bluuebunny/crossref_metadata_2025 huggingface dataset:
Physical chemistry insights into surface charge phenomena during frictional coupling in triboelectric X-ray sources
Authors: Pezzotti Giuseppe , Camara Carlos , Marin Elia , Zhu Wenliang , Green Douglas , Collins Adam , Putterman Seth
Published: May 2019

This study delves into molecular-scale phenomena that govern the frictional coupling of triboelectric materials used in miniaturized X-ray sources.
Diagnostic value and safety of color doppler ultrasound-guided transthoracic core needle biopsy of thoracic disease
Authors: Huang Weina , Chen Libin , Xu Ning , Wang Linfeng , Liu Fang , He Shiyi , Lai Tianwen , Chen Xueqin
Published: May 2019

Objective: The aim of the present study was to explore the diagnostic value and safety of color Doppler ultrasound (US)-guided transthoracic core needle biopsy (CNB) of peripheral lung, chest wall and mediastinal lesions using automated biopsy guns.

Materials and methods: We analyzed clinical and image data, histopathologic and microbiologic details and complications from 121 patients with peripheral lung, chest wall and mediastinal lesions who underwent color Doppler US-guided transthoracic CNB in Ningbo First Hospital between January 2015 and June 2018.

Results: Color Doppler US-guided transthoracic CNB performed with a freehand technique using automated biopsy guns had a sensitivity of 93.94%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 78.57%, and a diagnostic accuracy of 95.04%. Lesion size did not affect the diagnostic rate (P=0.40). No serious complications of the procedure were noted.

Conclusion: Color Doppler US-guided transthoracic CNB of peripheral lung, chest wall and mediastinal lesions is a safe and inexpensive procedure. The diagnostic accuracy of color Doppler US-guided transthoracic CNB was higher than that of color Doppler US-guided transthoracic fine needle aspiration biopsy (FNAB).
Service‐dependent task offloading for multiuser mobile edge computing system
Authors: Ni Wanli , Tian Hui , Lyu Xinchen , Fan Shaoshuai
Published: May 2019

Mobile edge computing (MEC) has been deemed as one of the key technologies for pushing powerful computing ability to the radio access network. Different scenarios require different services, and tasks usually require computing in a specific runtime environment. However, few studies have taken this into consideration. To this end, the authors propose a novel model of service‐dependent task offloading for the multiuser MEC system with resource constraints. Through determining which services should be deployed at the network edge and how many tasks should be offloaded, a revenue maximisation problem is constructed. Accordingly, they propose an iterative optimisation algorithm with high performance for the service deploying and task offloading problem. Finally, numerical simulations reveal that their proposed algorithm outperforms other schemes.
High isolation diplexer using stub‐loaded resonators
Authors: Li Xuan‐Tan , Cheng Fei , Lu Ping , Huang Kama
Published: May 2019

This Letter reports a high isolation diplexer using stub‐loaded resonators (SLRs). Each SLR can generate one transmission pole and one transmission zero (TZ). By changing the length of the open stub, the frequency of the TZ can be adjusted. The upper channel filter using the capacitive coupled SLRs can have TZs above the passband, while the lower channel filter using inductive coupled SLRs can have TZs below the passband. With those TZs, the isolation of the diplexer is greatly improved. A high isolation diplexer is designed and fabricated to validate the design concept.
Initial frequency split reduction of MEMS ring gyroscope based on cascaded springs geometrical compensation
Authors: Bai Zesen , Cui Jian , Zhao Qiancheng , Yang Zhenchuan , Yan Guizhen
Published: May 2019

Small initial frequency split is preferred to reduce the complexity of control circuits and enhance the device sensitivity for mode‐matching MEMS gyroscopes. A microring gyroscope with cascaded rectangular beams as supporting springs fabricated by (100) single crystal silicon (SCS) is presented. Frequency split due to the anisotropic of Young's modulus of (100) SCS is geometrically compensated by adjusting the width of cascaded springs and adding an extra mass. The rectangular beams are designed to be wide enough to improve the immunity to fabrication imperfections, obtaining good manufacturing repeatability. The proposed method can largely attenuate the frequency difference of the gyroscope by using (100) SCS, which can reduce the processing cost and be easily integrated with CMOS circuit compared with (111) SCS. The test results show that the average initial frequency split of 15 different devices is 5.1 Hz for the ∼10,430 Hz resonant frequency. The minimum and maximum splits are 2.3 Hz (0.022%) and 7.3 Hz (0.069%), respectively, with the standard deviation of 1.3 Hz.
Sequence‐based differential evolution for solving economic dispatch considering virtual power plant
Authors: Yang Yude , Wei Bori , Qin Zhijun
Published: May 2019

The economic dispatch (ED) of distributed energy resources (DERs) is an important and challenging problem in smart grid operation. Different frameworks are proposed for solving this issue, among which the virtual power plant (VPP) is considered as a promising means for ED in smart grids with DERs. This study presents a novel optimisation algorithm entitled sequence‐based differential evolution (SDE) for solving generation dispatch among several DERs with VPPs. In the proposed method, a novel and efficient initialisation technique, namely sequence‐based deterministic initialisation, is used to generate high‐quality initial population. Besides, a self‐adaptation mechanism is utilised to eliminate the difficulty of tuning the problem‐specific control parameters of the algorithm. Subsequently, the SDE is applied for solving the ED model to obtain the optimal power generation share of the VPP. Case studies compare the solutions obtained by the proposed method with several state‐of‐the‐art algorithms in the existing literature. It is validated the proposed method is advantageous for ED with VPPs in better solution accuracy, less computational burden, and faster convergence.
Coordination of interdependent natural gas and electricity systems based on information gap decision theory
Authors: Sohrabi Farnaz , Jabari Farkhondeh , Mohammadi‐Ivatloo Behnam , Soroudi Alireza
Published: May 2019

