bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrodynamic modeling of surface plasmon enhanced photon induced current in a gold grating
Authors: English Alex , Cheng Cheng-Wen , Lowe Lloyd , Shih Min-Hsiung , Kuang Wan
Published: May 2011

The current induced by incident photons on an gold grating slab is investigated numerically and experimentally. A semiclassical electrodynamic model is developed under the weak nonlinearity approximation. Electrons in the conduction band are treated as an electron gas in the presence of a self-consistent electromagnetic field. The model is solved by the finite element method and compared with measurements. The calculated current density as a function of incident angle and wavelength is found to be in qualitative agreement with the experimental measurements. The results show that increasing surface plasmon spatial variation enhances photon induced current.
ZnO nanobarbed fibers: Fabrication, sensing NO2 gas, and their sensing mechanism
Authors: Lee Hyun-Uk , Ahn Kyun , Lee Su-Jae , Kim Jong-Pil , Kim Hyun-Gyu , Jeong Se-Young , Cho Chae-Ryong
Published: May 2011

ZnO nanobarbed fibers (NBFs) are synthesized by the epitaxial growth of 1–D ZnO nanorods (NRs) on ZnO nanofibers (NFs) via electrospinning and chemical bath deposition. The change in resistance of the NBFs in the presence or absence of a gas was explained using the surface depletion model and modified grain boundary model, in which the junction points of the NFs and NRs are considered. The NBF structure showed extraordinary NO2 sensing performance for gas concentrations up to 30 ppb. This indicates that NBF structures have great potential for use as gas sensing materials.
Photovoltage induced by ratchet effect in Si/SiGe heterostructures under microwave irradiation
Authors: Kannan E. S. , Bisotto I. , Portal J.-C. , Murali R. , Beck T. J.
Published: May 2011

Directed electron transport induced by polarized microwave in Si/SiGe heterostructure is investigated by patterning an array of semicircular antidots in hexagonal geometry. Carriers interact strongly with the asymmetric antidots under microwave radiation and the broken spatial symmetry drives the carriers to move preferably in one direction (ratchet effect), thereby generating a longitudinal photovoltage. In addition to this, the strong electron–electron interaction in Si/SiGe heterostructure favors a collective carrier motion along the sample edges, which gives rise to the transverse photovoltage. Both longitudinal and transverse photovoltage induced by ratchet effect opens up promising possibilities for Si/SiGe based photogalvanic detectors.
Anisotropic thermoelectric effect in helimagnetic tunnel junctions
Authors: Jia Chenglong , Berakdar Jamal
Published: May 2011

Thermoelectric transport across normal-metal/helical-multiferroic/ferromagnetic heterojunctions is theoretically investigated. We find an anisotropic charge and spin thermopower with a C2v symmetry. The angular dependence on the magnetization orientation of the ferromagnetic layer is substantiated by a phenomenological theory based on the symmetry of the effective spin-orbit interaction induced by the topology of the spiral magnetic order in the multiferroic barrier.
Charge transfer, lattice distortion, and quantum confinement effects in Pd, Cu, and Pd–Cu nanoparticles; size and alloying induced modifications in binding energy
Authors: Sengar Saurabh K. , Mehta B. R. , Gupta Govind
Published: May 2011

In this letter, effect of size and alloying on the core and valence band shifts of Pd, Cu, and Pd–Cu alloy nanoparticles has been studied. It has been shown that the sign and magnitude of the binding energy shifts is determined by the contributions of different effects; with quantum confinement and lattice distortion effects overlapping for size induced shifts in case of core levels and lattice distortion and charge transfer effects overlapping for alloying induced shifts at smaller sizes. These results are important for understanding gas molecule-solid surface interaction in metal and alloy nanoparticles in terms of valance band positions.
Photoinduced multimode coherent acoustic phonons of metallic nanoprisms and the effects of shape-induced anisotropic electronic stresses
Authors: Tai Po-Tse , Yu Pyng , Tang Jau
Published: May 2011

In this work we reported experimental measurements of ultrafast structural dynamics in metallic nanoprisms induced by a femtosecond laser pulse. The main focus of this study of anisotropic heating in nanoprisms is about laser fluence effects on photoexcitation of two planar coherent acoustic phonon modes, namely, the breathing mode and the totally symmetric mode. We presented a combined two-temperature model and 2-D Fermi-Pasta-Ulam model to explain both the dependence of the initial phases and the mode weight on the excitation power. Our transient optical absorption data for both the initial fast monotonic decay and the subsequent coherent acoustic oscillations clearly indicate the presence of anisotropic thermal expansion in nanoprisms.
Improvement of electroluminescent performance of n-ZnO/AlN/p-GaN light-emitting diodes by optimizing the AlN barrier layer
Authors: Zhang S. G. , Zhang X. W. , Yin Z. G. , Wang J. X. , Dong J. J. , Wang Z. G. , Qu S. , Cui B. , Wowchak A. M. , Dabiran A. M. , Chow P. P.
Published: May 2011

