bluuebunny/crossref_metadata_2025 huggingface dataset:
Intellectual Property Rights and the Conservation of Plant Biodiversity as a Common Concern of Humankind
Authors: Jaeckel Aline
Published: February 2013

This article makes the case for the obligation to conserve plant biodiversity to be classified as a common concern of humankind, to justify and indeed prescribe limitations on private intellectual property rights over plants and related processes. Within the biodiversity regime, the notion of ‘common concern of humankind’ subjects the permanent sovereignty of states over natural resources to the interests of humanity. It shifts the obligations of states from managing their own plant biodiversity towards conserving it on behalf of humankind. In contrast, TRIPS requires states to protect private intellectual property rights with little discretion to adequately balance them with public interests. This creates a dichotomy. This article argues that rather than mobilizing state sovereignty as rhetoric to distract from addressing common concerns of humankind, it should be constructed as a concept capable of facilitating these very concerns.
Stellenwert radiologischer Bildgebung nach laparoskopischem Gastric Banding
Authors: Wiesner
Published: February 2013

Durant les dernières années, le banding gastrique par laparoscopie est devenu une des opérations les plus courantes pour le traitement de patients avec une polyphagie pathologique. Deux systèmes sont utilisés dans le monde: Le LAP BAND (ASGB – Adjustable Silicone Gastric Banding) et le banding suédois (SAGB – Swedish Adjustable Gastric Banding) qui sont tous les deux implantés par laparoscopie dans la partie proximale de l'estomac environ 2 cm distalement du cardia de façon suprabursale pour diminuer le volume fonctionnel de l'estomac et stimuler ainsi un sentiment de satiété. Les deux systèmes se différencient par leur consistance, leur opacité radiologique et leur dimension, mais les mécanismes d'action et les principes techniques d'implantation de banding, d'ajustement de la lumière de l'estomac ainsi que de la perte de poids postopératoire et des contrôles radiologiques sont similaires pour les deux systèmes. Bien que les patients avec un banding de l'estomac peuvent être pris en charge complètement par les cliniciens, il est établi que des contrôles radiologiques sont indispensables non seulement pour une régulation exacte de la lumière de l'estomac mais aussi pour la perte de poids postopératoire optimale et la mise en évidence de complications postopératoires éventuelles. Ce travail décrit l'image radiologique des deux systèmes, la prise en charge radiologique de ce collectif de patients et présente un aperçu des complications postopératoires connues et quelques recommandations concernant l'approche thérapeutique.
53-jährige Patientin mit über 38 °C Fieber seit drei Wochen sowie generalisiertem Exanthem
Authors: Handschin  , Nüesch
Published: February 2013

Anhand einer Fallbeschreibung werden epidemiologische, diagnostische und therapeutische Aspekte der Zytomegalievirusinfektion besprochen. Schwerpunktmässig werden im Kommentar die Diagnostik bzw. Abklärungsschritte bei «Fever of unknown origin» (FUO) beleuchtet. Im Weiteren wird die Abschätzung des Zeitfensters, in der eine Infektion durch EBV-, CMV- oder Toxoplasmose erfolgte, anhand der Avidität erklärt.
Die Pathogenese des kolorektalen Karzinoms
Authors: Reinacher-Schick  , Schmiegel
Published: February 2013

Die Identifizierung der Adenom-Karzinom-Sequenz mit ihren korrespondierenden molekulargenetischen Veränderungen hat entscheidend zum Verständnis der Pathogenese des kolorektalen Karzinoms (KRK) beigetragen. Aufgrund des häufigen biallelischen Verlustes, bzw. der Inaktivierung bestimmter Tumorsuppressorgene (APC, p53 u.a.) wird dieser Karzinogeneseweg üblicherweise «suppressor pathway» genannt. Hierfür charakteristisch ist eine genetische Instabilität auf chromosomaler Ebene. Nicht alle genetischen Veränderungen, die in der Kolonkarzinogenese eine Rolle spielen, lassen sich jedoch in dieses lineare Tumorprogressionsmodell einordnen. So entwickelt sich ein Teil der hereditären und sporadischen KRK auf dem Boden einer genetischen Instabilität auf DNA-Ebene (nachgewiesen als sog. Mikrosatelliteninstabilität, MSI). Dieser Weg der Kolonkarzinogenese wird auch «mutator pathway» genannt. Während sich die Familiäre Adenomatöse Polyposis (FAP) dem «suppressor pathway» zuordnen lässt, folgen die hereditären nicht-polypösen kolorektalen Karzinome (HNPCC) typischerweise dem «mutator pathway». Obwohl sich wahrscheinlich die meisten MSI-Karzinome ebenfalls aus kolorektalen Adenomen entwickeln, gibt es erste Hinweise, dass ein Teil der MSI-Tumoren möglicherweise aus bestimmten hyperplastischen Polypen über sog. «serrated adenoma» entsteht (sog. «serrated pathway»). In dieser Übersicht sollen die unterschiedlichen Wege der Kolonkarzinomentstehung dargestellt werden. Neben den molekularen Veränderungen sollen die morphologischen und klinischen Korrelate, die diese Karzinogenesewege kennzeichnen, aufgezeigt werden. Abschliessend werden praxisrelevante Aspekte des Themas diskutiert.
Differentialdiagnose und Therapie der akuten Pankreatitis
Authors: Haas  , Singer
Published: February 2013

