bluuebunny/crossref_metadata_2025 huggingface dataset:
Extrinsic photoresponse enhancement under additional intrinsic photoexcitation in organic semiconductors
Authors: Kounavis P.
Published: June 2016

Dual light beam photoresponse experiments are employed to explore the photoresponse under simultaneous extrinsic and intrinsic photoexcitation of organic semiconductors. The photoresponse of a red modulated light extrinsic photoexcitation is found that can be significantly enhanced under an additional blue bias-light intrinsic photoexcitation in two terminal pentacene films on glass substrates. From the frequency resolved photoresponse, it is deduced that the phenomenon of photoresponse enhancement can be attributed to an increase in the extrinsic photogeneration rate of the red modulated light and/or an improvement of the drift velocity of carriers under an additional blue light intrinsic photoexcitation. The possible predominant extrinsic photogeneration mechanism, which can be compatible with the observed dependence of the photoresponse enhancement on the frequency and on the light intensities of the red and blue light excitation, is the singlet exciton dissociation through electron transfer to acceptor-like traps. Moreover, an improvement in the drift velocity of carriers traversing grain boundaries with potential energy barriers, which may be reduced by trapping of minority carriers created from the intrinsic photoexcitation, may partly contribute to the photoresponse enhancement.
Dynamo action in dissipative, forced, rotating MHD turbulence
Authors: Shebalin John V.
Published: June 2016

Magnetohydrodynamic (MHD) turbulence is an inherent feature of large-scale, energetic astrophysical and geophysical magnetofluids. In general, these are rotating and are energized through buoyancy and shear, while viscosity and resistivity provide a means of dissipation of kinetic and magnetic energy. Studies of unforced, rotating, ideal (i.e., non-dissipative) MHD turbulence have produced interesting results, but it is important to determine how these results are affected by dissipation and forcing. Here, we extend our previous work and examine dissipative, forced, and rotating MHD turbulence. Incompressibility is assumed, and finite Fourier series represent turbulent velocity and magnetic field on a 643 grid. Forcing occurs at an intermediate wave number by a method that keeps total energy relatively constant and allows for injection of kinetic and magnetic helicity. We find that 3-D energy spectra are asymmetric when forcing is present. We also find that dynamo action occurs when forcing has either kinetic or magnetic helicity, with magnetic helicity injection being more important. In forced, dissipative MHD turbulence, the dynamo manifests itself as a large-scale coherent structure that is similar to that seen in the ideal case. These results imply that MHD turbulence, per se, may play a fundamental role in the creation and maintenance of large-scale (i.e., dipolar) stellar and planetary magnetic fields.
On the physics of electron ejection from laser-irradiated overdense plasmas
Authors: Thévenet M. , Vincenti H. , Faure J.
Published: June 2016

Using 1D and 2D PIC simulations, we describe and model the backward ejection of electron bunches when a laser pulse reflects off an overdense plasma with a short density gradient on its front side. The dependence on the laser intensity and gradient scale length is studied. It is found that during each laser period, the incident laser pulse generates a large charge-separation field, or plasma capacitor, which accelerates an attosecond bunch of electrons toward vacuum. This process is maximized for short gradient scale lengths and collapses when the gradient scale length is comparable to the laser wavelength. We develop a model that reproduces the electron dynamics and the dependence on laser intensity and gradient scale length. This process is shown to be strongly linked with high harmonic generation via the Relativistic Oscillating Mirror mechanism.
Analyzing aging under oscillatory strain field through the soft glassy rheology model
Authors: Kaushal Manish , Joshi Yogesh M.
Published: June 2016

In this work, we solve the Soft Glassy Rheology (SGR) model under application of oscillatory deformation field with varying magnitudes of strain as well as frequency for different noise temperatures. In the glassy domain, the SGR model undergoes time evolution of elastic modulus. Increase in strain magnitude beyond the linear regime is observed to enhance the rate of aging as manifested by a faster evolution of elastic modulus with increase in strain amplitude due to overaging. However at higher strain magnitudes, the rejuvenation effect starts dominating over the aging, thereby reducing the rate at which elastic modulus evolves. We also plot the aging phase diagram describing an occurrence of the linear, the overaging, and the rejuvenation regimes as a function of strain and frequency for different noise temperatures. The aging phase diagram suggests that while the linear regime remains unaffected by the changes in frequency and noise temperature, the width of the overaging regime increases with increase in frequency and noise temperature. We also study the time evolution of the shapes of relaxation time spectra as a function of strain amplitude, which renders further insight into the overaging and the rejuvenation behavior. While the phenomenon of overaging is observed to be an inherent character of the SGR model, experimentally not all the materials demonstrate overaging. Such a discrepancy suggests that the energy well depths before and after a yielding event may not be completely uncorrelated as assumed in the SGR formalism.
Communication: Visualization and spectroscopy of defects induced by dehydrogenation in individual silicon nanocrystals
Authors: Kislitsyn Dmitry A. , Mills Jon M. , Kocevski Vancho , Chiu Sheng-Kuei , DeBenedetti William J. I. , Gervasi Christian F. , Taber Benjamen N. , Rosenfield Ariel E. , Eriksson Olle , Rusz Ján , Goforth Andrea M. , Nazin George V.
Published: June 2016

