bluuebunny/crossref_metadata_2025 huggingface dataset:
From the degenerate quantum compressible Navier-Stokes-Poisson system to incompressible Euler equations
Authors: Kwon Young-Sam
Published: December 2018

In this paper, we study the convergence from the degenerate quantum compressible Navier-Stokes-Poisson system on a unbounded domain R2×T with general initial data to the incompressible Euler equation with the damping term. We prove rigorously that the weak solutions of the degenerate quantum compressible Navier-Stokes-Poisson system converge to the strong solution of the incompressible Euler equations with a linear damping term, and the result is proven by applying the refined relative entropy method and carrying out the detailed analysis on the oscillations of velocity. Furthermore, the convergence rates are obtained. To handle the oscillations of velocity, we use the dispersive estimates of acoustic systems in the work of D. Donatelli, E. Feireisl, and A. Novotny, Math. Models Methods Appl. Sci. 25(2), 371–394 (2015).
Variable-deceleration-ratio wide-acceptance-angle electrostatic lens for two-dimensional angular and energy analysis
Authors: Matsuda Hiroyuki , Tóth László , Daimon Hiroshi
Published: December 2018

Variable-deceleration-ratio wide-acceptance-angle electrostatic lens (VD-WAAEL) is proposed as a potential technique for two-dimensional angular and energy analysis. The basic features of the lens are studied using the charge simulation method and ray tracing calculation. The lens uses an ellipsoidal mesh electrode and allows a wide acceptance angle of ±50°. Two possible applications of the VD-WAAEL are discussed. One is a simple combination of the VD-WAAEL-projection-lens, in which an aperture is used for energy analysis. The other is a combination of the VD-WAAEL with a conventional electron spectrometer, which is responsible for obtaining higher energy resolution. The former is discussed in detail and the latter is described briefly. While the ray tracing calculation is only for the case of an ideal mesh, a note on the disturbing effect of mesh holes is presented. The best possible energy resolution of the simple VD-WAAEL-projection-lens analyzer seems to be around 1/1000, given a fine mesh electrode to suppress the disturbing effect of mesh holes.
Near-infrared optical investigations of snow, ice, and water layers on diffuse reflecting surfaces
Authors: Baumgartner A. , Amann S. , Werz M. , Herkommer A. , Dressel M. , Fella S.
Published: December 2018

While most experiments on water or ice utilize rather complex, elaborate, and expensive apparatus in order to obtain reliable optical data, here we present a simple and affordable setup that enables us to perform near-infrared measurements on water, ice, and snow on top of rough diffuse reflecting surfaces such as concrete, stone, pavement, or asphalt. By using the properties of diffuse scattering instead of specular reflection, we are able to determine the imaginary part of the refraction index of water without using any liquid cells. In addition, we demonstrate that the snow spectra can be well described by newly developed two-dimensional ray tracing simulations.
Generation of cylindrical and elliptical symmetrical vector beam on the Mach–Zehnder interferometer
Authors: Xu Xiang , Zhou Yuan , Yuan Yang-Sheng , Wang Jun , Xu Hua-Feng , Qu Jun
Published: December 2018

We propose a principal scheme to generate the cylindrical and the elliptical symmetrical vector beam based on a modified Mach-Zehnder interferometer. The modified Mach-Zehnder interferometer, the wave plates, the Polarizing Beam Splitter (PBS) and the Dove prism are used in this optical system. Two different order polarized beams can be generated and combined by this system and the arbitrary-order cylindrical and elliptical vector beams can be obtained. With the help of this simple optical system, the various profile vector beams can be generated flexibly.
Gibbs free-energy differences between polymorphs via a diabat approach
Authors: Kamat Kartik , Peters Baron
Published: December 2018

Polymorph free-energy differences are critical to several applications. A recently proposed diabat interpolation framework estimated free-energy differences between polymorphs by quadratic interpolation of diabats. This work extends the Zwanzig-Bennett relation to the NPT ensemble so that the diabats directly give Gibbs free-energy differences. We also demonstrate how the approach can be used in cases where the diabats are not parabolic. We illustrate the diabat method for Gibbs free-energy difference of zirconium (BCC and HCP phases) and compare it with the conventional lattice switch Monte Carlo approach.
Interface properties study on SiC MOS with high-k hafnium silicate gate dielectric
Authors: Liang Lin , Li Wei , Li Sichao , Li Xuefei , Wu Yanqing
Published: December 2018

High k dielectrics, such as Al2O3, has attracted increasing research attention for its use as the gate dielectric of 4H-SiC MOS capacitors. Since the dielectric constant of Al2O3 is not high enough, many other high-k dielectrics are actively explored. In this letter, a report of the interface properties of 4H-SiC MOS capacitors with Hafnium silicate (HfSiOx) dielectric is presented. The HfSiOx dielectric was deposited by thermal atomic layer deposition. A systematic study of I-V and multi-frequency C-V characteristics were carried out and the results showed HfSiOx gate dielectric could effectively increase dielectric constant. A thin layer of SiO2 in between SiC and high k dielectric can further improve interface properties. These results indicate that HfSiOx could be a promising candidate as suitable gate dielectric material for future 4H-SiC MOS capacitors and MOSFETs.
Parallel propagation and damping of electromagnetic waves in a partially ionized plasma with multiple species
Authors: Huang Yifan , Tu Jiannan , Song Paul
Published: December 2018

