bluuebunny/crossref_metadata_2025 huggingface dataset:
Small GTPase-dependent regulation of leukocyte–endothelial interactions in inflammation
Authors: Chu Julia Y. , McCormick Barry , Vermeren Sonja
Published: May 2018

Inflammation is a complex biological response that serves to protect the body's tissues following harmful stimuli such as infection, irritation or injury and initiates tissue repair. At the start of an inflammatory response, pro-inflammatory mediators induce changes in the endothelial lining of the blood vessels and in leukocytes. This results in increased vascular permeability and increased expression of adhesion proteins, and promotes adhesion of leukocytes, especially neutrophils to the endothelium. Adhesion is a prerequisite for neutrophil extravasation and chemoattractant-stimulated recruitment to inflammatory sites, where neutrophils phagocytose and kill microbes, release inflammatory mediators and cross-talk with other immune cells to co-ordinate the immune response in preparation for tissue repair. Many signalling proteins are critically involved in the complex signalling processes that underpin the inflammatory response and cross-talk between endothelium and leukocytes. As key regulators of cell–cell and cell–substratum adhesion, small GTPases (guanosine triphosphatases) act as important controls of neutrophil-endothelial cell interactions as well as neutrophil recruitment to sites of inflammation. Here, we summarise key processes that are dependent upon small GTPases in leukocytes during these early inflammatory events. We place a particular focus on the regulation of integrin-dependent events and their control by Rho and Rap family GTPases as well as their regulators during neutrophil adhesion, chemotaxis and recruitment.
Spectral clustering ensemble model based on distance decision
Authors: Fei Bowen , Qiu Yunfei , Liu Daqian
Published: May 2018

Spectral clustering (SC) is a kind of clustering method which shows superior performance in recent years; however, the method is sensitive to the initial scale parameter. In order to improve the accuracy and stability of clustering, this Letter proposes a novel approach of SC ensemble model based on distance decision. First of all, the model performs several times clustering for data samples by SC, and corresponding joint Laplacian matrix is obtained. Then, a new method of distance decision is proposed, the joint Laplacian matrix is transformed into a cumulative distance matrix using the fuzzy theory. Finally, the distance matrix is introduced into the density peaks (DP) algorithm, and the final results of clustering are obtained by the improved DP algorithm for clustering ensemble. The experimental results show that the clustering ensemble model proposed in this Letter is more effective than other classical clustering ensemble model on the 12 data sets in University of California Irvine machine learning database.
Improvement of ground radiation antenna performance using compact EBG in presence of battery effects
Authors: Xu Yunxue , Qu Longyue , Kim Hyung‐Hoon , Kim Hyeongdong
Published: May 2018

In Internet‐of‐things devices, to alleviate the performance degradation of the ground radiation antenna due to the large battery, two compact electromagnetic bandgap (EBG) unit cells are introduced between the ground radiation antenna and the battery. The ground radiation antenna is comprised a small loop‐type circuit that is designed within a 5‐mm × 5‐mm ground clearance for 2.4‐GHz WLAN applications. The compact EBG unit cell is a modified square split‐ring resonator that is designed by meandering‐line technology. The measurement results showed that the 3:1 VSWR impedance bandwidth of the ground radiation antenna increased from 30 to 90 MHz, and the average total efficiency increased from 19% to over 54% with and without the introduction of the EBG structure, respectively.
Aperture efficiency improvement of folded reflectarray using rectangle and split‐ring combined element
Authors: Jeong J.G. , Park N.J. , Yoon Y.J.
Published: May 2018

In this Letter, the aperture efficiency of a folded reflectarray is improved using a proposed element. This element is designed with a simple structure using a rectangle and split‐ring combined structure to obtain a more accurate reflection phase for the folded reflectarray than that of a conventional element in the millimetre wave frequency. Thus, a high aperture efficiency of 55.04% is obtained at 77 GHz. The element design concept and procedure are presented in detail.
Assessment of regional transmission connection capacity based on two novel indices
Authors: Güverçinci Ali Haydar , Göl Murat
Published: May 2018

In deregulated market environments, transmission system expansion planning becomes a troublesome task as transmission system operators lose their direct control over plant investments. Moreover, the increase in the share of renewable sources in electricity generation creates an uncertainty about future generation investments in terms of location and size. Assessment of transmission connection capacities, which determines the boundaries of new generation amount that can safely be connected from a region, is a mechanism that facilitates economic and reliable transmission expansion. In this study, use of two novel indices, namely region‐based evaluation index (REI) and line‐based evaluation index (LEI), is proposed for this purpose. REI aims to indicate the suitability of a region for new generation investments from a holistic point of view. Its calculation is based on the loadings of the lines under N  − 1 conditions, and their overloading probabilities. LEI, on the other hand, is usable to assess each variation of the considered line's loading. By tracking LEI of a line, one can follow if a line's loading exceeds limits during contingencies, and observe if the loading benefits from additional generation. It allows identifying the weak points of the analysed system. The proposed methodology was demonstrated on projected Turkish Transmission Network model of 2026.
Aharonov–Bohm‐inspired tomographic imaging via compressive sensing
Authors: Valagiannopoulos Constantinos , Marengo Edwin A. , Dimakis Alexandros G. , Alù Andrea
Published: May 2018