We present results of a scanning tunneling spectroscopy (STS) study of the impact of dehydrogenation on the electronic structures of hydrogen-passivated silicon nanocrystals (SiNCs) supported on the Au(111) surface. Gradual dehydrogenation is achieved by injecting high-energy electrons into individual SiNCs, which results, initially, in reduction of the electronic bandgap, and eventually produces midgap electronic states. We use theoretical calculations to show that the STS spectra of midgap states are consistent with the presence of silicon dangling bonds, which are found in different charge states. Our calculations also suggest that the observed initial reduction of the electronic bandgap is attributable to the SiNC surface reconstruction induced by conversion of surface dihydrides to monohydrides due to hydrogen desorption. Our results thus provide the first visualization of the SiNC electronic structure evolution induced by dehydrogenation and provide direct evidence for the existence of diverse dangling bond states on the SiNC surfaces.
AFM investigation of effect of absorbed water layer structure on growth mechanism of octadecyltrichlorosilane self-assembled monolayer on oxidized silicon
Authors: Li Shaowei , Zheng Yanjun , Chen Changfeng
Published: June 2016

The growth mechanism of an octadecyltrichlorosilane (OTS) self-assembled monolayer on a silicon oxide surface at various relative humidities has been investigated. Atomic force microscopy images show that excess water may actually hinder the nucleation and growth of OTS islands. A moderate amount of water is favorable for the nucleation and growth of OTS islands in the initial stage; however, the completion of the monolayer is very slow in the final stage. The growth of OTS islands on a low-water-content surface maintains a relatively constant speed and requires the least amount of time. The mobility of water molecules is thought to play an important role in the OTS monolayers, and a low-mobility water layer provides a steady condition for OTS monolayer growth.
The role of zonal flows in the saturation of multi-scale gyrokinetic turbulence
Authors: Staebler G. M. , Candy J. , Howard N. T. , Holland C.
Published: June 2016

The 2D spectrum of the saturated electric potential from gyrokinetic turbulence simulations that include both ion and electron scales (multi-scale) in axisymmetric tokamak geometry is analyzed. The paradigm that the turbulence is saturated when the zonal (axisymmetic) ExB flow shearing rate competes with linear growth is shown to not apply to the electron scale turbulence. Instead, it is the mixing rate by the zonal ExB velocity spectrum with the turbulent distribution function that competes with linear growth. A model of this mechanism is shown to be able to capture the suppression of electron-scale turbulence by ion-scale turbulence and the threshold for the increase in electron scale turbulence when the ion-scale turbulence is reduced. The model computes the strength of the zonal flow velocity and the saturated potential spectrum from the linear growth rate spectrum. The model for the saturated electric potential spectrum is applied to a quasilinear transport model and shown to accurately reproduce the electron and ion energy fluxes of the non-linear gyrokinetic multi-scale simulations. The zonal flow mixing saturation model is also shown to reproduce the non-linear upshift in the critical temperature gradient caused by zonal flows in ion-scale gyrokinetic simulations.
Spatial selective manipulation of microbubbles by tunable surface acoustic waves
Authors: Zhou Wei , Niu Lili , Cai Feiyan , Li Fei , Wang Chen , Huang Xiaowei , Wang Jingjing , Wu Junru , Meng Long , Zheng Hairong
Published: June 2016

A microfluidic device based on a pair of slant-finger interdigital transducers (SFITs) is developed to achieve a selective and flexible manipulation of microbubbles (MBs) by surface acoustic waves (SAWs). The resonance frequency of SAWs generated by the SFITs depends on the location of its parallel pathway; the particles at different locations of the SAWs' pathway can be controlled selectively by choosing the frequency of the excitation signal applied on the SFITs. By adjusting the input signal continuously, MBs can be transported along the acoustic aperture precisely. The displacement of MBs has a linear relationship with the frequency shift. The resolution of transportation is 15.19 ± 2.65 μm when the shift of input signal frequency is at a step of 10 kHz. In addition, the MBs can be controlled in a two-dimensional plane by combining variations of the frequency and the relative phase of the excitation signal applied on the SFITs simultaneously. This technology may open up the possibility of selectively and flexibly manipulating MBs using a simple one-dimensional device.
Photoelectron generation and capture in the resonance fluorescence of a quantum dot
Authors: Kurzmann A. , Ludwig A. , Wieck A. D. , Lorke A. , Geller M.
Published: June 2016

Time-resolved resonance fluorescence on a single self-assembled quantum dot (QD) is used to analyze the generation and capture of photoinduced free charge carriers. We directly observe the capture of electrons into the QD as an intensity reduction of the exciton transition. The exciton transition is quenched until the captured electron tunnels out of the dot again in the order of milliseconds. Our results demonstrate that even under resonant excitation, excited free electrons are generated and can negatively influence the optical properties of a QD.
Morphology modification of gold nanoparticles from nanoshell to C-shape: Improved surface enhanced Raman scattering
Authors: Xing Ting-Yang , Zhu Jian , Li Jian-Jun , Zhao Jun-Wu
Published: June 2016

