bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymerization of nitrogen in lithium azide
Authors: Wang Xiaoli , Li Jianfu , Botana Jorge , Zhang Meiguang , Zhu Hongyang , Chen Li , Liu Hongmei , Cui Tian , Miao Maosheng
Published: October 2013

Additional electrons can drastically change the bonding trend of light elements. For example, N atoms in alkali metal azides form the linear N3− anions instead of N2 molecules with the introduction of additional electrons. The effect of the additional electrons on the polymerization of N under pressure is important and thus far unclear. Using first principles density functional methods and the particle swarm optimization structure search algorithm, we systematically study the evolution of LiN3 structures under pressures up to 600 GPa. A stable structure featuring polymerized N under pressures higher than 375 GPa is identified for the first time. It consists of zig-zag N polymer chains that are formed by N5− five-member rings sharing N–N pairs. Throughout the stable pressure range, the structure is insulating and consists of N atoms in sp3 hybridizations. Comparing with the atomic and electronic structures of previous phases, our study completes the structural evolution of LiN3 under pressure and reveals the structural changes which are accompanied and driven by the change of atomic orbital hybridization, first from sp to sp2 and then from sp2 to sp3.
Origin of subgap states in amorphous In-Ga-Zn-O
Authors: Körner Wolfgang , Urban Daniel F. , Elsässer Christian
Published: October 2013

We present a density functional theory analysis of stoichiometric and nonstoichiometric, crystalline and amorphous In-Ga-Zn-O (c-IGZO, a-IGZO), which connects the recently experimentally discovered electronic subgap states to structural features of a-IGZO. In particular, we show that undercoordinated oxygen atoms create electronic defect levels in the lower half of the band gap up to about 1.5 eV above the valence band edge. As a second class of fundamental defects that appear in a-IGZO, we identify mainly pairs of metal atoms which are not separated by oxygen atoms in between. These defects cause electronic defect levels in the upper part of the band gap. Furthermore, we show that hydrogen doping can suppress the deep levels due to undercoordinated oxygen atoms while those of metal defects just undergo a shift within the band gap. Altogether our results provide an explanation for the experimentally observed effect that hydrogen doping increases the transparency and improves the conductivity of a-IGZO.
Planar isotropic broadband metamaterial absorber
Authors: Gu Shuai , Su Bin , Zhao Xiaopeng
Published: October 2013

This paper presents a type of isotropic broadband metamaterial absorber comprising single-layer densely arranged hexagonal metal dendritic units having different sizes printed on an FR-4 dielectric substrate with a metallic film coating. The convergence of the different neighboring resonant frequencies of the differently sized units yields broadband absorption characteristics. In the case of normal incidence, the absorber operating in the X-band yields absorption rates greater than 80% in the frequency range from 9.05 GHz to 11.4 GHz, this reasonable absorption performance is maintained for oblique incidences less than 45°. The S-band absorber has an absorptivity of more than 50% in the frequency range from 3.02 GHz to 4 GHz. The experimental results demonstrate that the interaction between the different structural units is not obvious.
Synthesizing frequency selective metasurfaces with nanodisks
Authors: Saeidi Chiya , van der Weide Daniel
Published: October 2013

We present a comprehensive method for synthesizing frequency selective surfaces (FSSs) composed of arrays of periodic nanodisks. The synthesis is based on the recently derived equivalent circuit of the nanoparticle arrays, whose element values are related to the physical, geometrical, and electrical parameters of the FSS, and can be determined from the desired frequency response. We validate the synthesis procedure with design examples of FSSs with second-order Chebyshev and third-order Butterworth bandstop responses.
Enhancement of the superconducting transition temperature in FeSe epitaxial thin films by anisotropic compression
Authors: Nabeshima Fuyuki , Imai Yoshinori , Hanawa Masafumi , Tsukada Ichiro , Maeda Atsutaka
Published: October 2013

In order to investigate the effects of in-plane strain on the superconductivity of FeSe, epitaxial thin films of FeSe were fabricated on CaF2 substrates. The films are compressed along the a-axis and their superconducting transition temperatures Tczero reach 11.4 K, which is approximately 1.5 times higher than that of bulk crystals. The Tc values are weakly dependent on the ratio of the lattice constants, c/a, compared to that of Fe(Se, Te). Our results indicate that even a binary system FeSe has room for improvement, and will pave the way for the application of Fe-based superconductors.
Surface waves in the magnetized, collisional dusty plasmas
Authors: Pandey B. P. , Vladimirov S. V. , Ishihara O.
Published: October 2013

The properties of the low frequency surface waves in inhomogeneous, magnetized collisional complex dusty plasma are investigated in this work. The inhomogeneity is modelled by the two distinct regions of the dusty medium with different dust densities. The external magnetic field is assumed to be oriented along the interface dividing the two medium. It is shown that the collisional momentum exchange that is responsible for the relative drift between the plasma particles affects the propagation of the surface waves in the complex plasma via the Hall drift of the magnetic fluctuations. The propagation properties of the sausage and kink waves depend not only on the grain charge and size distribution but also on the ambient plasma thermal conditions.
Continuous 30 μW terahertz source by a high-Tc superconductor mesa structure
Authors: Sekimoto S. , Watanabe C. , Minami H. , Yamamoto T. , Kashiwagi T. , Klemm Richard A. , Kadowaki K.
Published: October 2013

