bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular insight into the role of the leucine residue on the L2 loop in the catalytic activity of caspases 3 and 7
Authors: Kang Hyo Jin , Lee Young-mi , Jeong Myeong Seon , Kim Moonil , Bae Kwang-Hee , Kim Seung Jun , Chung Sang J.
Published: February 2012

Various apoptotic signals can activate caspases 3 and 7 by triggering the L2 loop cleavage of their proenzymes. These two enzymes have highly similar structures and functions, and serve as apoptotic executioners. The structures of caspase 7 and procaspase 7 differ significantly in the conformation of the loops constituting the active site, indicating that the enzyme undergoes a large structural change during activation. To define the role of the leucine residue on the L2 loop, which shows the largest movement during enzyme activation but has not yet been studied, Leu168 of caspase 3 and Leu191 of caspase 7 were mutated. Kinetic analysis indicated that the mutation of the leucine residues sometimes improved the Km but also greatly decreased the kcat, resulting in an overall decrease in enzyme activity. The tryptophan fluorescence change at excitation/emission=280/350 nm upon L2–L2′ loop cleavage was found to be higher in catalytically active mutants, including the corresponding wild-type caspase, than in the inactive mutants. The crystal structures of the caspase 3 mutants were solved and compared with that of wild-type. Significant alterations in the conformations of the L1 and L4 loops were found. These results indicate that the leucine residue on the L2 loop has an important role in maintaining the catalytic activity of caspases 3 and 7.
Seizing the Opportunity: Towards a Historiography of Information Systems
Authors: Mitev Nathalie , De Vaujany François-Xavier
Published: February 2012

Historical perspectives are only timidly entering the world of IS research compared to historical research in management or organisation studies. If major IS outlets have already published history-oriented papers, the number of historical papers - although increasing - remains low. We carried out a thematic analysis of all papers on History and IS published between 1972 and 2009 indexed on ABI and papers indexed in Google Scholar™ for the same period. We used a typology developed by theorists Üsdiken and Kieser, who classify historical organisation research into supplementarist, integrationist and reorientationist approaches. We outline their links with the epistemological stances well known in IS research, positivism, interpretivism and critical research; we then focus on their differences and historiographical characteristics. We found that most IS History papers are supplementarist descriptive case studies with limited uses of History. This paper then suggests that IS research could benefit from adopting integrationist and reorientationist historical perspectives and we offer some examples to illustrate how that would contribute to enriching, extending and challenging existing theories.
Laser and focused ion beam combined machining for micro dies
Authors: Yoshida Y. , Okazaki W. , Uchida T.
Published: February 2012

We have developed a laser and focused ion beam (FIB) compound process for press mold dies of a micro lens array (MLA) and a micro needle array (MNA) in a glassy carbon (GC). The press mold die of the MLA was roughly fabricated by UV-YAG laser. After this process, we finished this surface by scanning FIB. As a result, higher accuracy and good roughness of surface profile can be realized. An optical glass is used to confirm the shape of lens. Moreover, we fabricated 6 × 6 through-holes in the GC by the spiral drilling in addition to the focus position movement of the UV laser for press mold die of the MNA. After the FIB process, we were able to make the needle die of surface and hole wall roughness less than 0.9 μm. A silicon rubber is used to confirm the shape of the holes.
The electron cyclotron resonance ion source with arc-shaped coils concept (invited)
Authors: Koivisto H. , Suominen P. , Tarvainen O. , Spädtke P.
Published: February 2012

The main limitation to further improve the performance of ECR ion sources is set by the magnet technology related to the multipole magnet field used for the closed minimum-B structure. The JYFL ion source group has sought different approaches to improve the strength of the minimum-B structure required for the production of highly charged ion beams. It was found out that such a configuration can be realized with arc shaped coils. The first prototype, electron cyclotron resonance ion source with arc-shaped coils (ARC-ECRIS), was constructed and tested at JYFL in 2006. It was confirmed that such an ion source can be used for the production of highly charged ion beams. Regardless of several cost-driven compromises such as extraction mirror ratio of 1.05–1.2, microwave frequency of 6.4 GHz, and beam line with limited capacity, Ar4+ beam intensity of up to 2 μA was measured. Subsequent design study has shown that the ARC-ECRIS operating at the microwave frequency above 40 GHz could be constructed. This specific design would be based on NbTi-wires and it fulfills the experimental magnetic field scaling laws. In this article, the ARC-ECRIS concept and its potential applications will be described.
Status of the plasma generator of the superconducting proton linac
Authors: Kronberger M. , Faircloth D. , Lettry J. , Paoluzzi M. , Pereira H. , Arias J. Sanchez , Schmitzer C. , Scrivens R.
Published: February 2012

In the framework of the superconducting proton linac (SPL) study at CERN, a new non-cesiated H− plasma generator driven by an external 2 MHz RF antenna has been developed and successfully operated at repetition rates of 50 Hz, pulse lengths of up to 3 ms, and average RF powers of up to 3 kW. The coupling efficiency of RF power into the plasma was determined by the cooling water temperatures and the analysis of the RF forward and reflected power and the antenna current and amounts to 50%–60%. The plasma resistance increases between 10 kW and 40 kW RF power from about 0.45 Ω to 0.65 Ω. Measurements of RF power dissipated in the ferrites and the magnets on a test bench show a 5-fold decrease of the power losses for the magnets when they are contained in a Cu box, thus validating the strategy of shielding the magnets with a high electrical conductivity material. An air cooling system was installed in the SPL plasma generator to control the temperatures of the ferrites despite hysteresis losses of several Watts.
The development of the radio frequency driven negative ion source for neutral beam injectors (invited)
Authors: Kraus W. , Fantz U. , Franzen P. , Fröschle M. , Heinemann B. , Riedl R. , Wünderlich D.
Published: February 2012

