bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation of natural red colorants from fermented broth using ionic liquid-based aqueous two-phase systems
Authors: Ventura Sónia P M , Santos-Ebinuma Valéria C , Pereira Jorge F B , Teixeira Maria F S , Pessoa Adalberto , Coutinho João A P
Published: March 2013

There is a growing demand for natural colorants. This is prompting the search for new alternative and “benign” separation systems allowing higher recoveries, extraction yields, and selectivities. This work investigates the use of aqueous two-phase systems (ATPS) based on ionic liquids as extraction processes for the recovery of red colorants from the fermented broth of Penicillium purpurogenum DPUA 1275. Several ATPS based on quaternary ammonium and imidazolium were studied in this work aiming at separating the red colorants produced from the remaining colorants and contaminant proteins present in the fermented broth. The results suggest that the red colorants can be isolated by an appropriate manipulation of some of the process conditions, such as the use of quaternary ammonium with short alkyl chains, alkaline media, and short tie-line lengths (extraction point systems with lower concentrations of ionic liquid). These conditions allow large partition coefficients for the red colorants (K  red = 24.4 ± 2.3), high protein removal (60.7 ± 2.8 %) and selectivity parameters (S  red/prot = 10.05).
Determination of the gas exchange phenology in an evergreen coniferous forest from 7 years of eddy covariance flux data using an extended big‐leaf analysis
Authors: Kosugi Yoshiko , Takanashi Satoru , Ueyama Masahito , Ohkubo Shinjiro , Tanaka Hiroki , Matsumoto Kazuho , Yoshifuji Natsuko , Ataka Mioko , Sakabe Ayaka
Published: March 2013

We defined gas exchange phenology as the seasonality of the gas exchange characteristics of a forest canopy, and investigated how the gas exchange phenology could be directly detected from an eddy covariance (EC) dataset and its influence on the canopy fluxes within an evergreen Japanese cypress forest. For the detection of gas exchange phenology, we derived three bulk parameters of the extended big‐leaf model (Kosugi et al. 2005) inversely from EC flux data over a 7‐year period: surface conductance (gc), maximum rate of carboxylation of the “big leaf” (VCMAX), and intercellular CO2 concentration of the “big leaf” (CI). The relationship between gc and the vapor pressure deficit declined in winter and spring. The relationship between the daily ecosystem respiration and air temperature was greater in the spring than in the other seasons. The temperature dependence curve of VCMAX decreased substantially in the winter and was different from that of an evergreen broadleaved forest. A decrease in CI was occasionally coupled with the decrease in canopy gross primary production during April and August, indicating that stomatal closure was responsible for a decline in canopy photosynthesis. Gas exchange phenology should be quantified when understanding the determining factors of the seasonality of canopy fluxes at evergreen coniferous forests.
Inside and Outside the EFTA Court: Evaluating the Effectiveness of the EFTA Court Through its Structures
Authors: Björnsson Thorbjörn
Published: March 2013

The article attempts to examine the structures of the EFTA Court in order to gain insights into its effectiveness. For this purpose the article relies on a rational system approach developed within social sciences to improve understanding the performance of public organisations and calibrated to examine international courts by the ERC Project Researching Conditions for Effective International Adjudication. Under the conceptual and analytical framework advanced by the Effectiveness Project the article, therefore, examines the main structures of the EFTA Court: for example, the Court's budget, jurisdictional rules, judicial independence and main legal doctrines. The article will also, in relation to some aspects, attempt to conduct a qualitative assessment of how some of these features relate to the effectiveness of the Court.
Non-deep complex morphophysiological dormancy inNarcissus longispathus(Amaryllidaceae): implications for evolution of dormancy levels within sectionPseudonarcissi
Authors: Herranz José M. , Copete Elena , Ferrandis Pablo
Published: March 2013

Narcissus longispathus(Amaryllidaceae) is a perennial geophyte and a Mediterranean narrowly endemic species. At dispersal time,N. longispathusseeds are dormant and have underdeveloped embryos. This work aimed to determine requirements for dormancy break and germination and to compare dormancy traits with those of the two endemic Iberian congeners. Phenology of embryo growth and germination were studied by regularly exhuming seeds sown in near-natural conditions. Temperature and light requirements for embryo growth, breaking of dormancy and germination were determined by incubating seeds under controlled laboratory conditions. Mean embryo length in fresh seeds was 1.50 mm, and embryos had to grow to 3.80 mm before radicle emergence. Embryos grew to full size and seeds germinated when they were warm stratified for 2 months (optimum 1 month at 20/7°C+1 month at 15/4°C), then cold stratified at 5°C for 2 months, and finally incubated at cool temperatures (15/4°C) for 30 d. However, in seeds only subjected to either warm or cold stratification, the embryos hardly grew and did not germinate. In natural conditions, the embryos elongate in autumn–winter, and in late winter–early spring (March) almost all radicles and seedlings emerged. Velocity of embryo growth and germination percentages increased with seed storage duration. Seeds ofN. longispathushave non-deep complex morphophysiological dormancy (MPD). This is the first report of such a level of MPD inNarcissus. Our data suggest that non-deep complex MPD may have been derived from intermediate complex MPD in the sectionPseudonarcissi.
Double right coronary artery and its clinical implications
Authors: Chien Tsu-Ming , Chen Chih-Wei , Chen Huai-Min , Lee Chee-Siong , Lin Ching-Cheng , Chen Ying-Fu
Published: March 2013

