WorldWideScience

Sample records for induces gap junction-dependant

  1. Analysis of the Gap Junction-dependent Transfer of miRNA with 3D-FRAP Microscopy.

    Science.gov (United States)

    Lemcke, Heiko; Voronina, Natalia; Steinhoff, Gustav; David, Robert

    2017-06-19

    Small antisense RNAs, like miRNA and siRNA, play an important role in cellular physiology and pathology and, moreover, can be used as therapeutic agents in the treatment of several diseases. The development of new, innovative strategies for miRNA/siRNA therapy is based on an extensive knowledge of the underlying mechanisms. Recent data suggest that small RNAs are exchanged between cells in a gap junction-dependent manner, thereby inducing gene regulatory effects in the recipient cell. Molecular biological techniques and flow cytometric analysis are commonly used to study the intercellular exchange of miRNA. However, these methods do not provide high temporal resolution, which is necessary when studying the gap junctional flux of molecules. Therefore, to investigate the impact of miRNA/siRNA as intercellular signaling molecules, novel tools are needed that will allow for the analysis of these small RNAs at the cellular level. The present protocol describes the application of three-dimensional fluorescence recovery after photobleaching (3D-FRAP) microscopy to elucidating the gap junction-dependent exchange of miRNA molecules between cardiac cells. Importantly, this straightforward and non-invasive live-cell imaging approach allows for the visualization and quantification of the gap junctional shuttling of fluorescently labeled small RNAs in real time, with high spatio-temporal resolution. The data obtained by 3D-FRAP confirm a novel pathway of intercellular gene regulation, where small RNAs act as signaling molecules within the intercellular network.

  2. ATP- and gap junction-dependent intercellular calcium signaling in osteoblastic cells

    DEFF Research Database (Denmark)

    Jorgensen, N R; Geist, S T; Civitelli, R

    1997-01-01

    mechanically induced calcium waves in two rat osteosarcoma cell lines that differ in the gap junction proteins they express, in their ability to pass microinjected dye from cell to cell, and in their expression of P2Y2 (P2U) purinergic receptors. ROS 17/2.8 cells, which express the gap junction protein...

  3. Applying 3D-FRAP microscopy to analyse gap junction-dependent shuttling of small antisense RNAs between cardiomyocytes.

    Science.gov (United States)

    Lemcke, Heiko; Peukert, Janine; Voronina, Natalia; Skorska, Anna; Steinhoff, Gustav; David, Robert

    2016-09-01

    Small antisense RNAs like miRNA and siRNA are of crucial importance in cardiac physiology, pathology and, moreover, can be applied as therapeutic agents for the treatment of cardiovascular diseases. Identification of novel strategies for miRNA/siRNA therapy requires a comprehensive understanding of the underlying mechanisms. Emerging data suggest that small RNAs are transferred between cells via gap junctions and provoke gene regulatory effects in the recipient cell. To elucidate the role of miRNA/siRNA as signalling molecules, suitable tools are required that will allow the analysis of these small RNAs at the cellular level. In the present study, we applied 3 dimensional fluorescence recovery after photo bleaching microscopy (3D-FRAP) to visualise and quantify the gap junctional exchange of small RNAs between neonatal cardiomyocytes in real time. Cardiomyocytes were transfected with labelled miRNA and subjected to FRAP microscopy. Interestingly, we observed recovery rates of 21% already after 13min, indicating strong intercellular shuttling of miRNA, which was significantly reduced when connexin43 was knocked down. Flow cytometry analysis confirmed our FRAP results. Furthermore, using an EGFP/siRNA reporter construct we demonstrated that the intercellular transfer does not affect proper functioning of small RNAs, leading to marker gene silencing in the recipient cell. Our results show that 3D-FRAP microscopy is a straightforward, non-invasive live cell imaging technique to evaluate the GJ-dependent shuttling of small RNAs with high spatio-temporal resolution. Moreover, the data obtained by 3D-FRAP confirm a novel pathway of intercellular gene regulation where small RNAs act as signalling molecules within the intercellular network. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Self-induced gap solitons in nonlinear magnetic metamaterials.

    Science.gov (United States)

    Cui, Weina; Zhu, Yongyuan; Li, Hongxia; Liu, Sumei

    2009-09-01

    The self-induced gap solitons in nonlinear magnetic metamaterials is investigated. It is shown that the self-induced gap solitons may exist due to the interaction of the discreteness and nonlinearity. The evolution of these localized structures is studied in the phase plane and analytical and numerical expressions are obtained.

  5. Super-Hard induced gap in InSb nanowires

    Science.gov (United States)

    Chen, Jun; Yu, Peng; Hocevar, Moïra; Plissard, Sébastien; Car, Diana; Bakkers, Erik; Frolov, Sergey

    In recent years, Majorana bound states were observed experimentally in InSb nanowire-superconductor hybrid devices, which manifested themselves as a zero-bias conductance peak (ZBP). However, there was still significant conductance inside the superconducting gap, which would smear sub-gap features. Moreover, fermionic states inside the gap would also break topological protection. Therefore, a hard gap is required in search of more deterministic signatures of Majorana bound states, and building up Majorana qubits. We report the observation of a hard induced gap in an InSb Josephson junction with an optimized superconducting contact recipe. The gap is resolved in magnetic field up to 2 Tesla, and demonstrates a peculiar kinked field dependence. In addition, we observed rich sub-gap features: Andreev levels appeared close to pinch off regime, while multiple Andreev reflection appeared in open regime.

  6. Substrate-induced Band Gap Renormalization in Semiconducting Carbon Nanotubes

    Science.gov (United States)

    Lanzillo, Nicholas A.; Kharche, Neerav; Nayak, Saroj K.

    2014-01-01

    The quasiparticle band gaps of semiconducting carbon nanotubes (CNTs) supported on a weakly-interacting hexagonal boron nitride (h-BN) substrate are computed using density functional theory and the GW Approximation. We find that the direct band gaps of the (7,0), (8,0) and (10,0) carbon nanotubes are renormalized to smaller values in the presence of the dielectric h-BN substrate. The decrease in the band gap is the result of a polarization-induced screening effect, which alters the correlation energy of the frontier CNT orbitals and stabilizes valence band maximum and conduction band minimum. The value of the band gap renormalization is on the order of 0.25 to 0.5 eV in each case. Accounting for polarization-induced band gap changes is crucial in comparing computed values with experiment, since nanotubes are almost always grown on substrates. PMID:24402238

  7. Induced spectral gap and pairing correlations from superconducting proximity effect

    Science.gov (United States)

    Chiu, Ching-Kai; Cole, William S.; Das Sarma, S.

    2016-09-01

    We theoretically consider superconducting proximity effect, using the Bogoliubov-de Gennes (BdG) theory, in heterostructure sandwich-type geometries involving a normal s -wave superconductor and a nonsuperconducting material with the proximity effect being driven by Cooper pairs tunneling from the superconducting slab to the nonsuperconducting slab. Applications of the superconducting proximity effect may rely on an induced spectral gap or induced pairing correlations without any spectral gap. We clarify that in a nonsuperconducting material the induced spectral gap and pairing correlations are independent physical quantities arising from the proximity effect. This is a crucial issue in proposals to create topological superconductivity through the proximity effect. Heterostructures of three-dimensional topological insulator (TI) slabs on conventional s -wave superconductor (SC) substrates provide a platform, with proximity-induced topological superconductivity expected to be observed on the "naked" top surface of a thin TI slab. We theoretically study the induced superconducting gap on this naked surface. In addition, we compare against the induced spectral gap in heterostructures of SC with a normal metal or a semiconductor with strong spin-orbit coupling and a Zeeman splitting potential (another promising platform for topological superconductivity). We find that for any model for the non-SC metal (including metallic TI) the induced spectral gap on the naked surface decays as L-3 as the thickness (L ) of the non-SC slab is increased in contrast to the slower 1 /L decay of the pairing correlations. Our distinction between proximity-induced spectral gap (with its faster spatial decay) and pairing correlation (with its slower spatial decay) has important implications for the currently active search for topological superconductivity and Majorana fermions in various superconducting heterostructures.

  8. Activation of L-type calcium channels is required for gap junction-mediated intercellular calcium signaling in osteoblastic cells

    Science.gov (United States)

    Jorgensen, Niklas Rye; Teilmann, Stefan Cuoni; Henriksen, Zanne; Civitelli, Roberto; Sorensen, Ole Helmer; Steinberg, Thomas H.

    2003-01-01

    The propagation of mechanically induced intercellular calcium waves (ICW) among osteoblastic cells occurs both by activation of P2Y (purinergic) receptors by extracellular nucleotides, resulting in "fast" ICW, and by gap junctional communication in cells that express connexin43 (Cx43), resulting in "slow" ICW. Human osteoblastic cells transmit intercellular calcium signals by both of these mechanisms. In the current studies we have examined the mechanism of slow gap junction-dependent ICW in osteoblastic cells. In ROS rat osteoblastic cells, gap junction-dependent ICW were inhibited by removal of extracellular calcium, plasma membrane depolarization by high extracellular potassium, and the L-type voltage-operated calcium channel inhibitor, nifedipine. In contrast, all these treatments enhanced the spread of P2 receptor-mediated ICW in UMR rat osteoblastic cells. Using UMR cells transfected to express Cx43 (UMR/Cx43) we confirmed that nifedipine sensitivity of ICW required Cx43 expression. In human osteoblastic cells, gap junction-dependent ICW also required activation of L-type calcium channels and influx of extracellular calcium.

  9. Substrate-induced band gap opening in epitaxial graphene

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, S.Y.; Gweon, G.-H.; Fedorov, A.V.; First, P.N.; de Heer,W.A.; Lee, D.-H.; Guinea, F.; Castro Neto, A.H.; Lanzara, A.

    2007-09-08

    Graphene has shown great application potential as the hostmaterial for next-generation electronic devices. However, despite itsintriguing properties, one of the biggest hurdles for graphene to beuseful as an electronic material is the lack of an energy gap in itselectronic spectra. This, for example, prevents the use of graphene inmaking transistors. Although several proposals have been made to open agap in graphene's electronic spectra, they all require complexengineering of the graphene layer. Here, we show that when graphene isepitaxially grown on SiC substrate, a gap of ~;0.26 eV is produced. Thisgap decreases as the sample thickness increases and eventually approacheszero when the number of layers exceeds four. We propose that the originof this gap is the breaking of sublattice symmetry owing to thegraphene-substrate interaction. We believe that our results highlight apromising direction for band gap engineering of graphene.

  10. Berberine potentizes apoptosis induced by X-rays irradiation probably through modulation of gap junctions

    Institute of Scientific and Technical Information of China (English)

    LIU Bing; WANG Qin; YUAN Dong-dong; HONG Xiao-ting; TAO Liang

    2011-01-01

    Background Clinical combination of some traditional Chinese medical herbs, including berberine, with irradiation is demonstrated to improve efficacy of tumor radiotherapy, yet the mechanisms for such effect remain largely unknown. The present study investigated the effect of berberine on apoptosis induced by X-rays irradiation and the relation between this effect and gap junction intercellular communication (GJIC).Methods The role of gap junctions in the modulation of X-rays irradiation-induced apoptosis was explored by manipulation of connexin (Cx) expression, and gap junction function, using oleamide, a GJIC inhibitor, and berberine.Results In transfected HeLa cells, Cx32 expression increased apoptosis induced by X-rays irradiation, while inhibition of gap junction by oleamide reduced the irradiation responses, indicating the dependence of X-rays irradiation-induced apoptosis on GJIC. Berberine, at the concentrations without cytotoxicity, enhanced apoptosis induced by irradiation only in the presence of functional gap junctions.Conclusions These results suggest that berberine potentizes cell apoptosis induced by X-rays irradiation, probably through enhancement of gap junction activity.

  11. Dirac gap-induced graphene quantum dot in an electrostatic potential

    Science.gov (United States)

    Giavaras, G.; Nori, Franco

    2011-04-01

    A spatially modulated Dirac gap in a graphene sheet leads to charge confinement, thus enabling a graphene quantum dot to be formed without the application of external electric and magnetic fields [G. Giavaras and F. Nori, Appl. Phys. Lett. 97, 243106 (2010)]. This can be achieved provided the Dirac gap has a local minimum in which the states become localized. In this work, the physics of such a gap-induced dot is investigated in the continuum limit by solving the Dirac equation. It is shown that gap-induced confined states couple to the states introduced by an electrostatic quantum well potential. Hence the region in which the resulting hybridized states are localized can be tuned with the potential strength, an effect which involves Klein tunneling. The proposed quantum dot may be used to probe quasirelativistic effects in graphene, while the induced confined states may be useful for graphene-based nanostructures.

  12. Locally Resonant Gaps of Phononic Beams Induced by Periodic Arrays of Resonant Shunts

    Institute of Scientific and Technical Information of China (English)

    CHEN Sheng-Bing; WEN Ji-Hong; WANG Gang; HAN Xiao-Yun; WEN Xi-Sen

    2011-01-01

    @@ Periodic arrays of shunted piezoelectric patches are employed to control the propagation of elastic waves in phononic beams.Each piezo-patch is connected to a single resistance-inductance-capacitance shunting circuit.Therefore,the resonances of the shunting circuits will produce locally resonant gaps in the phononic beam.However,the existence of locally resonant gaps induced by resonant shunts has not been clearly proved by experiment so far.In this work,the locally resonant gap in a piezo-shunted phononic beam is investigated theoretically and verified by experiment.The results prove that resonances of shunting circuits can produce locally resonant gaps in phononic beams.%Periodic arrays of shunted piezoelectric patches are employed to control the propagation of elastic waves in phononic beams. Each piezo-patch is connected to a single resistance-inductance-capacitance shunting circuit. Therefore, the resonances of the shunting circuits will produce locally resonant gaps in the phononic beam. However, the existence of locally resonant gaps induced by resonant shunts has not been clearly proved by experiment so far. In this work, the locally resonant gap in a piezo-shunted phononic beam is investigated theoretically and verified by experiment. The results prove that resonances of shunting circuits can produce locally resonant gaps in phononic beams.

  13. Cisplatin-induced premature senescence with concomitant reduction of gap junctions in human fibroblasts

    Institute of Scientific and Technical Information of China (English)

    Wei ZHAO; Zhong Xiang LIN; Zhi Qian ZHANG

    2004-01-01

    To examine the role of gap junctions in cell senescence,the changes of gap junctions in cisplatin-induced premature senescence of primary cultured fibroblasts were studied and compared with the replicative senescent human fibroblasts.Dye transfer assay for gap junction function and immunofluorescent staining for connexin 43 protein distribution were done respectively. Furthermore,cytofluorimetry and DAPI fluorescence staining were performed for cell cycle and apoptosis analysis. p53 gene expression level was detected with indirect immunofluorescence. We found that cisplatin (10 mM) treatment could block cell growth cycle at G1 and induced premature senescence. The premature senescence changes included high frequency of apoptosis,elevation of p53 expression,loss of membranous gap junctions and reduction of dye-transfer capacity. These changes were comparable to the changes of replicative senescence of human fibroblasts. It was also concluded that cisplatin could induce premature senescence concomitant with inhibition of gap junctions in the fibroblasts. Loss of functional gap junctions from the cell membrane may account for the reduced intercellular communication in the premature senescent fibroblasts. The cell system we used may provide a model useful for the study of the gap junction thus promoting agents against premature senescence.

  14. Carrier plasmon induced nonlinear band gap renormalization in two-dimensional semiconductors.

    Science.gov (United States)

    Liang, Yufeng; Yang, Li

    2015-02-13

    In reduced-dimensional semiconductors, doping-induced carrier plasmons can strongly couple with quasiparticle excitations, leading to a significant band gap renormalization. However, the physical origin of this generic effect remains obscure. We develop a new plasmon-pole theory that efficiently and accurately captures this coupling. Using monolayer MoS(2) and MoSe(2) as prototype two-dimensional (2D) semiconductors, we reveal a striking band gap renormalization above 400 meV and an unusual nonlinear evolution of their band gaps with doping. This prediction significantly differs from the linear behavior that is observed in one-dimensional structures. Notably, our predicted band gap renormalization for MoSe(2) is in excellent agreement with recent experimental results. Our developed approach allows for a quantitative understanding of many-body interactions in general doped 2D semiconductors and paves the way for novel band gap engineering techniques.

  15. The gap junction blocker carbenoxolone enhances propofol and sevoflurane-induced loss of consciousness

    Institute of Scientific and Technical Information of China (English)

    Zhigang Liu; Yongfang Liu; Bo Zhao; Li Du; Zhongyuan Xia; Xiangdong Chen; Tao Luo

    2012-01-01

    General anesthetics induce loss of consciousness by inhibiting ascending arousal pathways, and they interfere with gap junction electrical coupling.The present study aimed to determine whether inhibition of gap junction-mediated signaling could influence general anesthetic-induced loss of consciousness.The general anesthetics sevoflurane and propofol were used.Intracerebroventricular administration of carbenoxolone, a gap junction blocker, significantly decreased the time to loss of the righting reflex (P < 0.05), but prolonged the time to recovery of the reflex (P < 0.05).Moreover, intracerebroventricular administration of carbenoxolone increased the sensitivity to sevoflurane, with a leftward shift of the loss of righting reflex dose-response curve, and decreased the 50% effective concentration of sevoflurane.These results suggest that the gap junction blocker carbenoxolone enhances propofol and sevoflurane-mediated general anesthesia.

  16. Altered detrusor gap junction communications induce storage symptoms in bladder inflammation: a mouse cyclophosphamide-induced model of cystitis.

    Science.gov (United States)

    Okinami, Takeshi; Imamura, Masaaki; Nishikawa, Nobuyuki; Negoro, Hiromitsu; Sugino, Yoshio; Yoshimura, Koji; Kanematsu, Akihiro; Hashitani, Hikaru; Ogawa, Osamu

    2014-01-01

    Lower urinary tract symptoms (LUTS) include storage, voiding and post-micturition symptoms, featuring many urological diseases. Storage symptoms are the most frequent among these and associated with overactive bladder and non-bacterial bladder inflammation such as interstitial cystitis/bladder pain syndrome (IC/BPS). Gap junction, a key regulator of hyperactive conditions in the bladder, has been reported to be involved in pathological bladder inflammation. Here we report involvement of gap junction in the etiology of storage symptoms in bladder inflammation. In this study, cyclophosphamide-induced cystitis was adapted as a model of bladder inflammation. Cyclophosphamide-treated mice showed typical storage symptoms including increased urinary frequency and reduced bladder capacity, with concurrent up-regulation of connexin 43 (GJA1), one of the major gap junction proteins in the bladder. In isometric tension study, bladder smooth muscle strips taken from the treated mice showed more pronounced spontaneous contraction than controls, which was attenuated by carbenoxolone, a gap junction inhibitor. In voiding behavior studies, the storage symptoms in the treated mice characterized by frequent voiding were alleviated by 18α-glycyrrhetinic acid, another gap junction inhibitor. These results demonstrate that cyclophosphamide-induced mouse model of cystitis shows clinical storage symptoms related with bladder inflammation and that gap junction in the bladder may be a key molecule of these storage symptoms. Therefore, gap junction in the bladder might be an alternative therapeutic target for storage symptoms in bladder inflammation.

  17. Altered detrusor gap junction communications induce storage symptoms in bladder inflammation: a mouse cyclophosphamide-induced model of cystitis.

    Directory of Open Access Journals (Sweden)

    Takeshi Okinami

    Full Text Available Lower urinary tract symptoms (LUTS include storage, voiding and post-micturition symptoms, featuring many urological diseases. Storage symptoms are the most frequent among these and associated with overactive bladder and non-bacterial bladder inflammation such as interstitial cystitis/bladder pain syndrome (IC/BPS. Gap junction, a key regulator of hyperactive conditions in the bladder, has been reported to be involved in pathological bladder inflammation. Here we report involvement of gap junction in the etiology of storage symptoms in bladder inflammation. In this study, cyclophosphamide-induced cystitis was adapted as a model of bladder inflammation. Cyclophosphamide-treated mice showed typical storage symptoms including increased urinary frequency and reduced bladder capacity, with concurrent up-regulation of connexin 43 (GJA1, one of the major gap junction proteins in the bladder. In isometric tension study, bladder smooth muscle strips taken from the treated mice showed more pronounced spontaneous contraction than controls, which was attenuated by carbenoxolone, a gap junction inhibitor. In voiding behavior studies, the storage symptoms in the treated mice characterized by frequent voiding were alleviated by 18α-glycyrrhetinic acid, another gap junction inhibitor. These results demonstrate that cyclophosphamide-induced mouse model of cystitis shows clinical storage symptoms related with bladder inflammation and that gap junction in the bladder may be a key molecule of these storage symptoms. Therefore, gap junction in the bladder might be an alternative therapeutic target for storage symptoms in bladder inflammation.

  18. Rap1GAP interacts with RET and suppresses GDNF-induced neurite outgrowth

    Institute of Scientific and Technical Information of China (English)

    Li Jiao; Yong Zhang; Chun Hu; Yong-Gang Wang; Aijun Huang; Cheng He

    2011-01-01

    Glial cell line-derived neurotrophic factor(GDNF)was originally recognized for its ability to promote survival of midbrain dopaminergic neurons,but it has since been demonstrated to be crucial for the survival and differentiation of many neuronal subpopulations,including motor neurons,sympathetic neurons,sensory neurons and enteric neurons.To identify possible effectors or regulators of GDNF signaling,we performed a yeast two-hybrid screen using the intracellular domain of RET,the common signaling receptor of the GDNF family,as bait.Using this approach,we identified RaplGAP,a GTPase-activating protein(GAP)for Rap1,as a novel RET-binding protein.Endogenous RaplGAP co-immunoprecipitated with RET in neural tissues,and RET and RaplGAP were co-expressed in dopaminergic neurons of the mesencephalon,in addition,overexpression of RaplGAP attenuated GDNF-induced neurite outgrowth,whereas suppressing the expression of endogenous RaplGAP by RNAi enhanced neurite outgrowth.Furthermore,using co-immunoprecipitation analyses,we found that the interaction between RET and RaplGAP was enhanced following GDNF treatment.Mutagenesis analysis revealed that Tyr981 in the intracellular domain of RET was crucial for the interaction with RapiGAP.Moreover,we found that RaplGAP negatively regulatedGNDFinduced ERK activation and neurite outgrowth.Taken together,our results suggest the involvement of a novel interaction of RET with Rap l GAP in the regulation of GDNF-mediated neurite outgrowth.

  19. Vacancy Induced Energy Band Gap Changes of Semiconducting Zigzag Single Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    DERELI, G.

    2017-08-01

    Full Text Available In this work, we have examined how the multi-vacancy defects induced in the horizontal direction change the energetics and the electronic structure of semiconducting Single-Walled Carbon Nanotubes (SWCNTs. The electronic structure of SWCNTs is computed for each deformed configuration by means of real space, Order(N Tight Binding Molecular Dynamic (O(N TBMD simulations. Energy band gap is obtained in real space through the behavior of electronic density of states (eDOS near the Fermi level. Vacancies can effectively change the energetics and hence the electronic structure of SWCNTs. In this study, we choose three different kinds of semiconducting zigzag SWCNTs and determine the band gap modifications. We have selected (12,0, (13,0 and (14,0 zigzag SWCNTs according to n (mod 3 = 0, n (mod 3 = 1 and n (mod 3 = 2 classification. (12,0 SWCNT is metallic in its pristine state. The application of vacancies opens the electronic band gap and it goes up to 0.13 eV for a di-vacancy defected tube. On the other hand (13,0 and (14,0 SWCNTs are semiconductors with energy band gap values of 0.44 eV and 0.55 eV in their pristine state, respectively. Their energy band gap values decrease to 0.07 eV and 0.09 eV when mono-vacancy defects are induced in their horizontal directions. Then the di-vacancy defects open the band gap again. So in both cases, the semiconducting-metallic ¬- semiconducting transitions occur. It is also shown that the band gap modification exhibits irreversible characteristics, which means that band gap values of the nanotubes do not reach their pristine values with increasing number of vacancies.

  20. Bridging the intention-behavior gap : Inducing implementation intentions through persuasive appeals

    NARCIS (Netherlands)

    Fennis, Bob M.; Adriaanse, Marieke A.; Pol, Bert; Stroebe, W

    2011-01-01

    The potential of using implementation intentions action plans that link a critical situational cue to a specific goal-directed behavior to bridge the intention behavior gap in consumer behavior has been limited by the practice of using explicit instructions to induce the construct. In two studies, w

  1. Bridging the intention-behavior gap : Inducing implementation intentions through persuasive appeals

    NARCIS (Netherlands)

    Fennis, Bob M.; Adriaanse, Marieke A.; Pol, Bert; Stroebe, W

    The potential of using implementation intentions action plans that link a critical situational cue to a specific goal-directed behavior to bridge the intention behavior gap in consumer behavior has been limited by the practice of using explicit instructions to induce the construct. In two studies,

  2. Gap state charge induced spin-dependent negative differential resistance in tunnel junctions

    Science.gov (United States)

    Jiang, Jun; Zhang, X.-G.; Han, X. F.

    2016-04-01

    We propose and demonstrate through first-principles calculation a new spin-dependent negative differential resistance (NDR) mechanism in magnetic tunnel junctions (MTJ) with cubic cation disordered crystals (CCDC) AlO x or Mg1-x Al x O as barrier materials. The CCDC is a class of insulators whose band gap can be changed by cation doping. The gap becomes arched in an ultrathin layer due to the space charge formed from metal-induced gap states. With an appropriate combination of an arched gap and a bias voltage, NDR can be produced in either spin channel. This mechanism is applicable to 2D and 3D ultrathin junctions with a sufficiently small band gap that forms a large space charge. It provides a new way of controlling the spin-dependent transport in spintronic devices by an electric field. A generalized Simmons formula for tunneling current through junction with an arched gap is derived to show the general conditions under which ultrathin junctions may exhibit NDR.

  3. Antofine-induced connexin43 gap junction disassembly in rat astrocytes involves protein kinase Cβ.

    Science.gov (United States)

    Huang, Yu-Fang; Liao, Chih-Kai; Lin, Jau-Chen; Jow, Guey-Mei; Wang, Hwai-Shi; Wu, Jiahn-Chun

    2013-03-01

    Antofine, a phenanthroindolizidine alkaloid derived from Cryptocaryachinensis and Ficusseptica in the Asclepiadaceae milkweed family, is cytotoxic for various cancer cell lines. In this study, we demonstrated that treatment of rat primary astrocytes with antofine induced dose-dependent inhibition of gap junction intercellular communication (GJIC), as assessed by scrape-loading 6-carboxyfluorescein dye transfer. Levels of Cx43 protein were also decreased in a dose- and time-dependent manner following antofine treatment. Double-labeling immunofluorescence microscopy showed that antofine (10ng/ml) induced endocytosis of surface gap junctions into the cytoplasm, where Cx43 was co-localized with the early endosome marker EEA1. Inhibition of lysosomes or proteasomes by co-treatment with antofine and their respective specific inhibitors, NH4Cl or MG132, partially inhibited the antofine-induced decrease in Cx43 protein levels, but did not inhibit the antofine-induced inhibition of GJIC. After 30min of treatment, antofine induced a rapid increase in the intracellular Ca(2+) concentration and activation of protein kinase C (PKC)α/βII, which was maintained for at least 6h. Co-treatment of astrocytes with antofine and the intracellular Ca(2+) chelator BAPTA-AM prevented downregulation of Cx43 and inhibition of GJIC. Moreover, co-treatment with antofine and a specific PKCβ inhibitor prevented endocytosis of gap junctions, downregulation of Cx43, and inhibition of GJIC. Taken together, these findings indicate that antofine induces Cx43 gap junction disassembly by the PKCβ signaling pathway. Inhibition of GJIC by antofine may undermine the neuroprotective effect of astrocytes in CNS.

  4. Microscopic theory of substrate-induced gap effect on real AFM susceptibility in graphene

    Indian Academy of Sciences (India)

    SIVABRATA SAHU; S K PANDA; G C ROUT

    2017-07-01

    We address here a tight-binding model study of frequency-dependent real part of antiferromagnetic susceptibility for the graphene systems. TheHamiltonian consists of electron hopping upto third nearest-neighbours,substrate and impurity effects in the presence of electron–electron interactions at A and B sublattices. To calculate susceptibility, we evaluate the two-particle electron Green’s function by using Zubarev’s Green’s functiontechnique. The frequency-dependent real part of antiferromagnetic susceptibility of the system is computed numerically by taking 1000 × 1000 grid points of the electron momentum. The susceptibility displays a sharp peak at the neutron momentum transfer energy at low energies and another higher energy peak appearing at substrate-induced gap. The evolution of these two peaks is investigated by varying neutron wave vector, Coulomb correlation energy, substrate-induced gap, electron hopping integrals and A- and B-site electron doping concentrations.

  5. GLAST deficiency in mice exacerbates gap detection deficits in a model of salicylate-induced tinnitus

    Directory of Open Access Journals (Sweden)

    Hong Yu

    2016-08-01

    Full Text Available Gap detection or gap pre-pulse inhibition of the acoustic startle (GPIAS has been successfully used in rat and guinea pig models of tinnitus, yet this system has proven to have low efficacy in CBA mice, with low basal GPIAS and subtle tinnitus like effects. Here, we tested five mouse strains (CBA, BalbC, CD-1, C57BL/6 and sv129 for pre-pulse inhibition and gap detection with varying interstimulus intervals (ISI and found the that mice from a CBA genetic background had the poorest capacities of suppressing the startle response in presence of a pre-pulse or a gap. CD-1 mice displayed variable responses throughout all ISI. Interestingly, C57BL/6, sv129 and BalbC showed efficient suppression with either pre-pulses or gaps with shorter ISI. The glutamate aspartate transporter (GLAST is expressed in support cells from the cochlea and buffers the excess of glutamate. We hypothesized that loss of GLAST function could sensitize the ear to tinnitus-inducing agents, such as salicylate. Using shorter ISI to obtain a greater dynamic range to assess tinnitus-like effects, we found that disruption of gap detection by salicylate was exacerbated across various intensities of a 32 kHz narrow band noise gap carrier in GLAST KO mice when compared to their wild-type littermates. Auditory brainstem responses (ABR and distortion products of otoacoustic emission (DPOAE were performed to evaluate the effects on hearing functions. Salicylate caused greater auditory threshold shifts (near 15 dB in GLAST KO mice than in wild-type mice across all tested frequencies, despite similarly reduced DPOAE. Despite these changes, inhibition using broad-band gap carriers and 32 kHz pre-pulses were not affected. Our study suggests that GLAST deficiency could become a useful experimental model to decipher the mechanisms underlying drug-induced tinnitus. Future studies addressing the neurological correlates of tinnitus in this model could provide additional insights into the mechanisms

  6. Pharmacological blockade of gap junctions induces repetitive surging of extracellular potassium within the locust CNS.

    Science.gov (United States)

    Spong, Kristin E; Robertson, R Meldrum

    2013-10-01

    The maintenance of cellular ion homeostasis is crucial for optimal neural function and thus it is of great importance to understand its regulation. Glial cells are extensively coupled by gap junctions forming a network that is suggested to serve as a spatial buffer for potassium (K(+)) ions. We have investigated the role of glial spatial buffering in the regulation of extracellular K(+) concentration ([K(+)]o) within the locust metathoracic ganglion by pharmacologically inhibiting gap junctions. Using K(+)-sensitive microelectrodes, we measured [K(+)]o near the ventilatory neuropile while simultaneously recording the ventilatory rhythm as a model of neural circuit function. We found that blockade of gap junctions with either carbenoxolone (CBX), 18β-glycyrrhetinic acid (18β-GA) or meclofenamic acid (MFA) reliably induced repetitive [K(+)]o surges and caused a progressive impairment in the ability to maintain baseline [K(+)]o levels throughout the treatment period. We also show that a low dose of CBX that did not induce surging activity increased the vulnerability of locust neural tissue to spreading depression (SD) induced by Na(+)/K(+)-ATPase inhibition with ouabain. CBX pre-treatment increased the number of SD events induced by ouabain and hindered the recovery of [K(+)]o back to baseline levels between events. Our results suggest that glial spatial buffering through gap junctions plays an essential role in the regulation of [K(+)]o under normal conditions and also contributes to a component of [K(+)]o clearance following physiologically elevated levels of [K(+)]o.

  7. Entanglement between qubits induced by a common environment with a gap

    CERN Document Server

    Oh, S; Oh, Sangchul; Kim, Jaewan

    2006-01-01

    We study a system of two qubits interacting with a common environment, described by a two-spin boson model. We demonstrate two competing roles of the environment: inducing entanglement between the two qubits and making them decoherent. For the environment of a single harmonic oscillator, if its frequency is commensurate with the induced two-qubit coupling strength, the two qubits could be maximally entangled and the environment could be separable. In the case of the environment of a bosonic bath, the gap of its spectral density function is essential to generate entanglement between two qubits at equilibrium and for it to be used as a quantum data bus.

  8. Vacancy-induced in-gap states in sodium tungsten bronzes: Density functional investigations

    Science.gov (United States)

    Paul, S.; Kumari, S.; Raj, S.

    2016-05-01

    We have performed extensive ab-initio self-consistent electronic-structure calculations on WO3 and NaWO3 with single- and double-oxygen-vacancy defects within the framework of density functional theory. Our calculated density of states reveals that the in-gap states in WO3 and NaWO3 are the consequence of oxygen vacancies in the system. The evolution of the induced states occurs from the unpaired electrons donated by the oxygen vacancy. We found that the energy positions of the in-gap states are sensitive to the oxygen vacancy concentrations. The in-gap states in NaWO3 are formed close to the valence band, which are pushed towards the conduction band with the increase in oxygen vacancies, whereas the states are formed mostly in the mid-gap region in the WO3 system. Our finding can now well explain the discrepancy in experimental band dispersion measurements from ARPES with that of WO3 and NaWO3 band calculations.

  9. Dipole-induced band-gap reduction in an inorganic cage.

    Science.gov (United States)

    Lv, Yaokang; Cheng, Jun; Steiner, Alexander; Gan, Lihua; Wright, Dominic S

    2014-02-10

    Metal-doped polyoxotitanium cages are a developing class of inorganic compounds which can be regarded as nano- and sub-nano sized molecular relatives of metal-doped titania nanoparticles. These species can serve as models for the ways in which dopant metal ions can be incorporated into metal-doped titania (TiO2 ), a technologically important class of photocatalytic materials with broad applications in devices and pollution control. In this study a series of cobalt(II)-containing cages in the size range ca. 0.7-1.3 nm have been synthesized and structurally characterized, allowing a coherent study of the factors affecting the band gaps in well-defined metal-doped model systems. Band structure calculations are consistent with experimental UV/Vis measurements of the Tix Oy absorption edges in these species and reveal that molecular dipole moment can have a profound effect on the band gap. The observation of a dipole-induced band-gap decrease mechanism provides a potentially general design strategy for the formation of low band-gap inorganic cages.

  10. Continuum absorption in the vicinity of the toroidicity-induced Alfvén gap

    Science.gov (United States)

    Li, M.; Breizman, B. N.; Zheng, L. J.; Chen, Eugene Y.

    2015-12-01

    Excitation of Alfvén modes is commonly viewed as a concern for energetic particle confinement in burning plasmas. The 3.5 MeV alpha particles produced by fusion may be affected as well as other fast ions in both present and future devices. Continuum damping of such modes is one of the key factors that determine their excitation thresholds and saturation levels. This work examines the resonant dissipative response of the Alfvén continuum to an oscillating driving current when the driving frequency is slightly outside the edges of the toroidicity-induced spectral gap. The problem is largely motivated by the need to describe the continuum absorption in the frequency sweeping events. A key element of this problem is the negative interference of the two closely spaced continuum crossing points. We explain why the lower and upper edges of the gap can have very different continuum absorption features. The difference is associated with an eigenmode whose frequency can be arbitrarily close to the upper edge of the gap whereas the lower edge of the gap is always a finite distance away from the closest eigenmode.

  11. Mode Modification of Plasmonic Gap Resonances induced by Strong Coupling with Molecular Excitons

    CERN Document Server

    Chen, Xingxing; Qin, Jian; Zhao, Ding; Ding, Boyang; Blaikie, Richard J; Qiu, Min

    2016-01-01

    Plasmonic cavities can be used to control the atom-photon coupling process at the nanoscale, since they provide ultrahigh density of optical states in an exceptionally small mode volume. Here we demonstrate strong coupling between molecular excitons and plasmonic resonances (so-called plexcitonic coupling) in a film-coupled nanocube cavity, which can induce profound and significant spectral and spatial modifications to the plasmonic gap modes. Within the spectral span of a single gap mode in the nanotube-film cavity with a 3-nm wide gap, the introduction of narrow-band J-aggregate dye molecules not only enables an anti-crossing behavior in the spectral response, but also splits the single spatial mode into two distinct modes that are easily identified by their far-field scattering profiles. Simulation results confirm the experimental findings and the sensitivity of the plexcitonic coupling is explored using digital control of the gap spacing. Our work opens up a new perspective to study the strong coupling pr...

  12. The Vertical Structure of Planet-induced Gaps in Proto-Planetary Discs

    CERN Document Server

    Edgar, R G

    2007-01-01

    Giant planets embedded in circumstellar discs are expected to open gaps in these discs. We examine the vertical structure of the gap edges. We find that the planet excites spiral arms with significant (Mach number of a half) vertical motion of the gas, and discuss the implications of these motions. In particular, the spiral arms will induce strong vertical stirring of the dust, making the edge appeared `puffed up' relative to the bulk of the disc. Infra-red observations (sensitive to dust) would be dominated by the light from the thick inner edge of the disc. Sub-millimetre observations (sensitive to gas velocities) would appear to be hot in `turbulent' motions (actually the ordered motion caused by the passage of the spiral arms), but cold in chemistry. Resolved sub-millimetre maps of circumstellar discs might even be able to detect the spiral arms directly.

  13. Polarization-induced pn diodes in wide-band-gap nanowires with ultraviolet electroluminescence.

    Science.gov (United States)

    Carnevale, Santino D; Kent, Thomas F; Phillips, Patrick J; Mills, Michael J; Rajan, Siddharth; Myers, Roberto C

    2012-02-08

    Almost all electronic devices utilize a pn junction formed by random doping of donor and acceptor impurity atoms. We developed a fundamentally new type of pn junction not formed by impurity-doping, but rather by grading the composition of a semiconductor nanowire resulting in alternating p and n conducting regions due to polarization charge. By linearly grading AlGaN nanowires from 0% to 100% and back to 0% Al, we show the formation of a polarization-induced pn junction even in the absence of any impurity doping. Since electrons and holes are injected from AlN barriers into quantum disk active regions, graded nanowires allow deep ultraviolet LEDs across the AlGaN band-gap range with electroluminescence observed from 3.4 to 5 eV. Polarization-induced p-type conductivity in nanowires is shown to be possible even without supplemental acceptor doping, demonstrating the advantage of polarization engineering in nanowires compared with planar films and providing a strategy for improving conductivity in wide-band-gap semiconductors. As polarization charge is uniform within each unit cell, polarization-induced conductivity without impurity doping provides a solution to the problem of conductivity uniformity in nanowires and nanoelectronics and opens a new field of polarization engineering in nanostructures that may be applied to other polar semiconductors.

  14. Surface Plasmon-Induced Band Gap in the Photocurrent Response of Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Ribal Georges Sabat

    2010-01-01

    Full Text Available A 260 nm layer of organic bulk heterojunction blend of the polymer poly(3-hexylthiophene (P3HT and the fullerene [6,6]-phenyl C61-butyric (PCBM was spin-coated in between aluminum and gold electrodes, respectively, on top of a laser inscribed azo polymer surface-relief diffraction grating. Angle-dependent surface plasmons (SPs with a large band gap were observed in the normalized photocurrent by the P3HT-PCBM layer as a function of wavelength. The SP-induced photocurrents were also investigated as a function of the grating depth and spacing.

  15. Analogy of transistor function with modulating photonic band gap in electromagnetically induced grating.

    Science.gov (United States)

    Wang, Zhiguo; Ullah, Zakir; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

    2015-09-09

    Optical transistor is a device used to amplify and switch optical signals. Many researchers focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data. Electronic transistor is the fundamental building block of modern electronic devices. To replace electronic components with optical ones, an equivalent optical transistor is required. Here we compare the behavior of an optical transistor with the reflection from a photonic band gap structure in an electromagnetically induced transparency medium. A control signal is used to modulate the photonic band gap structure. Power variation of the control signal is used to provide an analogy between the reflection behavior caused by modulating the photonic band gap structure and the shifting of Q-point (Operation point) as well as amplification function of optical transistor. By means of the control signal, the switching function of optical transistor has also been realized. Such experimental schemes could have potential applications in making optical diode and optical transistor used in quantum information processing.

  16. Coupled resonator induced transparency in surface plasmon polariton gap waveguide with two side-coupled cavities

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhengren, E-mail: zhrenzhang@126.com [School of Science, Chongqing Jiaotong University, Chongqing 400074 (China); Zhang, Liwei [School of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000 (China); Yin, Pengfei; Han, Xiangyu [School of Science, Chongqing Jiaotong University, Chongqing 400074 (China)

    2014-08-01

    We investigate theoretically the generation process of coupled resonator-induced transparency (CRIT) in surface plasmon polariton gap waveguide system containing two side-coupled cavities, which locate at a symmetric position. The CRIT is original from the destructive interference of the two detuned cavities. In contrast with the existing electromagnetically induced transparency (EIT) schemes, the occurrence of the CRIT is caused by the two radiative cavities in waveguide, instead of interference between a dark cavity and radiative cavity. This behavior mimics the quantum interference between two direct excitation pathways in a three-level V-type atom. The transmission lineshape can be tuned between an EIT-like resonant peak and a Lorentzian-like resonant dip by tailoring the detuning of the two cavities. Moreover, we also find that the transparency peak moves to high frequency with a line shift and its Q factor decreases with the increase of coupling distance between the cavities and waveguide.

  17. Search for a proximity effect induced gap in gold/high T sub c junctions

    Energy Technology Data Exchange (ETDEWEB)

    Dessau, D.S.; Wells, B.O.; Shen, Z.; Spicer, W.E. (Stanford Electronics Laboratories, Stanford University, Stanford California 94305 (US)); Arko, A.J.; List, R.S. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA)); Olson, C.G. (Ames Laboratory, Iowa State University, Ames, Iowa 50011 (USA)); Eom, C.B.; Mitzi, D.B.; Kapitulnik, A.; Geballe, T.H. (Department of Applied Physics, Stanford University, Stanford, California 94305 (USA))

    1991-03-25

    We have used high-resolution photoemission spectroscopy to search for a proximity effect induced superconducting gap in gold overlayers on {ital c}-axis single crystals of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} and {ital a}-axis thin films of YBa{sub 2}Cu{sub 3}O{sub 7}. These two junction types give us a representative sampling of very well characterized near-ideal interfaces (gold/{ital c}-axis Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}) and junctions in which the geometry more strongly favors the existence of the proximity effect but the interfacial quality may not be as ideal (gold/{ital a}-axis YBa{sub 2}Cu{sub 3}O{sub 7}). In neither of these junction types did we observe any evidence for a proximity effect induced gap, and we place an upper limit of approximately 5 meV on its existence in the junctions that we have studied.

  18. Terahertz radiation-induced sub-cycle field electron emission across a split-gap dipole antenna

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jingdi; Averitt, Richard D., E-mail: xinz@bu.edu, E-mail: raveritt@ucsd.edu [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Zhao, Xiaoguang; Fan, Kebin; Wang, Xiaoning; Zhang, Xin, E-mail: xinz@bu.edu, E-mail: raveritt@ucsd.edu [Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215 (United States); Zhang, Gu-Feng [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Geng, Kun [Department of Physics, Boston University, Boston, Massachusetts 02215 (United States)

    2015-12-07

    We use intense terahertz pulses to excite the resonant mode (0.6 THz) of a micro-fabricated dipole antenna with a vacuum gap. The dipole antenna structure enhances the peak amplitude of the in-gap THz electric field by a factor of ∼170. Above an in-gap E-field threshold amplitude of ∼10 MV/cm{sup −1}, THz-induced field electron emission is observed as indicated by the field-induced electric current across the dipole antenna gap. Field emission occurs within a fraction of the driving THz period. Our analysis of the current (I) and incident electric field (E) is in agreement with a Millikan-Lauritsen analysis where log (I) exhibits a linear dependence on 1/E. Numerical estimates indicate that the electrons are accelerated to a value of approximately one tenth of the speed of light.

  19. Terahertz radiation-induced sub-cycle field electron emission across a split-gap dipole antenna

    CERN Document Server

    Zhang, Jingdi; Fan, Kebin; Wang, Xiaoning; Zhang, Gu-Feng; Geng, Kun; Zhang, Xin; Averitt, Richard D

    2015-01-01

    We use intense terahertz pulses to excite the resonant mode (0.6 THz) of a micro-fabricated dipole antenna with a vacuum gap. The dipole antenna structure enhances the peak amplitude of the in-gap THz electric field by a factor of ~170. Above an in-gap E-field threshold amplitude of ~10 MVcm-1, THz-induced field electron emission is observed (TIFEE) as indicated by the field-induced electric current across the dipole antenna gap. Field emission occurs within a fraction of the driving THz period. Our analysis of the current (I) and incident electric field (E) is in agreement with a Millikan-Lauritsen analysis where log (I) exhibits a linear dependence on 1/E. Numerical estimates indicate that the electrons are accelerated to a value of approximately one tenth of the speed of light.

  20. Variation in yield gap induced by nitrogen, phosphorus and potassium fertilizer in North China Plain.

    Directory of Open Access Journals (Sweden)

    Xiaoqin Dai

    Full Text Available A field experiment was conducted under a wheat-maize rotation system from 1990 to 2006 in North China Plain (NCP to determine the effects of N, P and K on yield and yield gap. There were five treatments: NPK, PK, NK, NP and a control. Average wheat and maize yields were the highest in the NPK treatment, followed by those in the NP plots among all treatments. For wheat and maize yield, a significant increasing trend over time was found in the NPK-treated plots and a decreasing trend in the NK-treated plots. In the absence of N or P, wheat and maize yields were significantly lower than those in the NPK treatment. For both crops, the increasing rate of the yield gap was the highest in the P omission plots, i.e., 189.1 kg ha(-1 yr(-1 for wheat and 560.6 kg ha(-1 yr(-1 for maize. The cumulative omission of P fertilizer induced a deficit in the soil available N and extractable P concentrations for maize. The P fertilizer was more pivotal in long-term wheat and maize growth and soil fertility conservation in NCP, although the N fertilizer input was important for both crops growth. The crop response to K fertilizers was much lower than that to N or P fertilizers, but for maize, the cumulative omission of K fertilizer decreased the yield by 26% and increased the yield gap at a rate of 322.7 kg ha(-1 yr(-1. The soil indigenous K supply was not sufficiently high to meet maize K requirement over a long period. The proper application of K fertilizers is necessary for maize production in the region. Thus, the appropriate application of N and P fertilizers for the growth of both crops, while regularly combining K fertilizers for maize growth, is absolutely necessary for sustainable crop production in the NCP.

  1. Variation in yield gap induced by nitrogen, phosphorus and potassium fertilizer in North China Plain.

    Science.gov (United States)

    Dai, Xiaoqin; Ouyang, Zhu; Li, Yunsheng; Wang, Huimin

    2013-01-01

    A field experiment was conducted under a wheat-maize rotation system from 1990 to 2006 in North China Plain (NCP) to determine the effects of N, P and K on yield and yield gap. There were five treatments: NPK, PK, NK, NP and a control. Average wheat and maize yields were the highest in the NPK treatment, followed by those in the NP plots among all treatments. For wheat and maize yield, a significant increasing trend over time was found in the NPK-treated plots and a decreasing trend in the NK-treated plots. In the absence of N or P, wheat and maize yields were significantly lower than those in the NPK treatment. For both crops, the increasing rate of the yield gap was the highest in the P omission plots, i.e., 189.1 kg ha(-1) yr(-1) for wheat and 560.6 kg ha(-1) yr(-1) for maize. The cumulative omission of P fertilizer induced a deficit in the soil available N and extractable P concentrations for maize. The P fertilizer was more pivotal in long-term wheat and maize growth and soil fertility conservation in NCP, although the N fertilizer input was important for both crops growth. The crop response to K fertilizers was much lower than that to N or P fertilizers, but for maize, the cumulative omission of K fertilizer decreased the yield by 26% and increased the yield gap at a rate of 322.7 kg ha(-1) yr(-1). The soil indigenous K supply was not sufficiently high to meet maize K requirement over a long period. The proper application of K fertilizers is necessary for maize production in the region. Thus, the appropriate application of N and P fertilizers for the growth of both crops, while regularly combining K fertilizers for maize growth, is absolutely necessary for sustainable crop production in the NCP.

  2. Filling of Cloud-Induced Gaps for Land Use and Land Cover Classifications Around Refugee Camps

    Science.gov (United States)

    Braun, Andreas; Hagensieker, Ron; Hochschild, Volker

    2016-08-01

    Clouds cover is one of the main constraints in the field of optical remote sensing. Especially the use of multispectral imagery is affected by either fully obscured data or parts of the image which remain unusable. This study compares four algorithms for the filling of cloud induced gaps in classified land cover products based on Markov Random Fields (MRF), Random Forest (RF), Closest Spectral Fit (CSF) operators. They are tested on a classified image of Sentinel-2 where artificial clouds are filled by information derived from a scene of Sentinel-1. The approaches rely on different mathematical principles and therefore produced results varying in both pattern and quality. Overall accuracies for the filled areas range from 57 to 64 %. Best results are achieved by CSF, however some classes (e.g. sands and grassland) remain critical through all approaches.

  3. Nanosecond laser-induced periodic surface structures on wide band-gap semiconductors

    Science.gov (United States)

    Sanz, Mikel; Rebollar, Esther; Ganeev, Rashid A.; Castillejo, Marta

    2013-08-01

    In this work we report on fabrication of laser-induced periodic surface structures (LIPSS) on different semiconductors with bandgap energies in the range of 1.3-3.3 eV and melting temperatures from 1100 to 2700 °C. In particular, InP, GaAs, GaP and SiC were irradiated in air with nanosecond pulses using a linearly polarized laser beam at 266 nm (6 ns pulse width). The nanostructures, inspected by atomic force microscopy, are produced upon multiple pulse irradiation at fluences near the ablation threshold. LIPSS are perpendicular to the laser polarization direction and their period is of the order of the irradiation wavelength. It was observed that the accumulative effect of both fluence and number of pulses needed for LIPSS formation increased with the material bandgap energy. These results, together with estimations of surface temperature increase, are discussed with reference to the semiconductor electrical, optical and thermal properties.

  4. Nanosecond laser-induced periodic surface structures on wide band-gap semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, Mikel, E-mail: mikel.sanz@iqfr.csic.es [Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Rebollar, Esther [Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Ganeev, Rashid A. [Voronezh State University, Voronezh 394006 (Russian Federation); Castillejo, Marta [Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain)

    2013-08-01

    In this work we report on fabrication of laser-induced periodic surface structures (LIPSS) on different semiconductors with bandgap energies in the range of 1.3–3.3 eV and melting temperatures from 1100 to 2700 °C. In particular, InP, GaAs, GaP and SiC were irradiated in air with nanosecond pulses using a linearly polarized laser beam at 266 nm (6 ns pulse width). The nanostructures, inspected by atomic force microscopy, are produced upon multiple pulse irradiation at fluences near the ablation threshold. LIPSS are perpendicular to the laser polarization direction and their period is of the order of the irradiation wavelength. It was observed that the accumulative effect of both fluence and number of pulses needed for LIPSS formation increased with the material bandgap energy. These results, together with estimations of surface temperature increase, are discussed with reference to the semiconductor electrical, optical and thermal properties.

  5. ATP Is Required and Advances Cytokine-Induced Gap Junction Formation in Microglia In Vitro

    Directory of Open Access Journals (Sweden)

    Pablo J. Sáez

    2013-01-01

    Full Text Available Microglia are the immune cells in the central nervous system. After injury microglia release bioactive molecules, including cytokines and ATP, which modify the functional state of hemichannels (HCs and gap junction channels (GJCs, affecting the intercellular communication via extracellular and intracellular compartments, respectively. Here, we studied the role of extracellular ATP and several cytokines as modulators of the functional state of microglial HCs and GJCs using dye uptake and dye coupling techniques, respectively. In microglia and the microglia cell line EOC20, ATP advanced the TNF-α/IFN-γ-induced dye coupling, probably through the induction of IL-1β release. Moreover, TNF-α/IFN-γ, but not TNF-α plus ATP, increased dye uptake in EOC20 cells. Blockade of Cx43 and Panx1 HCs prevented dye coupling induced by TNF-α/IFN-γ, but not TNF-α plus ATP. In addition, IL-6 prevented the induction of dye coupling and HC activity induced by TNF-α/IFN-γ in EOC20 cells. Our data support the notion that extracellular ATP affects the cellular communication between microglia through autocrine and paracrine mechanisms, which might affect the timing of immune response under neuroinflammatory conditions.

  6. The number and size of subhalo-induced gaps in stellar streams

    Science.gov (United States)

    Erkal, Denis; Belokurov, Vasily; Bovy, Jo; Sanders, Jason L.

    2016-11-01

    Ample observational capabilities exist today to detect the small density perturbations that low-mass dark matter subhaloes impart on stellar streams from disrupting Galactic satellites. In anticipation of these observations, we investigate the expected number and size of gaps by combining an analytic prescription for gap evolution on circular orbits with the flux of subhaloes near the stream. We explore the distribution of gap sizes and depths for a typical cold stream around the Milky Way and find that for a given stream age and gap depth, each subhalo mass produces a characteristic gap size. For a stream with an age of a few Gyr, orbiting at a distance of 10-20 kpc from the Galactic centre, even modest subhaloes with a mass of 106-107 M⊙ produce gaps with sizes that are of the order of several degrees. We consider the number and distribution of gap sizes created by subhaloes with masses 105-109 M⊙, accounting for the expected depletion of subhaloes by the Milky Way disc, and present predictions for six cold streams around the Milky Way. For Pal 5, we forecast 0.7 gaps with a density depletion of at least 25 per cent and a typical gap size of 8°. Thus, there appears to be no tension between the recent non-detection of density depletions in the Pal 5 tidal tails and ΛCDM expectations. These predictions can be used to guide the scale of future gap searches.

  7. Role of gap junctions in acetylcholine-induced vasodilation of proximal and distal arteries of the rat mesentery.

    Science.gov (United States)

    Hill, C E; Hickey, H; Sandow, S L

    2000-07-01

    We have previously shown that myoendothelial gap junctions are more prevalent in distal than in proximal arteries of the rat mesentery. In the present study we have investigated the role of gap junctions in the mechanism of action of endothelium-derived hyperpolarizing factor (EDHF) in these same vessels following relaxation with acetylcholine. Arteries were pre-constricted with phenylephrine and concentration response curves to acetylcholine were constructed in the presence of N(G)-nitro-L-arginine methyl ester (L-NAME; 10(-5) M) and indomethacin (10(-5) M) to prevent effects due to the release of nitric oxide and prostacyclins. Nitric oxide was found to have only a small role in the relaxation of the proximal vessels and was not involved in the relaxations of the distal vessels. 18 alpha-Glycyrrhetinic acid (10(-5) M), a putative gap junction uncoupler, significantly reduced acetylcholine-induced relaxations by 50% in both proximal and distal vessels. Potassium channel antagonists, tetraethylammonium chloride (TEA; 10(-3) M) and barium chloride (10(-4) M), together abolished the dilatory response in the proximal mesenteric arteries, but did not completely block responses in the distal arteries. The data suggest that gap junctions contribute significantly to the acetylcholine-induced relaxation in both proximal and distal arteries of the rat mesentery. We hypothesize that the absence of a correlation between the role of gap junctions and the incidence of myoendothelial gap junctions in these same vessels is due to significant effects of the inhibitors on gap junctions located in the smooth muscle layers of the larger vessels.

  8. Saffman-Taylor-like instability in a narrow gap induced by dielectric barrier discharge

    Science.gov (United States)

    Hou, Shang-Yan; Chu, Hong-Yu

    2015-07-01

    This work is inspired by the expansion of the plasma bubble in a narrow gap reported by Chu and Lee [Phys. Rev. Lett. 107, 225001 (2011)], 10.1103/PhysRevLett.107.225001. We report the unstable phenomena of the plasma-liquid interface with different curvature in a Hele-Shaw cell. Dielectric barrier discharge is produced in the cell at atmospheric pressure which is partially filled with silicone oil. We show that the Saffman-Taylor-like instability is observed on the bubble-type, channel-type, and drop-type interfaces. The Schlieren observation of the plasma-drop interaction reveals that there is a vapor layer around the drop and the particle image velocimetry shows the liquid flow inside the drop. We propose that the thermal Marangoni effect induced by the plasma heating is responsible for the unstable phenomena of the plasma-liquid interaction. The fluctuation of the interface is shown consistently with the Saffman-Taylor instability modified by the temperature-dependent velocity and surface tension.

  9. Patient-practitioner perception gap in treatment-induced nausea and vomiting.

    Science.gov (United States)

    Vidall, Cheryl; Sharma, Sangeeta; Amlani, Bharat

    2016-09-08

    This UK cohort analysis of a European survey evaluated the differences between health professionals and cancer patients regarding the perceived incidence, impact and drug management of chemotherapy/radiotherapy-induced nausea/vomiting (CINV/RINV). The UK healthcare system is unique in that it has dedicated oncology clinical nurse specialists. The analysis found that more patients experienced nausea following their most recent treatment cycle than vomiting. Health professionals overestimated the incidence of CINV/RINV but underestimated its impact on patients' daily lives, particularly in cases of mild and moderate nausea/vomiting. The level of antiemetic cover initiated and degree of symptom control was often suboptimal. Patients under-reported symptoms, primarily because they considered nausea/vomiting an inevitable side effect of treatment. Altogether, 42% of patients reported full adherence to their antiemetic regimen. Leading factors for non-adherence included not having a 'preventive mindset', low symptom severity and a reluctance to increase pill burden. In conclusion, there is a perceptual gap between health professionals and patients around experiences of CINV/RINV. Advances in management depend on enhancing health professional-patient communication, and reporting and understanding nausea as a distinct issue.

  10. Chemisorption-induced gap states at organic-metal interfaces: benzenethiol and benzeneselenol on metal surfaces.

    Science.gov (United States)

    Aoki, Masaru; Kamada, Toyohiro; Sasaki, Keita; Masuda, Shigeru; Morikawa, Yoshitada

    2012-03-28

    Valence electronic states of benzenethiol (C(6)H(5)SH) and benzeneselenol (C(6)H(5)SeH) in the gas, condensed, and chemisorbed phases were examined by ultraviolet photoemission spectroscopy, metastable atom electron spectroscopy, and first-principles calculations using density functional theory. C(6)H(5)SH is chemisorbed on Pt(111) and Au(111) substrates to form a thiolate (C(6)H(5)S), and C(6)H(5)SeH is bound on Pt(111) substrate to form a selenolate (C(6)H(5)Se). In all cases, chemisorption-induced gap states (CIGSs) appear just below the Fermi level (E(F)) of the substrate, yielding a metallic character around the anchor S and Se atoms. However, the local density at E(F) decreases considerably from the anchor atom to the benzene ring, because strong coupling between benzene π(1e(1g)) and S 3p(or Se 4p) in free molecules is apparently lifted upon chemisorption. In other words, thiolates and selenolates (especially C(6)H(5)S on Au(111)) act as poor mediators of the metal wave functions at E(F), which is closely related to electric conductance in the relevant metal-organic-metal junctions at zero bias.

  11. Polarization-induced electrical conductivity in ultra-wide band gap AlGaN alloys

    Science.gov (United States)

    Armstrong, Andrew M.; Allerman, Andrew A.

    2016-11-01

    Unintentionally doped (UID) AlGaN epilayers graded over Al compositions of 80%-90% and 80%-100% were grown by metal organic vapor phase epitaxy and were electrically characterized using contactless sheet resistance (Rsh) and capacitance-voltage (C-V) measurements. Strong electrical conductivity in the UID graded AlGaN epilayers resulted from polarization-induced doping and was verified by the low resistivity of 0.04 Ω cm for the AlGaN epilayer graded over 80%-100% Al mole fraction. A free electron concentration (n) of 4.8 × 1017 cm-3 was measured by C-V for Al compositions of 80%-100%. Average electron mobility ( μ ¯ ) was calculated from Rsh and n data for three ranges of Al composition grading, and it was found that UID AlGaN graded from 88%-96% had μ ¯ = 509 cm2/V s. The combination of very large band gap energy, high μ ¯ , and high n for UID graded AlGaN epilayers make them attractive as a building block for high voltage power electronic devices such as Schottky diodes and field effect transistors.

  12. Field-induced Gap and Quantized Charge Pumping in Nano-helix

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Xiao-Liang; /Stanford U., Phys. Dept. /Tsinghua U., Beijing; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-02-15

    We propose several novel physical phenomena based on nano-scale helical wires. Applying a static electric field transverse to the helical wire induces a metal to insulator transition, with the band gap determined by the applied voltage. Similar idea can be applied to 'geometrically' constructing one-dimensional systems with arbitrary external potential. With a quadrupolar electrode configuration, the electric field could rotate in the transverse plane, leading to a quantized dc charge current proportional to the frequency of the rotation. Such a device could be used as a new standard for the high precession measurement of the electric current. The inverse effect implies that passing an electric current through a helical wire in the presence of a transverse static electric field can lead to a mechanical rotation of the helix. This effect can be used to construct nano-scale electro-mechanical motors. Finally, our methodology also enables new ways of controlling and measuring the electronic properties of helical biological molecules such as the DNA.