Large and powerful negative hydrogen ion sources are required for the neutral beam injection (NBI) systems of future fusion devices. Simplicity and maintenance-free operation favors RF sources, which are developed intensively at the Max-Planck-Institut für Plasmaphysik (IPP) since many years. The negative hydrogen ions are generated by caesium-enhanced surface conversion of atoms and positive ions on the plasma grid surface. With a small scale prototype the required high ion current density and the low fraction of co-extracted electrons at low pressure as well as stable pulses up to 1 h could be demonstrated. The modular design allows extension to large source dimensions. This has led to the decision to choose RF sources for the NBI of the international fusion reactor, ITER. As an intermediate step towards the full size ITER source at IPP, the development will be continued with a half-size source on the new ELISE testbed. This will enable to gain experience for the first time with negative hydrogen ion beams from RF sources of these dimensions.
Giant magnetostriction in tetragonally distorted antiperovskite manganese nitrides
Authors: Shimizu T. , Shibayama T. , Asano K. , Takenaka K.
Published: February 2012

The discovery of giant magnetostriction exceeding 2000 ppm in Mn3CuN has stimulated the research of manganese antiperovskites from the perspective of forced magnetostriction. We discovered that Mn3SbN exhibits a large magnetostriction of up to 450 ppm in the tetragonally distorted ferromagnetic phase below the Curie temperature TC = 360 K. The magnitude of magnetostriction is enhanced by up to 1000 ppm without reduction of TC by partial replacement of the constituent elements. The present results are examined in terms of ferromagnetic shape memory effects.
Electron resonance and magnetic response of low-doped La0.88Ca0.12MnO3 and La0.9Sr0.1MnO3 manganite single crystals
Authors: Rozenberg E. , Shames A. I. , Tsindlekht M. I. , Felner I. , Mukovskii Ya. M.
Published: February 2012

Ferromagnetic resonance and ac/dc magnetic properties of the low-doped La0.88Ca0.12MnO3 and La0.9Sr0.1MnO3 manganite single crystals were studied below (down to 5 K) their paramagnetic-ferromagnetic phase transition. It appears that technologically driven chemical/structural disorder inherent to low-doped manganites influences strongly on both resonance and magnetic properties of these crystals. It is suggested that a special complexity of such disorder, which manifests itself in Sr-doped crystal on the “meso-” and “macroscopic” scales, may cause additional (as compared to the more structurally homogeneous Ca-doped sample) orbital ordering at lowest temperatures.
Methyl group rotation, 1H spin-lattice relaxation in an organic solid, and the analysis of nonexponential relaxation
Authors: Beckmann Peter A. , Schneider Evan
Published: February 2012

We report 1H spin-lattice relaxation measurements in polycrystalline 4,4′-dimethoxybiphenyl at temperatures between 80 and 300 K at NMR frequencies of ω0/2π = 8.50, 22.5, and 53.0 MHz. The data are interpreted in terms of the simplest possible Bloch-Wangsness-Redfield methyl group hopping model. Different solid states are observed at low temperatures. The 1H spin-lattice relaxation is nonexponential at higher temperatures where a stretched-exponential function fits the data very well, but this approach is phenomenological and not amenable to theoretical interpretation. (We provide a brief literature review of the stretched-exponential function.) The Bloch-Wangsness-Redfield model applies only to the relaxation rate that characterizes the initial 1H magnetization decay in a high-temperature nonexponential 1H spin-lattice relaxation measurement. A detailed procedure for determining this initial relaxation rate is described since large systematic errors can result if this is not done carefully.
Synchronization of fluid-dynamics related and physiological time scales and algal biomass production in thin flat-plate bioreactors
Authors: Gebremariam Alemayehu Kasahun , Zarmi Yair
Published: February 2012

Experiments on ultrahigh density unicellular algae cultures in thin flat-plate bioreactors (thickness ≤2 cm) indicate that: i) Optimal areal biomass production rates are significantly higher than in traditional ponds or raceways, ii) productivity grows for radiation levels substantially higher than one sun; saturation emerging, possibly, at intensities of about four suns, and iii) optimal volumetric and areal production rates as well as culture densities increase as reactor thickness is reduced. The observations are reproduced within the framework of a simple model, which takes into account the random motion of cells across the reactor thickness, and the competing effects of two physiologically significant time scales. These are TR, the time that elapses from the moment a reaction center has collected the number of photons required for one photosynthetic cycle until it is available again for exploiting impinging photons (1–10 ms), and TW, an average of the decay time characteristic of photon loss processes (several ms to several tens of ms).
Identifying and evaluating organic nonlinear optical materials via molecular moments
Authors: Higginbotham A. P. , Cole J. M. , Blood-Forsythe M. A. , Hickstein D. D.
Published: February 2012

