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Sample records for bacterial triphosphate tunnel

  1. Chunnel vision: Export and efflux through bacterial channel-tunnels

    OpenAIRE

    Andersen, Christian; Hughes, Colin; Koronakis, Vassilis

    2000-01-01

    The Escherichia coli TolC protein is central to toxin export and drug efflux across the inner and outer cell membranes and the intervening periplasmic space. The crystal structure has revealed that TolC assembles into a remarkable α-helical trans-periplasmic cylinder (tunnel) embedded in the outer membrane by a contiguous β-barrel (channel), so providing a large duct open to the outside environment. The channel-tunnel structure is conserved in TolC homologues throughout Gram-negative bacteria...

  2. Imaging Adenosine Triphosphate (ATP).

    Science.gov (United States)

    Rajendran, Megha; Dane, Eric; Conley, Jason; Tantama, Mathew

    2016-08-01

    Adenosine triphosphate (ATP) is a universal mediator of metabolism and signaling across unicellular and multicellular species. There is a fundamental interdependence between the dynamics of ATP and the physiology that occurs inside and outside the cell. Characterizing and understanding ATP dynamics provide valuable mechanistic insight into processes that range from neurotransmission to the chemotaxis of immune cells. Therefore, we require the methodology to interrogate both temporal and spatial components of ATP dynamics from the subcellular to the organismal levels in live specimens. Over the last several decades, a number of molecular probes that are specific to ATP have been developed. These probes have been combined with imaging approaches, particularly optical microscopy, to enable qualitative and quantitative detection of this critical molecule. In this review, we survey current examples of technologies available for visualizing ATP in living cells, and identify areas where new tools and approaches are needed to expand our capabilities.

  3. Laboratory procedures manual for the firefly luciferase assay for adenosine triphosphate (ATP)

    Science.gov (United States)

    Chappelle, E. W.; Picciolo, G. L.; Curtis, C. A.; Knust, E. A.; Nibley, D. A.; Vance, R. B.

    1975-01-01

    A manual on the procedures and instruments developed for the adenosine triphosphate (ATP) luciferase assay is presented. Data cover, laboratory maintenance, maintenance of bacterial cultures, bacteria measurement, reagents, luciferase procedures, and determination of microbal susceptibility to antibiotics.

  4. Optical Aptasensors for Adenosine Triphosphate

    Science.gov (United States)

    Ng, Stella; Lim, Hui Si; Ma, Qian; Gao, Zhiqiang

    2016-01-01

    Nucleic acids are among the most researched and applied biomolecules. Their diverse two- and three-dimensional structures in conjunction with their robust chemistry and ease of manipulation provide a rare opportunity for sensor applications. Moreover, their high biocompatibility has seen them being used in the construction of in vivo assays. Various nucleic acid-based devices have been extensively studied as either the principal element in discrete molecule-like sensors or as the main component in the fabrication of sensing devices. The use of aptamers in sensors - aptasensors, in particular, has led to improvements in sensitivity, selectivity, and multiplexing capacity for a wide verity of analytes like proteins, nucleic acids, as well as small biomolecules such as glucose and adenosine triphosphate (ATP). This article reviews the progress in the use of aptamers as the principal component in sensors for optical detection of ATP with an emphasis on sensing mechanism, performance, and applications with some discussion on challenges and perspectives. PMID:27446501

  5. Adenosine triphosphate inhibition of yeast trehalase.

    Science.gov (United States)

    Panek, A D

    1969-09-01

    Yeast trehalase has been found to be inhibited non-competitively by adenosine triphosphate. Such a biological control could explain the accumulation of trehalose during the stationary phase of the growth curve. PMID:5370287

  6. Chemoelectrical energy conversion of adenosine triphosphate

    Science.gov (United States)

    Sundaresan, Vishnu Baba; Sarles, Stephen Andrew; Leo, Donald J.

    2007-04-01

    Plant and animal cell membranes transport charged species, neutral molecules and water through ion pumps and channels. The energy required for moving species against established concentration and charge gradients is provided by the biological fuel - adenosine triphosphate (ATP) -synthesized within the cell. The adenosine triphosphatase (ATPases) in a plant cell membrane hydrolyze ATP in the cell cytoplasm to pump protons across the cell membrane. This establishes a proton gradient across the membrane from the cell exterior into the cell cytoplasm. This proton motive force stimulates ion channels that transport nutrients and other species into the cell. This article discusses a device that converts the chemical energy stored in adenosine triphosphate into electrical power using a transporter protein, ATPase. The V-type ATPase proteins used in our prototype are extracted from red beet(Beta vulgaris) tonoplast membranes and reconstituted in a bilayer lipid membrane or BLM formed from POPC and POPS lipids. A pH7 medium that can support ATP hydrolysis is provided on both sides of the membrane and ATP is dissolved in the pH7 buffer on one side of the membrane. Hydrolysis of ATP results in the formation of a phosphate ion and adenosine diphosphate. The energy from the reaction activates ATPase in the BLM and moves a proton across the membrane. The charge gradient established across the BLM due to the reaction and ion transport is converted into electrical current by half-cell reference electrodes. The prototype ATPase cell with an effective BLM area of 4.15 mm2 carrying 15 μl of ATPase proteins was observed to develop a steady state peak power output of 70 nW, which corresponds to a specific power of 1.69 μW/cm2 and a current density of 43.4 μA/cm2 of membrane area.

  7. Behavior and stability of adenosine triphosphate (ATP) during chlorine disinfection.

    Science.gov (United States)

    Nescerecka, Alina; Juhna, Talis; Hammes, Frederik

    2016-09-15

    Adenosine triphosphate (ATP) analysis is a cultivation-independent alternative method for the determination of bacterial viability in both chlorinated and non-chlorinated water. Here we investigated the behavior and stability of ATP during chlorination in detail. Different sodium hypochlorite doses (0-22.4 mg-Cl2 L(-1); 5 min exposure) were applied to an Escherichia coli pure culture suspended in filtered river water. We observed decreasing intracellular ATP with increasing chlorine concentrations, but extracellular ATP concentrations only increased when the chlorine dose exceeded 0.35 mg L(-1). The release of ATP from chlorine-damaged bacteria coincided with severe membrane damage detected with flow cytometry (FCM). The stability of extracellular ATP was subsequently studied in different water matrixes, and we found that extracellular ATP was stable in sterile deionized water and also in chlorinated water until extremely high chlorine doses (≤11.2 mg-Cl2 L(-1); 5 min exposure). In contrast, ATP decreased relatively slowly (k = 0.145 h(-1)) in 0.1 μm filtered river water, presumably due to degradation by either extracellular enzymes or the fraction of bacteria that were able to pass through the filter. Extracellular ATP decreased considerably faster (k = 0.368 h(-1)) during batch growth of a river water bacterial community. A series of growth potential tests showed that extracellular ATP molecules were utilized as a phosphorus source during bacteria proliferation. From the combined data we conclude that ATP released from bacteria at high chlorine doses could promote bacteria regrowth, contributing to biological instability in drinking water distribution systems. PMID:27295623

  8. Behavior and stability of adenosine triphosphate (ATP) during chlorine disinfection.

    Science.gov (United States)

    Nescerecka, Alina; Juhna, Talis; Hammes, Frederik

    2016-09-15

    Adenosine triphosphate (ATP) analysis is a cultivation-independent alternative method for the determination of bacterial viability in both chlorinated and non-chlorinated water. Here we investigated the behavior and stability of ATP during chlorination in detail. Different sodium hypochlorite doses (0-22.4 mg-Cl2 L(-1); 5 min exposure) were applied to an Escherichia coli pure culture suspended in filtered river water. We observed decreasing intracellular ATP with increasing chlorine concentrations, but extracellular ATP concentrations only increased when the chlorine dose exceeded 0.35 mg L(-1). The release of ATP from chlorine-damaged bacteria coincided with severe membrane damage detected with flow cytometry (FCM). The stability of extracellular ATP was subsequently studied in different water matrixes, and we found that extracellular ATP was stable in sterile deionized water and also in chlorinated water until extremely high chlorine doses (≤11.2 mg-Cl2 L(-1); 5 min exposure). In contrast, ATP decreased relatively slowly (k = 0.145 h(-1)) in 0.1 μm filtered river water, presumably due to degradation by either extracellular enzymes or the fraction of bacteria that were able to pass through the filter. Extracellular ATP decreased considerably faster (k = 0.368 h(-1)) during batch growth of a river water bacterial community. A series of growth potential tests showed that extracellular ATP molecules were utilized as a phosphorus source during bacteria proliferation. From the combined data we conclude that ATP released from bacteria at high chlorine doses could promote bacteria regrowth, contributing to biological instability in drinking water distribution systems.

  9. Identification of an Alternative Nucleoside Triphosphate: 5′-Deoxyadenosylcobinamide Phosphate Nucleotidyltransferase in Methanobacterium thermoautotrophicum ΔH

    OpenAIRE

    Michael G Thomas; Escalante-Semerena, Jorge C.

    2000-01-01

    Computer analysis of the archaeal genome databases failed to identify orthologues of all of the bacterial cobamide biosynthetic enzymes. Of particular interest was the lack of an orthologue of the bifunctional nucleoside triphosphate (NTP):5′-deoxyadenosylcobinamide kinase/GTP:adenosylcobinamide-phosphate guanylyltransferase enzyme (CobU in Salmonella enterica). This paper reports the identification of an archaeal gene encoding a new nucleotidyltransferase, which is proposed to be the nonorth...

  10. An Effector of Hemoglobin Structure: The Guanosine 3', 5'-Triphosphate

    OpenAIRE

    Rezaei-Zarchi, Saeed; Imani, Saber; Soufian, Safieh; Panahi, Yunes; Saboury, Ali Akbar; Arefi, Mohammad Reza

    2012-01-01

    The effect of guanosine 3', 5'-triphosphate (GTP) on the hemoglobin structure was studied by UV-visible, fluorescence and circular dichroism (CD) spectroscopies, and cyclic voltammetry. UV-visible absorption spectra showed an increase in absorbance in the regions of 420 nm and 280 nm. Fluorescence spectra showed that the Trp fluorescence intensity increased upon excitation at 280 nm, when guanosine 3', 5'-triphosphate concentration was increased in hemoglobin solution. Along with the increase...

  11. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Adenosine triphosphate release assay. 864.7040 Section 864.7040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... disorders. (b) Classification. Class I (general controls)....

  12. A rapid method for the determination of microbial susceptibility using the firefly luciferase assay for adenosine triphosphate (ATP)

    Science.gov (United States)

    Vellend, H.; Tuttle, S. A.; Barza, M.; Weinstein, L.; Picciolo, G. L.; Chappelle, E. W.

    1975-01-01

    Luciferase assay for adenosine triphosphate (ATP) was optimized for pure bacteria in broth in order to evaluate if changes in bacterial ATP content could be used as a rapid measure of antibiotic effect on microorganisms. Broth cultures of log phase bacteria were incubated at 310 K (37 C) for 2.5 hours at antimicrobial concentrations which resulted in the best discrimination between sensitive and resistant strains. Eighty-seven strains of 11 bacterial species were studied for their susceptibility to 12 commonly used antimicrobial agents: ampicillin, Penicillin G, nafcillin, carbenicillin, cephalothin, tetracycline, erythromycin, clindamycin, gentamicin, nitrofurantoin, colistin, and chloramplenicol. The major advantage of the ATP system over existing methods of rapid microbial susceptibility testing is that the assay can be made specific for bacterial ATP.

  13. Synthesis and Enzymatic Incorporation of Modified Deoxyuridine Triphosphates

    Directory of Open Access Journals (Sweden)

    Erkai Liu

    2015-07-01

    Full Text Available To expand the chemical functionality of DNAzymes and aptamers, several new modified deoxyuridine triphosphates have been synthesized. An important precursor that enables this aim is 5-aminomethyl dUTP, whereby the pendent amine serves as a handle for further synthetic functionalization. Five functional groups were conjugated to 5-aminomethyl dUTP. Incorporation assays were performed on several templates that demand 2–5 sequential incorporation events using several commercially available DNA polymerases. It was found that Vent (exo- DNA polymerase efficiently incorporates all five modified dUTPs. In addition, all nucleoside triphosphates were capable of supporting a double-stranded exponential PCR amplification. Modified PCR amplicons were PCR amplified into unmodified DNA and sequenced to verify that genetic information was conserved through incorporation, amplification, and reamplification. Overall these modified dUTPs represent new candidate substrates for use in selections using modified nucleotide libraries.

  14. Modified Nucleoside Triphosphates for in-vitro Selection Techniques

    Science.gov (United States)

    Iribarren, Adolfo; Dellafiore, María; Montserrat, Javier

    2016-05-01

    The development of SELEX (Selective Enhancement of Ligands by Exponential Enrichment) provides a powerful tool for the search of functional oligonucleotides with the ability to bind ligands with high affinity and selectivity (aptamers) and for the discovery of nucleic acid sequences with diverse enzymatic activities (ribozymes and DNAzymes). This technique has been extensively applied to the selection of natural DNA or RNA molecules but, in order to improve chemical and structural diversity as well as for particular applications where further chemical or biological stability is necessary, the extension of this strategy to modified oligonucleotides is desirable. Taking into account these needs, this review intends to collect the research carried out during the past years, focusing mainly on the use of modified nucleotides in SELEX and the development of mutant enzymes for broadening nucleoside triphosphates acceptance. In addition, comments regarding the synthesis of modified nucleoside triphosphate will be briefly discussed.

  15. Polyadenylation inhibition by the triphosphates of deoxyadenosine analogues

    OpenAIRE

    Chen, Lisa S.; Plunkett, William; Gandhi, Varsha

    2008-01-01

    The nucleotide substrate specificity of yeast poly(A) polymerase (yPAP) was examined with various ATP analogues of clinical relevance. The triphosphate derivatives of cladribine (2-Cl-dATP), clofarabine (Cl-F-ara-ATP), fludarabine (F-ara-ATP), and related derivatives were incubated with yPAP and 32P-radiolabeled RNA oligonucleotide primers in the absence of ATP to assay polyadenylation. While 2-Cl-ATP resulted in primer elongation, ara-ATP and F-ara-ATP were poor substrates for yPAP. In contr...

  16. Treatment of paroxysmal supraventricular tachycardia with intravenous injection of adenosine triphosphate.

    OpenAIRE

    Saito, D.; Ueeda, M; Abe, Y.; Tani, H; Nakatsu, T.; Yoshida, H.; Haraoka, S; Nagashima, H

    1986-01-01

    Intravenous adenosine triphosphate rapidly terminated all 11 episodes of paroxysmal supraventricular tachycardia in 10 patients. Eight patients reported side effects but these resolved within 20 seconds and did not require treatment. Adenosine triphosphate is a suitable agent for the rapid termination of paroxysmal supraventricular tachycardia.

  17. Autophagy occurs within an hour of adenosine triphosphate treatment after nerve cell damage:the neuroprotective effects of adenosine triphosphate against apoptosis

    Institute of Scientific and Technical Information of China (English)

    Na Lu; Baoying Wang; Xiaohui Deng; Honggang Zhao; Yong Wang; Dongliang Li

    2014-01-01

    After hypoxia, ischemia, or inlfammatory injuries to the central nervous system, the damaged cells release a large amount of adenosine triphosphate, which may cause secondary neuronal death. Autophagy is a form of cell death that also has neuroprotective effects. Cell Counting Kit assay, monodansylcadaverine staining, lfow cytometry, western blotting, and real-time PCR were used to determine the effects of exogenous adenosine triphosphate treatment at different concentrations (2, 4, 6, 8, 10 mmol/L) over time (1, 2, 3, and 6 hours) on the apoptosis and autophagy of SH-SY5Y cells. High concentrations of extracellular adenosine triphosphate induced autophagy and apoptosis of SH-SY5Y cells. The enhanced autophagy ifrst appeared, and peaked at 1 hour after treatment with adenosine triphosphate. Cell apoptosis peaked at 3 hours, and persisted through 6 hours. With prolonged exposure to the adenosine triphosphate treatment, the fraction of apoptotic cells increased. These data suggest that the SH-SY5Y neural cells initiated autophagy against apoptosis within an hour of adenosine triphosphate treatment to protect themselves against injury.

  18. Crystal Structure of a Legionella pneumophila Ecto -Triphosphate Diphosphohydrolase, A Structural and Functional Homolog of the Eukaryotic NTPDases

    Energy Technology Data Exchange (ETDEWEB)

    Vivian, Julian P.; Riedmaier, Patrice; Ge, Honghua; Le Nours, Jérôme; Sansom, Fiona M.; Wilce, Matthew C.J.; Byres, Emma; Dias, Manisha; Schmidberger, Jason W.; Cowan, Peter J.; d' Apice, Anthony J.F.; Hartland, Elizabeth L.; Rossjohn, Jamie; Beddoe, Travis (Monash); (Melbourne)

    2010-04-19

    Many pathogenic bacteria have sophisticated mechanisms to interfere with the mammalian immune response. These include the disruption of host extracellular ATP levels that, in humans, is tightly regulated by the nucleoside triphosphate diphosphohydrolase family (NTPDases). NTPDases are found almost exclusively in eukaryotes, the notable exception being their presence in some pathogenic prokaryotes. To address the function of bacterial NTPDases, we describe the structures of an NTPDase from the pathogen Legionella pneumophila (Lpg1905/Lp1NTPDase) in its apo state and in complex with the ATP analog AMPPNP and the subtype-specific NTPDase inhibitor ARL 67156. Lp1NTPDase is structurally and catalytically related to eukaryotic NTPDases and the structure provides a basis for NTPDase-specific inhibition. Furthermore, we demonstrate that the activity of Lp1NTPDase correlates directly with intracellular replication of Legionella within macrophages. Collectively, these findings provide insight into the mechanism of this enzyme and highlight its role in host-pathogen interactions.

  19. Carpal Tunnel Syndrome

    Science.gov (United States)

    ... arm. Just a passing cramp? It could be carpal tunnel syndrome. The carpal tunnel is a narrow passageway of ligament and ... difficult. Often, the cause is having a smaller carpal tunnel than other people do. Other causes include ...

  20. Cyclization of the phosphate side chain of adenosine triphosphate: formation of monoadenosine 5'-trimetaphosphate.

    Science.gov (United States)

    Glonek, T; Kleps, R A; Myers, T C

    1974-07-26

    Monoadenosine 5'-trimetaphosphate has been prepared from adeno-sine 5'-triphosphate by a carbodiimide-mediated condensation. The molecule was characterized by (3l)P nuclear magnetic resonance, and its (31)P spectrum was simulated through the assumption of a three-phosphorus spin system. The molecule is highly reactive and is rapidly converted to adenosine triphosphate upon contact with water. PMID:4834364

  1. Association of Thymidylate Synthase Gene Polymorphisms with Stavudine Triphosphate Intracellular Levels and Lipodystrophy▿

    OpenAIRE

    Domingo, Pere (Domingo Pedrol); Cabeza, M. Carmen; Pruvost, Alain; Torres, Ferran; Salazar, Juliana; del Mar Gutierrez, M.; Mateo, M. Gracia; Fontanet, Angels; Fernandez, Irene; Domingo, Joan C.; Villarroya, Francesc; Vidal, Francesc; Baiget, Montserrat

    2011-01-01

    The antiviral activity and toxicity of stavudine (d4T) depend on its triphosphate metabolite, stavudine triphosphate (d4T-TP). Therefore, modifications in intracellular levels of d4T-TP may change the toxicity profile of stavudine. d4T-TP intracellular levels in peripheral blood mononuclear cells were determined with a prominence liquid chromatograph connected to a triple-quadruple mass spectrometer. Polymorphisms in the thymidylate synthase (TS), methylenetetrahydrofolate reductase (MTHFR), ...

  2. Identification of an alternative nucleoside triphosphate: 5'-deoxyadenosylcobinamide phosphate nucleotidyltransferase in Methanobacterium thermoautotrophicum delta H.

    Science.gov (United States)

    Thomas, M G; Escalante-Semerena, J C

    2000-08-01

    Computer analysis of the archaeal genome databases failed to identify orthologues of all of the bacterial cobamide biosynthetic enzymes. Of particular interest was the lack of an orthologue of the bifunctional nucleoside triphosphate (NTP):5'-deoxyadenosylcobinamide kinase/GTP:adenosylcobinamide-phosphate guanylyltransferase enzyme (CobU in Salmonella enterica). This paper reports the identification of an archaeal gene encoding a new nucleotidyltransferase, which is proposed to be the nonorthologous replacement of the S. enterica cobU gene. The gene encoding this nucleotidyltransferase was identified using comparative genome analysis of the sequenced archaeal genomes. Orthologues of the gene encoding this activity are limited at present to members of the domain Archaea. The corresponding ORF open reading frame from Methanobacterium thermoautotrophicum Delta H (MTH1152; referred to as cobY) was amplified and cloned, and the CobY protein was expressed and purified from Escherichia coli as a hexahistidine-tagged fusion protein. This enzyme had GTP:adenosylcobinamide-phosphate guanylyltransferase activity but did not have the NTP:AdoCbi kinase activity associated with the CobU enzyme of S. enterica. NTP:adenosylcobinamide kinase activity was not detected in M. thermoautotrophicum Delta H cell extract, suggesting that this organism may not have this activity. The cobY gene complemented a cobU mutant of S. enterica grown under anaerobic conditions where growth of the cell depended on de novo adenosylcobalamin biosynthesis. cobY, however, failed to restore adenosylcobalamin biosynthesis in cobU mutants grown under aerobic conditions where de novo synthesis of this coenzyme was blocked, and growth of the cell depended on the assimilation of exogenous cobinamide. These data strongly support the proposal that the relevant cobinamide intermediates during de novo adenosylcobalamin biosynthesis are adenosylcobinamide-phosphate and adenosylcobinamide-GDP, not adenosylcobinamide

  3. Adenosine triphosphate inhibits melatonin synthesis in the rat pineal gland.

    Science.gov (United States)

    Souza-Teodoro, Luis Henrique; Dargenio-Garcia, Letícia; Petrilli-Lapa, Camila Lopes; Souza, Ewerton da Silva; Fernandes, Pedro A C M; Markus, Regina P; Ferreira, Zulma S

    2016-03-01

    Adenosine triphosphate (ATP) is released onto the pinealocyte, along with noradrenaline, from sympathetic neurons and triggers P2Y1 receptors that enhance β-adrenergic-induced N-acetylserotonin (NAS) synthesis. Nevertheless, the biotransformation of NAS into melatonin, which occurs due to the subsequent methylation by acetylserotonin O-methyltransferase (ASMT; EC 2.1.1.4), has not yet been evaluated in the presence of purinergic stimulation. We therefore evaluated the effects of purinergic signaling on melatonin synthesis induced by β-adrenergic stimulation. ATP increased NAS levels, but, surprisingly, inhibited melatonin synthesis in an inverse, concentration-dependent manner. Our results demonstrate that enhanced NAS levels, which depend on phospholipase C (PLC) activity (but not the induction of gene transcription), are a post-translational effect. By contrast, melatonin reduction is related to an ASMT inhibition of expression at both the gene transcription and protein levels. These results were independent of nuclear factor-kappa B (NF-kB) translocation. Neither the P2Y1 receptor activation nor the PLC-mediated pathway was involved in the decrease in melatonin, indicating that ATP regulates pineal metabolism through different mechanisms. Taken together, our data demonstrate that purinergic signaling differentially modulates NAS and melatonin synthesis and point to a regulatory role for ATP as a cotransmitter in the control of ASMT, the rate-limiting enzyme in melatonin synthesis. The endogenous production of melatonin regulates defense responses; therefore, understanding the mechanisms involving ASMT regulation might provide novel insights into the development and progression of neurological disorders since melatonin presents anti-inflammatory, neuroprotective, and neurogenic effects. PMID:26732366

  4. Electron tunnel sensor technology

    Science.gov (United States)

    Waltman, S. B.; Kaiser, W. J.

    1989-01-01

    The recent development of Scanning Tunneling Microscopy technology allows the application of electron tunneling to position detectors for the first time. The vacuum tunnel junction is one of the most sensitive position detection mechanisms available. It is also compact, simple, and requires little power. A prototype accelerometer based on electron tunneling, and other sensor applications of this promising new technology are described.

  5. Effect of calcium triphosphate cement on proximal humeral fracture osteosynthesis: a finite element analysis.

    Science.gov (United States)

    Kennedy, Jim; Feerick, Emer; McGarry, Patrick; FitzPatrick, David; Mullett, Hannan

    2013-08-01

    PURPOSE. To measure the effect of void-filling calcium triphosphate cement on the loads at the implant-bone interface of a proximal humeral fracture osteosynthesis using a finite element analysis. METHODS. Finite element models of a 3-part proximal humeral fracture fixed with a plate with and without calcium triphosphate cement augmentation were generated from a quantitative computed tomography dataset of an intact proximal humerus. Material properties were assigned to bone fragments using published expressions relating Young's modulus to local Hounsfield number. Boundary conditions were then applied to the model to replicate the physiological loads. The effect of void-filling calcium triphosphate cement was analysed. RESULTS. When the void was filled with calcium triphosphate cement, the pressure gradient of the bone surrounding the screws in the medial fracture fragment decreased 97% from up to 21.41 to 0.66 MPa. Peak pressure of the fracture planes decreased 95% from 6.10 to 0.30 MPa and occurred along the medial aspect. The mean stress in the screw locking mechanisms decreased 78% from 71.23 to 15.92 MPa. The angled proximal metaphyseal screw had the highest stress. CONCLUSION. Augmentation with calcium triphosphate cement improves initial stability and reduces stress on the implant-bone interface. PMID:24014777

  6. Adenosine Triphosphate Stimulates Aquifex aeolicus MutL Endonuclease Activity

    OpenAIRE

    Jerome Mauris; Thomas C Evans

    2009-01-01

    BACKGROUND: Human PMS2 (hPMS2) homologues act to nick 5' and 3' to misincorporated nucleotides during mismatch repair in organisms that lack MutH. Mn(++) was previously found to stimulate the endonuclease activity of these homologues. ATP was required for the nicking activity of hPMS2 and yPMS1, but was reported to inhibit bacterial MutL proteins from Thermus thermophilus and Aquifex aeolicus that displayed homology to hPMS2. Mutational analysis has identified the DQHA(X)(2)E(X)(4)E motif pre...

  7. Carpal Tunnel Surgery

    Medline Plus

    Full Text Available ... that is putting pressure on the median nerve. This is the procedure of carpal tunnel syndrome release, ... for the condition of carpal tunnel syndrome. At this point in time, we have the patient under ...

  8. Transonic Dynamics Tunnel (TDT)

    Data.gov (United States)

    Federal Laboratory Consortium — The Transonic Dynamics Tunnel (TDT) is a continuous flow wind-tunnel facility capable of speeds up to Mach 1.2 at stagnation pressures up to one atmosphere. The TDT...

  9. Quantum theory of tunneling

    CERN Document Server

    Razavy, Mohsen

    2014-01-01

    In this revised and expanded edition, in addition to a comprehensible introduction to the theoretical foundations of quantum tunneling based on different methods of formulating and solving tunneling problems, different semiclassical approximations for multidimensional systems are presented. Particular attention is given to the tunneling of composite systems, with examples taken from molecular tunneling and also from nuclear reactions. The interesting and puzzling features of tunneling times are given extensive coverage, and the possibility of measurement of these times with quantum clocks are critically examined. In addition by considering the analogy between evanescent waves in waveguides and in quantum tunneling, the times related to electromagnetic wave propagation have been used to explain certain aspects of quantum tunneling times. These topics are treated in both non-relativistic as well as relativistic regimes. Finally, a large number of examples of tunneling in atomic, molecular, condensed matter and ...

  10. Hypersonic Tunnel Facility (HTF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Hypersonic Tunnel Facility (HTF) is a blow-down, non-vitiated (clean air) free-jet wind tunnel capable of testing large-scale, propulsion systems at Mach 5, 6,...

  11. Magnetic tunnel junctions (MTJs)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We review the giant tunnel magnetoresistance (TMR) in ferromagnetic-insulator-ferromagnetic junctions discovered in recent years, which is the magnetoresistance (MR) associated with the spin-dependent tunneling between two ferromagnetic metal films separated by an insulating thin tunnel barrier. The theoretical and experimental results including junction conductance, magnetoresistance and their temperature and bias dependences are described.

  12. Radiologically placed tunneled peritoneal catheter in palliation of malignant ascites

    Energy Technology Data Exchange (ETDEWEB)

    Akinci, Devrim; Erol, Bekir; Ciftci, Tuerkmen T. [Hacettepe University, Faculty of Medicine, Department of Radiology, 06100 Ankara (Turkey); Akhan, Okan, E-mail: akhano@tr.net [Hacettepe University, Faculty of Medicine, Department of Radiology, 06100 Ankara (Turkey)

    2011-11-15

    The purpose of this study was to evaluate retrospectively the safety and effectiveness of radiologically placed tunneled peritoneal catheter in palliation of malignant ascites. Between July 2005 and June 2009, 41 tunneled peritoneal catheters were placed under ultrasonographic and fluoroscopic guidance in 40 patients (mean age, 55 years; 22 women) who had symptomatic malignant ascites. No procedure related mortality was observed. Major complication occurred in one patient (2.5%) in the form of serious bacterial peritonitis that necessitated catheter removal. Minor complications such as minor bacterial peritonitis, catheter dislodgement, tunnel infection, and catheter blockage occurred in 11 patients (27.5%). The mean duration of survival after catheter placement was 11.8 weeks. All patients expired of their primary malignancies in the follow-up. Radiologically placed tunneled peritoneal catheter is safe and effective in palliation of symptomatic malignant ascites.

  13. Proton tunneling in solids

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, J.

    1998-10-01

    The tunneling rate of the proton and its isotopes between interstitial sites in solids is studied theoretically. The phonons and/or the electrons in the solid have two effects on the tunneling phenomenon. First, they suppress the transfer integral between two neighbouring states. Second, they give rise to a finite lifetime of the proton state. Usually the second effect is large and the tunneling probability per unit time (tunneling rate) can be defined. In some cases, however, a coherent tunneling is expected and actually observed. (author)

  14. Unexpected Discovery of Dichloroacetate Derived Adenosine Triphosphate Competitors Targeting Pyruvate Dehydrogenase Kinase To Inhibit Cancer Proliferation.

    Science.gov (United States)

    Zhang, Shao-Lin; Hu, Xiaohui; Zhang, Wen; Tam, Kin Yip

    2016-04-14

    Pyruvate dehydrogenase kinases (PDKs) have recently emerged as an attractive target for cancer therapy. Herein, we prepared a series of compounds derived from dichloroacetate (DCA) which inhibited cancer cells proliferation. For the first time, we have successfully developed DCA derived inhibitors that preferentially bind to the adenosine triphosphate (ATP) pocket of PDK isoform 1 (PDK1).

  15. Increased deoxythymidine triphosphate levels is a feature of relative cognitive decline

    DEFF Research Database (Denmark)

    Madsen, Claus Desler; Frederiksen, Jane H; Olsen, Maria Nathalie Angleys;

    2015-01-01

    PBMC content of deoxythymidine-triphosphate (dTTP) (20%), but not mitochondrial bioenergetics parameters measured in this study or mitochondrial ROS. Levels of dTTP in PBMCs are indicators of relative cognitive change suggesting a role of deoxyribonucleotides in the etiology of AD....

  16. Guanosine triphosphate cyclohydrolase 1 promoter deletion causes dopa-responsive dystonia

    NARCIS (Netherlands)

    Theuns, Jessie; Crosiers, David; Debaene, Luc; Nuytemans, Karen; Meeus, Bram; Sleegers, Kristel; Goossens, Dirk; Corsmit, Ellen; Elinck, Ellen; Peeters, Karin; Mattheijssens, Maria; Pickut, Barbara; Del-Favero, Jurgen; Engelborghs, Sebastiaan; De Deyn, Peter Paul; Cras, Patrick; Van Broeckhoven, Christine

    2012-01-01

    Background: Autosomal dominant dopa-responsive dystonia (AD-DRD) is caused by a biochemical defect primarily resulting from guanosine triphosphate cyclohydrolase 1 gene (GCH1) mutations. Few families have been reported without mutations in GCH1. Methods: Genome-wide linkage analysis and positional c

  17. Leishmania infantum ecto-nucleoside triphosphate diphosphohydrolase-2 is an apyrase involved in macrophage infection and expressed in infected dogs.

    Directory of Open Access Journals (Sweden)

    Raphael De Souza Vasconcellos

    2014-11-01

    Full Text Available Visceral leishmaniasis is an important tropical disease, and Leishmania infantum chagasi (synonym of Leishmania infantum is the main pathogenic agent of visceral leishmaniasis in the New World. Recently, ecto-nucleoside triphosphate diphosphohydrolases (E-NTPDases were identified as enablers of infection and virulence factors in many pathogens. Two putative E-NTPDases (∼70 kDa and ∼45 kDa have been found in the L. infantum genome. Here, we studied the ∼45 kDa E-NTPDase from L. infantum chagasi to describe its natural occurrence, biochemical characteristics and influence on macrophage infection.We used live L. infantum chagasi to demonstrate its natural ecto-nucleotidase activity. We then isolated, cloned and expressed recombinant rLicNTPDase-2 in bacterial system. The recombinant rLicNTPDase-2 hydrolyzed a wide variety of triphosphate and diphosphate nucleotides (GTP> GDP  =  UDP> ADP> UTP  =  ATP in the presence of calcium or magnesium. In addition, rLicNTPDase-2 showed stable activity over a pH range of 6.0 to 9.0 and was partially inhibited by ARL67156 and suramin. Microscopic analyses revealed the presence of this protein on cell surfaces, vesicles, flagellae, flagellar pockets, kinetoplasts, mitochondria and nuclei. The blockade of E-NTPDases using antibodies and competition led to lower levels of parasite adhesion and infection of macrophages. Furthermore, immunohistochemistry showed the expression of E-NTPDases in amastigotes in the lymph nodes of naturally infected dogs from an area of endemic visceral leishmaniasis.In this work, we cloned, expressed and characterized the NTPDase-2 from L. infantum chagasi and demonstrated that it functions as a genuine enzyme from the E-NTPDase/CD39 family. We showed that E-NTPDases are present on the surface of promastigotes and in other intracellular locations. We showed, for the first time, the broad expression of LicNTPDases in naturally infected dogs. Additionally, the blockade of

  18. Complex tunneling dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Yang, C.-D. [Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan (China)]. E-mail: cdyang@mail.ncku.edu.tw

    2007-04-15

    Tunneling dynamics and tunneling trajectories are modeled exactly by complex-extended Hamilton-Jacobi formulation in this paper. It is found that the wave-like properties of tunneling particles, such as reflection, refraction, and transmission resonance, can be identified and explained in terms of particle's motion in complex space with the tunneling time defined as the usual sense of classical time. Following the complex trajectories determined by the complex Hamilton equations of motion, we can connect classical trajectories smoothly with tunneling trajectories using position and velocity continuity at the interface of the media, locate the particle's position at any instant, and find the time spent by a particle within the potential. A microscopic tunneling model is also developed to explain the probabilistic nature why a particle with the same incident conditions sometimes transmits the potential and sometimes is reflected from the potential.

  19. Adenosine triphosphate stimulates Aquifex aeolicus MutL endonuclease activity.

    Directory of Open Access Journals (Sweden)

    Jerome Mauris

    Full Text Available BACKGROUND: Human PMS2 (hPMS2 homologues act to nick 5' and 3' to misincorporated nucleotides during mismatch repair in organisms that lack MutH. Mn(++ was previously found to stimulate the endonuclease activity of these homologues. ATP was required for the nicking activity of hPMS2 and yPMS1, but was reported to inhibit bacterial MutL proteins from Thermus thermophilus and Aquifex aeolicus that displayed homology to hPMS2. Mutational analysis has identified the DQHA(X(2E(X(4E motif present in the C-terminus of PMS2 homologues as important for endonuclease activity. METHODOLOGIES/PRINCIPAL FINDINGS: We examined the effect ATP had on the Mn(++ induced nicking of supercoiled pBR322 by full-length and mutant A. aeolicus MutL (Aae MutL proteins. Assays were single time point, enzyme titration experiments or reaction time courses. The maximum velocity for MutL nicking was determined to be 1.6+/-0.08x10(-5 s(-1 and 4.2+/-0.3x10(-5 s(-1 in the absence and presence of ATP, respectively. AMPPNP stimulated the nicking activity to a similar extent as ATP. A truncated Aae MutL protein composed of only the C-terminal 123 amino acid residues was found to nick supercoiled DNA. Furthermore, mutations in the conserved C-terminal DQHA(X(2E(X(4E and CPHGRP motifs were shown to abolish Aae MutL endonuclease activity. CONCLUSIONS: ATP stimulated the Mn(++ induced endonuclease activity of Aae MutL. Experiments utilizing AMPPNP implied that the stimulation did not require ATP hydrolysis. A mutation in the DQHA(X(2E(X(4E motif of Aae MutL further supported the role of this region in endonclease activity. For the first time, to our knowledge, we demonstrate that changing the histidine residue in the conserved CPHGRP motif abolishes endonucleolytic activity of a hPMS2 homologue. Finally, the C-terminal 123 amino acid residues of Aae MutL were sufficient to display Mn(++ induced nicking activity.

  20. Resonance Enhanced Tunneling

    CERN Document Server

    Matsumoto, S; Matsumoto, Sh.

    2000-01-01

    Time evolution of tunneling in thermal medium is examined using the real-time semiclassical formalism previously developed. Effect of anharmonic terms in the potential well is shown to give a new mechanism of resonance enhanced tunneling. If the friction from environment is small enough, this mechanism may give a very large enhancement for the tunneling rate. The case of the asymmetric wine bottle potential is worked out in detail.

  1. Microsystem Aeromechanics Wind Tunnel

    Data.gov (United States)

    Federal Laboratory Consortium — The Microsystem Aeromechanics Wind Tunnel advances the study of fundamental flow physics relevant to micro air vehicle (MAV) flight and assesses vehicle performance...

  2. Comparison of plate counts, Petrifilm, dipslides, and adenosine triphosphate bioluminescence for monitoring bacteria in cooling-tower waters.

    Science.gov (United States)

    Mueller, Sherry A; Anderson, James E; Kim, Byung R; Ball, James C

    2009-04-01

    Effective bacterial control in cooling-tower systems requires accurate and timely methods to count bacteria. Plate-count methods are difficult to implement on-site, because they are time- and labor-intensive and require sterile techniques. Several field-applicable methods (dipslides, Petrifilm, and adenosine triphosphate [ATP] bioluminescence) were compared with the plate count for two sample matrices--phosphate-buffered saline solution containing a pure culture of Pseudomonas fluorescens and cooling-tower water containing an undefined mixed bacterial culture. For the pure culture, (1) counts determined on nutrient agar and plate-count agar (PCA) media and expressed as colony-forming units (CFU) per milliliter were equivalent to those on R2A medium (p = 1.0 and p = 1.0, respectively); (2) Petrifilm counts were not significantly different from R2A plate counts (p = 0.99); (3) the dipslide counts were up to 2 log units higher than R2A plate counts, but this discrepancy was not statistically significant (p = 0.06); and (4) a discernable correlation (r2 = 0.67) existed between ATP readings and plate counts. For cooling-tower water samples (n = 62), (1) bacterial counts using R2A medium were higher (but not significant; p = 0.63) than nutrient agar and significantly higher than tryptone-glucose yeast extract (TGE; p = 0.03) and PCA (p < 0.001); (2) Petrifilm counts were significantly lower than nutrient agar or R2A (p = 0.02 and p < 0.001, respectively), but not statistically different from TGE, PCA, and dipslides (p = 0.55, p = 0.69, and p = 0.91, respectively); (3) the dipslide method yielded bacteria counts 1 to 3 log units lower than nutrient agar and R2A (p < 0.001), but was not significantly different from Petrifilm (p = 0.91), PCA (p = 1.00) or TGE (p = 0.07); (4) the differences between dipslides and the other methods became greater with a 6-day incubation time; and (5) the correlation between ATP readings and plate counts varied from system to system, was poor

  3. Purification, crystallization and preliminary crystallographic analysis of deoxyuridine triphosphate nucleotidohydrolase from Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Bajaj, Mamta [School of Biological Sciences, University of Nebraska-Lincoln, Manter Hall, Lincoln, Nebraska 68588-0304 (United States); Moriyama, Hideaki, E-mail: hmoriyama2@unl.edu [Department of Chemistry, e-Toxicology and Biotechnology, University of Nebraska-Lincoln, Hamilton Hall, Lincoln, Nebraska 68588-0304 (United States); School of Biological Sciences, University of Nebraska-Lincoln, Manter Hall, Lincoln, Nebraska 68588-0304 (United States)

    2007-05-01

    The first crystallization of deoxyuridine triphosphate nucleotidohydrolase from plant, Arabidopsis thaliana, has been performed. An additive, taurine, was effective in producing the single crystal. The deoxyuridine triphosphate nucleotidohydrolase gene from Arabidopsis thaliana was expressed and the gene product was purified. Crystallization was performed by the hanging-drop vapour-diffusion method at 298 K using 2 M ammonium sulfate as the precipitant. X-ray diffraction data were collected to 2.2 Å resolution using Cu Kα radiation. The crystal belongs to the orthorhombic space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 69.90, b = 70.86 Å, c = 75.55 Å. Assuming the presence of a trimer in the asymmetric unit, the solvent content was 30%, with a V{sub M} of 1.8 Å{sup 3} Da{sup −1}.

  4. Tunnel modeling with BIM tools

    OpenAIRE

    Saje, Samo

    2014-01-01

    Graduation thesis deals with the process of tunnel modeling with the use of BIM tools and shows the development of libraries and families for tunnels for Revit software environment. In the first part of the thesis the process of design and construction of tunnels is presented, various tunnel construction methods and typical structure of road tunnels are described with an emphasis on the new Austrian method (NATM). The tunnel design process is broken down into individual phases, while the ...