Die akute Pankreatitis wird in eine interstitielle ödematöse Pankreatitis und eine hämorrhagisch nekrotisierende Pankreatitis eingeteilt, die 80% bzw. 20% der Fälle repräsentieren. 80% aller akuten Pankeatitiden haben eine biliäre bzw. alkoholische Genese, in mehr als 10% der Fälle lässt sich keine eindeutige Ätiologie finden (akute idiopathische Pankreatitis). Die klinischen Beschwerden sind wenig spezifisch, so dass eine grosse Zahl von anderen abdominellen und extraabdominellen Erkrankungen in die Differentialdiagnose eingeschlossen werden muss. Die Diagnosesicherung erfolgt auf der Basis der klinischen Untersuchung sowie der laborchemischen und bildgebenden Diagnostik. Zu beachten ist, dass selbst bei fehlenden abdominellen Beschwerden und normwertiger Amylase- und Lipasewerte eine manifeste Pankreatitis vorliegen kann. Der Übergang in eine schwere Verlaufsform ist durch einen steilen Anstieg der Mortalitätsrate charakterisiert, so dass engmaschige Kontrollen erforderlich sind, um frühzeitig eine Identifikation dieser Hochrisikogruppe zu ermöglichen, wobei Prognoseindizes wie der Ranson-, Glasgow- und APACHE-II-Score hinzugezogen werden können. Zusätzlich stehen neue Laborparameter mit hoher prädiktiver Aussagekraft zur Verfügung. Bei einer sterilen nekrotischen Pankreatitis ist eine Antibiotikaprophylaxe indiziert, während die infizierte Nekrose eine Nekrosektomie und Lavage erfordert, die operativ oder entsprechend neueren Strategien auch endoskopisch durchgeführt werden können. Als wichtige Komplikationen gelten neben dem akuten Nierenversagen und der respiratorischen Insuffizienz die Pankreaspseudozyste und der Pankreasabszess. Die biliäre Pankreatitis nimmt eine Sonderstellung ein, da beim Nachweis eines inkarzerierten Gallensteins in der Papilla Vateri umgehend eine ERCP in Kombination mit einer Steinextraktion und Papillotomie durchzuführen ist. Noch während des gleichen Krankenhausaufenthalts sollte die elektive laparoskopische Cholezystektomie erfolgen.
52-jähriger Manager einer Chemiefirma mit unklarer Lebererkrankung, Hüftbeschwerden seit Jahren und Schwächegefühlen seit Monaten
Authors: Estlinbaum
Published: February 2013

Bei einem 52-jährigen Manager einer Chemiefirma mit anamnestisch erhöhten Leberwerten und Müdigkeit seit Monaten werden ein massiv erhöhtes Ferritin und eine Transferrinsättigung registriert. Bei hochgradigem Verdacht auf eine Hämochromatose wird das HFE-Gen bestimmt, welches eine homozygote Mutation vom Typ C282Y ergibt, was mit einer hereditären Hämochromatose zu vereinbaren ist. Die Durchführung regelmässiger Aderlässe ist die effizienteste und beste Therapie, um die Entwicklung eisenbedingter Organschäden zu verhindern, resp. zu begrenzen.
Hereditäre und erworbene Störungen mitochondrialer DNA
Authors: Walker
Published: February 2013

Mitochondriale DNA (mtDNA) kodiert 13 Strukturproteine, die für die Funktion der Atmungskette notwendig sind. Das nur 16,5 kbp große und zirkuläre Doppelstrang-DNA-Molekül liegt in jeder Zelle in tausendfacher Kopie vor und wird maternal vererbt. Mutationen (Punktmutationen, Deletionen) als auch eine quantitative Verminderung der Kopienzahl (mtDNA-Depletion) können entweder vererbt werden, spontan auftreten oder durch Noxen erworben werden. Beim Erwachsenen werden insbesondere neurologische Ausfallserscheinungen beobachtet, desweiteren Myopathie, Kardiomyopathie, Diabetes mellitus und Laktatazidose, seltener sind hämatologische und renale Manifestationen. Es können einzelne oder mehrere Organsysteme gleichzeitig betroffen sein. MtDNA-Mutationen können auch im Rahmen von Alterungsvorgängen, Tumorerkrankungen und durch Noxen, wie z. B. Alkohol erworben werden. Sie sind aber dabei vermutlich nicht von zentraler pathogenetischer Bedeutung. Erworbene qualitative und quantitative mtDNA-Alterationen sind wahrscheinlich ursächlich für die Langzeitnebenwirkungen u. a. von Doxorubicin, von Reverse-Transkriptase-Inhibitoren und weiteren antiviralen Nukleosidanaloga verantwortlich. Auch Fettumverteilungsstörungen (Madelungscher Fetthals und Lipodystrophie bei HIV-Patienten unter antiretroviraler Langzeitmedikation) werden mit mtDNA-Alterationen assoziiert. Die therapeutischen Ansätze mit Vitaminen, Radikalfängern und L-Carnitin zeigten bisher nur unzureichende Ergebnisse.
Gentherapie: Neue Entwicklungen
Authors: Mohr  , Geissler
Published: February 2013