We study the propagation of electromagnetic waves (or incompressible waves with negligible thermal pressure) along the magnetic field in a partially ionized plasma with multiple species. Because of differences in mass and density, each species responds to and hence affects the perturbations of electromagnetic fields differently. Collisions among all the species further complicate the process. With a linear analysis, the dispersion relation of parallel propagation covering a large range of frequencies, from magnetohydrodynamics (MHD) waves to light waves, with an arbitrary combination of multiple positively charged species, negatively charged species, and neutral species is derived based on a multi-fluid treatment, in combination with Faraday's law and Ampere's law including the displacement current. In a collisional plasma, when the collision frequency is lower than the gyrofrequencies of charged species, the resonances are at the gyrofrequencies of each charged species and the cutoff frequencies are related to the densities of the charged species. Stopbands in which waves propagate with extremely high phase velocity but are strongly damped form between some of these characteristic frequencies. In the MHD wave frequency range, the coupling with neutral species slows the propagation speed compared with the Alfvén speed. The collisions between plasma and neutrons efficiently contribute to the wave damping, which is significantly reduced when the neutral species are completely driven with plasma by collisions. When the collisions become stronger, the resonances and cutoffs become weaker and may disappear. The species could couple tightly and act as a single fluid if the collisions among them are strong enough.
Optical properties of quasi-type-II structure in GaAs/GaAsSb/GaAs coaxial single quantum-well nanowires
Authors: Li Haolin , Tang Jilong , Kang Yubin , Zhao Haixia , Fang Dan , Fang Xuan , Chen Rui , Wei Zhipeng
Published: December 2018

The GaAsSb-based quantum well plays a very important role in optoelectronic devices due to its excellent wavelength tunability. When the dimension reduces, the quantum confinement effect will take place and the quantum well in nanowires will show many interesting characteristics. GaAsSb-based quantum-well nanowires are of contemporary interest. However, the properties of the quasi-type-II structure in a single quantum well nanowire have been rarely investigated. Here, we grow GaAs/GaAs0.92Sb0.08/GaAs coaxial single quantum-well nanowires and discussed their power-dependent and temperature-dependent photoluminescence. We find that due to the small band offset of conduction bands, both type-I like and type-II like emission exist in our nanowires. When electrons obtain enough thermal energy through collisions or surrounding environment, they will overcome the barrier and diffuse to the GaAs conduction band, which contributes to the type-II like recombination. These results show the optical property of the quasi-type-II quantum well in nanowires, which can pave the way toward future nanoscale quantum well devices.
Real-time monitoring of stress evolution during thin film growth by in situ substrate curvature measurement
Authors: Gilardi Elisa , Fluri Aline , Lippert Thomas , Pergolesi Daniele
Published: December 2018

Strain engineering is the art of inducing controlled lattice distortions in a material to modify specific physicochemical properties. Strain engineering is applied not only for basic fundamental studies of physics and chemistry of solids but also for device fabrication through the development of materials with new functionalities. Thin films are one of the most important tools for strain engineering. Thin films can in fact develop large strain due to the crystalline constraints at the interface with the substrate and/or as a result of specific morphological features that can be selected by an appropriate tuning of the deposition parameters. Within this context, the in situ measurement of the substrate curvature is a powerful diagnostic tool allowing real time monitoring of the stress state of the growing film. This paper reviews a few recent applications of this technique and presents new measurements that point out the great potentials of the substrate curvature measurement in strain engineering. Our study also shows how, due to the high sensitivity of the technique, the correct interpretation of the results can be in certain cases not trivial and require complementary characterizations and an accurate knowledge of the physicochemical properties of the materials under investigation.
Nonlinear acoustic-power measurement based on fundamental focal axial vibration velocity for high-intensity focused ultrasound
Authors: Li Yuzhi , Tao Chenyang , Ma Qingyu , Guo Gepu , Zhang Dong , Hu Jimin
Published: December 2018

The acoustic power (AP) of high-intensity focused ultrasound (HIFU) shows great potential for ensuring the efficacy and safety of tumor treatment. By considering the energy of the harmonics, an easily applicable nonlinear AP measurement method for HIFU based on the fundamental focal axial vibration velocity (F-FAVV) is proposed. The focal pressures of the harmonics with respect to the surface vibration velocity are simulated, and a piecewise function of the required harmonic order is developed based on the 40-dB attenuation criterion of the harmonic-to-fundamental ratio. With the relationships between the power gain and the FAVVs of the harmonics, the dependence of AP on the F-FAVV is achieved by summing the harmonic powers. The APs of HIFU under various surface vibration velocities are verified by experimental measurements of the F-FAVV using a laser vibrometer and the corresponding integration results over the transducer surface. Good agreement between the numerical and experimental results demonstrates the feasibility of accurate AP measurement for HIFU using the F-FAVV and suggests the potential for applications in biomedical engineering.
Self-polarization effect on large photovoltaic response in lead free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 epitaxial film
Authors: Swain Atal Bihari , Rath Martando , Pal Subhajit , Ramachandra Rao M. S. , Subramanian V. , Murugavel P.
Published: December 2018

