bluuebunny/crossref_metadata_2025 huggingface dataset:
Superhard sp2-sp3 hybridized BC2N: A 3D crystal with 1D and 2D alternate metallicity
Authors: Gao Yufei , Wu Yingju , Huang Quan , Ma Mengdong , Pan Yilong , Xiong Mei , Li Zihe , Zhao Zhisheng , He Julong , Yu Dongli
Published: June 2017

A novel sp2-sp3 hybridized orthorhombic BC2N (o-BC2N) structure (space group: Pmm2, No. 25) is investigated using first-principles calculations. O-BC2N is constructed from multi-layers of C sandwiched between two layers of BN along the c axis; this structure contains sp2- and sp3-hybridized B-C, C-C, and C-N bonds. The structural stability of o-BC2N is confirmed based on the calculation results for elastic constants and phonon dispersions. On the basis of the semi-empirical microscopic model, we speculate that the o-BC2N compound is a potential superhard material with a Vickers hardness of 41.2 GPa. Calculated results for electronic band structures, density of states (DOS) and partial DOS (PDOS) show that the o-BC2N crystal is metallic. The conducting electrons at the Fermi level are mostly from the 2p orbits of sp2-hybridized B4, N1, and Ci (i = 2, 3, 4, 6, 7, 8) atoms, with slight contribution from the sp3-hybridizd B2 atoms. Furthermore, the calculated electron orbits of the o-BC2N crystal demonstrate that the 2p orbits of the sp2-hybridized atoms overlapped and formed π bonds. The electrons can conduct through the π bonds along the orientation parallel to the [100] and [010] directions in different layers, and the basal planes were formed by B2-C3-C4 blocks, indicating that the o-BC2N possesses the fascinating electronic property of linear-planar metallicity.
Solid-like features in dense vapors near the fluid critical point
Authors: Ruppeiner George , Dyjack Nathan , McAloon Abigail , Stoops Jerry
Published: June 2017

The phase diagram (pressure versus temperature) of the pure fluid is typically envisioned as being featureless apart from the presence of the liquid-vapor coexistence curve terminating at the critical point. However, a number of recent authors have proposed that this simple picture misses important features, such as the Widom line, the Fisher-Widom line, and the Frenkel line. In our paper, we discuss another way of augmenting the pure fluid phase diagram, lines of zero thermodynamic curvature R = 0 separating regimes of fluid solid-like behavior (R > 0) from gas-like or liquid-like behavior (R < 0). We systematically evaluate R for the 121 pure fluids in the NIST/REFPROP (version 9.1) fluid database near the saturated vapor line from the triple point to the critical point. Our specific goal was to identify regions of positive R abutting the saturated vapor line (“feature D”). We found the following: (i) 97/121 of the NIST/REFPROP fluids have feature D. (ii) The presence and character of feature D correlates with molecular complexity, taken to be the number of atoms Q per molecule. (iii) The solid-like properties of feature D might be attributable to a mesoscopic model based on correlations among coordinated spinning molecules, a model that might be testable with computer simulations. (iv) There are a number of correlations between thermodynamic quantities, including the acentric factor ω, but we found little explicit correlation between ω and the shape of a molecule. (v) Feature D seriously constrains the size of the asymptotic fluid critical point regime, possibly resolving a long-standing mystery about why these are so small. (vi) Feature D correlates roughly with regimes of anomalous sound propagation.
Plasmonic optical convergence microcavity based on the metal-insulator-metal microstructure
Authors: Wen J. , Wang W. J. , Li N. , Li Z. F. , Lu W.
Published: June 2017

With the increasing demand of low noise detection, the dimension of detectors are becoming smaller and smaller to reduce the dark current while sacrificing the detection efficiency. Here, a metal-insulator-metal (MIM) optical microcavity is proposed to converge light from tens of micrometers to several micrometers with little divergence. The measured transmission peaks show obvious dependence on the top metallic grating parameters, indicating the surface plasmon polariton resonance inside the cavity. Scanning near-field optical microscopy reveals the output profile around the exit holes. Polarization selective transmission has been demonstrated. If combined with a photodetector, the MIM microcavity, due to its light convergence capability, would provide a possibility to reduce the detector's active dimension down to 1–2 μm while retaining high quantum efficiency by keeping a large light collection area.
Modification of dielectric functions by lattice defects in lightly-absorbing LaB6 nanoparticles studied with effective medium theory
Authors: Machida Keisuke , Yoshio Satoshi , Adachi Kenji , Sato Yohei , Terauchi Masami
Published: June 2017

Optical properties of lightly absorbing LaB6 nanoparticles (NPs) derived from mechanical pulverization have been studied using the effective medium theory (EMT). EMT calculations are found to agree with observed optical profiles remarkably if both Drude and bound-electron terms of dielectric functions are modified for NPs from bulk values. In LaB6 NPs, the imaginary part of dielectric functions increases and the energy of initial rise in joint density of states redshifts as compared to bulk values. Origin of these behaviors has been examined in terms of lattice defects, in addition to the conventional intrinsic size effects. Lattice defects in LaB6 NPs have been identified as modest lattice expansion using x-ray diffraction and transmission electron microscopy. The observed lattice expansion is found to decrease the band gap by decreasing the anti-bonding energy of La-5d/B-2p hybridized orbitals by first-principles calculations using sX-LDA. It is concluded that, unlike conventional belief, dielectric functions can be modified from bulk values in NPs whose average particle size amply exceeds the electron mean free path.
On a class of integrable systems of Monge-Ampère type
Authors: Doubrov B. , Ferapontov E. V. , Kruglikov B. , Novikov V. S.
Published: June 2017