Das Prinzip der Gentherapie beruht auf dem Transfer genetischen Materials in geeignete Zielzellen, um dort eine spezifische therapeutische Wirkung zu erzielen. Neben genetischen Erkrankungen, bei denen der Ersatz fehlender Genprodukte oder die Korrektur eines defekten Gens das therapeutische Prinzip darstellt, stellen maligne Erkrankungen und zunehmend auch andere erworbene Erkrankungen Ziele gentherapeutischer Ansätze dar. Die zentrale Voraussetzung für eine erfolgreiche Gentherapie besteht im sicheren und therapeutisch wirksamen Transfer therapeutischer Gene in spezifische Zielzellen. Für diesen Gentransfer stehen eine Vielfalt viraler und nichtviraler Vektoren zur Verfügung. Nichtvirale Vektoren weisen im Vergleich zu viralen Vektoren eine deutlich geringere Effizienz beim Gentransfer auf, verfügen aber auch über entscheidende Vorteile, da sie DNA von nahezu unbegrenzter Grösse transferieren können und deutlich weniger immunogen sind. Zur weiteren Verbesserung nichtviraler Vektoren wird versucht, ihnen virusähnliche Funktionen hinzuzufügen, um künstliche, virusähnliche Vektoren zu entwickeln. Natürliche Viren stellen hingegen hochentwickelte Strukturen für den Transfer von Nukleinsäuren dar, die in abgewandelter Form als virale Vektoren verwendet werden können. Für gentherapeutische Ansätze, die auf einer dauerhaften Genexpression basieren, wie z.B. der Korrektur eines Enzymdefektes oder der Manipulation von hämatopoetischen Stammzellen, kommen vor allem Retroviren, Adeno-assoziierte Viren (AAV) und neuerdings auch Lentiviren in Frage, die in der Lage sind, DNA in das Wirtsgenom zu integrieren. Adenoviren stellen hingegen sehr effiziente Vektoren für eine vorübergehende Genexpression dar und eignen sich daher besonders für die Therapie maligner Tumoren. Neue Entwicklungen viraler Vektoren zielen auf eine Reduktion ihrer Immunogenität und Toxizität sowie die Vergrösserung ihrer Kapazität für therapeutische Gene. Viren, die sich selektiv nur in Tumorzellen vermehren und diese abtöten können, stellen ein neuartiges Prinzip viraler Vektoren dar, deren Effizienz durch die Integration therapeutischer Gene noch erhöht werden kann.
Immuntherapie: Neue Entwicklungen
Authors: Geissler  , Weth
Published: February 2013

Trotz enormer Fortschritte in den letzten Jahren beim Verständnis der Regulation und Aktivierung antiviraler und antitumoraler Immunität, befindet sich das Gebiet der Immuntherapie gegen Tumoren, chronische Virus- und Autoimmunerkrankungen noch in einem frühen Entwicklungsstadium. Aufgrund der ausserordentlichen Diversität dieses Forschungsgebietes fokussiert diese Übersicht auf neue Entwicklungen im Bereich der Tumor-Immuntherapie. Viele bisherige immuntherapeutische Strategien, obwohl vielversprechend in präklinischen Modellen, zeigten nur mässigen klinischen Erfolg. Durch die Identifizierung neuer Tumorantigene mittels molekularer Methoden und das verbesserte Verständnis grundlegender Funktionen des Immunsystems wurde aber in den letzten Jahren der Grundstein für zukünftige, erfolgreiche, immuntherapeutische Ansätze gegen Tumore gelegt. Die Verwendung dendritischer Zellen als zelluläres Adjuvans zur Tumorantigenvakzinierung ist ein potentiell sicherer und vielversprechender antitumoraler Therapieansatz. Die bisher durchgeführten klinischen Studien besassen aber ein Defizit bezüglich der Korrelation von klinischem Verlauf und Monitoring der Immuneffektoren nach Tumorvakzinierung. Diese wichtige Korrelierung kann nun aber mittels neuer immunologischer Techniken, die Immuneffektoren auf Einzelzellebene charakterisieren und in vivo verfolgen können, durchgeführt werden. Für zukünftige immuntherapeutische klinische Studien müssen standardisierte Kriterien für Qualitätskontrollen und Studienprotokolle geschaffen werden. Damit können prognostische Parameter für bestimmte Patientenuntergruppen, optimierte Vakzinierungsprotokolle und letztendlich auch neue immunologisch-molekulare Surrogatmarker für die Diagnostik von Tumoren und Tumormetastasen entwickelt werden.
Molekulare Virologie der Hepatitis C
Authors: Moradpour  , Brass  , Gosert  , Wölk  , Blum
Published: February 2013

Die Hepatitis C stellt weltweit eine der häufigsten chronischen Virusinfektionen dar und ist mit ihren Spätfolgen Leberzirrhose und hepatozelluläres Karzinom mit einer erheblichen Morbidität und Mortalität assoziiert. Die Behandlungsmöglichkeiten sind limitiert und eine präventive Vakzine steht noch nicht zur Verfügung. Zudem sind grundlegende Aspekte des viralen Lebenszyklus noch ungeklärt. In diesem Beitrag werden aktuelle Konzepte der molekularen Virologie der Hepatitis C kurz zusammengefasst. Dabei wird auch auf die Bedeutung von in vitro- und in vivo-Modellen der Hepatitis-C-Virus Replikation eingegangen. Schliesslich werden neue antivirale Strategien skizziert, die sich aus einem verbesserten Verständnis des viralen Lebenszyklus ergeben.
Exazerbation einer chronischen Hepatitis B nach Absetzen der antiretroviralen Therapie bei HIV-Infektion
Authors: Khanna
Published: February 2013

Eine HIV-infizierte Patientin stellt sich mit Ikterus und erhöhten Leberwerten vor. Als Ursache wird eine Exazerbation einer chronischen Hepatitis B nach Absetzen des Lamivudins im Rahmen der antiretroviralen Therapie angenommen.
Die AB0-inkompatible Nierentransplantation: Top oder Flop?
Authors: Dickenmann
Published: February 2013

Blutgruppeninkompatibilität zwischen Spender und Empfänger galt bisher als Kontraindikation für eine Nierentransplantation. Die Resultate der neusten Zeit zeigen aber, dass diese Art der Nierentransplantation mit einer entsprechenden Technik sicher und mit vergleichbar guten Resultaten wie Blutgruppen-übereinstimmende Transplantationen durchgeführt werden kann. Damit eröffnet sich eine neue Möglichkeit, den Organmangel in der Schweiz zu verringern.
Perikarderguss bei einer 21-jährigen Angestellten
Authors: Wiggli  , Lüthy  , Tyndall  , Vogt
Published: February 2013

