bluuebunny/crossref_metadata_2025 huggingface dataset:
Problem-free time-dependent variational principle for open quantum systems
Authors: Joubert-Doriol Loïc , Izmaylov Artur F.
Published: April 2015

Methods of quantum nuclear wave-function dynamics have become very efficient in simulating large isolated systems using the time-dependent variational principle (TDVP). However, a straightforward extension of the TDVP to the density matrix framework gives rise to methods that do not conserve the energy in the isolated system limit and the total system population for open systems where only energy exchange with environment is allowed. These problems arise when the system density is in a mixed state and is simulated using an incomplete basis. Thus, the basis set incompleteness, which is inevitable in practical calculations, creates artificial channels for energy and population dissipation. To overcome this unphysical behavior, we have introduced a constrained Lagrangian formulation of TDVP applied to a non-stochastic open system Schrödinger equation [L. Joubert-Doriol, I. G. Ryabinkin, and A. F. Izmaylov, J. Chem. Phys. 141, 234112 (2014)]. While our formulation can be applied to any variational ansatz for the system density matrix, derivation of working equations and numerical assessment is done within the variational multiconfiguration Gaussian approach for a two-dimensional linear vibronic coupling model system interacting with a harmonic bath.
Infrared rovibrational spectroscopy of OH–C2H2 in 4He nanodroplets: Parity splitting due to partially quenched electronic angular momentum
Authors: Douberly Gary E. , Raston Paul L. , Liang Tao , Marshall Mark D.
Published: April 2015

The T-shaped OH–C2H2 complex is formed in helium droplets via the sequential pick-up and solvation of the monomer fragments. Rovibrational spectra of the a-type OH stretch and b-type antisymmetric CH stretch vibrations contain resolved parity splitting that reveals the extent to which electronic angular momentum of the OH moiety is quenched upon complex formation. The energy difference between the spin-orbit coupled 2B1 (A″) and 2B2 (A′) electronic states is determined spectroscopically to be 216 cm−1 in helium droplets, which is 13 cm−1 larger than in the gas phase [Marshall et al., J. Chem. Phys. 121, 5845 (2004)]. The effect of the helium is rationalized as a difference in the solvation free energies of the two electronic states. This interpretation is motivated by the separation between the Q(3/2) and R(3/2) transitions in the infrared spectrum of the helium-solvated 2Π3/2 OH radical. Despite the expectation of a reduced rotational constant, the observed Q(3/2) to R(3/2) splitting is larger than in the gas phase by ≈0.3 cm−1. This observation can be accounted for quantitatively by assuming the energetic separation between 2Π3/2 and 2Π1/2 manifolds is increased by ≈40 cm−1 upon helium solvation.
Evaluation of the exothermicity of the chemi-ionization reaction Sm + O → SmO+ + e−
Authors: Cox Richard M , Kim JungSoo , Armentrout P. B. , Bartlett Joshua , VanGundy Robert A. , Heaven Michael C. , Ard Shaun G. , Melko Joshua J. , Shuman Nicholas S. , Viggiano Albert A.
Published: April 2015

The exothermicity of the chemi-ionization reaction Sm + O → SmO+ + e− has been re-evaluated through the combination of several experimental methods. The thermal reactivity (300–650 K) of Sm+ and SmO+ with a range of species measured using a selected ion flow tube-mass spectrometer apparatus is reported and provides limits for the bond strength of SmO+, 5.661 eV ≤ D0(Sm+-O) ≤ 6.500 eV. A more precise value is measured to be 5.725 ± 0.07 eV, bracketed by the observed reactivity of Sm+ and SmO+ with several species using a guided ion beam tandem mass spectrometer (GIBMS). Combined with the established Sm ionization energy (IE), this value indicates an exothermicity of the title reaction of 0.08 ± 0.07 eV, ∼0.2 eV smaller than previous determinations. In addition, the ionization energy of SmO has been measured by resonantly enhanced two-photon ionization and pulsed-field ionization zero kinetic energy photoelectron spectroscopy to be 5.7427 ± 0.0006 eV, significantly higher than the literature value. Combined with literature bond energies of SmO, this value indicates an exothermicity of the title reaction of 0.14 ± 0.17 eV, independent from and in agreement with the GIBMS result presented here. The evaluated thermochemistry also suggests that D0(SmO) = 5.83 ± 0.07 eV, consistent with but more precise than the literature values. Implications of these results for interpretation of chemical release experiments in the thermosphere are discussed.
Eigenspectra and mode coalescence of temporal instability in two-phase channel flow
Authors: Kaffel Ahmed , Riaz Amir
Published: April 2015

The stability of two immiscible fluids with different densities and viscosities is examined for channel flow. A multi-domain Chebyshev collocation spectral method is used for solving the coupled Orr-Sommerfeld stability equations for the entire spectrum of eigenvalues and associated eigenfunctions. Numerical solution of the eigenvalue problem is obtained with the QZ eigenvalue solver and is validated with analytical results derived in the long and short wave limits. A parametric study is carried out to investigate the spectral characteristics and eigenfunction structures related to the shear and interfacial modes of instability. The interactions and mode switching between the two instability modes are investigated. Under certain conditions, the two modes are found to become unstable simultaneously. Mode coalescence can occur in either the stable or the unstable part of the spectrum. In general, the eigenfunction of the most dangerous mode is observed to vary sharply in the neighborhood of the interface and the critical points.
Electromagnetic effects on turbulent transport in high-performance ASDEX Upgrade discharges
Authors: Doerk H. , Dunne M. , Jenko F. , Ryter F. , Schneider P. A. , Wolfrum E. ,   The ASDEX Upgrade Team
Published: April 2015