We investigate a class of multi-dimensional two-component systems of Monge-Ampère type that can be viewed as generalisations of heavenly type equations appearing in a self-dual Ricci-flat geometry. Based on the Jordan-Kronecker theory of the skew-symmetric matrix pencils, a classification of normal forms of such systems is obtained. All two-component systems of Monge-Ampère type turn out to be integrable and can be represented as the commutativity conditions of parameter-dependent vector fields. Geometrically, systems of Monge-Ampère type are associated with linear sections of the Grassmannians. This leads to an invariant differential-geometric characterisation of the Monge-Ampère property.
Deposition of TiO2/Al2O3 bilayer on hydrogenated diamond for electronic devices: Capacitors, field-effect transistors, and logic inverters
Authors: Liu J. W. , Liao M. Y. , Imura M. , Banal R. G. , Koide Y.
Published: June 2017

The wide bandgap semiconductor diamond has been studied to develop high-power and high-frequency electronic devices. Here, high dielectric constant (high-k) TiO2/Al2O3 bilayers are deposited on hydrogenated diamond (H-diamond) channel layers using sputter deposition (SD) and atomic layer deposition (ALD) techniques. Thin ALD-Al2O3 films are employed as buffer layers for the SD-TiO2 and ALD-TiO2 on H-diamond to suppress plasma discharge effect and to decrease leakage current density (J), respectively. The electrical properties of the resulting TiO2/Al2O3/H-diamond metal-oxide-semiconductor (MOS) capacitors, MOS field-effect transistors (MOSFETs), and MOSFET logic inverters are investigated. With the same thickness (4.0 nm) for ALD-Al2O3 buffer layer, the ALD-TiO2/ALD-Al2O3/H-diamond MOS capacitor shows a lower J and better capacitance-voltage characteristics than the SD-TiO2/ALD-Al2O3/H-diamond capacitor. The maximum capacitance of the ALD-TiO2/ALD-Al2O3/H-diamond capacitor and the k value of the ALD-TiO2/ALD-Al2O3 bilayer are 0.83 μF cm−2 and 27.2, respectively. Valence band offset between ALD-TiO2 and H-diamond is calculated to be 2.3 ± 0.2 eV based on the element binding energies measured using an X-ray photoelectron spectroscopy technique. Both the SD-TiO2/ALD-Al2O3/H-diamond and ALD-TiO2/ALD-Al2O3/H-diamond MOSFETs show p-type, pinch-off, and enhancement mode characteristics with on/off current ratios around 109. The subthreshold swings of them are 115 and as low as 79 mV dec−1, respectively. The ALD-TiO2/ALD-Al2O3/H-diamond MOSFET logic inverters, when coupled with load resistors, show distinct inversion characteristics with gains of 6.2–12.7.
Electric field induced broadening of magnetic resonance line in ferrite/piezoelectric bilayer
Authors: Petrov V. , Bichurin M. , Saplev A. , Tatarenko A. , Lobekin V.
Published: June 2017

The present investigation focuses on magnetoelectric interactions in ferrite-piezoelectric bilayers in the ferromagnetic resonance (FMR) region. A dc electric field applied perpendicular to the sample plane gives rise to an in-plane strain that is transferred to the ferrite and produces a uniaxial thickness-dependent magnetic anisotropy. Expressions for microwave magnetic susceptibility are obtained taking into account the effects of flexural deformations. The results are applied to the specific case of yttrium iron garnet (YIG)/lead zirconate titanate (PZT). The study predicts the unique electric field dependence of FMR line broadening. For the specific YIG to PZT thickness ratio, magnetoelectric coupling results in a weak FMR line shift and considerable line broadening. The results are of interest for novel ferrite-piezoelectric microwave devices.
Current conduction mechanism and electrical break-down in InN grown on GaN
Authors: Kuzmik J. , Fleury C. , Adikimenakis A. , Gregušová D. , Ťapajna M. , Dobročka E. , Haščík Š. , Kučera M. , Kúdela R. , Androulidaki M. , Pogany D. , Georgakilas A.
Published: June 2017

Current conduction mechanism, including electron mobility, electron drift velocity (vd) and electrical break-down have been investigated in a 0.5 μm-thick (0001) InN layer grown by molecular-beam epitaxy on a GaN/sapphire template. Electron mobility (μ) of 1040 cm2/Vs and a free electron concentration (n) of 2.1 × 1018 cm−3 were measured at room temperature with only a limited change down to 20 K, suggesting scattering on dislocations and ionized impurities. Photoluminescence spectra and high-resolution X-ray diffraction correlated with the Hall experiment showing an emission peak at 0.69 eV, a full-width half-maximum of 30 meV, and a dislocation density Ndis ∼ 5.6 × 1010 cm−2. Current-voltage (I-V) characterization was done in a pulsed (10 ns-width) mode on InN resistors prepared by plasma processing and Ohmic contacts evaporation. Resistors with a different channel length ranging from 4 to 15.8 μm obeyed the Ohm law up to an electric field intensity Eknee ∼ 22 kV/cm, when vd ≥ 2.5 × 105 m/s. For higher E, I-V curves were nonlinear and evolved with time. Light emission with a photon energy > 0.7 eV has been observed already at modest Erad of ∼ 8.3 kV/cm and consequently, a trap-assisted interband tunneling was suggested to play a role. At Eknee ∼ 22 kV/cm, we assumed electron emission from traps, with a positive feed-back for the current enhancement. Catastrophic break-down appeared at E ∼ 25 kV/cm. Reduction of Ndis was suggested to fully exploit InN unique prospects for future high-frequency devices.
Anomalous electron transport in metal/carbon multijunction devices by engineering of the carbon thickness and selecting metal layer
Authors: Dwivedi Neeraj , Dhand Chetna , Rawal Ishpal , Kumar Sushil , Malik Hitendra K. , Lakshminarayanan Rajamani
Published: June 2017