Wir beschreiben die Abklärung bei einer 21-jährigen Patientin mit langsam progredienter Verschlechterung des Allgemeinzustandes und Perikarderguss. Die Klinik und die Untersuchungen ergaben die Diagnose eines Lupus erythemathodes systemicus. Wir weisen auf die wichtigsten Merkmale der Krankheit und auf «red flags» in Diagnostik und Therapie hin.
Transient overexpression of TGFBR3 induces apoptosis in human nasopharyngeal carcinoma CNE-2Z cells
Authors: Zheng Fangfang , He Kaiwen , Li Xin , Zhao Dan , Sun Fei , Zhang Yu , Nie Dan , Li Xingda , Chu Wenfeng , Sun Yan , Lu Yanjie
Published: February 2013

NPC (nasopharyngeal carcinoma) is a common malignancy in southern China without defined aetiology. Recent studies have shown that TGFBR3 (transforming growth factor type III receptor, also known as betaglycan), exhibits anticancer activities. This study was to investigate the effects of TGFBR3 on NPC growth and the mechanisms for its actions. Effects of TGFBR3 overexpression on cell viability and apoptosis were measured by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide], AO/EB (acridine orange/ethidium bromide) staining and electron microscopy in human NPC CNE-2Z cells. The expression of apoptosis-related proteins, p-Bad, Bad, XIAP (X-linked inhibitor of apoptosis), AIF (apoptosis-inducing factor), Bax and Bcl-2, was determined by Western blot or immunofluorescence analysis. Caspase 3 activity was measured by caspase 3 activity kit and [Ca2+]i (intracellular Ca2+ concentration) was detected by confocal microscopy. Transfection of TGFBR3 containing plasmid DNA at concentrations of 0.5 and 1 μg/ml reduced viability and induced apoptosis in CNE-2Z in concentration- and time-dependent manners. Forced expression of TGFBR3 up-regulated pro-apoptotic Bad and Bax protein, and down-regulated anti-apoptotic p-Bad, Bcl-2 and XIAP protein. Furthermore, transient overexpression of TGFBR3 also enhanced caspase 3 activity, increased [Ca2+]i and facilitated AIF redistribution from the mitochondria to the nucleus in CNE-2Z cells, which is independent of the caspase 3 pathway. These events were associated with TGFBR3-regulated multiple targets involved in CNE-2Z proliferation. Therefore transient overexpression of TGFBR3 may be a novel strategy for NPC prevention and therapy.
Structure and properties of Mn4Cl9: An antiferromagnetic binary hyperhalogen
Authors: Li Yawei , Zhang Shunhong , Wang Qian , Jena Puru
Published: February 2013

Calculations based on density functional theory show that the structure of Mn4Cl9 anion is that of a Mn atom at the core surrounded by three MnCl3 moieties. Since Mn is predominantly divalent and MnCl3 is known to be a superhalogen with a vertical detachment energy (VDE) of 5.27 eV, Mn4Cl9 can be viewed as a hyperhalogen with the formula unit Mn(MnCl3)3. Indeed, the calculated VDE of Mn4Cl9 anion, namely 6.76 eV, is larger than that of MnCl3 anion. More importantly, unlike previously discovered hyperhalogens, Mn4Cl9 is the first such hyperhalogen species composed of only two constituent atoms. We further show that Mn4Cl9 can be used as a ligand to design molecules with even higher VDEs. For example, Li[Mn(MnCl3)3]2 anion has a VDE of 7.26 eV. These negatively charged clusters are antiferromagnetic with most of the magnetic moments localized at the Mn sites. Our studies show new pathways for creating binary hyperhalogens.
The localization tensor for the H2 molecule: Closed formulae for the Heitler-London and related wavefunctions and comparison with full configuration interaction
Authors: Angeli Celestino , Bendazzoli Gian Luigi , Evangelisti Stefano
Published: February 2013

A closed analytical formula for the localization tensor of the Heitler-London and related wavefunctions of the hydrogen molecule is given. For the wavefunctions with a well defined nature, the various contributions of the analytical expressions can be interpreted in simple terms. The results are then compared with full configuration interaction calculations, showing that the main contributions to the localization tensor for the ground state wavefunction are caught by the very simple wavefunctions here considered.
In situ granular charge measurement by free-fall videography
Authors: Waitukaitis S. R. , Jaeger H. M.
Published: February 2013

We present the design and performance characterization of a new experimental technique for measuring individual particle charges in large ensembles of macroscopic grains. The measurement principle is qualitatively similar to that used in determining the elementary charge by Millikan in that it follows individual particle trajectories. However, by taking advantage of new technology we are able to work with macroscopic grains and achieve several orders of magnitude better resolution in charge to mass ratios. By observing freely falling grains accelerated in a horizontal electric field with a co-falling, high-speed video camera, we dramatically increase particle tracking time and measurement precision. Keeping the granular medium under vacuum, we eliminate air drag, leaving the electrostatic force as the primary source of particle accelerations in the co-moving frame. Because the technique is based on direct imaging, we can distinguish between different particle types during the experiment, opening up the possibility of studying charge transfer processes between different particle species. For the ∼300 μm diameter grains reported here, we achieve an average acceleration resolution of ∼0.008 m/s2, a force resolution of ∼500 pN, and a median charge resolution ∼6× 104 elementary charges per grain (corresponding to surface charge densities ∼1 elementary charges per μm2). The primary source of error is indeterminacy in the grain mass, but with higher resolution cameras and better optics this can be further improved. The high degree of resolution and the ability to visually identify particles of different species or sizes with direct imaging make this a powerful new tool to characterize charging processes in granular media.
Polarizability effects in molecular dynamics simulations of the graphene-water interface
Authors: Ho Tuan A. , Striolo Alberto
Published: February 2013