  13. Porcine induced pluripotent stem cells may bridge the gap between mouse and human iPS.

    Science.gov (United States)

    Esteban, Miguel A; Peng, Meixiu; Deli, Zhang; Cai, Jie; Yang, Jiayin; Xu, Jianyong; Lai, Liangxue; Pei, Duanqing

    2010-04-01

    Recently, three independent laboratories reported the generation of induced pluripotent stem cells (iPSCs) from pig (Sus scrofa). This finding sums to the growing list of species (mouse, human, monkey, and rat, in this order) for which successful reprogramming using exogenous factors has been achieved, and multiple others are possibly forthcoming. But apart from demonstrating the universality of the network identified by Shinya Yamanaka, what makes the porcine model so special? On one side, pigs are an agricultural commodity and have an easy and affordable maintenance compared with nonhuman primates that normally need to be imported. On the other side, resemblance (for example, size of organs) of porcine and human physiology is striking and because pigs are a regular source of food the ethical concerns that still remain in monkeys are not applicable. Besides, the prolonged lifespan of pigs compared with other domestic species can allow exhaustive follow up of side effects after transplantation. Porcine iPSCs may thus fill the gap between the mouse model, which due to its ease is preferred for mechanistic studies, and the first clinical trials using iPSCs in humans. However, although these studies are relevant and have created significant interest they face analogous problems that we discuss herein together with potential new directions.

  14. Ischaemia-induced autophagy leads to degradation of gap junction protein connexin43 in cardiomyocytes.

    Science.gov (United States)

    Martins-Marques, Tania; Catarino, Steve; Zuzarte, Monica; Marques, Carla; Matafome, Paulo; Pereira, Paulo; Girão, Henrique

    2015-04-15

    GJIC (gap junction intercellular communication) between cardiomyocytes is essential for synchronous heart contraction and relies on Cx (connexin)-containing channels. Increased breakdown of Cx43 has been often associated with various cardiac diseases. However, the mechanisms whereby Cx43 is degraded in ischaemic heart remain unknown. The results obtained in the present study, using both HL-1 cells and organotypic heart cultures, show that simulated ischaemia induces degradation of Cx43 that can be prevented by chemical or genetic inhibitors of autophagy. Additionally, ischaemia-induced degradation of Cx43 results in GJIC impairment in HL-1 cells, which can be restored by autophagy inhibition. In cardiomyocytes, ubiquitin signals Cx43 for autophagic degradation, through the recruitment of the ubiquitin-binding proteins Eps15 (epidermal growth factor receptor substrate 15) and p62, that assist in Cx43 internalization and targeting to autophagic vesicles, via LC3 (light chain 3). Moreover, we establish that degradation of Cx43 in ischaemia or I/R (ischaemia/reperfusion) relies upon different molecular players. Indeed, degradation of Cx43 during early periods of ischaemia depends on AMPK (AMP-activated protein kinase), whereas in late periods of ischaemia and I/R Beclin 1 is required. In the Langendorff-perfused heart, Cx43 is dephosphorylated in ischaemia and degraded during I/R, where Cx43 degradation correlates with autophagy activation. In summary, the results of the present study provide new evidence regarding the molecular mechanisms whereby Cx43 is degraded in ischaemia, which may contribute to the development of new strategies that aim to preserve GJIC and cardiac function in ischaemic heart.

  15. Autophagy and gap junctional intercellular communication inhibition are involved in cadmium-induced apoptosis in rat liver cells

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Hui [College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, 225009 (China); Zhuo, Liling [College of Life Science, Zaozhuang University, Zaozhuang, Shandong, 277160 (China); Han, Tao; Hu, Di; Yang, Xiaokang; Wang, Yi; Yuan, Yan; Gu, Jianhong; Bian, Jianchun; Liu, Xuezhong [College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, 225009 (China); Liu, Zongping, E-mail: liuzongping@yzu.edu.cn [College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, 225009 (China)

    2015-04-17

    Cadmium (Cd) is known to induce hepatotoxicity, yet the underlying mechanism of how this occurs is not fully understood. In this study, Cd-induced apoptosis was demonstrated in rat liver cells (BRL 3A) with apoptotic nuclear morphological changes and a decrease in cell index (CI) in a time- and concentration-dependent manner. The role of gap junctional intercellular communication (GJIC) and autophagy in Cd-induced apoptosis was investigated. Cd significantly induced GJIC inhibition as well as downregulation of connexin 43 (Cx43). The prototypical gap junction blocker carbenoxolone disodium (CBX) exacerbated the Cd-induced decrease in CI. Cd treatment was also found to cause autophagy, with an increase in mRNA expression of autophagy-related genes Atg-5, Atg-7, Beclin-1, and microtubule-associated protein light chain 3 (LC3) conversion from cytosolic LC3-I to membrane-bound LC3-II. The autophagic inducer rapamycin (RAP) prevented the Cd-induced CI decrease, while the autophagic inhibitor chloroquine (CQ) caused a further reduction in CI. In addition, CBX promoted Cd-induced autophagy, as well as changes in expression of Atg-5, Atg-7, Beclin-1 and LC3. CQ was found to block the Cd-induced decrease in Cx43 and GJIC inhibition, whereas RAP had opposite effect. These results demonstrate that autophagy plays a protective role during Cd-induced apoptosis in BRL 3A cells during 6 h of experiment, while autophagy exacerbates Cd-induced GJIC inhibition which has a negative effect on cellular fate. - Highlights: • GJIC and autophagy is crucial for biological processes. • Cd exposure causes GJIC inhibition and autophagy increase in BRL 3A cells. • Autophagy protects Cd induced BRL 3A cells apoptosis at an early stage. • Autophagy exacerbates Cd-induced GJIC inhibition. • GJIC plays an important role in autophagy induced cell death or survival.

  16. Phylogenetic inference under varying proportions of indel-induced alignment gaps

    Directory of Open Access Journals (Sweden)

    Gadagkar Sudhindra R

    2009-08-01

    Full Text Available Abstract Background The effect of alignment gaps on phylogenetic accuracy has been the subject of numerous studies. In this study, we investigated the relationship between the total number of gapped sites and phylogenetic accuracy, when the gaps were introduced (by means of computer simulation to reflect indel (insertion/deletion events during the evolution of DNA sequences. The resulting (true alignments were subjected to commonly used gap treatment and phylogenetic inference methods. Results (1 In general, there was a strong – almost deterministic – relationship between the amount of gap in the data and the level of phylogenetic accuracy when the alignments were very "gappy", (2 gaps resulting from deletions (as opposed to insertions contributed more to the inaccuracy of phylogenetic inference, (3 the probabilistic methods (Bayesian, PhyML & "MLε, " a method implemented in DNAML in PHYLIP performed better at most levels of gap percentage when compared to parsimony (MP and distance (NJ methods, with Bayesian analysis being clearly the best, (4 methods that treat gapped sites as missing data yielded less accurate trees when compared to those that attribute phylogenetic signal to the gapped sites (by coding them as binary character data – presence/absence, or as in the MLε method, and (5 in general, the accuracy of phylogenetic inference depended upon the amount of available data when the gaps resulted from mainly deletion events, and the amount of missing data when insertion events were equally likely to have caused the alignment gaps. Conclusion When gaps in an alignment are a consequence of indel events in the evolution of the sequences, the accuracy of phylogenetic analysis is likely to improve if: (1 alignment gaps are categorized as arising from insertion events or deletion events and then treated separately in the analysis, (2 the evolutionary signal provided by indels is harnessed in the phylogenetic analysis, and (3 methods that

  17. Temperature induced band gap shrinkage in Cu 2GeSe 3: Role of electron-phonon interaction

    Science.gov (United States)

    Sarkar, Bimal Kumar; Verma, Ajay Singh; Deviprasad, P. S.

    2011-07-01

    The ternary semiconducting compound Cu 2GeSe 3 has been investigated for optical properties with photoacoustic spectroscopy. Optical absorption spectra of Cu 2GeSe 3 is obtained in the range of 0.76-0.81 eV photon-energy at temperatures between 80 and 300 K. The thermal variation of band gap energy has been examined from the optical absorption spectra at different temperatures. The temperature induced band gap shrinkage has been explained on the basis of electron-phonon interaction. Varshni's empirical relation in conjunction with Vina and Passler model is taken into consideration for data fitting. The Debye temperature was calculated approximately as 240 K. The acoustic phonons with a characteristic temperature as 160 K corresponding to effective mean frequency have been attributed to the thermal variation of the energy gap.

  18. The number and size of subhalo-induced gaps in stellar streams

    CERN Document Server

    Erkal, Denis; Bovy, Jo; Sanders, Jason L

    2016-01-01

    Ample observational capabilities exist today to detect the small density perturbations that low-mass dark matter subhaloes impart on stellar streams from disrupting Galactic satellites. In anticipation of these observations, we investigate the expected number and size of gaps by combining an analytic prescription for gap evolution on circular orbits with the flux of subhaloes near the stream. We explore the distribution of gap sizes and depths for a typical cold stream around the Milky Way and find that for a given stream age and gap depth, each subhalo mass produces a characteristic gap size. For a stream with an age of a few Gyr, orbiting at a distance of 10-20 kpc from the Galactic center, even modest subhaloes with a mass of $10^6-10^7 M_\\odot$ produce gaps with sizes that are on the order of several degrees. We consider the number and distribution of gap sizes created by subhaloes with masses $10^5-10^9 M_\\odot$ and present predictions for six cold streams around the Milky Way. For Pal 5, we forecast 0.7...

  19. Functional role of gap junctions in cytokine-induced leukocyte adhesion to endothelium in vivo

    Science.gov (United States)

    Véliz, Loreto P.; González, Francisco G.; Duling, Brian R.; Sáez, Juan C.; Boric, Mauricio P.

    2008-01-01

    To assess the hypothesis that gap junctions (GJs) participate on leukocyte-endothelium interactions in the inflammatory response, we compared leukocyte adhesion and transmigration elicited by cytokine stimulation in the presence or absence of GJ blockers in the hamster cheek pouch and also in the cremaster muscle of wild-type (WT) and endothelium-specific connexin 43 (Cx43) null mice (Cx43e−/−). In the cheek pouch, topical tumor necrosis factor-α (TNF-α; 150 ng/ml, 15 min) caused a sustained increment in the number of leukocytes adhered to venular endothelium (LAV) and located at perivenular regions (LPV). Superfusion with the GJ blockers 18-α-glycyrrhetinic acid (AGA; 75 μM) or 18-β-glycyrrhetinic acid (50 μM) abolished the TNF-α-induced increase in LAV and LPV; carbenoxolone (75 μM) or oleamide (100 μM) reduced LAV by 50 and 75%, respectively, and LPV to a lesser extent. None of these GJ blockers modified venular diameter, blood flow, or leukocyte rolling. In contrast, glycyrrhizin (75 μM), a non-GJ blocker analog of AGA, was devoid of effect. Interestingly, when AGA was removed 90 min after TNF-α stimulation, LAV started to rise at a similar rate as in control. Conversely, application of AGA 90 min after TNF-α reduced the number of previously adhered cells. In WT mice, intrascrotal injection of TNF-α (0.5 μg/0.3 ml) increased LAV (fourfold) and LPV (threefold) compared with saline-injected controls. In contrast to the observations in WT animals, TNF-α stimulation did not increase LAV or LPV in Cx43e−/− mice. These results demonstrate an important role for GJ communication in leukocyte adhesion and transmigration during acute inflammation in vivo and further suggest that endothelial Cx43 is key in these processes. PMID:18599597

  20. Self-amplified photo-induced gap quenching in a correlated electron material

    Science.gov (United States)

    Mathias, S.; Eich, S.; Urbancic, J.; Michael, S.; Carr, A. V.; Emmerich, S.; Stange, A.; Popmintchev, T.; Rohwer, T.; Wiesenmayer, M.; Ruffing, A.; Jakobs, S.; Hellmann, S.; Matyba, P.; Chen, C.; Kipp, L.; Bauer, M.; Kapteyn, H. C.; Schneider, H. C.; Rossnagel, K.; Murnane, M. M.; Aeschlimann, M.

    2016-10-01

    Capturing the dynamic electronic band structure of a correlated material presents a powerful capability for uncovering the complex couplings between the electronic and structural degrees of freedom. When combined with ultrafast laser excitation, new phases of matter can result, since far-from-equilibrium excited states are instantaneously populated. Here, we elucidate a general relation between ultrafast non-equilibrium electron dynamics and the size of the characteristic energy gap in a correlated electron material. We show that carrier multiplication via impact ionization can be one of the most important processes in a gapped material, and that the speed of carrier multiplication critically depends on the size of the energy gap. In the case of the charge-density wave material 1T-TiSe2, our data indicate that carrier multiplication and gap dynamics mutually amplify each other, which explains--on a microscopic level--the extremely fast response of this material to ultrafast optical excitation.

  1. Leptin Induces Hippocampal Synaptogenesis via CREB-Regulated MicroRNA-132 Suppression of p250GAP

    Science.gov (United States)

    Dhar, Matasha; Zhu, Mingyan; Impey, Soren; Lambert, Talley J.; Bland, Tyler; Karatsoreos, Ilia N.; Nakazawa, Takanobu

    2014-01-01

    Leptin acts in the hippocampus to enhance cognition and reduce depression and anxiety. Cognitive and emotional disorders are associated with abnormal hippocampal dendritic spine formation and synaptogenesis. Although leptin has been shown to induce synaptogenesis in the hypothalamus, its effects on hippocampal synaptogenesis and the mechanism(s) involved are not well understood. Here we show that leptin receptors (LepRs) are critical for hippocampal dendritic spine formation in vivo because db/db mice lacking the long form of the leptin receptor (LepRb) have reduced spine density on CA1 and CA3 neurons. Leptin promotes the formation of mature spines and functional glutamate synapses on hippocampal pyramidal neurons in both dissociated and slice cultures. These effects are blocked by short hairpin RNAs specifically targeting the LepRb and are absent in cultures from db/db mice. Activation of the LepR leads to cAMP response element–binding protein (CREB) phosphorylation and initiation of CREB-dependent transcription via the MAPK kinase/Erk pathway. Furthermore, both Mek/Erk and CREB activation are required for leptin-induced synaptogenesis. Leptin also increases expression of microRNA-132 (miR132), a well-known CREB target, which is also required for leptin-induced synaptogenesis. Last, leptin suppresses the expression of p250GAP, a miR132 target, and this suppression is obligatory for leptin's effects as is the downstream target of p250GAP, Rac1. LepRs appear to be critical in vivo as db/db mice have lowered hippocampal miR132 levels and elevated p250GAP expression. In conclusion, we identify a novel signaling pathway by which leptin increases synaptogenesis through inducing CREB transcription and increasing microRNA-mediated suppression of p250GAP activity, thus removing a known inhibitor of Rac1-stimulated synaptogenesis. PMID:24877561

  2. Dust coagulation and magnetic field strength in a planet-induced gap subject to MRI turbulence

    Science.gov (United States)

    Carballido, Augusto; Matthews, Lorin; Hyde, Truell

    2017-01-01

    We investigate the coagulation of dust particles in and around a gap opened by a Jupiter-mass planet. To this end, we carry out a high-resolution magnetohydrodynamic (MHD) simulation of the gap environment, which is turbulent due to the magneto rotational instability. From the MHD simulation, we obtain values of the gas velocities, densities and turbulent stresses close to the gap edge, in one of the two gas streams that accrete onto the planet, and inside the low-density gap. The MHD values are then supplied to a Monte Carlo dust coagulation algorithm, which models grain sticking, compaction and bouncing. We consider two dust populations for each region: one whose initial size distribution is monodisperse, with monomer radius equal to 1 micron, and another one whose initial size distribution follows the Mathis-Rumpl-Nordsieck distribution for interstellar dust grains, with an initial range of monomer radii between 0.5 and 10 microns. Without bouncing, our Monte Carlo calculations show steady growth of dust aggregates in all regions, and the mass-weighted (MW) average porosity of the initially mono disperse population reaches extremely high final values of 98%. The final MW porosities in all other cases without bouncing range from 30% to 82%. The efficiency of compaction is due to high turbulent relative speeds between dust particles. When bouncing is introduced, growth is slowed down in the planetary wake and inside the gap.We also analyze the strength of the magnetic field threading the gaps opened by planets of different sub-Jovian masses. Preliminary results show that, in a gap opened by a large-mass planet (~ 1 MJ), the time-averaged radial profile of the vertical component of the field (Bz) increases sharply inside the gap, and less sharply in the case of less massive planets. In gaps opened by intermediate-mass planets (~ 0.5 — 0.75 MJ), the radial profile of Bz exhibits local maxima in the vicinity of the planet, but not at the gap center.

  3. Oxygen vacancy induced band gap narrowing of ZnO nanostructures by an electrochemically active biofilm.

    Science.gov (United States)

    Ansari, Sajid Ali; Khan, Mohammad Mansoob; Kalathil, Shafeer; Nisar, Ambreen; Lee, Jintae; Cho, Moo Hwan

    2013-10-07

    Band gap narrowing is important and advantageous for potential visible light photocatalytic applications involving metal oxide nanostructures. This paper reports a simple biogenic approach for the promotion of oxygen vacancies in pure zinc oxide (p-ZnO) nanostructures using an electrochemically active biofilm (EAB), which is different from traditional techniques for narrowing the band gap of nanomaterials. The novel protocol improved the visible photocatalytic activity of modified ZnO (m-ZnO) nanostructures through the promotion of oxygen vacancies, which resulted in band gap narrowing of the ZnO nanostructure (Eg = 3.05 eV) without dopants. X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and high resolution transmission electron microscopy confirmed the oxygen vacancy and band gap narrowing of m-ZnO. m-ZnO enhanced the visible light catalytic activity for the degradation of different classes of dyes and 4-nitrophenol compared to p-ZnO, which confirmed the band gap narrowing because of oxygen defects. This study shed light on the modification of metal oxide nanostructures by EAB with a controlled band structure.

  4. Acetaminophen-induced anion gap metabolic acidosis secondary to 5-oxoproline: a case report.

    Science.gov (United States)

    Abkur, Tarig Mohammed; Mohammed, Waleed; Ali, Mohamed; Casserly, Liam

    2014-12-06

    5-oxoproline (pyroglutamic acid), an organic acid intermediate of the gamma-glutamyl cycle, is a rare cause of high anion gap metabolic acidosis. Acetaminophen and several other drugs have been implicated in the development of transient 5-oxoprolinemia in adults. We believe that reporting all cases of 5-oxoprolinemia will contribute to a better understanding of this disease. Here, we report the case of a patient who developed transient 5-oxoprolinemia following therapeutic acetaminophen use. A 75-year-old Caucasian woman was initially admitted for treatment of an infected hip prosthesis and subsequently developed transient high anion gap metabolic acidosis. Our patient received 40 g of acetaminophen over a 10-day period. After the more common causes of high anion gap metabolic acidosis were excluded, a urinary organic acid screen revealed a markedly increased level of 5-oxoproline. The acidosis resolved completely after discontinuation of the acetaminophen. 5-oxoproline acidosis is an uncommon cause of high anion gap metabolic acidosis; however, it is likely that it is under-diagnosed as awareness of the condition remains low and testing can only be performed at specialized laboratories. The diagnosis should be suspected in cases of anion gap metabolic acidosis, particularly in patients with recent acetaminophen use in combination with sepsis, malnutrition, liver disease, pregnancy or renal failure. This case has particular interest in medicine, especially for the specialties of nephrology and orthopedics. We hope that it will add more information to the literature about this rare condition.

  5. Interaction dynamics of gap flow with vortex-induced vibration in side-by-side cylinder arrangement

    Science.gov (United States)

    Liu, Bin; Jaiman, Rajeev K.

    2016-12-01

    A numerical investigation of the vortex-induced vibration (VIV) in a side-by-side circular cylinder arrangement has been performed in a two-dimensional laminar flow environment. One of the cylinders is elastically mounted and only vibrates in the transverse direction, while its counterpart remains stationary in a uniform flow stream. When the gap ratio is sufficiently small, the flip-flopping phenomenon of the gap flow can be an additional time-dependent interference to the flow field. This phenomenon was reported in the experimental work of Bearman and Wadcock ["The interaction between a pair of circular cylinders normal to a stream," J. Fluid Mech. 61(3), 499-511 (1973)] in a side-by-side circular cylinder arrangement, in which the gap flow deflects toward one of the cylinders and switched its sides intermittently. Albeit one of the two cylinders is free to vibrate, the flip-flop of a gap flow during VIV dynamics can still be observed outside the lock-in region. The exact moments of the flip-flop phenomenon due to spontaneous symmetry breaking are observed in this numerical study. The significant characteristic vortex modes in the near-wake region are extracted via dynamic modal analysis and the interference between the gap flow and VIV is found to be mutual. In a vibrating side-by-side arrangement, the lock-in region with respect to reduced velocity becomes narrower due to the interference from its stationary counterpart. The frequency lock-in occurs and ends earlier than that of an isolated vibrating circular cylinder subjected to an identical flow environment. Similar to a tandem cylinder arrangement, in the post-lock-in region, the maximum vibration amplitudes are escalated compared with those of an isolated circular cylinder configuration. On the other hand, subjected to the influence from VIV, the biased gap flow deflects toward the vibrating cylinder quasi-stably during the frequency lock-in process. This behavior is different from the reported bi

  6. Strain-Induced Energy Band Gap Opening in Two-Dimensional Bilayered Silicon Film

    Science.gov (United States)

    Ji, Z.; Zhou, R.; Lew Yan Voon, L. C.; Zhuang, Y.

    2016-10-01

    This work presents a theoretical study of the structural and electronic properties of bilayered silicon film (BiSF) under in-plane biaxial strain/stress using density functional theory (DFT). Atomic structures of the two-dimensional (2-D) silicon films are optimized by using both the local-density approximation (LDA) and generalized gradient approximation (GGA). In the absence of strain/stress, five buckled hexagonal honeycomb structures of the BiSF with triangular lattice have been obtained as local energy minima, and their structural stability has been verified. These structures present a Dirac-cone shaped energy band diagram with zero energy band gaps. Applying a tensile biaxial strain leads to a reduction of the buckling height. Atomically flat structures with zero buckling height have been observed when the AA-stacking structures are under a critical biaxial strain. Increase of the strain between 10.7% and 15.4% results in a band-gap opening with a maximum energy band gap opening of ˜0.17 eV, obtained when a 14.3% strain is applied. Energy band diagrams, electron transmission efficiency, and the charge transport property are calculated. Additionally, an asymmetric energetically favorable atomic structure of BiSF shows a non-zero band gap in the absence of strain/stress and a maximum band gap of 0.15 eV as a -1.71% compressive strain is applied. Both tensile and compressive strain/stress can lead to a band gap opening in the asymmetric structure.

  7. Bismuth-induced Raman modes in GaP1- x Bi x

    Science.gov (United States)

    Christian, Theresa M.; Fluegel, Brian; Beaton, Daniel A.; Alberi, Kirstin; Mascarenhas, Angelo

    2016-10-01

    Dilute bismide semiconductor alloys are a promising material platform for optoelectronic devices due to drastic impacts of bismuth on the electronic structure of the alloy. At the same time, the details of bismuth incorporation in the lattice are not fully understood. In this work, we conduct Raman scattering spectroscopy on GaP1- x Bi x epilayers grown by molecular beam epitaxy (MBE) and identify several bismuth-related Raman features including gap vibration modes at 296, 303, and 314 cm-1. This study paves the way for more detailed analysis of the local symmetry at bismuth incorporation sites in the dilute bismide alloy regime.

  8. Bismuth-Induced Raman Modes in GaP1-xBix

    Energy Technology Data Exchange (ETDEWEB)

    Christian, Theresa M.; Fluegel, Brian; Beaton, Daniel A.; Alberi, Kirstin; Mascarenhas, Angelo

    2016-10-01

    Dilute bismide semiconductor alloys are a promising material platform for optoelectronic devices due to drastic impacts of bismuth on the electronic structure of the alloy. At the same time, the details of bismuth incorporation in the lattice are not fully understood. In this work, we conduct Raman scattering spectroscopy on GaP1- x Bi x epilayers grown by molecular beam epitaxy (MBE) and identify several bismuth-related Raman features including gap vibration modes at 296, 303, and 314 cm-1. This study paves the way for more detailed analysis of the local symmetry at bismuth incorporation sites in the dilute bismide alloy regime.

  9. Highly effective strain-induced band-engineering of (111) oriented, direct-gap GeSn crystallized on amorphous SiO2 layers

    Science.gov (United States)

    Li, Haofeng; Wang, Xiaoxin; Liu, Jifeng

    2016-03-01

    We demonstrate highly effective strain-induced band-engineering of (111) oriented direct-gap Ge1-xSnx thin films (0.074 GeSn films also demonstrate high thermal stability, offering both excellent direct-gap optoelectronic properties and fabrication/operation robustness for integrated photonics.

  10. Orbital migration of giant planets induced by gravitationally unstable gaps: the effect of planet mass

    CERN Document Server

    Cloutier, Ryan

    2013-01-01

    It has been suggested that long-period giant planets, such as HD 95086b and HR 8799bcde, may have formed through gravitational instability of protoplanetary discs. However, self-gravitating disc-satellite interaction can lead to the formation of a gravitationally unstable gap. Such an instability significantly affects the orbital migration of gap-opening perturbers in massive discs. We use 2D hydrodynamical simulations to examine the role of planet mass on the gravitational stability of gaps and its impact on orbital migration. We consider giant planets with planet-to-star mass ratio q=0.0003 to q=0.003, in a self-gravitating disc with disc-to-star mass ratio M_d/M_*=0.08, aspect ratio h=0.05, and Keplerian Toomre parameter Q = 1.5 at 2.5 times the planet's initial orbital radius. Fixed-orbit simulations show that all planet masses we consider open gravitationally unstable gaps, but the instability is stronger and develops sooner with increasing planet mass. The disc-on-planet torques typically become more po...

  11. Hofstadter butterflies and magnetically induced band-gap quenching in graphene antidot lattices

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Pedersen, Thomas Garm

    2013-01-01

    We study graphene antidot lattices (GALs) in magnetic fields. Using a tight-binding model and a recursive Green's function technique that we extend to deal with periodic structures, we calculate Hofstadter butterflies of GALs. We compare the results to those obtained in a simpler gapped graphene...

  12. MoS2-WSe2 Hetero Bilayer: Possibility of Mechanical Strain Induced Band Gap Engineering

    Science.gov (United States)

    Sharma, Munish; Kumar, Ashok; Ahluwalia, P. K.

    2014-03-01

    The tunability of band gap in two-dimensional (2D) hetero-bilayers of MoS2-WSe2 with applied mechanical strains (in-plane and out-of-plane) in two different types of stackings (AA and AB) have been investigated in the framework of density functional theory (DFT). The in-plane biaxial tensile strain is found to reduce electronic band gap monotonically and rendered considered bilayer into metal at 6% of applied strain. The transition pressure required for complete semiconductor-to-metal transition is found to be of 7.89 GPa while tensile strength of the reported hetero-bilayer has been calculated 10 GPa at 25% strain. In case of vertical compression strain, 16 GPa pressure has been calculated for complete semiconductor-to-metal transition. The band-gap deformation potentials and effective masses (electron and hole) have been found to posses strong dependence on the type of applied strain. Such band gap engineering in controlled manner (internal control by composition and external control by applied strain) makes the considered hetero-bilayer as a strong candidate for the application in variety of nano scale devices.

  13. The strain induced band gap modulation from narrow gap semiconductor to half-metal on Ti2CrGe: A first principles study

    Directory of Open Access Journals (Sweden)

    Jia Li

    2015-11-01

    Full Text Available The Heusler alloy Ti2CrGe is a stable L21 phase with antiferromagnetic ordering. With band-gap energy (∼ 0.18 eV obtained from a first-principles calculation, it belongs to the group of narrow band gap semiconductor. The band-gap energy decreases with increasing lattice compression and disappears until a strain of −5%; moreover, gap contraction only occurs in the spin-down states, leading to half-metallic character at the −5% strain. The Ti1, Ti2, and Cr moments all exhibit linear changes in behavior within strains of −5%– +5%. Nevertheless, the total zero moment is robust for these strains. The imaginary part of the dielectric function for both up and down spin states shows a clear onset energy, indicating a corresponding electronic gap for the two spin channels.

  14. S-diclofenac Protects against Doxorubicin-Induced Cardiomyopathy in Mice via Ameliorating Cardiac Gap Junction Remodeling

    Science.gov (United States)

    Zhang, Huili; Zhang, Alian; Guo, Changfa; Shi, Chunzhi; Zhang, Yang; Liu, Qing; Sparatore, Anna; Wang, Changqian

    2011-01-01

    Hydrogen sulfide (H2S), as a novel gaseous mediator, plays important roles in mammalian cardiovascular tissues. In the present study, we investigated the cardioprotective effect of S-diclofenac (2-[(2,6-dichlorophenyl)amino] benzeneacetic acid 4-(3H-1,2,dithiol-3-thione-5-yl)phenyl ester), a novel H2S-releasing derivative of diclofenac, in a murine model of doxorubicin-induced cardiomyopathy. After a single dose injection of doxorubicin (15 mg/kg, i.p.), male C57BL/6J mice were given daily treatment of S-diclofenac (25 and 50 µmol/kg, i.p.), diclofenac (25 and 50 µmol/kg, i.p.), NaHS (50 µmol/kg, i.p.), or same volume of vehicle. The cardioprotective effect of S-diclofenac was observed after 14 days. It showed that S-diclofenac, but not diclofenac, dose-dependently inhibited the doxorubicin-induced downregulation of cardiac gap junction proteins (connexin 43 and connexin 45) and thus reversed the remodeling of gap junctions in hearts. It also dose-dependently suppressed doxorubicin-induced activation of JNK in hearts. Furthermore, S-diclofenac produced a dose-dependent anti-inflammatory and anti-oxidative effect in this model. As a result, S-diclofenac significantly attenuated doxorubicin-related cardiac injury and cardiac dysfunction, and improved the survival rate of mice with doxorubicin-induced cardiomyopathy. These effects of S-diclofenac were mimicked in large part by NaHS. Therefore, we propose that H2S released from S-diclofenac in vivo contributes to the protective effect in doxorubicin-induced cardiomyopathy. These data also provide evidence for a critical role of H2S in the pathogenesis of doxorubicin-induced cardiomyopathy. PMID:22039489

  15. S-diclofenac protects against doxorubicin-induced cardiomyopathy in mice via ameliorating cardiac gap junction remodeling.

    Directory of Open Access Journals (Sweden)

    Huili Zhang

    Full Text Available Hydrogen sulfide (H(2S, as a novel gaseous mediator, plays important roles in mammalian cardiovascular tissues. In the present study, we investigated the cardioprotective effect of S-diclofenac (2-[(2,6-dichlorophenylamino] benzeneacetic acid 4-(3H-1,2,dithiol-3-thione-5-ylphenyl ester, a novel H(2S-releasing derivative of diclofenac, in a murine model of doxorubicin-induced cardiomyopathy. After a single dose injection of doxorubicin (15 mg/kg, i.p., male C57BL/6J mice were given daily treatment of S-diclofenac (25 and 50 µmol/kg, i.p., diclofenac (25 and 50 µmol/kg, i.p., NaHS (50 µmol/kg, i.p., or same volume of vehicle. The cardioprotective effect of S-diclofenac was observed after 14 days. It showed that S-diclofenac, but not diclofenac, dose-dependently inhibited the doxorubicin-induced downregulation of cardiac gap junction proteins (connexin 43 and connexin 45 and thus reversed the remodeling of gap junctions in hearts. It also dose-dependently suppressed doxorubicin-induced activation of JNK in hearts. Furthermore, S-diclofenac produced a dose-dependent anti-inflammatory and anti-oxidative effect in this model. As a result, S-diclofenac significantly attenuated doxorubicin-related cardiac injury and cardiac dysfunction, and improved the survival rate of mice with doxorubicin-induced cardiomyopathy. These effects of S-diclofenac were mimicked in large part by NaHS. Therefore, we propose that H(2S released from S-diclofenac in vivo contributes to the protective effect in doxorubicin-induced cardiomyopathy. These data also provide evidence for a critical role of H(2S in the pathogenesis of doxorubicin-induced cardiomyopathy.

  16. Microwave irradiation induced band gap tuning of MoS2-TiO2 nanocomposites

    Science.gov (United States)

    Shakya, Jyoti; Mohanty, T.

    2016-05-01

    The MoS2-TiO2 nanocomposites have been synthesized by sol-gel method and characterized by different microscopic and spectroscopic techniques. The crystallinity of these nanocomposites has been confirmed by X-ray diffraction (XRD) analysis. The Raman spectrum of MoS2-TiO2 nanocomposites consists of three distinct peaks (E1 g, E1 2g and A1g) which are associated with TiO2 and MoS2. The morphological study is carried out by scanning electron microscope. The effect of microwave irradiation on the band gap of MoS2-TiO2 nanocomposites has been investigated; it is observed that the microwave irradiation causes decrease in the band gap of MoS2-TiO2 nanocomposites. The microwave treated MoS2-TiO2 thin films offers a novel process route in treating thin films for commercial applications.

  17. Two-dimensional silica: Structural, mechanical properties, and strain-induced band gap tuning

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Enlai; Xie, Bo [Applied Mechanics Laboratory, Department of Engineering Mechanics, and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084 (China); Xu, Zhiping, E-mail: xuzp@tsinghua.edu.cn [Applied Mechanics Laboratory, Department of Engineering Mechanics, and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

    2016-01-07

    Two-dimensional silica is of rising interests not only for its practical applications as insulating layers in nanoelectronics, but also as a model material to understand crystals and glasses. In this study, we examine structural and electronic properties of hexagonal and haeckelite phases of silica bilayers by performing first-principles calculations. We find that the corner-sharing SiO{sub 4} tetrahedrons in these two phases are locally similar. The robustness and resilience of these tetrahedrons under mechanical perturbation allow effective strain engineering of the electronic structures with band gaps covering a very wide range, from of that for insulators, to wide-, and even narrow-gap semiconductors. These findings suggest that the flexible 2D silica holds great promises in developing nanoelectronic devices with strain-tunable performance, and lay the ground for the understanding of crystalline and vitreous phases in 2D, where bilayer silica provides an ideal test-bed.

  18. Observation of the four wave mixing photonic band gap signal in electromagnetically induced grating.

    Science.gov (United States)

    Ullah, Zakir; Wang, Zhiguo; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

    2014-12-01

    For the first time, we experimentally and theoretically research about the probe transmission signal (PTS), the reflected four wave mixing band gap signal(FWM BGS) and fluorescence signal (FLS) under the double dressing effect in an inverted Y-type four level system. FWM BGS results from photonic band gap structure. We demonstrate that the characteristics of PTS, FWM BGS and FLS can be controlled by power, phase and the frequency detuning of the dressing beams. It is observed in our experiment that FWM BGS switches from suppression to enhancement, corresponding to the switch from transmission enhancement to absorption enhancement in the PTS with changing the relative phase. We also observe the relation among the three signals, which satisfy the law of conservation of energy. Such scheme could have potential applications in optical diodes, amplifiers and quantum information processing.

  19. Impurity-induced photoconductivity of narrow-gap Cadmium–Mercury–Telluride structures

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, D. V., E-mail: dvkoz@impras.ru; Rumyantsev, V. V.; Morozov, S. V.; Kadykov, A. M. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Varavin, V. S.; Mikhailov, N. N.; Dvorestky, S. A. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Gavrilenko, V. I. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Teppe, F. [Universite Montpellier II, Laboratoire Charles Coulomb (L2C) (France)

    2015-12-15

    The photoconductivity (PC) spectra of CdHgTe (MCT) solid solutions with a Cd fraction of 17 and 19% are measured. A simple model for calculating the states of doubly charged acceptors in MCT solid solutions, which makes it possible to describe satisfactorily the observed photoconductivity spectra, is proposed. The found lines in the photoconductivity spectra of narrow-gap MCT structures are associated with transitions between the states of both charged and neutral acceptor centers.

  20. Quantum confinement induced band gaps in MgB2 nanosheets

    Science.gov (United States)

    Xu, Bo Z.; Beckman, Scott P.

    2016-09-01

    The discovery of two-dimensional semiconducting materials, a decade ago, spawned an entire sub-field within solid-state physics that is focused on the development of nanoelectronics. Here we present a new class of semiconducting two-dimensional material based on hexagonal MgB2. Although MgB2 is a semimetal, similar to the other well-studied transition metal diborides, we demonstrate that, unlike the transition metal diborides, thinning MgB2, to create nanosheets, opens a band gap in the density of states. We predict that a 7 Å thick MgB2 nanosheet will have a band gap of 0.51 eV. MgB2 nanosheets differ from other two-dimensional semiconductors in that the band gap is introduced by (001) surfaces and is opened by the quantum confinement effect. The implications of these findings are that nanostructured MgB2 is not merely a new composition, but also has intrinsic mechanisms for tuning its electronic properties, which may facilitate the development of nanoelectronics.

  1. Gaps induced by inversion symmetry breaking and second-generation Dirac cones in graphene/hexagonal boron nitride

    Science.gov (United States)

    Wang, Eryin; Lu, Xiaobo; Ding, Shijie; Yao, Wei; Yan, Mingzhe; Wan, Guoliang; Deng, Ke; Wang, Shuopei; Chen, Guorui; Ma, Liguo; Jung, Jeil; Fedorov, Alexei V.; Zhang, Yuanbo; Zhang, Guangyu; Zhou, Shuyun

    2016-12-01

    Graphene/hexagonal boron nitride (h-BN) has emerged as a model van der Waals heterostructure as the superlattice potential, which is induced by lattice mismatch and crystal orientation, gives rise to various novel quantum phenomena, such as the self-similar Hofstadter butterfly states. Although the newly generated second-generation Dirac cones (SDCs) are believed to be crucial for understanding such intriguing phenomena, fundamental knowledge of SDCs, such as locations and dispersion, and the effect of inversion symmetry breaking on the gap opening, still remains highly debated due to the lack of direct experimental results. Here we report direct experimental results on the dispersion of SDCs in 0°-aligned graphene/h-BN heterostructures using angle-resolved photoemission spectroscopy. Our data unambiguously reveal SDCs at the corners of the superlattice Brillouin zone, and at only one of the two superlattice valleys. Moreover, gaps of approximately 100 meV and approximately 160 meV are observed at the SDCs and the original graphene Dirac cone, respectively. Our work highlights the important role of a strong inversion-symmetry-breaking perturbation potential in the physics of graphene/h-BN, and fills critical knowledge gaps in the band structure engineering of Dirac fermions by a superlattice potential.

  2. Induced Kramer-Pesch effect in a two-gap superconductor: Application to MgB2

    Science.gov (United States)

    Gumann, A.; Graser, S.; Dahm, T.; Schopohl, N.

    2006-03-01

    The size of the vortex core in a clean superconductor is strongly temperature dependent and shrinks with decreasing temperature, decreasing to zero for T→0 . We study this so-called Kramer-Pesch effect both for a single-gap superconductor and for the case of a two-gap superconductor using parameters appropriate for magnesium diboride. Usually, the Kramer-Pesch effect is absent in the dirty limit. Here, we show that the Kramer-Pesch effect exists in both bands of a two-gap superconductor even if only one of the two bands is in the clean limit and the other band in the dirty limit, a case appropriate for MgB2 . In this case an induced Kramer-Pesch effect appears in the dirty band. Besides numerical results we also present an analytical model for the spatial variation of the pairing potential in the vicinity of the vortex center that allows a simple calculation of the vortex core radius even in the limit T→0 .

  3. GAP Analysis Program (GAP)

    Data.gov (United States)

    Kansas Data Access and Support Center — The Kansas GAP Analysis Land Cover database depicts 43 land cover classes for the state of Kansas. The database was generated using a two-stage hybrid classification...

  4. Deep ventilation in the Okinawa Trough induced by Kerama Gap overflow

    Science.gov (United States)

    Nishina, Ayako; Nakamura, Hirohiko; Park, Jae-Hun; Hasegawa, Daisuke; Tanaka, Yuki; Seo, Seongbong; Hibiya, Toshiyuki

    2016-08-01

    Near-bottom water flowing over the Kerama Gap's sills is thought to ventilate the deep water below ˜1100 m depth in the Okinawa Trough and then upwell with 5-10 years residence time. The present study follows up on this phenomenon, using comprehensive profile data of temperature, salinity, dissolved oxygen, currents and turbulence obtained by intensive shipboard observations performed in June 2013 and June 2014 in the region. Strong near-bottom subtidal flow with speeds exceeding 0.5 m s-1 was observed within a layer of about 100 m thickness over the western side of the peak of the main sill. Temperature and salinity sections along the Kerama Gap indicated some depressions and overturns of the deep water downstream of the strong overflow, suggesting the existence of breaking internal gravity waves and hydraulic jumps. Associated vertical diffusivities, estimated using the Thorpe scale and the buoyancy frequency, were three to four orders of magnitude larger than typical values observed in the thermocline of the open ocean (˜10-5 m2 s-1). The dissolved oxygen section also indicated strong vertical mixing and associated upwelling with the entrainment of the near-bottom overflow water into the lower thermocline beneath the Kuroshio in the Okinawa Trough. The present study not only supports the previous conceptual model but also provides new evidence that the Okinawa Trough is an upwelling location where nutrient rich Philippine Sea intermediate water is sucked up into the lower thermocline below the Kuroshio.

  5. Inflammatory conditions induce gap junctional communication between rat Kupffer cells both in vivo and in vitro

    Science.gov (United States)

    Eugenín, Eliseo A.; González, Hernán E.; Sánchez, Helmuth A.; Brañes, María C.; Sáez, Juan C.

    2007-01-01

    Connexin43 (Cx43), a gap junction protein subunit, has been previously detected in Kupffer cells (KCs) during liver inflammation, however, KCs phagocytose cell debris that may include Cx43 protein, which could explain the detection of Cx43 in KCs. We determined that KCs express Cx43 and form gap junctions both in vivo and in vitro. In liver sections of animals treated with LPS, Cx43 was detected at ED2+ cells interfaces, indicating formation of GJ between KCs in vivo. In vitro, unstimulated KCs cultures did not form functional GJs, and expressed low levels of Cx43 that showed a diffuse intracellular distribution. In contrast, KCs treated with LPS plus IFN-γ, expressed a greater amount of Cx43 at both the, protein and mRNA levels, and showed Cx43 at cell-cell contacts associated with higher dye coupling. In conclusion, activation of KCs in vivo or in vitro resulted in enhanced Cx43 expression levels and formation of GJ that might play relevant roles during liver inflammation. PMID:17900549

  6. Band Gap Opening Induced by the Structural Periodicity in Epitaxial Graphene Buffer Layer.

    Science.gov (United States)

    N Nair, Maya; Palacio, Irene; Celis, Arlensiú; Zobelli, Alberto; Gloter, Alexandre; Kubsky, Stefan; Turmaud, Jean-Philippe; Conrad, Matthew; Berger, Claire; de Heer, Walter; Conrad, Edward H; Taleb-Ibrahimi, Amina; Tejeda, Antonio

    2017-04-12

    The epitaxial graphene buffer layer on the Si face of hexagonal SiC shows a promising band gap, of which the precise origin remains to be understood. In this work, we correlate the electronic to the atomic structure of the buffer layer by combining angle resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy (STM), and high-resolution scanning transmission electron microscopy (HR-STEM). We show that the band structure in the buffer has an electronic periodicity related to the structural periodicity observed in STM images and published X-ray diffraction. Our HR-STEM measurements show the bonding of the buffer layer to the SiC at specific locations separated by 1.5 nm. This is consistent with the quasi 6 × 6 periodic corrugation observed in the STM images. The distance between buffer C and SiC is 1.9 Å in the bonded regions and up to 2.8 Å in the decoupled regions, corresponding to a 0.9 Å corrugation of the buffer layer. The decoupled regions are sp(2) hybridized. Density functional tight binding (DFTB) calculations demonstrate the presence of a gap at the Dirac point everywhere in the buffer layer, even in the decoupled regions where the buffer layer has an atomic structure close to that of graphene. The surface periodicity also promotes band in the superperiodic Brillouin zone edges as seen by photoemission and confirmed by our calculations.

  7. Doping induced metallization of a narrow gap insulator FeGa3

    Science.gov (United States)

    Gamza, Monika; Puri, Akshat; Tomczak, Jan; Quinn, Jim; Aronson, Meigan

    2013-03-01

    Narrow gap semiconductors attract great interest owing to an unusual metallization process which remains poorly understood despite decades of extensive research. Here, we report on the effects of hole doping on properties of a nonmagnetic semiconductor FeGa3 with a band gap of 0.4 eV. By means of electrical resistivity, magnetization and specific heat measurements performed on single crystals grown from gallium flux we have found that a substitution of Mn for Fe in Fe1-xMnxGa3 (0.005< x < 0.03) yields an insulating state at high temperatures with residual magnetic moments. With lowering temperature, resistivity deviates from an activation-type behavior and nearly saturates at T<100 K. Finally, it drops by as much as two orders of magnitude at temperature of 6 K, indicating a metal-insulator transition. Magnetization measurements did not show magnetic order associated with the transition. When an external magnetic field is applied, the metal-insulator transition moves to lower temperatures and eventually the resistivity returns to the insulating-type behavior in fields higher then of 5 Tesla.

  8. Local strain-induced band gap fluctuations and exciton localization in aged WS2 monolayers

    Science.gov (United States)

    Krustok, J.; Kaupmees, R.; Jaaniso, R.; Kiisk, V.; Sildos, I.; Li, B.; Gong, Y.

    2017-06-01

    Optical properties of aged WS2 monolayers grown by CVD method on Si/SiO2 substrates are studied using temperature dependent photoluminescence and reflectance contrast spectroscopy. Aged WS2 monolayers have a typical surface roughness about 0.5 nm and, in addition, a high density of nanoparticles (nanocaps) with the base diameter about 30 nm and average height of 7 nm. The A-exciton of aged monolayer has a peak position at 1.951 eV while in as-grown monolayer the peak is at about 24 meV higher energy at room temperature. This red-shift is explained using local tensile strain concept, where strain value of 2.1% was calculated for these nanocap regions. Strained nanocaps have lower band gap energy and excitons will funnel into these regions. At T=10K a double exciton and trion peaks were revealed. The separation between double peaks is about 20 meV and the origin of higher energy peaks is related to the optical band gap energy fluctuations caused by random distribution of local tensile strain due to increased surface roughness. In addition, a wide defect related exciton band XD was found at about 1.93 eV in all aged monolayers. It is shown that the theory of localized excitons describes well the temperature dependence of peak position and halfwidth of the A-exciton band. The possible origin of nanocaps is also discussed.

  9. Surface induced magnetization reversal of MnP nanoclusters embedded in GaP

    Science.gov (United States)

    Lacroix, Christian; Lambert-Milot, Samuel; Desjardins, Patrick; Masut, Remo A.; Ménard, David

    2016-03-01

    We investigate the quasi-static magnetic behavior of ensembles of ferromagnetic nanoparticles consisting of MnP nanoclusters embedded in GaP(001) epilayers grown at 600, 650, and 700 °C. We use a phenomenological model, in which surface effects are included, to reproduce the experimental hysteresis curves measured as a function of temperature (120-260 K) and direction of the applied field. The slope of the hysteresis curve during magnetization reversal is determined by the MnP nanoclusters size distribution, which is a function of the growth temperature. Our results show that the coercive field is very sensitive to the strength of the surface anisotropy, which reduces the energy barrier between the two states of opposite magnetization. Notably, this reduction in the energy barrier increases by a factor of 3 as the sample temperature is lowered from 260 to 120 K.

  10. [Induced abortion--clinical problems, regulatory gaps, chaos. How much longer?].

    Science.gov (United States)

    Andreeva, A; Marinov, B; Tzankova, M

    2014-01-01

    Induced abortion is becoming more and more frequent in the contemporary clinical practice. Usually these are pregnant women with diagnosed foetal malformations. Most of them reach a final diagnose in the late second trimester and hence need a pregnancy termination at this gestational age. They are treated in accordance with The Artificial Pregnancy Termination Regulations and put on N 142 clinical-care pathway. The presentation describes the patients' journey form the diagnose through the induced abortion and to the discharge. Analyses the regulations, the multiple inaccuracies and striking omissions with regards to the procedure. Stimulates a discussion on the clinical problems and offers reasonable and realistic solutions.

  11. Retention of chimeric Tat2-Gap1 permease in the endoplasmic reticulum induces unfolded protein response in Saccharomyces cerevisiae.

    Science.gov (United States)

    Mochizuki, Takahiro; Kimata, Yukio; Uemura, Satoshi; Abe, Fumiyoshi

    2015-08-01

    In Saccharomyces cerevisiae, high-affinity tryptophan import is performed by subtle mechanisms involving tryptophan permease Tat2. We have shown that Tat2 requires 15 amino acid residues in the transmembrane domains (TMDs) for its import activity, whereas leucine permease Bap2 requires only seven corresponding residues for its leucine import. For this reason, the structure of Tat2 is elaborately designed to transport the hydrophobic and bulky tryptophan. Newly synthesized cell surface proteins first undergo endoplasmic reticulum (ER)-associated quality check before entering the secretory pathway. In this study, we used domain replacement with general amino acid permease Gap1 to show that Tat2 chimeric proteins were dysfunctional when TMD10 or TMD11 was replaced. These chimeras formed large 270-800-kDa protein complexes and were stably retained in the ER membrane without efficient degradation. In contrast, Tat2 chimeras of TMD9 or TMD12 retained some of their tryptophan import activity and underwent vacuolar degradation as observed with wild-type Tat2. Thus, ours results suggest that TMD10 and TMD11 are essential for the correct folding of Tat2, probably because of their interdomain interactions. Notably, overexpression of Tat2-Gap1 chimera of TMD10 activated the unfolded protein response (UPR) element-lacZ reporter, suggesting that ER retention of the protein aggregates induces the UPR.

  12. Controlling multi-wave mixing signals via photonic band gap of electromagnetically induced absorption grating in atomic media

    CERN Document Server

    Zhang, Yiqi; Yao, Xin; Zhang, Zhaoyang; Chen, Haixia; Zhang, Huaibin; Zhang, Yanpeng

    2013-01-01

    We experimentally demonstrate dressed multi-wave mixing (MWM) and the reflection of the probe beam due to electromagnetically induced absorption (EIA) grating can coexist in a five-level atomic ensemble. The reflection is derived from the photonic band gap (PBG) of EIA grating, which is much broader than the PBG of EIT grating. Therefore, EIA-type PBG can reflect more energy from probe than EIT-type PBG does, which can effectively affect the MWM signal. The EIA-type as well as EIT-type PBG can be controlled by multiple parameters including the frequency detunings, propagation angles and powers of the involved light fields. Also, the EIA-type PBG by considering both the linear and third-order nonlinear refractive indices is also investigated. The theoretical analysis agrees well with the experimental results. This investigation has potential applications in all-optical communication and information processing.

  13. Resistance modulation in VO2 nanowires induced by an electric field via air-gap gates

    Science.gov (United States)

    Kanki, Teruo; Chikanari, Masashi; Wei, Tingting; Tanaka, Hidekazu; The Institute of Scientific; Industrial Research Team

    Vanadium dioxide (VO2) shows huge resistance change with metal-insulator transition (MIT) at around room temperature. Controlling of the MIT by applying an electric field is a topical ongoing research toward the realization of Mott transistor. In this study, we have successfully switched channel resistance of VO2 nano-wire channels by a pure electrostatic field effect using a side-gate-type field-effect transistor (SG-FET) viaair gap and found that single crystalline VO2 nanowires and the channels with narrower width enhance transport modulation rate. The rate of change in resistance ((R0-R)/R, where R0 and R is the resistance of VO2 channel with off state and on state gate voltage (VG) , respectively) was 0.42 % at VG = 30 V in in-plane poly-crystalline VO2 channels on Al2O3(0001) substrates, while the rate in single crystalline channels on TiO2 (001) substrates was 3.84 %, which was 9 times higher than that using the poly-crystalline channels. With reducing wire width from 3000 nm to 400 nm of VO2 on TiO2 (001) substrate, furthermore, resistance modulation ratio enhanced from 0.67 % to 3.84 %. This change can not be explained by a simple free-electron model. In this presentation, we will compare the electronic properties between in-plane polycrystalline VO2 on Al2O3 (0001) and single crystalline VO2 on TiO2 (001) substrates, and show experimental data in detail..

  14. Optical anisotropy induced by mechanical strain around the fundamental gap of GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Ortega-Gallegos, J.; Lastras-Martinez, A.; Lastras-Martinez, L.F. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico); Balderas-Navarro, R.E. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico); Facultad de Ciencias, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico)

    2008-07-01

    We report on a theoretical-experimental study of reflectance anisotropy spectroscopy (RAS) of GaAs (001) crystals under uniaxial stress. The study was carried out in the energy region around the fundamental transition. RAS spectra in the energy range from 1.2-1.7 eV were measured with a photoelastic-modulator-based spectrometer. To induce an optical anisotropy, the GaAs crystals were thinned down to 400 {mu}m and an calibrated uniaxial stress was applied by deflection. RAS showed a line shape consisting of an oscillation at around E{sub 0}. On the basis of a perturbative approach employing the Pikus-Bir Hamiltonian, we calculated the RAS line shape and found a close agreement with the experimental spectra. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Cation-induced band-gap tuning in organohalide perovskites: interplay of spin-orbit coupling and octahedra tilting.

    Science.gov (United States)

    Amat, Anna; Mosconi, Edoardo; Ronca, Enrico; Quarti, Claudio; Umari, Paolo; Nazeeruddin, Md K; Grätzel, Michael; De Angelis, Filippo

    2014-06-11

    Organohalide lead perovskites have revolutionized the scenario of emerging photovoltaic technologies. The prototype MAPbI3 perovskite (MA = CH3NH3(+)) has dominated the field, despite only harvesting photons above 750 nm (∼1.6 eV). Intensive research efforts are being devoted to find new perovskites with red-shifted absorption onset, along with good charge transport properties. Recently, a new perovskite based on the formamidinium cation ((NH2)2CH(+) = FA) has shown potentially superior properties in terms of band gap and charge transport compared to MAPbI3. The results have been interpreted in terms of the cation size, with the larger FA cation expectedly delivering reduced band-gaps in Pb-based perovskites. To provide a full understanding of the interplay among size, structure, and organic/inorganic interactions in determining the properties of APbI3 perovskites, in view of designing new materials and fully exploiting them for solar cells applications, we report a fully first-principles investigation on APbI3 perovskites with A = Cs(+), MA, and FA. Our results evidence that the tetragonal-to-quasi cubic structural evolution observed when moving from MA to FA is due to the interplay of size effects and enhanced hydrogen bonding between the FA cations and the inorganic matrix altering the covalent/ionic character of Pb-I bonds. Most notably, the observed cation-induced structural variability promotes markedly different electronic and optical properties in the MAPbI3 and FAPbI3 perovskites, mediated by the different spin-orbit coupling, leading to improved charge transport and red-shifted absorption in FAPbI3 and in general in pseudocubic structures. Our theoretical model constitutes the basis for the rationale design of new and more efficient organohalide perovskites for solar cells applications.

  16. Proposed mode of action of benzene-induced leukemia: Interpreting available data and identifying critical data gaps for risk assessment.

    Science.gov (United States)

    Meek, M E Bette; Klaunig, James E

    2010-03-19

    Mode of action is defined as a series of key biological events leading to an observed toxicological effect (for example, metabolism to a toxic entity, cell death, regenerative repair and tumors). It contrasts with mechanism of action, which generally involves a detailed understanding of the molecular basis for an effect. A framework to consider the weight of evidence for hypothesized modes of action in animals and their relevance to humans, has been widely adopted and used by government agencies and international organizations. The framework, developed and refined through its application in case studies for principally non-DNA-reactive carcinogens, has more recently been extended to DNA-reactive carcinogens, non-cancer endpoints and different life stages. In addition to increasing transparency, use of the framework promotes consistency in decision-making concerning adequacy of weight of evidence, facilitates peer input and review and identifies critical research needs. The framework provides an effective tool to facilitate discussion between the research and risk assessment communities on critical data gaps, which if filled, would permit more refined estimates of risk. As a basis for additionally coordinating and focusing research on critical data gaps in a risk assessment context, five key events in the mode of action for benzene-induced leukemia are proposed: (1) benzene metabolism via Cytochrome P450, (2) the interaction of benzene metabolites with target cells in the bone marrow, (3) formation of initiated, mutated target cells, (4) selective proliferation of the mutated cells and (5) production of leukemia. These key events are considered in a framework analysis of human relevance as a basis to consider appropriate next steps in developing research strategies.

  17. Doping-Induced Change of Superconducting Gap Anisotropy in Bi_2Sr_2Ca_1Cu_2O8+δ

    Science.gov (United States)

    Kelley, R. J.; Quitmann, C.; Onellion, M.; Berger, H.; Almeras, P.; Margaritondo, G.

    1996-03-01

    High-resolution angle-resolved photoemission measurements were performed on single crystals of Bi_2Sr_2Ca_1Cu_2O8+δ with different oxygen stoichiometries. The data establish that the gap anisotropy (ratio of the gap along Gamma-M to the gap along Gamma-X) can be reversibly changed from ~20:1 (optimal or underdoped) to ~2:1 (overdoped). Differences in sample doping explain the conflicting reports on gap anisotropy in the literature. Possible effects of this change in gap anisotropy on the symmetry of the order parameter are discussed. There remains some ambiguity as to the relation between the order parameter and doping.

  18. Bi-induced band gap reduction in epitaxial InSbBi alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rajpalke, M. K.; Linhart, W. M.; Birkett, M.; Alaria, J.; Veal, T. D., E-mail: T.Veal@liverpool.ac.uk [Stephenson Institute for Renewable Energy and Department of Physics, School of Physical Sciences, University of Liverpool, Liverpool L69 7ZF (United Kingdom); Yu, K. M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Bomphrey, J. J.; Jones, T. S.; Ashwin, M. J., E-mail: M.J.Ashwin@warwick.ac.uk [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom); Sallis, S.; Piper, L. F. J. [Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States)

    2014-11-24

    The properties of molecular beam epitaxy-grown InSb{sub 1−x}Bi{sub x} alloys are investigated. Rutherford backscattering spectrometry shows that the Bi content increases from 0.6% for growth at 350 °C to 2.4% at 200 °C. X-ray diffraction indicates Bi-induced lattice dilation and suggests a zinc-blende InBi lattice parameter of 6.626 Å. Scanning electron microscopy reveals surface InSbBi nanostructures on the InSbBi films for the lowest growth temperatures, Bi droplets at intermediate temperatures, and smooth surfaces for the highest temperature. The room temperature optical absorption edge was found to change from 172 meV (7.2 μm) for InSb to ∼88 meV (14.1 μm) for InSb{sub 0.976}Bi{sub 0.024}, a reduction of ∼35 meV/%Bi.

  19. Effects of maturation-inducing hormone on heterologous gap junctional coupling in ovarian follicles of Atlantic croaker

    Science.gov (United States)

    Yoshizaki, G.; Patino, R.; Thomas, P.; Bolamba, D.; Chang, Xiaotian

    2001-01-01

    A previous ultrastructural study of heterologous (granulosa cell-oocyte) gap junction (GJ) contacts in ovarian follicles of Atlantic croaker suggested that these contacts disappear late during the process of resumption of oocyte meiosis. This observation suggested that, unlike scenarios proposed for a number of other species, uncoupling of GJ is not necessary for the onset of meiotic resumption in croaker follicles. However, the functionality of heterologous GJ contacts and the temporal association between maturation-inducing hormone (MIH)-induced changes in heterologous coupling and resumption of oocyte meiosis have not been examined in Atlantic croaker. These questions were addressed with a cell-cell coupling assay that is based on the transfer of a GJ marker, Lucifer Yellow, from oocytes to granulosa cells. Follicle-enclosed oocytes injected with Lucifer Yellow allowed transfer of the dye into the follicle cell layer, thus confirming that there is functional heterologous coupling between the oocyte and the granulosa cells. Dye transfer was observed in vitellogenic, full-grown/maturation-incompetent, and full-grown /maturation-competent follicles. Treatment of maturation-competent follicles with MIH caused a time-dependent decline in the number of follicles transferring dye. However, although GJ uncoupling in some of the follicles was observed before germinal vesicle breakdown (GVBD, index of meiotic resumption), about 50% of the follicles maintained the ability to transfer dye even after GVBD had occurred. Further, a known GJ inhibitor (phorbol 12-myristate 13-acetate) blocked heterologous GJ within a time frame similar to that seen with MIH but without inducing any of the morphological changes (including GVBD) associated with follicular maturation. In conclusion, uncoupling of heterologous GJ seems insufficient and unnecessary for the onset of meiotic resumption in ovarian follicles of Atlantic croaker. ?? 2001 Elsevier Science.

  20. Inhibition of gap junction intercellular communication is involved in silica nanoparticles-induced H9c2 cardiomyocytes apoptosis via the mitochondrial pathway.