A longstanding concern in the research of amorphous carbon films is their poor electrical conductivity at room temperature which constitutes a major barrier for the development of cost effective electronic and optoelectronic devices. Here, we propose metal/carbon hybrid multijunction devices as a promising facile way to overcome room temperature electron transport issues in amorphous carbon films. By the tuning of carbon thickness and swapping metal layers, we observe giant (upto ∼7 orders) reduction of electrical resistance in metal/carbon multijunction devices with respect to monolithic amorphous carbon device. We engineer the maximum current (electrical resistance) from about 10−7 to 10−3 A (∼107 to 103 Ω) in metal (Cu or Ti)/carbon hybrid multijunction devices with a total number of 10 junctions. The introduction of thin metal layers breaks the continuity of relatively higher resistance carbon layer as well as promotes the nanostructuring of carbon. These contribute to low electrical resistance of metal/carbon hybrid multijunction devices, with respect to monolithic carbon device, which is further reduced by decreasing the thickness of carbon layers. We also propose and discuss equivalent circuit model to explain electrical resistance in monolithic carbon and metal/carbon multijunction devices. Cu/carbon multijunction devices display relatively better electrical transport than Ti/carbon devices owing to low affinity of Cu with carbon that restricts carbide formation. We also observe that in metal/carbon multijunction devices, the transport mechanism changes from Poole-Frenkel/Schottky model to the hopping model with a decrease in carbon thickness. Our approach opens a new route to develop carbon-based inexpensive electronic and optoelectronic devices.
Mobility modulation in low carrier concentration organic semiconducting thin films by varying disorder parameters
Authors: Kalia Sameer , Mahajan Aman , Ghansyam C. G. , Bedi R. K.
Published: June 2017

In the present work, an attempt has been made to modulate the carrier mobility in thermally evaporated, low carrier concentration organic thin films, with boron sub phthalocyanine chloride (sub pc) as a case study, by changing its various disorder parameters namely energetic disorder (σ), positional disorder (Σ2, Γ), and average inter-site hopping distance (a). The change in these disorder parameters was achieved by varying the substrate temperature of the films. All the films were electrically characterized under different temperature and bias conditions. An improvement of more than two orders in the mobility was achieved in the films with lower energetic and positional disorder. The transport mechanism exhibited a cross over from low frequency dispersion (high loss) regime to low loss regime with a decrease in disorder parameters. The average inter site hopping distance emerged as a key factor contributing to mobility enhancement. The zero field mobilities and other parameters were analyzed using Gaussian Disorder Model, Correlated Gaussian Disorder Model, and Murgatroyed equation. Variation in energetic disorder extracted from the analytical model was compared with the width of absorption tail obtained from UV-Vis spectra of the films.
Electrical measurement of absolute temperature and temperature transients in a buried nanostructure under ultrafast optical heating
Authors: Yang H. F. , Hu X. K. , Liebing N. , Böhnert T. , Costa J. D. , Tarequzzaman M. , Ferreira R. , Sievers S. , Bieler M. , Schumacher H. W.
Published: June 2017

We report absolute temperature measurements in a buried nanostructure with a sub-nanosecond temporal resolution. For this purpose, we take advantage of the temperature dependence of the resistance of a magnetic tunnel junction (MTJ) as detected by a fast sampling oscilloscope. After calibrating the measurement setup using steady-state electric heating, we are able to quantify temperature changes in the MTJ induced by femtosecond optical heating of the metal contact lying several 100 nm above the MTJ. We find that a femtosecond pulse train with an average power of 400 mW and a repetition rate of 76 MHz leads to a constant temperature increase of 80 K and a temporally varying temperature change of 2 K in the MTJ. The maximum temperature change in the MTJ occurs 4 ns after the femtosecond laser pulses hit the metal contact, which is supported by simulations. Our work provides a scheme to quantitatively study local temperatures in nanoscale structures and might be important for the testing of nanoscale thermal transport simulations.
Electrical detection of nuclear spin-echo signals in an electron spin injection system
Authors: Lin Zhichao , Rasly Mahmoud , Uemura Tetsuya
Published: June 2017

We demonstrated spin echoes of nuclear spins in a spin injection device with a highly polarized spin source by nuclear magnetic resonance (NMR). Efficient spin injection into GaAs from a half-metallic spin source of Co2MnSi enabled efficient dynamic nuclear polarization (DNP) and sensitive detection of NMR signals even at a low magnetic field of ∼0.1 T and a relatively high temperature of 4.2 K. The intrinsic coherence time T2 of 69Ga nuclear spins was evaluated from the spin-echo signals. The relation between T2 and the decay time of the Rabi oscillation suggests that the inhomogeneous effects in our system are not obvious. This study provides an all-electrical NMR system for nuclear-spin-based qubits.
Experiments on W-band extended interaction oscillator with pseudospark sourced post-accelerated electron beam
Authors: Zhao J. , Yin H. , Zhang L. , He W. , Zhang Q. , Phelps A. D. R. , Cross A. W.
Published: June 2017

The experimental study of a pseudospark discharge sourced electron beam with post acceleration (PA) is presented. The PA circuit was used to drive a W-band extended interaction oscillator. The experiments showed a significant increase in the output power, with 200 W at 94 GHz measuring corresponding to a 5 times increase in the output power as compared to when post acceleration is not used. The microwave device developed has the advantage of not requiring an external magnetic field making it a low cost, compact, and portable sub-terahertz radiation source.
Parent material and climate affect soil organic carbon fractions under pastures in south-eastern Australia
Authors: Orgill Susan E. , Condon Jason R. , Conyers Mark K. , Morris Stephen G. , Murphy Brian W. , Greene Richard S. B.
Published: June 2017