Congenital anomalies of the coronary arteries are present in 0.2–1.4% of the general population. These anomalies represent one of the most confusing issues in the field of cardiology and challenges for interventional cardiologists and cardiac surgeons if the anomalies are unrecognised. Double right coronary artery is one of the rarest coronary arteries. Previously, the probability of developing atherosclerotic changes in patients with a double right coronary artery was considered to be equal to that in those without it. In reality, however, a high prevalence of atherosclerotic coronary artery disease was found in patients with a double right coronary artery originating from a single ostium after our comprehensive literature search through the PubMed database. Owing to the fact that double right coronary artery is both a congenital and potentially atherosclerotic coronary artery disease at diagnosis, coronary intervention or cardiac operation is more complicated than previously believed. Individuals with a double right coronary artery may be unaware of its presence until an accidental finding during coronary angiography or cardiac operation and are at risk for unsuspected complications of atherosclerotic coronary artery disease or during cardiac operation. Therefore, it is important to obtain information on the anatomic variants of this congenital coronary anomaly in patients who are undergoing either coronary intervention, aortic root operation or myocardial revascularisation. To our knowledge, this is the first comprehensive article to discuss the anomalies and their clinical implications.
Theory of Mind in Patients with Temporal Lobe Epilepsy
Authors: Li Yi-Hsing , Chiu Ming-Jang , Yeh Zai-Ting , Liou Horng-Huei , Cheng Ting-Wen , Hua Mau-Sun
Published: March 2013

Theory of mind (ToM) is a crucial aspect of social cognition and is mediated by a complex neural network. Studies on temporal lobe epilepsy (TLE) suggest that its neuropathological involvement includes several brain regions. Some regions seem to overlap the neural network responsible for ToM, and this overlap provides an opportunity to explore ToM in TLE patients. Another concern is psychosocial problems in TLE, and the study of ToM in TLE could serve as a basis for further understanding the nature of such psychosocial disturbances. Studies on whether TLE patients evidence ToM deficit, however, are scant and controversial. Consequently, we examine whether ToM deficit is evident in TLE. Thirty-one TLE patients and 24 matched controls were recruited and completed four tasks measuring different levels of ToM: false belief, faux pas recognition, processing of implied meanings, and cartoon ToM. The patients were impaired in both basic and advanced ToM. Right TLE had a more wide-ranging picture of deficit than left TLE. ToM appears to be vulnerable to TLE, especially on the right side. Since ToM might contribute to patients’ psychosocial adjustment, we thus suggest that a ToM measure be included in regular neuropsychological assessments of such patients. (JINS, 2013, 19, 1–7)
Ultrastructural Imaging of Endocytic Sites in Saccharomyces cerevisiae by Transmission Electron Microscopy and Immunolabeling
Authors: Buser Christopher , Drubin David G.
Published: March 2013

Defining the ultrastructure of endocytic sites and localization of endocytic proteins in Saccharomyces cerevisiae by immunoelectron microscopy is central in understanding the mechanisms of membrane deformation and scission during endocytosis. We show that an improved sample preparation protocol based on high-pressure freezing, freeze substitution, and low-temperature embedding allows us to maintain the cellular fine structure and to immunolabel green fluorescent protein–tagged endocytic proteins or actin in the same sections. Using this technique we analyzed the stepwise deformation of endocytic membranes and immunolocalized the endocytic proteins Abp1p, Sla1p, Rvs167p, and actin, and were able to draw a clear ultrastructural distinction between endocytic sites and eisosomes by immunolocalizing Pil1p. In addition to defining the geometry and the fine structure of budding yeast endocytic sites, we observed associated actin filaments forming a cage-like meshwork around the endocytic membrane.
Communication with aliens, as an opening of the horizon of a scientific Humanity. A philosopher's reflections
Authors: Petit J.-L.
Published: March 2013

In this article, we reflect on the motives underlying the search for extraterrestrial intelligent life (SETI) with a view to show that far from turning away from humanity it is profoundly rooted in human aspirations. We suggest that those motives derive their driving force from the fact that they combine two powerful aspirations of humanity. On the one hand, there is the transcendental motive that drives history of science, the human enterprise that claims to escape any communitarian closure of horizon and brings our humanity to transcend itself toward the other, which was formerly referred to under the title Universal Reason. On the other hand, there is the anthropological motive by virtue of which the human being tends to project on the other and even in inanimate nature a double of himself. The mixture of both motives is deemed responsible for a remarkable bias in the current understanding of the SETI programme. Despite the fact that such a programme might well be aimed at any biological formation which could be arbitrarily different from all known forms, it is focused instead on a very special kind of being: beings that possess both the natural property of the type of mentality we identify with: intelligence, and the ideal one of being possible co-subjects for a Science of Nature.
Responsibilisation on Government's Terms: New Welfare and the Governance of Responsibility and Solidarity
Authors: Peeters Rik
Published: March 2013

The notion of ‘governance’ is often studied from a public management perspective and is associated with the image of a modest or even retreating state. However, ‘governance’ can also be studied from a political perspective, which focuses on issues of power and interests in governance practices. This shifts attention from a modest state to the techniques governments use to step into society and influence citizen behaviour. Whether in crime policy, youth policy or public health policy, traditional government techniques such as penalising behaviour or compensating harm are complemented by governance techniques to manage citizen responsibility and solidarity in the face of social risks.