We demonstrate how to appropriately estimate the zero-frequency (static) hyperpolarizability of an organic molecule from its charge distribution, and we explore applications of these estimates for identifying and evaluating new organic nonlinear optical (NLO) materials. First, we calculate hyperpolarizabilities from Hartree-Fock–derived charge distributions and find order-of-magnitude agreement with experimental values. We show that these simple arithmetic calculations will enable systematic searches for new organic NLO molecules. Second, we derive hyperpolarizabilities from crystallographic data using a multipolar charge-density analysis and find good agreement with empirical calculations. This demonstrates an experimental determination of the full static hyperpolarizability tensor in a solid-state sample.
Dynamic mitigation of instabilities
Authors: Kawata S.
Published: February 2012

In the paper Phys. Plasmas 18, 092705 (2011), dynamic stabilization mechanism for the Rayleigh-Taylor instability was discussed together with another dynamic migration mechanism, which we proposed and is discussed further in a more general way in this paper. In general, a perturbation of physical quantity would feature the instability onset. Normally, the perturbation phase is unknown, so that the instability growth is discussed with the growth rate. However, if the perturbation phase is known, the instability growth can be controlled by a superposition of perturbations; the most well-known mechanism is a feedback control to compensate the displacement or the distortion of physical quantity. If the perturbation is induced by, for example, a particle beam axis oscillation or wobbling, the perturbation phase could be controlled, and the instability growth is mitigated by the superposition of the growing perturbations.
Interfaces between nonpolar and semipolar III-nitride semiconductor orientations: Structure and defects
Authors: Kioseoglou J. , Lotsari A. , Kalesaki E. , Dimitrakopulos G. P.
Published: February 2012

Observations of easy transition between nonpolar and semipolar orientations during III-Nitride heteroepitaxy identify the 90o 〈1¯21¯0〉 rotation relationship as being very important in defining this coexistence. A rigorous analysis of this relationship using the topological theory of interfaces showed that it leads to a high order of coincident symmetry and makes energetically favorable the appearance of the intergranular boundaries. Principal low-energy boundaries, that could also be technologically exploited, have been identified by high-resolution transmission electron microscopy (HRTEM) observations and have been studied energetically using empirical potential calculations. It is also shown that these boundaries can change their average orientation by incorporating disconnections. The pertinent strain relaxation mechanisms can cause such boundaries to act as sources of threading dislocations and stacking faults. The energetically favorable (101¯0) || (0001) boundary was frequently observed to delimit m-plane crystallites in (1¯21¯2) semipolar growth.
In situ crystallization kinetics studies of plasma-deposited, hydrogenated amorphous silicon layers
Authors: Sharma K. , Verheijen M. A. , van de Sanden M. C. M. , Creatore M.
Published: February 2012

The impact of the amorphous silicon properties, i.e., the microstructure parameter R* and the medium range order (MRO), on the crystallization process is highlighted and discussed. In agreement with literature, the development of large grains extending through the thickness of the poly-Si layer is found to be promoted by an increase in the amorphous silicon microstructure parameter, R*. Furthermore, while the role of the MRO in controlling the incubation time and, therefore, the onset in crystallization is generally acknowledged, it is also concluded that the presence of nano-sized voids plays an essential role in the crystallization kinetics.
The study of pressure induced structural phase transition in spin-frustrated Yb2Ti2O7 pyrochlore
Authors: Mishra A. K. , Poswal H. K. , Sharma Surinder M. , Saha Surajit , Muthu D. V. S. , Singh Surjeet , Suryanarayanan R. , Revcolevschi A. , Sood A. K.
Published: February 2012

Our in situ x-ray diffraction and Raman measurements of Yb2Ti2O7 pyrochlore show that it undergoes a reversible structural phase transition from cubic pyrochlore to a monoclinic phase at ∼28.6 GPa. Analysis of the x-ray data shows the transition to be thermodynamically first order and the high pressure phase to be substitutionally disordered. These experimental results are supported by our first principles calculations.
The effect of In-flush on the optical anisotropy of InAs/GaAs quantum dots
Authors: Molas M. , Gołasa K. , Kuldová K. , Borysiuk J. , Babiński A. , Lapointe J. , Wasilewski Z. R.
Published: February 2012

The effect of the In-flush technique on the optical anisotropy of InAs/GaAs quantum dots (QDs) has been investigated. The anisotropy was deduced from low temperature microluminescence measurements of the splitting of the emission lines related to single neutral excitons confined to the QDs. It was found that the anisotropy was significantly smaller in a structure grown by the In-flush technique as compared to a structure grown without this procedure. It is proposed that this anisotropy reduction is due to the reduction in the strain generated within the GaAs barrier when using the In-flush procedure.
Mobility matrix of a spherical particle translating and rotating in a viscous fluid confined in a spherical cell, and the rate of escape from the cell
Authors: Felderhof B. U. , Sellier A.
Published: February 2012

The mobility matrix of a spherical particle moving in a spherical cavity, filled with a viscous incompressible fluid, and with no-slip boundary condition at the wall of the cavity, is evaluated from the Oseen tensor for the cavity by the method used by Lorentz for a particle near a planar wall. For the case that the particle is a rigid sphere with no-slip boundary condition the comparison with exact calculations shows that the approximation is quite accurate, provided the radius of the particle is small relative to that of the cavity, and provided the particle is not too close to the wall. The translational mobility is used to derive the diffusion tensor of a Brownian particle via an Einstein relation. The approximate result for the diffusion tensor is employed to estimate the rate of escape of a Brownian particle from a cavity with semipermeable wall.
A nanopositioner for scanning probe microscopy: The KoalaDrive
Authors: Cherepanov Vasily , Coenen Peter , Voigtländer Bert
Published: February 2012

