bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of defect distribution on IrOx/ZnO interface doping and Schottky barriers
Authors: Foster Geoffrey M. , Gao Hantian , Mackessy Grace , Hyland Alana M. , Allen Martin W. , Wang Buguo , Look David C. , Brillson Leonard J.
Published: September 2017

We used depth-resolved cathodoluminescence spectroscopy (DRCLS) to measure the nature and spatial distribution of native point defects at Zn- and O-polar ZnO interfaces with iridium oxide (IrOx) and their impact on Schottky barrier formation. IrOx and other metal oxides exhibit higher Schottky barriers than their pure metal counterparts, consistent with wider depletion regions and potentially useful for ohmic contacts to p-type semiconductors. DRCLS with I-V and 1/C2-V barrier height and carrier profile measurements showed high zinc vacancy VZn and CuZn defect densities that compensate free carrier densities, increase depletion widths, and form higher effective barriers than Ir/ZnO contacts. Zn-polar versus O-polar ZnO interfaces with IrOx exhibit 40% higher VZn + CuZn interface segregation and lower carrier densities within a wider depletion region, accounting for the significantly higher (0.89 vs. 0.67 eV) barrier heights. Both the depth of VZn density segregation and the Zn-deficient layer thickness measured microscopically match the depletion width and applied electric fields comparable to spontaneous polarization fields across similar layers displaying analogous defect segregation. These results account for the difference in polarity-dependent segregation due to the electric field-driven diffusion of native defects near ZnO interfaces.
Fluid breakup in carbon nanotubes: An explanation of ultrafast ion transport
Authors: Gao Xiang , Zhao Tianshou , Li Zhigang
Published: September 2017

Ultrafast ion transport in carbon nanotubes (CNTs) has been experimentally observed, but the underlying mechanism is unknown. In this work, we investigate ion transport in CNTs through molecular dynamics (MD) simulations. It is found that the flow in CNTs undergoes a transition from the passage of a continuous liquid chain to the transport of isolated ion-water clusters as the CNT length or the external electric filed strength is increased. The breakup of the liquid chain in CNTs greatly reduces the resistance caused by the hydrogen bonds of water and significantly enhances the ionic mobility, which explains the two-order-magnitude enhancement of ionic conductance in CNTs reported in the literature. A theoretical criterion for fluid breakup is proposed, which agrees well with MD results. The fluid breakup phenomenon provides new insights into enhancing ion transport in nanoconfinements.
Local deep level transient spectroscopy using super-higher-order scanning nonlinear dielectric microscopy and its application to imaging two-dimensional distribution of SiO2/SiC interface traps
Authors: Chinone N. , Cho Y.
Published: September 2017

We propose a new technique called local deep level transient spectroscopy (local-DLTS), which utilizes scanning nonlinear dielectric microscopy to analyze oxide/semiconductor interface traps, and validate the method by investigating thermally oxidized silicon carbide wafers. Measurements of C-t curves demonstrate the capability of distinguishing sample-to-sample differences in the trap density. Furthermore, the DC bias dependence of the time constant and the local-DLTS signal intensity are investigated, and the results agree to characteristic of interface traps. In addition, the Dit values for the examined samples are estimated from the local-DLTS signals and compared with results obtained using the conventional high-low method. The comparison reveals that the Dit values obtained by the two methods are of the same order of magnitude. Finally, two-dimensional (2D) distributions of local-DLTS signals are obtained, which show substantial intensity variations resulting in random 2D patterns. The 2D distribution of the local-DLTS signal depends on the time constant, which may be due to the coexistence of multiple types of traps with different capture cross sections.
Tamper asymmetry and its effect on transmission for x-ray driven opacity simulations
Authors: Morris H. E. , Tregillis I. L. , Hoffman N. M. , Sherrill M. E. , Fontes C. J. , Marshall A. J. , Urbatsch T. J. , Bradley P. A.
Published: September 2017

This paper reports on synthetic transmission results from Lasnex [Zimmerman and Kruer, Comments Plasma Phys. 2, 51 (1975)] radiation-hydrodynamics simulations of opacity experiments carried out at Sandia National Laboratories' recently upgraded ZR facility. The focus is on experiments utilizing disk targets composed of a half-moon Fe/Mg mixture tamped on either end with 10-μm CH and an additional 35-μm beryllium tamper accessory on the end facing the spectrometer. Five x-ray sources with peak power ranging from 10 to 24 TW were used in the simulations to heat and backlight the opacity target. The dominant effect is that the beryllium behind the Fe/Mg mixture is denser and more opaque than the beryllium unshielded by metal during the times of greatest importance for the transmission measurement for all drives. This causes the simulated transmission to be lower than expected, and this is most pronounced for the case using the lowest drive power. While beryllium has a low opacity, its areal density is sufficiently high such that the expected reduction of the measured transmission is significant. This situation leads to an overestimate of iron opacity by 10%–215% for a photon energy range of 975–1775 eV for the 10-TW case. It is shown that if the tamper conditions are known, the transmission through each component of the target can be calculated and the resulting opacity can be corrected.
Effect of magnetoelastic film thickness on power absorption in acoustically driven ferromagnetic resonance
Authors: Labanowski D. , Jung A. , Salahuddin S.
Published: September 2017