This article deals with the question of how politicians and governments publicly frame and legitimise a new realm of state intervention dedicated to enticing, persuading and nudging citizens to ‘take responsibility’ in producing public value. An analysis of Dutch political discourse in the first decade of the twenty-first century reveals the mechanisms by which government justifies its new approach to social issues. The traditional connotations of the notions ‘responsibility’ and ‘solidarity’ are transformed in order to mobilise citizens and approach them as both part of the problem and part of the solution to various social issues. An analysis of Dutch youth policy shows how this brings about a politicisation of citizen behaviour and implicates citizens as co-operators of political will formation.
Wozu braucht es die Milz?
Authors: Tuchscherer Daniel , Reinhart Walter H.
Published: March 2013

Auch wenn die Milz nicht ein lebensnotwendiges Organ ist, hat sie wichtige Funktionen wie z. B. Immunabwehr, Blutfiltration, Speicherfunktion und bei Bedarf Blutbildung. Für die Immunabwehr ist die sogenannte weiße Pulpa mit T-Lymphozyten in periarteriolären Lymphozytenscheiden und B-Lymphozyten in Lymphfollikeln und der sogenannten Marginalzone verantwortlich, welche in einem komplexen Zusammenspiel Antigene und Erreger im Blutstrom aufspüren und eliminieren. Bei fehlender Milz besteht die Gefahr einer fulminanten Sepsis mit bekapselten Erregern. Die rote Pulpa ist der Bereich, in dem gealterte und defekte Erythrozyten herausfiltriert und durch Makrophagen phagozytiert werden, unter Wiederverwendung des Hämoglobin-Eisens. Deshalb ist die Milz nicht irgendein „Spleen“ der Natur, sondern ein hochentwickeltes Organ für die Instandhaltung der Blutzirkulation.
Die Milz bei hämato-onkologischen Erkrankungen
Authors: Kienle Dirk L.
Published: March 2013

Die Milz als lymphatisches und hämatologisches Organ spielt eine wichtige Rolle bei hämato-onkologischen Erkrankungen. Eine Splenomegalie kann zur Diagnose einer hämato-onkologischen Erkrankung führen, umgekehrt sollte bei Verdacht auf eine hämato-onkologische Erkrankung eine Milzuntersuchung erfolgen. Bei unklarer Splenomegalie führt eine erste diagnostische Aufarbeitung mit gezielter Anamnese, klinischer Untersuchung, Laboruntersuchungen einschließlich gründlicher Beurteilung eines Blutbildausstriches häufig zu einer Verdachtsdiagnose, sodass weitere diagnostische Maßnahmen gezielt ergriffen werden können. Eine diagnostische Splenektomie ist in aller Regel nicht erforderlich. Zu den häufigsten hämato-onkologischen Erkrankungen mit Splenome galie zählen wenig aggressive Lymphome (v. a. chronisch lymphatische Leukämie, Haarzellleukämie, splenisches Marginalzonenlymphom) und chronisch myeloproliferative Erkrankungen (v. a. chronisch myeloische Leukämie, Polycythämia vera, essentielle Thrombozythämie, Myelofibrose). Die therapeutischen Optionen sind sehr differenziert, und bis auf wenige Ausnahmen kann heutzutage auf eine therapeutische Splenektomie verzichtet werden.
Elektive Splenektomie bei Erwachsenen – Vorbereitung, Durchführung und Nachbetreuung
Authors: Worni Mathias , Schudel Hans H. , Güller Ulrich
Published: March 2013

Die elektive Splenektomie bei Erwachsenen wird häufig nach erfolgloser, konservativer Therapie bei hämatologischen, neoplastischen und autoimmunen Krankheiten durchgeführt. Die Indikation zur Splenektomie sollte bei allen Pa tienten interdisziplinär – und nicht durch den Chirurgen allein – gestellt werden. Die laparoskopische Splenektomie hat sich heutzutage als Gold-Standard eta bliert mit sehr geringer postoperativer Morbidität und Mortalität und im Vergleich zur offenen Methode weniger postoperativen Schmerzen und einem kür zeren Spitalaufenthalt. Spätestens zwei Wochen präoperativ müssen die Patienten erstmals gegen Pneumokokken sowie Meningokokken geimpft werden, um das Risiko einer „overwhelming post-splenectomy infection“ (OPSI) zu minimieren. Zusätzlich zur Auffrischimpfung im follow-up sollte jeder Patient über das erhöhte Infektrisiko informiert sein sowie einen Post-Splenektomie-Ausweis und ein Notfall-Antibiotikum auf sich tragen.
Der splenektomierte Patient in der Praxis
Authors: Goede Jeroen S. , Siciliano Daniele
Published: March 2013

Splenektomierte Patienten stellen eine bezüglich Alter und Grunderkrankungen sehr heterogene Gruppe von Patienten dar, die ein erhöhtes Risiko für potentiell lebensbedrohliche Infektionen, meist ausgelöst durch bekapselte Bakterien, sowie für Thrombosen im portalen Venensystem aufweisen. Im vorliegenden Artikel werden die in der Praxis zentralen und oft unterschätzten Präventionsmaßnahmen zusammen mit den empfohlenen praktischen Verhaltensregeln für diese Patienten besprochen.
Performance and characterization of the prototype nm-scale spatial resolution scanning multilayer Laue lenses microscope
Authors: Nazaretski E. , Kim Jungdae , Yan H. , Lauer K. , Eom D. , Shu D. , Maser J. , Pešić Z. , Wagner U. , Rau C. , Chu Y. S.
Published: March 2013