    Science.gov (United States)

    Du, Zhong-Jun; Cui, Guan-Qun; Zhang, Juan; Liu, Xiao-Mei; Zhang, Zhi-Hu; Jia, Qiang; Ng, Jack C; Peng, Cheng; Bo, Cun-Xiang; Shao, Hua

    2017-01-01

    Gap junction intercellular communication (GJIC) between cardiomyocytes is essential for synchronous heart contraction and relies on connexin-containing channels. Connexin 43 (Cx43) is a major component involved in GJIC in heart tissue, and its abnormal expression is closely associated with various cardiac diseases. Silica nanoparticles (SNPs) are known to induce cardiovascular toxicity. However, the mechanisms through which GJIC plays a role in cardiomyocytes apoptosis induced by SNPs remain unknown. The aim of the present study is to determine whether SNPs-decreased GJIC promotes apoptosis in rat cardiomyocytes cell line (H9c2 cells) via the mitochondrial pathway using CCK-8 Kit, scrape-loading dye transfer technique, Annexin V/PI double-staining assays, and Western blot analysis. The results showed that SNPs elicited cytotoxicity in H9c2 cells in a time- and concentration-dependent manner. SNPs also reduced GJIC in H9c2 cells in a concentration-dependent manner through downregulation of Cx43 and upregulation of P-Cx43. Inhibition of gap junctions by gap junction blocker carbenoxolone disodium resulted in decreased survival and increased apoptosis, whereas enhancement of the gap junctions by retinoic acid led to enhanced survival but decreased apoptosis. Furthermore, SNPs-induced apoptosis through the disrupted functional gap junction was correlated with abnormal expressions of the proteins involved in the mitochondrial pathway-related apoptosis such as Bcl-2/Bax, cytochrome C, Caspase-9, and Caspase-3. Taken together, our results provide the first evidence that SNPs-decreased GJIC promotes apoptosis in cardiomyocytes via the mitochondrial pathway. In addition, downregulation of GJIC by SNPs in cardiomyocytes is mediated through downregulation of Cx43 and upregulation of P-Cx43. These results suggest that in rat cardiomyocytes cell line, GJIC plays a protective role in SNPs-induced apoptosis and that GJIC may be one of the targets for SNPs-induced biological

  1. Valence-band offsets and Schottky barrier heights of layered semiconductors explained by interface-induced gap states

    Science.gov (United States)

    Mönch, Winfried

    1998-04-01

    Many metal chalcogenides are layered semiconductors. They consist of chalcogen-metal-chalcogen layers that are themselves bound by van der Waals forces. Hence, heterostructures involving layered compounds are abrupt and strain-free. Experimental valence-band offsets of heterostructures between GaSe, InSe, SnS2, SnSe2, MoS2, MoTe2, WSe2, and CuInSe2 and between some of these compounds and ZnSe, CdS, and CdTe as well as barrier heights of Au contacts on GaSe, InSe, MoS2, MoTe2, WSe2, ZnSe, CdS, and CdTe are analyzed. The valence-band discontinuities of the heterostructures and the barrier heights of the Schottky contact compounds are consistently described by the continuum of interface-induced gap states as the primary mechanism that governs the band lineup at semiconductor interfaces.

  2. Gap Junctional Blockade Stochastically Induces Different Species-Specific Head Anatomies in Genetically Wild-Type Girardia dorotocephala Flatworms.

    Science.gov (United States)

    Emmons-Bell, Maya; Durant, Fallon; Hammelman, Jennifer; Bessonov, Nicholas; Volpert, Vitaly; Morokuma, Junji; Pinet, Kaylinnette; Adams, Dany S; Pietak, Alexis; Lobo, Daniel; Levin, Michael

    2015-11-24

    The shape of an animal body plan is constructed from protein components encoded by the genome. However, bioelectric networks composed of many cell types have their own intrinsic dynamics, and can drive distinct morphological outcomes during embryogenesis and regeneration. Planarian flatworms are a popular system for exploring body plan patterning due to their regenerative capacity, but despite considerable molecular information regarding stem cell differentiation and basic axial patterning, very little is known about how distinct head shapes are produced. Here, we show that after decapitation in G. dorotocephala, a transient perturbation of physiological connectivity among cells (using the gap junction blocker octanol) can result in regenerated heads with quite different shapes, stochastically matching other known species of planaria (S. mediterranea, D. japonica, and P. felina). We use morphometric analysis to quantify the ability of physiological network perturbations to induce different species-specific head shapes from the same genome. Moreover, we present a computational agent-based model of cell and physical dynamics during regeneration that quantitatively reproduces the observed shape changes. Morphological alterations induced in a genomically wild-type G. dorotocephala during regeneration include not only the shape of the head but also the morphology of the brain, the characteristic distribution of adult stem cells (neoblasts), and the bioelectric gradients of resting potential within the anterior tissues. Interestingly, the shape change is not permanent; after regeneration is complete, intact animals remodel back to G. dorotocephala-appropriate head shape within several weeks in a secondary phase of remodeling following initial complete regeneration. We present a conceptual model to guide future work to delineate the molecular mechanisms by which bioelectric networks stochastically select among a small set of discrete head morphologies. Taken together

  3. Gap Junctional Blockade Stochastically Induces Different Species-Specific Head Anatomies in Genetically Wild-Type Girardia dorotocephala Flatworms

    Directory of Open Access Journals (Sweden)

    Maya Emmons-Bell

    2015-11-01

    Full Text Available The shape of an animal body plan is constructed from protein components encoded by the genome. However, bioelectric networks composed of many cell types have their own intrinsic dynamics, and can drive distinct morphological outcomes during embryogenesis and regeneration. Planarian flatworms are a popular system for exploring body plan patterning due to their regenerative capacity, but despite considerable molecular information regarding stem cell differentiation and basic axial patterning, very little is known about how distinct head shapes are produced. Here, we show that after decapitation in G. dorotocephala, a transient perturbation of physiological connectivity among cells (using the gap junction blocker octanol can result in regenerated heads with quite different shapes, stochastically matching other known species of planaria (S. mediterranea, D. japonica, and P. felina. We use morphometric analysis to quantify the ability of physiological network perturbations to induce different species-specific head shapes from the same genome. Moreover, we present a computational agent-based model of cell and physical dynamics during regeneration that quantitatively reproduces the observed shape changes. Morphological alterations induced in a genomically wild-type G. dorotocephala during regeneration include not only the shape of the head but also the morphology of the brain, the characteristic distribution of adult stem cells (neoblasts, and the bioelectric gradients of resting potential within the anterior tissues. Interestingly, the shape change is not permanent; after regeneration is complete, intact animals remodel back to G. dorotocephala-appropriate head shape within several weeks in a secondary phase of remodeling following initial complete regeneration. We present a conceptual model to guide future work to delineate the molecular mechanisms by which bioelectric networks stochastically select among a small set of discrete head morphologies

  4. Impact of obesity on 7,12-dimethylbenz[a]anthracene-induced altered ovarian connexin gap junction proteins in female mice

    Energy Technology Data Exchange (ETDEWEB)

    Ganesan, Shanthi, E-mail: shanthig@iastate.edu; Nteeba, Jackson, E-mail: nteeba@iastate.edu; Keating, Aileen F., E-mail: akeating@iastate.edu

    2015-01-01

    The ovarian gap junction proteins alpha 4 (GJA4 or connexin 37; CX37), alpha 1 (GJA1 or connexin 43; CX43) and gamma 1 (GJC1 or connexin 45; CX45) are involved in cell communication and folliculogenesis. 7,12-dimethylbenz[a]anthracene (DMBA) alters Cx37 and Cx43 expression in cultured neonatal rat ovaries. Additionally, obesity has an additive effect on DMBA-induced ovarian cell death and follicle depletion, thus, we investigated in vivo impacts of obesity and DMBA on CX protein levels. Ovaries were collected from lean and obese mice aged 6, 12, 18, or 24 wks. A subset of 18 wk old mice (lean and obese) were dosed with sesame oil or DMBA (1 mg/kg; ip) for 14 days and ovaries collected 3 days thereafter. Cx43 and Cx45 mRNA and protein levels decreased (P < 0.05) after 18 wks while Cx37 mRNA and protein levels decreased (P < 0.05) after 24 wks in obese ovaries. Cx37 mRNA and antral follicle protein staining intensity were reduced (P < 0.05) by obesity while total CX37 protein was reduced (P < 0.05) in DMBA exposed obese ovaries. Cx43 mRNA and total protein levels were decreased (P < 0.05) by DMBA in both lean and obese ovaries while basal protein staining intensity was reduced (P < 0.05) in obese controls. Cx45 mRNA, total protein and protein staining intensity level were decreased (P < 0.05) by obesity. These data support that obesity temporally alters gap junction protein expression and that DMBA-induced ovotoxicity may involve reduced gap junction protein function. - Highlights: • Ovarian gap junction proteins are affected by ovarian aging and obesity. • DMBA exposure negatively impacts gap junction proteins. • Altered gap junction proteins may contribute to infertility.

  5. Improved laser-induced forward transfer of organic semiconductor thin films by reducing the environmental pressure and controlling the substrate-substrate gap width

    Energy Technology Data Exchange (ETDEWEB)

    Shaw-Stewart, James [Empa Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Functional Polymers, Duebendorf (Switzerland); Paul Scherrer Institut, Materials Group, General Energies Department, Villigen-PSI (Switzerland); Chu, Bryan; Maniglio, Ylenia; Nagel, Matthias; Nueesch, Frank [Empa Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Functional Polymers, Duebendorf (Switzerland); Lippert, Thomas; Wokaun, Alexander [Paul Scherrer Institut, Materials Group, General Energies Department, Villigen-PSI (Switzerland)

    2011-11-15

    Laser-induced forward transfer (LIFT) has been investigated for bilayer transfer material systems: silver/organic film (Alq{sub 3} or PFO). The LIFT process uses an intermediate dynamic release layer of a triazene polymer. This study focuses on the effect of introducing a controlled donor-receiver substrate gap distance and the effect of doing the transfer at reduced air pressures, whilst varying the fluence up to {proportional_to}200 mJ/cm{sup 2}. The gap between 'in-contact' substrates has been measured to be a minimum of 2-3 {mu}m. A linear variation in the gap width from 'in contact' to 40 {mu}m has been achieved by adding a spacer at one side of the substrate-substrate sandwich. At atmospheric pressure, very little transfer is achieved for Alq{sub 3}, although PFO shows some signs of successful doughnut transfer (with a large hole in the middle) in a narrow fluence range, at gaps greater than 20 {mu}m. For the transfer of Ag/PFO bilayers at atmospheric pressure, the addition of a PFO layer onto the receiver substrate improved the transfer enormously at smaller gaps and higher fluences. However, the best transfer results were obtained at reduced pressures where a 100% transfer success rate is obtained within a certain fluence window. The quality of the pixel morphology at less than 100 mbar is much higher than at atmospheric pressure, particularly when the gap width is less than 20 {mu}m. These results show the promise of LIFT for industrial deposition processes where a gap between the substrates will improve the throughput. (orig.)

  6. Involvement of gap junctional intercellular communication in the bystander effect induced by broad-beam or microbeam heavy ions

    Science.gov (United States)

    Shao, Chunlin; Furusawa, Yoshiya; Kobayashi, Yasuhiko; Funayama, Tomoo

    2006-09-01

    Most of the reported bystander responses were studied by using low dose irradiation of γ-rays and light ions such as alpha-particles. In this study, primary human fibroblasts AG1522 in confluent cultures were irradiated with either broad-beam of 100 keV/μm 12C or microbeams of 380 keV/μm 20Ne and 1260 keV/μm 40Ar. When cells were irradiated with 12C ions, the induction of micronucleus (MN) had a low-dose sensitive effect, i.e. a lower dose of irradiation gave a higher yield of MN per cell-traversal. This phenomenon was further reinforced by using a microbeam to irradiate a fraction of cells within a population. Even when only a single cell was targeted with one particle of 40Ar or 20Ne, the MN yield was increased to 1.4-fold of the non-irradiated control. When the number of microbeam targeted cells increased, the MN yield per targeted-cell decreased drastically. In addition, the bystander MN induction did not vary significantly with the number and the linear energy transfer (LET) of microbeam particles. When the culture was treated with PMA, an inhibitor of gap junctional intercellular communication (GJIC), MN induction was decreased for both microbeam and broad-beam irradiations even at high-doses where all cells were hit. The present findings indicate that a GJIC-mediated signaling amplification mechanism was involved in the high-LET heavy ion irradiation induced bystander effect. Moreover, at high-doses of radiation, the bystander signals could perform a complex interaction with direct irradiation.

  7. P190B RhoGAP overexpression in the developing mammary epithelium induces TGFβ-dependent fibroblast activation.

    Directory of Open Access Journals (Sweden)

    Melissa Gillette

    Full Text Available Rho GTPases mediate stromal-epithelial interactions that are important for mammary epithelial cell (MEC morphogenesis. Increased extracellular matrix (ECM deposition and reorganization affect MEC morphogenesis in a Rho GTPase-dependent manner. Although the effects of altered ECM on MEC morphogenesis have been described, how MECs regulate stromal deposition is not well understood. Previously, we showed that p190B RhoGAP overexpression disrupts mammary gland morphogenesis by inducing hyperbranching in association with stromal alterations. We therefore hypothesized that MEC overexpression of p190B regulates paracrine interactions to impact fibroblast activation. Using a combination of in vivo morphometric and immunohistochemical analyses and primary cell culture assays, we found that p190B overexpression in MECs activates fibroblasts leading to increased collagen, fibronectin, and laminin production and elevated expression of the collagen crosslinking enzyme lysyl oxidase. Phosphorylation of the TGF-β effector SMAD2 and expression of the TGF-β target gene αSma were increased in p190B-associated fibroblasts, suggesting that elevated TGF-β signaling promoted fibroblast activation. Mechanical tension and TGF-β cooperate to activate fibroblasts. Interestingly, active TGF-β was elevated in conditioned medium from p190B overexpressing MECs compared to control MECs, and p190B overexpressing MECs exhibited increased contractility in a collagen gel contraction assay. These data suggest that paracrine signaling from the p190B overexpressing MECs may activate TGF-β signaling in adjacent fibroblasts. In support of this, transfer of conditioned medium from p190B overexpressing MECs onto wildtype fibroblasts or co-culture of p190B overexpressing MECs with wildtype fibroblasts increased SMAD2 phosphorylation and mRNA expression of ECM genes in the fibroblasts when compared to fibroblasts treated with control CM or co-cultured with control MECs. The

  8. Inhibition of gap junction intercellular communication is involved in silica nanoparticles-induced H9c2 cardiomyocytes apoptosis via the mitochondrial pathway

    Directory of Open Access Journals (Sweden)

    Du ZJ

    2017-03-01

    Full Text Available Zhong-jun Du,1 Guan-qun Cui,2 Juan Zhang,1 Xiao-mei Liu,3 Zhi-hu Zhang,1 Qiang Jia,1 Jack C Ng,4 Cheng Peng,1,4 Cun-xiang Bo,1 Hua Shao1 1Department of Toxicology, Shandong Academy of Occupational Health and Occupational Medicine, Shandong Academy of Medical Sciences, 2Department of Respiratory Medicine, Qilu Children’s Hospital of Shandong University, Jinan, 3Department of Radiation Chemistry and Toxicology, School of Public Health, Jilin University, Changchun, People’s Republic of China; 4National Research Centre for Environmental Toxicology-Entox, The University of Queensland, Brisbane, QLD, Australia Abstract: Gap junction intercellular communication (GJIC between cardiomyocytes is essential for synchronous heart contraction and relies on connexin-containing channels. Connexin 43 (Cx43 is a major component involved in GJIC in heart tissue, and its abnormal expression is closely associated with various cardiac diseases. Silica nanoparticles (SNPs are known to induce cardiovascular toxicity. However, the mechanisms through which GJIC plays a role in cardiomyocytes apoptosis induced by SNPs remain unknown. The aim of the present study is to determine whether SNPs-decreased GJIC promotes apoptosis in rat cardiomyocytes cell line (H9c2 cells via the mitochondrial pathway using CCK-8 Kit, scrape-loading dye transfer technique, Annexin V/PI double-staining assays, and Western blot analysis. The results showed that SNPs elicited cytotoxicity in H9c2 cells in a time- and concentration-dependent manner. SNPs also reduced GJIC in H9c2 cells in a concentration-dependent manner through downregulation of Cx43 and upregulation of P-Cx43. Inhibition of gap junctions by gap junction blocker carbenoxolone disodium resulted in decreased survival and increased apoptosis, whereas enhancement of the gap junctions by retinoic acid led to enhanced survival but decreased apoptosis. Furthermore, SNPs-induced apoptosis through the disrupted functional gap junction

  9. Neutron diffraction study of the pressure-induced magnetic ordering in the spin gap system TlCuCl sub 3

    CERN Document Server

    Oosawa, A; Kakurai, K; Fujisawa, M; Tanaka, H

    2003-01-01

    Neutron elastic scattering measurements have been performed under a hydrostatic pressure in order to investigate the spin structure of the pressure-induced magnetic ordering in the spin gap system TlCuCl sub 3. Below the ordering temperature T sub N = 16.9 K for the hydrostatic pressure P = 1.48 GPa, magnetic Bragg reflections were observed at reciprocal lattice points Q = (h, 0, l) with integer h and odd l, which are equivalent to those points with the lowest magnetic excitation energy at ambient pressure. This indicates that the spin gap close due to the applied pressure. The spin structure of the pressure-induced magnetic ordered state for P = 1.48 GPa was determined. (author)

  10. Majorana modes in InSb nanowires (I): zero bias peaks in hybrid devices with low-disorder and hard induced superconducting gap

    Science.gov (United States)

    Gül, Ö.; Zhang, H.; de Moor, M. W. A.; de Vries, F.; van Veen, J.; van Woerkom, D. J.; Zuo, K.; Mourik, V.; Cassidy, M.; Geresdi, A.; Car, D.; Bakkers, E. P. A. M.; Goswami, S.; Watanabe, K.; Taniguchi, T.; Kouwenhoven, L. P.

    Majorana modes in hybrid superconductor-semiconductor nanowire devices can be probed via tunnelling spectroscopy which shows a zero bias peak (ZBP) in differential conductance (1). However, alternative mechanisms such as disorder or formation of quantum dots can also give rise to ZBPs, and obscure experimental studies of Majoranas. Further, a soft induced superconducting gap commonly observed in experiments presents an outstanding challenge for the demonstration of their topological protection. In this talk we show that with device improvements, we reach low-disorder transport regime with clear quantized conductance plateaus and Andreev enhancement approaching the theoretical limit. Tunnelling spectroscopy shows a hard induced superconducting gap and no formation of quantum dots. Together with extremely stable ZBPs observed in large gate voltage and magnetic field ranges, we exclude various alternative theories besides the formation of localized Majorana modes for our observations.

  11. Band gap opening in silicene on MgBr2(0001) induced by Li and Na

    KAUST Repository

    Zhu, Jiajie

    2014-11-12

    Silicene consists of a monolayer of Si atoms in a buckled honeycomb structure and is expected to be well compatible with the current Si-based technology. However, the band gap is strongly influenced by the substrate. In this context, the structural and electronic properties of silicene on MgBr2(0001) modified by Li and Na are investigated by first-principles calculations. Charge transfer from silicene (substrate) to substrate (silicene) is found for substitutional doping (intercalation). As compared to a band gap of 0.01 eV on the pristine substrate, strongly enhanced band gaps of 0.65 eV (substitutional doping) and 0.24 eV (intercalation) are achieved. The band gap increases with the dopant concentration.

  12. Knowledge Gaps

    DEFF Research Database (Denmark)

    Lyles, Marjorie; Pedersen, Torben; Petersen, Bent

    2003-01-01

    The study explores what factors influence the reduction of managers' perceivedknowledge gaps in the context of the environments of foreign markets. Potentialdeterminants are derived from traditional internationalization theory as well asorganizational learning theory, including the concept......, assimilating, and utilizing knowledge - are crucial determinants ofknowledge gap elimination. In contrast, the two factors deemed essential in traditionalinternationalization process theory - elapsed time of operations and experientiallearning - are found to have no or limited effect.Key words......: Internationalization, knowledge gap, absorptive capacity, learning box....

  13. Analytically determined topological phase diagram of the proximity-induced gap in diffusive n-terminal Josephson junctions

    Science.gov (United States)

    Amundsen, Morten; Ouassou, Jabir Ali; Linder, Jacob

    2017-01-01

    Multiterminal Josephson junctions have recently been proposed as a route to artificially mimic topological matter with the distinct advantage that its properties can be controlled via the superconducting phase difference, giving rise to Weyl points in 4-terminal geometries. A key goal is to accurately determine when the system makes a transition from a gapped to non-gapped state as a function of the phase differences in the system, the latter effectively playing the role of quasiparticle momenta in conventional topological matter. We here determine the proximity gap phase diagram of diffusive n-terminal Josephson junctions (), both numerically and analytically, by identifying a class of solutions to the Usadel equation at zero energy in the full proximity effect regime. We present an analytical equation which provides the phase diagram for an arbitrary number of terminals n. After briefly demonstrating the validity of the analytical approach in the previously studied 2- and 3-terminal cases, we focus on the 4-terminal case and map out the regimes where the electronic excitations in the system are gapped and non-gapped, respectively, demonstrating also in this case full agreement between the analytical and numerical approach.

  14. Role of Fe doping in tuning the band gap of TiO2 for the photo-oxidation-induced cytotoxicity paradigm.

    Science.gov (United States)

    George, Saji; Pokhrel, Suman; Ji, Zhaoxia; Henderson, Bryana L; Xia, Tian; Li, LinJiang; Zink, Jeffrey I; Nel, André E; Mädler, Lutz

    2011-07-27

    UV-light-induced electron-hole (e(-)/h(+)) pair generation with free radical production in TiO(2)-based nanoparticles is a major conceptual paradigm for biological injury. However, to date, this hypothesis has been difficult to experimentally verify due to the high energy of UV light that is intrinsically highly toxic to biological systems. Here, a versatile flame spray pyrolysis (FSP) synthetic process has been exploited to synthesize a library of iron-doped (0-10 wt%) TiO(2) nanoparticles. These particles have been tested for photoactivation-mediated cytotoxicity using near-visible light exposure. The reduction in TiO(2) band gap energy with incremental levels of Fe loading maintained the nanoparticle crystalline structure in spite of homogeneous Fe distribution (demonstrated by XRD, HRTEM, SAED, EFTEM, and EELS). Photochemical studies showed that band gap energy was reciprocally tuned proportional to the Fe content. The photo-oxidation capability of Fe-doped TiO(2) was found to increase during near-visible light exposure. Use of a macrophage cell line to evaluate cytotoxic and ROS production showed increased oxidant injury and cell death in parallel with a decrease in band gap energy. These findings demonstrate the importance of band gap energy in the phototoxic response of the cell to TiO(2) nanoparticles and reflect the potential of this material to generate adverse effects in humans and the environment during high-intensity light exposure.

  15. Experimental Investigation of the Effect of Radial Gap and Impeller Blade Exit on Flow-Induced Vibration at the Blade-Passing Frequency in a Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    A. Al-Qutub

    2009-01-01

    Full Text Available It has been recognized that the pressure pulsation excited by rotor-stator interaction in large pumps is strongly influenced by the radial gap between impeller and volute diffusers/tongues and the geometry of impeller blade at exit. This fluid-structure interaction phenomenon, as manifested by the pressure pulsation, is the main cause of flow-induced vibrations at the blade-passing frequency. In the present investigation, the effects of the radial gap and flow rate on pressure fluctuations, vibration, and pump performance are investigated experimentally for two different impeller designs. One impeller has a V-shaped cut at the blade's exit, while the second has a straight exit (without the V-cut. The experimental findings showed that the high vibrations at the blade-passing frequency are primarily raised by high pressure pulsation due to improper gap design. The existence of V-cut at blades exit produces lower pressure fluctuations inside the pump while maintaining nearly the same performance. The selection of proper radial gap for a given impeller-volute combination results in an appreciable reduction in vibration levels.

  16. Gap Resolution

    Energy Technology Data Exchange (ETDEWEB)

    2017-04-25

    Gap Resolution is a software package that was developed to improve Newbler genome assemblies by automating the closure of sequence gaps caused by repetitive regions in the DNA. This is done by performing the follow steps:1) Identify and distribute the data for each gap in sub-projects. 2) Assemble the data associated with each sub-project using a secondary assembler, such as Newbler or PGA. 3) Determine if any gaps are closed after reassembly, and either design fakes (consensus of closed gap) for those that closed or lab experiments for those that require additional data. The software requires as input a genome assembly produce by the Newbler assembler provided by Roche and 454 data containing paired-end reads.

  17. In-clustering induced anomalousbehavior of band gap in InAlN and InGaN

    DEFF Research Database (Denmark)

    Gorczyca, I.; Suski, T.; Christensen, Niels Egede

    2010-01-01

    that Indium clustering is the additional, large factor leading to the unusual bowings of the band gaps and their pressure coefficients. The theoretical results are compared with experimental data on variations of EG with In content. In the analysis of observed phenomena we point out the particular role......Electronic band structure calculations of In containing ternary nitride alloys are presented showing a strong modification of the band gap, EG and its pressure coefficient, dEG/dp, as a function of In-content. Two different arrangements of In atoms are considered: uniform and clustered. It is shown...

  18. Impact of obesity on 7,12-dimethylbenz[a]anthracene-induced altered ovarian connexin gap junction proteins in female mice.

    Science.gov (United States)

    Ganesan, Shanthi; Nteeba, Jackson; Keating, Aileen F

    2015-01-01

    The ovarian gap junction proteins alpha 4 (GJA4 or connexin 37; CX37), alpha 1 (GJA1 or connexin 43; CX43) and gamma 1 (GJC1 or connexin 45; CX45) are involved in cell communication and folliculogenesis. 7,12-dimethylbenz[a]anthracene (DMBA) alters Cx37 and Cx43 expression in cultured neonatal rat ovaries. Additionally, obesity has an additive effect on DMBA-induced ovarian cell death and follicle depletion, thus, we investigated in vivo impacts of obesity and DMBA on CX protein levels. Ovaries were collected from lean and obese mice aged 6, 12, 18, or 24 wks. A subset of 18 wk old mice (lean and obese) were dosed with sesame oil or DMBA (1mg/kg; ip) for 14days and ovaries collected 3days thereafter. Cx43 and Cx45 mRNA and protein levels decreased (Pobese ovaries. Cx37 mRNA and antral follicle protein staining intensity were reduced (Pobesity while total CX37 protein was reduced (Pobese ovaries. Cx43 mRNA and total protein levels were decreased (Pobese ovaries while basal protein staining intensity was reduced (Pobese controls. Cx45 mRNA, total protein and protein staining intensity level were decreased (Pobesity. These data support that obesity temporally alters gap junction protein expression and that DMBA-induced ovotoxicity may involve reduced gap junction protein function. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Protection of a ceramide synthase 2 null mouse from drug-induced liver injury: role of gap junction dysfunction and connexin 32 mislocalization.

    Science.gov (United States)

    Park, Woo-Jae; Park, Joo-Won; Erez-Roman, Racheli; Kogot-Levin, Aviram; Bame, Jessica R; Tirosh, Boaz; Saada, Ann; Merrill, Alfred H; Pewzner-Jung, Yael; Futerman, Anthony H

    2013-10-25

    Very long chain (C22-C24) ceramides are synthesized by ceramide synthase 2 (CerS2). A CerS2 null mouse displays hepatopathy because of depletion of C22-C24 ceramides, elevation of C16-ceramide, and/or elevation of sphinganine. Unexpectedly, CerS2 null mice were resistant to acetaminophen-induced hepatotoxicity. Although there were a number of biochemical changes in the liver, such as increased levels of glutathione and multiple drug-resistant protein 4, these effects are unlikely to account for the lack of acetaminophen toxicity. A number of other hepatotoxic agents, such as d-galactosamine, CCl4, and thioacetamide, were also ineffective in inducing liver damage. All of these drugs and chemicals require connexin (Cx) 32, a key gap junction protein, to induce hepatotoxicity. Cx32 was mislocalized to an intracellular location in hepatocytes from CerS2 null mice, which resulted in accelerated rates of its lysosomal degradation. This mislocalization resulted from the altered membrane properties of the CerS2 null mice, which was exemplified by the disruption of detergent-resistant membranes. The lack of acetaminophen toxicity and Cx32 mislocalization were reversed upon infection with recombinant adeno-associated virus expressing CerS2. We establish that Gap junction function is compromised upon altering the sphingolipid acyl chain length composition, which is of relevance for understanding the regulation of drug-induced liver injury.

  20. Gap Junctions

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2013-01-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031

  1. Gap junctions.

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2012-07-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1853-1872, 2012.

  2. Climate-induced yield variability and yield gaps of maize (Zea mays L.) in the Central Rift Valley of Ethiopia

    NARCIS (Netherlands)

    Kassie, B.T.; Ittersum, van M.K.; Hengsdijk, H.; Asseng, S.; Wolf, J.; Rotter, R.P.

    2014-01-01

    There is a high demand for quantitative information on impacts of climate on crop yields, yield gaps and their variability in Ethiopia, yet, quantitative studies that include an indication of uncertainties in the estimates are rare. A multi-model crop growth simulation approach using the two crop mo

  3. Indirect effects of emerald ash borer-induced ash mortality and canopy gap formation on epigaeic beetles.

    Science.gov (United States)

    Gandhi, Kamal J K; Smith, Annemarie; Hartzler, Diane M; Herms, Daniel A

    2014-06-01

    Exotic herbivorous insects have drastically and irreversibly altered forest structure and composition of North American forests. For example, emerald ash borer (Agrilus planipennis Fairmaire) from Asia has caused wide-scale mortality of ash trees (Fraxinus spp.) in eastern United States and Canada. We studied the effects of forest changes resulting from emerald ash borer invasion on epigaeic or ground beetles (Coleoptera: Carabidae) along a gradient of ash dieback and gap sizes in southeastern Michigan. Ground beetles were sampled in hydric, mesic, and xeric habitats in which black (Fraxinus nigra Marshall), green (Fraxinus pennsylvanica Marshall), and white (Fraxinus americana L.) ash were the most common species, respectively. During 2006-2007, we trapped 2,545 adult ground beetles comprising 52 species. There was a negative correlation between percent ash tree mortality in 2006 and catches of all beetles. Catches of Agonum melanarium Dejean (in 2006) and Pterostichus mutus (Say) (in 2006-2007) were negatively correlated with tree mortality and gap size, respectively. However, catches of Pterostichus corvinus Dejean were positively correlated with gap size in 2006. As ash mortality and average gap size increased from 2006 to 2007, catches of all beetles as well as P. mutus and Pterostichus stygicus (Say) increased (1.3-3.9 times), while species diversity decreased, especially in mesic and xeric stands. Cluster analysis revealed that beetle assemblages in hydric and mesic stand diverged (25 and 40%, respectively) in their composition from 2006 to 2007, and that hydric stands had the most unique beetle assemblages. Overall, epigaeic beetle assemblages were altered in ash stands impacted by emerald ash borer; however, these impacts may dissipate as canopy gaps close.

  4. Mythic gaps

    Directory of Open Access Journals (Sweden)

    William Hansen

    2014-11-01

    Full Text Available Different kinds of omissions sometimes occur, or are perceived to occur, in traditional narratives and in tradition-inspired literature. A familiar instance is when a narrator realizes that he or she does not fully remember the story that he or she has begun to tell, and so leaves out part of it, which for listeners may possibly result in an unintelligible narrative. But many instances of narrative gap are not so obvious. From straightforward, objective gaps one can distinguish less-obvious subjective gaps: in many cases narrators do not leave out anything crucial or truly relevant from their exposition, and yet readers perceive gaps and take steps to fill them. The present paper considers four examples of subjective gaps drawn from ancient Greek literature (the Pandora myth, ancient Roman literature (the Pygmalion legend, ancient Hebrew literature (the Joseph legend, and early Christian literature (the Jesus legend. I consider the quite varied ways in which interpreters expand the inherited texts of these stories, such as by devising names, manufacturing motives, creating backstories, and in general filling in biographical ellipses. Finally, I suggest an explanation for the phenomenon of subjective gaps, arguing that, despite their variety, they have a single cause.

  5. Gap-filling and bypass at the replication fork are both active mechanisms for tolerance of low-dose ultraviolet-induced DNA damage in the human genome.

    Science.gov (United States)

    Quinet, Annabel; Vessoni, Alexandre T; Rocha, Clarissa R R; Gottifredi, Vanesa; Biard, Denis; Sarasin, Alain; Menck, Carlos F M; Stary, Anne

    2014-02-01

    Ultraviolet (UV)-induced DNA damage are removed by nucleotide excision repair (NER) or can be tolerated by specialized translesion synthesis (TLS) polymerases, such as Polη. TLS may act at stalled replication forks or through an S-phase independent gap-filling mechanism. After UVC irradiation, Polη-deficient (XP-V) human cells were arrested in early S-phase and exhibited both single-strand DNA (ssDNA) and prolonged replication fork stalling, as detected by DNA fiber assay. In contrast, NER deficiency in XP-C cells caused no apparent defect in S-phase progression despite the accumulation of ssDNA and a G2-phase arrest. These data indicate that while Polη is essential for DNA synthesis at ongoing damaged replication forks, NER deficiency might unmask the involvement of tolerance pathway through a gap-filling mechanism. ATR knock down by siRNA or caffeine addition provoked increased cell death in both XP-V and XP-C cells exposed to low-dose of UVC, underscoring the involvement of ATR/Chk1 pathway in both DNA damage tolerance mechanisms. We generated a unique human cell line deficient in XPC and Polη proteins, which exhibited both S- and G2-phase arrest after UVC irradiation, consistent with both single deficiencies. In these XP-C/Polη(KD) cells, UVC-induced replicative intermediates may collapse into double-strand breaks, leading to cell death. In conclusion, both TLS at stalled replication forks and gap-filling are active mechanisms for the tolerance of UVC-induced DNA damage in human cells and the preference for one or another pathway depends on the cellular genotype. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Annealing-induced optical and sub-band-gap absorption parameters of Sn-doped CdSe thin films

    Science.gov (United States)

    Kaur, Jagdish; Tripathi, S. K.

    2016-01-01

    Thin films of Sn-doped CdSe were prepared by thermal evaporation onto glass substrates in an argon gas atmosphere and annealed at different temperatures. Structural evaluation of the films was carried out using X-ray diffraction and their stoichiometry studied by energy-dispersive X-ray analysis. The films exhibit a preferred orientation along the hexagonal direction of CdSe. The optical transmittance of the films shows a red shift of the absorption edge with annealing. The fundamental absorption edge corresponds to a direct energy gap with a temperature coefficient of 3.34 × 10-3 eV K-1. The refractive index, optical conductivity and real and imaginary parts of the dielectric constants were found to increase after annealing. The sub-band gap absorption coefficient was evaluated using the constant photocurrent method. It varies exponentially with photon energy. The Urbach energy, the density of defect states, and the steepness of the density of localized states were evaluated from the sub-band-gap absorption.

  7. Remaining gaps for "safe" CO2 storage: the INGV CO2GAPS vision of "learning by doing" monitoring geogas leakage, reservoirs contamination/mixing and induced/triggered seismicity

    Science.gov (United States)

    Quattrocchi, F.; Vinciguerra, S.; Chiarabba, C.; Boschi, E.; Anselmi, M.; Burrato, P.; Buttinelli, M.; Cantucci, B.; Cinti, D.; Galli, G.; Improta, L.; Nazzari, M.; Pischiutta, M.; Pizzino, L.; Procesi, M.; Rovelli, A.; Sciarra, A.; Voltattorni, N.

    2012-12-01

    The CO2GAPS project proposed by INGV is intended to build up an European Proposal for a new kind of research strategy in the field of the geogas storage. Aim of the project would be to fill such key GAPS concerning the main risks associated to CO2 storage and their implications on the entire Carbon Capture and Storage (CCS) process, which are: i) the geogas leakage both in soils and shallow aquifers, up to indoor seepage; ii) the reservoirs contamination/mixing by hydrocarbons and heavy metals; iii) induced or triggered seismicity and microseismicity, especially for seismogenic blind faults. In order to consider such risks and make the CCS public acceptance easier, a new kind of research approach should be performed by: i) a better multi-disciplinary and "site specific" risk assessment; ii) the development of more reliable multi-disciplinary monitoring protocols. In this view robust pre-injection base-lines (seismicity and degassing) as well as identification and discrimination criteria for potential anomalies are mandatory. CO2 injection dynamic modelling presently not consider reservoirs geomechanical properties during reactive mass-transport large scale simulations. Complex simulations of the contemporaneous physic-chemical processes involving CO2-rich plumes which move, react and help to crack the reservoir rocks are not totally performed. These activities should not be accomplished only by the oil-gas/electric companies, since the experienced know-how should be shared among the CCS industrial operators and research institutions, with the governments support and overview, also flanked by a transparent and "peer reviewed" scientific popularization process. In this context, a preliminary and reliable 3D modelling of the entire "storage complex" as defined by the European Directive 31/2009 is strictly necessary, taking into account the above mentioned geological, geochemical and geophysical risks. New scientific results could also highlighting such opportunities

  8. GAP Analysis Program (GAP) Raster

    Data.gov (United States)

    Kansas Data Access and Support Center — The Kansas GAP Land Cover database depicts 43 land cover classes for the state of Kansas. The database was generated using a two-stage hybrid classification of...

  9. Anion Gap Toxicity in Alloxan Induced Type 2 Diabetic Rats Treated with Antidiabetic Noncytotoxic Bioactive Compounds of Ethanolic Extract of Moringa oleifera

    Directory of Open Access Journals (Sweden)

    Maxwell Omabe

    2014-01-01

    Full Text Available Moringa oleifera (MO is used for a number of therapeutic purposes. This raises the question of safety and possible toxicity. The objective of the study was to ascertain the safety and possible metabolic toxicity in comparison with metformin, a known drug associated with acidosis. Animals confirmed with diabetes were grouped into 2 groups. The control group only received oral dose of PBS while the test group was treated with ethanolic extract of MO orally twice daily for 5-6 days. Data showed that the extract significantly lowered glucose level to normal values and did not cause any significant cytotoxicity compared to the control group (P=0.0698; there was no gain in weight between the MO treated and the control groups (P>0.8115. However, data showed that treatment with an ethanolic extract of MO caused a decrease in bicarbonate (P<0.0001, and more than twofold increase in anion gap (P<0.0001; metformin treatment also decreased bicarbonate (P<0.0001 and resulted in a threefold increase in anion gap (P<0.0001. Conclusively, these data show that while MO appears to have antidiabetic and noncytotoxic properties, it is associated with statistically significant anion gap acidosis in alloxan induced type 2 diabetic rats.

  10. Yield gap analysis and assessment of climate-induced yield trends of irrigated rice in selected provinces of the Philippines

    Directory of Open Access Journals (Sweden)

    Reiner Wassmann

    2012-04-01

    Full Text Available This study describes a combined empirical/modeling approach to assess the possible impact of climate variability on rice production in the Philippines. We collated climate data of the last two decades (1985-2002 as well as yield statistics of six provinces of the Philippines, selected along a North-South gradient. Data from the climate information system of NASA were used as input parameters of the model ORYZA2000 to determine potential yields and, in the next steps, the yield gaps defined as the difference between potential and actual yields. Both simulated and actual yields of irrigated rice varied strongly between years. However, no climate-driven trends were apparent and the variability in actual yields showed no correlation with climatic parameters. The observed variation in simulated yields was attributable to seasonal variations in climate (dry/wet season and to climatic differences between provinces and agro-ecological zones. The actual yield variation between provinces was not related to differences in the climatic yield potential but rather to soil and management factors. The resulting yield gap was largest in remote and infrastructurally disfavored provinces (low external input use with a high production potential (high solar radiation and day-night temperature differences. In turn, the yield gap was lowest in central provinces with good market access but with a relatively low climatic yield potential. We conclude that neither long-term trends nor the variability of the climate can explain current rice yield trends and that agroecological, seasonal, and management effects are over-riding any possible climatic variations. On the other hand the lack of a climate-driven trend in the present situation may be superseded by ongoing climate change in the future.

  11. Evidence of a Surface-Mediated Magnetically Induced Miscibility Gap in Co-Pt Alloy Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Rooney, P.W.; Shapiro, A.L.; Tran, M.Q.; Hellman, F. [Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States)

    1995-08-28

    (100) and (111) oriented single-crystal CoPt{sub 3} films were deposited over a range of growth temperatures from {minus}50 to 800 {degree}C. The Curie temperature is increased by 200 {degree}C over the value expected for the homogeneous alloy in the as-deposited films (of both orientations) grown near 400 {degree}C. We interpret this as evidence for a previously unobserved, surface-mediated, magnetically driven miscibility gap in vapor-deposited CoPt{sub 3} films. Large perpendicular magnetic anisotropy is also observed in the as-deposited films (of both orientations) grown near 400 {degree}C.

  12. Knowledge Gaps

    DEFF Research Database (Denmark)

    Lyles, Marjorie; Pedersen, Torben; Petersen, Bent

    2003-01-01

    of absorptive capacity. Building onthese literature streams a conceptual model is developed and tested on a set of primarydata of Danish firms and their foreign market operations. The empirical study suggeststhat the factors that pertain to the absorptive capacity concept - capabilities ofrecognizing......, assimilating, and utilizing knowledge - are crucial determinants ofknowledge gap elimination. In contrast, the two factors deemed essential in traditionalinternationalization process theory - elapsed time of operations and experientiallearning - are found to have no or limited effect.Key words......: Internationalization, knowledge gap, absorptive capacity, learning box....

  13. Induced changes in refractive index, optical band gap, and absorption edge of polycarbonate-SiO2 thin films by Vis-IR lasers

    Science.gov (United States)

    Ehsani, Hassan; Akhoondi, Somaieh

    2016-09-01

    In this experimental work, we have studied induced changes in refractive index, extinction coefficient, and optical band-gap of Bisphenol-A-polycarbonate (BPA-PC) coated with a uniform and thin, anti-scratch SiO2 film irradiated by visible to near-infrared lasers at 532 nm (green),650 nm(red), and 980 nm (IR)wavelength lasers with different energy densities. Our lasers sources are indium-gallium-aluminum-phosphide, second harmonic of neodymium-YAG-solid state lasers and gallium-aluminum-arsenide-semiconductor laser. The energy densities of our sources have been changed by changing the spot size of incident laser. samples transmission spectra were monitored by carry500 spectrophotometer and induced changes in optical properties are evaluated by using, extrapolation of the transmission spectrum through Swanepoel method and computer application

  14. High anion gap metabolic acidosis induced by cumulation of ketones, L- and D-lactate, 5-oxoproline and acute renal failure.

    Science.gov (United States)

    Heireman, Laura; Mahieu, Boris; Helbert, Mark; Uyttenbroeck, Wim; Stroobants, Jan; Piqueur, Marian

    2017-07-27

    Frequent causes of high anion gap metabolic acidosis (HAGMA) are lactic acidosis, ketoacidosis and impaired renal function. In this case report, a HAGMA caused by ketones, L- and D-lactate, acute renal failure as well as 5-oxoproline is discussed. A 69-year-old woman was admitted to the emergency department with lowered consciousness, hyperventilation, diarrhoea and vomiting. The patient had suffered uncontrolled type 2 diabetes mellitus, underwent gastric bypass surgery in the past and was chronically treated with high doses of paracetamol and fosfomycin. Urosepsis was diagnosed, whilst laboratory analysis of serum bicarbonate concentration and calculation of the anion gap indicated a  HAGMA. L-lactate, D-lactate, β-hydroxybutyric acid, acetone and 5-oxoproline serum levels were markedly elevated and renal function was impaired. We concluded that this case of HAGMA was induced by a variety of underlying conditions: sepsis, hyperglycaemia, prior gastric bypass surgery, decreased renal perfusion and paracetamol intake. Risk factors for 5-oxoproline intoxication present in this case are female gender, sepsis, impaired renal function and uncontrolled type 2 diabetes mellitus. Furthermore, chronic antibiotic treatment with fosfomycin might have played a role in the increased production of 5-oxoproline. Paracetamol-induced 5-oxoproline intoxication should be considered as a cause of HAGMA in patients with female gender, sepsis, impaired renal function or uncontrolled type 2 diabetes mellitus, even when other more obvious causes of HAGMA such as lactate, ketones or renal failure can be identified.

  15. Potassium Postdeposition Treatment-Induced Band Gap Widening at Cu(In,Ga)Se₂ Surfaces--Reason for Performance Leap?

    Science.gov (United States)

    Handick, Evelyn; Reinhard, Patrick; Alsmeier, Jan-Hendrik; Köhler, Leonard; Pianezzi, Fabian; Krause, Stefan; Gorgoi, Mihaela; Ikenaga, Eiji; Koch, Norbert; Wilks, Regan G; Buecheler, Stephan; Tiwari, Ayodhya N; Bär, Marcus

    2015-12-16

    Direct and inverse photoemission were used to study the impact of alkali fluoride postdeposition treatments on the chemical and electronic surface structure of Cu(In,Ga)Se2 (CIGSe) thin films used for high-efficiency flexible solar cells. We find a large surface band gap (E(g)(Surf), up to 2.52 eV) for a NaF/KF-postdeposition treated (PDT) absorber significantly increases compared to the CIGSe bulk band gap and to the Eg(Surf) of 1.61 eV found for an absorber treated with NaF only. Both the valence band maximum (VBM) and the conduction band minimum shift away from the Fermi level. Depth-dependent photoemission measurements reveal that the VBM decreases with increasing surface sensitivity for both samples; this effect is more pronounced for the NaF/KF-PDT CIGSe sample. The observed electronic structure changes can be linked to the recent breakthroughs in CIGSe device efficiencies.

  16. Unconventional Magnetism and Band Gap Formation in LiFePO4: Consequence of Polyanion Induced Non-planarity.

    Science.gov (United States)

    Jena, Ajit; Nanda, B R K

    2016-01-21

    Oxygen plays a critical role in strongly correlated transition metal oxides as crystal field effect is one of the key factors that determine the degree of localization of the valence d/f states. Based on the localization, a set of conventional mechanisms such as Mott-Hubbard, Charge-transfer and Slater were formulated to explain the antiferromagnetic and insulating (AFI) phenomena in many of these correlated systems. From the case study on LiFePO4, through density-functional calculations, we demonstrate that none of these mechanisms are strictly applicable to explain the AFI behavior when the transition metal oxides have polyanions such as (PO4)(3-). The symmetry-lowering of the metal-oxygen complex, to stabilize the polyanion, creates an asymmetric crystal field for d/f states. In LiFePO4 this field creates completely non-degenerate Fe-d states which, with negligible p-d and d-d covalent interactions, become atomically localized to ensure a gap at the Fermi level. Due to large exchange splitting, high spin state is favored and an antiferromagnetic configuration is stabilized. For the prototype LiFePO4, independent electron approximation is good enough to obtain the AFI ground state. Inclusion of additional correlation measures like Hubbard U simply amplifies the gap and therefore LiFePO4 can be preferably called as weakly coupled Mott insulator.

  17. Unconventional Magnetism and Band Gap Formation in LiFePO4: Consequence of Polyanion Induced Non-planarity

    Science.gov (United States)

    Jena, Ajit; Nanda, B. R. K.

    2016-01-01

    Oxygen plays a critical role in strongly correlated transition metal oxides as crystal field effect is one of the key factors that determine the degree of localization of the valence d/f states. Based on the localization, a set of conventional mechanisms such as Mott-Hubbard, Charge-transfer and Slater were formulated to explain the antiferromagnetic and insulating (AFI) phenomena in many of these correlated systems. From the case study on LiFePO4, through density-functional calculations, we demonstrate that none of these mechanisms are strictly applicable to explain the AFI behavior when the transition metal oxides have polyanions such as (PO4)3-. The symmetry-lowering of the metal-oxygen complex, to stabilize the polyanion, creates an asymmetric crystal field for d/f states. In LiFePO4 this field creates completely non-degenerate Fe-d states which, with negligible p-d and d-d covalent interactions, become atomically localized to ensure a gap at the Fermi level. Due to large exchange splitting, high spin state is favored and an antiferromagnetic configuration is stabilized. For the prototype LiFePO4, independent electron approximation is good enough to obtain the AFI ground state. Inclusion of additional correlation measures like Hubbard U simply amplifies the gap and therefore LiFePO4 can be preferably called as weakly coupled Mott insulator.

  18. Preliminary investigation into the simulation of a laser-induced plasma by means of a floating object in a spark gap

    CSIR Research Space (South Africa)

    West, NJ

    2007-08-01

    Full Text Available In this research, an orthogonally laser-triggered spark gap is investigated. The laser beam is directed in the region of a 30mm spark gap at 90 degrees to the gap and focused on the axis. The influence of plasma position within the spark gap...

  19. Water2Invest: Global facility for calculating investments needed to bridge the climate-induced water gap

    Science.gov (United States)

    Straatsma, Menno; Droogers, Peter; Brandsma, Jairus; Buytaert, Wouter; Karssenberg, Derek; Meijer, Karen; van Aalst, Maaike; van Beek, Rens; Wada, Yoshihide; Bierkens, Marc

    2013-04-01

    Decision makers responsible for climate change adaptation investments are confronted with large uncertainties regarding future water availability and water demand, as well as the investment cost required to reduce the water gap. Moreover, scientists have worked hard to increase fundamental knowledge on climate change and its impacts (climate services), while practical use of this knowledge is limited due to a lack of tools for decision support under uncertain long term future scenarios (decision services). The Water2Invest project aims are to (i) assess the joint impact of climate change and socioeconomic change on water scarcity, (ii) integrate impact and potential adaptation in one flow, (iii) prioritize adaptation options to counteract water scarcity on their financial, regional socio-economic and environmental implications, and (iv) deliver all this information in an integrated user-friendly web-based service. Global water availability is computed between 2006 and 2100 using the PCR-GLOBWB water resources model at a 6 minute spatial resolution. Climate change scenarios are based on the fifth Assessment Report (AR5) of the IPCC Coupled Model Intercomparison Project (CMIP5) that defines four CO2 emission scenarios as representative concentration pathways. Water demand is computed for agriculture, industry, domestic, and environmental requirements based on socio-economic scenarios of increase in population and gross domestic product. Using a linear programming algorithm, water is allocated on a monthly basis over the four sectors. Based on these assessments, the user can evaluate various technological and infrastructural adaptation measures to assess the investments needed to bridge the future water gap. Regional environmental and socioeconomic effects of these investments are evaluated, such as environmental flows or downstream effects. A scheme is developed to evaluate the strategies on robustness and flexibility under climate change and scenario uncertainty

  20. Growth concentration effect on oxygen vacancy induced band gap narrowing and optical CO gas sensing properties of ZnO nanorods

    Science.gov (United States)

    Tan, Chun Hui; Tan, Sin Tee; Lee, Hock Beng; Yap, Chi Chin; Yahaya, Muhammad

    2016-11-01

    Band gap energy and surface defect on the nanostructure play an important role especially in determining the performance and properties of the optical based gas sensor. In this report, ZnO nanorods (ZNRs) with various growth concentrations were successfully synthesized using a facile wet chemical approach. The gas sensing performance of the ZNRs samples with different concentrations were tested toward the highly hazardous carbon monoxide (CO) gas at a concentration of 10 ppm operated at room temperature. It was found that the 40 mM ZNRs sample exhibited the highest response coupled with the shortest response time (123.3 ± 1.3 s) and recovery time (7.7 ± 0.3 s). The high response and accelerated sensing reaction were attributed to the band gap narrowing of the 40 mM ZNRs induced by the increase in oxygen vacancy related defect states, and it is directly proportional to the CO gas sensing activity. These defects acted as the oxygen trap sites which will promote the oxygen adsorption on the surface of ZNRs and enhanced its gas sensing capability. The ZNRs reported herein which exhibits a high sensitivity, fast and reversible response with rapid recovery have great potential to be used in toxic gas sensing applications at room temperature.

  1. Minding the Cyber-Physical Gap: Model-Based Analysis and Mitigation of Systemic Perception-Induced Failure.

    Science.gov (United States)

    Mordecai, Yaniv; Dori, Dov

    2017-07-17

    The cyber-physical gap (CPG) is the difference between the 'real' state of the world and the way the system perceives it. This discrepancy often stems from the limitations of sensing and data collection technologies and capabilities, and is inevitable at some degree in any cyber-physical system (CPS). Ignoring or misrepresenting such limitations during system modeling, specification, design, and analysis can potentially result in systemic misconceptions, disrupted functionality and performance, system failure, severe damage, and potential detrimental impacts on the system and its environment. We propose CPG-Aware Modeling & Engineering (CPGAME), a conceptual model-based approach to capturing, explaining, and mitigating the CPG. CPGAME enhances the systems engineer's ability to cope with CPGs, mitigate them by design, and prevent erroneous decisions and actions. We demonstrate CPGAME by applying it for modeling and analysis of the 1979 Three Miles Island 2 nuclear accident, and show how its meltdown could be mitigated. We use ISO-19450:2015-Object Process Methodology as our conceptual modeling framework.

  2. Enhanced thermo-mechanical performance and strain-induced band gap reduction of TiO2@PVC nanocomposite films

    Indian Academy of Sciences (India)

    Mudassir Hasan; Arghya Narayan Banerjee; Moonyong Lee

    2015-04-01

    The present paper reports the fabrication of TiO2@PVC nanocomposites by incorporating TiO2 in polyvinyl chloride (PVC) followed by solution casting to prepare TiO2@PVC nanocomposite thin films. The asprepared TiO2@PVC nanocomposite films were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy, thermogravimetric analysis, optical spectroscopy and mechanical strength analyses. The TiO2@PVC nanocomposites were found to be thermally and mechanically more stable compared with pure PVC. The anatase TiO2 in the TiO2@PVC nanocomposite showed a lower indirect band gap compared with pure TiO2, which can be attributed to the strain within the nanocomposite, thereby affecting the band-structure of the nanocomposite. Significant enhancement in the mechanical properties of TiO2@PVC compared with pure PVC was observed with a 10 wt% TiO2 loading, such as a 50% increase in Young's modulus and almost 100% improvement in the tensile strength.

  3. Activation of L-type calcium channels is required for gap junction-mediated intercellular calcium signaling in osteoblastic cells

    DEFF Research Database (Denmark)

    Jørgensen, Niklas Rye; Teilmann, Stefan Cuoni; Henriksen, Zanne

    2003-01-01

    of extracellular calcium, plasma membrane depolarization by high extracellular potassium, and the L-type voltage-operated calcium channel inhibitor, nifedipine. In contrast, all these treatments enhanced the spread of P2 receptor-mediated ICW in UMR rat osteoblastic cells. Using UMR cells transfected to express Cx......43 (UMR/Cx43) we confirmed that nifedipine sensitivity of ICW required Cx43 expression. In human osteoblastic cells, gap junction-dependent ICW also required activation of L-type calcium channels and influx of extracellular calcium....

  4. A large gap opening of graphene induced by the adsorption of CO on the Al-doped site.

    Science.gov (United States)

    Peyghan, Ali Ahmadi; Noei, Maziar; Tabar, Mohammad Bigdeli

    2013-08-01

    We investigated CO adsorption on the pristine, Stone-Wales (SW) defected, Al- and Si- doped graphenes by using density functional calculations in terms of geometric, energetic and electronic properties. It was found that CO molecule is weakly adsorbed on the pristine and SW defected graphenes and their electronic properties were slightly changed. The Al- and Si- doped graphenes show high reactivity toward CO, so calculated adoption energies are about -11.40 and -13.75 kcal mol(-1) in the most favorable states. It was found that, among all the structures, the electronic properties of Al-doped graphene are strongly sensitive to the presence of CO molecule. We demonstrate the existence of a large Eg opening of 0.87 eV in graphene which is induced by Al-doping and CO adsorption.

  5. Red paprika (Capsicum annuum L.) and its main carotenoids, capsanthin and β-carotene, prevent hydrogen peroxide-induced inhibition of gap-junction intercellular communication.

    Science.gov (United States)

    Kim, Ji-Sun; Lee, Woo-Moon; Rhee, Han Cheol; Kim, Suna

    2016-07-25

    This study was conducted to investigate the protective effect of red paprika extract (RPE) and its main carotenoids, namely, capsanthin (CST) and β-carotene (BCT), on the H2O2-induced inhibition of gap-junction intercellular communication (GJIC) in WB-F344 rat liver epithelial cells (WB cells). We found that pre-treatment with RPE, CST and BCT protected WB cells from H2O2-induced inhibition of GJIC. RPE, CST and BCT not only recovered connexin 43 (Cx43) mRNA expression but also prevented phosphorylation of Cx43 protein by H2O2 treatment. RPE attenuated the phosphorylation of ERK, p38 and JNK, whereas pre-treatment with CST and BCT only attenuated the phosphorylation of ERK and p38 and did not affect JNK in H2O2-treated WB cells. RPE, CST and BCT significantly suppressed the formation of reactive oxygen species (ROS) in H2O2-treated cells compared to untreated WB cells. These results suggest that dietary intake of red paprika might be helpful for lowering the risk of diseases caused by oxidative stress.

  6. Changes in homologous and heterologous gap junction contacts during maturation-inducing hormone-dependent meiotic resumption in ovarian follicles of Atlantic croaker

    Science.gov (United States)

    Bolamba, D.; Patino, R.; Yoshizaki, G.; Thomas, P.

    2003-01-01

    Homologous (granulosa cell-granulosa cell) gap junction (GJ) contacts increase in ovarian follicles of Atlantic croaker (Micropogonias undulatus) during the early (first) stage of maturation, but their profile during the second stage [i.e., during maturation-inducing hormone (MIH)-mediated meiotic resumption] is unknown. The profile of homologous GJ contacts during the second stage of maturation in croaker follicles was examined in this study and compared to that of heterologous (granulosa cell-oocyte) GJ, for which changes have been previously documented. Follicles were incubated with human chorionic gonadotropin to induce maturational competence (first stage), and then with MIH to induce meiotic resumption. The follicles were collected for examination immediately before and after different durations of MIH exposure until the oocyte had reached the stage of germinal vesicle breakdown (GVBD; index of meiotic resumption). Ultrathin sections were observed by transmission electron microscopy, and homologous and heterologous GJ contacts were quantified along a 100-??m segment of granulosa cell-zona radiata complex per follicle (three follicles/time/fish, n=3 fish). Relatively high numbers of both types of GJ were observed before and after the first few hours of MIH exposure (up to the stage of oil droplet coalescence). GJ numbers declined during partial yolk globule coalescence (at or near GVBD) and were just under 50% of starting values after the completion of GVBD (Pobservations that GVBD temporally correlates with declining heterologous GJ contacts, and for the first time in teleosts show that there is a parallel decline in homologous GJ. The significance of the changes in homologous and heterologous GJ is uncertain and deserves further study. ?? 2003 Elsevier Science (USA). All rights reserved.

  7. Targeted overexpression of the neurite growth-associated protein B-50/GAP-43 in cerebellar Purkinje cells induces sprouting after axotomy but not axon regeneration into growth-permissive transplants

    NARCIS (Netherlands)

    Gispen, W.H.; Buffo, A.; Hoftmaat, A.J.; Savio, T.; Verbeek, J.S.; Oberdick, J.; Oestreicher, A.B.; Verhaagen, J.; Rossi, F.; Strata, P.

    1997-01-01

    B-50/GAP-43 is a nervous tissue-specific protein, the expression of which is associated with axon growth and regeneration. Its overexpression in transgenic mice produces spontaneous axonal sprouting and enhances induced remodeling in several neuron populations (; ). We examined the capacity of this

  8. A COMPARATIVE STUDY ON MANAGEMENT OF INFECTED GAP NONUNION WITH MASQUELET-2-STAGED INDUCED MEMBRANE TECHNIQUE VERSUS CONVENTIONAL DISTRACTION OSTEOSYNTHESIS

    Directory of Open Access Journals (Sweden)

    Satish Koti

    2016-07-01

    Full Text Available BACKGROUND Management of segmental long bone defects is a challenging task. Attempting limb reconstruction in the presence of significant bone loss usually involves surgery, which is technically difficult, time-consuming, physically and psychologically demanding for the patient, and with no guarantee of a satisfactory outcome. Amputation, external fixators, vascularised fibular grafts, acute limb shortening, and various quantities of allograft and autograft have historically been the mainstays of treatment. For the past 4 decades, Vascularised Fibular Grafting (VFG and distraction osteosynthesis with ring external factor (Ilizarov technique stood the test of time to become standard techniques for the management of large long bone defects. More recently, Masquelet described the use of a cement spacer placed within the osseous void followed by staged bone grafting within the induced biomembrane formed around the spacer as a potential treatment strategy to manage these large defects. The main aim of the study is to compare the efficacy of the two philosophically different methods, conventional distraction osteosynthesis, and Masquelet technique in the management of tibial bone defect incurred due to traumatic bone loss, traumatic fractures complicated by infection, and chronic osteomyelitis of tibia. METHOD Prospective observational study on male and female patients admitted in the Department of Orthopaedics in our tertiary level hospital from November 2012 to September 2014. All patients who have tibial bone defect incurred due to traumatic bone loss, traumatic fractures complicated by infection, and chronic osteomyelitis of tibia are included in the study. Children of age less than 5 years and elderly patients of age more than 85 years are excluded from the present study. Patients with tibial bone defects resulting from injury or surgical intervention are selected into the study and assigned either group D or group M. The patients in group D (n

  9. Phosphatidylcholine Specific PLC-Induced Dysregulation of Gap Junctions, a Robust Cellular Response to Environmental Toxicants, and Prevention by Resveratrol in a Rat Liver Cell Model.

    Directory of Open Access Journals (Sweden)

    Iva Sovadinova

    Full Text Available Dysregulation of gap junctional intercellular communication (GJIC has been associated with different pathologies, including cancer; however, molecular mechanisms regulating GJIC are not fully understood. Mitogen Activated Protein Kinase (MAPK-dependent mechanisms of GJIC-dysregulation have been well-established, however recent discoveries have implicated phosphatidylcholine-specific phospholipase C (PC-PLC in the regulation of GJIC. What is not known is how prevalent these two signaling mechanisms are in toxicant/toxin-induced dysregulation of GJIC, and do toxicants/toxins work through either signaling mechanisms or both, or through alternative signaling mechanisms. Different chemical toxicants were used to assess whether they dysregulate GJIC via MEK or PC-PLC, or both Mek and PC-PLC, or through other signaling pathways, using a pluripotent rat liver epithelial oval-cell line, WB-F344. Epidermal growth factor, 12-O-tetradecanoylphorbol-13-acetate, thrombin receptor activating peptide-6 and lindane regulated GJIC through a MEK1/2-dependent mechanism that was independent of PC-PLC; whereas PAHs, DDT, PCB 153, dicumylperoxide and perfluorodecanoic acid inhibited GJIC through PC-PLC independent of Mek. Dysregulation of GJIC by perfluorooctanoic acid and R59022 required both MEK1/2 and PC-PLC; while benzoylperoxide, arachidonic acid, 18β-glycyrrhetinic acid, perfluorooctane sulfonic acid, 1-monolaurin, pentachlorophenol and alachlor required neither MEK1/2 nor PC-PLC. Resveratrol prevented dysregulation of GJIC by toxicants that acted either through MEK1/2 or PC-PLC. Except for alachlor, resveratrol did not prevent dysregulation of GJIC by toxicants that worked through PC-PLC-independent and MEK1/2-independent pathways, which indicated at least two other, yet unidentified, pathways that are involved in the regulation of GJIC.the dysregulation of GJIC is a contributing factor to the cancer process; however the underlying mechanisms by which gap

  10. Phosphatidylcholine Specific PLC-Induced Dysregulation of Gap Junctions, a Robust Cellular Response to Environmental Toxicants, and Prevention by Resveratrol in a Rat Liver Cell Model.