In the present field survey, 72 sites were sampled to assess the effect of climate (Monaro, Boorowa and Coleambally regions) and parent material (Monaro region only; basalt and granite) on soil organic carbon (OC) under perennial pastures. In the higher-rainfall zone (Monaro and Boorowa; >500mm mean annual rainfall), OC stocks under introduced and native perennial pastures were compared, whereas in the lower-rainfall zone (Coleambally; <500mm mean annual rainfall) OC stocks under crops and pastures were compared. Carbon fractions included total OC (TOC), particulate OC (POC), resistant OC (ROC) and humic OC (HUM). Higher OC stocks were associated with higher spring and summer rainfall and lower annual temperatures. Within a climatic zone, parent material affected the stock of OC fractions in the 0–30cm soil layer. Within a climatic zone, when grouped by parent material, there was no difference in OC stock with vegetation type. There were significant correlations between soil factors associated with parent material and OC concentration, including negative correlations between SiO2 and HUM (P<0.05) and positive correlations between cation exchange capacity and TOC, POC and ROC (P<0.01). TOC was also positively correlated with total nitrogen (N) and available sulfur (S; P<0.05), indicating organic matter in soil is important for N and S supply for plant production in the studied regions, and vice versa. Although ensuring adequate available S may increase OC stocks in south-eastern Australia, the large stock of OC in the soil under perennial pastures, and the dominating effect of climate and parent material on this stock, may mean that modest increases in soil OC due to management factors go undetected.
A note on the syntax of possession in Paraguayan Guaraní
Authors: Zubizarreta Maria Luisa , Pancheva Roumyana
Published: June 2017

This article shows that the pronominal system of Paraguayan Guaraní provides evidence that 3p (null) possessor pronouns behave differently from 1p and 2p (overt) possessor pronouns and argues that this difference can be captured by a conjunction of hypotheses, namely, that the 3p possessor pronoun in Paraguayan Guaraní is negatively specified for Person feature and that its syntax is crucially different from that of 1p and 2p possessor pronouns. The null possessor pronoun is an nP (not a DP) that receives its interpretation via local binding. We furthermore argue that all inalienable possessor pronouns in Paraguayan Guaraní originate as an nP and that 1p and 2p pronouns must sideward-merge with a D and then merge as specifiers of higher heads (either in the nominal or verbal domain) to be syntactically realized as full DPs. We extend the analysis proposed for inalienable possessors to a certain class of transitive verbs (known as triforme verbs) as well as to nominal possessor constructions.
The grammaticalization of ‘big’ situations
Authors: Rivero María Luisa , Arregui Ana , Slavkov Nikolay
Published: June 2017

Assuming that syntax and morphology constraints can target ‘situation size’ in semantics, this paper argues for the necessity of constraints on ‘big’ situations, and for their grammaticalization. Data from Bulgarian indicate that complex (viewpoint) aspectual interactions between Perfective verbs in the Imperfect Tense in adjunct/restrictor clauses and verbs in the Imperfect Tense in main/nuclear scope clauses trigger habitual interpretations. Such interactions result in propositions that can only be true in ‘big’ situations, informally described as ‘non-accidental generalizations on repeated actions that are complete’. Furthermore, a morphological contrast between Perfective Imperfects and Perfective Aorists in adverbial adjunct clauses accounts for restrictions on the modal interpretations of imperfective aspect associated with a Viewpoint operator IMPF, and distinguishes between ongoing and habitual readings.
Spanish participial adjectives and individual-level/stage-level interpretations in nominals
Authors: Zagona Karen , Contreras Heles
Published: June 2017

This article addresses the well-known restriction on stage-level readings of pre-nominal predicative adjectives in Spanish. We argue that this restriction is due to a structural difference between ‘direct modifiers’ and ‘indirect modifiers’ as has been previously proposed in the literature (Demonte 1999; Cinque 2010). New evidence for such a distinction is introduced, based on the contrasting behavior of two classes of deverbal adjectives: se-inchoatives versus ‘perfective’ participial adjectives.
The method of shifted partial derivatives cannot separate the permanent from the determinant
Authors: Efremenko Klim , Landsberg J. , Schenck Hal , Weyman Jerzy
Published: June 2017

The method of shifted partial derivatives introduced A. Gupta et al. [Approaching the chasm at depth four, IEEE Comp. Soc., 2013, pp. 65-73] and N. Kayal [An exponential lower bound for the sum of powers of bounded degree polynomials, ECCC 19, 2010, p. 81], was used to prove a super-polynomial lower bound on the size of depth four circuits needed to compute the permanent. We show that this method alone cannot prove that the padded permanent

ℓ

n
−
m

p
e
r
m

m

\ell ^{n-m}\mathrm {perm}_m

cannot be realized inside the

G

L

n
2

GL_{n^2}

-orbit closure of the determinant

d
e
t

n

\mathrm {det}_n

when

n
>
2

m
2

+
2
m

n>2m^2+2m

. Our proof relies on several simple degenerations of the determinant polynomial, Macaulay’s theorem, which gives a lower bound on the growth of an ideal, and a lower bound estimate from [Approaching the chasm at depth four, IEEE Comp. Soc., 2013, pp. 65-73] regarding the shifted partial derivatives of the determinant.
The degenerate Eisenstein series attached to the Heisenberg parabolic subgroups of quasi-split forms of 𝑆𝑝𝑖𝑛₈
Authors: Segal Avner
Published: June 2017

In [J. Inst. Math. Jussieu 14 (2015), 149–184] and [Int. Math. Res. Not. IMRN 7 (2017), 2014–2099] a family of Rankin-Selberg integrals was shown to represent the twisted standard

L

\mathcal {L}

-function

L

(
s
,
π
,
χ
,

s
t

)

\mathcal {L}(s,\pi ,\chi ,\mathfrak {st})

of a cuspidal representation

π
\pi

of the exceptional group of type

G
2

G_2

. These integral representations bind the analytic behavior of this

L

\mathcal {L}

-function with that of a family of degenerate Eisenstein series for quasi-split forms of

S
p
i

n
8

Spin_8

associated to an induction from a character on the Heisenberg parabolic subgroup.

