bluuebunny/crossref_metadata_2025 huggingface dataset:
Negative ion photoelectron spectra of ISO3–, IS2O3–, and IS2O4– intermediates formed in interfacial reactions of ozone and iodide/sulfite aqueous microdroplets
Authors: Qin Zhengbo , Hou Gao-Lei , Yang Zheng , Valiev Marat , Wang Xue-Bin
Published: December 2016

Three short-lived, anionic intermediates, ISO3–, IS2O3–, and IS2O4–, are detected during reactions between ozone and aqueous iodine/sulfur oxide microdroplets. These species may play an important role in ozone-driven inorganic aerosol formation; however their chemical properties remain largely unknown. This is the issue addressed in this work using negative ion photoelectron spectroscopy (NIPES) and ab initio modeling. The NIPE spectra reveal that all of the three anionic species are characterized by high adiabatic detachment energies (ADEs) − 4.62 ± 0.10, 4.52 ± 0.10, and 4.60 ± 0.10 eV for ISO3–, IS2O3–, and IS2O4–, respectively. Vibrational progressions with frequencies assigned to the S–O symmetric stretching modes are discernable in the ground state transition features. Density functional theory calculations show the presence of several low-lying isomers involving different bonding scenarios. Further analysis based on high level CCSD(T) calculations reveal that the lowest energy structures are characterized by the formation of I–S and S–S bonds and can be structurally viewed as SO3 linked with I, IS, and ISO for ISO3–, IS2O3–, and IS2O4–, respectively. The calculated ADEs and vertical detachment energies are in excellent agreement with the experimental results, further supporting the identified minimum energy structures. The obtained intrinsic molecular properties of these anionic intermediates and neutral radicals should be useful to help understand their photochemical reactions in the atmosphere.
A computational component analysis of dielectric relaxation and THz spectra of water/AOT reverse micelles with different water loading
Authors: Schmollngruber Michael , Braun Daniel , Steinhauser Othmar
Published: December 2016

In this computational study, we present molecular dynamics simulations of water/aerosol-OT/isooctane reverse micelles with different water loading. We compare these systems in terms of a detailed analysis of dielectric relaxation spectra and water librations in the THz region. The spectra are decomposed into contributions by molecular species and contributions from individual water solvation shells. Additionally, micellar tumbling motion is shown to have a profound influence on the observed dielectric relaxation spectra, if relaxation by internal reorganization and micellar tumbling occurs within similar time scales. A formalism to directly quantify the effect of micellar tumbling motion on a recorded dielectric spectrum is developed. Since micellar rotational diffusion obeys the laws of hydrodynamics, this method is applicable in an experimental context as well, only knowing the viscosity of the outside medium and the average volume of the reverse micelle.
One-species Vlasov-Poisson-Landau system for soft potentials in ℝ3
Authors: He Cong , Lei Yuanjie
Published: December 2016

We consider the global classical solution near a global Maxwellian to the one-species Vlasov-Poisson-Landau system in the whole space Rx3. It is shown that our global solvability result is obtained under the weaker smallness condition on the initial perturbation than that of Duan et al., [preprint arXiv:1112.3261 (2011)] and Lei et al., [Kinet. Relat. Models 7(3), 551–590 (2014)].
Electron and lattice dynamics of transition metal thin films observed by ultrafast electron diffraction and transient optical measurements
Authors: Nakamura A. , Shimojima T. , Nakano M. , Iwasa Y. , Ishizaka K.
Published: December 2016

We report the ultrafast dynamics of electrons and lattice in transition metal thin films (Au, Cu, and Mo) investigated by a combination of ultrafast electron diffraction (UED) and pump-probe optical methods. For a single-crystalline Au thin film, we observe the suppression of the diffraction intensity occuring in 10 ps, which direcly reflects the lattice thermalization via the electron-phonon interaction. By using the two-temperature model, the electron-phonon coupling constant (g) and the electron and lattice temperatures (Te, Tl) are evaluated from UED, with which we simulate the transient optical transmittance. The simulation well agrees with the experimentally obtained transmittance data, except for the slight deviations at the initial photoexcitation and the relaxed quasi-equilibrium state. We also present the results similarly obtained for polycrystalline Au, Cu, and Mo thin films and demonstrate the electron and lattice dynamics occurring in metals with different electron-phonon coupling strengths.
Smart viscoelastic and self-healing characteristics of graphene nano-gels
Authors: Dhar Purbarun , Katiyar Ajay , Maganti Lakshmi Sirisha
Published: December 2016