The effects of the growth temperature and thickness of AlN layer on the electroluminescence (EL) performance of n-ZnO/AlN/p-GaN devices have been systematically investigated. It is found that the higher growth temperature of AlN layer (TAlN) may facilitate the improvement of EL performance of the device, which is attributed to that the crystalline quality of AlN layer improves with increasing growth temperatures TAlN. Besides the crystallinity of AlN layer, the thickness of AlN barrier layer plays an important role on the performance of the device. The thinner AlN layer is not enough to cover the whole surface of GaN, while the thicker AlN layer is unfavorable to the tunneling of carriers and many of electrons will be captured and recombined nonradiatively via the deep donors within the thick AlN layer. We have demonstrated that the AlN layer at the growth temperature of 700 °C with an optimized thickness of around 10 nm could effectively confine the injected carriers and suppress the formation of interfacial layer, thus, the EL performance of n-ZnO/AlN/p-GaN device could be significantly improved.
Ohmic contact formation on n-type Ge by direct deposition of TiN
Authors: Iyota Masatoshi , Yamamoto Keisuke , Wang Dong , Yang Haigui , Nakashima Hiroshi
Published: May 2011

We succeeded in Ohmic contact formation on an n-Ge substrate by direct sputter deposition from a TiN target and subsequent postmetallization annealing (PMA) at 350 °C. The Schottky barrier heights of the TiN/n-Ge and TiN/p-Ge contacts were 0.18 eV and 0.50 eV, respectively, and were maintained up to a PMA temperature of 550 °C. These electrical characteristics are likely to be associated with an approximately 1-nm-thick interlayer formed at a TiN/Ge interface, which leads to the alleviation of the Fermi level pinning. We demonstrated the validity of the TiN/n-Ge contact using an n+/p junction, which showed an excellent ideal factor of n=1.01.
Silver vanadate nanoribbons: A label-free bioindicator in the conversion between human serum transferrin and apotransferrin via surface-enhanced Raman scattering
Authors: Zhou Qing , Shao Mingwang , Que Ronghui , Cheng Liang , Zhuo Shujuan , Tong Yanhua , Lee Shuit-Tong
Published: May 2011

Silver vanadate nanoribbons were synthesized via a hydrothermal process, which exhibited surface-enhanced Raman scattering effect. This surface-enhanced substrate was stable and reproducible for identifying human serum transferrin and human serum apotransferrin in the concentration of 1×10−5 M, which further exhibited significant sensitivity in monitoring the conversion of these two proteins in turn. This result showed that the silver vanadate nanoribbon might be employed as biomonitor in such systems.
Magnetic field insensitivity of magnetic domain wall velocity induced by electrical current in Co/Ni nanowire
Authors: Koyama T. , Chiba D. , Ueda K. , Tanigawa H. , Fukami S. , Suzuki T. , Ohshima N. , Ishiwata N. , Nakatani Y. , Ono T.
Published: May 2011

We have investigated the velocity of magnetic domain wall (DW) motion induced by electric currents in a Co/Ni nanowire with a perpendicular magnetic anisotropy. The DW velocity increased as current density increased and the maximum velocity of 60 m/s was observed. Furthermore, the DW velocity was found to be almost independent of external perpendicular magnetic fields in the range of −50 to +50 Oe. The mechanism of the observed field insensitivity of the current induced DW motion is also discussed.
Temperature- and magnetic-field-induced magnetization reversal in perovskite YFe0.5Cr0.5O3
Authors: Mao Jinhua , Sui Yu , Zhang Xingquan , Su Yantao , Wang Xianjie , Liu Zhiguo , Wang Yi , Zhu Ruibin , Wang Yang , Liu Wanfa , Tang Jinke
Published: May 2011

Perovskite YFe0.5Cr0.5O3 exhibits magnetization reversal at low applied fields due to the competition between the single ion magnetic anisotropy and the antisymmetric Dzyaloshinsky–Moriya interaction. Below a compensation temperature (Tcomp), a tunable bipolar switching of magnetization is demonstrated by changing the magnitude of the field while keeping it in the same direction. The present compound also displays both normal and inverse magnetocaloric effects above and below 260 K, respectively. These phenomena coexisting in a single magnetic system can be tuned in a predictable manner and have potential applications in electromagnetic devices.
Negative differential resistance in bilayer graphene nanoribbons
Authors: Habib K. M. Masum , Zahid Ferdows , Lake Roger K.
Published: May 2011

Lack of a bandgap is one of the significant challenges for application of graphene as the active element of an electronic device. A bandgap can be induced in bilayer graphene by application of a potential difference between the two layers. The simplest geometry for creating such a potential difference is two overlayed graphene nanoribbons independently contacted. Calculations, based on density functional theory and the nonequilibrium Green’s function formalism, show that transmission through such a structure is a strong function of applied bias. The simulated current voltage characteristics mimic the characteristics of resonant tunneling diode featuring negative differential resistance.
Direct measurement of compositional complexity-induced electronic inhomogeneity in VO2 thin films grown on gate dielectrics
Authors: Yang Zheng , Ramanathan Shriram
Published: May 2011

We report on measurements of variation in metal-insulator transition characteristics through thickness in VO2 film grown on model SiO2 gate insulator by nanometric scale controlled etching followed by electrical and compositional measurements. The phase transition magnitude defined as ratio of resistivity at 25 °C to that at 100 °C of VO2 decreases from ∼159 at the surface to ∼14 at ∼10 nm away from a VO2/SiO2 interface, showing a difference of >10 times, while that for a VO2 thin film grown with identical conditions on single crystal sapphire only shows ∼3 times difference. The off-stoichiometric composition near the VO2/SiO2 interface induced by unoriented growth on amorphous SiO2 is likely responsible for the dramatic change in transition characteristics.
Enhancement of the ferromagnetic order of graphite after sulphuric acid treatment
Authors: Barzola-Quiquia J. , Böhlmann W. , Esquinazi P. , Schadewitz A. , Ballestar A. , Dusari S. , Schultze-Nobre L. , Kersting B.
Published: May 2011