    Science.gov (United States)

    Sovadinova, Iva; Babica, Pavel; Böke, Hatice; Kumar, Esha; Wilke, Andrew; Park, Joon-Suk; Trosko, James E; Upham, Brad L

    2015-01-01

    Dysregulation of gap junctional intercellular communication (GJIC) has been associated with different pathologies, including cancer; however, molecular mechanisms regulating GJIC are not fully understood. Mitogen Activated Protein Kinase (MAPK)-dependent mechanisms of GJIC-dysregulation have been well-established, however recent discoveries have implicated phosphatidylcholine-specific phospholipase C (PC-PLC) in the regulation of GJIC. What is not known is how prevalent these two signaling mechanisms are in toxicant/toxin-induced dysregulation of GJIC, and do toxicants/toxins work through either signaling mechanisms or both, or through alternative signaling mechanisms. Different chemical toxicants were used to assess whether they dysregulate GJIC via MEK or PC-PLC, or both Mek and PC-PLC, or through other signaling pathways, using a pluripotent rat liver epithelial oval-cell line, WB-F344. Epidermal growth factor, 12-O-tetradecanoylphorbol-13-acetate, thrombin receptor activating peptide-6 and lindane regulated GJIC through a MEK1/2-dependent mechanism that was independent of PC-PLC; whereas PAHs, DDT, PCB 153, dicumylperoxide and perfluorodecanoic acid inhibited GJIC through PC-PLC independent of Mek. Dysregulation of GJIC by perfluorooctanoic acid and R59022 required both MEK1/2 and PC-PLC; while benzoylperoxide, arachidonic acid, 18β-glycyrrhetinic acid, perfluorooctane sulfonic acid, 1-monolaurin, pentachlorophenol and alachlor required neither MEK1/2 nor PC-PLC. Resveratrol prevented dysregulation of GJIC by toxicants that acted either through MEK1/2 or PC-PLC. Except for alachlor, resveratrol did not prevent dysregulation of GJIC by toxicants that worked through PC-PLC-independent and MEK1/2-independent pathways, which indicated at least two other, yet unidentified, pathways that are involved in the regulation of GJIC. the dysregulation of GJIC is a contributing factor to the cancer process; however the underlying mechanisms by which gap junction channels

  11. Estimation of Bi induced changes in the direct E0 band gap of III-V-Bi alloys and comparison with experimental data

    Science.gov (United States)

    Samajdar, D. P.; Dhar, S.

    2016-03-01

    Quantum dielectric Theory (QDT) is used to explain the band gap bowing effect observed in III-V-Bismides such as InSb1-xBix, InAs1-xBix, InP1-xBix, GaSb1-xBix, GaAs1-xBix and GaP1-xBix. The dependence of the direct E0 band gap for these alloys on Bi mole fraction is calculated using QDT which requires the evaluation of the bowing parameter c. The bowing parameter gives the deviation of the direct E0 band gap from the linear relationship of E0 with Bi mole fraction. The band gap reduction values obtained using QDT are compared with those calculated using Virtual Crystal approximation (VCA) and Valence Band Anticrossing (VBAC) model as well as with the reported experimental data and the results of the comparison shows excellent agreement.

  12. Gap Junction Communication and the Propagation of Bystander Effects Induced by Microbeam Irradiation in Human Fibroblast Cultures: The Impact of Radiation Quality

    Science.gov (United States)

    Autsavapromporn, Narongchai; Suzuki, Masao; Funayama, Tomoo; Usami, Noriko; Plante, Ianik; Yokota, Yuichiro; Mutou, Yasuko; Ikeda, Hiroko; Kobayashi, Katsumi; Kobayashi, Yasuhiko; Uchihori, Yukio; Hei, Tom K.; Azzam, Edouard I.; Murakami, Takeshi

    2014-01-01

    Understanding the mechanisms underlying the bystander effects of low doses/low fluences of low- or high-linear energy transfer (LET) radiation is relevant to radiotherapy and radiation protection. Here, we investigated the role of gap-junction intercellular communication (GJIC) in the propagation of stressful effects in confluent normal human fibroblast cultures wherein only 0.036–0.144% of cells in the population were traversed by primary radiation tracks. Confluent cells were exposed to graded doses from monochromatic 5.35 keV X ray (LET ~6 keV/μm), 18.3 MeV/u carbon ion (LET ~103 keV/μm), 13 MeV/u neon ion (LET ~380 keV/μm) or 11.5 MeV/u argon ion (LET ~1,260 keV/μm) microbeams in the presence or absence of 18-α-glycyrrhetinic acid (AGA), an inhibitor of GJIC. After 4 h incubation at 37°C, the cells were subcultured and assayed for micronucleus (MN) formation. Micronuclei were induced in a greater fraction of cells than expected based on the fraction of cells targeted by primary radiation, and the effect occurred in a dose-dependent manner with any of the radiation sources. Interestingly, MN formation for the heavy-ion microbeam irradiation in the absence of AGA was higher than in its presence at high mean absorbed doses. In contrast, there were no significant differences in cell cultures exposed to X-ray microbeam irradiation in presence or absence of AGA. This showed that the inhibition of GJIC depressed the enhancement of MN formation in bystander cells from cultures exposed to high-LET radiation but not low-LET radiation. Bystander cells recipient of growth medium harvested from 5.35 keV X-irradiated cultures experienced stress manifested in the form of excess micronucleus formation. Together, the results support the involvement of both junctional communication and secreted factor(s) in the propagation of radiation-induced stress to bystander cells. They highlight the important role of radiation quality and dose in the observed effects. PMID:23987132

  13. Chiral gap effect in curved space

    CERN Document Server

    Flachi, Antonino

    2014-01-01

    We discuss a new type of QCD phenomenon induced in curved space. In the QCD vacuum a mass gap of Dirac fermions is attributed to the spontaneous breaking of chiral symmetry. If the curvature is positive large, the chiral condensate melts but a chiral invariant mass gap can still remain, which we name the chiral gap effect in curved space. This leads to decoupling of quark deconfinement which implies a view of black holes surrounded by a first-order QCD phase transition.

  14. Global ischemia-induced increases in the gap junctional proteins connexin 32 (Cx32) and Cx36 in hippocampus and enhanced vulnerability of Cx32 knock-out mice.

    Science.gov (United States)

    Oguro, K; Jover, T; Tanaka, H; Lin, Y; Kojima, T; Oguro, N; Grooms, S Y; Bennett, M V; Zukin, R S

    2001-10-01

    Gap junctions are conductive channels that connect the interiors of coupled cells. In the hippocampus, GABA-containing hippocampal interneurons are interconnected by gap junctions, which mediate electrical coupling and synchronous firing and thereby promote inhibitory transmission. The present study was undertaken to examine the hypothesis that the gap junctional proteins connexin 32 (Cx32; expressed by oligodendrocytes, interneurons, or both), Cx36 (expressed by interneurons), and Cx43 (expressed by astrocytes) play a role in defining cell-specific patterns of neuronal death in hippocampus after global ischemia in mice. Global ischemia did not significantly alter Cx32 and Cx36 mRNA expression and slightly increased Cx43 mRNA expression in the vulnerable CA1, as assessed by Northern blot analysis and in situ hybridization. Global ischemia induced a selective increase in Cx32 and Cx36 but not Cx43 protein abundance in CA1 before onset of neuronal death, as assessed by Western blot analysis. The increase in Cx32 and Cx36 expression was intense and specific to parvalbumin-positive inhibitory interneurons of CA1, as assessed by double immunofluorescence. Protein abundance was unchanged in CA3 and dentate gyrus. The finding of increase in connexin protein without increase in mRNA suggests regulation of Cx32 and Cx36 expression at the translational or post-translational level. Cx32(Y/-) null mice exhibited enhanced vulnerability to brief ischemic insults, consistent with a role for Cx32 gap junctions in neuronal survival. These findings suggest that Cx32 and Cx36 gap junctions may contribute to the survival and resistance of GABAergic interneurons, thereby defining cell-specific patterns of global ischemia-induced neuronal death.

  15. [Remodeling of cardiac gap junctions and arrhythmias].

    Science.gov (United States)

    Yu, Zhi-Bin; Sheng, Juan-Juan

    2011-12-25

    In the heart, gap junctions mediate electrical and chemical coupling between adjacent cardiomyocytes, forming the cell-to-cell pathways for orderly spread of the wave of electrical excitation responsible for a functional syncytium. Three principal connexins are expressed in cardiomyocytes, connexin 43 (CX43), CX40, and CX45. CX43 predominates in ventricular muscle cells. Most of the gap junctions, assembled from CX43, are located at the intercalated discs, often with larger junctional plaques at the disc periphery. The gap junctions are rarely distributed to the sides of the cardiomyocyte. The ischemia-reperfusion, cardiac hypertrophy, heart failure, hypercholesterolemia, and diabetes mellitus induce gap junction remodeling. The gap junction remodeling induced by above-mentioned diseases shows similar characteristics, including down-regulation of CX43, reduction in gap junction plaque size, increased heterogeneity and lateralization of gap junction distribution, and dephosphorylation of CX43. The elevated angiotensin II concentration in local myocardium may play an important role in the gap junction remodeling. The down-regulation of CX43 and lateralization of gap junction distribution alter anisotropic spread of the impulse of ventricular myocardium. The dephosphorylation of CX43 not only reduces electrical conductance, but also decreases permeability of chemicals between cardiomyocytes. The lateralization of gap junctions may increase the number of hemichannels formed by CX43. The opening of hemichannels induces ATP efflux and Na(+) influx, which forms a delayed after-depolarization. The gap junction remodeling in pathological condition produces arrhythmia substrate in the ventricles. In this review, the current knowledge on the relationship between the remodeling of cardiac gap junctions and arrhythmias were summarized.

  16. The Gap-Tpc

    Science.gov (United States)

    Rossi, B.; Anastasio, A.; Boiano, A.; Catalanotti, S.; Cocco, A. G.; Covone, G.; Di Meo, P.; Longo, G.; Vanzanella, A.; Walker, S.; Wang, H.; Wang, Y.; Fiorillo, G.

    2016-02-01

    Several experiments have been conducted worldwide, with the goal of observing low-energy nuclear recoils induced by WIMPs scattering off target nuclei in ultra-sensitive, low-background detectors. In the last few decades noble liquid detectors designed to search for dark matter in the form of WIMPs have been extremely successful in improving their sensitivities and setting the best limits. One of the crucial problems to be faced for the development of large size (multi ton-scale) liquid argon experiments is the lack of reliable and low background cryogenic PMTs: their intrinsic radioactivity, cost, and borderline performance at 87 K rule them out as a possible candidate for photosensors. We propose a brand new concept of liquid argon-based detector for direct dark matter search: the Geiger-mode Avalanche Photodiode Time Projection Chamber (GAP-TPC) optimized in terms of residual radioactivity of the photosensors, energy and spatial resolution, light and charge collection efficiency.

  17. The GAP-TPC

    CERN Document Server

    Rossi, B; Boiano, A; Catalanotti, S; Cocco, A G; Covone, G; Di Meo, P; Longo, G; Vanzanella, A; Walker, S; Wang, H; Wang, Y; Fiorillo, G

    2016-01-01

    Several experiments have been conducted worldwide, with the goal of observing low-energy nuclear recoils induced by WIMPs scattering off target nuclei in ultra-sensitive, low-background detectors. In the last few decades noble liquid detectors designed to search for dark matter in the form of WIMPs have been extremely successful in improving their sensitivities and setting the best limits. One of the crucial problems to be faced for the development of large size (multi ton-scale) liquid argon experiments is the lack of reliable and low background cryogenic PMTs: their intrinsic radioactivity, cost, and borderline performance at 87 K rule them out as a possible candidate for photosensors. We propose a brand new concept of liquid argon-based detector for direct dark matter search: the Geiger-mode Avalanche Photodiode Time Projection Chamber (GAP-TPC) optimized in terms of residual radioactivity of the photosensors, energy and spatial resolution, light and charge collection efficiency

  18. Involvement of a cytoplasmic glyceraldehyde-3-phosphate dehydrogenase GapC-2 in low-phosphate-induced anthocyanin accumulation in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    WANG XiYao; CHEN YiFang; ZOU JunJie; WU WeiHua

    2007-01-01

    Phosphorous is one of the essential mineral elements for plant growth and development. Typically,the shoots of plant seedlings usually turn a dark-brown or purple colour under low-Pi stress. Using protein 2-D gel and peptide mass fingerprinting mapping (PMF) methods,a cytoplasmic glyceraldehyde-3-phosphate dehydrogenase GapC-2 was identified as a low-Pi responsive protein in Arabidopsis plants. Expression of AtGapC-2 protein was significantly decreased after 4 d of low-Pi stress. Two independent T-DNA insertion lines of GapC-2 gene (At1g13440) showed a hypersensitive phenotype in response to low-Pi stress compared with wild type plants,while the transgenic complementation lines of the mutants showed a similar phenotype to the wild type. These results indicate that AtGapC-2 may play an important role in Arabidopsis responses to low-Pi stress,possibly by regulation of glycolysis-associated "Pi-pool" and accumulation of anthocyanin pigments in plants.

  19. Visualizing the gap closure by Rh dopant in SOC induced Mott insulator Sr2IrO4 with Scanning Tunneling Microscopy

    Science.gov (United States)

    Dai, Jixia; Calleja, Eduardo; McElroy, Kyle; Qi, Tongfei; Cao, Gang

    2013-03-01

    Sr2IrO4 is a novel Jeff = 1/2 Mott insulator with characteristics of 5d electrons. The strong spin orbit coupling (SOC) in the 5d orbitals of iridium plays an important role in the insulating nature of the parent compound, while replacing Ir4+ with the isoelectronic Rh4+ is able to drive the system to a metallic regime. We use variable temperature Scanning Tunneling Microscope to study both the insulating parent compound and the Rh doped Sr2Ir1-xRhxO4, with x =0.04, 0.11. By doing differential conductance measurement, we were able to observe an insulating gap both in the parent compound and the low doping areas of the x =0.04 and 0.11 samples. We also observed that in the doped samples, local gaps varies largely at the atomic length scale. By correlating the locations of Rh dopant and the size of local gaps, we found that Rh doping will decrease the insulating gap size which is in accordance with the metallic behavior observed by transport measurements.

  20. Protein-Energy Malnutrition Developing after Global Brain Ischemia Induces an Atypical Acute-Phase Response and Hinders Expression of GAP-43: e107570

    National Research Council Canada - National Science Library

    Shari E Smith; Sarah A Figley; David J Schreyer; Phyllis G Paterson

    2014-01-01

      Protein-energy malnutrition (PEM) is a common post-stroke problem. PEM can independently induce a systemic acute-phase response, and pre-existing malnutrition can exacerbate neuroinflammation induced by brain ischemia...

  1. Protein-energy malnutrition developing after global brain ischemia induces an atypical acute-phase response and hinders expression of GAP-43

    National Research Council Canada - National Science Library

    Smith, Shari E; Figley, Sarah A; Schreyer, David J; Paterson, Phyllis G

    2014-01-01

    Protein-energy malnutrition (PEM) is a common post-stroke problem. PEM can independently induce a systemic acute-phase response, and pre-existing malnutrition can exacerbate neuroinflammation induced by brain ischemia...

  2. Aggregation of BiTe monolayer on Bi2Te3 (111) induced by diffusion of intercalated atoms in the van der Waals gap

    Science.gov (United States)

    Wang, Zhi-Wen; Huang, Wen-Kai; Zhang, Kai-Wen; Shu, Da-Jun; Wang, Mu; Li, Shao-Chun

    2017-03-01

    We report a postgrowth aging mechanism of Bi2Te3 (111) films with scanning tunneling microscopy in combination with density functional theory calculation. It is found that a monolayered structure with a squared lattice symmetry gradually aggregates from the surface steps. Theoretical calculations indicate that the van der Waals (vdW) gap not only acts as a natural reservoir for self-intercalated Bi and Te atoms, but also provides them easy diffusion pathways. Once hopping out of the gap, these defective atoms prefer to develop into a two-dimensional BiTe superstructure on the Bi2Te3 (111) surface driven by positive energy gain. Considering the common nature of weak bonding between vdW layers, we expect such unusual diffusion and aggregation of the intercalated atoms may be of general importance for most kinds of vdW layered materials.

  3. Towards smaller gap microbulks

    CERN Document Server

    Attié, D.; Dafni, T; Ferrer-Ribas, E.; Ferrer-Ribas, E; Ferry, S; Giomataris, Y; Herrera, D C; Iguaz, F J; Irastorza, I G; Kebbiri, M; Papaevangelou, T; de Oliveira, R; Seguí, L; Tomás, A

    2014-01-01

    Small gap Micromegas detectors ( < 50 μm) are expected to be optimal for high pressure applications. Combining the microbulk manufacturing technique with a small gap can result in attractive detectors for rare event detection, in particular double beta decay or dark matter searches. We present novel results obtained with small gap microbulks (25 and 12.5 μm) that have been manufactured recently. For the first time for this type of detectors, we show experimentally that for each amplification gap there is an optimal pressure and that smaller gaps are more suitable for higher pressures.

  4. Gap junctional communication modulates gene transcription by altering the recruitment of Sp1 and Sp3 to connexin-response elements in osteoblast promoters

    Science.gov (United States)

    Stains, Joseph P.; Lecanda, Fernando; Screen, Joanne; Towler, Dwight A.; Civitelli, Roberto

    2003-01-01

    Loss-of-function mutations of gap junction proteins, connexins, represent a mechanism of disease in a variety of tissues. We have shown that recessive (gene deletion) or dominant (connexin45 overexpression) disruption of connexin43 function results in osteoblast dysfunction and abnormal expression of osteoblast genes, including down-regulation of osteocalcin transcription. To elucidate the molecular mechanisms of gap junction-sensitive transcriptional regulation, we systematically analyzed the rat osteocalcin promoter for sensitivity to gap junctional intercellular communication. We identified an Sp1/Sp3 containing complex that assembles on a minimal element in the -70 to -57 region of the osteocalcin promoter in a gap junction-dependent manner. This CT-rich connexin-response element is necessary and sufficient to confer gap junction sensitivity to the osteocalcin proximal promoter. Repression of osteocalcin transcription occurs as a result of displacement of the stimulatory Sp1 by the inhibitory Sp3 on the promoter when gap junctional communication is perturbed. Modulation of Sp1/Sp3 recruitment also occurs on the collagen Ialpha1 promoter and translates into gap junction-sensitive transcriptional control of collagen Ialpha1 gene expression. Thus, regulation of Sp1/Sp3 recruitment to the promoter may represent a potential general mechanism for transcriptional control of target genes by signals passing through gap junctions.

  5. Efficient H{sub 2} production over Au/graphene/TiO{sub 2} induced by surface plasmon resonance of Au and band-gap excitation of TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yang; Yu, Hongtao [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Wang, Hua, E-mail: wanghua@dlou.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); School of Fisheries and Life Science, Dalian Ocean University, Dalian 116023 (China); Chen, Shuo [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Quan, Xie, E-mail: quanxie@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China)

    2014-11-15

    Highlights: • Both surface plasmon resonance and band-gap excitation were used for H{sub 2} production. • Au/Gr/TiO{sub 2} composite photocatalyst was synthesized. • Au/Gr/TiO{sub 2} exhibited enhancement of light absorption and charge separation. • H{sub 2} production rate of Au/Gr/TiO{sub 2} was about 2 times as high as that of Au/TiO{sub 2}. - Abstract: H{sub 2} production over Au/Gr/TiO{sub 2} composite photocatalyst induced by surface plasmon resonance of Au and band-gap excitation of TiO{sub 2} using graphene (Gr) as an electron acceptor has been investigated. Electron paramagnetic resonance study indicated that, in this composite, Gr collected electrons not only from Au with surface plasmon resonance but also from TiO{sub 2} with band-gap excitation. Surface photovoltage and UV–vis absorption measurements revealed that compared with Au/TiO{sub 2}, Au/Gr/TiO{sub 2} displayed more effective photogenerated charge separation and higher optical absorption. Benefiting from these advantages, the H{sub 2} production rate of Au/Gr/TiO{sub 2} composite with Gr content of 1.0 wt% and Au content of 2.0 wt% was about 2 times as high as that of Au/TiO{sub 2}. This work represents an important step toward the efficient application of both surface plasmon resonance and band-gap excitation on the way to converting solar light into chemical energy.

  6. Disorder-induced gap in the normal density of states of the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br.

    Science.gov (United States)

    Diehl, Sandra; Methfessel, Torsten; Tutsch, Ulrich; Müller, Jens; Lang, Michael; Huth, Michael; Jourdan, Martin; Elmers, Hans-Joachim

    2015-07-01

    The local density of states (DOS) of the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br, measured by scanning tunneling spectroscopy on in situ cleaved surfaces, reveals a logarithmic suppression near the Fermi edge persisting above the critical temperature T(c). The experimentally observed suppression of the DOS is in excellent agreement with a soft Hubbard gap as predicted by the Anderson-Hubbard model for systems with disorder. The electronic disorder also explains the diminished coherence peaks of the quasi-particle DOS below T(c).

  7. Direct evidence for a pressure-induced nodal superconducting gap in the Ba0.65Rb0.35Fe2As2 superconductor

    Science.gov (United States)

    Guguchia, Z.; Amato, A.; Kang, J.; Luetkens, H.; Biswas, P. K.; Prando, G.; von Rohr, F.; Bukowski, Z.; Shengelaya, A.; Keller, H.; Morenzoni, E.; Fernandes, Rafael M.; Khasanov, R.

    2015-01-01

    The superconducting gap structure in iron-based high-temperature superconductors (Fe-HTSs) is non-universal. In contrast to other unconventional superconductors, in the Fe-HTSs both d-wave and extended s-wave pairing symmetries are close in energy. Probing the proximity between these very different superconducting states and identifying experimental parameters that can tune them is of central interest. Here we report high-pressure muon spin rotation experiments on the temperature-dependent magnetic penetration depth in the optimally doped nodeless s-wave Fe-HTS Ba0.65Rb0.35Fe2As2. Upon pressure, a strong decrease of the penetration depth in the zero-temperature limit is observed, while the superconducting transition temperature remains nearly constant. More importantly, the low-temperature behaviour of the inverse-squared magnetic penetration depth, which is a direct measure of the superfluid density, changes qualitatively from an exponential saturation at zero pressure to a linear-in-temperature behaviour at higher pressures, indicating that hydrostatic pressure promotes the appearance of nodes in the superconducting gap. PMID:26548650

  8. Effect of compressive stress inducing a band gap narrowing on the photoinduced activities of sol-gel TiO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Ghazzal, Mohamed N., E-mail: mohamed.ghazzal@uclouvain.be [Laboratoire de Chimie et Methodologie pour l' Evironnement, Universite Paul Verlaine de Metz, rue Victor Demange, 57500 Saint-Avold (France); Institute of Condensed Matter and Nanoscience Molecules, Solids and reacTivity (IMCN/MOST), Universite catholique de Louvain, Croix du Sud 2/17, B-1348 Louvain-la-Neuve (Belgium); Chaoui, N. [Laboratoire de Spectrometrie de Masse et de Chimie Laser, Universite Paul Verlaine de Metz, Boulvard arago, F-57078 Metz Cedex 3 (France); Genet, M. [Institute of Condensed Matter and Nanoscience Molecules, Division of Bio and Soft Matter (IMCN/BSMA), Universite catholique de Louvain, Croix du Sud 2/17, B-1348 Louvain-la-Neuve (Belgium); Gaigneaux, Eric M. [Institute of Condensed Matter and Nanoscience Molecules, Solids and reacTivity (IMCN/MOST), Universite catholique de Louvain, Croix du Sud 2/17, B-1348 Louvain-la-Neuve (Belgium); Robert, D. [Laboratoire des Materiaux, Surface et Procedes pour la Catalyse (LMSPC) CNRS-UMR7515, Antenne de Saint-Avold, UPV-Metz, Rue Victor Demange 57500 Saint-Avold (France)

    2011-11-30

    TiO{sub 2} thin films grown on different kinds of substrates were obtained by sol-gel process. X-ray diffraction revealed that the TiO{sub 2} lattice parameter c decreased continuously, indicating a continuous variation in the compressive stress, a negligible compressive stress of the film grown onto Soda-Lime Glass (SLG), medium compressive stress of the film grown onto BoroSilicate Glass (BSG) and large compressive stress of the film deposited onto the Quartz Substrate (QS). UV-Vis absorbance spectra exhibited a red-shift of the absorbance edge of the TiO{sub 2} films suggesting a lowering of the band gap, which is a direct consequence of the increase of the compressive stress. X-ray photoelectron spectroscopy revealed that the surface composition of titania films was similar except for sodium-ion concentration. The rate observed during the photo-oxydation of the stearic acid on TiO{sub 2}/QS was twice as high as that of TiO{sub 2}/BSG and about 1000 times superior to that of TiO{sub 2}/SLG. The photoinduced wettability shows an identical dependence of the compressive stress. According to these results, the compressive stress could be used to tune the band gap of the titanium oxide in order to enhance the photoinduced properties.

  9. In situ synthesis of porous array films on a filament induced micro-gap electrode pair and their use as resistance-type gas sensors with enhanced performances.

    Science.gov (United States)

    Xu, Zongke; Duan, Guotao; Zhang, Hongwen; Wang, Yingying; Xu, Lei; Cai, Weiping

    2015-09-14

    Resistance-type metal-oxide semiconductor gas sensors with high sensitivity and low detection limit have been explored for practical applications. They require both sensing films with high sensitivity to target gases and an appropriate structure of the electrode-equipped substrate to support the sensing films, which is still challenging. In this paper, a new gas sensor of metal-oxide porous array films on a micro-gap electrode pair is designed and implemented by taking ZnO as a model material. First, a micro-gap electrode pair was constructed by sputtering deposition on a filament template, which was used as the sensor's supporting substrate. Then, the sensing film, made up of ZnO porous periodic arrays, was in situ synthesized onto the supporting substrate by a solution-dipping colloidal lithography strategy. The results demonstrated the validity of the strategy, and the as-designed sensor shows a small device-resistance, an enhanced sensing performance with high resolution and an ultralow detection limit. This work provides an alternative method to promote the practical application of resistance-type gas sensors.

  10. Hosting of surface states in spin-orbit induced projected bulk band gaps of W(1 1 0) and Ir(1 1 1)

    Science.gov (United States)

    Elmers, H. J.; Kutnyakhov, D.; Chernov, S. V.; Medjanik, K.; Fedchenko, O.; Zaporozhchenko-Zymakova, A.; Ellguth, M.; Tusche, C.; Viefhaus, J.; Schönhense, G.

    2017-06-01

    Spin-momentum locking of surface states has attracted great interest in recent years due to envisioned technological applications in the field of spintronics. Normal metal surfaces like W(1 1 0) and Ir(1 1 1) show surface states with energy dispersions and spin-polarization textures, which are reminiscent of topologically non-trivial surface states. In order to understand this phenomenon the connection of bulk and surface states has to be explored. Using time-of-flight momentum microscopy with soft x-ray excitation, we present a comprehensive analysis of the bulk bands of W and Ir. Surface states are determined by the same method with photon excitation in the vacuum ultraviolet region. The superposition of both spectral densities reveals the hosting of surface states within the gap structure of bulk bands projected on the surface Brillouin zone. Quantitative differences in the extension of experimental and theoretical local band gaps indicate an underestimation of electron correlation effects in theory.

  11. Bridging the Gap

    OpenAIRE

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska; Murdock, Karen; Schmidt, Iben Julie

    2015-01-01

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures. Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ve...

  12. Bridging the Gap

    DEFF Research Database (Denmark)

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska;

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures.......Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures....

  13. Gap and density theorems

    CERN Document Server

    Levinson, N

    1940-01-01

    A typical gap theorem of the type discussed in the book deals with a set of exponential functions { \\{e^{{{i\\lambda}_n} x}\\} } on an interval of the real line and explores the conditions under which this set generates the entire L_2 space on this interval. A typical gap theorem deals with functions f on the real line such that many Fourier coefficients of f vanish. The main goal of this book is to investigate relations between density and gap theorems and to study various cases where these theorems hold. The author also shows that density- and gap-type theorems are related to various propertie

  14. Band-gap engineering by molecular mechanical strain-induced giant tuning of the luminescence in colloidal amorphous porous silicon nanostructures

    KAUST Repository

    Mughal, Asad Jahangir

    2014-01-01

    Nano-silicon is a nanostructured material in which quantum or spatial confinement is the origin of the material\\'s luminescence. When nano-silicon is broken into colloidal crystalline nanoparticles, its luminescence can be tuned across the visible spectrum only when the sizes of the nanoparticles, which are obtained via painstaking filtration methods that are difficult to scale up because of low yield, vary. Bright and tunable colloidal amorphous porous silicon nanostructures have not yet been reported. In this letter, we report on a 100 nm modulation in the emission of freestanding colloidal amorphous porous silicon nanostructures via band-gap engineering. The mechanism responsible for this tunable modulation, which is independent of the size of the individual particles and their distribution, is the distortion of the molecular orbitals by a strained silicon-silicon bond angle. This mechanism is also responsible for the amorphous-to-crystalline transformation of silicon. This journal is

  15. Bridging the climate-induced water gap in the twenty-first century: adaptation support based on water supply, demand, adaptation and financing.

    Science.gov (United States)

    Straatsma, Menno; Droogers, Peter; Brandsma, Jaïrus; Buytaert, Wouter; Karssenberg, Derek; Van Beek, Rens; Wada, Yoshihide; Sutanudjaja, Edwin; Vitolo, Claudia; Schmitz, Oliver; Meijer, Karen; Van Aalst, Maaike; Bierkens, Marc

    2014-05-01

    Water scarcity affects large parts of the world. Over the course of the twenty-first century, water demand is likely to increase due to population growth and associated food production, and increased economic activity, while water supply is projected to decrease in many regions due to climate change. Despite recent studies that analyze the effect of climate change on water scarcity, e.g. using climate projections under representative concentration pathways (RCP) of the fifth assessment report of the IPCC (AR5), decision support for closing the water gap between now and 2100 does not exist at a meaningful scale and with a global coverage. In this study, we aimed (i) to assess the joint impact of climatic and socio-economic change on water scarcity, (ii) to integrate impact and potential adaptation in one workflow, (iii) to prioritize adaptation options to counteract water scarcity based on their financial, regional socio-economic and environmental implications, and (iv) to deliver all this information in an integrated user-friendly web-based service. To enable the combination of global coverage with local relevance, we aggregated all results for 1604 water provinces (food producing units) delineated in this study, which is five times smaller than previous food producing units. Water supply was computed using the PCR-GLOBWB hydrological and water resources model, parameterized at 5 arcminutes for the whole globe, excluding Antarctica and Greenland. We ran PCR-GLOBWB with a daily forcing derived from five different GCM models from the CMIP5 (GFDL-ESM2M, Hadgem2-ES, IPSL-CMA5-LR, MIROC-ESM-CHEM, NorESM1-M) that were bias corrected using observation-based WATCH data between 1960-1999. For each of the models all four RCPs (RCP 2.6, 4.5, 6.0, and 8.5) were run, producing the ensemble of 20 future projections. The blue water supply was aggregated per month and per water province. Industrial, domestic and irrigation water demands were computed for a limited number of

  16. Band-gap engineering by molecular mechanical strain-induced giant tuning of the luminescence in colloidal amorphous porous silicon nanostructures.

    Science.gov (United States)

    Mughal, A; El Demellawi, J K; Chaieb, Sahraoui

    2014-12-14

    Nano-silicon is a nanostructured material in which quantum or spatial confinement is the origin of the material's luminescence. When nano-silicon is broken into colloidal crystalline nanoparticles, its luminescence can be tuned across the visible spectrum only when the sizes of the nanoparticles, which are obtained via painstaking filtration methods that are difficult to scale up because of low yield, vary. Bright and tunable colloidal amorphous porous silicon nanostructures have not yet been reported. In this letter, we report on a 100 nm modulation in the emission of freestanding colloidal amorphous porous silicon nanostructures via band-gap engineering. The mechanism responsible for this tunable modulation, which is independent of the size of the individual particles and their distribution, is the distortion of the molecular orbitals by a strained silicon-silicon bond angle. This mechanism is also responsible for the amorphous-to-crystalline transformation of silicon.

  17. Annealing induced electrical conduction and band gap variation in thermally reduced graphene oxide films with different sp{sup 2}/sp{sup 3} fraction

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mukesh [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Yadav, Asha [Centre for Energy, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Kumar, Shailendra [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Agarwal, Pratima, E-mail: pratima@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Centre for Energy, Indian Institute of Technology Guwahati, Guwahati 781039 (India)

    2015-01-30

    Highlights: • Controllable electrical properties of GO from insulator to semimetal behavior with different reduction temperatures. • High conductivity ∼40 S/cm for GO reduced at 400 °C. • Tunable band gap of GO with different reduction temperatures. • A systematic decrease the fraction of sp{sup 3} as compared to sp{sup 2} with increase in reduction temperature. - Abstract: Temperature dependent electrical conductivity of as prepared and thermally reduced graphene oxide (GO) thin films was measured in the range 300–520 K. As prepared GO films show very low conductivity ∼6.8 × 10{sup −6} S/cm at 300 K, which increases slowly till 370 K. A sharp increase in conductivity is observed in the temperature range 370–440 K, beyond which conductivity is thermally activated with activation energy 0.26 eV. Reduced GO films show an increase in conductivity at 300 K with increase in reduction temperature. GO films reduced at 400 °C exhibit high conductivity ∼40 S/cm at 300 K, with very low activation energy 0.05 eV in the measured temperature range 300–520 K. The increase in conductivity after thermal reduction is due to an increase in the ratio sp{sup 2}/sp{sup 3} bonded carbon atoms. The band gap of as prepared GO is 3.20 eV and it is decreased by approximately 0.4 eV in the case of thermally reduced GO at 400 °C in comparison to as prepared GO.

  18. Bridging a Cultural Gap

    Science.gov (United States)

    Leviatan, Talma

    2008-01-01

    There has been a broad wave of change in tertiary calculus courses in the past decade. However, the much-needed change in tertiary pre-calculus programmes--aimed at bridging the gap between high-school mathematics and tertiary mathematics--is happening at a far slower pace. Following a discussion on the nature of the gap and the objectives of a…

  19. Senseless Extravagance, Shocking Gaps

    Science.gov (United States)

    Weissbourd, Richard; Dodge, Trevor

    2012-01-01

    Although most people in the United States believe, at least theoretically, in educational equality, fewer and fewer appear to care about the resource gaps between affluent and poor schools, says Weissbourd. He illustrates these gaps with vivid descriptions of what he calls an "opulence arms race" among affluent independent schools, but…

  20. Bridge the Gap

    DEFF Research Database (Denmark)

    Marselis, Randi Lorenz

    2017-01-01

    This article focuses on photo projects organised for teenage refugees by the Society for Humanistic Photography (Berlin, Germany). These projects, named Bridge the Gap I (2015), and Bridge the Gap II (2016), were carried out in Berlin and brought together teenagers with refugee and German...

  1. Optimized measurement of gaps

    Science.gov (United States)

    Harding, Kevin; Ramamurthy, Rajesh

    2017-05-01

    Gaps are important in a wide range of measurements in manufacturing, from the fitting of critical assemblies too cosmetic features on cars. There are a variety of potential sensors that can measure a gap opening, each with aspects of gap measurements that they do well and other aspects where the technology may lack capability. This paper provides a review of a wide range of optical gages from structured light to passive systems and from line to area measurement. Each technology is considered relative to the ability to accurately measure a gap, including issues of edge effects, edge shape, surface finish, and transparency. Finally, an approach will be presented for creating an optimize measurement off gap openings for critical assembly applications.

  2. Band gap expansion, shear inversion phase change behaviour and low-voltage induced crystal oscillation in low-dimensional tin selenide crystals.

    Science.gov (United States)

    Carter, Robin; Suyetin, Mikhail; Lister, Samantha; Dyson, M Adam; Trewhitt, Harrison; Goel, Sanam; Liu, Zheng; Suenaga, Kazu; Giusca, Cristina; Kashtiban, Reza J; Hutchison, John L; Dore, John C; Bell, Gavin R; Bichoutskaia, Elena; Sloan, Jeremy

    2014-05-28

    In common with rocksalt-type alkali halide phases and also semiconductors such as GeTe and SnTe, SnSe forms all-surface two atom-thick low dimensional crystals when encapsulated within single walled nanotubes (SWNTs) with diameters below ∼1.4 nm. Whereas previous density functional theory (DFT) studies indicate that optimised low-dimensional trigonal HgTe changes from a semi-metal to a semi-conductor, low-dimensional SnSe crystals typically undergo band-gap expansion. In slightly wider diameter SWNTs (∼1.4-1.6 nm), we observe that three atom thick low dimensional SnSe crystals undergo a previously unobserved form of a shear inversion phase change resulting in two discrete strain states in a section of curved nanotube. Under low-voltage (i.e. 80-100 kV) imaging conditions in a transmission electron microscope, encapsulated SnSe crystals undergo longitudinal and rotational oscillations, possibly as a result of the increase in the inelastic scattering cross-section of the sample at those voltages.

  3. Modelling Gender Pay Gaps

    OpenAIRE

    2004-01-01

    EXECUTIVE SUMMARYIntroductionThere has been little change in the full-time gender pay gap since the mid 1990s andin the female part-time/male full-time pay gap since the mid 1970s. The gender gapin hourly earnings for those employed full-time in Britain in 2003 was 18 per cent,while that between women working part-time and men working full-time was 40 percent.This research uses statistical methods to identify how much of the gender pay gap isassociated with different factors. The data set ana...

  4. Filling the Income Gap

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Income distribution has become one of the people's main concerns in China where more than 30years of reform and opening up have also resulted in an ever-expanding wealth gap.But narrowing down the rich-poor disparity will prove to be no easy task.Wei Zhong,a researcher with the Institute of Economics under the Chinese Academy of Social Sciences,elaborated on the origins and trends of China's widening income gap,and discussed solutions to curb the gap,in a recent article.Edited excerpts follow:

  5. Bridging The Inferential Gap

    Science.gov (United States)

    Stewart, Walter F.; Shah, Nirav R.; Selna, Mark J.; Paulus, Ronald A.; Walker, James M.

    2009-01-01

    Most clinical decisions involve bridging the inferential gap: Clinicians are required to “fill in” where they lack knowledge or where no knowledge yet exists. In this context we consider how the inferential gap is a product, in part, of how knowledge is created, the limits to gaining access to such knowledge, and the variable ways in which knowledge is translated into decisions. We consider how electronic health records (EHRs) will help narrow this gap by accelerating the creation of evidence relevant to everyday practice needs and facilitating real-time use of knowledge in practice. PMID:17259202

  6. Small-Gap Flows

    Science.gov (United States)

    1984-04-01

    34’OF CALIFORNIA# BERKELEY, CA 5.1720 ft (45 642-141 SMALL- GAP FLOWS BY E. 0. TUCK REPORT No. NAUE 84-1 CONTRACT N00014-84-K-OU26 APRIL i984...Mechanics, 41 (1970) 769-792. 11 3. Shallow-Water Waves at Discontinuities Shallow-water waves represent perhaps the prototype small- gap flow , the...solving (4.4) we need "initial" conditions at the starting station z = 0, and "exit" conditions at the station z = L where the gap flow merges with the

  7. Gap junction intercellular communication and benzene toxicity.

    Science.gov (United States)

    Rivedal, Edgar; Witz, Gisela; Leithe, Edward

    2010-03-19

    Aberrant regulation of gap junction intercellular communication (GJIC) has been linked to several human diseases, including cancer and abnormal hematopoietic development. Benzene exposure has been shown to cause hematotoxicity and leukemia, but the underlying mechanisms involved remain unclear. We have observed that several metabolites of benzene have the ability to block gap junction intercellular communication. The ring-opened trans,trans-muconaldehyde (MUC) was found to be the most potent inhibitor of gap junction channels. MUC was found to induce cross-linking of the gap junction protein connexin43, which seemed to be responsible for the induced inhibition of GJIC. Glutaraldehyde, which has a similar molecular structure as MUC, was found to possess similar effects on gap junctions as MUC, while the mono-aldehyde formaldehyde shows lower potency, both as a connexin cross-linker, and as an inhibitor of GJIC. Both glutaraldehyde and formaldehyde have previously been associated with induction of leukemia and disturbance of hematopoiesis. Taken together, the data support a possible link between the effect of MUC on gap junctions, and the toxic effects of benzene. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

  8. Filling the Income Gap

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Income distribution has become one of the people’s main concerns in China where more than 30 years of reform and opening up have also resulted in an ever-expanding wealth gap. But narrowing down the

  9. Protein-energy malnutrition developing after global brain ischemia induces an atypical acute-phase response and hinders expression of GAP-43.

    Directory of Open Access Journals (Sweden)

    Shari E Smith

    Full Text Available Protein-energy malnutrition (PEM is a common post-stroke problem. PEM can independently induce a systemic acute-phase response, and pre-existing malnutrition can exacerbate neuroinflammation induced by brain ischemia. In contrast, the effects of PEM developing in the post-ischemic period have not been studied. Since excessive inflammation can impede brain remodeling, we investigated the effects of post-ischemic malnutrition on neuroinflammation, the acute-phase reaction, and neuroplasticity-related proteins. Male, Sprague-Dawley rats were exposed to global forebrain ischemia using the 2-vessel occlusion model or sham surgery. The sham rats were assigned to control diet (18% protein on day 3 after surgery, whereas the rats exposed to global ischemia were assigned to either control diet or a low protein (PEM, 2% protein diet. Post-ischemic PEM decreased growth associated protein-43, synaptophysin and synaptosomal-associated protein-25 immunofluorescence within the hippocampal CA3 mossy fiber terminals on day 21, whereas the glial response in the hippocampal CA1 and CA3 subregions was unaltered by PEM. No systemic acute-phase reaction attributable to global ischemia was detected in control diet-fed rats, as reflected by serum concentrations of alpha-2-macroglobulin, alpha-1-acid glycoprotein, haptoglobin, and albumin. Acute exposure to the PEM regimen after global brain ischemia caused an atypical acute-phase response. PEM decreased the serum concentrations of albumin and haptoglobin on day 5, with the decreases sustained to day 21. Serum alpha-2-macroglobulin concentrations were significantly higher in malnourished rats on day 21. This provides the first direct evidence that PEM developing after brain ischemia exerts wide-ranging effects on mechanisms important to stroke recovery.

  10. Protein-energy malnutrition developing after global brain ischemia induces an atypical acute-phase response and hinders expression of GAP-43.

    Science.gov (United States)

    Smith, Shari E; Figley, Sarah A; Schreyer, David J; Paterson, Phyllis G

    2014-01-01

    Protein-energy malnutrition (PEM) is a common post-stroke problem. PEM can independently induce a systemic acute-phase response, and pre-existing malnutrition can exacerbate neuroinflammation induced by brain ischemia. In contrast, the effects of PEM developing in the post-ischemic period have not been studied. Since excessive inflammation can impede brain remodeling, we investigated the effects of post-ischemic malnutrition on neuroinflammation, the acute-phase reaction, and neuroplasticity-related proteins. Male, Sprague-Dawley rats were exposed to global forebrain ischemia using the 2-vessel occlusion model or sham surgery. The sham rats were assigned to control diet (18% protein) on day 3 after surgery, whereas the rats exposed to global ischemia were assigned to either control diet or a low protein (PEM, 2% protein) diet. Post-ischemic PEM decreased growth associated protein-43, synaptophysin and synaptosomal-associated protein-25 immunofluorescence within the hippocampal CA3 mossy fiber terminals on day 21, whereas the glial response in the hippocampal CA1 and CA3 subregions was unaltered by PEM. No systemic acute-phase reaction attributable to global ischemia was detected in control diet-fed rats, as reflected by serum concentrations of alpha-2-macroglobulin, alpha-1-acid glycoprotein, haptoglobin, and albumin. Acute exposure to the PEM regimen after global brain ischemia caused an atypical acute-phase response. PEM decreased the serum concentrations of albumin and haptoglobin on day 5, with the decreases sustained to day 21. Serum alpha-2-macroglobulin concentrations were significantly higher in malnourished rats on day 21. This provides the first direct evidence that PEM developing after brain ischemia exerts wide-ranging effects on mechanisms important to stroke recovery.

  11. Semantic Gaps Are Dangerous

    DEFF Research Database (Denmark)

    Ejstrup, Michael; le Fevre Jakobsen, Bjarne

    Semantic gaps are dangerous Language adapts to the environment where it serves as a tool to communication. Language is a social agreement, and we all have to stick to both grammaticalized and non-grammaticalized rules in order to pass information about the world around us. As such language develops...... unpolite language and tend to create dangerous relations where specialy language creates problems and trouble that could be avoided if we had better language tools at hand. But we have not these tools of communication, and we are in a situation today where media and specially digital and social media......, supported by new possibilities of migration, create dangerous situations. How can we avoid these accidental gaps in language and specially the gaps in semantic and metaphoric tools. Do we have to keep silent and stop discusing certain isues, or do we have other ways to get acces to sufficient language tools...

  12. Gap Cycling for SWIFT

    CERN Document Server

    Corum, Curtis A; Snyder, Carl J; Garwood, Michael

    2013-01-01

    Purpose: SWIFT (SWeep Imaging with Fourier Transformation) is a non- Cartesian MRI method with unique features and capabilities. In SWIFT, radiofrequency (RF) excitation and reception are performed nearly simultaneously, by rapidly switching between transmit and receive during a frequency-swept RF pulse. Because both the transmitted pulse and data acquisition are simultaneously amplitude-modulated in SWIFT (in contrast to continuous RF excitation and uninterrupted data acquisition in more familiar MRI sequences), crosstalk between different frequency bands occurs in the data. This crosstalk leads to a "bulls-eye" artifact in SWIFT images. We present a method to cancel this inter-band crosstalk by cycling the pulse and receive gap positions relative to the un-gapped pulse shape. We call this strategy "gap cycling." Methods: We carry out theoretical analysis, simulation and experiments to characterize the signal chain, resulting artifacts, and their elimination for SWIFT. Results: Theoretical analysis reveals t...

  13. Missing the gap

    DEFF Research Database (Denmark)

    Tanggaard, Lene; Glaveanu, Vlad Petre

    creative learning at the borders need not minimize differences, but handle and learn from them? If not, schools and educational institutions risk becoming bad copies of the labour marked instead of enabling students to enter the market with something new, something radically dissimilar from what......Missing the gap This paper is focused on an exploration of creative learning involved in boundary crossing (Tanggaard, 2007). Our aim is to explore the trajectories and pathways realised by students as they move from education to work and vice versa (Tanggaard & Beghetto, 2015), guided...... by the premise that difference and gaps are places where creative learning is intensified (Glaveanu & Gillespie, 2015). The public discourse around education is often concerned with minding or avoiding the gap by making education more relevant for or similar to the labour market, but what if facilitating...

  14. Credible enforcement policies under illegal fishing: does individual transferable quotas induce to reduce the gap between approved and proposed allowable catches?

    Science.gov (United States)

    Da Rocha, José María; Villasante, Sebastián; González, Rafael Trelles

    2013-12-01

    In general, approved Total Allowable Catches (TACs) are higher than proposed TACs by the scientific assessment and reported landings approved are higher than approved TAC. We build a simple enforcement agency's behavior model that generates-as a rational behavior-those two facts. The model has two ingredients. First, there exists illegal fishing generated by an imperfect enforcement technology; second, the enforcement agency cannot commit on announced penalties. We show that lack of commitment increases the potential benefits for national enforcement agency of deviating from proposal (scientific optimal) quotas. Although the enforcement agency wants to announce a low quota target to induce a low level of illegal harvest, it will find optimal to revise the quota announced in order to reduce penalties and improve fishermen welfare. Therefore, agencies find it optimal to approve higher quotas than that proposed by the scientific advice. Our main result is to show that when full compliance is not possible, and national agencies cannot commit, the introduction of Individual Transferable Quotas increases the potential benefits for agencies of deviating from the optimal proposed TAC by the scientific advised.

  15. The longevity gender gap

    DEFF Research Database (Denmark)

    Aviv, Abraham; Shay, Jerry; Christensen, Kaare

    2005-01-01

    In this Perspective, we focus on the greater longevity of women as compared with men. We propose that, like aging itself, the longevity gender gap is exceedingly complex and argue that it may arise from sex-related hormonal differences and from somatic cell selection that favors cells more...... resistant to the ravages of time. We discuss the interplay of these factors with telomere biology and oxidative stress and suggest that an explanation for the longevity gender gap may arise from a better understanding of the differences in telomere dynamics between men and women....

  16. The photon PDF in events with rapidity gaps

    Energy Technology Data Exchange (ETDEWEB)

    Harland-Lang, L.A. [University College London, Department of Physics and Astronomy, London (United Kingdom); Khoze, V.A. [Durham University, Institute for Particle Physics Phenomenology, Durham (United Kingdom); NRC Kurchatov Institute, Petersburg Nuclear Physics Institute, Moscow (Russian Federation); Ryskin, M.G. [NRC Kurchatov Institute, Petersburg Nuclear Physics Institute, Moscow (Russian Federation)

    2016-05-15

    We consider photon-initiated events with large rapidity gaps in proton-proton collisions, where one or both protons may break up. We formulate a modified photon PDF that accounts for the specific experimental rapidity gap veto, and demonstrate how the soft survival probability for these gaps may be implemented consistently. Finally, we present some phenomenological results for the two-photon induced production of lepton and W boson pairs. (orig.)

  17. Molecular doping and band-gap opening of bilayer graphene.

    OpenAIRE

    Samuels, AJ; Carey, JD

    2013-01-01

    The ability to induce an energy band gap in bilayer graphene is an important development in graphene science and opens up potential applications in electronics and photonics. Here we report the emergence of permanent electronic and optical band gaps in bilayer graphene upon adsorption of π electron containing molecules. Adsorption of n- or p-type dopant molecules on one layer results in an asymmetric charge distribution between the top and bottom layers and in the formation of an energy gap. ...

  18. Superconducting gap anomaly in heavy fermion systems

    Indian Academy of Sciences (India)

    G C Rout; M S Ojha; S N Behera

    2008-04-01

    The heavy fermion system (HFS) is described by the periodic Anderson model (PAM), treating the Coulomb correlation between the -electrons in the mean-field Hartree-Fock approximation. Superconductivity is introduced by a BCS-type pairing term among the conduction electrons. Within this approximation the equation for the superconducting gap is derived, which depends on the effective position of the energy level of the -electrons relative to the Fermi level. The latter in turn depends on the occupation probability f of the -electrons. The gap equation is solved self-consistently with the equation for f; and their temperature dependences are studied for different positions of the bare -electron energy level, with respect to the Fermi level. The dependence of the superconducting gap on the hybridization leads to a re-entrant behaviour with increasing strength. The induced pairing between the -electrons and the pairing of mixed conduction and -electrons due to hybridization are also determined. The temperature dependence of the hybridization parameter, which characterizes the number of electrons with mixed character and represents the number of heavy electrons is studied. This number is shown to be small. The quasi-particle density of states (DOS) shows the existence of a pseudo-gap due to superconductivity and the signature of a hybridization gap at the Fermi level. For the choice of the model parameters, the DOS shows that the HFS is a metal and undergoes a transition to the gap-less superconducting state.

  19. Estimating Gender Wage Gaps

    Science.gov (United States)

    McDonald, Judith A.; Thornton, Robert J.

    2011-01-01

    Course research projects that use easy-to-access real-world data and that generate findings with which undergraduate students can readily identify are hard to find. The authors describe a project that requires students to estimate the current female-male earnings gap for new college graduates. The project also enables students to see to what…

  20. Closing the Gap

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    China's recent economic success has brought positive changes to its urban population,but left those in the countryside way behind.The gap in income and living standrs that always existed between urban and rural dwellers has widened alarmingly in the past two decades,causing serious problems.

  1. Structuring the Information Gap.

    Science.gov (United States)

    Edge, Julian

    1984-01-01

    Describes an information gap procedure to teach a new structure which requires students to look for and exchange information in order to complete a task in an English as a second language class. Illustrates the method with a set of materials and suggests ways for teachers to produce similar materials. (SED)

  2. 'Mind the Gap!'

    DEFF Research Database (Denmark)

    Persson, Karl Gunnar

    This paper challenges the widely held view that sharply falling real transport costs closed the transatlantic gap in grain prices in the second half of the 19th century. Several new results emerge from an analysis of a new data set of weekly wheat prices and freight costs from New York to UK mark...

  3. Bridging the Technological Gap.

    Science.gov (United States)

    Lazow, Robert; And Others

    The aim of "Bridging the Technological Gap" (BTG), a federally funded demonstration project, is to use microcomputer technology in the rehabilitation of the psychiatrically disabled. Through the use of a custom designed microcomputer software package, clients receive remediation in areas of specific cognitive and behavioral deficits. The project…

  4. Inverse Probability of Censoring Weighted Estimates of Kendall’s τ for Gap Time Analyses

    OpenAIRE

    Lakhal-Chaieb, Lajmi; Cook, Richard J.; Lin, Xihong

    2010-01-01

    In life history studies interest often lies in the analysis of the inter-event, or gap times and the association between event times. Gap time analyses are challenging however, even when the length of follow-up is determined independently of the event process, since associations between gap times induce dependent censoring for second and subsequent gap times. This paper discusses nonparametric estimation of the association between consecutive gap times based on Kendall’s τ in the presence of ...

  5. Photon-assisted Andreev transport and sub-gap structures

    DEFF Research Database (Denmark)

    Wildt, M; Kutchinsky, Jonatan; Taboryski, Rafael Jozef;

    2000-01-01

    We report new measurements of microwave-induced perturbations of the sub-harmonic energy gap structures in the current-voltage characteristics of superconductor-semiconductor-superconductor junctions. Around the sub-gap bias voltages associated with the enhanced quasi-particle transfer mediated b...

  6. A review of the roles of forest canopy gaps

    Institute of Scientific and Technical Information of China (English)

    Adele Muscolo; Silvio Bagnato; Maria Sidari; Roberto Mercurio

    2014-01-01

    Treefall gap, canopy opening caused by the death of one or more trees, is the dominant form of disturbance in many forest systems worldwide. Gaps play an important role in forest ecology helping to pre-serve bio-and pedo-diversity, influencing nutrient cycles, and maintain-ing the complex structure of the late-successional forests. Over the last 30 years, numerous reviews have been written describing gap dynamics. Here we synthesize current understanding on gap dynamics relating to tree regeneration with particular emphasis on gap characteristics consid-ered critical to develop ecologically sustainable forest management sys-tems and to conserve native biodiversity. Specifically, we addressed the question:how do gaps influence forest structure? From the literature re-viewed, the size of gaps induces important changes in factors such as light intensity, soil humidity and soil biological properties that influence tree species regeneration and differ in gaps of different sizes. Shade-tolerant species can colonize small gaps; shade-intolerant species need large gaps for successful regeneration. Additionally, gap dynamics differ between temperate, boreal, and tropical forests, showing the importance of climate differences in driving forest regeneration. This review summa-rizes information of use to forest managers who design cutting regimes that mimic natural disturbances and who must consider forest structure, forest climate, and the role of natural disturbance in their designs.

  7. Holographic Quenches with a Gap

    CERN Document Server

    da Silva, Emilia; Mas, Javier; Serantes, Alexandre

    2016-01-01

    In order to holographically model quenches with a gapped final hamiltonian, we consider a gravity-scalar theory in anti-de Sitter space with an infrared hard wall. We allow a time dependent profile for the scalar field at the wall. This induces an energy exchange between bulk and wall and generates an oscillating scalar pulse. We argue that such backgrounds are the counterpart of quantum revivals in the dual field theory. We perform a qualitative comparison with the quench dynamics of the massive Schwinger model, which has been recently analyzed using tensor network techniques. Agreement is found provided the width of the oscillating scalar pulse is inversely linked to the energy density communicated by the quench. We propose this to be a general feature of holographic quenches.

  8. Holographic quenches with a gap

    Science.gov (United States)

    da Silva, Emilia; Lopez, Esperanza; Mas, Javier; Serantes, Alexandre

    2016-06-01

    In order to holographically model quenches with a gapped final hamiltonian, we consider a gravity-scalar theory in anti-de Sitter space with an infrared hard wall. We allow a time dependent profile for the scalar field at the wall. This induces an energy exchange between bulk and wall and generates an oscillating scalar pulse. We argue that such backgrounds are the counterpart of quantum revivals in the dual field theory. We perform a qualitative comparison with the quench dynamics of the massive Schwinger model, which has been recently analyzed using tensor network techniques. Agreement is found provided the width of the oscillating scalar pulse is inversely linked to the energy density communicated by the quench. We propose this to be a general feature of holographic quenches.

  9. The inverse F-BAR domain protein srGAP2 acts through srGAP3 to modulate neuronal differentiation and neurite outgrowth of mouse neuroblastoma cells.

    Directory of Open Access Journals (Sweden)

    Yue Ma

    Full Text Available The inverse F-BAR (IF-BAR domain proteins srGAP1, srGAP2 and srGAP3 are implicated in neuronal development and may be linked to mental retardation, schizophrenia and seizure. A partially overlapping expression pattern and highly similar protein structures indicate a functional redundancy of srGAPs in neuronal development. Our previous study suggests that srGAP3 negatively regulates neuronal differentiation in a Rac1-dependent manner in mouse Neuro2a cells. Here we show that exogenously expressed srGAP1 and srGAP2 are sufficient to inhibit valporic acid (VPA-induced neurite initiation and growth in the mouse Neuro2a cells. While ectopic- or over-expression of RhoGAP-defective mutants, srGAP1(R542A and srGAP2(R527A exert a visible inhibitory effect on neuronal differentiation. Unexpectedly, knockdown of endogenous srGAP2 fails to facilitate the neuronal differentiation induced by VPA, but promotes neurite outgrowth of differentiated cells. All three IF-BAR domains from srGAP1-3 can induce filopodia formation in Neuro2a, but the isolated IF-BAR domain from srGAP2, not from srGAP1 and srGAP3, can promote VPA-induced neurite initiation and neuronal differentiation. We identify biochemical and functional interactions of the three srGAPs family members. We propose that srGAP3-Rac1 signaling may be required for the effect of srGAP1 and srGAP2 on attenuating neuronal differentiation. Furthermore, inhibition of Slit-Robo interaction can phenocopy a loss-of-function of srGAP3, indicating that srGAP3 may be dedicated to the Slit-Robo pathway. Our results demonstrate the interplay between srGAP1, srGAP2 and srGAP3 regulates neuronal differentiation and neurite outgrowth. These findings may provide us new insights into the possible roles of srGAPs in neuronal development and a potential mechanism for neurodevelopmental diseases.

  10. Size-confined fixed-composition and composition-dependent engineered band gap alloying induces different internal structures in L-cysteine-capped alloyed quaternary CdZnTeS quantum dots

    Science.gov (United States)

    Adegoke, Oluwasesan; Park, Enoch Y.

    2016-06-01

    The development of alloyed quantum dot (QD) nanocrystals with attractive optical properties for a wide array of chemical and biological applications is a growing research field. In this work, size-tunable engineered band gap composition-dependent alloying and fixed-composition alloying were employed to fabricate new L-cysteine-capped alloyed quaternary CdZnTeS QDs exhibiting different internal structures. Lattice parameters simulated based on powder X-ray diffraction (PXRD) revealed the internal structure of the composition-dependent alloyed CdxZnyTeS QDs to have a gradient nature, whereas the fixed-composition alloyed QDs exhibited a homogenous internal structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed the size-confined nature and monodispersity of the alloyed nanocrystals. The zeta potential values were within the accepted range of colloidal stability. Circular dichroism (CD) analysis showed that the surface-capped L-cysteine ligand induced electronic and conformational chiroptical changes in the alloyed nanocrystals. The photoluminescence (PL) quantum yield (QY) values of the gradient alloyed QDs were 27–61%, whereas for the homogenous alloyed QDs, the PL QY values were spectacularly high (72–93%). Our work demonstrates that engineered fixed alloying produces homogenous QD nanocrystals with higher PL QY than composition-dependent alloying.

  11. Minding the Gap

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Millicent Anne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-23

    Neutron & X-ray scattering provides nano- to meso-scale details of complex fluid structure; 1D electronic density maps dervied from SAXS yield molecular level insights; Neutron reflectivity provides substructure details of substrate supported complex fluids; Complex fluids composition can be optimized to support a wide variety of both soluble and membrane proteins; The water gap dimensions can be finely tuned through polymer component.