Using a modified mesa structure of high-Tc superconducting Bi2Sr2CaCu2O8+δ with a thin underlaying base superconductor (∼3 μm), the effective working temperature of the continuous and monochromatic terahertz emitter is extended up to 70 K, and the maximum power of ∼30 μW at 0.44 THz is achieved at the relatively high temperature of Tb = 55 K in a low bias current retrapping region. The diverging behavior of the intensity occurring at 55 K in the low current regime without hot spot formation may provide us an important clue for the stronger THz radiation from intrinsic Josephson junction devices.
Communication: Site-dependent reactivity between chlorine atoms and mixed-chain-length alkanethiolate monolayers
Authors: Lee David Y. , Kandel S. Alex
Published: October 2013

The chemical reaction of atomic chlorine with mixed monolayers of alkanethiolates having different chain lengths was investigated. In situ scanning tunneling microscopy was used to acquire time-lapsed series of images, allowing the measurement of the effect of monolayer structure and composition on reactivity. The rate of chemical reaction is strongly site-dependent. In particular, the boundary between two different-length alkanethiolates greatly promotes the reactivity of nearby molecules, much more so than any other native defect typical of single-component alkanethiolate monolayers.
Characteristics and applications of near-infrared emissions from lightning
Authors: Zhao Jincui , Yuan Ping , Cen Jianyong , Liu Jianguo , Wang Jie , Zhang Guangshu
Published: October 2013

Using the lightning spectra captured by a slitless spectrograph, the characteristics of near-infrared emissions from lightning are investigated. The results show that atomic lines in the near-infrared range are consistently strong and can be almost recorded during the whole luminous phase from the leader to the return stroke. OI 777.4 nm is persistently one of the strongest lines in the near-infrared range of lightning spectra. Moreover, by combining synchronous electric field information, the intensity of OI 777.4 nm is found to correlate well with the amplitude of the electric field change, and its waveform is consistent with the waveform of synchronous electric field change. It is concluded that the information of OI 777.4 nm recorded in the thunderstorm activities can be used to locate the lightning discharge processes, including counting the flashes, identifying discharge intensity, displaying spatial and temporal evolution of the discharge channel, and even presenting more details of discharge processes.
Controllable acoustic rectification in one-dimensional piezoelectric composite plates
Authors: Zou Xin-Ye , Liang Bin , Yuan Ying , Zhu Xue-Feng , Cheng Jian-Chun
Published: October 2013

Theoretical studies are presented for the band structures and power transmission spectra for both symmetric and asymmetric Lamb wave modes in a one-dimensional piezoelectric composite plate consisting of piezoelectric ceramics placed periodically in epoxy by the plane wave expansion method and the harmonic response analysis method, respectively. The one-way transmission, two-way transmission, and two-way forbidden models of acoustic rectification for Lamb waves can be established in specific frequency ranges by introducing corresponding modes conversion and selection mechanisms, and the steady-state displacement fields of these models are also calculated for the proposed plate. The numerical results show that the power extinction ratio for one-way transmission model is up to 104. The piezoelectric composite plate can be switched between these models rapidly and efficiently only by applying the open-circuit and short-circuit electric boundary conditions antisymmetrically or symmetrically on the piezoelectric ceramic unit's boundaries instead of changing any geometrical structure, and the composite plate's architecture structure is also simple enough for the on-chip integration in the engineering field.
Flowing microbubble manipulation in blood vessel phantom using ultrasonic standing wave with stepwise frequency
Authors: Shi Aiwei , Min Yu , Wan Mingxi
Published: October 2013

An approach was demonstrated to gather, fix, and controllably shift flowing microbubbles in a blood vessel phantom. An ultrasonic standing wave field was generated by the superposition of the emission of a 5 MHz conventional transducer and the reflection from a bone surface. The acoustic radiation force gathered flowing microbubbles into the nodes, fixed some accumulated microbubble clusters in the flow condition, and shifted microbubbles to target site with stepwise frequency. The resolution of microbubble shift was approximately 4 μm, and the low acoustic pressure range was from 4 to 16 kPa to avoid microbubble rupture.
Unidirectionally oriented nanocracks on metal surfaces irradiated by low-fluence femtosecond laser pulses
Authors: Shimizu Masahiro , Hashida Masaki , Miyasaka Yasuhiro , Tokita Shigeki , Sakabe Shuji
Published: October 2013

We have investigated the origin of nanostructures formed on metals by low-fluence femtosecond laser pulses. Nanoscale cracks oriented perpendicular to the incident laser polarization are induced on tungsten, molybdenum, and copper targets. The number density of the cracks increases with the number of pulses, but crack length plateaus. Electromagnetic field simulation by the finite-difference time-domain method indicates that electric field is locally enhanced along the direction perpendicular to the incident laser polarization around a nanoscale hole on the metal surface. Crack formation originates from the hole.
Observability of the quantum pinch effect in semiconducting quantum wires
Authors: Kushwaha Manvir S.
Published: October 2013

