bluuebunny/crossref_metadata_2025 huggingface dataset:
Outcomes of an international multicenter registry on EUS-guided gallbladder drainage in patients at high risk for cholecystectomy
Authors: Teoh A.Y. , Perez-Miranda Manuel , Kunda Rastislav , Lee Sang Soo , Irani Shayan , Yeaton Paul , Sun Siyu , Baron Todd Huntley , Moon Jong Ho , Holt Bronte , Khor Christopher J.L. , Rerknimitr Rungsun , Bapaye Amol , Chan Shannon Melissa , Choi Hyun Jong , James Theodore William , Kongkam Pradermchai , Lee Yun Nah , Parekh Parth , Ridtitid Wiriyaporn , Serna-Higuera Carlos , Tan Damien M.Y. , Torres-Yuste Raul
Published: July 2019

Background and study aims The aim of the current study was to review the outcomes of a large-scale international registry on endoscopic ultrasound-guided gallbladder drainage (EGBD) that encompasses different stent systems in patients who are at high-risk for cholecystectomy.

Patients and methods This was a retrospective international multicenter registry on EGBD created by 13 institutions around the world. Consecutive patients who received EGBD for several indications were included. Outcomes include technical and clinical success, unplanned procedural events (UPE), adverse events (AEs), mortality, recurrent cholecystitis and learning curve of the procedure.

Results Between June 2011 and November 2017, 379 patients were recruited to the study. Technical and clinical success were achieved in 95.3 % and 90.8 % of the patients, respectively. The 30-day AE rate was 15.3 % and 30-day mortality was 9.2 %. UPEs were significantly more common in patients with EGBD performed for conversion of cholecystostomy and symptomatic gallstones (P < 0.001); and by endoscopists with experience of fewer than 25 procedures (P = 0.033). Both presence of clinical failure (P = 0.014; RR 8.69 95 %CI [1.56 – 48.47]) and endoscopist experience with fewer than 25 procedures (P = 0.002; RR 4.68 95 %CI [1.79 – 12.26]) were significant predictors of 30-day AEs. Presence of 30-day AEs was a significant predictor of mortality (P < 0.001; RR 103 95 %CI [11.24 – 944.04]).

Conclusion EGBD was associated with high success rates in this large-scale study. EGBD performed for indications other than acute cholecystitis was associated with higher UPEs. The number of cases required to gain competency with the technique by experienced interventional endosonographers was 25 procedures.
Investigation of Radiation Exposure of Patients with Acute Ischemic Stroke during Mechanical Thrombectomy
Authors: Bärenfänger Felix , Block Andreas , Rohde Stefan
Published: July 2019

Purpose In radiological interventions, the skin is the most exposed organ. The aim of this study was to investigate the local dose exposure and the resulting risk of deterministic radiation effects for patients who underwent mechanichal thrombectomy.

Materials and Methods The examination protocols of 50 consecutive stroke patients who underwent mechanical thrombectomy from September 2016 to April 2017 were evaluated in this study. All procedures were performed on a biplanar angiographic suite. The local skin equivalent dose H
P(0.07) was calculated retrospectively using the recorded radiation data and previously measured conversion factors. The in-vitro determination of the conversion factors was performed with a silicon semiconductor detector on the surface of an Alderson-Rando head phantom depending on the radiation quality.

Results Vessel occlusion was located in the M1 and M2 segments of the cerebral artery media (n = 32), the internal carotid artery or carotid-T (n = 12) and the basilar artery (n = 6). The fluoroscopy times ranged from 5.7 minutes to 137.3 minutes with an average value of 39.5 ± 4.1 minutes. The determined skin equivalent dose values ranged from 0.16 ± 0.02 Gy to 4.80 ± 0.51 Gy, with the mean value being 1.00 ± 0.14 Gy. In 3 out of 50 cases (6 %), the threshold value for skin reactions of 3 Gy published by the German Radiation Protection Commission was exceeded. A further 15 patients (36 %) were exposed to a dose of 1–3 Gy. The highest dose values were achieved during long procedures with occlusions in the posterior circulation and carotid occlusions. In addition, a local dose reference level of 1.24 ± 0.15 Gy could be determined for the skin equivalent dose in mechanical thrombectomies for our center.

Conclusion Even during a modern neuroradiological intervention, such as mechanical thrombectomy, radiation doses to the patient are produced and can lead to deterministic radiation damage to the skin in approximately 6 % of cases. Systematic monitoring of local dose quantities, such as H
P(0.07), seems appropriate. Possibilities for recording and reducing the local dose load should be developed by the interventional teams in cooperation with a medical physics expert.

Key Points: 

Citation Format
Facile Strategy to Access the Indolo[2,3-a]quinolizidine Framework: Synthetic Study on Tangutorine
Authors: Reddy Chada Raji , Warudikar Kamalkishor , Latha Bellamkonda
Published: July 2019

An asymmetric synthetic approach to indolo[2,3-a]quinolizidine framework has been developed involving Horner–Wadsworth–Emmons olefination and reductive amination as the key steps. Further, the developed strategy was explored towards the synthesis of tangutorine using Evans aldol reaction for the preparation of desired aldehyde.
Carotid Artery Injury during Transsphenoidal Pituitary Surgery: Lessons from a 15-Year Modern Microsurgery Cohort
Authors: Meyer Jenna , Perry Avital , Graffeo Christopher S. , Carlstrom Lucas P. , Marcellino Christopher R. , Burrows Anthony , Bancos Irina , Driscoll Colin , Meyer Fredric B.
Published: July 2019

Background Internal carotid artery (ICA) injury is a rare but potentially catastrophic complication of transsphenoidal resection (TSR) of pituitary tumors, potentially resulting in a host of deficits due to the risk of hemorrhage, ischemia, or even death. The endoscopic endonasal approach (EEA) has gained considerable popularity in the modern era, with few busy neurosurgeons remaining committed to practicing transnasal pituitary microsurgery. Our objective was therefore to characterize the overall incidence of ICA injury in a large, longitudinal, single-surgeon microscopic TSR series conducted during the modern EEA era.