  12. Small Generation Gap

    Institute of Scientific and Technical Information of China (English)

    JANE SHAW

    1994-01-01

    IT was while I was making milk for my son that I discovered the generation gap between us. A little thing of two years and three months, my son stood on a big chair I brought him and joined me to make milk. Holding a small spoon in his plump little hand, he scooped flour out of a jar and poured it into the feeding bottle and then scooped milk powder and

  13. GapBlaster-A Graphical Gap Filler for Prokaryote Genomes.

    Science.gov (United States)

    de Sá, Pablo H C G; Miranda, Fábio; Veras, Adonney; de Melo, Diego Magalhães; Soares, Siomar; Pinheiro, Kenny; Guimarães, Luis; Azevedo, Vasco; Silva, Artur; Ramos, Rommel T J

    2016-01-01

    The advent of NGS (Next Generation Sequencing) technologies has resulted in an exponential increase in the number of complete genomes available in biological databases. This advance has allowed the development of several computational tools enabling analyses of large amounts of data in each of the various steps, from processing and quality filtering to gap filling and manual curation. The tools developed for gap closure are very useful as they result in more complete genomes, which will influence downstream analyses of genomic plasticity and comparative genomics. However, the gap filling step remains a challenge for genome assembly, often requiring manual intervention. Here, we present GapBlaster, a graphical application to evaluate and close gaps. GapBlaster was developed via Java programming language. The software uses contigs obtained in the assembly of the genome to perform an alignment against a draft of the genome/scaffold, using BLAST or Mummer to close gaps. Then, all identified alignments of contigs that extend through the gaps in the draft sequence are presented to the user for further evaluation via the GapBlaster graphical interface. GapBlaster presents significant results compared to other similar software and has the advantage of offering a graphical interface for manual curation of the gaps. GapBlaster program, the user guide and the test datasets are freely available at https://sourceforge.net/projects/gapblaster2015/. It requires Sun JDK 8 and Blast or Mummer.

  14. GapBlaster-A Graphical Gap Filler for Prokaryote Genomes.

    Directory of Open Access Journals (Sweden)

    Pablo H C G de Sá

    Full Text Available The advent of NGS (Next Generation Sequencing technologies has resulted in an exponential increase in the number of complete genomes available in biological databases. This advance has allowed the development of several computational tools enabling analyses of large amounts of data in each of the various steps, from processing and quality filtering to gap filling and manual curation. The tools developed for gap closure are very useful as they result in more complete genomes, which will influence downstream analyses of genomic plasticity and comparative genomics. However, the gap filling step remains a challenge for genome assembly, often requiring manual intervention. Here, we present GapBlaster, a graphical application to evaluate and close gaps. GapBlaster was developed via Java programming language. The software uses contigs obtained in the assembly of the genome to perform an alignment against a draft of the genome/scaffold, using BLAST or Mummer to close gaps. Then, all identified alignments of contigs that extend through the gaps in the draft sequence are presented to the user for further evaluation via the GapBlaster graphical interface. GapBlaster presents significant results compared to other similar software and has the advantage of offering a graphical interface for manual curation of the gaps. GapBlaster program, the user guide and the test datasets are freely available at https://sourceforge.net/projects/gapblaster2015/. It requires Sun JDK 8 and Blast or Mummer.

  15. Gap Opening in 3D: Single Planet Gaps

    CERN Document Server

    Fung, Jeffrey

    2016-01-01

    Giant planets can clear deep gaps when embedded in 2D (razor-thin) viscous circumstellar disks. We show by direct simulation that giant planets are just as capable of carving out gaps in 3D. Surface density maps are similar between 2D and 3D, even in detail. In particular, the scaling $\\Sigma_{\\rm gap} \\propto q^{-2}$ of gap surface density with planet mass, derived from a global "zero-dimensional" balance of Lindblad and viscous torques, applies equally well to results obtained at higher dimensions. Our 3D simulations reveal extensive, near-sonic, meridional flows both inside and outside the gaps; these large-scale circulations might bear on disk compositional gradients, in dust or other chemical species. At high planet mass, gap edges are mildly Rayleigh unstable and intermittently shed streams of material into the gap - less so in 3D than in 2D.

  16. Structural analyses of Legionella LepB reveal a new GAP fold that catalytically mimics eukaryotic RasGAP

    Institute of Scientific and Technical Information of China (English)

    Qin Yu; Liyan Hu; Qing Yao; Yongqun Zhu; Na Dong; Da-Cheng Wang; Feng Shao

    2013-01-01

    Rab GTPases are emerging targets of diverse bacterial pathogens.Here,we perform biochemical and structural analyses of LepB,a Rab GTPase-activating protein (GAP) effector from Legionellapneumophila.We map LepB GAP domain to residues 313-618 and show that the GAP domain is Rab1 specific with a catalytic activity higher than the canonical eukaryotic TBC GAP and the newly identified VirA/EspG family of bacterial RabGAP effectors.Exhaustive mutation analyses identify Arg444 as the arginine finger,but no catalytically essential glutamine residues.Crystal structures of LepB313-618 alone and the GAP domain of Legionella drancourtii LepB in complex with Rab1-GDP-AIF3 support the catalytic role of Arg444,and also further reveal a 3D architecture and a GTPase-binding mode distinct from all known GAPs.Glu449,structurally equivalent to TBC RabGAP glutamine finger in apo-LepB,undergoes a drastic movement upon Rab1 binding,which induces Rab1 Gin70 side-chain flipping towards GDP-AIF3 through a strong ionic interaction.This conformationally rearranged Gln70 acts as the catalytic cis-glutamine,therefore uncovering an unexpected RasGAP-like catalytic mechanism for LepB.Our studies highlight an extraordinary structural and catalytic diversity of RabGAPs,particularly those from bacterial pathogens.

  17. Unveiling the Gap

    DEFF Research Database (Denmark)

    Jensson, Pall; Rokkjær, Ole; Nørgaard, Bente

    discussing their NQF and Sweden has decided not to adjust to the EQF for the moment. Analysis of the subject focus for the individual programmes showed a high degree of variation. In the context of CDIO this means that what seems to be a well-known and commonly accepted definition of a discipline like IE...... needs, how universities decide what to teach, and how to bridge the gap. Do the university programs simply reflect the expertise of the faculty members? Is there need for increasing emphasis on continuing education? Is life-long education the answer, and has this been addressed by the CDIO community?...

  18. Mind the gap

    Energy Technology Data Exchange (ETDEWEB)

    Bhagwat, M.S.; Roberts, C.D. [Argonne National Laboratory, Physics Division, Argonne, IL (United States); Krassnigg, A. [Universitaet Graz, Fachbereich Theoretische Physik, Graz (Austria); Maris, P. [University of Pittsburgh, Department of Physics and Astronomy, PA (United States)

    2007-03-15

    In this summary of the application of Dyson-Schwinger equations to the theory and phenomenology of hadrons, some deductions following from a nonperturbative, symmetry-preserving truncation are highlighted, notable amongst which are results for pseudoscalar mesons. We also describe inferences from the gap equation relating to the radius of convergence of a chiral expansion, applications to heavy-light and heavy-heavy mesons, and quantitative estimates of the contribution of quark orbital angular momentum in pseudoscalar mesons; and recapitulate upon studies of nucleon electromagnetic form factors. (orig.)

  19. Mind the gap.

    Energy Technology Data Exchange (ETDEWEB)

    Bhagwat, M. S.; Krassnigg, A.; Maris, P.; Roberts, C. D.; Physics; Univ. Graz; Univ. of Pittsburgh

    2007-03-01

    In this summary of the application of Dyson-Schwinger equations to the theory and phenomenology of hadrons, some deductions following from a nonperturbative, symmetry-preserving truncation are highlighted, notable amongst which are results for pseudoscalar mesons. We also describe inferences from the gap equation relating to the radius of convergence of a chiral expansion, applications to heavy-light and heavy-heavy mesons, and quantitative estimates of the contribution of quark orbital angular momentum in pseudoscalar mesons; and recapitulate upon studies of nucleon electromagnetic form factors.

  20. Photonic band gap materials

    Science.gov (United States)

    Cassagne, D.

    Photonic band gap materials Photonic band gap materials are periodic dielectric structures that control the propagation of electromagnetic waves. We describe the plane wave method, which allows to calculate the band structures of photonic crystals. By symmetry analysis and a perturbative approach, we predict the appearance of the low energy photonic band gaps of hexagonal structures. We propose new two-dimensional structures called graphite and boron nitride. Using a transfer matrix method, we calculate the transmission of the graphite structure and we show the crucial role of the coupling with external modes. We study the appearance of allowed modes in the photonic band gap by the introduction of localized defects in the periodicity. Finally, we discuss the properties of opals formed by self-organized silica microspheres, which are very promising for the fabrication of three-dimensional photonic crystals. Les matériaux à bandes interdites photoniques sont des structures diélectriques périodiques qui contrôlent la propagation des ondes électromagnétiques. Nous décrivons la méthode des ondes planes qui permet de calculer les structures de bandes des cristaux photoniques. Par une analyse de la symétrie et une approche perturbative, nous précisons les conditions d'existence des bandes interdites de basse énergie. Nous proposons de nouvelles structures bidimensionnelles appelées graphite et nitrure de bore. Grâce à une méthode de matrices de transfert, nous calculons la transmission de la structure graphite et nous mettons en évidence le rôle fondamental du couplage avec les modes extérieurs. Nous étudions l'apparition de modes permis dans la bande interdite grâce à l'introduction de défauts dans la périodicité. Enfin, nous discutons les propriétés des opales constituées de micro-billes de silice auto-organisées, qui sont très prometteuses pour la fabrication de cristaux photoniques tridimensionnels.

  1. Closing the stop gap

    Energy Technology Data Exchange (ETDEWEB)

    Czakon, Michal [RWTH Aachen Univ. (Germany). Inst. fuer Theoretische Teilchnphysik und Kosmologie; Mitov, Alexander [Univ. of Cambridge (United Kingdom). Cavendish Lab.; Papucci, Michele [Lawrence Berkeley National Laboratory, CA (United States). Theoretical Physics Group; California Univ., Berkeley, CA (United States). Dept. of Physics; Ruderman, Joshua T. [Lawrence Berkeley National Laboratory, CA (United States). Theoretical Physics Group; California Univ., Berkeley, CA (United States). Dept. of Physics; New York Univ., NY (United States). Center for Cosmology and Particle Physics; Weiler, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); CERN - European Organization for Nuclear Research, Geneva (Switzerland). Theory Div.

    2014-07-15

    Light stops are a hallmark of the most natural realizations of weak-scale supersymmetry. While stops have been extensively searched for, there remain open gaps around and below the top mass, due to similarities of stop and top signals with current statistics. We propose a new fast-track avenue to improve light stop searches for R-parity conserving supersymmetry, by comparing top cross section measurements to the theoretical prediction. Stop masses below ∝180 GeV can now be ruled out for a light neutralino. The possibility of a stop signal contaminating the top mass measurement is also briefly addressed.

  2. Mind the Gap

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    While a growing number of Chinese people are enjoying the benefits brought by economic reform and social development, some are being left behind. The divide between the rich and the poor is widening in China, resulting in an increasingly dissatisfied populace. Some argue that a wealth gap is not a big deal in a market economy and that the problem in China has been exaggerated. But in an article published by China Economic Times, Wu Zhongmin, a sociology professor at the Central Party School of the Commun...

  3. Tunable three photonic band-gaps coherently induced in one-dimensional cold atomic lattices%一维冷原子晶格中相干诱导三光子带隙

    Institute of Scientific and Technical Information of China (English)

    巴诺; 王磊; 张岩

    2014-01-01

    基于电磁感应透明技术,将相干耦合的Tripod型原子俘获在一维光晶格中并使其呈高斯型分布,由于介质的折射率被一维光晶格周期性调制,从而实现动态调控的三光子带隙结构。通过求解光场与原子相互作用密度矩阵方程以及光波在周期性介质中散射的传输矩阵方程,计算出探测场在相干驱动介质中的稳态反射谱和透射谱。计算结果表明:光子带隙的位置、宽度以及反射率可以通过改变两个耦合场的失谐、强度和几何布拉格失谐来调谐。%Using the technique of electromagnetically induced transparency, three photonic bandgaps can be established and manipulated at any time due to the refraction modulated periodically by the one-dimensional optical lattice in a tripod atomic system which is trapped in a one-dimensional optical lattice with a Gaussian density distribution. Using the density-matrix equations to describe the interaction between laser and atoms and the transfer-matrix equation to describe the scattering of light waves in periodic media, we can obtain the steady reflection and transmission spectra. It can be found that the position and width as well as the reflectivity of the photonic band-gap could be tuned by changing the detunings and intensities of the coupling fields and the geometric Bragg detuning.

  4. Board affiliation and pay gap

    Institute of Scientific and Technical Information of China (English)

    Shenglan; Chen; Hui; Ma; Danlu; Bu

    2014-01-01

    This paper examines the effects of board affiliation on the corporate pay gap.Using a sample of Chinese listed firms from 2005 to 2011, we find that boards with a greater presence of directors appointed by block shareholders have lower pay gaps. Furthermore, the governance effects of board affiliation with and without pay are distinguished. The empirical results show that board affiliation without pay is negatively related to the pay gap, while board affiliation with pay is positively related to the pay gap. Overall, the results shed light on how block shareholders affect their companies’ pay gaps through board affiliation.

  5. Gap Task Force

    CERN Multimedia

    Lissuaer, D

    One of the more congested areas in the ATLAS detector is the GAP region (the area between the Barrel Calorimeter and the End Cap calorimeter) where Inner Detector services, LAr Services and some Tile services all must co-habitat in a very limited area. It has been clear for some time that the space in the GAP region is not sufficient to accommodate all that is needed. In the last few month additional problems of routing all the services to Z=0 have been encountered due to the very limited space between the Tile Calorimeter and the first layer of Muon chambers. The Technical Management Board (TMB) and the Executive Board (EB) decided in the middle of March to establish a Task Force to look at this problem and come up with a solution within well-specified guidelines. The task force consisted of experts from the ID, Muon, Liquid Argon and Tile systems in addition to experts from the Technical Coordination team and the Physics coordinator. The task force held many meetings and in general there were some very l...

  6. The Politics of Achievement Gaps

    DEFF Research Database (Denmark)

    Valant, J.; Newark, D. A.

    2016-01-01

    on achievement gaps have received little attention from researchers, despite playing an important role in shaping policymakers’ behaviors. Drawing on randomized experiments with a nationally representative sample of adults, we explore the public’s beliefs about test score gaps and its support for gap......-closing initiatives. We find that Americans are more concerned about—and more supportive of proposals to close—wealth-based achievement gaps than Black-White or Hispanic-White gaps. Americans also explain the causes of wealth-based gaps more readily. © 2016 AERA.......For decades, researchers have documented large differences in average test scores between minority and White students and between poor and wealthy students. These gaps are a focal point of reformers’ and policymakers’ efforts to address educational inequities. However, the U.S. public’s views...

  7. 匹罗卡品致疒间大鼠海马GAP-43与TrkB基因表达及其意义%Expression and its significance of GAP-43 and TrkB mRNA in the rat hippocampus after epilepsy induced by pilocarpine

    Institute of Scientific and Technical Information of China (English)

    李国良; 肖波; 谢光洁; 章蓓; 李昌奇; 伍校琼

    2003-01-01

    目的探讨生长相关蛋白(GAP-43)和脑源性神经营养因子(BDNF)受体TrkB基因在匹罗卡品致疒间大鼠海马的表达及其意义.方法应用原位杂交组织化学方法研究匹罗卡品(PILO)致疒间大鼠海马GAP-43及TrkB mRNA表达的变化.结果匹罗卡品致癫疒间持续状态后3~6小时,海马齿状回颗粒细胞、CA3区及CA1区锥体细胞层TrkB mRNA表达显著高于对照组(P<0.01或0.05);在慢性期第7~30天,呈现第2次表达增强.致疒间后6~12小时,正常状态下并不表达GAP-43的大鼠海马颗粒细胞其GAP-43 mRNA表达较对照组显著增高(P<0.01),24小时~7天表达减少,在癫疒间慢性期表达再次高于对照组.结论 GAP-43及TrkB是颞叶癫疒间病理基础--海马苔藓纤维出芽的重要分子机制;BDNF对苔藓纤维的作用部分是通过GAP-43实现的.

  8. Small Multiples with Gaps.

    Science.gov (United States)

    Meulemans, Wouter; Dykes, Jason; Slingsby, Aidan; Turkay, Cagatay; Wood, Jo

    2017-01-01

    Small multiples enable comparison by providing different views of a single data set in a dense and aligned manner. A common frame defines each view, which varies based upon values of a conditioning variable. An increasingly popular use of this technique is to project two-dimensional locations into a gridded space (e.g. grid maps), using the underlying distribution both as the conditioning variable and to determine the grid layout. Using whitespace in this layout has the potential to carry information, especially in a geographic context. Yet, the effects of doing so on the spatial properties of the original units are not understood. We explore the design space offered by such small multiples with gaps. We do so by constructing a comprehensive suite of metrics that capture properties of the layout used to arrange the small multiples for comparison (e.g. compactness and alignment) and the preservation of the original data (e.g. distance, topology and shape). We study these metrics in geographic data sets with varying properties and numbers of gaps. We use simulated annealing to optimize for each metric and measure the effects on the others. To explore these effects systematically, we take a new approach, developing a system to visualize this design space using a set of interactive matrices. We find that adding small amounts of whitespace to small multiple arrays improves some of the characteristics of 2D layouts, such as shape, distance and direction. This comes at the cost of other metrics, such as the retention of topology. Effects vary according to the input maps, with degree of variation in size of input regions found to be a factor. Optima exist for particular metrics in many cases, but at different amounts of whitespace for different maps. We suggest multiple metrics be used in optimized layouts, finding topology to be a primary factor in existing manually-crafted solutions, followed by a trade-off between shape and displacement. But the rich range of possible

  9. Gaps in Political Interest

    DEFF Research Database (Denmark)

    Robison, Joshua

    2015-01-01

    sought to measure respondents’ general interest in politics by asking them how often they follow public affairs. In this article, we uncover novel sources of measurement error concerning this question. We first show that other nationally representative surveys that frequently use this item deliver......Political interest fundamentally influences political behavior, knowledge, and persuasion (Brady, Verba, & Schlozman, 1995; Delli Carpini & Keeter, 1996; Luskin, 1990; Zukin, Andolina, Keeter, Jenkins, & Delli Carpini, 2006). Since the early 1960s, the American National Election Studies (ANES) has...... drastically higher estimates of mass interest. We then use a survey experiment included on a wave of the ANES’ Evaluating Government and Society Surveys (EGSS) to explore the influence of question order in explaining this systemic gap in survey results. We show that placing batteries of political...

  10. Closing the Gap

    DEFF Research Database (Denmark)

    Tamke, Martin; Kobiella, Olaf

    2007-01-01

    The e4d design series is looking for an innovative use of digital technology in architectural education to overcome the gap between design development and the acquisition of digital skills. Digital design approaches include multimedia technology, the crossover of analogue and digital techniques......, rapid-prototyping, visualization, and the presentation in artistic movies. Over the past two years a problem- based design approach was developed, which enabled students to learn digital and architectural skills simultaneously and efficiently. The educational concept consisted generally of four steps......, which, though independent of each other, are determined by questions of the ongoing design process. The first step consists of an abstract or subjective research phase; in the second step the findings are transferred into dynamic spatial structures. Later, the detected qualities are used to develop...

  11. Closing the Gap

    DEFF Research Database (Denmark)

    Tamke, Martin; Kobiella, Olaf

    2007-01-01

    The e4d design series is looking for an innovative use of digital technology in architectural education to overcome the gap between design development and the acquisition of digital skills. Digital design approaches include multimedia technology, the crossover of analogue and digital techniques......, rapid-prototyping, visualization, and the presentation in artistic movies. Over the past two years a problem- based design approach was developed, which enabled students to learn digital and architectural skills simultaneously and efficiently. The educational concept consisted generally of four steps...... architectural projects can be discussed; in addition, a competent monitoring of the process and outcome of innovative and efficient design strategies in architectural and pedagogical aspect is included....

  12. Closing the Gap

    DEFF Research Database (Denmark)

    Tamke, Martin; Kobiella, Olaf

    2007-01-01

    The e4d design series is looking for an innovative use of digital technology in architectural education to overcome the gap between design development and the acquisition of digital skills. Digital design approaches include multimedia technology, the crossover of analogue and digital techniques...... architectural projects can be discussed; in addition, a competent monitoring of the process and outcome of innovative and efficient design strategies in architectural and pedagogical aspect is included......., rapid-prototyping, visualization, and the presentation in artistic movies. Over the past two years a problem- based design approach was developed, which enabled students to learn digital and architectural skills simultaneously and efficiently. The educational concept consisted generally of four steps...

  13. Molecular doping and band-gap opening of bilayer graphene.

    Science.gov (United States)

    Samuels, Alexander J; Carey, J David

    2013-03-26

    The ability to induce an energy band gap in bilayer graphene is an important development in graphene science and opens up potential applications in electronics and photonics. Here we report the emergence of permanent electronic and optical band gaps in bilayer graphene upon adsorption of π electron containing molecules. Adsorption of n- or p-type dopant molecules on one layer results in an asymmetric charge distribution between the top and bottom layers and in the formation of an energy gap. The resultant band gap scales linearly with induced carrier density though a slight asymmetry is found between n-type dopants, where the band gap varies as 47 meV/10(13) cm(-2), and p-type dopants where it varies as 40 meV/10(13) cm(-2). Decamethylcobaltocene (DMC, n-type) and 3,6-difluoro-2,5,7,7,8,8-hexacyano-quinodimethane (F2-HCNQ, p-type) are found to be the best molecules at inducing the largest electronic band gaps up to 0.15 eV. Optical adsorption transitions in the 2.8-4 μm region of the spectrum can result between states that are not Pauli blocked. Comparison is made between the band gaps calculated from adsorbate-induced electric fields and from average displacement fields found in dual gate bilayer graphene devices. A key advantage of using molecular adsorption with π electron containing molecules is that the high binding energy can induce a permanent band gap and open up possible uses of bilayer graphene in mid-infrared photonic or electronic device applications.

  14. The Adaptation Finance Gap Report

    DEFF Research Database (Denmark)

    UNEP’s Adaptation Gap Report series focuses on Finance, Technology and Knowledge gaps in climate change adaptation. It compliments the Emissions Gap Report series, and explores the implications of failing to close the emissions gap. The report builds on a 2014 assessment by the United Nations...... Environment Programme (UNEP), which laid out the concept of ‘adaptation gaps’ and outlined three such gaps: technology, finance and knowledge. The 2016 Adaptation Gap Report assesses the difference between the financial costs of adapting to climate change in developing countries and the amount of money...... actually available to meet these costs – a difference known as the “adaptation finance gap”. Like the 2014 report, the 2016 report focuses on developing countries, where adaptation capacity is often the lowest and needs the highest, and concentrates on the period up to 2050. The report identifies trends...

  15. Electron Elevator: Excitations across the Band Gap via a Dynamical Gap State.

    Science.gov (United States)

    Lim, A; Foulkes, W M C; Horsfield, A P; Mason, D R; Schleife, A; Draeger, E W; Correa, A A

    2016-01-29

    We use time-dependent density functional theory to study self-irradiated Si. We calculate the electronic stopping power of Si in Si by evaluating the energy transferred to the electrons per unit path length by an ion of kinetic energy from 1 eV to 100 keV moving through the host. Electronic stopping is found to be significant below the threshold velocity normally identified with transitions across the band gap. A structured crossover at low velocity exists in place of a hard threshold. An analysis of the time dependence of the transition rates using coupled linear rate equations enables one of the excitation mechanisms to be clearly identified: a defect state induced in the gap by the moving ion acts like an elevator and carries electrons across the band gap.

  16. Understanding the Tax Gap1

    OpenAIRE

    Mazur, Mark J.; Plumley, Alan H.

    2007-01-01

    The Tax Gap is defined as the difference between the amount of tax imposed by the Tax Code and the amount that is reported and paid with timely filed returns. For the federal government, the gross tax gap is estimated at $345 billion for Tax Year 2001 (after the collection of late and enforced payments, the net tax gap is estimated at $290 billion for Tax Year 2001). This paper explains the concept of the tax gap, discusses how it is estimated, and points out some limitations with the estimates.

  17. Measuring the Gap

    Directory of Open Access Journals (Sweden)

    Xinshu She MD, MPH

    2016-02-01

    Full Text Available China is a large country where rapid development is accompanied by growing inequalities. How economic inequalities translate to health inequalities is unknown. Baseline health assessment is lacking among rural Chinese children. We aimed at assessing baseline student health of rural Chinese children and comparing them with those of urban children of similar ages. A cross-sectional study was conducted using the 2003 Global School-Based Student Health Survey among 100 students Grade 4 to 6 from rural Guizhou, China. Results were summarized and compared with public data from urban Beijing using multivariate logistic regression models. Rural children are more likely to not wash their hands before a meal (odds ratio [OR] = 5.71, P .05. Rural parents are more likely to not know their children’s whereabouts (OR = 1.81, P < .05. Rural children are more than 4 times likely to have serious injuries (OR = 4.64, P < .01 and to be bullied (OR = 4.01, P < .01. In conclusion, school-age rural Chinese children exhibit more health risk behaviors and fewer protective factors at baseline compared to their urban counterparts. Any intervention aimed at improving child health should take this distributive gap into consideration.

  18. Measuring the Gap

    Science.gov (United States)

    She, Xinshu; Zhao, Deqing; Scholnick, Jenna

    2016-01-01

    China is a large country where rapid development is accompanied by growing inequalities. How economic inequalities translate to health inequalities is unknown. Baseline health assessment is lacking among rural Chinese children. We aimed at assessing baseline student health of rural Chinese children and comparing them with those of urban children of similar ages. A cross-sectional study was conducted using the 2003 Global School-Based Student Health Survey among 100 students Grade 4 to 6 from rural Guizhou, China. Results were summarized and compared with public data from urban Beijing using multivariate logistic regression models. Rural children are more likely to not wash their hands before a meal (odds ratio [OR] = 5.71, P suicidal ideation in the past year (OR = 0.68, P > .05). Rural parents are more likely to not know their children’s whereabouts (OR = 1.81, P bullied (OR = 4.01, P < .01). In conclusion, school-age rural Chinese children exhibit more health risk behaviors and fewer protective factors at baseline compared to their urban counterparts. Any intervention aimed at improving child health should take this distributive gap into consideration. PMID:27335999

  19. Theories of subharmonic gap structures in superconducting junctions

    DEFF Research Database (Denmark)

    Hasselberg, L.E.; Levinsen, M. T.; Samuelsen, Mogens Rugholm

    1974-01-01

    The two theories of subharmonic gap structures in superconducting junctions, multiparticle tunneling and self-coupling due to an electromagnetic field set up by the ac Josephson current, are analyzed when microwaves are applied. Both theories give the same location in voltage for the microwave......-induced satellites and the same microwave-power dependence for the subharmonic gap structure and the satellites. Therefore other properties than these are to be considered in order to distinguish between the two theories. We suggest that self-coupling is the main cause of the subharmonic gap structure....

  20. MODELING GD-1 GAPS IN A MILKY WAY POTENTIAL

    Energy Technology Data Exchange (ETDEWEB)

    Carlberg, R. G., E-mail: carlberg@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada)

    2016-03-20

    The GD-1 star stream is currently the best available for identifying density fluctuations, “gaps,” along its length as a test of the LCDM prediction of large numbers of dark matter sub-halos orbiting in the halo. Density variations of some form are present, since the variance of the density along the stream is three times that expected from the empirically estimated variation in the filtered mean star counts. The density variations are characterized with filters that approximate the shape of sub-halo, gravitationally induced stream gaps. The filters locate gaps and measure their amplitude, leading to a measurement of the distribution of gap widths. To gain an understanding of the factors influencing the gap width distribution, a suite of collisionless n-body simulations for a GD-1-like orbit in a Milky-Way-like potential provides a dynamically realistic statistical prediction of the gap distribution. The simulations show that every location in the stream has been disturbed to some degree by a sub-halo. The small gaps found via the filtering are largely noise. Larger gaps, those longer than 1 kpc, or 10° for GD-1, are the source of the excess variance. The suite of stream simulations shows that sub-halos at the predicted inner halo abundance or possibly somewhat higher can produce the required large-scale density variations.

  1. Modeling GD-1 Gaps in a Milky Way Potential

    Science.gov (United States)

    Carlberg, R. G.

    2016-03-01

    The GD-1 star stream is currently the best available for identifying density fluctuations, “gaps,” along its length as a test of the LCDM prediction of large numbers of dark matter sub-halos orbiting in the halo. Density variations of some form are present, since the variance of the density along the stream is three times that expected from the empirically estimated variation in the filtered mean star counts. The density variations are characterized with filters that approximate the shape of sub-halo, gravitationally induced stream gaps. The filters locate gaps and measure their amplitude, leading to a measurement of the distribution of gap widths. To gain an understanding of the factors influencing the gap width distribution, a suite of collisionless n-body simulations for a GD-1-like orbit in a Milky-Way-like potential provides a dynamically realistic statistical prediction of the gap distribution. The simulations show that every location in the stream has been disturbed to some degree by a sub-halo. The small gaps found via the filtering are largely noise. Larger gaps, those longer than 1 kpc, or 10° for GD-1, are the source of the excess variance. The suite of stream simulations shows that sub-halos at the predicted inner halo abundance or possibly somewhat higher can produce the required large-scale density variations.

  2. Nodal and nodeless gap in proximity-induced superconductivity: Application to monolayer CuO2 on a Bi2Sr2CaCu2O8 +δ substrate

    Science.gov (United States)

    Wang, Yimeng; Wang, Zhen-Hua; Chen, Wei-Qiang

    2017-09-01

    We present a detailed analysis on the hopping between monolayer CuO2 and bulk CuO2 plane in the Bi2Sr2CaCu2O8 +δ substrate. With a two-band model, we demonstrate that the nodeless gap can only exist when the hole concentration in the monolayer CuO2 plane is very large. We argue that the possible phase separation may play an important role in the recent experimental observation of a nodeless gap.

  3. GAP Analysis. Bulletin Number 11

    Science.gov (United States)

    2002-01-01

    in 2002 ( ESSB • Creation of a stewardship map is central to GAP’s analysis 6400) that authorizes a comprehensive review to identify the state’s method...governments and their consultants. "Washington State Law ESSB 6400 can be accessed at www.leg.wa.gov/pubfbillinfo/2001-02/Senate, January 10, 2003. Gap

  4. PhoneGap for enterprise

    CERN Document Server

    Shotts, Kerri

    2014-01-01

    This book is intended for developers who wish to use PhoneGap to develop useful, rich, secure mobile applications for their enterprise environment. The book assumes you have working knowledge of PhoneGap, HTML5, CSS3, and JavaScript, and a reasonable understanding of networking and n-tier architectures.

  5. Components of the Belief Gap

    Directory of Open Access Journals (Sweden)

    Cecilie Gaziano

    2014-01-01

    Full Text Available Knowledge gap research focuses on education as an indicator of socioeconomic status (SES. Belief gap research centers on ideology as potentially more powerful than education in comparing sociopolitical groups with scientifically established knowledge and groups with opposing beliefs accepted on faith. This study examined the relationship between education and ideology to understand belief gaps better. The study used 2008 American National Election Study (ANES data to compare conservatives, moderates, and liberals by education on religiosity, child rearing values, opinionation, need for cognition, orientation toward politics, and mass media access and use. Although liberals tended to be more educated than conservatives overall, better-educated conservatives had the highest household incomes and were a much larger group. No known knowledge gap studies have reported results on one group characterized by high education and an opposing group distinguished by a different indicator of SES. Reformulations of the belief gap hypothesis are offered.

  6. GAP Analysis Bulletin Number 15

    Science.gov (United States)

    Maxwell, Jill; Gergely, Kevin; Aycrigg, Jocelyn; Canonico, Gabrielle; Davidson, Anne; Coffey, Nicole

    2008-01-01

    The Mission of the Gap Analysis Program (GAP) is to promote conservation by providing broad geographic information on biological diversity to resource managers, planners, and policy makers who can use the information to make informed decisions. As part of the National Biological Information Infrastructure (NBII) ?a collaborative program to provide increased access to data and information on the nation?s biological resources--GAP data and analytical tools have been used in hundreds of applications: from basic research to comprehensive state wildlife plans; from educational projects in schools to ecoregional assessments of biodiversity. The challenge: keeping common species common means protecting them BEFORE they become threatened. To do this on a state or regional basis requires key information such as land cover descriptions, predicted distribution maps for native animals, and an assessment of the level of protection currently given to those plants and animals. GAP works cooperatively with Federal, state, and local natural resource professionals and academics to provide this kind of information. GAP activities focus on the creation of state and regional databases and maps that depict patterns of land management, land cover, and biodiversity. These data can be used to identify ?gaps? in conservation--instances where an animal or plant community is not adequately represented on the existing network of conservation lands. GAP is administered through the U.S. Geological Survey. Through building partnerships among disparate groups, GAP hopes to foster the kind of collaboration that is needed to address conservation issues on a broad scale. For more information, contact: John Mosesso National GAP Director 703-648-4079 Kevin Gergely National GAP Operations Manager 208-885-3565

  7. The fluctuating gap model

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xiaobin

    2011-01-15

    The quasi-one-dimensional systems exhibit some unusual phenomenon, such as the Peierls instability, the pseudogap phenomena and the absence of a Fermi-Dirac distribution function line shape in the photoemission spectroscopy. Ever since the discovery of materials with highly anisotropic properties, it has been recognized that fluctuations play an important role above the three-dimensional phase transition. This regime where the precursor fluctuations are presented can be described by the so called fluctuating gap model (FGM) which was derived from the Froehlich Hamiltonian to study the low energy physics of the one-dimensional electron-phonon system. Not only is the FGM of great interest in the context of quasi-one-dimensional materials, liquid metal and spin waves above T{sub c} in ferromagnets, but also in the semiclassical approximation of superconductivity, it is possible to replace the original three-dimensional problem by a directional average over effectively one-dimensional problem which in the weak coupling limit is described by the FGM. In this work, we investigate the FGM in a wide temperature range with different statistics of the order parameter fluctuations. We derive a formally exact solution to this problem and calculate the density of states, the spectral function and the optical conductivity. In our calculation, we show that a Dyson singularity appears in the low energy density of states for Gaussian fluctuations in the commensurate case. In the incommensurate case, there is no such kind of singularity, and the zero frequency density of states varies differently as a function of the correlation lengths for different statistics of the order parameter fluctuations. Using the density of states we calculated with non-Gaussian order parameter fluctuations, we are able to calculate the static spin susceptibility which agrees with the experimental data very well. In the calculation of the spectral functions, we show that as the correlation increases, the

  8. More on gapped Goldstones at finite density: More gapped Goldstones

    CERN Document Server

    Nicolis, Alberto; Piazza, Federico; Rosen, Rachel A

    2013-01-01

    It was recently argued that certain relativistic theories at finite density can exhibit an unconventional spectrum of Goldstone excitations, with gapped Goldstones whose gap is exactly calculable in terms of the symmetry algebra. We confirm this result as well as previous ones concerning gapless Goldstones for non-relativistic systems via a coset construction of the low-energy effective field theory. Moreover, our analysis unveils additional gapped Goldstones, naturally as light as the others, but this time with a model-dependent gap. Their exact number cannot be inferred solely from the symmetry breaking pattern either, but rather depends on the details of the symmetry breaking mechanism--a statement that we explicitly verify with a number of examples. Along the way we provide what we believe to be a particularly transparent interpretation of the so-called inverse-Higgs constraints for spontaneously broken spacetime symmetries.

  9. Energy gap in concentrated spin glasses

    Energy Technology Data Exchange (ETDEWEB)

    Liao, S.B.; Bhagat, S.M.; Manheimer, M.A.; Moorjani, K.

    1988-04-15

    Using magnetic resonance data at several frequencies, we have obtained the temperature dependence of the field-induced magnetization (M) in three concentrated spin glasses. At every frequency, M is independent of T for Tapprox. gap energy with values close to the corresponding Curie--Weiss temperatures theta/sub p/ but much larger than the respective spin-glass transition temperatures T/sub SG/.

  10. The Income Gap GROWS Large

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The income gap between regions, urban and rural areas, industries and various social groups is widening in China. The gap, as indicated by the Gini Coefficient, extended beyond an alarming level. A World Bank report said the Gini Coefficient for China surged to 0.47 in 2009, exceeding the "red line" of 0.4. The problems caused by the rising income disparity have been the focus of public attention. Some experts believe that it is high time for China to shrink this income gap. A Xinhua News Agency research team recently analyzed this trend, and published an article in the Economic Information Daily. Edited excerpts follow:

  11. The Income Gap Grows Large

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ The income gap between regions,urban and rural areas,industries and various social groups is widening in China.The gap,as indicated by the Gini Coefficient,extended beyond an alarming level.A World Bank report said the Gini Coefficient for China surged to 0A7 in 2009,exceeding the "red line"of 0.4.The problems caused by the rising income disparity have been the focus of public attention.Some experts believe that it is high time for China to shrink this income gap.

  12. Gap Surface Plasmon Waveguide Analysis

    DEFF Research Database (Denmark)

    Nielsen, Michael Grøndahl; Bozhevolnyi, Sergey I.

    2014-01-01

    Plasmonic waveguides supporting gap surface plasmons (GSPs) localized in a dielectric spacer between metal films are investigated numerically and the waveguiding properties at telecommunication wavelengths are presented. Especially, we emphasize that the mode confinement can advantageously...

  13. Talent Management: Bridging the Gap

    Science.gov (United States)

    2015-06-12

    Cooper and Colton, you are the greatest gift I could have ever imagined. Daddy’s done with his homework and now we can go to the park–I promise...45 Gap 4: Up-Or-Out Promotions ..................................................................................... 49

  14. Closing the Cybersecurity Skills Gap

    Directory of Open Access Journals (Sweden)

    Rebecca Vogel

    2016-05-01

    Full Text Available The current consensus is that there is a worldwide gap in skills needed for a competent cybersecurity workforce. This skills gap has implications for the national security sector, both public and private. Although the view is that this will take a concerted effort to rectify, it presents an opportunity for IT professionals, university students, and aspirants to take-up jobs in national security national intelligence as well military and law enforcement intelligence. This paper examines context of the issue, the nature of the cybersecurity skills gap, and some key responses by governments to address the problem. The paper also examines the emerging employment trends, some of the employment challenges, and what these might mean for practice. The paper argues that the imperative is to close the cyber skills gap by taking advantage of the window of opportunity, allowing individuals interested in moving into the cybersecurity field to do so via education and training.

  15. Modeling GD-1 Gaps in a Milky-Way Potential

    CERN Document Server

    Carlberg, Raymond G

    2015-01-01

    The GD-1 star stream is currently the best available for identifying density fluctuations, "gaps", along its length as a test of the LCDM prediction of large numbers of dark matter sub-halos orbiting in the halo. Density variations of some form are present, since the variance of the density along the stream is three times that expected from the empirically estimated variation in the filtered mean star counts. The density variations are characterized with filters that approximate the shape of sub-halo induced stream gaps, which locates gaps and measures their amplitude, leading to a measurement of the distribution of gap widths. To gain understanding of the gap width distribution, a suite of n-body simulations for a GD-1 like orbit in a Milky Way-like potential provides a dynamically realistic statistical prediction of the gap distribution. The simulations show that every location in the stream has been disturbed to some degree by a sub-halo. The small gaps emerging from the filtering are largely noise. Larger...

  16. Virtual gap dielectric wall accelerator

    Science.gov (United States)

    Caporaso, George James; Chen, Yu-Jiuan; Nelson, Scott; Sullivan, Jim; Hawkins, Steven A

    2013-11-05

    A virtual, moving accelerating gap is formed along an insulating tube in a dielectric wall accelerator (DWA) by locally controlling the conductivity of the tube. Localized voltage concentration is thus achieved by sequential activation of a variable resistive tube or stalk down the axis of an inductive voltage adder, producing a "virtual" traveling wave along the tube. The tube conductivity can be controlled at a desired location, which can be moved at a desired rate, by light illumination, or by photoconductive switches, or by other means. As a result, an impressed voltage along the tube appears predominantly over a local region, the virtual gap. By making the length of the tube large in comparison to the virtual gap length, the effective gain of the accelerator can be made very large.

  17. Folk Belief Theory, the Rigor Gap, and the Achievement Gap

    Science.gov (United States)

    Torff, Bruce

    2014-01-01

    Folk belief theory is suggested as a primary cause for the persistence of the achievement gap. In this research-supported theory, culturally specified folk beliefs about learning and teaching prompt educators to direct more rigorous curriculum to high-advantage students but not to low-advantage students, resulting in impoverished pedagogy in…

  18. Want to Close the Achievement Gap? Close the Teaching Gap

    Science.gov (United States)

    Darling-Hammond, Linda

    2015-01-01

    For years now, educators have looked to international tests as a yardstick to measure how well students from the United States are learning compared with their peers. The answer has been: not so well. The United States has been falling further behind other nations and has struggled with a large achievement gap. Federal policy under No Child Left…

  19. Folk Belief Theory, the Rigor Gap, and the Achievement Gap

    Science.gov (United States)

    Torff, Bruce

    2014-01-01

    Folk belief theory is suggested as a primary cause for the persistence of the achievement gap. In this research-supported theory, culturally specified folk beliefs about learning and teaching prompt educators to direct more rigorous curriculum to high-advantage students but not to low-advantage students, resulting in impoverished pedagogy in…

  20. The Emissions Gap Report 2014

    DEFF Research Database (Denmark)

    Farrell, Timothy Clifford

    This fifth Emissions Gap report has a different focus from previous years. While it updates the 2020 emissions gap analysis, it gives particular attention to the implications of the global carbon dioxide emissions budget for staying within the 2 °C limit beyond 2020. It does so because countries...... are giving increasing attention to where they need to be in 2025, 2030 and beyond. Furthermore, this year’s update of the report benefits from the findings on the emissions budget from the latest series of Intergovernmental Panel on Climate Change (IPCC) reports...

  1. Microstrip microwave band gap structures

    Indian Academy of Sciences (India)

    V Subramanian

    2008-04-01

    Microwave band gap structures exhibit certain stop band characteristics based on the periodicity, impedance contrast and effective refractive index contrast. These structures though formed in one-, two- and three-dimensional periodicity, are huge in size. In this paper, microstrip-based microwave band gap structures are formed by removing the substrate material in a periodic manner. This paper also demonstrates that these structures can serve as a non-destructive characterization tool for materials, a duplexor and frequency selective coupler. The paper presents both experimental results and theoretical simulation based on a commercially available finite element methodology for comparison.

  2. The Adaptation Gap Report - a Preliminary Assessment

    DEFF Research Database (Denmark)

    Alverson, Keith; Olhoff, Anne; Noble, Ian;

    This first Adaptation Gap report provides an equally sobering assessment of the gap between adaptation needs and reality, based on preliminary thinking on how baselines, future goals or targets, and gaps between them might be defined for climate change adaptation. The report focuses on gaps in de...... in developing countries in three important areas: finance, technology and knowledge....

  3. Fear Similarly Alters Perceptual Estimates of and Actions over Gaps.

    Science.gov (United States)

    Geuss, Michael N; McCardell, Michael J; Stefanucci, Jeanine K

    2016-01-01

    Previous research has demonstrated an influence of one's emotional state on estimates of spatial layout. For example, estimates of heights are larger when the viewer is someone typically afraid of heights (trait fear) or someone who, in the moment, is experiencing elevated levels of fear (state fear). Embodied perception theories have suggested that such a change in perception occurs in order to alter future actions in a manner that reduces the likelihood of injury. However, other work has argued that when acting, it is important to have access to an accurate perception of space and that a change in conscious perception does not necessitate a change in action. No one has yet investigated emotional state, perceptual estimates, and action performance in a single paradigm. The goal of the current paper was to investigate whether fear influences perceptual estimates and action measures similarly or in a dissociable manner. In the current work, participants either estimated gap widths (Experiment 1) or were asked to step over gaps (Experiment 2) in a virtual environment. To induce fear, the gaps were placed at various heights up to 15 meters. Results showed an increase in gap width estimates as participants indicated experiencing more fear. The increase in gap estimates was mirrored in participants' stepping behavior in Experiment 2; participants stepped over fewer gaps when experiencing higher state and trait fear and, when participants actually stepped, they stepped farther over gap widths when experiencing more fear. The magnitude of the influence of fear on both perception and action were also remarkably similar (5.3 and 3.9 cm, respectively). These results lend support to embodied perception claims by demonstrating an influence on action of a similar magnitude as seen on estimates of gap widths.

  4. A PHOTONIC BAND GAP FIBRE

    DEFF Research Database (Denmark)

    1999-01-01

    An optical fibre having a periodicidal cladding structure provididing a photonic band gap structure with superior qualities. The periodical structure being one wherein high index areas are defined and wherein these are separated using a number of methods. One such method is the introduction...

  5. Burkholderia pseudomallei Data Gap Analysis

    Science.gov (United States)

    2015-11-01

    conducting this review is to identify the major biodefense relevant data gaps critical to better understanding B. pseudomallei infections and how they are...of patients (Table 2-1). Much of the data has excellent demographic and clinical resolution including age, sex, symptoms, duration of illness, risk...inhalation and enteral. Presentations include pneumonia , genitourinary, cutaneous, general bacteremia, septic arthritis and neurological

  6. Gap Analysis Bulletin No. 13

    Science.gov (United States)

    2005-12-01

    Project Laurence L. Strong of the spatial distribution of the accuracy parameters by applying U.S. Geological Survey, Northern Prairie Wildlife...Wildlife Resources year: at the University of Idaho. Her dissertation focuses on the " GIS Analyst Ree Brannon has returned to school at the population...54 North Dakota Gap Analysis Project Laurence L. Strong

  7. Income Gap Widens in Beijing

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The income gap between the highest-and lowestincome groups in Beijing, China's capital city, grew to 4:1 in 2004, up from 3:1 in 2003, according to a sampling survey of 2,000 urban households conducted by the Beijing Municipal Statistics Bureau.Among the most important factors affecting income levels were education and profession, the survey indicated.

  8. The Widening Income Achievement Gap

    Science.gov (United States)

    Reardon, Sean F.

    2013-01-01

    Has the academic achievement gap between high-income and low-income students changed over the last few decades? If so, why? And what can schools do about it? Researcher Sean F. Reardon conducted a comprehensive analysis of research to answer these questions and came up with some striking findings. In this article, he shows that income-related…

  9. Denmark and the gap year

    DEFF Research Database (Denmark)

    Katznelson, Noemi; Juul, Tilde Mette

    2013-01-01

    This paper describes three different educational offers to young people: “The Folk High School”, “The ‘After-school’” and 10th class. All can be considered optional Gap Years. The following diagram shows how the Danish education system is structured. The Folk High School is a training course of v...

  10. The Gap Detection Test : Can It Be Used to Diagnose Tinnitus?

    NARCIS (Netherlands)

    Boyen, Kris; Başkent, Deniz; van Dijk, Pim

    2015-01-01

    Objectives: Animals with induced tinnitus showed difficulties in detecting silent gaps in sounds, suggesting that the tinnitus percept may be filling the gap. The main purpose of this study was to evaluate the applicability of this approach to detect tinnitus in human patients. The authors first hyp

  11. Air Gap Effects in LX-17

    Energy Technology Data Exchange (ETDEWEB)

    Souers, P C; Ault, S; Avara, R; Bahl, K L; Boat, R; Cunningham, B; Gidding, D; Janzen, J; Kuklo, D; Lee, R; Lauderbach, L; Weingart, W C; Wu, B; Winer, K

    2005-09-26

    Three experiments done over twenty years on gaps in LX-17 are reported. For the detonation front moving parallel to the gaps, jets of gas products were seen coming from the gaps at velocities greater than the detonation velocity. A case can be made that the jet velocity increased with gap thickness but the data is scattered. For the detonation front moving transverse to the gap, time delays were seen. The delays roughly increase with gap width, going from 0-70 ns at 'zero gap' to around 300 ns at 0.5-1 mm gap. Larger gaps of up to 6 mm width almost certainly stopped the detonation, but this was not proved. Real-time resolution of the parallel jets and determination of the actual re-detonation or failure in the transverse case needs to be done in future experiments.

  12. Evidence for two superconducting gaps in MgB2.

    Science.gov (United States)

    Chen, X K; Konstantinovic, M J; Irwin, J C; Lawrie, D D; Franck, J P

    2001-10-01

    We have measured the Raman spectra of polycrystalline MgB2 from 25 to 1200 cm(-1). A superconductivity-induced redistribution in the electronic Raman continuum was observed. Two pair-breaking peaks appear in the spectra, suggesting the presence of two superconducting gaps. The measured spectra were analyzed using a quasi-two-dimensional model in which two s-wave superconducting gaps open on two sheets of Fermi surface. For the gap values we have obtained Delta(1) = 22 cm(-1) ( 2.7 meV) and Delta(2) = 50 cm(-1) ( 6.2 meV). Our results suggest that a conventional phonon-mediated pairing mechanism occurs in the planar boron sigma bands and is responsible for the superconductivity of MgB2.

  13. Charge distribution dependency on gap thickness of CMS endcap RPC

    CERN Document Server

    Park, Sung Keun

    2016-01-01

    We present a systematic study of charge distribution dependency of CMS Resistive Plate Chamber (RPC) on gap thickness.Prototypes of double-gap with five different gap thickness from 1.8mm to 1.0mm in 0.2mm steps have been built with 2mm thick phenolic high-pressure-laminated (HPL) plates. The charges of cosmic-muon signals induced on the detector strips are measured as a function of time using two four-channel 400-MHz fresh ADCs. In addition, the arrival time of the muons and the strip cluster sizes are measured by digitizing the signal using a 32-channel voltage-mode front-end-electronics and a 400-MHz 64-channel multi-hit TDC. The gain and the input impedance of the front-end-electronics were 200mV/mV and 20 Ohm, respectively.

  14. Bright and gap solitons in membrane-type acoustic metamaterials

    Science.gov (United States)

    Zhang, Jiangyi; Romero-García, Vicente; Theocharis, Georgios; Richoux, Olivier; Achilleos, Vassos; Frantzeskakis, Dimitrios J.

    2017-08-01

    We study analytically and numerically envelope solitons (bright and gap solitons) in a one-dimensional, nonlinear acoustic metamaterial, composed of an air-filled waveguide periodically loaded by clamped elastic plates. Based on the transmission line approach, we derive a nonlinear dynamical lattice model which, in the continuum approximation, leads to a nonlinear, dispersive, and dissipative wave equation. Applying the multiple scales perturbation method, we derive an effective lossy nonlinear Schrödinger equation and obtain analytical expressions for bright and gap solitons. We also perform direct numerical simulations to study the dissipation-induced dynamics of the bright and gap solitons. Numerical and analytical results, relying on the analytical approximations and perturbation theory for solions, are found to be in good agreement.

  15. Hard gap in epitaxial semiconductor-superconductor nanowires.

    Science.gov (United States)

    Chang, W; Albrecht, S M; Jespersen, T S; Kuemmeth, F; Krogstrup, P; Nygård, J; Marcus, C M

    2015-03-01

    Many present and future applications of superconductivity would benefit from electrostatic control of carrier density and tunnelling rates, the hallmark of semiconductor devices. One particularly exciting application is the realization of topological superconductivity as a basis for quantum information processing. Proposals in this direction based on the proximity effect in semiconductor nanowires are appealing because the key ingredients are currently in hand. However, previous instances of proximitized semiconductors show significant tunnelling conductance below the superconducting gap, suggesting a continuum of subgap states--a situation that nullifies topological protection. Here, we report a hard superconducting gap induced by the proximity effect in a semiconductor, using epitaxial InAs-Al semiconductor-superconductor nanowires. The hard gap, together with favourable material properties and gate-tunability, makes this new hybrid system attractive for a number of applications, as well as fundamental studies of mesoscopic superconductivity.

  16. Hard gap in epitaxial semiconductor-superconductor nanowires

    DEFF Research Database (Denmark)

    Chang, W.; Albrecht, S. M.; Jespersen, T. S.;

    2015-01-01

    a continuum of subgap states---a situation that nullifies topological protection. Here, we report a hard superconducting gap induced by proximity effect in a semiconductor, using epitaxial Al-InAs superconductor-semiconductor nanowires. The hard gap, along with favorable material properties and gate......Many present and future applications of superconductivity would benefit from electrostatic control of carrier density and tunneling rates, the hallmark of semiconductor devices. One particularly exciting application is the realization of topological superconductivity as a basis for quantum...... information processing. Proposals in this direction based on proximity effect in semiconductor nanowires are appealing because the key ingredients are currently in hand. However, previous instances of proximitized semiconductors show significant tunneling conductance below the superconducting gap, suggesting...

  17. Closing the BME attainment gap

    OpenAIRE

    Nortcliffe, Anne; Pink-Keech, Cathy; Evans, Jayne

    2014-01-01

    The national British Minority Ethnic (BME) attainment gap is 16% (Berry and Loke, 2011). BME students frequently report being isolated and lonely (Cotton et al, 2011), and experience derisory support (NUS, 2011). At Sheffield Hallam University (SHU) a pilot Peer Assisted Learning (PAL) programme on an engineering course to aid inclusivity, as at UCL PAL has increased student retention (Angelini, 2011). The initial results at SHU are positive: "They [Mentors] kept me on a course and ...

  18. Introspections on the Semantic Gap

    Science.gov (United States)

    2015-04-14

    essential goal of virtual machine introspection ( VMI ) is security policy enforcement in the presence of an untrustworthy OS. One obstacle to this goal is...ABSTRACT Introspections on the Semantic Gap Report Title An essential goal of virtual machine introspection ( VMI ) is security policy enforcement in the...machine introspection ( VMI ) is security policy enforcement in the presence of an untrustworthy OS. One obstacle to this goal is the difficulty in

  19. Investigations of Pulsed Vacuum Gap.

    Science.gov (United States)

    1981-02-10

    re-az4,irc t:ata -.as taken .0thcut t1he cury-ent vino r’esistor. Initial data, with no current viewing resistor, were taken for a 35 mmn gap using an...Eastman, and J. Kivlin, "The Appearance of Micro- particles in Accelerator Tubes," Proc. of 8th Symp., Paper F6-1, Albuquerque, . . Mexico , (1978). 71391

  20. Filling in biodiversity threat gaps

    DEFF Research Database (Denmark)

    Joppa, L. N.; O'Connor, Brian; Visconti, Piero

    2016-01-01

    increase to 10,000 times the background rate should species threatened with extinction succumb to pressures they face (4). Reversing these trends is a focus of the Convention on Biological Diversity's 2020 Strategic Plan for Biodiversity and its 20 Aichi Targets and is explicitly incorporated...... into the United Nations' 2030 Agenda for Sustainable Development and its 17 Sustainable Development Goals (SDGs). We identify major gaps in data available for assessing global biodiversity threats and suggest mechanisms for closing them....

  1. Rational Solution To Income Gap

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    While enjoying an economic boom, China has seen a widening income gap that has appeared like a chasm between its urban and rural citizens. What are the deep roots of this situation and what is the best way to deal with it? Ding Yuanzhu, researcher at the Macro-Economic Research Institute of the National Development and Reform Commission, shares his views on this issue in an article published in Wen Hui Bao. Excerpts follow:

  2. Prometheus and the Keeler gap

    Science.gov (United States)

    Tajeddine, Radwan; Nicholson, Phillip D.; Hedman, Matthew M.; French, Richard G.; Tiscareno, Matthew S.; Burns, Joseph A.

    2014-11-01

    Linblad resonances with Saturn’s satellites are located at many radii in the rings. While some cause density or bending waves, others hold gap edges from spreading, like the 2:1 resonance with Mimas located at the B-ring edge, the 7:6 resonance with Janus at the A-ring edge, and the 32:31 resonance with Prometheus at the inner edge of the Keeler gap. The latter is the case of study here.Theoretically, the inner edge of the Keeler gap should have 32 regular sinusoidal lobes, where either the maximum or the minimum radius is expected to be aligned with Prometheus and rotating with its mean motion. We show that such is not the case. Fit of occultation data shows the presence of the 32:31 resonance, however, the fit residuals is as high as the amplitude of the resonance amplitude (about 2 km). Analysis of the ISS data, shows irregularities overlapping the lobes (Tiscareno et al. 2005, DPS), that follow Keplerian motion. These irregularities may be due to clumps of particles with different eccentricities than the rest of the edge particles. This phenomenon may be caused by the resonance, as it has not been observed at other circular edges were no resonance is present at their location. The ISS data also shows that the lobe’s minimum/maximum is not perfectly aligned with the longitude of Prometheus, which may be due to libration about the centre of the resonance.

  3. Using Unmanned Aerial Vehicles (UAV to Quantify Spatial Gap Patterns in Forests

    Directory of Open Access Journals (Sweden)

    Stephan Getzin

    2014-07-01

    Full Text Available Gap distributions in forests reflect the spatial impact of man-made tree harvesting or naturally-induced patterns of tree death being caused by windthrow, inter-tree competition, disease or senescence. Gap sizes can vary from large (>100 m2 to small (<10 m2, and they may have contrasting spatial patterns, such as being aggregated or regularly distributed. However, very small gaps cannot easily be recorded with conventional aerial or satellite images, which calls for new and cost-effective methodologies of forest monitoring. Here, we used an unmanned aerial vehicle (UAV and very high-resolution images to record the gaps in 10 temperate managed and unmanaged forests in two regions of Germany. All gaps were extracted for 1-ha study plots and subsequently analyzed with spatially-explicit statistics, such as the conventional pair correlation function (PCF, the polygon-based PCF and the mark correlation function. Gap-size frequency was dominated by small gaps of an area <5 m2, which were particularly frequent in unmanaged forests. We found that gap distances showed a variety of patterns. However, the polygon-based PCF was a better descriptor of patterns than the conventional PCF, because it showed randomness or aggregation for cases when the conventional PCF showed small-scale regularity; albeit, the latter was only a mathematical artifact. The mark correlation function revealed that gap areas were in half of the cases negatively correlated and in the other half independent. Negative size correlations may likely be the result of single-tree harvesting or of repeated gap formation, which both lead to nearby small gaps. Here, we emphasize the usefulness of UAV to record forest gaps of a very small size. These small gaps may originate from repeated gap-creating disturbances, and their spatial patterns should be monitored with spatially-explicit statistics at recurring intervals in order to further insights into forest dynamics.

  4. Electroluminescence from indirect band gap semiconductor ReS2

    Science.gov (United States)

    Gutiérrez-Lezama, Ignacio; Aditya Reddy, Bojja; Ubrig, Nicolas; Morpurgo, Alberto F.

    2016-12-01

    It has been recently claimed that bulk crystals of transition metal dichalcogenide (TMD) ReS2 are direct band gap semiconductors, which would make this material an ideal candidate, among all TMDs, for the realization of efficient opto-electronic devices. The situation is however unclear, because even more recently an indirect transition in the PL spectra of this material has been detected, whose energy is smaller than the supposed direct gap. To address this issue we exploit the properties of ionic liquid gated field-effect transistors (FETs) to investigate the gap structure of bulk ReS2. Using these devices, whose high quality is demonstrated by a record high electron FET mobility of 1100 cm2 V-1 s-1 at 4 K, we can induce hole transport at the surface of the material and determine quantitatively the smallest band gap present in the material, irrespective of its direct or indirect nature. The value of the band gap is found to be 1.41 eV, smaller than the 1.5 eV direct optical transition but in good agreement with the energy of the indirect optical transition, providing an independent confirmation that bulk ReS2 is an indirect band gap semiconductor. Nevertheless, contrary to the case of more commonly studied semiconducting TMDs (e.g., MoS2, WS2, etc) in their bulk form, we also find that ReS2 FETs fabricated on bulk crystals do exhibit electroluminescence when driven in the ambipolar injection regime, likely because the difference between direct and indirect gap is only 100 meV. We conclude that ReS2 does deserve more in-depth investigations in relation to possible opto-electronic applications.

  5. Epithelial gap closure governed by forces and geometry

    Science.gov (United States)

    Ladoux, Benoit

    The closure of gaps within epithelia is crucial to maintain the integrity and the homeostasis of the tissue during wound healing or cell extrusion processes. Cells mediate gap closure through either the assembly of multicellular actin-based contractile cables (purse-string contraction) or the protrusive activity of border cells into the gap (cell crawling). I will present experimental data and numerical modeling that show how these mechanisms can mutually interact to promote efficient epithelial gap closure and how mechanical constraints can regulate these mechanisms. I will first present how geometrical constraints dictate mechanisms of epithelial gap closure. We determine the importance of tissue shape during closure and the role of curvature of cell boundaries in this process. An essential difference between the two closure mechanisms is that cell crawling always pulls the edge of the tissue forward (i.e. towards the gap) while purse string pulls the edge forward or backwards depending on the local geometry. Our study demonstrates how the interplay between these two mechanisms is crucial for closing gaps and wounds, which naturally come in arbitrary shapes. Then I will focus on epithelial closure mechanism during cell extrusion. Within confluent cell layers, cellular motions coupled between neighbors are tightly regulated by the packing density of the epithelium inducing drastic changes in the dynamics of these tissues. I will show how cell density and tissue mechanics regulate the extrusion of cells within a confluent epithelial cell sheet, simultaneously measuring collective movements and traction forces. Epithelial packing and collective cell dynamics dictate the modes of cellular extrusions from lamellipodia crawling of the neighboring cells at low densities to coordinated actin-based contractile purse-string mechanism at higher density.

  6. Hard Superconducting Gap in InSb Nanowires

    Science.gov (United States)

    Gül, Önder; Zhang, Hao; de Vries, Folkert K.; van Veen, Jasper; Zuo, Kun; Mourik, Vincent; Conesa-Boj, Sonia; Nowak, Michał P.; van Woerkom, David J.; Quintero-Pérez, Marina; Cassidy, Maja C.; Geresdi, Attila; Koelling, Sebastian; Car, Diana; Plissard, Sébastien R.; Bakkers, Erik P. A. M.; Kouwenhoven, Leo P.