Surface acoustic waves (SAWs) traveling on the surface of a piezoelectric substrate are capable of exciting magnetoelastic ferromagnets into resonance. In this work, we explore the effects of magnetoelastic film thickness on the coupling of SAWs into such magnetic thin films. We find that power absorption as a function of film thickness begins to saturate above thicknesses of ≈20 nm. This is contrary to current models that predict an exponential increase of the absorption as a function of increasing film thickness. We show that the saturation happens due to an increase in the damping of the film beyond this thickness range.
Anisotropic magnetorheological elastomers for mechanical to electrical energy conversion
Authors: Lallart Mickaël , Sebald Gaël , Diguet Gildas , Cavaille Jean-Yves , Nakano Masami
Published: September 2017

MagnetoRheological Elastomers (MREs) have been widely used for actuation purposes in numerous applications (e.g., vibration damping), thanks to their magnetic-field controllable shear modulus. Nevertheless, the converse effect, namely, the modification of the magnetic properties through the application of a shear strain or stress has been barely studied. Hence, the purpose of this paper is to investigate such a possibility, both qualitatively and quantitatively, through the modeling of the rotation of particle segments induced both by the mechanical and magnetic solicitations in the case of anisotropic MREs. Such a demonstration, along with experimental validations, therefore allows envisaging new application fields for such materials.
Non-local effects of point mutations on the stability of a protein module
Authors: Chwastyk Mateusz , Vera Andrés M. , Galera-Prat Albert , Gunnoo Melissabye , Thompson Damien , Carrión-Vázquez Mariano , Cieplak Marek
Published: September 2017

We combine experimental and theoretical methods to assess the effect of a set of point mutations on c7A, a highly mechanostable type I cohesin module from scaffoldin CipA from Clostridium thermocellum. We propose a novel robust and computationally expedient theoretical method to determine the effects of point mutations on protein structure and stability. We use all-atom simulations to predict structural shifts with respect to the native protein and then analyze the mutants using a coarse-grained model. We examine transitions in contacts between residues and find that changes in the contact map usually involve a non-local component that can extend up to 50 Å. We have identified mutations that may lead to a substantial increase in mechanical and thermodynamic stabilities by making systematic substitutions into alanine and phenylalanine in c7A. Experimental measurements of the mechanical stability and circular dichroism data agree qualitatively with the predictions provided the thermal stability is calculated using only the contacts within the secondary structures.
Hybrid systems with Ag nanocrystals and Si nanostructures synthesized by ultra-low-energy ion beam synthesis
Authors: Carrada M. , Haj Salem A. , Pecassou B. , Carles R. , Ben Assayag G.
Published: September 2017

Hybrid systems based on silicon and silver nanocrystals (Si-NCs and Ag-NCs) are of considerable interest in photon conversion solar cells. Due to their plasmonic properties, Ag-NCs strongly increase the photoluminescence emission intensity of Si-NCs located in their vicinity, allowing, in principle, to solve the problem of their low emission yield. In this work, we have elaborated 2D networks of Ag-NCs and amorphous Si nanoparticles in a controlled way by using Ultra-Low-Energy Ion-Beam-Synthesis. In the proposed synthesis scheme, a 2D layer of Si-NCs is first obtained by implanting Si+ ions at ultra low energy (from 1 to 3 keV) in a SiO2 layer with subsequent high temperature thermal annealing. Then, Ag+ ions are implanted in the same matrix at energies between 3 and 10 keV and crystalline Ag-NCs are formed during the implantation step. Several configurations with either 2D arrays or a large band of Ag-NCs have been obtained following the Ag+ implantation energy. Enhancement of the PL emission from Si nanostructures, which is related to the presence of Ag-NCs, has been observed under specific arrangement of the two embedded subsystems. In this type of synthesis, a combination of physical phenomena including ion mixing, implantation damage, point defect, and thermal diffusion has been taken into account in order to explain and thus control the structural and the optical characteristics of the system.
Reconfigurable re-entrant cavity for wireless coupling to an electro-optomechanical device
Authors: Menke T. , Burns P. S. , Higginbotham A. P. , Kampel N. S. , Peterson R. W. , Cicak K. , Simmonds R. W. , Regal C. A. , Lehnert K. W.
Published: September 2017

An electro-optomechanical device capable of microwave-to-optics conversion has recently been demonstrated, with the vision of enabling optical networks of superconducting qubits. Here we present an improved converter design that uses a three-dimensional microwave cavity for coupling between the microwave transmission line and an integrated LC resonator on the converter chip. The new design simplifies the optical assembly and decouples it from the microwave part of the setup. Experimental demonstrations show that the modular device assembly allows us to flexibly tune the microwave coupling to the converter chip while maintaining small loss. We also find that electromechanical experiments are not impacted by the additional microwave cavity. Our design is compatible with a high-finesse optical cavity and will improve optical performance.
Signatures of chaos in the Brillouin zone
Authors: Barr Aaron , Barr Ariel , Porter Max D. , Reichl Linda E.
Published: September 2017

