obey the cubic root-law behavior. It is also shown that the synthesized ZnO nanodots are highly-uniform, controllable by the experimental parameters, and also feature good structural and photoluminescent properties. These results suggest that this custom-designed ICP-based technique is very effective and highly-promising for the synthesis of property- and size-controllable highly-uniform ZnO nanodots suitable for next-generation light emitting diodes, energy storage, UV nanolasers, and other applications.
Ground-state cooling of a mechanical resonator by single- and two-phonon processes
Authors: Zhu Jia-pei , Li Gao-xiang
Published: February 2012

A scheme for ground-state cooling of a mechanical resonator by single- and two-phonon processes is analyzed. The mechanical resonator is coupled to two coupled quantum dots forming an effective Λ-type three-level structure and connected with two normal metal leads. The quantum dots are driven by two light fields; by choosing appropriate parameters, the electron can be trapped in the dark state of the system, a superposition of the two ground states. When the single-phonon absorption and emission processes are dominant, under the weak (strong) driving field circumstances, the mechanical resonator is cooled through absorbing a phonon when the electron jumps from dark state to bright state (one of the dressed states) and then tunnels out of the two coupled dots. Net cooling of the resonator to its ground state is possible in the absence of the electron-phonon dephasing via single-phonon processes. When the two-phonon processes are tuned to be stronger than the single-phonon processes, the mechanical resonator can be cooled to its nonclassical state.
Non-contact thrust stand calibration method for repetitively pulsed electric thrusters
Authors: Wong Andrea R. , Toftul Alexandra , Polzin Kurt A. , Pearson J. Boise
Published: February 2012

A thrust stand calibration technique for use in testing repetitively pulsed electric thrusters for in-space propulsion has been developed and tested using a modified hanging pendulum thrust stand. In the implementation of this technique, current pulses are applied to a solenoid to produce a pulsed magnetic field that acts against a permanent magnet mounted to the thrust stand pendulum arm. The force on the magnet is applied in this non-contact manner, with the entire pulsed force transferred to the pendulum arm through a piezoelectric force transducer to provide a time-accurate force measurement. Modeling of the pendulum arm dynamics reveals that after an initial transient in thrust stand motion the quasi-steady average deflection of the thrust stand arm away from the unforced or “zero” position can be related to the average applied force through a simple linear Hooke's law relationship. Modeling demonstrates that this technique is universally applicable except when the pulsing period is increased to the point where it approaches the period of natural thrust stand motion. Calibration data were obtained using a modified hanging pendulum thrust stand previously used for steady-state thrust measurements. Data were obtained for varying impulse bit at constant pulse frequency and for varying pulse frequency. The two data sets exhibit excellent quantitative agreement with each other. The overall error on the linear regression fit used to determine the calibration coefficient was roughly 1%.
Effectiveness of frequency mapping on 28 nm device broken scan chain failures
Authors: Goh S. H. , Pan Yan , You G. F. , Chan Y. H. , ran He , Herrman Thomas , Heller Thomas , Lim Victor S. K. , Mai Z. H. , Lam Jeffrey , Chua C. M. , Chua W. P. , Tan S. H.
Published: February 2012

Frequency mapping methodology is an effective diagnostic tool for detection of manufacturing defects in scan chains. It analyses reflected laser modulations from toggling scan cells to localize defective scan path or scan cell. In this paper, we demonstrate experimentally that the use of solid immersion lens technology to enhance signal and spatial resolution is not a prerequisite for this technique up till 28 nm technology node. We present case studies to show the effectiveness of frequency mapping for detecting systematic and random broken scan chain failures on a 28 nm technology node test chip. We achieved 81% success rate in this methodology.
Study of instabilities and transitions for a family of quasi-two-dimensional magnetohydrodynamic flows based on a parametrical model
Authors: Smolentsev S. , Vetcha N. , Moreau R.
Published: February 2012

In this study, flow phenomena associated with inflectional and boundary-layer instabilities, as well as a mixed instability mode in quasi-two-dimensional magnetohydrodynamic flows in a rectangular duct are accessed with the help of a parametrical model, where the basic velocity profile with near-wall jets and associated points of inflection are produced by imposing an external flow-opposing force. By varying this force, various instability modes and transition scenarios are reproduced. First, linear stability analysis is performed and then nonlinear effects are studied using direct numerical simulation for Hartmann numbers 100 and 200 and Reynolds numbers from 1800 to 5000. A special attention is paid to the location of the inflection point with respect to the duct wall. A more complex flow dynamics, including various vortex-wall and vortex-vortex interactions, and even negative turbulence production are observed and analyzed as the inflection point approaches the wall. The analysis of obtained results and their comparison with relevant data for magnetohydrodynamic duct flows gain an insight into what is typically called “jet instability,” including linear and nonlinear mechanisms.
Oxygen vacancy segregation and space-charge effects in grain boundaries of dry and hydrated BaZrO3
Authors: Joakim Nyman B. , Helgee Edit E. , Wahnström Göran
Published: February 2012

A space-charge model is applied to describe the equilibrium effects of segregation of double-donor oxygen vacancies to grain boundaries in dry and wet acceptor-doped samples of the perovskite oxide BaZrO3. The grain boundary (GB) core vacancy concentrations and electrostatic potential barriers resulting from different vacancy segregation energies were evaluated. Density-functional calculations on vacancy segregation to the mirror-symmetric Σ3 (112) [1¯10] tilt grain boundary are also presented. Our results indicate that oxygen vacancy segregation can be responsible for the low grain boundary proton conductivity in BaZrO3 reported in the literature.
Growth and piezo-/ferroelectric properties of PIN-PMN-PT single crystals
Authors: Li Xiuzhi , Wang Zujian , He Chao , Long Xifa , Ye Zuo-Guang
Published: February 2012