An epitaxial lead free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) thin film is fabricated on a (001)Nb:SrTiO3 single crystalline substrate by the pulsed laser deposition method. The 2.3% lattice mismatch between the BZT-BCT and substrate suggests that the film is grown under a compressively strained state by leaving a large strain gradient near the interface. Polarization versus electric field measurement reveals that the film exhibits a ferroelectric hysteresis character with a large imprint effect indicating the existence of an internal electric field. The origin of the internal electric field is correlated with the strain gradient induced flexoelectric effect and the interfacial built-in field. Consequently, the resultant internal electric field could lead to a self-polarized non-switchable layer at the interface. The evidence for the envisaged self-polarization effect is indeed shown by the piezo force microscopic measurements. Importantly, photovoltaic studies performed on the film display an open circuit voltage of 1.1 V, which is higher than the values reported for many ferroelectric films. The observed photovoltaic response is correlated with the depolarization field and the self-polarization effect. The demonstrated large photo-response illustrates the application potential of the BZT-BCT system in photovoltaic devices.
Starch sources and concentration in diet of dairy goats affected ruminal pH and fermentation, and inflammatory response
Authors: Shen Yizhao , Zhao Fangfang , Yu Lihuai , Yang Wenzhu , Wang Mengzhi , Wang Hongrong
Published: December 2018

Corn and wheat grains are two starch sources with considerably different ruminal digestion rates, which may lead to differing lipopolysaccharide (LPS) release in both rumen and hindgut affecting animal production. The objectives of this study were to (1) investigate the effects of different ruminal and faecal LPS concentrations induced by starch source (corn vs wheat) and starch concentrations (low vs high) on DMI, ruminal pH, ruminal fermentation patterns, milk production, and inflammatory responses; and (2) evaluate the possible translocation site of LPS in dairy goats. Eight lactating dairy goats with ruminal cannulas were used in a replicated 4 × 4 Latin square design with 2 × 2 factorial arrangement of treatments. Each experimental period consisted of 24 days long including 21 days for adaption and 3 days for data and sample collection. The four treatment diets were: corn and wheat grain combined with low (LS) and high grain starch (HS). Goats were fed equal amounts of a total mixed ration twice daily at 0700 hours and 1900 hours. Replacing corn with wheat in goat diet led to longer (P < 0.02) duration of ruminal pH <5.6, higher ruminal LPS (P < 0.05), but lower faecal LPS concentration. However, no differences between two grains in ruminal pH (mean, minimum and maximum), volatile fatty acids (VFA) and lactic acid concentration were observed. Goats fed HS diets had lower (P < 0.01) ruminal pH and higher (P < 0.01) ruminal concentrations of VFA and lactic acid, as well as higher (P < 0.01) ruminal and faecal LPS concentrations. Starch source did not affect DMI, milk yield and milk components whereas feeding HS versus LS diet had higher milk yield, lactose yield and improved milk efficiency (P < 0.05). Feeding wheat- versus corn-based diet showed only greater (P < 0.05) concentration of toll-like receptor-4, whereas feeding the HS versus LS diet consistently increased blood concentrations of amyloid A, haptoglobin, LPS binding protein, and LPS (P < 0.05). Analysis of Pearson correlation coefficients illustrated that the ruminal LPS concentration is more important than faecal LPS in inflammatory responses. In conclusion, replacing corn with wheat in lactating goat diet had negative impact on ruminal pH but little effects on fermentation characteristics and milk production. Increasing the dietary concentration of starch decreased ruminal pH status and thus increased risk of acidosis, whereas, feeding HS versus LS diets resulted in an improvement in milk yield, milk efficiency, and immunity response. Moreover, rumen acidosis induced by wheat based diet was accompanied with more severe inflammatory responses.
Floral traits predict pollination syndrome in Syzygium species: a study on four endemic species of the Western Ghats, India
Authors: Kuriakose Giby , Sinu Palatty Allesh , Shivanna K. R.
Published: December 2018

Pollination ecology and the breeding system of four endemic species of Syzygium (S. heyneanum, S. travancoricum, S. laetum and S. mundagam) of the Western Ghats, India are investigated. The floral traits are used for ordination analysis to understand if the species form any cryptic groups and whether this grouping predicts the pollination syndrome and the breeding system. Pollinators were distinguished from frequent visitors by studying their efficiency to transfer pollen to the stigma or induce fruit set following their exclusive visit to virgin flowers. The species formed two groups in the ordination map: the S. heyneanum and S. travancoricum group and the S. laetum and S. mundagam group. The flowers of studied species attracted 3–23 species of animals during the day, but none were encountered during the night. Flowers of S. heyneanum and S. travancoricum were visited by a large number of insect species of which only a limited number turned out to be the pollinators. S. laetum and S. mundagam attracted two bird species apart from a few insect species. In S. laetum, although birds did not bring about pollination directly, their visits facilitated anemophily by releasing pollen to the air by causing physical disturbance to the flowers. In S. mundagam, both birds and wind were involved in pollination. S. heyeanum and S. travancoricum were fully self-compatible, whereas S. laetum and S. mundagam were partially self-compatible.
VIPER is a genetically encoded peptide tag for fluorescence and electron microscopy
Authors: Doh Julia K. , White Jonathan D. , Zane Hannah K. , Chang Young Hwan , López Claudia S. , Enns Caroline A. , Beatty Kimberly E.
Published: December 2018