Methods Retrospective case series.

Results Overall TSR volume by the senior author (F.B.M.) was 817 pituitary tumors during the study period, 2002 to 2017. Within that cohort, two instances of ICA injury were identified (0.2%), including one each with Cushing's disease and acromegaly, both of whom ultimately recovered without residual neurologic deficit. No pediatric injuries were identified.

Conclusion Vascular injury is an exceedingly rare complication of transsphenoidal pituitary surgery. Adjuncts to prevent this complication include careful review of the coronal magnetic resonance imaging, identification of the midline, as needed use of the Doppler, and initial caudal opening of the sellar dura. Although potentially disastrous, good neurologic outcomes may be obtained, with immediate judicious packing followed by immediate digital subtraction angiography to assess vessel patency and secondary complications such as pseudoaneurysm.
Prospective Evaluation of Health-Related Quality of Life in Patients Undergoing Anterolateral Craniofacial Resection with Orbital Exenteration
Authors: Mukoyama Nobuaki , Nishio Naoki , Kimura Hiroyuki , Kishi Shinichi , Tokura Tatsuya , Kimura Hiroki , Hiramatsu Mariko , Maruo Takashi , Tsuzuki Hidenori , Fujii Masazumi , Iwami Kenichiro , Takanari Keisuke , Kamei Yuzuru , Ozaki Norio , Sone Michihiko , Fujimoto Yasushi
Published: July 2019

Objective This study was aimed to evaluate health-related quality of life in patients undergoing anterolateral craniofacial resection (AL-CFR) with orbital exenteration (OE) for malignant skull base tumors and to investigate the effects of early psychiatric intervention.

Design Present study is a prospective, observational study.

Setting The study took place at the hospital department.

Participants Twenty-six consecutive patients were selected who underwent AL-CFR with OE at our hospital between 2005 and 2015.

Main Outcome Measures Health-related quality of life was assessed preoperatively and 3, 6, 12, and 24 months after surgery using the Hospital Anxiety and Depression Scale (HADS) and medical outcomes study 8-items Short Form health survey (SF-8). In all cases, psychiatric intervention was organized by the consultation liaison psychiatry team preoperatively and postoperatively.

Results Ten (38.0%) of the 26 patients died and 16 (62.0%) were alive and disease-free at the end of the study. The 3-year overall and disease-free survival rates were 64.9% and 53.3%, respectively. Twenty-one patients (80.8%) developed psychiatric complications after surgery and needed treatment with psychotropic medication. Before surgery, 28% of patients had HADS scores ≥8 for anxiety and 20% had scores ≥8 for depression. Seven of the eight items in the SF-8 were significantly lower than those for the general Japanese population. However, scores for all the SF-8 items gradually improved during postoperative follow-up, reaching approximately 50 points, which is the national standard value, at 2 years after surgery.

Conclusions Craniofacial resection with OE was feasible and well tolerated in patients with malignant skull base tumors who received early psychiatric intervention to decrease the considerable psychological impact of this procedure.
A mechanism study on influence of strong external magnetic field on fracture properties of a ferromagnetic steel
Authors: Xie Zheng , He Manru , Xu Panpan , Li Qun , Pei Cuixiang , Xie Shejuan , Chen Zhenmao
Published: July 2019

For some ferromagnetic metallic materials, measurable influence of strong external magnetic field on their fracture properties has been observed experimentally, i.e., an external magnetic field of large intensity can promote the propagation of the crack. In order to clarify the mechanism of this phenomenon, a fracture model is put forward in this paper based on reversal magnetic domain theory and minimum free energy algorithm and verified through observations of magnetic domains structure. Compact tensile (CT) specimens which were stretched in strong magnetic field are adopted to observe their magnetic domains structure with the powder grain method in practice. It is found that the crack in the CT specimen propagated mainly along the magnetic domain wall rather than passing through the domain body. Together with the experimental results, the fracture model for the rupture and propagation mechanism under strong magnetic field was discussed.
One-dimensional surface phononic crystal ring resonator and its application in gas sensing
Authors: Kaya Olgun Adem , Korozlu Nurettin , Trak Digdem , Arslan Yasin , Cicek Ahmet
Published: July 2019

