bluuebunny/crossref_metadata_2025 huggingface dataset:
Autophagy in health and disease: focus on the cardiovascular system
Authors: Mialet-Perez Jeanne , Vindis Cécile
Published: December 2017

Autophagy is a highly conserved mechanism of lysosome-mediated protein and organelle degradation that plays a crucial role in maintaining cellular homeostasis. In the last few years, specific functions for autophagy have been identified in many tissues and organs. In the cardiovascular system, autophagy appears to be essential to heart and vessel homeostasis and function; however defective or excessive autophagy activity seems to contribute to major cardiovascular disorders including heart failure (HF) or atherosclerosis. Here, we review the current knowledge on the role of cardiovascular autophagy in physiological and pathophysiological conditions.
To be or not to be cell autonomous? Autophagy says both
Authors: Fenouille Nina , Nascimbeni Anna Chiara , Botti-Millet Joëlle , Dupont Nicolas , Morel Etienne , Codogno Patrice
Published: December 2017

Although cells are a part of the whole organism, classical dogma emphasizes that individual cells function autonomously. Many physiological and pathological conditions, including cancer, and metabolic and neurodegenerative diseases, have been considered mechanistically as cell-autonomous pathologies, meaning those that damage or defect within a selective population of affected cells suffice to produce disease. It is becoming clear, however, that cells and cellular processes cannot be considered in isolation. Best known for shuttling cytoplasmic content to the lysosome for degradation and repurposing of recycled building blocks such as amino acids, nucleotides, and fatty acids, autophagy serves a housekeeping function in every cell and plays key roles in cell development, immunity, tissue remodeling, and homeostasis with the surrounding environment and the distant organs. In this review, we underscore the importance of taking interactions with the microenvironment into consideration while addressing the cell autonomous and non-autonomous functions of autophagy between cells of the same and different types and in physiological and pathophysiological situations.
Dysregulation of autophagy as a common mechanism in lysosomal storage diseases
Authors: Seranova Elena , Connolly Kyle J. , Zatyka Malgorzata , Rosenstock Tatiana R. , Barrett Timothy , Tuxworth Richard I. , Sarkar Sovan
Published: December 2017

The lysosome plays a pivotal role between catabolic and anabolic processes as the nexus for signalling pathways responsive to a variety of factors, such as growth, nutrient availability, energetic status and cellular stressors. Lysosomes are also the terminal degradative organelles for autophagy through which macromolecules and damaged cellular components and organelles are degraded. Autophagy acts as a cellular homeostatic pathway that is essential for organismal physiology. Decline in autophagy during ageing or in many diseases, including late-onset forms of neurodegeneration is considered a major contributing factor to the pathology. Multiple lines of evidence indicate that impairment in autophagy is also a central mechanism underlying several lysosomal storage disorders (LSDs). LSDs are a class of rare, inherited disorders whose histopathological hallmark is the accumulation of undegraded materials in the lysosomes due to abnormal lysosomal function. Inefficient degradative capability of the lysosomes has negative impact on the flux through the autophagic pathway, and therefore dysregulated autophagy in LSDs is emerging as a relevant disease mechanism. Pathology in the LSDs is generally early-onset, severe and life-limiting but current therapies are limited or absent; recognizing common autophagy defects in the LSDs raises new possibilities for therapy. In this review, we describe the mechanisms by which LSDs occur, focusing on perturbations in the autophagy pathway and present the latest data supporting the development of novel therapeutic approaches related to the modulation of autophagy.
Circularly polarised MIMO ground radiation antennas for wearable devices
Authors: Qu Longyue , Piao Haiyan , Qu Yunhao , Kim Hyung‐Hoon , Kim Hyeongdong
Published: December 2017

Two ground radiation antennas with polarisation diversity performance were proposed for MIMO WLAN applications in wearable devices. The antennas can simultaneously excite the vertical mode and horizontal mode of the ground plane and the phase difference between the two modes can be controlled by utilising an inductor‐loaded metal strip in the ground plane, generating circular polarisation. A 3:1 VSWR bandwidth of 140 MHz with high isolation (above 17 dB) and a 3 dB axial ratio bandwidth of 100 MHz was obtained. The opposite rotations generated by the two antennas resulted in good diversity performance, which was verified by the measured envelope correlation coefficient.
Single image dehazing and denoising combining dark channel prior and variational models
Authors: Wang Zhi , Hou Guojia , Pan Zhenkuan , Wang Guodong
Published: December 2017

Single image dehazing and denoising models can simultaneously remove haze and noise with high efficiency. Here, the authors propose three variational models combining the celebrated dark channel prior (DCP) and total variations (TV) models for image dehazing and denoising. The authors firstly estimate the transmission map associated with depth using DCP, then design three variational models for colour image dehazing and denoising based on this estimation and the layered total variation (LTV) regulariser, multichannel total variation (MTV) regulariser, and colour total variation (CTV) regulariser, respectively. In order to improve the computation efficiency of the three models, the authors design their fast split Bregman algorithms via introducing some auxiliary variables and the Bregman iterative parameters. Numerous experiments are presented to compare their denoising effects, edge‐preserving properties, and computation efficiencies. To demonstrate the merits of the proposed models, the authors also conduct some comparisons with several existing state‐of‐the‐art methods. Numerical results further prove that the LTV‐based model is fastest, and the CTV model is the best for denoising with edge‐preserving, and it also leads to the best visually haze‐free and noise‐free images.
Research on the ranging statistical distribution of laser radar with a constant fraction discriminator
Authors: Jiancheng Lai , Chunyong Wang , Wei Yan , Zhenhua Li
Published: December 2017