Significance

We are entering a new era in cell cartography, wherein proteins and multiprotein complexes will be mapped with nanoscale precision using advanced instrumentation. The central obstacle hindering progress in this area is the shortage of methods for labeling proteins for imaging by both fluorescence microscopy and electron microscopy. In this report, we describe a technology for tracking and mapping proteins by multiscale microscopy. To do this, we developed an innovative technology called VIPER. VIPER consists of a heterodimeric coiled-coil between a genetically encoded peptide tag (CoilE) and a reporter-conjugated peptide (CoilR). The key finding is that VIPER delivers a variety of chemical reporters, thus enabling effortless switching from fluorescence microscopy to high-resolution electron microscopy imaging without changing the genetically encoded tag.
Hybrid prevalence estimation: Method to improve intervention coverage estimations
Authors: Jeffery Caroline , Pagano Marcello , Hemingway Janet , Valadez Joseph J.
Published: December 2018

Significance

Over the last 2 decades, low- and middle-income countries have moved from fragmented paper-based systems to electronic health information systems (HIS). Although these are a major advance, they are not well suited to drive operational policy decisions and detect gaps in service coverage. To avoid overreliance on administrative estimates from HIS, probability surveys of population coverage are increasingly used operationally. By combining the probability survey and HIS data, a hybrid prevalence estimate can be generated that can be used to validate and/or moderate HIS administrative estimates of coverage.
Some reflections on the syllabification of clusters
Authors: Passino Diana
Published: December 2018

Throughout different theoretical models it is generally agreed that syllable structure is only determined by the melodic composition of segments and predictions are made concerning the syllabification of clusters on the basis of their segmental content. This contribution draws attention on empirical data showing that the predictions are not always verified, arguing in favour of a refinement of the theoretical tools proposed so far to derive cluster syllabification.
Reforming Canada's Dairy Sector: USMCA and the Issue of Compensation
Authors: van Kooten G. Cornelis
Published: December 2018

Supply management (SM) in Canada's dairy sector was an obstacle to the successful renegotiation of the North American Free Trade Agreement. Reform of agricultural SM regimes in sugar, peanuts, tobacco, and dairy in various jurisdictions are reviewed, and an analytic framework is developed to investigate how Canada might eliminate its dairy quota regime while not overcompensating producers. Compensation based on quota values amount to $5.9 billion if untargeted, but only $2.9 billion if targeted; in contrast, theoretically correct estimates of the loss that dairy producers would face range from $0.2 to $1.9 billion. Such costs are low enough not to impede the elimination of supply management.
DensityPath: an algorithm to visualize and reconstruct cell state-transition path on density landscape for single-cell RNA sequencing data
Authors: Chen Ziwei , An Shaokun , Bai Xiangqi , Gong Fuzhou , Ma Liang , Wan Lin
Published: December 2018

Motivation

Visualizing and reconstructing cell developmental trajectories intrinsically embedded in high-dimensional expression profiles of single-cell RNA sequencing (scRNA-seq) snapshot data are computationally intriguing, but challenging.

Results

We propose DensityPath, an algorithm allowing (i) visualization of the intrinsic structure of scRNA-seq data on an embedded 2-d space and (ii) reconstruction of an optimal cell state-transition path on the density landscape. DensityPath powerfully handles high dimensionality and heterogeneity of scRNA-seq data by (i) revealing the intrinsic structures of data, while adopting a non-linear dimension reduction algorithm, termed elastic embedding, which can preserve both local and global structures of the data; and (ii) extracting the topological features of high-density, level-set clusters from a single-cell multimodal density landscape of transcriptional heterogeneity, as the representative cell states. DensityPath reconstructs the optimal cell state-transition path by finding the geodesic minimum spanning tree of representative cell states on the density landscape, establishing a least action path with the minimum-transition-energy of cell fate decisions. We demonstrate that DensityPath can ably reconstruct complex trajectories of cell development, e.g. those with multiple bifurcating and trifurcating branches, while maintaining computational efficiency. Moreover, DensityPath has high accuracy for pseudotime calculation and branch assignment on real scRNA-seq, as well as simulated datasets. DensityPath is robust to parameter choices, as well as permutations of data.

Availability and implementation

DensityPath software is available at https://github.com/ucasdp/DensityPath.

Supplementary information

Supplementary data are available at Bioinformatics online.
Evaluation of methods for generative modeling of cell and nuclear shape
Authors: Ruan Xiongtao , Murphy Robert F
Published: December 2018

Motivation

Cell shape provides both geometry for, and a reflection of, cell function. Numerous methods for describing and modeling cell shape have been described, but previous evaluation of these methods in terms of the accuracy of generative models has been limited.