  5. Description of a novel eukaryotic deoxyuridine 5'-triphosphate nucleotidohydrolase in Leishmania major

    DEFF Research Database (Denmark)

    Camacho, A; Arrebola, R; Pena Diaz, Javier;

    1997-01-01

    . None of the characteristic motifs were readily identifiable and the sequence encoded a larger polypeptide. However, the products of the reaction were dUMP and PPi, competition experiments with other deoxyribonucleoside triphosphates showed that the reaction is specific for dUTP, and the protozoan gene...... of recombinant enzyme in large quantities will now permit detailed mechanistic and structural studies, which might contribute to a rational design of specifically targeted inhibitors against dUTPase from L. major....

  6. Possible regulation of the Salmonella typhimurium histidine operon by adenosine triphosphate phosphoribosyltransferase: large metabolic effects.

    OpenAIRE

    Goitein, R K; Parsons, S. M.

    1980-01-01

    An effort to find growth conditions leading to conditional regulation of the histidine operon of Salmonella typhimurium by the allosteric first enzyme of the pathway, adenosine triphosphate phosphoribosyltransferase (EC 2.4.2.17), is reported. A strain deleting the enzyme, TR3343, behaved simply and predictably under all growth conditions, whereas histidine auxotrophs containing active enzyme behaved in complicated ways dependent upon the location of the histidine pathway lesion. hisE strains...

  7. Randomized clinical trial of adenosine 5'-triphosphate in patients with advanced non-small-cell lung cancer

    NARCIS (Netherlands)

    H.J. Agteresch; P.C. Dagnelie (Pieter); A. van der Gaast (Ate); Th. Stijnen (Theo); J.H.P. Wilson (Paul)

    2000-01-01

    textabstractBACKGROUND: Extracellular adenosine 5'-triphosphate (ATP) is involved in the regulation of a variety of biologic processes, including neurotransmission, muscle contraction, and liver glucose metabolism, via purinergic receptors. In nonrandomized studies invo

  8. Regulation of adenosine triphosphate-sensitive potassium channels suppresses the toxic effects of amyloid-beta peptide (25-35)

    Institute of Scientific and Technical Information of China (English)

    Min Kong; Maowen Ba; Hui Liang; Peng Shao; Tianxia Yu; Ying Wang

    2013-01-01

    In this study, we treated PC12 cells with 0-20 μM amyloid-β peptide (25-35) for 24 hours to induce cytotoxicity, and found that 5-20 μM amyloid-β peptide (25-35) decreased PC12 cell viability, but adenosine triphosphate-sensitive potassium channel activator diazoxide suppressed the decrease reactive oxygen species levels. These protective effects were reversed by the selective mitochondrial adenosine triphosphate-sensitive potassium channel blocker 5-hydroxydecanoate. An inducible nitric oxide synthase inhibitor, Nω-nitro-L-arginine, also protected PC12 cells from intracellular reactive oxygen species levels. However, the H2O2-degrading enzyme catalase could that the increases in both mitochondrial membrane potential and reactive oxygen species levels adenosine triphosphate-sensitive potassium channels and nitric oxide. Regulation of adenosine triphosphate-sensitive potassium channels suppresses PC12 cell cytotoxicity induced by amyloid-β

  9. Carpal Tunnel Surgery

    Medline Plus

    Full Text Available ... carpal tunnel syndrome. At this point in time, we have the patient under anesthesia. We have the hand prepped. Great. And then, the ... the carpal tunnel, and it’s the ligament that we incise to release the carpal canal. The carpal ...

  10. Tunnel fire dynamics

    CERN Document Server

    Ingason, Haukur; Lönnermark, Anders

    2015-01-01

    This book covers a wide range of issues in fire safety engineering in tunnels, describes the phenomena related to tunnel fire dynamics, presents state-of-the-art research, and gives detailed solutions to these major issues. Examples for calculations are provided. The aim is to significantly improve the understanding of fire safety engineering in tunnels. Chapters on fuel and ventilation control, combustion products, gas temperatures, heat fluxes, smoke stratification, visibility, tenability, design fire curves, heat release, fire suppression and detection, CFD modeling, and scaling techniques all equip readers to create their own fire safety plans for tunnels. This book should be purchased by any engineer or public official with responsibility for tunnels. It would also be of interest to many fire protection engineers as an application of evolving technical principles of fire safety.

  11. Structural and functional insights into DR2231 protein, the MazG-like nucleoside triphosphate pyrophosphohydrolase from Deinococcus radiodurans.

    Science.gov (United States)

    Gonçalves, Ana Maria D; de Sanctis, Daniele; McSweeney, Sean M

    2011-09-01

    Deinococcus radiodurans is among the very few bacterial species extremely resistant to ionizing radiation, UV light, oxidizing agents, and cycles of prolonged desiccation. The proteome of D. radiodurans reflects the evolutionary pressure exerted by chronic exposure to (nonradioactive) forms of DNA and protein damage. A clear example of this adaptation is the overrepresentation of protein families involved in the removal of non-canonical nucleoside triphosphates (NTPs) whose incorporation into nascent DNA would promote mutagenesis and DNA damage. The three-dimensional structure of the DR2231 protein has been solved at 1.80 Å resolution. This protein had been classified as an all-α-helical MazG-like protein. The present study confirms that it holds the basic structural module characteristic of the MazG superfamily; two helices form a rigid domain, and two helices form a mobile domain and connecting loops. Contrary to what is known of MazG proteins, DR2231 protein shows a functional affinity with dUTPases. Enzymatic and isothermal calorimetry assays have demonstrated high specificity toward dUTP but an inability to hydrolyze dTTP, a typical feature of dUTPases. Co-crystallization with the product of hydrolysis, dUMP, in the presence of magnesium or manganese cations, suggests similarities with the dUTP/dUDP hydrolysis mechanism reported for dimeric dUTPases. The genome of D. radiodurans encodes for all enzymes required for dTTP synthesis from dCMP, thus bypassing the need of a dUTPase. We postulate that DR2231 protein is not essential to D. radiodurans and rather performs "house-cleaning" functions within the framework of oxidative stress response. We further propose DR2231 protein as an evolutionary precursor of dimeric dUTPases.

  12. Using an Adenosine Triphosphate Bioluminescent Assay to Determine Effective Antibiotic Combinations against Carbapenem-Resistant Gram Negative Bacteria within 24 Hours.

    Directory of Open Access Journals (Sweden)

    Yiying Cai

    Full Text Available Current in vitro combination testing methods involve enumeration by bacterial plating, which is labor-intensive and time-consuming. Measurement of bioluminescence, released when bacterial adenosine triphosphate binds to firefly luciferin-luciferase, has been proposed as a surrogate for bacterial counts. We developed an ATP bioluminescent combination testing assay with a rapid turnaround time of 24h to determine effective antibiotic combinations.100 strains of carbapenem-resistant (CR GNB [30 Acinetobacter baumannii (AB, 30 Pseudomonas aeruginosa (PA and 40 Klebsiella pneumoniae (KP] were used. Bacterial suspensions (105 CFU/ml were added to 96-well plates containing clinically achievable concentrations of multiple single and two-antibiotic combinations. At 24h, the luminescence intensity of each well was measured. Receiver operator characteristic curves were plotted to determine optimal luminescence threshold (TRLU to discriminate between inhibitory/non-inhibitory combinations when compared to viable plating. The unweighted accuracy (UA [(sensitivity + specificity/2] of TRLU values was determined. External validation was further done using 50 additional CR-GNB.Predictive accuracies of TRLU were high for when all antibiotic combinations and species were collectively analyzed (TRLU = 0.81, UA = 89%. When individual thresholds for each species were determined, UA remained high. Predictive accuracy was highest for KP (TRLU = 0.81, UA = 91%, and lowest for AB (TRLU = 0.83, UA = 87%. Upon external validation, high overall accuracy (91% was observed. The assay distinguished inhibitory/non-inhibitory combinations with UA of 80%, 94% and 93% for AB, PA and KP respectively.We developed an assay that is robust at identifying useful combinations with a rapid turn-around time of 24h, and may be employed to guide the timely selection of effective antibiotic combinations.

  13. Ultrafast scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Botkin, D.A. [California Univ., Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley Lab., CA (United States)

    1995-09-01

    I have developed an ultrafast scanning tunneling microscope (USTM) based on uniting stroboscopic methods of ultrafast optics and scanned probe microscopy to obtain nanometer spatial resolution and sub-picosecond temporal resolution. USTM increases the achievable time resolution of a STM by more than 6 orders of magnitude; this should enable exploration of mesoscopic and nanometer size systems on time scales corresponding to the period or decay of fundamental excitations. USTM consists of a photoconductive switch with subpicosecond response time in series with the tip of a STM. An optical pulse from a modelocked laser activates the switch to create a gate for the tunneling current, while a second laser pulse on the sample initiates a dynamic process which affects the tunneling current. By sending a large sequence of identical pulse pairs and measuring the average tunnel current as a function of the relative time delay between the pulses in each pair, one can map the time evolution of the surface process. USTM was used to measure the broadband response of the STM`s atomic size tunnel barrier in frequencies from tens to hundreds of GHz. The USTM signal amplitude decays linearly with the tunnel junction conductance, so the spatial resolution of the time-resolved signal is comparable to that of a conventional STM. Geometrical capacitance of the junction does not appear to play an important role in the measurement, but a capacitive effect intimately related to tunneling contributes to the measured signals and may limit the ultimate resolution of the USTM.

  14. The aeolian wind tunnel

    Science.gov (United States)

    Iversen, J. D.

    1991-01-01

    The aeolian wind tunnel is a special case of a larger subset of the wind tunnel family which is designed to simulate the atmospheric surface layer winds to small scale (a member of this larger subset is usually called an atmospheric boundary layer wind tunnel or environmental wind tunnel). The atmospheric boundary layer wind tunnel is designed to simulate, as closely as possible, the mean velocity and turbulence that occur naturally in the atmospheric boundary layer (defined as the lowest portion of the atmosphere, of the order of 500 m, in which the winds are most greatly affected by surface roughness and topography). The aeolian wind tunnel is used for two purposes: to simulate the physics of the saltation process and to model at small scale the erosional and depositional processes associated with topographic surface features. For purposes of studying aeolian effects on the surface of Mars and Venus as well as on Earth, the aeolian wind tunnel continues to prove to be a useful tool for estimating wind speeds necessary to move small particles on the three planets as well as to determine the effects of topography on the evolution of aeolian features such as wind streaks and dune patterns.

  15. Spin Tunneling in Conducting Oxides

    OpenAIRE

    Bratkovsky, Alexander

    1997-01-01

    Direct tunneling in ferromagnetic junctions is compared with impurity-assisted, surface state assisted, and inelastic contributions to a tunneling magnetoresistance (TMR). Theoretically calculated direct tunneling in iron group systems leads to about a 30% change in resistance, which is close to experimentally observed values. It is shown that the larger observed values of the TMR might be a result of tunneling involving surface polarized states. We find that tunneling via resonant defect sta...

  16. Carpal Tunnel Surgery

    Medline Plus

    Full Text Available ... of carpal tunnel syndrome. At this point in time, we have the patient under anesthesia. We have ... and is not visible over a period of time. You can barely see a surgical scar. My ...

  17. Carpal Tunnel Surgery

    Medline Plus

    Full Text Available ... tunnel pass the tendons and the nerves. So, right beneath this ligament is going to be the ... and it’s actually beneath this bridge of skin right in here. So, I’ve incised this ligament ...

  18. Water Tunnel Facility

    Data.gov (United States)

    Federal Laboratory Consortium — NETL’s High-Pressure Water Tunnel Facility in Pittsburgh, PA, re-creates the conditions found 3,000 meters beneath the ocean’s surface, allowing scientists to study...

  19. Wind Tunnel Testing Facilities

    Data.gov (United States)

    Federal Laboratory Consortium — NASA Ames Research Center is pleased to offer the services of our premier wind tunnel facilities that have a broad range of proven testing capabilities to customers...

  20. INCAS TRISONIC WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Florin MUNTEANU

    2009-09-01

    Full Text Available The 1.2 m x 1.2 m Trisonic Blowdown Wind Tunnel is the largest of the experimental facilities at the National Institute for Aerospace Research - I.N.C.A.S. "Elie Carafoli", Bucharest, Romania. The tunnel has been designed by the Canadian company DSMA (now AIOLOS and since its commissioning in 1978 has performed high speed aerodynamic tests for more than 120 projects of aircraft, missiles and other objects among which the twin jet fighter IAR-93, the jet trainer IAR-99, the MIG-21 Lancer, the Polish jet fighter YRYDA and others. In the last years the wind tunnel has been used mostly for experimental research in European projects such as UFAST. The high flow quality parameters and the wide range of testing capabilities ensure the competitivity of the tunnel at an international level.

  1. On tunneling across horizons

    OpenAIRE

    Vanzo, Luciano

    2011-01-01

    The tunneling method for stationary black holes in the Hamilton-Jacobi variant is reconsidered in the light of various critiques that have been moved against. It is shown that once the tunneling trajectories have been correctly identified the method isfree from internal inconsistencies, it is manifestly covariant, it allows for the extension to spinning particles and it can even be used without solving the Hamilton-Jacobi equation. These conclusions borrow support on a simple analytic continu...

  2. Tunnelling in organic superconductors

    OpenAIRE

    Bolech, C. J.; Giamarchi, T.

    2005-01-01

    We discuss the possibility of deciding on the symmetry of the superconducting phase in the organic superconductors (Bechgaard salts), using tunnelling experiments. We first briefly review the properties of organic superconductors, and the possibility to have unconventional (triplet) superconductivity in these systems. We then present a simple scheme for computing the full current-voltage characteristics for tunnelling experiments within the framework of the non-equilibrium Keldysh Green funct...

  3. Temperature stratification in tunnels

    OpenAIRE

    Nyman, Hans; Ingason, Haukur

    2012-01-01

    An investigation of previously established correlations between gas temperature distribution and smoke stratification in mines has been carried out for tunnel applications. The investigated correlations are based on excess gas temperature ratios and Froude number scaling. This paper describes a comparison between two large scale tests carried out in a road tunnel and two well defined model scale tests. In each of the tests, a longitudinal flow was maintained. The temperature data obtained at ...

  4. Gravity Tunnel Drag

    CERN Document Server

    Concannon, Thomas

    2016-01-01

    The time it takes to fall down a tunnel through the center of the Earth to the other side takes approximately 42 minutes, but only when given several simplifying assumptions: a uniform density Earth; a gravitational field that varies linearly with radial position; a non-rotating Earth; a tunnel evacuated of air; and zero friction along the sides of the tunnel. Though several papers have singularly relaxed the first three assumptions, in this paper we relax the final two assumptions and analyze the motion of a body experiencing these types of drag forces in the tunnel. Under such drag forces, we calculate the motion of a transport vehicle through a tunnel of the Earth under uniform density, under constant gravitational acceleration, and finally under the more realistic Preliminary Reference Earth Model (PREM) density data. We find the density profile corresponding to a constant gravitational acceleration better models the motion through the tunnel compared to the PREM density profile, and the uniform density m...

  5. Tunnelling of a molecule

    International Nuclear Information System (INIS)

    A quantum-mechanical description of tunnelling is presented for a one-dimensional system with internal oscillator degrees of freedom. The 'charged diatomic molecule' is frustrated on encountering a barrier potential by its centre of charge not being coincident with its centre of mass, resulting in transitions amongst internal states. In an adiabatic limit, the tunnelling of semiclassical coherent-like oscillator states is shown to exhibit the Hartman and Bueuttiker-Landauer times tH and tBL, with the time dependence of the coherent state parameter for the tunnelled state given by α(t) = α e-iω(t+Δt) , Δt = tH - itBL. A perturbation formalism is developed, whereby the exact transfer matrix can be expanded to any desired accuracy in a suitable limit. An 'intrinsic' time, based on the oscillator transition rate during tunnelling, transmission or reflection, is introduced. In simple situations the resulting intrinsic tunnelling time is shown to vanish to lowest order. In the general case a particular (nonzero) parametrisation is inferred, and its properties discussed in comparison with the literature on tunnelling times for both wavepackets and internal clocks. Copyright (1998) CSIRO Australia

  6. Numerical wind tunnels

    CERN Document Server

    Souza, Paulo Victor Santos

    2015-01-01

    Flow of viscous fluids are not usually discussed in detail in general and basic courses of physics. This is due in part to the fact that the Navier-Stokes equation has analytical solution only for a few restricted cases, while more sophisticated problems can only be solved by numerical methods. In this text, we present a computer simulation of wind tunnel, i.e., we present a set of programs to solve the Navier-Stokes equation for an arbitrary object inserted in a wind tunnel. The tunnel enables us to visualize the formation of vortices behind object, the so-called von K\\'arm\\'an vortices, and calculate the drag force on the object. We believe that this numerical wind tunnel can support the teacher and allow a more elaborate discussion of viscous flow. The potential of the tunnel is exemplified by the study of the drag on a simplified model of wing whose angle of attack can be controlled. A link to download the programs that make up the tunnel appears at the end.

  7. Bacterial Vaginosis

    Science.gov (United States)

    ... 586. Related Content STDs during Pregnancy Fact Sheet Pregnancy and HIV, Viral Hepatitis, and STD Prevention Pelvic Inflammatory Disease ( ... Bacterial Vaginosis (BV) Chlamydia Gonorrhea Genital Herpes Hepatitis HIV/AIDS & STDs Human Papillomavirus ... STDs See Also Pregnancy Reproductive ...

  8. Bacterial Meningitis

    Science.gov (United States)

    ... Schedules Preteen & Teen Vaccines Meningococcal Disease Sepsis Bacterial Meningitis Recommend on Facebook Tweet Share Compartir On this ... serious disease. Laboratory Methods for the Diagnosis of Meningitis This manual summarizes laboratory methods used to isolate, ...

  9. Fluorescent Structural DNA Nanoballs Functionalized With Phosphate-Linked Nucleotide Triphosphates

    Science.gov (United States)

    Anderson, Jon P.; Reynolds, Bambi L.; Baum, Kristin; Williams, John G.

    2010-01-01

    Highly labeled DNA nanoballs functionalized with phosphate-linked nucleotide triphosphates (dNTPs) were developed as a source of dNTPs for DNA polymerase. The particles were prepared by strand-displacement polymerization from a self-complementary circular template. Imaged by atomic force microscopy, these functionalized particles appear as condensed fuzzy balls with diameters between 50–150 nm. They emit a bright fluorescent signal, detected in 2 msec exposures with a signal-to-noise of 25 when imaged using a TIR fluorescence microscope. PMID:20158249

  10. Synthesis of Nucleoside Triphosphates from 2'-3'-Protected Nucleosides Using Trimetaphosphate.

    Science.gov (United States)

    Mohamady, Samy; Taylor, Scott D

    2016-02-01

    Chemists have been attempting to triphosphorylate nucleosides and other alcohols using trimetaphosphate (TriMP) since the 1960s. However, this route appears to have been abandoned due to poor yields. The first practical syntheses of nucleoside triphosphates (NTPs) are reported using TriMP as the key reagent. This was achieved by reacting the tetrabutylammonium salt of TriMP with mesitylenesulfonyl chloride in the presence of DABCO in pyridine followed by the addition of an appropriately protected nucleoside and phthalimide. Quenching the reaction with aqueous buffer followed by hydrolysis of the OH protecting groups gave the NTPs in good yield. PMID:26759914

  11. Chloride permeability of rat brain membrane vesicles correlates with thiamine triphosphate content.

    Science.gov (United States)

    Bettendorff, L; Hennuy, B; De Clerck, A; Wins, P

    1994-07-25

    Incubation of rat brain homogenates with thiamine or thiamine diphosphate (TDP) leads to a synthesis of thiamine triphosphate (TTP). In membrane vesicles subsequently prepared from the homogenates, increased TTP content correlates with increased 36Cl- uptake. A hyperbolic relationship was obtained with a K0.5 of 0.27 nmol TTP/mg protein. In crude mitochondrial fractions from the brains of animals previously treated with thiamine or sulbutiamine, a positive correlation between 36Cl- uptake and TTP content was found. These results, together with other results previously obtained with the patch-clamp technique, suggest that TTP is an activator of chloride channels having a large unit conductance. PMID:7953714

  12. Scope and Limitations of Typical Copper-Free Bioorthogonal Reactions with DNA: Reactive 2'-Deoxyuridine Triphosphates for Postsynthetic Labeling.

    Science.gov (United States)

    Merkel, Marcus; Arndt, Stefanie; Ploschik, Damian; Cserép, Gergely B; Wenge, Ulrike; Kele, Péter; Wagenknecht, Hans-Achim

    2016-09-01

    Four triphosphates of 2'-deoxyuridine that carried the following bioorthogonally reactive groups were synthesized by organic-chemical methods. Two triphosphates with tetrazines and one with a cyclopropene moiety were designed for Diels-Alder reactions with inverse electron demand, and one triphosphate with a tetrazole core was designed for the "photoclick" cycloaddition. These triphosphates were not only successfully applied for oligonucleotide preparation by standard DNA polymerases, including Hemo KlenTaq, Vent, and Deep Vent, but also bypassed for full length primer extension products. Fluorescent labeling of the primer extension products was achieved by fluorophores with reactive counterparts and analyzed by polyacrylamide gel electrophoresis mobility shifts. The tetrazine-oligonucleotide conjugates were reacted with carboxymethylmonobenzocyclooctyne- and bicyclononyne-modified fluorophores. The yield of these postsynthetic reactions could significantly be improved by a more stable but still reactive nicotinic acid-derived tetrazine and by changing the key experimental conditions, mainly the pH of 7.2 and the temperature of 45-55 °C. The cyclopropene-oligonucleotide conjugate could be successfully labeled with a tetrazine-modified rhodamine in very good yields. The "photoclick" cycloaddition between tetrazole-oligonucleotide conjugates and a maleimide-modified dye worked quantitatively. The combination of primer extension, bypass, and bioorthogonal modification works also for double and triple labeling using the cyclopropene-modified 2'-deoxyuridine triphosphate. PMID:27513089

  13. Bacterial carbonatogenesis

    International Nuclear Information System (INIS)

    Several series of experiments in the laboratory as well as in natural conditions teach that the production of carbonate particles by heterotrophic bacteria follows different ways. The 'passive' carbonatogenesis is generated by modifications of the medium that lead to the accumulation of carbonate and bicarbonate ions and to the precipitation of solid particles. The 'active' carbonatogenesis is independent of the metabolic pathways. The carbonate particles are produced by ionic exchanges through the cell membrane following still poorly known mechanisms. Carbonatogenesis appears to be the response of heterotrophic bacterial communities to an enrichment of the milieu in organic matter. The active carbonatogenesis seems to start first. It is followed by the passive one which induces the growth of initially produced particles. The yield of heterotrophic bacterial carbonatogenesis and the amounts of solid carbonates production by bacteria are potentially very high as compared to autotrophic or chemical sedimentation from marine, paralic or continental waters. Furthermore, the bacterial processes are environmentally very ubiquitous; they just require organic matter enrichment. Thus, apart from purely evaporite and autotrophic ones, all Ca and/or Mg carbonates must be considered as from heterotrophic bacterial origin. By the way, the carbon of carbonates comes from primary organic matter. Such considerations ask questions about some interpretations from isotopic data on carbonates. Finally, bacterial heterotrophic carbonatogenesis appears as a fundamental phase in the relationships between atmosphere and lithosphere and in the geo-biological evolution of Earth. (author)

  14. Interaction between groundwater and TBM (Tunnel Boring Machine) excavated tunnels

    OpenAIRE

    Font Capó, Jordi

    2012-01-01

    A number of problems, e.g. sudden inflows are encountered during tunneling under the piezometric level, especially when the excavation crosses high transmissivity areas. These inflows may drag materials when the tunnel crosses low competent layers, resulting in subsidence, chimney formation and collapses. Moreover, inflows can lead to a decrease in head level because of aquifer drainage. Tunnels can be drilled by a tunnel boring machine (TBM) to minimize inflows and groundwater impacts, restr...

  15. Shot Noise in Magnetic Tunnel Junctions: Evidence for Sequential Tunneling

    OpenAIRE

    Guerrero, R.; Aliev, F. G.; Tserkovnyak, Y.; Santos, T. S.; Moodera, J.S.

    2006-01-01

    We report the experimental observation of sub-Poissonian shot noise in single magnetic tunnel junctions, indicating the importance of tunneling via impurity levels inside the tunnel barrier. For junctions with weak zero-bias anomaly in conductance, the Fano factor (normalized shot noise) depends on the magnetic configuration being enhanced for antiparallel alignment of the ferromagnetic electrodes. We propose a model of sequential tunneling through nonmagnetic and paramagnetic impurity levels...

  16. Early times in tunneling

    CERN Document Server

    García-Calderón, G; Garcia-Calderon, Gaston; Villavicencio, Jorge

    2000-01-01

    Exact analytical solutions of the time-dependent Schr\\"odinger equation with the initial condition of an incident cutoff wave are used to investigate the traversal time for tunneling. The probability density starts from a vanishing value along the tunneling and transmitted regions of the potential. At the barrier width it exhibits, at early times, a distribution of traversal times that typically has a peak $\\tau_p$ and a width $\\Delta \\tau$. Numerical results for other tunneling times, as the phase-delay time, fall within $\\Delta \\tau$. The B\\"uttiker traversal time is the closest to $\\tau_p$. Our results resemble calculations based on Feynman paths if its noisy behaviour is ignored.

  17. Tunneling with negative tension

    CERN Document Server

    Marvel, Kate

    2008-01-01

    We describe a new family of thin-wall instantons, with negative tension bubble walls, that mediate tunneling between Minkowski or de Sitter vacua. Some of these instantons can have exponentially enhanced tunneling rates, and would dominate the Euclidean path integral, representing a severe non-perturbative instability in any theory which supports them. We give two constructions of these instantons in theories which are perturbatively stable, but violate the null energy condition. One construction uses a scalar field theory with higher-derivative kinetic term, and is similar to the Coleman-de Luccia positive tension instanton. The other construction employs a negative-tension boundary arising from Z_2 orbifolding: it resembles a "bubble of nothing" which nucleates and grows, consuming the surrounding de Sitter or Minkowski spacetime. We explain how the spectral flow for fluctutations about the thin-wall tunneling solutions automatically protects causality, for both positive and negative tension instantons. We ...

  18. Tunneling Through Black Rings

    Institute of Scientific and Technical Information of China (English)

    ZHAO Liu

    2007-01-01

    Hawking radiation of black ring solutions to 5-dimensional Einstein-Maxwell-dilaton theory is analyzed by use of the Parikh-Wilczek tunneling method. To get the correct tunneling amplitude and emission rate, we adopt and develop the Angheben-Nadalini-Vanzo-Zerbini covariant approach to cover the effects of rotation and electronic discharge all at once, and the effect of back reaction is also taken into account. This constitutes a unified approach to the tunneling problem. Provided the first law of thermodynamics for black rings holds, the emission rate is proportional to the exponential of the change of Bekenstein-Hawking entropy. Explicit calculation for black ring temperatures agrees exactly with the results obtained via the classical surface gravity method and the quasi-local formalism.

  19. Den Trygge Tunnel

    OpenAIRE

    Jensen, Claus Bach; Hertz, Thea Stine Lund; Loose, Mikkel Thybo; Carlsson, Katrine; Høg, Lasse Noe; Andersen, Ea Leighton

    2013-01-01

    Abstract Pedestrian tunnels in Denmark has for a long time just been something that is solely there to transport the pedestrians away and in safety from car or train traffic, from one point to another, and it still is in many cases. There has been no focus on making it an experience in itself, actively including the pedestrians, which could promote comfort, pleasure and a feeling of safety when using the tunnels. They are left as they were build; creepy, dark, humid, wet and often vandali...

  20. Long distance tunneling

    CERN Document Server

    Ivlev, B I

    2005-01-01

    Quantum tunneling between two potential wells in a magnetic field can be strongly increased when the potential barrier varies in the direction perpendicular to the line connecting the two wells and remains constant along this line. A periodic structure of the wave function is formed in the direction joining the wells. The resulting motion can be coherent like motion in a conventional narrow band periodic structure. A particle penetrates the barrier over a long distance which strongly contrasts to WKB-like tunneling. The whole problem is stationary. The coherent process can be influenced by dissipation.

  1. Tunneling in Axion Monodromy

    CERN Document Server

    Brown, Jon; Shiu, Gary; Soler, Pablo

    2016-01-01

    The Coleman formula for vacuum decay and bubble nucleation has been used to estimate the tunneling rate in models of axion monodromy in recent literature. However, several of Coleman's original assumptions do not hold for such models. Here we derive a new estimate with this in mind using a similar Euclidean procedure. We find that there are significant regions of parameter space for which the tunneling rate in axion monodromy is not well approximated by the Coleman formula. However, there is also a regime relevant to large field inflation in which both estimates parametrically agree. We also briefly comment on the applications of our results to the relaxion scenario.

  2. Programmable ferroelectric tunnel memristor

    OpenAIRE

    Andy eQuindeau; Dietrich eHesse; Marin eAlexe

    2014-01-01

    We report an analogously programmable memristor based on genuine electronic resistive switching combining ferroelectric switching and electron tunneling. The tunnel current through an 8 unit cell thick epitaxial Pb(Zr[0.2]Ti[0.8])O[3] film sandwiched between La[0.7]Sr[0.3]MnO[3] and cobalt electrodes obeys the Kolmogorov-Avrami-Ishibashi model for bidimensional growth with a characteristic switching time in the order of 10^-7 seconds. The analytical description of switching kinetics allows us...

  3. INCAS SUBSONIC WIND TUNNEL

    OpenAIRE

    Corneliu STOICA; Corneliu OPREAN; Florin MUNTEANU

    2009-01-01

    The INCAS Subsonic Wind Tunnel is a closed circuit, continuous, atmospheric pressure facility with a maximum speed of 110 m/s. The test section is octagonal ,of 2.5 m wide, 2.0 m high and 4 m long. The tunnel is powered by a 1200 kW, air cooled variable speed DC motor which drives a 12 blade, 3.5 m diameter fan and is equipped with a six component pyramidal type external mechanical balance with a 700 Kgf maximum lift capacity.The angle of attack range is between -45º and +45º while the yaw an...

  4. Breaking through the tranfer tunnel

    CERN Multimedia

    Laurent Guiraud

    2001-01-01

    This image shows the tunnel boring machine breaking through the transfer tunnel into the LHC tunnel. Proton beams will be transferred from the SPS pre-accelerator to the LHC at 450 GeV through two specially constructed transfer tunnels. From left to right: LHC Project Director, Lyn Evans; CERN Director-General (at the time), Luciano Maiani, and Director for Accelerators, Kurt Hubner.

  5. Gap anisotropy and tunneling currents. [MPS3

    DEFF Research Database (Denmark)

    Lazarides, N.; Sørensen, Mads Peter

    1996-01-01

    The tunneling Hamiltonian formalism is applied to calculate the tunnelingcurrents through a small superconducting tunnel junction. The formalism isextended to nonconstant tunneling matrix elements. The electrodes of thejunction are assumed to......The tunneling Hamiltonian formalism is applied to calculate the tunnelingcurrents through a small superconducting tunnel junction. The formalism isextended to nonconstant tunneling matrix elements. The electrodes of thejunction are assumed to...

  6. Bacterial Adhesion & Blocking Bacterial Adhesion

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk

    2008-01-01

    tract to the microbial flocs in waste water treatment facilities. Microbial biofilms may however also cause a wide range of industrial and medical problems, and have been implicated in a wide range of persistent infectious diseases, including implantassociated microbial infections. Bacterial adhesion...... is the first committing step in biofilm formation, and has therefore been intensely scrutinized. Much however, still remains elusive. Bacterial adhesion is a highly complex process, which is influenced by a variety of factors. In this thesis, a range of physico-chemical, molecular and environmental parameters......, which influence the transition from a planktonic lifestyle to a sessile lifestyle, have been studied. Protein conditioning film formation was found to influence bacterial adhesion and subsequent biofilm formation considerable, and an aqueous extract of fish muscle tissue was shown to significantly...

  7. Bacterial lipases

    NARCIS (Netherlands)

    Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno

    1994-01-01

    Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation, mea

  8. Comparison of immunomagnetic separation/adenosine triphosphate rapid method to traditional culture-based method for E. coli and enterococci enumeration in wastewater.

    Science.gov (United States)

    Bushon, Rebecca N; Likirdopulos, Christina A; Brady, Amie M G

    2009-11-01

    Untreated wastewater samples from California, North Carolina, and Ohio were analyzed by the immunomagnetic separation/adenosine triphosphate (IMS/ATP) method and the traditional culture-based method for E. coli and enterococci concentrations. The IMS/ATP method concentrates target bacteria by immunomagnetic separation and then quantifies captured bacteria by measuring bioluminescence induced by release of ATP from the bacterial cells. Results from this method are available within 1h from the start of sample processing. Significant linear correlations were found between the IMS/ATP results and results from traditional culture-based methods for E. coli and enterococci enumeration for one location in California, two locations in North Carolina, and one location in Ohio (r values ranged from 0.87 to 0.97). No significant linear relation was found for a second location in California that treats a complex mixture of residential and industrial wastewater. With the exception of one location, IMS/ATP showed promise as a rapid method for the quantification of faecal-indicator organisms in wastewater.

  9. Comparison of immunomagnetic separation/adenosine triphosphate rapid method to traditional culture-based method for E. coli and enterococci enumeration in wastewater

    Science.gov (United States)

    Bushon, R.N.; Likirdopulos, C.A.; Brady, A.M.G.

    2009-01-01

    Untreated wastewater samples from California, North Carolina, and Ohio were analyzed by the immunomagnetic separation/adenosine triphosphate (IMS/ATP) method and the traditional culture-based method for E. coli and enterococci concentrations. The IMS/ATP method concentrates target bacteria by immunomagnetic separation and then quantifies captured bacteria by measuring bioluminescence induced by release of ATP from the bacterial cells. Results from this method are available within 1 h from the start of sample processing. Significant linear correlations were found between the IMS/ATP results and results from traditional culture-based methods for E. coli and enterococci enumeration for one location in California, two locations in North Carolina, and one location in Ohio (r??values ranged from 0.87 to 0.97). No significant linear relation was found for a second location in California that treats a complex mixture of residential and industrial wastewater. With the exception of one location, IMS/ATP showed promise as a rapid method for the quantification of faecal-indicator organisms in wastewater.

  10. Tunnelling with wormhole creation

    Energy Technology Data Exchange (ETDEWEB)

    Ansoldi, S. [National Institute of Nuclear Physics (INFN) (Italy); Tanaka, T., E-mail: tanaka@yukawa.kyoto-u.ac.jp [Kyoto University, Department of Physics (Japan)

    2015-03-15

    The description of quantum tunnelling in the presence of gravity shows subtleties in some cases. We discuss wormhole production in the context of the spherically symmetric thin-shell approximation. By presenting a fully consistent treatment based on canonical quantization, we solve a controversy present in the literature.

  11. Tunnelling with wormhole creation

    OpenAIRE

    Ansoldi, Stefano; Tanaka, Takahiro

    2014-01-01

    The description of quantum tunnelling in the presence of gravity shows subtleties in some cases. Here we discuss wormhole production in the context of the spherically symmetric thin-shell approximation. By presenting a fully consistent treatment based on canonical quantization, we solve a controversy present in literature.

  12. INCAS SUBSONIC WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Corneliu STOICA

    2009-09-01

    Full Text Available The INCAS Subsonic Wind Tunnel is a closed circuit, continuous, atmospheric pressure facility with a maximum speed of 110 m/s. The test section is octagonal ,of 2.5 m wide, 2.0 m high and 4 m long. The tunnel is powered by a 1200 kW, air cooled variable speed DC motor which drives a 12 blade, 3.5 m diameter fan and is equipped with a six component pyramidal type external mechanical balance with a 700 Kgf maximum lift capacity.The angle of attack range is between -45º and +45º while the yaw angle range is between -140º and +216º .The data acquisition system has been modified recently to allow the recording of all test data on a PC - type computer using LABVIEW and a PXI – type chassis containing specialized data acquisition modules.The tunnel is equipped with a variable frequency electrical supply system for powered models and a 10 bar compressed air supply for pneumatic flow control applications.In the recent years the subsonic wind tunnel has been intensively used for tests within several European projects (AVERT, CESAR and others.

  13. Carpal tunnel release

    DEFF Research Database (Denmark)

    Larsen, Morten Bo; Sørensen, A I; Crone, K L;

    2013-01-01

    A single-blind, randomized, controlled trial was done to compare the results of carpal tunnel release using classic incision, short incision, or endoscopic technique. In total, 90 consecutive cases were included. Follow-up was 24 weeks. We found a significantly shorter sick leave in the endoscopic...

  14. Adenosine triphosphate concentration in relation to microbial biomass in aquatic systems

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, H.W. Jr.

    1977-01-01

    Analyses of adenosine triphosphate (ATP) extracted from a sediment community of an aquatic ecosystem by the sulfuric acid method are complicated by inhibitions from inorganic and organic compounds. Inhibitions by inorganic compounds are reversible while those by organic compounds are irreversible. The primary inhibition by organic compounds results by complexing with acid-soluble fulvic acids which will prevent the detection of as much as 80% of the ATP present in a sample by the luciferin-luciferase reaction. Analytical techniques were developed to partially circumvent such interferences. Biomass interpretations from ATP concentrations in aquatic systems are complicated by the diversity of the microbiota and by the variability in the carbon to ATP ratio caused by environmental conditions. However, when levels of ATP are considered as a physiological condition of a sedimentary community, this data provides a means to interpret community metabolism not available hitherto.

  15. Interaction of Divalent Metal Ions with the Adenosine Triphosphate Measured Using Nuclear Magnetic Resonance

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The interaction of adenosine triphosphate with divalent metal ions is important in biochemical functions. The effects of pH and metal ions Mg2+, Ca2+, Zn2+, Mn2+, and Co2+ on the chemical shift of the phosphate group of ATP have been studied using Nuclear Magnetic Resonance. The chemical shift of the β-phosphate of ATP is the most sensitive to pH. Ca2+ and Mg2+ bind with the α- and β-phosphate groups of ATP. Zn2+ binds to the adenosine ring hydrogen as well as to phosphate. The paramagnetic ions Mn2+ and Co2+ do not cause chemical shifts of the phosphate or proton peak. Mn2+ and Co2+ broaden the resonance peak only.

  16. Genetics and complementation of Haemophilus influenzae mutants deficient in adenosine 5'-triphosphate-dependent nuclease

    Energy Technology Data Exchange (ETDEWEB)

    Kooistra, J.; Small, G.D.; Setlow, J.K.; Shapanka, R.

    1976-04-01

    Eight different mutations in Haemophilus influenzae leading to deficiency in adenosine 5'-triphosphate (ATP)-dependent nuclease have been investigated in strains in which the mutations of the originally mutagenized strains have been transferred into the wild type. Sensitivity to mitomycin C and deoxycholate and complementation between extracts and deoxyribonucleic acid (DNA)-dependent ATPase activity have been measured. Genetic crosses have provided information on the relative position of the mutations on the genome. There are three complementation groups, corresponding to three genetic groups. The strains most sensitive to mitomycin and deoxycholate, derived from mutants originally selected on the basis of sensitivity to mitomycin C or methyl methanesulfonate, are in one group. Apparently all these sensitive strains lack DNA-dependent ATPase activity, as does a strain intermediate in sensitivity to deoxycholate, which is the sole representative of another group. There are four strains that are relatively resistant to deoxycholate and mitomycin C, and all of these contain the ATPase activity.

  17. Monitoring pilot projects on bored tunnelling: the Second Heinenoord Tunnel and the Botlek Rail Tunnel

    NARCIS (Netherlands)

    Bakker, K.J.; De Boer, F.; Admiraal, J.B.M.; Van Jaarsveld, E.P.

    1999-01-01

    Two pilot projects for bored tunnelling in soft soil have been undertaken in the Netherlands. The monitoring was commissioned under the authority of the Centre for Underground Construction (COB). A description of the research related to the Second Heinenoord Tunnel and the Botlek Rail Tunnel will be

  18. Classical trajectories and quantum tunneling

    CERN Document Server

    Ivlev, B I

    2003-01-01

    The problem of inter-band tunneling in a semiconductor (Zener breakdown) in a nonstationary and homogeneous electric field is solved exactly. Using the exact analytical solution, the approximation based on classical trajectories is studied. A new mechanism of enhanced tunneling through static non-one-dimensional barriers is proposed in addition to well known normal tunneling solely described by a trajectory in imaginary time. Under certain conditions on the barrier shape and the particle energy, the probability of enhanced tunneling is not exponentially small even for non-transparent barriers, in contrast to the case of normal tunneling.

  19. A sensitive LC-MS/MS method for quantifying clofarabine triphosphate concentrations in human peripheral blood mononuclear cells.