We present a new type of piezoelectric nanopositioner called KoalaDrive which can have a diameter less than 2.5 mm and a length smaller than 10 mm. The new operating principle provides a smooth travel sequence and avoids shaking which is intrinsic to nanopositioners based on inertial motion with sawtooth driving signals. In scanning probe microscopy, the KoalaDrive can be used for the coarse approach of the tip or sensor towards the sample. Inserting the KoalaDrive in a piezo tube for xyz-scanning integrates a complete scanning tunneling microscope (STM) inside a 4 mm outer diameter piezo tube of <10 mm length. The use of the KoalaDrive makes the scanning probe microscopy design ultracompact and accordingly leads to a high mechanical stability. The drive is UHV, low temperature, and magnetic field compatible. The compactness of the KoalaDrive allows building a multi-tip STM as small as a single tip STM.
Nucleobase adsorbed at graphene devices: Enhance bio-sensorics
Authors: Song Bo , Cuniberti Gianaurelio , Sanvito Stefano , Fang Haiping
Published: February 2012

Graphene as a good material for sensing single small molecules is hardly believed to identify bio-molecules via electrical currents. This is because bio-molecules tend to bind to graphene through non-covalent bonds, such as π-π stacking interaction, which is not customarily considered to induce a clear perturbation of the graphene electronic structure. In contrast to these expectations, we demonstrate that oxygen in nucleobases adsorbed on graphene with π-π stacking interaction can clearly alter the electric current even in water at room temperature. This property allows us to devise the strategies employing graphene as material of choice in bio-sensorics, bio-chips.
On the variational homotopy perturbation method for nonlinear oscillators
Authors: Fernández Francisco M.
Published: February 2012

In this paper, I discuss a recent application of a variational homotopy perturbation method to rather simple nonlinear oscillators. It is shown that the main equations are inconsistent and for that reason the results may be of scarce utility.
Terahertz magnetic field induced coherent spin precession in YFeO3
Authors: Zhou Runze , Jin Zuanming , Li Gaofang , Ma Guohong , Cheng Zhenxiang , Wang Xiaolin
Published: February 2012

We present the magnetic dipole transition at 0.299 THz excited by magnetic component of terahertz electromagnetic pulse in an antiferromagnetic YFeO3 crystal. The impulsive magnetic field of the terahertz pulse tilts the macroscopic magnetization, causing deviation from the equilibrium position, which is manifested by a sharp absorption at the frequency of the quasiferromagnetic mode of the crystal. The rotating coherent macroscopic magnetization radiates elliptically polarized emission at the frequency of the quasiferromagnetic resonance due to the dichroic absorption in the crystal.
Entropy change linked to the magnetic field induced Morin transition in Hematite nanoparticles
Authors: Pastor J. M. , Pérez-Landazábal J. I. , Gómez-Polo C. , Recarte V. , Larumbe S. , Santamarta R. , Fernandes Silva M. , Gómez Pineda E. A. , Winkler Hechenleitner A. A. , Lima M. K.
Published: February 2012

The most stable form of iron oxide is Hematite (α-Fe2O3), which has interesting electronic, catalytic, and magnetic properties showing size dependent characteristics. At room temperature, Hematite is weakly ferromagnetic with a rhombohedral corundum structure. Upon cooling, the structure undergoes a first order spin reorientation, in which the net magnetic moment is lost. This transition is called the Morin transition. In this work, the first order Morin transition has been analyzed as a function of the temperature and applied magnetic field in Hematite nanoparticles. The magnetization was measured in the temperature range of the transformation at different applied magnetic fields to evaluate the entropy change linked to the Morin transition. The magnetic field promotes a shift of the transformation temperature. The change of entropy has been estimated on the basis of Clausius-Clapeyron type equation.
Self-aligned lateral dual-gate suspended-body single-walled carbon nanotube field-effect transistors
Authors: Cao Ji , Ionescu Adrian M.
Published: February 2012

Self-aligned lateral dual-gate suspended-body single-walled carbon nanotube (CNT) field-effect transistors (CNFETs) have been demonstrated. A nano-precision assembly method using resist-assisted ac-dielectrophoresis is applied. Superior I-V characteristics controlled by two independent lateral gates spaced sub-100 nm away from the CNT body are experimentally observed and studied. The dual-gate operation mode effectively boosts the device performance: 34% smaller subthreshold slope, three times larger on-current, and four times higher transconductance. The proposed dual-gate suspended-body CNFETs hold promise for bottom-up fabrication of advanced complementary metal-oxide-semiconductor circuits and nano-electro-mechanical systems devices, such as tunable/switchable resonators for sensing and radio-frequency applications.
Suppression of edge magnetism in a titanium-embedded zigzag graphene nanoribbon
Authors: Guodong Yu , Xiaoling Lü , Yisong Zheng , Wenjing Tian
Published: February 2012