The Aharonov–Bohm effect is a well‐established quantum phenomenon that relates the behaviour of an electron not only to the local electromagnetic field but also to the associated potentials. An important consequence is that electron beams travelling through an arbitrary medium can carry information not only about the properties of the materials along with their trajectories but also about those of the entire background around them. Based on this established principle, the authors propose an inverse formulation for the estimation of a sample's magnetic permeability based on measurements of the wave function of a split electron beam. For one‐dimensional distributions, the analysed concept is shown to lead to the ideal retrieval of the sample's texture for a sufficiently large number of measurements. Two‐ and three‐dimensional permeability distributions can be successfully estimated by employing sparsification transformations associated with compressive imaging approaches. The proposed configuration and formulation may be useful in non‐destructive detection and sensing of biological, chemical or ferrimagnetic samples.
Design of ultra‐compact UWB antenna with band‐notched characteristics for MIMO applications
Authors: Gautam Anil Kumar , Yadav Swati , Rambabu Karumudi
Published: May 2018

This study describes the design of a very compact dual‐band‐notched ultrawide band (UWB) multiple‐input multiple‐output (MIMO) antenna. The main features of the proposed antenna are its compact dimensions and high isolation between the two antenna elements. The UWB performance of the antenna is attained by designing two identical triangular‐shaped patch elements, which are designed opposite to each other and connected to a tapered microstrip feedline. The ground plane of the proposed antenna consists of a funnel‐shaped patch connected with two triangles at the lower end. In addition, two J‐shaped slits are etched in the radiator to get the band rejection characteristics at wireless local area network band from 5.1 to 5.8 GHz and IEEE INSAT/Super‐Extended C‐band from 6.7 to 7.1 GHz. The designed antenna has the smallest dimension of . Results show that the MIMO antenna has a large impedance bandwidth of 31.9 GHz from 3.1 to 35 GHz. The diversity performance of the proposed antenna is also analysed using different parameters such as envelope correlation coefficient (ECC), diversity gain, total active reflection coefficient and so on. Due to the low mutual coupling of <−24 dB and ECC of <0.2 across the frequency band this antenna is a good candidate for portable UWB applications.
Different approaches in calculating AC inductive interference from power lines on pipelines
Authors: Lucca Giovanni
Published: May 2018

When dealing with 50–60 Hz inductive electromagnetic interference from power lines on pipelines, the key parameter is represented by the per unit length mutual impedance between the power line conductor‐Earth and pipe‐Earth circuits. Different philosophies can be followed concerning the evaluation of this parameter, i.e.: modelling the power line conductors by wires of finite length or by wires of infinite length. What is missing in the literature is a comparison of the interference results (i.e. overvoltage and overcurrent induced on the pipeline) that are obtained by following these different approaches. Thus, this study is devoted to investigate this neglected point relevant to the 50–60 Hz interference issue. To this aim, the authors also present and compare some results of interference calculated in real cases and, on the basis of them, they draw some conclusions concerning which, in their opinion, is the best approach.
New vectorial H(curl) shape functions for the edge meshless method
Authors: Silva Paulo M.I. , Mesquita Renato C. , Lima Naísses Z.
Published: May 2018

New vectorial shape functions for the edge meshless method are introduced. The theory to develop these functions is based on Nédélec's elements of the first type in the space. The mathematical formulation to construct the shape functions is presented and the method's main characteristics in two dimensions are verified numerically. As a result, it is shown that the numerical solution is not corrupted by spurious modes and that the new shape functions are less dependent on edges distribution in the problem domain. Furthermore, it is possible to generate consistent approximations even when the length of the edges tends to zero.
Ambulante Entgiftung bei Patienten mit Medikamenten-Doppelabhängigkeit von Benzodiazepinen und Opioiden
Authors: Piest Bernhard
Published: May 2018

Ziel Bericht über ein einheitliches Vorgehen bei einer ambulanten Entgiftung von 2 Patienten mit Doppelabhängigkeit von Benzodiazepinen und Opioiden.

Methode Beide Patienten wurden zunächst mithilfe von Buprenorphin von den Opioiden entgiftet, dann auf den Opiatantagonisten Naltrexon eingestellt. Im zweiten Schritt wurden sie unter der Naltrexontherapie von den Benzodiazepinen entgiftet.

Ergebnis Bei beiden Patienten wurde für beide Substanzen Abstinenz erreicht.

Diskussion Das geschilderte Vorgehen eignet sich eventuell als Standard für ähnliche Fälle.
Antidepressiva
Authors: Haverkamp Wilhelm , Blaschke Daniela , Ströhle Andreas
Published: May 2018

Die meisten Antidepressiva besitzen ein Potenzial für unerwünschte kardiale Wirkungen. Hinsichtlich der prognostischen Bedeutung im Vordergrund stehen
unerwünschte elektrophysiologische Effekte (d. h. eine QT/QTc-Verlängerung und/oder eine Zunahme der QRS-Dauer), die zu tachykarden Rhythmusstörungen führen
können. Berichte über solche proarrhythmischen Ereignisse haben in den letzten Jahren zu einer zunehmenden Verunsicherung im klinischen Alltag geführt.