The interactions of the natural gas (NG) network and the electricity system are increased by using gas‐fired generation units, which use NG to produce electricity. There are various uncertainty sources such as the forced outage of generating units or market price fluctuations that affect the economic operation of both NG and electricity systems. This study focuses on the steady‐state formulation of the integrated NG transmission grid and electricity system by considering the uncertainty of electricity market price based on information gap decision theory. The higher and lower costs than the expected cost originated from the fluctuations of electricity market price are modelled by the robustness and opportunity functions, respectively. The objective is to minimise the cost of zone one while satisfying the constraints of two interdependent systems, which can obtain revenue from selling power to its connected zones in short‐term scheduling. The capability of the proposed method is demonstrated by applying it on a 20‐node NG network and IEEE RTS 24‐bus. The proposed short‐term coordination between NG and electricity infrastructures is solved and discussed.
Markov chain‐based wind power time series modelling method considering the influence of the state duration on the state transition probability
Authors: Zhu Chenxi , Zhang Yan , Yan Zheng , Zhu Jinzhou
Published: May 2019

Due to the inherent uncertainties of wind power, its large‐scale integration strongly impacts the planning and operation of power systems. To investigate these impacts, a stochastic model is required to more accurately capture the wind power's characteristics. This study proposes an improved Markov chain (MC)‐based time series (TS) modelling method for the stochastic generation of synthetic wind power TS. First, a self‐adaptive state division strategy is proposed to objectively classify historical data into several typical states. This strategy combines a state optimisation clustering model with a random‐variable‐modelling‐oriented filter parameter optimisation method. Then, a three‐dimensional state transition probability matrix (STPM) is proposed and constructed to generate synthetic wind power state TS. In contrast to the previous STPMs, the proposed STPM can capture the changing pattern of the transition probability against the state duration. Finally, the fluctuation quantity and noise are separately and sequentially added to the generated state TS, as an improvement over previous fluctuation characteristic addition methods, to obtain the final synthetic wind power TS. The results show that the proposed method outperforms previous MC‐based TS modelling methods in reproducing historical characteristics, such as the transition and fluctuation characteristics, and does not increase the STPM construction algorithm's time complexity.
Testing gravity with galaxy-galaxy lensing and redshift-space distortions using CFHT-Stripe 82, CFHTLenS, and BOSS CMASS datasets
Authors: Jullo E. , de la Torre S. , Cousinou M.-C. , Escoffier S. , Giocoli C. , Metcalf R. B. , Comparat J. , Shan H.-Y. , Makler M. , Kneib J.-P. , Prada F. , Yepes G. , Gottlöber S.
Published: May 2019

The combination of galaxy-galaxy lensing (GGL) and redshift space distortion of galaxy clustering (RSD) is a privileged technique to test general relativity predictions and break degeneracies between the growth rate of structure parameterfand the amplitude of the linear power spectrumσ8. We performed a joint GGL and RSD analysis on 250 sq. deg using shape catalogues from CFHTLenS and CFHT-Stripe 82 and spectroscopic redshifts from the BOSS CMASS sample. We adjusted a model that includes non-linear biasing, RSD, and Alcock–Paczynski effects. We used an N-body simulation supplemented by an abundance matching prescription for CMASS galaxies to build a set of overlapping lensing and clustering mocks. Together with additional spectroscopic data, this helps us to quantify and correct several systematic errors, such as photometric redshifts. We findf(z = 0.57) = 0.95 ± 0.23,σ8(z = 0.57) = 0.55 ± 0.07 and Ωm = 0.31 ± 0.08, in agreement withPlanckcosmological results 2018. We also estimate the probe of gravityEG = 0.43 ± 0.10, in agreement with ΛCDM−GR predictions ofEG = 0.40. This analysis reveals that RSD efficiently decreases the GGL uncertainty on Ωmby a factor of 4 and by 30% onσ8. We make our mock catalogues available on the Skies and Universe database.
Homogeneity of 67P/Churyumov-Gerasimenko as seen by CONSERT: implication on composition and formation
Authors: Herique A. , Kofman W. , Zine S. , Blum J. , Vincent J.-B. , Ciarletti V.
Published: May 2019

Context. After the landing of Philae, CONSERT probed the nucleus of 67P/Churyumov-Gerasimenko (67P) and observed no heterogeneities at metric scale within the probed part of the small lobe of 67P. Further studies have then quantified the observed homogeneity in terms of maximum permittivity contrast versus the typical size of heterogeneities.

Aims. The aim of this article is to interpret the sensitivity limits of CONSERT measurements in terms of composition, and to provide constraints on the maximum variability in composition, porosity, and local dust-to-ice ratio.

Methods. The sensitivity of CONSERT measurements to local variations in density, dust-to-ice ratio, and composition was analyzed using permittivity modeling of mixtures.

Results. We interpret the maximum detectable heterogeneity size and contrast in terms of composition and porosity of the nucleus. The sensitivity to porosity is ±10 percent points for heterogeneities with a characteristic length scale of a few meters; the sensitivity to local variations in the composition is limited.