Electronic and magnetic properties of zigzag-edged graphene nanoribbons (ZGNR) embedded with titanium (Ti) atoms are studied by means of the first principle calculations. When Ti atoms are positioned near either edge of the ZGNR, the magnetic moment at this edge is rapidly suppressed as the Ti concentration increases, whereas the magnetism on the opposite edge is hardly affected. Rather than destroy the localized edge state of the ZGNR, the remarkable suppression of the edge magnetism by the Ti atoms originates from the antiferromagnetic coupling between the magnetic moments of a Ti atom and the ribbon edge. As a result, the Ti atoms introduce some additional subbands with spin polarization, which neutralizes the magnetic moment at the edge of the ZGNR. Such a Ti-embedded ZGNR with the unilateral magnetism can be utilized to realize the spin-polarized electronic transport.
Search for a small hole in a cavity wall by intermittent bulk and surface diffusion
Authors: Berezhkovskii Alexander M. , Barzykin Alexander V.
Published: February 2012

We study the search of a small round hole in the wall of a spherical cavity by a diffusing particle, which can reversibly bind to the cavity wall and diffuse on the surface being in the bound state. There are two channels for the particle first passage to the hole, through the bulk, and through the surface. We propose a coarse-grained model of the search process and use it to derive simple approximate formulas for the mean time required for the particle to reach the hole for the first time and for the probability of the first passage to the hole through the bulk channel. This is done for two distributions of the particle starting point: (1) Uniform distribution over the cavity volume and (2) uniform distribution over the cavity wall. We check the accuracy of the approximate formulas by comparing their predictions with the corresponding quantities found by solving the mixed bulk-surface diffusion problem numerically by the finite difference method. The comparison shows excellent agreement between the analytical and numerical results.
Solitonic solutions of Faddeev model
Authors: Shi Chang-Guang , Hirayama Minoru
Published: February 2012

An application of the equation proposed by the present authors, which is equivalent to the static field equation of the Faddeev model, is discussed. Under some assumptions on the space and on the form of the solution, the field equation is reduced to a nonlinear ordinary differential equation of second order. By solving this equation numerically, some solitonic solutions are obtained. It is discussed that the product of two integers specifying solutions may be identified with the Hopf topological invariant.
Mixed self-assembled monolayer of molecules with dipolar and acceptor character—Influence on hysteresis and threshold voltage in organic thin-film transistors
Authors: Jedaa Abdesselam , Salinas Michael , Jäger Christof M. , Clark Timothy , Ebel Alexander , Hirsch Andreas , Halik Marcus
Published: February 2012

In this report, we investigate the impact of the molecular dipole moment and redox active head groups (C60) in pure and mixed self-assembled monolayers (SAMs), which serve as an ultra-thin hybrid dielectric layer in low-voltage operating organic thin-film transistors. We show that the dipole of the SAM-forming molecules affects the threshold voltage, while the concentration of redox-active C60 moieties determines the hysteresis in devices with α,α′-dihexyl-sexithiophene and pentacene as organic semiconductors.
ZnO/Si arrays decorated by Au nanoparticles for surface-enhanced Raman scattering study
Authors: Chan Yu Fei , Xu Hai Jun , Cao Lei , Tang Ying , Li De Yao , Sun Xiao Ming
Published: February 2012

Large scale and highly ordered flowerlike ZnO/Si nanostructures are successfully prepared by combining two common techniques, viz. hydrothermally etch fabrication of nanoporous Si pillar array (NSPA) and self-catalytic chemical vapor transport growth of ZnO nanowires. Au nanoparticles are decorated onto the ZnO/Si nanoflowers by the hydrothermal method. The formed Au/ZnO/NSPA array is evaluated as a surface-enhanced Raman scattering SERS-active substrate, which exhibits very high sensitivity and good stability and reproducibility. The excellent SERS enhancement is mainly attributed to the strong local electromagnetic effect which is associated with the unique flowerlike nanostructures of Au/ZnO/NSPA and the formed metal-induced gap states at the Au/ZnO interfaces. The results indicated that Au/ZnO/NSPA might be employed as a promising SERS substrate for the fast detection of low-concentration biomolecules.
Correlated intermolecular coupling fluctuations in photosynthetic complexes
Authors: Vlaming Sebastiaan M. , Silbey Robert J.
Published: February 2012

The functioning and efficiency of natural photosynthetic complexes is strongly influenced by their embedding in a noisy protein environment, which can even serve to enhance the transport efficiency. Interactions with the environment induce fluctuations of the transition energies and couplings between the chlorophyll molecules, and due to the fact that different fluctuations will partially be caused by the same environmental factors, correlations between the various fluctuations will occur. We argue that fluctuations of the couplings should, in general, not be neglected, as these have a considerable impact on population transfer rates, decoherence rates, and the efficiency of photosynthetic complexes. Furthermore, while correlations between transition energy fluctuations have been studied, we provide the first quantitative study of the effect of correlations between coupling fluctuations and transition energy fluctuations, and of correlations between the various coupling fluctuations. It is shown that these additional correlations typically lead to changes in interchromophore transfer rates and population oscillations and can lead to a limited enhancement of the light harvesting efficiency.
ZnO nanorods-graphene hybrid structures for enhanced current spreading and light extraction in GaN-based light emitting diodes
Authors: Min Lee Jung , Yi Jaeseok , Woo Lee Won , Yong Jeong Hae , Jung Taeil , Kim Youngchae , Il Park Won
Published: February 2012

One-dimensional and two-dimensional hybrid structures, composed of vertical ZnO nanorods grown on large-area graphene, are successfully integrated onto the GaN/InGaN light emitting diodes (LEDs). Compared with GaN LED without transparent conducting electrode, current injection and light emission increased almost 2–3 times, respectively, by the introduction of graphene based conducting electrode. Additional ∼66% increase in light emission was achieved by growing the ZnO nanorods on the graphene, which is consistent with the finite difference time domain modeling result. Furthermore, electroluminescence intensity profiles confirm the uniform light emission with high brightness in GaN LED with the ZnO nanorods-graphene hybrid electrode.
Fourier-transform photocurrent spectroscopy using a supercontinuum light source
Authors: Petermann Christian , Beigang Rene , Fischer Peer
Published: February 2012