A theoretical framework is presented to describe the statistical distribution of ranging data obtained by laser radar with a constant fraction discriminator. The solution's correctness has been verified by Monte‐Carlo simulation and fixed‐target‐ranging experiments. Based on the numerical calculations, the influences of delay and attenuation on the distribution of ranging data were discussed comprehensively, and found that there exist optimal delay and attenuation to make laser radar has best precision, the optimal attenuation k  = 0.7 and delay τ  = 2 ns for the calculation condition. At the optimal attenuation and delay, the peak position of ranging data distribution is free of the signal's amplitude, and the ranging data distribution is very close to the normal distribution with R2 0.99991.
Comparative study of SPEX and planetary milling methods for the fabrication of complex metallic alloy nanoparticles
Authors: Zolriasatein Ashkan , Shokuhfar Ali , Safari Fardin , Abdi Nazanin
Published: December 2017

The objective of the present work is the comparison of two common milling methods for the production of complex metallic alloy nanoparticles. γ‐Al12Mg17 nanoparticles were fabricated using both a planetary ball mill and a SPEX mill. The produced nanoparticles have been compared on the basis of the phase and microstructural characterisations by means of X‐ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. The crystallite size, lattice strain, and lattice parameter have been calculated from the XRD data followed by an investigation on the powder morphology and particle size by FESEM. It has been indicated that the higher milling speed in the SPEX milling method leads to a higher milling energy and consequently lower particle size. For the same milling time of 2 h, the particle size decreases down to nano‐scale using a SPEX ball mill whereas the planetary ball mill products contained a varied size in the range of micron and submicron regimes. Furthermore, the results showed approximate crystalline sizes of 12 and 85 nm for the Al12Mg17 in SPEX and planetary ball mills after 2 h of milling time, respectively.
An X-ray survey of the central molecular zone: Variability of the Fe Kα emission line
Authors: Terrier R. , Clavel M. , Soldi S. , Goldwurm A. , Ponti G. , Morris M. R. , Chuard D.
Published: December 2017

There is now abundant evidence that the luminosity of the Galactic super-massive black hole (SMBH) has not always been as low as it is nowadays. The observation of varying non-thermal diffuse X-ray emission in molecular complexes in the central 300 pc has been interpreted as delayed reflection of a past illumination by bright outbursts of the SMBH. The observation of different variability timescales of the reflected emission in the Sgr A molecular complex can be well explained if the X-ray emission of at least two distinct and relatively short events (i.e. about 10 yr or less) is currently propagating through the region. The number of such events or the presence of a long-duration illumination are open questions. Variability of the reflected emission all over of the central 300 pc, in particular in the 6.4 keV Fe Kα line, can bring strong constraints. To do so we performed a deep scan of the inner 300 pc with XMM-Newton in 2012. Together with all the archive data taken over the course of the mission, and in particular a similar albeit more shallow scan performed in 2000–2001, this allows for a detailed study of variability of the 6.4 keV line emission in the region, which we present here. We show that the overall 6.4 keV emission does not strongly vary on average, but variations are very pronounced on smaller scales. In particular, most regions showing bright reflection emission in 2000–2001 significantly decrease by 2012. We discuss those regions and present newly illuminated features. The absence of bright steady emission argues against the presence of an echo from an event of multi-centennial duration and most, if not all, of the emission can likely be explained by a limited number of relatively short (i.e. up to 10 yr) events.
MUSE observations of the counter-rotating nuclear ring in NGC 7742
Authors: Martinsson Thomas P. K. , Sarzi Marc , Knapen Johan H. , Coccato Lodovico , Falcón-Barroso Jesús , Elmegreen Bruce G. , de Zeeuw Tim
Published: December 2017

Aims. We present results from MUSE observations of the nearly face-on disk galaxy NGC 7742. This galaxy hosts a spectacular nuclear ring of enhanced star formation, which is unusual in that it is hosted by a non-barred galaxy, and because this star formation is most likely fuelled by externally accreted gas that counter-rotates with respect to its main stellar body.

Methods. We used the MUSE data to derive the star-formation history (SFH) and accurately measure the stellar and ionized-gas kinematics of NGC 7742 in its nuclear, bulge, ring, and disk regions.

Results. We have mapped the previously known gas counter-rotation well outside the ring region and deduce the presence of a slightly warped inner disk, which is inclined at approximately 6° compared to the outer disk. The gas-disk inclination is well constrained from the kinematics; the derived inclination 13.7°  ± 0.4° agrees well with that derived from photometry and from what one expects using the inverse Tully-Fisher relation. We find a prolonged SFH in the ring with stellar populations as old as 2–3 Gyr and an indication that the star formation triggered by the minor merger event was delayed in the disk compared to the ring. There are two separate stellar components: an old population that counter-rotates with the gas, and a young one, concentrated to the ring, that co-rotates with the gas. We recover the kinematics of the old stars from a two-component fit, and show that combining the old and young stellar populations results in the erroneous average velocity of nearly zero found from a one-component fit.