Conclusions. In terms of accretion, our results are compatible only with scenarios generating porosity heterogeneities at scales lower than one meter, or with porosity variations smaller than ±10 percent points. This is clearly compatible with an accretion model of a gentle gravitational collapse of a pebble cloud.
Time-resolved GRB polarization with POLAR and GBM
Authors: Burgess J. M. , Kole M. , Berlato F. , Greiner J. , Vianello G. , Produit N. , Li Z. H. , Sun J. C.
Published: May 2019

Context. Simultaneousγ-ray measurements ofγ-ray burst spectra and polarization offer a unique way to determine the underlying emission mechanism(s) in these objects, as well as probing the particle acceleration mechanism(s) that lead to the observedγ-ray emission.

Aims. We examine the jointly observed data from POLAR andFermi-GBM of GRB 170114A to determine its spectral and polarization properties, and seek to understand the emission processes that generate these observations. We aim to develop an extensible and statistically sound framework for these types of measurements applicable to other instruments.

Methods. We leveraged the existing3MLanalysis framework to develop a new analysis pipeline for simultaneously modeling the spectral and polarization data. We derived the proper Poisson likelihood forγ-ray polarization measurements in the presence of background. The developed framework is publicly available for similar measurements with otherγ-ray polarimeters. The data are analyzed within a Bayesian probabilistic context and the spectral data from both instruments are simultaneously modeled with a physical, numerical synchrotron code.

Results. The spectral modeling of the data is consistent with a synchrotron photon model as has been found in a majority of similarly analyzed single-pulse gamma-ray bursts. The polarization results reveal a slight trend of growing polarization in time reaching values of ∼30% at the temporal peak of the emission. We also observed that the polarization angle evolves with time throughout the emission. These results suggest a synchrotron origin of the emission but further observations of many GRBs are required to verify these evolutionary trends. Furthermore, we encourage the development of time-resolved polarization models for the prompt emission of gamma-ray bursts as the current models are not predictive enough to enable a full modeling of our current data.
Formation of interstellar propanal and 1-propanol ice: a pathway involving solid-state CO hydrogenation
Authors: Qasim D. , Fedoseev G. , Chuang K.-J. , Taquet V. , Lamberts T. , He J. , Ioppolo S. , van Dishoeck E. F. , Linnartz H.
Published: May 2019

Context. 1-propanol (CH3CH2CH2OH) is a three carbon-bearing representative of the primary linear alcohols that may have its origin in the cold dark cores in interstellar space. To test this, we investigated in the laboratory whether 1-propanol ice can be formed along pathways possibly relevant to the prestellar core phase.

Aims. We aim to show in a two-step approach that 1-propanol can be formed through reaction steps that are expected to take place during the heavy CO freeze-out stage by adding C2H2 into the CO + H hydrogenation network via the formation of propanal (CH3CH2CHO) as an intermediate and its subsequent hydrogenation.

Methods. Temperature programmed desorption-quadrupole mass spectrometry (TPD-QMS) was used to identify the newly formed propanal and 1-propanol. Reflection absorption infrared spectroscopy (RAIRS) was used as a complementary diagnostic tool. The mechanisms that can contribute to the formation of solid-state propanal and 1-propanol, as well as other organic compounds, during the heavy CO freeze-out stage are constrained by both laboratory experiments and theoretical calculations.

Results. Here it is shown that recombination of HCO radicals formed upon CO hydrogenation with radicals formed via C2H2 processing – H2CCH and H3CCH2 – offers possible reaction pathways to solid-state propanal and 1-propanol formation. This extends the already important role of the CO hydrogenation chain to the formation of larger complex organic molecules. The results are compared with ALMA observations. The resulting 1-propanol:propanal ratio concludes an upper limit of <0.35−0.55, which is complemented by computationally derived activation barriers in addition to the experimental results.
High gas-to-dust size ratio indicating efficient radial drift in the mm-faint CX Tauri disk
Authors: Facchini S. , van Dishoeck E. F. , Manara C. F. , Tazzari M. , Maud L. , Cazzoletti P. , Rosotti G. , van der Marel N. , Pinilla P. , Clarke C. J.
Published: May 2019

The large majority of protoplanetary disks have very compact continuum emission (≲15 AU) at millimeter wavelengths. However, high angular resolution observations that resolve these small disks are still lacking, due to their intrinsically fainter emission compared with large bright disks. In this Letter we present 1.3 mm ALMA data of the faint disk (∼10 mJy) orbiting the TTauri star CX Tau at a resolution of ∼40 mas, ∼5 AU in diameter. The millimeter dust disk is compact, with a 68% enclosing flux radius of 14 AU, and the intensity profile exhibits a sharp drop between 10 and 20 AU, and a shallow tail between 20 and 40 AU. No clear signatures of substructure in the dust continuum are observed, down to the same sensitivity level of the DSHARP large program. However, the angular resolution does not allow us to detect substructures on the scale of the disk aspect ratio in the inner regions. The radial intensity profile closely resembles the inner regions of more extended disks imaged at the same resolution in DSHARP, but with no rings present in the outer disk. No inner cavity is detected, even though the disk has been classified as a transition disk from the spectral energy distribution in the near-infrared. The emission of 12CO is much more extended, with a 68% enclosing flux radius of 75 AU. The large difference of the millimeter dust and gas extents (> 5) strongly points to radial drift, and closely matches the predictions of theoretical models.
Sea cucumber fishing pattern and the socio-economic characteristics of fisher communities in Sri Lanka
Authors: Nishanthan Ganeshan , Kumara Ajith , Prasada Pahan , Dissanayake Chamari
Published: May 2019