Readily synthesizable nano-graphene and poly ethylene glycol based stable gels have been synthesized employing an easy refluxing method, and exhaustive rheological and viscoelastic characterizations have been performed to understand the nature of such complex gel systems. The gels exhibit shear thinning response with pronounced yield stress values which is indicative of a microstructure, where the graphene nanoflakes intercalate (possible due to the refluxing) with the polymer chains and form a pseudo spring damper network. Experimentations on the thixotropic behavior of the gels indicate that the presence of the G nanoflakes leads to immensely augmented structural stability capable of withstanding severe impact shears. Further information about the localized interactions of the G nanoflakes with the polymer chains is revealed from the amplitude and frequency sweep analyses in both linear and non-linear viscoelastic regimes. Massively enhanced cross over amplitude values are recorded and several smart effects such as enhanced elastic behavior at increasing forcing frequencies are registered. Structural resonance induced disruption of the elastic behavior is observed for the gels for a given range of frequency and the proposition of resonance has been justified mathematically. It is observed that, post this resonance bandwidth, the gels are able to self-heal and regain their original elastic behavior back without any external intervention. More detailed information on the viscoelastic nature of the gels has been obtained from creep and recovery compliance tests and justifications for the spring damper microstructure has been obtained. Smart features such as enhanced stress relaxation behavior with increasing strain have been observed and the same explained, based on the proposed microstructure. The viscoelastic response of the gels has been mathematically modeled and it has been revealed that such complex gels can be accommodated as modified Burger's viscoelastic systems with predominant elastic/plastic behavior. The present gels show promise in microscale actuators, vibration isolation, and damping in devices and prosthetics, as active fluids in automotive suspensions, controlled motion arrestors, and so on.
Tunnel electroresistance in BiFeO3 junctions: size does matter
Authors: Boyn S. , Douglas A. M. , Blouzon C. , Turner P. , Barthélémy A. , Bibes M. , Fusil S. , Gregg J. M. , Garcia V.
Published: December 2016

In ferroelectric tunnel junctions, the tunnel resistance depends on the polarization orientation of the ferroelectric tunnel barrier, giving rise to tunnel electroresistance. These devices are promising to be used as memristors in neuromorphic architectures and as non-volatile memory elements. For both applications, device scalability is essential, which requires a clear understanding of the relationship between polarization reversal and resistance change as the junction size shrinks. Here we show a robust tunnel electroresistance in BiFeO3-based junctions with diameters ranging from 1200 to 180 nm. We demonstrate that the tunnel electroresistance and the corresponding fraction of reversed ferroelectric domains change drastically with the junction diameter: while the micron-size junctions display a reversal in less than 10% of the area, the smallest junctions show an almost complete polarization reversal. Modeling the electric-field distribution, we highlight the critical role of the bottom electrode resistance which significantly diminishes the actual electric field applied to the ferroelectric barrier in the mixed polarization state. A polarization-dependent critical electric field below which further reversal is prohibited is found to explain the large differences between the ferroelectric switchability of nano- and micron-size junctions. Our results indicate that ferroelectric junctions are downscalable and suggest that specific junction shapes facilitate complete polarization reversal.
Photonic crystal fiber modal interferometer with Pd/WO3 coating for real-time monitoring of dissolved hydrogen concentration in transformer oil
Authors: Zhang Ya-nan , Wu Qilu , Peng Huijie , Zhao Yong
Published: December 2016

A highly-sensitive and temperature-robust photonic crystal fiber (PCF) modal interferometer coated with Pd/WO3 film was fabricated and studied, aiming for real-time monitoring of dissolved hydrogen concentration in transformer oil. The sensor probe was fabricated by splicing two segments of a single mode fiber (SMF) with both ends of the PCF. Since the collapse of air holes in the PCF in the interfaces between SMF and PCF, a SMF-PCF-SMF interferometer structure was formed. The Pd/WO3 film was fabricated by sol-gel method and coated on the surface of the PCF by dip-coating method. When the Pd/WO3 film is exposed to hydrogen, both the length and cladding refractive index of the PCF would be changed, resulting in the resonant wavelength shift of the interferometer. Experimental results showed that the hydrogen measurement sensitivity of the proposed sensor can reach 0.109 pm/(μl/l) in the transformer oil, with the measurement range of 0–10 000 μl/l and response time less than 33 min. Besides, the proposed sensor was temperature-insensitive without any compensation process, easy to fabricate without any tapering, polishing, or etching process, low cost and quickly response without any oil-gas separation device. All these performances satisfy the actual need of real-time monitoring of dissolved hydrogen concentration in the transformer oil.
Laser-induced fluorescence analysis of plasmas for epitaxial growth of YBiO3 films with pulsed laser deposition
Authors: Orsel Kasper , Groenen Rik , Bastiaens Bert , Koster Gertjan , Rijnders Guus , Boller Klaus-J.
Published: December 2016

We record the two-dimensional laser-induced fluorescence (LIF) on multiple plasma constituents in a YBiO3 plasma. This allows us to directly link the influence of oxygen present in the background gas during pulsed laser deposition to the oxidation of plasma species as well as the formation of epitaxial YBiO3 films. With spatiotemporal LIF mapping of the plasma species (Y, YO, Bi, and BiO) in different background gas compositions, we find that little direct chemical interaction takes place between the plasma plume constituents and the background gas. However, a strong influence of the background gas composition can be seen on the YBO film growth, as well as a strong correlation between the oxygen fraction in the background gas and the amount of YO in the plasma plume. We assign this correlation to a direct interaction between the background gas and the target in between ablation pulses. In an O2 background, an oxygen-rich surface layer forms in between ablation pulses, which provides additional oxygen for the plasma plume during target ablation. This differs from our previous observations in STO and LAO plasmas, where species oxidation primarily takes place during propagation of the plasma plume towards the substrate.
Incorporation of gold into silicon by thin film deposition and pulsed laser melting
Authors: Warrender Jeffrey M. , Hudspeth Quentin , Malladi Girish , Efstathiadis Harry , Mathews Jay
Published: December 2016