Modern tokamak H-mode discharges routinely operate at high plasma beta. Dedicated experiments performed on multiple machines measure contradicting dependence of the plasma confinement on this important parameter. In view of designing high-performance scenarios for next-generation devices like ITER, a fundamental understanding of the involved physics is crucial. Theoretical results—most of which have been obtained for simplified setups—indicate that increased beta does not only modify the characteristics of microturbulence but also potentially introduces fundamentally new physics. Empowered by highly accurate measurements at ASDEX Upgrade, the GENE turbulence code is used to perform a comprehensive gyrokinetic study of dedicated H-Mode plasmas. We find the stabilization of ion-temperature-gradient driven turbulence to be the most pronounced beta effect in these experimentally relevant cases. The resulting beta-improved core confinement should thus be considered for extrapolations to future machines.
Coupling of the interfacial and bulk flow in knife-edge viscometers
Authors: Lopez Juan M. , Hirsa Amir H.
Published: April 2015

The operation of the knife-edge viscometer requires knowledge of the interfacial velocity profile in order to determine the viscous traction between the surface film and the knife edge and hence measure the surface shear viscosity of the film. The interfacial velocity profile can be obtained analytically in two limiting regimes. One is the limit of the surface shear viscosity going to infinity, in which case the interfacial velocity profile is independent of the bulk flow and a simple analytic expression is available. The other limit corresponds to vanishing bulk flow inertia, allowing one to reduce the Navier–Stokes equations to the Stokes equation, and the resulting linear system can be solved analytically. For finite inertia and finite surface shear viscosity, the knife-edge viscometer hydrodynamics is governed by the coupled nonlinear set of equations. Here, we study these numerically, explore the coupling between the interfacial and bulk flow, and delineate the ranges of surface shear viscosity and knife-edge rotation rates where the analytic approximations are appropriate. We also examine a variant of the knife-edge viscometer, known as the double-wall ring viscometer, which is essentially the same geometry but with the addition of a stationary inner cylinder so that the bulk fluid is contained in an annular channel rather than a cylinder.
Tunable and white light emitting AlPO4 mesoporous glass by design of inorganic/organic luminescent species
Authors: He Jin , Wang Yan , Li Rihong , Yuan Xinqiang , Xu Shiqing , Zhang Long
Published: April 2015

The realization of tunable and white light emitting sources employed by UV-LED with single-host phosphors has been an exciting development in the search for high luminous efficiency and excellent color rendering index white-light source. A tunable and white light emitting mesoporous glass was prepared by utilizing both inorganic/organic (Europium/coumarin) luminescent species in the meso-structure. The tunable and white light emission was deliberately designed by CIE calculation based on the individual emission spectra, which was realized by tailoring the emission of Eu2+/Eu3+ ions and coumarin 535 in sol-gel AlPO4 mesoporous glass. This simple and versatile procedure is not limited in the combination of rare earth and organic dye and is therefore extendable to other luminescent species in meso-structure for color-tunable efficient solid-state lighting sources.
Electron-phonon coupling and thermal conductance at a metal-semiconductor interface: First-principles analysis
Authors: Sadasivam Sridhar , Waghmare Umesh V. , Fisher Timothy S.
Published: April 2015

The mechanism of heat transfer and the contribution of electron-phonon coupling to thermal conductance of a metal-semiconductor interface remains unclear in the present literature. We report ab initio simulations of a technologically important titanium silicide (metal)–silicon (semiconductor) interface to estimate the Schottky barrier height, and the strength of electron-phonon and phonon-phonon heat transfer across the interface. The electron and phonon dispersion relations of TiSi2 with C49 structure and the TiSi2-Si interface are obtained using first-principles calculations within the density functional theory framework. These are used to estimate electron-phonon linewidths and the associated Eliashberg function that quantifies coupling. We show that the coupling strength of electrons with interfacial phonon modes is of the same order of magnitude as coupling of electrons to phonon modes in the bulk metal, and its contribution to electron-phonon interfacial conductance is comparable to the harmonic phonon-phonon conductance across the interface.
Terahertz magneto-optics in the ferromagnetic semiconductor HgCdCr2Se4
Authors: Huisman T. J. , Mikhaylovskiy R. V. , Telegin A. V. , Sukhorukov Yu. P. , Granovsky A. B. , Naumov S. V. , Rasing Th. , Kimel A. V.
Published: April 2015

The magneto-optical response of the ferromagnetic semiconductor HgCdCr2Se4 at terahertz (THz) frequencies is studied using polarization sensitive THz time-domain spectroscopy. It is shown that the polarization state of broadband terahertz pulses, with a spectrum spanning from 0.2 THz to 2.2 THz, changes as an even function of the magnetization of the medium. Analysing the ellipticity and the rotation of the polarization of the THz radiation, we show that these effects originate from linear birefringence and dichroism, respectively, induced by the magnetic ordering. These effects are rather strong and reach 102 rad/m at an applied field of 1 kG which saturates the magnetization of the sample. Our observation serves as a proof-of-principle showing strong effects of the magnetic order on the response of a medium to electric fields at THz frequencies. These experiments also suggest the feasibility of spin-dependent transport measurements on a sub-picosecond timescale.
Research Update: New possibilities for the nanoscale engineering of complex oxide thin films
Authors: McMitchell S. R. C.
Published: April 2015