Ternary solid solution crystals of 0.19Pb(In1/2Nb1/2)O3− 0.46Pb(Mg1/3Nb2/3)O3− 0.35PbTiO3 [PIMNT(19/46/35)] with dimensions of 35 × 38 × 15 mm3 were grown by the top-seeded solution growth (TSSG) method. The dielectric, piezo- and ferroelectric properties of the grown crystals were characterized. The ternary piezocrystals exhibit a Curie temperature TC = 190 °C and a tetragonal-rhombohedral phase transition temperature TR-T = 130 °C, which are increased significantly compared with TC ≈ 155 °C and TR-T ≈ 80 °C of PMN-PT crystals. The dielectric constant (ɛ′) and dielectric loss tangent (tan δ) are 4300 and 0.40 at room temperature. The piezoelectric coefficient d33 is found to be 2380 pC/N. The longitudinal electromechanical coupling factor k33 reaches 90% at room temperature. A peak-to-peak bipolar strain value of 0.13% is obtained at E ≈ ± 14 kV/cm. The coercive field Ec and remanent polarization Pr are 5.50 kV/cm and 27.10 μC/cm2, respectively, which are also improved from the vales of PMN-PT crystals.
The sign problem and population dynamics in the full configuration interaction quantum Monte Carlo method
Authors: Spencer J. S. , Blunt N. S. , Foulkes W. M.C.
Published: February 2012

The recently proposed full configuration interaction quantum Monte Carlo method allows access to essentially exact ground-state energies of systems of interacting fermions substantially larger than previously tractable without knowledge of the nodal structure of the ground-state wave function. We investigate the nature of the sign problem in this method and how its severity depends on the system studied. We explain how cancellation of the positive and negative particles sampling the wave function ensures convergence to a stochastic representation of the many-fermion ground state and accounts for the characteristic population dynamics observed in simulations.
Measurement of ion and electron temperatures in plasma blobs by using an improved ion sensitive probe system and statistical analysis methods
Authors: Okazaki K. , Tanaka H. , Ohno N. , Ezumi N. , Tsuji Y. , Kajita S.
Published: February 2012

We have measured ion temperature as well as electron temperature in plasma blobs observed in a linear plasma device by using an improved ion sensitive probe. Current–voltage characteristics of the ion sensitive probe inside and outside plasma blobs were re-constructed with a conditional sampling method. It is clearly found that both ion and electron temperatures in plasma blobs decrease more slowly in a cross-field direction than those in a bulk plasma without plasma blobs.
Sound velocity measurements of tantalum under shock compression in the 10-110 GPa range
Authors: Hu Jianbo , Dai Chengda , Yu Yuying , Liu Zijiang , Tan Ye , Zhou Xianming , Tan Hua , Cai Lingcang , Wu Qiang
Published: February 2012

The high-pressure melting curve of tantalum (Ta) has been the center of a long-standing controversy. Sound velocities along the Hugoniot curve are expected to help in understanding this issue. To that end, we employed a direct-reverse impact technique and velocity interferometry to determine sound velocities of Ta under shock compression in the 10-110 GPa pressure range. The measured longitudinal sound velocities show an obvious kink at ∼60 GPa as a function of shock pressure, while the bulk sound velocities show no discontinuity. Such observation could result from a structural transformation associated with a negligible volume change or an electronic topological transition.
Improved chopping of a lithium beam for plasma edge diagnostic at ASDEX Upgrade
Authors: Willensdorfer M. , Wolfrum E. , Fischer R. , Schweinzer J. , Sertoli M. , Sieglin B. , Veres G. , Aumayr F. ,   the ASDEX Upgrade Team
Published: February 2012

The lithium beam diagnostic at ASDEX Upgrade routinely delivers electron density profiles in the plasma edge by lithium beam impact excitation spectroscopy. An accurate background subtraction requires a periodically chopped lithium beam. A new, improved chopping system was developed and installed. It involves a voltage modulation for the extractor electrode and the beam deflection plates. The modulation of the extractor electrode reduces the unused portion of lithium ions and improves the stability of the beam with respect to its position. Furthermore, the data indicate an extended emitter lifetime. The extractor chopping was also found to be insensitive to sparks. The deflection chopping experiments demonstrated beam chopping in the kilohertz range. The significantly higher modulation frequency of the deflection chopping improves background subtraction of fast transient events. It allows a more accurate density measurements in the scrape off layer during impurity injections and edge localized modes.
Broadband ferromagnetic resonance spectroscopy of permalloy triangular nanorings
Authors: Ding J. , Kostylev M. , Adeyeye A. O.
Published: February 2012

We investigate the spin dynamics in triangular shaped permalloy rings using broadband ferromagnetic resonance spectroscopy. Compared with circular rings, we observed multiple resonance frequency peaks, which are strongly dependent on the orientation of the applied magnetic field relative to the horizontal edge of rings, displaying six-fold anisotropy. We validated our experimental results using modified Kittel equation [C. Kittel, Phys. Rev. 73, 155 (1948)] and dynamic micromagnetic simulations which show good agreement.
The multi-configuration electron-nuclear dynamics method applied to LiH
Authors: Ulusoy Inga S. , Nest Mathias
Published: February 2012