We report on the incorporation of gold into silicon at a peak concentration of 1.9 × 1020 at./cm3, four orders of magnitude above the equilibrium solubility limit, using pulsed laser melting of a thin film deposited on the silicon surface. We vary the film thickness and laser process parameters (fluence, number of shots) to quantify the range of concentrations that can be achieved. Our approach achieves gold concentrations comparable to those achieved with ion implantation followed by pulsed laser melting, in a layer with high crystalline quality. This approach offers an attractive alternative to ion implantation for forming high quality, high concentration layers of transition metals like gold in silicon.
Tailoring capping layers to reduce stress gradients in copper metallization
Authors: Murray Conal E. , Priyadarshini Deepika , Nguyen Son , Ryan E. Todd
Published: December 2016

Capping layers for back-end-of-line metallization, which primarily serve as diffusion barriers to prevent contamination, also play a role in mitigating electromigration in the underlying conductive material. Stress gradients can be generated in copper metallization due to the conditions associated with the capping process. To study the effects of deposition and subsequent annealing on the mechanical response of copper films with various capping schemes, we employed a combination of conventional and glancing incidence X-ray diffraction techniques to quantify the stress gradient maxima. The Cu films with dielectric caps, such as silicon nitride, can exhibit large gradients that decrease slightly with thermal cycling. However, Co and TaN-based metallic capping layers create significantly lower stress gradient maxima in copper features both before and after annealing. The different evolution of stress gradients in Cu films with dielectric and metallic caps due to thermal cycling reveals the interaction of dislocation-mediated, plastic deformation with the cap/Cu interface.
Strong out-of-plane magnetic anisotropy in ion irradiated anatase TiO2 thin films
Authors: Stiller M. , Barzola-Quiquia J. , Esquinazi P. , Spemann D. , Meijer J. , Lorenz M. , Grundmann M.
Published: December 2016

The temperature and field dependence of the magnetization of epitaxial, undoped anatase TiO2 thin films on SrTiO3 substrates was investigated. Low-energy ion irradiation was used to modify the surface of the films within a few nanometers, yet with high enough energy to produce oxygen and titanium vacancies. The as-prepared thin film shows ferromagnetism which increases after irradiation with low-energy ions. An optimal and clear magnetic anisotropy was observed after the first irradiation, opposite to the expected form anisotropy. Taking into account the experimental parameters, titanium vacancies as di-Frenkel pairs appear to be responsible for the enhanced ferromagnetism and the strong anisotropy observed in our films. The magnetic impurities concentrations was measured by particle-induced X-ray emission with ppm resolution. They are ruled out as a source of the observed ferromagnetism before and after irradiation.
Effects of preheat and mix on the fuel adiabat of an imploding capsule
Authors: Cheng B. , Kwan T. J. T. , Wang Y. M. , Yi S. A. , Batha S. H. , Wysocki F. J.
Published: December 2016

We demonstrate the effect of preheat, hydrodynamic mix and vorticity on the adiabat of the deuterium-tritium (DT) fuel in fusion capsule experiments. We show that the adiabat of the DT fuel increases resulting from hydrodynamic mixing due to the phenomenon of entropy of mixture. An upper limit of mix, Mclean/MDT ≥ 0.98, is found necessary to keep the DT fuel on a low adiabat. We demonstrate in this study that the use of a high adiabat for the DT fuel in theoretical analysis and with the aid of 1D code simulations could explain some aspects of 3D effects and mix in capsule implosion. Furthermore, we can infer from our physics model and the observed neutron images the adiabat of the DT fuel in the capsule and the amount of mix produced on the hot spot.
Multilevel resistance in ZnO nanowire memristors enabled by hydrogen annealing treatment
Authors: Lee Sunghun , Park Jung-Bong , Lee Myoung-Jae , Boland John J.
Published: December 2016

In non-volatile memory technology, various attempts to overcome both technology and physical limits have led to development of neuromorphic devices like memristors. Moreover, multilevel resistance and the potential for enhanced memory capability has attracted much attention. Here, we report memristive characteristics and multilevel resistance in a hydrogen annealed ZnO nanowire device. We find that the memristive behavior including negative differential resistance arises from trapped electrons in an amorphous ZnO interfacial layer at the injection electrode that is formed following hydrogen annealing. Furthermore, we demonstrate that it is possible to control electrons trapping and detrapping by the controlled application of voltage pulses to establish a multilevel memory. These results could pave the way for multifunctional memory device technology such as the artificial neuromorphic system.
Reconfigurable heat-induced spin wave lenses
Authors: Dzyapko O. , Borisenko I. V. , Demidov V. E. , Pernice W. , Demokritov S. O.
Published: December 2016

We study the control and manipulation of propagating spin waves in yttrium iron garnet films using a local laser-induced heating. We show that, due to the refraction of spin waves in the thermal gradients, the heated region acts as a defocusing lens for Damon-Eshbach spin waves and as a focusing lens for backward volume waves enabling collimation of spin-wave beams in the latter case. In addition to the focusing/defocusing functionality, the local heating allows one to manipulate the propagation direction of the spin-wave beams and to efficiently suppress their diffraction spreading by utilizing caustic effects.
Temperature invariant energy value in LED spectra
Authors: Baumgartner Hans , Vaskuri Anna , Kärhä Petri , Ikonen Erkki
Published: December 2016