Complex oxides are becoming engrained into modern technology. Understanding the growth and properties of these materials is extremely important for development of novel devices and optimization of existing technologies. Control of the growth of thin film oxides is essential to facilitate the fine-tuning of properties needed for device optimization. In this article, some recent advances in nanoscale engineering of functional oxides are summarized. Control of film structure through manipulation of growth kinetics and substrate considerations is discussed. The construction of composites and artificial materials is also considered. Furthermore, a future outlook is investigated including a route to industrial scale application.
High-frequency properties of oriented hcp-Co1−xIrx (0.06 ≤ x ≤ 0.24) soft magnetic films
Authors: Xu Fei , Zhang Sha , Yang Dezheng , Wang Tao , Li Fashen
Published: April 2015

In this work, the composition dependence of high-frequency magnetic properties for the oriented hcp-Co1−xIrx soft magnetic films with negative uniaxial magnetocrystalline anisotropy (Kugrain) and in-plane uniaxial anisotropy field (Hu) is investigated. Both the saturation magnetization (Ms), Kugrain, and Hu are greatly affected by the composition of Ir. The (μi−1)⋅fr of Co1−xIrx (with negative Kugrain) is larger than Acher's limit (without Kugrain) when x exceeds 0.14. The increasing percent of (μi−1)⋅fr could get a maximum of 42% when x is 0.2.
Stoichiometry control of complex oxides by sequential pulsed-laser deposition from binary-oxide targets
Authors: Herklotz A. , Dörr K. , Ward T. Z. , Eres G. , Christen H. M. , Biegalski M. D.
Published: April 2015

To have precise atomic layer control over interfaces, we examine the growth of complex oxides through the sequential deposition from binary targets by pulsed laser deposition. In situ reflection high-energy electron diffraction (RHEED) is used to control the growth and achieve films with excellent structural quality. The growth from binary oxide targets is fundamentally different from single target growth modes and shows more similarities to shuttered growth by molecular beam epitaxy. The RHEED intensity oscillations of non-stoichiometric growth are consistent with a model of island growth and accumulation of excess material on the surface that can be utilized to determine the correct stoichiometry for growth. Correct monolayer doses can be determined through an envelope frequency in the RHEED intensity oscillations. In order to demonstrate the ability of this growth technique to create complex heterostructures, the artificial n = 2 and 3 Srn+1TinO3n+1 Ruddlesden-Popper phases are grown with good long-range order. This method enables the precise unit-cell level control over the structure of perovskite-type oxides, and thus the growth of complex materials with improved structural quality and electronic functionality.
Note: Determining the detection efficiency of excited neutral atoms by a microchannel plate detector
Authors: Berry Ben , Zohrabi M. , Hayes D. , Ablikim U. , Jochim Bethany , Severt T. , Carnes K. D. , Ben-Itzhak I.
Published: April 2015

We present a method for determining the detection efficiency of neutral atoms relative to keV ions. Excited D* atoms are produced by D2 fragmentation in a strong laser field. The fragments are detected by a micro-channel plate detector either directly as neutrals or as keV ions following field ionization and acceleration by a static electric field. Moreover, we propose a new mechanism by which neutrals are detected. We show that the ratio of the yield of neutrals and ions can be related to the relative detection efficiency of these species.
Universal features of phonon transport in nanowires with correlated surface roughness
Authors: Maurer L. N. , Aksamija Z. , Ramayya E. B. , Davoody A. H. , Knezevic I.
Published: April 2015

The ultralow thermal conductivity, κ, observed experimentally in intentionally roughened silicon nanowires (SiNWs) is reproduced in phonon Monte Carlo simulations with exponentially correlated real-space rough surfaces similar to measurement [J. Lim et al., Nano Lett. 12, 2475 (2012)]. Universal features of thermal transport are revealed by presenting κ as a function of the normalized geometric mean free path λ¯ (0<λ¯<1); the diffusive (Casimir) limit corresponds to λ¯=1/2. κ vs λ¯ is exponential at low-to-moderate roughness (high λ¯), where internal scattering randomly interrupts phonon bouncing across the SiNW, and linear at high roughness (low λ¯), where multiple scattering events at the same surface results in ultralow, amorphous-limit thermal conductivity.
Spin wave differential circuit for realization of thermally stable magnonic sensors
Authors: Goto Taichi , Kanazawa Naoki , Buyandalai Altansargai , Takagi Hiroyuki , Nakamura Yuichi , Okajima Shingo , Hasegawa Takashi , Granovsky Alexander B. , Sekiguchi Koji , Ross Caroline A. , Inoue Mitsuteru
Published: April 2015

A magnetic-field sensor with a high sensitivity of 38 pT/Hz was demonstrated. By utilizing a spin-wave differential circuit (SWDC) using two yttrium iron garnet (YIG) films, the temperature sensitivity was suppressed, and the thermal stability of the phase of the spin waves was −0.0095° K−1, which is three orders of magnitude better than a simple YIG-based sensor, ∼20° K−1. The SWDC architecture opens the way to design YIG-based magnonic devices.
Left-handed metastructures with selective frequency transmission window for gigahertz shielding applications
Authors: Ababei G. , Olariu C. S. , Lupu N. , Chiriac H.
Published: April 2015