We have studied the changes in the ferromagnetic behavior of graphite powder and graphite flakes after treatment with diluted sulphuric acid. We show that this kind of acid treatment enhances substantially the ferromagnetic magnetization of virgin graphite micrometer size powder as well as in graphite flakes. The anisotropic magnetoresistance amplitude at 300 K measured in a micrometer size thin graphite flake after acid treatment reaches values comparable to polycrystalline cobalt.
Nonblinking green emission from single H3 color centers in nanodiamonds
Authors: Hsu Jui-Hung , Su Wei-De , Yang Kai-Lin , Tzeng Yan-Kai , Chang Huan-Cheng
Published: May 2011

This work investigates the emission properties of single color centers in natural diamond nanoparticles for potential use as single photon sources and photostable biomarkers. Two emitters, H3 and H4, were identified by their sharp zero-phonon lines at 503 nm and 496 nm, respectively, in the photoluminescence spectra. Using a modified Hanbury Brown and Twiss setup, we observed complete photon antibunching for the H3 center. No fluorescence blinking was detected for a single H3 emitter on the ms timescale, indicating weak coupling between the electronic transition A11↔B11 and adjacent metastable states of this nitrogen-vacancy-nitrogen point defect.
Gouy phase anomaly in photonic nanojets
Authors: Kim Myun-Sik , Scharf Toralf , Mühlig Stefan , Rockstuhl Carsten , Herzig Hans Peter
Published: May 2011

We investigate in real space amplitude and phase distributions of light in photonic nanojets emerging from micrometer-sized dielectric spheres with a high-resolution interference microscope. Strong localization of light and a Gouy phase anomaly are witnessed. We show that the phase advance of photonic nanojets significantly deviates from a plane wave due to the sudden transition from a converging to a diverging wave front. Understanding such phase anomalies and verifying the presence of photonic nanojets promises to pave the way to prospective applications that may exploit the ability to localize light in spatial domains smaller than the usual resolution limit.
Laser ablation of polymer coatings allows for electromagnetic field enhancement mapping around nanostructures
Authors: Fiutowski J. , Maibohm C. , Kjelstrup-Hansen J. , Rubahn H.-G.
Published: May 2011

Subdiffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures. The accompanying field enhancement substantially lowers the ablation threshold of the polymer film and thus creates local ablation spots and corresponding topographic modifications of the polymer film. Such modifications are quantified straightforwardly via scanning electron microscopy and atomic force microscopy. Thickness variation in the polymer film enables the investigation of either the initial ablation phase or ablation induced by collective enhancement effects.
Optical bistability in InGaN-based multisection laser diodes
Authors: Dorsaz J. , Boïko D. L. , Sulmoni L. , Carlin J.-F. , Scheibenzuber W. G. , Schwarz U. T. , Grandjean N.
Published: May 2011

Optical bistability is observed in cw-operating InGaN-based laser diodes including a saturable absorber (SA) section. The dependence of the light-current hysteresis on the SA section length and reverse bias (VSA) has been studied. An analytical approach is developed to estimate the carrier lifetime τa in the SA section from the measurements of the hysteresis width, which leads to τa=1.9 ns at zero bias. τa is found to decrease rapidly for higher reverse biases and a minimum of τa=0.4 ns is interpolated for flatband conditions. We explain the dependence of the carrier lifetime on VSA via the modification of the quantum-confined Stark effect.
Irradiation induced ferromagnetism at room temperature in TiO2 thin films: X-ray magnetic circular dichroism characterizations
Authors: Thakur Hardeep , Thakur P. , Kumar Ravi , Brookes N. B. , Sharma K. K. , Singh A. P. , Kumar Yogesh , Gautam S. , Chae K. H.
Published: May 2011

We report on the room temperature ferromagnetism in the swift heavy ion (SHI) irradiated TiO2 thin films by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) experiments at the O K and Ti L3,2 absorption edges. The XAS/XMCD measurements provide direct evidence of magnetic polarization of the O 2p and Ti 3d orbitals. The unquenched orbital magnetic moment within the O 2p shell is ferromagnetically coupled to the neighboring Ti moments, which illustrates the intense hybridization of the O 2p and Ti 3d orbitals induced by SHI irradiation.
Hole mobility in wurtzite InN
Authors: Ma N. , Wang X. Q. , Liu S. T. , Chen G. , Pan J. H. , Feng L. , Xu F. J. , Tang N. , Shen B.
Published: May 2011

Hole mobility in wurtzite InN at low electric fields is studied by an ensemble Monte Carlo calculation. Scatterings of holes by polar optical phonons, nonpolar optical phonons, acoustic phonons, ionized and neutral impurities, and threading dislocations are taken into account. Mobility of holes is ∼220 cm2/V s at 300 K in the InN, where holes are only scattered by the lattice. It decreases to 20–70 cm2/V s when the present quality of InN with threading dislocation density of ∼1010 cm−2 and residual donor concentration of over 1017 cm−3 is considered. The calculated mobility coincides well with the recent experimental observation.
Imaging the electromechanical activity of the heart in vivo
Authors: Provost Jean , Lee Wei-Ning , Fujikura Kana , Konofagou Elisa E.
Published: May 2011