Relative emission spectra of light-emitting diodes (LEDs) depend on the junction temperature. The high-energy region of the emission spectrum can be modelled with Maxwell-Boltzmann distribution as a function of energy and junction temperature. We show that according to the model and our experiments, the normalized emission spectra at different junction temperatures intersect at a unique energy value. The invariant intersection energy exists for many types of LEDs and can be used to determine the alloy composition of the material. Furthermore, the wavelength determined by the intersection energy can be used as a temperature invariant wavelength reference in spectral measurements.
Accessing Rashba states in electrostatically gated topological insulator devices
Authors: Banerjee Abhishek , Sundaresh Ananthesh , Majhi Kunjalata , Ganesan R. , Anil Kumar P. S.
Published: December 2016

We study the low temperature electrical transport in gated BiSbTe1.25Se1.75/hexagonal-Boron Nitride van der Waals heterostructure devices. Our experiments indicate the presence of Rashba spin-split states confined to the sample surface. While such states have been observed previously in photo-emission spectroscopy and STM experiments, it has not been possible to unambiguously detect them by electrical means and their transport properties remain mostly unknown. We show that these states support high mobility conduction with Hall effect mobilities ∼2000 to 3000 cm2/V-s that are paradoxically much larger than the mobilities of the topological surface states ∼300 cm2/V-s at T = 2 K. The spin-split nature of these states is confirmed by magneto-resistance measurements that reveal multi-channel weak anti-localization. Our work shows that Rashba spin split states can be electrically accessed in Topological insulators paving the way for future spintronic applications.
Terahertz detectors from Be-doped low-temperature grown InGaAs/InAlAs: Interplay of annealing and terahertz performance
Authors: Globisch B. , Dietz R. J. B. , Nellen S. , Göbel T. , Schell M.
Published: December 2016

The influence of post-growth annealing on the electrical properties, the transient carrier dynamics and the performance as THz photoconductive receiver of Beryllium (Be) doped InGaAs/InAlAs multilayer heterostructures grown at 130 °C in a molecular beam epitaxy (MBE) system was investigated. We studied samples with nominally Be doping concentrations of 8 ×10 17 cm-3 – 1.2 ×1019 cm3 annealed for 15 min. – 120 min. at temperatures between 500 °C – 600 °C. In contrast to previous publications, the results show consistently that annealing increases the electron lifetime of the material. In analogy to the annealing properties of low-temperature grown (LTG) GaAs we explain our findings by the precipitation of arsenic antisite defects. The knowledge of the influence of annealing on the material properties allowed for the fabrication of broadband THz photoconductive receivers with an electron lifetime below 300 fs and varying electrical properties. We found that the noise of the detected THz pulse trace in time-domain spectroscopy (TDS) was directly determined by the resistance of the photoconductive receiver and the peak-to-peak amplitude of the THz pulse correlated with the electron mobility.
Thermoelectric transport through a T-shaped DQD connected to ferromagnetic and superconducting electrodes
Authors: Xu Li , Li Zhi-Jian , Wang Qiang , Nie Yi-Hang
Published: December 2016

We theoretically analyze the properties of thermoelectric transport through a T-shaped DQD connected to ferromagnetic and superconducting electrodes by means of nonequilibrium Green function formalism. The influences of the superconducting gap, interdot tunneling coupling and asymmetry parameter on the thermoelectric properties are discussed. The large thermoelectric efficiency can be obtained by choosing small polarization of ferromagnetic electrode, small asymmetry parameter (<1), appropriately large gap and appropriately interdot coupling, which can be used as the optimal schemes for obtaining high thermoelectric efficiency in the device.
Birth of a W sex chromosome by horizontal transfer ofWolbachiabacterial symbiont genome
Authors: Leclercq Sébastien , Thézé Julien , Chebbi Mohamed Amine , Giraud Isabelle , Moumen Bouziane , Ernenwein Lise , Grève Pierre , Gilbert Clément , Cordaux Richard
Published: December 2016

Significance

Sex determination is an evolutionarily ancient, key developmental pathway governing sexual differentiation in animals. Sex determination systems are remarkably variable between species or groups of species, however, and the evolutionary forces underlying transitions between these systems are poorly understood. Here we provide evidence indicating that the genome ofWolbachiabacterial endosymbionts was horizontally transferred into a chromosome of the common pillbugArmadillidium vulgare, which resulted in this chromosome evolving as a new female (W) sex chromosome. This represents a remarkable mechanism underpinning the birth of sex chromosomes. We conclude that bacteria can be powerful agents of evolutionary transitions in sex determination systems in animals.
Pegylated IFN-α suppresses hepatitis C virus by promoting the DAPK-mTOR pathway
Authors: Liu Wei-Liang , Yang Hung-Chih , Hsu Ching-Sheng , Wang Chih-Chiang , Wang Tzu-San , Kao Jia-Horng , Chen Ding-Shinn
Published: December 2016