We introduce a ring resonator, which employs a one-dimensional phononic crystal on its inner surface, and investigate its performance as a gas sensor both numerically and experimentally. Having periodic equilateral trapezoidal protrusions, the ring resonator with 207 periods is optimized through band structure calculations via the finite-element method. A surface band linear around 58 kHz is observed. The resonator exhibits sharp transmission peaks with a broad free-spectral range of 0.54 kHz. Accordingly, a peak at 58.49 kHz with a high-quality factor of 8196 appears. Application in detection of the carbon dioxide level in air with high sensitivity is demonstrated. The 58.49 kHz peak red shifts linearly at 17.3 mHz/ppm and 17.8 mHz/ppm rates, as obtained from numerical calculations and experiments, respectively. Besides, the peak shape and maximum intensity are preserved. Due to the linear shift of the resonance peak with respect to the carbon dioxide concentration, acoustic intensity at initial peak frequency can be utilized as an auxiliary means for concentrations up to 1000 ppm. The proposed ring resonator can be adapted to a variety of acoustic devices such as liquid concentration sensors based on phononic crystals, surface acoustic wave sensors, and micromechanical resonators.
Three dimensional tracing of a charged particle by electrostatic detection
Authors: Genc Erdem , Mölleken Andre , Tarasevitch Doris , Utzat Detlef , Nienhaus Hermann , Möller Rolf
Published: July 2019

Using a configuration of electrodes connected to charge sensitive amplifiers, the position of a charged particle in free space can be determined in all three dimensions. In our experiment, spheres with a diameter of a millimeter and a charge of about 0.1 pC are traced while they are bouncing at a surface. A spatial resolution of about 0.5 mm combined with a temporal resolution better than 10 µs is achieved. Moreover, the transfer of electric charges when touching a surface can be evaluated.
Effects of reduced internal electric field in InGaN/pseudo-AlInGaN multi-quantum-well on forward leakage current and photocurrent properties
Authors: Park Byung-Guon , Maddaka Reddeppa , Nguyen Thi Kim Phung , Peta Koteswara Rao , Noh Young-Kyun , Oh Jae-Eung , Kim Moon-Deock
Published: July 2019

The main focus of this work is to find the effects of the internal electric field on the forward leakage current and photocurrent of an InGaN/pseudo-AlInGaN multi-quantum-well (MQW) grown on sapphire substrate using metalorganic chemical vapor deposition. The temperature dependent current-voltage characteristics of an InGaN MQW with and without an AlInGaN barrier (sample A = GaN barrier, sample B = Al0.043In0.036Ga0.921N barrier, sample C = Al0.043In0.052Ga0.905N) exhibit two linearly dependent divisions with different slopes at low (1.0 ≤ V ≤ 1.4) and medium (1.6 ≤ V ≤ 2.5) bias regions in the 250–300 K range. The temperature-insensitive behavior of the characteristic energy and large ideality factors mean that tunneling is the dominant process in the three samples. Distinct tunneling entities at low and medium biases are observed for samples A and B; however, for sample C, thermionic emission gain dominance in the medium bias range. The peculiar behavior in sample C is attributed to suppressed hole-tunneling currents caused by a low internal electric field. Photocurrent experiments using a xenon lamp demonstrate that sample C exhibit higher photocurrent characteristics and that the enhanced photocurrent is due to a reduced internal electric field. The low internal electric field generates a large amount of photo-excited carriers, which cross the potential of QW effectively compared to the conventional GaN barrier.
Combining particle-in-cell and direct simulation Monte Carlo for the simulation of reactive plasma flows
Authors: Fasoulas S. , Munz C.-D. , Pfeiffer M. , Beyer J. , Binder T. , Copplestone S. , Mirza A. , Nizenkov P. , Ortwein P. , Reschke W.
Published: July 2019

A combined approach for the simulation of reactive, neutral, partially or fully ionized plasma flows is presented. This is realized in a code framework named “PICLas” for the approximate solution of the Boltzmann equation by particle based methods. PICLas combines the particle-in-cell method for the collisionless Vlasov–Maxwell system and the direct simulation Monte Carlo method for neutral reactive flows. Basic physical and mathematical modeling of both methods is addressed, and some application examples are presented in order to demonstrate the capabilities and the broad applicability of the solution strategy.
Aspect ratio dependence of Rayleigh-Bénard convection of cold water near its maximum density in box-shaped containers
Authors: Huang Xiao-Jie , Hu Yu-Peng , Li You-Rong
Published: July 2019

The aim of this research is to understand the effect of the aspect ratio on the heat transfer ability and hydrodynamics characteristics of Rayleigh-Bénard convection of cold water near its maximum density in box-shaped containers. The Rayleigh number is fixed at 109, density inversion parameters are 0.3, 0.5 and 0.7, and the aspect ratio ranges from 1/60 to 1. Results indicate that the average Nusselt number presents a weak dependence on the aspect ratio at the large aspect ratio (A > 0.3). However, it reaches the maximum and then drops when the aspect ratio decreases from A = 0.3. Large scale circulations are observed for containers at the large aspect ratio, and the confinement of sidewalls weakens the large-scale circulation and eventually destructs it. At the large aspect ratio, the velocity fluctuation near the sidewalls is stronger than that in the center zone, because plumes primarily move along the sidewalls of the container. At a small aspect ratio, more plumes appear in the center of the container, where the fluctuation is stronger than that near sidewalls. The effect of cold plumes on the flow is reduced as the density inversion parameter increases. Therefore, the flow is mainly driven by hot plumes, and the velocity magnitude and fluctuation decrease significantly.
Stream broadening due to fluid shear across the wider transverse dimension of a free-flow zone electrophoresis channel
Authors: Dutta Debashis
Published: July 2019