When the classical dynamics of a particle in a finite two-dimensional billiard undergoes a transition to chaos, the quantum dynamics of the particle also shows manifestations of chaos in the form of scarring of wave functions and changes in energy level spacing distributions. If we “tile” an infinite plane with such billiards, we find that the Bloch states on the lattice undergo avoided crossings, energy level spacing statistics change from Poisson-like to Wigner-like, and energy sheets of the Brillouin zone begin to “mix” as the classical dynamics of the billiard changes from regular to chaotic behavior.
Generalized second law for a simple chaotic system
Authors: Hasegawa Hiroshi H. , Nakamura Tomomi , Driebe Dean J.
Published: September 2017

The generalized second law (nonequilibrium maximum work formulation) is derived for a simple chaotic system. We consider a probability density, prepared in the far past, which weakly converges to an invariant density due to the mixing property. The generalized second law is then rewritten for an initial invariant density. Gibbs-Shannon entropy is constant in time, but the invariant density has a greater entropy than the prepared density. The maximum work is reduced due to the greater entropy of the invariant density. If and only if the invariant density is a canonical distribution, work is not extractable by any cyclic operation. This gives us the unique equilibrium state. Our argument is extended for a power invariant density such as the Tsallis distribution. On the basis of the Tsallis entropy, the maximum q-work formulation is derived. If and only if the invariant density is a Tsallis distribution, the q-work is no longer extractable by any cyclic operation.
Regularity of beating of small clusters of embryonic chick ventricular heart-cells: experiment vs. stochastic single-channel population model
Authors: Krogh-Madsen Trine , Kold Taylor Louise , Skriver Anne D. , Schaffer Peter , Guevara Michael R.
Published: September 2017

The transmembrane potential is recorded from small isopotential clusters of 2–4 embryonic chick ventricular cells spontaneously generating action potentials. We analyze the cycle-to-cycle fluctuations in the time between successive action potentials (the interbeat interval or IBI). We also convert an existing model of electrical activity in the cluster, which is formulated as a Hodgkin–Huxley-like deterministic system of nonlinear ordinary differential equations describing five individual ionic currents, into a stochastic model consisting of a population of ∼20 000 independently and randomly gating ionic channels, with the randomness being set by a real physical stochastic process (radio static). This stochastic model, implemented using the Clay–DeFelice algorithm, reproduces the fluctuations seen experimentally: e.g., the coefficient of variation (standard deviation/mean) of IBI is 4.3% in the model vs. the 3.9% average value of the 17 clusters studied. The model also replicates all but one of several other quantitative measures of the experimental results, including the power spectrum and correlation integral of the voltage, as well as the histogram, Poincaré plot, serial correlation coefficients, power spectrum, detrended fluctuation analysis, approximate entropy, and sample entropy of IBI. The channel noise from one particular ionic current (IKs), which has channel kinetics that are relatively slow compared to that of the other currents, makes the major contribution to the fluctuations in IBI. Reproduction of the experimental coefficient of variation of IBI by adding a Gaussian white noise-current into the deterministic model necessitates using an unrealistically high noise-current amplitude. Indeed, a major implication of the modelling results is that, given the wide range of time-scales over which the various species of channels open and close, only a cell-specific stochastic model that is formulated taking into consideration the widely different ranges in the frequency content of the channel-noise produced by the opening and closing of several different types of channels will be able to reproduce precisely the various effects due to membrane noise seen in a particular electrophysiological preparation.
Electronic orbital response of regular extended and infinite periodic systems to magnetic fields. I. Theoretical foundations for static case
Authors: Springborg Michael , Molayem Mohammad , Kirtman Bernard
Published: September 2017

A theoretical treatment for the orbital response of an infinite, periodic system to a static, homogeneous, magnetic field is presented. It is assumed that the system of interest has an energy gap separating occupied and unoccupied orbitals and a zero Chern number. In contrast to earlier studies, we do not utilize a perturbation expansion, although we do assume the field is sufficiently weak that the occurrence of Landau levels can be ignored. The theory is developed by analyzing results for large, finite systems and also by comparing with the analogous treatment of an electrostatic field. The resulting many-electron Hamilton operator is forced to be hermitian, but hermiticity is not preserved, in general, for the subsequently derived single-particle operators that determine the electronic orbitals. However, we demonstrate that when focusing on the canonical solutions to the single-particle equations, hermiticity is preserved. The issue of gauge-origin dependence of approximate solutions is addressed. Our approach is compared with several previously proposed treatments, whereby limitations in some of the latter are identified.
Biomechanical and morphological multi-parameter photoacoustic endoscope for identification of early esophageal disease
Authors: Jin Dayang , Yang Fen , Chen Zhongjiang , Yang Sihua , Xing Da
Published: September 2017

The combination of phase-sensitive photoacoustic (PA) imaging of tissue viscoelasticity with the esophagus-adaptive PA endoscope (PAE) technique allows the characterization of the biomechanical and morphological changes in the early stage of esophageal disease with high accuracy. In this system, the tissue biomechanics and morphology are obtained by detecting the PA phase and PA amplitude information, respectively. The PAE has a transverse resolution of approximately 37 μm and an outer diameter of 1.2 mm, which is suitable for detecting rabbit esophagus. Here, an in-situ biomechanical and morphological study of normal and diseased rabbit esophagus (tumors of esophagus and reflux esophagitis) was performed. The in-situ findings were highly consistent with those observed by histology. In summary, we demonstrated the potential application of PAE for early clinical detection of esophageal diseases.
Field-reversed configuration formed by in-vessel θ-pinch in a tandem mirror device
Authors: Lin Munan , Liu Ming , Zhu Guanghui , Shi Peiyun , Zheng Jian , Lu Quanming , Sun Xuan
Published: September 2017