    Science.gov (United States)

    Tu, Xiaowei; Lu, Youming; Zhong, Dafang; Zhang, Yifan; Chen, Xiaoyan

    2014-08-01

    Clofarabine triphosphate is an intracellular active metabolite of clofarabine. In the present study, we developed and validated a rapid, sensitive, and selective liquid chromatography-tandem mass spectrometry method (LC-MS/MS) for quantifying clofarabine triphosphate concentrations in human peripheral blood mononuclear cells (PBMCs). PBMCs were isolated from blood using the Ficoll gradient centrifugation method. Chromatographic separation was performed on a CN column using an isocratic mobile phase comprising acetonitrile/5mM ammonium acetate with 0.001% ammonium hydroxide (20/80, v/v) at a flow rate of 0.60 mL/min. Detection was carried out by MS/MS in the multiple reaction monitoring mode using a negative electrospray ionization interface. The method was validated in concentration ranges of 1.25-100 ng/10(7) cells with acceptable accuracy and precision using 50 μL of cell extract. Clofarabine triphosphate was stable in a series of stability studies with bench-top, auto-sampler, and repeated freeze-thaw cycles. The validated method was successfully used to measure the concentrations of clofarabine triphosphate in PBMCs from cancer patients treated with clofarabine. PMID:24529342

  20. Bacterial Ecology

    DEFF Research Database (Denmark)

    Fenchel, Tom

    2011-01-01

    Bacterial ecology is concerned with the interactions between bacteria and their biological and nonbiological environments and with the role of bacteria in biogeochemical element cycling. Many fundamental properties of bacteria are consequences of their small size. Thus, they can efficiently exploit...... biogeochemical processes are carried exclusively by bacteria. * Bacteria play an important role in all types of habitats including some that cannot support eukaryotic life....

  1. [Bacterial vaginosis].

    Science.gov (United States)

    Romero Herrero, Daniel; Andreu Domingo, Antonia

    2016-07-01

    Bacterial vaginosis (BV) is the main cause of vaginal dysbacteriosis in the women during the reproductive age. It is an entity in which many studies have focused for years and which is still open for discussion topics. This is due to the diversity of microorganisms that cause it and therefore, its difficult treatment. Bacterial vaginosis is probably the result of vaginal colonization by complex bacterial communities, many of them non-cultivable and with interdependent metabolism where anaerobic populations most likely play an important role in its pathogenesis. The main symptoms are an increase of vaginal discharge and the unpleasant smell of it. It can lead to serious consequences for women, such as an increased risk of contracting sexually transmitted infections including human immunodeficiency virus and upper genital tract and pregnancy complications. Gram stain is the gold standard for microbiological diagnosis of BV, but can also be diagnosed using the Amsel clinical criteria. It should not be considered a sexually transmitted disease but it is highly related to sex. Recurrence is the main problem of medical treatment. Apart from BV, there are other dysbacteriosis less characterized like aerobic vaginitis of which further studies are coming slowly but are achieving more attention and consensus among specialists. PMID:27474242

  2. Detection of adenosine triphosphate through polymerization-induced aggregation of actin-conjugated gold/silver nanorods

    Science.gov (United States)

    Liao, Yu-Ju; Shiang, Yen-Chun; Chen, Li-Yi; Hsu, Chia-Lun; Huang, Chih-Ching; Chang, Huan-Tsung

    2013-11-01

    We have developed a simple and selective nanosensor for the optical detection of adenosine triphosphate (ATP) using globular actin-conjugated gold/silver nanorods (G-actin-Au/Ag NRs). By simply mixing G-actin and Au/Ag NRs (length ˜56 nm and diameter ˜12 nm), G-actin-Au/Ag NRs were prepared which were stable in physiological solutions (25 mM Tris-HCl, 150 mM NaCl, 5.0 mM KCl, 3.0 mM MgCl2 and 1.0 mM CaCl2; pH 7.4). Introduction of ATP into the G-actin-Au/Ag NR solutions in the presence of excess G-actin induced the formation of filamentous actin-conjugated Au/Ag NR aggregates through ATP-induced polymerization of G-actin. When compared to G-actin-modified spherical Au nanoparticles having a size of 13 nm or 56 nm, G-actin-Au/Ag NRs provided better sensitivity for ATP, mainly because the longitudinal surface plasmon absorbance of the Au/Ag NR has a more sensitive response to aggregation. This G-actin-Au/Ag NR probe provided high sensitivity (limit of detection 25 nM) for ATP with remarkable selectivity (>10-fold) over other adenine nucleotides (adenosine, adenosine monophosphate and adenosine diphosphate) and nucleoside triphosphates (guanosine triphosphate, cytidine triphosphate and uridine triphosphate). It also allowed the determination of ATP concentrations in plasma samples without conducting tedious sample pretreatments; the only necessary step was simple dilution. Our experimental results are in good agreement with those obtained from a commercial luciferin-luciferase bioluminescence assay. Our simple, sensitive and selective approach appears to have a practical potential for the clinical diagnosis of diseases (e.g. cystic fibrosis) associated with changes in ATP concentrations.

  3. Regulation of the intersubunit ammonia tunnel in Mycobacterium tuberculosis glutamine-dependent NAD[superscript +] synthetase

    Energy Technology Data Exchange (ETDEWEB)

    Chuenchor, Watchalee; Doukov, Tzanko I.; Resto, Melissa; Chang, Andrew; Gerratana, Barbara (SSRL); (Maryland)

    2012-08-31

    Glutamine-dependent NAD{sup +} synthetase is an essential enzyme and a validated drug target in Mycobacterium tuberculosis (mtuNadE). It catalyses the ATP-dependent formation of NAD{sup +} from NaAD{sup +} (nicotinic acid-adenine dinucleotide) at the synthetase active site and glutamine hydrolysis at the glutaminase active site. An ammonia tunnel 40 {angstrom} (1 {angstrom} = 0.1 nm) long allows transfer of ammonia from one active site to the other. The enzyme displays stringent kinetic synergism; however, its regulatory mechanism is unclear. In the present paper, we report the structures of the inactive glutaminase C176A variant in an apo form and in three synthetase-ligand complexes with substrates (NaAD{sup +}/ATP), substrate analogue {l_brace}NaAD{sup +}/AMP-CPP (adenosine 5'-[{alpha},{beta}-methylene]triphosphate){r_brace} and intermediate analogues (NaAD{sup +}/AMP/PPi), as well as the structure of wild-type mtuNadE in a product complex (NAD{sup +}/AMP/PPi/glutamate). This series of structures provides snapshots of the ammonia tunnel during the catalytic cycle supported also by kinetics and mutagenesis studies. Three major constriction sites are observed in the tunnel: (i) at the entrance near the glutaminase active site; (ii) in the middle of the tunnel; and (iii) at the end near the synthetase active site. Variation in the number and radius of the tunnel constrictions is apparent in the crystal structures and is related to ligand binding at the synthetase domain. These results provide new insight into the regulation of ammonia transport in the intermolecular tunnel of mtuNadE.

  4. Programmable ferroelectric tunnel memristor

    Directory of Open Access Journals (Sweden)

    Andy eQuindeau

    2014-02-01

    Full Text Available We report an analogously programmable memristor based on genuine electronic resistive switching combining ferroelectric switching and electron tunneling. The tunnel current through an 8 unit cell thick epitaxial Pb(Zr[0.2]Ti[0.8]O[3] film sandwiched between La[0.7]Sr[0.3]MnO[3] and cobalt electrodes obeys the Kolmogorov-Avrami-Ishibashi model for bidimensional growth with a characteristic switching time in the order of 10^-7 seconds. The analytical description of switching kinetics allows us to develop a characteristic transfer function that has only one parameter viz. the characteristic switching time and fully predicts the resistive states of this type of memristor.

  5. On tunneling across horizons

    Science.gov (United States)

    Vanzo, L.

    2011-07-01

    The tunneling method for stationary black holes in the Hamilton-Jacobi variant is reconsidered in the light of some critiques that have been moved against. It is shown that once the tunneling trajectories have been correctly identified the method is free from internal inconsistencies, it is manifestly covariant, it allows for the extension to spinning particles and it can even be used without solving the Hamilton-Jacobi equation. These conclusions borrow support on a simple analytic continuation of the classical action of a pointlike particle, made possible by the unique assumption that it should be analytic in the complexified Schwarzschild or Kerr-Newman space-time. A more general version of the Parikh-Wilczek method will also be proposed along these lines.

  6. Educational Wind Tunnel

    Directory of Open Access Journals (Sweden)

    Juozas Bielskus

    2012-12-01

    Full Text Available The paper analyzes an educational wind tunnel produced by the Department of Building Energetics (DBE of Vilnius Gediminas Technical University. The equipment could be used for performing laboratory works and simple research. The article presents the projection of inflow and outlet velocity in the working chamber of DBE wind tunnel and carries out actual noise level measurement. The received data are compared with information on the level of noise generated by the fan considering instructions provided by the manufacturer. In order to assess the reliability of the computer program, simulation applying PHOENICS software has been conducted. The aim of modeling is to simulate a pilot model and to compare the obtained results with those of an analogous test presented in scientific articles.Article in Lithuanian

  7. Tunnel boring machine applications

    International Nuclear Information System (INIS)

    This paper reports that characterization of Yucca Mountain for a potential repository requires construction of an underground Exploratory Studies Facility (ESF). Mechanical excavating methods have been proposed for construction of the ESF as they offer a number of advantages over drilling and blasting at the Yucca Mountain site, including; less ground disturbance and therefore a potential for less adverse effects on the integrity of the site, creation of a more stable excavation cross section requiring less ground support, and an inherently safer and cleaner working environment. The tunnel boring machine (TBM) provides a proven technology for excavating the welded and unwelded Yucca Mountain tuffs. The access ramps and main underground tunnels form the largest part of the ESF underground construction work, and have been designed for excavation by TBM

  8. Fire Size in Tunnels

    OpenAIRE

    Carvel, Ricky O

    2004-01-01

    In recent years, a number of high profile accidental fires have occurred in several road and rail tunnels throughout the world. Many of these fires grew rapidly to catastrophic size and claimed many lives. The processes involved in the rapid growth and extremely severe of these fires are not adequately understood as yet. The introduction to this thesis reviews a number of these accidental fires and describes much of the previous experimental research which has brought about the...

  9. The beam dump tunnels

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    In these images workers are digging the tunnels that will be used to dump the counter-circulating beams. Travelling just a fraction under the speed of light, the beams at the LHC will each carry the energy of an aircraft carrier travelling at 12 knots. In order to dispose of these beams safely, a beam dump is used to extract the beam and diffuse it before it collides with a radiation shielded graphite target.

  10. Ferroelectric tunnel memristor.

    Science.gov (United States)

    Kim, D J; Lu, H; Ryu, S; Bark, C-W; Eom, C-B; Tsymbal, E Y; Gruverman, A

    2012-11-14

    Strong interest in resistive switching phenomena is driven by a possibility to develop electronic devices with novel functional properties not available in conventional systems. Bistable resistive devices are characterized by two resistance states that can be switched by an external voltage. Recently, memristors-electric circuit elements with continuously tunable resistive behavior-have emerged as a new paradigm for nonvolatile memories and adaptive electronic circuit elements. Employment of memristors can radically enhance the computational power and energy efficiency of electronic systems. Most of the existing memristor prototypes involve transition metal oxide resistive layers where conductive filaments formation and/or the interface contact resistance control the memristive behavior. In this paper, we demonstrate a new type of memristor that is based on a ferroelectric tunnel junction, where the tunneling conductance can be tuned in an analogous manner by several orders of magnitude by both the amplitude and the duration of the applied voltage. The ferroelectric tunnel memristors exhibit a reversible hysteretic nonvolatile resistive switching with a resistance ratio of up to 10(5) % at room temperature. The observed memristive behavior is attributed to the field-induced charge redistribution at the ferroelectric/electrode interface, resulting in the modulation of the interface barrier height. PMID:23039785

  11. Tunnelling from black holes and tunnelling into white holes

    Science.gov (United States)

    Chatterjee, Bhramar; Ghosh, A.; Mitra, P.

    2008-03-01

    Hawking radiation is nowadays being understood as tunnelling through black hole horizons. Here, the extension of the Hamilton-Jacobi approach to tunnelling for non-rotating and rotating black holes in different non-singular coordinate systems not only confirms this quantum emission from black holes but also reveals the new phenomenon of absorption into white holes by quantum mechanical tunnelling. The rôle of a boundary condition of total absorption or emission is also clarified.

  12. Quantum tunneling in thermal medium

    OpenAIRE

    Matsumoto, Sh.; Yoshimura, M.

    2000-01-01

    Time evolution of tunneling phenomena in medium is studied using a standard model of environment interaction. A semiclassical formula valid at low, but finite temperatures is derived in the form of integral transform for the reduced Wigner function, and the tunneling probability in thermal medium is calculated for a general tunneling potential of one dimensional system. Effect of dissipation, its time evolution in particular, depends on the behavior of the potential far beyond the barrier.

  13. Managerial Ownership Influencing Tunnelling Behaviour

    Directory of Open Access Journals (Sweden)

    Agung Juliarto

    2013-06-01

    Full Text Available This study investigates the extent and the determinants of tunnelling behaviour in five ASEAN countries (i.e. Indonesia, Malaysia, Philippines, Singapore, and Thailand. Related party transactions (RPTs in the form of loans to related parties are used as the proxy for tunnelling. With 200 firm-year observations over the period 2006-2009, this study finds a positive association between managerial ownership and the extent of tunnelling.The other important findings are that business environment (BE, foreign ownership, and independent directors are ineffective governance mechanisms to rein in tunnelling behaviour. This suggests that regulators need to evolve more effective governance mechanisms.

  14. Hybrid integrated biological-solid-state system powered with adenosine triphosphate

    Science.gov (United States)

    Roseman, Jared M.; Lin, Jianxun; Ramakrishnan, Siddharth; Rosenstein, Jacob K.; Shepard, Kenneth L.

    2015-12-01

    There is enormous potential in combining the capabilities of the biological and the solid state to create hybrid engineered systems. While there have been recent efforts to harness power from naturally occurring potentials in living systems in plants and animals to power complementary metal-oxide-semiconductor integrated circuits, here we report the first successful effort to isolate the energetics of an electrogenic ion pump in an engineered in vitro environment to power such an artificial system. An integrated circuit is powered by adenosine triphosphate through the action of Na+/K+ adenosine triphosphatases in an integrated in vitro lipid bilayer membrane. The ion pumps (active in the membrane at numbers exceeding 2 × 106 mm-2) are able to sustain a short-circuit current of 32.6 pA mm-2 and an open-circuit voltage of 78 mV, providing for a maximum power transfer of 1.27 pW mm-2 from a single bilayer. Two series-stacked bilayers provide a voltage sufficient to operate an integrated circuit with a conversion efficiency of chemical to electrical energy of 14.9%.

  15. Five putative nucleoside triphosphate diphosphohydrolase genes are expressed in Trichomonas vaginalis.

    Science.gov (United States)

    Frasson, Amanda Piccoli; Dos Santos, Odelta; Meirelles, Lúcia Collares; Macedo, Alexandre José; Tasca, Tiana

    2016-01-01

    Trichomonas vaginalis is a protozoan that parasitizes the human urogenital tract causing trichomoniasis, the most common non-viral sexually transmitted disease. The parasite has unique genomic characteristics such as a large genome size and expanded gene families. Ectonucleoside triphosphate diphosphohydrolase (E-NTPDase) is an enzyme responsible for hydrolyzing nucleoside tri- and diphosphates and has already been biochemically characterized in T. vaginalis. Considering the important role of this enzyme in the production of extracellular adenosine for parasite uptake, we evaluated the gene expression of five putative NTPDases in T. vaginalis. We showed that all five putative TvNTPDase genes (TvNTPDase1-5) were expressed by both fresh clinical and long-term grown isolates. The amino acid alignment predicted the presence of the five crucial apyrase conserved regions, transmembrane domains, signal peptides, phosphorylation and catalytic sites. Moreover, a phylogenetic analysis showed that TvNTPDase sequences make up a clade with NTPDases intracellularly located. Biochemical NTPDase activity (ATP and ADP hydrolysis) is responsive to the serum-restrictive conditions and the gene expression of TvNTPDases was mostly increased, mainly TvNTPDase2 and TvNTPDase4, although there was not a clear pattern of expression among them. In summary, the present report demonstrates the gene expression patterns of predicted NTPDases in T. vaginalis.

  16. A Graphene and Aptamer Based Liquid Gated FET-Like Electrochemical Biosensor to Detect Adenosine Triphosphate.

    Science.gov (United States)

    Mukherjee, Souvik; Meshik, Xenia; Choi, Min; Farid, Sidra; Datta, Debopam; Lan, Yi; Poduri, Shripriya; Sarkar, Ketaki; Baterdene, Undarmaa; Huang, Ching-En; Wang, Yung Yu; Burke, Peter; Dutta, Mitra; Stroscio, Michael A

    2015-12-01

    Here we report successful demonstration of a FET-like electrochemical nano-biosensor to accurately detect ultralow concentrations of adenosine triphosphate. As a 2D material, graphene is a promising candidate due to its large surface area, biocompatibility, and demonstrated surface binding chemistries and has been employed as the conducting channel. A short 20-base DNA aptamer is used as the sensing element to ensure that the interaction between the analyte and the aptamer occurs within the Debye length of the electrolyte (PBS). Significant increase in the drain current with progressive addition of ATP is observed whereas for control experiments, no distinct change in the drain current occurs. The sensor is found to be highly sensitive in the nanomolar (nM) to micromolar ( μM) range with a high sensitivity of 2.55 μA (mM) (-1), a detection limit as low as 10 pM, and it has potential application in medical and biological settings to detect low traces of ATP. This simplistic design strategy can be further extended to efficiently detect a broad range of other target analytes.

  17. Leptin suppresses adenosine triphosphate-induced impairment of spinal cord astrocytes.

    Science.gov (United States)

    Li, Baoman; Qi, Shuang; Sun, Guangfeng; Yang, Li; Han, Jidong; Zhu, Yue; Xia, Maosheng

    2016-10-01

    Spinal cord injury (SCI) causes long-term disability and has no clinically effective treatment. After SCI, adenosine triphosphate (ATP) may be released from neuronal cells and astrocytes in large amounts. Our previous studies have shown that the extracellular release of ATP increases the phosphorylation of cytosolic phospholipase A2 (cPLA2 ) and triggers the rapid release of arachidonic acid (AA) and prostaglandin E2 (PGE2) via the stimulation of epidermal growth factor receptor (EGFR) and the downstream phosphorylation of extracellular-regulated protein kinases 1 and 2. Leptin, a glycoprotein, induces the activation of the Janus kinase (JAK2)/signal transducers and activators of transcription-3 (Stat3) pathway via the leptin receptor. In this study, we found that 1) prolonged leptin treatment suppressed the ATP-stimulated release of AA and PGE2 from cultured spinal cord astrocytes; 2) leptin elevated the expression of caveolin-1 (Cav-1) via the JAK2/Stat3 signaling pathway; 3) Cav-1 blocked the interaction between Src and EGFR, thereby inhibiting the phosphorylation of EGFR and cPLA2 and attenuating the release of AA or PGE2; 4) pretreatment with leptin decreased ;he level of apoptosis and the release of interleukin-6 from cocultured neurons and astrocytes; and 5) leptin improved the recovery of locomotion in mice after SCI. Our results highlight leptin as a promising therapeutic agent for SCI. © 2016 Wiley Periodicals, Inc. PMID:27316329

  18. The clinical value of adenosine triphosphate stress myocardial perfusion tomography for detecting coronary artery disease

    International Nuclear Information System (INIS)

    Objective: To study the clinical value of adenosine triphosphate stress myocardial perfusion tomography imaging (ATP-MPI) in detection of coronary artery disease (CAD). Methods: There were 278 patients underwent ATP-MPI, 51 patients of them also underwent coronary angiography (CAG). Seventy-three patients underwent stress-rest myocardial perfusion tomography imaging with multi-stage submaximal exercise test (ST-MPI) and CAG serving as control group. Results: 1) Side effects: there were 11 different symptoms and atrioventricular conduction block (10 patients), sinoatrial conduction block (2 patients) occurred during ATP stress. Allopathy or interruption of ATP stress did not happen. 2) The sensitivity and specificity of ATP-MPI in detection of CAD were 97.1% and 82.4%, respectively, and those in detection of ≥50% narrowing coronary artery were 91.0% and 94.7%, respectively. 3) In patients without myocardial infarction, the sensitivity and specificity of ATP-MPI in detection of myocardial ischemia were comparable to those of ST-MPI. Conclusion: ATP-MPI is an accurate, safe modality and is comparable to ST-MPI in the detection of CAD

  19. Measurement and interpretation of microbial adenosine tri-phosphate (ATP) in aquatic environments.

    Science.gov (United States)

    Hammes, Frederik; Goldschmidt, Felix; Vital, Marius; Wang, Yingying; Egli, Thomas

    2010-07-01

    There is a widespread need for cultivation-free methods to quantify viability of natural microbial communities in aquatic environments. Adenosine tri-phosphate (ATP) is the energy currency of all living cells, and therefore a useful indicator of viability. A luminescence-based ATP kit/protocol was optimised in order to detect ATP concentrations as low as 0.0001 nM with a standard deviation of water samples from a variety of aquatic environments (drinking water, groundwater, bottled water, river water, lake water and wastewater effluent) were analysed for extracellular ATP and microbial ATP in comparison with flow-cytometric (FCM) parameters. Microbial ATP concentrations ranged between 3% and 97% of total ATP concentrations, and correlated well (R(2)=0.8) with the concentrations of intact microbial cells (after staining with propidium iodide). From this correlation, we calculated an average ATP-per-cell value of 1.75x10(-10)nmol/cell. An even better correlation (R(2)=0.88) was observed between intact biovolume (derived from FCM scatter data) and microbial ATP concentrations, and an average ATP-per-biovolume value of 2.95x10(-9)nmol/microm(3) was calculated. These results support the use of ATP analysis for both routine monitoring and research purposes, and contribute towards a better interpretation of ATP data. PMID:20605621

  20. INHIBITORY EFFECTS OF ADENOSINE 5' -TRIPHOSPHATE ON COCHLEAR FUNCTION OF GUINEA PIG

    Institute of Scientific and Technical Information of China (English)

    杨军; 李吉平; 钱敏飞; 徐秀玲; 王家东; 丁大连

    2005-01-01

    Objective To study effects of adenosine 5'-triphosphate (ATP) on cochlear function of guinea pig. Methods After perfusion of ATP into perilymphatic spaces of the guinea pig cochlea, summating potential (SP), cochlear microphonic (CM) , auditory nerve compound action potential ( CAP ) , distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) were measured. Results The results showed concentration-dependent effect of ATP on the response alterations of bioelectric activity in cochlea. Administration of lmmol/L ATP caused an increase both in the amplitude of the SP and in the threshold of ABR, a decrease in amplitude of the CAP and DPOAE. In addition, response alterations of the CAP and DPOAE showed in an intensity- and frequency-dependent manner, respectively. At levels of 20 -70dB nHL sound intensity, lmmol/L ATP caused a significant decrease in the CAP amplitude, while at moderate and high frequency ranges of 2 -8kHz it reduced DPOAE amplitude significantly. 330μmol/L ATP also increased the threshold of ABR. Conclusion ATP through perilymphatic perfusion could inhibit cochlear function of guinea pig.

  1. Electroacupuncture improves neuropathic pain Adenosine,adenosine 5'-triphosphate disodium and their receptors perhaps change simultaneously

    Institute of Scientific and Technical Information of China (English)

    Wen Ren; Wenzhan Tu; Songhe Jiang; Ruidong Cheng; Yaping Du

    2012-01-01

    Applying a stimulating current to acupoints through acupuncture needles-known as electroacupuncture-has the potential to produce analgesic effects in human subjects and experimental animals.When acupuncture was applied in a rat model,adenosine 5'-triphosphate disodium in the extracellular space was broken down into adenosine,which in turn inhibited pain transmission by means of an adenosine A1 receptor-dependent process.Direct injection of an adenosine A1 receptor agonist enhanced the analgesic effect of acupuncture.The analgesic effect of acupuncture appears to be mediated by activation of A1 receptors located on ascending nerves.In neuropathic pain,there is upregulation of P2X purinoceptor 3(P2X3)receptor expression in dorsal root ganglion neurons.Conversely,the onset of mechanical hyperalgesia was diminished and established hyperalgesia was significantly reversed when P2X3 receptor expression was downregulated.The pathways upon which electroacupuncture appear to act are interwoven with pain pathways,and electroacupuncture stimuli converge with impulses originating from painful areas.Electroacupuncture may act via purinergic A1 and P2X3 receptors simultaneously to induce an analgesic effect on neuropathic pain.

  2. Comparison of the novel vasodilator uridine triphosphate and adenosine for the measurement of fractional flow reserve

    DEFF Research Database (Denmark)

    Sivertsen, Jacob; Jensen, Jan Skov; Galatius, Søren;

    2014-01-01

    AIM: Examination of the fractional flow reserve (FFR) responses of intravenous (IV) adenosine with increasing doses of intracoronary (IC) adenosine versus IC uridine triphosphate (UTP) in patients with coronary artery disease. METHODS AND RESULTS: We measured FFR in 25 patients during continuous IV...... and IC infusion (using a microcatheter in the coronary ostium). Standard IV adenosine infusion (140 μg/kg/min) was compared to 8 equimolar incremental doses of IC UTP and IC adenosine (20, 40, 60, 80, 160, 240, 320 and 640 μg/min) in a randomized order. Across all doses, ΔFFR[IC UTP - IC adenosine......] was -0.038 ± 0.008, Pdose of IC UTP, FFR was significantly lower (FFR[IC UTP] = 0.62 ± 0.04) than during IV adenosine (FFR[IV adenosine] = 0.72 ± 0.05; P=.02) and IC adenosine (FFR[IC adenosine] = 0.68 ± 0.05; P=.03). Furthermore, UTP had significantly fewer side effects compared...

  3. Age-associated repression of type 1 inositol 1, 4, 5-triphosphate receptor impairs muscle regeneration

    Science.gov (United States)

    Lee, Bora; Lee, Seung-Min; Bahn, Young Jae; Lee, Kwang-Pyo; Kang, Moonkyung; Kim, Yeon-Soo; Woo, Sun-Hee; Lim, Jae-Young; Kim, Eunhee; Kwon, Ki-Sun

    2016-01-01

    Skeletal muscle mass and power decrease with age, leading to impairment of mobility and metabolism in the elderly. Ca2+ signaling is crucial for myoblast differentiation as well as muscle contraction through activation of transcription factors and Ca2+-dependent kinases and phosphatases. Ca2+ channels, such as dihydropyridine receptor (DHPR), two-pore channel (TPC) and inositol 1,4,5-triphosphate receptor (ITPR), function to maintain Ca2+ homeostasis in myoblasts. Here, we observed a significant decrease in expression of type 1 IP3 receptor (ITPR1), but not types 2 and 3, in aged mice skeletal muscle and isolated myoblasts, compared with those of young mice. ITPR1 knockdown using shRNA-expressing viruses in C2C12 myoblasts and tibialis anterior muscle of mice inhibited myotube formation and muscle regeneration after injury, respectively, a typical phenotype of aged muscle. This aging phenotype was associated with repression of muscle-specific genes and activation of the epidermal growth factor receptor (EGFR)-Ras-extracellular signal-regulated kinase (ERK) pathway. ERK inhibition by U0126 not only induced recovery of myotube formation in old myoblasts but also facilitated muscle regeneration after injury in aged muscle. The conserved decline in ITPR1 expression in aged human skeletal muscle suggests utility as a potential therapeutic target for sarcopenia, which can be treated using ERK inhibition strategies. PMID:27658230

  4. Bond cleavages of adenosine 5'-triphosphate induced by monochromatic soft X-rays

    International Nuclear Information System (INIS)

    To investigate which type of bond is likely to be cleaved by soft X-ray exposure to an adenosine 5'-triphosphate (ATP), we observed spectral changes in X-ray absorption near edge structure (XANES) around nitrogen and oxygen K-edge of an ATP film by soft X-ray irradiation. Experiments were performed at a synchrotron soft X-ray beamline at SPring-8, Japan. The XANES spectra around the nitrogen and oxygen .K-edge slightly varied by exposure to 560 eV soft X-rays. These changes are originated from the cleavage of C-N bonds between a sugar and a nucleobase site and of C-O, P-O or O-H bond of sugar and phosphate site. From the comparison between the change in XANES intensity of σ* peak at nitrogen and that at oxygen K-edges, it is inferred that the C-O, P-O or O-H bond of sugar and phosphate is much efficiently cleaved than the C-N of N-glycoside bond by the exposure of 560 eV soft X-ray to ATP film.

  5. Bacterial Hydrodynamics

    Science.gov (United States)

    Lauga, Eric

    2016-01-01

    Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells, yet they represent the bulk of the world's biomass and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micrometer scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically complex environments. Using hydrodynamics as an organizing framework, I review the biomechanics of bacterial motility and look ahead to future challenges.

  6. Bacterial hydrodynamics

    CERN Document Server

    Lauga, Eric

    2015-01-01

    Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells yet they represent the bulk of the world's biomass, and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds-number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micron scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically-complex environments. Using hydrodynamics as an organizing framework, we review the biomechanics of bacterial motility and look ahead to future challenges.

  7. Engineers win award for Swiss tunnel

    CERN Multimedia

    2003-01-01

    A Derby engineering consultancy has won the Tunnelling Industry Award 2003 for Excellence in Tunnel Design, offered by the British Tunnelling Society, for its work on the LHC in Geneva, Switzerland (1/2 page).

  8. Wind tunnel AVERT model

    Directory of Open Access Journals (Sweden)

    Adrian DOBRE

    2009-09-01

    Full Text Available The AVERT project aims to asses the oscillatory blowing on the flap for a high-lift configuration (wing with flap, and involves both experimental (low speed wind tunnel INCAS and numerical activities.At low speed the active flow control may lead to a reduction or elimination of the flow separation on the high-lift devices, such as flaps, and involves the introduction or re distribution of momentum within the boundary layer.High-lift systems utilized as particular profiles at a certain offset of the main wing may solve the disagreement between the requirements of cruise flight and landing, especially for low velocity take-off.

  9. HPLC–MS/MS method for the intracellular determination of ribavirin monophosphate and ribavirin triphosphate in CEMss cells

    OpenAIRE

    Meléndez, Margarita; Rosario, Osvaldo; Zayas, Beatriz; Rodríguez, José F.

    2009-01-01

    A sensitive and specific method using high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) for the determination of ribavirin monophosphate (RBV-MP) and ribavirin triphosphate (RBV-TP) in cells has been developed and validated. In this method, ribavirin phosphorylated metabolites were extracted and separated by anion exchange solid phase extraction (SPE). The RBV-MP and RBV-TP fractions were dephosphorylated using acid phosphatase and further purified by phenyl boronat...

  10. Diastolic Dysfunction Induced by a High-Fat Diet Is Associated with Mitochondrial Abnormality and Adenosine Triphosphate Levels in Rats

    OpenAIRE

    Kang, Ki-Woon; Kim, Ok-Soon; Chin, Jung Yeon; Kim, Won Ho; Park, Sang Hyun; Choi, Yu Jeong; Shin, Jong Ho; Jung, Kyung Tae; Lim, Do-Seon; Lee, Seong-Kyu

    2015-01-01

    Background Obesity is well-known as a risk factor for heart failure, including diastolic dysfunction. However, this mechanism in high-fat diet (HFD)-induced obese rats remain controversial. The purpose of this study was to investigate whether cardiac dysfunction develops when rats are fed with a HFD for 10 weeks; additionally, we sought to investigate the association between mitochondrial abnormalities, adenosine triphosphate (ATP) levels and cardiac dysfunction. Methods We examined myocardia...

  11. Assays To Detect the Formation of Triphosphates of Unnatural Nucleotides: Application to Escherichia coli Nucleoside Diphosphate Kinase.

    Science.gov (United States)

    Matsuura, Mariko F; Shaw, Ryan W; Moses, Jennifer D; Kim, Hyo-Joong; Kim, Myong-Jung; Kim, Myong-Sang; Hoshika, Shuichi; Karalkar, Nilesh; Benner, Steven A

    2016-03-18

    One frontier in synthetic biology seeks to move artificially expanded genetic information systems (AEGIS) into natural living cells and to arrange the metabolism of those cells to allow them to replicate plasmids built from these unnatural genetic systems. In addition to requiring polymerases that replicate AEGIS oligonucleotides, such cells require metabolic pathways that biosynthesize the triphosphates of AEGIS nucleosides, the substrates for those polymerases. Such pathways generally require nucleoside and nucleotide kinases to phosphorylate AEGIS nucleosides and nucleotides on the path to these triphosphates. Thus, constructing such pathways focuses on engineering natural nucleoside and nucleotide kinases, which often do not accept the unnatural AEGIS biosynthetic intermediates. This, in turn, requires assays that allow the enzyme engineer to follow the kinase reaction, assays that are easily confused by ATPase and other spurious activities that might arise through "site-directed damage" of the natural kinases being engineered. This article introduces three assays that can detect the formation of both natural and unnatural deoxyribonucleoside triphosphates, assessing their value as polymerase substrates at the same time as monitoring the progress of kinase engineering. Here, we focus on two complementary AEGIS nucleoside diphosphates, 6-amino-5-nitro-3-(1'-β-D-2'-deoxyribofuranosyl)-2(1H)-pyridone and 2-amino-8-(1'-β-D-2'-deoxyribofuranosyl)-imidazo[1,2-a]-1,3,5-triazin-4(8H)-one. These assays provide new ways to detect the formation of unnatural deoxyribonucleoside triphosphates in vitro and to confirm their incorporation into DNA. Thus, these assays can be used with other unnatural nucleotides. PMID:26829203

  12. A virtual detector approach to tunnel ionization and tunneling times

    CERN Document Server

    Teeny, Nicolas; Bauke, Heiko

    2016-01-01

    Tunneling times in atomic ionization is studied theoretically by a virtual detector approach. A virtual detector is a hypothetical device that allows to monitor the wave-function's density with spatial and temporal resolution during the ionization process. With this theoretical approach, it becomes possible to define unique moments when the electron enters and leaves with highest probability the classically forbidden region from first principles and a tunneling time can be specified unambiguously. It is shown that neither the moment when the electron enters the tunneling barrier nor when it leaves the tunneling barrier coincide with the moment when the external electric field reaches its maximum. Under the tunneling barrier as well as at the exit the electron has a nonzero velocity in electric field direction. This nonzero exit velocity has to be incorporated when the free motion of the electron is modeled by classical equations of motion.

  13. Tunnel face stability and ground settlement in pressurized shield tunnelling

    Institute of Scientific and Technical Information of China (English)

    苏艺; 汪国锋; 周庆宏

    2014-01-01

    An analysis of the stability of large-diameter circular tunnels and ground settlement during tunnelling by a pressurized shield was presented. An innovative three-dimensional translational multi-block failure mechanism was proposed to determine the face support pressure of large-shield tunnelling. Compared with the currently available mechanisms, the proposed mechanism has two unique features: (1) the supporting pressure applied to the tunnel face is assumed to have a non-uniform rather than uniform distribution, and (2) the method takes into account the entire circular excavation face instead of merely an inscribed ellipse. Based on the discrete element method, a numerical simulation of the Shanghai Yangtze River Tunnel was carried out using the Particle Flow Code in two dimensions. The immediate ground movement during excavation, as well as the behaviour of the excavation face, the shield movement, and the excavated area, was considered before modelling the excavation process.

  14. The Langley Wind Tunnel Enterprise

    Science.gov (United States)

    Paulson, John W., Jr.; Kumar, Ajay; Kegelman, Jerome T.

    1998-01-01

    After 4 years of existence, the Langley WTE is alive and growing. Significant improvements in the operation of wind tunnels have been demonstrated and substantial further improvements are expected when we are able to truly address and integrate all the processes affecting the wind tunnel testing cycle.

  15. Tunneling magnetic force microscopy

    Science.gov (United States)

    Burke, Edward R.; Gomez, Romel D.; Adly, Amr A.; Mayergoyz, Isaak D.

    1993-01-01

    We have developed a powerful new tool for studying the magnetic patterns on magnetic recording media. This was accomplished by modifying a conventional scanning tunneling microscope. The fine-wire probe that is used to image surface topography was replaced with a flexible magnetic probe. Images obtained with these probes reveal both the surface topography and the magnetic structure. We have made a thorough theoretical analysis of the interaction between the probe and the magnetic fields emanating from a typical recorded surface. Quantitative data about the constituent magnetic fields can then be obtained. We have employed these techniques in studies of two of the most important issues of magnetic record: data overwrite and maximizing data-density. These studies have shown: (1) overwritten data can be retrieved under certain conditions; and (2) improvements in data-density will require new magnetic materials. In the course of these studies we have developed new techniques to analyze magnetic fields of recorded media. These studies are both theoretical and experimental and combined with the use of our magnetic force scanning tunneling microscope should lead to further breakthroughs in the field of magnetic recording.

  16. Tunnel electroresistance through organic ferroelectrics

    Science.gov (United States)

    Tian, B. B.; Wang, J. L.; Fusil, S.; Liu, Y.; Zhao, X. L.; Sun, S.; Shen, H.; Lin, T.; Sun, J. L.; Duan, C. G.; Bibes, M.; Barthélémy, A.; Dkhil, B.; Garcia, V.; Meng, X. J.; Chu, J. H.

    2016-05-01

    Organic electronics is emerging for large-area applications such as photovoltaic cells, rollable displays or electronic paper. Its future development and integration will require a simple, low-power organic memory, that can be written, erased and readout electrically. Here we demonstrate a non-volatile memory in which the ferroelectric polarisation state of an organic tunnel barrier encodes the stored information and sets the readout tunnel current. We use high-sensitivity piezoresponse force microscopy to show that films as thin as one or two layers of ferroelectric poly(vinylidene fluoride) remain switchable with low voltages. Submicron junctions based on these films display tunnel electroresistance reaching 1,000% at room temperature that is driven by ferroelectric switching and explained by electrostatic effects in a direct tunnelling regime. Our findings provide a path to develop low-cost, large-scale arrays of organic ferroelectric tunnel junctions on silicon or flexible substrates.

  17. Carpal tunnel syndrome and acromegaly.

    Science.gov (United States)

    Baum, H; Lüdecke, D K; Herrmann, H D

    1986-01-01

    50 patients with acromegaly and carpal tunnel syndrome have been examined electrophysiologically before and after transnasal operation of the pituitary adenoma. 32 of the 50 patients (64%) had symptoms of carpal tunnel syndrome. 13 of them had neurological deficits. 28 of the examined patients had pathological neurographical findings only. About 1 week post-operatively DL was decreased in 43%; in 10 out of 13 patients with neurological deficits DL decreased. GH was normalized in 80% and reduced to 5-10 micrograms/l in a further 10%. The investigation did not show whether the carpal tunnel syndrome only depended on a GH increase or on other factors also such as e.g., on the duration of symptoms or tissue changes. None of the patients had the transversal carpal ligament operated on. The coincidence between acromegaly and carpal tunnel syndrome was 64%. In 3 cases the carpal tunnel syndrome was the leading sign to the diagnosis of acromegaly.

  18. Amperometric biosensor system for simultaneous determination of adenosine-5'-triphosphate and glucose.

    Science.gov (United States)

    Kucherenko, Ivan S; Didukh, Daria Yu; Soldatkin, Oleksandr O; Soldatkin, Alexei P

    2014-06-01

    The majority of biosensors for adenosine-5'-triphosphate (ATP) determination are based on cascades of enzymatic reactions; therefore, they are sensitive to glucose or glycerol (depending on the enzymatic system) as well as to ATP. The presence of unknown concentrations of these substances in the sample greatly complicates the determination of ATP. To overcome this disadvantage of known biosensors, we developed a biosensor system consisting of two biosensors: the first one is based on glucose oxidase and is intended for measuring glucose concentration, and the second one is based on glucose oxidase and hexokinase and is sensitive toward both glucose and ATP. Using glucose concentration measured by the first biosensor, we can analyze the total response to glucose and ATP obtained by the second biosensor. Platinum disc electrodes were used as amperometric transducers. The polyphenilenediamine membrane was deposited onto the surface of platinum electrodes to avoid the response to electroactive substances. The effect of glucose concentration on biosensor determination of ATP was studied. The reproducibility of biosensor responses to glucose and ATP during a day was tested (relative standard deviation, RSD, of responses to glucose was 3-6% and to ATP was 8-12%) as well as storage stability of the biosensors (no decrease of glucose responses and 43% drop of ATP responses during 50 days). The measurements of ATP and glucose in pharmaceutical vials (including mixtures of ATP and glucose) were carried out. It was shown that the developed biosensor system can be used for simultaneous analysis of glucose and ATP concentrations in water solutions. PMID:24810180

  19. Coxsackievirus cloverleaf RNA containing a 5' triphosphate triggers an antiviral response via RIG-I activation.

    Science.gov (United States)

    Feng, Qian; Langereis, Martijn A; Olagnier, David; Chiang, Cindy; van de Winkel, Roel; van Essen, Peter; Zoll, Jan; Hiscott, John; van Kuppeveld, Frank J M

    2014-01-01

    Upon viral infections, pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs) and stimulate an antiviral state associated with the production of type I interferons (IFNs) and inflammatory markers. Type I IFNs play crucial roles in innate antiviral responses by inducing expression of interferon-stimulated genes and by activating components of the adaptive immune system. Although pegylated IFNs have been used to treat hepatitis B and C virus infections for decades, they exert substantial side effects that limit their use. Current efforts are directed toward the use of PRR agonists as an alternative approach to elicit host antiviral responses in a manner similar to that achieved in a natural infection. RIG-I is a cytosolic PRR that recognizes 5' triphosphate (5'ppp)-containing RNA ligands. Due to its ubiquitous expression profile, induction of the RIG-I pathway provides a promising platform for the development of novel antiviral agents and vaccine adjuvants. In this study, we investigated whether structured RNA elements in the genome of coxsackievirus B3 (CVB3), a picornavirus that is recognized by MDA5 during infection, could activate RIG-I when supplied with 5'ppp. We show here that a 5'ppp-containing cloverleaf (CL) RNA structure is a potent RIG-I inducer that elicits an extensive antiviral response that includes induction of classical interferon-stimulated genes, as well as type III IFNs and proinflammatory cytokines and chemokines. In addition, we show that prophylactic treatment with CVB3 CL provides protection against various viral infections including dengue virus, vesicular stomatitis virus and enterovirus 71, demonstrating the antiviral efficacy of this RNA ligand. PMID:24759703

  20. Adenosine 5′-Triphosphate Flux Through the North Inlet Marsh System †

    Science.gov (United States)

    Chrzanowski, Thomas H.; Stevenson, L. Harold; Kjerfve, Bjorn

    1979-01-01

    The distribution, fluctuation, and short-term transport of total microbial biomass (measured as adenosine 5′-triphosphate [ATP]) was investigated in a large salt marsh creek. Hourly samples were collected synoptically for 25 h from 10 boats positioned across the 320-m width of the creek. Samples were collected from three depths ranging from 0.2 to 8.0 m. Hourly data obtained from each station were graphed, plotting depth against ATP. Subsequently, interpolated ATP values were generated for every one-tenth depth from the surface to the bottom with the use of an 11-point proportional divider. A total of 2,750 values were generated, and a mean value of 0.865 mg of ATP per m3 was determined. Maximum levels of ATP were found at high tide and minimal values were found at low tide. The distribution of ATP concentrations was found to be complex, with no suggestion of vertical stratification; however, horizontal divisions were apparent. ATP values corrected for direction of flow or velocity indicated two ebb-directed channels; however, when considered in total, there was a net import of ATP through the interface. The total import of ATP for this 25-h sampling period was calculated to be 3.58 kg, corresponding to a net transport of 39.8 mg of ATP per s through the cross section. Results suggest that detailed characterization of a creek transect in terms of ATP or any similar parameter requires the simultaneous measurements of both the concentration of the parameter in question and the velocity at the time and point from which the sample was taken. PMID:16345382

  1. CaMKII Regulation of Cardiac Ryanodine Receptors and Inositol Triphosphate Receptors

    Directory of Open Access Journals (Sweden)

    Emmanuel eCamors

    2014-05-01

    Full Text Available Ryanodine receptors (RyRs and inositol triphosphate receptors (InsP3Rs are structurally related intracellular calcium release channels that participate in multiple primary or secondary amplified Ca2+ signals, triggering muscle contraction and oscillatory Ca2+ waves, or activating transcription factors. In the heart, RyRs play an indisputable role in the process of excitation-contraction coupling as the main pathway for Ca2+ release from sarcoplasmic reticulum (SR, and a less prominent role in the process of excitation-transcription coupling. Conversely, InsP3Rs are believed to contribute in subtle ways, only, to contraction of the heart, and in more important ways to regulation of transcription factors. Because uncontrolled activity of either RyRs or InsP3Rs may elicit life-threatening arrhythmogenic and/or remodeling Ca2+ signals, regulation of their activity is of paramount importance for normal cardiac function. Due to their structural similarity, many regulatory factors, accessory proteins, and posttranslational processes are equivalent for RyRs and InsP3Rs. Here we discuss regulation of RyRs and InsP3Rs by CaMKII phosphorylation, but touch on other kinases whenever appropriate. CaMKII is emerging as a powerful modulator of RyR and InsP3R activity but interestingly, some of the complexities and controversies surrounding phosphorylation of RyRs also apply to InsP3Rs, and a clear-cut effect of CaMKII on either channel eludes investigators for now. Nevertheless, some effects of CaMKII on global cellular activity, such as SR Ca2+ leak or force-frequency potentiation, appear clear now, and this constrains the limits of the controversies and permits a more tractable approach to elucidate the effects of phosphorylation at the single channel level.