Synchrotron based x-ray microscopy established itself as a prominent tool for noninvasive investigations in many areas of science and technology. Many facilities around the world routinely achieve sub-micrometer resolution with a few instruments capable of imaging with the spatial resolution better than 100 nm. With an ongoing effort to push the 2D/3D resolution down to 10 nm in the hard x-ray regime both fabrication of the nano-focusing optics and stability of a microscope become extremely challenging. In this work we present our approach to overcome technical challenges on the path towards high spatial resolution hard x-ray microscopy and demonstrate the performance of a scanning fluorescence microscope equipped with the multilayer Laue lenses focusing optics.
A quantum Mermin–Wagner theorem for quantum rotators on two-dimensional graphs
Authors: Kelbert Mark , Suhov Yurii
Published: March 2013

This is the first of a series of papers considering symmetry properties of quantum systems over 2D graphs or manifolds, with continuous spins, in the spirit of the Mermin–Wagner theorem [N. D. Mermin and H. Wagner, “Absence of ferromagnetism or antiferromagnetism in one- or two-dimensional isotropic Heisenberg models,” Phys. Rev. Lett. 17, 1133–1136 (1966)]10.1103/PhysRevLett.17.1133. In the model considered here (quantum rotators), the phase space of a single spin is a d-dimensional torus M, and spins (or particles) are attached to sites of a graph \documentclass[12pt]{minimal}\begin{document}$(\Gamma ,\mathcal {E})$\end{document}(Γ,E) satisfying a special bi-dimensionality property. The kinetic energy part of the Hamiltonian is minus a half of the Laplace operator −Δ/2 on M. We assume that the interaction potential is C2-smooth and invariant under the action of a connected Lie group \documentclass[12pt]{minimal}\begin{document}${\tt G}$\end{document}G (i.e., a Euclidean space \documentclass[12pt]{minimal}\begin{document}${\mathbb {R}}^{d^{\prime }}$\end{document}Rd′ or a torus M′ of dimension d′ ⩽ d) on M preserving the flat Riemannian metric. A part of our approach is to give a definition (and a construction) of a class of infinite-volume Gibbs states for the systems under consideration (the class \documentclass[12pt]{minimal}\begin{document}$\mathfrak {G}$\end{document}G). This class contains the so-called limit Gibbs states, with or without boundary conditions. We use ideas and techniques originated from papers [R. L. Dobrushin and S. B. Shlosman, “Absence of breakdown of continuous symmetry in two-dimensional models of statistical physics,” Commun. Math. Phys. 42, 31–40 (1975)10.1007/BF01609432; C.-E. Pfister, “On the symmetry of the Gibbs states in two-dimensional lattice systems,” Commun. Math. Phys. 79, 181–188 (1981)10.1007/BF01942060; J. Fröhlich and C. Pfister, “On the absence of spontaneous symmetry breaking and of crystalline ordering in two-dimensional systems,” Commun. Math. Phys. 81, 277–298 (1981)10.1007/BF01208901; B. Simon and A. Sokal, “Rigorous entropy-energy arguments,” J. Stat. Phys. 25, 679–694 (1981)10.1007/BF01022362; D. Ioffe, S. Shlosman and Y. Velenik, “2D models of statistical physics with continuous symmetry: The case of singular interactions,” Commun. Math. Phys. 226, 433–454 (2002)]10.1007/s002200200627 in combination with the Feynman–Kac representation, to prove that any state lying in the class \documentclass[12pt]{minimal}\begin{document}$\mathfrak {G}$\end{document}G (defined in the text) is \documentclass[12pt]{minimal}\begin{document}${\tt G}$\end{document}G-invariant. An example is given where the interaction potential is singular and there exists a Gibbs state which is not \documentclass[12pt]{minimal}\begin{document}${\tt G}$\end{document}G-invariant. In the next paper, under the same title we establish a similar result for a bosonic model where particles can jump from a vertex i ∈ Γ to one of its neighbors (a generalized Hubbard model).
Exponential decay for a von Kármán equations with memory
Authors: Kang Jum-Ran
Published: March 2013

In this paper, we consider a von Kármán equations with memory term. We show an exponential decay result of solutions under weaker assumption than the ones frequently used in the literature. In particular, the kernel we are considering is not necessarily exponentially decaying to zero as was assumed before.
A multiscale modeling study of loss processes in block-copolymer-based solar cell nanodevices
Authors: Donets Sergii , Pershin Anton , Christlmaier Evelin Martine Corvid , Baeurle Stephan A.
Published: March 2013