Erfreulicherweise sind schwerwiegende unerwünschte Wirkungen von Antidepressiva selten. Zu den Maßnahmen, die geeignet erscheinen, ihre Häufigkeit weiter zu
minimieren gehören eine strenge Indikationsstellung, eine Kenntnis der im Einzelfall ggf. vorliegenden kardialen Grund- oder Begleiterkrankungen und eine (auch
durch letzteres beeinflusste) sorgfältige Auswahl des Antidepressivums. Während einer Behandlung mit kardial wirksamen Antidepressiva sind
Kontrolluntersuchungen notwendig. Hierzu gehören klinische Kontrollen und regelmäßige EKG-Registrierungen. Auch eine intensivierte interdisziplinäre Kooperation
kann hilfreich sein.
Kardiale Biomarker und EKG-Veränderungen beim Schlaganfall
Authors: von Rennenberg Regina , Scheitz Jan F. , Endres Matthias , Nolte Christian
Published: May 2018

Kardiale Komplikationen treten bei akuten Schlaganfallpatienten häufig auf und sind eine der Haupttodesursachen nach einem Schlaganfall. Gleichzeitig sind
kardiale Erkrankungen häufig Ursache für die Entstehung von Schlaganfällen. Kardiovaskuläre und zerebrovaskuläre Erkrankungen teilen viele gemeinsame
Risikofaktoren, sodass nicht selten zusätzlich zum Schlaganfall auch eine KHK vorliegt. Das kontinuierliche EKG-Monitoring stellt einen wichtigen Baustein in
der diagnostischen Abklärung beim Schlaganfall dar und die Leitlinien der American Heart Association (AHA) empfehlen Troponin bei Schlaganfallpatienten zu
bestimmen. Häufig finden sich nach Schlaganfall EKG-Veränderungen sowie eine Erhöhung von Troponin. Beides ist mit einer schlechten Prognose assoziiert. Es gibt
jedoch wenig konkrete Empfehlungen zum Umgang mit pathologischen EKG- und Laborbefunden im Alltag. Im klinischen Alltag gestaltet sich die Differenzialdiagnose
von kardialen Erkrankungen bei Schlaganfallpatienten aber häufig schwierig: Kardiale Erkrankungen präsentieren sich bei Schlaganfallpatienten vielfach mit
atypischen Symptomen. Bei Schlaganfallpatienten können EKG-Veränderungen oder eine Erhöhung kardialer Biomarker vorkommen, ohne dass dem eine akute koronare
Ischämie zugrunde liegt. Stattdessen können sowohl chronische kardiale als auch nicht-kardiale Erkrankungen die Ursache für die Erhöhung kardialer Biomarker
oder EKG-Veränderungen sein. Daneben kommt es bei einigen Schlaganfallpatienten zu einer neurogenen Myokardschädigung im Sinne einer stressinduzierten
Kardiomyopathie.

Dieser Artikel soll einen Überblick über die klinische Relevanz und Interpretationsmöglichkeiten häufiger EKG-Veränderungen und kardialer Biomarker bei Patienten
mit akuter zerebraler Ischämie liefern.
Aufbruchstimmung? Bessere Gesundheit durch digitale Medizin …
Authors: Gocke Peter
Published: May 2018

… lautet der Untertitel eines Buches, welches unser neuer Gesundheitsminister Jens Spahn bereits im Jahre 2016 mit herausgegeben hat. Mir ist nicht bekannt, ob er damals bereits mit seiner Berufung zum nächsten Gesundheitsminister gerechnet hat – die Größe der Aufgabe dürfte ihm vermutlich erst jetzt bewusst werden.
Ausbildung zum Notfallmediziner: Burgfrieden zwischen den Fachgesellschaften
Authors: Mau Jens
Published: May 2018

Auf dem Ärztetag soll nach sechs Jahren Diskussion eine neue Musterweiterbildungsordnung verabschiedet werden. Viel Zoff gab es um die Ausbildung der Notfallmediziner. Doch die Bundesärztekammer (BÄK) hat jetzt einen Kompromiss ausgehandelt, mit dem alle Seiten eine Weile leben können.
Kliniken Köln: Geschäftsführer der Kölner Kliniken soll gehen
Authors: Hissel Yvonne
Published: May 2018

Roman Lovenfosse-Gehrt wird nach einer Sitzung des Aufsichtsrates mit sofortiger Wirkung von seinen Aufgaben entbunden. Grund für die Entscheidung ist die große finanzielle Schieflage des Hauses.
3. Fachmesse krankenhaus Technologie: Die Innovationsleistung steigern
Authors: Thalmayr Maria
Published: May 2018

Zeit und Raum zu bieten für ausführliche Expertengespräche mit Herstellern, Dienstleistern und Kollegen, ist Intention der Fachmesse Krankenhaus Technologie. Am 19. und 20. Juni offeriert das junge Branchentreffen Entscheidern aus dem Krankenhaus zum dritten Mal Inspiration für einen optimierten Klinikbetrieb.
IT-Infrastruktur: Der KIS-Anbieter als Systemadministrator
Authors: Kucera Martin
Published: May 2018

In deutschen Krankenhäusern stoßen nicht nur viele Ärzte und Pflegekräfte an die Grenzen ihrer Belastbarkeit – auch die IT-Mitarbeiter sehen sich angesichts der zunehmenden Digitalisierung immer mehr administrativen Aufgaben ausgesetzt. KIS-Hersteller bieten Kliniken deshalb an, die Verwaltung ihrer IT-Infrastruktur selbst zu übernehmen.
99. Deutscher Röntgenkongress: Radiologie verbindet
Authors: Stavginski Hans-Georg
Published: May 2018

Im Interview stellt Kongresspräsident Prof. Dr. Peter Huppert Schwerpunkte und besondere Akzente des Kongresses vor, der vom 9. bis 12. Mai in Leipzig stattfindet.
Eine Standortbestimmung: Radiologie 4.0 – oder wie steht es um die Basics?
Authors: Freye Carolin
Published: May 2018