  2. Coxsackievirus cloverleaf RNA containing a 5' triphosphate triggers an antiviral response via RIG-I activation.

    Directory of Open Access Journals (Sweden)

    Qian Feng

    Full Text Available Upon viral infections, pattern recognition receptors (PRRs recognize pathogen-associated molecular patterns (PAMPs and stimulate an antiviral state associated with the production of type I interferons (IFNs and inflammatory markers. Type I IFNs play crucial roles in innate antiviral responses by inducing expression of interferon-stimulated genes and by activating components of the adaptive immune system. Although pegylated IFNs have been used to treat hepatitis B and C virus infections for decades, they exert substantial side effects that limit their use. Current efforts are directed toward the use of PRR agonists as an alternative approach to elicit host antiviral responses in a manner similar to that achieved in a natural infection. RIG-I is a cytosolic PRR that recognizes 5' triphosphate (5'ppp-containing RNA ligands. Due to its ubiquitous expression profile, induction of the RIG-I pathway provides a promising platform for the development of novel antiviral agents and vaccine adjuvants. In this study, we investigated whether structured RNA elements in the genome of coxsackievirus B3 (CVB3, a picornavirus that is recognized by MDA5 during infection, could activate RIG-I when supplied with 5'ppp. We show here that a 5'ppp-containing cloverleaf (CL RNA structure is a potent RIG-I inducer that elicits an extensive antiviral response that includes induction of classical interferon-stimulated genes, as well as type III IFNs and proinflammatory cytokines and chemokines. In addition, we show that prophylactic treatment with CVB3 CL provides protection against various viral infections including dengue virus, vesicular stomatitis virus and enterovirus 71, demonstrating the antiviral efficacy of this RNA ligand.

  3. Adenosine-5'-triphosphate release by Mannheimia haemolytica, lipopolysaccharide, and interleukin-1 stimulated bovine pulmonary epithelial cells.

    Science.gov (United States)

    Craddick, Michael; Patel, Rakhi; Lower, Amanda; Highlander, Sarah; Ackermann, Mark; McClenahan, David

    2012-09-15

    Mannheimia haemolytica, one of the agents associated with bovine respiratory disease complex, can cause severe lung pathology including the leakage of vascular products into the airways and alveoli. Previous work by this laboratory has demonstrated that bovine lung endothelial and epithelial cells undergo dramatic permeability increases when exposed to adenosine-5'-triphosphate (ATP). Therefore, we wanted to determine if ATP levels were elevated in bronchoalveolar lavage (BAL) samples from calves experimentally infected with M. haemolytica. In addition, cultured bovine pulmonary epithelial (BPE) cells were stimulated with heat-killed and live M. haemolytica bacteria, lipopolysaccharide (LPS), lipoteichoic acid (LTA), interleukin-1 (IL-1), and zymosan activated plasma (ZAP) to determine whether they might release extracellular ATP during in vitro infection. Calves experimentally exposed to M. haemolytica had an approximately 2-fold higher level of ATP in their BAL samples compared to control. BPE cells exposed to increasing numbers of heat-killed or live M. haemolytica had significantly increased levels of ATP release as compared to time-matched controls. Finally, BPE cells treated with several concentrations of LPS and IL-1 had increases in ATP release as compared to time-matched controls. This increase appeared to be a result of active ATP secretion by the cells, as cell viability was similar between treated and non-treated cells. Neither ZAP nor LTA induced any ATP release by the cells. In conclusion, ATP levels are elevated in lung secretions from calves infected with M. haemolytica. In addition, lung epithelial cells can actively release ATP when exposed to heat-killed or live M. haemolytica, LPS or IL-1. PMID:22771196

  4. Tunneling electroresistance effect in ferroelectric tunnel junctions at the nanoscale.

    Science.gov (United States)

    Gruverman, A; Wu, D; Lu, H; Wang, Y; Jang, H W; Folkman, C M; Zhuravlev, M Ye; Felker, D; Rzchowski, M; Eom, C-B; Tsymbal, E Y

    2009-10-01

    Using a set of scanning probe microscopy techniques, we demonstrate the reproducible tunneling electroresistance effect on nanometer-thick epitaxial BaTiO(3) single-crystalline thin films on SrRuO(3) bottom electrodes. Correlation between ferroelectric and electronic transport properties is established by direct nanoscale visualization and control of polarization and tunneling current. The obtained results show a change in resistance by about 2 orders of magnitude upon polarization reversal on a lateral scale of 20 nm at room temperature. These results are promising for employing ferroelectric tunnel junctions in nonvolatile memory and logic devices. PMID:19697939

  5. Tunneling times with covariant measurements

    CERN Document Server

    Kiukas, J; Werner, R F; 10.1007/s10701-009-9275-z

    2009-01-01

    We consider the time delay of massive, non-relativistic, one-dimensional particles due to a tunneling potential. In this setting the well-known Hartman effect asserts that often the sub-ensemble of particles going through the tunnel seems to cross the tunnel region instantaneously. An obstacle to the utilization of this effect for getting faster signals is the exponential damping by the tunnel, so there seems to be a trade-off between speedup and intensity. In this paper we prove that this trade-off is never in favor of faster signals: the probability for a signal to reach its destination before some deadline is always reduced by the tunnel, for arbitrary incoming states, arbitrary positive and compactly supported tunnel potentials, and arbitrary detectors. More specifically, we show this for several different ways to define ``the same incoming state'' and ''the same detector'' when comparing the settings with and without tunnel potential. The arrival time measurements are expressed in the time-covariant appr...

  6. Sensitive, Rapid Detection of Bacterial Spores

    Science.gov (United States)

    Kern, Roger G.; Venkateswaran, Kasthuri; Chen, Fei; Pickett, Molly; Matsuyama, Asahi

    2009-01-01

    A method of sensitive detection of bacterial spores within delays of no more than a few hours has been developed to provide an alternative to a prior three-day NASA standard culture-based assay. A capability for relatively rapid detection of bacterial spores would be beneficial for many endeavors, a few examples being agriculture, medicine, public health, defense against biowarfare, water supply, sanitation, hygiene, and the food-packaging and medical-equipment industries. The method involves the use of a commercial rapid microbial detection system (RMDS) that utilizes a combination of membrane filtration, adenosine triphosphate (ATP) bioluminescence chemistry, and analysis of luminescence images detected by a charge-coupled-device camera. This RMDS has been demonstrated to be highly sensitive in enumerating microbes (it can detect as little as one colony-forming unit per sample) and has been found to yield data in excellent correlation with those of culture-based methods. What makes the present method necessary is that the specific RMDS and the original protocols for its use are not designed for discriminating between bacterial spores and other microbes. In this method, a heat-shock procedure is added prior to an incubation procedure that is specified in the original RMDS protocols. In this heat-shock procedure (which was also described in a prior NASA Tech Briefs article on enumerating sporeforming bacteria), a sample is exposed to a temperature of 80 C for 15 minutes. Spores can survive the heat shock, but nonspore- forming bacteria and spore-forming bacteria that are not in spore form cannot survive. Therefore, any colonies that grow during incubation after the heat shock are deemed to have originated as spores.

  7. Dynamical tunneling theory and experiment

    CERN Document Server

    Keshavamurthy, Srihari

    2011-01-01

    A prominent aspect of quantum theory, tunneling arises in a variety of contexts across several fields of study, including nuclear, atomic, molecular, and optical physics and has led to technologically relevant applications in mesoscopic science. Exploring mechanisms and consequences, Dynamical Tunneling: Theory and Experiment presents the work of international experts who discuss the considerable progress that has been achieved in this arena in the past two decades.Highlights in this volume include:A historical introduction and overview of dynamical tunneling, with case histories ranging from

  8. Tunneling inhibition for subwavelength light

    CERN Document Server

    Huang, Changming; Ye, Fangwei; Kartashov, Yaroslav V; Chen, Xianfeng; Torner, Lluis

    2013-01-01

    We show that light tunneling inhibition may take place in suitable dynamically modulated waveguide arrays for light spots whose features are remarkably smaller than the wavelength of light. We found that tunneling between neighboring waveguides can be suppressed for specific frequencies of the out-of-phase refractive index modulation, affording undistorted propagation of the input subwavelength light spots over hundreds of Rayleigh lengths. Tunneling inhibition turns out to be effective only when the waveguide separation in the array is above a critical threshold. Inclusion of a weak focusing nonlinearity is shown to improve localization. We analyze the phenomenon in purely dielectric structures and also in arrays containing periodically spaced metallic layers.

  9. Tunneling Ionization of Diatomic Molecules

    DEFF Research Database (Denmark)

    Svensmark, Jens Søren Sieg

    2016-01-01

    When a molecule is subject to a strong laser field, there is a probability that an electron can escape, even though the electrons are bound by a large potential barrier. This is possible because electrons are quantum mechanical in nature, and they are therefore able to tunnel through potential...... of tunneling ionizaion of molecules is presented and the results of numerical calculations are shown. One perhaps surprising result is, that the frequently used Born-Oppenheimer approximation breaks down for weak fields when describing tunneling ionization. An analytic theory applicable in the weak-field limit...

  10. Predicting Tunneling-Induced Ground Movement

    OpenAIRE

    Laefer, Debra F.; Kim, Wan

    2004-01-01

    Cost-effective and permissible tunneling can occur only if ground movement prediction is refined to accommodate changes in both the urban environment and tunneling technology. As cities age, tunnels are being installed closer to existing structures and in increasingly complicated belowground conditions. The reality of stacked tunnels, abandoned facilities, and more extensive use of underground space raises the question of whether relationships derived for single open-shield tunnels in free-fi...

  11. FUNDAMENTAL TUNNELING PROCESSES IN MOSa SOLAR CELLS

    OpenAIRE

    Balberg, I.; Hanak, J.; Weakliem, H.; Gal, E.

    1981-01-01

    In previous studies of tunneling through a MOSa tunnel junction, where Sa was a-Si : H, it was shown that their characteristics resemble those of MOSc devices where Sc was crystalline silicon. In the present work we would like to report a demonstration of fundamental tunneling processes in such tunnel junctions. In particular, the transition from semiconductor controlled regime to tunneling controlled regime can be clearly distinguished. The present results represent one of the rare cases whe...

  12. Analytic Solutions of Elastic Tunneling Problems

    OpenAIRE

    Strack, O.E.

    2002-01-01

    The complex variable method for solving two dimensional linearly elastic problems is used to obtain several fundamental analytical solutions of tunneling problems. The method is used to derive the general mathematical representation of problems involving resultant forces on holes in a half-plane. Such problems are encountered in geomechanics during the excavation of tunnels. When tunnels are excavated the removal of the weighted material inside the tunnel causes the ground under the tunnel to...

  13. Flatback airfoil wind tunnel experiment.

    Energy Technology Data Exchange (ETDEWEB)

    Mayda, Edward A. (University of California, Davis, CA); van Dam, C.P. (University of California, Davis, CA); Chao, David D. (University of California, Davis, CA); Berg, Dale E.

    2008-04-01

    A computational fluid dynamics study of thick wind turbine section shapes in the test section of the UC Davis wind tunnel at a chord Reynolds number of one million is presented. The goals of this study are to validate standard wind tunnel wall corrections for high solid blockage conditions and to reaffirm the favorable effect of a blunt trailing edge or flatback on the performance characteristics of a representative thick airfoil shape prior to building the wind tunnel models and conducting the experiment. The numerical simulations prove the standard wind tunnel corrections to be largely valid for the proposed test of 40% maximum thickness to chord ratio airfoils at a solid blockage ratio of 10%. Comparison of the computed lift characteristics of a sharp trailing edge baseline airfoil and derived flatback airfoils reaffirms the earlier observed trend of reduced sensitivity to surface contamination with increasing trailing edge thickness.

  14. Free Surface Water Tunnel (FSWT)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: The Free Surface Water Tunnel consists of the intake plenum, the test section and the exit plenum. The intake plenum starts with a perforated pipe that...

  15. Self-Organizing Tunnel Peers

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Tunneling is an important approach in IPv6 transition techniques. The tunnel broker model provides a way to build virtual IPv6 networks without manual configuration.However, neither it adapts performance variation on the IPv4 infrastructure,nor it is a scalable solution for a wide-area IPv6 networking environment. In this paper, a self-organizing tunnel peer (SOTP)model is presented. Tunnel peers are clustered in the SOTP system so that optimization is scalable. Four primitive operations related to cluster construction - arrest,release,division and death - endow the system with the nature of self-organization.Occurrence and behavior of the operations are decided by criteria on the IPv4 end-to-end performance; hence measurement is an indispensable component of the system. The metabolism of cluster relaxes the requirement to accuracy of measurement and optimization.

  16. Probing the ATP Site of GRP78 with Nucleotide Triphosphate Analogs.

    Directory of Open Access Journals (Sweden)

    Scott J Hughes

    Full Text Available GRP78, a member of the ER stress protein family, can relocate to the surface of cancer cells, playing key roles in promoting cell proliferation and metastasis. GRP78 consists of two major functional domains: the ATPase and protein/peptide-binding domains. The protein/peptide-binding domain of cell-surface GRP78 has served as a novel functional receptor for delivering cytotoxic agents (e.g., a apoptosis-inducing peptide or taxol across the cell membrane. Here, we report our study on the ATPase domain of GRP78 (GRP78ATPase, whose potential as a transmembrane delivery system of cytotoxic agents (e.g., ATP-based nucleotide triphosphate analogs remains unexploited. As the binding of ligands (ATP analogs to a receptor (GRP78ATPase is a pre-requisite for internalization, we determined the binding affinities and modes of GRP78ATPase for ADP, ATP and several ATP analogs using surface plasmon resonance and x-ray crystallography. The tested ATP analogs contain one of the following modifications: the nitrogen at the adenine ring 7-position to a carbon atom (7-deazaATP, the oxygen at the β-γ bridge position to a carbon atom (AMPPCP, or the removal of the 2'-OH group (2'-deoxyATP. We found that 7-deazaATP displays an affinity and a binding mode that resemble those of ATP regardless of magnesium ion (Mg++ concentration, suggesting that GRP78 is tolerant to modifications at the 7-position. By comparison, AMPPCP's binding affinity was lower than ATP and Mg++-dependent, as the removal of Mg++ nearly abolished binding to GRP78ATPase. The AMPPCP-Mg++ structure showed evidence for the critical role of Mg++ in AMPPCP binding affinity, suggesting that while GRP78 is sensitive to modifications at the β-γ bridge position, these can be tolerated in the presence of Mg++. Furthermore, 2'-deoxyATP's binding affinity was significantly lower than those for all other nucleotides tested, even in the presence of Mg++. The 2'-deoxyATP structure showed the conformation of the

  17. Probing the ATP Site of GRP78 with Nucleotide Triphosphate Analogs.

    Science.gov (United States)

    Hughes, Scott J; Antoshchenko, Tetyana; Chen, Yun; Lu, Hua; Pizarro, Juan C; Park, Hee-Won

    2016-01-01

    GRP78, a member of the ER stress protein family, can relocate to the surface of cancer cells, playing key roles in promoting cell proliferation and metastasis. GRP78 consists of two major functional domains: the ATPase and protein/peptide-binding domains. The protein/peptide-binding domain of cell-surface GRP78 has served as a novel functional receptor for delivering cytotoxic agents (e.g., a apoptosis-inducing peptide or taxol) across the cell membrane. Here, we report our study on the ATPase domain of GRP78 (GRP78ATPase), whose potential as a transmembrane delivery system of cytotoxic agents (e.g., ATP-based nucleotide triphosphate analogs) remains unexploited. As the binding of ligands (ATP analogs) to a receptor (GRP78ATPase) is a pre-requisite for internalization, we determined the binding affinities and modes of GRP78ATPase for ADP, ATP and several ATP analogs using surface plasmon resonance and x-ray crystallography. The tested ATP analogs contain one of the following modifications: the nitrogen at the adenine ring 7-position to a carbon atom (7-deazaATP), the oxygen at the β-γ bridge position to a carbon atom (AMPPCP), or the removal of the 2'-OH group (2'-deoxyATP). We found that 7-deazaATP displays an affinity and a binding mode that resemble those of ATP regardless of magnesium ion (Mg++) concentration, suggesting that GRP78 is tolerant to modifications at the 7-position. By comparison, AMPPCP's binding affinity was lower than ATP and Mg++-dependent, as the removal of Mg++ nearly abolished binding to GRP78ATPase. The AMPPCP-Mg++ structure showed evidence for the critical role of Mg++ in AMPPCP binding affinity, suggesting that while GRP78 is sensitive to modifications at the β-γ bridge position, these can be tolerated in the presence of Mg++. Furthermore, 2'-deoxyATP's binding affinity was significantly lower than those for all other nucleotides tested, even in the presence of Mg++. The 2'-deoxyATP structure showed the conformation of the bound

  18. Molecular structure of tetraaqua adenosine 5'-triphosphate aluminium(III) complex: A study involving Raman spectroscopy, theoretical DFT and potentiometry

    Science.gov (United States)

    Tenório, Thaís; Silva, Andréa M.; Ramos, Joanna Maria; Buarque, Camilla D.; Felcman, Judith

    2013-03-01

    The Alzheimer's disease is one of the most common neurodegenerative diseases that affect elderly population, due to the formation of β-amyloid protein aggregate and several symptoms, especially progressive cognitive decline. The result is a decrease in capture of glucose by cells leading to obliteration, meddling in the Krebs cycle, the principal biochemical route to the energy production leading to a decline in the levels of adenosine 5'-triphosphate. Aluminium(III) is connected to Alzheimer's and its ion provides raise fluidity of the plasma membrane, decrease cell viability and aggregation of amyloid plaques. Studies reveal that AlATP complex promotes the formation of reactive fibrils of β-amyloid protein and independent amyloidogenic peptides, suggesting the action of the complex as a chaperone in the role pathogenic process. In this research, one of complexes formed by Al(III) and adenosine 5'-triphosphate in aqueous solution is analyzed by potentiometry, Raman spectroscopy and ab initio calculations. The value of the log KAlATP found was 9.21 ± 0.01 and adenosine 5'-triphosphate should act as a bidentate ligand in the complex. Raman spectroscopy and potentiometry indicate that donor atoms are the oxygen of the phosphate β and the oxygen of the phosphate γ, the terminal phosphates. Computational calculations using Density Functional Theory, with hybrid functions B3LYP and 6-311++G(d,p) basis set regarding water solvent effects, have confirmed the results. Frontier molecular orbitals, electrostatic potential contour surface, electrostatic potential mapped and Mulliken charges of the title molecule were also investigated.

  19. Molecular structure of tetraaqua adenosine 5'-triphosphate aluminium(III) complex: a study involving Raman spectroscopy, theoretical DFT and potentiometry.

    Science.gov (United States)

    Tenório, Thaís; Silva, Andréa M; Ramos, Joanna Maria; Buarque, Camilla D; Felcman, Judith

    2013-03-15

    The Alzheimer's disease is one of the most common neurodegenerative diseases that affect elderly population, due to the formation of β-amyloid protein aggregate and several symptoms, especially progressive cognitive decline. The result is a decrease in capture of glucose by cells leading to obliteration, meddling in the Krebs cycle, the principal biochemical route to the energy production leading to a decline in the levels of adenosine 5'-triphosphate. Aluminium(III) is connected to Alzheimer's and its ion provides raise fluidity of the plasma membrane, decrease cell viability and aggregation of amyloid plaques. Studies reveal that AlATP complex promotes the formation of reactive fibrils of β-amyloid protein and independent amyloidogenic peptides, suggesting the action of the complex as a chaperone in the role pathogenic process. In this research, one of complexes formed by Al(III) and adenosine 5'-triphosphate in aqueous solution is analyzed by potentiometry, Raman spectroscopy and ab initio calculations. The value of the logK(AlATP) found was 9.21±0.01 and adenosine 5'-triphosphate should act as a bidentate ligand in the complex. Raman spectroscopy and potentiometry indicate that donor atoms are the oxygen of the phosphate β and the oxygen of the phosphate γ, the terminal phosphates. Computational calculations using Density Functional Theory, with hybrid functions B3LYP and 6-311++G(d,p) basis set regarding water solvent effects, have confirmed the results. Frontier molecular orbitals, electrostatic potential contour surface, electrostatic potential mapped and Mulliken charges of the title molecule were also investigated.

  20. Wildlife Tunnel Enhances Population Viability

    OpenAIRE

    Michael McCarthy; Dean Heinze; Rodney van der Ree; Ian Mansergh

    2009-01-01

    Roads and traffic are pervasive components of landscapes throughout the world: they cause wildlife mortality, disrupt animal movements, and increase the risk of extinction. Expensive engineering solutions, such as overpasses and tunnels, are increasingly being adopted to mitigate these effects. Although some species readily use such structures, their success in preventing population extinction remains unknown. Here, we use population viability modeling to assess the effectiveness of tunnels f...

  1. Enzymatic Recognition of 2′‐Modified Ribonucleoside 5′‐Triphosphates: Towards the Evolution of Versatile Aptamers

    DEFF Research Database (Denmark)

    Lauridsen, Lasse Holm; Rothnagel, Joseph A.; Veedu, Rakesh N.

    2012-01-01

    The quest for effective, selective and nontoxic nucleic‐acid‐based drugs has led to designing modifications of naturally occurring nucleosides. A number of modified nucleic acids have been made in the past decades in the hope that they would prove useful in target‐validation studies and therapeutic...... of aptamers containing naturally occurring nucleotides, chemically modified nucleotides have to be used. In order to apply modified nucleotides in aptamer drug development, their enzyme‐recognition capabilities must be understood. For this purpose, several modified nucleoside 5′‐triphosphates were synthesized...

  2. Cross-linked polymeric nanogel formulations of 5'-triphosphates of nucleoside analogues: role of the cellular membrane in drug release.

    Science.gov (United States)

    Vinogradov, Serguei V; Kohli, Ekta; Zeman, Arin D

    2005-01-01

    Activation of cytotoxic nucleoside analogues in vivo depends primarily on their cell-specific phosphorylation. Anticancer chemotherapy using nucleoside analogues may be significantly enhanced by intracellular administration of active phosphorylated drugs. However, the cellular transport of anionic compounds is very ineffective and restricted by many drug efflux transporters. Recently developed cationic nanogel carriers can encapsulate large amounts of nucleoside 5'-triphosphates that form polyionic complexes with protonated amino groups on the polyethylenimine backbone of the nanogels. In this paper, the 5'-triphosphate of an antiviral nucleoside analogue, 3'-azido-2',3'-dideoxythymidine (AZT), was efficiently synthesized and its complexes with nanogels were obtained and evaluated as potential cytotoxic drug formulations for treatment of human breast carcinoma cells. A selective phosphorylating reagent, tris-imidazolylphosphate, was used to convert AZT into the nucleoside analogue 5'-triphosphate using a one-pot procedure. The corresponding 3'-azido-2',3'-dideoxythymidine 5'-triphosphate (AZTTP) was isolated with high yield (75%). Nanogels encapsulated up to 30% of AZTTP by weight by mixing solutions of the carrier and the drug. The AZTTP/nanogel formulation showed enhanced cytotoxicity in two breast cancer cell lines, MCF-7 and MDA-MB-231, demonstrating IC50 values 130-200 times lower than those values for AZT alone. The exact mechanism of drug release from nanogels remains unclear. One mechanism could involve interaction with negatively charged counterions. A high affinity of nanogels to isolated cellular membranes has been observed, especially for nanogels made of amphiphilic block copolymer, Pluronic P85. Cellular trafficking of nanogel particles, contrasted by polyethylenimine-coordinated copper(II) ions, was studied by transmission electron microscopy (TEM), which revealed membranotropic properties of nanogels. A substantial release of encapsulated drug was

  3. Scanning Tunneling Optical Resonance Microscopy

    Science.gov (United States)

    Bailey, Sheila; Wilt, Dave; Raffaelle, Ryne; Gennett, Tom; Tin, Padetha; Lau, Janice; Castro, Stephanie; Jenkins, Philip; Scheiman, Dave

    2003-01-01

    Scanning tunneling optical resonance microscopy (STORM) is a method, now undergoing development, for measuring optoelectronic properties of materials and devices on the nanoscale by means of a combination of (1) traditional scanning tunneling microscopy (STM) with (2) tunable laser spectroscopy. In STORM, an STM tip probing a semiconductor is illuminated with modulated light at a wavelength in the visible-to-near-infrared range and the resulting photoenhancement of the tunneling current is measured as a function of the illuminating wavelength. The photoenhancement of tunneling current occurs when the laser photon energy is sufficient to excite charge carriers into the conduction band of the semiconductor. Figure 1 schematically depicts a proposed STORM apparatus. The light for illuminating the semiconductor specimen at the STM would be generated by a ring laser that would be tunable across the wavelength range of interest. The laser beam would be chopped by an achromatic liquid-crystal modulator. A polarization-maintaining optical fiber would couple the light to the tip/sample junction of a commercial STM. An STM can be operated in one of two modes: constant height or constant current. A STORM apparatus would be operated in the constant-current mode, in which the height of the tip relative to the specimen would be varied in order to keep the tunneling current constant. In this mode, a feedback control circuit adjusts the voltage applied to a piezoelectric actuator in the STM that adjusts the height of the STM tip to keep the tunneling current constant. The exponential relationship between the tunneling current and tip-to-sample distance makes it relatively easy to implement this mode of operation. The choice of method by which the photoenhanced portion of the tunneling current would be measured depends on choice of the frequency at which the input illumination would be modulated (chopped). If the frequency of modulation were low enough (typically < 10 Hz) that the

  4. Submucosal tunneling techniques: current perspectives

    Directory of Open Access Journals (Sweden)

    Kobara H

    2014-04-01

    Full Text Available Hideki Kobara,1 Hirohito Mori,1 Kazi Rafiq,2 Shintaro Fujihara,1 Noriko Nishiyama,1 Maki Ayaki,1 Tatsuo Yachida,1 Tae Matsunaga,1 Johji Tani,1 Hisaaki Miyoshi,1 Hirohito Yoneyama,1 Asahiro Morishita,1 Makoto Oryu,1 Hisakazu Iwama,3 Tsutomu Masaki1 1Department of Gastroenterology and Neurology, 2Department of Pharmacology, 3Life Science Research Center, Faculty of Medicine, Kagawa University, Miki-cho, Kita-Gun, Kagawa, Japan Abstract: Advances in endoscopic submucosal dissection include a submucosal tunneling technique, involving the introduction of tunnels into the submucosa. These tunnels permit safer offset entry into the peritoneal cavity for natural orifice transluminal endoscopic surgery. Technical advantages include the visual identification of the layers of the gut, blood vessels, and subepithelial tumors. The creation of a mucosal flap that minimizes air and fluid leakage into the extraluminal cavity can enhance the safety and efficacy of surgery. This submucosal tunneling technique was adapted for esophageal myotomy, culminating in its application to patients with achalasia. This method, known as per oral endoscopic myotomy, has opened up the new discipline of submucosal endoscopic surgery. Other clinical applications of the submucosal tunneling technique include its use in the removal of gastrointestinal subepithelial tumors and endomicroscopy for the diagnosis of functional and motility disorders. This review suggests that the submucosal tunneling technique, involving a mucosal safety flap, can have potential values for future endoscopic developments. Keywords: submucosal endoscopy, submucosal tunneling method, natural orifice transluminal endoscopic surgery, peroral endoscopic myotomy, gastrointestinal subepithelial tumor, functional and motility disorders

  5. Characterization of nucleoside triphosphate diphosphohydrolase activity in Trichomonas gallinae and the influence of penicillin and streptomycin in extracellular nucleotide hydrolysis.

    Science.gov (United States)

    Borges, Fernanda Pires; de Brum Vieira, Patrícia; Wiltuschnig, Renata C M; Tasca, Tiana; De Carli, Geraldo Attilio; Bonan, Carla Denise

    2008-06-01

    Here we described an nucleoside triphosphate diphosphohydrolase (NTPDase) activity in living trophozoites of Trichomonas gallinae. The enzyme hydrolyzes a variety of purine and pyrimidine nucleoside di- and triphosphates in an optimum pH range of 6.0-8.0. This enzyme activity was activated by high concentrations of divalent cations, such as calcium and magnesium. Contaminant activities were ruled out because the enzyme was not inhibited by classical inhibitors of ATPases (ouabain, 5.0 mM sodium azide, oligomycin) and alkaline phosphatases (levamisole). A significant inhibition of ATP hydrolysis (38%) was observed in the presence of 20 mM sodium azide. Sodium orthovanadate inhibited ATP and ADP hydrolysis (24% and 78%), respectively. The apparent K(M) (Michaelis constant) values were 667.62+/-13 microM for ATP and 125+/-5.3 microM for ADP. V(max) (maximum velocity) values were 0.44+/-0.007 nmol Pi min(-1) per 10(6) trichomonads and 0.91+/-0.12 nmol Pi min(-1) per 10(6) trichomonads for ATP and ADP, respectively. Moreover, we showed a marked decrease in ATP, ADP and AMP hydrolysis when the parasites were grown in the presence of penicillin and streptomycin. The existence of an NTPDase activity in T. gallinae may be involved in pathogenicity, protecting the parasite from the cytolytic effects of the extracellular nucleotides. PMID:18422631

  6. Ecto-nucleoside triphosphate diphosphohydrolase 2 modulates local ATP-induced calcium signaling in human HaCaT keratinocytes.

    Directory of Open Access Journals (Sweden)

    Chia-Lin Ho

    Full Text Available Keratinocytes are the major building blocks of the human epidermis. In many physiological and pathophysiological conditions, keratinocytes release adenosine triphosphate (ATP as an autocrine/paracrine mediator that regulates cell proliferation, differentiation, and migration. ATP receptors have been identified in various epidermal cell types; therefore, extracellular ATP homeostasis likely determines its long-term, trophic effects on skin health. We investigated the possibility that human keratinocytes express surface-located enzymes that modulate ATP concentration, as well as the corresponding receptor activation, in the pericellular microenvironment. We observed that the human keratinocyte cell line HaCaT released ATP and hydrolyzed extracellular ATP. Interestingly, ATP hydrolysis resulted in adenosine diphosphate (ADP accumulation in the extracellular space. Pharmacological inhibition by ARL 67156 or gene silencing of the endogenous ecto-nucleoside triphosphate diphosphohydrolase (NTPDase isoform 2 resulted in a 25% reduction in both ATP hydrolysis and ADP formation. Using intracellular calcium as a reporter, we found that although NTPDase2 hydrolyzed ATP and generated sustainable ADP levels, only ATP contributed to increased intracellular calcium via P2Y2 receptor activation. Furthermore, knocking down NTPDase2 potentiated the nanomolar ATP-induced intracellular calcium increase, suggesting that NTPDase2 globally attenuates nucleotide concentration in the pericellular microenvironment as well as locally shields receptors in the vicinity from being activated by extracellular ATP. Our findings reveal an important role of human keratinocyte NTPDase2 in modulating nucleotide signaling in the extracellular milieu of human epidermis.

  7. Crystallization and preliminary X-ray structural analysis of nucleoside triphosphate hydrolases from Neospora caninum and Toxoplasma gondii

    International Nuclear Information System (INIS)

    Recombinant nucleoside triphosphate hydrolases from N. caninum and T. gondii have been purified and crystallized for X-ray structure analysis. The nucleoside triphosphate hydrolases that are produced by Neospora caninum (NcNTPase) and Toxoplasma gondii (TgNTPase-I) have a different physiological function from the ubiquitous ecto-ATPases. The recombinant enzymes were crystallized at 293 K using polyethylene glycol 3350 as a precipitant and X-ray diffraction data sets were collected for NcNTPase (to 2.8 Å resolution) and TgNTPase-I (to 3.1 Å resolution) at 100 K using synchrotron radiation. The crystals of NcNTPase and TgNTPase-I belonged to the orthorhombic space group I222 (unit-cell parameters a = 93.6, b = 140.8, c = 301.1 Å) and the monoclinic space group P21 (unit-cell parameters a = 87.1, b = 123.5, c = 120.2 Å, β = 96.6°), respectively, with two NcNTPase (VM = 3.7 Å3 Da−1) and four TgNTPase-I (VM = 2.7 Å3 Da−1) molecules per asymmetric unit. SAD phasing trials using a data set (λ = 0.97904 Å) collected from a crystal of selenomethionylated NcNTPase gave an initial electron-density map of sufficient quality to build a molecular model of NcNTPase

  8. National Wind Tunnel Complex (NWTC)

    Science.gov (United States)

    1996-01-01

    The National Wind Tunnel Complex (NWTC) Final Report summarizes the work carried out by a unique Government/Industry partnership during the period of June 1994 through May 1996. The objective of this partnership was to plan, design, build and activate 'world class' wind tunnel facilities for the development of future-generation commercial and military aircraft. The basis of this effort was a set of performance goals defined by the National Facilities Study (NFS) Task Group on Aeronautical Research and Development Facilities which established two critical measures of improved wind tunnel performance; namely, higher Reynolds number capability and greater productivity. Initial activities focused upon two high-performance tunnels (low-speed and transonic). This effort was later descoped to a single multipurpose tunnel. Beginning in June 1994, the NWTC Project Office defined specific performance requirements, planned site evaluation activities, performed a series of technical/cost trade studies, and completed preliminary engineering to support a proposed conceptual design. Due to budget uncertainties within the Federal government, the NWTC project office was directed to conduct an orderly closure following the Systems Design Review in March 1996. This report provides a top-level status of the project at that time. Additional details of all work performed have been archived and are available for future reference.

  9. Prevention of bacterial adhesion

    DEFF Research Database (Denmark)

    Klemm, Per; Vejborg, Rebecca Munk; Hancock, Viktoria

    2010-01-01

    Management of bacterial infections is becoming increasingly difficult due to the emergence and increasing prevalence of bacterial pathogens that are resistant to available antibiotics. Conventional antibiotics generally kill bacteria by interfering with vital cellular functions, an approach that ...

  10. TunnelVision: LHC Tunnel Photogrammetry System for Structural Monitoring

    CERN Document Server

    Fallas, William

    2014-01-01

    In this document an algorithm to detect deformations in the LHC Tunnel of CERN is presented. It is based on two images, one represents the ideal state of the tunnel and the other one the actual state. To find the differences between both, the algorithm is divided in three steps. First, an image enhancement is applied to make easier the detection. Second, two different approaches to reduce noise are applied to one or both images. And third, it is defined a group of characteristics about the type of deformation desired to detect. Finally, the conclusions show the effectiveness of the algorithm in the experimental results.

  11. Other Cryogenic Wind Tunnel Projects

    Science.gov (United States)

    Kilgore, Robert A.

    1997-01-01

    The first cryogenic tunnel was built at the NASA Langley Research Center in 1972. Since then, many cryogenic wind-tunnels have been built at aeronautical research centers around the world. In this lecture some of the more interesting and significant of these projects that have not been covered by other lecturers at this Special Course are described. In this lecture authors describe cryogenic wind-tunnel projects at research centers in four countries: China (Chinese Aeronautical Research and Development Center); England (College of Aeronautics at Cranfield, and Defence Research Agency - Bedford); Japan (National Aerospace Laboratory, University of Tsukuba, and National Defense Academy); and United States (Douglas Aircraft Co., University of Illinois at Urbana-Champaign, and NASA Langley).

  12. Fermion Tunneling from Dynamical Horizons

    CERN Document Server

    Di Criscienzo, Roberto

    2008-01-01

    The instability against emission of fermionic particles by the trapping horizon of an evolving black hole is analyzed using the Hamilton-Jacobi tunneling method. This method automatically selects one special expression for the surface gravity of a changing horizon. The results also apply to point masses embedded in an expanding universe. As a bonus of the tunneling method, we gain the insight that the surface gravity still defines a temperature parameter as long as the evolution is sufficiently slow that the black hole pass through a sequence of quasi-equilibrium states, and that black holes should be semi-classically unstable even in a hypothetical world without bosonic fields.

  13. Spin tunnelling in mesoscopic systems

    Indian Academy of Sciences (India)

    Anupam Garg

    2001-02-01

    We study spin tunnelling in molecular magnets as an instance of a mesoscopic phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel splitting between various pairs of Zeeman levels in this molecule oscillates as a function of applied magnetic field, vanishing completely at special points in the space of magnetic fields, known as diabolical points. This phenomena is explained in terms of two approaches, one based on spin-coherent-state path integrals, and the other on a generalization of the phase integral (or WKB) method to difference equations. Explicit formulas for the diabolical points are obtained for a model Hamiltonian.

  14. Tunneling field effect transistor technology

    CERN Document Server

    Chan, Mansun

    2016-01-01

    This book provides a single-source reference to the state-of-the art in tunneling field effect transistors (TFETs). Readers will learn the TFETs physics from advanced atomistic simulations, the TFETs fabrication process and the important roles that TFETs will play in enabling integrated circuit designs for power efficiency. · Provides comprehensive reference to tunneling field effect transistors (TFETs); · Covers all aspects of TFETs, from device process to modeling and applications; · Enables design of power-efficient integrated circuits, with low power consumption TFETs.

  15. Inelastic scattering in resonant tunneling

    DEFF Research Database (Denmark)

    Wingreen, Ned S.; Jacobsen, Karsten Wedel; Wilkins, John W.

    1989-01-01

    The exact resonant-tunneling transmission probability for an electron interacting with phonons is presented in the limit that the elastic coupling to the leads is independent of energy. The phonons produce transmission sidebands but do not affect the integrated transmission probability or the esc......The exact resonant-tunneling transmission probability for an electron interacting with phonons is presented in the limit that the elastic coupling to the leads is independent of energy. The phonons produce transmission sidebands but do not affect the integrated transmission probability...

  16. Efficient Verification of Tunnell's Criterion

    OpenAIRE

    Bach, Eric; Ryan, Nathan C.

    2007-01-01

    An integer $n$ is congruent if there is a triangle with rational sides whose area is $n$. In the 1980s Tunnell gave an algorithm to test congruence which relied on counting integral points on the ellipsoids $2x^2+y^2+8z^2 = n$ and $2x^2+y^2+32z^2=n$. The correctness of this algorithm is conditional on the conjecture of Birch and Swinnerton-Dyer. The known methods for testing Tunnell's criterion use $O(n)$ operations. In this paper we give several methods with smaller expo...

  17. Quantum Cosmology for Tunneling Universes

    CERN Document Server

    Kim, Sang Pyo

    2004-01-01

    In a quantum cosmological model consisting of a Euclidean region and a Lorentzian region, Hartle-Hawking's no-bounary wave function, and Linde's wave function and Vilenkin's tunneling wave function are briefly described and compared with each other. We put a particular emphasis on semiclassical gravity from quantum cosmology and compare it with the conventional quantum field theory in curved spacetimes. Finally, we discuss the recent debate on catastrophic particle production in the tunneling universe between Rubakov and Vilenkin within the semiclassical gravity.