The multi-configuration electron-nuclear dynamics (MCEND) method is a nonadiabatic quantum dynamics approach to the description of molecular processes. MCEND is a combination of the multi-configuration time-dependent Hartree (MCTDH) method for atoms and its antisymmetrized equivalent MCTDHF for electrons. The purpose of this method is to simultaneously describe nuclear and electronic wave packets in a quantum dynamical way, without the need to calculate potential energy surfaces and diabatic coupling functions. In this paper we present first exemplary calculations of MCEND applied to the LiH molecule, and discuss computational and numerical details of our implementation.
Nonadiabatic dynamics of O(1D) + N2$( {X{}^1\Sigma _g^ + } )\rightarrow $(XΣg+1)→O(3P) + N2$ ( {X{}^1\Sigma _g^ + } )$(XΣg+1) on three coupled potential surfaces: Symmetry, Coriolis, spin-orbit, and Renner-Teller effects
Authors: Defazio Paolo , Gamallo Pablo , Petrongolo Carlo
Published: February 2012

We present the spin-orbit (SO) and Renner-Teller (RT) quantum dynamics of the spin-forbidden quenching O(1D) + N2$( {X{}^1\Sigma _g^ + } ) \to$(XΣg+1)→O(3P) + N2$( {X{}^1\Sigma _g^ + } )$(XΣg+1) on the N2O $\tilde X{}^1A^{\prime }$X̃A′1, $\tilde a{}^3A^{\prime\prime}$ãA″3, and $\tilde b{}^3A^{\prime }$b̃A′3 coupled PESs. We use the permutation-inversion symmetry, propagate coupled-channel (CC) real wavepackets, and compute initial-state-resolved probabilities and cross sections $\sigma _{j_0 }$σj0 for the ground vibrational and the first two rotational states of N2, j0 = 0 and 1. Labeling symmetry angular states by j and K, we report selection rules for j and for the minimum K value associated with any electronic state, showing that $\tilde a{}^3A^{\prime\prime}$ãA″3 is uncoupled in the centrifugal-sudden (CS) approximation at j0 = 0. The dynamics is resonance-dominated, the probabilities are larger at low K, $\sigma _{j_0 }$σj0 decrease with the collision energy and increase with j0, and the CS σ0 is lower than the CC one. The nonadiabatic interactions play different roles on the quenching dynamics, because the $\tilde X{}^1A^ {\prime } - \tilde b{}^3A^ {\prime }$X̃A′1−b̃A′3 SO effects are those most important while the $\tilde a{}^3A^{\prime\prime} - \tilde b{}^3A ^{\prime }$ãA″3−b̃A′3 RT ones are negligible.
Ultrafast resonance-enhanced multiphoton ionization in the azabenzenes: Pyridine, pyridazine, pyrimidine, and pyrazine
Authors: Scarborough Timothy D. , Foote David B. , Uiterwaal Cornelis J. G. J.
Published: February 2012

We report on the ultrafast photoionization of pyridine, pyridazine, pyrimidine, and pyrazine. These four molecules represent a systematic series of perturbations into the structure of a benzene ring which explores the substitution of a C–H entity with a nitrogen atom, creating a heterocyclic structure. Data are recorded under intense-field, single-molecule conditions. The pulses (50 fs, 800 nm) are focused into the molecular vapor, and ion mass spectra are recorded for intensities of ∼1013 W/cm2 to ∼1015 W/cm2. We measure ion yields in the absence of the focal volume effect without the need for deconvolution of the data. For all targets, stable singly- and doubly-charged parent ions (C6-nH6-nNn+(+)) are observed with features suggesting resonance-enhanced ionization. From the intensity dependence of the ion yield, we infer that excitation occurs both through 1ππ* transitions (remnants of the benzene structure) and through 1nπ* transitions, the latter being a result of Rydberg-like excitations of the lone pair electrons of the nitrogen atoms. Stability against intense-field fragmentation is also discussed.
Cold collisions of complex polyatomic molecules
Authors: Li Zhiying , Heller Eric J.
Published: February 2012

We introduce a method for classical trajectory calculations to simulate collisions between atoms and large rigid asymmetric-top molecules. We investigate the formation of molecule-helium complexes in buffer-gas cooling experiments at a temperature of 6.5 K for molecules as large as naphthalene. Our calculations show that the mean lifetime of the naphthalene-helium quasi-bound collision complex is not long enough for the formation of stable clusters under the experimental conditions. Our results suggest that it may be possible to improve the efficiency of the production of cold molecules in buffer-gas cooling experiments by increasing the density of helium. In addition, we find that the shape of molecules is important for the collision dynamics when the vibrational motion of molecules is frozen. For some molecules, it is even more crucial than the number of accessible degrees of freedom. This indicates that by selecting molecules with suitable shape for buffer-gas cooling, it may be possible to cool molecules with a very large number of degrees of freedom.
Role of retroviral restriction factors in the interferon-α–mediated suppression of HIV-1 in vivo
Authors: Pillai Satish K. , Abdel-Mohsen Mohamed , Guatelli John , Skasko Mark , Monto Alexander , Fujimoto Katsuya , Yukl Steven , Greene Warner C. , Kovari Helen , Rauch Andri , Fellay Jacques , Battegay Manuel , Hirschel Bernard , Witteck Andrea , Bernasconi Enos , Ledergerber Bruno , Günthard Huldrych F. , Wong Joseph K. ,   the Swiss HIV Cohort Study, Barth J , Battegay M , Bernasconi E , Böni J , Bucher HC , Burton-Jeangros C , Calmy A , Cavassini M , Cellerai C , Egger M , Elzi L , Fehr J , Fellay J , Flepp M , Francioli P , Furrer H , Fux CA , Gorgievski M , Günthard H , Haerry D , Hasse B , Hirsch HH , Hirschel B , Hösli I , Kahlert C , Kaiser L , Keiser O , Kind C , Klimkait T , Kovari H , Ledergerber B , Martinetti G , Martinez de Tejada B , Metzner K , Müller N , Nadal D , Pantaleo G , Rauch A , Regenass S , Rickenbach M , Rudin C , Schmid P , Schultze D , Schöni-Affolter F , Schüpbach J , Speck R , Taffé P , Tarr P , Telenti A , Trkola A , Vernazza P , Weber R , Yerly S
Published: February 2012