We describe a field reversed configuration (FRC) experiment featuring in-vessel θ-pinch coils and open-field-line plasmas confined in a tandem mirror. Two FRCs, formed near the west and the east mirror throats of a central cell, are ejected toward the mid-plane for colliding and merging. Each FRC consists of four groups of pulsed power supplies and four groups of coils, having diameters 35, 35, 40, and 45 cm. The rise time of the main reversal field is 7.15 μs, and the maximum voltage is 40 kV with total currents of 416 kA, corresponding to a magnetic field of 1690 G. The total capacitive stored energy is 115.2 kJ. A fast pulse gas injection system was designed and tested to inject neutral gas into the FRC formation region with controlled directions. The successful installation of the θ-pinch coils inside the vacuum vessel offers greater freedom for diagnostics and control instruments as well as preserving magnetic tandem mirror configuration. The magnetic field reversal is confirmed by internal magnetic field measurements. The plasma temperature, density, and lifetime are, respectively, ∼100 eV, ∼3.0 × 1018 m−3, and ∼300 μs for the current operating conditions.
On the inter-layer magneto-electric coupling in BiFeO3/SrRuO3 heterostructure
Authors: Sil Anomitra , Wagh Aditya A. , Sharma Deepak , Ranjan Rajeev , Anil Kumar P. S.
Published: September 2017

Interlayer magneto-electric coupling in BiFeO3/SrRuO3 heterostructures was investigated by impedance spectroscopy over a temperature range of 80 K–260 K. In-plane impedance measurements were performed using interdigitated gold electrodes fabricated on the BiFeO3 layer. The Nyquist plots at different temperatures were fitted with an equivalent circuit model of the heterostructure. A pronounced dip in the temperature coefficient of equivalent-capacitance and a distinct increase in the temperature coefficient of equivalent-resistance of the BiFeO3 layer were observed on cooling across ferromagnetic TC of the bottom SrRuO3 layer. Temperature dependent capacitance (at 0 T magnetic fields) and magneto-capacitance (at 5 T magnetic fields) plots showed anomalies near 160 K. A shift of the hysteresis loop along the magnetization axis in field cooled M-H measurements was also found, which indicates the presence of pinned SrRuO3 moments due to the magnetic interaction at the interface. These observations suggest a strong magneto-electric coupling between the BiFeO3 and SrRuO3 layers of this heterostructure.
Enhanced magnetization in morphologically and magnetically distinct BiFeO3 and La0.7Sr0.3MnO3 composites
Authors: Pillai Shreeja , Reshi Hilal Ahmad , Bagwaiya Toshi , Banerjee Alok , Shelke Vilas
Published: September 2017

Nanomaterials exhibit properties different from those of their bulk counterparts. The modified magnetic characteristics of manganite nanoparticles were exploited to improve magnetization in multiferroic BiFeO3 compound. We studied the composite of two morphologically and magnetically distinct compounds BiFeO3 (BFO) and La0.7Sr0.3MnO3 (LSMO). The microcrystalline BiFeO3 sample was prepared by solid state reaction method and the nanocrystalline La0.7Sr0.3MnO3 by sol-gel method. Composites with nominal compositions (1−x)BiFeO3–(x)La0.7Sr0.3MnO3 were prepared by modified solid state reaction method. The phase purity and crystal structures were checked by using X-ray diffraction. The formation of composites with phase separated BFO and LSMO was confirmed using Raman and Fourier Transform Infrared spectroscopy studies. The composite samples showed relatively high value of magnetization with finite coercivity. This improvement in magnetic behavior is ascribed to the coexistence of multiple magnetic orderings in composite samples. We scrutinized the possibility of oxygen vacancy or Fe mixed valency formation in the samples using X-ray photoelectron spectroscopy technique.
Understanding climate-change adaptation on Kakadu National Park, using a combined diagnostic and modelling framework: a case study at Yellow Water wetland
Authors: Dutra Leo X. C. , Bayliss Peter , McGregor Sandra , Christophersen Peter , Scheepers Kelly , Woodward Emma , Ligtermoet Emma , Melo Lizandra F. C.
Published: September 2017

This paper describes a semi-quantitative approach for the assessment of sea-level rise (SLR) impacts on social–ecological systems (SES), using Yellow Water wetland on Kakadu National Park as a case study. The approach includes the application of a diagnostic framework to portray the existing SES configuration, including governance structures, in combination with qualitative modelling and Bayesian belief networks. Although SLR is predicted to cause saltwater inundation of freshwater ecosystems, cultural sites and built infrastructure, our study suggested that it may provide also an opportunity to bring together Indigenous and non-Indigenous knowledge and governance systems, towards a commonly perceived threat. Where feasible, mitigation actions such as levees may be required to manage local SLR impacts to protect important freshwater values. In contrast, adaptation will require strategies that facilitate participation by Kakadu Bininj (the Aboriginal people of Kakadu National Park) in research and monitoring programs that enhance understanding of salinity impacts and the adaptive capacity to respond to reasonably rapid, profound and irreversible future landscape-scale changes.
Negotiating gendered transnationalism and nationalism in post-socialist Latvia
Authors: Lazda Mara
Published: September 2017