Flexible photovoltaic devices possess promising perspectives in opto-electronic technologies, where high mobility and/or large-scale applicability are important. However, their usefulness in such applications is currently still limited due to the low level of optimization of their performance and durability. For the improvement of these properties, a better understanding and control of small-scale annihilation phenomena involved in the photovoltaic process, such as exciton loss and charge carrier loss, is necessary, which typically implicates multiple length- and time-scales. Here, we study the causes for their occurrence on the example of nanostructured diblock- and triblock-copolymer systems by making use of a novel solar-cell simulation algorithm and explore new routes to optimize their photovoltaic properties. A particular focus is set on the investigation of exciton and charge carrier loss phenomena and their dependence on the inter-monomeric interaction strength, chain architecture, and external mechanical loading. Our simulation results reveal that in the regime from low up to intermediate χ-parameters an increasing number of continuous percolation paths is created. In this parameter range, the internal quantum efficiency (IQE) increases up to a maximum, characterized by a minimum in the number of charge losses due to charge recombination. In the regime of high χ-parameters both block-copolymer systems form nanostructures with a large number of bottlenecks and dead ends. These lead to a large number of charge losses due to charge recombination, charge trapping, and a deteriorated exciton dissociation, resulting in a significant drop in the IQE. Moreover, we find that the photovoltaic performance of the triblock-copolymer material decreases with increasing mechanical loading, caused by a growing number of charge losses due to charge recombination and charge accumulation. Finally, we demonstrate that the process of charge trapping in defects can be reversed by changing the polarity of the electrodes, which confers these materials the ability to be used as charge storage media.
Dissociation limit and dissociation dynamic of CF4+: Application of threshold photoelectron-photoion coincidence velocity imaging
Authors: Tang Xiaofeng , Zhou Xiaoguo , Wu Manman , Gao Zhi , Liu Shilin , Liu Fuyi , Shan Xiaobin , Sheng Liusi
Published: March 2013

Dissociation of internal energy selected CF4+ ions in an excitation energy range of 15.40–19.60 eV has been investigated using threshold photoelectron-photoion coincidence (TPEPICO) velocity imaging. Only CF3+ fragment ions are observed in coincident mass spectra, indicating all the X2T1, A2T2, and B2E ionic states of CF4+ are fully dissociative. Both kinetic energy released distribution (KERD) and angular distribution in dissociation of CF4+ ions have been derived from three-dimensional TPEPICO time-sliced images. A parallel distribution of CF3+ fragments along the polarization vector of photon is observed for dissociation of CF4+ ions in all the low-lying electronic states. With the aid of F-loss potential energy curves, dissociation mechanisms of CF4+ ions in these electronic states have been proposed. CF4+ ions in both X2T1 and A2T2 states directly dissociate to CF3+ and F fragments along the repulsive C-F coordinate, while a two-step dissociation mechanism is suggested for B2E state: CF4+(B2E) ion first converts to the lower A2T2 state via internal conversion, then dissociates to CF3+ and F fragments along the steep A2T2 potential energy surface. In addition, an adiabatic appearance potential of AP0(CF3+/CF4) has also been established to be 14.71 ± 0.02 eV, which is very consistent with the recent calculated values.
Steady heat conduction-based thermal conductivity measurement of single walled carbon nanotubes thin film using a micropipette thermal sensor
Authors: Shrestha R. , Lee K. M. , Chang W. S. , Kim D. S. , Rhee G. H. , Choi T. Y.
Published: March 2013

In this paper, we describe the thermal conductivity measurement of single-walled carbon nanotubes thin film using a laser point source-based steady state heat conduction method. A high precision micropipette thermal sensor fabricated with a sensing tip size varying from 2 μm to 5 μm and capable of measuring thermal fluctuation with resolution of ±0.01 K was used to measure the temperature gradient across the suspended carbon nanotubes (CNT) film with a thickness of 100 nm. We used a steady heat conduction model to correlate the temperature gradient to the thermal conductivity of the film. We measured the average thermal conductivity of CNT film as 74.3 ± 7.9 W m−1 K−1 at room temperature.
Differential electronic detector to monitor apoptosis using dielectrophoresis-induced translation of flowing cells (dielectrophoresis cytometry)
Authors: Nikolic-Jaric Marija , Cabel Tim , Salimi Elham , Bhide Ashlesha , Braasch Katrin , Butler Michael , Bridges Greg E. , Thomson Douglas J.
Published: March 2013

The instrument described here is an all-electronic dielectrophoresis (DEP) cytometer sensitive to changes in polarizability of single cells. The important novel feature of this work is the differential electrode array that allows independent detection and actuation of single cells within a short section (∼300 μm) of the microfluidic channel. DEP actuation modifies the altitude of the cells flowing between two altitude detection sites in proportion to cell polarizability; changes in altitude smaller than 0.25 μm can be detected electronically. Analysis of individual experimental signatures allows us to make a simple connection between the Clausius-Mossotti factor (CMF) and the amount of vertical cell deflection during actuation. This results in an all-electronic, label-free differential detector that monitors changes in physiological properties of the living cells and can be fully automated and miniaturized in order to be used in various online and offline probes and point-of-care medical applications. High sensitivity of the DEP cytometer facilitates observations of delicate changes in cell polarization that occur at the onset of apoptosis. We illustrate the application of this concept on a population of Chinese hamster ovary (CHO) cells that were followed in their rapid transition from a healthy viable to an early apoptotic state. DEP cytometer viability estimates closely match an Annexin V assay (an early apoptosis marker) on the same population of cells.
Hafnium intercalation between epitaxial graphene and Ir(111) substrate
Authors: Li Linfei , Wang Yeliang , Meng Lei , Wu Rong-ting , Gao H.-J.
Published: March 2013

We report on the change of structural and electronic properties while depositing Hf atoms onto the graphene epitaxially grown on Ir(111) substrate. We find that the Hf atoms intercalate between the graphene and its iridium host. This intercalation induces a new interface superstructure, as confirmed by scanning tunneling microscopy and low energy electron diffraction. Raman spectra reveal that the Hf-intercalated graphene shows the prominent features of intrinsic graphene. Our study suggests that the Hf intercalation acts as a buffer layer between the graphene and the Ir(111) substrate, restoring the graphene's intrinsic electronic properties.
On the formation of m = 1, n = 1 density snakes
Authors: Sugiyama Linda E.
Published: March 2013