While the pressure-gradient applied along the length of a free-flow zone electrophoresis (FFZE) chamber is known to produce a parabolic flow profile for the carrier electrolyte across the narrower channel dimension (typically the channel depth), additional fluid shear can arise across the channel width due to a variety of reasons. Most commonly, any variation in the pressure-drop or channel depth across this wider dimension can lead to a gradient in the liquid flow velocity along it, significantly altering the stream broadening and, thereby, the separation performance of the assay. This article assesses the effect of such fluid shear on stream broadening during the FFZE process by describing a mathematical framework for solving the relevant advection-diffusion equation based on the method-of-moments approach. A closed-form expression for the leading order term describing the additional contribution to the spatial stream variance has been derived considering a small linear gradient in the liquid velocity across the wider transverse dimension of the FFZE chamber. The noted analysis predicts this contribution to be governed by two Péclet numbers that are evaluated based on the axial pressure-driven flow and transverse electrophoretic solute velocities. More importantly, this contribution is shown to vary quadratically with the axial distance traversed by the analyte stream as opposed to the classical linear variation known for all other stream broadening contributions in FFZE systems. The results from the analytic theory have been validated with Monte Carlo simulations, which also establish a time and length scale over which the noted analytical results are applicable.
The coherent heteroepitaxy of high-index Bi2Se3 thin film on nanofaceted Si(211) substrate
Authors: Li Handong , Yu Shupeng , Li Yong , Channa Ali Imran , Ji Haining , Wu Jiang , Niu Xiaobin , Wang Zhiming
Published: July 2019

In this paper, high-index Bi2Se3(2045) films are achieved on a Bi-modified Si(211) substrate with corrugated surface morphologies composed of striplike 19.5° tilted (001) facets by molecular beam epitaxy. The chemical bonds between Bi2Se3(001) faces and Bi-absorbed nanoscale faceted (111) terraces on Si(211) surfaces provide solid lattice constraints which favor the coherent epitaxy of Bi2Se3 films on the Bi-modified Si(211) substrate as compared to the H-passivated Si(211) substrate. This makes Bi2Se3(2045) grown on Bi-modified Si(211) more suitable for device applications. Temperature-dependent I-V measurements of the Bi2Se3(2045)/Si(211) heterojunction are performed which yield a Schottky barrier height of ФB = 0.22 eV at the heterointerface.
Aerodynamic interaction of collective plates in side-by-side arrangement
Authors: Kim Dongwook , Lee Seung Hun , Kim Daegyoum
Published: July 2019

In the tip-reversal upstroke of avian flight, individual feathers twist so as to create gaps between them. Although this behavior allows the feathers to function as individual lift-generating bodies, the lift generation mechanism of these multiple bodies remains unclear. This paper reports a numerical investigation of multiple stationary plates arranged side by side in a uniform flow. The aim is to elucidate the collective mechanism of the flow generated by the plates and the lift contribution of each plate. The angle of attack of each plate and the gap between the plates are varied to determine their influence on the flow and lift of the collection of plates. The time-averaged lift increases from the lowermost to the uppermost plate, and, at a high angle of attack, the total lift coefficient of the plates becomes greater than that of a single plate solely placed in a uniform flow. At a high angle of attack, vortex shedding from the upper plates is synchronized with some phase difference, resulting in synchronized lift fluctuations for individual plates and a reduction in the overall fluctuation amplitude. With an optimal gap ratio and angle of attack, the collective behavior of plates in side-by-side arrangement can be advantageous to enhance lift-generation performance.
Terahertz field depolarization and absorption within composite media
Authors: Bergen Mark H. , Reich Jason , Ho Tyler , Clark Flynn , Reid Matthew , Holzman Jonathan F.
Published: July 2019

In this work, we pursue a deeper understanding of the expression of the inclusion morphology and index contrast in the refraction and absorption characteristics of composites within the terahertz (THz) spectrum. The composites are composed of SiO2 and Si nanoparticles as well as SiO2 and Si microparticles functioning as deeply subwavelength inclusions in a polydimethylsiloxane (PDMS) host. Terahertz time-domain spectroscopy is used for experimental characterization of the composites over a wide range of volumetric fractions, and the trends that emerge are contrasted to theoretical predictions from the Bruggeman model. It is found that the refraction characteristics have a heightened dependence on the inclusions' shape when their index contrast with respect to the host becomes sufficiently large. We attribute such a correlation to terahertz field depolarization that occurs within inclusions at high index contrasts and the dependence of the fields to the inclusions' shape—as defined by a depolarization factor in the generalized form of the Bruggeman model. Moreover, it is found that the absorption characteristics have a heightened dependence on the inclusions' size when that size becomes sufficiently small. We attribute this to the manifold of surface states that form in small inclusions, due to their high surface-to-volume ratio, which raises the absorption beyond that of the bulk. It is concluded that the Bruggeman model can accurately characterize the refraction and absorption of THz radiation within composites having deeply subwavelength inclusions if their (shape-dependent) polarization and (size-dependent) absorption are suitably defined.
Study and analysis the Cu nanoparticle assisted texturization forming low reflective silicon surface for solar cell application
Authors: Basher M. K. , Mishan R. , Biswas S. , Khalid Hossain M. , Akand M. A. R. , Matin M. A.
Published: July 2019