The importance of including the polarizability of both water and graphene in molecular dynamics simulations of the water/graphene system was quantified. A thin film of either rigid single point charge extended (SPC/E) water or polarizable simple 4-site water model with Drude polarizability (SWM4_DP) water on non-polarizable and polarizable graphene surfaces was simulated. The graphene surface was either maintained neutral or charged, positively and negatively. The results suggest that SPC/E and SWM4_DP water models yield very similar predictions for the water structural properties on neutral non-polarizable graphene, although they yield slightly different dynamical properties of interfacial water on neutral non-polarizable graphene. More pronounced were the differences obtained when graphene was modeled with a polarizable force field. In particular, the polarizability of graphene was found to enhance the number of interfacial SWM4_DP water molecules pointing one of their OH bonds towards the neutral surface. Despite this structural difference, the dynamical properties predicted for the interfacial SWM4_DP water were found to be independent on polarizability as long as the polarizability of a carbon atom is smaller than α = 0.878 Å. On charged graphene surfaces, the effect of polarizability of graphene on structural properties and some dynamical properties of SWM4_DP water is negligible because electrostatic forces due to surface charge dominate polarization forces, as expected. For all cases, our results suggest that the hydrogen bond network is insensitive to the polarizability of both water and graphene. Understanding how these effects will determine the accumulation of ions near neutral or charged graphene could have important implications for applications in the fields of energy storage and water desalination.
Unified explanation of the anomalous dynamic properties of highly asymmetric polymer blends
Authors: Ngai K. L. , Capaccioli S.
Published: February 2013

In polymer blends where the glass transition temperatures of the two components differ greatly, the segmental α-relaxation and the chain dynamics of the faster component exhibit a number of anomalous properties not seen before in homopolymers, and not explainable by conventional theory of polymer dynamics. In the first part of this paper, these anomalous properties are collected altogether and made known. We show their interconnections and emphasize the necessity of explaining all of them together if the objective is to fully solve the problem. In the second part, the predictions from a single theoretical framework, namely, the coupling model, are applied to explain the anomalous properties in toto.
Liquid-vapor phase diagram and surface properties in oppositely charged colloids represented by a mixture of attractive and repulsive Yukawa potentials
Authors: Chapela Gustavo A. , del Río Fernando , Alejandre José
Published: February 2013

The liquid-vapor phase diagrams of equal size diameter σ binary mixtures of screened potentials have been reported for several ranges of interaction using Monte Carlo simulation methods [J. B. Caballero, A. M. Puertas, A. Fern´andez-Barbero, F. J. de las Nieves, J. M. Romero-Enrique, and L. F. Rull, J. Chem. Phys. 124, 054909 (2006)10.1063/1.2159481; A. Fortini, A.-P. Hynninen, and M. Dijkstra, J. Chem. Phys. 125, 094502 (2006)10.1063/1.2335453]. Both works report controversial results about the stability of the phase diagram with the inverse Debye screening length κ. Caballero found stability for values of κσ up to 20 while Fortini reported stability for κσ up to 20 while Fortini reported stability for κσ ⩽ 4. In this work a spinodal decomposition process where the liquid and vapor phases coexist through an interface in a slab geometry is used to obtain the phase equilibrium and surface properties using a discontinuous molecular dynamics simulations for mixtures of equal size particles carrying opposite charge and interacting with a mixture of attractive and repulsive Yukawa potentials at different values of κσ. An crude estimation of the triple point temperatures is also reported. The isothermal-isobaric method was also used to determine the phase stability using one phase simulations. We found that liquid-vapor coexistence is stable for values of κσ > 20 and that the critical temperatures have a maximum value at around κσ = 10, in agreement with Caballero et al. calculations. There also exists a controversy about the liquid-vapor envelope stability of the pure component attractive Yukawa model which is also discussed in the text. In addition, details about the equivalence between continuous and discontinuous molecular dynamics simulations are given, in the Appendix, for Yukawa and Lennard-Jones potentials.
Reduced threading dislocation densities in high-T/N-rich grown InN films by plasma-assisted molecular beam epitaxy
Authors: Loitsch Bernhard , Schuster Fabian , Stutzmann Martin , Koblmüller Gregor
Published: February 2013

We explore the effect of growth kinetics on the structural properties of In-polar InN films on GaN templates grown near the thermal dissociation limit by plasma-assisted molecular beam epitaxy. Unlike the common growth temperature limit (T ≈ 500 °C) for In-polar InN grown under In-rich conditions, slightly N-rich conditions are demonstrated to shift the available growth temperature window to much higher temperatures (by >50 °C). InN films grown in this high-T/N-rich regime show significantly reduced off-axis X-ray diffraction rocking curve peak widths and record low threading dislocation densities (TDD ∼ 4 × 109 cm−2) even for film thicknesses <1 μm, as compared to state of the art In-rich growth. The reduction of TDD is attributed to more effective TD inclination and annihilation under N-rich growth, delineating prospective routes for improved InN-based materials.
Ultra-broadband simultaneous superluminal phase and group velocities in non-Foster epsilon-near-zero metamaterial
Authors: Hrabar Silvio , Krois Igor , Bonic Ivan , Kiricenko Aleksandar
Published: February 2013

Experimental investigation of ultra-broadband simultaneous superluminal phase and group velocity in recently introduced epsilon-near-zero (ENZ) non-Foster metamaterial is reported. The phase and group velocities were extracted both from the measurements of scattering parameters in the frequency domain and the measurements of propagation time of broadband Gaussian pulse in time domain. Reported superluminal effects are extremely broadband (relative bandwidth of 180% (1:20)) and they are fundamentally different from widely reported narrowband experiments based on the anomalous dispersion. The phenomenon of simultaneous superluminal phase and group velocities may find applications in transformation electromagnetic devices and in communication systems.
Stripe order related in-plane fourfold symmetric superconductivity in La1.45Nd0.4Sr0.15CuO4 single crystal
Authors: Teng M. L. , Yin Y. W. , Xie L. , Li X. G.
Published: February 2013