The m/n = 1/1 helical ion density “snake” located near the q = 1 magnetic surface in a toroidal, magnetically confined plasma arises naturally in resistive MHD, when the plasma density evolves separately from pressure. Nonlinear numerical simulations show that a helical density perturbation applied around q = 1 can form a quasi-steady state over q≳1 with T̃ of opposite average sign to ñ. Two principal outcomes depend on the magnitude of ñ/n and the underlying stability of the 1/1 internal kink mode. For a small q<1 central region, a moderate helical density drives a new, slowly growing type of nonlinear 1/1 internal kink inside q<1, with small ñ and ∇p̃≃∇(nT̃). The hot kink core moves away from, or perpendicular to, the high density region near q≃1, preserving the snake density during a sawtooth crash. The mode resembles the early stage of heavy-impurity-ion snakes in ohmic discharges, including recent observations in Alcator C-Mod. For a larger, more unstable q<1 region, the helical density perturbation drives a conventional 1/1 kink where ñ aligns with T̃, leading to a rapid sawtooth crash. The crash redistributes the density to a localized helical concentration inside q≲1, similar to experimentally observed snakes that are initiated by a sawtooth crash.
Relationship between thermodynamic parameter and thermodynamic scaling parameter for orientational relaxation time for flip-flop motion of nematic liquid crystals
Authors: Satoh Katsuhiko
Published: March 2013

Thermodynamic parameter Γ and thermodynamic scaling parameter γ for low-frequency relaxation time, which characterize flip-flop motion in a nematic phase, were verified by molecular dynamics simulation with a simple potential based on the Maier-Saupe theory. The parameter Γ, which is the slope of the logarithm for temperature and volume, was evaluated under various conditions at a wide range of temperatures, pressures, and volumes. To simulate thermodynamic scaling so that experimental data at isobaric, isothermal, and isochoric conditions can be rescaled onto a master curve with the parameters for some liquid crystal (LC) compounds, the relaxation time was evaluated from the first-rank orientational correlation function in the simulations, and thermodynamic scaling was verified with the simple potential representing small clusters. A possibility of an equivalence relationship between Γ and γ determined from the relaxation time in the simulation was assessed with available data from the experiments and simulations. In addition, an argument was proposed for the discrepancy between Γ and γ for some LCs in experiments: the discrepancy arises from disagreement of the value of the order parameter P2 rather than the constancy of relaxation time $\tau _1^*$τ1* on pressure.
Frequency dependence of specific heat in supercooled liquid water and emergence of correlated dynamics
Authors: Saito Shinji , Ohmine Iwao , Bagchi Biman
Published: March 2013

Molecular origin of the well-known specific heat anomaly in supercooled liquid water is investigated here by using extensive computer simulations and theoretical analyses. A rather sharp increase in the values of isobaric specific heat with lowering temperature and the weak temperature dependence of isochoric specific heat in the same range are reproduced in simulations. We calculated the spatio-temporal correlation among temperature fluctuations and examined the frequency dependent specific heat. The latter shows a rapid growth in the low frequency regime as temperature is cooled below 270 K. In order to understand the microscopic basis of this increase, we have performed a shellwise decomposition of contributions of distant molecules to the temperature fluctuations in a central molecule. This decomposition reveals the emergence, at low temperatures, of temporally slow, spatially long ranged large temperature fluctuations. The temperature fluctuation time correlation function (TFCF) can be fitted to a William-Watts stretched exponential form with the stretching parameter close to 0.6 at low temperatures, indicating highly non-exponential relaxation. Temperature dependence of the relaxation time of the correlation function can be fitted to Vogel-Fulcher-Tamermann expression which provides a quantitative measure of the fragility of the liquid. Interestingly, we find that the rapid growth in the relaxation time of TFCF with lowering temperature undergoes a sharp crossover from a markedly fragile state to a weakly fragile state around 220 K.
The dynamics of hybrid metabolic-genetic oscillators
Authors: Reznik Ed , Kaper Tasso J. , Segrè Daniel
Published: March 2013

The synthetic construction of intracellular circuits is frequently hindered by a poor knowledge of appropriate kinetics and precise rate parameters. Here, we use generalized modeling (GM) to study the dynamical behavior of topological models of a family of hybrid metabolic-genetic circuits known as “metabolators.” Under mild assumptions on the kinetics, we use GM to analytically prove that all explicit kinetic models which are topologically analogous to one such circuit, the “core metabolator,” cannot undergo Hopf bifurcations. Then, we examine more detailed models of the metabolator. Inspired by the experimental observation of a Hopf bifurcation in a synthetically constructed circuit related to the core metabolator, we apply GM to identify the critical components of the synthetically constructed metabolator which must be reintroduced in order to recover the Hopf bifurcation. Next, we study the dynamics of a re-wired version of the core metabolator, dubbed the “reverse” metabolator, and show that it exhibits a substantially richer set of dynamical behaviors, including both local and global oscillations. Prompted by the observation of relaxation oscillations in the reverse metabolator, we study the role that a separation of genetic and metabolic time scales may play in its dynamics, and find that widely separated time scales promote stability in the circuit. Our results illustrate a generic pipeline for vetting the potential success of a circuit design, simply by studying the dynamics of the corresponding generalized model.
Linear mode conversion of Langmuir/z-mode waves to radiation: Scalings of conversion efficiencies and propagation angles with temperature and magnetic field orientation
Authors: Schleyer F. , Cairns Iver H. , Kim E.-H.
Published: March 2013