Sea cucumber fishing pattern and the social and economic characteristics of sea cucumber fisher communities in the north, north-west and north-east regions of Sri Lanka were assessed using the data collected from November 2015 to January 2017. A total of 9 sea cucumber species is landed in these areas using three fishing methods; diving (SCUBA and breath-hold), gleaning and surrounding nets. SCUBA diving is the dominant fishing method and SCUBA divers do both day and night fishing reporting the highest catch rates (CPUE ± SD in numbers/person/day) than the other fishers (p < 0.05; ANOVA). Gleaning is entirely carried out by fisherwomen in the northern region whereas 28 surrounding nets are used targeting low-value Stichopus naso. CPUE found to be varied with respect to species, region and fishing method (p < 0.05; ANOVA). Bohadschia vitiensis made the highest percentage contribution (61.3%) to the total sea cucumber landings during the study period. Among all fishers, SCUBA divers reported the highest average net monthly income. Men play a dominant role in sea cucumber fishing (98%), processing (99%) and marketing (100%). Fishermen in the age range of 25–67 yr, having only primary education mainly involved in the sea cucumber industry. The sea cucumber value chain consists of fishers (∼2000), middlemen (12), processors (16) and exporters (7). A significant increase in overall price development from fishers to the exporters was reported for all 9 species (p < 0.05; ANOVA). Fishers received a proportionally higher share of the end-market price mainly for low-value Bohadschia spp. Although fishers receive disproportionately low returns compared to other value chain players, 47.8% of fishers showed high satisfaction towards the prices they received from buyers. However, 83.6% of fishers are not satisfied with existing management measures. Apart from strengthening the existing management measures, this information is important to update the regional and global sea cucumber statistics.
Effects of mixing intensity on colony size and growth ofMicrocystis aeruginosa
Authors: Chunni Zhong , Guijun Yang , Boqiang Qin , Wilhelm Steven W. , Yu Liu , Lihua Han , Zheng Rui , Hongwei Yang , Zhou Zhang
Published: May 2019

Mixing is an integral environmental factor that affects lake ecosystems. For the cyanobacteriumMicrocystis, colony size is important with respects to migration velocity, how cells respond to grazing pressure, light attenuation, nutrient uptake and growth. To understand how mixing shapes colony size and the growth ofMicrocystis, we measured the effects of different current velocities (0, 0.16, 0.32, 0.64, and 1.28 m s−1) onM. aeruginosain Lake Taihu. After 24 h of continuous mixing, the mean colony sizes ofM. aeruginosain the controls, 0.16, 0.32, 0.64, and 1.28 m s−1groups were 23.6, 50.1, 92.9, 67.8, and 37.3 μm, respectively. Colony sizes ofM. aeruginosain all treatment groups were significantly larger than those in controls. As well, the concentration of soluble extracellular polysaccharide and bound extracellular polysaccharides ofM. aeruginosain all treatment groups were significantly higher than those in controls. Except for the highest level of mixing (1.28 m s−1), the growth rate ofM. aeruginosawas significantly higher than that in controls. This study suggested that mixing intensity over short time periods can significantly influence colony size and the growth ofM. aeruginosa.
Osteoporosetherapie unter Beachtung der Komorbiditäten des Alters
Authors: Schober Hans-Christof , Hesse Kathrin
Published: May 2019

Ältere Patienten mit chronischen Erkrankungen erhalten zu häufig keine adäquate und differenzierte Therapie ihrer Osteoporose. Dabei sollte gerade diesen Patienten eine besondere Aufmerksamkeit zukommen, da deren chronische Erkrankungen wie Herz- und Niereninsuffizienz und Diabetes mellitus Typ II den Knochenstoffwechsel negativ beeinflussen und die Frakturrate signifikant erhöhen. Daher ist es unerlässlich, vor Therapieeinleitung eine gezielte laborchemische Untersuchung durchzuführen, um den gestörten Knochenstoffwechsels zu beurteilen und geeignete Therapieformen abzuleiten. Eine interdisziplinäre Behandlung ist angezeigt.
Langzeitsicherheit von Bisphosphonaten
Authors: Gasser Rudolf Wolfgang
Published: May 2019

Bisphosphonate sind derzeit die am häufigsten verwendeten Medikamente bei metabolischen Knochenerkrankungen, insbesondere bei Osteoporose, die Wirksamkeit ist durch Studien gut belegt. Bisphosphonate führen bei Osteoporose zu einer Reduktion des Knochenmineralverlusts und zu einer Senkung des Frakturrisikos. Neben den bekannten Kurzzeit-Nebenwirkungen wurden bei einer Langzeittherapie mit Bisphosphonaten potentielle Sicherheitsrisiken und Nebenwirkungen festgestellt. Zu diesen sehr seltenen Langzeitnebenwirkungen zählen: Kieferosteonekrose, atypische Femurfraktur, Muskel- und Skelettschmerzen, Vorhofflimmern und Ösophaguskarzinom. Dabei ergab sich teilweise keine eindeutige Kausalität aber eine Evidenz für ein vermehrtes, wenn auch sehr seltenes Auftreten. Eine Awareness gegenüber diesen Nebenwirkungen ist jedoch erforderlich. Bei leitliniengerechter Indikationsstellung und adäquater Prophylaxe, z. B. im Falle einer möglichen Kiefernekrose, überwiegen bei den meisten Patienten die Vorteile einer Bisphosphonattherapie gegenüber den möglichen Risiken. Unter Berücksichtigung des individuellen Frakturrisikos ist nach 3–5 Jahren Behandlung eine Therapiepause (drug holiday ) möglich, um die Gefahr von Nebenwirkungen zu reduzieren.
Nicht kleinzelliges Bronchialkarzinom
Authors: Krome Susanne
Published: May 2019