Conclusions. The spatial resolution and field of view of MUSE allow us to establish the kinematics and SFH of the nuclear ring in NGC 7742. We show further evidence that this ring has its origin in a minor merger event, possibly 2–3 Gyr ago.
Horizontal flow below solar filaments
Authors: Ambrož P. , Pötzi W.
Published: December 2017

Context. Observations of the internal fine structures of solar filaments indicate that the threads of filaments follow magnetic field lines. The magnetic field inside the filament has a strong axial component. Some models of magnetic fields suggest that the field structure in filaments could be caused by the horizontal plasma velocity field near both sides below the filament, where observable shearing effects from the axial component are expected.

Aims. The horizontal velocity field in the vicinity of polarity inversion lines is measured in order to determine, if it exhibits a systematic movement that induces shear along the filament axis and convergence perpendicular to the axis.

Methods. The horizontal velocity was obtained from the displacement of supergranules, which were derived from Doppler measurements in the solar photosphere. Dopplergrams corrected for rigid rotation and p-mode oscillations were further analyzed by local correlation tracking.

Results. Vector fields of the horizontal velocities were measured in 16 areas during 8 time intervals in the years 2000–2002 on both solar hemispheres, each for a few consecutive days. For 64 selected filaments the nearby horizontal velocity vectors were split up into a component along the filament axis and a perpendicular component.

Conclusions. Differences between the axial velocities on both sides of the filaments were calculated. In almost all cases the velocity gradient corresponds to the inclination of the threads observed in Hα images. The average transverse velocity does not show any preferred tendency towards a divergence or convergence to the filament axis. Testing the horizontal velocity for the creation of the differential rotation profile in the photosphere reveals a strong dependence of the averaging process on the scale of our velocities.
Superhumps linked to X-ray emission
Authors: Neustroev V. V. , Page K. L. , Kuulkers E. , Osborne J. P. , Beardmore A. P. , Knigge C. , Marsh T. , Suleimanov V. F. , Zharikov S. V.
Published: December 2017

Context. We present more than 4 years of Swift X-ray observations of the 2013 superoutburst, subsequent decline and quiescence of the WZ Sge-type dwarf nova SSS J122221.7−311525 (SSS J122222) from 6 days after discovery.

Aims. Only a handful of WZ Sge-type dwarf novae have been observed in X-rays, and until recently GW Lib was the only binary of this type with complete coverage of an X-ray light curve throughout a superoutburst. We collected extensive X-ray data of a second such system to understand the extent to which the unexpected properties of GW Lib are common to the WZ Sge class.

Methods. We collected 60 Swift-XRT observations of SSS J122222 between 2013 January 6 and 2013 July 1. Four follow-up observations were performed in 2014, 2015, 2016 and 2017. The total exposure time of our observations is 86.6 ks. We analysed the X-ray light curve and compared it with the behaviour of superhumps which were detected in the optical light curve. We also performed spectral analysis of the data. The results were compared with the properties of GW Lib, for which new X-ray observations were also obtained.

Results. SSS J122222 was variable and around five times brighter in 0.3–10 keV X-rays during the superoutburst than in quiescence, mainly because of a significant strengthening of a high-energy component of the X-ray spectrum. The post-outburst decline of the X-ray flux lasted at least 500 d. The data show no evidence of the expected optically thick boundary layer in the system during the outburst. SSS J122222 also exhibited a sudden X-ray flux change in the middle of the superoutburst, which occurred exactly at the time of the superhump stage transition. A similar X-ray behaviour was also detected in GW Lib.

Conclusions. We show that the X-ray flux exhibits changes at the times of changes in the superhump behaviour of both SSS J122222 and GW Lib. This result demonstrates a relationship between the outer disc and the white dwarf boundary layer for the first time, and suggests that models for accretion discs in high mass ratio accreting binaries are currently incomplete. The very long decline to X-ray quiescence is also in strong contrast to the expectation of low viscosity in the disc after outburst.
Wolf–Rayet stars in the Small Magellanic Cloud as testbed for massive star evolution
Authors: Schootemeijer A. , Langer N.
Published: December 2017

Context. The majority of the Wolf–Rayet (WR) stars represent the stripped cores of evolved massive stars who lost most of their hydrogen envelope. Wind stripping in single stars is expected to be inefficient in producing WR stars in metal-poor environments such as the Small Magellanic Cloud (SMC). While binary interaction can also produce WR stars at low metallicity, it is puzzling that the fraction of WR binaries appears to be about 40%, independent of the metallicity.

Aim. We aim to use the recently determined physical properties of the twelve known SMC WR stars to explore their possible formation channels through comparisons with stellar models.

Methods. We used the MESA stellar evolution code to construct two grids of stellar models with SMC metallicity. One of these consists of models of rapidly rotating single stars, which evolve in part or completely chemically homogeneously. In a second grid, we analyzed core helium burning stellar models assuming constant hydrogen and helium gradients in their envelopes.

Results. We find that chemically homogeneous evolution is not able to account for the majority of the WR stars in the SMC. However, in particular the apparently single WR star SMC AB12, and the double WR system SMC AB5 (HD 5980) appear consistent with this channel. We further find a dichotomy in the envelope hydrogen gradients required to explain the observed temperatures of the SMC WR stars. Shallow gradients are found for the WR stars with O star companions, while much steeper hydrogen gradients are required to understand the group of hot apparently single WR stars.