We investigate a two-component, cylindrical, quasi-one-dimensional quantum plasma subjected to a radial confining harmonic potential and an applied magnetic field in the symmetric gauge. It is demonstrated that such a system as can be realized in semiconducting quantum wires offers an excellent medium for observing the quantum pinch effect at low temperatures. An exact analytical solution of the problem allows us to make significant observations: surprisingly, in contrast to the classical pinch effect, the particle density as well as the current density displays a determinable maximum before attaining a minimum at the surface of the quantum wire. The effect will persist as long as the equilibrium pair density is sustained. Therefore, the technological promise that emerges is the route to the precise electronic devices that will control the particle beams at the nanoscale.
Accurate layers determination of graphene on transparent substrate based on polarization-sensitive absorption effect
Authors: Wang Peng , Liu Zhi-Bo , Chen Xu-Dong , Xing Fei , Jiang Wen-Shuai , Dong Bin , Xin Wei , Tian Jian-Guo
Published: October 2013

Based on the polarization-sensitive absorption effect, we have proposed a method to accurately count the number of carbon atomic layers for both exfoliated and chemical vapor deposition graphene sheets on transparent substrate. With spatial scanning, the three-dimensional imaging of graphene sample can be achieved to test the uniformity of the sample. In addition, our method serves for graphene test on transparent substrate, which is different from the commonly used SiO2/Si substrate. Moreover, this method is also applicable to layers counting of other two-dimensional materials. Therefore, it paves the way for applications of two-dimensional materials on transparent medium.
Improving electrical performance and bias stability of HfInZnO-TFT with optimizing the channel thickness
Authors: Li Jun , Ding Xing-Wei , Zhang Jian-Hua , Zhang Hao , Jiang Xue-Yin , Zhang Zhi-Lin
Published: October 2013

RF magnetron sputtered HfInZnO film and atomic layer deposition (ALD) Al2O3 film were employed for thin film transistors (TFTs) as channel layer and gate insulator, respectively. To achieve HfInZnO-TFT with high performance and good bias stability, the thickness of HfInZnO active layer was optimized. The performance of HfInZnO-TFTs was found to be thickness dependent. As the HfInZnO active layer got thicker, the leakage current greatly increased from 1.73 × 10−12 to 2.54 × 10−8 A, the threshold voltage decreased from 7.4 to −4.7 V, while the subthreshold swing varied from 0.41 to 1.07 V/decade. Overall, the HfInZnO film showed superior performance, such as saturation mobility of 6.4 cm2/V s, threshold voltage of 4.2 V, subthreshold swing of 0.43 V/decade, on/off current ratio of 3 × 107 and Vth shift of 3.6 V under VGS = 10 V for 7200 s. The results demonstrate the possibility of fabricating TFTs using HfInZnO film as active layer and using ALD Al2O3 as gate insulator.
A critical review of vaginal birth rates after a primary Caesarean in Queensland hospitals
Authors: Toohill Jocelyn , Gamble Jenny , Creedy Debra K.
Published: October 2013

Introduction For women with a lower uterine incision without indication for repeat Caesarean section (CS), vaginal birth for their next pregnancy is a safe option. Although these women should be encouraged to consider vaginal birth after a Caesarean section (VBAC) it is not consistently supported in practice. There is relatively little information on the extent to which maternal preference, birthing decisions and outcomes match best available evidence. Aim To describe current VBAC rates for women in Queensland, Australia and compare this to safe, achievable VBAC rates reported in national and international studies. Method Perinatal data from 2004 to 2011 were reviewed to determine current VBAC rates following a primary CS for women birthing in Queensland. These were compared with VBAC rates reported in the literature. Results Queensland has a high overall CS rate and high repeat CS rate compared with the national average. In 2010, Queensland VBAC rates for next birth following primary CS were 14% (range 13–21% public sector, 7–11% private hospitals). This is substantially lower than achievable Australian rates of 24% and international rates. Conclusion Low VBAC rates reflect low numbers of women commencing labour in a pregnancy subsequent to a primary CS. There is unexplained variation in VBAC rates between maternity facilities. Clinical reviews to support evidence-based practice are warranted. What is known about the topic? Repeat CS is a major contributor to high CS rates in industrialised countries. What does this paper add? Following a primary CS, women in Queensland are less likely to commence labour and achieve a vaginal birth compared with rates reported in national and international VBAC studies. What are the implications for practitioners? Maternity clinicians need to be aware of best practice and contextualise the evidence for individual women to improve VBAC rates.
Recombination rates between adjacent genic and retrotransposon regions in maize vary by 2 orders of magnitude
Authors: Fu Huihua , Zheng Zhenwei , Dooner Hugo K.
Published: October 2013

Genetic map length and gene number in eukaryotes vary considerably less than genome size, giving rise to the hypothesis that recombination is restricted to genes. The complex genome of maize contains a large fraction of repetitive DNA, composed principally of retrotransposons arranged in clusters. Here, we assess directly the contribution of retrotransposon clusters and genes to genetic length. We first measured recombination across adjacent homozygous genetic intervals on either side of the bronze (
bz
) locus. We then isolated and characterized two bacterial artificial chromosome clones containing those intervals. Recombination was almost 2 orders of magnitude higher in the distal side, which is gene-dense and lacks retrotransposons, than in the proximal side, which is gene-poor and contains a large cluster of methylated retrotransposons. We conclude that the repetitive retrotransposon DNA in maize, which constitutes the bulk of the genome, most likely contributes little if any to genetic length.
Ku86 is essential in human somatic cells
Authors: Li Gang , Nelsen Caron , Hendrickson Eric A.
Published: October 2013