This paper is divided into two parts. In Part 1 we study the poles of these degenerate Eisenstein series in the right half-plane

R
e

(
s
)
>
0

\mathfrak {Re}(s)>0

. In Part 2 we use the results of Part 1 to prove the conjecture, made by J. Hundley and D. Ginzburg in [Israel J. Math. 207 (2015), 835–879], for stable poles and also to give a criterion for

π
\pi

to be a CAP representation with respect to the Borel subgroup of

G
2

G_2

in terms of the analytic behavior of

L

(
s
,
π
,
χ
,

s
t

)

\mathcal {L}(s,\pi ,\chi ,\mathfrak {st})

at

s
=

3
2

s=\frac {3}{2}

.
omiXcore: a web server for prediction of protein interactions with large RNA
Authors: Armaos Alexandros , Cirillo Davide , Gaetano Tartaglia Gian
Published: June 2017

Here we introduce omiXcore, a server for calculations of protein binding to large RNAs (> 500 nucleotides). Our webserver allows (i) use of both protein and RNA sequences without size restriction, (ii) pre-compiled library for exploration of human long intergenic RNAs interactions and (iii) prediction of binding sites.

Results

omiXcore was trained and tested on enhanced UV Cross-Linking and ImmunoPrecipitation data. The method discriminates interacting and non-interacting protein-RNA pairs and identifies RNA binding sites with Areas under the ROC curve > 0.80, which suggests that the tool is particularly useful to prioritize candidates for further experimental validation.

Availability and implementation

omiXcore is freely accessed on the web at http://service.tartaglialab.com/grant_submission/omixcore.

Supplementary information

Supplementary data are available at Bioinformatics online.
Wound Complication Rates After Staples or Suture for Midline Vertical Skin Closure in Obese Women
Authors: Kuroki Lindsay M. , Mullen Mary M. , Massad L. Stewart , Wu Ningying , Liu Jingxia , Mutch David G. , Powell Matthew A. , Hagemann Andrea R. , Thaker Premal H. , McCourt Carolyn K. , Novetsky Akiva P.
Published: June 2017

OBJECTIVE:

To compare wound complication rates after skin closure with staples and subcuticular suture in obese gynecology patients undergoing laparotomy through a midline vertical incision.

METHODS:

In this randomized controlled trial, women with body mass indexes (BMIs) of 30 or greater undergoing surgery by a gynecologic oncologist through a midline vertical incision were randomized to skin closure with staples or subcuticular 4-0 monofilament suture. The primary outcome was the rate of wound complication, defined as the presence of a wound breakdown, or infection, within 8 weeks postoperatively. Secondary outcomes included operative time, Stony Brook scar cosmetic score, and patient satisfaction. A sample size of 162 was planned to detect a 50% reduction in wound complications. At planned interim review (n=82), there was no significant difference in primary outcome.

RESULTS:

Between 2013 and 2016, 163 women were analyzed, including 84 who received staples and 79 suture. Women who received staples were older (mean age 59 compared with 57 years), had lower mean BMI (37.3 compared with 38.9), and fewer benign indications for surgery (22 compared with 27). There were no differences in wound complication rates between staple compared with suture skin closure (28 [33%] compared with 25 [32%], relative risk 1.05, 95% confidence interval [CI] 0.68–1.64). Women with staples reported worse median cosmetic scores (four of five compared with five of five, P<.001), darker scar color (37 [49%] compared with 13 [18%], relative risk 2.69, 95% CI 1.57–4.63), and more skin marks (30 [40%] compared with three [4%], relative risk 9.47, 95% CI 3.02–29.65) compared with women with suture closure. There was no group difference regarding satisfaction with their scar. Stepwise multivariate analysis revealed BMI (odds ratio [OR] 1.13, 95% CI 1.07–1.20), maximum postoperative glucose (OR 1.01, 95% CI 1.00–1.01), and cigarette smoking (OR 4.96, 95% CI 1.32–18.71) were correlates of wound complication.

CONCLUSION:

Closure of midline vertical skin incisions with subcuticular suture does not reduce surgical site wound complications compared with staples in obese gynecology patients.

CLINICAL TRIAL REGISTRATION:

ClinicalTrials.gov, NCT01977612.
False Labor at Term in Singleton Pregnancies
Authors: Nelson David B. , McIntire Donald D. , Leveno Kenneth J.
Published: June 2017

OBJECTIVE:

To evaluate perinatal outcomes in women sent home with a diagnosis of false labor at term and assess the time interval to return for delivery.