Patienten mit einem nicht kleinzelligen Bronchialkarzinom (NSCLC) und EGFR-Mutation profitieren von Tyrosinkinaseinhibitoren (TKI), aber nicht alle. Eine aktuelle retrospektive Studie zeigt den Zusammenhang von Behandlungseffektivität und Immunphänotyp: Eine starke PD-L1-Expression war dabei mit einem kürzeren progressionsfreien Überleben und De-novo-Resistenzen assoziiert.
ASCO-GI 2019: Leberzellkarzinom
Authors: Schmale Ine
Published: May 2019

Erhöhte α-Fetoprotein (AFP)-Spiegel sind bei HCC-Patienten mit einer schlechten Prognose assoziiert. Vice versa gibt es Hinweise darauf, dass ein AFP-Ansprechen mit einem längeren Gesamtüberleben korreliert. Anhand der Daten der Phase-III-Studie REACH-2 mit Ramucirumab in der Zweitlinientherapie wurde AFP als Surrogat für das Gesamtüberleben (OS) untersucht.
ASCO-GI 2019: Pankreaskarzinom
Authors: Schmale Ine
Published: May 2019

Während bei vielen Tumorentitäten große Fortschritte in der Behandlung zu berichten sind, bleibt das Pankreaskarzinom ein Tumor mit einer schlechten Prognose und wenigen Therapieoptionen. Beim Gastrointestinal Cancers Symposium (ASCO­GI) wurde eine Sitzung der frühen Detektion, der Sequenztherapie resektabler Tumoren und den Therapien der Zukunft beim Pankreaskarzinom gewidmet.
Malignes Melanom
Authors: Warpakowski Andrea
Published: May 2019

Anfang des Jahres wurde der PD-1-Inihibitor Pembrolizumab (Keytruda®) erstmals auch als adjuvante Therapie zugelassen. Seitdem können Melanom-Patienten im Stadium III mit Lymphknotenbeteiligung nach einer vollständigen Resektion diese immunonkologische Therapie erhalten. Diese Zulassung basiert auf der place-bokontrollierten, doppelblinden Phase-III-Studie EORTEC1325/KEYNOTE- 054, in der Pembrolizumab gegenüber Placebo ein signifikant verlängertes rezidivfreies Überleben erzielte.
ASCO-GU 2019: Fortgeschrittenes Nierenzellkarzinom
Authors: Schmale Ine
Published: May 2019

Das Armamentarium zur Behandlung des Nierenzellkarzinoms (RCC) hat sich um effektive Therapien erweitert, durch die der Therapiealgorithmus komplett umgestellt werden musste. Prof. Michael B. Atkins vom Georgetown-Lombardi Comprehensive Cancer Center, Washington DC/USA, und Prof. Daniel Y. C. Heng vom Tom Baker Cancer Center, Calgary/Kanada, teilten beim ASCO-GU ihre Einschätzung zur optimalen Behandlung des Nierenzellkarzinoms in der Erst- und Zweitlinientherapie für das Jahr 2019.
The impact of cathode surface roughness and multiple breakdown events on microscale gas breakdown at atmospheric pressure
Authors: Brayfield Russell S. , Fairbanks Andrew J. , Loveless Amanda M. , Gao Shengjie , Dhanabal Agni , Li Weihang , Darr Caleb , Wu Wenzhuo , Garner Allen L.
Published: May 2019

Gas breakdown is typically driven by Townsend avalanche and predicted mathematically by Paschen’s law (PL). Gas breakdown deviates from PL at microscale due to field emission, which depends critically on electrode condition; however, understanding of the impact of initial electrode surface roughness and multiple breakdown events on breakdown voltage is incomplete. This paper assesses the variation of breakdown voltage for a pin-to-plate electrode setup in air at atmospheric pressure for gap distances of 1 ± 0.5 μm, 5 ± 0.5 μm, and 10 ± 0.5 μm with different surface roughnesses. Breakdown voltage generally increases with increasing gap distance and decreasing surface roughness for a single breakdown event; however, the breakdown voltage after ten breakdown events does not depend on initial gap distance. Atomic force microscopy and optical microscopy show that multiple discharges create circular craters on the flat cathode up to 40 μm deep, with more pronounced craters created at smaller gap sizes and greater cathode surface roughness. The resulting effective gap distances (deff, the sum of cathode placement distance and crater depth) for subsequent breakdown events are similar to those of the initially larger gap distances. Moreover, deff becomes sufficiently large to exceed the Meek criterion for streamer formation, indicating a potential for breakdown mechanisms to change from field emission to Townsend avalanche to streamer formation for a single electrode separation distance. The resulting impact of this change in the breakdown mechanism could have significant implications for ensuring consistent microdevice operation.
Phonons and anisotropic thermal expansion behavior of NiX (X = S, Se, Te)
Authors: Goel Prabhatasree , Gupta M. K. , Mishra S. K. , Singh Baltej , Mittal R. , Sastry P. U. , Thamizhavel A. , Chaplot S. L.
Published: May 2019