Cardiac conduction abnormalities remain a major cause of death and disability worldwide. However, as of today, there is no standard clinical imaging modality that can noninvasively provide maps of the electrical activation. In this paper, electromechanical wave imaging (EWI), a novel ultrasound-based imaging method, is shown to be capable of mapping the electromechanics of all four cardiac chambers at high temporal and spatial resolutions and a precision previously unobtainable in a full cardiac view in both animals and humans. The transient deformations resulting from the electrical activation of the myocardium were mapped in 2D and combined in 3D biplane ventricular views. EWI maps were acquired during five distinct conduction configurations and were found to be closely correlated to the electrical activation sequences. EWI in humans was shown to be feasible and capable of depicting the normal electromechanical activation sequence of both atria and ventricles. This validation of EWI as a direct, noninvasive, and highly translational approach underlines its potential to serve as a unique imaging tool for the early detection, diagnosis, and treatment monitoring of arrhythmias through ultrasound-based mapping of the transmural electromechanical activation sequence reliably at the point of care, and in real time.
Genetic analysis of age-dependent defects of the
Caenorhabditis elegans
touch receptor neurons
Authors: Pan Chun-Liang , Peng Chiu-Ying , Chen Chun-Hao , McIntire Steven
Published: May 2011

Although many genes have been implicated in the pathogenesis of common neurodegenerative diseases, the genetic and cellular mechanisms that maintain neuronal integrity during normal aging remain elusive. Here we show that
Caenorhabditis elegans
touch receptor and cholinergic neurons display age-dependent morphological defects, including cytoskeletal disorganization, axon beading, and defasciculation. Progression of neuronal aging is regulated by DAF-2 and DAF-16 signaling, which also modulate adult life span. Mutations that disrupt touch-evoked sensory activity or reduce membrane excitability trigger accelerated neuronal aging, indicating that electrical activity is critical for adult neuronal integrity. Disrupting touch neuron attachment to the epithelial cells induces distinct neurodegenerative phenotypes. These results provide a detailed description of the age-dependent morphological defects that occur in identified neurons of
C. elegans
, demonstrate that the age of onset of these defects is regulated by specific genes, and offer experimental evidence for the importance of normal levels of neural activity in delaying neuronal aging.
Amphioxus FGF signaling predicts the acquisition of vertebrate morphological traits
Authors: Bertrand Stephanie , Camasses Alain , Somorjai Ildiko , Belgacem Mohamed R. , Chabrol Olivier , Escande Marie-Line , Pontarotti Pierre , Escriva Hector
Published: May 2011

FGF signaling is one of the few cell–cell signaling pathways conserved among all metazoans. The diversity of FGF gene content among different phyla suggests that evolution of FGF signaling may have participated in generating the current variety of animal forms. Vertebrates possess the greatest number of FGF genes, the functional evolution of which may have been implicated in the acquisition of vertebrate-specific morphological traits. In this study, we have investigated the roles of the FGF signal during embryogenesis of the cephalochordate amphioxus, the best proxy for the chordate ancestor. We first isolate the full FGF gene complement and determine the evolutionary relationships between amphioxus and vertebrate FGFs via phylogenetic and synteny conservation analysis. Using pharmacological treatments, we inhibit the FGF signaling pathway in amphioxus embryos in different time windows. Our results show that the requirement for FGF signaling during gastrulation is a conserved character among chordates, whereas this signal is not necessary for neural induction in amphioxus, in contrast to what is known in vertebrates. We also show that FGF signal, acting through the MAPK pathway, is necessary for the formation of the most anterior somites in amphioxus, whereas more posterior somite formation is not FGF-dependent. This result leads us to propose that modification of the FGF signal function in the anterior paraxial mesoderm in an amphioxus-like vertebrate ancestor might have contributed to the loss of segmentation in the preotic paraxial mesoderm of the vertebrate head.
Functional importance of telomerase pseudoknot revealed by single-molecule analysis
Authors: Mihalusova Mariana , Wu John Y. , Zhuang Xiaowei
Published: May 2011

Telomerase ribonucleoprotein (RNP) employs an RNA subunit to template the addition of telomeric repeats onto chromosome ends. Previous studies have suggested that a region of the RNA downstream of the template may be important for telomerase activity and that the region could fold into a pseudoknot. Whether the pseudoknot motif is formed in the active telomerase RNP and what its functional role is have not yet been conclusively established. Using single-molecule FRET, we show that the isolated pseudoknot sequence stably folds into a pseudoknot. However, in the context of the full-length telomerase RNA, interference by other parts of the RNA prevents the formation of the pseudoknot. The protein subunits of the telomerase holoenzyme counteract RNA-induced misfolding and allow a significant fraction of the RNPs to form the pseudoknot structure. Only those RNP complexes containing a properly folded pseudoknot are catalytically active. These results not only demonstrate the functional importance of the pseudoknot but also reveal the critical role played by telomerase proteins in pseudoknot folding.
Integrin adhesion drives the emergent polarization of active cytoskeletal stresses to pattern cell delamination
Authors: Meghana C. , Ramdas Nisha , Hameed Feroz Meeran , Rao Madan , Shivashankar G. V. , Narasimha Maithreyi
Published: May 2011