    2017-04-01

    Topological superconductivity is a state of matter that can host Majorana modes, the building blocks of a topological quantum computer. Many experimental platforms predicted to show such a topological state rely on proximity-induced superconductivity. However, accessing the topological properties requires an induced hard superconducting gap, which is challenging to achieve for most material systems. We have systematically studied how the interface between an InSb semiconductor nanowire and a NbTiN superconductor affects the induced superconducting properties. Step by step, we improve the homogeneity of the interface while ensuring a barrier-free electrical contact to the superconductor, and obtain a hard gap in the InSb nanowire. The magnetic field stability of NbTiN allows the InSb nanowire to maintain a hard gap and a supercurrent in the presence of magnetic fields (~ 0.5 Tesla), a requirement for topological superconductivity in one-dimensional systems. Our study provides a guideline to induce superconductivity in various experimental platforms such as semiconductor nanowires, two dimensional electron gases and topological insulators, and holds relevance for topological superconductivity and quantum computation.

  7. Electric field dependence of hybridized gap in InAs/GaSb quantum well system

    Science.gov (United States)

    Ruan, Jiufu; Wei, Xiangfei; Wang, Weiyang

    2017-02-01

    We demonstrate theoretically that exchange interaction induced by electron-hole scattering via Coulomb interaction can cause a hybridized gap in InAs/GaSb based type II and broken-gap quantum wells. The hybridized energy spectra are obtained analytically at the low temperature and long wave limits. An electric field depended hybridized gap about 4 meV opens at the anti-crossing points of the hybridized energy spectra, in accordance with experimental measurements. The hybridized gap varies linearly with the gate electric voltage due to the fact that the electric field can change the exchange self-energy by tuning the overlap of the wavefunctions and the Fermi energy. Our theoretical results can give a deep insight of the origin of the hybridized gap and provide a simple way to determine the value and the position of the hybridized gap in the presence of the gate electric voltage.

  8. Inverse probability of censoring weighted estimates of Kendall's τ for gap time analyses.

    Science.gov (United States)

    Lakhal-Chaieb, Lajmi; Cook, Richard J; Lin, Xihong

    2010-12-01

    In life history studies, interest often lies in the analysis of the interevent, or gap times and the association between event times. Gap time analyses are challenging however, even when the length of follow-up is determined independently of the event process, because associations between gap times induce dependent censoring for second and subsequent gap times. This article discusses nonparametric estimation of the association between consecutive gap times based on Kendall's τ in the presence of this type of dependent censoring. A nonparametric estimator that uses inverse probability of censoring weights is provided. Estimates of conditional gap time distributions can be obtained following specification of a particular copula function. Simulation studies show the estimator performs well and compares favorably with an alternative estimator. Generalizations to a piecewise constant Clayton copula are given. Several simulation studies and illustrations with real data sets are also provided.

  9. GAP-43 Expression and Pathological Changes of Temporal Infarction in Rats and Effects of Batroxobin

    Institute of Scientific and Technical Information of China (English)

    吴卫平; 管兴志; 张小澍; 匡培根

    2002-01-01

    @@ To study the changes of the expression of growth-associated protein-43 (GAP-43) and pathology in temporal infarction of rats photochemically induced and the effects of batroxobin. Methods: immunohistochemical technique and hematoxylin-eosin stain was used to show the changes of the expression of GAP-43 and pathology. Results: In infarction group, GAP-43 expression was markedly increased on the infarction and surronding tissues at 24h cerebral infarction. The expression reached peak level at 72h after cerebral infarction and was decreased at 7d after cerebral infarction. However, in batroxobin-treated group, GAP-43 expression was increased and the pathological changes were much slight as compared with infarction group. Conclusion: The expression of GAP-43 increases in infarction of temporal neocortex and batroxobin promotes the expression of GAP-43 and ameliorates the pathological changes in infarction of temporal neocortex.

  10. Induced superconductivity in the topological insulator mercury telluride

    Energy Technology Data Exchange (ETDEWEB)

    Maier, Luis

    2015-07-01

    thus the increased coupling of the Nb's superconductivity to the HgTe results in a deeper penetration of the induced superconductivity into the HgTe. Due to this strong coupling it was possible to enter the regime, where a supercurrent is carried through the complete HgTe layer. For the first time the passing of an induced supercurrent through strained bulk HgTe was achieved and thus opened the area for detailed studies. The magnetic dependence of the supercurrent in the JJ was recorded, which is also known as a Fraunhofer pattern. The periodicity of this pattern in magnetic field compared to the JJ geometry allowed to conclude how the junction depends on the phase difference between both superconducting contacts. Theoretical calculations predicted a phase periodicity of 4π instead of 2π, if a TI is used as weak link material between the contacts, due to the presence of Majorana modes. It could clearly be shown that despite the usage of a TI the phase still was 2π periodic. By varying further influencing factors, like number of modes and phase coherence length in the junction, it might still be possible to reach the 4π regime with bound Majorana states in the future. A good candidate for further experiments was found in capped HgTe samples, but here the fabrication process still has to be developed to the same quality as for the uncapped HgTe samples. The second type of geometry studied in this thesis was a DC-SQUID, which consists of two parallel JJs and can also be described as an interference device between two JJs. The DC-SQUID devices were produced in two configurations: The symmetric SQUID, where both JJs were identical, and the asymmetric SQUID, where one JJ was not linear, but instead has a 90 bent. These configurations allow to test, if the predicted uniformity of the superconducting band gap for induced superconductivity in a TI is valid. While the phase of the symmetric SQUID is not influenced by the shape of the band gap, the asymmetric SQUID would

  11. A SEMIOLOGIC APPROACH TO AUDIT EXPECTATIONS GAP

    Directory of Open Access Journals (Sweden)

    Ciolpan Daniela

    2009-05-01

    Full Text Available Audit expectations gap (AEG is one of the most debated phenomena animating the international scientific research scene. The volume of papers focused on defining the AEG concept, examining its determinants, implications, and mechanisms to minimize the gap

  12. Parameters affecting gap detection in the rat.

    Science.gov (United States)

    Leitner, D S; Hammond, G R; Springer, C P; Ingham, K M; Mekilo, A M; Bodison, P R; Aranda, M T; Shawaryn, M A

    1993-09-01

    The present research used a startle amplitude reduction paradigm to investigate the ability of the rat's auditory system to track rapidly changing acoustic transients. Specifically examined was the ability of brief gaps in otherwise continuous noise to reduce the amplitude of a subsequently elicited acoustic startle reflex. The duration of the gap, time between gap offset and startle elicitation (the interstimulus interval or ISI), and rise-fall characteristics of the gap were systematically varied. Consistent with previous research, gaps reliably reduced startle amplitude. Gaps 2 msec long were reliably detected, and a 50-msec ISI resulted in the greatest amplitude reduction. Gaps presented at short ISIs produced amplitude reduction that followed a different time course than did gaps presented at longer ISIs. These results may reflect differences in the length of time available for the processing of the stimulus and may involve two different processes.

  13. The time evolution of gaps in tidal streams

    CERN Document Server

    Helmi, Amina

    2016-01-01

    We model the time evolution of gaps in tidal streams caused by the impact of a dark matter subhalo, while both orbit a spherical gravitational potential. To this end, we make use of the simple behaviour of orbits in action-angle space. A gap effectively results from the divergence of two nearby orbits whose initial phase-space separation is, for very cold thin streams, largely given by the impulse induced by the subhalo. We find that in a spherical potential the size of a gap increases linearly with time, while its density decreases as 1/t^2 for sufficiently long timescales. We have derived an analytic expression that shows how the growth rate depends on the mass of the perturbing subhalo, its scale and its relative velocity with respect to the stream. We have verified these scalings using N-body simulations and find excellent agreement. For example, a subhalo of mass 10^8 Msun directly impacting a very cold thin stream on an inclined orbit can induce a gap that may reach a size of several tens of kpc after a...

  14. The band gap variation of a two dimensional binary locally resonant structure in thermal environment

    Science.gov (United States)

    Li, Zhen; Wang, Xian; Li, Yue-ming

    2017-01-01

    In this study, the numerical investigation of thermal effect on band gap dynamical characteristic for a two-dimensional binary structure composed of aluminum plate periodically filled with nitrile rubber cylinder is presented. Initially, the band gap of the binary structure variation trend with increasing temperature is studied by taking the softening effect of thermal stress into account. A breakthrough is made which found the band gap being narrower and shifting to lower frequency in thermal environment. The complete band gap which in higher frequency is more sensitive to temperature that it disappears with temperature increasing. Then some new transformed models are created by changing the height of nitrile rubber cylinder from 1mm to 7mm. Simulations show that transformed model can produce a wider band gap (either flexure or complete band gap). A proper forbidden gap of elastic wave can be utilized in thermal environment although both flexure and complete band gaps become narrower with temperature. Besides that, there is a zero-frequency flat band appearing in the first flexure band, and it becomes broader with temperature increasing. The band gap width decreases trend in thermal environment, as well as the wider band gap induced by the transformed model with higher nitrile rubber cylinder is useful for the design and application of phononic crystal structures in thermal environment.

  15. The band gap variation of a two dimensional binary locally resonant structure in thermal environment

    Directory of Open Access Journals (Sweden)

    Zhen Li

    2017-01-01

    Full Text Available In this study, the numerical investigation of thermal effect on band gap dynamical characteristic for a two-dimensional binary structure composed of aluminum plate periodically filled with nitrile rubber cylinder is presented. Initially, the band gap of the binary structure variation trend with increasing temperature is studied by taking the softening effect of thermal stress into account. A breakthrough is made which found the band gap being narrower and shifting to lower frequency in thermal environment. The complete band gap which in higher frequency is more sensitive to temperature that it disappears with temperature increasing. Then some new transformed models are created by changing the height of nitrile rubber cylinder from 1mm to 7mm. Simulations show that transformed model can produce a wider band gap (either flexure or complete band gap. A proper forbidden gap of elastic wave can be utilized in thermal environment although both flexure and complete band gaps become narrower with temperature. Besides that, there is a zero-frequency flat band appearing in the first flexure band, and it becomes broader with temperature increasing. The band gap width decreases trend in thermal environment, as well as the wider band gap induced by the transformed model with higher nitrile rubber cylinder is useful for the design and application of phononic crystal structures in thermal environment.

  16. "Explaining the Gender Wage Gap in Georgia"

    OpenAIRE

    Khitarishvili, Tamar

    2009-01-01

    This paper evaluates gender wage differentials in Georgia between 2000 and 2004. Using ordinary least squares, we find that the gender wage gap in Georgia is substantially higher than in other transition countries. Correcting for sample selection bias using the Heckman approach further increases the gender wage gap. The Blinder Oaxaca decomposition results suggest that most of the wage gap remains unexplained. The explained portion of the gap is almost entirely attributed to industrial variab...

  17. Gap Year: Time off, with a Plan

    Science.gov (United States)

    Torpey, Elka Maria

    2009-01-01

    A gap year allows people to step off the usual educational or career path and reassess their future. According to people who have taken a gap year, the time away can be well worth it. This article can help a person decide whether to take a gap year and how to make the most of his time off. It describes what a gap year is, including its pros and…

  18. Closing the Achievement Gap: Four States' Efforts

    Science.gov (United States)

    Wixom, Micah Ann

    2015-01-01

    The achievement gap separating economically disadvantaged students from their more advantaged peers disproportionately affects students of color and has been the focus of discussion, research and controversy for more than 40 years. While the gap between black and white students narrowed considerably from the 1950s to the 1980s, that gap has…

  19. Hyper-active gap filling

    Directory of Open Access Journals (Sweden)

    Akira eOmaki

    2015-04-01

    Full Text Available Much work has demonstrated that speakers of verb-final languages are able to construct rich syntactic representations in advance of verb information. This may reflect general architectural properties of the language processor, or it may only reflect a language-specific adaptation to the demands of verb-finality. The present study addresses this issue by examining whether speakers of a verb-medial language (English wait to consult verb transitivity information before constructing filler-gap dependencies, where internal arguments are fronted and hence precede the verb. This configuration makes it possible to investigate whether the parser actively makes representational commitments on the gap position before verb transitivity information becomes available. A key prediction of the view that rich pre-verbal structure-building is a general architectural property is that speakers of verb-medial languages should predictively construct dependencies in advance of verb transitivity information, and therefore that disruption should be observed when the verb has intransitive subcategorization frames that are incompatible with the predicted structure. In three reading experiments (self-paced and eye-tracking that manipulated verb transitivity, we found evidence for reading disruption when the verb was intransitive, although no such reading difficulty was observed when the critical verb was embedded inside a syntactic island structure, which blocks filler-gap dependency completion. These results are consistent with the hypothesis that in English, as in verb-final languages, information from preverbal NPs is sufficient to trigger active dependency completion without having access to verb transitivity information.

  20. Long-gap esophageal atresia.

    Science.gov (United States)

    Shieh, Hester F; Jennings, Russell W

    2017-04-01

    The management of long-gap esophageal atresia remains challenging with limited consensus on the definition, evaluation, and surgical approach to treatment. Efforts to preserve the native esophagus have been successful with delayed primary anastomosis and tension-based esophageal growth induction processes. Esophageal replacement is necessary in a minority of cases, with the conduit of choice and patient outcomes largely dependent on institutional expertise. Given the complexity of this patient population with significant morbidity, treatment and long-term follow-up are best done in multidisciplinary esophageal and airway treatment centers. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Gap junctions - guards of excitability.

    Science.gov (United States)

    Stroemlund, Line Waring; Jensen, Christa Funch; Qvortrup, Klaus; Delmar, Mario; Nielsen, Morten Schak

    2015-06-01

    Cardiomyocytes are connected by mechanical and electrical junctions located at the intercalated discs (IDs). Although these structures have long been known, it is becoming increasingly clear that their components interact. This review describes the involvement of the ID in electrical disturbances of the heart and focuses on the role of the gap junctional protein connexin 43 (Cx43). Current evidence shows that Cx43 plays a crucial role in organizing microtubules at the intercalated disc and thereby regulating the trafficking of the cardiac sodium channel NaV1.5 to the membrane.

  2. The Emissions Gap Report 2015

    DEFF Research Database (Denmark)

    Following the historic signing of the 2030 Agenda for Sustainable Development, this sixth edition of the UNEP Emissions Gap Report comes as world leaders start gathering in Paris to establish a new agreement on climate change. The report offers an independent assessment of the mitigation contribu...... temperature increases on track to stay below 2°C by the end of the century; it provides data for an aspirational target of keeping that increase below 1.5°C; and it evaluates the INDCs in relation to progress on the 2020 pledges made in Cancun....

  3. Band gaps in bubble phononic crystals

    Directory of Open Access Journals (Sweden)

    V. Leroy

    2016-12-01

    Full Text Available We investigate the interaction between Bragg and hybridization effects on the band gap properties of bubble phononic crystals. These latter consist of air cavities periodically arranged in an elastomer matrix and are fabricated using soft-lithography techniques. Their transmission properties are affected by Bragg effects due to the periodicity of the structure as well as hybridization between the propagating mode of the embedding medium and bubble resonance. The hybridization gap survives disorder while the Bragg gap requires a periodic distribution of bubbles. The distance between two bubble layers can be tuned to make the two gaps overlap or to create a transmission peak in the hybridization gap.

  4. Gap Model for Dual Customer Values

    Institute of Scientific and Technical Information of China (English)

    HOU Lun; TANG Xiaowo

    2008-01-01

    The customer value, the key problem in customer relationship management (CRM), was studied to construct a gap model for dual customer values. A basic description of customer values is given, and then the gaps between products and services in different periods for the customers and companies are analyzed based on the product or service life-cycle. The main factors that influence the perceived customer value were analyzed to define the "recognized value gap" and a gap model for the dual customer values was constructed to supply companies with a tool to analyze existing customer value gaps and improve customer relationship management.

  5. Role of gap junctions on synchronization in human neocortical networks.

    Science.gov (United States)

    Gigout, S; Deisz, R A; Dehnicke, C; Turak, B; Devaux, B; Pumain, R; Louvel, J

    2016-04-15

    Gap junctions (GJ) have been implicated in the synchronization of epileptiform activities induced by 4-aminopyrine (4AP) in slices from human epileptogenic cortex. Previous evidence implicated glial GJ to govern the frequency of these epileptiform events. The synchrony of these events (evaluated by the phase unlocking index, PUI) in adjacent areas however was attributed to neuronal GJ. In the present study, we have investigated the effects of GAP-134, a recently developed specific activator of glial GJ, on both the PUI and the frequency of the 4AP-induced epileptiform activities in human neocortical slices of temporal lobe epilepsy tissue. To delineate the impact of GJ on spatial spread of synchronous activity we evaluated the effects of carbenoxolone (CBX, a non-selective GJ blocker) on the spread in three axes 1. vertically in a given cortical column, 2. laterally within the deep cortical layers and 3. laterally within the upper cortical layers. GAP-134 slightly increased the frequency of the 4AP-induced spontaneous epileptiform activities while leaving the PUI unaffected. CBX had no effect on the PUI within a cortical column or on the PUI in the deep cortical layers. CBX increased the PUI for long interelectrodes distances in the upper cortical layers. In conclusion we provide new arguments toward the role played by glial GJ to maintain the frequency of spontaneous activities. We show that neuronal GJ control the PUI only in upper cortical layers.

  6. Selective permeability of gap junction channels.

    Science.gov (United States)

    Goldberg, Gary S; Valiunas, Virginijus; Brink, Peter R

    2004-03-23

    Gap junctions mediate the transfer of small cytoplasmic molecules between adjacent cells. A family of gap junction proteins exist that form channels with unique properties, and differ in their ability to mediate the transfer of specific molecules. Mutations in a number of individual gap junction proteins, called connexins, cause specific human diseases. Therefore, it is important to understand how gap junctions selectively move molecules between cells. Rules that dictate the ability of a molecule to travel through gap junction channels are complex. In addition to molecular weight and size, the ability of a solute to transverse these channels depends on its net charge, shape, and interactions with specific connexins that constitute gap junctions in particular cells. This review presents some data and interpretations pertaining to mechanisms that govern the differential transfer of signals through gap junction channels.

  7. Terahertz field induced electromigration

    DEFF Research Database (Denmark)

    Strikwerda, Andrew; Zalkovskij, Maksim; Iwaszczuk, Krzysztof;

    We report the first observation of THz-field-induced electromigration in sub-wavelength metallic gap structures after exposure to intense single-cycle, sub-picosecond electric field transients of amplitude up to 400 kV/cm.......We report the first observation of THz-field-induced electromigration in sub-wavelength metallic gap structures after exposure to intense single-cycle, sub-picosecond electric field transients of amplitude up to 400 kV/cm....

  8. 电针联合强制性运动对脑缺血大鼠神经功能及GAP-43表达的影响%Effects of Electroacupuncture and Constraint-Induced Movement Therapy on Neural Function and Expression of Growth-Associated Protein-43 after Middle Cerebral Artery Occlusion in Rats

    Institute of Scientific and Technical Information of China (English)

    樊留博; 章霞; 卢战; 马利中; 田瑛; 王灵芝

    2015-01-01

    目的:探讨电针联合强制性运动对局灶性脑缺血大鼠的不同时间点神经功能评分及灶周生长相关蛋白-43(growth associated protein,GAP-43)表达的影响.方法:将200只SD雄性大鼠按完全随机分组法分为假手术组、模型组、强制性运动(constraint-induced movement therapy,CIMT)组、电针组和电针联合强制性运动组各40只,每组随机分为7d、14 d、21 d、28 d和35 d5个亚组,每个亚组各8只大鼠.采用线栓法制作大脑中动脉阻塞(middle cerebral artery occlusion,MCAO)局灶性脑缺血模型,造模24 h后模型组和正常组动物自然饲养,不作特殊处理,其他组行相应治疗,分别于相应天数进行神经功能缺损评分,随后取脑采用免疫组织化学方法观察每个时间点脑梗死灶周围GAP-43的表达.结果:造模后各时间点电针联合强制性运动组大鼠神经功能缺损评分明显低于模型组、CIMT组和电针组(P<0.01);与模型组比较,CIMT组、电针组在28 d和35 d神经功能缺损评分减低(P<0.05),CIMT组在造模后35 d与电针组神经功能缺损评分比较无统计学差异(P>0.05).电针联合强制性运动组与模型组进行比较,在14、21、28 d时能够显著上调GAP-43表达(P<0.05),且强于CIMT组和电针组(P<0.05);在35 d缺血区周围GAP-43表达增加,但CIMT组和电针组比较无显著性差异(P>0.05).结论:电针联合强制性运动可促进脑梗死灶周围GAP-43的表达,改善大鼠神经功能,可能与缺血损伤神经元的再生和修复有关.

  9. The influence of GAP-43 on orientation of cell division through G proteins.

    Science.gov (United States)

    Huang, Rui; Zhao, Junpeng; Ju, Lili; Wen, Yujun; Xu, Qunyuan

    2015-12-01

    Recent studies have shown that GAP-43 is highly expressed in horizontally dividing neural progenitor cells, and G protein complex are required for proper mitotic-spindle orientation of those progenitors in the mammalian developing cortex. In order to verify the hypothesis that GAP-43 may influence the orientation of cell division through interacting with G proteins during neurogenesis, the GAP-43 RNA from adult C57 mouse was cloned into the pEGFP-N1 vector, which was then transfected into Madin-Darby Canine Kidney (MDCK) cells cultured in a three-dimensional (3D) cell culture system. The interaction of GAP-43 with Gαi was detected by co-immunoprecipitation (co-IP), while cystogenesis of 3D morphogenesis of MDCK cells and expression of GAP-43 and Gαi were determined by immunofluorescence and Western blotting. The results showed are as follows: After being transfected by pEGFP-N1-GAP-43, GAP-43 was localized on the cell membrane and co-localized with Gαi, and this dramatically induced a defective cystogenesis in 3D morphogenesis of MDCK cells. The functional interaction between GAP-43 and Gαi proteins was proven by the co-IP assay. It can be considered from the results that the GAP-43 is involved in the orientation of cell division by interacting with Gαi and this should be an important mechanism for neurogenesis in the mammalian brain. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Updated Starshade Technology Gap List

    Science.gov (United States)

    Crill, Brendan P.; Siegler, Nicholas

    2017-01-01

    NASA's Exoplanet Exploration Program (ExEP) guides the development of technology that enables the direct imaging and characterization of exo-Earths in the habitable zone of their stars, for future space observatories. Here we present the Starshade portion of the 2017 ExEP Enabling Technology Gap List, an annual update to ExEP's list of of technology to be advanced in the next 1-5 years. A Starshade is an external occulter on an independent spacecraft, allowing a space telescope to achieve exo-Earth imaging contrast requirements by blocking starlight before it enters the telescope. Building and operating a Starshade requires new technology: the occulter is a structure tens of meters in diameter that must be positioned precisely at a distance of tens of thousands of kilometers from the telescope. We review the current state-of-the-art performance and the performance level that must be achieved for a Starshade.

  11. The "Efficacy-Effectiveness Gap"

    DEFF Research Database (Denmark)

    Nordon, Clementine; Karcher, Helene; Groenwold, Rolf H H

    2016-01-01

    BACKGROUND: The concept of the "efficacy-effectiveness gap" (EEG) has started to challenge confidence in decisions made for drugs when based on randomized controlled trials alone. Launched by the Innovative Medicines Initiative, the GetReal project aims to improve understanding of how to reconcile...... paradigms, in which EEG is related to 1) real-life characteristics of the health care system; 2) the method used to measure the drug's effect; and 3) a complex interaction between the drug's biological effect and contextual factors. CONCLUSIONS: The third paradigm provides an opportunity to look beyond any...... dichotomy between "standardized" versus "real-life" characteristics of the health care system and study designs. Namely, future research will determine whether the identification of these contextual factors can help to best design randomized controlled trials that provide better estimates of drugs...

  12. Denmark and the gap year

    DEFF Research Database (Denmark)

    Katznelson, Noemi; Juul, Tilde Mette

    2013-01-01

    This paper describes three different educational offers to young people: “The Folk High School”, “The ‘After-school’” and 10th class. All can be considered optional Gap Years. The following diagram shows how the Danish education system is structured. The Folk High School is a training course...... of varying duration (approximately between 12 weeks and 1 year) where one lives at the school. It is primarily located after 12 school year. The ‘After-school’ is a special school structure, were the students also live at the school during their 8th, 9th, or 10th years of primary school. 10th Class...... is a voluntary school year extension of primary school. All three types of schools will be described in more detail in this paper....

  13. GAP-43 expression in retina of neonate rat and induced differentiation of bone marrow mesenchymal stem cells to retinal ganglion-like cells in vitro%GAP-43在新生大鼠视网膜及其诱导的骨髓间充质干细胞向视网膜神经节样细胞分化过程中的表达

    Institute of Scientific and Technical Information of China (English)

    齐首楠; 苏冠方; 王晨光; 王淑荣; 刘早霞

    2010-01-01

    目的 探讨生长相关蛋白43(growth associated protein,GAP-43)在新生大鼠视网膜发育过程中及在以新生大鼠视网膜细胞诱导体外培养的骨髓间充质干细胞(bone marrow mesenchymal stem cell,BMSC)向视网膜神经节样细胞定向分化中的作用.方法 体外培养新生3 d大乳鼠视网膜细胞,应用免疫细胞化学方法检测GAP-43的表达;提取新生大鼠视网膜细胞总RNA,应用RT-PCR方法检测GAP-43 mRNA的表达.体外培养大鼠BMSC至第3代,经流式细胞仪检测干细胞表面标志物进行鉴定,应用乳鼠视网膜细胞诱导BMSC分化,观察诱导后细胞的形态学变化,并应用免疫细胞化学方法对诱导后第5天的细胞进行神经元及视网膜神经节细胞标志物NSE、nestin、GAP-43、thyl.1鉴定,并应用RT-PCR的方法检测、分析GAP-43 mRNA的表达情况.结果 体外培养的新生大乳鼠视网膜细胞应用免疫细胞化学方法可检测到GAP43阳性表达;RT-PcR方法检测到新生大鼠的GAP-43 mRNA的表达;第3代BMSC经流式细胞仪检测CD71(+)、C LY29(+)、CD34(-)、CD45(-),经与大乳鼠视网膜细胞共培养的方法可诱导BMSC分化为视网膜神经节样细胞,免疫细胞化学染色表明其表达特异性标志物NSE、nestin、GAP-43、thyl.1,分化后的神经节样细胞内可检测到GAP-43 mRNA阳性表达:结论本研究结果显示CAP-43不仅参与了大鼠视网膜发育过程,且GAP-43在以乳鼠视网膜细胞诱导BMsc定向分化为视网膜神经节样细胞这一过程中具有重要意义.

  14. Anomalous Temperature Dependence of the Band Gap in Black Phosphorus.

    Science.gov (United States)

    Villegas, Cesar E P; Rocha, A R; Marini, Andrea

    2016-08-10

    Black phosphorus (BP) has gained renewed attention due to its singular anisotropic electronic and optical properties that might be exploited for a wide range of technological applications. In this respect, the thermal properties are particularly important both to predict its room temperature operation and to determine its thermoelectric potential. From this point of view, one of the most spectacular and poorly understood phenomena is indeed the BP temperature-induced band gap opening; when temperature is increased, the fundamental band gap increases instead of decreases. This anomalous thermal dependence has also been observed recently in its monolayer counterpart. In this work, based on ab initio calculations, we present an explanation for this long known and yet not fully explained effect. We show that it arises from a combination of harmonic and lattice thermal expansion contributions, which are in fact highly interwined. We clearly narrow down the mechanisms that cause this gap opening by identifying the peculiar atomic vibrations that drive the anomaly. The final picture we give explains both the BP anomalous band gap opening and the frequency increase with increasing volume (tension effect).

  15. Prediction of Gap Asymmetry in Differential Micro Accelerometers

    Directory of Open Access Journals (Sweden)

    Xiaoping He

    2012-05-01

    Full Text Available Gap asymmetry in differential capacitors is the primary source of the zero bias output of force-balanced micro accelerometers. It is also used to evaluate the applicability of differential structures in MEMS manufacturing. Therefore, determining the asymmetry level has considerable significance for the design of MEMS devices. This paper proposes an experimental-theoretical method for predicting gap asymmetry in differential sensing capacitors of micro accelerometers. The method involves three processes: first, bi-directional measurement, which can sharply reduce the influence of the feedback circuit on bias output, is proposed. Experiments are then carried out on a centrifuge to obtain the input and output data of an accelerometer. Second, the analytical input-output relationship of the accelerometer with gap asymmetry and circuit error is theoretically derived. Finally, the prediction methodology combines the measurement results and analytical derivation to identify the asymmetric error of 30 accelerometers fabricated by DRIE. Results indicate that the level of asymmetry induced by fabrication uncertainty is about ±5 × 10−2, and that the absolute error is about ±0.2 µm under a 4 µm gap.

  16. Giant Hall Photoconductivity in Narrow-Gapped Dirac Materials.

    Science.gov (United States)

    Song, Justin C W; Kats, Mikhail A

    2016-12-14

    Carrier dynamics acquire a new character in the presence of Bloch-band Berry curvature, which naturally arises in gapped Dirac materials (GDMs). Here, we argue that photoresponse in GDMs with small band gaps is dramatically enhanced by Berry curvature. This manifests in a giant and saturable Hall photoconductivity when illuminated by circularly polarized light. Unlike Hall motion arising from a Lorentz force in a magnetic field, which impedes longitudinal carrier motion, Hall photoconductivity arising from Berry curvature can boost longitudinal carrier transport. In GDMs, this results in a helicity-dependent photoresponse in the Hall regime, where photoconductivity is dominated by its Hall component. We find that the induced Hall conductivity per incident irradiance is enhanced by up to 6 orders of magnitude when moving from the visible regime (with corresponding band gaps) to the far infrared. These results suggest that narrow-gap GDMs are an ideal test-bed for the unique physics that arise in the presence of Berry curvature and open a new avenue for infrared and terahertz optoelectronics.

  17. Temperature and magnetization-dependent band-gap renormalization and optical many-body effects in diluted magnetic semiconductors

    OpenAIRE

    2005-01-01

    We calculate the Coulomb interaction induced density, temperature and magnetization dependent many-body band-gap renormalization in a typical diluted magnetic semiconductor GaMnAs in the optimally-doped metallic regime as a function of carrier density and temperature. We find a large (about 0.1 eV) band gap renormalization which is enhanced by the ferromagnetic transition. We also calculate the impurity scattering effect on the gap narrowing. We suggest that the temperature, magnetization, an...

  18. [Gap edge effect of Castanopsis kawakamii community].

    Science.gov (United States)

    Liu, Jinfu; Hong, Wei; Li, Junqing; Lin, Rongfu

    2003-09-01

    This paper reported the characters of gap edge effect of Castanopsis kawakamii community in Sanming, Fujian Province. The species diversity, ecological dominance, and edge effect strength of 38 forest gaps with different development stages in different stands of Castanopsis kawakamii community were measured, and Shannon-Wiener index, Simpson index, and index of edge effect strength were calculated. The results showed that the index of the gap edge effect of Castanopsis kawakamii community was about 0.7-1.3 (according to the species diversity index) and 0.3-1.8 (according to the ecological dominance index). The gap edge effect had the trend of increasing the species diversity of forest communities. The index of gap effect was affected by the size and development stage of the gap and the related forest type. The study provided a theoretical basis for the maintenance of species diversity and the forest management in Castanopsis kawakamii community.

  19. National GAP Conference 2007-Discussion Groups Report

    Science.gov (United States)

    Ratz, Joan M.; Lamb, Berton Lee

    2010-01-01

    We led two discussion groups during the 2007 National GAP Conference. These discussion groups provided information to help develop a survey of National Gap Analysis Program (GAP) data users. One group discussed technical issues, and the second group discussed the use of GAP data for decisionmaking. Themes emerging from the technical issues group included concerns about data quality, need for information on how to use data, and passive data distribution. The decisionmaking discussion included a wide range of topics including the need to understand presentation of information, the need to connect with and understand users of data, the revision of GAP's mission, and the adaptability of products and data. The decisionmaking group also raised concerns regarding technical issues. One conclusion is that a deep commitment to ongoing information transfer and support is a key component of success for the GAP program.

  20. Angle-resolved photoemission studies of the superconducting gap symmetry in Fe-based superconductors

    Directory of Open Access Journals (Sweden)

    Y.-B. Huang

    2012-12-01

    Full Text Available The superconducting gap is the fundamental parameter that characterizes the superconducting state, and its symmetry is a direct consequence of the mechanism responsible for Cooper pairing. Here we discuss about angle-resolved photoemission spectroscopy measurements of the superconducting gap in the Fe-based high-temperature superconductors. We show that the superconducting gap is Fermi surface dependent and nodeless with small anisotropy, or more precisely, a function of the momentum location in the Brillouin zone. We show that while this observation seems inconsistent with weak coupling approaches for superconductivity in these materials, it is well supported by strong coupling models and global superconducting gaps. We also suggest that a smaller lifetime of the superconducting Cooper pairs induced by the momentum dependent interband scattering inherent to these materials could affect the residual density of states at low energies, which is critical for a proper evaluation of the superconducting gap.

  1. Forensics of Subhalo-Stream Encounters: The Three Phases of Gap Growth

    CERN Document Server

    Erkal, Denis

    2014-01-01

    There is hope to discover dark matter subhalos free of stars (predicted by the current theory of structure formation) by observing gaps they produce in tidal streams. In fact, this is the most promising technique for dark substructure detection and characterization as such gaps grow with time and hence become more observable by ongoing and planned Galaxy surveys. To facilitate such future inference, we develop a comprehensive framework for studies of the growth of the stream density perturbations. Starting with simple assumptions, we derive analytic formulae that describe the evolution of all gap properties (size, density contrast etc) at all times. We uncover complex, previously unnoticed behavior, with the stream initially forming a density enhancement near the subhalo impact point. Shortly after, a gap forms due to the relative change in period induced by the subhalo's passage. There is an intermediate regime where the gap grows linearly in time. At late times, the particles in the stream overtake each oth...

  2. The Immigrant Wage Gap in Germany

    OpenAIRE

    Stephan L. Thomsen; Gernandt, Johannes; Aldashev, Alisher

    2008-01-01

    Immigrants consist of foreigners and citizens with migration background. We analyze the wage gap between natives and these two groups in Germany. The estimates show a substantial gap for both groups with respect to natives. Discarding immigrants who completed education abroad reduces much of the immigrants' wage gap. This implies educational attainment in Germany is an important component of economic integration and degrees obtained abroad are valued less.

  3. PBX 9502 air-gap tests

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, Peter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Novak, Alan M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Foley, Timothy J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Campbell, Christopher Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-29

    A small number of simple air-gap tests were performed on 1-inch diameter PBX 9502 cylinders to determine an approximate threshold for detonation failure. The primary diagnostics were streak imaging and dent measurements in a steel witness plate. Relight was found to occur, with negligible excess transit time, for air gaps up to 1 mm. Relight did not occur with a 3-mm air gap.

  4. Wavelet description of the Glottal Gap

    OpenAIRE

    Gómez Vilda, Pedro; Nieto Lluis, Victor; Rodellar Biarge, M. Victoria; Martínez Olalla, Rafael; Muñoz Mulas, Cristina Elena; Álvarez Marquina, Agustin; Mazaira Fernández, Luis Miguel; Scola Yurrita, Bartolomé; Ramírez Calvo, Carlos; Poletti Serafini,Daniel

    2013-01-01

    The Glottal Source correlates reconstructed from the phonated parts of voice may render interesting information with applicability in different fields. One of them is defective closure (gap) detection. Through the paper the background to explain the physical foundations of defective gap are reviewed. A possible method to estimate defective gap is also presented based on a Wavelet Description of the Glottal Source. The method is validated using results from the analysis of a gender-balanced sp...

  5. Gap between active and passive solar heating

    Energy Technology Data Exchange (ETDEWEB)

    Balcomb, J.D.

    1985-01-01

    The gap between active and passive solar could hardly be wider. The reasons for this are discussed and advantages to narrowing the gap are analyzed. Ten years of experience in both active and passive systems are reviewed, including costs, frequent problems, performance prediction, performance modeling, monitoring, and cooling concerns. Trends are analyzed, both for solar space heating and for service water heating. A tendency for the active and passive technologies to be converging is observed. Several recommendations for narrowing the gap are presented.

  6. Structural Dynamics of Tropical Moist Forest Gaps

    Science.gov (United States)

    Hunter, Maria O.; Keller, Michael; Morton, Douglas; Cook, Bruce; Lefsky, Michael; Ducey, Mark; Saleska, Scott; de Oliveira, Raimundo Cosme; Schietti, Juliana

    2015-01-01

    Gap phase dynamics are the dominant mode of forest turnover in tropical forests. However, gap processes are infrequently studied at the landscape scale. Airborne lidar data offer detailed information on three-dimensional forest structure, providing a means to characterize fine-scale (1 m) processes in tropical forests over large areas. Lidar-based estimates of forest structure (top down) differ from traditional field measurements (bottom up), and necessitate clear-cut definitions unencumbered by the wisdom of a field observer. We offer a new definition of a forest gap that is driven by forest dynamics and consistent with precise ranging measurements from airborne lidar data and tall, multi-layered tropical forest structure. We used 1000 ha of multi-temporal lidar data (2008, 2012) at two sites, the Tapajos National Forest and Ducke Reserve, to study gap dynamics in the Brazilian Amazon. Here, we identified dynamic gaps as contiguous areas of significant growth, that correspond to areas > 10 m2, with height <10 m. Applying the dynamic definition at both sites, we found over twice as much area in gap at Tapajos National Forest (4.8 %) as compared to Ducke Reserve (2.0 %). On average, gaps were smaller at Ducke Reserve and closed slightly more rapidly, with estimated height gains of 1.2 m y-1 versus 1.1 m y-1 at Tapajos. At the Tapajos site, height growth in gap centers was greater than the average height gain in gaps (1.3 m y-1 versus 1.1 m y-1). Rates of height growth between lidar acquisitions reflect the interplay between gap edge mortality, horizontal ingrowth and gap size at the two sites. We estimated that approximately 10 % of gap area closed via horizontal ingrowth at Ducke Reserve as opposed to 6 % at Tapajos National Forest. Height loss (interpreted as repeat damage and/or mortality) and horizontal ingrowth accounted for similar proportions of gap area at Ducke Reserve (13 % and 10 %, respectively). At Tapajos, height loss had a much stronger signal (23

  7. Structural Dynamics of Tropical Moist Forest Gaps.

    Directory of Open Access Journals (Sweden)

    Maria O Hunter

    Full Text Available Gap phase dynamics are the dominant mode of forest turnover in tropical forests. However, gap processes are infrequently studied at the landscape scale. Airborne lidar data offer detailed information on three-dimensional forest structure, providing a means to characterize fine-scale (1 m processes in tropical forests over large areas. Lidar-based estimates of forest structure (top down differ from traditional field measurements (bottom up, and necessitate clear-cut definitions unencumbered by the wisdom of a field observer. We offer a new definition of a forest gap that is driven by forest dynamics and consistent with precise ranging measurements from airborne lidar data and tall, multi-layered tropical forest structure. We used 1000 ha of multi-temporal lidar data (2008, 2012 at two sites, the Tapajos National Forest and Ducke Reserve, to study gap dynamics in the Brazilian Amazon. Here, we identified dynamic gaps as contiguous areas of significant growth, that correspond to areas > 10 m2, with height <10 m. Applying the dynamic definition at both sites, we found over twice as much area in gap at Tapajos National Forest (4.8% as compared to Ducke Reserve (2.0%. On average, gaps were smaller at Ducke Reserve and closed slightly more rapidly, with estimated height gains of 1.2 m y-1 versus 1.1 m y-1 at Tapajos. At the Tapajos site, height growth in gap centers was greater than the average height gain in gaps (1.3 m y-1 versus 1.1 m y-1. Rates of height growth between lidar acquisitions reflect the interplay between gap edge mortality, horizontal ingrowth and gap size at the two sites. We estimated that approximately 10% of gap area closed via horizontal ingrowth at Ducke Reserve as opposed to 6% at Tapajos National Forest. Height loss (interpreted as repeat damage and/or mortality and horizontal ingrowth accounted for similar proportions of gap area at Ducke Reserve (13% and 10%, respectively. At Tapajos, height loss had a much stronger signal

  8. Forests and Forest Cover - Green Infrastructure Gaps

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — These data provide restoration value rankings and ecological attributes associated with green infrastructure gaps. The Green Infrastructure Assessment was developed...

  9. Structural Dynamics of Tropical Moist Forest Gaps.

    Science.gov (United States)

    Hunter, Maria O; Keller, Michael; Morton, Douglas; Cook, Bruce; Lefsky, Michael; Ducey, Mark; Saleska, Scott; de Oliveira, Raimundo Cosme; Schietti, Juliana

    2015-01-01

    Gap phase dynamics are the dominant mode of forest turnover in tropical forests. However, gap processes are infrequently studied at the landscape scale. Airborne lidar data offer detailed information on three-dimensional forest structure, providing a means to characterize fine-scale (1 m) processes in tropical forests over large areas. Lidar-based estimates of forest structure (top down) differ from traditional field measurements (bottom up), and necessitate clear-cut definitions unencumbered by the wisdom of a field observer. We offer a new definition of a forest gap that is driven by forest dynamics and consistent with precise ranging measurements from airborne lidar data and tall, multi-layered tropical forest structure. We used 1000 ha of multi-temporal lidar data (2008, 2012) at two sites, the Tapajos National Forest and Ducke Reserve, to study gap dynamics in the Brazilian Amazon. Here, we identified dynamic gaps as contiguous areas of significant growth, that correspond to areas > 10 m2, with height <10 m. Applying the dynamic definition at both sites, we found over twice as much area in gap at Tapajos National Forest (4.8%) as compared to Ducke Reserve (2.0%). On average, gaps were smaller at Ducke Reserve and closed slightly more rapidly, with estimated height gains of 1.2 m y-1 versus 1.1 m y-1 at Tapajos. At the Tapajos site, height growth in gap centers was greater than the average height gain in gaps (1.3 m y-1 versus 1.1 m y-1). Rates of height growth between lidar acquisitions reflect the interplay between gap edge mortality, horizontal ingrowth and gap size at the two sites. We estimated that approximately 10% of gap area closed via horizontal ingrowth at Ducke Reserve as opposed to 6% at Tapajos National Forest. Height loss (interpreted as repeat damage and/or mortality) and horizontal ingrowth accounted for similar proportions of gap area at Ducke Reserve (13% and 10%, respectively). At Tapajos, height loss had a much stronger signal (23% versus 6

  10. Undecidability of the Spectral Gap (short version)

    CERN Document Server

    Cubitt, Toby; Wolf, Michael M

    2015-01-01

    The spectral gap -- the difference in energy between the ground state and the first excited state -- is one of the most important properties of a quantum many-body system. Quantum phase transitions occur when the spectral gap vanishes and the system becomes critical. Much of physics is concerned with understanding the phase diagrams of quantum systems, and some of the most challenging and long-standing open problems in theoretical physics concern the spectral gap, such as the Haldane conjecture that the Heisenberg chain is gapped for integer spin, proving existence of a gapped topological spin liquid phase, or the Yang-Mills gap conjecture (one of the Millennium Prize problems). These problems are all particular cases of the general spectral gap problem: Given a quantum many-body Hamiltonian, is the system it describes gapped or gapless? Here we show that this problem is undecidable, in the same sense as the Halting Problem was proven to be undecidable by Turing. A consequence of this is that the spectral gap...

  11. Band gap engineering of indium zinc oxide by nitrogen incorporation

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, J.J., E-mail: jjosila@hotmail.com [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad esq. Paseo la Bufa, Fracc. Progreso, C.P. 98060 Zacatecas (Mexico); Doctorado Institucional de Ingeniería y Ciencia de Materiales, Universidad Autónoma de San Luis Potosí, Av. Salvador Nava, Zona Universitaria, C.P. 78270 San Luis Potosí (Mexico); Aguilar-Frutis, M.A.; Alarcón, G. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del Instituto Politécnico Nacional, Unidad Legaría, Calz. Legaría No. 694, Col. Irrigación, C.P. 11500 México D.F. (Mexico); Falcony, C. [Departamento de Física, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional campus Zacatenco, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, C.P. 07360 México D.F. (Mexico); and others

    2014-09-15

    Highlights: • IZON thin films were deposited by RF reactive sputtering at room temperature. • The effects of nitrogen on physical properties of IZO were analyzed. • Optical properties of IZON were studied by SE and UV–vis spectroscopy. • Adachi and classical parameters were quantitative and qualitatively congruent. • Nitrogen induces a gradual narrowing band gap from 3.5 to 2.5 eV on IZON films. - Abstract: The effects of nitrogen incorporation in indium zinc oxide films, as grown by RF reactive magnetron sputtering, on the structural, electrical and optical properties were studied. It was determined that the variation of the N{sub 2}/Ar ratio, in the reactive gas flux, was directly proportional to the nitrogen percentage measured in the sample, and the incorporated nitrogen, which substituted oxygen in the films induces changes in the band gap of the films. This phenomenon was observed by measurement of absorption and transmission spectroscopy in conjunction with spectral ellipsometry. To fit the ellipsometry spectra, the classical and Adachi dispersion models were used. The obtained optical parameters presented notable changes related to the increment of the nitrogen in the film. The band gap narrowed from 3.5 to 2.5 eV as the N{sub 2}/Ar ratio was increased. The lowest resistivity obtained for these films was 3.8 × 10{sup −4} Ω cm with a carrier concentration of 5.1 × 10{sup 20} cm{sup −3}.

  12. Two-phase Cryogenic Avalanche Detector with electroluminescence gap operated in argon doped with nitrogen

    CERN Document Server

    Bondar, A; Dolgov, A; Nosov, V; Shekhtman, L; Shemyakina, E; Sokolov, A

    2016-01-01

    A two-phase Cryogenic Avalanche Detector (CRAD) with electroluminescence (EL) gap, operated in argon doped with a minor (49$\\pm$7 ppm) admixture of nitrogen, has been studied. The EL gap was optically read out using cryogenic PMTs located on the perimeter of the gap. We present the results of the measurements of the N$_2$ content, detector sensitivity to X-ray-induced signals, EL gap yield and electron lifetime in the liquid. The detector sensitivity, at a drift field in liquid Ar of 0.6 kV/cm, was measured to be 9 and 16 photoelectrons recorded at the PMTs per keV of deposited energy at 23 and 88 keV respectively. Such two-phase detectors, with enhanced sensitivity to the S2 (ionization-induced) signal, are relevant in the field of argon detectors for dark matter search and low energy neutrino detection.

  13. Two-phase Cryogenic Avalanche Detector with electroluminescence gap operated in argon doped with nitrogen

    Science.gov (United States)

    Bondar, A.; Buzulutskov, A.; Dolgov, A.; Nosov, V.; Shekhtman, L.; Shemyakina, E.; Sokolov, A.

    2017-02-01

    A two-phase Cryogenic Avalanche Detector (CRAD) with electroluminescence (EL) gap, operated in argon doped with a minor (49±7 ppm) admixture of nitrogen, has been studied. The EL gap was optically read out using cryogenic PMTs located on the perimeter of the gap. We present the results of the measurements of the N2 content, detector sensitivity to X-ray-induced signals, EL gap yield and electron lifetime in the liquid. The detector sensitivity, at a drift field in liquid Ar of 0.6 kV/cm, was measured to be 9 and 16 photoelectrons recorded at the PMTs per keV of deposited energy at 23 and 88 keV respectively. Such two-phase detectors, with enhanced sensitivity to the S2 (ionization-induced) signal, are relevant in the field of argon detectors for dark matter search and low energy neutrino detection.

  14. Methamphetamine compromises gap junctional communication in astrocytes and neurons.

    Science.gov (United States)

    Castellano, Paul; Nwagbo, Chisom; Martinez, Luis R; Eugenin, Eliseo A

    2016-05-01

    Methamphetamine (meth) is a central nervous system (CNS) stimulant that results in psychological and physical dependency. The long-term effects of meth within the CNS include neuronal plasticity changes, blood-brain barrier compromise, inflammation, electrical dysfunction, neuronal/glial toxicity, and an increased risk to infectious diseases including HIV. Most of the reported meth effects in the CNS are related to dysregulation of chemical synapses by altering the release and uptake of neurotransmitters, especially dopamine, norepinephrine, and epinephrine. However, little is known about the effects of meth on connexin (Cx) containing channels, such as gap junctions (GJ) and hemichannels (HC). We examined the effects of meth on Cx expression, function, and its role in NeuroAIDS. We found that meth altered Cx expression and localization, decreased GJ communication between neurons and astrocytes, and induced the opening of Cx43/Cx36 HC. Furthermore, we found that these changes in GJ and HC induced by meth treatment were mediated by activation of dopamine receptors, suggesting that dysregulation of dopamine signaling induced by meth is essential for GJ and HC compromise. Meth-induced changes in GJ and HC contributed to amplified CNS toxicity by dysregulating glutamate metabolism and increasing the susceptibility of neurons and astrocytes to bystander apoptosis induced by HIV. Together, our results indicate that connexin containing channels, GJ and HC, are essential in the pathogenesis of meth and increase the sensitivity of the CNS to HIV CNS disease. Methamphetamine (meth) is an extremely addictive central nervous system stimulant. Meth reduced gap junctional (GJ) communication by inducing internalization of connexin-43 (Cx43) in astrocytes and reducing expression of Cx36 in neurons by a mechanism involving activation of dopamine receptors (see cartoon). Meth-induced changes in Cx containing channels increased extracellular levels of glutamate and resulted in higher

  15. GAP-ANALYSIS METHODS USAGE FOR DISTRIBUTION LOGISTICS SYSTEM EFFICIENCY APPRAISAL

    OpenAIRE

    Markovskiy Vladimir Andreevich

    2012-01-01

    The article is dedicated to the appraisal of distribution logistics system efficiency problem, which is induced by lack of coordination of its elements. The aim of the article is to determine criteria for lack of logistics distribution systems efficiency. Novelty of the article is in applying GAP-analysis method to logistics distribution macrosystems, which allowed to propose a calculation method for informing about the presence of gaps in the logistics system. It is revea...

  16. Gap Junction Enhancer Potentiates Cytotoxicity of Cisplatin in Breast Cancer Cells

    OpenAIRE

    Ding, Ying; Nguyen, Thu Annelise

    2012-01-01

    Cisplatin is one of the most widely used anti-cancer drugs due to its ability to damage DNA and induce apoptosis. However, increasing reports of side effects and drug resistance indicate the limitation of cisplatin in cancer therapeutics. Recent studies showed that inhibition of gap junctions diminishes the cytotoxic effect and contributes to drug resistance. Therefore, identification of molecules that counteract gap junctional inhibition without decreasing the anti-cancer effect of cisplatin...

  17. Tunable mode-locked laser with micro-air gap cavity

    Science.gov (United States)

    Ahmad, H.; Aidit, S. N.; Hassan, N. A.; Ooi, S. I.; Tiu, Z. C.

    2017-02-01

    A tunable mode-locked laser with a micro-air gap cavity acting as a high resolution tuning is proposed and demonstrated. The laser utilizes the nonlinear polarization technique in the cavity to obtain a reliable and stable mode locking over the whole tuning range at a resolution of 1 nm. The micro-air gap is constructed by aligning two fiber facets coaxially, and the variation of micro-air gap introduces a tuning mechanism where it changes the gain saturation compensation in the gain medium and thus induces wavelength shifting on the generated solitons.

  18. Air-gap Limitations and Bypass Techniques: “Command and Control” using Smart Electromagnetic Interferences

    Directory of Open Access Journals (Sweden)

    Chaouki Kasmi

    2016-01-01

    Full Text Available Air gaps are generally considered to be a very efficient information security protection. However, this technique also showed limitations, involving finding covert channels for bridging the air gap. Interestingly, recent publications have pointed out that a smart use of the intentional electromagnetic interferences introduced new threats for information security. In this paper, an innovative way for remotely communicating with a malware already installed on a computer by involving the induced perturbations is discussed leading to the design of a new air gap bridging covert channel.

  19. Gender gap and polarisation of physics on global courses

    CERN Document Server

    Alinea, Allan L

    2016-01-01

    We extend on previous research on the Force Concept Inventory (FCI) given to first year classical mechanics students (N=66 students, over four years) pre and post score, for students on an international (global) course at Osaka University. In particular, we revisit the notion of "polarisation" in connection with the six polarisation-inducing questions in the FCI and examine its gender aspect. Our data suggest that this phenomenon is not unique to one gender. Furthermore, the extent by which it is exhibited by males may differ from that of females at the beginning (pretest) but the gap closes upon learning more about forces (posttest). These findings are for the most part, complemented by our result for the FCI as a whole. Although the differences in means for males and females suggest a gender gap, statistical analysis shows that there is no gender difference at the 95% confidence level.

  20. Can the inner gap sparking take place in millisecond pulsars?

    Institute of Scientific and Technical Information of China (English)

    Hong-Guang Wang; Guo-Jun Qiao; Ren-Xin Xu

    2003-01-01

    The inner vacuum gap model has become the foundation stone of most theories on pulsar radio emission. The fundamental picture of this model is the sparking, which was conjectured to be induced by magnetic absorption of background gamma photons. However, a question is, can the sparking be triggered in the millisecond pulsars (MSPs) with magnetic fields (B) only about 10s G? We investigate this problem by including the pair production above the inner gap. Under the assumption that the magnetic field is dipolar, our results show the background gamma-ray emission can not be the key factor that triggers the sparking, at least not in MSPs with B ~ 108 G, if the temperature in the polar cap region is only so high as is observed (< 4 × 106 K). Some other mechanisms are required.

  1. Role of gap junctions and hemichannels in parasitic infections.

    Science.gov (United States)

    Vega, José Luis; Subiabre, Mario; Figueroa, Felipe; Schalper, Kurt Alex; Osorio, Luis; González, Jorge; Sáez, Juan Carlos

    2013-01-01

    In vertebrates, connexins (Cxs) and pannexins (Panxs) are proteins that form gap junction channels and/or hemichannels located at cell-cell interfaces and cell surface, respectively. Similar channel types are formed by innexins in invertebrate cells. These channels serve as pathways for cellular communication that coordinate diverse physiologic processes. However, it is known that many acquired and inherited diseases deregulate Cx and/or Panx channels, condition that frequently worsens the pathological state of vertebrates. Recent evidences suggest that Cx and/or Panx hemichannels play a relevant role in bacterial and viral infections. Nonetheless, little is known about the role of Cx- and Panx-based channels in parasitic infections of vertebrates. In this review, available data on changes in Cx and gap junction channel changes induced by parasitic infections are summarized. Additionally, we describe recent findings that suggest possible roles of hemichannels in parasitic infections. Finally, the possibility of new therapeutic designs based on hemichannel blokers is presented.

  2. Mind the gap - tip leakage vortex in axial turbines

    Science.gov (United States)

    Dreyer, M.; Decaix, J.; Münch-Alligné, C.; Farhat, M.

    2014-03-01

    The tendency of designing large Kaplan turbines with a continuous increase of output power is bringing to the front the cavitation erosion issue. Due to the flow in the gap between the runner and the discharge ring, axial turbine blades may develop the so called tip leakage vortex (TLV) cavitation with negative consequences. Such vortices may interact strongly with the wake of guide vanes leading to their multiple collapses and rebounds. If the vortex trajectory remains close to the blade tip, these collapses may lead to severe erosion. One is still unable today to predict its occurrence and development in axial turbines with acceptable accuracy. Numerical flow simulations as well as the actual scale-up rules from small to large scales are unreliable. The present work addresses this problematic in a simplified case study representing TLV cavitation to better understand its sensitivity to the gap width. A Naca0009 hydrofoil is used as a generic blade in the test section of EPFL cavitation tunnel. A sliding mounting support allowing an adjustable gap between the blade tip and wall was manufactured. The vortex trajectory is visualized with a high speed camera and appropriate lighting. The three dimensional velocity field induced by the TLV is investigated using stereo particle image velocimetry. We have taken into account the vortex wandering in the image processing to obtain accurate measurements of the vortex properties. The measurements were performed in three planes located downstream of the hydrofoil for different values of the flow velocity, the incidence angle and the gap width. The results clearly reveal a strong influence of the gap width on both trajectory and intensity of the tip leakage vortex.

  3. Effect of air gap variation on the performance of single stator single rotor axial flux permanent magnet generator

    Science.gov (United States)

    Kasim, Muhammad; Irasari, Pudji; Hikmawan, M. Fathul; Widiyanto, Puji; Wirtayasa, Ketut

    2017-02-01

    The axial flux permanent magnet generator (AFPMG) has been widely used especially for electricity generation. The effect of the air gap variation on the characteristic and performances of single rotor - single stator AFPMG has been described in this paper. Effect of air gap length on the magnetic flux distribution, starting torque and MMF has been investigated. The two dimensional finite element magnetic method has been deployed to model and simulated the characteristics of the machine which is based on the Maxwell equation. The analysis has been done for two different air gap lengths which were 2 mm and 4 mm using 2D FEMM 4.2 software at no load condition. The increasing of air gap length reduces the air-gap flux density. For air gap 2 mm, the maximum value of the flux density was 1.04 T while 0.73 T occured for air gap 4 mm.. Based on the experiment result, the increasing air gap also reduced the starting torque of the machine with 39.2 Nm for air gap 2 mm and this value decreased into 34.2 Nm when the air gap increased to 4 mm. Meanwhile, the MMF that was generated by AFPMG decreased around 22% at 50 Hz due to the reduction of magnetic flux induced on stator windings. Overall, the research result showed that the variation of air gap has significant effect on the machine characteristics.

  4. Forensics of subhalo-stream encounters: the three phases of gap growth

    Science.gov (United States)

    Erkal, Denis; Belokurov, Vasily

    2015-06-01

    There is hope to discover dark matter subhaloes free of stars (predicted by the current theory of structure formation) by observing gaps they produce in tidal streams. In fact, this is the most promising technique for dark substructure detection and characterization as such gaps grow with time, magnifying small perturbations into clear signatures observable by ongoing and planned Galaxy surveys. To facilitate such future inference, we develop a comprehensive framework for studies of the growth of the stream density perturbations. Starting with simple assumptions and restricting to streams on circular orbits, we derive analytic formulae that describe the evolution of all gap properties (size, density contrast, etc.) at all times. We uncover complex, previously unnoticed behaviour, with the stream initially forming a density enhancement near the subhalo impact point. Shortly after, a gap forms due to the relative change in period induced by the subhalo's passage. There is an intermediate regime where the gap grows linearly in time. At late times, the particles in the stream overtake each other, forming caustics, and the gap grows like √{t}. In addition to the secular growth, we find that the gap oscillates as it grows due to epicyclic motion. We compare this analytic model to N-body simulations and find an impressive level of agreement. Importantly, when analysing the observation of a single gap we find a large degeneracy between the subhalo mass, the impact geometry and kinematics, the host potential, and the time since flyby.

  5. Technology--The New Gender Gap.

    Science.gov (United States)

    Weinman, Janice; Cain, Lisa

    1999-01-01

    Focuses on the gender gap in computer science and discusses results from a new report, "Gender Gaps," by the American Association of University Women. Examines technology's impact on gender equity and the importance of teacher education. Notes the increased enrollment of girls in math and science and calls for new programs to increase…

  6. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the best-studied

  7. The Wage Gap and Administrative Salaries Today.

    Science.gov (United States)

    Beyer, Kirk D.

    1992-01-01

    Analysis of national data on college administrator salaries by gender, minority/nonminority status, years of service, and institution type found that wage gaps related to gender and minority status persisted in 1991-92 but that interaction of length of service with other study variables explained a significant amount of this gap. (MSE)

  8. Estimating Gender Wage Gaps: A Data Update

    Science.gov (United States)

    McDonald, Judith A.; Thornton, Robert J.

    2016-01-01

    In the authors' 2011 "JEE" article, "Estimating Gender Wage Gaps," they described an interesting class project that allowed students to estimate the current gender earnings gap for recent college graduates using data from the National Association of Colleges and Employers (NACE). Unfortunately, since 2012, NACE no longer…

  9. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the

  10. String matching with variable length gaps

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Vildhøj, Hjalte Wedel

    2012-01-01

    We consider string matching with variable length gaps. Given a string T and a pattern P consisting of strings separated by variable length gaps (arbitrary strings of length in a specified range), the problem is to find all ending positions of substrings in T that match P. This problem is a basic...

  11. PhoneGap 3 beginner's guide

    CERN Document Server

    Natili, Giorgio

    2013-01-01

    Written in a friendly, example-driven Beginner's Guide format, there are plenty of step-by-step instructions to help you get started with PhoneGap.If you are a web developer or mobile application developer interested in an examples-based approach to learning mobile application development basics with PhoneGap, then this book is for you.

  12. Band Gaps of an Amorphous Photonic Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Yi-Quan; FENG Zhi-Fang; HU Xiao-Yong; CHENG Bing-Ying; ZHANG Dao-Zhong

    2004-01-01

    @@ A new kind of amorphous photonic materials is presented. Both the simulated and experimental results show that although the disorder of the whole dielectric structure is strong, the amorphous photonic materials have two photonic gaps. This confirms that the short-range order is an essential factor for the formation of the photonic gaps.

  13. Intersectionopoly: A Simulation of the Wage Gap

    Science.gov (United States)

    Paino, Maria; May, Matthew; Burrington, Lori A.; Becker, Jacob H.