The in-plane fourfold symmetry of the upper critical field Hc2 in a stripe-ordered La1.45Nd0.4Sr0.15CuO4 single crystal has been observed through measuring the out-of-plane resistivity ρc by rotating the crystal around its c-axis in magnetic fields parallel to the ab-plane of the crystal. It was found that the upper critical field Hc2 takes maxima (minima) for magnetic fields along Cu-O-Cu (Cu-Cu) direction, suggesting an intrinsic fourfold superconductivity. The results should be closely related to the special structure of the charge stripes which are along Cu-O-Cu direction and rotated 90° in adjacent CuO2 planes, and the fourfold symmetry behaviors in Hc2 and ρc can be well described by a scaling method. The stripe phase can also lead to a fourfold vortex pinning effect which is confirmed by the angular dependence of the irreversibility field Hirr and the activation energy U for flux motion.
Transient lattice distortion induced by ultrashort heat pulse propagation through thin film metal/metal interface
Authors: Oguz Er Ali , Chen Jie , Tang Jau , Rentzepis Peter M.
Published: February 2013

Phonon propagation across the Cu/Ag(111) interface and transient structural disorder in Ag(111) crystal, after excitation of 18 nm copper layer with UV femtosecond pulses has been studied by means of picosecond time resolved X-ray diffraction. The lattice disorder was measured by the changes in peak shift and broadening of the XRD rocking curve. A blast force was formed within 2 ps after fs UV irradiation. After fast initial expansion and contraction, a sharp oscillation is observed, while the subsequent oscillations were found to be broader due to out-of phase relationship between the sound waves in the copper and silver layers.
The increase in conductance of a gold single atom chain during elastic elongation
Authors: Tavazza F. , Barzilai S. , Smith D. T. , Levine L. E.
Published: February 2013

The conductance of monoatomic gold wires has been studied using ab initio calculations and the transmission was found to vary with the elastic strain. Counter-intuitively, the conductance was found to increase for the initial stages of the elongation, where the structure has a zigzag shape and the bond angles increase from ≈140° toward ≈160°. After a certain elongation limit, where the angles are relatively high, the bond length elongation associated with a Peierls distortion reverses this trend and the conductance decreases. These simulations are in good agreement with previously unexplained experimental results.
Coercivity dynamics and origin of time-delayed magneto-optical hysteresis loops in pump-probe Kerr spectroscopy
Authors: Li Shufa , Chen Zhifeng , Cheng Chuyuan , Li Jiaming , Zhou Shiming , Lai Tianshu
Published: February 2013

Time-resolved magneto-optical Kerr effect (TR-MOKE) is used to measure hysteresis loops of a magnetic film at a different delayed time after femtosecond laser excitations. Coercivity dynamics of the magnetic film is obtained from TR-MOKE loops as usual. However, we point out that the dynamics of coercivity does not reflect the evolution of initial coercivity shown by the initial hysteresis loop with no laser excitation, but that of the final coercivity under laser excitation, where the final coercivity means one given by the hysteresis loop measured at a negative pump-probe delay time under pump excitation. TR-MOKE loops usually cannot track the evolution of coercivity of a magnetic system upon strong laser shot, and can do that only when the magnetic system is reversible under a low excitation. The oscillatory recovery behavior of the final coercivity is observed, and is ascribed to metastability of zero magnetization state.
Structural, electronic, magnetic and spin dependent transport properties of Fe/CaS/Fe (001) heterostructures
Authors: Vlaic P. , Burzo E. , Carva K.
Published: February 2013

Structural, electronic, and magnetic properties of Fe/CaS (001) interfaces and Fe/CaS/Fe (001) heterostructures have been studied by means of a self-consistent Green's function technique for surface and interfaces implemented within the tight-binding linear muffin-tin orbital formalism. Spin dependent transport properties of the Fe/CaS/Fe (001) tunnel junctions with thin and intermediate barriers, in the current-perpendicular-to-plane geometry, have been determined by means of Kubo-Landauer approach implemented within the tight-binding linear muffin-tin orbital formalism. A small charge rearrangement is evidenced at the Fe/CaS (001) interfaces. The iron interfacial magnetic moments are enhanced over the bulk value. A small exchange coupling with the sign depending on the Fe/CaS (001) interface geometric structure and the strength decaying exponentially with the barrier is evidenced. Interfacial charge transfer, interface iron magnetic moments, and tunneling currents are sensitive to the interfacial structure. Interface resonant states have a decisive role in the tunneling process and the main contribution to the current in the ferromagnetic state of the junction is given by the minority-spin electrons.
Effect of A-site La, Ba, and Sr doping on the threshold field and characteristic temperatures of PbSc0.5Nb0.5O3 relaxor studied by acoustic emission
Authors: Dul'kin E. , Mihailova B. , Gospodinov M. , Roth M.
Published: February 2013