Kein anderes medizinisches Fachgebiet wendet IT-Systeme schon so lange und in einer solchen Tiefe an wie die Radiologie – sei es RIS, PACS oder Spracherkennung. Big-Data und Künstliche Intelligenz sind die nächsten Schritte. Also alles bestens im radiologischen Alltag deutscher Krankenhäuser?
Universelles Ausweichgebäude für das LKH Graz Süd-West, Standort Süd: Anheimelnd hölzern
Authors: Thalmayr Maria
Published: May 2018

Mit einem Pavillon in Holzriegelbauweise beschreitet das Landeskrankenhaus Graz Süd-West, Standort Süd, völlig neue Wege. „Statt Krankenhausluft schnuppern unsere Patienten den angenehmen Duft von Holz“, freut sich die Technische Leiterin, Eva Peter.
39. Tagung „Technik im Krankenhaus“: Weiterentwicklung von Personal und Prozessen
Authors: Brüning Cord , Fouckhardt-Bradt Birgit
Published: May 2018

Neben dem anhaltenden Kostendruck sind Digitalisierung und demografischer Wandel mit resultierendem Fachkräftemangel für Technische Abteilungen die dringlichen Herausforderungen. Die WGKT macht nun die notwendige Weiterentwicklung von Personal und Prozessen zum Schwerpunkt.
A Different Approach to the EGFR Inhibitor Gefitinib Involving Solid-Phase Synthesis
Authors: Carvalho Luísa , Sequeira André , Lourenço Ana , Ferreira Luísa , Branco Paula , Mendes Zita , Lourenço Nuno , Figueiredo Margarida
Published: May 2018

An efficient solid-phase synthesis approach is here reported for the first time to prepare the EGFR inhibitor Gefitinib. The five-step synthetic strategy used FMP resin as the solid support, and FTIR and colorimetric assays were used to track the reaction’s progress. Gefitinib was obtained with an overall yield of 40%.
Applying User-Centered Design Methods to the Development of an mHealth Application for Use in the Hospital Setting by Patients and Care Partners
Authors: Couture Brittany , Lilley Elizabeth , Chang Frank , DeBord Smith Ann , Cleveland Jessica , Ergai Awatef , Katsulis Zachary , Benneyan James , Gershanik Esteban , Bates David , Collins Sarah
Published: May 2018

Introduction Developing an optimized and user-friendly mHealth application for patients and family members in the hospital environment presents unique challenges given the diverse patient population and patients' various states of well-being.

Objective This article describes user-centered design methods and results for developing the patient and family facing user interface and functionality of MySafeCare, a safety reporting tool for hospitalized patients and their family members.

Methods Individual and group usability sessions were conducted with specific testing scenarios for participants to follow to test the usability and functionality of the tool. Participants included patients, family members, and Patient and Family Advisory Council (PFAC) members. Engagement rounds were also conducted on study units and lessons learned provided additional information to the usability work. Usability results were aligned with Nielsen's Usability Heuristics.

Results Eleven patients and family members and 25 PFAC members participated in usability testing and over 250 patients and family members were engaged during research team rounding. Specific themes resulting from the usability testing sessions influenced the changes made to the user interface design, workflow functionality, and terminology.

Conclusion User-centered design should focus on workflow functionality, terminology, and user interface issues for mHealth applications. These themes illustrated issues aligned with four of Nielsen's Usability Heuristics: match between system and the real world, consistency and standards, flexibility and efficiency of use, and aesthetic and minimalist design. We identified workflow and terminology issues that may be specific to the use of an mHealth application focused on safety and used by hospitalized patients and their families.
Functioning in Women with Cervical Cancer in Brazil: the Perspective of Experts
Authors: Castaneda Luciana , Bergmann Anke , Castro Shamyr , Koifman Rosalina
Published: May 2018

Objective The objective of this study was to identify the perspective of the specialists about functioning in women with cervical cancer (CC).

Methods A study was conducted with specialists using the Delphi methodology. The specialist contacts were found in oncology organizations and associations, as well as in a referral hospital in the treatment of CC. The questions that the experts answered covered the biopsychosocial domains of the International Classification of Functioning, Disability and Health (ICF).

Results Twenty-five specialists participated in the study. The experts' responses generated 485 significant concepts. The categories that presented the highest frequencies of reporting by the specialists were health services, systems and policies; structure of the reproductive system; health professionals and sexual function.

Conclusion Regarding the perception of the specialists, this study concluded that 24 categories of ICF are the most relevant in the context of functioning in women with CC. The results suggest that the biopsychosocial perspective was incorporated in the experts' perceptions about the functioning phenomenon in women with CC in Brazil.
Evaluation of a Novel System to Enhance Clinicians' Recognition of Preadmission Adverse Drug Reactions
Authors: Smith Joshua , Chen Qingxia , Denny Joshua , Roden Dan , Johnson Kevin , Miller Randolph
Published: May 2018

Background Often unrecognized by providers, adverse drug reactions (ADRs) diminish patients' quality of life, cause preventable admissions and emergency department visits, and increase health care costs.

Objective This article evaluates whether an automated system, the Adverse Drug Effect Recognizer (ADER), could assist clinicians in detecting and addressing inpatients' ongoing preadmission ADRs.

Methods ADER uses natural language processing to extract patients' medications, findings, and past diagnoses from admission notes. It compares excerpted information to a database of known medication adverse effects and promptly warns clinicians about potential ongoing ADRs and potential confounders via alerts placed in patients' electronic health records (EHRs). A 3-month intervention trial evaluated ADER's impact on antihypertensive medication ordering behaviors. At the time of patient admission, ADER warned providers on the Internal Medicine wards of Vanderbilt University Hospital about potential ongoing preadmission antihypertensive medication ADRs. A retrospective control group, comprised similar physicians from a period prior to the intervention, received no alerts. The evaluation compared ordering behaviors for each group to determine if preadmission medications changed during hospitalization or at discharge. The study also analyzed intervention group participants' survey responses and user comments.