Significance

Death-associated protein kinase (DAPK) regulates several important biological functions through a diverse range of signal transduction pathways, including cell growth, the immune response, apoptosis, and autophagy, but its antiviral activity has not been explored. Our data provide evidence that DAPK is one of the major regulators for the pegylated IFN-α–induced antiviral activity against hepatitis C virus, suggesting that DAPK may serve as a novel antiviral target and also a new biomarker to predict the therapeutic efficacy of pegylated IFN-α and other antiviral agents.
On literary fiction and its effects on theory of mind
Authors: Kidd David , Ongis Martino , Castano Emanuele
Published: December 2016

Storytelling is a hallmark human activity. We use stories to make sense of the world, to explain it to our children, to create communities, and to learn about others. This article focuses on fictional stories and their impact on complex sociocognitive abilities. Correlational and experimental evidence shows that exposure to fiction recruits and hones our ability to represent others’ mental states, or theory of mind (ToM). Experimental studies suggest this effect is specific to literary fiction. Using a unique set of texts, we replicate the finding that literary fiction improves ToM performance. Consistent with the expectation of greater focus on characters in literary fiction, linguistic analysis of the texts revealed that the literary texts contain more markers of reflective function, a sophisticated manifestation of ToM. Further analysis showed the prevalence of markers of reflective function partially mediated the effect of literary fiction on ToM performance.
National Parks in Iran and the Evolution of People-Park Relationships
Authors: Seyed-Emami Kavous , Ashayeri Sheyda
Published: December 2016

In Iran, national parks were originally created to protect wildlife and natural expanses. Over time, the exigencies of handling conflict with the locals and a worldwide shift in management approaches from strict protection to newer participatory approaches led Iranian conservationists to adopt the discourse of participatory conservation. However, serious institutional and attitudinal obstacles have prevented policy makers and officials from developing good relations with local communities, making it difficult to serve the interests of conservation or accommodate tourists. Based on interviews with past and present officials of the Department of the Environment of Iran and other field observers, this paper discusses approaches to conservation that reconcile the requirements of conservation with the needs of the people who benefit from reserves.
The Conservation of Biodiversity in Iran: Threats, Challenges and Hopes
Authors: Jowkar Houman , Ostrowski Stéphane , Tahbaz Morad , Zahler Peter
Published: December 2016

Because of its diverse geological formations, climates, and soils, Iran is home to outstanding biodiversity. National conservation started in Iran over fifty years ago and today nearly 10 percent of the country is protected. However, biodiversity in Iran is threatened, with about 100 species of vertebrate fauna vulnerable or endangered. Increased population and human activity, climate change, drought, desertification, agriculture, poaching, and economic sanctions have helped create this crisis. Many of these causes can be mitigated through better planning, sustainable policies, and increased civil society and local engagement. Promoting awareness about the impacts of human practices will also be important for the long-term sustainability of Iran’s ecosystems. Iranian conservation NGOs have already taken an active role in preserving biodiversity.
Environmental Challenges in Today’s Iran
Authors: Tahbaz Morad
Published: December 2016

Drought, increased population, war, air pollution, climate change, industrial and agricultural production, sanctions, inefficient water and natural resource use, and lack of enforcement of existing environmental regulations have contributed to Iran’s current environmental crisis. Insufficient water resources are forcing people to migrate, putting pressure on others. Aquifers are being drained. Air pollution has made living conditions in Iran’s cities increasingly challenging. Wind erosion is furthering the desertification of agricultural land, creating greater production demand on remaining arable areas. Biodiversity is under threat. On the other hand, Iran’s environmental future can be positively influenced by the collaboration of the public, private and non-profit sectors. Awareness and education, along with greater financial and human resources, will be necessary to tackle the problem.
There's Something about Molly: The Underresearched Yet Popular Powder form of Ecstasy in the United States
Authors: Palamar Joseph J.
Published: December 2016

Molly has been the street name for powder or crystalline ecstasy (3,4-methylenedioxymethamphetamine [MDMA]) in the United States since the early 2000s; however, few studies have examined Molly use or included Molly in the definition of ecstasy/MDMA. Prevalence of self-reported ecstasy use is being underreported on surveys due to the lack of inclusion of “Molly,” although Molly is often so adulterated with novel psychoactive substances such as synthetic cathinones (“bath salts”) that the name “Molly” may no longer adequately represent ecstasy/MDMA. The author recommends that Molly use and Molly purity be further studied to more adequately inform prevention and harm reduction.
The influence of race length on arterial compliance following an ultra‐endurance marathon
Authors: Bonsignore Alis , Bredin Shannon S. D. , Wollmann Holly , Morrison Barb , Jeklin Andrew , Buschmann Lauren , Robertson Josh , Buckler Elizabeth Jean , McGuinty Duncan , Rice Mark S. , Warburton Darren E. R.
Published: December 2016