The behavior of the temperature of the dielectric-permittivity maximum Tm, the intermediate temperature T*, and the Burns temperature Td in stoichiometric PbSc0.5Nb0.5O3 (PSN) as well as in PSN heavily doped on the A-site by La (PSN-La), Ba (PSN-Ba), and Sr (PSN-Sr) was studied by means of acoustic emission (AE) under an external dc electric field (E). For all compounds, Tm exhibits a non-trivial behavior when applying E, namely, it initially decreases with the increase of E, attain a minimum at a threshold field Eth, ranging from 0.55 kV/cm for PSN to 0.25 kV/cm for PSN-Sr, and then Tm starts to increase with further increase of E. The minimum of Tm is accompanied by a pronounced maximum of the AE count rate Ṅ, which at Eth varies from 10.0 s−1 to 3.0 s−1 for all the compounds, respectively. The similarities and difference between PSN, PSN-Ba, PSN-La, and PSN-Sr with respect to Eth, the Ṅ, and the normalized AE parameter η are discussed from the viewpoint of three mechanisms: (i) chemically induced random local electric fields due to the extra charge on the A-site ion, (ii) disturbance of the system of stereochemically active lone-pair electrons of Pb2+ by the isotropic outermost electron shell of the substituting ion, and (iii) change in the tolerance factor and elastic fields related to the larger ionic radius of the substituting A-site ion. The characteristic temperatures T* and Td also exhibit a non-trivial behavior under E, which is better pronounced for pure PSN than for the A-site-substituted PSN compounds.
Cross-sectional sizes and emission wavelengths of regularly patterned GaN and core-shell InGaN/GaN quantum-well nanorod arrays
Authors: Liao Che-Hao , Chang Wen-Ming , Yao Yu-Feng , Chen Hao-Tsung , Su Chia-Ying , Chen Chih-Yen , Hsieh Chieh , Chen Horng-Shyang , Tu Charng-Gan , Kiang Yean-Woei , Yang C. C. , Hsu Ta-Cheng
Published: February 2013

The cross-sectional sizes of the regularly patterned GaN nanorods (NRs) and InGaN/GaN quantum-well (QW) NRs of different heights and different hexagon orientations, which are grown on the patterned templates of different hole diameters, pitches, and crystal orientations, are compared. It is found that the cross-sectional size of the GaN NR, which is formed with the pulsed growth mode, is mainly controlled by the patterned hole diameter, and the thickness of the sidewall QW structure is mainly determined by the NR height. The cross-sectional size variation of GaN NR is interpreted by the quasi-three-dimensional nature of atom supply amount for precipitating a two-dimensional disk-shaped NR segment. The variation of the sidewall QW structure is explained by the condition of constituent atom supply in the gap volume between the neighboring NRs. Also, we compare the cathodoluminescence emission wavelengths among those samples of different growth conditions. Generally speaking, the QW NR with a smaller height, a larger cross-sectional size, or a larger pitch has a longer emission wavelength.
Is thermoelectric conversion efficiency of a composite bounded by its constituents?
Authors: Yang Y. , Ma F. Y. , Lei C. H. , Liu Y. Y. , Li J. Y.
Published: February 2013

We analyze the conversion efficiency of a bilayered thermoelectric composite, and conclude that thermoelectric conversion efficiency of a composite is not bounded by its constituents, and can be higher than all its constituents in the absence of size and interface effects. Conditions on constituent phases for enhanced conversion efficiency are also identified, and the upper bound on their conversion efficiency is established. This points to a new route for high efficiency thermoelectric materials.
Effect of inclusion of grasses and wet hulless-barley distillers’ grains on the fermentation and nutritive quality of oat straw- and straw-grass silages in Tibet
Authors: Yuan XianJun , Yu ChengQun , Li ZhiHua , Shimojo M. , Shao Tao
Published: February 2013

In order to enlarge the feed resources in Tibet, oat straw was conserved as silage by combining with tall fescue and wet hulless-barley distillers’ grains (WHDG). In Experiment 1, oat straw was ensiled with four levels of tall fescue (0, 20, 40 or 60% of fresh weight) in laboratory silos for 30 days. Ensiling oat straw with tall fescue significantly increased (P < 0.05) lactic acid and water-soluble carbohydrate contents, and significantly (P < 0.05) decreased acetic acid, propionic acid, butyric acid and total volatile fatty acid concentrations. The values of pH and ammonia/total N decreased with the increase in tall fescue ratios. There were no significant differences (P > 0.05) in pH value between 40 and 60% tall fescue inclusion silages. To maximise the use of straw, it was suggested that 40% tall fescue inclusion was proper for further study. In Experiment 2, mixture of tall fescue and oat straw (6/4) were ensiled with 0, 10, 20 or 30% WHDG, triplicate silos for each treatment were opened on 7, 14, 30 and 60 days after ensiling, respectively, the fermentation characteristics and in vitro rumen degradability were analysed. WHDG addition significantly improved the fermentation quality of mixed silages, indicated by significantly lower (P < 0.05) pH, ammonia/total N , butyric acid and propionic acid concentrations and significantly higher (P < 0.05) DM and lactic acid content than the control. WHDG addition silages also showed higher crude protein contents, and lower neutral detergent fibre and acid detergent fibre content. These results suggest that adding WHDG to mixture of oat straw and tall fescue before ensiling appears to be a feasible strategy to improve the fermentation and nutritive quality of straw-grass silage.
CO2 generation by calcified invertebrates along rocky shores of Brittany, France
Authors: Hily Christian , Grall Jacques , Chauvaud Laurent , Lejart Morgane , Clavier Jacques
Published: February 2013

Many autochthonous and alien macroinvertebrates of the intertidal zone are biocalcifiers, and the present study proposes a first assessment of their calcimass and their annual calcium carbonate (CaCO3) production at a regional scale, along 500 km of the coastline of Brittany, France, which represents a wide range of the rocky-shore habitats commonly encountered in the north-eastern Atlantic region. All sites considered together gave a mean calcimass estimate of 5327 g m–2. The corresponding mean CaCO3 gross production was 2584 g m–2 year–1. The net production (including dissolution) by biocalcification was 2384 g CaCO3 m–2 year–1. Estimations of CO2 production via both calcification and respiration were carried out in particular for the phylum Mollusca and for crustacean barnacles, dominating in terms of calcimass. Mean CO2 production obtained by summing CO2 fluxes related to net CaCO3 production and respiration for all sampled sites was 22.9 mol m–2 year–1. These results illustrate the significance of CO2 production during biogenic CaCO3 precipitation of intertidal invertebrates in such temperate coastal environment compared with tropical zones and the contribution of the shelves to the global CaCO3 budget.
Life form and preference can drive spatial relationships among plant species in semi-arid rangelands of middle Iran
Authors: Khojasteh Farzaneh , Chahouki Mohammad Ali Zare , Azarnivand Hossein , Kikvidze Zaal
Published: February 2013