Tissue patterning relies on cellular reorganization through the interplay between signaling pathways and mechanical stresses. Their integration and spatiotemporal coordination remain poorly understood. Here we investigate the mechanisms driving the dynamics of cell delamination, diversely deployed to extrude dead cells or specify distinct cell fates. We show that a local mechanical stimulus (subcellular laser perturbation) releases cellular prestress and triggers cell delamination in the amnioserosa during
Drosophila
dorsal closure, which, like spontaneous delamination, results in the rearrangement of nearest neighbors around the delaminating cell into a rosette. We demonstrate that a sequence of “emergent cytoskeletal polarities” in the nearest neighbors (directed myosin flows, lamellipodial growth, polarized actomyosin collars, microtubule asters), triggered by the mechanical stimulus and dependent on integrin adhesion, generate active stresses that drive delamination. We interpret these patterns in the language of active gels as asters formed by active force dipoles involving surface and body stresses generated by each cell and liken delamination to mechanical yielding that ensues when these stresses exceed a threshold. We suggest that differential contributions of adhesion, cytoskeletal, and external stresses must underlie differences in spatial pattern.
Decellularized tissue-engineered blood vessel as an arterial conduit
Authors: Quint Clay , Kondo Yuka , Manson Roberto J. , Lawson Jeffrey H. , Dardik Alan , Niklason Laura E.
Published: May 2011

Arterial tissue-engineering techniques that have been reported previously typically involve long waiting times of several months while cells from the recipient are cultured to create the engineered vessel. In this study, we developed a different approach to arterial tissue engineering that can substantially reduce the waiting time for a graft. Tissue-engineered vessels (TEVs) were grown from banked porcine smooth muscle cells that were allogeneic to the intended recipient, using a biomimetic perfusion system. The engineered vessels were then decellularized, leaving behind the mechanically robust extracellular matrix of the graft wall. The acellular grafts were then seeded with cells that were derived from the intended recipient—either endothelial progenitor cells (EPC) or endothelial cell (EC)—on the graft lumen. TEV were then implanted as end-to-side grafts in the porcine carotid artery, which is a rigorous testbed due to its tendency for graft occlusion. The EPC- and EC-seeded TEV all remained patent for 30 d in this study, whereas the contralateral control vein grafts were patent in only 3/8 implants. Going along with the improved patency, the cell-seeded TEV demonstrated less neointimal hyperplasia and fewer proliferating cells than did the vein grafts. Proteins in the mammalian target of rapamycin signaling pathway tended to be decreased in TEV compared with vein grafts, implicating this pathway in the TEV's resistance to occlusion from intimal hyperplasia. These results indicate that a readily available, decellularized tissue-engineered vessel can be seeded with autologous endothelial progenitor cells to provide a biological vascular graft that resists both clotting and intimal hyperplasia. In addition, these results show that engineered connective tissues can be grown from banked cells, rendered acellular, and then used for tissue regeneration in vivo.
Ubiquitin-recognition protein Ufd1 couples the endoplasmic reticulum (ER) stress response to cell cycle control
Authors: Chen Meifan , Gutierrez Gustavo J. , Ronai Ze'ev A.
Published: May 2011

The ubiquitin-recognition protein Ufd1 facilitates clearance of misfolded proteins through the endoplasmic reticulum (ER)-associated degradation (ERAD) pathway. Here we report that prolonged ER stress represses Ufd1 expression to trigger cell cycle delay, which contributes to ERAD. Remarkably, down-regulation of Ufd1 enhances ubiquitination and destabilization of Skp2 mediated by the anaphase-promoting complex or cyclosome bound to Cdh1 (APC/C
Cdh1
), resulting in accumulation of the cyclin-dependent kinase inhibitor p27 and a concomitant cell cycle delay during the G1 phase that enables more efficient clearance of misfolded proteins. Mechanistically, nuclear Ufd1 recruits the deubiquitinating enzyme USP13 to counteract APC/C
Cdh1
-mediated ubiquitination of Skp2. Our data identify a coordinated cell cycle response to prolonged ER stress through regulation of the Cdh1-Skp2-p27 axis by Ufd1 and USP13.
Recurrent chimeric RNAs enriched in human prostate cancer identified by deep sequencing
Authors: Kannan Kalpana , Wang Liguo , Wang Jianghua , Ittmann Michael M. , Li Wei , Yen Laising
Published: May 2011

Transcription-induced chimeric RNAs, possessing sequences from different genes, are expected to increase the proteomic diversity through chimeric proteins or altered regulation. Despite their importance, few studies have focused on chimeric RNAs especially regarding their presence/roles in human cancers. By deep sequencing the transcriptome of 20 human prostate cancer and 10 matched benign prostate tissues, we obtained 1.3 billion sequence reads, which led to the identification of 2,369 chimeric RNA candidates. Chimeric RNAs occurred in significantly higher frequency in cancer than in matched benign samples. Experimental investigation of a selected 46 set led to the confirmation of 32 chimeric RNAs, of which 27 were highly recurrent and previously undescribed in prostate cancer. Importantly, a subset of these chimeras was present in prostate cancer cell lines, but not detectable in primary human prostate epithelium cells, implying their associations with cancer. These chimeras contain discernable 5′ and 3′ splice sites at the RNA junction, indicating that their formation is mediated by splicing. Their presence is also largely independent of the expression of parental genes, suggesting that other factors are involved in their production and regulation. One chimera,
TMEM79-SMG5
, is highly differentially expressed in human cancer samples and therefore a potential biomarker. The prevalence of chimeric RNAs may allow the limited number of human genes to encode a substantially larger number of RNAs and proteins, forming an additional layer of cellular complexity. Together, our results suggest that chimeric RNAs are widespread, and increased chimeric RNA events could represent a unique class of molecular alteration in cancer.
Climatically driven biogeographic provinces of Late Triassic tropical Pangea
Authors: Whiteside Jessica H. , Grogan Danielle S. , Olsen Paul E. , Kent Dennis V.
Published: May 2011