Results

Here we compare traditional methods and deep autoencoders to build generative models for cell shapes in terms of the accuracy with which shapes can be reconstructed from models. We evaluated the methods on different collections of 2D and 3D cell images, and found that none of the methods gave accurate reconstructions using low dimensional encodings. As expected, much higher accuracies were observed using high dimensional encodings, with outline-based methods significantly outperforming image-based autoencoders. The latter tended to encode all cells as having smooth shapes, even for high dimensions. For complex 3D cell shapes, we developed a significant improvement of a method based on the spherical harmonic transform that performs significantly better than other methods. We obtained similar results for the joint modeling of cell and nuclear shape. Finally, we evaluated the modeling of shape dynamics by interpolation in the shape space. We found that our modified method provided lower deformation energies along linear interpolation paths than other methods. This allows practical shape evolution in high dimensional shape spaces. We conclude that our improved spherical harmonic based methods are preferable for cell and nuclear shape modeling, providing better representations, higher computational efficiency and requiring fewer training images than deep learning methods.

Availability and implementation

All software and data is available at http://murphylab.cbd.cmu.edu/software.

Supplementary information

Supplementary data are available at Bioinformatics online.
Comparison of vulnerability to catastrophic wind between Abies plantation forests and natural mixed forests in northern Japan
Authors: Morimoto Junko , Nakagawa Kosuke , Takano Kohei T , Aiba Masahiro , Oguro Michio , Furukawa Yasuto , Mishima Yoshio , Ogawa Kenta , Ito Rui , Takemi Tetsuya , Nakamura Futoshi , Peterson Chris J
Published: December 2018

The risk of extreme events due to weather and climate change, such as winds of unprecedented magnitude, is predicted to increase throughout this century. Artificial ecosystems, such as coniferous plantation forests, can suffer irreversible deterioration due to even a slight change in environmental conditions. However, few studies have examined the effects of converting natural forests to plantations on their vulnerability to catastrophic winds. By modelling the 2004 windthrow event of Typhoon Songda in northern Japan using the random forest machine learning method, we answered two questions: do Abies plantation forests and natural mixed forests differ in their vulnerability to strong winds and how do winds, topography and forest structure affect their vulnerability. Our results show that Abies plantation forests are more vulnerable to catastrophic wind than natural mixed forests under most conditions. However, the windthrow process was common to both types of forests, and the behaviour of wind inside the forests may determine the windthrow probability. Future management options for adapting to climate change were proposed based on these findings, including modifications of plantation forest structure to reduce windthrow risk and reconversion of plantations to natural forests.
Influence of fluids on VP/VS ratio: increase or decrease?
Authors: Brantut Nicolas , David Emmanuel C
Published: December 2018

The evolution of the ratio between P- and S-wave velocities (VP/VS) with increasing fluid-saturated porosity is computed for isotropic rocks containing spheroidal pores. The ratio VP/VS is shown to either decrease or increase with increasing porosity, depending on the aspect ratio α of the pores, fluid to solid bulk modulus ratio ζ and Poisson’s ratio ν0 of the solid constituents of the rock. A critical initial Poisson’s ratio ν0, crit is computed, separating cases where VP/VS increases (if ν0 < ν0, crit) or decreases (if ν0 > ν0, crit) with increasing porosity. For thin cracks and highly compressible fluids, ν0, crit is approximated by $0.157\, \zeta /\alpha$, whereas for spherical pores ν0, crit is given by 0.2 + 0.8ζ. When ν0 is close to ν0, crit, the evolution of VP/VS with increasing fluid-saturated porosity is near neutral and depends on subtle changes in pore shape and fluid properties. This regime is found to be relevant to partially dehydrated serpentinites in subduction zones (porosity of aspect ratio near 0.1 and ζ in the range 0.01–0.1), and makes detection of these rocks and possibly elevated fluid pressures difficult from VP/VS only.
Evolution of the Yeast Recombination Landscape
Authors: Liu Haoxuan , Maclean Calum J , Zhang Jianzhi
Published: December 2018

Meiotic recombination comprises crossovers and noncrossovers. Recombination, crossover in particular, shuffles mutations and impacts both the level of genetic polymorphism and the speed of adaptation. In many species, the recombination rate varies across the genome with hot and cold spots. The hotspot paradox hypothesis asserts that recombination hotspots are evolutionarily unstable due to self-destruction. However, the genomic landscape of double-strand breaks (DSBs), which initiate recombination, is evolutionarily conserved among divergent yeast species, casting doubt on the hotspot paradox hypothesis. Nonetheless, because only a subset of DSBs are associated with crossovers, the evolutionary conservation of the crossover landscape could differ from that of DSBs. Here, we investigate this possibility by generating a high-resolution recombination map of the budding yeast Saccharomyces paradoxus through whole-genome sequencing of 50 meiotic tetrads and by comparing this recombination map with that of S. cerevisiae. We observe a 40% lower recombination rate in S. paradoxus than in S. cerevisiae. Compared with the DSB landscape, the crossover landscape is even more conserved. Further analyses indicate that the elevated conservation of the crossover landscape is explained by a near-subtelomeric crossover preference in both yeasts, which we find to be attributable at least in part to crossover interference. We conclude that the yeast crossover landscape is highly conserved and that the evolutionary conservation of this landscape can differ from that of the DSB landscape.
Draft Opioid-Prescribing Guidelines for Uncomplicated Normal Spontaneous Vaginal Birth
Authors: Mills J. Rebecca , Huizinga Mary Margaret , Robinson Scott B. , Lamprecht Lara , Handler Arden , Petros Michael , Davis Teresa , Chan Kee
Published: December 2018