Metal chalcogenides have been known for their important technological applications and have attracted continuous interest for their structural, electronic, thermal, and transport properties. Here, we present first-principles calculations of the vibrational and thermodynamic properties of NiX (X = S, Se, Te) compounds along with inelastic neutron scattering measurements of the phonon spectrum in NiSe. The measured phonon spectrum is in very good agreement with the computed result. We also report the measurement of thermal expansion behavior of NiSe using X-ray diffraction from 13 K to 300 K. The change in the hexagonal c lattice parameter in NiSe is considerably greater as compared to that in the a-parameter. The ab initio calculated anisotropic Grüneisen parameters of the different phonon modes in all the chalcogenides along with the elastic constants are used to compute anisotropic thermal expansion behavior, which is found in good agreement with experiments. The displacement pattern of phonons indicates that the difference in the amplitudes of Ni and X atoms follows the anisotropy of thermal expansion behavior along c- and a-axes.
Current-controlled negative differential resistance in small-polaron hopping system
Authors: Wu Jing , Hu Tao , Yin Yiming , Li Jingbo , Zhou Wei , Gao Yanqing , Jiang Lin , Huang Zhiming , Chu Junhao
Published: May 2019

Current-controlled negative differential resistance (CC-NDR) phenomenon attracts a lot of interest for fabricating the access devices of nonvolatile memory based on crossbar array architectures. However, simple, bipolar, two-terminal commercial devices that exhibit CC-NDR are currently lacking because a number of critical characteristics needed to be met for such application. Here, we report the CC-NDR observed in Mn1.56Co0.96Ni0.48O4 (MCNO)- a small-polaron hopping material. Our experimental data and simulation reveal that the CC-NDR arises from self-heating effect due to the nature of strong electron-phonon coupling in small-polaron hopping system. The reported CC-NDR exhibits adjustable threshold voltage from 10-3 to 102 V, on-state current from 105 to 108 A/cm2 and off-state current is as low as ∼10 A/cm2 depending on device dimensions, thermal isolation condition, environmental temperature and activation energy of material. Uniquely, unlike in NbO2, Nb2O5, TiO2, TaOx et. al. materials, the CC-NDR in MCNO is more stable and reliable, because it does not undergo any electroforming process. These traits make MCNO a very potential candidate for CC-NDR devices.
Near-field scattering enhancement of perylene based aggregates for random lasing
Authors: Zhang Zhen-zhen , Yin Lei-cheng , Xu Xiao-long , Xia Jiang-ying , Xie Kang , Zou Gang , Zhang Xiao-juan , Hu Zhi-jia , Zhang Qi-jin
Published: May 2019

Strong near-field scattering enhancement (NFSE) of polyhedral oligomeric silsesquioxanes (POSS) nanoparticles (NPs) aggregates is found through physical simulation. An aggregation of N,N’-di-[3-(isobutyl polyhedral oligomeric silsesquioxanes) propyl] perylene diimide (DPP) which possesses POSS as scatteres experimentally performs strong NFSE, which confirms the physical simulation results. Moreover, coherent random laser is triggered from the DPP aggregates in carbon disulfide. It is the NFSE of POSS NPs connected to both ends of DPP through covalent bonds and the NFSE of their aggregation thanks to DPP’s aggregation that is responsible for the coherent random laser. So, this work develops a method to improve weak scattering of system through construction of molecules, and opens a road to a variety of novel interdisciplinary investigations, involving molecular designing for disordered photonics.
Optical properties and response mechanism analysis of multi-branched fluorescent probes based on intramolecular charge transfer
Authors: Zhou Yong , Wang Xiao-fei , Tan Chao-hua , Wang Chuan-kui
Published: May 2019

In this work, the optical properties of fluorescent probes used for detection of biothiol were studied by employing time-dependent density functional theory. By calculating the single photon absorption and emission properties of probe Mol.1, Mol.2 and Mol.3 before and after reaction with cysteine and homocysteine, we have investigated the effect of carbon-carbon triple bond and benzene ring on the properties of fluorescent probes. It is found that the oscillator strength of probe molecules increases gradually with the improvement of the structure of the electron donor triphenylamine and the addition of carbon-carbon triple bonds, and better properties of fluorescence probes have also been demonstrated. At the same time, the effect of different number of side branches on the molecular properties of the probe was also studied. The results showed that compared with single-branched molecule Z1 and tribranched probe Mol.3, two side probe molecules Z2 had higher oscillator strength and better detection effect. In addition, the new single-branched probe Mol.4 with the addition of carbon-carbon triple bonds and benzene rings has better probe properties and simpler structure than the tribranched probe Mol.3.
The role of the genome in experience-dependent plasticity: Extending the analogy of the genomic action potential
Authors: Clayton David F. , Anreiter Ina , Aristizabal Maria , Frankland Paul W. , Binder Elisabeth B. , Citri Ami
Published: May 2019

Our past experiences shape our current and future behavior. These experiences must leave some enduring imprint on our brains, altering neural circuits that mediate behavior and contributing to our individual differences. As a framework for understanding how experiences might produce lasting changes in neural circuits, Clayton [D. F. Clayton,
Neurobiol. Learn. Mem.
74, 185–216 (2000)] introduced the concept of the genomic action potential (gAP)—a structured genomic response in the brain to acute experience. Similar to the familiar electrophysiological action potential (eAP), the gAP also provides a means for integrating afferent patterns of activity but on a slower timescale and with longer-lasting effects. We revisit this concept in light of contemporary work on experience-dependent modification of neural circuits. We review the “Immediate Early Gene” (IEG) response, the starting point for understanding the gAP. We discuss evidence for its involvement in the encoding of experience to long-term memory across time and biological levels of organization ranging from individual cells to cell ensembles and whole organisms. We explore distinctions between memory encoding and homeostatic functions and consider the potential for perpetuation of the imprint of experience through epigenetic mechanisms. We describe a specific example of a gAP in humans linked to individual differences in the response to stress. Finally, we identify key objectives and new tools for continuing research in this area.
Lacapitis deminutiode un rey
Authors: González-Barrera Julián
Published: May 2019