Results ADER identified potential preadmission ADRs for 30% of both groups. Compared with controls, intervention providers more often withheld or discontinued suspected ADR-causing medications during the inpatient stay (p < 0.001). Intervention providers who responded to alert-related surveys held or discontinued suspected ADR-causing medications more often at discharge (p < 0.001).

Conclusion Results indicate that ADER helped physicians recognize ADRs and reduced ordering of suspected ADR-causing medications. In hospitals using EHRs, ADER-like systems could improve clinicians' recognition and elimination of ongoing ADRs.
Periphere Regionalanästhesie ohne Komplikationen – Ein Traum wird wahr?!
Authors: Wiesmann Thomas , Döffert Jens , Steinfeldt Thorsten
Published: May 2018

Periphere Regionalanästhesieverfahren sind relativ sichere Verfahren der klinischen Anästhesie – dennoch können typische, meist transiente und selten sogar persistierende Komplikationen auftreten. Neben allgemeinen Komplikationen und Strategien zur Risikoreduktion widmet sich dieser Artikel akzidentellen Mitblockaden anderer nervaler Strukturen am Beispiel des Plexus brachialis. Ein Ausblick in die Zukunft informiert über selektivere Blockaden.
Patientenkontrollierte Analgesie: Methoden, Handhabung und Ausbaufähigkeit
Authors: Abrolat Marie , Eberhart Leopold , Kalmus Gerald , Koch Tilo , Nardi-Hiebl Stefan
Published: May 2018

Eine nebenwirkungsarme und patientenadaptierte Schmerztherapie ist integraler Bestandteil aller multimodalen Behandlungskonzepte, die eine schnelle und komplikationsfreie Erholung nach operativen Eingriffen ermöglichen sollen. Die patientenkontrollierte Analgesie (PCA) bietet dabei eine etablierte und sichere Option für eine individuell angepasste Schmerztherapie, die – richtig genutzt – ein hohes Maß an Patientenzufriedenheit garantiert.
Organisation der perioperativen Schmerztherapie
Authors: Meißner Winfried , Erlenwein Joachim , Stamer Ulrike
Published: May 2018

Organisatorische Aspekte der postoperativen Schmerztherapie werden oft vernachlässigt – dabei sind sie ebenso wichtig wie Details zu pharmakologischen oder regionalanalgetischen Verfahren. Anhand virtueller Fragen und Erfahrungen eines Assistenzarztes beleuchten wir in diesem Artikel die „Organisation der perioperativen Schmerztherapie“: Schmerzerfassung und Dokumentation, Patienteninformation und -edukation, Aufgaben eines Akutschmerzdienstes.
Die Bedeutung der Hämolyse in Anästhesie und Intensivmedizin
Authors: Graw Jan , Baron David , Francis Roland
Published: May 2018

Die intravasale Hämolyse mit erhöhten Plasmakonzentrationen von zellfreiem Hämoglobin tritt nicht nur bei hämolytischen Erkrankungen auf – sie ist auch bei der Transfusion von Blutkonserven sowie bei Patienten mit ARDS, Sepsis oder kardiopulmonalem Bypass für den Krankheitsverlauf von Bedeutung. Dieser Beitrag möchte den klinisch tätigen Anästhesisten für die Relevanz der Hämolyse sowie deren Prävention und Früherkennung sensibilisieren.
Current sheet characteristics of a parallel-plate electromagnetic plasma accelerator operated in gas-prefilled mode
Authors: Liu Shuai , Huang Yizhi , Guo Haishan , Lin Tianyu , Huang Dong , Yang Lanjun
Published: May 2018

The axial characteristics of a current sheet in a parallel-plate electromagnetic plasma accelerator operated in gas-prefilled mode are reported. The accelerator is powered by a fourteen stage pulse forming network. The capacitor and inductor in each stage are 1.5 μF and 300 nH, respectively, and yield a damped oscillation square wave of current with a pulse width of 20.6 μs. Magnetic probes and photodiodes are placed at various axial positions to measure the behavior of the current sheet. Both magnetic probe and photodiode signals reveal a secondary breakdown when the current reverses the direction. An increase in the discharge current amplitude and a decrease in pressure lead to a decrease in the current shedding factor. The current sheet velocity and thickness are nearly constant during the run-down phase under the first half-period of the current. The current sheet thicknesses are typically in the range of 25 mm to 40 mm. The current sheet velocities are in the range of 10 km/s to 45 km/s when the discharge current is between 10 kA and 55 kA and the gas prefill pressure is between 30 Pa and 800 Pa. The experimental velocities are about 75% to 90% of the theoretical velocities calculated with the current shedding factor. One reason for this could be that the idealized snowplow analysis model ignores the surface drag force.
Generation of parasitic axial flow by drift wave turbulence with broken symmetry: Theory and experiment
Authors: Hong R. , Li J. C. , Hajjar R. , Chakraborty Thakur S. , Diamond P. H. , Tynan G. R.
Published: May 2018