Women who experience an uncomplicated vaginal delivery have acute intrapartum pain and variable pain in the immediate postpartum period. Although the Centers for Disease Control and Prevention (CDC) has urged clinicians to improve opioid-prescribing behavior, there are no published clinical practice guidelines for prescribing opioids during labor and delivery and at discharge for patients with uncomplicated normal spontaneous vaginal delivery. To address the knowledge gap regarding guidelines for pain management in this population, we used the national Premiere Health Care Database for deliveries of uncomplicated vaginal births from January 1, 2014, to December 31, 2016, to determine the prevalence of opioid administration. Among the 49,133 women who met inclusion criteria, 78.2% were administered opioids during hospitalization and 29.8% were administered opioids on the day of discharge. Descriptive statistics were generated to document the characteristics of the patients receiving opioids as well as the characteristics of hospitals administering opioids during inpatient labor and delivery and on discharge. Patient-level variables included age group, marital status, race, ethnicity, payer type, and length of stay. Hospital-level variables included bed size, geographic region, teaching status, and urbanicity status. These data were then presented in an electronic Delphi survey to 14 participants. The survey participants were obstetrician–gynecologists identified by the American College of Obstetricians and Gynecologists as being thought leaders in the obstetrics field and who had also demonstrated an active interest in the opioid epidemic and its effect on women's health. After the panelists viewed the opioid administration data, they were presented with an adapted version of the CDC’s guidelines for opioid prescribing for chronic pain management. The eight adapted guidelines were constructed to be more relevant and appropriate for the inpatient normal spontaneous vaginal delivery population. After three rounds of the surveying process, seven of the eight adapted guidelines were endorsed by the survey participants. These seven draft consensus guidelines could now be used as a starting point to develop more broadly endorsed and studied guidelines for appropriately managing pain control for women with uncomplicated spontaneous vaginal birth.
Stage IV Gestational Choriocarcinoma Diagnosed in the Third Trimester
Authors: Jorgensen Kirsten , Roychowdhury Monika , da Cunha Grace , Kim Young Bae , Schorge John O.
Published: December 2018

BACKGROUND:

Gestational trophoblastic neoplasia rarely occurs in term pregnancies. Stage IV choriocarcinoma treated with conventional chemotherapy can result in death as a result of hemorrhagic sequelae at tumor sites.

CASE:

A 30-year-old woman at 34 weeks of gestation presented with a persistent cough, worsening dyspnea, and vaginal bleeding. Chest radiograph demonstrated innumerable lung nodules, and quantitative β-hcg concentration exceeded 1.3 million milli-international units/mL. Cesarean delivery was performed for presumed abruption. Placental pathology demonstrated choriocarcinoma, and imaging confirmed stage IV disease with a World Health Organization score of 14. Remission was achieved after two courses of low-dose induction chemotherapy followed by 10 cycles of combination chemotherapy.

CONCLUSION:

Gestational trophoblastic neoplasia should be considered in a pregnant or postpartum woman presenting with atypical vaginal bleeding. Coexistent pulmonary or neurologic findings may suggest advanced disease.
Efficacy of Misoprostol Alone for First-Trimester Medical Abortion
Authors: Raymond Elizabeth G. , Harrison Margo S. , Weaver Mark A.
Published: December 2018

OBJECTIVE:

To summarize available data on the effectiveness and safety of single-agent misoprostol for medical abortion in the first trimester.

DATA SOURCES:

We searched MEDLINE, CABI, Cochrane, EMBASE, LILACS, the Web of Science, and ClinicalTrials.gov for English-language studies that evaluated misoprostol alone for abortion of a viable pregnancy in the first trimester.

METHODS OF STUDY SELECTION:

Our search yielded 1,562 citations, of which 38 included data from 53 trial groups that met our inclusion and exclusion criteria.

TABULATION, INTEGRATION, AND RESULTS:

We abstracted data about each trial group, including study characteristics, treatment regimen, clinical protocol, number of women treated and followed, and numbers with outcomes of interest. We used meta-analytic methods and logistic regression to examine factors associated with surgical intervention after treatment. Among all 12,829 evaluable women, 2,536 (meta-analytic estimate 22.0%, 95% CI 18.8–25.5%) had surgical uterine evacuation. Multiple factors were significantly associated with this proportion, including misoprostol amount per dose and route of administration, loss to follow-up rate, publication date, geographic region, number of misoprostol doses, duration of dosing, and time between dosing and evaluation. Of 6,359 evaluable women, 384 (meta-analytic estimate 6.8%, 95% CI 5.3–8.5%) had ongoing pregnancies. At most 26 of 12,184 evaluable women (meta-analytic estimate 0.7%, 95% CI 0.4–1.0%) were transfused or hospitalized for abortion-related reasons. In trials that provided satisfaction data, most women were satisfied or very satisfied with the treatment (meta-analytic estimate 78%, 95% CI 71–85%).

CONCLUSIONS:

Misoprostol alone is effective and safe and is a reasonable option for women seeking abortion in the first trimester. Research is indicated to further refine the regimen and to establish efficacy in the late first trimester.