Experimental evidence of left-handed properties of the Fe-, CoFe-, and Co-based glass-covered amorphous microwires in free standing systems is demonstrated. A new broadband frequency shielding metastructure with selective transmission frequency in the microwave range is presented. The X-band microwave-guide and the free-space methods were used as experimental techniques in the frequency range from 1 to 12 GHz. The X-band experimental results show that the mixed metastructure presents left-handed behavior between 8.5 and 10.5 GHz. The mixed metastructure for large areas presents broadband frequency domains, with left-handed properties between 6.5 and 10.5 GHz (the sum of intrinsic ferromagnetic and antiferromagnetic resonance frequencies domains of individual microwires) and a transmission window between 7.6 and 10.5 GHz. Double negative characteristics of the metastructures are in agreement with the computed results calculated based on Landau–Lifshitz–Gilbert equations and Nicolson-Ross-Weir analytical method.
Stress-induced resistivity changes in a Ni-Mn-In alloy
Authors: Kokorin V. V. , Konoplyuk S. M. , Dalinger A. , Thürer S. , Gerstein G. , Maier H. J.
Published: April 2015

The elastoresistive effect is reported in polycrystalline Ni45.4Mn40In14.6 metamagnetic alloy at uniaxial compression: abrupt growth of electric resistance by more than 30% occurs when the applied mechanical stress achieves 16 MPa. In the process of deformation at temperature 23 K above martensitic transition, the alloy demonstrated superelastic behavior. Surface morphology of specimen at different strain levels was monitored in situ by optical microscopy. The observations showed that after compressive deformation up to 5% followed by unloading specimen fully reverted back to parent phase.
Localized conductive patterning via focused electron beam reduction of graphene oxide
Authors: Kim Songkil , Kulkarni Dhaval D. , Henry Mathias , Zackowski Paul , Jang Seung Soon , Tsukruk Vladimir V. , Fedorov Andrei G.
Published: April 2015

We report on a method for “direct-write” conductive patterning via reduction of graphene oxide (GO) sheets using focused electron beam induced deposition (FEBID) of carbon. FEBID treatment of the intrinsically dielectric graphene oxide between two metal terminals opens up the conduction channel, thus enabling a unique capability for nanoscale conductive domain patterning in GO. An increase in FEBID electron dose results in a significant increase of the domain electrical conductivity with improving linearity of drain-source current vs. voltage dependence, indicative of a change of graphene oxide electronic properties from insulating to semiconducting. Density functional theory calculations suggest a possible mechanism underlying this experimentally observed phenomenon, as localized reduction of graphene oxide layers via interactions with highly reactive intermediates of electron-beam-assisted dissociation of surface-adsorbed hydrocarbon molecules. These findings establish an unusual route for using FEBID as nanoscale lithography and patterning technique for engineering carbon-based nanomaterials and devices with locally tailored electronic properties.
Toward major evolutionary transitions theory 2.0
Authors: Szathmáry Eörs
Published: April 2015

The impressive body of work on the major evolutionary transitions in the last 20 y calls for a reconstruction of the theory although a 2D account (evolution of informational systems and transitions in individuality) remains. Significant advances include the concept of fraternal and egalitarian transitions (lower-level units like and unlike, respectively). Multilevel selection, first without, then with, the collectives in focus is an important explanatory mechanism. Transitions are decomposed into phases of origin, maintenance, and transformation (i.e., further evolution) of the higher level units, which helps reduce the number of transitions in the revised list by two so that it is less top-heavy. After the transition, units show strong cooperation and very limited realized conflict. The origins of cells, the emergence of the genetic code and translation, the evolution of the eukaryotic cell, multicellularity, and the origin of human groups with language are reconsidered in some detail in the light of new data and considerations. Arguments are given why sex is not in the revised list as a separate transition. Some of the transitions can be recursive (e.g., plastids, multicellularity) or limited (transitions that share the usual features of major transitions without a massive phylogenetic impact, such as the micro- and macronuclei in ciliates). During transitions, new units of reproduction emerge, and establishment of such units requires high fidelity of reproduction (as opposed to mere replication).
PLZF expression maps the early stages of ILC1 lineage development
Authors: Constantinides Michael G. , Gudjonson Herman , McDonald Benjamin D. , Ishizuka Isabel E. , Verhoef Philip A. , Dinner Aaron R. , Bendelac Albert
Published: April 2015

Significance

Diverse populations of group 1 innate lymphocytes, which exert critical early cytolytic functions against virally infected cells, have recently been discovered, raising issues of lineage relationships. We used expression of the transcription factor promyelocytic leukaemia zinc finger (PLZF) to identify the developmental intermediates of innate lymphoid cells type 1 (ILC1s), a subset of innate lymphoid cells that are particularly abundant in the liver, and demonstrated that this lineage arises from a distinct precursor, but that its development partially overlaps with established classical NK stages. Using microarray analysis, we defined a set of PLZF-dependent genes that may contribute to lineage divergence between ILC1s and classical NK cells.
Temporal prepositions explained
Authors: Johansson Falck Marlene
Published: April 2015

To what extent can factors such as the size of a unit of time landmark and zoomed in effects explain the patterns of temporal prepositions in English (Lindstromberg, 1998/2010)? How important are these factors cross-linguistically? This paper is a corpus linguistic analysis of unit of time landmarks in Englishinandoninstances, and in their Swedish equivalents,iandpåinstances. My aims are to investigate how temporalinandonrelationships are construed in terms of spatial ones and to identify shared and differing patterns between these two closely related languages. Shared patterns may provide clues in regard to which factors are salient when time is construed in terms of space. Differing patterns highlight the fact that a given way of construing time in terms of space is not the only alternative. Systematicity at this level of abstraction is potentially useful for the second language (L2) learner.
The development of the modal and discourse marker uses of (there/it is/I have)no doubt
Authors: Davidse Kristin , De Wolf Simon , Van linden An
Published: April 2015