METHODS:

This was a prospective observational cohort study of women at 37 0/7 to 41 6/7 weeks of gestation without pre-existing medical complications who presented to our hospital-based triage unit with symptoms of labor and underwent a standardized evaluation. Women diagnosed as having false labor with a live singleton fetus in cephalic presentation without a prior cesarean delivery and sent home were compared with a group of similar women diagnosed to be in spontaneous labor. Women with hypertension, diabetes, and known fetal malformations were excluded. Using a perinatal composite outcome of respiratory insufficiency, intraventricular hemorrhage, culture-proven sepsis, Apgar score 3 or less at 5 minutes, phototherapy, and perinatal death, we tested the noninferiority of being sent home compared with being admitted for labor. The relationship of cervical dilatation to the time interval from discharge home to delivery was also analyzed.

RESULTS:

Between October 2012 and March 2016, a total of 3,949 women met inclusion criteria and were diagnosed with false labor, discharged, and returned to deliver, whereas 2,592 similar women were admitted in early labor. The mean interval from discharge to return was 4.9 days. Cesarean delivery rates were not different between the study groups—11% for both (P=.69), and the perinatal composite outcome rates were not significantly different between those sent home and those admitted—3.2% compared with 3.1% (P=.79). Women with more advanced cervical dilatation at discharge returned and delivered significantly earlier than those with less dilatation regardless of parity.

CONCLUSION:

Discharge with false labor at term after a standardized assessment in a triage unit was not associated with increased rates of adverse perinatal composite outcomes or cesarean delivery. The time interval to return for delivery was significantly associated with the cervical dilatation at discharge.
Timing of Etonogestrel-Releasing Implants and Growth of Breastfed Infants
Authors: Carmo Lilian Sheila de Melo Pereira , Braga Giordana Campos , Ferriani Rui Alberto , Quintana Silvana Maria , Vieira Carolina Sales
Published: June 2017

OBJECTIVE:

To evaluate the growth of breastfed infants whose mothers had inserted an etonogestrel-releasing implant in the immediate postpartum period.

METHODS:

An open, randomized controlled, and parallel trial of postpartum women who were block-randomized to early (up to 48 hours postpartum before discharge) or conventional (at 6 weeks postpartum) insertion of an etonogestrel implant. The primary outcome was average infant weight at 12 months (360 days) and a difference of equal to or greater than 10% between groups was considered clinically significant. The secondary outcomes were infant's height and head and arm circumferences. These variables were measured at baseline and at 14, 40, 90, 180, 270, and 360 days postpartum. The mixed-effects linear regression model was used to evaluate the outcomes with a power of 80% and a significance level of 1% for the primary outcome and 0.3% for secondary outcomes as a result of correction for multiple hypothesis testing.

RESULTS:

From June to August 2015, a total of 100 women were randomized: 50 to early and 50 to conventional postpartum etonogestrel insertion. Sociodemographic characteristics were similar between the groups, except for educational attainment. The conventional insertion group included a higher proportion of women with 8 or more years of formal education than the early insertion group (88% [44/50] compared with 70% [35/50], P=.02). There was no difference in infant weight at 360 days between the groups (early [mean±standard deviation] 10.1±1.2 kg compared with conventional 9.8±1.3 kg, mean difference estimate 0.3 kg, 95% confidence interval 0–0.7 kg). Growth curves, height, and head and arm circumferences did not differ between the groups.

CONCLUSION:

There is no difference in growth at 12 months among breastfed infants whose mothers underwent early compared with conventional postpartum insertion of the etonogestrel implant.

CLINICAL TRIAL REGISTRATION:

ClinicalTrials.gov, NCT02469454.
Associations of Parity, Breastfeeding, and Fractures in the Women's Health Observational Study
Authors: Crandall Carolyn J. , Liu Jingmin , Cauley Jane , Newcomb Polly A. , Manson JoAnn E. , Vitolins Mara Z. , Jacobson Lisette T. , Rykman Kelli K. , Stefanick Marcia L.
Published: June 2017

OBJECTIVE:

To examine associations of several aspects of parity and history of lactation with incident hip fractures and clinical fractures and, in a subset of women, with bone mineral density.

METHODS:

In this observational study, we analyzed data from 93,676 postmenopausal women participating in the Women's Health Initiative Observational Study and all bone density data from the subset of participants who underwent bone density testing at three clinical centers. At baseline, participants were aged 50–79 years. Using Cox proportional hazards regression analysis, we examined associations of fracture incidence and bone density with several aspects of parity (number of pregnancies, age at first pregnancy lasting 6 months or greater, and number of pregnancies lasting 6 months or greater) and breastfeeding (number of episodes of breastfeeding for at least 1 month, number of children breastfed, age when first breastfed, age when last breastfed, total number of months breastfed).

RESULTS:

The mean baseline age (standard deviation) of participants was 64 (±7.4) years (mean follow-up 7.9 years). During follow-up, the incident rate of hip fracture was 1.27%. Ten percent of participants were nulligravid. In fully adjusted models, number of pregnancies, parity, age at first birth, number of children breastfed, age at first breastfeeding, age at last breastfeeding, and total duration of breastfeeding were not statistically significantly associated with hip fracture incidence. There were no consistent associations of parity or lactation characteristics with overall clinical fracture risk or bone density. However, compared with never breastfeeding, a history of breastfeeding for at least 1 month was associated with a decreased risk of hip fracture (yes compared with no, hazard ratio 0.84, 95% confidence interval 0.73–0.98).

CONCLUSION:

Patterns of parity and history of lactation were largely unrelated to fracture risk or bone density.
Patterns of Specialty-Based Referral and Perioperative Outcomes for Women With Endometrial Cancer Undergoing Hysterectomy
Authors: Wright Jason D. , Chen Ling , Gabor Lisa , Burke William M. , Tergas Ana I. , Hou June Y. , Ananth Cande V. , Neugut Alfred I. , Hershman Dawn L.
Published: June 2017

OBJECTIVE:

To examine patterns of referral to gynecologic oncologists and perioperative outcomes based on surgeon specialty for women with endometrial cancer and hyperplasia.