We demonstrate an implementation of frequency-encoded photocurrent spectroscopy using a super-continuum light source. The spectrally broad light is spatially dispersed and modulated with a special mechanical chopper design that permits a continuous wavelength-dependent modulation. After recombination, the light beam contains a frequency encoded spectrum which enables us to map the spectral response of a given sample in 60 ms and with a lateral resolution of 10 μm.
Magnetization states and switching in narrow-gapped ferromagnetic nanorings
Authors: Li Jie , Zhang Sheng , Grigas Chris , Misra Rajiv , Bartell Jason , Crespi Vincent H. , Schiffer Peter
Published: February 2012

We study permalloy nanorings that are lithographically fabricated with narrow gaps that break the rotational symmetry of the ring while retaining the vortex ground state, using both micromagnetic simulations and magnetic force microscopy (MFM). The vortex chirality in these structures can be readily set with an in-plane magnetic field and easily probed by MFM due to the field associated with the gap, suggesting such rings for possible applications in storage technologies. We find that the gapped ring edge characteristics (i.e., edge profile and gap shape) are critical in determining the magnetization switching field, thus elucidating an essential parameter in the controls of devices that might incorporate such structures.
Investigations of field instability of ferrofluid in hypergravity and microgravity
Authors: Chong Theng Yee , Ho Kent Loong , Ong Boon Hoong
Published: February 2012

The field instability of the free surface of ferrofluid was investigated under microgravity and hypergravity environments conducted by parabolic flight. It is observed that the perturbation was suppressed under hypergravity, whereas at the microgravity condition, it appeared to have only slight increase in the amplitude of the perturbation peaks compared to the case of ground condition. Besides, an observation of peak-trough distance showed that not only the peak, but the trough was also very much dependent on the applied magnetic field. The difference of magnetic pole (north and south) had shown to be a factor to the perturbation as well.
MicroRNA-132 dysregulation in schizophrenia has implications for both neurodevelopment and adult brain function
Authors: Miller Brooke H. , Zeier Zane , Xi Li , Lanz Thomas A. , Deng Shibing , Strathmann Julia , Willoughby David , Kenny Paul J. , Elsworth John D. , Lawrence Matthew S. , Roth Robert H. , Edbauer Dieter , Kleiman Robin J. , Wahlestedt Claes
Published: February 2012

Schizophrenia is characterized by affective, cognitive, neuromorphological, and molecular abnormalities that may have a neurodevelopmental origin. MicroRNAs (miRNAs) are small noncoding RNA sequences critical to neurodevelopment and adult neuronal processes by coordinating the activity of multiple genes within biological networks. We examined the expression of 854 miRNAs in prefrontal cortical tissue from 100 control, schizophrenic, and bipolar subjects. The cyclic AMP-responsive element binding- and NMDA-regulated microRNA miR-132 was significantly down-regulated in both the schizophrenic discovery cohort and a second, independent set of schizophrenic subjects. Analysis of miR-132 target gene expression in schizophrenia gene-expression microarrays identified 26 genes up-regulated in schizophrenia subjects. Consistent with NMDA-mediated hypofunction observed in schizophrenic subjects, administration of an NMDA antagonist to adult mice results in miR-132 down-regulation in the prefrontal cortex. Furthermore, miR-132 expression in the murine prefrontal cortex exhibits significant developmental regulation and overlaps with critical neurodevelopmental processes during adolescence. Adult prefrontal expression of miR-132 can be down-regulated by pharmacologic inhibition of NMDA receptor signaling during a brief postnatal period. Several key genes, includingDNMT3A,GATA2, andDPYSL3, are regulated by miR-132 and exhibited altered expression either during normal neurodevelopment or in tissue from adult schizophrenic subjects. Our data suggest miR-132 dysregulation and subsequent abnormal expression of miR-132 target genes contribute to the neurodevelopmental and neuromorphological pathologies present in schizophrenia.
Transient Ru-methyl formate intermediates generated with bifunctional transfer hydrogenation catalysts
Authors: Perry Richard H. , Brownell Kristen R. , Chingin Konstantin , Cahill Thomas J. , Waymouth Robert M. , Zare Richard N.
Published: February 2012

Desorption electrospray ionization (DESI) coupled to high-resolution Orbitrap mass spectrometry (MS) was used to study the reactivity of a (β-amino alcohol)(arene)RuCl transfer hydrogenation catalytic precursor in methanol (CH
3
OH). By placing [(
p
-cymene)RuCl
2
]
2
on a surface and spraying a solution of β-amino alcohol in methanol, two unique transient intermediates having lifetimes in the submillisecond to millisecond range were detected. These intermediates were identified as Ru (II) and Ru (IV) complexes incorporating methyl formate (HCOOCH
3
). The Ru (IV) intermediate is not observed when the DESI spray solution is sparged with Ar gas, indicating that O
2
dissolved in the solvent is necessary for oxidizing Ru (II) to Ru (IV). These proposed intermediates are supported by high-resolution and high mass accuracy measurements and by comparing experimental to calculated isotope profiles. Additionally, analyzing the bulk reaction mixture using gas chromatography-MS and nuclear magnetic resonance spectroscopy confirms the formation of HCOOCH
3
. These results represent an example that species generated from the (β-amino alcohol)(arene)RuCl (II) catalytic precursor can selectively oxidize CH
3
OH to HCOOCH
3
. This observation leads us to propose a pathway that can compete with the hydrogen transfer catalytic cycle. Although bifunctional hydrogen transfer with Ru catalysts has been well-studied, the ability of DESI to intercept intermediates formed in the first few milliseconds of a chemical reaction allowed identification of previously unrecognized intermediates and reaction pathways in this catalytic system.
The effect of mild depression on time discrimination
Authors: Msetfi Rachel M. , Murphy Robin A. , Kornbrot Diana E.
Published: February 2012