There is inconclusive evidence concerning the effects of routine participation in ultra‐endurance events on cardiovascular disease (CVD) risk. Arterial compliance is a reliable, non‐invasive, and effective tool for evaluating CVD risk. The purpose of this research was to examine if race length influences acute changes in arterial compliance following an ultra‐marathon event. A total of 46 ultra‐marathon runners were recruited including 21 participants (39.8 ± 8.3 years, 6 females) in the 80‐km event and 25 participants (43.7 ± 9.8 years, 3 female) in the 195‐km event. Arterial compliance was measured via radial applanation tonometry (CR‐2000, HDI) for diastolic pulse contour analysis before and following the race. Significant between‐group differences were found for changes in large arterial compliance with a decrease (increase in stiffness) following the 195‐km event and an increase following the 80‐kilometre event (p < .05). Longer race lengths are associated with greater reductions in large arterial compliance following recreational ultra‐marathon running. Assessment of arterial compliance might be a useful prognostic tool to assess the long‐term risk of CVD among ultra‐marathon runners.
CD4+ T cell effector commitment coupled to self-renewal by asymmetric cell divisions
Authors: Nish Simone A. , Zens Kyra D. , Kratchmarov Radomir , Lin Wen-Hsuan W. , Adams William C. , Chen Yen-Hua , Yen Bonnie , Rothman Nyanza J. , Bhandoola Avinash , Xue Hai-Hui , Farber Donna L. , Reiner Steven L.
Published: December 2016

Upon infection, an activated CD4+ T cell produces terminally differentiated effector cells and renews itself for continued defense. In this study, we show that differentiation and self-renewal arise as opposing outcomes of sibling CD4+ T cells. After influenza challenge, antigen-specific cells underwent several divisions in draining lymph nodes (LN; DLNs) while maintaining expression of TCF1. After four or five divisions, some cells silenced, whereas some cells maintained TCF1 expression. TCF1-silenced cells were T helper 1–like effectors and concentrated in the lungs. Cells from earliest divisions were memory-like and concentrated in nondraining LN. TCF1-expressing cells from later divisions in the DLN could self-renew, clonally yielding a TCF1-silenced daughter cell as well as a sibling cell maintaining TCF1 expression. Some TCF1-expressing cells in DLNs acquired an alternative, follicular helper-like fate. Modeled differentiation experiments in vitro suggested that unequal PI3K/mechanistic target of rapamycin signaling drives intraclonal cell fate heterogeneity. Asymmetric division enables self-renewal to be coupled to production of differentiated CD4+ effector T cells during clonal selection.
Criteria for the existence of principal eigenvalues of time periodic cooperative linear systems with nonlocal dispersal
Authors: Bao Xiongxiong , Shen Wenxian
Published: December 2016

The current paper establishes criteria for the existence of principal eigenvalues of time periodic cooperative linear nonlocal dispersal systems with Dirichlet type, Neumann type or periodic type boundary conditions. It is shown that such a nonlocal dispersal system has a principal eigenvalue in the following cases: the nonlocal dispersal distance is sufficiently small; the spatial inhomogeneity satisfies a so-called vanishing condition; or the spatial inhomogeneity is nearly globally homogeneous. Moreover, it is shown that the principal eigenvalue of a time periodic cooperative linear nonlocal dispersal system (if it exists) is algebraically simple. A linear nonlocal dispersal system may not have a principal eigenvalue. The results established in the current paper extend those in literature for time independent or periodic nonlocal dispersal equations to time periodic cooperative nonlocal dispersal systems and will serve as a basic tool for the study of cooperative nonlinear systems with nonlocal dispersal.
Compact Lie groups: Euler constructions and generalized Dyson conjecture
Authors: Cacciatori S. , Dalla Piazza F. , Scotti A.
Published: December 2016

A generalized Euler parameterization of a compact Lie group is a way for parameterizing the group starting from a maximal Lie subgroup, which allows a simple characterization of the range of parameters. In the present paper we consider the class of all compact connected Lie groups. We present a general method for realizing their generalized Euler parameterization starting from any symmetrically embedded Lie group. Our construction is based on a detailed analysis of the geometry of these groups. As a byproduct this gives rise to an interesting connection with certain Dyson integrals. In particular, we obtain a geometry based proof of a Macdonald conjecture regarding the Dyson integrals correspondent to the root systems associated to all irreducible symmetric spaces. As an application of our general method we explicitly parameterize all groups of the class of simple, simply connected compact Lie groups. We provide a table giving all necessary ingredients for all such Euler parameterizations.
The MD–MEd Joint-Degree Program at Vanderbilt University: Training Future Expert Medical Educators
Authors: Sullivan William M. , DeVolder Jacob , Bhutiani Monica , Neal Kristen W. , Miller Bonnie M.
Published: December 2016

Problem

Some medical students are drawn to medical education as an area of academic specialization. However, few options exist for medical students who wish to build a scholarly foundation for future careers in medical education.

Approach

In 2011, Vanderbilt University School of Medicine (VUSM) and Peabody College of Education and Human Development at Vanderbilt University partnered to establish a novel dual-degree program that, through transfer of credit, allows students to graduate with both an MD and a master of education (MEd) degree in five years. The MD–MEd joint-degree program equips students with robust knowledge and skills related to general education while providing opportunities through independent studies and capstone projects to contextualize these ideas in medical education.