In this paper, we reconstruct the emergence of the modal and discourse marker uses of adverbial and clausal expressions withno doubt. Their history contrasts in a number of surprising ways with typical grammaticalization hypotheses. Existential expressions withno doubtemerged directly with grammatical modal meaning and developed lexicalized idiomatic uses later on. We account for this in terms of Boye and Harder’s discourse approach to grammaticalization and lexicalization, according to which the former involves coded discourse secondariness whereas the latter expresses a primary point of the discourse. Like adverbialno doubt,I have/make no doubtacquired uses not only as a modal but also as a discourse marker. Invoking the principles of Kaltenböck, Heine and Kuteva’s Thetical Grammar, we explain this development in terms of the positional and scopal flexibility, and the discourse functionality of these expressions.
Morphological contrasts between Modern Greek and Italian
Authors: Giannoulopoulou Giannoula
Published: April 2015

The aim of this paper is to discuss topics in contrastive morphology, combining the perspectives of morphological theory and contrastive linguistics. After an overview of the recent literature on contrastive morphology and the relevant ‘tertia comparationis’ in Section 2, Section 3 focuses on the main differences between compounding in Modern Greek and Italian (e.g. the position of the morphological head, the pattern stem+stem in Modern Greek vs. the pattern word+word in Italian). The diachronic dimension, the inflectional system and the role of syntax are put forward as explanatory factors for the differences between the two languages. Two recent types of compounds, [V+V] V in Modern Greek and [V+N] N in Italian, are therefore examined contrastively. The contrastive analysis of compounding is based on three types of equivalence: ‘system equivalence’, ‘rule equivalence’, and ‘morphological age equivalence’. The main conclusion is that a contrastive approach to morphology enables us to deepen our understanding of both the fundamental distinction and the fundamental interconnection between morphology and syntax.
Combinatorics of tight geodesics and stable lengths
Authors: Webb Richard
Published: April 2015

We give an algorithm to compute the stable lengths of pseudo-Anosovs on the curve graph, answering a question of Bowditch. We also give a procedure to compute all invariant tight geodesic axes of pseudo-Anosovs.

Along the way we show that there are constants

1
>

a
1

>

a
2

1>a_1>a_2

such that the minimal upper bound on ‘slices’ of tight geodesics is bounded below and above by

a
1

ξ
(
S
)

a_1^{\xi (S)}

and

a
2

ξ
(
S
)

a_2^{\xi (S)}

, where

ξ
(
S
)

\xi (S)

is the complexity of the surface. As a consequence, we give the first computable bounds on the asymptotic dimension of curve graphs and mapping class groups.

Our techniques involve a generalization of Masur–Minsky’s tight geodesics and a new class of paths on which their tightening procedure works.
Cryptococcal Antigenemia in Immunocompromised Human Immunodeficiency Virus Patients in Rural Tanzania: A Preventable Cause of Early Mortality
Authors: Letang Emilio , Müller Matthias C. , Ntamatungiro Alex J. , Kimera Namvua , Faini Diana , Furrer Hansjakob , Battegay Manuel , Tanner Marcel , Hatz Christoph , Boulware David R. , Glass Tracy R.
Published: April 2015

Background.  Cryptococcal meningitis is a leading cause of death in people living with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome. The World Health Organizations recommends pre-antiretroviral treatment (ART) cryptococcal antigen (CRAG) screening in persons with CD4 below 100 cells/µL. We assessed the prevalence and outcome of cryptococcal antigenemia in rural southern Tanzania.

Methods.  We conducted a retrospective study including all ART-naive adults with CD4 <150 cells/µL prospectively enrolled in the Kilombero and Ulanga Antiretroviral Cohort between 2008 and 2012. Cryptococcal antigen was assessed in cryopreserved pre-ART plasma. Cox regression estimated the composite outcome of death or loss to follow-up (LFU) by CRAG status and fluconazole use.

Results.  Of 750 ART-naive adults, 28 (3.7%) were CRAG-positive, corresponding to a prevalence of 4.4% (23 of 520) in CD4 <100 and 2.2% (5 of 230) in CD4 100–150 cells/µL. Within 1 year, 75% (21 of 28) of CRAG-positive and 42% (302 of 722) of CRAG-negative patients were dead or LFU (P<.001), with no differences across CD4 strata. Cryptococcal antigen positivity was an independent predictor of death or LFU after adjusting for relevant confounders (hazard ratio [HR], 2.50; 95% confidence interval [CI], 1.29–4.83; P = .006). Cryptococcal meningitis occurred in 39% (11 of 28) of CRAG-positive patients, with similar retention-in-care regardless of meningitis diagnosis (P = .8). Cryptococcal antigen titer >1:160 was associated with meningitis development (odds ratio, 4.83; 95% CI, 1.24–8.41; P = .008). Fluconazole receipt decreased death or LFU in CRAG-positive patients (HR, 0.18; 95% CI, .04–.78; P = .022).

Conclusions.  Cryptococcal antigenemia predicted mortality or LFU among ART-naive HIV-infected persons with CD4 <150 cells/µL, and fluconazole increased survival or retention-in-care, suggesting that targeted pre-ART CRAG screening may decrease early mortality or LFU. A CRAG screening threshold of CD4 <100 cells/µL missed 18% of CRAG-positive patients, suggesting guidelines should consider a higher threshold.
Effects of emergency department crowding on the delivery of timely care in an inner-city hospital in the Netherlands
Authors: van der Linden Naomi , van der Linden M. Christien , Richards John R. , Derlet Robert W. , Grootendorst Diana C. , van den Brand Crispijn L.
Published: April 2015

Background

The impact of delays in emergency department (ED) care has not been described in European countries where ED crowding is not universally recognized. The aim of this study was to determine the relationship of ED crowding with delays in triage and treatment, and 24-h mortality in patients admitted to the ED.