Ku86 plays a key role in nonhomologous end joining in mammals. Functional inactivation in rodents of either Ku86 or Ku70, which form the heterodimeric DNA end-binding subunit of the DNA-dependent protein kinase complex, is nevertheless compatible with viability. In contrast, no human patient has been described with mutations in either Ku86 or Ku70. This has led to the hypotheses that either these genes are performing an additional essential role(s) and/or redundant pathways exist that mask the phenotypic expression of these genes when they are mutated in humans. To address this issue, we describe here the construction of human somatic cell lines containing a targeted disruption of the Ku86 locus. Human HCT116 colon cancer cells heterozygous for Ku86 were haploinsufficient with an increase in polyploid cells, a reduction in cell proliferation, elevated p53 levels, and a slight hypersensitivity to ionizing radiation. Functional inactivation of the second Ku86 allele resulted in cells with a drastically reduced doubling time. These cells were capable of undergoing only a limited number of cell divisions, after which they underwent apoptosis. These experiments demonstrate that the Ku86 locus is essential in human somatic tissue culture cells.
Plasmonic antennas as design elements for coherent ultrafast nanophotonics
Authors: Brinks Daan , Castro-Lopez Marta , Hildner Richard , van Hulst Niek F.
Published: October 2013

Significance

The focus of ultrafast science is rapidly moving toward increasingly complex systems, both on a fundamental level (such as quantum networks in diamond or excitonic coherence in photosynthesis) and in applied physics (such as multiphoton microscopy in membranes and cells). However, to disentangle the heterogeneous contributions to dynamics in such complex structures, femtosecond time resolution needs to be accompanied by nanometric spatial excitation volumes. Here we present preengineered plasmonic structures to amplitude-phase shape excitation pulses in a designed way, and thus deliver simultaneous deterministic spatial and temporal control. We expect these results to establish the reproducibility that ultrafast plasmonics needs to serve as a reliable and accurate tool for the investigation of femtosecond nanoscopic dynamics in complex systems.
Intracellular pH reduction prevents excitotoxic and ischemic neuronal death by inhibiting NADPH oxidase
Authors: Lam Tina I. , Brennan-Minnella Angela M. , Won Seok Joon , Shen Yiguo , Hefner Colleen , Shi Yejie , Sun Dandan , Swanson Raymond A.
Published: October 2013

Significance

Activation of NMDA-type glutamate receptors produces neuronal excitotoxicity, a primary cause of cell death in stroke and other neurological disorders. This cell death process requires superoxide release by neuronal NADPH oxidase. Results presented here show that small reductions in intracellular pH uncouple neuronal NADPH oxidase from NMDA receptor activation, and thereby prevent neuronal death. The findings establish a link between metabolic activity and excitotoxicity, and identify a mechanism by which mild acidosis improves outcome after excitotoxic and ischemic brain insults. The findings also suggest that variations in intracellular pH associated with physiological brain activity may likewise influence the cell-to-cell signaling normally mediated by neuronal superoxide release.
Par1b links lumen polarity with LGN–NuMA positioning for distinct epithelial cell division phenotypes
Authors: Lázaro-Diéguez Francisco , Cohen David , Fernandez Dawn , Hodgson Louis , van IJzendoorn Sven C.D. , Müsch Anne
Published: October 2013

Columnar epithelia establish their luminal domains and their mitotic spindles parallel to the basal surface and undergo symmetric cell divisions in which the cleavage furrow bisects the apical domain. Hepatocyte lumina interrupt the lateral domain of neighboring cells perpendicular to two basal domains and their cleavage furrow rarely bifurcates the luminal domains. We determine that the serine/threonine kinase Par1b defines lumen position in concert with the position of the astral microtubule anchoring complex LGN–NuMA to yield the distinct epithelial division phenotypes. Par1b signaling via the extracellular matrix (ECM) in polarizing cells determined RhoA/Rho-kinase activity at cell–cell contact sites. Columnar MDCK and Par1b-depleted hepatocytic HepG2 cells featured high RhoA activity that correlated with robust LGN–NuMA recruitment to the metaphase cortex, spindle alignment with the substratum, and columnar organization. Reduced RhoA activity at the metaphase cortex in HepG2 cells and Par1b-overexpressing MDCK cells correlated with a single or no LGN–NuMA crescent, tilted spindles, and the development of lateral lumen polarity.
Extracellular cell wall β(1,3)glucan is required to couple septation to actomyosin ring contraction
Authors: Muñoz Javier , Cortés Juan Carlos G. , Sipiczki Matthias , Ramos Mariona , Clemente-Ramos José Angel , Moreno M. Belén , Martins Ivone M. , Pérez Pilar , Ribas Juan Carlos
Published: October 2013