Detailed measurements of intrinsic axial flow generation parallel to the magnetic field in the controlled shear decorrelation experiment linear plasma device with no axial momentum input are presented and compared to theory. The results show a causal link from the density gradient to drift-wave turbulence with broken spectral symmetry and development of the axial mean parallel flow. As the density gradient steepens, the axial and azimuthal Reynolds stresses increase and radially sheared azimuthal and axial mean flows develop. A turbulent axial momentum balance analysis shows that the axial Reynolds stress drives the radially sheared axial mean flow. The turbulent drive (Reynolds power) for the azimuthal flow is an order of magnitude greater than that for axial flow, suggesting that the turbulence fluctuation levels are set by azimuthal flow shear regulation. The direct energy exchange between axial and azimuthal mean flows is shown to be insignificant. Therefore, the axial flow is parasitic to the turbulence-zonal flow system and is driven primarily by the axial turbulent stress generated by that system. The non-diffusive, residual part of the axial Reynolds stress is found to be proportional to the density gradient and is formed due to dynamical asymmetry in the drift-wave turbulence.
A versatile tunable microcavity for investigation of light–matter interaction
Authors: Mochalov Konstantin E. , Vaskan Ivan S. , Dovzhenko Dmitriy S. , Rakovich Yury P. , Nabiev Igor
Published: May 2018

Light–matter interaction between a molecular ensemble and a confined electromagnetic field is a promising area of research, as it allows light-control of the properties of coupled matter. The common way to achieve coupling is to place an ensemble of molecules or quantum emitters into a cavity. In this approach, light–matter coupling is evidenced by modification of the spectral response of the emitter, which depends on the strength of interaction between emitter and cavity modes. However, there is not yet a user-friendly approach that allows the study of a large number of different and replaceable samples in a wide optical range using the same resonator. Here, we present the design of such a device that can speed up and facilitate investigation of light–matter interaction ranging from weak to strong coupling regimes in ultraviolet-visible and infrared (IR) spectral regions. The device is based on a tunable unstable λ/2 Fabry–Pérot microcavity consisting of plane and convex mirrors that satisfy the plane-parallelism condition at least at one point of the curved mirror and minimize the mode volume. Fine tuning of the microcavity length is provided by a Z-piezopositioner in a range up to 10 μm with a step of several nm. This design makes a device a versatile instrument that ensures easy finding of optimal conditions for light–matter interaction for almost any sample in both visible and IR areas, enabling observation of both electronic and vibrational couplings with microcavity modes thus paving the way to investigation of various coupling effects including Raman scattering enhancement, modification of chemical reactivity rate, lasing, and long-distance nonradiative energy transfer.
NH
2
−
in a cold ion trap with He buffer gas: Ab initio quantum modeling of the interaction potential and of state-changing multichannel dynamics
Authors: Hernández Vera Mario , Yurtsever Ersin , Wester Roland , Gianturco Franco A.
Published: May 2018

We present an extensive range of accurate ab initio calculations, which map in detail the spatial electronic potential energy surface that describes the interaction between the molecular anion NH2− (1A1) in its ground electronic state and the He atom. The time-independent close-coupling method is employed to generate the corresponding rotationally inelastic cross sections, and then the state-changing rates over a range of temperatures from 10 to 30 K, which is expected to realistically represent the experimental trapping conditions for this ion in a radio frequency ion trap filled with helium buffer gas. The overall evolutionary kinetics of the rotational level population involving the molecular anion in the cold trap is also modelled during a photodetachment experiment and analyzed using the computed rates. The present results clearly indicate the possibility of selectively detecting differences in behavior between the ortho- and para-anions undergoing photodetachment in the trap.
Quasi-isentropic compression using compressed water flow generated by underwater electrical explosion of a wire array
Authors: Gurovich V. , Virozub A. , Rososhek A. , Bland S. , Spielman R. B. , Krasik Ya. E.
Published: May 2018

A major experimental research area in material equation-of-state today involves the use of off-Hugoniot measurements rather than shock experiments that give only Hugoniot data. There is a wide range of applications using quasi-isentropic compression of matter including the direct measurement of the complete isentrope of materials in a single experiment and minimizing the heating of flyer plates for high-velocity shock measurements. We propose a novel approach to generating quasi-isentropic compression of matter. Using analytical modeling and hydrodynamic simulations, we show that a working fluid composed of compressed water, generated by an underwater electrical explosion of a planar wire array, might be used to efficiently drive the quasi-isentropic compression of a copper target to pressures ∼2 × 1011 Pa without any complex target designs.
Simulations of toroidal Alfvén eigenmode excited by fast ions on the Experimental Advanced Superconducting Tokamak
Authors: Pei Youbin , Xiang Nong , Shen Wei , Hu Youjun , Todo Y. , Zhou Deng , Huang Juan
Published: May 2018

Kinetic-MagnetoHydroDynamic (MHD) hybrid simulations are carried out to study fast ion driven toroidal Alfvén eigenmodes (TAEs) on the Experimental Advanced Superconducting Tokamak (EAST). The first part of this article presents the linear benchmark between two kinetic-MHD codes, namely MEGA and M3D-K, based on a realistic EAST equilibrium. Parameter scans show that the frequency and the growth rate of the TAE given by the two codes agree with each other. The second part of this article discusses the resonance interaction between the TAE and fast ions simulated by the MEGA code. The results show that the TAE exchanges energy with the co-current passing particles with the parallel velocity |v∥|≈VA0/3 or |v∥|≈VA0/5, where VA0 is the Alfvén speed on the magnetic axis. The TAE destabilized by the counter-current passing ions is also analyzed and found to have a much smaller growth rate than the co-current ions driven TAE. One of the reasons for this is found to be that the overlapping region of the TAE spatial location and the counter-current ion orbits is narrow, and thus the wave-particle energy exchange is not efficient.
Spontaneous insertion of GPI anchors into cholesterol-rich membrane domains
Authors: Li Jing , Liu Xiuhua , Tian Falin , Yue Tongtao , Zhang Xianren , Cao Dapeng
Published: May 2018