Las sátiras contra Felipe III y sus ministros fueron una parte fundamental de la poesía del conde de Villamediana, especialmente en los últimos años de su reinado. Su audacia no conoció límites. En uno de sus sonetos mitológicos utilizará el mito de Hércules y Ónfale para acusar a Felipe III de ser un esclavo sin voluntad para reinar, una auténticacapitis deminutioque ponía en duda su condición de rey, cristiano y hombre.
Influence of reconstruction settings in electrical impedance tomography on figures of merit and physiological parameters
Authors: Thürk F , Elenkov M , Waldmann A D , Böhme S , Braun C , Adler A , Kaniusas E
Published: May 2019

Objective: Electrical impedance tomography (EIT) is a non-invasive and relatively cheap imaging technique allowing continuous monitoring of lung function at the bedside. However, image reconstruction and processing are not yet standardized for clinical use, limiting comparability and reproducibility between studies. In addition, optimal reconstruction settings still have to be identified for different clinical applications. In this work (i) a systematic way to select ‘good’ EIT algorithm parameters is developed and (ii) an evaluation of these parameters in terms of correct functional imaging and consistency is performed. Approach: First, 19 200 reconstruction models are generated by full factorial design of experiment in 5D space. Then, in order to quantify the quality of reconstruction, known conductivity changes are introduced and figures of merit (FoM) are calculated from the response image. These measures are further used to select a subset of reconstruction models, matching certain FoM thresholds, and are then used for in vivo evaluation. For this purpose, EIT images of one piglet are reconstructed to assess changes in tidal impedance and end-expiratory lung impedance, at positive end expiratory pressure of 0 and 15 cmH2O. From ground truth spirometry measurements, physiological criteria are formulated and the subset of models is further reduced. Finally, the remaining reconstruction models are evaluated on physiological data gathered from published data in the literature to assess the generalization possibilities. Main results: Parametrization of EIT image reconstruction has a strong influence on the resulting FoM and the derived physiological parameter. While numerous reconstruction models showed reasonable values for a single parameter, in total only 12 matched all simulation and physiological criteria. After validation on further physiological data, only a single reconstruction model remained with a noise figure of 0.3, target size of 0.08, weight radius of 0.3, normalized voltage and strong weighting of lung and heart regions. Furthermore, the relationship between the reconstruction settings and some FoM could be partly explained by using a linear statistical model. Significance: The quest for standard reconstruction settings is highly relevant for future clinical applications. Simulation measures might help to assess the quality of the reconstruction models, but further evaluation of more data and different experimental settings is required.
A minimal tight-binding model for the quasi-one-dimensional superconductor K2Cr3As3
Authors: Cuono Giuseppe , Autieri Carmine , Forte Filomena , Mercaldo Maria Teresa , Romano Alfonso , Avella Adolfo , Noce Canio
Published: May 2019

We present a systematic derivation of a minimal five-band tight-binding model for the description of the electronic structure of the recently discovered quasi-one-dimensional superconductor K2Cr3As3. Taking as a reference the density-functional theory (DFT) calculation, we use the outcome of a Löwdin procedure to refine a Wannier projection and fully exploit the predominant weight at the Fermi level of the states having the same symmetry of the crystal structure. Such states are described in terms of five quasi-atomic d orbitals: four planar orbitals, two d

xy
and two

d

x

2

−

y

2

, and a single out-of-plane one,

d

z

2

. We show that this minimal model reproduces with great accuracy the DFT band structure in a broad energy window around the Fermi energy. Moreover, we derive an explicit simplified analytical expression of such model, which includes three nearest-neighbor (NN) hopping terms along the z direction and one NN term within the xy plane. This model captures very efficiently the energy spectrum of the system and, consequently, can be used to study transport properties, superconductivity and dynamical effects in this novel class of superconductors.
Giant-dipole excitons in cuprous oxide
Authors: Kurz M , Scheel S
Published: May 2019

In this work we present the interaction potentials and eigenenergies of a novel species of Wannier excitons when exposed to crossed electric and magnetic fields. More precisely, we present the theory of giant-dipole excitons in Cu2O. We derive an exact formulation of the field-dressed excitonic Hamiltonian and exemplarily calculate the excitonic eigenenergies in an exact diagonalization approach for external field strengths of B = 4T and E = 1 kV/cm. For this particular field configuration, we obtain level spacings between 1.14 μV and 77.6 μeV.
Optical observation of fermionic partons in Kitaev spin balls
Authors: Yamamoto Shoji , Kimura Taku
Published: May 2019

We demonstrate a Kitaev spin liquid in a polyhedral cluster and propose detecting its fractional excitations—Majorana spinons—by magnetic Raman scattering. While little polarization dependence of the Raman spectra at sufficiently low temperatures is usual with quantum spin liquids, the present observations are primarily of geometric origin. The Raman scattering intensity peaks melt with increasing temperature, to be more precise, with increasing number of background gauge-flux excitations.
Anisotropic dynamics of nanoparticles in clusters at a solid-liquid interface by laser trapping
Authors: Hanasaki Itsuo , Hosokawa Chie
Published: May 2019