Cytokinesis has been extensively studied in different models, but the role of the extracellular cell wall is less understood. Here we studied this process in fission yeast. The essential protein Bgs4 synthesizes the main cell wall β(1,3)glucan. We show that Bgs4-derived β(1,3)glucan is required for correct and stable actomyosin ring positioning in the cell middle, before the start of septum formation and anchorage to the cell wall. Consequently, β(1,3)glucan loss generated ring sliding, oblique positioned rings and septa, misdirected septum synthesis indicative of relaxed rings, and uncoupling between a fast ring and membrane ingression and slow septum synthesis, suggesting that cytokinesis can progress with defective septum pushing and/or ring pulling forces. Moreover, Bgs4-derived β(1,3)glucan is essential for secondary septum formation and correct primary septum completion. Therefore, our results show that extracellular β(1,3)glucan is required for cytokinesis to connect the cell wall with the plasma membrane and for contractile ring function, as proposed for the equivalent extracellular matrix in animal cells.
The interplay between Hebbian and homeostatic synaptic plasticity
Authors: Vitureira Nathalia , Goda Yukiko
Published: October 2013

Synaptic plasticity, a change in the efficacy of synaptic signaling, is a key property of synaptic communication that is vital to many brain functions. Hebbian forms of long-lasting synaptic plasticity—long-term potentiation (LTP) and long-term depression (LTD)—have been well studied and are considered to be the cellular basis for particular types of memory. Recently, homeostatic synaptic plasticity, a compensatory form of synaptic strength change, has attracted attention as a cellular mechanism that counteracts changes brought about by LTP and LTD to help stabilize neuronal network activity. New findings on the cellular mechanisms and molecular players of the two forms of plasticity are uncovering the interplay between them in individual neurons.
(Don’t) Write My Lips: Interpretations of the Relationship between German Sign Language and German across Scales of SignWriting Practice
Authors: Hoffmann-Dilloway Erika
Published: October 2013

Perceptions of boundaries between communicative codes and the modalities through which they are produced and perceived are mediated by social actors’ particular communicative repertoires and histories. I focus in particular on how the affordances of SignWriting (SW), a writing system for sign languages that has been adapted in Germany to additionally inscribe the physical movements by which spoken languages are produced, reveal and affect users’ diverse interpretations of the relationship between German Sign Language (DGS) and German. I examine the production and interpretation of DGS SW texts on two different scales: a classroom in Germany and a transnational, multilingual online network of SignWriters with whom classroom participants engage.
Pediatric Antimicrobial Susceptibility Trends across the United States
Authors: Tamma Pranita D. , Robinson Gwen L. , Gerber Jeffrey S. , Newland Jason G. , DeLisle Chloe M. , Zaoutis Theoklis E. , Milstone Aaron M.
Published: October 2013

Objective.

Antimicrobial susceptibility patterns across US pediatric healthcare institutions are unknown. A national pooled pediatric antibiogram (1) identifies nationwide trends in antimicrobial resistance, (2) allows across-hospital benchmarking, and (3) provides guidance for empirical antimicrobial regimens for institutions unable to generate pediatric antibiograms.

Methods.

In January 2012, a request for submission of pediatric antibiograms between 2005 and 2011 was sent to 233 US hospitals. A summary antibiogram was compiled from participating institutions to generate proportions of antimicrobial susceptibility. Temporal and regional comparisons were evaluated using χ² tests and logistic regression, respectively.

Results.

Of 200 institutions (85%) responding to our survey, 78 (39%) reported generating pediatric antibiograms, and 55 (71%) submitted antibiograms. Carbapenems had the highest activity against the majority of gram-negative organisms tested, but no antibiotic had more than 90% activity against Pseudomonas aeruginosa. Approximately 50% of all Staphylococcus aureus isolates were methicillin resistant. Western hospitals had significantly lower proportions of S. aureus that were methicillin resistant compared with all other regions tested. Overall, 21% of S. aureus isolates had resistance to clindamycin. Among Enterococcus faecium isolates, the prevalence of susceptibility to ampicillin (25%) and vancomycin (45%) was low but improved over time (P < .01), and 8% of E. faecium isolates were resistant to linezolid. Southern hospitals reported significantly higher prevalence of E. faecium with susceptibilities to ampicillin, vancomycin, and linezolid compared with the other 3 regions (P < .01).

Conclusions.

A pooled, pediatric antibiogram can identify nationwide antimicrobial resistance patterns for common pathogens and might serve as a useful tool for benchmarking resistance and informing national prescribing guidelines for children.
The Use of Best Practice Alerts with the Development of an Antimicrobial Stewardship Navigator to Promote Antibiotic De-escalation in the Electronic Medical Record
Authors: Schulz Lucas , Osterby Kurt , Fox Barry
Published: October 2013

Objective.

Develop a clinical decision support tool comprised of an electronic medical record alert and antimicrobial stewardship navigator to facilitate antimicrobial stewardship.

Design.

We analyzed alerts targeting antimicrobial de-escalation to assess the effectiveness of the navigator as a stewardship tool. The alert provides antimicrobial recommendations, then directs providers to the navigator, which includes order management, relevant patient information, evidence-based clinical information, and bidirectional communication capability.

Setting.

Academic, tertiary care medical center with an electronic medical record.

Intervention.

Alerts containing stewardship recommendations and immediate access to the navigator were created.

Results.

Antibiotic use and response data were collected 1 day before stewardship recommendation via the best practice alert (BPA) tool and 1 day after the BPA tool response. A total of 1,285 stewardship BPAs were created. Two hundred and forty-four (18.9%) of the BPAs were created and acted upon within 72 hours for the purpose of de-escalation: 169 (69%) were accepted, 30 (12%) were accepted with modification, and 45 (18%) were rejected. Statistically significant decreases in total antibiotic use as well as in use of broad-spectrum (anti-methicillin-resistant Staphylococcus aureus and anti-pseudomonal) agents occurred when accepted recommendations were compared with rejected recommendations.