  18. Drill and blast tunnelling; Konvensjonell drift av tunneler

    Energy Technology Data Exchange (ETDEWEB)

    Roenn, Paal-Egil

    1997-12-31

    This thesis treats drill and blast tunnelling. The rapid technological advance necessitates revised and updated design criteria, quality requirements and quality control. In situ blast experiments were carried out in order to test new methods and improve the basis for calculation and design. The main topics of the experiments were (1) longer rounds and increased drillhole diameter, (2) emulsion slurry as explosives in tunnelling, and (3) electronic detonators in contour blasting. The experiments show that it is technically feasible to blast rounds of up to 8.6 m length. Using current technology, the economical optimum round length is substantially shorter. Dust, low visibility, noise and toxic fumes are occupational environmental strains for the tunnel workers. Several of the environmental factors are strongly influenced by the type of explosives used. For example, emulsion slurry resulted in 4 to 5 times better visibility than Anolit and the concentration of respirable dust and total dust was reduced by 30-50 %. Electronic detonators were tested and found to give a higher percentage of remaining drillholes in the contour than Nonel detonators. The thesis includes a chapter on economic design of hydropower tunnels. 42 refs., 83 figs., 45 tabs.

  19. Spin-dependent tunnelling in magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Tsymbal, Evgeny Y [Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE (United States); Mryasov, Oleg N [Seagate Research, 1251 Waterfront Place, Pittsburgh, PA (United States); LeClair, Patrick R [Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA (United States)

    2003-02-05

    The phenomenon of electron tunnelling has been known since the advent of quantum mechanics, but continues to enrich our understanding of many fields of physics, as well as creating sub-fields on its own. Spin-dependent tunnelling (SDT) in magnetic tunnel junctions (MTJs) has recently aroused enormous interest and has developed in a vigorous field of research. The large tunnelling magnetoresistance (TMR) observed in MTJs garnered much attention due to possible applications in non-volatile random-access memories and next-generation magnetic field sensors. This led to a number of fundamental questions regarding the phenomenon of SDT. In this review article we present an overview of this field of research. We discuss various factors that control the spin polarization and magnetoresistance in MTJs. Starting from early experiments on SDT and their interpretation, we consider thereafter recent experiments and models which highlight the role of the electronic structure of the ferromagnets, the insulating layer, and the ferromagnet/insulator interfaces. We also discuss the role of disorder in the barrier and in the ferromagnetic electrodes and their influence on TMR. (topical review)

  20. COMPARISON OF PAVEMENT STRUCTURES IN TUNNELS

    OpenAIRE

    Rimac, Ivan; Šimun, Miroslav; Dimter, Sanja

    2014-01-01

    Tunnels pose many fire risks. It is difficult to fight fires in tunnels due to their limited accessibility, the quantity of smoke, and high thermal radiation. Temperatures in tunnel fires can reach 1000 °C, and these fires can spread quickly and persist for long periods, the longest recorded in Europe lasting 53 h. The main requirements of tunnel pavement structures are driving safety and comfort, as well as low construction and maintenance costs. Choosing between using concrete or asphalt pa...

  1. Prevention of bacterial adhesion

    DEFF Research Database (Denmark)

    Klemm, Per; Vejborg, Rebecca Munk; Hancock, Viktoria

    2010-01-01

    that imposes selection pressure for resistant bacteria. New approaches are urgently needed. Targeting bacterial virulence functions directly is an attractive alternative. An obvious target is bacterial adhesion. Bacterial adhesion to surfaces is the first step in colonization, invasion, and biofilm formation....... As such, adhesion represents the Achilles heel of crucial pathogenic functions. It follows that interference with adhesion can reduce bacterial virulence. Here, we illustrate this important topic with examples of techniques being developed that can inhibit bacterial adhesion. Some of these will become...

  2. Road Tunnels, Maryland Tunnels, MDTA Tunnels, Fort McHenry Tunnel, Baltimore Harbor Tunnel, Published in 2009, 1:1200 (1in=100ft) scale, Maryland Transportation Authority.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Road Tunnels dataset, published at 1:1200 (1in=100ft) scale, was produced all or in part from Orthoimagery information as of 2009. It is described as 'Maryland...

  3. Fiber coupled ultrafast scanning tunneling microscope

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1997-01-01

    We report on a scanning tunneling microscope with a photoconductive gate in the tunneling current circuit. The tunneling tip is attached to a coplanar transmission line with an integrated photoconductive switch. The switch is illuminated through a fiber which is rigidly attached to the switch...

  4. Tunnel Face Stability & New CPT Applications

    NARCIS (Netherlands)

    Broere, W.

    2001-01-01

    Nearly all tunnels bored in soft soils have encountered problems with the stability of the tunnel face. In several cases these problems led to an extended stand-still of the boring process. A better understanding of the face stability, and of the soil conditions around the tunnel boring machine, can

  5. Tunneling Processes in Optically Excited Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    LI Xiu-Ping; WEI Hua-Rong; XU Li-Ping; GONG Jian-Ping; YAN Wei-Xian

    2011-01-01

    The single-electron tunneling processes in optically excited coupled quantum dots can be divided into two parts: the electron and the hole parts, which are analytically obtained in the framework of the Keldysh formalism. The tunneling process is selective tunneling, which results in dark tunneling states. The tunneling currents are co-determined by the resonance energies and probability distributions of the particular quantum channels defined by the electron-hole complex resonant states.%The single-electron tunneling processes in optically excited coupled quantum dots can be divided into two parts:the electron and the hole parts,which are analytically obtained in the framework of the Keldysh formalism.The tunneling process is selective tunneling,which results in dark tunneling states.The tunneling currents are co-determined by the resonance energies and probability distributions of the particular quantum channels defined by the electron-hole complex resonant states.Probing the fine-energy structure of the exciton complexes[1-10] in an optically excited quantum dot is an important way of exploring new mechanisms in nanostructures.Single electron tunneling (SET) devices consisting of a central quantum dot (QD) and a tunneling coupled source and drain have become important optoelectronic nano-devices.[11,12

  6. Macroscopic quantum tunneling in Josephson tunnel junctions and Coulomb blockade in single small tunnel junctions

    International Nuclear Information System (INIS)

    Experiments investigating the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very small capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showing good agreement with no adjustable parameters; the tunneling rate in the moderately damped (Q ∼ 1) junction is seen to be reduced by a factor of 300 from that predicted for an undamped junction. The phase is seen to be a good quantum-mechanical variable. The experiments on small capacitance tunnel junctions extend the measurements on the larger-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wavefunction has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias. I present the first clear observation of the Coulomb blockade in single junctions. The electrical environment of the tunnel junction, however, strongly affects the behavior of the junction: higher resistance leads are observed to greatly sharpen the Coulomb blockade over that seen with lower resistance leads. I present theoretical descriptions of how the environment influences the junctions; comparisons with the experimental results are in reasonable agreement

  7. An Escherichia coli strain deficient for both exonuclease V and deoxycytidine triphosphate deaminase shows enhanced sensitivity to ionizing radiation.

    Science.gov (United States)

    Estèvenon, A M; Kooistra, J; Sicard, N

    1995-02-20

    An Escherichia coli mutant lacking deoxycytidine triphosphate deaminase (Dcd) activity and an unknown function encoded by a gene designated ior exhibits sensitivity to ionizing radiation whereas dcd mutants themselves are not sensitive. A DNA fragment from an E. coli genomic library that restores the wild type level of UV and gamma ray resistance to this mutant has been cloned in the multicopy vector pBR322. Comparison of its restriction map with the physical map of the E. coli chromosome revealed complete identity to the recBD genes. ior affects ATP-dependent exonuclease activity, suggesting that it is an allele of recB. This mutation alone does not confer sensitivity to UV and gamma radiation, indicating that lack of Dcd activity is also required for expression of radiation sensitivity.

  8. Mars Surface Tunnel Element Concept

    Science.gov (United States)

    Rucker, Michelle A.; Mary, Natalie; Howe, A. Scott; Jeffries, Sharon

    2016-01-01

    How Mars surface crews get into their ascent vehicle has profound implications for Mars surface architecture. To meet planetary protection protocols, the architecture has get Intravehicular Activity (IVA)-suited crew into a Mars Ascent Vehicle (MAV) without having to step outside into the Mars environment. Pushing EVA suit don/doff and EVA operations to an element that remains on the surface also helps to minimize MAV cabin volume, which in turn can reduce MAV cabin mass. Because the MAV will require at least seven kilograms of propellant to ascend each kilogram of cabin mass, minimal MAV mass is desired. For architectures involving more than one surface element-such as an ascent vehicle and a pressurized rover or surface habitat-a retractable tunnel is an attractive solution. Beyond addressing the immediate MAV access issue, a reusable tunnel may be useful for other surface applications once its primary mission is complete. A National Aeronautics and Space Administration (NASA) team is studying the optimal balance between surface tunnel functionality, mass, and stowed volume as part of the Evolvable Mars Campaign (EMC). The "Minimum Functional Tunnel" is a conceptual design that performs a single function. Having established this baseline configuration, the next step is to trade design options, evaluate other applications, and explore alternative solutions.

  9. Time tunnels meet warped passages

    CERN Multimedia

    Kushner, David

    2006-01-01

    "Just in time for its 40th anniversary, the classic sci-fi television show "The time tunnel" is out on DVD. The conceit is something every engineer can relate to: a pulled plug. Scientists in an underground lab are working on a secret government experiment in time travel. (1 page)

  10. Tunneling in the SIS Structure

    Science.gov (United States)

    Shukrinov, Yu.; Kohandel, M.

    2000-09-01

    We discuss the effects caused by the layered structure of high temperature superconductors (HTS). We use the layered S-N model to obtain the tunneling current of the SIS structure. The current-voltage characteristic is calculated in the limit cases when dI/dV is proportional to the state density of HTS.

  11. Wormhole creation by quantum tunnelling

    CERN Document Server

    Battarra, Lorenzo; Lehners, Jean-Luc

    2016-01-01

    We study the process of quantum tunnelling in self-interacting scalar field theories with non-minimal coupling to gravity. In these theories gravitational instantons can develop a neck -- a feature prohibited in theories with minimal coupling, and describing the nucleation of geometries containing a wormhole. We also clarify the relationship of neck geometries to violations of the null energy condition.

  12. Quantum Tunneling in Black Holes

    CERN Document Server

    Majhi, Bibhas Ranjan

    2011-01-01

    This thesis is focussed towards the applications of the quantum tunneling mechanism to study black holes. Here we give a general frame work of the existing tunneling mechanism, both the radial null geodesic and Hamilton Jacobi methods. On the radial null geodesic method side, we study the modifications to the tunneling rate, Hawking temperature and the Bekenstein- Hawking area law by including the back reaction as well as non-commutative effects in the space-time. A reformulation of the Hamilton-Jacobi (HJ) method is first introduced. Based on this, a close connection between the quantum tunneling and the gravitational anomaly mechanisms to discuss Hawking effect, is put forwarded. An interesting advantage of this reformulated HJ method is that one can get directly the emission spectrum from the event horizon of the black hole, which was missing in the earlier literature. Also, the quantization of the entropy and area of a black hole is discussed in this method. Another part of the thesis is the introduction ...

  13. Installation in the SPS tunnel

    CERN Multimedia

    1974-01-01

    The SPS tunnel is 6910 m in circumference and has a cross section of 4 m inner diameter. It is situated at an elevation of 400 m above sea level at a depth below the surface varying between 23 and 65 m. Its walls are lined with a concrete shell of about 30 cm thickness. See also 7410043X

  14. Apparent tunneling in chemical reactions

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm; Hansen, Flemming Yssing; Billing, G. D.

    2000-01-01

    A necessary condition for tunneling in a chemical reaction is that the probability of crossing a barrier is non-zero, when the energy of the reactants is below the potential energy of the barrier. Due to the non-classical nature (i.e, momentum uncertainty) of vibrational states this is, however...

  15. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

    Two different analyses have been carried out in order to find the vertical earth pressure, or overburden pressure, at the crown of a tunnel going through a dike. Firstly, a hand calculation is performed using a simple dispersion of the stresses over depth. Secondly, the finite‐element program...

  16. The recurrent carpal tunnel syndrome.

    Science.gov (United States)

    Kern, B C; Brock, M; Rudolph, K H; Logemann, H

    1993-01-01

    Sixteen out of 720 patients with carpal tunnel syndrome who had undergone surgery since 1979 were reoperated for a "recurrence" (2.2%). Twelve of these patients had been originally operated on in our department. Thus, our own recurrence rate is 1.7%. Three patients deteriorated following surgery, 6 had an unsatisfactory improvement, and in 7 the symptoms recurred after initial improvement. Eight of the reoperated patients had a predisposing disease (terminal renal insufficiency, insulin-dependent diabetes mellitus, acromegaly). In 10 of the 16 cases the initial operation had been carried out by surgeons in the first three years of training. Reoperation revealed incomplete splitting of the transverse carpal ligament in 10 cases, compression of the median nerve by the scar in 4, injury of the muscular branch in 1, and an anatomical variant as cause of incomplete decompression in 1 patient. "Recurrences" after carpal tunnel surgery are predominantly due to inadequacies of the first procedure. A remarkable number of patients (50%) has predisposing diseases. Interfascicular or epineural neurolysis and complete exposure and neurolysis of the median nerve and its branches is necessary only in cases of recurrence. Their omission at the first surgery does not result in an increased recurrence rate. Our observations indicate that the number of operations for recurrent carpal tunnel syndrome can probably be reduced when the first operation is performed with care and experience. Patients with carpal tunnel syndrome secondary to a systemic disease are particularly at risk.

  17. Introduction to scanning tunneling microscopy

    CERN Document Server

    Chen, C Julian

    2008-01-01

    The scanning tunneling and the atomic force microscope, both capable of imaging individual atoms, were crowned with the Physics Nobel Prize in 1986, and are the cornerstones of nanotechnology today. This is a thoroughly updated version of this 'bible' in the field.

  18. Light emission in tunneling processes

    International Nuclear Information System (INIS)

    We introduce a new method for mapping and analyzing (with atomic resolution) molecules adsorbed on surfaces. This method relies on the detection of fluorescence from molecules, electronically excited by inelastic tunneling in STM. It may combines the excellent spatial resolution of STM together with the specificity of fluorescence as an analytical tool. We propose to overcome this problem by choosing 'transparent conductors' (such as Indium Tin Oxides-lTO) as the STM substrate. ITO, characterized by a large optical gap, will not quench electronically excited molecules. We have tested our idea to enhance the quantum efficiency of molecular emission on surfaces by using transparent conductors in the tunneling junction. We have constructed large area tunnel-junctions by using the squeezable tunnel-Junction technique. The principle of this technique is to squeeze together smooth flat surfaces separated by a thin spacer. By applying a controlled force, junctions with surface area of thousands of square angstroms are made. We have recorded light emission from bare tunneling surfaces and from surfaces coated with molecules (DCA, DCM and COUMARINE), as a function of the bias voltage in the range of 0-5 volts. Typical tunneling currents are 50 nano ampere. Our main findings are: The bare ITO surface emits light at biasing voltages larger than 4.0 eV which corresponds to electron-hole excitation over the optical gap of ITO. ITO surfaces coated with chromophore molecules have shown enhanced light emission at a voltage bias which corresponds to the allowed excitations energies in the chromophore. A voltage bias of 2-5 V yielded light emission of 5 * 103 photon/μC. The corresponding metallic surfaces, bare or coated with a chromophore did not show any emission. In order to test the possibility of using this effect for imaging purposes we have replaced one electrode of junction with an ITO coated glass tip of 180 μm radius. such a tip yield an upper limit of tunneling area of

  19. An improved red blood cell additive solution maintains 2,3-diphosphoglycerate and adenosine triphosphate levels by an enhancing effect on phosphofructokinase activity during cold storage

    NARCIS (Netherlands)

    P. Burger; H. Korsten; D. de Korte; E. Rombout; R. van Bruggen; A.J. Verhoeven

    2010-01-01

    BACKGROUND: Current additive solutions (ASs) for red blood cells (RBCs) do not maintain constant 2,3-diphosphoglycerate (DPG) and adenosine triphosphate (ATP) levels during cold storage We have previously shown that with a new AS called phosphate-adenine-glucose-guanosine-gluconate-mannitol (PAGGGM)

  20. Plaque retention by self-ligating vs elastomeric orthodontic brackets: quantitative comparison of oral bacteria and detection with adenosine triphosphate-driven bioluminescence.

    NARCIS (Netherlands)

    Pellegrini, P.; Sauerwein, R.W.; Finlayson, T.; McLeod, J.; Covell, D.A.; Maier, T.; Machida, C.A.

    2009-01-01

    INTRODUCTION: Enamel decalcification is a common problem in orthodontics. The objectives of this randomized clinical study were to enumerate and compare plaque bacteria surrounding 2 bracket types, self-ligating (SL) vs elastomeric ligating (E), and to determine whether adenosine triphosphate (ATP)-

  1. AN ESCHERICHIA-COLI STRAIN DEFICIENT FOR BOTH EXONUCLEASE-V AND DEOXYCYTIDINE TRIPHOSPHATE DEAMINASE SHOWS ENHANCED SENSITIVITY TO IONIZING-RADIATION

    NARCIS (Netherlands)

    ESTEVENON, AM; KOOISTRA, J; SICARD, N

    1995-01-01

    An Escherichia coli mutant lacking deoxycytidine triphosphate deaminase (Dcd) activity and an unknown function encoded by a gene designated ior exhibits sensitivity to ionizing radiation whereas dcd mutants themselves are not sensitive. A DNA fragment from an E. coli genomic library that restores th

  2. Sterol transporter adenosine triphosphate-binding cassette transporter G8, gallstones, and biliary cancer in 62,000 individuals from the general population

    DEFF Research Database (Denmark)

    Stender, Stefan; Frikke-Schmidt, Ruth; Nordestgaard, Børge G;

    2011-01-01

    Gallstone disease, a risk factor for biliary cancer, has a strong heritable component, but the underlying genes are largely unknown. To test the hypothesis that ABCG8 (adenosine triphosphate-binding cassette transporter G8) Asp19His (D19H) genotype predicted risk of gallstones and biliary cancer ...

  3. Adenosine 5 '-triphosphate (ATP) supplements are not orally bioavailable: a randomized, placebo-controlled cross-over trial in healthy humans

    NARCIS (Netherlands)

    Arts, I.C.W.; Coolen, E.J.C.M.; Bours, M.J.L.; Huyghebaert, N.; Cohen Stuart, M.A.; Bast, A.; Dagnelie, P.C.

    2012-01-01

    Background: Nutritional supplements designed to increase adenosine 5'-triphosphate (ATP) concentrations are commonly used by athletes as ergogenic aids. ATP is the primary source of energy for the cells, and supplementation may enhance the ability to maintain high ATP turnover during high-intensity

  4. Heat Transfer in Underground Rail Tunnels

    CERN Document Server

    Sadokierski, Stefan

    2007-01-01

    The transfer of heat between the air and surrounding soil in underground tunnels ins investigated, as part of the analysis of environmental conditions in underground rail systems. Using standard turbulent modelling assumptions, flow profiles are obtained in both open tunnels and in the annulus between a tunnel wall and a moving train, from which the heat transfer coefficient between the air and tunnel wall is computed. The radial conduction of heat through the surrounding soil resulting from changes in the temperature of air in the tunnel are determined. An impulse change and an oscillating tunnel air temperature are considered separately. The correlations between fluctuations in heat transfer coefficient and air temperature are found to increase the mean soil temperature. Finally, a model for the coupled evolution of the air and surrounding soil temperature along a tunnel of finite length is given.

  5. An Entropic Formulation of Tunneling Time

    CERN Document Server

    Demir, Durmus A

    2015-01-01

    Quantum tunneling governs numerous phenomena in biology, chemistry, physics and technology. Tunneling time, formulated in various different forms due to the absence of a time operator in quantum theory, has been measured recently in experiments based on the attoclock in ultrafast laser ionization of Helium atoms [A.~Landsman {\\it et al.}, Optica {\\bf 1}, 343 (2014)]. The experiment performs a refined measurement with which no tunneling time formula in the literature exhibits adequate congruence. Here we show that, entropic considerations lead to a real tunneling time which shows remarkable agreement with the experimental data and stays always subluminal. Indeed, with phase space volume setting the number of microstates for a single evanescing particle in a state of definite momentum consistent with energy conservation, one is naturally led to a statistical description for quantum tunneling in which thermal energy sets the tunneling time. This entropic tunneling time is rather general and might also be extende...

  6. Photon Aided and Inhibited Tunneling of Photons

    CERN Document Server

    liu, xuele

    2013-01-01

    In the light of the interest in the transport of single photons in arrays of waveguides, fiber couplers, photonic crystals, etc., we consider the quantum mechanical process of the tunneling of photons through evanescently or otherwise coupled structures. We specifically examine the issue of tunneling between two structures when one structure already contains few photons. We demonstrate the possibility of both photon aided and inhibited tunneling of photons. The Bosonic nature of photons enhances the tunneling probability. We also show how the multiphoton tunneling probability can be either enhanced or inhibited due to the presence of photons. We find similar results for the higher order tunneling. Finally, we show that the presence of a squeezed field changes the nature of tunneling considerably.

  7. Resonant tunnel magnetoresistance in a double magnetic tunnel junction

    KAUST Repository

    Useinov, Arthur

    2011-08-09

    We present quasi-classical approach to calculate a spin-dependent current and tunnel magnetoresistance (TMR) in double magnetic tunnel junctions (DMTJ) FML/I/FMW/I/FMR, where the magnetization of the middle ferromagnetic metal layer FMW can be aligned parallel or antiparallel with respect to the fixed magnetizations of the left FML and right FMR ferromagnetic electrodes. The transmission coefficients for components of the spin-dependent current, and TMR are calculated as a function of the applied voltage. As a result, we found a high resonant TMR. Thus, DMTJ can serve as highly effective magnetic nanosensor for biological applications, or as magnetic memory cells by switching the magnetization of the inner ferromagnetic layer FMW.© Springer Science+Business Media, LLC 2011.

  8. In-Tunnel Blast Pressure Empirical Formulas for Detonations External, Internal and at the Tunnel Entrance

    Institute of Scientific and Technical Information of China (English)

    LI Xiudi; ZHENG Yingren

    2006-01-01

    In order to define the loading on protective doors of an underground tunnel,the exact knowledge of the blast propagation through tunnels is needed.Thirty-three scale high-explosive tests are conducted to obtain in-tunnel blast pressure for detonations external,internal and at the tunnel entrance.The cross section of the concrete model tunnel is 0.67 m2.Explosive charges of TNT,ranging in mass from 400 g to 4 600 g,are detonated at various positions along the central axis of the model tunnel.Blast gages are flush-installed in the interior surface of the tunnel to record side-on blast pressure as it propagates down the tunnel.The engineering empirical formulas for predicting blast peak pressure are evaluated,and are found to be reasonably accurate for in-tunnel pressure prediction.

  9. Fermion tunneling from dynamical horizons

    Science.gov (United States)

    Di Criscienzo, R.; Vanzo, L.

    2008-06-01

    The instability against emission of fermionic particles by the trapping horizon of an evolving black hole is analyzed and confirmed using the Hamilton-Jacobi tunneling method. This method automatically selects one special expression for the surface gravity of a changing horizon. The results also apply to point masses embedded in an expanding universe. As a bonus of the tunneling method, we gain the insight that the surface gravity still defines a temperature parameter as long as the evolution is sufficiently slow that the black-hole pass through a sequence of quasi-equilibrium states, and that black holes should be semi-classically unstable even in a hypothetical world without bosonic fields.

  10. Single-contact tunneling thermometry

    Energy Technology Data Exchange (ETDEWEB)

    Maksymovych, Petro

    2016-02-23

    A single-contact tunneling thermometry circuit includes a tunnel junction formed between two objects. Junction temperature gradient information is determined based on a mathematical relationship between a target alternating voltage applied across the junction and the junction temperature gradient. Total voltage measured across the junction indicates the magnitude of the target alternating voltage. A thermal gradient is induced across the junction. A reference thermovoltage is measured when zero alternating voltage is applied across the junction. An increasing alternating voltage is applied while measuring a thermovoltage component and a DC rectification voltage component created by the applied alternating voltage. The target alternating voltage is reached when the thermovoltage is nullified or doubled by the DC rectification voltage depending on the sign of the reference thermovoltage. Thermoelectric current and current measurements may be utilized in place of the thermovoltage and voltage measurements. The system may be automated with a feedback loop.

  11. Tunneling of a coupled system

    International Nuclear Information System (INIS)

    We consider tunneling through a potential barrier V(x) in the presence of a coupling term W(x,y). Let H(y) be the internal Hamiltonian associated with the coordinate y and let E0(x) be the ground state energy of the operator H(x;y) = H(y) + W(x,y) in which x is a parameter. Our result for the tunneling probability (in the WKB approximation) is P = exp(2i ∫ k0(x)dx) where, at energy E, k0(x) = [E-E0(x)-V(x)]sup(1/2)/(h/2π) is the local wave number in the presence of coupling. (orig.)

  12. Seismic scanning tunneling macroscope - Theory

    KAUST Repository

    Schuster, Gerard T.

    2012-09-01

    We propose a seismic scanning tunneling macroscope (SSTM) that can detect the presence of sub-wavelength scatterers in the near-field of either the source or the receivers. Analytic formulas for the time reverse mirror (TRM) profile associated with a single scatterer model show that the spatial resolution limit to be, unlike the Abbe limit of λ/2, independent of wavelength and linearly proportional to the source-scatterer separation as long as the point scatterer is in the near-field region; if the sub-wavelength scatterer is a spherical impedance discontinuity then the resolution will also be limited by the radius of the sphere. Therefore, superresolution imaging can be achieved as the scatterer approaches the source. This is analogous to an optical scanning tunneling microscope that has sub-wavelength resolution. Scaled to seismic frequencies, it is theoretically possible to extract 100 Hz information from 20 Hz data by imaging of near-field seismic energy.

  13. Wildlife Tunnel Enhances Population Viability

    Directory of Open Access Journals (Sweden)

    Michael McCarthy

    2009-12-01

    Full Text Available Roads and traffic are pervasive components of landscapes throughout the world: they cause wildlife mortality, disrupt animal movements, and increase the risk of extinction. Expensive engineering solutions, such as overpasses and tunnels, are increasingly being adopted to mitigate these effects. Although some species readily use such structures, their success in preventing population extinction remains unknown. Here, we use population viability modeling to assess the effectiveness of tunnels for the endangered Mountain Pygmy-possum (Burramys parvus in Australia. The underpasses reduced, but did not completely remove, the negative effects of a road. The expected minimum population size of a “reconnected” population remained 15% lower than that of a comparable “undivided” population. We propose that the extent to which the risk of extinction decreases should be adopted as a measure of effectiveness of mitigation measures and that the use of population modeling become routine in these evaluations.

  14. Tunneling decay of false kinks

    CERN Document Server

    Dupuis, Éric; MacKenzie, Richard; Marleau, Luc; Paranjape, M B; Ung, Y

    2015-01-01

    We consider the decay of "false kinks," that is, kinks formed in a scalar field theory with a pair of degenerate symmetry-breaking false vacua in 1+1 dimensions. The true vacuum is symmetric. A second scalar field and a peculiar potential are added in order for the kink to be classically stable. We find an expression for the decay rate of a false kink. As with any tunneling event, the rate is proportional to $\\exp(-S_E)$ where $S_E$ is the Euclidean action of the bounce describing the tunneling event. This factor varies wildly depending on the parameters of the model. Of interest is the fact that for certain parameters $S_E$ can get arbitrarily small, implying that the kink is only barely stable. Thus, while the false vacuum itself may be very long-lived, the presence of kinks can give rise to rapid vacuum decay.

  15. Observing remnants by fermions' tunneling

    OpenAIRE

    Chen, Deyou; Wu, Houwen; Yang, Haitang

    2013-01-01

    The standard Hawking formula predicts the complete evaporation of black holes. In this paper, we introduce effects of quantum gravity into fermions' tunneling from Reissner-Nordstrom and Kerr black holes. The quantum gravity effects slow down the increase of Hawking temperatures. This property naturally leads to a residue mass in black hole evaporation. The corrected temperatures are affected by the quantum numbers of emitted fermions. Meanwhile, the temperature of the Kerr black hole is a fu...

  16. Dissipative Effect and Tunneling Time

    Directory of Open Access Journals (Sweden)

    Samyadeb Bhattacharya

    2011-01-01

    Full Text Available The quantum Langevin equation has been studied for dissipative system using the approach of Ford et al. Here, we have considered the inverted harmonic oscillator potential and calculated the effect of dissipation on tunneling time, group delay, and the self-interference term. A critical value of the friction coefficient has been determined for which the self-interference term vanishes. This approach sheds new light on understanding the ion transport at nanoscale.

  17. Laser tunneling from aligned molecules

    CERN Document Server

    Smeenk, C T L; Sokolov, A V; Spanner, M; Lee, K F; Staudte, A; Villeneuve, D M; Corkum, P B

    2013-01-01

    We study multi-photon ionization from N_2, O_2 and benzene using circularly polarized light. By examining molecular frame photo-electron angular distributions, we illustrate how multi-photon ionization acts a momentum-selective probe of the local electron density in the Dyson orbitals for these molecules. We find good agreement with calculations based on a tunneling model and including saturation effects.

  18. Digging the CNGS decay tunnel

    CERN Multimedia

    Patrice Loiez

    2002-01-01

    Products of the collision between a proton beam and a graphite target will pass through a horn containing an electric field that will produce a focused beam. These particles will decay into muon neutrinos within the tunnel that is being constructed in these images. The neutrinos will then travel 730 km to Gran Sasso in Italy where huge detectors will observe the beam to study a process called neutrino oscillation.

  19. Quantum tunneling and trace anomaly

    International Nuclear Information System (INIS)

    We compute the corrections, using the tunneling formalism based on a quantum WKB approach, to the Hawking temperature and Bekenstein-Hawking entropy for the Schwarzschild black hole. The results are related to the trace anomaly and are shown to be equivalent to findings inferred from Hawking's original calculation based on path integrals using zeta function regularization. Finally, exploiting the corrected temperature and periodicity arguments we also find the modification to the original Schwarzschild metric which captures the effect of quantum corrections.

  20. Electrodiagnosis of carpal tunnel syndrome.

    Science.gov (United States)

    Wang, Leilei

    2013-02-01

    This article discusses the historical aspects related to the understanding of carpal tunnel syndrome (CTS) and its diagnosis, highlighting observations about this disease that have yet to be challenged. This is followed by a discussion regarding the use of electrodiagnostic testing as a diagnostic tool for CTS, as well as the author's approach to making the diagnosis of CTS. Finally, conclusions about future directions in the diagnosis and treatment of this disorder are presented.

  1. Confocal Annular Josephson Tunnel Junctions

    Science.gov (United States)

    Monaco, Roberto

    2016-04-01

    The physics of Josephson tunnel junctions drastically depends on their geometrical configurations and here we show that also tiny geometrical details play a determinant role. More specifically, we develop the theory of short and long annular Josephson tunnel junctions delimited by two confocal ellipses. The behavior of a circular annular Josephson tunnel junction is then seen to be simply a special case of the above result. For junctions having a normalized perimeter less than one, the threshold curves in the presence of an in-plane magnetic field of arbitrary orientations are derived and computed even in the case with trapped Josephson vortices. For longer junctions, a numerical analysis is carried out after the derivation of the appropriate motion equation for the Josephson phase. We found that the system is modeled by a modified and perturbed sine-Gordon equation with a space-dependent effective Josephson penetration length inversely proportional to the local junction width. Both the fluxon statics and dynamics are deeply affected by the non-uniform annulus width. Static zero-field multiple-fluxon solutions exist even in the presence of a large bias current. The tangential velocity of a traveling fluxon is not determined by the balance between the driving and drag forces due to the dissipative losses. Furthermore, the fluxon motion is characterized by a strong radial inward acceleration which causes electromagnetic radiation concentrated at the ellipse equatorial points.

  2. Variable Density Turbulence Tunnel Facility

    CERN Document Server

    Bewley, Gregory P; Sinhuber, Michael; Xu, Haitao; Bodenschatz, Eberhard

    2014-01-01

    The Variable Density Turbulence Tunnel (VDTT) at the Max Planck Institute for Dynamics and Self-Organization in G\\"ottingen, Germany produces very high turbulence levels at moderate flow velocities, low power consumption and adjustable kinematic viscosity. To reach the highest Reynolds number, the tunnel can be filled and pressurized up to 15 bar with the dense gas sulfur hexafluoride (SF$_6$). The Reynolds number can be varied by changing the pressure or flow rate of the gas or by using different non-flammable gases including air. Turbulence is generated at the upstream ends of two measurement sections with grids, and the evolution of this turbulence is observed as it moves down the length of the sections. We describe the instrumentation presently in operation, which consists of the tunnel itself, classical grid turbulence generators, and state-of-the-art nano-fabricated hot-wire anemometers provided by Princeton University [Vallikivi et al. (2011) Exp. Fluids 51, 1521]. We report measurements of the charact...

  3. Confocal Annular Josephson Tunnel Junctions

    Science.gov (United States)

    Monaco, Roberto

    2016-09-01

    The physics of Josephson tunnel junctions drastically depends on their geometrical configurations and here we show that also tiny geometrical details play a determinant role. More specifically, we develop the theory of short and long annular Josephson tunnel junctions delimited by two confocal ellipses. The behavior of a circular annular Josephson tunnel junction is then seen to be simply a special case of the above result. For junctions having a normalized perimeter less than one, the threshold curves in the presence of an in-plane magnetic field of arbitrary orientations are derived and computed even in the case with trapped Josephson vortices. For longer junctions, a numerical analysis is carried out after the derivation of the appropriate motion equation for the Josephson phase. We found that the system is modeled by a modified and perturbed sine-Gordon equation with a space-dependent effective Josephson penetration length inversely proportional to the local junction width. Both the fluxon statics and dynamics are deeply affected by the non-uniform annulus width. Static zero-field multiple-fluxon solutions exist even in the presence of a large bias current. The tangential velocity of a traveling fluxon is not determined by the balance between the driving and drag forces due to the dissipative losses. Furthermore, the fluxon motion is characterized by a strong radial inward acceleration which causes electromagnetic radiation concentrated at the ellipse equatorial points.

  4. Tunneling decay of false vortices

    CERN Document Server

    Lee, Bum-Hoon; MacKenzie, Richard; Paranjape, M B; Yajnik, U A; Yeom, Dong-han

    2013-01-01

    We consider the decay of vortices trapped in the false vacuum of a theory of scalar electrodynamics in 2+1 dimensions. The potential is inspired by models with intermediate symmetry breaking to a metastable vacuum that completely breaks a U(1) symmetry, while in the true vacuum the symmetry is unbroken. The false vacuum is unstable through the formation of true vacuum bubbles; however, the rate of decay can be extremely long. On the other hand, the false vacuum can contain metastable vortex solutions. These vortices contain the true vacuum inside in addition to a unit of magnetic flux and the appropriate topologically nontrivial false vacuum outside. We numerically establish the existence of vortex solutions which are classically stable; however, they can decay via tunneling. In general terms, they tunnel to a configuration which is a large, thin-walled vortex configuration that is now classically unstable to the expansion of its radius. We compute an estimate for the tunneling amplitude in the semi-classical...

  5. Autonomous Robotic Inspection in Tunnels

    Science.gov (United States)

    Protopapadakis, E.; Stentoumis, C.; Doulamis, N.; Doulamis, A.; Loupos, K.; Makantasis, K.; Kopsiaftis, G.; Amditis, A.

    2016-06-01

    In this paper, an automatic robotic inspector for tunnel assessment is presented. The proposed platform is able to autonomously navigate within the civil infrastructures, grab stereo images and process/analyse them, in order to identify defect types. At first, there is the crack detection via deep learning approaches. Then, a detailed 3D model of the cracked area is created, utilizing photogrammetric methods. Finally, a laser profiling of the tunnel's lining, for a narrow region close to detected crack is performed; allowing for the deduction of potential deformations. The robotic platform consists of an autonomous mobile vehicle; a crane arm, guided by the computer vision-based crack detector, carrying ultrasound sensors, the stereo cameras and the laser scanner. Visual inspection is based on convolutional neural networks, which support the creation of high-level discriminative features for complex non-linear pattern classification. Then, real-time 3D information is accurately calculated and the crack position and orientation is passed to the robotic platform. The entire system has been evaluated in railway and road tunnels, i.e. in Egnatia Highway and London underground infrastructure.

  6. Vimentin in Bacterial Infections

    Directory of Open Access Journals (Sweden)

    Tim N. Mak

    2016-04-01

    Full Text Available Despite well-studied bacterial strategies to target actin to subvert the host cell cytoskeleton, thus promoting bacterial survival, replication, and dissemination, relatively little is known about the bacterial interaction with other components of the host cell cytoskeleton, including intermediate filaments (IFs. IFs have not only roles in maintaining the structural integrity of the cell, but they are also involved in many cellular processes including cell adhesion, immune signaling, and autophagy, processes that are important in the context of bacterial infections. Here, we summarize the knowledge about the role of IFs in bacterial infections, focusing on the type III IF protein vimentin. Recent studies have revealed the involvement of vimentin in host cell defenses, acting as ligand for several pattern recognition receptors of the innate immune system. Two main aspects of bacteria-vimentin interactions are presented in this review: the role of vimentin in pathogen-binding on the cell surface and subsequent bacterial invasion and the interaction of cytosolic vimentin and intracellular pathogens with regards to innate immune signaling. Mechanistic insight is presented involving distinct bacterial virulence factors that target vimentin to subvert its function in order to change the host cell fate in the course of a bacterial infection.

  7. Evidence for a "metabolically inactive" inorganic phosphate pool in adenosine triphosphate synthase reaction using localized 31P saturation transfer magnetic resonance spectroscopy in the rat brain at 11.7 T.

    Science.gov (United States)

    Tiret, Brice; Brouillet, Emmanuel; Valette, Julien

    2016-09-01

    With the increased spectral resolution made possible at high fields, a second, smaller inorganic phosphate resonance can be resolved on (31)P magnetic resonance spectra in the rat brain. Saturation transfer was used to estimate de novo adenosine triphosphate synthesis reaction rate. While the main inorganic phosphate pool is used by adenosine triphosphate synthase, the second pool is inactive for this reaction. Accounting for this new pool may not only help us understand (31)P magnetic resonance spectroscopy metabolic profiles better but also better quantify adenosine triphosphate synthesis.

  8. Insights into the molecular mechanism of inhibition and drug resistance for HIV-1 RT with carbovir triphosphate.

    Science.gov (United States)

    Ray, Adrian S; Yang, Zhenjun; Shi, Junxing; Hobbs, Ann; Schinazi, Raymond F; Chu, Chung K; Anderson, Karen S

    2002-04-23

    Abacavir (1592U89, or Ziagen) is a powerful and selective inhibitor of HIV-1 viral replication that has been approved by the FDA for treatment of acquired immunodeficiency syndrome. Abacavir is metabolized to the active compound carbovir triphosphate (CBVTP). This compound is a guanosine analogue containing a 2',3'-unsaturation in its planar carbocyclic deoxyribose ring that acts on HIV-1 reverse transcriptase (RT(WT)) as a molecular target, resulting in chain termination of DNA synthesis. A single amino acid change from methionine 184 to valine in HIV-1 RT (RT(M184V)) has been observed clinically in response to abacavir treatment. The ability of the natural substrate, dGTP, or CBVTP to be utilized during DNA- and RNA-directed polymerization by RT(WT) and RT(M184V) was defined by pre-steady-state kinetic parameters. In the case of RT(WT), CBVTP was found to be a surprisingly poor substrate relative to dGTP. In both DNA- and RNA-directed polymerization, a decrease in the efficiency of CBVTP utilization with respect to dGTP was found with RT(M184V), suggesting that this mutation confers resistance at the level of CBVMP incorporation. The relatively low incorporation efficiency for RT(WT) was unanticipated considering earlier studies showing that the triphosphate form of a thymidine nucleoside analogue containing a planar 2',3'-unsaturated ribose ring, D4TTP, was incorporated with high efficiency relative to the natural substrate, dTTP. The difference may be related to the isosteric replacement of oxygen in the deoxyribose ring with carbon. This hypothesis was tested by synthesizing and evaluating D4GTP (the planar 2',3'-unsaturated deoxyribose guanosine analogue that is complementary to D4TTP). In contrast to CBVTP, D4GTP was found to be an excellent substrate for RT(WT) and no resistance was conferred by the M184V mutation, thus providing novel insight into structure-activity relationships for nucleoside-based inhibitors. In this work, we illustrate how an

  9. Tunneling Dynamics Between Atomic Bright Solitons

    CERN Document Server

    Zhao, Li-Chen; Yang, Zhan-Ying; Yang, Wen-Li

    2016-01-01

    We investigate tunneling behavior between two bright solitons in a Bose-Einstein condensate with attractive contact interactions between atoms. The explicit tunneling properties including tunneling particles and oscillation period are described analytically, which indicates that the periodic tunneling form is a nonlinear Josephson type oscillation. The results suggest that the breathing behavior of solitons comes from the tunneling mechanism in an effective double-well potential, which is quite different from the modulational instability mechanism for Akhmediev breather and K-M breather. Furthermore, we obtain a phase diagram for two soliton interaction which admits tunneling property, particle-like property, interference property, and a resonant interaction case. The explicit conditions for them are clarified based on the defined critical distance $d_c$ and spatial interference period $D$.