Depressed mood states affect subjective perceptions of time but it is not clear whether this is due to changes in the underlying timing mechanisms, such as the speed of the internal clock. In order to study depression effects on time perception, two experiments using time discrimination methods with short (<300 ms) and long (>1,000 ms) durations were conducted. Student participants who were categorized as mildly depressed by their scores on the Beck Depression Inventory were less able than controls to discriminate between two longer durations but were equally able to discriminate shorter intervals. The results suggest that mildly depressed or dysphoric moods do not affect pacemaker speed. It is more likely that depression affects the ability to maintain attention to elapsing duration.
A Crossover Trial of Antimicrobial Scrubs to Reduce Methicillin-Resistant Staphylococcus aureus Burden on Healthcare Worker Apparel
Authors: Bearman Gonzalo M. L. , Rosato Adriana , Elam Kara , Sanogo Kakotan , Stevens Michael P. , Sessler Curtis N. , Wenzel Richard P.
Published: February 2012

Background.

The impact of antimicrobial scrubs on healthcare worker (HCW) bacterial burden is unknown.

Objective.

To determine die effectiveness of antimicrobial scrubs on hand and apparel bacterial burden.

Design.

Prospective, crossover trial.

Setting and Participants.

Thirty HCWs randomized to study versus control scrubs in an intensive care unit.

Methods.

Weekly microbiology samples were obtained from scrub abdominal area, cargo pocket, and hands. Mean log colony-forming unit (CFU) counts were calculated. Compliance with hand hygiene practices was measured. Apparel and hand mean log CFU counts were compared.

Results.

Adherence measures were 78% (910/1,173) for hand hygiene and 82% (223/273) for scrubs. Culture compliance was 67% (306/460). No differences were observed in bacterial hand burden or in HCWs with unique positive scrub cultures. No difference in vancomycin-resistant enterococci (VRE) and gram-negative rod (GNR) burden was observed. A difference in mean log mediicillin-resistant Staphylococcus aureus (MRSA) CFU count was found between study and control scrubs for leg cargo pocket (mean log CFUs, 11.84 control scrub vs 6.71 study scrub; P = .0002), abdominal area (mean log CFUs, 11.35 control scrub vs 7.54 study scrub; P = .0056), leg cargo pocket at die beginning of shift (mean log CFUs, 11.96 control scrub vs 4.87 study scrub; P = .0028), and abdominal area pocket at die end of shift (mean log CFUs, 12.14 control scrubs vs 8.22 study scrub; P = .0054).

Conclusions.

Study scrubs were associated witfi a 4–7 mean log reduction in MRSA burden but not VRE or GNRs. A prospective trial is needed to measure die impact of antimicrobial impregnated apparel on MRSA transmission rates.

Infect Control Hosp Epidemiol 2012;33(3):268-275
Implementing Automated Surveillance for Tracking Clostridium difficile Infection at Multiple Healthcare Facilities
Authors: Dubberke Erik R. , Nyazee Humaa A. , Yokoe Deborah S. , Mayer Jeanmarie , Stevenson Kurt B. , Mangino Julie E. , Khan Yosef M. , Fraser Victoria J. ,   Centers for Disease Control and Prevention Epicenters Program
Published: February 2012

Automated surveillance using electronically available data has been found to be accurate and save time. An automated Clostridium difficile infection (CDI) surveillance algorithm was validated at 4 Centers for Disease Control and Prevention Epicenter hospitals. Electronic surveillance was highly sensitive, specific, and showed good to excellent agreement for hospital-onset; community-onset, study facility-associated; indeterminate; and recurrent CDI.

Infect Control Hosp Epidemiol 2012;33(3):305-308
The Impact of Depth of Infection and Postdischarge Surveillance on Rate of Surgical-Site Infections in a Network of Community Hospitals
Authors: Ming David Y. , Chen Luke F. , Miller Becky A. , Sexton Daniel J. , Anderson Deverick J.
Published: February 2012

Objective.

To describe the epidemiology of surgical-site infections (SSIs) in community hospitals and to explore the impact of depth of SSI, healthcare location at the time of diagnosis, and variations in surveillance practices on the overall rate of SSI.

Design.

Retrospective cohort study.

Setting.

Thirty-seven community hospitals in the southeastern United States.

Patients.

Consecutive sample of patients undergoing surgical procedures between July 1, 2007, and December 31, 2008.

Methods.

ANOVA was used to compare rates of SSIs, and the F test was used to compare the distribution of rates of SSIs. Wilcoxon rank-sum was used to test for differences in performance rankings of hospitals.

Results.