    2017-01-01

    This article describes a simulation activity designed to teach students about the wage gap. The wage gap is an important topic in many sociology classrooms, but it can be difficult to convey the accumulated disadvantage experienced by women and racial/ethnic minorities to students using in-class discussions, lectures, or assigned readings alone.…

  14. Caring Closes the Language-Learning Gap

    Science.gov (United States)

    Borba, Mary

    2009-01-01

    The gap in academic achievement between English speakers and English learners continues to concern educators, parents, and legislators. Rising expectations for literacy and the increasing number of students from diverse backgrounds contribute to this achievement gap. In this article, the author discusses a variety of strategies for reaching out to…

  15. Predicting the optical gap of conjugated systems

    Science.gov (United States)

    Botelho, Andre Leitao

    The adapted Su-Schrieffer-Heeger model is developed in this work as a tool for in silico prediction of the optical gap of pi-conjugated systems for photovoltaic applications. Full transferability of the model ensures reliable predictive power - excellent agreement with 180 independent experimental data points covering virtually all existing conjugated system types with an accuracy exceeding the time-dependent density functional theory, one of the most accurate first-principles methods. Insights on the structure-property relation of conjugated systems obtained from the model lead to guiding rules for optical gap design: 1) fusing aromatic rings parallel to the conjugated path does not significantly lower the optical gap, 2) fusing rings perpendicularly lowers the optical gap of the monomer, but has a reduced benefit from polymerization, and 3) copolymers take advantage of the lower optical gap of perpendicular fused rings and benefit from further optical gap reduction through added parallel fused rings as electronic communicators. A copolymer of parallel and perpendicular benzodithiophenes, differing only in sulfur atom locations, is proposed as a candidate to achieve the optimal 1.2 eV donor optical gap for organic photovoltaics. For small-molecule organic photovoltaics, substituting the end pairs of carbon atoms on pentacene with sulfur atoms is predicted to lower the optical gap from 1.8 eV to 1.1 eV. Furthermore, the model offers an improvement of orders of magnitude in the computational efficiency over commonly used first-principles tools.

  16. Delaying the Academy: A Gap Year Education

    Science.gov (United States)

    O'Shea, Joseph

    2011-01-01

    This investigation serves as one of the first empirical analyses to examine the international volunteering gap year from an educational perspective, concluding an in-depth case study of a prominent gap year organisation in the UK. Contrary to widespread industry promotion of international development, the findings suggest that the experience can…

  17. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the best-studied

  18. Closing the Gender Gap: Act Now

    Science.gov (United States)

    OECD Publishing (NJ3), 2012

    2012-01-01

    Gender gaps are pervasive in all walks of economic life and imply large losses in terms of foregone productivity and living standards to the individuals concerned and the economy. This new OECD report focuses on how best to close these gender gaps under four broad headings: (1) Gender equality, social norms and public policies; and gender equality…

  19. Optical response and excitons in gapped graphene

    DEFF Research Database (Denmark)

    Pedersen, Thomas Garm; Jauho, Antti-Pekka; Pedersen, K.

    2009-01-01

    Graphene can be rendered semiconducting via energy gaps introduced in a variety of ways, e.g., coupling to substrates, electrical biasing, or nanostructuring. To describe and compare different realizations of gapped graphene we propose a simple two-band model in which a "mass" term is responsible...

  20. Low band gap polymers for organic photovoltaics

    DEFF Research Database (Denmark)

    Bundgaard, Eva; Krebs, Frederik C

    2007-01-01

    Low band gap polymer materials and their application in organic photovoltaics (OPV) are reviewed. We detail the synthetic approaches to low band gap polymer materials starting from the early methodologies employing quinoid homopolymer structures to the current state of the art that relies...... in photovoltaic applications and give a tabular overview of rarely applied materials....

  1. The "Developing" Achievement Gap: Colombian Voucher Reform

    Science.gov (United States)

    Stern, Jonathan M. B.

    2014-01-01

    The achievement gap in many developing countries is defined in terms of rich/poor and public/private. The prevailing explanation for the "developing" achievement gap is an underfunded, inefficient, and/or inadequately supplied public school sector. Via an analysis of a Colombian voucher experiment, this article examines the extent to…

  2. School Choice and the Achievement Gap

    Science.gov (United States)

    Jeynes, William H.

    2014-01-01

    The possibility is examined that school choice programs could be a means to reducing the achievement gap. Data based on meta-analytic research and the examination of nationwide data sets suggest that school choice programs that include private schools could reduce the achievement gap by 25%. The propounding of this possibility is based on research…

  3. Spin susceptibility of disordered gapped graphene systems

    Science.gov (United States)

    Grosu, I.; Biter, T. L.

    2017-02-01

    We calculate the spin susceptibility for the case of gapped graphene systems in the presence of disorder. The average single-particle density of states in gapped graphene with disorder was calculated, using the Born and the T-matrix approximations. The temperature dependence of the static spin susceptibility was analyzed. The influence of the chemical potential position and disorder is also discussed.

  4. Delaying the Academy: A Gap Year Education

    Science.gov (United States)

    O'Shea, Joseph

    2011-01-01

    This investigation serves as one of the first empirical analyses to examine the international volunteering gap year from an educational perspective, concluding an in-depth case study of a prominent gap year organisation in the UK. Contrary to widespread industry promotion of international development, the findings suggest that the experience can…

  5. Closing the Prescription Drug Coverage Gap

    Science.gov (United States)

    ... drugs they make are covered during the coverage gap for that calendar year. This includes prescription drugs on the plan’s formulary ( ... you pay for generic drugs during the coverage gap will decrease each year until it reaches 25% in 2020. The coverage ...

  6. THE TECHNOLOGY GAP: ANALYSIS AND APPRAISAL

    Science.gov (United States)

    The paper considers the following five points: First, the technological gap is a meaningful concept, and the phenomenon probably is real. Second, it...is nothing new; something like a technological gap between the United States and Europe has existed for upwards of one hundred years. Third, what is

  7. Superconducting gap structure of FeSe.

    Science.gov (United States)

    Jiao, Lin; Huang, Chien-Lung; Rößler, Sahana; Koz, Cevriye; Rößler, Ulrich K; Schwarz, Ulrich; Wirth, Steffen

    2017-03-07

    The microscopic mechanism governing the zero-resistance flow of current in some iron-based, high-temperature superconducting materials is not well understood up to now. A central issue concerning the investigation of these materials is their superconducting gap symmetry and structure. Here we present a combined study of low-temperature specific heat and scanning tunnelling microscopy measurements on single crystalline FeSe. The results reveal the existence of at least two superconducting gaps which can be represented by a phenomenological two-band model. The analysis of the specific heat suggests significant anisotropy in the gap magnitude with deep gap minima. The tunneling spectra display an overall "U"-shaped gap close to the Fermi level away as well as on top of twin boundaries. These results are compatible with the anisotropic nodeless models describing superconductivity in FeSe.

  8. Antideuteron Sensitivity for the GAPS Experiment

    CERN Document Server

    Aramaki, T; Boggs, S E; von Doetinchem, P; Fuke, H; Mognet, S I; Ong, R A; Perez, K; Zweerink, J

    2015-01-01

    The General Antiparticle Spectrometer (GAPS) is a novel approach for indirect dark matter searches that exploits cosmic antiparticles, especially antideuterons. The GAPS antideuteron measurement utilizes distinctive detection methods using atomic X-rays and charged particles from the decay of exotic atoms as well as the timing and stopping range of the incoming particle, which together provide excellent antideuteron identification. Prior to the future balloon experiment, an accelerator test and a prototype flight were successfully conducted in 2005 and 2012 respectively, in order to verify the GAPS detection concept. This paper describes how the sensitivity of GAPS to antideuterons was estimated using a Monte Carlo simulation along with the atomic cascade model and the Intra-Nuclear Cascade model. The sensitivity for the GAPS antideuteron search obtained using this method is 2.0 $\\times 10^{-6}$ [m$^{-2}$s$^{-1}$sr$^{-1}$(GeV/$n$)$^{-1}$] for the proposed long duration balloon program (LDB, 35 days $\\times$ 3...

  9. Terminology gap in hydrological cycle

    Science.gov (United States)

    Zhuo, Lu; Han, Dawei

    2016-04-01

    Water is central to life on Earth. People have been trying to understand how water moves in the hydrosphere throughout the human history. In the 9th century BC, the famous Greek poet Homer described the hydrological cycle in Iliad as "okeanos whose stream bends back in a circle" with a belief that rivers are ocean-fed from subterranean seas. Later, Aristotle (4th century BC) claimed that most of the water came from underground caverns in which air was transformed into water. It was only until 1674, French scientist Perrault developed the correct concept of the water cycle. In modern times, scientists are interested in understanding the individual processes of the hydrological cycle with a keen focus on runoff which supplies water to rivers, lakes, and oceans. Currently, the prevailing concepts on runoff processes include 'infiltration excess runoff' and 'saturation excess runoff'. However, there is no term to describe another major runoff due to the excess beyond the soil water holding capacity (i.e., the field capacity). We argue that a new term should be introduced to fill this gap, and it could be called 'holding excess runoff' which is compatible with the convention. This new term is significant in correcting a half-century misnomer where 'holding excess runoff' has been incorrectly named as 'saturation excess runoff', which was introduced by the Xinanjiang model in China in 1960s. Similar concept has been adopted in many well-known hydrological models such as PDM and HBV in which the saturation refers to the field capacity. The term 'holding excess runoff' resolves such a common confusion in the hydrological community.

  10. Quantifying Audit Expectation Gap: A New approach to Measuring Expectation Gap

    Directory of Open Access Journals (Sweden)

    Salehi Mahdi

    2016-05-01

    Full Text Available The main objective of the study is at first identifying the expectation gap about audit responsibility and the second quantifying the expectation gap in Iran. In order to collecting data, a questionnaire designed and developed between auditors and investors. Collected data analyzed by employing non-parametric statistics test. The results show that there is expectation gap between auditors and investors in Iran. The current study employed a new approach in the world in order to quantifying the expectation gap. It gives the more strength to other researchers in order to measuring audit expectation gap in the world.

  11. Traction force dynamics predict gap formation in activated endothelium.

    Science.gov (United States)

    Valent, Erik T; van Nieuw Amerongen, Geerten P; van Hinsbergh, Victor W M; Hordijk, Peter L

    2016-09-10

    In many pathological conditions the endothelium becomes activated and dysfunctional, resulting in hyperpermeability and plasma leakage. No specific therapies are available yet to control endothelial barrier function, which is regulated by inter-endothelial junctions and the generation of acto-myosin-based contractile forces in the context of cell-cell and cell-matrix interactions. However, the spatiotemporal distribution and stimulus-induced reorganization of these integral forces remain largely unknown. Traction force microscopy of human endothelial monolayers was used to visualize contractile forces in resting cells and during thrombin-induced hyperpermeability. Simultaneously, information about endothelial monolayer integrity, adherens junctions and cytoskeletal proteins (F-actin) were captured. This revealed a heterogeneous distribution of traction forces, with nuclear areas showing lower and cell-cell junctions higher traction forces than the whole-monolayer average. Moreover, junctional forces were asymmetrically distributed among neighboring cells. Force vector orientation analysis showed a good correlation with the alignment of F-actin and revealed contractile forces in newly formed filopodia and lamellipodia-like protrusions within the monolayer. Finally, unstable areas, showing high force fluctuations within the monolayer were prone to form inter-endothelial gaps upon stimulation with thrombin. To conclude, contractile traction forces are heterogeneously distributed within endothelial monolayers and force instability, rather than force magnitude, predicts the stimulus-induced formation of intercellular gaps. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Confined PBX 9501 gap reinitiation studies

    Energy Technology Data Exchange (ETDEWEB)

    Salyer, Terry R [Los Alamos National Laboratory; Hill, Larry G [Los Alamos National Laboratory; Lam, Kin [Los Alamos National Laboratory

    2009-01-01

    For explosive systems that exhibit gaps or cracks between their internal components (either by design or mechanical failure), measurable time delays exist for detonation waves crossing them. Reinitiation across such gaps is dependent on the type of explosive, gap width, gap morphology, confinement, and temperature effects. To examine this reinitiation effect, a series of tests has been conducted to measure the time delay across a prescribed gap within an 'infinitely' confined PBX 9501 system. Detonation breakout along the explosive surface is measured with a streak camera, and flow features are examined during reinitiation near the gap. Such tests allow for quantitative determination of the time delay corresponding to the time of initiation across a given gap oriented normal to the direction of the detonation wave. Measured time delays can be compared with numerical calculations, making it possible to validate initiation models as well as estimate detonation run-up distances. Understanding this reinitiation behavior is beneficial for the design and evaluation of explosive systems that require precision timing and performance.

  13. Flow Induced Noise from Turbulent Flow over Steps and Gaps

    Science.gov (United States)

    2010-05-04

    HP-8D20 is housed inside of a casing constructed of medium density fiberboard, MDF , and pushes air into a settling chamber consisting of...settling chamber is constructed of MDF with square steel tubing along the outside for support as the settling chamber pressurizes during operation...is housed inside of a removable acoustic enclosure of dimension 2.13 by 2.43 by 4.06 m. This enclosure is constructed of MDF and square steel

  14. Carrier concentration dependence of band gap shift in n-type ZnO:Al films

    Science.gov (United States)

    Lu, J. G.; Fujita, S.; Kawaharamura, T.; Nishinaka, H.; Kamada, Y.; Ohshima, T.; Ye, Z. Z.; Zeng, Y. J.; Zhang, Y. Z.; Zhu, L. P.; He, H. P.; Zhao, B. H.

    2007-04-01

    Al-doped ZnO (AZO) thin films have been prepared by mist chemical vapor deposition and magnetron sputtering. The band gap shift as a function of carrier concentration in n-type zinc oxide (ZnO) was systematically studied considering the available theoretical models. The shift in energy gap, evaluated from optical absorption spectra, did not depend on sample preparations; it was mainly related to the carrier concentrations and so intrinsic to AZO. The optical gap increased with the electron concentration approximately as ne2/3 for ne≤4.2×1019 cm-3, which could be fully interpreted by a modified Burstein-Moss (BM) shift with the nonparabolicity of the conduction band. A sudden decrease in energy gap occurred at 5.4-8.4×1019 cm-3, consistent with the Mott criterion for a semiconductor-metal transition. Above the critical values, the band gap increased again at a different rate, which was presumably due to the competing BM band-filling and band gap renormalization effects, the former inducing a band gap widening and the latter an offsetting narrowing. The band gap narrowing (ΔEBGN) derived from the band gap renormalization effect did not show a good ne1/3 dependence predicated by a weakly interacting electron-gas model, but it was in excellent agreement with a perturbation theory considering different many-body effects. Based on this theory a simple expression, ΔEBGN=Ane1/3+Bne1/4+Cne1/2, was deduced for n-type ZnO, as well as p-type ZnO, with detailed values of A, B, and C coefficients. An empirical relation once proposed for heavily doped Si could also be used to describe well this gap narrowing in AZO.

  15. Abort Gap Cleaning for LHC Run 2

    Energy Technology Data Exchange (ETDEWEB)

    Uythoven, Jan [CERN; Boccardi, Andrea [CERN; Bravin, Enrico [CERN; Goddard, Brennan [CERN; Hemelsoet, Georges-Henry [CERN; Höfle, Wolfgang [CERN; Jacquet, Delphine [CERN; Kain, Verena [CERN; Mazzoni, Stefano [CERN; Meddahi, Malika [CERN; Valuch, Daniel [CERN; Gianfelice-Wendt, Eliana [Fermilab

    2014-07-01

    To minimize the beam losses at the moment of an LHC beam dump the 3 μs long abort gap should contain as few particles as possible. Its population can be minimised by abort gap cleaning using the LHC transverse damper system. The LHC Run 1 experience is briefly recalled; changes foreseen for the LHC Run 2 are presented. They include improvements in the observation of the abort gap population and the mechanism to decide if cleaning is required, changes to the hardware of the transverse dampers to reduce the detrimental effect on the luminosity lifetime and proposed changes to the applied cleaning algorithms.

  16. One-Dimensional Anisotropic Band Gap Structure

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The band gap structure of one-dimensional anisotropic photonic crystal has been studied by means of the transfer matrix formalism. From the analytic expressions and numeric calculations we see some general characteristics of the band gap structure of anisotropic photonic crystals, each band separates into two branches and the two branches react to polarization sensitively. In the practical case of oblique incidence, gaps move towards high frequency when the angle of incidence increases. Under some special conditions, the two branches become degenerate again.

  17. Method for Bubbledeck Concrete Slab with Gaps

    Directory of Open Access Journals (Sweden)

    Sergiu Călin

    2009-01-01

    Full Text Available The composite slabs are made of BubbleDeck type slab elements with spherical gaps, poured in place on transversal and longitudinal directions. By introducing the gaps leads to a 30...50\\% lighter slab which reduces the loads on the columns, walls and foundations, and of course of the entire building. BubbleDeck slab elements are plates with ribs on two directions made of reinforced concrete or precast concrete with spherical shaped bubbles. These slab elements have a bottom and an upper concrete part connected with vertical ribs that go around the gaps.

  18. Refractive Indices of Semiconductors from Energy gaps

    CERN Document Server

    Tripathy, S K

    2015-01-01

    An empirical relation based on energy gap and refractive index data has been proposed in the present study to calculate the refractive index of semiconductors. The proposed model is then applied to binary as well as ternary semiconductors for a wide range of energy gap. Using the relation, dielectric constants of some III-V group semiconductors are calculated. The calculated values for different group of binary semiconductors, alkali halides and ternary semiconductors fairly agree with other calculations and known values over a wide range of energy gap. The temperature variation of refractive index for some binary semiconductors have been calculated.

  19. LHC Abort Gap Monitoring and Cleaning

    CERN Document Server

    Meddahi, M; Boccardi, A; Butterworth, A; Fisher, A S; Gianfelice-Wendt, E; Goddard, B; Hemelsoet, G H; Höfle, W; Jacquet, D; Jaussi, M; Kain, V; Lefevre, T; Shaposhnikova, E; Uythoven, J; Valuch, D

    2010-01-01

    Unbunched beam is a potentially serious issue in the LHC as it may quench the superconducting magnets during a beam abort. Unbunched particles, either not captured by the RF system at injection or leaking out of the RF bucket, will be removed by using the existing damper kickers to excite resonantly the particles in the abort gap. Following beam simulations, a strategy for cleaning the abort gap at different energies was proposed. The plans for the commissioning of the beam abort gap cleaning are described and first results from the beam commissioning are presented.

  20. A gap clearing kicker for Main Injector

    CERN Document Server

    Kourbanis, I; Biggs, J; Brown, B; Capista, D; Jensen, C C; Krafczyk, G E; Morris, D K; Scott, D; Seiya, K; Ward, S R; Wu, G; Yang, M -J

    2012-01-01

    Fermilab Main Injector has been operating at high Beam Power levels since 2008 when multi-batch slip stacking became operational. In order to maintain and increase the beam power levels the localized beam loss due to beam left over in the injection kicker gap during slip stacking needs to be addressed. A set of gap clearing kickers that kick any beam left in the injection gap to the beam abort have been built. The kickers were installed in the summer of 2009 and became operational in November of 2010. The kicker performance and its effect on the beam losses will be described.

  1. Abort Gap Cleaning for LHC Run 2

    CERN Document Server

    Uythoven, J; Bravin, E; Goddard, B; Hemelsoet, GH; Höfle, W; Jacquet, D; Kain, V; Mazzoni, S; Meddahi, M; Valuch, D

    2015-01-01

    To minimise the beam losses at the moment of an LHC beam dump the 3 μs long abort gap should contain as few particles as possible. Its population can be minimised by abort gap cleaning using the LHC transverse damper system. The LHC Run 1 experience is briefly recalled; changes foreseen for the LHC Run 2 are presented. They include improvements in the observation of the abort gap population and the mechanism to decide if cleaning is required, changes to the hardware of the transverse dampers to reduce the detrimental effect on the luminosity lifetime and proposed changes to the applied cleaning algorithms.

  2. Determining the nature of the gap in semiconducting graphene

    Science.gov (United States)

    Prestigiacomo, J. C.; Nath, A.; Osofsky, M. S.; Hernández, S. C.; Wheeler, V. D.; Walton, S. G.; Gaskill, D. K.

    2017-01-01

    Since its discovery, graphene has held great promise as a two-dimensional (2D) metal with massless carriers and, thus, extremely high-mobility that is due to the character of the band structure that results in the so-called Dirac cone for the ideal, perfectly ordered crystal structure. This promise has led to only limited electronic device applications due to the lack of an energy gap which prevents the formation of conventional device geometries. Thus, several schemes for inducing a semiconductor band gap in graphene have been explored. These methods do result in samples whose resistivity increases with decreasing temperature, similar to the temperature dependence of a semiconductor. However, this temperature dependence can also be caused by highly diffusive transport that, in highly disordered materials, is caused by Anderson-Mott localization and which is not desirable for conventional device applications. In this letter, we demonstrate that in the diffusive case, the conventional description of the insulating state is inadequate and demonstrate a method for determining whether such transport behavior is due to a conventional semiconductor band gap. PMID:28181521

  3. Determining the nature of the gap in semiconducting graphene

    Science.gov (United States)

    Prestigiacomo, J. C.; Nath, A.; Osofsky, M. S.; Hernández, S. C.; Wheeler, V. D.; Walton, S. G.; Gaskill, D. K.

    2017-02-01

    Since its discovery, graphene has held great promise as a two-dimensional (2D) metal with massless carriers and, thus, extremely high-mobility that is due to the character of the band structure that results in the so-called Dirac cone for the ideal, perfectly ordered crystal structure. This promise has led to only limited electronic device applications due to the lack of an energy gap which prevents the formation of conventional device geometries. Thus, several schemes for inducing a semiconductor band gap in graphene have been explored. These methods do result in samples whose resistivity increases with decreasing temperature, similar to the temperature dependence of a semiconductor. However, this temperature dependence can also be caused by highly diffusive transport that, in highly disordered materials, is caused by Anderson-Mott localization and which is not desirable for conventional device applications. In this letter, we demonstrate that in the diffusive case, the conventional description of the insulating state is inadequate and demonstrate a method for determining whether such transport behavior is due to a conventional semiconductor band gap.

  4. ArfGAP1 function in COPI mediated membrane traffic: currently debated models and comparison to other coat-binding ArfGAPs.

    Science.gov (United States)

    Shiba, Yoko; Randazzo, Paul A

    2012-09-01

    The ArfGAPs are a family of proteins containing an ArfGAP catalytic domain that induces the hydrolysis of GTP bound to the small guanine nucleotide binding-protein ADP-ribosylation factor (Arf). Functional models for Arfs, which are regulators of membrane traffic, are based on the idea that guanine nucleotide-binding proteins function as switches: Arf with GTP bound is active and binds to effector proteins; the conversion of GTP to GDP inactivates Arf. The cellular activities of ArfGAPs have been examined primarily as regulatory proteins that inactivate Arf; however, Arf function in membrane traffic does not strictly adhere to the concept of a simple switch, adding complexity to models explaining the role of ArfGAPs. Here, we review the literature addressing the function Arf and ArfGAP1 in COPI mediated transport, focusing on two critical and integrated functions of membrane traffic, cargo sorting and vesicle coat polymerization. We briefly discuss other ArfGAPs that may have similar function in Arf-dependent membrane traffic outside the ER-Golgi.

  5. Gap Junction Enhancer Potentiates Cytotoxicity of Cisplatin in Breast Cancer Cells.

    Science.gov (United States)

    Ding, Ying; Nguyen, Thu Annelise

    2012-11-01

    Cisplatin is one of the most widely used anti-cancer drugs due to its ability to damage DNA and induce apoptosis. However, increasing reports of side effects and drug resistance indicate the limitation of cisplatin in cancer therapeutics. Recent studies showed that inhibition of gap junctions diminishes the cytotoxic effect and contributes to drug resistance. Therefore, identification of molecules that counteract gap junctional inhibition without decreasing the anti-cancer effect of cisplatin could be used in combinational treatment, potentiating cisplatin efficacy and preventing resistance. This study investigates the effects of combinational treatment of cisplatin and PQ1, a gap junction enhancer, in T47D breast cancer cells. Our results showed that combinational treatment of PQ1 and cisplatin increased gap junctional intercellular communication (GJIC) as well as expressions of connexins (Cx26, Cx32 and Cx43), and subsequently decreased cell viability. Ki67, a proliferation marker, was decreased by 75% with combinational treatment. Expressions of pro-apoptotic factors (cleaved caspase-3/-8/-9 and bax) were increased by the combinational treatment with PQ1 and cisplatin; whereas, the pro-survival factor, bcl-2, was decreased by the combinational treatment. Our study demonstrates for the first time that the combinational treatment with gap junction enhancers can counteract cisplatin induced inhibition of gap junctional intercellular communication and reduction of connexin expression, thereby increasing the efficacy of cisplatin in cancer cells.

  6. A photonic thermalization gap in disordered lattices

    CERN Document Server

    Kondakci, H E; Saleh, B E A

    2016-01-01

    The formation of gaps -- forbidden ranges in the values of a physical parameter -- is a ubiquitous feature of a variety of physical systems: from energy bandgaps of electrons in periodic lattices and their analogs in photonic, phononic, and plasmonic systems to pseudo energy gaps in aperiodic quasicrystals. Here, we report on a `thermalization' gap for light propagating in finite disordered structures characterized by disorder-immune chiral symmetry -- the appearance of the eigenvalues and eigenvectors in skew-symmetric pairs. In this class of systems, the span of sub- thermal photon statistics is inaccessible to input coherent light, which -- once the steady state is reached -- always emerges with super-thermal statistics no matter how small the disorder level. We formulate an independent constraint that must be satisfied by the input field for the chiral symmetry to be `activated' and the gap to be observed. This unique feature enables a new form of photon-statistics interferometry: the deterministic tuning...

  7. Globalization and the Gender Wage Gap

    National Research Council Canada - National Science Library

    Remco H. Oostendorp

    There are several theoretical reasons why globalization will have a narrowing as well as a widening effect on the gender wage gap, but little is known about the actual impact, except for some country studies...

  8. Device Physics of Narrow Gap Semiconductors

    CERN Document Server

    Chu, Junhao

    2010-01-01

    Narrow gap semiconductors obey the general rules of semiconductor science, but often exhibit extreme features of these rules because of the same properties that produce their narrow gaps. Consequently these materials provide sensitive tests of theory, and the opportunity for the design of innovative devices. Narrow gap semiconductors are the most important materials for the preparation of advanced modern infrared systems. Device Physics of Narrow Gap Semiconductors offers descriptions of the materials science and device physics of these unique materials. Topics covered include impurities and defects, recombination mechanisms, surface and interface properties, and the properties of low dimensional systems for infrared applications. This book will help readers to understand not only the semiconductor physics and materials science, but also how they relate to advanced opto-electronic devices. The last chapter applies the understanding of device physics to photoconductive detectors, photovoltaic infrared detector...

  9. Sustainability Tools Inventory - Initial Gaps Analysis

    Science.gov (United States)

    This report identifies a suite of tools that address a comprehensive set of community sustainability concerns. The objective is to discover whether "gaps" exist in the tool suite’s analytic capabilities. These tools address activities that significantly influenc...

  10. Multi Band Gap High Efficiency Converter (RAINBOW)

    Science.gov (United States)

    Bekey, I.; Lewis, C.; Phillips, W.; Shields, V.; Stella, P.

    1997-01-01

    The RAINBOW multi band gap system represents a unique combination of solar cells, concentrators and beam splitters. RAINBOW is a flexible system which can readily expand as new high efficiency components are developed.

  11. School Segregation and Racial Academic Achievement Gaps

    Directory of Open Access Journals (Sweden)

    Sean F. Reardon

    2016-09-01

    Full Text Available Although it is clear that racial segregation is linked to academic achievement gaps, the mechanisms underlying this link have been debated since James Coleman published his eponymous 1966 report. In this paper, I examine sixteen distinct measures of segregation to determine which is most strongly associated with academic achievement gaps. I find clear evidence that one aspect of segregation in particular—the disparity in average school poverty rates between white and black students’ schools—is consistently the single most powerful correlate of achievement gaps, a pattern that holds in both bivariate and multivariate analyses. This implies that high-poverty schools are, on average, much less effective than lower-poverty schools and suggests that strategies that reduce the differential exposure of black, Hispanic, and white students to poor schoolmates may lead to meaningful reductions in academic achievement gaps.

  12. Gap Junctions in the Ventral Hippocampal-Medial Prefrontal Pathway Are Involved in Anxiety Regulation

    Science.gov (United States)

    Schoenfeld, Timothy J.; Kloth, Alexander D.; Hsueh, Brian; Runkle, Matthew B.; Kane, Gary A.; Wang, Samuel S.-H.

    2014-01-01

    Anxiety disorders are highly prevalent but little is known about their underlying mechanisms. Gap junctions exist in brain regions important for anxiety regulation, such as the ventral hippocampus (vHIP) and mPFC, but their functions in these areas have not been investigated. Using pharmacological blockade of neuronal gap junctions combined with electrophysiological recordings, we found that gap junctions play a role in theta rhythm in the vHIP and mPFC of adult mice. Bilateral infusion of neuronal gap junction blockers into the vHIP decreased anxiety-like behavior on the elevated plus maze and open field. Similar anxiolytic effects were observed with unilateral infusion of these drugs into the vHIP combined with contralateral infusion into the mPFC. No change in anxious behavior was observed with gap junction blockade in the unilateral vHIP alone or in the bilateral dorsal HIP. Since physical exercise is known to reduce anxiety, we examined the effects of long-term running on the expression of the neuronal gap junction protein connexin-36 among inhibitory interneurons and found a reduction in the vHIP. Despite this change, we observed no alteration in theta frequency or power in long-term runners. Collectively, these findings suggest that neuronal gap junctions in the vHIP–mPFC pathway are important for theta rhythm and anxiety regulation under sedentary conditions but that additional mechanisms are likely involved in running-induced reduction in anxiety. PMID:25411496

  13. Closing Yield Gaps: How Sustainable Can We Be?

    Directory of Open Access Journals (Sweden)

    Prajal Pradhan

    Full Text Available Global food production needs to be increased by 60-110% between 2005 and 2050 to meet growing food and feed demand. Intensification and/or expansion of agriculture are the two main options available to meet the growing crop demands. Land conversion to expand cultivated land increases GHG emissions and impacts biodiversity and ecosystem services. Closing yield gaps to attain potential yields may be a viable option to increase the global crop production. Traditional methods of agricultural intensification often have negative externalities. Therefore, there is a need to explore location-specific methods of sustainable agricultural intensification. We identified regions where the achievement of potential crop calorie production on currently cultivated land will meet the present and future food demand based on scenario analyses considering population growth and changes in dietary habits. By closing yield gaps in the current irrigated and rain-fed cultivated land, about 24% and 80% more crop calories can respectively be produced compared to 2000. Most countries will reach food self-sufficiency or improve their current food self-sufficiency levels if potential crop production levels are achieved. As a novel approach, we defined specific input and agricultural management strategies required to achieve the potential production by overcoming biophysical and socioeconomic constraints causing yield gaps. The management strategies include: fertilizers, pesticides, advanced soil management, land improvement, management strategies coping with weather induced yield variability, and improving market accessibility. Finally, we estimated the required fertilizers (N, P2O5, and K2O to attain the potential yields. Globally, N-fertilizer application needs to increase by 45-73%, P2O5-fertilizer by 22-46%, and K2O-fertilizer by 2-3 times compared to the year 2010 to attain potential crop production. The sustainability of such agricultural intensification largely depends

  14. Structural Dynamics of Tropical Moist Forest Gaps

    OpenAIRE

    Hunter, Maria O.; Michael Keller; Douglas Morton; Bruce Cook; Michael Lefsky; Mark Ducey; Scott Saleska; Raimundo Cosme de Oliveira; Juliana Schietti

    2015-01-01

    Gap phase dynamics are the dominant mode of forest turnover in tropical forests. However, gap processes are infrequently studied at the landscape scale. Airborne lidar data offer detailed information on three-dimensional forest structure, providing a means to characterize fine-scale (1 m) processes in tropical forests over large areas. Lidar-based estimates of forest structure (top down) differ from traditional field measurements (bottom up), and necessitate clear-cut definitions unencumbered...

  15. Columbia River Component Data Gap Analysis

    Energy Technology Data Exchange (ETDEWEB)

    L. C. Hulstrom

    2007-10-23

    This Data Gap Analysis report documents the results of a study conducted by Washington Closure Hanford (WCH) to compile and reivew the currently available surface water and sediment data for the Columbia River near and downstream of the Hanford Site. This Data Gap Analysis study was conducted to review the adequacy of the existing surface water and sediment data set from the Columbia River, with specific reference to the use of the data in future site characterization and screening level risk assessments.

  16. Gap Waves in Piezoelectric layered Medium

    Directory of Open Access Journals (Sweden)

    Danoyan Z.N.

    2007-03-01

    Full Text Available In the present paper the conditions of existence of shear electroelastic gap waves in piezoelectric-vacuum-dielectric layered system are found. It is shown that in the discontact layered system the gap electroelastic waves can be propagated. It is considered the limiting case when the thickness of vacuuming layer tends to zero. It is proved that the statement of the problem is true when there is no acoustic contact between piezoelectric and dielectric grounded media.

  17. Modification in band gap of zirconium complexes

    Science.gov (United States)

    Sharma, Mayank; Singh, J.; Chouhan, S.; Mishra, A.; Shrivastava, B. D.

    2016-05-01

    The optical properties of zirconium complexes with amino acid based Schiff bases are reported here. The zirconium complexes show interesting stereo chemical features, which are applicable in organometallic and organic synthesis as well as in catalysis. The band gaps of both Schiff bases and zirconium complexes were obtained by UV-Visible spectroscopy. It was found that the band gap of zirconium complexes has been modified after adding zirconium compound to the Schiff bases.

  18. Gap junction communication in myelinating glia.

    Science.gov (United States)

    Nualart-Marti, Anna; Solsona, Carles; Fields, R Douglas

    2013-01-01

    Gap junction communication is crucial for myelination and axonal survival in both the peripheral nervous system (PNS) and central nervous system (CNS). This review examines the different types of gap junctions in myelinating glia of the PNS and CNS (Schwann cells and oligodendrocytes respectively), including their functions and involvement in neurological disorders. Gap junctions mediate intercellular communication among Schwann cells in the PNS, and among oligodendrocytes and between oligodendrocytes and astrocytes in the CNS. Reflexive gap junctions mediating transfer between different regions of the same cell promote communication between cellular compartments of myelinating glia that are separated by layers of compact myelin. Gap junctions in myelinating glia regulate physiological processes such as cell growth, proliferation, calcium signaling, and participate in extracellular signaling via release of neurotransmitters from hemijunctions. In the CNS, gap junctions form a glial network between oligodendrocytes and astrocytes. This transcellular communication is hypothesized to maintain homeostasis by facilitating restoration of membrane potential after axonal activity via electrical coupling and the re-distribution of potassium ions released from axons. The generation of transgenic mice for different subsets of connexins has revealed the contribution of different connexins in gap junction formation and illuminated new subcellular mechanisms underlying demyelination and cognitive defects. Alterations in metabolic coupling have been reported in animal models of X-linked Charcot-Marie-Tooth disease (CMTX) and Pelizaeus-Merzbarcher-like disease (PMLD), which are caused by mutations in the genes encoding for connexin 32 and connexin 47 respectively. Future research identifying the expression and regulation of gap junctions in myelinating glia is likely to provide a better understanding of myelinating glia in nervous system function, plasticity, and disease. This

  19. Explaining personality pay gaps in the UK

    OpenAIRE

    Nandi, Alita; Nicoletti, Cheti

    2009-01-01

    Using the British Household Panel Survey we examine how the Big Five personality traits - openness to experience, conscientiousness, extroversion, agreeableness, and neuroticism - affect wages. We estimate mean and quantile pay gaps between people with low and high levels of each of the Big Five, and decompose these pay gaps in the part explained by differences in workers’ characteristics and in the residual unexplained part. We find that openness to experience is the most relevant personal...

  20. Light transmission through a triangular air gap

    CERN Document Server

    Carvalho, Silvania A

    2013-01-01

    Due to the recent interest in studying propagation of light through triangular air gaps, we calculate, by using the analogy between optics and quantum mechanics and the multiple step technique, the transmissivity through a triangular air gap surrounded by an homogeneous dielectric medium. The new formula is then compared with the formula used in literature. Starting from the qualitative and quantitative differences between these formulas, we propose optical experiments to test our theoretical results.

  1. Modification in band gap of zirconium complexes

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mayank, E-mail: mayank30134@gmail.com; Singh, J.; Chouhan, S. [Department of Physics, ISLE, IPS Academy, Indore (M.P.) (India); Mishra, A. [School of Physics, Devi Ahilya Vishwavidyalaya, Indore (M.P.) (India); Shrivastava, B. D. [Govt. P. G. College, Biora (M.P.) (India)

    2016-05-06

    The optical properties of zirconium complexes with amino acid based Schiff bases are reported here. The zirconium complexes show interesting stereo chemical features, which are applicable in organometallic and organic synthesis as well as in catalysis. The band gaps of both Schiff bases and zirconium complexes were obtained by UV-Visible spectroscopy. It was found that the band gap of zirconium complexes has been modified after adding zirconium compound to the Schiff bases.

  2. Synthetic analyses of the LAVA experimental results on in-vessel corium retention through gap cooling

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Kyoung Ho; Cho, Young Ro; Koo, Kil Mo; Park, Rae Joon; Kim, Jong Hwan; Kim, Jong Tae; Ha, Kwang Sun; Kim, Sang Baik; Kim, Hee Dong

    2001-03-01

    LAVA(Lower-plenum Arrested Vessel Attack) has been performed to gather proof of gap formation between the debris and lower head vessel and to evaluate the effect of the gap formation on in-vessel cooling. Through the total of 12 tests, the analyses on the melt relocation process, gap formation and the thermal and mechanical behaviors of the vessel were performed. The thermal behaviors of the lower head vessel were affected by the formation of the fragmented particles and melt pool during the melt relocation process depending on mass and composition of melt and subcooling and depth of water. During the melt relocation process 10.0 to 20.0 % of the melt mass was fragmented and also 15.5 to 47.5 % of the thermal energy of the melt was transferred to water. The experimental results address the non-adherence of the debris to the lower head vessel and the consequent gap formation between the debris and the lower head vessel in case there was an internal pressure load across the vessel abreast with the thermal load induced by the thermite melt. The thermal behaviors of the lower head vessel during the cooldown period were mainly affected by the heat removal characteristics through this gap, which were determined by the possibilities of the water ingression into the gap depending on the melt composition of the corium simulant. The enhanced cooling capacity through the gap was distinguished in the Al{sub 2}O{sub 3} melt tests. It could be inferred from the analyses on the heat removal capacity through the gap that the lower head vessel could effectively cooldown via heat removal in the gap governed by counter current flow limits(CCFL) even if 2mm thick gap should form in the 30 kg Al{sub 2}O{sub 3} melt tests, which was also confirmed through the variations of the conduction heat flux in the vessel and rapid cool down of the vessel outer surface in the Al{sub 2}O{sub 3} melt tests. In the case of large melt mass of 70 kg Al{sub 2}O{sub 3} melt, however, the infinite

  3. Narrow Band Gap Lead Sulfide Hole Transport Layers for Quantum Dot Photovoltaics.

    Science.gov (United States)

    Zhang, Nanlin; Neo, Darren C J; Tazawa, Yujiro; Li, Xiuting; Assender, Hazel E; Compton, Richard G; Watt, Andrew A R

    2016-08-24

    The band structure of colloidal quantum dot (CQD) bilayer heterojunction solar cells is optimized using a combination of ligand modification and QD band gap control. Solar cells with power conversion efficiencies of up to 9.33 ± 0.50% are demonstrated by aligning the absorber and hole transport layers (HTL). Key to achieving high efficiencies is optimizing the relative position of both the valence band and Fermi energy at the CQD bilayer interface. By comparing different band gap CQDs with different ligands, we find that a smaller band gap CQD HTL in combination with a more p-type-inducing CQD ligand is found to enhance hole extraction and hence device performance. We postulate that the efficiency improvements observed are largely due to the synergistic effects of narrower band gap QDs, causing an upshift of valence band position due to 1,2-ethanedithiol (EDT) ligands and a lowering of the Fermi level due to oxidation.

  4. Photonic band gap of a graphene-embedded quarter-wave stack

    CERN Document Server

    Fan, Yuancheng; Li, Hongqiang; Chen, Hong; Soukoulis, Costas M

    2013-01-01

    Here, we present a mechanism for tailoring the photonic band structure of a quarter-wave stack without changing its physical periods by embedding conductive sheets. Graphene is utilized and studied as a realistic, two-dimensional conductive sheet. In a graphene-embedded quarter-wave stack, the synergic actions of Bragg scattering and graphene conductance contributions open photonic gaps at the center of the reduced Brillouin zone, that nonexistent in conventional quarter-wave stacks. Such photonic gaps show giant, loss-independent density of optical states at the fixed lower-gap-edges, of even-multiple characteristic frequency of the quarter-wave stack. The novel conductive sheets induced photonic gaps provide a new platform for the enhancement of light-matter interactions.

  5. The Microvascular Gap Junction Channel: A Route to Deliver MicroRNAs for Neurological Disease Treatment.

    Science.gov (United States)

    Thuringer, Dominique; Solary, Eric; Garrido, Carmen

    2017-01-01

    Brain microvascular endothelial cells (BMECs) separate the peripheral blood from the brain. These cells, which are surrounded by basal lamina, pericytes and glial cells, are highly interconnected through tight and gap junctions. Their permeability properties restrict the transfer of potentially useful therapeutic agents. In such a hermetic system, the gap junctional exchange of small molecules between cerebral endothelial and non-endothelial cells is crucial for maintaining tissue homeostasis. MicroRNA were shown to cross gap junction channels, thereby modulating gene expression and function of the recipient cell. It was also shown that, when altered, BMEC could be regenerated by endothelial cells derived from pluripotent stem cells. Here, we discuss the transfer of microRNA through gap junctions between BMEC, the regeneration of BMEC from induced pluripotent stem cells that could be engineered to express specific microRNA, and how such an innovative approach could benefit to the treatment of glioblastoma and other neurological diseases.

  6. The Microvascular Gap Junction Channel: A Route to Deliver MicroRNAs for Neurological Disease Treatment

    Directory of Open Access Journals (Sweden)

    Dominique Thuringer

    2017-08-01

    Full Text Available Brain microvascular endothelial cells (BMECs separate the peripheral blood from the brain. These cells, which are surrounded by basal lamina, pericytes and glial cells, are highly interconnected through tight and gap junctions. Their permeability properties restrict the transfer of potentially useful therapeutic agents. In such a hermetic system, the gap junctional exchange of small molecules between cerebral endothelial and non-endothelial cells is crucial for maintaining tissue homeostasis. MicroRNA were shown to cross gap junction channels, thereby modulating gene expression and function of the recipient cell. It was also shown that, when altered, BMEC could be regenerated by endothelial cells derived from pluripotent stem cells. Here, we discuss the transfer of microRNA through gap junctions between BMEC, the regeneration of BMEC from induced pluripotent stem cells that could be engineered to express specific microRNA, and how such an innovative approach could benefit to the treatment of glioblastoma and other neurological diseases.

  7. Band gap narrowing models tested on low recombination phosphorus laser doped silicon

    Science.gov (United States)

    Dahlinger, Morris; Carstens, Kai

    2016-10-01

    This manuscript discusses bandgap narrowing models for highly phosphorus doped silicon. We simulate the recombination current pre-factor J0,phos in PC1Dmod 6.2 of measured doping profiles and apply the theoretical band gap narrowing model of Schenk [J. Appl. Phys. 84, 3684 (1998)] and an empirical band gap narrowing model of Yan and Cuevas [J. Appl. Phys. 114, 044508 (2013)]. The recombination current pre-factor of unpassivated and passivated samples measured by the photo conductance measurement and simulated J0,phos agrees well, when the band gap narrowing model of Yan and Cuevas is applied. With the band gap narrowing model of Schenk, the simulation cannot reproduce the measured J0,phos. Furthermore, the recombination current pre-factor of our phosphorus laser doped silicon samples are comparable with furnace diffused samples. There is no indication of recombination active defects, thus no laser induced defects in the diffused volume.

  8. Undecidability of the Spectral Gap (full version)

    CERN Document Server

    Cubitt, Toby; Wolf, Michael M

    2015-01-01

    We show that the spectral gap problem is undecidable. Specifically, we construct families of translationally-invariant, nearest-neighbour Hamiltonians on a 2D square lattice of $d$-level quantum systems ($d$ constant), for which determining whether the system is gapped or gapless is an undecidable problem. This is true even with the promise that each Hamiltonian is either gapped or gapless in the strongest sense: it is promised to either have continuous spectrum above the ground state in the thermodynamic limit, or its spectral gap is lower-bounded by a constant in the thermodynamic limit. Moreover, this constant can be taken equal to the local interaction strength of the Hamiltonian. This implies that it is logically impossible to say in general whether a quantum many-body system is gapped or gapless. Our results imply that there exist specific Hamiltonians for which the presence or absence of a spectral gap is independent of all consistent axiomatisations of mathematics. These results have a number of impor...

  9. Plasmon transmission through excitonic subwavelength gaps

    CERN Document Server

    Sukharev, Maxim

    2016-01-01

    We study the transfer of electromagnetic energy across a subwavelength gap separating two co-axial metal nanorodes. The absence of spacer in the gap separating the rods the system exhibits the strong coupling between longitudinal plasmons in the two rods. The nature and magnitude of this coupling is studied by varying various geometrical parameters. When the length of one rod is varied this mode spectrum exhibits the familiar anti-crossing behavior that depends on the coupling strength determined by the gap width. As a function of frequency the transmission is dominated by a splitted longitudinal plasmon peak. The two hybrid modes are the dipole-like "bonding" mode characterized by a peak intensity in the gap, and a quadrupole-like "antibonding" mode whose amplitude vanishes at the gap center. When off-resonant $2-$level emitters are placed in the gap, almost no effect on the frequency dependent transmission is observed. In contrast, when the molecular system is resonant with the plasmonic lineshape, the tran...

  10. Plasmon resonances in atomic-scale gaps

    CERN Document Server

    Kern, Johannes; Tarakina, Nadezda V; Häckel, Tim; Emmerling, Monika; Kamp, Martin; Huang, Jer-Shing; Biagioni, Paolo; Prangsma, Jord C; Hecht, Bert

    2011-01-01

    Gap modes in resonant plasmonic nanostructures exhibit optical fields whose spatial confinement and near-field enhancement strongly increases for smaller gaps[1]. In the context of augmented light-matter interaction, gap modes are of high interest for various applications such as single-emitter spectroscopy[2-4], quantum optics[5,6], extreme nonlinear optics[7,8], efficient optical switching[9], optical trapping10, and molecular opto-electronics[11]. By means of reproducible self-assembly we have obtained side-by-side aligned gold nanorod dimers with robust gaps reaching well below 0.5 nm. For such atomic-scale gaps extreme splitting of the symmetric and anti-symmetric dimer eigenmodes of more than 800 meV is observed in white-light scattering experiments. Besides providing evidence for atomic-scale gap modes at visible wavelengths with correspondingly small mode volumes and strong field enhancement, our experimental results can serve as a benchmark for electromagnetic modeling beyond local Maxwell theory[12,...

  11. Flows of gas through a protoplanetary gap

    Science.gov (United States)

    Casassus, Simon; van der Plas, Gerrit; M, Sebastian Perez; Dent, William R. F.; Fomalont, Ed; Hagelberg, Janis; Hales, Antonio; Jordán, Andrés; Mawet, Dimitri; Ménard, Francois; Wootten, Al; Wilner, David; Hughes, A. Meredith; Schreiber, Matthias R.; Girard, Julien H.; Ercolano, Barbara; Canovas, Hector; Román, Pablo E.; Salinas, Vachail

    2013-01-01

    The formation of gaseous giant planets is thought to occur in the first few million years after stellar birth. Models predict that the process produces a deep gap in the dust component (shallower in the gas). Infrared observations of the disk around the young star HD 142527 (at a distance of about 140 parsecs from Earth) found an inner disk about 10 astronomical units (AU) in radius (1 AU is the Earth-Sun distance), surrounded by a particularly large gap and a disrupted outer disk beyond 140 AU. This disruption is indicative of a perturbing planetary-mass body at about 90 AU. Radio observations indicate that the bulk mass is molecular and lies in the outer disk, whose continuum emission has a horseshoe morphology. The high stellar accretion rate would deplete the inner disk in less than one year, and to sustain the observed accretion matter must therefore flow from the outer disk and cross the gap. In dynamical models, the putative protoplanets channel outer-disk material into gap-crossing bridges that feed stellar accretion through the inner disk. Here we report observations of diffuse CO gas inside the gap, with denser HCO+ gas along gap-crossing filaments. The estimated flow rate of the gas is in the range of 7 × 10-9 to 2 × 10-7 solar masses per year, which is sufficient to maintain accretion onto the star at the present rate.

  12. Numerical simulation of supersonic gap flow.

    Science.gov (United States)

    Jing, Xu; Haiming, Huang; Guo, Huang; Song, Mo

    2015-01-01

    Various gaps in the surface of the supersonic aircraft have a significant effect on airflows. In order to predict the effects of attack angle, Mach number and width-to-depth ratio of gap on the local aerodynamic heating environment of supersonic flow, two-dimensional compressible Navier-Stokes equations are solved by the finite volume method, where convective flux of space term adopts the Roe format, and discretization of time term is achieved by 5-step Runge-Kutta algorithm. The numerical results reveal that the heat flux ratio is U-shaped distribution on the gap wall and maximum at the windward corner of the gap. The heat flux ratio decreases as the gap depth and Mach number increase, however, it increases as the attack angle increases. In addition, it is important to find that chamfer in the windward corner can effectively reduce gap effect coefficient. The study will be helpful for the design of the thermal protection system in reentry vehicles.

  13. Numerical simulation of supersonic gap flow.

    Directory of Open Access Journals (Sweden)

    Xu Jing

    Full Text Available Various gaps in the surface of the supersonic aircraft have a significant effect on airflows. In order to predict the effects of attack angle, Mach number and width-to-depth ratio of gap on the local aerodynamic heating environment of supersonic flow, two-dimensional compressible Navier-Stokes equations are solved by the finite volume method, where convective flux of space term adopts the Roe format, and discretization of time term is achieved by 5-step Runge-Kutta algorithm. The numerical results reveal that the heat flux ratio is U-shaped distribution on the gap wall and maximum at the windward corner of the gap. The heat flux ratio decreases as the gap depth and Mach number increase, however, it increases as the attack angle increases. In addition, it is important to find that chamfer in the windward corner can effectively reduce gap effect coefficient. The study will be helpful for the design of the thermal protection system in reentry vehicles.

  14. Water limits to closing yield gaps

    Science.gov (United States)

    Davis, Kyle Frankel; Rulli, Maria Cristina; Garrassino, Francesco; Chiarelli, Davide; Seveso, Antonio; D'Odorico, Paolo

    2017-01-01

    Agricultural intensification is often seen as a suitable approach to meet the growing demand for agricultural products and improve food security. It typically entails the use of fertilizers, new cultivars, irrigation, and other modern technology. In regions of the world affected by seasonal or chronic water scarcity, yield gap closure is strongly dependent on irrigation (blue water). Global yield gap assessments have often ignored whether the water required to close the yield gap is locally available. Here we perform a gridded global analysis (10 km resolution) of the blue water consumption that is needed annually to close the yield gap worldwide and evaluate the associated pressure on renewable freshwater resources. We find that, to close the yield gap, human appropriation of freshwater resources for irrigation would have to increase at least by 146%. Most study countries would experience at least a doubling in blue water requirement, with 71% of the additional blue water being required by only four crops - maize, rice, soybeans, and wheat. Further, in some countries (e.g., Algeria, Morocco, Syria, Tunisia, and Yemen) the total volume of blue water required for yield gap closure would exceed sustainable levels of freshwater consumption (i.e., 40% of total renewable surface and groundwater resources).

  15. U.S. Geological Survey Gap Analysis Program

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Gap Analysis Program (GAP) is an element of the U.S. Geological Survey (USGS). GAP helps to implement the Department of Interior?s goals of inventory,...

  16. Increasing gap junctional coupling: a tool for dissecting the role of gap junctions.

    Science.gov (United States)

    Axelsen, Lene Nygaard; Haugan, Ketil; Stahlhut, Martin; Kjølbye, Anne-Louise; Hennan, James K; Holstein-Rathlou, Niels-Henrik; Petersen, Jørgen Søberg; Nielsen, Morten Schak

    2007-03-01

    Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes. In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs and by interfering with the gating of gap junctional channels.

  17. Ocean Mixed Layer Response to Gap Wind Scenarios

    Science.gov (United States)

    2006-12-01

    LAYER ........5 B. GAP WINDS AND GAP FLOW .............................7 III MODELS AND DATA SOURCES ................................13 A. COUPLED...atmospheric and the oceanic boundary layer during gap flow conditions were made by a research aircraft with dropsonde and AXBTs. This dataset gave us the...Polar Regions (http://oceanworld.tamu.edu/resources/ocng textbook , last visited 26 October 2006). B. GAP WINDS AND GAP FLOW Gap winds are low

  18. Resistance to change and vulnerability to stress: Autistic-like features of GAP43 deficient mice

    Science.gov (United States)

    Zaccaria, Kimberly J; Lagace, Diane C; Eisch, Amelia J; McCasland, James S

    2010-01-01

    There is an urgent need for animal models of autism spectrum disorder (ASD) to understand the underlying pathology and facilitate development and testing of new treatments. The synaptic growth-associated protein-43 (GAP43) has recently been identified as an autism candidate gene of interest. Our previous studies show many brain abnormalities in mice lacking one allele for GAP43 (GAP43 (+/−)) that are consistent with the disordered connectivity theory of ASD. Thus, we hypothesized that GAP43 (+/−) mice would demonstrate at least some autistic-like behaviors. We found that GAP43 (+/−) mice, relative to wild-type (+/+) littermates, displayed resistance to change, consistent with one of the diagnostic critera for ASD. GAP43 (+/−) mice also displayed stress-induced behavioral withdrawal and anxiety, as seen in many autistic individuals. In addition, both GAP43 (+/−) mice and (+/+) littermates demonstrated low social approach and lack of preference for social novelty, consistent with another diagnostic criterion for ASD. This low sociability is likely due to the mixed C57BL/6J 129S3/SvImJ background. We conclude that GAP43 deficiency leads to the development of a subset of autistic-like behaviors. Since these behaviors occur in a mouse that displays disordered connectivity, we propose that future anatomical and functional studies in this mouse may help uncover underlying mechanisms for these specific behaviors. Strain-specific low sociability may be advantageous in these studies, creating a more autistic-like environment for study of the GAP43-mediated deficits of resistance to change and vulnerability to stress. PMID:20707874

  19. Resistance to change and vulnerability to stress: autistic-like features of GAP43-deficient mice.

    Science.gov (United States)

    Zaccaria, K J; Lagace, D C; Eisch, A J; McCasland, J S

    2010-11-01

    There is an urgent need for animal models of autism spectrum disorder (ASD) to understand the underlying pathology and facilitate development and testing of new treatments. The synaptic growth-associated protein-43 (GAP43) has recently been identified as an autism candidate gene of interest. Our previous studies show many brain abnormalities in mice lacking one allele for GAP43 [GAP43 (+/-)] that are consistent with the disordered connectivity theory of ASD. Thus, we hypothesized that GAP43 (+/-) mice would show at least some autistic-like behaviors. We found that GAP43 (+/-) mice, relative to wild-type (+/+) littermates, displayed resistance to change, consistent with one of the diagnostic criteria for ASD. GAP43 (+/-) mice also displayed stress-induced behavioral withdrawal and anxiety, as seen in many autistic individuals. In addition, both GAP43 (+/-) mice and (+/+) littermates showed low social approach and lack of preference for social novelty, consistent with another diagnostic criterion for ASD. This low sociability is likely because of the mixed C57BL/6J 129S3/SvImJ background. We conclude that GAP43 deficiency leads to the development of a subset of autistic-like behaviors. As these behaviors occur in a mouse that displays disordered connectivity, we propose that future anatomical and functional studies in this mouse may help uncover underlying mechanisms for these specific behaviors. Strain-specific low sociability may be advantageous in these studies, creating a more autistic-like environment for study of the GAP43-mediated deficits of resistance to change and vulnerability to stress. © 2010 The Authors. Genes, Brain and Behavior © 2010 Blackwell Publishing Ltd and International Behavioural and Neural Genetics Society.

  20. Horizontal roof gap of backfill hydraulic support

    Institute of Scientific and Technical Information of China (English)

    张强; 张吉雄; 邰阳; 方坤; 殷伟

    2015-01-01

    For the backfill hydraulic support as the key equipment for achieving integration of backfilling and coal mining simultaneously in the practical process, its characteristics will directly influence the backfill body’s compression ratio. Horizontal roof gap, as a key parameter of backfilling characteristics, may impact the backfilling effect from the aspects of control of roof subsidence in advance, support stress, backfilling process and the support design. Firstly, the reason why horizontal roof gap exists was analyzed and its definition, causes and connotation were introduced, then adopting the Pro/E 3D simulation software, three typical 3D entity models of backfill hydraulic supports were built, based on the influence of horizontal roof gap on backfilling effect, and influence rules of four factors, i.e. support height, suspension height, suspension angle and tamping angle, were emphatically analyzed on horizontal roof gap. The results indicate that, the four factors all have significant impacts on horizontal roof gap, but show differences in influence trend and degree, showing negative linear correlation, positive linear correlation, positive semi-parabolic correlation and negative semi-parabolic correlation, respectively. Four legs type is the most adaptive to the four factors, while six legs (II) type has the poorest adaptability, and the horizontal roof gap is small under large support height, small suspension height, small suspension angle and large tamping angle situation. By means of optimizing structure components and their positional relation and suspension height of backfill scrape conveyor in the process of support design and through controlling working face deployment, roof subsidence in advance, mining height and backfilling during engineering application, the horizontal roof gap is optimized. The research results can be served as theoretical basis for support design and guidance for backfill support to have better performance in backfilling.

  1. Specific analogues uncouple transport, signalling, oligo-ubiquitination and endocytosis in the yeast Gap1 amino acid transceptor.

    Science.gov (United States)

    Van Zeebroeck, Griet; Rubio-Texeira, Marta; Schothorst, Joep; Thevelein, Johan M

    2014-07-01

    The Saccharomyces cerevisiae amino acid transceptor Gap1 functions as receptor for signalling to the PKA pathway and concomitantly undergoes substrate-induced oligo-ubiquitination and endocytosis. We have identified specific amino acids and analogues that uncouple to certain extent signalling, transport, oligo-ubiquitination and endocytosis. L-lysine, L-histidine and L-tryptophan are transported by Gap1 but do not trigger signalling. Unlike L-histidine, L-lysine triggers Gap1 oligo-ubiquitination without substantial induction of endocytosis. Two transported, non-metabolizable signalling agonists, β-alanine and D-histidine, are strong and weak inducers of Gap1 endocytosis, respectively, but both causing Gap1 oligo-ubiquitination. The non-signalling agonist, non-transported competitive inhibitor of Gap1 transport, L-Asp-γ-L-Phe, induces oligo-ubiquitination but no discernible endocytosis. The Km of L-citrulline transport is much lower than the threshold concentration for signalling and endocytosis. These results show that molecules can be transported without triggering signalling or substantial endocytosis, and that oligo-ubiquitination and endocytosis do not require signalling nor metabolism. Oligo-ubiquitination is required, but apparently not sufficient to trigger endocytosis. In addition, we demonstrate intracellular cross-induction of endocytosis of transport-defective Gap1(Y395C) by ubiquitination- and endocytosis-deficient Gap1(K9R,K16R). Our results support the concept that different substrates bind to partially overlapping binding sites in the same general substrate-binding pocket of Gap1, triggering divergent conformations, resulting in different conformation-induced downstream processes.

  2. Tire Crumb Research Study Literature Review / Gap ...

    Science.gov (United States)

    In order to more fully understand data gaps in human exposure and toxicity to tire crumb materials, ATSDR, CPSC and EPA undertook a collaborative effort in the form of a scientific literature review and subsequent gaps analysis. The first objective of the Literature Review and Gap Analysis (LRGA) collaboration was to identify the existing body of literature related specifically to human exposure to tire crumb materials through the use of synthetic turf athletic fields and playgrounds. The second objective was to characterize and summarize the relevant data from the scientific literature. The final objective was to review the summary information and identify data gaps to build on the current understanding of the state-of-the-science and inform the development of specific research efforts that would be most impactful in the near-term. Because of the need for additional information, the U.S. Environmental Protection Agency (EPA), the Centers for Disease Control and Prevention/Agency for Toxic Substances and Disease Registry (ATSDR), and the U.S. Consumer Product Safety Commission (CPSC) launched a multi-agency action plan to study key environmental human health questions. The Federal Research Action Plan includes numerous activities, including research studies (U.S. EPA, 2016). A key objective of the Action Plan is to identify key knowledge gaps.

  3. Comparative study of INPIStron and spark gap

    Science.gov (United States)

    Han, Kwang S.; Lee, Ja H.

    1993-01-01

    An inverse pinch plasma switch, INPIStron, was studied in comparison to a conventional spark gap. The INPIStron is under development for high power switching applications. The INPIStron has an inverse pinch dynamics, opposed to Z-pinch dynamics in the spark gap. The electrical, plasma dynamics and radiative properties of the closing plasmas have been studied. Recently the high-voltage pulse transfer capabilities or both the INPIStron and the spark gap were also compared. The INPIStron with a low impedance Z = 9 ohms transfers 87 percent of an input pulse with a halfwidth of 2 mu s. For the same input pulse the spark gap of Z = 100 ohms transfers 68 percent. Fast framing and streak photography, taken with an TRW image converter camera, was used to observe the discharge uniformity and closing plasma speed in both switches. In order to assess the effects of closing plasmas on erosion of electrode material, emission spectra of two switches were studied with a spectrometer-optical multi channel analyzer (OMA) system. The typical emission spectra of the closing plasmas in the INPIStron and the spark gap showed that there were comparatively weak carbon line emission in 658.7 nm and copper (electrode material) line emissions in the INPIStron, indicating low erosion of materials in the INPIStron.