Conclusions.

We describe the successful development of a clinical decision support tool to perform prospective audit and feedback comprised of an alert and navigator system featuring evidence-based recommendations and clinical and educational information. We demonstrate that this tool improves antibiotic use through our example of de-escalation.

Clinical Trials Identifier.

This project was registered at ClinicalTrials.gov (NCT01573195).
Identification of important regressor groups, subgroups and individuals via regularization methods: application to gut microbiome data
Authors: Garcia Tanya P. , Müller Samuel , Carroll Raymond J. , Walzem Rosemary L.
Published: October 2013

Motivation: Gut microbiota can be classified at multiple taxonomy levels. Strategies to use changes in microbiota composition to effect health improvements require knowing at which taxonomy level interventions should be aimed. Identifying these important levels is difficult, however, because most statistical methods only consider when the microbiota are classified at one taxonomy level, not multiple.

Results: Using L1 and L2 regularizations, we developed a new variable selection method that identifies important features at multiple taxonomy levels. The regularization parameters are chosen by a new, data-adaptive, repeated cross-validation approach, which performed well. In simulation studies, our method outperformed competing methods: it more often selected significant variables, and had small false discovery rates and acceptable false-positive rates. Applying our method to gut microbiota data, we found which taxonomic levels were most altered by specific interventions or physiological status.

Availability: The new approach is implemented in an R package, which is freely available from the corresponding author.

Contact: tpgarcia@srph.tamhsc.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
African Americans
Authors: Young, Jr. Alford A.
Published: October 2013

African Americans have been the focus of wide-ranging studies in sociology for more than a century. Research on this group has been central to the formation of the sociological subfields of race and ethnic relations, urban sociology, and the sociology of identity. In these and other subfields, sociologists have explored how African Americans experienced the transition from the rural South to northeastern and midwestern urban-based communities (occurring from the early to the mid-20th century during a period labeled the Great Migration), how and why they engaged in social protest activities during the late 1950s and 1960s, and how they have experienced and confronted the increasing poverty and socioeconomic despair that unfolded in American cities since the middle of the 20th century. Sociologists also have explored the social identity of African Americans as that identity has been transformed since the mid-20th century and as it has affected, and been affected by, intellectual and political transformations in multiraciality, gender, sexual orientation, and other identities.
Electrophysiological Study for Nerve Root Entrapment in Patients With Isthmic Spondylolisthesis
Authors: Morita Masahiro , Miyauchi Akira , Okuda Shinya , Oda Takenori , Iwasaki Motoki
Published: October 2013

Study Design:

A case series study.

Objective:

To investigate the electrophysiological location of nerve root entrapment in patients with isthmic spondylolisthesis.

Summary of Background Data:

Although the lesion of the nerve root in patients with isthmic spondylolisthesis has been thought to be located at the pars interarticularis due to proliferation of fibrous cartilage, there is no electrophysiological study in relation to this accomplished fact.

Methods:

We performed an electrophysiological study in 12 patients with isthmic spondylolisthesis during surgery. All patients presented with low-grade isthmic spondylolisthesis and unilateral radiculopathy, and underwent single-level posterior lumbar interbody fusion with instrumentation. After a total facetectomy, nerve root action potentials were recorded by stimulating the ipsilateral peroneal nerve at the popliteal fossa. Four needle electrodes were inserted into the affected nerve root at the intraspinal canal, pars interarticularis, disk level, and extralateral to the disk. The waveforms that showed either a positive waveform pattern or polyphasic waveform pattern were regarded as abnormal potentials. We also confirmed surgical records and preoperative images to investigate the relationship to the electrophysiological findings.

Results:

An abnormal waveform pattern was demonstrated at the pars interarticularis in 6 patients, at the disk level in 5, and at the extralateral site in 1. On the basis of the electrophysiological findings of this study, the nerve root lesion was not always found on only the pars interarticularis in patients with isthmic spondylolisthesis. A relationship between the electrophysiological findings and surgical records or preoperative images was not found.

Conclusions:

The electrophysiological investigation in this study shows that the nerve root entrapment in patients with isthmic spondylolisthesis occurs not only at the pars interarticularis but also distal to the isthmus. This study suggests the possibility of insufficiency of decompression only at the pars interarticularis for patients with isthmic spondylolisthesis.
Exogenous Pigment in Peyer Patches of Children Suspected of Having IBD
Authors: Hummel Thalia Z. , Kindermann Angelika , Stokkers Pieter C.F. , Benninga Marc A. , ten Kate Fiebo J.W.
Published: October 2013

Objectives:

The base of human Peyer patches of the terminal ileum has been noted to contain black granular pigment deposits, composed of titanium dioxide and aluminosilicate, which are food additives typically present in a Western diet, and pharmaceuticals. In the present study, we investigated the distribution of exogenous pigment throughout the gastrointestinal tract of children suspected of having inflammatory bowel disease (IBD), the correlation between their age and the presence and amount of pigment in Peyer patches, and its relation to pediatric IBD.