It is well-recognized that the Brownian motion of particles in fluids is random. Nevertheless, there can be characteristics depending on the specific physical conditions. We analyze the system of nanoparticle clusters formed by the laser trapping force field at the solid-liquid interface, based on the microscopy movie data. Since the laser trapping force field is basically a function of radial distance from the focal point in the two dimension at the liquid-solid interface, we examine the difference of displacement distributions in the radial and circumferential directions. The results show that the basic characteristics in this system depends on the laser power, and there is an anisotropy in the stochastic motion of the nanoparticles.
Modulation of Graphene/Au(111) Interaction by Electrocatalytic Hydrogen Evolution Reaction
Authors: Fukushima Tomohiro , Yasuda Kensuke , Hasebe Hidetaka , Zhou Ruifeng , Minamimoto Hiro , Murakoshi Kei
Published: May 2019

Electronic structure of monolayer graphene with metal contacts can be modified by control of interfacial interaction. Here, we show that the strength of local interfacial interaction between graphene and Au(111) surface can be electrochemically controlled by the hydrogen evolution reaction process. Graphene/Au(111) electrodes were prepared by the chemical vapour deposition. Raman spectroscopy indicated existence of monolayer of graphene over Au surface. Local interaction of graphene/Au(111) interaction can be differentiated by intercalation of H2 molecules at interface. This study shed lights on the possibility of proton penetration through the graphene to modify the strength of interaction between graphene and Au(111) surface.
Time-resolved measurement of photocarrier generation in CH3NH3PbI3 single crystals
Authors: Tanaka Y , Akimoto I
Published: May 2019

A giant microwave response is transiently observed in CH3NH3PbI3 single crystals under pulsed laser excitation at temperatures in both structural phases across the transition at 161 K. The response is caused by photocarriers generated in the specimen mounted in a microwave cavity. This detection technique is capable of measuring the carrier dynamics with a time-resolution of a few nanoseconds. Based on the time-resolved excitation spectrum near the absorption edge, we unveil that the photocarriers are generated by long-lived excitons as well as by fast band-to-band transition.
Nonlinear polarization optical response to entangled state of biexciton
Authors: Tsuji T , Oohata G , Mizoguchi K
Published: May 2019

We have investigated the nonlinear optical responses of biexcitons which show the polarization entanglement by using pump-probe spectroscopy. Measuring all polarization combinations of pump-probe signals and precise analysis using the idea of quantum tomography enable us to extract the specific property of the entanglement. The obtained results indicate the two kinds of the third-order nonlinear response, namely the photo-induced absorption and the optical Kerr effect. From the analysis with the optical Kerr effect signals, the polarization correlations of the optical responses are clearly derived.
Spectral properties of chiral electromagnetic near fields created by chiral plasmonic nanostructures
Authors: Hashiyada S. , Endo K. , Narushima T. , Togawa Y. , Okamoto H.
Published: May 2019

The surface-enhanced chiral-optical spectroscopy is based on the interaction of chiral molecules with chiral electromagnetic near field localized on a chiral plasmonic nanostructure. It is of fundamental importance to reveal the spectral characteristics of chiral near fields for maximizing the chiral interaction. Here we investigate relations between near field and far field polarization characteristics of the chiral plasmonic nanostructures, using electromagnetic simulations. We found that spectral features of chiral near fields created by the nanostructures intercorrelate with those of far field optical rotation. This finding may provide us a method to characterize and design the chiral near field.
Second harmonic generation from complementary triangular Au metamaterials
Authors: Habibullah Y B , Iwata K , Ishihara T
Published: May 2019

Sub-wavelength square array of a triangular Au platelet and its complementary structure (i.e. that of a triangular hole in a square film of Au) are compared in terms of second harmonic generation efficiency for fundamental light in the near infrared and visible region of spectrum for normal incidence. Electric field strength around the convex corners of a triangular particle is at least 10 times larger than the one around the concave corners of triangular hole in the complementary structure. Nevertheless the SHG intensity at the respective resonant frequency is found to be comparable, which are numerically estimated by an overlap integral of nonlinear polarization and electric field at the SHG frequency in the nonlinear optical scattering theory originally proposed by Roke et al. (Phys. Rev. B 70, 115106 (2004)). The reason is due to the large electric field strength at the sides of the triangular hole at the resonance frequency, which compensates the suppressed electric field at the concave corners in the overlap integral.
Unpacking the climatic drivers of US agricultural yields
Authors: Ortiz-Bobea Ariel , Wang Haoying , Carrillo Carlos M , Ault Toby R
Published: May 2019

Understanding the climatic drivers of present-day agricultural yields is critical for prioritizing adaptation strategies to climate change. However, unpacking the contribution of different environmental stressors remains elusive in large-scale observational settings in part because of the lack of an extensive long-term network of soil moisture measurements and the common seasonal concurrence of droughts and heat waves. In this study, we link state-of-the-art land surface model data and fine-scale weather information with a long panel of county-level yields for six major US crops (1981–2017) to unpack their historical and future climatic drivers. To this end, we develop a statistical approach that flexibly characterizes the distinct intra-seasonal yield sensitivities to high-frequency fluctuations of soil moisture and temperature. In contrast with previous statistical evidence, we directly elicit an important role of water stress in explaining historical yields. However, our models project the direct effect of temperature—which we interpret as heat stress—remains the primary climatic driver of future yields under climate change.