Although continents were coalesced into the single landmass Pangea, Late Triassic terrestrial tetrapod assemblages are surprisingly provincial. In eastern North America, we show that assemblages dominated by traversodont cynodonts are restricted to a humid 6° equatorial swath that persisted for over 20 million years characterized by “semiprecessional” (approximately 10,000-y) climatic fluctuations reflected in stable carbon isotopes and sedimentary facies in lacustrine strata. More arid regions from 5–20°N preserve procolophonid-dominated faunal assemblages associated with a much stronger expression of approximately 20,000-y climatic cycles. In the absence of geographic barriers, we hypothesize that these variations in the climatic expression of astronomical forcing produced latitudinal climatic zones that sorted terrestrial vertebrate taxa, perhaps by excretory physiology, into distinct biogeographic provinces tracking latitude, not geographic position, as the proto-North American plate translated northward. Although the early Mesozoic is usually assumed to be characterized by globally distributed land animal communities due to of a lack of geographic barriers, strong provinciality was actually the norm, and nearly global communities were present only after times of massive ecological disruptions.
Soluble epoxide hydrolase deficiency alters pancreatic islet size and improves glucose homeostasis in a model of insulin resistance
Authors: Luria Ayala , Bettaieb Ahmed , Xi Yannan , Shieh Guang-Jong , Liu Hsin-Chen , Inoue Hiromi , Tsai Hsing-Ju , Imig John D. , Haj Fawaz G. , Hammock Bruce D.
Published: May 2011

Visceral obesity has been defined as an important element of the metabolic syndrome and contributes to the development of insulin resistance and cardiovascular disease. Increasing endogenous levels of epoxyeicosatrienoic acids (EETs) are known for their analgesic, antihypertensive, and antiinflammatory effects. The availability of EETs is limited primarily by the soluble epoxide hydrolase (sEH,
EPHX2
), which metabolizes EETs to their less active diols. In this study, we tested the hypothesis that EETs are involved in glucose regulation and in retarding the development of insulin resistance. To address the role of EETs in regulating glucose homeostasis and insulin signaling, we used mice with targeted gene deletion of sEH (
Ephx2
-null mice) and a subsequent study with a selective sEH inhibitor. When wild-type mice are fed a high fat diet, insulin resistance develops. However, knockout or inhibition of sEH activity resulted in a significant decrease in plasma glucose. These findings are characterized by enhancement of tyrosyl phosphorylation of the insulin receptor, insulin receptor substrate 1, and their downstream cascade. In addition, pancreatic islets were larger when sEH was disrupted. This effect was associated with an increase in vasculature. These observations were supported by pharmacological inhibition of sEH. These data suggest that an increase in EETs due to sEH-gene knockout leads to an increase in the size of islets and improved insulin signaling and sensitivity.
Regulation of human EGF receptor by lipids
Authors: Coskun Ünal , Grzybek Michał , Drechsel David , Simons Kai
Published: May 2011

The human epidermal growth factor receptor (EGFR) is a key representative of tyrosine kinase receptors, ubiquitous actors in cell signaling, proliferation, differentiation, and migration. Although the receptor is well-studied, a central issue remains: How does the compositional diversity and functional diversity of the surrounding membrane modulate receptor function? Reconstituting human EGFR into proteoliposomes of well-defined and controlled lipid compositions represents a minimal synthetic approach to systematically address this question. We show that lipid composition has little effect on ligand-binding properties of the EGFR but rather exerts a profound regulatory effect on kinase domain activation. Here, the ganglioside GM3 but not other related lipids strongly inhibited the autophosphorylation of the EGFR kinase domain. This inhibitory action of GM3 was only seen in liposomes compositionally poised to phase separate into coexisting liquid domains. The inhibition by GM3 was released by either removing the neuraminic acid of the GM3 headgroup or by mutating a membrane proximal lysine of EGFR (K642G). Our results demonstrate that GM3 exhibits the potential to regulate the allosteric structural transition from inactive to a signaling EGFR dimer, by preventing the autophosphorylation of the intracellular kinase domain in response to ligand binding.
Adaptive shape processing in primary visual cortex
Authors: McManus Justin N. J. , Li Wu , Gilbert Charles D.
Published: May 2011

The ability to derive meaning from complex sensory input requires the integration of information over space and time, as well as cognitive mechanisms to shape that integration. We studied these processes in the primary visual cortex (V1), where neurons are thought to integrate visual inputs along contours defined by an association field (AF). We recorded extracellularly from single cells in macaque V1 to map the AF, by using an optimization algorithm to find the contours that maximally activated individual cells. We combined the algorithm with a delayed-match-to-sample task, to test how the optimal contours might be molded by the monkey's expectation for particular cue shapes. We found that V1 neurons were selective for complex shapes, a property previously ascribed to higher cortical areas. Furthermore, the shape selectivity was reprogrammed by perceptual task: Over the whole network, the optimal modes of geometric selectivity shifted between distinct subsets of the AF, alternately representing different stimulus features known to predominate in natural scenes. Our results suggest a general model of cortical function, whereby horizontal connections provide a broad domain of potential associations, and top–down inputs dynamically gate these linkages to task switch the function of a network.
Phosphorylation state of a Tob/BTG protein, FOG-3, regulates initiation and maintenance of the
Caenorhabditis elegans
sperm fate program
Authors: Lee Myon-Hee , Won Kim Kyung , Morgan Clinton T. , Morgan Dyan E. , Kimble Judith
Published: May 2011