Monocrystalline silicon solar cells with photo-absorbing morphology can amplify light-trapping properties within the absorber layer and help to fabricate cost-effective solar cells. In this paper, the effect of different parameters namely temperature and time of Cu-assisted chemical etching was thoroughly investigated for the optimization of the light absorption properties. P-type monocrystalline wafers were selectively treated with Cu(NO3)2.3H2O:HF:H2O2:DI water solution at 50 °C for five different time duration. The entire process was repeated at five different temperatures for 20min as well to study the relation between etching temperature and surface reflectance. Sonication bathing was used for the removal of the deposited Cu atoms from the surface with the variation of time and the effect was examined using energy dispersive spectroscopy (EDS). Field emission scanning electron microscopy (FESEM) and UV/VIS spectroscopy were conducted to study the surface morphology and light absorbance respectively. Inverted shapes almost similar to inverted pyramids or porous surface were found randomly on the surface of the wafer. The effect of temperature was found more significant compared to the effect of time variation. An optimum light reflectance was found at 50 °C for 20 min of texturization. Atomic force microscopy (AFM) of the textured sample revealed the average depth of pyramidal shape was about 1.58 μm. EDS results showed a proportional relation between time and Cu removal process, and a complete Cu atoms free textured surface after 25 min of sonication bathing. Therefore, a suitable Cu-assisted texturization technique was found, which could enable lowering the photo-reflectance below 1% without any antireflection coating.
Hole-doped M4SiTe4 (M = Ta, Nb) as an efficient p-type thermoelectric material for low-temperature applications
Authors: Okamoto Yoshihiko , Yoshikawa Yuma , Wada Taichi , Takenaka Koshi
Published: July 2019

Solid-state thermoelectric cooling is expected to be widely used in various cryogenic applications such as local cooling of superconducting devices. At present, however, thermoelectric cooling using p- and n-type Bi2Te3-based materials has been put to practical use only at room temperature. Recently, M4SiTe4 (M = Ta, Nb) has been found to show excellent n-type thermoelectric properties down to 50 K. This paper reports on the synthesis of high-performance p-type M4SiTe4 by Ti doping, which can be combined with n-type M4SiTe4 in a cooling device at low temperatures. The thermoelectric power factor of p-type M4SiTe4 reaches a maximum value of approximately 60 μW cm−1 K−2 at 210 K and exceeds the practical level in a wide temperature range of 130–270 K. A finite temperature drop by Peltier cooling was also achieved in a cooling device made of p- and n-type Ta4SiTe4 whisker crystals. These results clearly indicate that M4SiTe4 is promising to realize a practical thermoelectric cooler for use at low temperatures, which is not covered by Bi2Te3-based materials.
GHz sampling hardware implementation with sub-Nyquist coprime sampling rates
Authors: Wen Weifeng , Yan Haoyue , Zhao Yijiu , Liu Dan , He Hui
Published: July 2019

A sub-Nyquist coprime sampling system for sparse signals is implemented in this article. The proposed system is composed of coprime sampling hardware and a multicoset signal reconstruction algorithm. A pair of uniform samplers is utilized in the hardware to sample a wideband spare analog signal with an uncertain difference in start times. A time difference acquisition module embedded into a field-programmable gate array and a pulse-expanding circuit are then used to measure the difference in start times. Owing to the different frequencies of the two samplers, the coprime sample sets obtained are nonuniform. Before they are used as input to the multicoset signal reconstruction algorithm, these coprime sample sets need to be regrouped into multicoset sample sets according to the sample pattern. The results of experiments indicate that the signals can be reconstructed at an equivalent rate of the order of gigahertz from sub-Nyquist samples acquired by the designed coprime acquisition system.
On the onset of convection in a highly permeable vertical porous layer with open boundaries
Authors: Barletta A. , Rees D. A. S.
Published: July 2019

The unstable nature of buoyant flow in a vertical porous slab with a pure conduction temperature distribution is investigated. The permeable and isothermal boundaries are subject to a temperature difference, which is responsible for the basic stationary and parallel vertical flow in the slab. The momentum transfer is modeled by adopting the Darcy–Forchheimer law, thus including the quadratic form-drag contribution. The instability to small-amplitude perturbations is tested by parameterizing the basic stationary flow through the Darcy–Rayleigh number and the form-drag number. The modal analysis is carried out numerically with a pressure–temperature formulation of the governing equations for the perturbations. The neutral stability curves and the critical values of the wave number and of the Darcy–Rayleigh number are obtained for different prescribed values of the form-drag number.
Construction of the interface potential from a series of canonical ensemble simulations
Authors: Jain Karnesh , Schultz Andrew J. , Errington Jeffrey R.
Published: July 2019

We introduce a method to construct the interface potential from a series of molecular dynamics simulations conducted within the canonical ensemble. The interface potential provides the surface excess free energy associated with the growth of a fluid film from a surface. We collect the force that the fluid exerts on the surface (disjoining pressure) at a series of film thicknesses. These force data are then integrated to obtain the interface potential. “Spreading” and “drying” versions of the general approach are considered. The spreading approach focuses on the growth of a thin liquid film from a solid substrate in a mother vapor. The drying approach focuses on the growth of a thin vapor film on a solid substrate in a mother liquid. The methods provide a means to compute the contact angle of a fluid droplet in contact with the surface. The general method is applied to two model systems: (1) a monatomic Lennard-Jones fluid in contact with atomistically detailed face centered cubic (FCC) substrate and (2) TIP4P/2005 water in contact with a rigid silica surface. For the Lennard-Jones model system, we generate results with both the drying and spreading methods at various temperatures and substrate strengths. These results are compared to those from previous simulation studies. For the water system, the drying method is used to obtain wetting properties over a range of temperatures. The water system also highlights challenges associated with application of the spreading method within the framework pursued here.
MeV photoelectron spectrometer for ultraintense laser interactions with atoms and molecules
Authors: Luo S. Y. , Grugan P. D. , Demircioglu Z. , Hoos A. , Germain Z. , McIntyre R. A. , Shen Xingyu , Ji Yi , Walker B. C.
Published: July 2019