Conclusions. The derived shallow hydrogen gradients in the WR component of the WR+O star binaries are consistent with predictions from binary models where mass transfer occurs early, in agreement with their binary properties. Since the hydrogen profiles in evolutionary models of massive stars become steeper with time after the main sequence, we conclude that most of the hot (Teff > 60 kK ) apparently single WR stars lost their envelope after a phase of strong expansion, e.g., as the result of common envelope evolution with a lower mass companion. The so far undetected companions, either main sequence stars or compact objects, are then expected to still be present. A corresponding search might identify the first immediate double black hole binary progenitor with masses as high as those detected in GW150914.
Discovery of a point-like source and a third spiral arm in the transition disk around the Herbig Ae star MWC 758
Authors: Reggiani M. , Christiaens V. , Absil O. , Mawet D. , Huby E. , Choquet E. , Gomez Gonzalez C. A. , Ruane G. , Femenia B. , Serabyn E. , Matthews K. , Barraza M. , Carlomagno B. , Defrère D. , Delacroix C. , Habraken S. , Jolivet A. , Karlsson M. , Orban de Xivry G. , Piron P. , Surdej J. , Vargas Catalan E. , Wertz O.
Published: December 2017

Context.Transition disks offer the extraordinary opportunity to look for newly born planets and to investigate the early stages of planet formation.

Aim.In this context we observed the Herbig A5 star MWC 758 with theL′-band vector vortex coronagraph installed in the near-infrared camera and spectrograph NIRC2 at the Keck II telescope, with the aim of unveiling the nature of the spiral structure by constraining the presence of planetary companions in the system.

Methods.Our high-contrast imaging observations show a bright (ΔL′= 7.0 ± 0.3 mag) point-like emission south of MWC 758 at a deprojected separation of ~20 au (r= 0.′′111 ± 0.′′004) from the central star. We also recover the two spiral arms (southeast and northwest), already imaged by previous studies in polarized light, and discover a third arm to the southwest of the star. No additional companions were detected in the system down to 5 Jupiter masses beyond 0.′′6 from the star.

Results.We propose that the brightL′-band emission could be caused by the presence of an embedded and accreting protoplanet, although the possibility of it being an asymmetric disk feature cannot be excluded. The spiral structure is probably not related to the protoplanet candidate, unless on an inclined and eccentric orbit, and it could be due to one (or more) yet undetected planetary companions at the edge of or outside the spiral pattern. Future observations and additional simulations will be needed to shed light on the true nature of the point-like source and its link with the spiral arms.
Risk Factors for Postoperative Venous Thromboembolic Complications after Microsurgical Breast Reconstruction
Authors: Sultan Steven , Jackson Danielle , Erhard Heather , Greenspun David , Benacquista Teresa , Garfein Evan , Weichman Katie
Published: December 2017

Background Venous thromboembolism (VTE) is a significant cause of postoperative morbidity and a focus of patient safety initiatives. Despite giving appropriate prophylaxis in accordance with the Caprini risk assessment model, we observed a high incidence of VTE in patients undergoing microsurgical breast reconstruction at our institution. To explore factors contributing to these events, we compared patients undergoing microsurgical breast reconstruction who sustained postoperative VTEs to those who did not.

Methods A retrospective review of all patients who underwent microsurgical free flap breast reconstruction at Montefiore Medical Center from January 2009 to January 2016 was conducted. Patients were divided into two cohorts; those sustaining postoperative VTE and those who did not. Patients were compared based on demographics, comorbidities, operative time, estimated intraoperative blood loss, need for transfusion, volume of transfusion, and discharge on postoperative aspirin.

Results A total of 133 patients underwent microsurgical breast reconstruction during the study period. Nine patients (6.8%) had postoperative VTE and there was one (0.8%) death. Patients having VTE were more likely to be Hispanic (33.3%, n = 3) in the VTE group versus 8.1% (n = 6) in the control group (p = 0.011), more likely to have an increased mean transfusion volume (455.5 ± 367.8 vs. 139.51 ± 221.7 mL, p = 0.03), and were more likely to be discharged without aspirin (77.8%, n = 7 and 58.1%, n = 72; p = 0.003).

Conclusion Patients sustaining postoperative VTE after microsurgical breast reconstruction are more likely to have an increased volume of blood transfusions and lack of discharge on postoperative aspirin.
Daten zur Behandlungsrealität des diabetischen Makulaödems mit Ranibizumab
Authors: Wilke Robert , Finger Robert , Sachs Helmut
Published: December 2017

Hintergrund Prospektive kontrollierte Studien zur Behandlung des diabetischen Makulaödems (DME) mit Anti-VEGF-Therapeutika zeigen ein sehr gutes Visusergebnis über mehrere Jahre hinweg. Bisher liegen kaum Daten über Ergebnisse in der klinischen Behandlungsrealität vor, obwohl aus anderen Indikationsbereichen bekannt ist, dass die Ergebnisse der klinischen Routine oft denen aus prospektiven, kontrollierten Studien in Visusergebnis und Anzahl an Injektionen hinterherhinken. Wir berichten über eine Fallserie der Behandlung des DME an unserer Klinik.