This article examines how gender equality activists in postsocialist Latvia negotiate national and transnational frameworks in their campaigns. The case study for this analysis is the 15-year evolution of one gender equality non-governmental organization (NGO), the Resource Center for Women, Marta, in Riga. RCW Malta's work has resulted in significant steps in policy reform and broader social awareness regarding questions of gender equality. In doing so, it bridges essentialist, patriarchal conceptions of the Latvian nation-state and a transnational European feminist narrative. The experience of RCW Marta affirms the continued relevance of the nation, though a redefined one, within transnationalism, which in turn contributes to a rethinking of post-socialism as a spatial and analytic category.
A $C_p$ criterion for semiparametric causal inference
Authors: Baba Takamichi , Kanemori Takayuki , Ninomiya Yoshiyuki
Published: September 2017

For marginal structural models, which play an important role in causal inference, we consider a model selection problem within a semiparametric framework using inverse-probability-weighted estimation or doubly robust estimation. In this framework, the modelling target is a potential outcome that may be missing, so there is no classical information criterion. We define a mean squared error for treating the potential outcome and derive an asymptotic unbiased estimator as a $C_{p}$ criterion using an ignorable treatment assignment condition. Simulation shows that the proposed criterion outperforms a conventional one by providing smaller squared errors and higher frequencies of selecting the true model in all the settings considered. Moreover, in a real-data analysis we found a clear difference between the two criteria.
Ecosystem change and decadal variation in stock–recruitment relationships of Lake Erie yellow perch (Perca flavescens)
Authors: Zhang Fan , Reid Kevin B , Nudds Thomas D
Published: September 2017

Fish stock–recruitment relationships (SRRs) may vary in response to ecosystem change, increasing uncertainty for fisheries management. We defined three periods between 1975 and 2015 over which Lake Erie, a Laurentian Great Lake, underwent significant ecosystem changes: before zebra mussel (Dreissena polymorpha) establishment, after zebra mussel establishment and before re-eutrophication, and after re-eutrophication. To examine the extent to which SRRs of Lake Erie yellow perch (Perca flavescens) also varied over these periods, we compared the performance of Baseline (constant recruitment), Ricker (constant SRR), Periodic Ricker (different SRRs among three periods) and Random-walk Ricker (annually varying SRRs) models fitted to data for yellow perch stocks corresponding to three lake basins. Periodic and Random-walk Ricker models performed better for stocks in the western and eastern basins, but the Baseline model performed best in the central basin. Annual variation in the SRRs coincided with the timing of zebra mussel establishment and re-eutrophication in the shallower western basin, but not in the deeper eastern basin, where quagga mussels (Dreissena bugensis) established later and conditions are less eutrophic. These results underscore that temporally and spatially varying SRRs associated with ecosystem change should be taken into account in models of fish population dynamics.
Deep Temporal Nerve Transfer for Facial Reanimation: Anatomic Dissections and Surgical Case Report
Authors: Mahan Mark A , Sivakumar Walavan , Weingarten David , Brown Justin M
Published: September 2017

BACKGROUND

Facial nerve palsy is a disabling condition that may arise from a variety of injuries or insults and may occur at any point along the nerve or its intracerebral origin.

OBJECTIVE

To examine the use of the deep temporal branches of the motor division of the trigeminal nerve for neural reconstruction of the temporal branches of the facial nerve for restoration of active blink and periorbital facial expression.

METHODS

Formalin-fixed human cadaver hemifaces were dissected to identify landmarks for the deep temporal branches and the tension-free coaptation lengths. This technique was then utilized in 1 patient with a history of facial palsy due to a brainstem cavernoma.

RESULTS

Sixteen hemifaces were dissected. The middle deep temporal nerve could be consistently identified on the deep side of the temporalis, within 9 to 12 mm posterior to the jugal point of the zygoma. From a lateral approach through the temporalis, the middle deep temporal nerve could be directly coapted to facial temporal branches in all specimens. Our patient has recovered active and independent upper facial muscle contraction, providing the first case report of a distinct distal nerve transfer for upper facial function.

CONCLUSION

The middle deep temporal branches can be readily identified and utilized for facial reanimation. This technique provided a successful reanimation of upper facial muscles with independent activation. Utilizing multiple sources for neurotization of the facial muscles, different potions of the face can be selectively reanimated to reduce the risk of synkinesis and improved control.
Heart Rate Variability as a Feeding Intervention Outcome Measure in the Preterm Infant
Authors: Pados Britt F. , Thoyre Suzanne M. , Knafl George J. , Nix William Brant
Published: September 2017

Background:

Feeding interventions for preterm infants aim to reduce the physiologic stress of feeding to promote growth. Heart rate variability (HRV) is a potential noninvasive measure of physiologic stress that may be useful for evaluating efficacy of feeding interventions.