  10. Tunnel design considering stress release effect

    Institute of Scientific and Technical Information of China (English)

    Van-hung DAO

    2009-01-01

    In tunnel design,the determination of installation time and the stiffness of supporting structures is very important to the tunnel stability.This study used the convergence-confinement method to determine the stress and displacement of the tunnel while considering the counter-pressure curve of the ground base,the stress release effect,and the interaction between the tunnel lining and the rock surrounding the tunnel chamber.The results allowed for the determination of the installation time,distribution and strength of supporting structures.This method was applied to the intake tunnel in the Ban Ve Hydroelectric Power Plant,in Nghe An Province,Vietnam.The results show that when a suitable displacement u0 ranging from 0.0865 m to 0.0919 m occurrs,we can install supporting structures that satisfy the stability and economical requirements.

  11. Investigation into scanning tunnelling luminescence microscopy

    CERN Document Server

    Manson-Smith, S K

    2001-01-01

    This work reports on the development of a scanning tunnelling luminescence (STL) microscope and its application to the study of Ill-nitride semiconductor materials used in the production of light emitting devices. STL microscopy is a technique which uses the high resolution topographic imaging capabilities of the scanning tunnelling microscope (STM) to generate high resolution luminescence images. The STM tunnelling current acts as a highly localised source of electrons (or holes) which generates luminescence in certain materials. Light generated at the STM tunnelling junction is collected concurrently with the height variation of the tunnelling probe as it is scanned across a sample surface, producing simultaneous topographic and luminescence images. Due to the very localised excitation source, high resolution luminescence images can be obtained. Spectroscopic resolution can be obtained by using filters. Additionally, the variation of luminescence intensity with tunnel current and with bias voltage can provi...

  12. Unconventional scanning tunneling conductance spectra for graphene

    OpenAIRE

    Saha, K.; Paul, I.; Sengupta, K.

    2009-01-01

    We compute the tunneling conductance of graphene as measured by a scanning tunneling microscope (STM) with a normal/superconducting tip. We demonstrate that for undoped graphene with zero Fermi energy, the first derivative of the tunneling conductance with respect to the applied voltage is proportional to the density of states of the STM tip. We also show that the shape of the STM spectra for graphene doped with impurities depends qualitatively on the position of the impurity atom in the grap...

  13. Emissions of noxious supstances in road tunnel

    OpenAIRE

    Kenda, Ivan

    2008-01-01

    Construction of tunnels, galleries, bridging objects and other underground engineers constructions is the most exacting work at low buildings. Tunnel seems to be very simple building but there must be interdisciplinary interweaving of entire civil engineering knowledge of geology, mining, architectures, ecology and of other in all phases of planning, building and maintenance of underground constructions. Tunnel is only one of the objects on a road. Careful planning of traffic only throu...

  14. Quantum tunneling and field electron emission theories

    CERN Document Server

    Liang, Shi-Dong

    2013-01-01

    Quantum tunneling is an essential issue in quantum physics. Especially, the rapid development of nanotechnology in recent years promises a lot of applications in condensed matter physics, surface science and nanodevices, which are growing interests in fundamental issues, computational techniques and potential applications of quantum tunneling. The book involves two relevant topics. One is quantum tunneling theory in condensed matter physics, including the basic concepts and methods, especially for recent developments in mesoscopic physics and computational formulation. The second part is the f

  15. Tunnel Probabilistic Structural Analysis Using the FORM

    OpenAIRE

    Yousef Mirzaeian; Kourosh Shahriar; Mostafa Sharifzadeh

    2015-01-01

    In this paper tunnel probabilistic structural analysis (TuPSA) was performed using the first order reliability method (FORM). In TuPSA, a tunnel performance function is defined according to the boundary between the structural stability and instability. Then the performance function is transformed from original space into the standard normal variable space to obtain the design point, reliability index, and also the probability of tunnel failure. In this method, it is possible to consider the d...

  16. Time Correlation in Tunneling of Photons

    OpenAIRE

    Hrasko, Peter

    2000-01-01

    I propose to consider photon tunneling as a space-time correlation phenomenon between the emission and absorption of a photon on the two sides of a barrier. Standard technics based on an appropriate counting rate formula may then be applied to derive the tunneling time distribution without any {\\em ad hoc} definition of this quantity. General formulae are worked out for a potential model using Wigner-Weisskopf method. For a homogeneous square barrier in the limit of zero tunneling probability...

  17. Carpal tunnel syndrome caused by cysticercosis

    OpenAIRE

    Sharma S; Sharma Nalini; Yeolekar M

    2010-01-01

    We present a case of carpal tunnel syndrome (CTS) due to compression of the median nerve within the carpal tunnel, caused by cysticercosis. Nerve conduction studies revealed severe CTS. Magnetic resonance imaging suggested an inflammatory mass compressing the median nerve in carpal tunnel. The histological diagnosis was consistent with cysticercosis. The case resolved with conservative treatment. Such solitary presentation of entrapment median neuropathy as CTS caused by cysticercosis is extr...

  18. Electromyographic diagnosis of the carpal tunnel syndrome

    Directory of Open Access Journals (Sweden)

    K. Toyonaga

    1978-06-01

    Full Text Available Sensory conduction velocities of the median nerVe were studied from digit to palm and from palm to wrist in normal subjects and in patients with the carpal tunnel syndrome. Definite slowing was noted in the palm to wrist segment, even in the early carpal tunnel syndrome. It was noted that 37% of normal women over 40 years of age had electrophysiological evidence of the carpal tunnel syndrome.

  19. Resonant Tunneling in the Quantum Hydrodynamic Model

    OpenAIRE

    Carl L. Gardner

    1995-01-01

    The phenomenon of resonant tunneling is simulated and analyzed in the quantum hydrodynamic (QHD) model for semiconductor devices. Simulations of a parabolic well resonant tunneling diode at 77 K are presented which show multiple regions of negative differential resistance (NDR) in the current-voltage curve. These are the first simulations of the QHD equations to show multiple regions of NDR.Resonant tunneling (and NDR) depend on the quantum interference of electron wavefunctions and therefore...

  20. Tunneling anisotropic magnetoresistance in organic spin valves

    OpenAIRE

    Grünewald, M; M. Wahler; Schumann, F; Michelfeit, M.; Gould, C.; Schmidt, R.; Würthner, F.; Schmidt, G.; Molenkamp, L. W.

    2011-01-01

    We report the observation of tunneling anisotropic magnetoresistance (TAMR) in an organic spin-valve-like structure with only one ferromagnetic electrode. The device is based on a new high mobility perylene diimide-based n-type organic semiconductor. The effect originates from the tunneling injection from the LSMO contact and can thus occur even for organic layers which are too thick to support the assumption of tunneling through the layer. Magnetoresistance measurements show a clear spin-val...

  1. Wind-Tunnel/Flight Correlation, 1981

    Science.gov (United States)

    Mckinney, L. W. (Editor); Baals, D. D. (Editor)

    1982-01-01

    Wind-tunnel/flight correlation activities are reviewed to assure maximum effectiveness of the early experimental programs of the National Transonic Facility (NTF). Topics included a status report of the NTF, the role of tunnel-to-tunnel correlation, a review of past flight correlation research and the resulting data base, the correlation potential of future flight vehicles, and an assessment of the role of computational fluid dynamics.

  2. Joberget tunnel - Analysis of stability and support design for tunneling in soil

    OpenAIRE

    Langåker, Margrete Øie

    2014-01-01

    The Norwegian Public Roads Administration (NPRA) is planning a construction of a new road tunnel, Joberget tunnel in the Granvin Municipality of western Norway. Approximately 80 m from the southwestern entrance of the tunnel will be excavated, partly in soil and partly in rock. Soil tunneling will be performed in this section instead of excavation of large open cuts, to avoid difficult work conditions, landslide hazards and severe landscape interventions. Sweco Norge AS in cooperation with th...

  3. Femtosecond tunneling response of surface plasmon polaritons

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Ha, Taekjip; Jensen, Jacob Riis;

    1998-01-01

    We obtain femtosecond (200 fs) time resolution using a scanning tunneling microscope on surface plasmon polaritons (SPPs) generated by two 100 fs laser beams in total internal reflection geometry. The tunneling gap dependence of the signal clearly indicates the tunneling origin of the signal...... and suggests that nanometer spatial resolution can be obtained together with femtosecond temporal resolution. This fast response, in contrast to the picosecond decay time of SPPs revealed by differential reflectivity measurements, can be attributed to a coherent superposition of SPPs rectified at the tunneling...... junction. (C) 1998 American Institute of Physics. [S0003-6951(98)02223-2]....

  4. Electronic tunneling currents at optical frequencies

    Science.gov (United States)

    Faris, S. M.; Fan, B.; Gustafson, T. K.

    1975-01-01

    Rectification characteristics of nonsuperconducting metal-barrier-metal junctions as deduced from electronic tunneling theory have been observed experimentally for optical frequency irradiation of the junction.

  5. Fire safety assessment of tunnel structures

    DEFF Research Database (Denmark)

    Gkoumas, Konstantinos; Giuliani, Luisa; Petrini, Francesco;

    2011-01-01

    .g. structural and non structural, organizational, human behavior). This is even more truth for the fire safety design of such structures. Fire safety in tunnels is challenging because of the particular environment, bearing in mind also that a fire can occur in different phases of the tunnel’s lifecycle. Plans...... for upgrading fire safety provisions and tunnel management are also important for existing tunnels. In this study, following a brief introduction of issues regarding the above mentioned aspects, the structural performance of a steel rib for a tunnel infrastructure subject to fire is assessed by means...

  6. Tunneling Ionization Time Resolved by Backpropagation

    Science.gov (United States)

    Ni, Hongcheng; Saalmann, Ulf; Rost, Jan-Michael

    2016-07-01

    We determine the ionization time in tunneling ionization by an elliptically polarized light pulse relative to its maximum. This is achieved by a full quantum propagation of the electron wave function forward in time, followed by a classical backpropagation to identify tunneling parameters, in particular, the fraction of electrons that has tunneled out. We find that the ionization time is close to zero for single active electrons in helium and in hydrogen if the fraction of tunneled electrons is large. We expect our analysis to be essential to quantify ionization times for correlated electron motion.

  7. Tunneling into high-Tc superconductors: methods of fabricating tunnel junctions

    International Nuclear Information System (INIS)

    In the preprint we shell review some experimental results on electron tunneling into high-Tc superconductors. Pros and cons of various methods of fabricating the tunnel junctions with metal oxide compound as a base electrode are discussed. The data obtained by different groups are examined in terms of the tunneling criterion. 66 refs.; 13 figs

  8. Surgical efficacy of carpal tunnel release for carpal tunnel syndrome in acromegaly: report of four patients.

    Science.gov (United States)

    Iwasaki, N; Masuko, T; Ishikawa, J; Minami, A

    2005-12-01

    Although carpal tunnel syndrome is frequent in acromegaly, few acromegalics will be encountered by most hand surgeons. This paper considers the treatment of four cases of acromegaly in whom carpal tunnel syndrome arose, to discuss aspects of management of carpal tunnel syndrome in this patient group.

  9. Utilization of adenosine triphosphate in rat mast cells during histamine release induced by the ionophore A23187

    DEFF Research Database (Denmark)

    Johansen, Torben

    1979-01-01

    The role of endogenous adenosine triphosphate (ATP) in histamine release from rat mast cells induced by the ionophore A23187 in vitro has been studied. 2 The amount of histamine released by calcium from rat mast cells primed with the ionophore A23187 was dependent on the ATP content of the mast c...... cells. 3 In aerobic experiments a drastic reduction in mast cell ATP content was found during the time when histamine release induced by A23187 takes place. 4 Anaerobic experiments were performed with metabolic inhibitors (antimycin A, oligomycin, and carbonyl cyanide p......-trifluorometroxyphenylnydrazone), which are known to block the energy-dependent calcium uptake by isolated mitochondria. The mast cell ATP content was reduced during A23187-induced histamine release under anaerobic conditions in the presence of glucose. This indicates an increased utilization of ATP during the release process. 5...... The observations are consistent with the view that energy requiring processes are involved in ionophore-induced histamine release from rat mast cells although part of the ATP reduction in the aerobic experiments may be due to an uncoupling effect of calcium on the oxidative phosphorylation....

  10. Diagnostic value of adenosine-triphosphate radionuclide ventriculography in coronary artery disease. Comparison with conventional exercise stress method

    International Nuclear Information System (INIS)

    The purpose of this study was to assess the effect of adenosine-triphosphate (ATP) on hemodynamics and left ventricular (LV) function, and to examine the value of ATP radionuclide-ventriculography (RNVG) for detecting coronary artery disease (CAD) in comparison with standard exercise RNVG. Thirty-eight consecutive patients with suspected CAD underwent ATP (0.18 mg/Kg/min) RNVG and symptom-limited exercise RNVG. Coronary angiography revealed 27 patients with CAD (Group S) and 11 without CAD (Group N). In group S, exercise induced an increase in LV end-diastolic volume (LVEDV) and LV end-systolic volume (LVESV), and a decrease in LV ejection fraction (LVEF). In contrast, ATP infusion caused LVESV to decrease in both groups, improving LVEF. Only 14 of 39 segments whose wall motion was deteriorated by exercise showed worsening regional wall motion during ATP infusion. The sensitivity and specificity of ATP RNVG for detecting CAD were 22. 2% and 100%, while those of exercise RNVG were 77.8% and 81.8%, respectively. Although ATP induced a depression of peak filling rate in group S as compared with group N, the deterioration of systolic function was not apparent with this method. ATP RNVG was not adequate for detecting CAD because of its lower sensitivity compared with exercise RNVG. (author)

  11. Calcium and adenosine triphosphate control of cellular pathology: asparaginase-induced pancreatitis elicited via protease-activated receptor 2.

    Science.gov (United States)

    Peng, Shuang; Gerasimenko, Julia V; Tsugorka, Tatiana; Gryshchenko, Oleksiy; Samarasinghe, Sujith; Petersen, Ole H; Gerasimenko, Oleg V

    2016-08-01

    Exocytotic secretion of digestive enzymes from pancreatic acinar cells is elicited by physiological cytosolic Ca(2+) signals, occurring as repetitive short-lasting spikes largely confined to the secretory granule region, that stimulate mitochondrial adenosine triphosphate (ATP) production. By contrast, sustained global cytosolic Ca(2+) elevations decrease ATP levels and cause necrosis, leading to the disease acute pancreatitis (AP). Toxic Ca(2+) signals can be evoked by products of alcohol and fatty acids as well as bile acids. Here, we have investigated the mechanism by which l-asparaginase evokes AP. Asparaginase is an essential element in the successful treatment of acute lymphoblastic leukaemia, the most common type of cancer affecting children, but AP is a side-effect occurring in about 5-10% of cases. Like other pancreatitis-inducing agents, asparaginase evoked intracellular Ca(2+) release followed by Ca(2+) entry and also substantially reduced Ca(2+) extrusion because of decreased intracellular ATP levels. The toxic Ca(2+) signals caused extensive necrosis. The asparaginase-induced pathology depended on protease-activated receptor 2 and its inhibition prevented the toxic Ca(2+) signals and necrosis. We tested the effects of inhibiting the Ca(2+) release-activated Ca(2+) entry by the Ca(2+) channel inhibitor GSK-7975A. This markedly reduced asparaginase-induced Ca(2+) entry and also protected effectively against the development of necrosis.This article is part of the themed issue 'Evolution brings Ca(2+) and ATP together to control life and death'. PMID:27377732

  12. Campylobacter jejuni adenosine triphosphate phosphoribosyltransferase is an active hexamer that is allosterically controlled by the twisting of a regulatory tail.

    Science.gov (United States)

    Mittelstädt, Gerd; Moggré, Gert-Jan; Panjikar, Santosh; Nazmi, Ali Reza; Parker, Emily J

    2016-08-01

    Adenosine triphosphate phosphoribosyltransferase (ATP-PRT) catalyzes the first committed step of the histidine biosynthesis in plants and microorganisms. Here, we present the functional and structural characterization of the ATP-PRT from the pathogenic ε-proteobacteria Campylobacter jejuni (CjeATP-PRT). This enzyme is a member of the long form (HisGL ) ATP-PRT and is allosterically inhibited by histidine, which binds to a remote regulatory domain, and competitively inhibited by AMP. In the crystalline form, CjeATP-PRT was found to adopt two distinctly different hexameric conformations, with an open homohexameric structure observed in the presence of substrate ATP, and a more compact closed form present when inhibitor histidine is bound. CjeATP-PRT was observed to adopt only a hexameric quaternary structure in solution, contradicting previous hypotheses favoring an allosteric mechanism driven by an oligomer equilibrium. Instead, this study supports the conclusion that the ATP-PRT long form hexamer is the active species; the tightening of this structure in response to remote histidine binding results in an inhibited enzyme. PMID:27191057

  13. Influence of Thromboxane A2 on the Regulation of Adenosine Triphosphate-Sensitive Potassium Channels in Mouse Ventricular Myocytes

    Science.gov (United States)

    Jeong, In Seok; Cho, Hwa Jin; Cho, Jeong Gwan; Kim, Sang Hyung; Na, Kook Joo

    2016-01-01

    Background and Objectives Adenosine triphosphate (ATP)-sensitive potassium (KATP) channels play an important role in myocardial protection. We examined the effects of thromboxane A2 on the regulation of KATP channel activity in single ventricular myocytes. Subjects and Methods Single ventricular myocytes were isolated from the hearts of adult Institute of Cancer Research (ICR) mice by enzymatic digestion. Single channel activity was recorded by excised inside-out and cell-attached patch clamp configurations at −60 mV holding potential during the perfusion of an ATP-free K-5 solution. Results In the excised inside-out patches, the thromboxane A2 analog, U46619, decreased the KATP channel activity in a dose-dependent manner; however, the thromboxane A2 receptor antagonist, SQ29548, did not significantly attenuate the inhibitory effect of U46619. In the cell-attached patches, U46619 inhibited dinitrophenol (DNP)-induced KATP channel activity in a dose-dependent manner, and SQ29548 attenuated the inhibitory effects of U46619 on DNP-induced KATP channel activity. Conclusion Thromboxane A2 may inhibit KATP channel activity, and may have a harmful effect on ischemic myocardium. PMID:27482267

  14. Calcium and adenosine triphosphate control of cellular pathology: asparaginase-induced pancreatitis elicited via protease-activated receptor 2

    Science.gov (United States)

    Peng, Shuang; Gerasimenko, Julia V.; Tsugorka, Tatiana; Gryshchenko, Oleksiy; Samarasinghe, Sujith; Gerasimenko, Oleg V.

    2016-01-01

    Exocytotic secretion of digestive enzymes from pancreatic acinar cells is elicited by physiological cytosolic Ca2+ signals, occurring as repetitive short-lasting spikes largely confined to the secretory granule region, that stimulate mitochondrial adenosine triphosphate (ATP) production. By contrast, sustained global cytosolic Ca2+ elevations decrease ATP levels and cause necrosis, leading to the disease acute pancreatitis (AP). Toxic Ca2+ signals can be evoked by products of alcohol and fatty acids as well as bile acids. Here, we have investigated the mechanism by which l-asparaginase evokes AP. Asparaginase is an essential element in the successful treatment of acute lymphoblastic leukaemia, the most common type of cancer affecting children, but AP is a side-effect occurring in about 5–10% of cases. Like other pancreatitis-inducing agents, asparaginase evoked intracellular Ca2+ release followed by Ca2+ entry and also substantially reduced Ca2+ extrusion because of decreased intracellular ATP levels. The toxic Ca2+ signals caused extensive necrosis. The asparaginase-induced pathology depended on protease-activated receptor 2 and its inhibition prevented the toxic Ca2+ signals and necrosis. We tested the effects of inhibiting the Ca2+ release-activated Ca2+ entry by the Ca2+ channel inhibitor GSK-7975A. This markedly reduced asparaginase-induced Ca2+ entry and also protected effectively against the development of necrosis. This article is part of the themed issue ‘Evolution brings Ca2+ and ATP together to control life and death’. PMID:27377732

  15. Serine-324 of myosin's heavy chain is photoaffinity-labeled by 3'(2')-O-(4-benzoylbenzoyl)adenosine triphosphate

    International Nuclear Information System (INIS)

    A portion of the active site of rabbit skeletal myosin near the ribose ring of ATP can be labeled by the photoaffinity analogue 3'(2')-O-(4-benzoylbenzoyl)adenosine triphosphate (Bz2ATP). The specificity of the photolabeling was assured by first trapping [14C]Bz2ATP at the active site by use of thiol cross-linking agents. Five radioactive peptides were isolated by high-performance liquid chromatography after extensive trypsin and subtilisin digestion of photolabeled myosin subfragment 1. Four of these peptides were sequenced by Edman techniques, and all originated from a region with the sequence Gly-Glu-Ile-Thr-Val-Pro-Ser-Ile-Asp-Asp-Gln, which corresponds to rabbit myosin heavy chain residues 312-328. The fifth labeled peptide had an amino acid composition appropriate for residues 312-328. Amino acid composition, radiochemical analysis, and sequence data indicate that Ser-324 is the major amino acid residue photolabeled by Bz2ATP. Spectrophotometric evidence indicates that the benzophenone carbonyl group has inserted into a C-H bond from either the α- or β-carbon of serine. These results place Ser-324 at a distance of 6-7 angstrom from the 3'(2') ribose oxygens of ATP bound at the active site of myosin

  16. Upregulation of nucleoside triphosphate diphosphohydrolase-1 and ecto-5'-nucleotidase in rat hippocampus after repeated low-dose dexamethasone administration.

    Science.gov (United States)

    Drakulić, Dunja; Stanojlović, Miloš; Nedeljković, Nadežda; Grković, Ivana; Veličković, Nataša; Guševac, Ivana; Mitrović, Nataša; Buzadžić, Ivana; Horvat, Anica

    2015-04-01

    Although dexamethasone (DEX), a synthetic glucocorticoid receptor (GR) analog with profound effects on energy metabolism, immune system, and hypothalamic-pituitary-adrenal axis, is widely used therapeutically, its impact on the brain is poorly understood. The aim of the present study was to explore the effect of repeated low-dose DEX administration on the activity and expression of the ectonucleotidase enzymes which hydrolyze and therefore control extracellular ATP and adenosine concentrations in the synaptic cleft. Ectonucleotidases tested were ectonucleoside triphosphate diphosphohydrolase 1-3 (NTPDase1-3) and ecto-5'-nucleotidase (eN), whereas the effects were evaluated in two brain areas that show different sensitivity to glucocorticoid action, hippocampus, and cerebral cortex. In the hippocampus, but not in cerebral cortex, modest level of neurodegenerative changes as well as increase in ATP, ADP, and AMP hydrolysis and upregulation of NTPDase1 and eN mRNA expression ensued under the influence of DEX. The observed pattern of ectonucleotidase activation, which creates tissue volume with enhanced capacity for adenosine formation, is the hallmark of the response after different insults to the brain.

  17. Supplementation of exogenous adenosine 5'-triphosphate enhances mechanical properties of 3D cell-agarose constructs for cartilage tissue engineering.

    Science.gov (United States)

    Gadjanski, Ivana; Yodmuang, Supansa; Spiller, Kara; Bhumiratana, Sarindr; Vunjak-Novakovic, Gordana

    2013-10-01

    Formation of tissue-engineered cartilage is greatly enhanced by mechanical stimulation. However, direct mechanical stimulation is not always a suitable method, and the utilization of mechanisms underlying mechanotransduction might allow for a highly effective and less aggressive alternate means of stimulation. In particular, the purinergic, adenosine 5'-triphosphate (ATP)-mediated signaling pathway is strongly implicated in mechanotransduction within the articular cartilage. We investigated the effects of transient and continuous exogenous ATP supplementation on mechanical properties of cartilaginous constructs engineered using bovine chondrocytes and human mesenchymal stem cells (hMSCs) encapsulated in an agarose hydrogel. For both cell types, we have observed significant increases in equilibrium and dynamic compressive moduli after transient ATP treatment applied in the fourth week of cultivation. Continuous ATP treatment over 4 weeks of culture only slightly improved the mechanical properties of the constructs, without major changes in the total glycosaminoglycan (GAG) and collagen content. Structure-function analyses showed that transiently ATP-treated constructs, and in particular those based on hMSCs, had the highest level of correlation between compositional and mechanical properties. Transiently treated groups showed intense staining of the territorial matrix for GAGs and collagen type II. These results indicate that transient ATP treatment can improve functional mechanical properties of cartilaginous constructs based on chondrogenic cells and agarose hydrogels, possibly by improving the structural organization of the bulk phase and territorial extracellular matrix (ECM), that is, by increasing correlation slopes between the content of the ECM components (GAG, collagen) and mechanical properties of the construct.

  18. Light-driven artificial enzymes for selective oxidation of guanosine triphosphate using water-soluble POSS network polymers.

    Science.gov (United States)

    Jeon, Jong-Hwan; Tanaka, Kazuo; Chujo, Yoshiki

    2014-09-01

    The light-driven artificial enzymes were constructed to realize unnatural reactions concerning bio-significant molecules. In this manuscript, the guanosine triphosphate (GTP)-selective oxidation is reported using the network polymers composed of polyhedral oligomeric silsesquioxane (POSS). We synthesized the water-soluble POSS network polymer containing the naphthyridine ligands to capture GTP inside the networks and the ruthenium complexes to oxidize the captured GTP under light irradiation. Initially, the binding affinities of the guanosine nucleosides to the naphthyridine ligand inside the POSS network polymer were evaluated from the emission quenching experiments. Accordingly, it was observed that the naphthyridine ligand can form the stable complex only with GTP (K(a) = 5.5 × 10(6) M(-1)). These results indicate that only GTP can be captured by the network polymer. Next, the photo-catalytic activity of the ruthenium complex-modified POSS network polymer was investigated. Finally, it was revealed that the network polymer can decompose GTP efficiently under light irradiation. This is the first example, to the best of our knowledge, to offer not only the GTP-selective host polymers but also the light-driven artificial enzyme for GTP oxidation. PMID:25026217

  19. Adenosine triphosphate-competitive mTOR inhibitors: a new class of immunosuppressive agents that inhibit allograft rejection.

    Science.gov (United States)

    Rosborough, B R; Raïch-Regué, D; Liu, Q; Venkataramanan, R; Turnquist, H R; Thomson, A W

    2014-09-01

    The mechanistic/mammalian target of rapamycin (mTOR) is inhibited clinically to suppress T cell function and prevent allograft rejection. mTOR is the kinase subunit of two mTOR-containing complexes, mTOR complex (mTORC) 1 and 2. Although mTORC1 is inhibited by the macrolide immunosuppressant rapamycin (RAPA), its efficacy may be limited by its inability to block mTORC1 completely and its limited effect on mTORC2. Adenosine triphosphate (ATP)-competitive mTOR inhibitors are an emerging class of mTOR inhibitors that compete with ATP at the mTOR active site and inhibit any mTOR-containing complex. Since this class of compounds has not been investigated for their immunosuppressive potential, our goal was to determine the influence of a prototypic ATP-competitive mTOR inhibitor on allograft survival. AZD8055 proved to be a potent suppressor of T cell proliferation. Moreover, a short, 10-day course of the agent successfully prolonged murine MHC-mismatched, vascularized heart transplant survival. This therapeutic effect was associated with increased graft-infiltrating regulatory T cells and reduced CD4(+) and CD8(+) T cell interferon-γ production. These studies establish for the first time, that ATP-competitive mTOR inhibition can prolong organ allograft survival and warrant further investigation of this next generation mTOR inhibitors. PMID:25307040

  20. Binding of Mn-deoxyribonucleoside Triphosphates to the Active Site of the DNA Polymerase of Bacteriophage T7

    Energy Technology Data Exchange (ETDEWEB)

    B Akabayov; C Richardson

    2011-12-31

    Divalent metal ions are crucial as cofactors for a variety of intracellular enzymatic activities. Mg{sup 2+}, as an example, mediates binding of deoxyribonucleoside 5'-triphosphates followed by their hydrolysis in the active site of DNA polymerase. It is difficult to study the binding of Mg{sup 2+} to an active site because Mg{sup 2+} is spectroscopically silent and Mg{sup 2+} binds with low affinity to the active site of an enzyme. Therefore, we substituted Mg{sup 2+} with Mn{sup 2+}:Mn{sup 2+} that is not only visible spectroscopically but also provides full activity of the DNA polymerase of bacteriophage T7. In order to demonstrate that the majority of Mn{sup 2+} is bound to the enzyme, we have applied site-directed titration analysis of T7 DNA polymerase using X-ray near edge spectroscopy. Here we show how X-ray near edge spectroscopy can be used to distinguish between signal originating from Mn{sup 2+} that is free in solution and Mn{sup 2+} bound to the active site of T7 DNA polymerase. This method can be applied to other enzymes that use divalent metal ions as a cofactor.

  1. Leishmania (Viannia) braziliensis nucleoside triphosphate diphosphohydrolase (NTPDase 1): localization and in vitro inhibition of promastigotes growth by polyclonal antibodies.

    Science.gov (United States)

    Porcino, Gabriane Nascimento; Carvalho-Campos, Cristiane; Maia, Ana Carolina Ribeiro Gomes; Detoni, Michelle Lima; Faria-Pinto, Priscila; Coimbra, Elaine Soares; Marques, Marcos José; Juliano, Maria Aparecida; Juliano, Luiz; Diniz, Vanessa Álvaro; Corte-Real, Suzana; Vasconcelos, Eveline Gomes

    2012-10-01

    Nucleoside triphosphate diphosphohydrolase (NTPDase) activity was recently characterized in Leishmania (Viannia) braziliensis promastigotes (Lb), and an antigenic conserved domain (r82-121) from the specific NTPDase 1 isoform was identified. In this work, mouse polyclonal antibodies produced against two synthetic peptides derived from this domain (LbB1LJ, r82-103; LbB2LJ, r102-121) were used. The anti-LbB1LJ or anti-LbB2LJ antibodies were immobilized on protein A-sepharose and immunoprecipitated the NTPDase 1 of 48 kDa and depleted approximately 40% of the phosphohydrolytic activity from detergent-homogenized Lb preparation. Ultrastructural immunocytochemical microscopy identified the NTPDase 1 on the parasite surface and in its subcellular cytoplasmic vesicles, mitochondria, kinetoplast and nucleus. The ATPase and ADPase activities of detergent-homogenized Lb preparation were partially inhibited by anti-LbB1LJ antibody (43-79%), which was more effective than that inhibition (18-47%) by anti-LbB2LJ antibody. In addition, the immune serum anti-LbB1LJ (67%) or anti-LbB2LJ (33%) was cytotoxic, significantly reducing the promastigotes growth in vitro. The results appoint the conserved domain from the L. braziliensis NTPDase as an important target for inhibitor design and the potential application of these biomolecules in experimental protocols of disease control. PMID:22921497

  2. Interfering with bacterial gossip

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Tolker-Nielsen, Tim; Givskov, Michael

    2011-01-01

    defense. Antibiotics exhibit a rather limited effect on biofilms. Furthermore, antibiotics have an ‘inherent obsolescence’ because they select for development of resistance. Bacterial infections with origin in bacterial biofilms have become a serious threat in developed countries. Pseudomonas aeruginosa...... that appropriately target bacteria in their relevant habitat with the aim of mitigating their destructive impact on patients. In this review we describe molecular mechanisms involved in “bacterial gossip” (more scientifically referred to as quorum sensing (QS) and c-di-GMP signaling), virulence, biofilm formation...

  3. Application of Adenosine Triphosphate Affinity Probe and Scheduled Multiple-Reaction Monitoring Analysis for Profiling Global Kinome in Human Cells in Response to Arsenite Treatment

    OpenAIRE

    Guo, Lei; Xiao, Yongsheng; Wang, Yinsheng

    2014-01-01

    Phosphorylation of cellular components catalyzed by kinases plays important roles in cell signaling and proliferation. Quantitative assessment of perturbation in global kinome may provide crucial knowledge for elucidating the mechanisms underlying the cytotoxic effects of environmental toxicants. Here, we utilized an adenosine triphosphate (ATP) affinity probe coupled with stable isotope labeling by amino acids in cell culture (SILAC) to assess quantitatively the arsenite-induced alteration o...

  4. Adenosine 5 '-triphosphate (ATP) supplements are not orally bioavailable: a randomized, placebo-controlled cross-over trial in healthy humans

    OpenAIRE

    Arts Ilja CW; Coolen Erik JCM; Bours Martijn JL; Huyghebaert Nathalie; Stuart Martien A; Bast Aalt; Dagnelie Pieter C

    2012-01-01

    Abstract Background Nutritional supplements designed to increase adenosine 5′-triphosphate (ATP) concentrations are commonly used by athletes as ergogenic aids. ATP is the primary source of energy for the cells, and supplementation may enhance the ability to maintain high ATP turnover during high-intensity exercise. Oral ATP supplements have beneficial effects in some but not all studies examining physical performance. One of the remaining questions is whether orally administered ATP is bioav...

  5. More about tunnelling times and superluminal tunnelling (Hartmann effect)

    International Nuclear Information System (INIS)

    Aims of the present paper are: i) presenting and analysing the results of various numerical calculations on the penetration and return times Pen>, Ret>, during tunnelling inside a rectangular potential barrier, for various penetration depths xf; ii) putting forth and discussing suitable definitions, besides of the mean values, also of the variances (or dispersions) DτT and DτR for the time durations of transmission and reflection processes; iii)mentioning, moreover, that our definition T> for the average transmission time results to constitute an improvement of the ordinary dwell- time formula; iv) commenting, at last, on the basis of the new numerical results, upon some recent criticism by C.R. Leavens. The paper stresses that numerical evaluations confirm that the approach implied, and implies, the existence of the Hartmann effect: an effect that in these days (due to the theoretical connections between tunnelling and evanescent-wave propagation) is receiving - at Cologne, Berkeley, Florence and Vienna - indirect, but quite interesting, experimental verification

  6. Quantum tunnelling in condensed media

    CERN Document Server

    Kagan, Yu

    1992-01-01

    The essays in this book deal with of the problem of quantum tunnelling and related behavior of a microscopic or macroscopic system, which interacts strongly with an ""environment"" - this being some form of condensed matter. The ""system"" in question need not be physically distinct from its environment, but could, for example, be one particular degree of freedom on which attention is focussed, as in the case of the Josephson junction studied in several of the papers. This general problem has been studied in many hundreds, if not thousands, of articles in the literature, in contexts as diverse

  7. Quantum Tunneling Beyond Semiclassical Approximation

    CERN Document Server

    Banerjee, Rabin

    2008-01-01

    Hawking radiation as tunneling by Hamilton-Jacobi method beyond semiclassical approximation is analysed. We compute all quantum corrections in the single particle action revealing that these are proportional to the usual semiclassical contribution. We show that a simple choice of the proportionality constants reproduces the one loop back reaction effect in the spacetime, found by conformal field theory methods, which modifies the Hawking temperature of the black hole. Using the law of black hole mechanics we give the corrections to the Bekenstein-Hawking area law following from the modified Hawking temperature. Some examples are explicitly worked out.

  8. Quantum tunneling beyond semiclassical approximation

    Science.gov (United States)

    Banerjee, Rabin; Ranjan Majhi, Bibhas

    2008-06-01

    Hawking radiation as tunneling by Hamilton-Jacobi method beyond semiclassical approximation is analysed. We compute all quantum corrections in the single particle action revealing that these are proportional to the usual semiclassical contribution. We show that a simple choice of the proportionality constants reproduces the one loop back reaction effect in the spacetime, found by conformal field theory methods, which modifies the Hawking temperature of the black hole. Using the law of black hole mechanics we give the corrections to the Bekenstein-Hawking area law following from the modified Hawking temperature. Some examples are explicitly worked out.

  9. Fermion Tunneling Beyond Semiclassical Approximation

    CERN Document Server

    Majhi, Bibhas Ranjan

    2008-01-01

    Applying the Hamilton-Jacobi method beyond the semiclassical approximation prescribed in \\cite{Majhi3} for the scalar particle, Hawking radiation as tunneling of Dirac particle through an event horizon is analysed. We show that, as before, all quantum corrections in the single particle action are proportional to the usual semiclassical contribution. We also compute the modifications to the Hawking temperature and Bekenstein-Hawking entropy for the Schwarzschild black hole. Finally, the coefficient of the logarithmic correction to entropy is shown to be related with the trace anomaly.

  10. Fermion tunneling beyond semiclassical approximation

    Science.gov (United States)

    Majhi, Bibhas Ranjan

    2009-02-01

    Applying the Hamilton-Jacobi method beyond the semiclassical approximation prescribed in R. Banerjee and B. R. Majhi, J. High Energy Phys.JHEPFG1029-8479 06 (2008) 09510.1088/1126-6708/2008/06/095 for the scalar particle, Hawking radiation as tunneling of the Dirac particle through an event horizon is analyzed. We show that, as before, all quantum corrections in the single particle action are proportional to the usual semiclassical contribution. We also compute the modifications to the Hawking temperature and Bekenstein-Hawking entropy for the Schwarzschild black hole. Finally, the coefficient of the logarithmic correction to entropy is shown to be related with the trace anomaly.

  11. Tunneling without barriers with gravity

    OpenAIRE

    Kanno, Sugumi; Sasaki, Misao; Soda, Jiro

    2012-01-01

    We consider the vacuum decay of the flat Minkowski space to an anti-de Sitter space. We find a one-parameter family of potentials that allow exact, analytical instanton solutions describing tunneling without barriers in the presence of gravity. In the absence of gravity such instantons were found and discussed by Lee and Weinberg more than a quarter of a century ago. The bounce action is also analytically computed. We discuss possible implications of these new instantons to cosmology in the c...

  12. Chemically driven electron tunnelling pumps

    CERN Document Server

    Goychuk, I

    2006-01-01

    The simplest mechanism for molecular electron pumps is discussed which is based on nonadiabatic electron tunnelling and nonequilibrium conformational fluctuations. Such fluctuations can be induced, e.g. by random binding of negatively charged ATP molecules to the electron-transferring molecular complex, their subsequent hydrolysis and the products dissociation. The pumping rate can be controlled by the ATP concentration in solution. Depending on the model parameters there may exist a critical ATP concentration for the pump to function. Alternatively, nonequilibrium fluctuations can be induced by externally applied stochastic electric fields. For realistically chosen parameters, the mechanism is shown to be robust and highly efficient.

  13. Crystal structure of Escherichia coli cytidine triphosphate synthetase, a nucleotide-regulated glutamine amidotransferase/ATP-dependent amidoligase fusion protein and homologue of anticancer and antiparasitic drug targets.

    Science.gov (United States)

    Endrizzi, James A; Kim, Hanseong; Anderson, Paul M; Baldwin, Enoch P

    2004-06-01

    Cytidine triphosphate synthetases (CTPSs) produce CTP from UTP and glutamine, and regulate intracellular CTP levels through interactions with the four ribonucleotide triphosphates. We solved the 2.3-A resolution crystal structure of Escherichia coli CTPS using Hg-MAD phasing. The structure reveals a nearly symmetric 222 tetramer, in which each bifunctional monomer contains a dethiobiotin synthetase-like amidoligase N-terminal domain and a Type 1 glutamine amidotransferase C-terminal domain. For each amidoligase active site, essential ATP- and UTP-binding surfaces are contributed by three monomers, suggesting that activity requires tetramer formation, and that a nucleotide-dependent dimer-tetramer equilibrium contributes to the observed positive cooperativity. A gated channel that spans 25 A between the glutamine hydrolysis and amidoligase active sites provides a path for ammonia diffusion. The channel is accessible to solvent at the base of a cleft adjoining the glutamine hydrolysis active site, providing an entry point for exogenous ammonia. Guanine nucleotide binding sites of structurally related GTPases superimpose on this cleft, providing insights into allosteric regulation by GTP. Mutations that confer nucleoside drug resistance and release CTP inhibition map to a pocket that neighbors the UTP-binding site and can accommodate a pyrimidine ring. Its location suggests that competitive feedback inhibition is affected via a distinct product/drug binding site that overlaps the substrate triphosphate binding site. Overall, the E. coli structure provides a framework for homology modeling of other CTPSs and structure-based design of anti-CTPS therapeutics. PMID:15157079

  14. Bacterial Wound Culture

    Science.gov (United States)

    ... Home Visit Global Sites Search Help? Bacterial Wound Culture Share this page: Was this page helpful? Also known as: Aerobic Wound Culture; Anaerobic Wound Culture Formal name: Culture, wound Related ...

  15. Bacterial surface adaptation

    Science.gov (United States)

    Utada, Andrew

    2014-03-01

    Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

  16. Bacterial intermediate filaments

    DEFF Research Database (Denmark)

    Charbon, Godefroid; Cabeen, M.; Jacobs-Wagner, C.

    2009-01-01

    Crescentin, which is the founding member of a rapidly growing family of bacterial cytoskeletal proteins, was previously proposed to resemble eukaryotic intermediate filament (IF) proteins based on structural prediction and in vitro polymerization properties. Here, we demonstrate that crescentin...

  17. Bacterial Meningitis in Infants

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-04-01

    Full Text Available A retrospective study of 80 infantile patients (ages 30-365 days; 47 male, 33 female with culture-proven bacterial meningitis seen over a 16 year period (1986-2001 is reported from Taiwan.

  18. Crystal Structure of Escherichia coli Cytidine Triphosphate Synthetase, a Nucleotide-Regulated Glutamine Amidotransferase/ATP-Dependent Amidoligase Fusion Protein and Homologue of Anticancer and Antiparasitic Drug Targets†,‡

    OpenAIRE

    Endrizzi, James A.; Kim, Hanseong; Anderson, Paul M; Baldwin, Enoch P.

    2004-01-01

    Cytidine triphosphate synthetases (CTPSs) produce CTP from UTP and glutamine, and regulate intracellular CTP levels through interactions with the four ribonucleotide triphosphates. We solved the 2.3-Å resolution crystal structure of Escherichia coli CTPS using Hg-MAD phasing. The structure reveals a nearly symmetric 222 tetramer, in which each bifunctional monomer contains a dethiobiotin synthetase-like amidoligase N-terminal domain and a Type 1 glutamine amidotransferase C-terminal domain. F...