Patienten/Material und Methoden Retrospektive Fallserie von 335 Fällen mit einer Nachbeobachtungszeit von bis zu 3 Jahren. Fälle aus einem Zentrum, die wegen eines visusrelevanten diabetischen Makulaödems mindestens 1 Lucentisinjektion erhalten haben, wurden unter Auswertung des Verlaufs der zentralen Sehschärfe sowie der Anzahl von Injektionen ausgewertet.

Ergebnisse Es findet sich ein mittlerer Gewinn an Sehschärfe im 1. und 2. Jahr von + 5,6 bzw. + 3,7 Buchstaben im Vergleich zur Baseline bei einem Ausgangsvisus von logMAR 0,52 (dezimal 0,3). Der Visusgewinn wird hauptsächlich in den ersten 4 Monaten erreicht, danach findet sich noch bis Monat 16 ein weiterer, jedoch flacherer Anstieg der Sehschärfe. Die mittlere Anzahl von Injektionen lag im 1., 2. und 3. Jahr bei 5,7, 3,2 und 1,1 Injektionen.

Schlussfolgerung Die Daten zeigen einen Unterschied in der Behandlungsrealität des DME im Vergleich zu prospektiven, kontrollierten Studien, wie er bereits bei anderen Indikationen der Anti-VEGF-Therapie gefunden wurde: Der initiale Visusgewinn fällt geringer aus als in kontrollierten Studien und er kann nicht vollständig über längere Zeit gehalten werden. Diese geht einher mit einer deutlich geringeren Anzahl an Injektionen als in kontrollierten Studien. Gründe können in unterschiedlichen Patientenpopulationen liegen sowie in einer Negativselektion im Langzeitverlauf. Barrieren, die darüber hinaus eine zügige und bedarfsgerechte Therapie behindern, müssen weiter identifiziert und möglichst umgangen werden.
Linksventrikuläre Assist-Systeme – Verbesserungsmöglichkeiten in der ambulanten Versorgung
Authors: Burkhard-Meier Caspar , Morshuis Michiel
Published: December 2017

The use of left-ventricular assist device therapy (LVAD) in terminal heart failure patients is increasing. Many patients are receiving LVAD-therapy as final solution (destination therapy). After discharge from the implanting heart center patient-centered care has to be implemented on an outpatient basis. A responsible ambulatory treatment of this severe heart failure population requires knowledge about LVAD specific problems (general medical care, long term complications, device management). The referring cardiologist as well as the private practitioner should be more involved in the care of patients with LVAD. By this means patients safety would increase and the overall costs decline not at least due to fewer hospital readmissions.
Biopsy of Liver Target Lesions under Contrast-Enhanced Ultrasound Guidance – A Multi-Center Study
Authors: Francica Giampiero , Meloni Maria , de Sio Ilario , Terracciano Fulvia , Caturelli Eugenio , Riccardi Laura , Roselli Paola , Iadevaia Maddalena , Scaglione Mariano , Lenna Giovanni , Chiang Jason , Pompili Maurizio
Published: December 2017

Purpose To retrospectively characterize the prevalence and impact of contrast-enhanced ultrasound (CEUS) as a guidance technique for the biopsy of liver target lesions (LTLs) at six interventional ultrasound centers.

Materials and Methods The six participating centers retrospectively selected all patients in whom biopsy needles were positioned in LTLs during CEUS. The prevalence of CEUS-guided biopsies at each center between 2005 and 2016, contrast agent consumption, procedure indications, diagnostic yield and complications were assessed. Informed consent was obtained for all patients.

Results CEUS-guided biopsy of LTLs was carried out in 103 patients (68 M/35 F, median age: 69 yrs) with 103 liver target lesions (median size: 20 mm) using cutting needles (18 – 20 g) in 94 cases (91.2 %). CEUS-guided biopsy represented 2.6 % (range: 0.8 – 7.7 %) of 3818 biopsies on LTLs carried out at the participating centers. Indications to CEUS-guided biopsy were: a target lesion not visible on non-enhanced US (27.2 %), improvement of conspicuity of the target (33 %), choice of non-necrotic area inside the target (39.8 %). 26 patients (25.2 %) had a previously non-diagnostic cyto-histological exam. The diagnostic accuracy of the technique was 99 %. No major complications followed infusion of contrast agent or biopsy performance.

Conclusion The indications for CEUS-guided biopsy for LTLs are limited, but CEUS can be useful in challenging clinical scenarios, e. g. poorly visualized or invisible lesions or sampling of non-necrotic areas in the target lesions. There is also a potential advantage in using CEUS to guide repeat biopsies after unsuccessful sampling performed using the standard ultrasound technique.
Wide-angle display-type retarding field analyzer with high energy and angular resolutions
Authors: Muro Takayuki , Ohkochi Takuo , Kato Yukako , Izumi Yudai , Fukami Shun , Fujiwara Hidenori , Matsushita Tomohiro
Published: December 2017