Linear mode conversion (LMC) is the linear transfer of energy from one wave mode to another in an inhomogeneous plasma. It is relevant to laboratory plasmas and multiple solar system radio emissions, such as continuum radiation from planetary magnetospheres and type II and III radio bursts from the solar corona and solar wind. This paper simulates LMC of waves defined by warm, magnetized fluid theory, specifically the conversion of Langmuir/z-mode waves to electromagnetic (EM) radiation. The primary focus is the calculation of the energy and power conversion efficiencies for LMC as functions of the angle of incidence θ of the Langmuir/z-mode wave, temperature β=Te/mec2, adiabatic index γ, and orientation angle ϕ between the ambient density gradient ∇N0 and ambient magnetic field B0 in a warm, unmagnetized plasma. The ratio of these efficiencies is found to agree well as a function of θ, γ, and β with an analytical relation that depends on the group speeds of the Langmuir/z and EM wave modes. The results demonstrate that the energy conversion efficiency ϵ is strongly dependent on γβ, ϕ and θ, with ϵ∝(γβ)1/2 and θ∝(γβ)1/2. The power conversion efficiency ϵp, on the other hand, is independent of γβ but does vary significantly with θ and ϕ. The efficiencies are shown to be maximum for approximately perpendicular density gradients (ϕ≈90°) and minimal for parallel orientation (ϕ=0°) and both the energy and power conversion efficiencies peak at the same θ.
Effect of Y-doping on spin entropy in Ca3−xYxCo4O9+δ
Authors: Zhang D. W. , Wang Z. H. , Tang G. D. , Xu X. B. , Xu X. N. , Qiu L. , Zhang D. X. , Du Y. W.
Published: March 2013

The effects of Y-doping on spin entropy of Ca3Co4O9+δ have been investigated through measurements of magnetothermopower and magnetic properties. The temperature dependence of thermopower at 4 T is weaker than that at 0 T, showing a clear field-induced suppression of thermopower and a large contribution from spin entropy. The results from magnetic measurements demonstrate that Co4+ concentration decreases with increasing Y-doping level, which gives rise to enhanced spin entropy. A suitable model is adopted to explain commendably the spin entropy enhancement.
Photoluminescence of antimony sprayed indium arsenide quantum dots for novel photovoltaic devices
Authors: Bray T. , Zhao Y. , Reece P. , Bremner S. P.
Published: March 2013

Emission from InAs/GaAs quantum dots (QDs) treated with Sb sprays of 7.5, 15, 22.5, and 30 s duration immediately prior to capping with GaAs has been studied via temperature dependent photoluminescence. Room temperature spectra show a significant increase in output intensity as the quantum dots are exposed to the Sb spray, but this improvement is lost when the Sb exposure is extended beyond 15 s. For the 7.5 s and 15 s Sb spray samples, temperature-dependent photoluminescence taken between 20 and 300 K show an increase in emission for increasing temperature from 30 to ∼100 K, for samples with an Sb spray before rolling off at temperatures in excess of 100 K, an effect ascribed to a small energy barrier close to the dots. Fitting of the temperature dependent data suggests that the impact of the energy barrier is only seen for the samples with lower defect densities in the immediate vicinity of the quantum dots. Results found when varying the excitation wavelength suggest the energy barrier is most likely located away from the top of the quantum dots, with it suggested that the inferred energy barrier may be due to Sb clustering around the base of the quantum dots in the capping layer, or incorporated Sb in the wetting layer of the QDs.
Measuring the yield stress in magnetorheological fluids using ultrasounds
Authors: Rodríguez-López Jaime , Elvira Luis , Montero de Espinosa Freijo Francisco , Bossis Georges , de Vicente Juan
Published: March 2013

In this work, we propose a method to accurately determine the yield stress in magnetorheological (MR) fluids using ultrasounds. The setup is constructed, and experimental data are obtained on a model conventional MR fluid under steady shear stress ramp-up tests. By using video-microscopy, ultrasonic techniques, and rheometry simultaneously, it is possible to precisely determine the yield stress at experimentally accessible times.
Low Peclet number mass and momentum transport in microcavities
Authors: Yew A. G. , Pinero D. , Hsieh A. H. , Atencia J.
Published: March 2013

For the informed design of microfluidic devices, it is important to understand transport phenomena at the microscale. This letter outlines an analytically driven approach to the design of rectangular microcavities extending perpendicular to a perfusion microchannel for applications that may include microfluidic cell culture devices. We present equations to estimate the transition from advection- to diffusion-dominant transport inside cavities as a function of the geometry and flow conditions. We also estimate the time required for molecules, such as nutrients or drugs, to travel from the microchannel to a given length into the cavity. These analytical predictions can facilitate the rational design of microfluidic devices to optimize and maintain long-term, low Peclet number environments with minimal fluid shear stress.
Information transport in field-coupled nanomagnetic logic devices
Authors: Kiermaier J. , Breitkreutz S. , Eichwald I. , Engelstädter M. , Ju X. , Csaba G. , Schmitt-Landsiedel D. , Becherer M.
Published: March 2013