FOG-3, the single
Caenorhabditis elegans
Tob/BTG protein, directs germ cells to adopt the sperm fate at the expense of oogenesis. Importantly, FOG-3 activity must be maintained for the continued production of sperm that is typical of the male sex. Vertebrate Tob proteins have antiproliferative activity and ERK phosphorylation of Tob proteins has been proposed to abrogate “antiproliferative” activity. Here we investigate FOG-3 phosphorylation and its effect on sperm fate specification. We found both phosphorylated and unphosphorylated forms of FOG-3 in nematodes. We then interrogated the role of FOG-3 phosphorylation in sperm fate specification. Specifically, we assayed FOG-3 transgenes for rescue of a
fog-3
null mutant. Wild-type FOG-3 rescued both initiation and maintenance of sperm fate specification. A FOG-3 mutant with its four consensus ERK phosphorylation sites substituted to alanines, called FOG-3(4A), rescued partially: sperm were made transiently but not continuously in both sexes. A different FOG-3 mutant with its sites substituted to glutamates, called FOG-3(4E), had no rescuing activity on its own, but together with FOG-3(4A) rescue was complete. Thus, when FOG-3(4A) and FOG-3(4E) were both introduced into the same animals, sperm fate specification was not only initiated but also maintained, resulting in continuous spermatogenesis in males. Our findings suggest that unphosphorylated FOG-3 initiates the sperm fate program and that phosphorylated FOG-3 maintains that program for continued sperm production typical of males. We discuss implications of our results for Tob/BTG proteins in vertebrates.
Defining the City ‘Trumpeter’: German Civic Identity and the Employment of Brass Instrumentalists, c.1500
Authors: Green Helen
Published: May 2011

This article examines the employment of brass instrumentalists in German cities around 1500, as a reflection of the political circumstances of the epoch, where rivalry between the distinct components of the social hierarchy encouraged the assertion of power and status through musical patronage. Archival records and contemporary chronicles provide invaluable insights into the performances of civic brass instrumentalists, whether in the provision of signals (by the city watchmen or those who played alongside the cities’ troops) or for the entertainment of the citizens and their guests (within the civic instrumental ensembles – the Stadtpfeifer (‘town pipers’)). Although the use of ambiguous nomenclature in contemporary records can hinder a definitive understanding of the instruments used by these musicians, the musicians different duties within the city walls can often be inferred. Important insights can thereby be gained into the extent of the patronage of these civic brass instrumentalists, their roles within everyday city life, and their resultant contribution to the communication of civic strength to the populace and their guests.
Hispanic Traditions in a Cross-Cultural Perspective: Raoul Laparra's La habanera (1908) and French Critics
Authors: Llano Samuel
Published: May 2011

The French composer Raoul Laparra held an advanced knowledge of Spanish culture and music that was rare among French musicians. In his first opera, La habanera (Opéra-Comique, 1908), he tried to represent a Spain that was ‘different from Carmen’, focused on the ‘colder’ central region of Castile rather than southern, gypsy stereotypes. However, owing to several inconsistencies in his ideological agenda, and the weight of conventional representations of Spanish music and culture, Laparra rendered a contradictory image of Spain, which drew partly on the very southern and gypsy stereotypes he had intended to oust. Furthermore, the French critics’ lack of familiarity with Spanish traditions caused his project to be misunderstood. Those critics read La habanera in the context of French cultural struggles, mostly related to the definition of a national identity and the influence of Italian and German music.
Musical Emergence in Björk's Medúlla
Authors: Malawey Victoria
Published: May 2011

Björk's 2004 album Medúlla offers listeners radical and new combinations of vocal sounds in pop music. The album features emergent processes ranging from textural emergence, as in standard pop-rock formulas for song introductions, to less common emergent and transformative processes involving metrical, tonal, motivic and phrasal structure. When such processes involving different parameters are combined, other (non-emergent) processes recede to the background, and the effect of emergence assumes a fundamental role over the course of the composition as a whole. Recognizing emergent processes opens up connections with song lyrics and possibly also extra-musical narratives which can enrich our analytical understanding and ultimately our listening experiences of these songs. Furthermore, Medúlla models ways in which other contemporary songwriters could develop sophisticated emergent processes that disturb conventional understandings of popular music as simplistic and formulaic.
Handel and Homosexuality: Burlington House and Cannons Revisited
Authors: McGeary Thomas
Published: May 2011

It has been claimed that Burlington House and Cannons, the homes of the Earl of Burlington and the Duke of Chandos, were homosexual or homoerotic settings and that Handel's presence in these environments suggests that he was ‘gay’ or influenced the secular works he composed there. Examining in detail biographical information about John Gay, Alexander Pope and William Kent, eighteenth-century biographical accounts of Handel and insights from the history of sexuality, this article argues that there is no basis for these claims about the homosexual milieux at Burlington House and Cannons or for Handel's sexuality.
The Expansion of Symphonic Space in Mahler's First Symphony
Authors: Peattie Thomas
Published: May 2011