Morphology modification of nanostructures is of great interest, because it can be used to fabricate nanostructures which are hard to be done using other methods. Different from traditional lithographic technique which is slow and expensive, morphology modification is easy, cheap, and reproducible. In this paper, modification of the optical and morphological properties of a hollow gold nanoshell (HGNS) is achieved by using H2O2 as an oxidizer. The reshaping of these nanostructures has been demonstrated as a consequence of an oxidation process in which HGNSs are dissolved by H2O2 under the acidic conditions provided by HCl. We investigate the oxidation process by a transmission electron microscope and propose a reshaping model involving four different shapes (HGNS, HGNS with hole, gold nanoring, and C-shaped gold nanoparticle) which are corresponding to the oxidation products of HGNSs at different pH values. Besides, the surface enhanced Raman scattering (SERS) activity of each oxidation product has been evaluated by using rhodamine 6G as the Raman active probe. It has been observed that the C-shaped gold nanoparticles which are corresponding to the oxidation products at the minimum pH value have the highest SERS activity and this result can also be interpreted by discrete-dipole approximation simulations. We demonstrate that the morphology modification of HGNSs becomes possible in a controlled manner using wet chemistry and can be used in preparation of gold nanoparticles such as HGNS with hole, gold nanoring, and C-shaped gold nanoparticle with large SERS activity. These nanostructures must have potential use in many plasmonic areas, including sensing, catalysis, and biomedicine.
Terahertz imaging of Landau levels in HgTe-based topological insulators
Authors: Kadykov Aleksandr M. , Torres Jeremie , Krishtopenko Sergey S. , Consejo Christophe , Ruffenach Sandra , Marcinkiewicz Michal , But Dmytro , Knap Wojciech , Morozov Sergey V. , Gavrilenko Vladimir I. , Mikhailov Nikolai N. , Dvoretsky Sergey A. , Teppe Frederic
Published: June 2016

We report on sub-terahertz photoconductivity under the magnetic field of a two dimensional topological insulator based on HgTe quantum wells. We perform a detailed visualization of Landau levels by means of photoconductivity measured at different gate voltages. This technique allows one to determine a critical magnetic field, corresponding to topological phase transition from inverted to normal band structure, even in almost gapless samples. The comparison with realistic calculations of Landau levels reveals a smaller role of bulk inversion asymmetry in HgTe quantum wells than it was assumed previously.
Probing the thermal Hall effect using miniature capacitive strontium titanate thermometry
Authors: Tinsman Colin , Li Gang , Su Caroline , Asaba Tomoya , Lawson Benjamin , Yu Fan , Li Lu
Published: June 2016

The thermal Hall effect is the thermal analog of the electrical Hall effect. Rarely observed in normal metals, thermal Hall signals have been argued to be a key property for a number of strongly correlated materials, such as high temperature superconductors, correlated topological insulators, and quantum magnets. The observation of the thermal Hall effect requires precise measurement of temperature in intense magnetic fields. Particularly at low temperature, resistive thermometers have a strong dependence on field, which makes them unsuitable for this purpose. We have created capacitive thermometers which instead measure the dielectric constant of strontium titanate (SrTiO3). SrTiO3 approaches a ferroelectric transition, causing its dielectric constant to increase by a few orders of magnitude at low temperature. As a result, these thermometers are very sensitive at low temperature while having very little dependence on the applied magnetic field, making them ideal for thermal Hall measurements. We demonstrate this method by making measurements of the thermal Hall effect in Bismuth in magnetic fields of up to 10 T.
Integrative taxonomic revision of the polymorphic flat-millipede genera Oncocladosoma and Somethus in South Australia (Diplopoda : Polydesmida : Paradoxosomatidae)
Authors: Decker Peter
Published: June 2016

The South Australian members of the flat-millipede genera Oncocladosoma Jeekel, 1985 and Somethus Chamberlin, 1920 are revised using an integrative approach incorporating sequence data and morphology. The partial mitochondrial cytochrome c oxidase subunit I (COI) barcoding gene and partial nuclear ribosomal 28S rRNA were amplified and sequenced for 15 Oncocladosoma specimens and 10 Somethus specimens and the datasets were used for molecular phylogenetic analysis and genetic distance determination. Both morphology and molecular data indicate that all species of Oncocladosoma fall within Somethus, and therefore, Oncocladosoma is synonymised with Somethus. Within those species supported by molecular data, features of the solenomere tip are relatively stable and useful for species identification. 28S rRNA has proven to provide sufficient nucleotide variation to provisionally discriminate species. Oncocladosoma castaneum ingens Jeekel, 1985, O. clavigerum Jeekel, 1985 and O. conigerum Jeekel, 1985 are junior synonyms of Somethus castaneus, comb. nov., and Somethus modicus Jeekel, 2002 is a synonym of S. scopiferus Jeekel, 2002. New records and electron scanning micrographs of gonopods are provided for S. castaneus, comb. nov., S. inflatus (Jeekel, 2002), comb. nov., S. lancearius Jeekel, 2002, S. scopiferus Jeekel, 2002, and Somethus grossi Jeekel, 1985, together with a key to the South Australian species of Somethus.
Transoceanic dispersal and cryptic diversity in a cosmopolitan rafting nudibranch
Authors: Trickey Jennifer S. , Thiel Martin , Waters Jonathan M.
Published: June 2016