Methods

Five years of data from adults admitted to the hospital were analysed retrospectively from an inner-city ED in the Netherlands. Variables included the following: crowded versus noncrowded time, time to triage, triage category, time to treatment, age, 24-h mortality and 10-day mortality.

Results

A total of 39 110 patients met the inclusion criteria. ED crowding occurred 30.8% of the time. There were no differences in mortality between patients arriving during crowding versus those arriving during noncrowding. Delays in triage during ED crowding occurred 29.7% of the time versus 14.6% during noncrowding. Delays in treatment occurred 11.7 and 7.3% of the time during crowding and noncrowding, respectively.

Conclusion

In this hospital, ED crowding results in increased times to triage and to treatment, not in increased 24-h or 10-day mortality.
Case Study: Ticagrelor in PLATO and Prasugrel in TRITON-TIMI 38 and TRILOGY-ACS Trials in Patients With Acute Coronary Syndromes
Authors: Husted Steen , Boersma Eric
Published: April 2015

Cross-trial comparisons are typically inappropriate as there are often numerous differences in study designs, populations, end points, and loading doses of the study drugs. These differences are clearly reflected in the most recent updates to the European Society of Cardiology (ESC) non-ST elevation acute coronary syndrome (NSTE-ACS) and ST elevation myocardial infarction (STEMI) guidelines, which include recommendations for the use of the antiplatelet agents ticagrelor, prasugrel, and clopidogrel, based in part on results from the TRial to assess Improvement in Therapeutic Outcomes by optimizing platelet inhibitioN with prasugrel–Thrombolysis In Myocardial Infarction (TRITON-TIMI) 38, TaRgeted platelet Inhibition to cLarify the Optimal strateGy to medicallY manage Acute Coronary Syndromes (TRILOGY-ACS) and PLATelet inhibition and patient Outcomes (PLATO) trials. Here, we describe each of these trials in detail and explain the differences between them that make direct comparisons difficult. In conclusion, this information, along with the current guidelines and recommendations, will assist clinicians in deciding the most appropriate treatment pathway for their patients with NSTE-ACS and STEMI.
Integrated whole‐genome screening for Pseudomonas aeruginosa virulence genes using multiple disease models reveals that pathogenicity is host specific
Authors: Dubern Jean‐Frédéric , Cigana Cristina , De Simone Maura , Lazenby James , Juhas Mario , Schwager Stephan , Bianconi Irene , Döring Gerd , Eberl Leo , Williams Paul , Bragonzi Alessandra , Cámara Miguel
Published: April 2015

Pseudomonas aeruginosa is a multi‐host opportunistic pathogen causing a wide range of diseases because of the armoury of virulence factors it produces, and it is difficult to eradicate because of its intrinsic resistance to antibiotics. Using an integrated whole‐genome approach, we searched for P. aeruginosa virulence genes with multi‐host relevance. We constructed a random library of 57 360 Tn5 mutants in P. aeruginosa PAO1‐L and screened it in vitro for those showing pleiotropic effects in virulence phenotypes (reduced swarming, exo‐protease and pyocyanin production). A set of these pleiotropic mutants were assayed for reduced toxicity in Drosophila melanogaster, Caenorhabditis elegans, human cell lines and mice. Surprisingly, the screening revealed that the virulence of the majority of P. aeruginosa mutants varied between disease models, suggesting that virulence is dependent on the disease model used and hence the host environment. Genomic analysis revealed that these virulence‐related genes encoded proteins from almost all functional classes, which were conserved among P. aeruginosa strains. Thus, we provide strong evidence that although P. aeruginosa is capable of infecting a wide range of hosts, many of its virulence determinants are host specific. These findings have important implication when searching for novel anti‐virulence targets to develop new treatments against P. aeruginosa.
rRNA regulation during growth and under stringent conditions in Staphylococcus aureus
Authors: Kästle Benjamin , Geiger Tobias , Gratani Fabio Lino , Reisinger Rudolf , Goerke Christiane , Borisova Marina , Mayer Christoph , Wolz Christiane
Published: April 2015

The control of rRNA synthesis and, thereby, translation is vital for adapting to changing environmental conditions. The decrease of rRNA is a common feature of the stringent response, which is elicited by the rapid synthesis of (p)ppGpp. Here we analysed the properties and regulation of one representative rRNA operon of Staphylococcus aureus under stringent conditions and during growth. The promoters, P1 and P2, are severely downregulated at low intracellular guanosine triphosphate (GTP) concentrations either imposed by stringent conditions or in a guanine auxotroph guaBA mutant. In a (p)ppGpp0 strain, the GTP level increased under stringent conditions, and rRNA transcription was upregulated. The correlation of the intracellular GTP levels and rRNA promoter activity could be linked to GTP nucleotides in the initiation region of both promoters at positions between +1 and +4. This indicates that not only transcriptional initiation, but also the first steps of elongation, requires high concentrations of free nucleotides. However, the severe downregulation of rRNA in post‐exponential growth phase is independent of (p)ppGpp, the composition of the initiation region and the intracellular nucleotide pool. In summary, rRNA transcription in S. aureus is only partially and presumably indirectly controlled by (p)ppGpp.
Ruminococcal cellulosome systems from rumen to human
Authors: Ben David Yonit , Dassa Bareket , Borovok Ilya , Lamed Raphael , Koropatkin Nicole M. , Martens Eric C. , White Bryan A. , Bernalier‐Donadille Annick , Duncan Sylvia H. , Flint Harry J. , Bayer Edward A. , Moraïs Sarah
Published: April 2015