Outcomes

This innovation at Vanderbilt University demonstrates the feasibility of an MD–MEd joint-degree program. MD–MEd graduates’ demonstrated commitment to medical education and credentials will allow them to take on greater educational responsibilities earlier in their careers and quickly gain experience. The three author participants feel their experiences allowed them to achieve desired competencies as educators. They have each gained early experience by chairing the Student Curriculum Committee and contributing to major curricular reform at VUSM.

Next Steps

The authors plan to integrate specific medical education competencies into the program, which will require MD–MEd students to develop and demonstrate proficiency in the knowledge and skills expected of dedicated medical educators. Graduates’ career trajectories will be tracked to explore whether they become medical educators, conduct educational research, and assume leadership positions.
Dystonia in Methylphenidate Withdrawal: A Case Report
Authors: Grau-López Lara , Daigre Constanza , Mercado Nestor , Casas Miquel , Roncero Carlos
Published: December 2016

Few studies have described movement disorders as withdrawal symptoms during psychostimulant detoxification. Although dystonia has been reported as an uncommon adverse effect of methylphenidate treatment, it has not been described in the context of methylphenidate withdrawal. We report a case of dystonia as the main withdrawal symptom in a methylphenidate-dependent adult participating in an inpatient methylphenidate detoxification program. Although movement disorders such as dystonia are very rare adverse effects of methylphenidate withdrawal, practitioners need to be alert to this risk in order to initiate appropriate treatment.
Evaluation of the Financial and Health Burden of Infants at Risk for Respiratory Syncytial Virus
Authors: Blake Stephanie McCallum , Tanaka David , Bendz Lisa M. , Staebler Suzanne , Brandon Debra
Published: December 2016

Background:

Respiratory syncytial virus (RSV) is the leading viral cause of death in infants younger than 1 year. In July 2014, the American Academy of Pediatrics (AAP) Committee on Infectious Diseases concluded that the “limited clinical benefit” for infants born at more than 29 weeks' gestation, together with the associated high cost of the immunoprophylaxis, no longer supported the routine use of palivizumab (Synagis).

Purpose:

To evaluate the impact of the newly adopted AAP palivizumab prophylaxis administration on health and subsequent hospital costs of infants born between 29 and less than 32 weeks' gestation.

Methods:

A retrospective cohort analysis from a single institution across the duration of the study comparing the clinical and financial outcomes of infants (aged < 32 weeks) treated under the 2009 AAP guidelines (PRE) and infants (aged >29 weeks) managed after the 2014 AAP guidelines (POST) took effect.

Results:

RSV-positive admissions were greater in the POST cohort versus the PRE cohort (P = .04). There were no readmission deaths due to RSV infection in either cohort. The number needed to treat to avoid a single RSV-positive hospitalization was 20 infants at an estimated palivizumab cost of $90,000 to avoid an estimated hospital cost of $29,000.

Implications for Practice:

Assessment of individual risk factors and their ability to predict severe RSV risk/disease, thus, would allow providers greater flexibility in determining need for prophylaxis therapy.

Implications for Research:

Longitudinal evaluation of financial and clinical outcomes is needed to determine the impact of the 2014 AAP revised regulatory guidelines.
Preeclampsia and Long-term Risk of Maternal Retinal Disorders
Authors: Auger Nathalie , Fraser William D. , Paradis Gilles , Healy-Profitós Jessica , Hsieh Ada , Rhéaume Marc-André
Published: December 2016

OBJECTIVE:

To evaluate whether preeclampsia is associated with risk of maternal retinal disease in the decades after pregnancy.

METHODS:

We carried out a longitudinal cohort study of 1,108,541 women who delivered neonates in any hospital in Quebec, Canada, between 1989 and 2013. We tracked women for later hospitalizations until March 31, 2014. Preeclampsia was measured at delivery categorized by severity (mild or severe) and onset (before or at 34 weeks or more of gestation). Main outcomes were hospitalizations and inpatient procedures for retinal detachment, retinopathy, or other retinal disorders. We used Cox regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) comparing preeclampsia with no preeclampsia adjusting for diabetes and hypertension.

RESULTS:

Compared with no preeclampsia, women with preeclampsia had a higher incidence of hospitalization for retinal detachment (52.9 compared with 23.9/10,000), retinopathy (60.5 compared with 8.0/10,000), and other retinal disorders (13.3 compared with 7.3/10,000). Preeclampsia was most strongly associated with traction detachments (HR 2.39, 95% CI 1.52–3.74), retinal breaks (HR 2.48, 95% CI 1.40–4.41), and diabetic retinopathy (HR 4.13, 95% CI 3.39–5.04). Severe and early-onset preeclampsia was associated with even higher risk compared with mild or late-onset preeclampsia.

CONCLUSION:

Preeclampsia, particularly severe or early-onset preeclampsia, is associated with an increased risk of maternal retinal disease in the decades after pregnancy.
Intraoperative Archive of Right Colonic Vascular Variability Aids Central Vascular Ligation and Redefines Gastrocolic Trunk of Henle Variants
Authors: Alsabilah Jamal F. , Razvi Syed A. , Albandar Mahdi H. , Kim Nam K.
Published: December 2016

BACKGROUND:

Vascular supply to the right colon has become an issue because of high variability and subsequent impact on minimally invasive surgery. Past cadaveric or radiologic anatomic assessments are noncomprehensive.