  19. Computational Wind Tunnel: A Design Tool for Rotorcraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Rotorcraft engineers traditionally use the wind tunnel to evaluate and finalize designs. Insufficient correlation between wind tunnel results and flight tests, have...

  20. Road tunnels safety according to European legislation

    Directory of Open Access Journals (Sweden)

    Fedor KÁLLAY

    2008-01-01

    Full Text Available The article deals with safety of European road tunnels in accordance with actual European legislation. Standards and recommendations of European Commission, PIARC and other professional bodies of the European Union define minimal technological requirements for equipment and operation of the tunnels in scope of Trans-European Road Network.

  1. Transport of dangerous goods through road tunnels

    DEFF Research Database (Denmark)

    Jørgensen, N O; Lacroix, Didier; Amundsen, F.H.;

    1999-01-01

    A paper which describes the work of an OECD research group. The group has suggested a grouping of dangerous materials, a quantitative risk assessment model and a decision support model which should allow tunnel operators to determine if a given material should be allowed throug a given tunnel...

  2. Flow-Based Detection of DNS Tunnels

    NARCIS (Netherlands)

    W. Ellens; P. Żuraniewski; A. Sperotto; H. Schotanus; M. Mandjes; E. Meeuwissen

    2013-01-01

    DNS tunnels allow circumventing access and security policies in firewalled networks. Such a security breach can be misused for activities like free web browsing, but also for command & control traffic or cyber espionage, thus motivating the search for effective automated DNS tunnel detection techniq

  3. 75 FR 42643 - National Tunnel Inspection Standards

    Science.gov (United States)

    2010-07-22

    ..., the repairs helped prevent a potential safety incident. A preliminary tunnel survey conducted in 2003... Advance Notice of Proposed Rulemaking (ANPRM) The FHWA issued an ANPRM on November 18, 2008, at 73 FR... approach would address the inspection needs of geotechnical aspects of a tunnel. The Massachusetts...

  4. Hawking temperature and higher order tunnelling calculations

    CERN Document Server

    Chatterjee, Bhramar

    2009-01-01

    Hawking radiation has recently been explained in terms of tunnelling across the black hole horizon in a Hamilton-Jacobi framework. Higher order calculations using both usual and non-singular coordinates are found to change the tunnelling amplitude, but this change is not a simple alteration of the Hawking temperature.

  5. A Supermagnetic Tunnel Full of Subatomic Action

    CERN Multimedia

    2008-01-01

    Last year, before the gigantic hadron supercollider at CERN research facility was installed underground, a photographer captured this picture of a 1,950 metric ton tunnel containing giant magnets that will be placed in a tunnel and kept at near-zero temperatures.

  6. Prediction of swelling rocks strain in tunneling

    Science.gov (United States)

    Parsapour, D.; Fahimifar, A.

    2016-05-01

    Swelling deformations leading to convergence of tunnels may result in significant difficulties during the construction, in particular for long term use of tunnels. By extracting an experimental based explicit analytical solution for formulating swelling strains as a function of time and stress, swelling strains are predicted from the beginning of excavation and during the service life of tunnel. Results obtained from the analytical model show a proper agreement with experimental results. This closed-form solution has been implemented within a numerical program using the finite element method for predicting time-dependent swelling strain around tunnels. Evaluating effects of swelling parameters on time-dependent strains and tunnel shape on swelling behavior around the tunnel according to this analytical solution is considered. The ground-support interaction and consequent swelling effect on the induced forces in tunnel lining is considered too. Effect of delay in lining installation on swelling pressure which acting on the lining and its structural integrity, is also evaluated. A MATLAB code of " SRAP" is prepared and applied to calculate all swelling analysis around tunnels based on analytical solution.

  7. 49 CFR 177.810 - Vehicular tunnels.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vehicular tunnels. 177.810 Section 177.810 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY... Information and Regulations § 177.810 Vehicular tunnels. Except as regards Class 7 (radioactive)...

  8. Ac electronic tunneling at optical frequencies

    Science.gov (United States)

    Faris, S. M.; Fan, B.; Gustafson, T. K.

    1974-01-01

    Rectification characteristics of non-superconducting metal-barrier-metal junctions deduced from electronic tunneling have been observed experimentally for optical frequency irradiation of the junction. The results provide verification of optical frequency Fermi level modulation and electronic tunneling current modulation.

  9. Tunnel number one, genus one fibered knots

    OpenAIRE

    Baker, Kenneth L.; Johnson, Jesse E.; Klodginski, Elizabeth A.

    2006-01-01

    We determine the genus one fibered knots in lens spaces that have tunnel number one. We also show that every tunnel number one, once-punctured torus bundle is the result of Dehn filling a component of the Whitehead link in the 3-sphere.

  10. Chronic Synovitis after Open Carpal Tunnel Decompression.

    Science.gov (United States)

    Yousef, Justin; Chan, Patrick; Rahdon, Richard

    2016-06-01

    Open carpal tunnel decompression is a common procedure with potential long-term complications such as scar tenderness, pillar pain and neuroma. We present the case of a 65 year-old male with chronic lipomatous hypertrophy of the wrist and chronic flexor tenosynovitis after open carpal tunnel release for its rarity and severity of symptoms that required further surgery. PMID:27454645

  11. Ultrasonographic assessment of carpal tunnel biomechanics

    NARCIS (Netherlands)

    van Doesburg, M.H.M.

    2012-01-01

    In this thesis, we searched for a way to assess flexor tendon and median nerve biomechanics, as well as subsynovial connective tissue thickness (SSCT) in the carpal tunnel with ultrasound, and tried to see if these patterns would give a clue towards understanding the etiology of carpal tunnel syndro

  12. Superconducting Super Collider Laboratory : tunnel boring

    CERN Multimedia

    SSC Media Production

    1999-01-01

    This film will take you down into the tunnel, show you the technology involved in boring the tunnel, and show what the SSC fmeans to the U.S. in terms of scientific discovery, innovative collaborations with industry and stimulating the job base nation-wide.

  13. Flapping around in a wind tunnel

    OpenAIRE

    Dimitriadis, Grigorios

    2015-01-01

    Aerodynamic investigations of animal flight have usually concentrated on static conditions. These are good enough to analyse gliding flight but not other types of flight, such as cruise (migrations), take-off and landing or manoeuvres. In this work we present wind tunnel experiments on geese flying in a wind tunnel and unsteady aerodynamic simulations of these flights, based on the Vortex Lattice Method.

  14. Flow-based detection of DNS tunnels

    NARCIS (Netherlands)

    Ellens, W.; Zuraniewski, P.W.; Sperotto, A.; Schotanus, H.A.; Mandjes, M.; Meeuwissen, H.B.

    2013-01-01

    DNS tunnels allow circumventing access and security policies in firewalled networks. Such a security breach can be misused for activities like free web browsing, but also for command & control traffic or cyber espionage, thus motivating the search for effective automated DNS tunnel detection techniq

  15. Tunnel widening in anterior cruciate ligament reconstruction

    DEFF Research Database (Denmark)

    Clatworthy, M G; Annear, P; Bulow, J U;

    1999-01-01

    We report a prospective series evaluating the incidence and degree of tunnel widening in a well-matched series of patients receiving a hamstring or patella tendon graft for anterior cruciate ligament (ACL) deficiency. We correlated tunnel widening with clinical factors, knee scores, KT-1000...

  16. Hydrogen tunneling in enzyme reactions

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Y.; Murray, C.J.; Klinman, J.P.

    1989-03-10

    Primary and secondary protium-to-tritium (H/T) and deuterium-to-tritium (D/T) kinetic isotope effects for the catalytic oxidation of benzyl alcohol to benzaldehyde by yeast alcohol dehydrogenase (YADH) at 25 degrees Celsius have been determined. Previous studies showed that this reaction is nearly or fully rate limited by the hydrogen-transfer step. Semiclassical mass considerations that do not include tunneling effects would predict that kH/kT = (kD/kT)3.26, where kH, kD, and kT are the rate constants for the reaction of protium, deuterium, and tritium derivatives, respectively. Significant deviations from this relation have now been observed for both primary and especially secondary effects, such that experimental H/T ratios are much greater than those calculated from the above expression. These deviations also hold in the temperature range from 0 to 40 degrees Celsius. Such deviations were previously predicted to result from a reaction coordinate containing a significant contribution from hydrogen tunneling.

  17. Hydrogen Tunneling in Enzyme Reactions

    Science.gov (United States)

    Cha, Yuan; Murray, Christopher J.; Klinman, Judith P.

    1989-03-01

    Primary and secondary protium-to-tritium (H/T) and deuterium-to-tritium (D/T) kinetic isotope effects for the catalytic oxidation of benzyl alcohol to benzaldehyde by yeast alcohol dehydrogenase (YADH) at 25 degrees Celsius have been determined. Previous studies showed that this reaction is nearly or fully rate limited by the hydrogen-transfer step. Semiclassical mass considerations that do not include tunneling effects would predict that kH/kT = (kD/kT)3.26, where kH, kD, and kT are the rate constants for the reaction of protium, deuterium, and tritium derivatives, respectively. Significant deviations from this relation have now been observed for both primary and especially secondary effects, such that experimental H/T ratios are much greater than those calculated from the above expression. These deviations also hold in the temperature range from 0 to 40 degrees Celsius. Such deviations were previously predicted to result from a reaction coordinate containing a significant contribution from hydrogen tunneling.

  18. Gauge independence of tunneling rates

    CERN Document Server

    Plascencia, Alexis D

    2015-01-01

    Despite the gauge dependence of the effective action at zero and finite temperature, it is shown that it leads to tunneling and nucleation rates that remain independent of the choice of gauge-fixing. Taking as a starting point the path integral that defines the transition amplitude from a false vacuum to itself, a careful treatment of the boundary conditions and the gauge-fixing allows to show that decay rates are exactly determined by the effective action evaluated at a generalized bounce configuration. The latter is a solution to the quantum equations of motion, with boundary conditions fixed by the false vacuum. The resulting tunneling rate is gauge-independent, as the Nielsen identities imply that the explicit gauge dependence in the effective action is exactly cancelled by the gauge dependence of the solution. This holds for any election of gauge-fixing that leads to an invertible Faddeev-Popov matrix. The result is nonperturbative and model-independent, and also clarifies how to incorporate radiative co...

  19. Temporary closure of the tunnel

    CERN Document Server

    Relations with the Host States Service

    2005-01-01

    Owing to major maintenance work, the tunnel linking the various parts of the CERN site will be closed from Monday 4 July to Sunday 24 July 2005 The Host State authorities have given authorisation for persons employed by CERN or the Institutes to travel and for goods belonging to these entities to be transported between the various parts of the site via Gate E (Charles de Gaulle) while this work is being carried out, subject to strict compliance with the Rules for the Use of the Tunnel (see http://dsu.web.cern.ch/dsu/dsum/hsr/DOCUMENTS/8200980415.pdf). Gate E will thus be open between 7.00 a.m. and 7.00 p.m. from Monday to Friday during the period concerned. The rules governing the use of Gate E to enter the Meyrin site between 7.30 a.m. and 9.00 a.m. or to leave the site between 5.00 p.m. and 6.30 p.m. (see http://dsu.web.cern.ch/dsu/dsum/hsr/DOCUMENTS/12222_041027.pdf)) will remain unaffected by this temporary authorisation. Relations with the Host States Service and TS-FM Group

  20. Control of tunneling by adapted signals

    CERN Document Server

    Ivlev, B I

    2000-01-01

    Process of quantum tunneling of particles in various physical systems can be effectively controlled even by a weak and slow varying in time electromagnetic signal if to adapt specially its shape to a particular system. During an under-barrier motion of a particle such signal provides a "coherent" assistance of tunneling by the multi-quanta absorption resulting in a strong enhancement of the tunneling probability. The semiclassical approach based on trajectories in the complex time is developed for tunneling in a non-stationary field. Enhancement of tunneling occurs when a singularity of the signal coincides in position at the complex time plane with a singularity of the classical Newtonian trajectory of the particle. The developed theory is also applicable to the over-barrier reflection of particles and to reflection of classical waves (electromagnetic, hydrodynamic, etc.) from a spatially-smooth medium.

  1. Detecting DNS Tunnels Using Character Frequency Analysis

    CERN Document Server

    Born, Kenton

    2010-01-01

    High-bandwidth covert channels pose significant risks to sensitive and proprietary information inside company networks. Domain Name System (DNS) tunnels provide a means to covertly infiltrate and exfiltrate large amounts of information passed network boundaries. This paper explores the possibility of detecting DNS tunnels by analyzing the unigram, bigram, and trigram character frequencies of domains in DNS queries and responses. It is empirically shown how domains follow Zipf's law in a similar pattern to natural languages, whereas tunneled traffic has more evenly distributed character frequencies. This approach allows tunnels to be detected across multiple domains, whereas previous methods typically concentrate on monitoring point to point systems. Anomalies are quickly discovered when tunneled traffic is compared to the character frequency fingerprint of legitimate domain traffic.

  2. Snow and ice blocking of tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Lia, Leif

    1998-12-31

    Hydroelectric power development in cold regions causes much concern about operational reliability and dam safety. This thesis studies the temperature distribution in tunnels by means of air temperature measurements in six tunnel spillways and five diversion tunnels. The measurements lasted for two consecutive winters. The air through flow tunnel is used as it causes cooling of both rock and water. In open spillway tunnels, frost reaches the entire tunnel. In spillway tunnels with walls, the frost zones reach about 100 m from the downstream end. In mildly-inclined diversion tunnels, a frost free zone is located in the middle of the tunnel and snow and ice problems were only observed in the inlet and outlet. Severe aufeis is accumulation is observed in the frost zones. The heat transfer from rock to air, water and ice is calculated and used in a prediction model for the calculation of aufeis build-up together with local field observation data. The water penetration of snow plugs is also calculated, based on the heat balance. It takes 20 to 50 days for water to enter the blocked tunnel. The empirical values are 30 to 60 days, but only 1 day if the temperature of the snow pack is 0{sup o}C. Sensitivity analyses are carried out for temperature variations in rock, snow, water and ice. Systematic field observation shows that it is important for hydropower companies to know about the effects of snow and ice blocking in an area. A risk analysis of dam safety is presented for a real case. Finally, the thesis proposes solutions which can reduce the snow and ice problems. 79 refs., 63 figs., 11 tabs.

  3. Analysis of Blast Wave Propagation Inside Tunnel

    Institute of Scientific and Technical Information of China (English)

    LIU Jingbo; YAN Qiushi; WU Jun

    2008-01-01

    The explosion inside tunnel would generate blast wave which transmits through the longi tudinal tunnel.Because of the close-in effects of the tunnel and the reflection by the confining tunnel structure,blast wave propagation inside tunnel is distinguished from that in air.When the explosion happens inside tunnel,the overpressure peak is higher than that of explosion happening in air.The continuance time of the biast wave also becomes longer.With the help of the numerical simu lation finite element software LS-DYNA.a three-dimensional nonlinear dynamic simulation analysis for an explosion experiment inside tunnel was carried out.LS-DYNA is a fully integrated analysis program specifically designed for nonlinear dynamics and large strain problems.Compared with the experimental results.the simulation results have made the material parameters of numerical simulation model available.By using the model and the same material parameters,many results were adopted by calculating the model under different TNT explosion dynamites.Then the method of dimensional analysis was Used for the Simulation resufts.AS Overpressures of the explosion biast wave are the governing factor in fhe tunnel responses.a formula for the explosion biast wave overpressure at a certain distance from the detonation center point inside the tunnel was de rived by using the dimensional analysis theory.By cornparing the results computed by the fromula with experimental results which were obtained before.the formula was proved to be very applicable at some instance.The research may be helpful to estimate rapidly the effect of internal explosion of tunnel on the structure.

  4. Effects of diesel exhaust on the microbiota within a tuffaceous tunnel system

    International Nuclear Information System (INIS)

    The abundance and distribution of microbiota that may be impacted by diesel and diesel exhaust were investigated from three depths into the walls and invert (floor) of U12n tunnel at Rainier Mesa, Nevada Test Site, a potential geological analog of Yucca Mountain. Enumerations included total cell counts, and numbers of aerobic heterotrophic, sulfate-reducing, nitrate-reducing, and diesel-degrading bacteria. Additionally, the disappearance of total petroleum hydrocarbons was determined in microcosms containing subsurface materials that were amended with diesel fuel. Results revealed that microbes capable of utilizing diesel and diesel combustion products were present in the subsurface in both the walls and the invert of the tunnel. The abundance of specific bacterial types in the tunnel invert, a perturbed environment, was greater than that observed in the tunnel wall. Few trends of microbial distribution either into the tunnel wall or the invert were noted with the exception of aerobic heterotrophic abundance which increased with depth into the wall and decreased with depth into the invert. No correlation between microbiota and a specific introduced chemical species have yet been determined. The potential for microbial contamination of the tunnel wall during sampling was determined to be negligible by the use of fluorescently labeled latex spheres (1μm in dia.) as tracers. Results indicate that additional investigations might be needed to examine the microbiota and their possible impacts on the geology and geochemistry of the subsurface, both indigenous microbiota and those microorganisms that will likely be introduced by anthropogenic activity associated with the construction of a high-level waste repository

  5. Effects of diesel exhaust on the microbiota within a tuffaceous tunnel system

    Energy Technology Data Exchange (ETDEWEB)

    Haldeman, D.L.; Lagadinos, T.; Amy, P.S. [Univ. of Nevada, Las Vegas, NV (United States); Hersman, L. [Los Alamos National Lab., NM (United States); Meike, A. [Lawrence Livermore National Lab., Livermore, CA (United States)

    1996-08-01

    The abundance and distribution of microbiota that may be impacted by diesel and diesel exhaust were investigated from three depths into the walls and invert (floor) of U12n tunnel at Rainier Mesa, Nevada Test Site, a potential geological analog of Yucca Mountain. Enumerations included total cell counts, and numbers of aerobic heterotrophic, sulfate-reducing, nitrate-reducing, and diesel-degrading bacteria. Additionally, the disappearance of total petroleum hydrocarbons was determined in microcosms containing subsurface materials that were amended with diesel fuel. Results revealed that microbes capable of utilizing diesel and diesel combustion products were present in the subsurface in both the walls and the invert of the tunnel. The abundance of specific bacterial types in the tunnel invert, a perturbed environment, was greater than that observed in the tunnel wall. Few trends of microbial distribution either into the tunnel wall or the invert were noted with the exception of aerobic heterotrophic abundance which increased with depth into the wall and decreased with depth into the invert. No correlation between microbiota and a specific introduced chemical species have yet been determined. The potential for microbial contamination of the tunnel wall during sampling was determined to be negligible by the use of fluorescently labeled latex spheres (1{mu}m in dia.) as tracers. Results indicate that additional investigations might be needed to examine the microbiota and their possible impacts on the geology and geochemistry of the subsurface, both indigenous microbiota and those microorganisms that will likely be introduced by anthropogenic activity associated with the construction of a high-level waste repository.

  6. Adenosine Triphosphate (ATP Is a Candidate Signaling Molecule in the Mitochondria-to-Nucleus Retrograde Response Pathway

    Directory of Open Access Journals (Sweden)

    Zhengchang Liu

    2013-03-01

    Full Text Available Intracellular communication from the mitochondria to the nucleus is achieved via the retrograde response. In budding yeast, the retrograde response, also known as the RTG pathway, is regulated positively by Rtg1, Rtg2, Rtg3 and Grr1 and negatively by Mks1, Lst8 and two 14-3-3 proteins, Bmh1/2. Activation of retrograde signaling leads to activation of Rtg1/3, two basic helix-loop-helix leucine zipper transcription factors. Rtg1/3 activation requires Rtg2, a cytoplasmic protein with an N-terminal adenosine triphosphate (ATP binding domain belonging to the actin/Hsp70/sugar kinase superfamily. The critical regulatory step of the retrograde response is the interaction between Rtg2 and Mks1. Rtg2 binds to and inactivates Mks1, allowing for activation of Rtg1/3 and the RTG pathway. When the pathway is inactive, Mks1 has dissociated from Rtg2 and bound to Bmh1/2, preventing activation of Rtg1/3. What signals association or disassociation of Mks1 and Rtg2 is unknown. Here, we show that ATP at physiological concentrations dissociates Mks1 from Rtg2 in a highly cooperative fashion. We report that ATP-mediated dissociation of Mks1 from Rtg2 is conserved in two other fungal species, K. lactis and K. waltii. Activation of Rtg1/3 upregulates expression of genes encoding enzymes catalyzing the first three reactions of the Krebs cycle, which is coupled to ATP synthesis through oxidative phosphorylation. Therefore, we propose that the retrograde response is an ATP homeostasis pathway coupling ATP production with ATP-mediated repression of the retrograde response by releasing Mks1 from Rtg2.

  7. A cascade amplification strategy based on rolling circle amplification and hydroxylamine amplified gold nanoparticles enables chemiluminescence detection of adenosine triphosphate.

    Science.gov (United States)

    Wang, Ping; Zhang, Tonghuan; Yang, Taoyi; Jin, Nan; Zhao, Yanjun; Fan, Aiping

    2014-08-01

    A highly sensitive and selective chemiluminescent (CL) biosensor for adenosine triphosphate (ATP) was developed by taking advantage of the ATP-dependent enzymatic reaction (ATP-DER), the powerful signal amplification capability of rolling circle amplification (RCA), and hydroxylamine-amplified gold nanoparticles (Au NPs). The strategy relies on the ability of ATP, a cofactor of T4 DNA ligase, to trigger the ligation-RCA reaction. In the presence of ATP, the T4 DNA ligase catalyzes the ligation reaction between the two ends of the padlock probe, producing a closed circular DNA template that initiates the RCA reaction with phi29 DNA polymerase and dNTP. Therein, many complementary copies of the circular template can be generated. The ATP-DER is eventually converted into a detectable CL signal after a series of processes, including gold probe hybridization, hydroxylamine amplification, and oxidative gold metal dissolution coupled with a simple and sensitive luminol CL reaction. The CL signal is directly proportional to the ATP level. The results showed that the detection limit of the assay is 100 pM of ATP, which compares favorably with those of other ATP detection techniques. In addition, by taking advantage of ATP-DER, the proposed CL sensing system exhibits extraordinary specificity towards ATP and could distinguish the target molecule ATP from its analogues. The proposed method provides a new and versatile platform for the design of novel DNA ligation reaction-based CL sensing systems for other cofactors. This novel ATP-DER based CL sensing system may find wide applications in clinical diagnosis as well as in environmental and biomedical fields.

  8. Analysis of the Endogenous Deoxynucleoside Triphosphate Pool in HIV-Positive and -Negative Individuals Receiving Tenofovir-Emtricitabine.

    Science.gov (United States)

    Chen, Xinhui; Castillo-Mancilla, Jose R; Seifert, Sharon M; McAllister, Kevin B; Zheng, Jia-Hua; Bushman, Lane R; MaWhinney, Samantha; Anderson, Peter L

    2016-09-01

    Tenofovir (TFV) disoproxil fumarate (TDF) and emtricitabine (FTC), two nucleos(t)ide analogs (NA), are coformulated as an anti-HIV combination tablet for treatment and preexposure prophylaxis (PrEP). TDF/FTC may have effects on the deoxynucleoside triphosphate (dNTP) pool due to their similar structures and similar metabolic pathways. We carried out a comprehensive clinical study to characterize the effects of TDF/FTC on the endogenous dNTP pool, from baseline to 30 days of TDF/FTC therapy, in both treatment-naive HIV-positive and HIV-negative individuals. dATP, dCTP, dGTP, and TTP were quantified in peripheral blood mononuclear cells (PBMC) with a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology. Forty individuals (19 HIV-positive) were enrolled and underwent a baseline visit and then received TDF/FTC for at least 30 days. Longitudinal measurements were analyzed using mixed-model segmented linear regression analysis. The dNTPs were reduced by 14% to 37% relative to the baseline level within 3 days in both HIV-negative and HIV-positive individuals (P ≤ 0.003). These reductions persisted to various degrees at day 30. These findings indicate that dNTP pools are influenced by TDF/FTC therapy. This may alter cellular homeostasis and could increase the antiviral effect through a more favorable analog/dNTP ratio. Further work is needed to elucidate mechanisms, to evaluate the clinical significance of these findings, and to further probe differences between HIV-negative and HIV-positive individuals. (This study has been registered at ClinicalTrials.gov under identifier NCT01040091.). PMID:27353267

  9. Magnetic nanoformulation of azidothymidine 5’-triphosphate for targeted delivery across the blood–brain barrier

    Directory of Open Access Journals (Sweden)

    Zainulabedin M Saiyed

    2010-03-01

    Full Text Available Zainulabedin M Saiyed, Nimisha H Gandhi, Madhavan PN Nair1Department of Immunology, College of Medicine, Florida International University, Miami, FL, USAAbstract: Despite significant advances in highly active antiretroviral therapy (HAART, the prevalence of neuroAIDS remains high. This is mainly attributed to inability of antiretroviral therapy (ART to cross the blood–brain barrier (BBB, thus resulting in insufficient drug concentration within the brain. Therefore, development of an active drug targeting system is an attractive strategy to increase the efficacy and delivery of ART to the brain. We report herein development of magnetic azidothymidine 5’-triphosphate (AZTTP liposomal nanoformulation and its ability to transmigrate across an in vitro BBB model by application of an external magnetic field. We hypothesize that this magnetically guided nanoformulation can transverse the BBB by direct transport or via monocyte-mediated transport. Magnetic AZTTP liposomes were prepared using a mixture of phosphatidyl choline and cholesterol. The average size of prepared liposomes was about 150 nm with maximum drug and magnetite loading efficiency of 54.5% and 45.3%, respectively. Further, magnetic AZTTP liposomes were checked for transmigration across an in vitro BBB model using direct or monocyte-mediated transport by application of an external magnetic field. The results show that apparent permeability of magnetic AZTTP liposomes was 3-fold higher than free AZTTP. Also, the magnetic AZTTP liposomes were efficiently taken up by monocytes and these magnetic monocytes showed enhanced transendothelial migration compared to normal/non-magnetic monocytes in presence of an external magnetic field. Thus, we anticipate that the developed magnetic nanoformulation can be used for targeting active nucleotide analog reverse transcriptase inhibitors to the brain by application of an external magnetic force and thereby eliminate the brain HIV reservoir and help

  10. Inhibition of DNA replication, DNA repair synthesis, and DNA polymerases α and δ by butylphenyl deoxyguanosine triphosphate

    International Nuclear Information System (INIS)

    Semiconservative DNA replication in growing mammalian cells and ultraviolet (UV)-induced DNA repair synthesis in nongrowing mammalian cells are mediated by one or both of the aphidicolin-sensitive DNA polymerases, α and/or δ. They have studied the inhibition of replication and repair synthesis in permeable human cells by N2 (p-n-butylphenyl)-2'-deoxyguanosine-5'-triphosphate (BuPh dGTP), an agent which inhibits polymerase α strongly and polymerase δ weakly. Both processes are inhibited by BuPh-dGTP in competition with dGTP. The K/sub i/'s are, for replication, 2-3 μM and, for repair synthesis, 3-4 μM, consistent with the involvement of the same DNA polymerase in both processes. Inhibition of isolated human polymerase α by BuPh-dGTP is also competitive with dGTP, but the K/sub i/ is approximately 10 nM, several hundred-fold lower than the K/sub i/'s of replication and repair synthesis. Isolated polymerase δ is inhibited by BuPh-dGTP at doses similar to those which inhibit replication and repair synthesis, however, attempts to determine the K/sub i/ of polymerase δ were hampered by the finding that the dependence of δ activity on deoxyribunucleotide concentration is parabolic at low doses. This behavior differs from the behavior of polymerase α and of cellular DNA replication and repair synthesis, all of which show a simple, hyperbolic relationship between activity and deoxyribonucleotide concentration. Thus, inhibition of DNA replication and UV induced DNA repair synthesis by BuPh dGTP is quantitatively similar to DNA polymerase δ, but some other characteristics of the cellular processes are more similar to those of polymerase α

  11. Quantitative risk assessment modeling for nonhomogeneous urban road tunnels.

    Science.gov (United States)

    Meng, Qiang; Qu, Xiaobo; Wang, Xinchang; Yuanita, Vivi; Wong, Siew Chee

    2011-03-01

    Urban road tunnels provide an increasingly cost-effective engineering solution, especially in compact cities like Singapore. For some urban road tunnels, tunnel characteristics such as tunnel configurations, geometries, provisions of tunnel electrical and mechanical systems, traffic volumes, etc. may vary from one section to another. These urban road tunnels that have characterized nonuniform parameters are referred to as nonhomogeneous urban road tunnels. In this study, a novel quantitative risk assessment (QRA) model is proposed for nonhomogeneous urban road tunnels because the existing QRA models for road tunnels are inapplicable to assess the risks in these road tunnels. This model uses a tunnel segmentation principle whereby a nonhomogeneous urban road tunnel is divided into various homogenous sections. Individual risk for road tunnel sections as well as the integrated risk indices for the entire road tunnel is defined. The article then proceeds to develop a new QRA model for each of the homogeneous sections. Compared to the existing QRA models for road tunnels, this section-based model incorporates one additional top event-toxic gases due to traffic congestion-and employs the Poisson regression method to estimate the vehicle accident frequencies of tunnel sections. This article further illustrates an aggregated QRA model for nonhomogeneous urban tunnels by integrating the section-based QRA models. Finally, a case study in Singapore is carried out.

  12. The bacterial lipocalins.

    Science.gov (United States)

    Bishop, R E

    2000-10-18

    The lipocalins were once regarded as a eukaryotic protein family, but new members have been recently discovered in bacteria. The first bacterial lipocalin (Blc) was identified in Escherichia coli as an outer membrane lipoprotein expressed under conditions of environmental stress. Blc is distinguished from most lipocalins by the absence of intramolecular disulfide bonds, but the presence of a membrane anchor is shared with two of its closest homologues, apolipoprotein D and lazarillo. Several common features of the membrane-anchored lipocalins suggest that each may play an important role in membrane biogenesis and repair. Additionally, Blc proteins are implicated in the dissemination of antibiotic resistance genes and in the activation of immunity. Recent genome sequencing efforts reveal the existence of at least 20 bacterial lipocalins. The lipocalins appear to have originated in Gram-negative bacteria and were probably transferred horizontally to eukaryotes from the endosymbiotic alpha-proteobacterial ancestor of the mitochondrion. The genome sequences also reveal that some bacterial lipocalins exhibit disulfide bonds and alternative modes of subcellular localization, which include targeting to the periplasmic space, the cytoplasmic membrane, and the cytosol. The relationships between bacterial lipocalin structure and function further illuminate the common biochemistry of bacterial and eukaryotic cells.

  13. Area and shape changes of the carpal tunnel in response to tunnel pressure.

    Science.gov (United States)

    Li, Zong-Ming; Masters, Tamara L; Mondello, Tracy A

    2011-12-01

    Carpal tunnel mechanics is relevant to our understanding of median nerve compression in the tunnel. The compliant characteristics of the tunnel strongly influence its mechanical environment. We investigated the distensibility of the carpal tunnel in response to tunnel pressure. A custom balloon device was designed to apply controlled pressure. Tunnel cross sections were obtained using magnetic resonance imaging to derive the relationship between carpal tunnel pressure and morphological parameters at the hook of hamate. The results showed that the cross-sectional area (CSA) at the level of the hook of hamate increased, on average, by 9.2% and 14.8% at 100 and 200 mmHg, respectively. The increased CSA was attained by a shape change of the cross section, displaying increased circularity. The increase in CSA was mainly attributable to the increase of area in the carpal arch region formed by the transverse carpal ligament. The narrowing of the carpal arch width was associated with an increase in the carpal arch. We concluded that the carpal tunnel is compliant to accommodate physiological variations of the carpal tunnel pressure, and that the increase in tunnel CSA is achieved by increasing the circularity of the cross section.

  14. Simulation of Stress Distribution around Tunnels and Interaction between Tunnels Using an Elasto-plastic Model

    Institute of Scientific and Technical Information of China (English)

    Muya M S; He Bo; Wang Jingtao; Li Guocheng

    2007-01-01

    This article presents a computer simulation of stress distribution around tunnels and interaction between tunnels using an elasto-plastic model. A finite element method using ANSYS software has been used for the analyses of one and two tunnels at different overburden depths with different separating distances between the tunnels. The results of numerical analyses indicate that stress distribution and stress concentration around the tunnels vary with the overburden depths. It is found that the coefficients of stress concentration for elasto-plastic medium are smaller than those for elastic one by 1.9%. Furthermore, the interaction between the two tunnels rapidly decreases with the increase of separation distance between them. In addition, for quantitatively describing the interaction between the two tunnels, a critical separation distance is introduced. The critical separation distances between the two tunnels at different overburden depths are 8 m, 12 m, and 14 m respectively. This fact is very important and essential for the design of mining tunnels and to ensure safety in tunnel engineering.

  15. Hawking Radiation and Classical Tunneling

    CERN Document Server

    Tracy, Eugene R

    2015-01-01

    Acoustic waves in fluids undergoing the transition from sub- to supersonic flow satisfy governing equations similar to those for light waves in the immediate vicinity of a black hole event horizon. This acoustic analogy has been used by Unruh and others as a conceptual model for `Hawking radiation.' Here we use variational methods, originally introduced by Brizard for the study of linearized MHD, and ray phase space methods, to analyze linearized acoustics in the presence of background flows. The variational formulation endows the evolution equations with natural Hermitian and symplectic structures that prove useful for later analysis. We derive a $2\\times 2$ normal form governing the wave evolution in the vicinity of the `event horizon.' This shows that the acoustic model can be reduced locally (in ray phase space) to a standard (scalar) tunneling process weakly coupled to a unidirectional non-dispersive wave (the `incoming wave'). Given the normal form, the Hawking `thermal spectrum' can be derived by invok...

  16. Giant tunneling magnetoresistance in silicene

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu, E-mail: ywang@semi.ac.cn [Department of Physics, Faculty of Science, Kunming University of Science and Technology, Kunming, 650500 Yunnan (China); Lou, Yiyi [Yiyuan Student Community, Center of Student Community Education and Management, Kunming University of Science and Technology, Kunming, 650500 Yunnan (China)

    2013-11-14

    We have theoretically studied ballistic electron transport in silicene under the manipulation of a pair of ferromagnetic gate. Transport properties like transmission and conductance have been calculated by the standard transfer matrix method for parallel and antiparallel magnetization configurations. It is demonstrated here that, due to the stray field-induced wave-vector filtering effect, remarkable difference in configuration-dependent transport gives rise to a giant tunneling magnetoresistance. In combination with the peculiar buckled structure of silicene and its electric tunable energy gap, the receiving magnetoresistance can be efficiently modulated by the externally-tunable stray field, electrostatic potential, and staggered sublattice potential, providing some flexible strategies to construct silicene-based nanoelectronic device.

  17. Josephson tunnel junction microwave attenuator

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Shchukin, A. V.;

    1993-01-01

    A new element for superconducting electronic circuitry-a variable attenuator-has been proposed, designed, and successfully tested. The principle of operation is based on the change in the microwave impedance of a superconductor-insulator-superconductor (SIS) Josephson tunnel junction when dc biased...... at different points in the current-voltage characteristic. Both numerical calculations based on the Tien-Gordon theory and 70-GHz microwave experiments have confirmed the wide dynamic range (more than 15-dB attenuation for one stage) and the low insertion loss in the ''open'' state. The performance of a fully...... integrated submillimeter receiver circuit which comprises a flux-flow oscillator (FFO) as local oscillator, a superconducting variable attenuator, and a microwave SIS detector with tuned-out capacitance is also reported....

  18. Theory of dissociative tunneling ionization

    CERN Document Server

    Svensmark, Jens; Madsen, Lars Bojer

    2016-01-01

    We present a theoretical study of the dissociative tunneling ionization process. Analytic expressions for the nuclear kinetic energy distribution of the ionization rates are derived. A particularly simple expression for the spectrum is found by using the Born-Oppenheimer (BO) approximation in conjunction with the reflection principle. These spectra are compared to exact non-BO ab initio spectra obtained through model calculations with a quantum mechanical treatment of both the electronic and nuclear degrees freedom. In the regime where the BO approximation is applicable imaging of the BO nuclear wave function is demonstrated to be possible through reverse use of the reflection principle, when accounting appropriately for the electronic ionization rate. A qualitative difference between the exact and BO wave functions in the asymptotic region of large electronic distances is shown. Additionally the behavior of the wave function across the turning line is seen to be reminiscent of light refraction. For weak fiel...

  19. Homoepitaxial graphene tunnel barriers for spin transport

    Science.gov (United States)

    Friedman, Adam L.; van't Erve, Olaf M. J.; Robinson, Jeremy T.; Whitener, Keith E.; Jonker, Berend T.

    2016-05-01

    Tunnel barriers are key elements for both charge-and spin-based electronics, offering devices with reduced power consumption and new paradigms for information processing. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, interface stability, and electronic states that severely complicate fabrication and compromise performance. Graphene is the perfect tunnel barrier. It is an insulator out-of-plane, possesses a defect-free, linear habit, and is impervious to interdiffusion. Nonetheless, true tunneling between two stacked graphene layers is not possible in environmental conditions usable for electronics applications. However, two stacked graphene layers can be decoupled using chemical functionalization. Here, we demonstrate that hydrogenation or fluorination of graphene can be used to create a tunnel barrier. We demonstrate successful tunneling by measuring non-linear IV curves and a weakly temperature dependent zero-bias resistance. We demonstrate lateral transport of spin currents in non-local spin-valve structures, and determine spin lifetimes with the non-local Hanle effect. We compare the results for hydrogenated and fluorinated tunnel and we discuss the possibility that ferromagnetic moments in the hydrogenated graphene tunnel barrier affect the spin transport of our devices.

  20. Rudolf Hermann, wind tunnels and aerodynamics

    Science.gov (United States)

    Lundquist, Charles A.; Coleman, Anne M.

    2008-04-01

    Rudolf Hermann was born on December 15, 1904 in Leipzig, Germany. He studied at the University of Leipzig and at the Aachen Institute of Technology. His involvement with wind tunnels began in 1934 when Professor Carl Wieselsberger engaged him to work at Aachen on the development of a supersonic wind tunnel. On January 6, 1936, Dr. Wernher von Braun visited Dr. Hermann to arrange for use of the Aachen supersonic wind tunnel for Army problems. On April 1, 1937, Dr. Hermann became Director of the Supersonic Wind Tunnel at the Army installation at Peenemunde. Results from the Aachen and Peenemunde wind tunnels were crucial in achieving aerodynamic stability for the A-4 rocket, later designated as the V-2. Plans to build a Mach 10 'hypersonic' wind tunnel facility at Kochel were accelerated after the Allied air raid on Peenemunde on August 17, 1943. Dr. Hermann was director of the new facility. Ignoring destruction orders from Hitler as WWII approached an end in Europe, Dr. Hermann and his associates hid documents and preserved wind tunnel components that were acquired by the advancing American forces. Dr. Hermann became a consultant to the Air Force at its Wright Field in November 1945. In 1951, he was named professor of Aeronautical Engineering at the University of Minnesota. In 1962, Dr. Hermann became the first Director of the Research Institute at the University of Alabama in Huntsville (UAH), a position he held until he retired in 1970.

  1. Simulation of people's evacuation in tunnel fire

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The simulation model Tunev(tunnel evacuation) was developed for people's evacuation in tunnel fire. It contains simple database of the people's behavioral reaction and structure characteristic parameters of tunnel fireproofing. The model can be used to calculate the total evacuation time in various scenes when fire occurs in the different locations of the tunnel. Combined with fire simulation soft ware CFD- POENICS3.5, Tunev model can be used to calculate the fire danger coming time; by comparing with these two kinds of time, it can be used to assess the safety of the evacuation, and the evacuation process also have a dynamic demo. The simulation results show that the Tunev model can be used to predict the reliability of safe evacuation for people in tunnel fire and provide references for people's safe escape scheme. Some relevant concepts of the model were described and an evacuation simulation of a typical tunnel case, i.e. Xuefeng Mountain Tunnel was performed by using this model. And the model's validation and actual application were also described.

  2. WT - WIND TUNNEL PERFORMANCE ANALYSIS

    Science.gov (United States)

    Viterna, L. A.

    1994-01-01

    WT was developed to calculate fan rotor power requirements and output thrust for a closed loop wind tunnel. The program uses blade element theory to calculate aerodynamic forces along the blade using airfoil lift and drag characteristics at an appropriate blade aspect ratio. A tip loss model is also used which reduces the lift coefficient to zero for the outer three percent of the blade radius. The application of momentum theory is not used to determine the axial velocity at the rotor plane. Unlike a propeller, the wind tunnel rotor is prevented from producing an increase in velocity in the slipstream. Instead, velocities at the rotor plane are used as input. Other input for WT includes rotational speed, rotor geometry, and airfoil characteristics. Inputs for rotor blade geometry include blade radius, hub radius, number of blades, and pitch angle. Airfoil aerodynamic inputs include angle at zero lift coefficient, positive stall angle, drag coefficient at zero lift coefficient, and drag coefficient at stall. WT is written in APL2 using IBM's APL2 interpreter for IBM PC series and compatible computers running MS-DOS. WT requires a CGA or better color monitor for display. It also requires 640K of RAM and MS-DOS v3.1 or later for execution. Both an MS-DOS executable and the source code are provided on the distribution medium. The standard distribution medium for WT is a 5.25 inch 360K MS-DOS format diskette in PKZIP format. The utility to unarchive the files, PKUNZIP, is also included. WT was developed in 1991. APL2 and IBM PC are registered trademarks of International Business Machines Corporation. MS-DOS is a registered trademark of Microsoft Corporation. PKUNZIP is a registered trademark of PKWare, Inc.