GPI-Anchored proteins (GPI-APs) can be exogenously transferred onto bilayer membranes both in vivo and in vitro, while the mechanism by which this transfer process occurs is unknown. In this work, we used atomistic molecular dynamics simulations and free energy calculations to characterize the essential influence of cholesterol on insertion of the GPI anchors into plasma membranes. We demonstrate, both dynamically and energetically, that in the presence of cholesterol, the tails of GPI anchors are able to penetrate inside the core of the lipid membrane spontaneously with a three-step mechanism, while in the absence of cholesterol no spontaneous insertion was observed. We ascribe the failure of insertion to the strong thermal fluctuation of lipid molecules in cholesterol-free bilayer, which generates a repulsive force in entropic origin. In the presence of cholesterol, however, the fluctuation of lipids is strongly reduced, thus decreasing the barrier for the anchor insertion. Based on this observation, we propose a hypothesis that addition of cholesterol creates vertical creases in membranes for the insertion of acyl chains. Moreover, we find that the GPI anchor could also spontaneously inserted into the boundary between cholesterol-rich and cholesterol-depleted domains. Our results shed light on the mechanism of cholesterol-mediated interaction between membrane proteins with acyl chain and plasma membranes in living cells.
The impact of electrode materials on 1/f noise in piezoelectric AlN contour mode resonators
Authors: Kim Hoe Joon , Jung Soon In , Segovia-Fernandez Jeronimo , Piazza Gianluca
Published: May 2018

This paper presents a detailed analysis on the impact of electrode materials and dimensions on flicker frequency (1/f) noise in piezoelectric aluminum nitride (AlN) contour mode resonators (CMRs). Flicker frequency noise is a fundamental noise mechanism present in any vibrating mechanical structure, whose sources are not generally well understood. 1 GHz AlN CMRs with three different top electrode materials (Al, Au, and Pt) along with various electrode lengths and widths are fabricated to control the overall damping acting on the device. Specifically, the use of different electrode materials allows control of thermoelastic damping (TED), which is the dominant damping mechanism for high frequency AlN CMRs and largely depends on the thermal properties (i.e. thermal diffusivities and expansion coefficients) of the metal electrode rather than the piezoelectric film. We have measured Q and 1/f noise of 68 resonators and the results show that 1/f noise decreases with increasing Q, with a power law dependence that is about 1/Q4. Interestingly, the noise level also depends on the type of electrode materials. Devices with Pt top electrode demonstrate the best noise performance. Our results help unveiling some of the sources of 1/f noise in these resonators, and indicate that a careful selection of the electrode material and dimensions could reduce 1/f noise not only in AlN-CMRs, but also in various classes of resonators, and thus enable ultra-low noise mechanical resonators for sensing and radio frequency applications.
Bernstein-Greene-Kruskal theory of electron holes in superthermal space plasma
Authors: Aravindakshan Harikrishnan , Kakad Amar , Kakad Bharati
Published: May 2018

Several spacecraft missions have observed electron holes (EHs) in Earth's and other planetary magnetospheres. These EHs are modeled with the stationary solutions of Vlasov-Poisson equations, obtained by adopting the Bernstein-Greene-Kruskal (BGK) approach. Through the literature survey, we find that the BGK EHs are modelled by using either thermal distribution function or any statistical distribution derived from particular spacecraft observations. However, Maxwell distributions are quite rare in space plasmas; instead, most of these plasmas are superthermal in nature and generally described by kappa distribution. We have developed a one-dimensional BGK model of EHs for space plasma that follows superthermal kappa distribution. The analytical solution of trapped electron distribution function for such plasmas is derived. The trapped particle distribution function in plasma following kappa distribution is found to be steeper and denser as compared to that for Maxwellian distribution. The width-amplitude relation of perturbation for superthermal plasma is derived and allowed regions of stable BGK solutions are obtained. We find that the stable BGK solutions are better supported by superthermal plasmas compared to that of thermal plasmas for small amplitude perturbations.
Low-lying excited states of model proteins: Performances of the CC2 method versus multireference methods
Authors: Ben Amor Nadia , Hoyau Sophie , Maynau Daniel , Brenner Valérie
Published: May 2018

A benchmark set of relevant geometries of a model protein, the N-acetylphenylalanylamide, is presented to assess the validity of the approximate second-order coupled cluster (CC2) method in studying low-lying excited states of such bio-relevant systems. The studies comprise investigations of basis-set dependence as well as comparison with two multireference methods, the multistate complete active space 2nd order perturbation theory (MS-CASPT2) and the multireference difference dedicated configuration interaction (DDCI) methods. First of all, the applicability and the accuracy of the quasi-linear multireference difference dedicated configuration interaction method have been demonstrated on bio-relevant systems by comparison with the results obtained by the standard MS-CASPT2. Second, both the nature and excitation energy of the first low-lying excited state obtained at the CC2 level are very close to the Davidson corrected CAS+DDCI ones, the mean absolute deviation on the excitation energy being equal to 0.1 eV with a maximum of less than 0.2 eV. Finally, for the following low-lying excited states, if the nature is always well reproduced at the CC2 level, the differences on excitation energies become more important and can depend on the geometry.
The Lamb wave bandgap variation of a locally resonant phononic crystal subjected to thermal deformation
Authors: Zhu Yun , Li Zhen , Li Yue-ming
Published: May 2018