The antiviral potency of the cytokine IFN-α has been long appreciated but remains poorly understood. A number of studies have suggested that induction of the apolipoprotein B mRNA editing enzyme, catalytic polypeptide 3 (APOBEC3) and bone marrow stromal cell antigen 2 (BST-2/tetherin/CD317) retroviral restriction factors underlies the IFN-α–mediated suppression of HIV-1 replication in vitro. We sought to characterize the as-yet-undefined relationship between IFN-α treatment, retroviral restriction factors, and HIV-1 in vivo. APOBEC3G, APOBEC3F, and BST-2 expression levels were measured in HIV/hepatitis C virus (HCV)-coinfected, antiretroviral therapy-naïve individuals before, during, and after pegylated IFN-α/ribavirin (IFN-α/riba) combination therapy. IFN-α/riba therapy decreased HIV-1 viral load by −0.921 (±0.858) log
10
copies/mL in HIV/HCV-coinfected patients. APOBEC3G/3F and BST-2 mRNA expression was significantly elevated during IFN-α/riba treatment in patient-derived CD4+ T cells (
P
< 0.04 and
P
< 0.008, paired Wilcoxon), and extent of BST-2 induction was correlated with reduction in HIV-1 viral load during treatment (
P
< 0.05, Pearson's
r
). APOBEC3 induction during treatment was correlated with degree of viral hypermutation (
P
< 0.03, Spearman's ρ), and evolution of the HIV-1 accessory protein viral protein U (Vpu) during IFN-α/riba treatment was suggestive of increased BST-2–mediated selection pressure. These data suggest that host restriction factors play a critical role in the antiretroviral capacity of IFN-α in vivo, and warrant investigation into therapeutic strategies that specifically enhance the expression of these intrinsic immune factors in HIV-1–infected individuals.
Inactivation of androgen-induced regulator ARD1 inhibits androgen receptor acetylation and prostate tumorigenesis
Authors: Wang Zehua , Wang Zemin , Guo Jianhui , Li Yingchun , Bavarva Jasmin H. , Qian Chiping , Brahimi-Horn M. Christiane , Tan Deyong , Liu Wanguo
Published: February 2012

Androgen signaling through androgen receptor (AR) is critical for prostate tumorigenesis. Given that AR-mediated gene regulation is enhanced by AR coregulators, inactivation of those coregulators is emerging as a promising therapy for prostate cancer (PCa). Here, we show that the
N
-acetyltransferase arrest-defect 1 protein (ARD1) functions as a unique AR regulator in PCa cells. ARD1 is up-regulated in human PCa cell lines and primary tumor biopsies. The expression of ARD1 was augmented by treatment with synthetic androgen (R1881) unless AR is deficient or is inhibited by AR-specific siRNA or androgen inhibitor bicalutamide (Casodex). Depletion of ARD1 by shRNA suppressed PCa cell proliferation, anchorage-independent growth, and xenograft tumor formation in SCID mice, suggesting that AR-dependent ARD1 expression is biologically germane. Notably, ARD1 was critical for transcriptionally regulating a number of AR target genes that are involved in prostate tumorigenesis. Furthermore, ARD1 interacted physically with and acetylated the AR protein in vivo and in vitro. Because AR–ARD1 interaction facilitated the AR binding to its targeted promoters for gene transcription, we propose that ARD1 functions as a unique AR regulator and forms a positive feedback loop for AR-dependent prostate tumorigenesis. Disruption of AR–ARD1 interactions may be a potent intervention for androgen-dependent PCa therapy.
Formation and release of arrestin domain-containing protein 1-mediated microvesicles (ARMMs) at plasma membrane by recruitment of TSG101 protein
Authors: Nabhan Joseph F. , Hu Ruoxi , Oh Raymond S. , Cohen Stanley N. , Lu Quan
Published: February 2012

Mammalian cells are capable of delivering multiple types of membrane capsules extracellularly. The limiting membrane of late endosomes can fuse with the plasma membrane, leading to the extracellular release of multivesicular bodies (MVBs), initially contained within the endosomes, as exosomes. Budding viruses exploit the TSG101 protein and endosomal sorting complex required for transport (ESCRT) machinery used for MVB formation to mediate the egress of viral particles from host cells. Here we report the discovery of a virus-independent cellular process that generates microvesicles that are distinct from exosomes and which, like budding viruses, are produced by direct plasma membrane budding. Such budding is driven by a specific interaction of TSG101 with a tetrapeptide PSAP motif of an accessory protein, arrestin domain-containing protein 1 (ARRDC1), which we show is localized to the plasma membrane through its arrestin domain. This interaction results in relocation of TSG101 from endosomes to the plasma membrane and mediates the release of microvesicles that contain TSG101, ARRDC1, and other cellular proteins. Unlike exosomes, which are derived from MVBs, ARRDC1-mediated microvesicles (ARMMs) lack known late endosomal markers. ARMMs formation requires VPS4 ATPase and is enhanced by the E3 ligase WWP2, which interacts with and ubiquitinates ARRDC1. ARRDC1 protein discharged into ARMMs was observed in co-cultured cells, suggesting a role for ARMMs in intercellular communication. Our findings reveal an intrinsic cellular mechanism that results in direct budding of microvesicles from the plasma membrane, providing a formal paradigm for the evolutionary recruitment of ESCRT proteins in the release of budding viruses.
Human kinome profiling identifies a requirement for AMP-activated protein kinase during human cytomegalovirus infection
Authors: Terry Laura J. , Vastag Livia , Rabinowitz Joshua D. , Shenk Thomas
Published: February 2012