Methods:

Biopsies (upper and lower gastrointestinal tract) from children suspected of having IBD who underwent endoscopy, were reassessed by a blinded, expert pathologist. The amount of pigment in biopsies was scored using a semiquantitative scale (range 0 to +++).

Results:

A total of 151 children were included: 62 with Crohn disease (CD), 26 with ulcerative colitis, and 63 with non‐IBD. In 63 children (42%), deposits of black pigment were found only in biopsies from the terminal ileum, located in Peyer patches. A significant correlation was found between increasing age and the amount of pigment (P = 0.004). Pigment deposits were found significantly less in the patients with CD compared with those in patients with ulcerative colitis and those with non‐IBD (26% vs 62% and 49%, P = 0.002).

Conclusions:

These results provide support for the hypothesis that the amount of pigment, only present in Peyer patches in the terminal ileum, becomes denser with increasing age. Absence of pigment in Peyer patches in a higher number of patients with CD suggests that microparticles may have become involved in the inflammatory process, possibly because of disrupted autophagy.
Comparison of Acoustic Radiation Force Impulse/Serum Noninvasive Markers for Fibrosis Prediction in Liver Transplant
Authors: Pinto Joana , Matos Hugo , Nobre Susana , Cipriano Maria A. , Marques Margarida , Pereira João M.S. , Gonçalves Isabel , Noruegas Maria J.
Published: October 2013

Objectives:

Fibrosis, related to several causes, can be diagnosed in children and adolescents' liver grafts that are >1 year old. At present, liver biopsy is the gold standard for assessing liver damage in the posttransplant setting. We aimed to evaluate the accuracy of noninvasive biomarkers of fibrosis, namely, acoustic radiation force impulse (ARFI), aspartate‐to‐platelet ratio index, and aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio index, either alone or in combination, for predicting fibrosis in pediatric patients submitted to liver transplantation.

Methods:

We prospectively assessed liver fibrosis in 30 children/adolescents with liver transplant through biopsy (liver transplant follow‐up during 12 months). ARFI with Virtual Touch Software (Acuson 2000) was performed, and blood samples were taken to determine liver function and platelet count. Two groups were analyzed according to the histopathologic stage of fibrosis, namely, none/mild (F0–F1) versus significant fibrosis (F2‐4).

Results:

The mean age of the 30 patients was 11 years (3–18 years), with a mean posttransplant period of assessment of 6.5 years. Twenty‐four patients (80%) presented stage F0–F1 fibrosis and 6 patients (20%) presented stage F2‐4. The area under the curve using receiver operating characteristic analysis for ARFI, aspartate‐to‐platelet ratio index, and AST/ALT ratio index for significant fibrosis was 0.76 (P = 0.052), 0.74 (P = 0.066), and 0.69 (P = 0.162), respectively. Through multivariate logistic regression analysis, the only independent predictor of significant fibrosis was ARFI (odds ratio 10.7, 95% confidence interval 1.2–95.7; P = 0.045). The combination of ARFI and AST/ALT ratio index presented a good diagnostic accuracy of fibrosis (area under the curve of 0.83; P = 0.013).

Conclusions:

ARFI may serve as a potential method for assessing significant fibrosis in pediatric patients with liver transplant, particularly in combination with AST/ALT ratio index.
TheArabidopsisEukaryotic Translation Initiation Factor eIF5A-2 Regulates Root Protoxylem Development by Modulating Cytokinin Signaling
Authors: Ren Bo , Chen Qingguo , Hong Sulei , Zhao Wenming , Feng Jian , Feng Haizhong , Zuo Jianru
Published: October 2013

The phytohormone cytokinin regulates various aspects of plant growth and development, including root vascular development. In Arabidopsis thaliana, mutations in the cytokinin signaling components cause misspecification of protoxylem cell files. Auxin antagonizes cytokinin-regulated root protoxylem differentiation by inducing expression of ARABIDOPSIS PHOSPHOTRANSFER PROTEIN6 (AHP6), a negative regulator of cytokinin signaling. However, the molecular mechanism of cytokinin-regulated protoxylem differentiation is not fully understood. Here, we show that a mutation in Arabidopsis FUMONISIN B1-RESISTANT12 (FBR12), which encodes a eukaryotic translation initiation factor 5A, causes defective protoxylem development and reduced sensitivity to cytokinin. FBR12 genetically interacts with the cytokinin receptor CYTOKININ RESPONSE1 (CRE1) and downstream AHP genes, as double mutants show enhanced phenotypes. FBR12 forms a protein complex with CRE1 and AHP1, and cytokinin regulates formation of this protein complex. Intriguingly, ahp6 partially suppresses the fbr12 mutant phenotype, and the fbr12 mutation causes increased expression of AHP6, indicating that FBR12 negatively regulates AHP6. Consistent with this, ectopic expression of FBR12 in the CRE1-expressing domain partially rescues defective protoxylem development in fbr12, and overexpression of AHP6 causes an fbr12-like phenotype. These results define a regulatory role of the highly conserved FBR12 in cytokinin-mediated root protoxylem specification.
Are saving and investment cointegrated: evidence from some African countries' data
Authors: Odulukwe Onwuka Kevin , Obiefuna Augustine
Published: October 2013

Purpose

– The purpose of this paper is to test the Feldstein and Horioka (FH), theory that capital mobility should be low if there is high correlation between saving and investment, in some African countries.