A cellulolytic fiber‐degrading bacterium, Ruminococcus champanellensis, was isolated from human faecal samples, and its genome was recently sequenced. Bioinformatic analysis of the R. champanellensis genome revealed numerous cohesin and dockerin modules, the basic elements of the cellulosome, and manual sequencing of partially sequenced genomic segments revealed two large tandem scaffoldin‐coding genes that form part of a gene cluster. Representative R. champanellensis dockerins were tested against putative cohesins, and the results revealed three different cohesin–dockerin binding profiles which implied two major types of cellulosome architectures: (i) an intricate cell‐bound system and (ii) a simplistic cell‐free system composed of a single cohesin‐containing scaffoldin. The cell‐bound system can adopt various enzymatic architectures, ranging from a single enzyme to a large enzymatic complex comprising up to 11 enzymes. The variety of cellulosomal components together with adaptor proteins may infer a very tight regulation of its components. The cellulosome system of the human gut bacterium R. champanellensis closely resembles that of the bovine rumen bacterium Ruminococcus flavefaciens. The two species contain orthologous gene clusters comprising fundamental components of cellulosome architecture. Since R. champanellensis is the only human colonic bacterium known to degrade crystalline cellulose, it may thus represent a keystone species in the human gut.
Trabeculectomy versus canaloplasty (TVC study) in the treatment of patients with open‐angle glaucoma: a prospective randomized clinical trial
Authors: Matlach Juliane , Dhillon Christine , Hain Johannes , Schlunck Günther , Grehn Franz , Klink Thomas
Published: April 2015

Purpose

To compare the outcomes of canaloplasty and trabeculectomy in open‐angle glaucoma.

Methods

This prospective, randomized clinical trial included 62 patients who randomly received trabeculectomy (n = 32) or canaloplasty (n = 30) and were followed up prospectively for 2 years. Primary endpoint was complete (without medication) and qualified success (with or without medication) defined as an intraocular pressure (IOP) of ≤18 mmHg (definition 1) or IOP ≤21 mmHg and ≥20% IOP reduction (definition 2), IOP ≥5 mmHg, no vision loss and no further glaucoma surgery. Secondary endpoints were the absolute IOP reduction, visual acuity, medication, complications and second surgeries.

Results

Surgical treatment significantly reduced IOP in both groups (p < 0.001). Complete success was achieved in 74.2% and 39.1% (definition 1, p = 0.01), and 67.7% and 39.1% (definition 2, p = 0.04) after 2 years in the trabeculectomy and canaloplasty group, respectively. Mean absolute IOP reduction was 10.8 ± 6.9 mmHg in the trabeculectomy and 9.3 ± 5.7 mmHg in the canaloplasty group after 2 years (p = 0.47). Mean IOP was 11.5 ± 3.4 mmHg in the trabeculectomy and 14.4 ± 4.2 mmHg in the canaloplasty group after 2 years. Following trabeculectomy, complications were more frequent including hypotony (37.5%), choroidal detachment (12.5%) and elevated IOP (25.0%).

Conclusions

Trabeculectomy is associated with a stronger IOP reduction and less need for medication at the cost of a higher rate of complications. If target pressure is attainable by moderate IOP reduction, canaloplasty may be considered for its relative ease of postoperative care and lack of complications.
More training and awareness are needed to improve the recognition of undernutrition in hospitalised children
Authors: Huysentruyt Koen , Goyens Philippe , Alliet Philippe , Bontems Patrick , Van Hautem Hilde , Philippet Pierre , Vandenplas Yvan , De Schepper Jean
Published: April 2015

Aim

Reports suggest that 10% of hospitalised children in Europe are undernourished. We investigated whether nutritional screening tools (NST) were used in Belgian secondary‐level hospitals, examined strategies for detecting undernutrition and identified barriers preventing the systematic management of undernutrition.

Methods

A nationwide questionnaire‐based survey of paediatric departments in Belgian secondary‐level hospitals was carried out from September 2013 to February 2014. Respondents were dived into French‐speaking (Walloon + Brussels) and Dutch‐speaking (Flemish) departments.

Results

We received replies from 71 of the 97 (73.2%) departments. Half of the departments – 39.5% Flemish speaking and 71.4% Walloon speaking – carried out nutritional screening. Undernutrition was identified by measuring weight and length or height (92.7% of cases), clinical appraisal (74.7%), mid‐upper arm circumference and/or skin fold thickness (19.7%). There was no protocol for undernutrition in many Flemish (60.5%)‐ and Walloon (28.6%)‐speaking departments. Reasons given for not screening were as follows: lack of training (46.9%), ignorance of NST (42.2%) and lack of time (29.7%).

Conclusion

Half of the paediatric departments in Belgian secondary‐level hospitals did not carry out nutritional screening, and differences in current practices and attitudes may be due to cultural and/or educational differences.
Variable risk of atopic disease due to indoor fungal exposure in NHANES 2005–2006
Authors: Sharpe R. A. , Thornton C. R. , Tyrrell J. , Nikolaou V. , Osborne N. J.
Published: April 2015

Background

Exposure to damp indoor environments is associated with increased risk of eczema, allergy and asthma. The role of dampness‐related exposures and risk of allergic diseases are yet to be fully explored in the US population.

Objective

We assess whether exposure to fungi, house dust mites and endotoxin increases the risk of eczema, allergy and asthma in children and adults participating in NHANES 2005–2006.