The aeolid nudibranch Fiona pinnata (Eschscholtz, 1831) is an obligate rafter that occurs exclusively on macroalgal rafts and other floating substrata, and has a seemingly cosmopolitan marine distribution. Mitochondrial (mtDNA) and nuclear DNA sequence data were generated from specimens collected worldwide to test for global connectivity in this species. Phylogeographic analyses revealed three divergent mtDNA lineages, two of which were abundant and widespread. One of these lineages has an apparent circumequatorial distribution, whereas the other may have an antitropical distribution within the Pacific Ocean. Low genetic divergences within each lineage suggest that rafting can mediate dispersal across transoceanic scales. A third, highly divergent, lineage was detected in a single Indonesian specimen. Broadly concordant phylogeographic relationships were detected for the nuclear ITS1 region, with distinct tropical versus antitropical lineages observed. The substantial genetic divergences and largely allopatric distributions observed among the F. pinnata lineages suggest that they represent a species complex.
Five new species and a systematic synopsis of Pycnandra (Sapotaceae), the largest endemic genus in New Caledonia
Authors: Swenson Ulf , Munzinger Jérôme
Published: June 2016

Pycnandra Benth. (Sapotaceae) is the largest endemic genus in New Caledonia and is subdivided into six subgenera. An addition of five species are here described in four subgenera, viz. P. comptonioides Swenson & Munzinger, P. kouakouensis Swenson & Munzinger, P. montana Swenson & Munzinger, P. poindimiensis Swenson & Munzinger and P. versicolor Swenson & Munzinger. Another seven to nine taxa are discussed but remain undescribed owing to the lack of adequate collections (and may remain undescribed pending the interpretation of the Nagoya Protocol). Pycnandra is characterised by a non-areolate higher leaf venation, sepals glabrous on the inner surface, no staminodes, and a single-seeded fruit. The members occur in a wide range of habitats and most species have very specific substrate requirements, growing on ultramafic, non-ultramafic or calcareous substrates. Almost 40 species are restricted to ultramafic substrates and many are now at risk of extinction because of deforestation, deliberately set fires and mining. We provide a systematic synopsis with keys to subgenera and species, phenology, substrate preferences, altitudinal ranges and preliminary IUCN Red List assessments for all described taxa. Four of the five new species are assessed as Critically Endangered. Pycnandra versicolor is in urgent need of conservation management beacuse its entire distribution is inside an active mine on the Koniambo massif.
Physiological role for amyloid precursor protein in adult experience-dependent plasticity
Authors: Marik Sally A. , Olsen Olav , Tessier-Lavigne Marc , Gilbert Charles D.
Published: June 2016

Significance

Amyloid precursor protein (APP) has long been implicated in Alzheimer’s disease, but its normal physiological role has only recently come to light. Here we demonstrate that APP plays a key role in axonal pruning after experience-dependent plasticity in the adult. Furthermore, we show that APP operates in a cell-autonomous fashion in the cortex to induce axonal pruning after sensory loss. APP is therefore important for the normal process of adult cortical plasticity through its role in the sculpting of axonal arbors.
Air pollutant emissions from Chinese households: A major and underappreciated ambient pollution source
Authors: Liu Jun , Mauzerall Denise L. , Chen Qi , Zhang Qiang , Song Yu , Peng Wei , Klimont Zbigniew , Qiu Xinghua , Zhang Shiqiu , Hu Min , Lin Weili , Smith Kirk R. , Zhu Tong
Published: June 2016

Significance

China suffers from severe outdoor air pollution and associated public health impacts. In response, the government has imposed restrictions on major pollution sources such as vehicles and power plants. We show that due to uncontrolled and inefficient combustion of solid fuels in household devices, emission reductions from the residential sector may have greater air quality benefits in the North China Plain, including Beijing than reductions from other sectors. These benefits would be largest in the winter heating season when severe air pollution occurs. Household emissions, mostly from space heating and cooking with solid fuels, are an important and generally unrecognized source of ambient air pollution in China and other developing countries. Alternative fuels and other ways of reducing emissions would have large benefits.
Nanofluid of graphene-based amphiphilic Janus nanosheets for tertiary or enhanced oil recovery: High performance at low concentration
Authors: Luo Dan , Wang Feng , Zhu Jingyi , Cao Feng , Liu Yuan , Li Xiaogang , Willson Richard C. , Yang Zhaozhong , Chu Ching-Wu , Ren Zhifeng
Published: June 2016

Significance

Improving crude oil recovery by 1% worldwide would result in a huge amount of crude oil resources becoming available. However, the economic and environmental concerns are too serious to ignore when chemical methods (surfactants or polymers flooding, etc.) are used for an average 10–20% enhancement for tertiary oil recovery. Simple nanofluid (containing only nanoparticles) flooding at low concentration (0.01 wt % or less) is a promising alternative, but the efficiency is below 5% in a saline environment (2 wt % or higher NaCl content). We report a simple nanofluid of graphene-based Janus amphiphilic nanosheets for enhanced oil recovery with efficiency of about 15.2%, comparable to chemical methods, which is both economically and environmentally beneficial to the petroleum industry.
The effects of neutron radiation on nickel-based alloys
Authors: Stopher M. A.
Published: June 2016

The effects of neutron radiation on nickel-based alloys in thermal reactors are defying predictions that were made based upon accelerated testing in fast reactors. As nickel-based alloy components face significant doses in aging thermal reactors and their role in Gen-IV reactor designs becomes prominent, the literature on the effects of radiation on such alloys must be reviewed to enable better structural integrity assessments for relevant components and optimise alloys with respect to irradiation embrittlement resistance. This paper reviews the available data on the effects of radiation, notably neutron radiation, on nickel-based alloys and discusses the possible mitigation strategies and design opportunities for radiation embrittlement-resistant alloys based on recent developments in alloy computational design.