Purpose:

To evaluate whether HRV is a sensitive measure of physiologic stress compared with standard physiologic outcomes in the context of a feeding intervention study.

Methods:

This was a secondary analysis of a within-subjects, cross-over design study comparing usual care feeding with a gentle, coregulated (CoReg) feeding approach in 14 infants born less than 35 weeks' postmenstrual age. HRV indices were calculated from electrocardiogram data and compared with standard physiologic outcomes, including oxygen saturation (Spo2), respiratory rate (RR), apnea, heart rate (HR), and bradycardia. Data were analyzed using linear mixed modeling.

Results:

Infants fed using the CoReg approach had fewer apneic events and higher RR, suggesting they were able to breathe more during feeding. No statistically significant differences were found in Spo
2, HR, bradycardia, or high frequency power (the most commonly reported measure of HRV). Infants fed using the usual care approach had significantly higher SD12, a measure of HRV indicating randomness in the HR, which is a potential indicator of elevated stress.

Implications for Practice:

SD12 was more sensitive to stress than Spo
2, HR, and bradycardia. The utility of HRV as a measure of feeding outcomes in clinical practice needs further exploration.

Implications for Research:

Further exploration of HRV as an intervention outcome measure is needed, particularly evaluating nonlinear indices, such as SD12.
Proximal Screw Configuration Alters Peak Plate Strain Without Changing Construct Stiffness in Comminuted Supracondylar Femur Fractures
Authors: McLachlin Stewart , Kreder Hans , Ng Matthew , Jenkinson Richard , Whyne Cari , Larouche Jeremie
Published: September 2017

Objectives:

Assess the effect of proximal screw configuration on the strain in lateral plating of a simulated comminuted supracondylar femur fracture.

Methods:

Fractures were simulated in 12 synthetic femurs by removing a 200-mm section of bone, located 60 mm from the intercondylar fossa and repaired using a 16-hole locked lateral plate instrumented with 8 uniaxial strain gauges. Three proximal screw type configurations were evaluated: (1) 4 nonlocking screws, (2) 4 locking screws, and (3) a hybrid configuration of 2 nonlocking screws flanked by a locking screw at each end of the proximal fragment. Each screw type was compared for 2 working lengths (∼90 and 160 mm). The longer working length was created by removing the proximal screw closest to the fracture gap. Testing consisted of a vertical load (500 N) applied to the head of femur. Configurations were compared using plate strain, construct stiffness, and fracture gap displacement as outcome measures.

Results:

Plate strain immediately above the fracture gap was reduced with nonlocking screws compared with the other screw types. Plate strains were reduced around the fracture gap with the longer working length but increased for the nonlocking construct at the location of the removed screw. Construct stiffness was not altered by screw type or working length. An increase in fracture gap displacement was only evident in shear translation with the longer working length.

Conclusions:

Plate strain in lateral plating of supracondylar femur fractures is decreased using nonlocking screws proximal to the fracture. Increasing the working length reduces plate strains over the working length yet should be cautioned because of increased interfragmentary shear motion.
Critical Care Resources in Guangdong Province of China: Three Surveys from 2005 to 2015*
Authors: Wu Jian-Feng , Pei Fei , Ouyang Bin , Chen Juan , Li Yi-Min , Feng Yong-Wen , Guo Fa-Liang , Zhou Li-Xin , Wang Zheng , Guo Ying-Jun , Lin Qin-Han , Li Zhan-Peng , Ling Yun , Li Li , Deng Lie-Hua , Zhao Ying-Ping , Dai Jian-Wei , Luo Shu-Yu , Zhou Dun-Rong , Luo Wei-Wen , Zhao Ling , Chen Wei-Ying , Wang Wei-Chuan , Cai Wen-Yang , Luo Qiong-Xiang , Guan Xiang-Dong
Published: September 2017

Objectives:

Data about the critical care resources in China remain scarce. The purpose of this study was to investigate the variation and distribution of critical care resources in Guangdong province from 2005 to 2015.

Design:

Data in regard to critical care resources were collected through questionnaires and visits every 5 years from 2005.

Setting:

All hospitals in Guangdong province were screened and hospitals that provide critical care services were enrolled.

Intervention:

None.

Measurements and Main Results:

One hundred eleven, 158, and 284 hospitals that provide critical care services were enrolled in the three consecutive surveys respectively. The number of ICUs, ICU beds, intensivists, and nurses increased to 324, 3,956, 2,470, and 7,695, respectively, by 2015. Adjusted by population, the number of ICU beds per 100,000 (100,000) population increased by 147.7% from 2005 to 2015, and the number of intensivists and nurses per 100,000 population increased by 35.3% and 55.1% from 2011 to 2015. However, the numbers in the Pearl River Delta, a richer area, were higher than those in the non–Pearl River Delta area (ICU beds: 4.64 vs 2.58; intensivists: 2.90 vs 1.61; nurses: 9.30 vs 4.71 in 2015). In terms of staff training, only 17.85% of intensivists and 14.29% of nurses have completed a formal accredited critical care training program by 2015.