Deployments of spherical grids to obtain high energy and angular resolutions for retarding field analyzers (RFAs) having acceptance angles as large as or larger than ±45° were explored under the condition of using commercially available microchannel plates with effective diameters of approximately 100 mm. As a result of electron trajectory simulations, a deployment of three spherical grids with significantly different grid separations instead of conventional equidistant separations showed an energy resolving power (E/ΔE) of 3200 and an angular resolution of 0.6°. The mesh number of the wire mesh retarding grid used for the simulation was 250. An RFA constructed with the simulated design experimentally showed an E/ΔE of 1100 and an angular resolution of 1°. Using the RFA and synchrotron radiation of 900 eV, photoelectron diffraction (PED) measurements were performed for single-crystal graphite. A clear C 1s PED pattern was observed even when the differential energy of the RFA was set at 0.5 eV. Further improvement of the energy resolution was theoretically examined under the assumption of utilizing a retarding grid fabricated by making a large number of radially directed cylindrical holes through a partial spherical shell instead of using a wire mesh retarding grid. An E/ΔE of 14 500 was predicted for a hole design with a diameter of 60 μm and a depth of 100 μm. A retarding grid with this hole design and a holed area corresponding to an acceptance angle of ±7° was fabricated. An RFA constructed with this retarding grid experimentally showed an E/ΔE of 1800. Possible reasons for the experimental E/ΔE lower than the theoretical values are discussed.
Theoretical study of the generation of terahertz radiation by the interaction of two laser beams with graphite nanoparticles
Authors: Sepehri Javan N. , Rouhi Erdi F.
Published: December 2017

In this theoretical study, we investigate the generation of terahertz radiation by considering the beating of two similar Gaussian laser beams with different frequencies of ω1 and ω2 in a spatially modulated medium of graphite nanoparticles. The medium is assumed to contain spherical graphite nanoparticles of two different configurations: in the first configuration, the electric fields of the laser beams are parallel to the normal vector of the basal plane of the graphite structure, whereas in the second configuration, the electric fields are perpendicular to the normal vector of the basal plane. The interaction of the electric fields of lasers with the electronic clouds of the nanoparticles generates a ponderomotive force that in turn leads to the creation of a macroscopic electron current in the direction of laser polarizations and at the beat frequency ω1−ω2, which can generate terahertz radiation. We show that, when the beat frequency lies near the effective plasmon frequency of the nanoparticles and the electric fields are parallel to the basal-plane normal, a resonant interaction of the laser beams causes intense terahertz radiation.
A new generation of effective core potentials for correlated calculations
Authors: Bennett M. Chandler , Melton Cody A. , Annaberdiyev Abdulgani , Wang Guangming , Shulenburger Luke , Mitas Lubos
Published: December 2017

We outline ideas on desired properties for a new generation of effective core potentials (ECPs) that will allow valence-only calculations to reach the full potential offered by recent advances in many-body wave function methods. The key improvements include consistent use of correlated methods throughout ECP constructions and improved transferability as required for an accurate description of molecular systems over a range of geometries. The guiding principle is the isospectrality of all-electron and ECP Hamiltonians for a subset of valence states. We illustrate these concepts on a few first- and second-row atoms (B, C, N, O, S), and we obtain higher accuracy in transferability than previous constructions while using semi-local ECPs with a small number of parameters. In addition, the constructed ECPs enable many-body calculations of valence properties with higher (or same) accuracy than their all-electron counterparts with uncorrelated cores. This implies that the ECPs include also some of the impacts of core-core and core-valence correlations on valence properties. The results open further prospects for ECP improvements and refinements.
Propensity of a single-walled carbon nanotube-peptide to mimic a KK10 peptide in an HLA-TCR complex
Authors: Feng Mei , Bell David R. , Zhou Ruhong
Published: December 2017

The application of nanotechnology to improve disease diagnosis, treatment, monitoring, and prevention is the goal of nanomedicine. We report here a theoretical study of a functionalized single-walled carbon nanotube (CNT) mimic binding to a human leukocyte antigen-T cell receptor (HLA-TCR) immune complex as a first attempt of a potential nanomedicine for human immunodeficiency virus (HIV) vaccine development. The carbon nanotube was coated with three arginine residues to imitate the HIV type 1 immunodominant viral peptide KK10 (gag 263–272: KRWIILGLNK), named CNT-peptide hereafter. Through molecular dynamics simulations, we explore the CNT-peptide and KK10 binding to an important HLA-TCR complex. Our results suggest that the CNT-peptide and KK10 bind comparably to the HLA-TCR complex, but the CNT-peptide forms stronger interactions with the TCR. Desorption simulations highlight the innate flexibility of KK10 over the CNT-peptide, resulting in a slightly higher desorption energy required for KK10 over the CNT-peptide. Our findings indicate that the designed CNT-peptide mimic has favorable propensity to activate TCR pathways and should be further explored to understand therapeutic potential.
Surrogate-assisted identification of influences of network construction on evolving weighted functional networks
Authors: Stahn Kirsten , Lehnertz Klaus
Published: December 2017

We aim at identifying factors that may affect the characteristics of evolving weighted networks derived from empirical observations. To this end, we employ various chains of analysis that are often used in field studies for a data-driven derivation and characterization of such networks. As an example, we consider fully connected, weighted functional brain networks before, during, and after epileptic seizures that we derive from multichannel electroencephalographic data recorded from epilepsy patients. For these evolving networks, we estimate clustering coefficient and average shortest path length in a time-resolved manner. Lastly, we make use of surrogate concepts that we apply at various levels of the chain of analysis to assess to what extent network characteristics are dominated by properties of the electroencephalographic recordings and/or the evolving weighted networks, which may be accessible more easily. We observe that characteristics are differently affected by the unavoidable referencing of the electroencephalographic recording, by the time-series-analysis technique used to derive the properties of network links, and whether or not networks were normalized. Importantly, for the majority of analysis settings, we observe temporal evolutions of network characteristics to merely reflect the temporal evolutions of mean interaction strengths. Such a property of the data may be accessible more easily, which would render the weighted network approach—as used here—as an overly complicated description of simple aspects of the data.
Structure of correlations for the Boltzmann-Grad limit of hard spheres
Authors: Denlinger Ryan
Published: December 2017