Human cytomegalovirus (HCMV) modulates numerous cellular signaling pathways. Alterations in signaling are evident from the broad changes in cellular phosphorylation that occur during HCMV infection and from the altered activity of multiple kinases. Here we report a comprehensive RNAi screen, which predicts that 106 cellular kinases influence growth of the virus, most of which were not previously linked to HCMV replication. Multiple elements of the AMP-activated protein kinase (AMPK) pathway scored in the screen. As a regulator of carbon and nucleotide metabolism, AMPK is poised to activate many of the metabolic pathways induced by HCMV infection. An AMPK inhibitor, compound C, blocked a substantial portion of HCMV-induced metabolic changes, inhibited the accumulation of all HCMV proteins tested, and markedly reduced the production of infectious progeny. We propose that HCMV requires AMPK or related activity for viral replication and reprogramming of cellular metabolism.
Infection Prevention and Control Guidance for Ronald McDonald Houses: A Needs Assessment
Authors: Guzman-Cottrill Judith A. , Bryant Kristina A. , Zerr Danielle M. , Harris Alan A. , Alexander Erin Rose , Boone Zak , Siegel Jane D.
Published: February 2012

We surveyed Ronald McDonald Houses (RMHs) to assess infection prevention and control (IPC) practices. A diverse patient population is served by RMH. Most sites have locally written IPC guidelines, and consultation resources vary, increasing the potential for inconsistent IPC practices. RMH would benefit from a standardized IPC guideline.

Infect Control Hosp Epidemiol 2012;33(3):299-301
Colonization with Extended-Spectrum β-Lactamase-ProducingEscherichia coliandKlebsiellaSpecies in Long-Term Care Facility Residents
Authors: Lautenbach Ebbing , Han Jennifer , Santana Evelyn , Tolomeo Pam , Bilker Warren B. , Maslow Joel
Published: February 2012

We describe the prevalence of and risk factors for colonization with extended-spectrum (3-lactamase-producing Enterobacteriaceae (ESBL-EB) in the long-term care facility (LTCF) setting. Colonization prevalence differed significantly across the 3 LTCFs evaluated in the study, with recent use of levofloxacin and fecal incontinence demonstrating borderline significant associations with ESBL-EB colonization.

Infect Control Hosp Epidemiol2012;33(3):302-304
Iteration of quasiregular tangent functions in three dimensions
Authors: Fletcher A. , Nicks D.
Published: February 2012

We define a new quasiregular mappingT:R3→R3∪{∞}T:\mathbb {R}^3\to \mathbb {R}^3 \cup \{\infty \}that generalizes the tangent function on the complex plane and shares a number of its geometric properties. We investigate the dynamics of the family{λT:λ>0}\{\lambda T:\lambda >0\}, establishing results analogous to those of Devaney and Keen for the meromorphic family{z↦λtan⁡z:λ>0}\{z\mapsto \lambda \tan z:\lambda >0\}, although the methods used are necessarily original.
Unresponsiveness ≠ Unconsciousness
Authors: Sanders Robert D. , Tononi Giulio , Laureys Steven , Sleigh Jamie W. , Warner David S.
Published: February 2012

Consciousness is subjective experience. During both sleep and anesthesia, consciousness is common, evidenced by dreaming. A defining feature of dreaming is that, while conscious, we do not experience our environment; we are disconnected. Besides inducing behavioral unresponsiveness, a key goal of anesthesia is to prevent the experience of surgery (connected consciousness), by inducing either unconsciousness or disconnection of consciousness from the environment. Review of the isolated forearm technique demonstrates that consciousness, connectedness, and responsiveness uncouple during anesthesia; in clinical conditions, a median 37% of patients demonstrate connected consciousness. We describe potential neurobiological constructs that can explain this phenomenon: during light anesthesia the subcortical mechanisms subserving spontaneous behavioral responsiveness are disabled but information integration within the corticothalamic network continues to produce consciousness, and unperturbed norepinephrinergic signaling maintains connectedness. These concepts emphasize the need for developing anesthetic regimens and depth of anesthesia monitors that specifically target mechanisms of consciousness, connectedness, and responsiveness.
Investigation of Short‐term Variations in Casein and Whey Proteins in Breast Milk of Term Mothers
Authors: Khan Sadaf , Casadio Ylenia S. , Lai Ching T. , Prime Danielle K. , Hepworth Anna R. , Trengove Naomi J. , Hartmann Peter E.
Published: February 2012

Objectives:

We investigated changes in breast milk whey and casein proteins, between fore and hind milk during breast expression, between breasts and within 24‐hour period during breast‐feeding. This has implications for developing an appropriate sampling protocol for investigating the influence of milk composition on gastric emptying and infants' feeding behaviour.