This article explores the treatment of space in Gustav Mahler's First Symphony from the perspective of the composer's experience as a conductor of opera. It considers the ‘theatrically’ located offstage utterances in the work's introduction in light of passages from Beethoven's Fidelio (Act 2, scene ii) and Tristan und Isolde (Act 2, scene ii), and against the backdrop of Mahler's controversial attempt to assign the Alla marcia section from the Finale of Beethoven's Ninth Symphony to a small offstage orchestra. By considering in turn the implications of Mahler's treatment of offstage space on the work's overall structure, specifically with respect to the moment of ‘breakthrough’ in the first and last movements, I suggest that Mahler ultimately re-establishes the vitality of the symphony as genre at the intersection between the waning symphonic tradition and the immediacy of operatic convention.
Harvey McMahon: Ahead of the curve on membrane dynamics
Authors: Short Ben
Published: May 2011

McMahon studies how membranes are bent into shape during vesicle formation and fusion.
Two MAPK-signaling pathways are required for mitophagy in Saccharomyces cerevisiae
Authors: Mao Kai , Wang Ke , Zhao Mantong , Xu Tao , Klionsky Daniel J.
Published: May 2011

Macroautophagy (hereafter referred to simply as autophagy) is a catabolic pathway that mediates the degradation of long-lived proteins and organelles in eukaryotic cells. The regulation of mitochondrial degradation through autophagy plays an essential role in the maintenance and quality control of this organelle. Compared with our understanding of the essential function of mitochondria in many aspects of cellular metabolism such as energy production and of the role of dysfunctional mitochondria in cell death, little is known regarding their degradation and especially how upstream signaling pathways control this process. Here, we report that two mitogen-activated protein kinases (MAPKs), Slt2 and Hog1, are required for mitophagy in Saccharomyces cerevisiae. Slt2 is required for the degradation of both mitochondria and peroxisomes (via pexophagy), whereas Hog1 functions specifically in mitophagy. Slt2 also affects the recruitment of mitochondria to the phagophore assembly site (PAS), a critical step in the packaging of cargo for selective degradation.
Novel molecular discharge light sources
Authors: Hilbig R , Koerber A , Schwan S , Hayashi D
Published: May 2011

A systematic investigation into transition metal halides and oxides showed the high potential of transition metal oxides as visible radiators for highly efficient gas discharge light sources. Zirconium monoxide (ZrO) has been identified as the most promising candidate combining highly attractive green and red emission band systems with very high dissociation energy (8.2 eV) which ensures that the molecule is stable even at the hot plasma centre. Thus far, however, it has been impossible to keep ZrO in the gas phase of a closed discharge vessel, because at wall temperature usually compounds are formed which have negligible vapour pressures. We succeeded in establishing a regenerative chemical cycle by filling ZrX
4 (X = Cl, Br, I) together with a stable, but volatile oxygen compound (like MoO2
X
2) and realized thus highly attractive, novel gas discharge light sources.
Standard enthalpies of formation, entropies and heat capacities of the lanthanide monohalides, LnX⟨g⟩, X = F, Cl, Br, I
Authors: Mucklejohn S A
Published: May 2011

Molecular constants and dissociation energies reported in the literature, supplemented by some estimated parameters, have been used to derive the molar heat capacities, molar entropies and molar standard enthalpies of formation for the lanthanide monohalides, LnX⟨g⟩, for Ln = Ba, La to Lu and X = F, Cl, Br, I.
Microplasma light tiles: thin sheet lamps for general illumination
Authors: Eden J G , Park S-J , Herring C M , Bulson J M
Published: May 2011

Flat, thin and lightweight lamps providing spatially uniform and dimmable illumination from active areas as large as 400 cm2 are being developed for general illumination and specialty applications. Comprising an array of low-temperature, nonequilibrium microplasmas driven by a dielectric barrier structure and operating at pressures of typically 400–700 Torr, these lamps have a packaged thickness <4 mm and yet produce luminance values beyond 26 000 cd m−2 with a luminous efficacy approaching 30 lm W−1. Third generation lamps, presently in limited production, offer a correlated colour temperature in the 3000–4100 K interval and a colour rendering index of 80. Current lamps employ Xe2 (λ ∼ 172 nm) as the primary emitter photoexciting a mixture of phosphors, and the pressure dependence of the wavelength-integrated fluorescence from the electronically excited dimer has been investigated with a vacuum ultraviolet spectrometer. In contrast to other promising lighting technologies, the decline in luminous efficacy of microplasma lamps with increasing power delivered to the lamp is small. For a 6 × 6 inch2 (∼225 cm2) lamp, efficacy falls <16% when the radiant output (luminance) is raised from 2000 cd m−2 to > 10 000 cd m−2.
Experimental and theoretical characterization of a multi-wavelength DBD-driven exciplex lamp operated with mercury bromide/rare gas mixtures
Authors: Guivan Mykola M , Malinina Antonina A , Brablec Antonin
Published: May 2011

Emission spectra from an atmospheric-pressure dielectric barrier discharge (DBD) with HgBr2/He or HgBr2/Xe/Kr mixtures, as well as the electrical characteristics, were investigated at repetition frequencies of sinusoidal voltage pulses up to 125 kHz. In the spectra, the study revealed radiation from HgBr(B–X, C–X) exciplex molecules, atomic lines of mercury and rare gases, and in mixtures with xenon, radiation of XeBr(B–X, B–A) exciplex molecules. Regularities in the spectral characteristics of the radiation from the gas-discharge plasma were discussed. The electron energy distribution function, the specific energy lost in the processes involving electrons, the electron temperature and density, and the rate constants of elastic and inelastic electron scattering by the components of the working mixture were calculated as functions of the reduced field E/N. The high-frequency atmospheric-pressure barrier discharge in mixtures of mercury dibromide with gases can be used in multi-wavelength exciplex lamps, operating in the UV and visible regions.