Traditional laser-matter spectroscopy techniques fail to accurately analyze photoelectrons and ions from ultrahigh intensity studies with terawatt and petawatt laser systems. We present a magnetic deflection, photoelectron spectrometer for ultrahigh intensity laser interactions with atoms and molecules in the single atom/molecule limit. Spectrometer fabrication and calibration, and noise background are presented as well as example photoelectron spectra for argon and chloromethane over an energy range from 20 keV to 2 MeV.
Review of Scientific Instruments New Products
Authors: Mandelis Andreas
Published: July 2019

In order to supplement manufacturers’ information, this department will welcome the submission by our readers of brief communications reporting measurements on the physical properties of materials which supersede earlier data or suggest new research applications.
An MeV spectrometer for photoelectrons generated by ultrahigh intensity lasers
Authors: Dooley Phil
Published: July 2019

A new tool for measuring high-energy electrons will enable closer study of interactions of ultrahigh energy lasers with matter and reveal secrets of the relativistic regime.
Homotypic cooperativity and collective binding are determinants of bHLH specificity and function
Authors: Shively Christian A. , Liu Jiayue , Chen Xuhua , Loell Kaiser , Mitra Robi D.
Published: July 2019

Eukaryotic cells express transcription factor (TF) paralogues that bind to nearly identical DNA sequences in vitro but bind at different genomic loci and perform different functions in vivo. Predicting how 2 paralogous TFs bind in vivo using DNA sequence alone is an important open problem. Here, we analyzed 2 yeast bHLH TFs, Cbf1p and Tye7p, which have highly similar binding preferences in vitro, yet bind at almost completely nonoverlapping target loci in vivo. We dissected the determinants of specificity for these 2 proteins by making a number of chimeric TFs in which we swapped different domains of Cbf1p and Tye7p and determined the effects on in vivo binding and cellular function. From these experiments, we learned that the Cbf1p dimer achieves its specificity by binding cooperatively with other Cbf1p dimers bound nearby. In contrast, we found that Tye7p achieves its specificity by binding cooperatively with 3 other DNA-binding proteins, Gcr1p, Gcr2p, and Rap1p. Remarkably, most promoters (63%) that are bound by Tye7p do not contain a consensus Tye7p binding site. Using this information, we were able to build simple models to accurately discriminate bound and unbound genomic loci for both Cbf1p and Tye7p. We then successfully reprogrammed the human bHLH NPAS2 to bind Cbf1p in vivo targets and a Tye7p target intergenic region to be bound by Cbf1p. These results demonstrate that the genome-wide binding targets of paralogous TFs can be discriminated using sequence information, and provide lessons about TF specificity that can be applied across the phylogenetic tree.
Assembling multidomain protein structures through analogous global structural alignments
Authors: Zhou Xiaogen , Hu Jun , Zhang Chengxin , Zhang Guijun , Zhang Yang
Published: July 2019

Significance

More than 80% of eukaryotic proteins and 67% of prokaryotic proteins contain multiple domains. Due to the technical difficulties in structural biology, however, 65.3% of solved proteins in the Protein Data Bank contain only single-domain structures. Similarly, most computational approaches are optimized for single-domain structure predictions. We propose a pipeline for assembling domain models into full-length structures with interdomain orientations constrained by an analogous structure alignment search. Large-scale benchmark tests showed an unprecedented ability of DEMO in modeling multidomain structures, with a success rate significantly beyond that of the state-of-the-art approaches built on linker modeling. This development helps bridge the significant gap between the increasingly improved ability of individual domain structure determination and the extremely high demands of community for multidomain structure models.
Mapping hole hopping escape routes in proteins
Authors: Teo Ruijie D. , Wang Ruobing , Smithwick Elizabeth R. , Migliore Agostino , Therien Michael J. , Beratan David N.
Published: July 2019

A recently proposed oxidative damage protection mechanism in proteins relies on hole hopping escape routes formed by redox-active amino acids. We present a computational tool to identify the dominant charge hopping pathways through these residues based on the mean residence times of the transferring charge along these hopping pathways. The residence times are estimated by combining a kinetic model with well-known rate expressions for the charge-transfer steps in the pathways. We identify the most rapid hole hopping escape routes in cytochrome P450 monooxygenase, cytochrome
c
peroxidase, and benzylsuccinate synthase (BSS). This theoretical analysis supports the existence of hole hopping chains as a mechanism capable of providing hole escape from protein catalytic sites on biologically relevant timescales. Furthermore, we find that pathways involving the [4Fe4S] cluster as the terminal hole acceptor in BSS are accessible on the millisecond timescale, suggesting a potential protective role of redox-active cofactors for preventing protein oxidative damage.
Rhetorical strategies in PhD conclusions of computer
science
Authors: Soler-Monreal Carmen
Published: July 2019