METHODS:

The National Surgical Quality Improvement Program database was used to perform a retrospective cohort study of women with endometrial cancer and hyperplasia who underwent hysterectomy from 2014 to 2015. Patients were stratified based on treatment by a gynecologic oncologist or other health care provider. Patterns of referral to a gynecologic oncologist was the primary outcome, and mode of hysterectomy and complications were secondary outcomes.

RESULTS:

A total of 6,510 women were identified. Gynecologic oncologists performed 90.9% (95% confidence interval [CI] 90.1–91.7) of the hysterectomies for endometrial cancer, 66.8% (95% CI 63.1–70.4) for complex atypical endometrial hyperplasia, and 49.3% (95% CI 44.7–53.8) for endometrial hyperplasia without atypia. Older women and those with a higher American Society of Anesthesiology score were more likely to be treated by an oncologist. Minimally invasive hysterectomy was performed in 73.6% (95% CI 72.1–75.1) of women with endometrial cancer operated on by gynecologic oncologists compared with 73.8% (95% CI 68.8–78.2) of those treated by other physicians (odds ratio [OR] 0.99, 95% CI 0.80–1.23); lymphadenectomy was performed in 56.3% of women treated by gynecologic oncologists compared with 34.8% of those treated by other specialists (OR 2.42, 95% CI 1.99–2.94). Severe complications were uncommon and there was no difference in complication rates based on specialty, 2.6% (95% CI 2.2–3.1) compared with 2.0% (95% CI 0.8–3.3).

CONCLUSION:

Gynecologic oncologists provide care for the majority of women with endometrial cancer who undergo hysterectomy in the United States and are also involved in the care of a large percentage of women with endometrial hyperplasia.
All-Cause Mortality After Fertility-Sparing Surgery for Stage I Epithelial Ovarian Cancer
Authors: Melamed Alexander , Rizzo Anthony E. , Nitecki Roni , Gockley Allison A. , Bregar Amy J. , Schorge John O. , del Carmen Marcela G. , Rauh-Hain J. Alejandro
Published: June 2017

OBJECTIVE:

To compare all-cause mortality between women who underwent fertility-sparing surgery with those who underwent conventional surgery for stage I ovarian cancer.

METHODS:

In a cohort study using the National Cancer Database, we identified women younger than 40 years diagnosed with stage IA and unilateral IC epithelial ovarian cancer between 2004 and 2012. Fertility-sparing surgery was defined as conservation of one ovary and the uterus. The primary outcome was time from diagnosis to death. We used propensity score methods to assemble a cohort of women who underwent fertility-sparing or conventional surgery but were otherwise similar on observed covariates and conducted survival analyses using the Kaplan–Meier method and Cox proportional hazard models.

RESULTS:

We identified 1,726 women with stage IA and unilateral IC epithelial ovarian cancer of whom 825 (47.8%) underwent fertility-sparing surgery. Fertility-sparing surgery was associated with younger age, residence in the northeastern and western United States, and serous or mucinous histology (P<.05 for all). Propensity score matching yielded a cohort of 904 women who were balanced on observed covariates. We observed 30 deaths among women who underwent fertility-sparing surgery and 37 deaths among propensity-matched women who underwent conventional surgery after a median follow-up of 63 months. Fertility-sparing surgery was not associated with hazard of death (hazard ratio 0.80, 95% confidence interval [CI] 0.49–1.29,P=.36). The probability of survival 10 years after diagnosis was 88.5% (95% CI 82.4–92.6) in the fertility-sparing group and 88.9% (95% CI 84.9–92.0) in the conventional surgery group. In patients with high-risk features such as clear cell histology, grade 3, or stage IC, 10-year survival was 80.5% (95% CI 68.5–88.3) among women who underwent fertility-sparing surgery and 83.4% (95% 76.0–88.7) among those who had conventional surgery (hazard ratio 0.86, 95% CI 0.49–1.53,P=.61).

CONCLUSION:

Compared with conventional surgery, fertility-sparing surgery was not associated with increased risk of death in young women with stage I epithelial ovarian cancer.
Is There a Role for Oral Antibiotic Preparation Alone Before Colorectal Surgery? ACS-NSQIP Analysis by Coarsened Exact Matching
Authors: Garfinkle Richard , Abou-Khalil Jad , Morin Nancy , Ghitulescu Gabriela , Vasilevsky Carol-Ann , Gordon Philip , Demian Marie , Boutros Marylise
Published: June 2017

BACKGROUND:

Recent studies demonstrated reduced postoperative complications using combined mechanical bowel and oral antibiotic preparation before elective colorectal surgery.

OBJECTIVE:

The aim of this study was to assess the impact of these 2 interventions on surgical site infections, anastomotic leak, ileus, major morbidity, and 30-day mortality in a large cohort of elective colectomies.

DESIGN:

This is a retrospective comparison of 30-day outcomes using the American College of Surgeons National Surgical Quality Improvement Program colectomy-targeted database with coarsened exact matching.

SETTINGS:

Interventions were performed in hospitals participating in the national surgical database.

PATIENTS:

Adult patients who underwent elective colectomy from 2012 to 2014 were included.

INTERVENTIONS:

Preoperative bowel preparations were evaluated.

MAIN OUTCOME MEASURES:

The primary outcomes measured were surgical site infections, anastomotic leak, postoperative ileus, major morbidity, and 30-day mortality.