Conclusions:

Our study was the first one to investigate the trend and distribution of critical care resources in China. The quantity of ICU beds and staff has been increasing rapidly, but professional training for staff was inadequate. The distribution of critical care resources was unbalanced. Our study can be beneficial for healthcare policymaking and the allocation of critical care resources in Guangdong province and other provinces in China.
Anaplastic gliomas in adults: an update
Authors: Izquierdo Cristina , Joubert Bastien , Ducray François
Published: September 2017

Purpose of review

The current review summarizes recent advances on the oncogenesis, classification and treatment of adult anaplastic gliomas.

Recent findings

According to the 2016 WHO classification, three main molecular subgroups of adult diffuse anaplastic gliomas can be distinguished based on the 1p/19q codeletion and isocitrate dehydrogenase (IDH) mutation status. In the future, this classification may be further refined based on the telomerase reverse transcriptase promoter and alpha thalassemia/mental retardation syndrome X-linked mutation status, gene expression, DNA methylation and genomic profiling. Both newly diagnosed 1p/19q codeleted and 1p/19q-intact anaplastic gliomas benefit from the addition of chemotherapy to radiotherapy. However, in 1p/19q codeleted anaplastic gliomas, Procarbazine, CCNU and Vincristine chemotherapy seems more effective than temozolomide. At recurrence, 1p/19q-intact anaplastic gliomas do not benefit from the addition of bevacizumab to temozolomide. The use of poly(adenosine 5′-diphosphate-ribose) inhibitors may be another way of specifically targeting IDH-mutant gliomas in addition to specific inhibitors, demethylating agents and anti-IDH vaccines. v-raf murine sarcoma viral oncogene homolog B1 (BRAF)-mutant anaplastic xanthoastrocytomas and gangliogliomas may benefit from BRAF and mitogen-activated protein kinase inhibitors.

Molecular characterization is mandatory for integrated diagnosis and appropriate management of adult anaplastic gliomas. Both 1p/19q codeleted and 1p/19q-intact anaplastic diffuse gliomas benefit from early chemotherapy. At recurrence, preliminary data suggest a potential role for targeted therapies in specific molecular subgroups.
Ethical Issues with Genetic Testing for Tay-Sachs
Authors: Clayton Tricia
Published: September 2017

Several genetic disorders are specific to Jewish heritage; one of the most devastating is Tay-Sachs disease.Tay-Sachs is a fatal hereditary disease, causing progressive neurological problems for which there is no cure. Ethical issues surrounding genetic testing for Tay-Sachs within the Jewish community continue to be complex and multifaceted. A perspective of Tay-Sachs, using rights-based ethics and virtue ethics as a theoretical framework, is explored.
Student Perspective Improves Spiritual Care Curriculum
Authors: Kroning Maureen , Yoon Deborah
Published: September 2017

Spiritual nursing care is a fundamental aspect of care often unobserved during students' clinical experiences. A nursing student shares her disillusionment about the lack of spiritual care she observed during a clinical rotation. Her instructor used the negative experience to identify areas for curriculum improvement to develop and address the lack of spiritual nursing care education.
Adrenal Lesions in Patients With (Attenuated) Familial Adenomatous Polyposis and MUTYH-Associated Polyposis
Authors: Kallenberg Frank G.J. , Bastiaansen Barbara A.J. , Nio C. Yung , Soeters Maarten R. , Boermeester Marja A. , Aalfs Cora M. , Bossuyt Patrick M.M. , Dekker Evelien
Published: September 2017

BACKGROUND:

The reported proportion of patients with familial adenomatous polyposis who have adrenal lesions varies between 7% and 13% compared with 4% in the general population; the prevalence of adrenal lesions in patients with attenuated familial adenomatous polyposis and MUTYH-associated polyposis is unknown. Data on the clinical relevance and clinical course are limited.

OBJECTIVE:

We aimed to report on the frequency, characteristics, and progression of adrenal lesions in polyposis patients.

DESIGN:

This was a historical cohort study.

SETTINGS:

The study was performed at the Academic Medical Center, Amsterdam.

PATIENTS:

All of the patients with familial adenomatous polyposis, attenuated familial adenomatous polyposis, and MUTYH-associated polyposis were included. Medical charts and imaging reports were analyzed for data on adrenal lesions. A radiologist reassessed all of the images. Patients had not routinely been screened for adrenal lesions.

MAIN OUTCOME MEASURES:

The frequency, characteristics, and progression of adrenal lesions in patients with polyposis who underwent abdominal imaging were assessed. Findings were compared with a reference.

RESULTS:

A total of 39 adrenal lesions were identified in 23 (26%) of 90 patients with familial adenomatous polyposis, 2 (18%) of 11 with attenuated familial adenomatous polyposis, and 5 (24%) of 21 with MUTYH-associated polyposis. Mean age at time of detection was 50.7 years (range, 17.1–83.3 y). Median lesion size at baseline was 1.4 cm (range, 1.0–5.0 cm) versus 1.7 cm (range, 1.0–5.7 cm) after a median of 3.5 years (range, 1.0–11.4 y). Two patients were diagnosed with a hyperfunctioning lesion, and 4 underwent adrenalectomy: 3 lesions appeared benign, and 1 was oncocytic of uncertain malignant potential. The OR for detecting at least 1 lesion in a patient with polyposis versus reference was 6.2 (95% CI, 3.2–12.3), with no significant differences in ORs among the 3 syndromes.