We consider a gas of N identical hard spheres in the whole space, and we enforce the Boltzmann-Grad scaling. We may suppose that the particles are essentially independent of each other at some initial time; even so, correlations will be created by the dynamics. We will prove a structure theorem for the correlations which develop at positive time. Our result generalizes a previous result which states that there are phase points where the three-particle marginal density factorizes into two-particle and one-particle parts, while further factorization is impossible. The result depends on uniform bounds which are known to hold on a small time interval or globally in time when the mean free path is large.
Coexisting nanoscale inverse spinel and rock salt crystallographic phases in NiCo2O4 epitaxial thin films grown by pulsed laser deposition
Authors: Sharona H. , Loukya B. , Bhat U. , Sahu R. , Vishal B. , Silwal P. , Gupta A. , Datta R.
Published: December 2017

The origin of alternating wavy dark-bright stripe-like contrast in strain contrast transmission electron microscopy images of NiCo2O4 (NCO) epitaxial thin films grown by pulsed laser deposition has been investigated. The nanoscale stripe-like pattern is determined to be associated with coexisting rock salt (RS) and inverse spinel crystal phases. The presence of two different phases, not addressed in previous reports, is experimentally confirmed by both electron diffraction and high resolution transmission electron microscopy imaging. First principles based calculations, together with compressive strain present in the films, support the formation of such coexisting crystallographic phases in NCO. Similar microstructural patterns and RS structure are not observed in epitaxial films of two other oxides of the spinel family, namely, NiFe2O4 and CoFe2O4. A correlation between the coexisting structures and the macroscopic physical properties of NCO is discussed.
An ultrahigh-vacuum cryostat for simultaneous scanning tunneling microscopy and magneto-transport measurements down to 400 mK
Authors: Liebmann Marcus , Bindel Jan Raphael , Pezzotta Mike , Becker Stefan , Muckel Florian , Johnsen Tjorven , Saunus Christian , Ast Christian R. , Morgenstern Markus
Published: December 2017

We present the design and calibration measurements of a scanning tunneling microscope setup in a 3He ultrahigh-vacuum cryostat operating at 400 mK with a hold time of 10 days. With 2.70 m in height and 4.70 m free space needed for assembly, the cryostat fits in a one-story lab building. The microscope features optical access, an xy table, in situ tip and sample exchange, and enough contacts to facilitate atomic force microscopy in tuning fork operation and simultaneous magneto-transport measurements on the sample. Hence, it enables scanning tunneling spectroscopy on microstructured samples which are tuned into preselected transport regimes. A superconducting magnet provides a perpendicular field of up to 14 T. The vertical noise of the scanning tunneling microscope amounts to 1 pmrms within a 700 Hz bandwidth. Tunneling spectroscopy using one superconducting electrode revealed an energy resolution of 120 μeV. Data on tip-sample Josephson contacts yield an even smaller feature size of 60 μeV, implying that the system operates close to the physical noise limit.
Thin film organic photodetectors for indirect X-ray detection demonstrating low dose rate sensitivity at low voltage operation
Authors: Starkenburg Daken J. , Johns Paul M. , Baciak James E. , Nino Juan C. , Xue Jiangeng
Published: December 2017

Developments in the field of organic semiconductors have generated organic photodetectors with high quantum efficiency, wide spectral sensitivity, low power consumption, and unique form factors that are flexible and conformable to their substrate shape. In this work, organic photodetectors coupled with inorganic CsI(Tl) scintillators are used to showcase the low dose rate sensitivity that is enabled when high performance organic photodetectors and scintillator crystals are integrated. The detection capability of these organic-inorganic coupled systems to high energy radiation highlights their potential as an alternative to traditional photomultiplier tubes for nuclear spectroscopy applications. When exposed to Bremsstrahlung radiation produced from an X-ray generator, SubPc:C60, AlPcCl:C70, and P3HT:PC61BM thin film photodetectors with active layer thicknesses less than 100 nm show detection of incident radiation at low and no applied bias. Remarkably low dose rates, down to at least 0.18 μGy/s, were detectable with a characteristic linear relationship between exposure rate and photodetector current output. These devices also demonstrate sensitivities as high as 5.37 mC Gy−1 cm−2 when coupled to CsI(Tl). Additionally, as the tube voltage across the X-ray generator was varied, these organic-inorganic systems showed their ability to detect a range of continuous radiation spectra spanning several hundred keV.
Geometric integrator for Langevin systems with quaternion-based rotational degrees of freedom and hydrodynamic interactions
Authors: Davidchack R. L. , Ouldridge T. E. , Tretyakov M. V.
Published: December 2017