RESULTS:

A total of 40,446 patients were analyzed: 13,219 (32.7%), 13,935 (34.5%), and 1572 (3.9%) in the no-preparation, mechanical bowel preparation alone, and oral antibiotic preparation alone groups, and 11,720 (29.0%) in the combined preparation group. After matching, 9800, 1461, and 8819 patients remained in the mechanical preparation, oral antibiotic preparation, and combined preparation groups for comparison with patients without preparation. On conditional logistic regression of matched patients, oral antibiotic preparation alone was protective of surgical site infection (OR, 0.63; 95% CI, 0.45–0.87), anastomotic leak (OR, 0.60; 95% CI, 0.34–0.97), ileus (OR, 0.79; 95% CI, 0.59–0.98), and major morbidity (OR, 0.73; 95% CI, 0.55–0.96), but not mortality (OR, 0.32; 95% CI, 0.08–1.18), whereas a regimen of combined oral antibiotics and mechanical bowel preparation was protective for all 5 major outcomes. When directly compared with oral antibiotic preparation alone, the combined regimen was not associated with any difference in any of the 5 postoperative outcomes.

LIMITATIONS:

This study was limited by its retrospective design with heterogeneous data.

CONCLUSIONS:

Oral antibiotic preparation alone significantly reduced surgical site infection, anastomotic leak, postoperative ileus, and major morbidity after elective colorectal surgery. A combined regimen of oral antibiotics and mechanical bowel preparation offered no superiority when compared with oral antibiotics alone for these outcomes. See Video Abstract at http://links.lww.com/DCR/A358.
Why apply for an intercalated research degree?
Authors: Agha Riaz , Fowler Alex , Whitehurst Katharine , Rajmohan Shivanchan , Gundogan Buket , Koshy Kiron
Published: June 2017

Intercalated degrees are commonly undertaken as part of the medical undergraduate course. In this article, we discuss the advantages and disadvantages of intercalation, along with alternatives that could be considered.
Repeat Revascularization after Minimally Invasive Coronary Artery Bypass Grafting
Authors: Rodriguez Maria L. , Lapierre Harry R. , Sohmer Benjamin F. , Ruel Marc A.
Published: June 2017

Objective

Minimally invasive coronary artery bypass grafting (MICS CABG) via a small left thoracotomy is a novel technique for coronary revascularization that is increasingly used around the world. However, multivessel MICS CABG is difficult, and concerns about repeat revascularization (RR) have been raised. This longitudinal study describes the rates of RR among patients who have undergone MICS CABG and identifies targets for improvement.

Methods

A prospective observational study was performed on the 306 MICS CABG patients operated on by a single surgeon from 2005 to 2015. Minimally invasive coronary artery bypass grafting was performed through a small left thoracotomy, using the in situ left internal mammary artery, ± a radial artery, and 1 to 3 saphenous veins anastomosed proximally to the aorta. Patients were followed annually. We examined the difference between the first half and second half of the series to ascertain the effects of a learning curve.

Results

Eighty percent of the procedures were performed off-pump. The median number of grafts performed were 2, and the left anterior descending, diagonals, obtuse marginals, and posterior interventricular artery were the distal targets in 94%, 12%, 44%, and 26%, respectively. The graftability index (#grafts/#diseased vessels) was 0.93. Revascularization of targets smaller than 1.5 mm decreased from 69% to 50% ( P = 0.002) between the series’ first and second halves. Overall, RR was needed in 21 patients (6.9%) and was performed at a mean ± SD of 1.7 ± 1.6 years postoperatively. The culprit lesion was attributed to the index surgical procedure (“graft-associated”) in 52%, to a stent stenosis or progression of native disease in 43%, and was unidentified in 5%. Patients with graft-associated RR had a lower graftability index at operation (0.73 vs 0.94) and more frequent involvement of the circumflex system (0.8 vs 0.3). The overall rate of RR at 3 years decreased from 11% in the first half to 2.6% in the second half ( P = 0.001).

Conclusions

The need for RR is part of the learning curve with MICS CABG, involves a graft in half of the cases, is more common in patients who had a lower graftability index at operation, and markedly improves with experience.
Comparing Population-based Risk-stratification Model Performance Using Demographic, Diagnosis and Medication Data Extracted From Outpatient Electronic Health Records Versus Administrative Claims
Authors: Kharrazi Hadi , Chi Winnie , Chang Hsien-Yen , Richards Thomas M. , Gallagher Jason M. , Knudson Susan M. , Weiner Jonathan P.
Published: June 2017

Background:

There is an increasing demand for electronic health record (EHR)–based risk stratification and predictive modeling tools at the population level. This trend is partly due to increased value-based payment policies and the increasing availability of EHRs at the provider level. Risk stratification models, however, have been traditionally derived from claims or encounter systems. This study evaluates the challenges and opportunities of using EHR data instead of or in addition to administrative claims for risk stratification.

Methods:

This study used the structured EHR records and administrative claims of 85,581 patients receiving outpatient care at a large integrated provider system. Common data elements for risk stratification (ie, age, sex, diagnosis, and medication) were extracted from outpatient EHR records and administrative claims. The performance of a validated risk-stratification model was assessed using data extracted from claims alone, EHR alone, and claims and EHR combined.

Results:

EHR-derived metrics overlapped considerably with administrative claims (eg, number of chronic conditions). The accuracy of the model, when using EHR data alone, was acceptable with an area under the curve of ∼0.81 for hospitalization and ∼0.85 for identifying top 1% utilizers using the concurrent model. However, when using EHR data alone, the predictive model explained a lower amount of variation in utilization-based outcomes compared with administrative claims.

Discussion:

The results show a promising performance of models predicting cost and hospitalization using outpatient EHR’s diagnosis and medication data. More research is needed to evaluate the benefits of other EHR data types (eg, lab values and vital signs) for risk stratification.