SYSTEMATIC REVIEW REGISTRATION:

PROSPERO, CRD42018083589.
An Ethical Framework for Research in Maternal–Fetal Intervention in the Presence of Maternal Human Immunodeficiency Virus or Hepatitis B and C Infection
Authors: Shamshirsaz Alireza A. , Sellner Allison A. , Erfani Hadi , Aagaard Kjersti M. , Nassr Ahmed A. , Pereira Stacey , Belfort Michael A. , McCullough Laurence B. , Chervenak Frank A.
Published: December 2018

Maternal–fetal interventions continue to be a groundbreaking and rapidly expanding area. In this article, we examine whether it is ethically permissible to conduct investigation into the expansion of inclusion criteria for existing maternal–fetal interventions to include pregnant patients with human immunodeficiency virus (HIV) and hepatitis B or C infection with low or undetectable viral loads. We addressed this ethical question by appealing to ethical principle of respect for the autonomy of the pregnant patient; the patient status of the fetus; the balance of overall benefits and risks of the procedure(s) to pregnant, fetal, and neonatal patients; and to the ethical principle of justice. The ethical framework we have provided supports the conclusion that research on maternal–fetal interventions with pregnant women with HIV and hepatitis B and C infection with low or undetectable viral loads is ethically permissible. To accumulate sufficient numbers, such research should be multicenter.
What Is New in Maternal Heart Disease?
Authors: Metz Torri D.
Published: December 2018

This month we focus on current research in maternal heart disease. Dr. Metz discusses four recent publications, which are concluded with a “bottom-line” that is the take-home message. A complete reference for each can be found on Box 1 on this page along with direct links to abstracts.
Stereotactic Pelvic Navigation With Augmented Reality for Transanal Total Mesorectal Excision
Authors: Kwak Jung-Myun , Romagnolo Luis , Wijsmuller Arthur , Gonzalez Cristians , Agnus Vincent , Lucchesi Fabiano R , Melani Armando , Marescaux Jacques , Dallemagne Bernard
Published: December 2018

INTRODUCTION:

Technical difficulty and unfamiliar surgical anatomy are the main challenges in transanal total mesorectal excision. Precise 3-dimensional real-time image guidance may facilitate the safety, accuracy, and efficiency of transanal total mesorectal excision.

TECHNIQUE:

A preoperative CT was obtained with 10 skin fiducials and further processed to emphasize the border of the anatomical structure by 3-dimensional modeling and pelvic organ segmentation. A forced sacral tilt by placing a 10-degree wedge under the patient’s sacrum was induced to minimize pelvic organ movement caused by lithotomy position. An optical navigation system with cranial software was used. Preoperative CT images were loaded into the navigation system, and patient tracker was mounted onto the iliac bone. Once the patient-to-image paired point registration using skin fiducials was completed, the laparoscopic instrument mounted with instrument tracker was calibrated for instrument tracking. After validating the experimental setup and process of registration by navigating laparoscopic anterior resection, stereotactic navigation for transanal total mesorectal excision was performed in the low rectal neuroendocrine tumor.

RESULTS:

The fiducial registration error was 1.7 mm. The accuracy of target positioning was sufficient at less than 3 mm (1.8 ± 0.9 mm). Qualitative assessment using a Likert scale was well matched between the 2 observers. Of the 20 scores, 19 were judged as 4 (very good) or 5 (excellent). There was no statistical difference between mean Likert scales of the abdominal or transanal landmarks (4.4 ± 0.5 vs 4.3 ± 1.0, p = 0.965).

CONCLUSIONS:

Application of an existing navigation system to transanal total mesorectal excision for a low rectal tumor is feasible. The acceptable accuracy of target positioning justifies its clinical use. Further research is needed to prove the clinical need for the procedure and its impact on clinical outcomes.
Early life exposure to famine and reproductive aging among Chinese women
Authors: Wang Nengying , Huang Yinqiong , Wen Junping , Su Qing , Huang Yanling , Cai Liangchun , Lin Wei , Zong Liyao , Huang Huibin , Qian Xiaofang , Zhu Fengye , Sun Han , Yao Jin , Tang Kaka , Chen Ling , Liang Jixing , Li Liantao , Lin Lixiang , Lu Jieli , Bi Yufang , Wang Weiqing , Zheng Yan , Chen Gang
Published: December 2018

Objective:

To assess the effect of early life exposure to famine, as endured during 1959 to 1961 in China, on reproductive aging in adult women.

Methods:

Between 2011 and 2012, 2,868 women born around the Chinese famine period (1956-1964) were enrolled in this study from three communities in China. Age at natural menopause was obtained retrospectively from a structured questionnaire. The associations of early life famine exposure with reproductive aging during adulthood were estimated, with adjustment of socioeconomic status, lifestyle factors, and body mass index.

Results:

Women exposed to prenatal famine had a higher risk of early menopause (ie, natural menopause <45 years, odds ratio: 1.59, 95% confidence interval [CI]: 1.07, 2.36), and a nonsignificant trend of higher risk of premature ovarian failure (ie, natural menopause <40 y, odds ratio: 1.94, 95% CI: 0.93, 4.00), compared to unexposed women. Exposure to famine during childhood was not significantly associated with reproductive aging. In a secondary analysis focusing on the fetal exposure, prenatal famine exposure was associated with a higher risk of premature ovarian failure (odds ratio: 2.07, 95% CI: 1.08, 3.87), and a nonsignificant trend of higher risk of early menopause (odds ratio: 1.37, 95% CI: 0.98, 1.91), compared to those unexposed to prenatal famine.