This review was submitted as part of the 2016 Materials Literature Review Prize of the Institute of Materials, Minerals and Mining run by the Editorial Board of MST. Sponsorship of the prize by TWI Ltd is gratefully acknowledged.
Review of tailoring ZnO for optoelectronics through atomic layer deposition experimental variables
Authors: Burgess C. H.
Published: June 2016

Atomic layer deposition (ALD) is an increasingly popular thin film deposition technique which offers unique large area capability combined with excellent conformality, thus ALD will likely be important in the development of next generation optoelectronic devices. Such device platforms include solar cells, thin film transistors and light emitting diodes, and in all of these technologies one material is frequently used – zinc oxide (ZnO) – owing to its excellent electrical and optical properties combined with earth abundance. The approaches and achievements in tailoring the properties of ALD ZnO are discussed. Key process variables include deposition temperature and purge times as well dopant incorporation, with particular attention paid to tuning band alignment and carrier concentrations (focusing on lower carrier concentration applications).

This review was submitted as part of the 2016 Materials Literature Review Prize of the Institute of Materials, Minerals and Mining run by the Editorial Board of MST. Sponsorship of the prize by TWI Ltd is gratefully acknowledged.
Functional characterization of selective exosite-binding inhibitors of matrix metalloproteinase-13 (MMP-13) – experimental validation in human breast and colon cancer
Authors: Kothapalli Roopa , Sivaraman Siveen Kodappully , Tan Tuan Zea , Thiery Jean Paul , Kumar Alan Prem , Sethi Gautam , Swaminathan Kunchithapadam
Published: June 2016

Considering the pathological significance of MMP-13 in breast and colon cancers, exosite-based inhibition of the C-terminal hemopexin (Hpx) domain could serve as an alternative strategy to develop selective inhibitors for MMP-13.Two of six lead compounds, compound 5 (2,3-dihydro-1,4-benzodioxine-5-carboxylic acid) and compound 6 (1-acetyl-4-hydroxypyrrolidine-2-carboxylic acid) exhibited considerable inhibitory activity against MMP-13. Complementing to this study, we have also shown the gene expression levels of MMP-13 within the subtypes of colon and breast cancers classified from patients’ tissue samples to provide a better understanding on which subtype of breast cancer patients would get benefited by MMP-13 inhibitors.Our current results show that compounds 5 and 6 could effectively inhibit MMP-13 and provide specific therapeutic possibilities in the treatment of inflammatory disorders and cancers. The characterization of these lead compounds would provide a better mechanistic understanding of exosite-based inhibition of MMP-13, which could overcome the challenges in the identification of other MMP catalytic domain-specific inhibitors.
Rational maps without Herman rings
Authors: Yang Fei
Published: June 2016

Let

f
f

be a rational map with degree at least two. We prove that

f
f

has at least two disjoint and infinite critical orbits in the Julia set if it has a Herman ring. This result is sharp in the following sense: there exists a cubic rational map having exactly two critical grand orbits but also having a Herman ring. In particular,

f
f

has no Herman rings if it has at most one infinite critical orbit in the Julia set. These criterions derive some known results about the rational maps without Herman rings.
Steady states of the Vlasov-Maxwell system
Authors: Schaeffer Jack
Published: June 2016

The Vlasov-Maxwell system models collisionless plasma. Solutions are considered that depend on one spatial variable,

x
x

, and two velocity variables,

v
1

v_1

and

v
2

v_2

. As

x
→
−
∞

x\rightarrow - \infty

it is required that the phase space densities of particles approach a prescribed function,

F

(

v
1

,

v
2

)

F\left (v_1,v_2\right )

, and all field components approach zero. It is assumed that

F

(

v
1

,

v
2

)

=
0

F\left (v_1,v_2\right ) = 0

if

v
1

≤

W
1

v_1 \leq W_1

, where

W
1

W_1

is a positive constant. An external magnetic field is prescribed and taken small enough so that no particle is reflected (

v
1

v_1

remains positive). The main issue is to identify the large-time behavior; is a steady state approached and, if so, can it be identified from the time independent Vlasov-Maxwell system? The time-dependent problem is solved numerically using a particle method, and it is observed that a steady state is approached (on a bounded

x
x

interval) for large time. For this steady state, one component of the electric field is zero at all points, the other oscillates without decay for

x
x

large; in contrast the magnetic field tends to zero for large

x
x

. Then it is proven analytically that if the external magnetic field is sufficiently small, then (a reformulation of) the steady problem has a unique solution with

B
→
0

B \rightarrow 0

as

x
→
+
∞

x \rightarrow +\infty

. Thus the “downstream” condition,

B
→
0

B \rightarrow 0

as

x
→
+
∞

x\rightarrow + \infty

, is used to identify the large time limit of the system.
Relative Donaldson-Thomas theory for Calabi-Yau 4-folds
Authors: Cao Yalong , Leung Naichung
Published: June 2016

Given a complex 4-fold

X
X

with an (Calabi-Yau 3-fold) anti- canonical divisor

Y
Y

, we study relative Donaldson-Thomas invariants for this pair, which are elements in the Donaldson-Thomas cohomologies of

Y
Y

. We also discuss gluing formulas which relate relative invariants and

D

T

4

DT_{4}

invariants for Calabi-Yau 4-folds.
A probabilistic approach for collective similarity-based drug–drug interaction prediction
Authors: Sridhar Dhanya , Fakhraei Shobeir , Getoor Lise
Published: June 2016

Motivation: As concurrent use of multiple medications becomes ubiquitous among patients, it is crucial to characterize both adverse and synergistic interactions between drugs. Statistical methods for prediction of putative drug–drug interactions (DDIs) can guide in vitro testing and cut down significant cost and effort. With the abundance of experimental data characterizing drugs and their associated targets, such methods must effectively fuse multiple sources of information and perform inference over the network of drugs.