  4. Gap junctions: structure and function (Review).

    Science.gov (United States)

    Evans, W Howard; Martin, Patricia E M

    2002-01-01

    Gap junctions are plasma membrane spatial microdomains constructed of assemblies of channel proteins called connexins in vertebrates and innexins in invertebrates. The channels provide direct intercellular communication pathways allowing rapid exchange of ions and metabolites up to approximately 1 kD in size. Approximately 20 connexins are identified in the human or mouse genome, and orthologues are increasingly characterized in other vertebrates. Most cell types express multiple connexin isoforms, making likely the construction of a spectrum of heteromeric hemichannels and heterotypic gap junctions that could provide a structural basis for the charge and size selectivity of these intercellular channels. The precise nature of the potential signalling information traversing junctions in physiologically defined situations remains elusive, but extensive progress has been made in elucidating how connexins are assembled into gap junctions. Also, participation of gap junction hemichannels in the propagation of calcium waves via an extracellular purinergic pathway is emerging. Connexin mutations have been identified in a number of genetically inherited channel communication-opathies. These are detected in connexin 32 in Charcot Marie Tooth-X linked disease, in connexins 26 and 30 in deafness and skin diseases, and in connexins 46 and 50 in hereditary cataracts. Biochemical approaches indicate that many of the mutated connexins are mistargeted to gap junctions and/or fail to oligomerize correctly into hemichannels. Genetic ablation approaches are helping to map out a connexin code and point to specific connexins being required for cell growth and differentiation as well as underwriting basic intercellular communication.

  5. GAP-43 in synaptic plasticity: molecular perspectives

    Directory of Open Access Journals (Sweden)

    Holahan MR

    2015-06-01

    Full Text Available Matthew R HolahanDepartment of Neuroscience, Carleton University, Ottawa, ON, CanadaAbstract: The growth-associated protein, GAP-43 (also known as F1, neuromodulin, B-50, participates in the developmental regulation of axonal growth and neural network formation via protein kinase C-mediated regulation of cytoskeletal elements. Transgenic overexpression of GAP-43 can result in the formation of new synapses, neurite outgrowth, and synaptogenesis after injury. In a number of adult mammalian species, GAP-43 has been implicated in the regulation of synaptic transmission and plasticity, such as long-term potentiation, drug sensitization, and changes in memory processes. This review examines the molecular and biochemical attributes of GAP-43, its distribution in the central nervous system, subcellular localization, role in neurite outgrowth and development, and functions related to plasticity, such as those occurring during long-term potentiation, memory formation, and drug sensitization.Keywords: GAP-43, protein kinase C, axons, development, regeneration, long-term potentiation, memory

  6. Two Modes of Partially Screened Gap

    CERN Document Server

    Szary, Andrzej; Gil, Janusz

    2014-01-01

    The analysis of X-ray observations suggest an ultrastrong ($B\\gtrsim 10^{14} \\,{\\rm G}$) surface magnetic field at the polar cap of pulsars (Szary, 2013). On the other hand, the temperature of the polar caps is about a few millions Kelvin. Based on these two facts we use the Partially Screened Gap (PSG) model to describe the Inner Acceleration Region (IAR). The PSG model assumes that the temperature of the actual polar cap is equal to the so-called critical value, i.e. the temperature at which the outflow of thermal ions from the surface screens the gap completely. We have found that, depending on the conditions above the polar cap, the generation of high energetic photons in IAR can be caused either by Curvature Radiation (CR) or by Inverse Compton Scattering (ICS). Completely different properties of both processes result in two different scenarios of breaking the acceleration gap: the so-called PSG-off mode for the gap dominated by CR and the PSG-on mode for the gap dominated by ICS. The existence of two di...

  7. Nonspecific effects of gap paradigm on swallowing.

    Science.gov (United States)

    Yoneda, Masaki; Saitoh, Kazuya

    2017-02-01

    Analogous to the gap paradigm in experiments for saccadic eye movements with very short reaction times, we hypothesized that the initiation of oropharyngeal swallowing movements guided by visual cues are encouraged under experimental conditions using a similar gap paradigm. A red visual cue indicating to hold a bolus in the mouth and a blue one indicating to swallow the bolus were sequentially provided on a computer display to 11 healthy participants. The gap period between these cues varied from 0 to 800ms. Swallowing kinetics and kinematics were recorded using surface electromyography and a laser displacement sensor, respectively. In comparison with the no-gap paradigm, the delay from the onset of muscle activities to initiation of movement significantly decreased with a 100- (pparadigm of 100-200ms. Wrist flexion was boosted in a similar manner. Thus, the gap effect may be a generalized warning effect. Our findings might provide insights into the contribution of the basal ganglia to volitional swallowing. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. The gap-startle paradigm for tinnitus screening in animal models: limitations and optimization.

    Science.gov (United States)

    Lobarinas, Edward; Hayes, Sarah H; Allman, Brian L

    2013-01-01

    In 2006, Turner and colleagues (Behav. Neurosci., 120:188-195) introduced the gap-startle paradigm as a high-throughput method for tinnitus screening in rats. Under this paradigm, gap detection ability was assessed by determining the level of inhibition of the acoustic startle reflex produced by a short silent gap inserted in an otherwise continuous background sound prior to a loud startling stimulus. Animals with tinnitus were expected to show impaired gap detection ability (i.e., lack of inhibition of the acoustic startle reflex) if the background sound containing the gap was qualitatively similar to the tinnitus pitch. Thus, for the gap-startle paradigm to be a valid tool to screen for tinnitus, a robust startle response from which to inhibit must be present. Because recent studies have demonstrated that the acoustic startle reflex could be dramatically reduced following noise exposure, we endeavored to 1) modify the gap-startle paradigm to be more resilient in the presence of hearing loss, and 2) evaluate whether a reduction in startle reactivity could confound the interpretation of gap prepulse inhibition and lead to errors in screening for tinnitus. In the first experiment, the traditional broadband noise (BBN) startle stimulus was replaced by a bandpass noise in which the sound energy was concentrated in the lower frequencies (5-10 kHz) in order to maintain audibility of the startle stimulus after unilateral high-frequency noise exposure (16 kHz). However, rats still showed a 57% reduction in startle amplitude to the bandpass noise post-noise exposure. A follow-up experiment on a separate group of rats with transiently-induced conductive hearing loss revealed that startle reactivity was better preserved when the BBN startle stimulus was replaced by a rapid airpuff to the back of the rat's neck. Furthermore, it was found that transient unilateral conductive hearing loss, which was not likely to induce tinnitus, caused an impairment in gap prepulse

  9. Anomalous composition dependence of the band gap pressure coefficients in In-containing nitride semiconductors

    DEFF Research Database (Denmark)

    Gorczyca, I.; Kamińska, A.; Staszczak, G.;

    2010-01-01

    The pressure-induced changes in the electronic band structures of In-containing nitride alloys, InxGa1-xN and InxAl1-xN are examined experimentally as well as by ab initio calculations. It is found that the band gap pressure coefficients, dEg/dp, exhibit very large bowing with x, and calculations...

  10. Canopy gap edge determination and the importance of gap edges for plant diversity

    Directory of Open Access Journals (Sweden)

    D. Salvador-Van Eysenrode

    2002-01-01

    Full Text Available Canopy gaps, i.e. openings in the forest cover caused by the fall of structural elements, are considered to be important for the maintenance of diversity and for the forest cycle. A gap can be considered as a young forest patch in the forest matrix, composed of interior surrounded by an edge, both enclosed by a perimeter. Much of the attention has been focused on the gap interior. However, at gap edges the spectrum of regeneration opportunities for plants may be larger than in the interior. Although definitions of gap are still discussed, any definition can describe it in an acceptable way, if justified, but defining edges is complicated and appropriate descriptors should be used. A method to determine gap interior and edge, using light as a descriptor, is presented with an example of gaps from a beech forest (Fagus sylvatica in Belgium. Also, the relevance and implications of gap edges for plant diversity and calculation of forest turnover is discussed.

  11. Closing the Gap: An Overview. The Achievement Gap: An Overview. Info Brief. Number 44

    Science.gov (United States)

    Poliakoff, Anne Rogers

    2006-01-01

    Persistent gaps between the academic achievements of different groups of children are thoroughly documented by the U.S. National Assessment of Educational Progress and other statistical analyses of state assessments, grades, course selection, and dropout rates. Despite improvements in some years, the gap endures as a consistent and disturbing…

  12. Widening the Gap: Pre-University Gap Years and the "Economy of Experience"

    Science.gov (United States)

    Heath, Sue

    2007-01-01

    Embarking upon a pre-university gap year is an increasingly popular option among British students. Drawing on Brown et al.'s work on positional conflict theory and the increased importance of the "economy of experience", this paper seeks to explore this growing popularity and argues that the gap year's enhanced profile raises important…

  13. Close the Gap : a study on the regulation of Connexin43 gap junctional communication

    NARCIS (Netherlands)

    Zeijl, Leonie van

    2009-01-01

    Gap junctions are groups of transmembrane channels that connect the cytoplasms of adjacent cells to mediate the diffusion of small molecules, such as ions, metabolites, second messengers and small peptides. The building blocks of gap junctions are connexin proteins. The most ubiquitous and best stu

  14. Focusing on the Participation and Engagement Gap: A Case Study on Closing the Achievement Gap

    Science.gov (United States)

    Fisher, Douglas; Frey, Nancy; Lapp, Diane

    2011-01-01

    In this case study, we focus on 2 variables often neglected in conversations about closing the achievement gap. Most recommendations for closing the achievement gap center on extending learning time, including afterschool programs, extended year programs, and supplemental instruction. Our school focused on attendance and student engagement in our…

  15. Widening the Gap: Pre-University Gap Years and the "Economy of Experience"

    Science.gov (United States)

    Heath, Sue

    2007-01-01

    Embarking upon a pre-university gap year is an increasingly popular option among British students. Drawing on Brown et al.'s work on positional conflict theory and the increased importance of the "economy of experience", this paper seeks to explore this growing popularity and argues that the gap year's enhanced profile raises important…

  16. Mean field magnetization of gapped anisotropic multiplet

    Science.gov (United States)

    Paixão, L. S.; Reis, M. S.

    2014-06-01

    Some materials have a large gap between the ground and first excited states. At temperatures smaller than the gap value, the thermodynamic properties of such materials are mainly ruled by the ground state. It is also common to find materials with magnetocrystalline anisotropy, which arises due to interatomic interactions. The present paper uses a classical approach to deal large angular momenta in such materials. Based on analytical expressions for the thermodynamics of paramagnetic gapped anisotropic multiplets, we use mean field theory to study the influence of the anisotropy upon the properties of interacting systems. We also use Landau theory to determine the influence of the anisotropy in first and second order phase transitions. It is found that the anisotropy increases the critical temperature, and enlarges the hysteresis of first order transitions. We present analytical expressions for the quantities analyzed.

  17. Gap junction diseases of the skin.

    Science.gov (United States)

    van Steensel, M A M

    2004-11-15

    Gap junctions are intercellular channels that allow the passage of water, ions, and small molecules. They are involved in quick, short-range messaging between cells and are found in skin, nervous tissue, heart, and muscle. An increasing number of hereditary skin disorders appear to be caused by mutations in one of the genes coding for the constituent proteins of gap junctions, known as connexins. In this review, the currently known connexin disorders that feature skin abnormalities are described: keratitis-ichthyosis deafness syndrome, erythrokeratoderma variabilis, Vohwinkel's syndrome, and a novel disorder called hypotrichosis-deafness syndrome. What is known about the pathogenesis of these disorders is discussed and related to gap junction physiology. (c) 2004 Wiley-Liss, Inc.

  18. Sizable band gap in organometallic topological insulator

    Science.gov (United States)

    Derakhshan, V.; Ketabi, S. A.

    2017-01-01

    Based on first principle calculation when Ceperley-Alder and Perdew-Burke-Ernzerh type exchange-correlation energy functional were adopted to LSDA and GGA calculation, electronic properties of organometallic honeycomb lattice as a two-dimensional topological insulator was calculated. In the presence of spin-orbit interaction bulk band gap of organometallic lattice with heavy metals such as Au, Hg, Pt and Tl atoms were investigated. Our results show that the organometallic topological insulator which is made of Mercury atom shows the wide bulk band gap of about ∼120 meV. Moreover, by fitting the conduction and valence bands to the band-structure which are produced by Density Functional Theory, spin-orbit interaction parameters were extracted. Based on calculated parameters, gapless edge states within bulk insulating gap are indeed found for finite width strip of two-dimensional organometallic topological insulators.

  19. Closing the technological gap in Latin America

    Energy Technology Data Exchange (ETDEWEB)

    Street, J.H.; James, D.D.

    1978-06-01

    The 19 oil-importing countries of Latin America were severely affected by the 1973 oil embargo and price increases, which revealed a widening technological gap that has made stability and economic growth difficult for these countries. Unstable price levels and massive inflation have produced unprecedented balance-of-payments deficits. The area's technological gap leaves it unprepared to produce adequate food supplies or to make major resource substitutions. Internal weaknesses are evident in the educational and research biases of South America that have limited the progress of universities and research institutes. New policies are needed to promote viable science and technology by setting priorities and expanding indigenous research programs. Several case studies of indigenous innovation and adaptation are noted to illustrate the potential for closing the technological gap in a peaceful, constructive way. 44 references.

  20. Review and bibliometric analysis of published literature citing data produced by the Gap Analysis Program (GAP)

    Science.gov (United States)

    Ratz, Joan M.; Conk, Shannon J.

    2014-01-01

    The Gap Analysis Program (GAP) of the U.S. Geological Survey (USGS) produces geospatial datasets providing information on land cover, predicted species distributions, stewardship (ownership and conservation status), and an analysis dataset which synthesizes the other three datasets. The intent in providing these datasets is to support the conservation of biodiversity. The datasets are made available at no cost. The initial datasets were created at the state level. More recent datasets have been assembled at regional and national levels. GAP entered an agreement with the Policy Analysis and Science Assistance branch of the USGS to conduct an evaluation to describe the effect that using GAP data has on those who utilize the datasets (GAP users). The evaluation project included multiple components: a discussion regarding use of GAP data conducted with participants at a GAP conference, a literature review of publications that cited use of GAP data, and a survey of GAP users. The findings of the published literature search were used to identify topics to include on the survey. This report summarizes the literature search, the characteristics of the resulting set of publications, the emergent themes from statements made regarding GAP data, and a bibliometric analysis of the publications. We cannot claim that this list includes all publications that have used GAP data. Given the time lapse that is common in the publishing process, more recent datasets may be cited less frequently in this list of publications. Reports or products that used GAP data may be produced but never published in print or released online. In that case, our search strategies would not have located those reports. Authors may have used GAP data but failed to cite it in such a way that the search strategies we used would have located those publications. These are common issues when using a literature search as part of an evaluation project. Although the final list of publications we identified is not

  1. GASP: Gapped Ancestral Sequence Prediction for proteins

    Directory of Open Access Journals (Sweden)

    Shields Denis C

    2004-09-01

    Full Text Available Abstract Background The prediction of ancestral protein sequences from multiple sequence alignments is useful for many bioinformatics analyses. Predicting ancestral sequences is not a simple procedure and relies on accurate alignments and phylogenies. Several algorithms exist based on Maximum Parsimony or Maximum Likelihood methods but many current implementations are unable to process residues with gaps, which may represent insertion/deletion (indel events or sequence fragments. Results Here we present a new algorithm, GASP (Gapped Ancestral Sequence Prediction, for predicting ancestral sequences from phylogenetic trees and the corresponding multiple sequence alignments. Alignments may be of any size and contain gaps. GASP first assigns the positions of gaps in the phylogeny before using a likelihood-based approach centred on amino acid substitution matrices to assign ancestral amino acids. Important outgroup information is used by first working down from the tips of the tree to the root, using descendant data only to assign probabilities, and then working back up from the root to the tips using descendant and outgroup data to make predictions. GASP was tested on a number of simulated datasets based on real phylogenies. Prediction accuracy for ungapped data was similar to three alternative algorithms tested, with GASP performing better in some cases and worse in others. Adding simple insertions and deletions to the simulated data did not have a detrimental effect on GASP accuracy. Conclusions GASP (Gapped Ancestral Sequence Prediction will predict ancestral sequences from multiple protein alignments of any size. Although not as accurate in all cases as some of the more sophisticated maximum likelihood approaches, it can process a wide range of input phylogenies and will predict ancestral sequences for gapped and ungapped residues alike.

  2. GASP: Gapped Ancestral Sequence Prediction for proteins.

    Science.gov (United States)

    Edwards, Richard J; Shields, Denis C

    2004-09-06

    The prediction of ancestral protein sequences from multiple sequence alignments is useful for many bioinformatics analyses. Predicting ancestral sequences is not a simple procedure and relies on accurate alignments and phylogenies. Several algorithms exist based on Maximum Parsimony or Maximum Likelihood methods but many current implementations are unable to process residues with gaps, which may represent insertion/deletion (indel) events or sequence fragments. Here we present a new algorithm, GASP (Gapped Ancestral Sequence Prediction), for predicting ancestral sequences from phylogenetic trees and the corresponding multiple sequence alignments. Alignments may be of any size and contain gaps. GASP first assigns the positions of gaps in the phylogeny before using a likelihood-based approach centred on amino acid substitution matrices to assign ancestral amino acids. Important outgroup information is used by first working down from the tips of the tree to the root, using descendant data only to assign probabilities, and then working back up from the root to the tips using descendant and outgroup data to make predictions. GASP was tested on a number of simulated datasets based on real phylogenies. Prediction accuracy for ungapped data was similar to three alternative algorithms tested, with GASP performing better in some cases and worse in others. Adding simple insertions and deletions to the simulated data did not have a detrimental effect on GASP accuracy. GASP (Gapped Ancestral Sequence Prediction) will predict ancestral sequences from multiple protein alignments of any size. Although not as accurate in all cases as some of the more sophisticated maximum likelihood approaches, it can process a wide range of input phylogenies and will predict ancestral sequences for gapped and ungapped residues alike.

  3. EVA Systems Technology Gaps and Priorities 2017

    Science.gov (United States)

    Johnson, Brian J.; Buffington, Jesse A.

    2017-01-01

    Performance of Extra-Vehicular Activities (EVA) has been and will continue to be a critical capability for human space flight. Human exploration missions beyond LEO will require EVA capability for either contingency or nominal activities to support mission objectives and reduce mission risk. EVA systems encompass a wide array of products across pressure suits, life support systems, EVA tools and unique spacecraft interface hardware (i.e. EVA Translation Paths and EVA Worksites). In a fiscally limited environment with evolving transportation and habitation options, it is paramount that the EVA community's strategic planning and architecture integration products be reviewed and vetted for traceability between the mission needs far into the future to the known technology and knowledge gaps to the current investments across EVA systems. To ascertain EVA technology and knowledge gaps many things need to be brought together, assessed and analyzed. This includes an understanding of the destination environments, various mission concept of operations, current state of the art of EVA systems, EVA operational lessons learned, and reference advanced capabilities. A combined assessment of these inputs should result in well-defined list of gaps. This list can then be prioritized depending on the mission need dates and time scale of the technology or knowledge gap closure plan. This paper will summarize the current state of EVA related technology and knowledge gaps derived from NASA's Exploration EVA Reference Architecture and Operations Concept products. By linking these products and articulating NASA's approach to strategic development for EVA across all credible destinations an EVA could be done in, the identification of these gaps is then used to illustrate the tactical and strategic planning for the EVA technology development portfolio. Finally, this paper illustrates the various "touch points" with other human exploration risk identification areas including human health and

  4. Increasing gap junctional coupling: a tool for dissecting the role of gap junctions

    DEFF Research Database (Denmark)

    Axelsen, Lene Nygaard; Haugan, Ketil; Stahlhut, Martin;

    2007-01-01

    . In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing......Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes...... the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs...

  5. The Gender Wage Gap and Domestic Violence

    Science.gov (United States)

    Aizer, Anna

    2014-01-01

    Three quarters of all violence against women is perpetrated by domestic partners. This study exploits exogenous changes in the demand for labor in female-dominated industries to estimate the impact of the male-female wage gap on domestic violence. Decreases in the wage gap reduce violence against women, consistent with a household bargaining model. These findings shed new light on the health production process as well as observed income gradients in health and suggest that in addition to addressing concerns of equity and efficiency, pay parity can also improve the health of American women via reductions in violence. PMID:25110354

  6. The Gender Wage Gap and Domestic Violence.

    Science.gov (United States)

    Aizer, Anna

    2010-09-01

    Three quarters of all violence against women is perpetrated by domestic partners. This study exploits exogenous changes in the demand for labor in female-dominated industries to estimate the impact of the male-female wage gap on domestic violence. Decreases in the wage gap reduce violence against women, consistent with a household bargaining model. These findings shed new light on the health production process as well as observed income gradients in health and suggest that in addition to addressing concerns of equity and efficiency, pay parity can also improve the health of American women via reductions in violence.

  7. Maximizing band gaps in plate structures

    DEFF Research Database (Denmark)

    Halkjær, Søren; Sigmund, Ole; Jensen, Jakob Søndergaard

    2006-01-01

    Band gaps, i.e., frequency ranges in which waves cannot propagate, can be found in elastic structures for which there is a certain periodic modulation of the material properties or structure. In this paper, we maximize the band gap size for bending waves in a Mindlin plate. We analyze an infinite...... periodic plate using Bloch theory, which conveniently reduces the maximization problem to that of a single base cell. Secondly, we construct a finite periodic plate using a number of the optimized base cells in a postprocessed version. The dynamic properties of the finite plate are investigated...

  8. Gendered Justice Gaps in Bosnia-Herzegovina

    DEFF Research Database (Denmark)

    Björkdahl, Annika; Mannergren Selimovic, Johanna

    2014-01-01

    , and reparations gaps-this article examines structural constraints for women to engage in shaping and implementing transitional justice, and unmasks transitional justice as a site for the long-term construction of the gendered post-conflict order. Thus, the gendered dynamics of peacebuilding and transitional...... justice have produced a post-conflict order characterized by gendered peace and justice gaps. Yet, we conclude that women are doing justice within the Bosnian-Herzegovina transitional justice project, and that their presence and participation is complex, multilayered, and constrained yet critical. © 2013...

  9. Natural Gas Engine Development Gaps (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Zigler, B.T.

    2014-03-01

    A review of current natural gas vehicle offerings is presented for both light-duty and medium- and heavy-duty applications. Recent gaps in the marketplace are discussed, along with how they have been or may be addressed. The stakeholder input process for guiding research and development needs via the Natural Gas Vehicle Technology Forum (NGVTF) to the U.S. Department of Energy and the California Energy Commission is reviewed. Current high-level natural gas engine development gap areas are highlighted, including efficiency, emissions, and the certification process.

  10. Gribov gap equation at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Canfora, Fabrizio; Pais, Pablo [Centro de Estudios Cientificos (CECS), Valdivia (Chile); Universidad Andres Bello, Santiago (Chile); Salgado-Rebolledo, Patricio [Centro de Estudios Cientificos (CECS), Valdivia (Chile); Universidad de Concepcion, Departamento de Fisica, Concepcion (Chile); Universite Libre de Bruxelles and International Solvay Insitutes, Physique Theorique et Mathematique, Bruxelles (Belgium)

    2014-05-15

    In this paper the Gribov gap equation at finite temperature is analyzed. The solutions of the gap equation (which depend explicitly on the temperature) determine the structure of the gluon propagator within the semi-classical Gribov approach. The present analysis is consistent with the standard confinement scenario for low temperatures, while for high enough temperatures, deconfinement takes place and a free gluon propagator is obtained. An intermediate regime in between the confined and free phases can be read off from the resulting gluon propagator, which appears to be closely related to partial deconfinement. (orig.)

  11. Closing the R&D Gap

    OpenAIRE

    Thomas Karier

    1999-01-01

    This study identifies a clear need for government policy to address the widening R&D gap between the United States, Japan and Germany. In 1991, the United States spent only 1.9 percent of its GDP on nondefense R&D compared to 3 percent for Japan and 2.7 percent for Germany. The possibility that his gap can be closed through tax incentives, such as the Research and Experimentation tax credit, appears highly unlikely. A detailed review of this credit shows that it had a relatively minor impact ...

  12. Security Gaps In Authentication Factor Credentials

    Directory of Open Access Journals (Sweden)

    Neeraj A. Sharma

    2015-08-01

    Full Text Available Authentication factors refer to user login credentials that a user supplies to an authentication process for it to decide whether to grant or deny access. While two-factor and three-factor authentication generally provides better security than one-factor authentication the aim of this paper is to review security in individual authentication factor credentials that are in use nowadays. These credentials will be discussed in factor categories knowledge factor possession factor and inherence factor. The paper details current security gaps and some novel approaches to diminish the gaps in these authentication factors. We believe that our recommendations will inspire development of better authentication credentials and systems.

  13. Spin gap in a spiral staircase model

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, M.N. [Institut fuer Theoretische Physik und Astrophysik, Wuerzburg Universitaet, Am Hubland, D-97074 Wuerzburg (Germany)]. E-mail: kiselev@physik.uni-wuerzburg.de; Aristov, D.N. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Kikoin, K. [Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2005-04-30

    We investigate the formation of spin gap in one-dimensional models characterized by the groups with hidden symmetries. We introduce a new class of Hamiltonians for description of spin staircases-the spin systems intermediate between 2-leg ladders and S=1 spin chains. The spin exchange anisotropy along legs is described by the angle of spiral twist. The properties of a special case of spin rotator chain (SRC) corresponding to a flat 1-leg ladder is considered by means of fermionization approach based on Jordan-Wigner transformation. The influence of dynamical hidden symmetries on the scaling properties of the spin gap is discussed.

  14. The Gender Gap in European Business Schools

    DEFF Research Database (Denmark)

    Roseberry, Lynn; Remke, Robyn; Klæsson, Johan

    "The Gender Gap in European Business Schools: A Leadership Perspective" is a research project initiated and funded by EFMD, EQUAL, and the business schools represented on the project’s Steering Committee with following motivations for the study: Numerous studies by policy makers and academics have...... documented the existence of a faculty gender gap in Higher Education Institutions (HEIs), which starts at the bottom of the academic hierarchy at the Ph.D. level and grows wider at each succeeding stage in the academic career path. As of 2013, women still represented less than 30% of grade A academic staff...

  15. Flexowriters, Punch Paper Poetry and Ontological Gaps

    DEFF Research Database (Denmark)

    Søndergaard, Morten

    2013-01-01

    this position as being as close to the current state of affairs at this point in time as may be achieved (and I think it is), then we still need to ask ourselves: what happened to the archive-material that did not ‘fit’ the technologies and politics of the archive? If and when the transformation of the archive...... able to close the gap between the different paradigmatic ‘regimes’ defining the archival practice in the process of transformation. The ‘unheard’ not only witnesses this on an empirical level; it points, I would claim, towards an ontological gap between archival practices and the theoretical scope...

  16. SAR backscatter from coniferous forest gaps

    Science.gov (United States)

    Day, John L.; Davis, Frank W.

    1992-01-01

    A study is in progress comparing Airborne Synthetic Aperture Radar (AIRSAR) backscatter from coniferous forest plots containing gaps to backscatter from adjacent gap-free plots. Issues discussed are how do gaps in the range of 400 to 1600 sq m (approximately 4-14 pixels at intermediate incidence angles) affect forest backscatter statistics and what incidence angles, wavelengths, and polarizations are most sensitive to forest gaps. In order to visualize the slant-range imaging of forest and gaps, a simple conceptual model is used. This strictly qualitative model has led us to hypothesize that forest radar returns at short wavelengths (eg., C-band) and large incidence angles (e.g., 50 deg) should be most affected by the presence of gaps, whereas returns at long wavelengths and small angles should be least affected. Preliminary analysis of 1989 AIRSAR data from forest near Mt. Shasta supports the hypothesis. Current forest backscatter models such as MIMICS and Santa Barbara Discontinuous Canopy Backscatter Model have in several cases correctly predicted backscatter from forest stands based on inputs of measured or estimated forest parameters. These models do not, however, predict within-stand SAR scene texture, or 'intrinsic scene variability' as Ulaby et al. has referred to it. For instance, the Santa Barbara model, which may be the most spatially coupled of the existing models, is not truly spatial. Tree locations within a simulated pixel are distributed according to a Poisson process, as they are in many natural forests, but tree size is unrelated to location, which is not the case in nature. Furthermore, since pixels of a simulated stand are generated independently in the Santa Barbara model, spatial processes larger than one pixel are not modeled. Using a different approach, Oliver modeled scene texture based on an hypothetical forest geometry. His simulated scenes do not agree well with SAR data, perhaps due to the simple geometric model used. Insofar as texture

  17. Closing the gap between formalism and application

    DEFF Research Database (Denmark)

    Christensen, Ole Ravn

    2008-01-01

    -based learning (PBL), in the special model used at Aalborg University, Denmark, may give us some idea of how to bridge this gap. Through an investigation of a series of examples of student projects concerning the application of mathematical subjects-such as matrices, differential equations, cluster analysis......A common problem in learning mathematics concerns the gap between, on the one hand, doing the formalisms and calculations of abstract mathematics and, on the other hand, applying these in a specific contextualized setting for example the engineering world. The skills acquired through problem...

  18. En introduksjon til Gap-modellen

    OpenAIRE

    Ranglund, Ole Jørgen

    2014-01-01

    GAP-modellen, som er forankret i det dominerende persepsjonspsykologiske perspektivet innen tjenesteforskningen, kan ofte være et velegnet redskap til bruk i organisasjoners kvalitetsrettede arbeid. Modellen, som har blitt forandret flere ganger, ble utviklet på midten av 1980-tallet (Parasuraman, Zeithaml og Berry 1985). Etter at forskning på tjenester for alvor skjøt fart litt ut på 1980-tallet har Gap-modellen vært sentral, og etter hvert har modellen fått hegemoni (Lindquist og Persson 19...

  19. Mechanics of Fluid-Filled Interstitial Gaps. II. Gap Characteristics in Xenopus Embryonic Ectoderm.

    Science.gov (United States)

    Barua, Debanjan; Parent, Serge E; Winklbauer, Rudolf

    2017-08-22

    The ectoderm of the Xenopus embryo is permeated by a network of channels that appear in histological sections as interstitial gaps. We characterized this interstitial space by measuring gap sizes, angles formed between adjacent cells, and curvatures of cell surfaces at gaps. From these parameters, and from surface-tension values measured previously, we estimated the values of critical mechanical variables that determine gap sizes and shapes in the ectoderm, using a general model of interstitial gap mechanics. We concluded that gaps of 1-4 μm side length can be formed by the insertion of extracellular matrix fluid at three-cell junctions such that cell adhesion is locally disrupted and a tension difference between cell-cell contacts and the free cell surface at gaps of 0.003 mJ/m(2) is generated. Furthermore, a cell hydrostatic pressure of 16.8 ± 1.7 Pa and an interstitial pressure of 3.9 ± 3.6 Pa, relative to the central blastocoel cavity of the embryo, was found to be consistent with the observed gap size and shape distribution. Reduction of cell adhesion by the knockdown of C-cadherin increased gap volume while leaving intracellular and interstitial pressures essentially unchanged. In both normal and adhesion-reduced ectoderm, cortical tension of the free cell surfaces at gaps does not return to the high values characteristic of the free surface of the whole tissue. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  20. Single-electron gap in the spectrum of twisted bilayer graphene

    Science.gov (United States)

    Rozhkov, A. V.; Sboychakov, A. O.; Rakhmanov, A. L.; Nori, Franco

    2017-01-01

    We investigate the gap in the single-electron spectrum of twisted bilayer graphene. In a perfect infinite lattice of a twisted bilayer, the gap varies exponentially in response to weak changes of the twist angle. Such a large sensitivity makes theoretical predictions of the gap nearly impossible, since experimentally the twist angle is always known with finite accuracy. To address this issue, we numerically study finite clusters of twisted bilayer graphene. For finite systems, changing the twist angle causes a gradual crossover between gapless and gapped regimes. The crossover occurs when the finite-size quantization energy becomes comparable to the matrix elements responsible for the generation of the gap. We further argue that disorder scattering can induce similar crossover, in which the mean-free path plays the same role as the system size for the finite clusters. It is demonstrated that to observe the gap experimentally, it is necessary to have a sample of suitable purity and to possess the ability to tune the twist angle accurately.

  1. Delayed high anion gap metabolic acidosis after a suicide attempt: case report.

    Science.gov (United States)

    Hsiao, Po-Jen; Chen, Tsu-Yi; Chiu, Chih-Chien; Wu, Tsung-Jui; Chan, Jenq-Shyong; Wu, Chia-Chao; Chen, Jin-Shuen

    2014-09-25

    Metabolic acidosis, especially when induced by multiple drug poisoning, often makes rapid and accurate differential diagnosis of the condition challenging. We closely followed anion and osmolal gaps to differentiate among the aetiologies of metabolic acidosis caused by poisoning with unknown drugs. The patient was admitted to our emergency department (ED) in an alert and consciousness state after attempting suicide by ingestion of an uncertain quantity of rodenticides combined with an unknown liquid. Initially, metabolic acidosis (pH7.23) with normal anion gap (12.8) was observed. However, a change in consciousness and hypotension subsequently developed 6h later, combined with severe metabolic acidosis (pH7.16), high anion gap (25.5), and high osmolal gap (83). A presumed diagnosis of methanol intoxication was suspected. After 4h of high-flux haemodialysis (HD), the serum bicarbonate returned to 23 mmol/l, and the patient regained consciousness. The serum level of methanol before HD was 193.8 mg/dl. The patient was discharged nine days later without sequelae. Delayed high anion gap metabolic acidosis may occur in the ED. Frequent monitoring of anion and osmolal gaps is a feasible method to perform a rapid differential diagnosis, particularly in response to drug poisoning. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Dynamic Model of Gap Loop for HCW Mill

    Institute of Scientific and Technical Information of China (English)

    YANG Jing-ming; YANG Qiu-xia; CHE Hai-jun; CHANG Ling-fang

    2004-01-01

    The hydraulic automatic gauge control system using gap loop for cold mill was designed. The stiffness of HCW cold mill was defined for gap loop, and the dynamic model of gauge control system for gap loop was built with mechanism analysis. The stiffness for gap loop and the cylinder displacement loop were measured.

  3. Test of a four-gap resistive plate chamber with cosmic muons and high-rate gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.K.; Shin, S.S.; Hong, B.; Jhang, G.; Jeong, M.S.; Jo, M.; Cho, S.W.; Joo, E.; Kim, C.; Kim, H.C. [Department of Physics and Korea Detector Laboratory, Korea University, Seoul 136-701 (Korea, Republic of); Lee, K.S., E-mail: kslee0421@korea.ac.kr [Department of Physics and Korea Detector Laboratory, Korea University, Seoul 136-701 (Korea, Republic of); Lee, K.S.; Lee, S.; Lee, S.K.; Lim, J.K.; Moon, D.H.; Shim, H.H.; Sim, K.S. [Department of Physics and Korea Detector Laboratory, Korea University, Seoul 136-701 (Korea, Republic of)

    2012-07-11

    We report a new development of a phenolic four-gap resistive plate chamber (RPC) for use as a high-rate particle trigger in high-energy physics experiments. In the current study, a prototype RPC equipped with four 1-mm-thick gaps made from high-pressure-laminated (HPL) resistive plates has been designed and built. The current detector R and D aims to reduce the probability of radiation-induced degradation of the core detector components of the RPCs, the gas gaps, as well as to improve the detection rate capability. The detector characteristics of the four-gap RPC were obtained though a series of tests with cosmic muons and gamma rays and were compared with those of the typical 2-mm thick double-gap RPCs currently used in the CMS experiment at the LHC and in the PHENIX experiment at the RHIC.

  4. Interplay of spin gap and nanoscopic quantum fluctuations in intermetallic CeCu{sub 2}Ge{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Singh, D.K.

    2014-05-01

    Neutron scattering measurements are used to elucidate interplay of the field-induced spin gap and the quantum fluctuations in archetypal heavy electron system CeCu{sub 2}Ge{sub 2}. A spin gap of Δ=0.56 meV is found to develop near the field-induced quantum critical state at H{sub c}≃8 T-driven by fluctuations of the long range antiferromagnetic order parameter. The superconducting transition temperature in many magnetic superconductors is found to exhibit one-to-one correspondence with the spin gap. In this regard, the demonstration of an interplay of the spin gap with the nanoscopic dynamic correlation provides new arena to explore direct relation between the quantum critical behavior and the unconventional superconductivity, especially in heavy electrons systems.

  5. Variable band-gap semiconductors as the basis of new solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Acevedo, Arturo [Centro de Investigacion y de Estudios Avanzados del IPN, Electrical Engineering Department, Avenida IPN No. 2508, 07360 Mexico, DF (Mexico)

    2009-09-15

    Some basic concepts related to variable band-gap absorbing semiconductors in solar cell structures, such as the associated quasi-electric field, will be discussed. The effects of this quasi-electric field upon the minority carrier drift-diffusion length and the back surface recombination velocity may induce a larger generated carrier collection at the junction with the corresponding increase of the illumination current density. It will also be shown that an additional improvement of the open-circuit voltage is possible when the band-gap is reduced within the space charge region so that the dark saturation current density is reduced there. Our estimation is that in the case of a solar cell where the band-gap is changed about 0.5 eV within the space charge region, an increase of the open-circuit voltage around 115 mV will be observed with respect to the single minimum band-gap absorbing material case. A similar band-gap variation in the bulk of the material will cause an increase of the minority carrier drift-diffusion length by a factor of 10 with respect to the single band-gap material. Therefore, based on these physical concepts, two possible structures with variable band-gap layers are proposed in order to have higher efficiencies than for cells without any band-gap grading. It will be shown that these concepts can be applied to II-VI, III-V chalcopyrite and even amorphous semiconductor solar cells. (author)

  6. Closing the Achievement Gap on ACT & SAT

    Science.gov (United States)

    Anderson, David

    2010-01-01

    Research has focused on four groups of factors and the achievement gap: (1) student characteristics (high school GPA, attendance patterns, courses taken in high school, participation in extra-curricular activities, etc.); (2) family characteristics (family structure, in home, parents' level of education, mobility, etc.); (3) school-based…

  7. The Wage Gap: Briefing Paper #1.

    Science.gov (United States)

    National Committee on Pay Equity, Washington, DC.

    Women have made slow, steady progress in the labor market since 1979, but the wage gap has not narrowed significantly. This briefing paper updates a September 1987 paper based on "Male-Female Differences in Work Experience, Occupations, and Earnings: 1984" (Current Population Reports, Household Economic Studies, Series P-70, No. 10, issued in…

  8. Plasmonic band gap cavities on biharmonic gratings

    Science.gov (United States)

    Kocabas, Askin; Seckin Senlik, S.; Aydinli, Atilla

    2008-05-01

    In this paper, we have experimentally demonstrated the formation of plasmonic band gap cavities in infrared and visible wavelength range. The cavity structure is based on a biharmonic metallic grating with selective high dielectric loading. A uniform metallic grating structure enables strong surface plasmon polariton (SPP) excitation and a superimposed second harmonic component forms a band gap for the propagating SPPs. We show that a high dielectric superstructure can dramatically perturb the optical properties of SPPs and enables the control of the plasmonic band gap structure. Selective patterning of the high index superstructure results in an index contrast in and outside the patterned region that forms a cavity. This allows us to excite the SPPs that localize inside the cavity at specific wavelengths, satisfying the cavity resonance condition. Experimentally, we observe the formation of a localized state in the band gap and measure the dispersion diagram. Quality factors as high as 37 have been observed in the infrared wavelength. The simplicity of the fabrication and the method of testing make this approach attractive for applications requiring localization of propagating SPPs.

  9. A Theory of Gender Wage Gap

    OpenAIRE

    Jellal, Mohamed; Nordman, Christophe

    2009-01-01

    In this paper, we introduce uncertainty of the labour productivity of women in a competitive model of wage determination. We demonstrate that more qualified women are then offered much lower wages than men at the equilibrium. This result is consistent with the glass ceiling hypothesis according to which there exist larger gender wage gaps at the upper tail of the wage distribution.

  10. Producing gapped-ferrite transformer cores

    Science.gov (United States)

    Mclyman, W. T.

    1980-01-01

    Improved manufacturing techniques make reproducible gaps and minimize cracking. Molded, unfired transformer cores are cut with thin saw and then fired. Hardened semicircular core sections are bonded together, placed in aluminum core box, and fluidized-coated. After winding is run over box, core is potted. Economical method significantly reduces number of rejects.

  11. FINAL REPORT ON GDE GAP CELL

    Energy Technology Data Exchange (ETDEWEB)

    Herman, D.; Summers, W.; Danko, E.

    2009-09-28

    A project has been undertaken to develop an electrochemical cell and support equipment for evaluation of a gas diffusion electrode-based, narrow-electrolyte-gap anode for SO{sub 2} oxidation in the hydrogen production cycle of the hybrid sulfur (HyS) process. The project supported the HyS development program at the Savannah River National Lab (SRNL). The benefits of using a gas diffusion electrode in conjunction with the narrow anolyte gap are being determined through electrochemical polarization testing under a variety conditions, and by comparison to results produced by SRNL and others using anode technologies that have no anolyte gap. These test results indicate that the NGA cell has low resistance suitable for use in the HyS electrolyzer, exhibits good efficiency at high current densities compared to the direct feed HyS electrolyzer, and indicates robust performance in extended testing over 65 hours. Seepage episodes were mostly caused by port clogging, which can be mitigated in future designs through minor modifications to the hardware. Significant reductions in sulfur crossover have not yet been demonstrated in the NGA configuration compared to in-house direct feed testing, but corroborative sulfur layer analysis is as yet incomplete. Further testing in a single-pass anolyte configuration is recommended for complete evaluation of steady-state electrochemical efficiency and SO{sub 2} crossover in the narrow gap configuration.

  12. Gap junction diseases of the skin.

    NARCIS (Netherlands)

    Steensel, M.A.M. van

    2004-01-01

    Gap junctions are intercellular channels that allow the passage of water, ions, and small molecules. They are involved in quick, short-range messaging between cells and are found in skin, nervous tissue, heart, and muscle. An increasing number of hereditary skin disorders appear to be caused by muta

  13. The deposit financing gap: another Dutch disease

    NARCIS (Netherlands)

    Meijers, H.H.M.; Muysken, J.; Sleijpen, O.C.H.M.

    2015-01-01

    In the last 2 decades, the Netherlands has experienced an increase in real-estate prices, accompanied by an increase in mortgages and a marked decline in household savings. As a consequence, banks are faced with a large retail funding gap: outstanding mortgage debt is insufficiently matched by

  14. The deposit financing gap: Another Dutch disease

    NARCIS (Netherlands)

    Meijers, H.H.M.; Muysken, J.; Sleijpen, O.C.H.M.

    2014-01-01

    In the last two decades the Netherlands have experienced an increase in real-estate prices, accompanied by an increase in mortgages and a marked decline in household savings. As a consequence banks are faced with a large retail funding gap: outstanding mortgage debt is insufficiently matched by

  15. The deposit financing gap: Another Dutch disease

    NARCIS (Netherlands)

    Meijers, H.H.M.; Muysken, J.; Sleijpen, O.C.H.M.

    2014-01-01

    In the last two decades the Netherlands have experienced an increase in real-estate prices, accompanied by an increase in mortgages and a marked decline in household savings. As a consequence banks are faced with a large retail funding gap: outstanding mortgage debt is insufficiently matched by reta

  16. The deposit financing gap: another Dutch disease

    NARCIS (Netherlands)

    Meijers, H.H.M.; Muysken, J.; Sleijpen, O.C.H.M.

    2015-01-01

    In the last 2 decades, the Netherlands has experienced an increase in real-estate prices, accompanied by an increase in mortgages and a marked decline in household savings. As a consequence, banks are faced with a large retail funding gap: outstanding mortgage debt is insufficiently matched by retai

  17. EurepGAP certification for small producers

    NARCIS (Netherlands)

    Valk, van der O.M.C.

    2006-01-01

    The majority of agriculture practitioners worldwide are smallholders. Compliance with market related standards, such as set by EurepGAP, is crucial for obtaining and maintaining international market access, particularly to the European Union. Private standards must allow for innovative and cost effi

  18. Auditory gap detection in the early blind.

    Science.gov (United States)

    Weaver, Kurt E; Stevens, Alexander A

    2006-01-01

    For blind individuals, audition provides critical information for interacting with the environment. Individuals blinded early in life (EB) typically show enhanced auditory abilities relative to sighted controls as measured by tasks requiring complex discrimination, attention and memory. In contrast, few deficits have been reported on tasks involving auditory sensory thresholds (e.g., Yates, J.T., Johnson, R.M., Starz, W.J., 1972. Loudness perception of the blind. Audiology 11(5), 368-376; Starlinger, I., Niemeyer, W., 1981. Do the blind hear better? Investigations on auditory processing in congenital or early acquired blindness. I. Peripheral functions. Audiology 20(6), 503-509). A study of gap detection stands at odds with this distinction [Muchnik, C., Efrati, M., Nemeth, E., Malin, M., Hildesheimer, M., 1991. Central auditory skills in blind and sighted subjects. Scand. Audiol. 20(1), 19-23]. In the current investigation we re-examined gap detection abilities in the EB using a single-interval, yes/no method. A group of younger sighted control individuals (SCy) was included in the analysis in addition to EB and sighted age matched control individuals (SCm) in order to examine the effect of age on gap detection performance. Estimates of gap detection thresholds for EB subjects were nearly identical to SCm subjects and slightly poorer relative to the SCy subjects. These results suggest some limits on the extent of auditory temporal advantages in the EB.

  19. The Gaps of Which Communication Is Made.

    Science.gov (United States)

    Peters, John Durham

    1994-01-01

    Argues that the gap between transmission and reception is fundamental to most communication. Summarizes theorizing on communication and mass communication in Plato, about U.S. broadcasting, and in hermeneutics. Concludes that a conceptual contrast between open dissemination (mass) and individualized interaction (interpersonal) is inevitable…

  20. Topological scaling and gap filling at crisis

    Energy Technology Data Exchange (ETDEWEB)

    Szabo, K. Gabor [Department of Mathematics, University of Kansas, Lawrence, Kansas 66045 (United States); Institute for Theoretical Physics, Eoetvoes University, P.O. Box 32, Budapest, H-1518, (Hungary); Lai, Ying-Cheng [Department of Mathematics and Department of Electrical Engineering, Arizona State University, Tempe, Arizona 85287 (United States); Tel, Tamas [Institute for Theoretical Physics, Eoetvoes University, P.O. Box 32, Budapest, H-1518, (Hungary); Grebogi, Celso [Institute for Plasma Research, Department of Mathematics, and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States)

    2000-05-01

    Scaling laws associated with an interior crisis of chaotic dynamical systems are studied. We argue that open gaps of the chaotic set become densely filled at the crisis due to the sudden appearance of unstable periodic orbits with extremely long periods. We formulate a scaling theory for the associated growth of the topological entropy. (c) 2000 The American Physical Society.

  1. Band Gap Narrowing in Heavily Doped Silicon.

    Science.gov (United States)

    Gupta, Tapan Kumar

    Two analytic models for transport and band gap narrowing in heavily doped (N_{rm D} > 10^{20} cm^ {-3}) silicon have been set up and verified through measurements on n^{+} -p junction devices. The first model is based on calculation of the ratio of the charge present in the emitter of the n^{+} region of the junction to that of the charge present in the absence of band gap shrinkage. Fermi-Dirac statistics are employed and are found to have a significant effect at this doping level. The second model is based on current transport of minority carriers in the n^{+} region. In this model only two parameters need to be known, the diffusion coefficient and the diffusion length for minority carriers, to calculate the band gap narrowing. An empirical relation between band gap narrowing and donor concentration has also been established based on experimental values of diffusion coefficient and mobility. These models have been verified by several different experimental techniques including surface photovoltage, open circuit voltage decay, photoconductivity decay and modulation reflection spectroscopy. The results indicate that, in the impurity range above about 10^{20} cm^{-3}, Fermi-Dirac statistics must be invoked in order to achieve a satisfactory fit with experimental data.

  2. Energy Gaps in a Spacetime Crystal

    CERN Document Server

    Horwitz, L P

    2009-01-01

    This paper presents an analysis of the band structure of a spacetime potential lattice created by a standing electromagnetic wave. We show that there are energy band gaps. We estimate the effect, and propose a measurement that could confirm the existence of such phenomena.

  3. Quantifying the Gender Gap in Science Interests

    Science.gov (United States)

    Baram-Tsabari, Ayelet; Yarden, Anat

    2011-01-01

    Nearly 5,000 self-generated science-related K-12 students' questions, classified into seven science subjects, were used to quantitatively measure the gender gap in science interests and its change with age. In this data set, a difference between boys' and girls' science interests did not exist during early childhood, but increased over 20-fold by…

  4. Subgroup Achievement and Gap Trends: Hawaii

    Science.gov (United States)

    Center on Education Policy, 2010

    2010-01-01

    Hawaii showed improvement in reading and math in grade 8 at the basic, proficient, and advanced levels for Asian and white students, low income students, and boys and girls. Gains in math tended to be larger than in reading. Trends in closing achievement gaps were mixed. Comparable data were available from 2007 through 2009. (Contains 9 tables.)…

  5. The Reed Elsevier stock price gap

    NARCIS (Netherlands)

    Kamp, B.

    1995-01-01

    This is the report of a limited study on the structural stock price differences between Reed and Elsevier. The purpose of this study is to provide an overview of the problem area and to formulate and discuss several hypotheses regarding the causes of this gap. The research was performed by

  6. Gap junction diseases of the skin.

    NARCIS (Netherlands)

    Steensel, M.A.M. van

    2004-01-01

    Gap junctions are intercellular channels that allow the passage of water, ions, and small molecules. They are involved in quick, short-range messaging between cells and are found in skin, nervous tissue, heart, and muscle. An increasing number of hereditary skin disorders appear to be caused by muta

  7. Ethnicity and Gender Gaps in Early Childhood

    Science.gov (United States)

    Hansen, Kirstine; Jones, Elizabeth M.

    2011-01-01

    Gender differences in academic performance and achievement have been of policy concern for decades--both interest in lower performance by girls in the areas of mathematics and science and, more recently, in boys' underperformance in most other academic areas. Much previous research has focused on gender gaps, while overlooking other factors that…

  8. The Gender Gap in European Business Schools

    DEFF Research Database (Denmark)

    Roseberry, Lynn; Remke, Robyn; Klæsson, Johan

    "The Gender Gap in European Business Schools: A Leadership Perspective" is a research project initiated and funded by EFMD, EQUAL, and the business schools represented on the project’s Steering Committee with following motivations for the study: Numerous studies by policy makers and academics have...

  9. Decomposing Achievement Gaps among OECD Countries

    Science.gov (United States)

    Zhang, Liang; Lee, Kristen A.

    2011-01-01

    In this study, we use decomposition methods on PISA 2006 data to compare student academic performance across OECD countries. We first establish an empirical model to explain the variation in academic performance across individuals, and then use the Oaxaca-Blinder decomposition method to decompose the achievement gap between each of the OECD…

  10. Gaps in agricultural climate adaptation research

    Science.gov (United States)

    Davidson, Debra

    2016-05-01

    The value of the social sciences to climate change research is well recognized, but notable gaps remain in the literature on adaptation in agriculture. Contributions focus on farmer behaviour, with important research regarding gender, social networks and institutions remaining under-represented.

  11. Colored neon flanks and line gap enhancement.

    Science.gov (United States)

    Redies, C; Spillmann, L; Kunz, K

    1984-01-01

    When a colored line connects two black (or differently colored) lines across a gap, colored neon flanks are seen on either side of it. These flanks extend over gap sizes of 50 min arc foveally and are not explained by Bezold-type assimilation. They may be elicited by black lines as short as 6 min arc adjoining the colored line at each end. To maximize these flanks, the black and colored lines must appear linearly continuous. Nonaligned junctions weaken the effect and an angular tilt of more than 40 dog destroys it. In this and other respects, (local) neon flanks are similar to van Tuijl's (global) neon color spreading (1975). Both phenomena have analogs in brightness perception. We propose that neon spreading is a lateral extension of neon flanks across the empty space between them, and discuss similarities of these effects with other brightness illusions (Schumann, Prandtl, Ehrenstein). For this group of illusions the term "line gap enhancement" is introduced to imply perceptual enhancement of changes in brightness and/or color along lines. Correspondences between the psychophysical properties and structural prerequisites for line gap enhancement on one hand and neuronal response properties of end-zone inhibited (hypercomplex) cortical cells on the other are discussed.

  12. Radial-Gap Motor for Ship Propulsion

    Science.gov (United States)

    Yanamoto, Toshiyuki; Yokoyama, Minoru

    The KHI team has developed radial gap high-temperature superconducting (HTS) motors of three sizes, 1 MW-class, 3 MW, and 20 MW, to be used for electric propulsion systems for ships. The volumetric torque density of the assembled 3 MW HTS motor was recorded at 40 kNm/m3 in the load test; the world's highest in the class.

  13. EurepGAP certification for small producers

    NARCIS (Netherlands)

    Valk, van der O.M.C.

    2006-01-01

    The majority of agriculture practitioners worldwide are smallholders. Compliance with market related standards, such as set by EurepGAP, is crucial for obtaining and maintaining international market access, particularly to the European Union. Private standards must allow for innovative and cost effi

  14. FINAL REPORT ON GDE GAP CELL

    Energy Technology Data Exchange (ETDEWEB)

    Herman, D.; Summers, W.; Danko, E.

    2009-09-28

    A project has been undertaken to develop an electrochemical cell and support equipment for evaluation of a gas diffusion electrode-based, narrow-electrolyte-gap anode for SO{sub 2} oxidation in the hydrogen production cycle of the hybrid sulfur (HyS) process. The project supported the HyS development program at the Savannah River National Lab (SRNL). The benefits of using a gas diffusion electrode in conjunction with the narrow anolyte gap are being determined through electrochemical polarization testing under a variety conditions, and by comparison to results produced by SRNL and others using anode technologies that have no anolyte gap. These test results indicate that the NGA cell has low resistance suitable for use in the HyS electrolyzer, exhibits good efficiency at high current densities compared to the direct feed HyS electrolyzer, and indicates robust performance in extended testing over 65 hours. Seepage episodes were mostly caused by port clogging, which can be mitigated in future designs through minor modifications to the hardware. Significant reductions in sulfur crossover have not yet been demonstrated in the NGA configuration compared to in-house direct feed testing, but corroborative sulfur layer analysis is as yet incomplete. Further testing in a single-pass anolyte configuration is recommended for complete evaluation of steady-state electrochemical efficiency and SO{sub 2} crossover in the narrow gap configuration.

  15. Health disparities and gaps in school readiness.

    Science.gov (United States)

    Currie, Janet

    2005-01-01

    The author documents pervasive racial disparities in the health of American children and analyzes how and how much those disparities contribute to racial gaps in school readiness. She explores a broad sample of health problems common to U.S. children, such as attention deficit hyperactivity disorder, asthma, and lead poisoning, as well as maternal health problems and health-related behaviors that affect children's behavioral and cognitive readiness for school. If a health problem is to affect the readiness gap, it must affect many children, it must be linked to academic performance or behavior problems, and it must show a racial disparity either in its prevalence or in its effects. The author focuses not only on the black-white gap in health status but also on the poor-nonpoor gap because black children tend to be poorer than white children. The health conditions Currie considers seriously impair cognitive skills and behavior in individual children. But most explain little of the overall racial gap in school readiness. Still, the cumulative effect of health differentials summed over all conditions is significant. Currie's rough calculation is that racial differences in health conditions and in maternal health and behaviors together may account for as much as a quarter of the racial gap in school readiness. Currie scrutinizes several policy steps to lessen racial and socioeconomic disparities in children's health and to begin to close the readiness gap. Increasing poor children's eligibility for Medicaid and state child health insurance is unlikely to be effective because most poor children are already eligible for public insurance. The problem is that many are not enrolled. Even increasing enrollment may not work: socioeconomic disparities in health persist in Canada and the United Kingdom despite universal public health insurance. The author finds more promise in strengthening early childhood programs with a built-in health component, like Head Start; family

  16. The role of gap edge instabilities in setting the depth of planet gaps in protoplanetary discs

    Science.gov (United States)

    Hallam, P. D.; Paardekooper, S.-J.

    2017-08-01

    It is known that an embedded massive planet will open a gap in a protoplanetary disc via angular momentum exchange with the disc material. The resulting surface density profile of the disc is investigated for one-dimensional and two-dimensional disc models and, in agreement with previous work, it is found that one-dimensional gaps are significantly deeper than their two-dimensional counterparts for the same initial conditions. We find, by applying one-dimensional torque density distributions to two-dimensional discs containing no planet, that the excitement of the Rossby wave instability and the formation of Rossby vortices play a critical role in setting the equilibrium depth of the gap. Being a two-dimensional instability, this is absent from one-dimensional simulations and does not limit the equilibrium gap depth there. We find similar gap depths between two-dimensional gaps formed by torque density distributions, in which the Rossby wave instability is present, and two-dimensional planet gaps, in which no Rossby wave instability is present. This can be understood if the planet gap is maintained at marginal stability, even when there is no obvious Rossby wave instability present. Further investigation shows the final equilibrium gap depth is very sensitive to the form of the applied torque density distribution, and using improved one-dimensional approximations from three-dimensional simulations can go even further towards reducing the discrepancy between one- and two-dimensional models, especially for lower mass planets. This behaviour is found to be consistent across discs with varying parameters.

  17. A WXW motif is required for the anticancer activity of the TAT-RasGAP317-326 peptide.

    Science.gov (United States)

    Barras, David; Chevalier, Nadja; Zoete, Vincent; Dempsey, Rosemary; Lapouge, Karine; Olayioye, Monilola A; Michielin, Olivier; Widmann, Christian

    2014-08-22

    TAT-RasGAP317-326, a cell-permeable 10-amino acid-long peptide derived from the N2 fragment of p120 Ras GTPase-activating protein (RasGAP), sensitizes tumor cells to apoptosis induced by various anticancer therapies. This RasGAP-derived peptide, by targeting the deleted in liver cancer-1 (DLC1) tumor suppressor, also hampers cell migration and invasion by promoting cell adherence and by inhibiting cell movement. Here, we systematically investigated the role of each amino acid within the RasGAP317-326 sequence for the anticancer activities of TAT-RasGAP317-326. We report here that the first three amino acids of this sequence, tryptophan, methionine, and tryptophan (WMW), are necessary and sufficient to sensitize cancer cells to cisplatin-induced apoptosis and to reduce cell migration. The WMW motif was found to be critical for the binding of fragment N2 to DLC1. These results define the interaction mode between the active anticancer sequence of RasGAP and DLC1. This knowledge will facilitate the design of small molecules bearing the tumor-sensitizing and antimetastatic activities of TAT-RasGAP317-326.

  18. A WXW Motif Is Required for the Anticancer Activity of the TAT-RasGAP317–326 Peptide*

    Science.gov (United States)

    Barras, David; Chevalier, Nadja; Zoete, Vincent; Dempsey, Rosemary; Lapouge, Karine; Olayioye, Monilola A.; Michielin, Olivier; Widmann, Christian

    2014-01-01

    TAT-RasGAP317–326, a cell-permeable 10-amino acid-long peptide derived from the N2 fragment of p120 Ras GTPase-activating protein (RasGAP), sensitizes tumor cells to apoptosis induced by various anticancer therapies. This RasGAP-derived peptide, by targeting the deleted in liver cancer-1 (DLC1) tumor suppressor, also hampers cell migration and invasion by promoting cell adherence and by inhibiting cell movement. Here, we systematically investigated the role of each amino acid within the RasGAP317–326 sequence for the anticancer activities of TAT-RasGAP317–326. We report here that the first three amino acids of this sequence, tryptophan, methionine, and tryptophan (WMW), are necessary and sufficient to sensitize cancer cells to cisplatin-induced apoptosis and to reduce cell migration. The WMW motif was found to be critical for the binding of fragment N2 to DLC1. These results define the interaction mode between the active anticancer sequence of RasGAP and DLC1. This knowledge will facilitate the design of small molecules bearing the tumor-sensitizing and antimetastatic activities of TAT-RasGAP317–326. PMID:25008324

  19. Contribution of the Staebler-Wronski effect to gap-state absorption in hydrogenated amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Amer, N.M.; Skumanich, A.

    1982-07-01

    The contribution of light-induced conductivity and luminescense changes to gap-state absorption in a-Si:H was directly measured by photothermal deflection spectroscopy. It is shown that sample illumination enhances gap-state absorption while annealing restores its magnitude to the original level. Doping further enhances this absorption while compensation results in the smallest observed effect. The energy position of the affected states are determined to be 1.2-1.3 eV below the conduction band and tentatively attribute the enhancement to Si dangling bonds created by breaking the Si-Si bonds.

  20. Strong interaction of a transmon qubit with 1D band-gap medium

    Science.gov (United States)

    Liu, Yanbing; Sadri, Darius; Houck, Andrew; Bronn, Nicholas; Chow, Jerry; Gambetta, Jay

    2015-03-01

    The spontaneous emission of an atom will be enhanced or suppressed in a structured vacuum, commonly known as Purcell effect. Moreover, in a frequency gap medium, an atom-photon bound state is predicted to exist in the band gap, causing the localization of light. Here using the technology of circuit quantum electrodynamics, we experimentally explore this mechanism by fabricating a microwave step-impedance filter strongly coupled to a transmon qubit. Standard transmission and spectroscopy measurements support the existence of atom-photon bound states in the system. Correlation measurement shows that the atom-photon interaction induces strong correlation of the transmitted light through the system. Thanks support from IARPA