A study on dynamical characteristics of a ternary locally resonant phononic crystal (PC) plate (i.e., hard scatterer with soft coating periodically disperse in stiff host matrix) is carried out in this paper. The effect of thermal deformation on the structure stiffness, which plays an important role in the PC’s dynamical characteristics, is considered. Results show that both the start and the stop frequency of bandgap shift to higher range with the thermal deformation. In particular, the characteristics of band structure change suddenly at critical buckling temperature. The effect of thermal deformation could be utilized for tuning of phononic band structures, which can promote their design and further applications.
Investigation of trapping levels in p-type Zn3P2 nanowires using transport and optical properties
Authors: Lombardi G. A. , de Oliveira F. M. , Teodoro M. D. , Chiquito A. J.
Published: May 2018

Here, we report the synthesis and structural characterization of high-quality Zn3P2 nanowires via chemical vapour deposition. Structural and morphological characterization studies revealed a reliable growth process of long, uniform, and single-crystalline nanowires. From temperature dependent transport and photoluminescence measurements, we have observed the contribution of different acceptor levels (15, 50, 70, 90, and 197 meV) to the conduction mechanisms. These levels were associated with zinc vacancies and phosphorous interstitial atoms which assigned a p-type character to this semiconductor. From time resolved photoluminescence experiments, a 91 ps lifetime decay was found. Such a fast lifetime decay is in agreement with the exciton transition along the bulk emission from high quality crystalline nanowires.
Phase-separation induced extraordinary toughening of magnetic hydrogels
Authors: Tang Jingda , Li Chenghai , Li Haomin , Lv Zengyao , Sheng Hao , Lu Tongqing , Wang T. J.
Published: May 2018

Phase separation markedly influences the physical properties of hydrogels. Here, we find that poly (N, N-dimethylacrylamide) (PDMA) hydrogels suffer from phase separation in aqueous sodium hydroxide solutions when the concentration is higher than 2 M. The polymer volume fraction and mechanical properties show an abrupt change around the transition point. We utilize this phase separation mechanism to synthesize tough magnetic PDMA hydrogels with the in-situ precipitation method. For comparison, we also prepared magnetic poly (2-acrylamido-2-methyl-propane sulfonic acid sodium) (PNaAMPS) magnetic hydrogels, where no phase separation occurs. The phase-separated magnetic PDMA hydrogels exhibit an extraordinarily high toughness of ∼1000 J m−2; while non-phase-separated magnetic PNaAMPS hydrogels only show a toughness of ∼1 J m−2, three orders of magnitude lower than that of PDMA hydrogels. This phase separation mechanism may become a new approach to prepare tough magnetic hydrogels and inspire more applications.
Diffusion length of non-equilibrium minority charge carriers in β-Ga2O3 measured by electron beam induced current
Authors: Yakimov E. B. , Polyakov A. Y. , Smirnov N. B. , Shchemerov I. V. , Yang Jiancheng , Ren F. , Yang Gwangseok , Kim Jihyun , Pearton S. J.
Published: May 2018

The spatial distribution of electron-hole pair generation in β-Ga2O3 as a function of scanning electron microscope (SEM) beam energy has been calculated by a Monte Carlo method. This spatial distribution is then used to obtain the diffusion length of charge carriers in high-quality epitaxial Ga2O3 films from the dependence of the electron beam induced current (EBIC) collection efficiency on the accelerating voltage of a SEM. The experimental results show, contrary to earlier theory, that holes are mobile in β-Ga2O3 and to a large extent determine the diffusion length of charge carriers. Diffusion lengths in the range 350–400 nm are determined for the as-grown Ga2O3, while processes like exposing the samples to proton irradiation essentially halve this value, showing the role of point defects in controlling minority carrier transport. The pitfalls related to using other popular EBIC-based methods assuming a point-like excitation function are demonstrated. Since the point defect type and the concentration in currently available Ga2O3 are dependent on the growth method and the doping concentration, accurate methods of diffusion length determination are critical to obtain quantitative comparisons of material quality.
Enhanced electrocaloric effect in lead-free organic and inorganic relaxor ferroelectric composites near room temperature
Authors: Aziguli Haibibu , Chen Xin , Liu Yang , Yang Guang , Yu Ping , Wang Qing
Published: May 2018

We study the electrocaloric effect in the composites composed of the ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer matrix and lead-free BaZr0.2Ti0.8O3 (BZT) fillers. The P(VDF-TrFE-CFE)/BZT composite with 5 vol. % BZT exhibits a high adiabatic temperature change of ΔT = 7.4 K and a large isothermal entropy change of ΔS = 30 J kg−1 K−1 under an electric field of 90 MV m−1 at room temperature. The electrocaloric response in the composites is significantly enhanced when compared to those of the constituent components, which has been attributed to the polymer-filler interfacial coupling effect. In addition, the composites display a wide operational temperature window as a result of their ferroelectric relaxor nature.
Characteristics of dust voids in a strongly coupled laboratory dusty plasma
Authors: Bailung Yoshiko , Deka T. , Boruah A. , Sharma S. K. , Pal A. R. , Chutia Joyanti , Bailung H.
Published: May 2018

A void is produced in a strongly coupled dusty plasma by inserting a cylindrical pin (∼0.1 mm diameter) into a radiofrequency discharge argon plasma. The pin is biased externally below the plasma potential to generate the dust void. The Debye sheath model is used to obtain the sheath potential profile and hence to estimate the electric field around the pin. The electric field force and the ion drag force on the dust particles are estimated and their balance accounts well for the maintenance of the size of the void. The effects of neutral density as well as dust density on the void size are studied.