Results: We propose a probabilistic approach for jointly inferring unknown DDIs from a network of multiple drug-based similarities and known interactions. We use the highly scalable and easily extensible probabilistic programming framework Probabilistic Soft Logic. We compare against two methods including a state-of-the-art DDI prediction system across three experiments and show best performing improvements of more than 50% in AUPR over both baselines. We find five novel interactions validated by external sources among the top-ranked predictions of our model.

Availability and implementation: Final versions of all datasets and implementations will be made publicly available.

Contact:  dsridhar@ucsc.edu
Abnormal right ventricular-pulmonary artery coupling with exercise in heart failure with preserved ejection fraction
Authors: Borlaug Barry A. , Kane Garvan C. , Melenovsky Vojtech , Olson Thomas P.
Published: June 2016

Background

Exercise intolerance is common in people with heart failure and preserved ejection fraction (HFpEF). Right ventricular (RV) dysfunction has been shown at rest in HFpEF but little data are available regarding dynamic RV-pulmonary artery (PA) coupling during exercise.

Methods and results

Subjects with HFpEF (n = 50) and controls (n = 24) prospectively underwent invasive cardiopulmonary exercise testing using high-fidelity micromanometer catheters along with simultaneous assessment of RV and left ventricular (LV) mechanics by echocardiography. Compared with controls at rest, subjects with HFpEF displayed preserved RV systolic and diastolic mechanics (RV s′ and e′), impaired LV s′ and e′, higher biventricular filling pressures, and higher pulmonary artery pressures. On exercise, subjects with HFpEF displayed less increase in stroke volume, heart rate, and cardiac output (CO), with blunted increase in CO relative to O2 consumption (VO2). Enhancement in RV systolic and diastolic function on exercise was impaired in HFpEF compared with controls. Exercise-induced PA vasodilation was reduced in HFpEF in correlation with greater venous hypoxia. Elevations in biventricular filling pressures and limitations in CO reserve were strongly correlated with abnormal enhancement in ventricular mechanics in the RV and LV during stress.

Conclusions

In addition to limited LV reserve, patients with HFpEF display impaired RV reserve during exercise that is associated with high filling pressures and inadequate CO responses. These findings highlight the importance of biventricular dysfunction in HFpEF and suggest that novel therapies targeting myocardial reserve in both the left and right heart may be effective to improve clinical status.
Extracting genetic alteration information for personalized cancer therapy from ClinicalTrials.gov
Authors: Xu Jun , Lee Hee-Jin , Zeng Jia , Wu Yonghui , Zhang Yaoyun , Huang Liang-Chin , Johnson Amber , Holla Vijaykumar , Bailey Ann M , Cohen Trevor , Meric-Bernstam Funda , Bernstam Elmer V , Xu Hua
Published: June 2016

Objective: Clinical trials investigating drugs that target specific genetic alterations in tumors are important for promoting personalized cancer therapy. The goal of this project is to create a knowledge base of cancer treatment trials with annotations about genetic alterations from ClinicalTrials.gov.

Methods: We developed a semi-automatic framework that combines advanced text-processing techniques with manual review to curate genetic alteration information in cancer trials. The framework consists of a document classification system to identify cancer treatment trials from ClinicalTrials.gov and an information extraction system to extract gene and alteration pairs from the Title and Eligibility Criteria sections of clinical trials. By applying the framework to trials at ClinicalTrials.gov, we created a knowledge base of cancer treatment trials with genetic alteration annotations. We then evaluated each component of the framework against manually reviewed sets of clinical trials and generated descriptive statistics of the knowledge base.

Results and Discussion: The automated cancer treatment trial identification system achieved a high precision of 0.9944. Together with the manual review process, it identified 20 193 cancer treatment trials from ClinicalTrials.gov. The automated gene-alteration extraction system achieved a precision of 0.8300 and a recall of 0.6803. After validation by manual review, we generated a knowledge base of 2024 cancer trials that are labeled with specific genetic alteration information. Analysis of the knowledge base revealed the trend of increased use of targeted therapy for cancer, as well as top frequent gene-alteration pairs of interest. We expect this knowledge base to be a valuable resource for physicians and patients who are seeking information about personalized cancer therapy.
Multimodal MRI features predict isocitrate dehydrogenase genotype in high-grade gliomas
Authors: Zhang Biqi , Chang Ken , Ramkissoon Shakti , Tanguturi Shyam , Bi Wenya Linda , Reardon David A. , Ligon Keith L. , Alexander Brian M. , Wen Patrick Y. , Huang Raymond Y.
Published: June 2016

Background.

High-grade gliomas with mutations in the isocitrate dehydrogenase (IDH) gene family confer longer overall survival relative to their IDH-wild-type counterparts. Accurate determination of the IDH genotype preoperatively may have both prognostic and diagnostic value. The current study used a machine-learning algorithm to generate a model predictive of IDH genotype in high-grade gliomas based on clinical variables and multimodal features extracted from conventional MRI.