Methods:

Breast milk samples were collected from mothers (n = 25) of healthy term infants ages 1 to 8 months. A total of 17 mothers provided fore and hind milk samples, which were collected during simultaneous expression of both breasts. Fifteen mothers provided samples from each breast‐feed during 24‐hour period, of which samples were selected from 4 time points (morning, day, evening, night). Whey and casein were isolated from skim milk, and protein concentration of the skim, whey, and casein fractions were determined.

Results:

Mean protein concentrations were found to be 13.5 ± 2.1 (skim milk), 7.6 ± 1.5 (whey), and 3.4 ± 0.97 g/L (casein). Protein concentrations were not significantly different between fore and hind milk. During a 24‐hour period, no significant differences were found in protein concentration of any fraction at the 4 time points or between left and right breasts. Large variations were seen between mothers with coefficient of variances of 15.5%, 19.8%, and 28.4% for skim milk, whey, and casein, respectively.

Conclusions:

Although there was wide variation between mothers, the small variations within mothers indicate that for sampling purposes, a single breast milk sample (fore or hind from each breast at any time point of the day) will be representative of that mother's protein concentration of skim, whey, and casein fractions for that day.
Pediatric Obesity and Gallstone Disease
Authors: Koebnick Corinna , Smith Ning , Black Mary Helen , Porter Amy H. , Richie Bradley A. , Hudson Sharon , Gililland Deborah , Jacobsen Steven J. , Longstreth George F.
Published: February 2012

Objectives:

The aim of the present study was to investigate the association between childhood and adolescent obesity, the risk of gallstones, and the potential effect modification by oral contraceptive use in girls.

Methods:

For this population‐based cross‐sectional study, measured weight and height, oral contraceptive use, and diagnosis of cholelithiasis or choledocholithiasis were extracted from the electronic medical records of 510,816 patients ages 10 to 19 years enrolled in an integrated health plan, 2007–2009.

Results:

We identified 766 patients with gallstones. The adjusted odds ratios (95% CI) of gallstones for under‐/normal‐weight (reference), overweight, moderate obesity, and extreme obesity in boys were 1.00, 1.46 (0.94%–2.27%), 1.83 (1.17%–2.85%), and 3.10 (1.99%–4.83%) and in girls were 1.00, 2.73 (2.18%–3.42%), 5.75 (4.62%–7.17%), and 7.71 (6.13%–9.71%), respectively (P for interaction sex × weight class <0.001). Among girls, oral contraceptive use was associated with higher odds for gallstones (odds ratio 2.00, 95% CI 1.66%–2.40%). Girls who used oral contraceptives were at higher odds for gallstones than their counterparts in the same weight class who did not use oral contraceptives (P for interaction weight class × oral contraceptive use 0.023).

Conclusions:

Due to the shift toward extreme childhood obesity, especially in minority children, pediatricians can expect to face increasing numbers of children and adolescents affected by gallstone disease.
Review article: the natural history of postoperative Crohn's disease recurrence
Authors: Buisson A. , Chevaux J.‐B. , Allen P. B. , Bommelaer G. , Peyrin‐Biroulet L.
Published: February 2012

Background

Surgical resection of the diseased bowel in Crohn's disease is unfortunately not curative, and postoperative recurrence remains a problem in these patients.

Aim

To review the rates of and risk factors for clinical and endoscopic recurrence in population‐based studies, referral centres and randomised controlled trials.

Methods

We searched MEDLINE (source PUBMED, 1966 to September, 2011).

Results

In randomised controlled trials, clinical recurrence in the first year after surgery occurred in 10–38% of patients, whereas endoscopic recurrence in the first year was reported in 35–85% of patients. In population‐based studies, approximately half of patients experienced clinical recurrence at 10 years. In referral centres, 48–93% of the patients had endoscopic lesions (Rutgeerts’ score ≥1) in the neoterminal ileum within 1 year after surgery, whereas 20–37% had symptoms suggestive of clinical recurrence. Three years after surgery, the endoscopic postoperative recurrence rate increased to 85–100%, and symptomatic recurrence occurred in 34–86% of patients. Smoking is the strongest risk factor for postoperative recurrence, increasing by twofold, the risk of clinical recurrence. Prior intestinal resection, penetrating behaviour, perianal disease and extensive bowel disease (>50 cm) are established risk factors for postoperative recurrence. Risk factors for postoperative recurrence remain poorly defined in population‐based cohorts.

Conclusion

Endoscopic and clinical postoperative recurrence remains common in patients with Crohn's disease, and the identification of risk factors may allow targeted strategies to reduce this recurrence rate.
Human erythrocyte remodelling during Plasmodium falciparum malaria parasite growth and egress
Authors: Mbengue Alassane , Yam Xue Y. , Braun‐Breton Catherine
Published: February 2012

The intra‐erythrocyte growth and survival of the malarial parasite Plasmodium falciparum is responsible for both uncomplicated and severe malaria cases and depends on the parasite's ability to remodel its host cell. Host cell remodelling has several functions for the parasite, such as acquiring nutrients from the extracellular milieu because of the loss of membrane transporters upon erythrocyte differentiation, avoiding splenic clearance by conferring cytoadhesive properties to the infected erythrocyte, escaping the host immune response by exporting antigenically variant proteins at the red blood cell surface. In addition, parasite‐induced changes at the red blood cell membrane and sub‐membrane skeleton are also necessary for the efficient release of the parasite progeny from the host cell. Here we review these cellular and molecular changes, which might not only sustain parasite growth but also prepare, at a very early stage, the last step of egress from the host cell.
Novel missense mutation in the IGF‐I receptor L2 domain results in intrauterine and postnatal growth retardation
Authors: Kawashima Yuki , Higaki Katsumi , Fukushima Toshiaki , Hakuno Fumihiko , Nagaishi Jun‐ichi , Hanaki Keiichi , Nanba Eiji , Takahashi Shin‐Ichiro , Kanzaki Susumu
Published: February 2012

Background

IGFs play key roles in intrauterine and postnatal growth through the IGF‐I receptor (IGF‐IR). We identified a family bearing a new heterozygous missense mutation at the L2 domain of IGF‐IR (R431L).