We introduce new Langevin-type equations describing the rotational and translational motion of rigid bodies interacting through conservative and non-conservative forces and hydrodynamic coupling. In the absence of non-conservative forces, the Langevin-type equations sample from the canonical ensemble. The rotational degrees of freedom are described using quaternions, the lengths of which are exactly preserved by the stochastic dynamics. For the proposed Langevin-type equations, we construct a weak 2nd order geometric integrator that preserves the main geometric features of the continuous dynamics. The integrator uses Verlet-type splitting for the deterministic part of Langevin equations appropriately combined with an exactly integrated Ornstein-Uhlenbeck process. Numerical experiments are presented to illustrate both the new Langevin model and the numerical method for it, as well as to demonstrate how inertia and the coupling of rotational and translational motion can introduce qualitatively distinct behaviours.
Vibrational relaxation at a metal surface: Electronic friction versus classical master equations
Authors: Miao Gaohan , Dou Wenjie , Subotnik Joseph
Published: December 2017

Within a 2-D scattering model, we investigate the vibrational relaxation of an idealized molecule colliding with a metal surface. Two perturbative nonadiabatic dynamics schemes are compared: (i) electronic friction (EF) and (ii) classical master equations. In addition, we also study a third approach, (iii) a broadened classical master equation that interpolates between approaches (i) and (ii). Two conclusions emerge. First, even though we do not have exact data to compare against, we find there is strong evidence suggesting that EF results may be spurious for scattering problems. Second, we find that there is an optimal molecule-metal coupling that maximizes vibrational relaxation rates by inducing large nonadiabatic interactions.
Aging near rough and smooth boundaries in colloidal glasses
Authors: Cao Cong , Huang Xinru , Roth Connie B. , Weeks Eric R.
Published: December 2017

We use a confocal microscope to study the aging of a bidisperse colloidal glass near rough and smooth boundaries. Near smooth boundaries, the particles form layers, and particle motion is dramatically slower near the boundary as compared to the bulk. Near rough boundaries, the layers nearly vanish, and particle motion is nearly identical to that of the bulk. The gradient in dynamics near the boundaries is demonstrated to be a function of the gradient in structure for both types of boundaries. Our observations show that wall-induced layer structures strongly influence aging.
Stability and thermal behavior of molybdenum disulfide nanotubes: Nonequilibrium molecular dynamics simulation using REBO potential
Authors: Ahadi Zohreh , Shadman Lakmehsari Muhammad , Kumar Singh Sandeep , Davoodi Jamal
Published: December 2017

This study is an attempt to perform equilibrium molecular dynamics and non-equilibrium molecular dynamics (NEMD) to evaluate the stability and thermal behavior of molybdenum disulfide nanotubes (MoS2NTs) by reactive empirical bond order potential. The stability of nanotubes, cohesive energy, isobaric heat capacity, and enthalpies of fusion in armchair and zigzag structures with different radii were calculated. The observed results illustrate that SWMoS2NTs, which have larger diameters, are more stable with more negative energy than the smaller ones. Moreover, it was found that the melting point is increased with an increase in the nanotube's radius. During the melting process, the structural transformation of nanotubes was investigated using a mean-square displacement and radial distribution function diagrams. Afterwards, using a NEMD simulation, the thermal conductivity of nanotubes with various diameters was calculated at a constant nanotube length. The obtained results show that the thermal conductivity coefficient increases with increasing nanotube diameters when the nanotube length is constant.
How pattern is selected in drift wave turbulence: Role of parallel flow shear
Authors: Kosuga Y.
Published: December 2017

The role of parallel shear flow in the pattern selection problem in drift wave turbulence is discussed. Patterns of interest here are E × B convective cells, which include poloidally symmetric zonal flows and radially elongated streamers. The competition between zonal flow formation and streamer formation is analyzed in the context of modulational instability analysis, with the parallel flow shear as a parameter. For drift wave turbulence with k⊥ρs ≲ O(1) and without parallel flow coupling, zonal flows are preferred structures. While increasing the magnitude of parallel flow shear, streamer growth overcomes zonal flow growth. This is because the self-focusing effect of the modulational instability becomes more effective for streamers through density and parallel velocity modulation. As a consequence, the bursty release of free energy may result as the parallel flow shear increases.
Sound velocity during solidification in binary eutectic systems
Authors: Yoshioka Hideaki , Kyoden Tomoaki , Hachiga Tadashi
Published: December 2017

We applied an ultrasound technique to an advanced material process by investigating the behavior of sound velocity during solidification of binary alloy melts over a wide range of temperatures and compositions. To gain a basic understanding of the relationship between the sound velocity and phase change in binary eutectic systems, the sound velocity was measured in Pb-Sn and Bi-Sn alloys by the pulse transmission method. Based on the measurement results, we established a link between the sound velocity variation and the complex solidification process, including the initial appearance of undercooling and eutectic reaction. During solidification, alloys usually pass through a transient mushy state between the liquid and solid phases. Since the solid fraction is uniquely related to the sound velocity, we demonstrate that it is possible to identify the solid fraction in the mushy state using the sound velocity. At the eutectic point, a sudden change was observed in relation to the eutectic reaction, in which the sound velocity exhibited an abrupt transition under isothermal conditions. This sudden change in the sound velocity was evident even when the initial composition was below the maximum solid-solution limit, such as when the solute distribution coefficient was relatively large. This result suggests that the presence of a eutectic in the final solidified texture can be predicted using our sound velocity measurement system. Finally, we present a novel sound velocity phase diagram that provides a real-time state determination system using ultrasound during solidification process, such as casting.