Methods.

Preoperative MRIs were obtained for 120 patients with primary grades III (n = 35) and IV (n = 85) glioma in this retrospective study. IDH genotype was confirmed for grade III (32/35, 91%) and IV (22/85, 26%) tumors by immunohistochemistry, spectrometry-based mutation genotyping (OncoMap), or multiplex exome sequencing (OncoPanel). IDH1 and IDH2 mutations were mutually exclusive, and all mutated tumors were collapsed into one IDH-mutated cohort. Cases were randomly assigned to either the training (n = 90) or validation cohort (n = 30). A total of 2970 imaging features were extracted from pre- and postcontrast T1-weighted, T2-weighted, and apparent diffusion coefficient map. Using a random forest algorithm, nonredundant features were integrated with clinical data to generate a model predictive of IDH genotype.

Results.

Our model achieved accuracies of 86% (area under the curve [AUC] = 0.8830) in the training cohort and 89% (AUC = 0.9231) in the validation cohort. Features with the highest predictive value included patient age as well as parametric intensity, texture, and shape features.

Conclusion.

Using a machine-learning algorithm, we achieved accurate prediction of IDH genotype in high-grade gliomas with preoperative clinical and MRI features.
Cumulative Fluid Balance and Mortality in Septic Patients With or Without Acute Kidney Injury and Chronic Kidney Disease*
Authors: Neyra Javier A. , Li Xilong , Canepa-Escaro Fabrizio , Adams-Huet Beverley , Toto Robert D. , Yee Jerry , Hedayati S. Susan
Published: June 2016

Objective:

Incident acute kidney injury and prevalent chronic kidney disease are commonly encountered in septic patients. We examined the differential effect of acute kidney injury and chronic kidney disease on the association between cumulative fluid balance and hospital mortality in critically ill septic patients.

Design:

Retrospective cohort study.

Setting:

Urban academic medical center ICU.

Patients:

ICU adult patients with severe sepsis or septic shock and serum creatinine measured within 3 months prior to and 72 hours of ICU admission. Patients with estimated glomerular filtration rate less than 15 mL/min/1.73 m2 or receiving chronic dialysis were excluded.

Interventions:

None.

Measurements and Main Results:

A total of 2,632 patients, 1,211 with chronic kidney disease, were followed up until hospital death or discharge. Acute kidney injury occurred in 1,525 patients (57.9%), of whom 679 (44.5%) had chronic kidney disease. Hospital mortality occurred in 603 patients (22.9%). Every 1-L increase in cumulative fluid balance at 72 hours of ICU admission was independently associated with hospital mortality in all patients (adjusted odds ratio, 1.06 [95% CI] 1.04–1.08; p < 0.001), and in each acute kidney injury/chronic kidney disease subgroup (adjusted odds ratio, 1.06 [1.03–1.09] for acute kidney injury+/chronic kidney disease+; 1.09 [1.05–1.13] for acute kidney injury–/chronic kidney disease+; 1.05 [1.03–1.08] for acute kidney injury+/chronic kidney disease–; and 1.07 [1.02–1.11] for acute kidney injury–/chronic kidney disease–). There was a significant interaction between acute kidney injury and chronic kidney disease on cumulative fluid balance (p =0.005) such that different cumulative fluid balance cut-offs with the best prognostic accuracy for hospital mortality were identified: 5.9 L for acute kidney injury+/chronic kidney disease+; 3.8 L for acute kidney injury–/chronic kidney disease+; 4.3 L for acute kidney injury+/chronic kidney disease–; and 1.5 L for acute kidney injury–/chronic kidney disease–. The addition of cumulative fluid balance to the admission Sequential Organ Failure Assessment score had increased prognostic utility for hospital mortality when compared with Sequential Organ Failure Assessment alone, particularly in patients with acute kidney injury.

Conclusions:

Higher cumulative fluid balance at 72 hours of ICU admission was independently associated with hospital mortality regardless of acute kidney injury or chronic kidney disease presence. We characterized cumulative fluid balance cut-offs associated with hospital mortality based on acute kidney injury/chronic kidney disease status, underpinning the heterogeneity of fluid regulation in sepsis and kidney disease.
Impact of Different Diagnostic Criteria on the Reported Prevalence of Junctional Ectopic Tachycardia After Pediatric Cardiac Surgery
Authors: Entenmann Andreas , Michel Miriam , Egender Friedemann , Hessling Vera , Kramer Hans-Heiner
Published: June 2016

Objectives:

Junctional ectopic tachycardia is a frequent complication after pediatric cardiac surgery. A uniform definition of postoperative junctional ectopic tachycardia has yet to be established in the literature. The objective of this study is to analyze differences in the general and age-related prevalence of postoperative junctional ectopic tachycardia according to different diagnostic definitions.

Design:

Data files and electrocardiograms of 743 patients (age, 1 d to 17.6 yr) who underwent surgery for congenital heart disease during a 3-year period were reviewed. The prevalence of postoperative junctional ectopic tachycardia in this cohort was determined according to six different definitions identified in the literature and one definition introduced for analytical purposes. Agreement between the definitions was analyzed according to Cohen κ coefficients. A receiver operating characteristic analysis was performed to determine the ability of different definitions to discriminate between patients with increased postoperative morbidity and without.