Method

We analysed the nucleotide sequences of the IGF1R gene of the family. We prepared R− cells (fibroblasts with targeted disruption of the IGF‐IR gene) expressing wild‐type or R431L IGF‐IR and performed functional analyses by evaluating IGF‐I binding, IGF‐I‐stimulated DNA synthesis, tyrosine phosphorylation of IGF‐IR and its substrates, and internalization by measuring [125I]IGF‐I internalization. We also performed confocal microscopy analysis.

Results

We identified a family bearing a new heterozygous missense mutation at the L2 domain of IGF‐IR (R431L) through an 8‐year‐old girl and her mother, both born with intrauterine growth retardation. In experiments conducted using cells homozygously transfected with the IGF‐IR R431L mutation; (i) IGF‐I binding was not affected; (ii) DNA synthesis induced by IGF‐I was decreased; (iii) IGF‐IR internalization stimulated by IGF‐I was decreased and (iv) IGF‐I‐stimulated tyrosine phosphorylation was reduced IGF‐IR by low concentrations of IGF‐I and on insulin receptor substrate (IRS)‐1 and IRS‐2.

Conclusion

A missense mutation (R431L) leads to the inhibition of cell proliferation, attenuation of IGF signalling and decrease in internalization of IGF‐IR. The results of this study suggest a novel link between a mutation at the IGF‐IR L2 domain and intrauterine and postnatal growth retardation.
Reverse iontophoresis of urea in health and chronic kidney disease: a potential diagnostic and monitoring tool?
Authors: Ebah Leonard M. , Read Ian , Sayce Andrew , Morgan Jane , Chaloner Christopher , Brenchley Paul , Mitra Sandip
Published: February 2012

Eur J Clin Invest 2012;

Background  Patients with chronic kidney disease (CKD) need regular monitoring, usually by blood urea and creatinine measurements, needing venepuncture, frequent attendances and a healthcare professional, with significant inconvenience. Noninvasive monitoring will potentially simplify and improve monitoring. We tested the potential of transdermal reverse iontophoresis of urea in patients with CKD and healthy controls.

Methods  Using a MIC 2® Iontophoresis Controller, reverse iontophoresis was applied on the forearm of five healthy subjects (controls) and 18 patients with CKD for 3–5 h. Urea extracted at the cathode was measured and compared with plasma urea.

Results  Reverse iontophoresis at 250 μA was entirely safe for the duration. Cathodal buffer urea linearly correlated with plasma urea after 2 h (r = 0·82, P < 0·0001), to 3·5 h current application (r = 0·89, P = 0·007). The linear equations y = 0·24x + 1 and y = 0·21x + 4·63 predicted plasma urea (y) from cathodal urea after 2 and 3 h, respectively. Cathodal urea concentration in controls was significantly lower than in patients with CKD after a minimum current application of 2 h (P < 0·0001), with the separation between the two groups becoming more apparent with longer application (P = 0·003). A cathodal urea cut‐off of 30 μM gave a sensitivity of 83·3% and positive predictive value of 87% CKD. During haemodialysis, the fall in cathodal urea was able to track that of blood urea.

Conclusion  Reverse iontophoresis is safe, can potentially discriminate patients with CKD and healthy subjects and is able to track blood urea changes on dialysis. Further development of the technology for routine use can lead to an exciting opportunity for its use in diagnostics and monitoring.
Large‐scale, long‐term trends in British river macroinvertebrates
Authors: Vaughan Ian P. , Ormerod Steve J.
Published: February 2012

Rivers are among the world's most modified ecosystems, with poor water quality representing a prominent problem for over 200 years, especially in urban areas. In Western Europe, however, industrial decline, tighter regulation and improved wastewater treatment have combined over recent decades to create conditions conducive to extensive restoration and positive biological change. Here, we evaluate the river macroinvertebrate fauna of England and Wales in relation to water quality, physical habitat and climate over almost two decades. We predicted that biological recovery would be characterized by: (i) greater taxon richness and prevalence of pollution‐sensitive taxa, (ii) larger changes in more heavily urbanized catchments, and (iii) temporal trends in assemblage structure that correlated with improving water quality. Family level richness increased on average by nearly 20% during 1991–2008, accompanied by a widespread shift towards taxa characteristic of well‐oxygenated and less polluted waters. Changes were largest in the most urbanized catchments. A combination of natural gradients and anthropogenic pressures explained the variation among sites, whereas temporal changes correlated with improving water quality and variations in discharge. Positive trends were not universal, however, and there was localized deterioration in some streams draining upland areas and in the lowland south east. Our results are consistent with a large‐scale ecological recovery of English and Welsh rivers since 1990, probably continuing a trend from the mid‐20th century. Based on these results, we suggest: (i) freshwater communities are resilient to long‐term anthropogenic pressures, (ii) biodiversity benefits can arise from investment and long‐term restoration intended largely to enhance ecosystem services such as drinking water and sanitary concerns, and (iii) long‐term monitoring data collected for statutory purposes–based in this case on nearly 50 000 samples–can address scientific questions at spatial and temporal extents seldom achieved in research programmes.
Keeping nurse researchers safe: workplace health and safety issues
Authors: Barr Jennieffer , Welch Anthony
Published: February 2012

barr j. & welch a. (2012) Keeping nurse researchers safe: workplace health and safety issues. Journal of Advanced Nursing68(7), 1538–1545.