This study investigates the predominant moves and move patterns
used in the separate final conclusion chapters of 48 PhD theses of computer
science at a UK university. The focus is on the most salient connections of
steps in the review of the study (Move 1) with steps for the consolidation
of research space (Move 2). The most common combinations relate (1) a
summary of the thesis work to the product and the evaluation of the product, (2)
the purpose, thesis statement or hypothesis to the findings or results, (3) the
research questions to the methodology, product or claim, (4) a problem or need
to a specific methodology, a new product and/or a claim, and (5) a summary of
the work done in each thesis chapter to the findings and claims. Some findings
are specific of the field of computer science. The study has pedagogical
implications for courses of English for Academic Purposes (EAP).
El papel del oyente en la adquisición de la competencia
conversacional en ELE
Authors: Pascual Escagedo Consuelo
Published: July 2019

En este artículo, proponemos una secuencia didáctica dirigida a
estudiantes italianos de nivel C1 centrada en el papel del oyente activo en la
conversación. Los estudios llevados a cabo hasta hoy en el campo de la
Lingüística Aplicada a la enseñanza de lenguas extranjeras y siguiendo los
presupuestos del Análisis de la Conversación, coinciden en que los estilos
conversacionales varían según las lenguas y las culturas. De la revisión
bibliográfica realizada se desprende que se hace necesaria la enseñanza
explícita de diferentes mecanismos conversacionales. Por ello, hemos diseñado
una propuesta didáctica, dividida en cuatro fases (presentación, práctica
controlada, práctica libre y evaluación de las prácticas), que pretende fomentar
la adquisición/aprendizaje de la competencia conversacional atendiendo al papel
del oyente en la interacción, basada en el estudio de las funciones de los
turnos de apoyo verbales.
The substituent effect on the excited state intramolecular proton transfer of 3-hydroxychromone*
Authors: Song Yuzhi , Liu Songsong , Lu Jiajun , Zhang Hui , Zhang Changzhe , Du Jun
Published: July 2019

The excited state intramolecular proton transfer of four derivatives (FM, BFM, BFBC, CCM) of 3-hydroxychromone is investigated. The geometries of different substituents are optimized to study the substituent effects on proton transfer. The mechanism of hydrogen bond enhancement is qualitatively elucidated by comparing the infrared spectra, the reduced density gradient, and the frontier molecular orbitals. The calculated electronic spectra are consistent with the experimental results. To quantify the proton transfer, the potential energy curves (PECs) of the four derivatives in S0 and S1 states are scanned. It is concluded that the ability of proton transfer follows the order: FM

>

BFM

>

BFBC

>

CCM.
A new cellular automaton model accounting for stochasticity in traffic flow induced by heterogeneity in driving behavior*
Authors: Ni Xiaoyong , Huang Hong
Published: July 2019

A new reliable cellular automaon (CA) model designed to account for stochasticity in traffic flow induced by heterogeneity in driving behavior is presented. The proposed model differs from most existing CA models in that this new model focuses on describing traffic phenomena by coding into its rules the key idea that a vehicle’s moving state is directly determined by a driver stepping on the accelerator or on the brake (the vehicle’s acceleration). Acceleration obeys a deformed continuous distribution function when considering the heterogeneity in driving behavior and the safe distance, rather than equaling a fixed acceleration value with a probability, as is the rule in many existing CA models. Simulation results show that the new proposed model is capable of reproducing empirical findings in real traffic system. Moreover, this new model makes it possible to implement in-depth analysis of correlations between a vehicle’s state parameters.
Trajectory analysis of few-cycle strong field ionization in two-color circularly polarized fields*
Authors: Huang Yan , Qin Chaochao , Zhang Yizhu , Wang Xincheng , Yan Tian-Min , Jiang Yuhai
Published: July 2019

Bichromatic circularly polarized fields provide a useful tool to probe the ionization dynamics. In this work, we compare the photoelectron momentum distribution in few-cycle bichromatic field of different helicities. The spectral features are analyzed with semiclassical trajectories derived from the strong field approximation. In particular, the interference fringes in momentum distribution are investigated by tracking the ionization time and tunneling exits of released photoelectrons. Different types of trajectories that contribute to the interference fringes are elucidated.
Characteristics of urea under high pressure and high temperature*
Authors: Fang Shuai , Ma Hong-An , Guo Long-Suo , Chen Liang-Chao , Wang Yao , Ding Lu-Yao , Cai Zheng-Hao , Wang Jian , Jia Xiao-Peng
Published: July 2019

The properties of urea under high pressure and high temperature (HPHT) are studied using a China-type large volume cubic high-presentation apparatus (CHPA) (SPD-6 × 600). The samples are characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and Raman spectroscopy. By directly observing the macroscopic morphology of urea with SEM, it is confirmed that the melting point of urea rises with the increase of pressure. The XRD patterns of urea residues derived under different pressures show that the thermal stability of urea also increases with the increase of pressure. The XRD pattern of the urea residue confirms the presence of C3H5N5O (ammeline) in the residue. A new peak emerges at 21.80°, which is different from any peak of all urea pyrolysis products under normal pressure. A more pronounced peak appears at 708 cm−1 in the Raman spectrum, which is produced by C–H off-plane bending. It is determined that the urea will produce a new substance with a C–H bond under HPHT, and the assessment of this substance requires further experiments.
Influence of intraband motion on the interband excitation and high harmonic generation*
Authors: Zuo Rui-Xin , Song Xiao-Hong , Liu Xi-Wang , Yang Shi-Dong , Yang Wei-Feng
Published: July 2019