The interaction among species is one of the most important factors influencing the distribution of plants in a given habitat. Vegetation of arid rangelands often appears patchy with many herbaceous species associated with shrub species. It was hypothesised that plant interactions among different life forms together with the effect of grazing preference generate this type of spatial distribution of plant species in the semi-arid rangelands of middle Iran. Spatial patterns and associations were quantitatively analysed using Hopkins’ index and Chi-square tests to establish links between spatial relationships, plant life forms and preference by grazers on the south foothills of the Taleghan ranges, Alborz Province. Data were collected from three geographical sites with different dominant species and clumped patterns of plant spatial distributions for these species were detected. These spatial patterns were probably generated by the interplay of life form-dependent facilitative interactions among plants and the grazing pressure on preferred species rather than due to their intrinsic characters. In the study sites, grass species were significantly more frequently observed in the vicinity of nurse species than in open areas. It was also found that plant-plant interactions may change in response to changes in environmental conditions, such as soil characters and the benefits achieved by the beneficiary species from being associated with nurse species. All preferred perennial species were spatially associated with shrub species (Astragalus gossypinus Fischer and Thymus kotschyanus Boiss & Hohen), while nurse species that just physically protect the beneficiary species from grazing (e.g. A. gossypinus) did not associate with non-preferred species (e.g. Stipa barbata Desf). Instead, these non-preferred species may positively aggregate with nurse plants showing other beneficial characteristics such as nitrogen fixation and improvement of soil conditions.
Prospective isolation of human embryonic stem cell-derived cardiovascular progenitors that integrate into human fetal heart tissue
Authors: Ardehali Reza , Ali Shah R. , Inlay Matthew A. , Abilez Oscar J. , Chen Michael Q. , Blauwkamp Timothy A. , Yazawa Masayuki , Gong Yongquan , Nusse Roeland , Drukker Micha , Weissman Irving L.
Published: February 2013

A goal of regenerative medicine is to identify cardiovascular progenitors from human ES cells (hESCs) that can functionally integrate into the human heart. Previous studies to evaluate the developmental potential of candidate hESC-derived progenitors have delivered these cells into murine and porcine cardiac tissue, with inconclusive evidence regarding the capacity of these human cells to physiologically engraft in xenotransplantation assays. Further, the potential of hESC-derived cardiovascular lineage cells to functionally couple to human myocardium remains untested and unknown. Here, we have prospectively identified a population of hESC-derived ROR2+/CD13+/KDR+/PDGFRα+cells that give rise to cardiomyocytes, endothelial cells, and vascular smooth muscle cells in vitro at a clonal level. We observed rare clusters of ROR2+cells and diffuse expression of KDR and PDGFRα in first-trimester human fetal hearts. We then developed an in vivo transplantation model by transplanting second-trimester human fetal heart tissues s.c. into the ear pinna of a SCID mouse. ROR2+/CD13+/KDR+/PDGFRα+cells were delivered into these functioning fetal heart tissues: in contrast to traditional murine heart models for cell transplantation, we show structural and functional integration of hESC-derived cardiovascular progenitors into human heart.
Intricate interplay between astrocytes and motor neurons in ALS
Authors: Phatnani Hemali P. , Guarnieri Paolo , Friedman Brad A. , Carrasco Monica A. , Muratet Michael , O’Keeffe Sean , Nwakeze Chiamaka , Pauli-Behn Florencia , Newberry Kimberly M. , Meadows Sarah K. , Tapia Juan Carlos , Myers Richard M. , Maniatis Tom
Published: February 2013

Significance

Although ALS is a motor neuron disease, processes within glial cells contribute significantly to motor neuron-specific degeneration. Using a mouse model of ALS, we identified cell autonomous and nonautonomous changes in gene expression in motor neurons cocultured with glia. We also found a remarkable concordance between the cell culture data and expression profiles of whole spinal cords and acutely isolated spinal cord cells during disease progression in this model. We identified changes in the expression of specific genes and signaling pathways that may contribute to motor neuron degeneration in ALS, among which are TGF-β signaling pathways.
Asymmetric gibberellin signaling regulates vacuolar trafficking of PIN auxin transporters during root gravitropism
Authors: Löfke Christian , Zwiewka Marta , Heilmann Ingo , Van Montagu Marc C. E. , Teichmann Thomas , Friml Jiří
Published: February 2013

Gravitropic bending of plant organs is mediated by an asymmetric signaling of the plant hormone auxin between the upper and lower side of the respective organ. Here, we show that also another plant hormone, gibberellic acid (GA), shows asymmetric action during gravitropic responses. Immunodetection using an antibody against GA and monitoring GA signaling output by downstream degradation of DELLA proteins revealed an asymmetric GA distribution and response with the maximum at the lower side of gravistimulated roots. Genetic or pharmacological manipulation of GA levels or response affects gravity-mediated auxin redistribution and root bending response. The higher GA levels at the lower side of the root correlate with increased amounts of PIN-FORMED2 (PIN2) auxin transporter at the plasma membrane. The observed increase in PIN2 stability is caused by a specific GA effect on trafficking of PIN proteins to lytic vacuoles that presumably occurs downstream of brefeldin A-sensitive endosomes. Our results suggest that asymmetric auxin distribution instructive for gravity-induced differential growth is consolidated by the asymmetric action of GA that stabilizes the PIN-dependent auxin stream along the lower side of gravistimulated roots.