Aim.  This article is a report of a qualitative study of workplace health and safety issues in nursing research.

Background.  Researcher health and safety have become increasing concerns as there is an increased amount of research undertaken in the community and yet there is a lack of appropriate guidelines on how to keep researchers safe when undertaking fieldwork.

Design.  This study employed a descriptive qualitative approach, using different sources of data to find any references to researcher health and safety issues.

Methods.  A simple descriptive approach to inquiry was used for this study. Three approaches to data collection were used: interviews with 15 researchers, audits of 18 ethics applications, and exploration of the literature between 1992 and 2010 for examples of researcher safety issues. Data analysis from the three approaches identified participant comments, narrative descriptions or statements focused on researcher health and safety.

Results.  Nurse researchers’ health and safety may be at risk when conducting research in the community. Particular concern involves conducting sensitive research where researchers are physically at risk of being harmed, or being exposed to the development of somatic symptoms. Nurse researchers may perceive the level of risk of harm as lower than the actual or potential harm present in research. Nurse researchers do not consistently implement risk assessment before and during research.

Conclusions.  Researcher health and safety should be carefully considered at all stages of the research process. Research focusing on sensitive data and vulnerable populations need to consider risk minimization through strategies such as appropriate researcher preparation, safety during data collection, and debriefing if required.
Genetic variants associated with predisposition to prostate cancer and potential clinical implications
Authors: Goh C. L. , Schumacher F. R. , Easton D. , Muir K. , Henderson B. , Kote‐Jarai Z. , Eeles R. A.
Published: February 2012

Abstract.  Goh CL, Schumacher FR, Easton D, Muir K, Henderson B, Kote‐Jarai Z, Eeles RA (The Institute of Cancer Research, Sutton, Surrey, UK; Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Strangeways Laboratory, University of Cambridge, Cambridge; Health Sciences Research Institute, Warwick Medical School, University of Warwick, Coventry; Royal Marsden Foundation NHS Trust, Sutton, Surrey, UK). Genetic variants associated with predisposition to prostate cancer and potential clinical implications (Review). J Intern Med 2012; 271: 353–365.

Prostate cancer is the commonest cancer in the developed world. There is an inherited component to this disease as shown in familial and twin studies. However, the discovery of these variants has been difficult. The emergence of genome‐wide association studies has led to the identification of over 46 susceptibility loci. Their clinical utility to predict risk, response to treatment, or treatment toxicity, remains undefined. Large consortia are needed to achieve adequate statistical power to answer these genetic–clinical and genetic–epidemiological questions. International collaborations are currently underway to link genetic with clinical/epidemiological data to develop risk prediction models, which could direct screening and treatment programs.
Climate‐controlled aggradation and cyclicity of continental loessic siliciclastic sediments in Asselian–Sakmarian cyclothems, Permian, Hugoton embayment, USA
Authors: DUBOIS MARTIN K. , GOLDSTEIN ROBERT H. , HASIOTIS STEPHEN T.
Published: February 2012

Siliciclastic intervals in Lower Permian carbonate–siliciclastic cyclothems in western Kansas record climate control on facies progression, deposition and preservation. The 26 000 km2study area comprises seven marine‐continental (carbonate–siliciclastic) cyclothems caused by glacioeustasy. Core data and a three‐dimensional geological model provide a detailed view of the sub‐surface on a gently sloping ramp. Siliciclastic intervals in the cyclothems are fine‐grained red beds with extensive pedogenic features, indicating a continental origin. Bed geometry (sheet‐like deposits that thin to the east), lateral grading, grain size (very fine‐grained sand to silt) and grain angularity (sub‐angular to angular) suggest that the sediment is loess sourced from the west, probably the Ancestral Rocky Mountains. There is a repeated record of glacial‐cycle‐scale, climate‐controlled cyclicity within siliciclastic intervals that has not been recognized previously. Aeolian silt grain size coarsens upward towards the middle, then fines upward in each siliciclastic interval. When sea‐level was high (interglacial) and carbonate production flourished, aeolian sedimentation nearly ceased, suggesting increased vegetation and rainfall at the source. As sea‐level fell, fine‐grained siliciclastic sediments were deposited under relatively dry, but seasonally wet conditions on an exposed ramp. Laterally graded coarser grained siliciclastic sediments with diagnostic fabrics indicate drier conditions with seasonal rainfall during a continued relative fall in sea‐level. The coarsest siliciclastic sediments were deposited during the lowest sea‐level and driest conditions, but still with sufficient seasonal moisture to allow vegetative cover and bioturbation. Subsequent upward fining is correlated with sedimentological indications of wetter conditions during relative sea‐level rise. Unlike common sequence stratigraphic models that relate siliciclastic sediment accumulation to base‐level rise, continental deposits were preserved because plants and pedogenesis stabilized aeolian sediment. The aggradational landscape formed by this process had several metres of positive relief that reduced accommodation for overlying marine carbonate strata. Thus, this mechanism for continental siliciclastic aggradation has a significant effect on sequence stratigraphic architecture.