Tunnelling, acceleration, and collision of electrons are the basic events in the process of high harmonic generation (HHG) in strong-field interaction with atoms. However, the periodic array of atoms in semiconductor structure makes three steps become interatomic coherent process which leads to complicated carrier dynamics and two sources of high harmonic emission: interband polarization and intraband current. The difference of features of high harmonic generation between semiconductors and atoms is strongly linked to the unique presence of intraband motion which manifests itself a nontrivial role in intertwined two dynamics. Here, we review recent experimental and theoretical advances of understanding coupled interband and intraband mechanisms of HHG in semiconductors. Particularly we focus on the influence of intraband motion on the interband excitation, and on the subsequent HHG emission and attosecond pulse generation.
Dynamical properties of ultracold Bose atomic gases in one-dimensional optical lattices created by two schemes*
Authors: Zhu Jiang , Bian Cheng-Ling , Wang Hong-Chen
Published: July 2019

An optical lattice could be produced either by splitting an input light (splitting scheme) or by reflecting the input light by a mirror (retro-reflected scheme). We study quantum dynamical properties of an atomic Bose–Einstein condensate (BEC) in the two schemes. Adopting a mean field theory and neglecting collision interactions between atoms, we find that the momentum and spatial distributions of BEC are always symmetric in the splitting scheme which, however, are asymmetric in the retro-reflected scheme. The reason for this difference is due to the local field effect. Furthermore, we propose an effective method to avoid asymmetric diffraction.
Lattices in 𝑃𝑈(𝑛,1) that are not profinitely rigid
Authors: Stover Matthew
Published: July 2019

Using conjugation of Shimura varieties, we produce nonisomorphic, cocompact, torsion-free lattices in

PU
⁡
(
n
,
1
)

\operatorname {PU}(n,1)

with isomorphic profinite completions for all

n
≥
2

n \ge 2

. This disproves a conjecture of D. Kazhdan and gives the first examples of nonisomorphic lattices in a semisimple Lie group of real rank one with isomorphic profinite completions, answering two questions of A. Reid.
Level aspect of simultaneous nonvanishing for the central 𝐿-values associated to cusp forms
Authors: Kumar Balesh
Published: July 2019

In this article, we prove a quantitative result on simultaneous nonvanishing of central

L
L

-values twisted by quadratic characters for two holomorphic primitive forms with large prime level. We also extend a result of Kohnen to certain higher level forms.
On a convexity property of sections of the cross-polytope
Authors: Nayar Piotr , Tkocz Tomasz
Published: July 2019

We establish the log-concavity of the volume of central sections of dilations of the cross-polytope (the strong B-inequality for the cross-polytope and Lebesgue measure restricted to an arbitrary subspace).
Self-repair of the Lepidopteran Proboscis
Authors: Pometto Suellen F , Beard Charles E , Gerard Patrick D , Kornev Konstantin G , Adler Peter H
Published: July 2019

Self-repair in the animal world typically involves regeneration of body parts. We present an example featuring the proboscis of butterflies and moths, which after separation of the galeae, undergoes nonregenerative repair. We demonstrated the ability of representative species to completely reunite (repair) the proboscis after total separation of the two galeae, and we showed that the repaired proboscis can take up fluid. Movements of the proboscis during repair were similar to the initial proboscis assembly after emergence from the pupa. We tested the influence of labial palps, wing movements, coiling, and fluid immersion on self-repair. These factors showed no statistically significant influence on the ability to repair the proboscis, with the exception of wing movements in one species. We suggest that the major selection forces driving assembly and repair have been the need to insert the proboscis into restricted openings of floral tubes to obtain nectar and the need for a united, compactly coiled proboscis to reduce air resistance during flight.
Large Hind Wings Enhance Gliding Performance in Ground Effect in a Neotropical Butterfly (Lepidoptera: Nymphalidae)
Authors: Stylman Marc , Penz Carla M , DeVries Phil
Published: July 2019

Neotropical butterflies in the nymphalid genera Pierella Herrich-Schäffer, 1865 (Lepidoptera, Nymphalidae) and Cithaerias Hübner, 1819 (Lepidoptera, Nymphalidae) are known to glide near ground level, and have a high forewing aspect ratio. The hind wings of Pierella are proportionately larger than those of Cithaerias, suggesting a potential role in gliding flight. We show that Pierella helvina (Hewitson, 1860) (Lepidoptera, Nymphalidae) is capable of gliding for longer periods of time than Cithaerias pireta (Stoll, 1780) (Lepidoptera, Nymphalidae) both in the field and a laboratory setting. Experimental reduction of hind wing area in P. helvina led to a decrease in male gliding performance, and an increase in female wing-beat frequency. We also found that escape velocity decreased in both sexes after hind wing area reduction, but the effect was strongest in females. Although the increased drag associated with large hind wings could be detrimental to gliding flight, the large hind wing area of P. helvina effectively enhances gliding performance in ground effect. This study is the first to investigate the role of hind wings on butterfly gliding performance.