OBJECTIVE:

Intraoperative charting of right colonic arteriovenous anatomy was undertaken to determine the incidence and scope of vascular variations.

DESIGN:

Vascular anatomy variations were documented in snapshot images, captured during laparoscopic video recordings or through open surgical digital photography.

SETTINGS:

Data were drawn from consecutive right hemicolectomies, routinely entailing complete mesocolic excision with central vascular ligation.

PATIENTS:

Seventy patients (mean age, 62.7 years; 37 women (52.8%); 33 men (47.2%)), each with surgically treatable right-sided colon cancer, were prospectively studied.

RESULTS:

Both ileocolic and middle colic arteries were regularly identified (100%), with right colic artery present in 41.4% of patients. Ileocolic and middle colic veins consistently drained into the right colon. Although the ileocolic vein always emptied into the superior mesenteric vein, drainage of the middle colic vein was split (superior mesenteric vein, 94.3%; gastrocolic trunk of Henle, 5.3%), as was drainage of the right colic (superior mesenteric vein, 43.3%; gastrocolic trunk of Henle, 56.7%) and accessory middle colic veins (superior mesenteric vein, 54.5%; gastrocolic trunk of Henle, 45.5%), present in 42.9% and 15.7% of patients. Gastrocolic trunk of Henle was found in 88.6% of patients, usually draining into the superior mesenteric vein. No significant sex-related differences were present regarding the incidence and scope of variability displayed by the right colic artery, right colic vein, accessory middle colic vein, or gastrocolic trunk of Henle classification (p > 0.05).

LIMITATIONS:

The inconsistency between cadaver and live surgery anatomy and the low BMI of the Asian population might be drawbacks of our study.

CONCLUSIONS:

Variations in right colonic arteriovenous channels, assessed intraoperatively, corroborate those established by cadaveric and radiologic means, prompting a new gastrocolic trunk of Henle classification.
Comparison of Intra-arterial and Subcutaneous Testicular Hyaluronidase Injection Treatments and the Vascular Complications of Hyaluronic Acid Filler
Authors: Wang Muyao , Li Wei , Zhang Yan , Tian Weidong , Wang Hang
Published: December 2016

BACKGROUND

Hyaluronidase is a key preventative treatment against vascular complications of hyaluronic acid (HA) filler injection, but the degradation profile of HA to hyaluronidase is limited, and the comparison between intra-arterial and subcutaneous injections of hyaluronidase has not been studied.

OBJECTIVE

To evaluate HA degradation to hyaluronidase and compare different treatments between intra-arterial and subcutaneous testicular hyaluronidase injections.

MATERIALS AND METHODS

The authors observed HA degradation to hyaluronidase in vitro via microscopic examination and particle analysis. Rabbit ears were used for the in vivo study. There were 2 control groups receiving ligation or HA-induced embolism in the arteries, respectively, and 2 intervention groups receiving hyaluronidase treatments in different regions. The laser Doppler blood perfusion monitoring measurements were made at defined time points, and biopsies were taken on Day 2.

RESULTS

Nearly, all of the HAs degraded in vitro at the 1-hour time point. Subcutaneous hyaluronidase treatment showed better recovery of blood perfusion. Histology showed severe inflammation in the embolism group and mild inflammation in the intervention groups.

CONCLUSION

A complete enzymatic degradation of HA filler to hyaluronidase needs a certain time, and subcutaneous hyaluronidase treatment may be the better option.
Clinical coordination in accountable care organizations: A qualitative study
Authors: Lewis Valerie A. , Schoenherr Karen , Fraze Taressa , Cunningham Aleen
Published: December 2016

Background:

Accountable care organizations (ACOs) are becoming a common payment and delivery model. Despite widespread interest, little empirical research has examined what efforts or strategies ACOs are using to change care and reduce costs. Knowledge of ACOs' clinical efforts can provide important context for understanding ACO performance, particularly to distinguish arenas where ACOs have and have not attempted care transformation.

Purpose:

The aim of the study was to understand ACOs' efforts to change clinical care during the first 18 months of ACO contracts.

Methods:

We conducted semistructured interviews between July and December 2013. Our sample includes ACOs that began performance contracts in 2012, including Medicare Shared Savings Program and Pioneer participants, stratified across key factors. In total, we conducted interviews with executives from 30 ACOs. Iterative qualitative analysis identified common patterns and themes.

Results:

ACOs in the first year of performance contracts are commonly focusing on four areas: first, transforming primary care through increased access and team-based care; second, reducing avoidable emergency department use; third, strengthening practice-based care management; and fourth, developing new boundary spanner roles and activities. ACOs were doing little around transforming specialty care, acute and postacute care, or standardizing care across practices during the first 18 months of ACO performance contracts.

Practice Implications:

Results suggest that cost reductions associated with ACOs in the first years of contracts may be related to primary care. Although in the long term many hope ACOs will achieve coordination across a wide array of care settings and providers, in the short term providers under ACO contracts are focused largely on primary care-related strategies. Our work provides a template of the common areas of clinical activity in the first years of ACO contracts, which may be informative to providers considering becoming an ACO. Further research will be needed to understand how these strategies are associated with performance.