The information transport in field-coupled nanomagnetic logic (NML) systems is demonstrated by investigating signal propagation in a circular chain of magnets. Design criteria for the magnet layout, signal injection timing, and the required clocking field are presented. The strong interaction between the magnets is estimated by simulations and verified by hysteresis curve measurements. Signal transmission in the magnetic wire is confirmed by magnetic force microscopy measurements, especially the propagation of a metastable pair of magnets with parallel magnetization. For the first time, a field-coupled magnetic logic device is successfully operated for hundreds of clocking cycles. Extensive studies verify the reliability and robustness of information transport in field-coupled NML systems from perpendicular magnetic media.
Collisional damping of the geodesic acoustic mode
Authors: Gao Zhe
Published: March 2013

The frequency and damping rate of the geodesic acoustic mode (GAM) is revisited by using a gyrokinetic model with a number-conserving Krook collision operator. It is found that the damping rate of the GAM is non-monotonic as the collision rate increases. At low ion collision rate, the damping rate increases linearly with the collision rate; while as the ion collision rate is higher than vti/R, where vti and R are the ion thermal velocity and major radius, the damping rate decays with an increasing collision rate. At the same time, as the collision rate increases, the GAM frequency decreases from the (7/4+τ)vti/R to (1+τ)vti/R, where τ is the ratio of electron temperature to ion temperature.
Fast wave stabilization/destabilization of drift waves in a plasma
Authors: Kumar Pawan , Tripathi V. K.
Published: March 2013

Four wave-nonlinear coupling of a large amplitude whistler with low frequency drift wave and whistler wave sidebands is examined. The pump and whistler sidebands exert a low frequency ponderomotive force on electrons introducing a frequency shift in the drift wave. For whistler pump propagating along the ambient magnetic field Bsẑ with wave number k→0, drift waves of wave number k→=k→⊥+k||ẑ see an upward frequency shift when k⊥2/k02>4k||/k0 and are stabilized once the whistler power exceeds a threshold value. The drift waves of low transverse wavelength tend to be destabilized by the nonlinear coupling. Oblique propagating whistler pump with transverse wave vector parallel to k→⊥ is also effective but with reduced effectiveness.
Temperature dependence of droop onset in optically pumped intrinsic InGaAs/InP heterostructures
Authors: Olsson Anders , Aierken Abuduwayiti , Oksanen Jani , Suihkonen Sami , Lipsanen Harri , Tulkki Jukka
Published: March 2013

Although conventional III-V compound semiconductors are often considered not to exhibit an efficiency droop, a pronounced low temperature droop was recently measured in AlGaInP/GaAs multi-quantum well structures. In this work, we investigate the efficiency droop in simple optically pumped lattice matched InGaAs/InP single well heterostructures to exclude charge transport related effects from the measurements. The results show that droop is present in this very simplistic setup and, furthermore, starts approximately at the same carrier density as in typical III-N structures. Our results suggest that in its most fundamental form, droop can be explained by Auger-like processes.
Exponential decay of shearing stress during jerky flows in a Zr-based bulk metallic glass
Authors: Qiao J. W. , Wang Z. , Yang H. J. , Li M. , Liang W. , Xu B. S.
Published: March 2013

Presently, an exponential decay of shearing stresses with the time during jerky flows in a Zr-based bulk metallic glass is revealed. The flow stresses with the time satisfy the following equation: σ = A · e−B · x, where A = −158.24*exp ( − N/47.60) + 1939.63 (N = 1, 2, 3…), and the mean value of obtained B is −0.13 with a Normal distribution. During jerky flows, the viscous shearing layer is formed, and the exponential decay of shear banding is present. The evolvement of shear bands is explained by the consumption of free volumes during flows.
Rare somatic cells from human breast tissue exhibit extensive lineage plasticity
Authors: Roy Somdutta , Gascard Philippe , Dumont Nancy , Zhao Jianxin , Pan Deng , Petrie Sarah , Margeta Marta , Tlsty Thea D.
Published: March 2013

We identified cell surface markers associated with repression of p16
INK4a
/cyclin-dependent kinase inhibitor 2A(CDKN2A), a critical determinant in the acquisition of a plastic state. These cell surface markers allowed direct isolation of rare cells from healthy human breast tissue that exhibit extensive lineage plasticity. This subpopulation is poised to transcribe plasticity markers, OCT3/4, SOX2, and NANOG, at levels similar to those measured in human embryonic stem cells and to acquire a plastic state sensitive to environmental programming. In vitro, in vivo, and teratoma assays demonstrated that either a directly sorted (uncultured) or a single-cell (clonogenic) cell population from primary tissue can differentiate into functional derivatives of each germ layer, ectodermal, endodermal, and mesodermal. In contrast to other cells that express OCT3/4, SOX2, and NANOG, these human endogenous plastic somatic cells are mortal, express low telomerase activity, expand for an extensive but finite number of population doublings, and maintain a diploid karyotype before arresting in G1.
Xerocytosis is caused by mutations that alter the kinetics of the mechanosensitive channel PIEZO1
Authors: Bae Chilman , Gnanasambandam Radhakrishnan , Nicolai Chris , Sachs Frederick , Gottlieb Philip A.
Published: March 2013

Significance

Familial xerocytosis in humans, which causes dehydration of red blood cells and hemolytic anemia, was traced to mutations in the mechanosensitive ion channel, PIEZO1. The mutations slowed inactivation and introduced a pronounced latency for activation. Loss of inactivation and increased latency for activation could modify groups of channels simultaneously, suggesting that they exist in common spatial domains. The hereditary xerocytosis mutants affect red cell cation fluxes: slow inactivation increases them, and increased latency decreases them. These data provide a direct link between pathology and mechanosensitive channel dysfunction in nonsensory cells.