Conclusions:

Our study showed that fetal exposure to famine was associated with an increased risk of early menopause. Such findings provided evidence in favor of the thrifty phenotype theory in reproductive aging and helped better understand the etiology of early menopause.
Etiology of Childhood Otorrhea in Luanda, Angola, and a Review of Otitis Media in African Children
Authors: Karppinen Mariia , Bernardino Luis , dos Anjos Elizabete , Pätäri-Sampo Anu , Pitkäranta Anne , Peltola Heikki , Pelkonen Tuula
Published: December 2018

Background:

In resource-poor settings, otorrhea causes a significant burden of disease in children. Etiologic studies and structured data on otorrhea and chronic otitis media among African children remain scarce.

Methods:

Here, we reviewed 678 bacteriologically analyzed otorrhea samples from Luanda Children’s Hospital from children ≤15 years of age between 2008 and 2015. We then compared these with data from other studies among African children through a literature review of 20 articles published over 2 decades.

Results:

Overall, 32 different bacteria were identified among 542 isolates from 654 children in Luanda. Gram-negative bacteria constituted the majority of all isolates (85%), wherebyPseudomonasspp. was the most common (n = 158; 29%), followed byProteusspp. (n = 134; 25%). AmongStaphylococcus aureus(n = 54; 10%), 69% of tested isolates were Methicillin-resistantS. aureus, and amongEnterobacteriaceae, 14% were expanded-spectrum β-lactamase isolates. Resistance to quinolones was rare. Furthermore, in a review of the literature, we found a high occurrence of otorrhea and chronic suppurative otitis media in children as well as possible gaps in existing knowledge.

Conclusions:

In Angola, Gram-negative rods emerged as common causative agents of otorrhea in children followed byS. aureus. The magnitude of chronic otorrhea in Africa represents a cause for public health concern.
Noninvasive approach for de novo acute hypoxemic respiratory failure: noninvasive ventilation, high-flow nasal cannula, both or none?
Authors: García-de-Acilu Marina , Patel Bhakti K. , Roca Oriol
Published: December 2018

Purpose of review

To summarize the recent evidence regarding the use of noninvasive strategies for de novo acute hypoxemic respiratory failure (AHRF).

Recent findings

New guidelines for the use of noninvasive ventilation (NIV) in acute respiratory failure have been published. In parallel, high-flow nasal cannula (HFNC) is an emerging noninvasive strategy for AHRF patients. Although some have cautioned against the use of NIV in AHRF, new encouraging data about the use of a helmet interface for NIV in acute respiratory distress syndrome may overcome the limitations of facemask NIV.

In the last two decades, the use of NIV and HFNC in patients with AHRF has considerably expanded, changing the paradigm of management of AHRF. Choice of each technique should be based according to centre experience and patient tolerability. However, when using noninvasive strategies for AHRF, it is crucial to predefine specific criteria for intubation and monitor patients closely for early detection of clinical deterioration to avoid delayed intubation.
Performance Characteristics of Endometrial Sampling in Diagnosis of Endometrial Carcinoma
Authors: Taraboanta Catalin , Britton Heidi , Plotkin Anna , Azordegan Nazila , Clement Philip B. , Gilks C. Blake
Published: December 2018

Outpatient endometrial biopsy can give false-negative results, with a 0.9% reported posttest probability for endometrial carcinoma (EC) after a negative result. Our objective was to determine if there has been any improvement in the performance characteristics of endometrial biopsy over the last 15 yr. All hysterectomy specimens with a diagnosis of EC or atypical hyperplasia (AH), reported between May 2011 and May 2015, were identified and cross-referenced for any negative endometrial sampling results during the 5 yr before hysterectomy. Negative endometrial samples were defined as either benign findings or insufficient/nondiagnostic, excluding those diagnosed as AH or EC and those for which follow-up sampling was recommended because of atypia. Of 1677 hysterectomy specimens showing AH or EC there were previous negative biopsies in 172: 116 benign and 56 insufficient/nondiagnostic. Over the same period 22,875 negative endometrial biopsy specimens were reported in our region. The posttest probability of having EC or AH in the hysterectomy specimen, given a negative endometrial biopsy result, was 0.74%. In a subset of 90 cases in which a negative biopsy was followed by a diagnosis of AH or EC in a hysterectomy specimen, the slides were independently reviewed. There were no cases where a diagnosis of carcinoma was missed. In 12 samples atypia or possible atypia was identified, and the level of agreement with the original diagnosis was excellent κ=0.83±0.05. In a prospective comparison of examination of 3 levels from each block versus a single slide in 319 cases, the routine preparation of additional slides did not yield clinically significant information. Although there has been evolution in the diagnostic criteria for AH and for recognition of morphologically subtle forms of AH or EC, our results demonstrate a significant lack of sensitivity of outpatient endometrial sampling in the diagnosis of endometrial malignancy/premalignancy. The sensitivity problems are mainly attributable to failure to sample abnormal endometrium. Independent review of slides or examination of additional levels did little to increase the diagnostic yield.