Methods

A total of 8412 participants (2849 were children aged between 6 and 17 years) were recruited in the 2005–2006 survey. We used multiple logistic regression to investigate whether mildew/musty odour and increased concentrations of Alternaria alternata allergen, Aspergillus fumigatus antigens, house dust mite and endotoxin antigens increase the risk of eczema, allergy and asthma. We stratified models by total IgE < 170 and ≥ 170 KU/L to assess allergic and non‐allergic asthma outcomes. Exposure to multiple biological agents and risk of reporting eczema, allergy and asthma were also investigated.

Results

Reporting of a mildew/musty odour was associated with increased risk of childhood asthma (OR 1.60; 95% CI 1.17–2.19), and adult eczema, allergy and asthma (OR 1.92; 95% CI 1.39–2.63, OR 1.59 95% CI 1.26–2.02 and OR 1.61 95% CI 1.00–2.57, respectively). Risk of asthma was associated with total IgE ≥ 170 KU/L in children (OR 1.81; 95% CI 1.01–3.25) and total IgE < 170 KU/L in adults (OR 1.91; 95% CI 1.07–3.42). Children and adults exposed to more than eight biological agents present in the home were at reduced risk of eczema (OR 0.17; 95% CI 0.04–0.77) and asthma (OR 0.49; 95% CI 0.25–0.97), respectively.

Conclusion

Exposure to a mildew/musty odour, as a proxy for exposure to fungus, was implicated in an increased risk of atopic diseases. Sensitisation may play a different role in children and adults, and exposure to multiple allergens may reduce the risk of atopic disease.
Serum osteopontin levels are upregulated and predict disability after an ischaemic stroke
Authors: Carbone Federico , Vuilleumier Nicolas , Burger Fabienne , Roversi Gloria , Tamborino Carmine , Casetta Ilaria , Seraceni Silva , Trentini Alessandro , Padroni Marina , Dallegri Franco , Mach François , Fainardi Enrico , Montecucco Fabrizio
Published: April 2015

Background

After an acute ischaemic stroke (AIS), several inflammatory biomarkers have been investigated, but their predictive role on functional recovery remains to be validated. Here, we investigated the prognostic relevance of biomarkers related to atherosclerotic plaque calcification, such as osteopontin (OPN), osteoprotegerin (OPG) and the receptor activator of nuclear factor kappa‐B ligand (RANKL) in a cohort of patients with AIS (n = 90) during 90‐day follow‐up.

Materials and methods

Radiological and clinical examinations as well as blood sampling were performed at admission and at days 1, 7 and 90 from the event. Validated scores [such as modified Rankin scale (mRS) and the National Institutes of Health Stroke Scale (NIHSS)] were used to assess poststroke outcome. Serum levels of OPN, OPG and RANKL were measured by colorimetric enzyme‐linked immunosorbent assay (ELISA).

Results

When compared to the admission, OPN serum levels increased at day 7. Serum OPN levels at this time point were positively correlated with both ischaemic lesion volume and NIHSS at days 7 and 90. A cut‐off of 30·53 ng/mL was identified for serum OPN by receiver operating characteristic (ROC) curve analysis. Adjusted logistic regression showed that serum OPN levels at day 7 predicted worse mRS at day 90 [OR 4·13 (95% CI 1·64–10·36); P = 0·002] and NIHSS [1·49 (95% CI 1·16–1·99); P = 0·007], independently of age, gender, hypertension and thrombolysis.

Conclusions

Serum levels of OPN, but not OPG and RANKL, peaked at day 7 after AIS and predicted worse neurological scores. Therefore, OPN might have a pathophysiological and clinical relevance after AIS.
Genetic deletion of the prostaglandin E2 E prostanoid receptor subtype 3 improves anatomical and functional outcomes after intracerebral hemorrhage
Authors: Leclerc Jenna L. , Lampert Andrew S. , Diller Matthew A. , Doré Sylvain
Published: April 2015

Intracerebral hemorrhage (ICH) is a stroke subtype associated with high mortality and morbidity. Following ICH, excitotoxicity and inflammation significantly contribute to secondary brain injury and poor outcomes. Prostaglandin E2 (PGE2) levels rise locally with insult to the nervous system, and PGE2 is known to modulate these processes mainly through its E prostanoid (EP) receptors, EP1‐4. EP receptor subtype 3 (EP3) is the most abundant EP receptor in the brain and we have previously shown that signaling through the PGE2–EP3 axis exacerbates excitotoxicity and ischemic stroke outcomes. This study aimed to investigate the contribution of this pathway in modulating anatomical outcomes and functional recovery following ICH. Genetic deletion of EP3 resulted in 48.2 ± 7.3% less ICH‐induced brain injury (P < 0.005) and improved functional recovery (P < 0.05), as identified by neurological deficit scoring. To start investigating the mechanisms involved in neuroprotection with impaired PGE2–EP3 signaling, histological staining was performed to evaluate blood and ferric iron accumulation, neuroinflammation, blood–brain barrier dysfunction, and peripheral neutrophil infiltration. After ICH, EP3 knockout mice demonstrated 49.5 ± 8.8% and 42.8 ± 13.1% less blood (P < 0.01) and ferric iron (P < 0.05), respectively. Furthermore, EP3 knockout mice had significantly reduced astrogliosis, microglial activation, blood–brain barrier breakdown, and neutrophil infiltration. Collectively, these results suggest an injurious role for the PGE2–EP3 signaling axis in modulating brain injury, inflammation, and neurological functional recovery after ICH. Modulation of the PGE2–EP3 signaling axis may represent a putative therapeutic avenue for the treatment of ICH.