LIMITATIONS:

The study was limited by its retrospective design.

CONCLUSIONS:

Adrenal lesions are frequent in patients with polyposis who undergo abdominal imaging. They appear to follow a benign and slowly progressive course and are mostly nonhyperfunctioning. See Abstract Video at http://links.lww.com/DCR/A323.
Uptake of Transanal Total Mesorectal Excision in North America: Initial Assessment of a Structured Training Program and the Experience of Delegate Surgeons
Authors: Atallah Sam B. , DuBose Arielle C. , Burke John P. , Nassif George , deBeche-Adams Teresa , Frering Taylor , Albert Matthew R. , Monson John R.T.
Published: September 2017

BACKGROUND:

Transanal total mesorectal excision is a new approach to curative-intent rectal cancer surgery. Training and surgeon experience with this approach has not been assessed previously in America.

OBJECTIVE:

The purpose of this study was to characterize a structured training program and to determine the experience of delegate surgeons.

DESIGN:

Data were assimilated from an anonymous, online survey delivered to attendees on course completion. Data on surgeon performance during hands-on cadaveric dissection were collected prospectively.

SETTINGS:

This study was conducted at a single tertiary colorectal surgery referral center, and cadaveric hands-on training was conducted at a specialized surgeon education center.

MAIN OUTCOME MEASURES:

The main outcome measurement was the use of the course and surgeon experience posttraining.

RESULTS:

During a 12-month period, eight 2-day transanal total mesorectal excision courses were conducted. Eighty-one colorectal surgeons successfully completed the course. During cadaveric dissection, 71% achieved a complete (Quirke 3) specimen; 26% were near complete (Quirke 2), and 3% were incomplete (Quirke 1). A total of 9.1% demonstrated dissection in the incorrect plane, whereas 4.5% created major injury to the rectum or surrounding structures, excluding the prostate. Thirty eight (46.9%) of 81 surgeon delegates responded to an online survey. Of survey respondents, 94.6% believed training should be required before performing transanal total mesorectal excision. Posttraining, 94.3% of surgeon delegates planned to use transanal total mesorectal excision for distal-third rectal cancers, 74.3% for middle-third cancers, and 8.6% for proximal-third cancers. The most significant complication reported was urethral injury; 5 were reported by the subset of survey respondents who had performed this operation postcourse.

LIMITATIONS:

The study was limited by inherent reporting bias, including observer and recall biases.

CONCLUSIONS:

Although this structured training program for transanal total mesorectal excision was found to be useful by the majority of respondents, the risk of iatrogenic injury after training remains high, suggesting that this training pedagogy alone is insufficient. See Video Abstract at http://links.lww.com/DCR/A335.
Prognostic Significance of Peritoneal Metastasis in Stage IV Colorectal Cancer Patients With R0 Resection: A Multicenter, Retrospective Study
Authors: Arakawa Keiichi , Kawai Kazushige , Ishihara Soichiro , Hata Keisuke , Nozawa Hiroaki , Oba Koji , Sugihara Kenichi , Watanabe Toshiaki
Published: September 2017

BACKGROUND:

Stage IV colorectal cancer encompasses various clinical conditions. The differences in prognosis after surgery between different metastatic organs have not been fully investigated.

OBJECTIVE:

This study aimed to assess prognostic significance in peritoneal metastasis in R0 resected stage IV colorectal cancer.

DESIGN:

We conducted a multicenter retrospective study of patients with R0 resected stage IV colorectal cancer; they were categorized into 3 groups according to the number and location of metastatic organs, including single-organ metastasis in the peritoneum, single-organ metastasis at sites except the peritoneum, and multiple-organ metastases.

SETTINGS:

This study used data accumulated by the Japanese Study Group for Postoperative Follow-Up of Colorectal Cancer.

PATIENTS:

A total of 1133 patients with R0 resected stage IV colorectal cancer were registered retrospectively between 1997 and 2007 in 20 referral hospitals.

MAIN OUTCOME MEASURES:

Cancer-specific survival rates between the groups were measured.

RESULTS:

The median cancer-specific survival of the single-organ metastasis in the peritoneum group was considerably shorter than that of the single-organ metastasis at a site other than the peritoneum group and was almost comparable to that of the multiple-organ metastases group (3.41 years, 6.20 years, and 2.99 years). In a multivariate analysis of cancer-specific survival, peritoneal dissemination was confirmed as an independent prognostic factor of survival. The median postrecurrence survival of single-organ metastasis in the peritoneum group was considerably shorter than that of the single-organ metastasis at a site other than the peritoneum group. Approximately half of the patients who experienced recurrence of single-organ metastasis in the peritoneum experienced peritoneal recurrence.

LIMITATIONS:

This was a retrospective, population-based study that requires a prospective design to validate its conclusions.

CONCLUSIONS:

Peritoneal metastasis of colorectal cancer frequently recurred in the peritoneum even after R0 resection. The cancer-specific survival of the single-organ metastasis in the peritoneum group was as poor as that of the multiple-organ metastases group. See Video Abstract at http://links.lww.com/DCR/A398.