Following 177,706 surgical procedures, 1,919 SSIs were identified (incidence, 1.08 per 100 procedures). Sixty-four percent (1,223 of 1,919) of these were identified as complex SSIs; 87% of the complex SSIs were diagnosed in inpatient settings. The median proportion of superficial-incisional SSIs was 37% (interquartile range, 29.6%–49.5%). Postdischarge SSI surveillance was variable, with 58% of responding hospitals using surgeon letters. As reporting focus was narrowed from all SSIs to complex SSIs (incidence, 0.69 per 100 procedures) and, finally, to complex SSIs diagnosed in the inpatient setting (incidence, 0.51 per 100 procedures), variance in rates changed significantly (P = .02). Performance ranking of individual hospitals, based on rates of SSIs, differed significandy, depending on the reporting method utilized (P = .0006).

Conclusions.

Inconsistent reporting mediods focused on variable depths of infection and healthcare location at time of diagnosis significandy impact rates of SSI, distribution of rates of SSI, and hospital comparative-performance rankings. We believe that public reporting of SSI rates should be limited to complex SSIs diagnosed in the inpatient setting.

Infect Control Hosp Epidemiol 2012;33(3):276-282
Phylogenetic and ecological factors influencing the number and distribution of electroreceptors in elasmobranchs
Authors: Kempster R. M. , McCarthy I. D. , Collin S. P.
Published: February 2012

Electroreception is found throughout the animal kingdom from invertebrates to mammals and has been shown to play an important role in prey detection, facilitating social behaviours, the detection of predators and orientation to the earth's magnetic field for navigation. Electroreceptors in elasmobranchs, the ampullae of Lorenzini, detect minute electric fields and independently process these stimuli, thereby providing spatial information to the central nervous system on the location of a source, often potential prey. The ampullae of Lorenzini are individually connected to a single somatic pore on the surface of the skin, with the spatial separation of each pore directly influencing how electrical stimuli are detected and processed. Pore abundance varies across taxonomic groups resulting in unique species‐specific differences. The intricate distribution patterns created by the specific positioning of somatic pores on the head are, however, consistent within families, resulting in patterns that are identifiable at higher taxonomic levels. As elasmobranchs evolved, the electrosensory system became more complex and highly specialized, which is evident by a general trend of increasing pore abundance over time. The elasmobranch electrosensory system has evolved to operate efficiently under the environmental conditions of the particular habitat in which a species lives. For example, reduced pore abundance is evident in oceanic pelagic elasmobranchs, for whom visual cues are thought to be of great importance. Pore abundance and spatial distribution may be influenced by multiple factors including head morphology, phylogeny, feeding behaviour and habitat.
Acute respiratory infections due to enterovirus 68 in Yamagata, Japan between 2005 and 2010
Authors: Ikeda Tatsuya , Mizuta Katsumi , Abiko Chieko , Aoki Yoko , Itagaki Tsutomu , Katsushima Fumio , Katsushima Yuriko , Matsuzaki Yoko , Fuji Naoko , Imamura Tadatsugu , Oshitani Hitoshi , Noda Masahiro , Kimura Hirokazu , Ahiko Tadayuki
Published: February 2012

To clarify the epidemiology of enterovirus 68 (EV68), which is one of the most rarely identified enteroviruses, virus isolation and molecular screening using RT‐PCR was performed on 6307 respiratory specimens collected at pediatric clinics in Yamagata, Japan between 2005 and 2010. In the years 2005–2009, 10, 1, 2, 0, and 2 (40) EV68‐positive cases, respectively, were identified by RT‐PCR. In 2010, 40 cases were identified altogether: 2 by isolation only, 26 by RT‐PCR only, and 12 by both isolation and RT‐PCR. Phylogenetic analysis indicated that plural genetically distinct clusters co‐circulated. These results suggest that that difficulty in EV68 isolation leads to an underestimation of the prevalence of EV68 infections.
Differential expression pattern of ISG15 in different tissue explants and cells induced by various interferons
Authors: Yang Ling , Zhang Le‐Ying , Wang Chengming , Wang Bin , Wang Xue‐Min , Zeng Shen‐Ming
Published: February 2012

Interferon stimulated gene 15 (ISG15), an ubiquitin cross‐reactive protein, can conjugate to target proteins. Unlike ubiquitination, protein modification by ISG15 does not target protein for degradation, but enhances the cellular response to interferon (IFN), which plays a key role in antiviral responses. In this study, Western blot and/or immunocytochemistry were performed to explore the ISG15 expression patterns in explants of bovine endometrium, mammary gland and kidney, as well as Madin–Darby bovine kidney (MDBK), endometrial and mammary cells stimulated by IFN‐α, ‐β, and ‐τ. Western blot indicated that there are differential minimum antiviral units among recombinant bovine interferon‐α (rbIFN‐α, 102 IU/mL), rbIFN‐β (103 IU/mL) and rbIFN‐τ (104 IU/mL) in regard to stimulating saturation expression of free and ISG15‐conjugated proteins by MDBK cells and endometrial and mammary explants. These results were further confirmed through immunocytochemical analysis of MDBK, endometrial and mammary cells. For the first time it has been shown that the expression pattern of ISG15‐conjugated proteins occurs in a tissue‐specific manner. Furthermore, the present findings provide the first evidence of 10‐ to 100‐fold differences in minimum antiviral units of rbIFN‐α, rbIFN‐β, and rbIFN‐τ in regard to stimulating saturation expression of ISG15.