Setting:

A university-affiliated tertiary pediatric cardiac PICU.

Patients:

Infants and children who underwent heart surgery.

Interventions:

None.

Measurements and Main Results:

The prevalence of postoperative junctional ectopic tachycardia ranged from 2.0% to 8.3% according to the seven different definitions. Even among definitions for which the general prevalence was almost equal, the distribution according to age varied. Most definitions used a frequency criterion to define postoperative junctional ectopic tachycardia. Definitions based on a fixed frequency criterion did not identify cases of postoperative junctional ectopic tachycardia in patients older than 12 months. The grade of agreement was moderate or poor between definitions using a fixed or dynamic frequency criterion and those not based on a critical heart rate (κ = 0.37–0.66). In the receiver operating characteristic analysis, the definition with a fixed frequency criterion of 180 beats/min or an age-related frequency criterion according to the 95th percentile showed the optimal cut-off value to determine increased postoperative morbidity.

Conclusions:

Different definitions of junctional ectopic tachycardia after pediatric cardiac surgery lead to relevant differences in the reported prevalence and age distribution pattern. A uniform definition of postoperative junctional ectopic tachycardia is needed to provide comparable study results and to improve the diagnosis of junctional ectopic tachycardia in pediatric patients.
Two-Stage Implant-Based Breast Reconstruction: An Evolution of the Conceptual and Technical Approach over a Two-Decade Period
Authors: Cordeiro Peter G. , Jazayeri Leila
Published: June 2016

Background:

Over a two-decade period, the senior author (P.G.C.) has had extensive experience with two-stage implant-based breast reconstruction with total musculofascial coverage. During this period, the approach has evolved substantially. The evolution has been based on changes in breast cancer treatment, available technology and, most importantly, yearly evaluation of surgical outcomes.

Methods:

This article describes changes in the conceptual approach to breast reconstruction, and the resulting evolution of surgical techniques. Evolving concepts and current techniques are described as they relate to each consecutive stage of implant-based breast reconstruction.

Results:

For the first stage of breast reconstruction (i.e., placement of the tissue expander), key concepts and techniques described are the vertical mastectomy defect, the point of maximal expansion, the musculofascial pocket, and the inferior fasciotomy. For the second stage of breast reconstruction (i.e., the exchange procedure), key concepts and techniques described are implant selection, setting the inframammary fold, defining the inferolateral shape of the breast, and circumferential capsulotomy.

Conclusion:

The purpose of this article is to relay the lessons learned from this long experience and to provide a conceptual and technical framework to two-stage implant-based breast reconstruction.
Defining the Role of Secondary Intention Healing in Full-Thickness Lid Margin Defects
Authors: Morton Jonathan David
Published: June 2016

More than 30 years have passed since the first case series was published regarding the phenomenon of secondary intention healing in relation to lid margin defects. Despite the fascinating results, the technique has not gained widespread support. This study looks at a series of 34 marginal lower lid defects allowed to heal without intervention. The results are remarkable for their consistently high quality, in terms of both cosmetic and functional outcomes. Medial lid defects, in particular, yielded results that would be difficult to surpass by conventional reconstructive techniques. The evidence presented here shows that secondary intention healing in lid margin defects should be considered as a genuine alternative to formal reconstruction, challenging the established dogma of bilamellar repair. For certain lid defects it is quite possibly (and unexpectedly) the new treatment of choice.

CLINICAL QUESTION/LEVEL OF EVIDENCE:

Therapeutic, IV.
Proposal of the TBN Classification of Thoracic Anomalies and Treatment Algorithm for Poland Syndrome
Authors: Romanini Maria Victoria , Torre Michele , Santi Pierluigi , Dova Laura , Valle Maura , Martinoli Carlo , Baldelli Iaria
Published: June 2016

Background:

Poland syndrome is a congenital deformity characterized by unilateral anomalies of pectoralis muscles, breast, nipple, axillary fold, subcutaneous tissue, ribs, and upper limb. The thoracic anomaly, which is the pathognomonic malformation of Poland syndrome, presents a wide phenotype variability and has been classified by different authors. However, these classifications do not include all the possible phenotypes of Poland syndrome. The aim of this study is to propose a simple classification of the whole spectrum of thoracic anomalies and a treatment algorithm that could have a practical value for determining the surgical approach.

Methods:

Since 2008, 100 patients have been evaluated by the same plastic surgical team at San Martino Hospital-IST and Istituto Gaslini of Genoa, Italy, using the thorax, breast, nipple-areola complex (TBN) classification. Thoracic anomalies were classified as follows: thorax (T), from T1 (muscle defect only) to T4 (complex deformity with rib and sternal involvement); breast (B), in B1 (hypoplasia) or B2 (amastia); and nipple-areola complex (N), from N1 (dislocation <2 cm) to N3 (athelia).

Results:

The most frequent thoracic anomalies were T1 (47 percent) and N2 (74 percent), whereas in female patients, B1 was more frequent than B2. The surgical approach to breast and pectoral reconstruction was based not only on the patient’s age and sex, but also on the type of anomaly according to the TBN classification. In particular, a two-step approach with tissue expanders was required in N2 and N3 cases, whereas in N1 patients a single step was sufficient.

Conclusion:

The TBN classification can be a useful tool for surgical decision-making according to each specific thoracic anomaly.

CLINICAL QUESTION/LEVEL OF EVIDENCE:

Diagnostic, IV.