Design/methodology/approach

– This paper tests the cointegration between saving and investment using bounds testing approach to cointegration and derive the long-run elasticities using autoregressive-distributed lag (ARDL) and Phillips-Hansen fully modified OLS for African countries over the period 1960-2008. This paper conducted the test for unit root properties using Augumented Dick-Fuller procedure.

Findings

– Their main findings are: investment and saving are strongly cointegrated for The Gambia and Burkina Faso and marginally cointegrated for Ghana, Mali, Cote d'Ivoire and Benin when investment is the dependent variable and there is evidence of cointegration between saving and investment when saving is the dependent variable for Senegal and Niger and no evidence of cointegration for Cameroon, Chad and Togo; the long-run coefficients on saving are low or negative implying low correlation. This paper concludes that Feldstein and Horioka theory could not be ruled out in African countries investigated.

Originality/value

– This paper is the original paper conducted on West African countries. This study has not across any paper bearing the same title on the countries of coverage.
One man's trash
Authors: McMullen Anthony
Published: October 2013

Purpose

– This paper aims to provide insights into issues encountered in maintaining library technologies and electronic collections in changing times and on a limited budget with limited personnel.

Design/methodology/approach

– The paper uses real-world experiences and anecdotal evidence to provide commentary on progress and the future of libraries as it relates to letting go of traditional practices and procedures and embracing new ideas and directions.

Findings

– Weeding a large collection of materials with limited personnel and finances is no easy task. Aside from the functional aspects of handling and processing thousands of volumes there are emotional aspects to discarding that can be overwhelming for some. There is also the fear that one may be throwing away something useful or valuable.

Originality/value

– This paper is a light hearted piece on one librarian's experiences in taking part in a large-scale weeding project.
Nigeria in transition: acculturation to global consumer culture
Authors: Lysonski Steven , Durvasula Srinivas
Published: October 2013

Purpose

– The purpose of this paper is to investigate the extent to which young urban Nigerians in Lagos have become acculturated to global consumer culture and the impact of acculturation on consumer ethnocentrism and materialism.

Design/methodology/approach

– A total of 165 young Nigerians living in Lagos completed a survey. The survey scales consisted of seven different dimensions of global consumer acculturation, ethnocentrism, materialism and demographics. All scales had strong reliabilities.

Findings

– Nigerians were acculturated to a large degree in terms of cosmopolitan tendency, exposure to marketing activities of multinationals, English language usage, social interactions, and global mass media exposure. However, openness to emulate global consumer culture was moderate and identification with global consumer culture was very low. Acculturation affected consumer ethnocentrism and materialism to some extent.

Research limitations/implications

– Only one segment of consumers in Nigeria was examined. Because the original scale for global consumer acculturation lacked psychometric rigor, we revised it using psychometric purification.

Practical implications

– Nigerians may be in a state of transition as they adapt to global consumer culture. Nigerians may have some resistance in adapting to global consumer culture given ideological, nationalistic, and socio-economic conditions. International marketers must realize that a level of “glocalization” is required attuned to the identify and national character of Nigerians. The authors discuss the paradox that Nigerians have low identification with global consumer culture despite their exposure to global forces.

Originality/value

– No other research has used the authors’ approach. The paper provides a fresh way of looking at Nigeria as it transitions into a global market and advances our understanding the connection of global consumer culture with ethnocentrism and materialism. The research can serve as a catalyst in looking at global consumer culture in Africa and in BRIC countries.
Requirements for vocabulary preservation and governance
Authors: Baker Thomas , Vandenbussche Pierre-Yves , Vatant Bernard
Published: October 2013

Purpose

– The paper seeks to analyze the health of the vocabulary ecosystem in terms of requirements, addressing its various stakeholders such as maintainers of linked open vocabularies, linked data providers who use those vocabularies in their data and memory institutions which, it is hoped, will eventually provide for the long-term preservation of vocabularies.

Design/methodology/approach

– This paper builds on requirements formulated more tersely in the DCMI generic namespace policy for RDF vocabularies. The examination of requirements for linked open vocabularies focuses primarily on property-and-class vocabularies in RDFS or OWL (sometimes called metadata element sets), with some consideration of SKOS concept schemes and Dublin Core application profiles. It also discusses lessons learned through two years of development of the linked open vocabularies (LOV), of which main features and key findings are described.

Findings

– Key findings about the current practices of vocabulary managers regarding metadata, policy and versioning are presented, as well as how such practices can be improved to ensure better discoverability and usability of RDF vocabularies. The paper presents new ways to assess the links and dependencies between vocabularies. It also stresses the necessity and importance of a global governance of the ecosystem in which vocabulary managers, standard bodies, and memory institutions should engage.

Research limitations/implications

– The current paper is focused on requirements related to a single type of vocabulary but could and should be extended to other types such as thesauri, classifications, and other semantic assets.

Practical implications

– Practical technical guidelines and social good practices are proposed for promotion in the Vocabulary Ecosystem (for example, by vocabulary managers).

Originality/value

– This paper brings together the research and action of several important actors in the vocabulary management and governance field, and is intended to be the basis of a roadmap for action presented at the Dublin Core conference of September 2013 in Lisbon (DC 2013).