  3. Pair Tunneling through Single Molecules

    Science.gov (United States)

    Raikh, Mikhail

    2007-03-01

    Coupling to molecular vibrations induces a polaronic shift, and can lead to a negative charging energy, U. For negative U, the occupation of the ground state of the molecule is even. In this situation, virtual pair transitions between the molecule and the leads can dominate electron transport. At low temperature, T, these transitions give rise to the charge-Kondo effect [1]. We developed the electron transport theory through the negative-U molecule [2] at relatively high T, when the Kondo correlations are suppressed. Two physical ingredients distinguish our theory from the transport through a superconducting grain coupled to the normal leads [3]: (i) in parallel with sequential pair-tunneling processes, single-particle cotunneling processes take place; (ii) the electron pair on the molecule can be created (or annihilated) by two electrons tunneling in from (or out to) opposite leads. We found that, even within the rate-equation description, the behavior of differential conductance through the negative-U molecule as function of the gate voltage is quite peculiar: the height of the peak near the degeneracy point is independent of temperature, while its width is proportional to T. This is in contrast to the ordinary Coulomb-blockade conductance peak, whose integral strength is T-independent. At finite source-drain bias, V>>T, the width of the conductance peak is ˜V, whereas the conventional Coulomb-blockade peak at finite V splits into two sharp peaks at detunings V/2, and -V/2. Possible applications to the gate-controlled current rectification and switching will be discussed. [1] A. Taraphder and P. Coleman, Phys. Rev. Lett. 66, 2814 (1991). [2] J. Koch, M. E. Raikh, and F. von Oppen, Phys. Rev. Lett. 96, 056803 (2006). [3] F. W. J. Hekking, L. I. Glazman, K. A. Matveev, and R. I. Shekhter, Phys. Rev. Lett. 70, 4138 (1993).

  4. Diagnosis of bacterial vaginosis

    Directory of Open Access Journals (Sweden)

    Đukić Slobodanka

    2013-01-01

    Full Text Available Bacterial vaginosis is a common, complex clinical syndrome characterized by alterations in the normal vaginal flora. When symptomatic, it is associated with a malodorous vaginal discharge and on occasion vaginal burning or itching. Under normal conditions, lactobacilli constitute 95% of the bacteria in the vagina. Bacterial vaginosis is associated with severe reduction or absence of the normal H2O2­producing lactobacilli and overgrowth of anaerobic bacteria and Gardnerella vaginalis, Atopobium vaginae, Mycoplasma hominis and Mobiluncus species. Most types of infectious disease are diagnosed by culture, by isolating an antigen or RNA/DNA from the microbe, or by serodiagnosis to determine the presence of antibodies to the microbe. Therefore, demonstration of the presence of an infectious agent is often a necessary criterion for the diagnosis of the disease. This is not the case for bacterial vaginosis, since the ultimate cause of the disease is not yet known. There are a variety of methods for the diagnosis of bacterial vaginosis but no method can at present be regarded as the best. Diagnosing bacterial vaginosis has long been based on the clinical criteria of Amsel, whereby three of four defined criteria must be satisfied. Nugent’s scoring system has been further developed and includes validation of the categories of observable bacteria structures. Up­to­date molecular tests are introduced, and better understanding of vaginal microbiome, a clear definition for bacterial vaginosis, and short­term and long­term fluctuations in vaginal microflora will help to better define molecular tests within the broader clinical context.

  5. Bacterial glycosyltransferase toxins.

    Science.gov (United States)

    Jank, Thomas; Belyi, Yury; Aktories, Klaus

    2015-12-01

    Mono-glycosylation of host proteins is a common mechanism by which bacterial protein toxins manipulate cellular functions of eukaryotic target host cells. Prototypic for this group of glycosyltransferase toxins are Clostridium difficile toxins A and B, which modify guanine nucleotide-binding proteins of the Rho family. However, toxin-induced glycosylation is not restricted to the Clostridia. Various types of bacterial pathogens including Escherichia coli, Yersinia, Photorhabdus and Legionella species produce glycosyltransferase toxins. Recent studies discovered novel unexpected variations in host protein targets and amino acid acceptors of toxin-catalysed glycosylation. These findings open new perspectives in toxin as well as in carbohydrate research.

  6. Thermal stability of tunneling spin polarization

    International Nuclear Information System (INIS)

    We present a study of the thermal stability of tunneling spin polarization in Al/AlOx/ferromagnet junctions based on the spin-polarized tunneling technique, in which the Zeeman-split superconducting density of states in the Al electrode is used as a detector for the spin polarization. Thermal robustness of the polarization, which is of key importance for the performance of magnetic tunnel junction devices, is demonstrated for post-deposition anneal temperatures up to 500oC with Co and Co90Fe10 top electrodes, independent of the presence of an FeMn layer on top of the ferromagnet

  7. Advancing Test Capabilities at NASA Wind Tunnels

    Science.gov (United States)

    Bell, James

    2015-01-01

    NASA maintains twelve major wind tunnels at three field centers capable of providing flows at 0.1 M 10 and unit Reynolds numbers up to 45106m. The maintenance and enhancement of these facilities is handled through a unified management structure under NASAs Aeronautics and Evaluation and Test Capability (AETC) project. The AETC facilities are; the 11x11 transonic and 9x7 supersonic wind tunnels at NASA Ames; the 10x10 and 8x6 supersonic wind tunnels, 9x15 low speed tunnel, Icing Research Tunnel, and Propulsion Simulator Laboratory, all at NASA Glenn; and the National Transonic Facility, Transonic Dynamics Tunnel, LAL aerothermodynamics laboratory, 8 High Temperature Tunnel, and 14x22 low speed tunnel, all at NASA Langley. This presentation describes the primary AETC facilities and their current capabilities, as well as improvements which are planned over the next five years. These improvements fall into three categories. The first are operations and maintenance improvements designed to increase the efficiency and reliability of the wind tunnels. These include new (possibly composite) fan blades at several facilities, new temperature control systems, and new and much more capable facility data systems. The second category of improvements are facility capability advancements. These include significant improvements to optical access in wind tunnel test sections at Ames, improvements to test section acoustics at Glenn and Langley, the development of a Supercooled Large Droplet capability for icing research, and the development of an icing capability for large engine testing. The final category of improvements consists of test technology enhancements which provide value across multiple facilities. These include projects to increase balance accuracy, provide NIST-traceable calibration characterization for wind tunnels, and to advance optical instruments for Computational Fluid Dynamics (CFD) validation. Taken as a whole, these individual projects provide significant

  8. HYDRAULIC RESEARCH OF AERATORS ON TUNNEL SPILLWAYS

    Institute of Scientific and Technical Information of China (English)

    RUAN Shi-ping; WU Jian-hua; WU Wei-wei; XI Ru-ze

    2007-01-01

    The selection of the configuration and size of an aerator was of importance for a tunnel spillway under the conditions of high speed flows. Experimental investigations were conducted on the effects of entrained air on the tunnel spillway in the Goupitan Project, based on the criterion of gravity similarity and the condition of aerated flow velocity of over 6 m/s, with physical models. The configurations of the aerators were presented of a larger bottom air concentration, to protect the tunnel spillway from cavitation as well as to see no water fills in the grooves.

  9. The Thames Tideway Tunnel (3/3)

    CERN Document Server

    CERN. Geneva

    2012-01-01

    Lecture 3: Insight into a pioneering project at the cutting edge of engineering: the upgrade to London’s failing sewerage system. With a growing population and heavier rainfall, the River Thames is regularly polluted in breach of European Directive requirements. Two new storage and transfer tunnels will run up to 85m deep under the river and will intercept and divert sewer overflows to a treatment facility in east London. The challenges faced by constructing a tunnel project of this size under the river and through London’s historic urban environment will set a new UK record for this type of tunnelling.

  10. Quantum limit in resonant vacuum tunneling transducers

    CERN Document Server

    Onofrio, Roberto

    2010-01-01

    We propose an electromechanical transducer based on a resonant-tunneling configuration that, with respect to the standard tunneling transducers, allows larger tunneling currents while using the same bias voltage. The increased current leads to an increase of the shot noise and an increase of the momentum noise which determine the quantum limit in the system under monitoring. Experiments with micromachined masses at 4.2 K could show dominance of the momentum noise over the Brownian noise, allowing observation of the quantum-mechanical noise at the mesoscopic scale.

  11. Integrated tunneling sensor for nanoelectromechanical systems

    DEFF Research Database (Denmark)

    Sadewasser, S.; Abadal, G.; Barniol, N.;

    2006-01-01

    Transducers based on quantum mechanical tunneling provide an extremely sensitive sensor principle, especially for nanoelectromechanical systems. For proper operation a gap between the electrodes of below 1 nm is essential, requiring the use of structures with a mobile electrode. At such small...... distances, attractive van der Waals and capillary forces become sizable, possibly resulting in snap-in of the electrodes. The authors present a comprehensive analysis and evaluation of the interplay between the involved forces and identify requirements for the design of tunneling sensors. Based...... on this analysis, a tunneling sensor is fabricated by Si micromachining technology and its proper operation is demonstrated. (c) 2006 American Institute of Physics....

  12. Carpal tunnel syndrome - anatomical and clinical correlations.

    Science.gov (United States)

    Iskra, Tomasz; Mizia, Ewa; Musial, Agata; Matuszyk, Aleksandra; Tomaszewski, Krzysztof A

    2013-01-01

    Carpal tunnel syndrome (CTS) is the most common and widely known of the entrapment neuropathies in which the body's peripheral nerves are compressed. Common symptoms of CTS involve the hand and result from compression of the median nerve within the carpal tunnel. In general, CTS develops when the tissues around the median nerve irritate or compress on the nerve along its course through the carpal tunnel, however often it is very difficult to determine cause of CTS. Proper treatment (conservative or surgical) usually can relieve the symptoms and restore normal use of the wrist and hand.

  13. Application of Important Factors in Tunnel Projects

    Directory of Open Access Journals (Sweden)

    Siamak Bagherian

    2013-06-01

    Full Text Available The objective of this thesis is to improve the quality of the basis for making decisions about tender prices and budgets for tunnel projects by developing a model for the estimation of construction time and cost. The planning and constructing of extensions to existing road and railway networks is an ongoing mission of transport infrastructure development. For functional, aesthetic or environmental reasons, a large number of these extensions are planned as tunnels. In the planning and procurement phases of tunnel projects, numerous decisions have to be made in relation to the tender price and project budget.

  14. Extraskeletal chondroma casuing carpal tunnel syndrome: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ok Hwa; Kim, Yeon Hee [Haeundae Paik Hospital, Inje University College of Medicine, Busan (Korea, Republic of)

    2014-03-15

    Carpal tunnel syndrome caused by extraskeletal chondroma has been scarcely reported in the literature. Authors report a case of carpal tunnel syndrome as a result of an extraskeletal chondroma arising within the carpal tunnel, and describe the radiological and pathological findings of the mass. We also discuss the differential diagnosis of the calcified space, occupying lesions that may occur in carpal tunnel.

  15. Pressure-morphology relationship of a released carpal tunnel.

    Science.gov (United States)

    Kim, Dong Hee; Marquardt, Tamara L; Gabra, Joseph N; Shen, Zhilei Liu; Evans, Peter J; Seitz, William H; Li, Zong-Ming

    2013-04-01

    We investigated morphological changes of a released carpal tunnel in response to variations of carpal tunnel pressure. Pressure within the carpal tunnel is known to be elevated in patients with carpal tunnel syndrome and dependent on wrist posture. Previously, increased carpal tunnel pressure was shown to affect the morphology of the carpal tunnel with an intact transverse carpal ligament (TCL). However, the pressure-morphology relationship of the carpal tunnel after release of the TCL has not been investigated. Carpal tunnel release (CTR) was performed endoscopically on cadaveric hands and the carpal tunnel pressure was dynamically increased from 10 to 120 mmHg. Simultaneously, carpal tunnel cross-sectional images were captured by an ultrasound system, and pressure measurements were recorded by a pressure transducer. Carpal tunnel pressure significantly affected carpal arch area (p 62 mm(2) at 120 mmHg. Carpal arch height, length, and width also significantly changed with carpal tunnel pressure (p carpal tunnel pressure increased, carpal arch height and length increased, but the carpal arch width decreased. Analyses of the pressure-morphology relationship for a released carpal tunnel revealed a nine times greater compliance than that previously reported for a carpal tunnel with an intact TCL. This change of structural properties as a result of transecting the TCL helps explain the reduction of carpal tunnel pressure and relief of symptoms for patients after CTR surgery.

  16. Pressure-morphology relationship of a released carpal tunnel.

    Science.gov (United States)

    Kim, Dong Hee; Marquardt, Tamara L; Gabra, Joseph N; Shen, Zhilei Liu; Evans, Peter J; Seitz, William H; Li, Zong-Ming

    2013-04-01

    We investigated morphological changes of a released carpal tunnel in response to variations of carpal tunnel pressure. Pressure within the carpal tunnel is known to be elevated in patients with carpal tunnel syndrome and dependent on wrist posture. Previously, increased carpal tunnel pressure was shown to affect the morphology of the carpal tunnel with an intact transverse carpal ligament (TCL). However, the pressure-morphology relationship of the carpal tunnel after release of the TCL has not been investigated. Carpal tunnel release (CTR) was performed endoscopically on cadaveric hands and the carpal tunnel pressure was dynamically increased from 10 to 120 mmHg. Simultaneously, carpal tunnel cross-sectional images were captured by an ultrasound system, and pressure measurements were recorded by a pressure transducer. Carpal tunnel pressure significantly affected carpal arch area (p 62 mm(2) at 120 mmHg. Carpal arch height, length, and width also significantly changed with carpal tunnel pressure (p < 0.05). As carpal tunnel pressure increased, carpal arch height and length increased, but the carpal arch width decreased. Analyses of the pressure-morphology relationship for a released carpal tunnel revealed a nine times greater compliance than that previously reported for a carpal tunnel with an intact TCL. This change of structural properties as a result of transecting the TCL helps explain the reduction of carpal tunnel pressure and relief of symptoms for patients after CTR surgery. PMID:23184493

  17. Electron transfer pathway analysis in bacterial photosynthetic reaction center

    CERN Document Server

    Kitoh-Nishioka, Hirotaka

    2016-01-01

    A new computational scheme to analyze electron transfer (ET) pathways in large biomolecules is presented with applications to ETs in bacterial photosynthetic reaction center. It consists of a linear combination of fragment molecular orbitals and an electron tunneling current analysis, which enables an efficient first-principles analysis of ET pathways in large biomolecules. The scheme has been applied to the ET from menaquinone to ubiquinone via nonheme iron complex in bacterial photosynthetic reaction center. It has revealed that not only the central Fe$^{2+}$ ion but also particular histidine ligands are involved in the ET pathways in such a way to mitigate perturbations that can be caused by metal ion substitution and depletion, which elucidates the experimentally observed insensitivity of the ET rate to these perturbations.

  18. Quantum dot resonant tunneling diode single photon detector with aluminum oxide aperture defined tunneling area

    OpenAIRE

    Li, H W; Kardynal, Beata; Ellis, D. J. P.; Shields, A.J.; Farrer, I.; Ritchie, D. A.

    2008-01-01

    Quantum dot resonant tunneling diode single photon detector with independently defined absorption and sensing areas is demonstrated. The device, in which the tunneling is constricted to an aperture in an insulating layer in the emitter, shows electrical characteristics typical of high quality resonant tunneling diodes. A single photon detection efficiency of 2.1%+/- 0.1% at 685 nm was measured corresponding to an internal quantum efficiency of 14%. The devices are simple to fabricate, robust,...

  19. TBM tunnelling through unfavourable ground conditions : a case study, SSDS tunnel F, Hong Kong

    OpenAIRE

    Lokusethu Hewage Don, Danuska Hasitha

    2013-01-01

    A study of the Strategic Sewage Disposal Scheme (SSDS) Stage 1 Tunnel F in Hong Kong was carried out as it is a great example of deep sub-sea hard rock TBM tunnelling through unfavourable, fault-affected ground conditions with heavy water inflows. The main objective of this study was to document events that took place during Tunnel F excavation and collate geological and geotechnical data related to the excavation, to aid future tunnel designers and contractors to assess the risk involved wit...

  20. Tunnel Waterproofing with Membranes Waterproofing at Senoko Cabele Tunnel in comparison with International Standards

    Institute of Scientific and Technical Information of China (English)

    Stefan Hotz

    2004-01-01

    Waterproofing of tunnels is and has always been a challenge, worldwide: Changing Geology with hardly predictable water inflow, limited space underground and only very little intervention opportunities once the tunnel is completed. This paper elaborates such challenges and focuses on the waterproofing solutions of mined tunnels with membranes. Different standards and approaches for the waterproofing system. In Singapore, a membrane waterproofing system is used for the shafts and adits at Senoko Cable Tunnel. The paper project specific waterproofing challenges and emphasizes on solution for them.

  1. Quantum size effects on spin-tunneling time in a magnetic resonant tunneling diode

    OpenAIRE

    Saffarzadeh, Alireza; Daqiq, Reza

    2009-01-01

    We study theoretically the quantum size effects of a magnetic resonant tunneling diode (RTD) with a (Zn,Mn)Se dilute magnetic semiconductor layer on the spin-tunneling time and the spin polarization of the electrons. The results show that the spin-tunneling times may oscillate and a great difference between the tunneling time of the electrons with opposite spin directions can be obtained depending on the system parameters. We also study the effect of structural asymmetry which is related to t...

  2. Sequencing, functional expression and characterization of rat NTPDase6, a nucleoside diphosphatase and novel member of the ecto-nucleoside triphosphate diphosphohydrolase family.

    Science.gov (United States)

    Braun, N; Fengler, S; Ebeling, C; Servos, J; Zimmermann, H

    2000-11-01

    We have isolated and characterized the cDNA encoding nucleoside triphosphate diphosphohydrolase 6 (NTPDase6), a novel member of the ecto-nucleoside triphosphate diphosphohydrolase family. The rat-brain-derived cDNA has an open reading frame of 1365 bp encoding a protein of 455 amino acid residues, a calculated molecular mass of 49971 Da and a predicted N-terminal hydrophobic sequence. It shares 86% sequence identity with the human CD39L2 sequence and 48% and 51% identity respectively with sequences of the two related human and murine nucleoside diphosphatases (CD39L4, NTPDase5/ER-UDPase). The mRNA was expressed in all tissues investigated, revealing two major transcripts with differing abundances. PCR analysis suggests a single open reading frame. A Myc-His-tagged NTPDase6 was expressed in Chinese hamster ovary (CHO) and PC12 cells for immunological analysis and protein isolation. The protein was contained in membrane fractions of transfected CHO cells and occurred in a soluble form in the cell culture supernatants. NTPDase6 preferentially hydrolysed nucleoside 5'-diphosphates. With different substrates the order of activity was GDP>IDP>UDP,CDP>ADP. Nucleoside 5'-triphosphates were hydrolysed only to a minor extent and no hydrolysis of nucleoside 5'-monophosphates was observed. The enzyme was strongly and equally activated by Ca(2+) and Mg(2+) and had a K(m) for GDP of 211 microM. The immunohistochemical analysis of transfected CHO and PC12 cells suggests that NTPDase6 is associated with the Golgi apparatus and to a small extent also with the plasma membrane. The enzyme might support glycosylation reactions in the Golgi apparatus and, when released from cells, might catalyse the hydrolysis of extracellular nucleotides. PMID:11042118

  3. Seizures Complicating Bacterial Meningitis

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-09-01

    Full Text Available The clinical data of 116 patients, 1 month to <5 years of age, admitted for bacterial meningitis, and grouped according to those with and without seizures during hospitalization, were compared in a study at Buddhist Dalin Tzu Chi General Hospital, Chang Gung Memorial Hospital and other centers in Taiwan.

  4. Bacterial extracellular lignin peroxidase

    Science.gov (United States)

    Crawford, Donald L.; Ramachandra, Muralidhara

    1993-01-01

    A newly discovered lignin peroxidase enzyme is provided. The enzyme is obtained from a bacterial source and is capable of degrading the lignin portion of lignocellulose in the presence of hydrogen peroxide. The enzyme is extracellular, oxidative, inducible by lignin, larch wood xylan, or related substrates and capable of attacking certain lignin substructure chemical bonds that are not degradable by fungal lignin peroxidases.

  5. Bacterial Skin Infections

    Science.gov (United States)

    ... or scraped, the injury should be washed with soap and water and covered with a sterile bandage. Petrolatum may be applied to open areas to keep the tissue moist and to try to prevent bacterial invasion. Doctors recommend that people do not use ...

  6. Vimentin in Bacterial Infections

    DEFF Research Database (Denmark)

    Mak, Tim N; Brüggemann, Holger

    2016-01-01

    filaments (IFs). IFs have not only roles in maintaining the structural integrity of the cell, but they are also involved in many cellular processes including cell adhesion, immune signaling, and autophagy, processes that are important in the context of bacterial infections. Here, we summarize the knowledge...

  7. Bacterial microflora of nectarines

    Science.gov (United States)

    Microflora of fruit surfaces has been the best source of antagonists against fungi causing postharvest decays of fruit. However, there is little information on microflora colonizing surfaces of fruits other than grapes, apples, and citrus fruit. We characterized bacterial microflora on nectarine f...

  8. Modeling intraocular bacterial infections.

    Science.gov (United States)

    Astley, Roger A; Coburn, Phillip S; Parkunan, Salai Madhumathi; Callegan, Michelle C

    2016-09-01

    Bacterial endophthalmitis is an infection and inflammation of the posterior segment of the eye which can result in significant loss of visual acuity. Even with prompt antibiotic, anti-inflammatory and surgical intervention, vision and even the eye itself may be lost. For the past century, experimental animal models have been used to examine various aspects of the pathogenesis and pathophysiology of bacterial endophthalmitis, to further the development of anti-inflammatory treatment strategies, and to evaluate the pharmacokinetics and efficacies of antibiotics. Experimental models allow independent control of many parameters of infection and facilitate systematic examination of infection outcomes. While no single animal model perfectly reproduces the human pathology of bacterial endophthalmitis, investigators have successfully used these models to understand the infectious process and the host response, and have provided new information regarding therapeutic options for the treatment of bacterial endophthalmitis. This review highlights experimental animal models of endophthalmitis and correlates this information with the clinical setting. The goal is to identify knowledge gaps that may be addressed in future experimental and clinical studies focused on improvements in the therapeutic preservation of vision during and after this disease. PMID:27154427

  9. Quantum Tunnelling to the Origin and Evolution of Life

    OpenAIRE

    Trixler, Frank

    2013-01-01

    Quantum tunnelling is a phenomenon which becomes relevant at the nanoscale and below. It is a paradox from the classical point of view as it enables elementary particles and atoms to permeate an energetic barrier without the need for sufficient energy to overcome it. Tunnelling might seem to be an exotic process only important for special physical effects and applications such as the Tunnel Diode, Scanning Tunnelling Microscopy (electron tunnelling) or Near-field Optical Microscopy operating ...

  10. Tunnel magnetoresistance in Self-Assembled Monolayers Based Tunnel Junctions

    Science.gov (United States)

    Mattana, Richard; Barraud, Clément; Tatay, Sergio; Galbiati, Marta; Seneor, Pierre; Bouzehouane, Karim; Jacquet, Eric; Deranlot, Cyrile; Fert, Albert; Petroff, Frédéric

    2012-02-01

    Organic/molecular spintronics is a rising research field at the frontier between spintronics and organic chemistry. Organic molecule and semiconductors were first seen as promising for spintronics devices due to their expected long spin lifetime. But an exciting challenge has also been to find opportunities arising from chemistry to develop new spintronics functionalities. It was shown that the molecular structure and the ferromagnetic metal/molecule hybridization can strongly influence interfacial spin properties going from spin polarization enhancement to its sign control in spintronics devices. In this scenario, while scarcely studied, self-assembled monolayers (SAMs) are expected to become perfect toy barriers to further test these tailoring properties in molecular magnetic tunnel junctions (MTJs). Due to its very high spin polarization and air stability LSMO has positioned itself as the electrode of choice in most of the organic spintronics devices. We will present a missing building block for molecular spintronics tailoring: the grafting and film characterization of organic monofunctionalized long alkane chains over LSMO. We have obtained 35% of magnetoresistance in LSMO/SAMs/Co MTJs. We will discuss the unusual behaviour of the bias voltage dependence of the TMR.

  11. Low Speed Wind Tunnel Facility (LSWTF)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: This facility consists of a large-scale, low-speed open-loop induction wind tunnel which has been modified to house a linear turbine cascade. A 125-hp...

  12. Hi-tech Tunnel Sets World Record

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A sport utility vehicle takes the new direct route from Xi’an, capital city of northwest China’s Shaanxi Province, to Zhashui County through the Zhongnanshan Tunnel, which opened on January 21.With a total investment of nearly 3.2 billion yuan, the four-lane highway is the world’s longest double-tube tunnel, stretching 18.02 km.As a major part of the province’s expressway network, the tunnel connects Xi’an with southwest Shaanxi through the Qinling Mountains, shortening the previous three-hour trip to 40 minutes.The highway tunnel is also planned as part of a national highway linking north China’s Inner Mongolia Autonomous Region and south China’s Guangxi Zhuang Autonomous Region.

  13. Unknotting tunnels in hyperbolic 3-manifolds

    CERN Document Server

    Adams, Colin

    2012-01-01

    An unknotting tunnel in a 3-manifold with boundary is a properly embedded arc, the complement of an open neighborhood of which is a handlebody. A geodesic with endpoints on the cusp boundary of a hyperbolic 3-manifold and perpendicular to the cusp boundary is called a vertical geodesic. Given a vertical geodesic in a hyperbolic 3-manifold M, we find sufficient conditions for it to be an unknotting tunnel. In particular, if the vertical geodesic corresponds to a 4-bracelet, 5-bracelet or 6-bracelet in the universal cover and has short enough length, it must be an unknotting tunnel. Furthermore, we consider a vertical geodesic that satisfies the elder sibling property, which means that in the universal cover, every horoball except the one centered at infinity is connected to a larger horoball by a lift of the vertical geodesic. Such a vertical geodesic with length less than ln(2) is then shown to be an unknotting tunnel.

  14. Program Analyzes Performance Of A Wind Tunnel

    Science.gov (United States)

    Viterna, L. A.

    1994-01-01

    WT computer program developed to calculate rotor power required by, and output thrust produced by, fan in closed-loop wind tunnel. Uses blade-element theory to calculate aerodynamic forces along each blade of fan. Written in APL2.

  15. Some Connections between Quantum Tunneling and Inflation

    CERN Document Server

    Norbury, J W

    1998-01-01

    The Wheeler-DeWitt equation in the minisuperspace approximation is studied in four different models. Under certain circumstances each model leads to a tunneling potential and under the same circumstances the classical version of each model leads to inflation.

  16. Tunneling rate in double quantum dots

    Science.gov (United States)

    Filikhin, Igor; Matinyan, Sergei; Vlahovic, Branislav

    2014-03-01

    We study spectral properties of electron tunneling in double quantum dots (DQDs) (and double quantum wells (DQWs)) and their relation to the geometry. In particular we compare the tunneling in DQW with chaotic and regular geometry, taking into account recent evidence about regularization of the tunneling rate when the QW geometry is chaotic. Our calculations do not support this assumption. We confirm high influence of the QW geometry boundaries on the rate fluctuation along the spectrum. The factors of the effective mass anisotropy and violation of the symmetry of DQD and DQW are also considered. Generally, we found that the small violation of the symmetry drastically affects tunneling. This work is supported by the NSF (HRD-0833184) and NASA (NNX09AV07A).

  17. Proton tunnelling in intermolecular hydrogen bonds

    Energy Technology Data Exchange (ETDEWEB)

    Horsewill, A.J. [Nottingham Univ. (United Kingdom); Johnson, M.R. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Trommsdorff, H.P. [Grenoble-1 Univ., 38 (France)

    1997-04-01

    The wavefunctions of particles extend beyond the classically accessible regions of potential energy-surfaces (PES). A manifestation of this partial delocalization is the quantum-mechanical tunneling effect which enables a particle to escape from a metastable potential-well. Tunnelling is most important for the lightest atoms, so that the determination of its contribution to proton transfer, one of the most fundamental chemical reactions, is an important issue. QENS and NMR techniques have been employed to study the motion of protons in the hydrogen bond of benzoic-acid crystals, a system which has emerged as a particularly suitable model since proton transfer occurs in a near symmetric double-well potential. The influence of quantum tunnelling was revealed and investigated in these experiments. This work provides an experimental benchmark for theoretical descriptions of translational proton-tunnelling. (author). 7 refs.

  18. Teelt van vruchtgewassen in lage tunnels

    NARCIS (Netherlands)

    Wijk, van C.A.P.; Geven, C.G.M.

    1994-01-01

    Een aantal warmteminnende vruchtgewassen zijn beproefd in lage tunnels en vergeleken met onbedekte teelt en met kasteelt. Het betrof aubergine, paprika, peper en diverse typen meloen. Daar is courgette als vergelijkend gewas aan toegevoegd

  19. Characterization of magnetic tunnel junction test pads

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Kjær, Daniel; Nielsen, Peter Folmer;

    2015-01-01

    relies on four-point probe measurements performed with a range of different probe pitches and was originally developed for infinite samples. Using the method of images, we derive a modified CIPT model, which compensates for the insulating boundaries of a finite rectangular sample geometry. We measure...... on square tunnel junction pads with varying sizes and analyze the measured data using both the original and the modified CIPT model. Thus, we determine in which sample size range the modified CIPT model is needed to ensure validity of the extracted sample parameters, RA and TMR. In addition, measurements......We show experimentally as well as theoretically that patterned magnetic tunnel junctions can be characterized using the current-in-plane tunneling (CIPT) method, and the key parameters, the resistance-area product (RA) and the tunnel magnetoresistance (TMR), can be determined. The CIPT method...

  20. Decoherence and tunneling of an interacting gas

    Science.gov (United States)

    Anglin, James; Rico-Perez, Luis; Wohlfarth, Daniel

    2015-05-01

    In quasi-steady escape of a confined interacting gas by quantum tunneling, collisional decoherence can reduce the escape rate through a many-body version of the Caldeira-Leggett effect. This explains why classical fluids fail to tunnel, even though they are composed of particles small enough to be quantum mechanical. We compute this effect in the Maxwell-Boltzmann regime by deriving a quantum generalization of the Boltzmann equation. We show that decoherence effectively makes tunneling of an interacting gas into an irreversible process: a uniquely quantum mechanical form of throttling. The rate of entropy production in tunneling is related in the semi-classical limit to the imaginary part of the single-particle action.

  1. Many-electron tunneling in atoms

    CERN Document Server

    Zon, B A

    1999-01-01

    A theoretical derivation is given for the formula describing N-electron ionization of atom by a dc field and laser radiation in tunneling regime. Numerical examples are presented for noble gases atoms.

  2. Particle Tunneling in the 7-Azaindole Dimer

    Institute of Scientific and Technical Information of China (English)

    VANHISE,JamesR.

    2005-01-01

    Using a one dimensional quantum particle tunneling model, the proton and deuteron transfer lifetime was developed and computed in the 7-azaindole dimer, the results were compared with measurements by Douhal and thereby the effective barrier heights and widths extracted.

  3. Computer graphic of LHC in the tunnel

    CERN Multimedia

    1996-01-01

    A computer-generated image of the LHC particle accelerator at CERN in the tunnel originally built for the LEP accelerator that was closed in 2000. The cross-section of an LHC superconducting dipole magnet is also seen.

  4. Dielectric Sensors Based on Electromagnetic Energy Tunneling

    Directory of Open Access Journals (Sweden)

    Omar Siddiqui

    2015-03-01

    Full Text Available We show that metallic wires embedded in narrow waveguide bends and channels demonstrate resonance behavior at specific frequencies. The electromagnetic energy at these resonances tunnels through the narrow waveguide channels with almost no propagation losses. Under the tunneling behavior, high-intensity electromagnetic fields are produced in the vicinity of the metallic wires. These intense field resonances can be exploited to build highly sensitive dielectric sensors. The sensor operation is explained with the help of full-wave simulations. A practical setup consisting of a 3D waveguide bend is presented to experimentally observe the tunneling phenomenon. The tunneling frequency is predicted by determining the input impedance minima through a variational formula based on the Green function of a probe-excited parallel plate waveguide.

  5. Wind tunnel buffet load measuring technique

    Science.gov (United States)

    Chang, C. S.; Ellison, A. M.

    1972-01-01

    Indirect force measurement technique estimates unsteady forces acting on elastic model during wind tunnel tests. Measurement of forces is practically insensitive to errors in aeroelastic scaling between model and full-scale structure, simplifying design, fabrication and dynamic calibration.

  6. 7 x 10 Foot Wind Tunnel

    Data.gov (United States)

    Federal Laboratory Consortium — This wind tunnel is used for basic and applied research in aeromechanics on advanced and unique technology rotorcraft. It supports research on advanced concepts and...

  7. LEP sees the end of the tunnel

    CERN Document Server

    2002-01-01

    After 14 months, which have seen the removal of 30,000 tonnes of material from the tunnel, the LEP dismantling operation has now been completed. LHC installation, which will be subject to new safety rules, can go ahead.

  8. Dynamical quenching of tunneling in molecular magnets

    Energy Technology Data Exchange (ETDEWEB)

    José Santander, María, E-mail: maria.jose.noemi@gmail.com [Recursos Educativos Quántica, Santiago (Chile); Departamento de Física, Universidad de Santiago de Chile and CEDENNA, Avda. Ecuador 3493, Santiago (Chile); Nunez, Alvaro S., E-mail: alnunez@dfi.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 487-3, Santiago (Chile); Roldán-Molina, A. [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Avenida Universidad 330, Curauma, Valparaíso (Chile); Troncoso, Roberto E., E-mail: r.troncoso.c@gmail.com [Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Avda. Ecuador 3493, Santiago 9170124 (Chile); Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso (Chile)

    2015-12-15

    It is shown that a single molecular magnet placed in a rapidly oscillating magnetic field displays the phenomenon of quenching of tunneling processes. The results open a way to manipulate the quantum states of molecular magnets by means of radiation in the terahertz range. Our analysis separates the time evolution into slow and fast components thereby obtaining an effective theory for the slow dynamics. This effective theory presents quenching of the tunnel effect, in particular, stands out its difference with the so-called coherent destruction of tunneling. We support our prediction with numerical evidence based on an exact solution of Schrödinger's equation. - Highlights: • Single molecular magnets under rapidly oscillating magnetic fields is studied. • It is shown that this system displays the quenching of tunneling processes. • Our findings provide a control of quantum molecular magnets via terahertz radiation.

  9. Two-Dimensional Low-Turbulence Tunnel

    Science.gov (United States)

    1938-01-01

    Manometer for the Two-Dimensional Low-Turbulence Tunnel. The Two-Dimensional Low-Turbulence Tunnel was originally called the Refrigeration or 'Ice' tunnel because it was intended to support research on aircraft icing. The tunnel was built of wood, lined with sheet steel, and heavily insulated on the outside. Refrigeration equipment was installed to generate icing conditions inside the test section. The NACA sent out a questionnaire to airline operators, asking them to detail the specific kinds of icing problems they encountered in flight. The replies became the basis for a comprehensive research program begun in 1938 when the tunnel commenced operation. Research quickly focused on the concept of using exhaust heat to prevent ice from forming on the wing's leading edge. This project was led by Lewis Rodert, who later would win the Collier Trophy for his work on deicing. By 1940, aircraft icing research had shifted to the new Ames Research Laboratory, and the Ice tunnel was refitted with screens and honeycomb. Researchers were trying to eliminate all turbulence in the test section. From TN 1283: 'The Langley two-dimensional low-turbulence pressure tunnel is a single-return closed-throat tunnel.... The tunnel is constructed of heavy steel plate so that the pressure of the air may be varied from approximately full vacuum to 10 atmospheres absolute, thereby giving a wide range of air densities. Reciprocating compressors with a capacity of 1200 cubic feet of free air per minute provide compressed air. Since the tunnel shell has a volume of about 83,000 cubic feet, a compression rate of approximately one atmosphere per hour is obtained. ... The test section is rectangular in shape, 3 feet wide, 7 1/2 feet high, and 7 1/2 feet long. ... The over-all size of the wind-tunnel shell is about 146 feet long and 58 feet wide with a maximum diameter of 26 feet. The test section and entrance and exit cones are surrounded by a 22-foot diameter section of the shell to provide a space

  10. Tunneling magnetoresistive heads for magnetic data storage.

    Science.gov (United States)

    Mao, Sining

    2007-01-01

    Spintronics is emerging to be a new form of nanotechnologies, which utilizes not only the charge but also spin degree of freedom of electrons. Spin-dependent tunneling transport is one of the many kinds of physical phenomena involving spintronics, which has already found industrial applications. In this paper, we first provide a brief review on the basic physics and materials for magnetic tunnel junctions, followed more importantly by a detailed coverage on the application of magnetic tunneling devices in magnetic data storage. The use of tunneling magnetoresistive reading heads has helped to maintain a fast growth of areal density, which is one of the key advantages of hard disk drives as compared to solid-state memories. This review is focused on the first commercial tunneling magnetoresistive heads in the industry at an areal density of 80 approximately 100 Gbit/in2 for both laptop and desktop Seagate hard disk drive products using longitudinal media. The first generation tunneling magnetoresistive products utilized a bottom stack of tunnel junctions and an abutted hard bias design. The output signal amplitude of these heads was 3 times larger than that of comparable giant magnetoresistive devices, resulting in a 0.6 decade bit error rate gain over the latter. This has enabled high component and drive yields. Due to the improved thermal dissipation of vertical geometry, the tunneling magnetoresistive head runs cooler with a better lifetime performance, and has demonstrated similar electrical-static-discharge robustness as the giant magnetoresistive devices. It has also demonstrated equivalent or better process and wafer yields compared to the latter. The tunneling magnetoresistive heads are proven to be a mature and capable reader technology. Using the same head design in conjunction with perpendicular recording media, an areal density of 274 Gbit/in2 has been demonstrated, and advanced tunneling magnetoresistive heads can reach 311 Gbit/in2. Today, the

  11. Preferential binding of Escherichia coli RecF protein to gapped DNA in the presence of adenosine (gamma-thio) triphosphate.

    OpenAIRE

    Hegde, S P; Rajagopalan, M; Madiraju, M V

    1996-01-01

    Escherichia coli RecF protein binds, but does not hydrolyze, ATP. To determine the role that ATP binding to RecF plays in RecF protein-mediated DNA binding, we have determined the interaction between RecF protein and single-stranded (ss)DNA, double-stranded (ds)DNA, and dsDNA containing ssDNA regions (gapped [g]DNA) either alone or in various combinations both in the presence and in the absence of adenosine (gamma-thio) triphosphate, gamma-S-ATP, a nonhydrolyzable ATP analog. Protein-DNA comp...

  12. Dihydrothymidine and thymidine glycol triphosphates as substrates for DNA polymerases: differential recognition of thymine C5-C6 bond saturation and sequence specificity of incorporation.

    OpenAIRE

    Ide, H; Wallace, S. S.

    1988-01-01

    The ability of dihydrothymidine (DHdTTP) and thymidine glycol (dTTP-GLY) 5'-triphosphates to serve as substrates for different DNA polymerases was investigated. DHdTTP but not dTTP-GLY was used as a substrate by E. coli DNA polymerase I (Pol I). Within the detection limit of the assay used, neither T4 DNA polymerase nor avian myeloblastosis virus (AMV) reverse transcriptase used DHdTTP or dTTP-GLY as substrates. The ability of DHdTTP and dTTP-GLY to undergo enzyme-catalyzed turnover to the mo...

  13. Andreev reflection and Klein tunneling in graphene

    OpenAIRE

    Beenakker, C. W. J.

    2007-01-01

    This is a colloquium-style introduction to two electronic processes in a carbon monolayer (graphene), each having an analogue in relativistic quantum mechanics. Both processes couple electron-like and hole-like states, through the action of either a superconducting pair potential or an electrostatic potential. The first process, Andreev reflection, is the electron-to-hole conversion at the interface with a superconductor. The second process, Klein tunneling, is the tunneling through a p-n jun...

  14. Aeroelastic instability stoppers for wind tunnel models

    Science.gov (United States)

    Doggett, R. V., Jr.; Ricketts, R. H. (Inventor)

    1981-01-01

    A mechanism for constraining models or sections thereof, was wind tunnel tested, deployed at the onset of aeroelastic instability, to forestall destructive vibrations in the model is described. The mechanism includes a pair of arms pivoted to the tunnel wall and straddling the model. Rollers on the ends of the arms contact the model, and are pulled together against the model by a spring stretched between the arms. An actuator mechanism swings the arms into place and back as desired.

  15. Tribocorrosion challenges in tunnel boring machinery (TBM)

    OpenAIRE

    Espallargas Alvarez, Nuria

    2015-01-01

    Tunnel Boring Machines (TBM) are used to bore tunnels, a specific area of interest for TBMs is their cutter heads, which is a massive steel structure with hardened steel disc cutters attached. The disc cutters can encounter all types of geology (i.e. from soft clays, slits, sands etc., to soft rock and extremely hard rock) and environments (i.e. dry, wet, seawater or chemical additives). These geologies and environments cause the disc cutters to be continuously exposed to degra...

  16. Geology of Pletovarje motorway tunnel (Slovenia

    Directory of Open Access Journals (Sweden)

    Magda Čarman

    2009-06-01

    Full Text Available Styrian motorway crosses the Pletovarje ridge through the tunnel having the same name. It intersects the mosteastern extension of the Southern Karavanke tectonic unit. Considering geological conditions, the tunnel couldbe divided into three sections: the inner Donat / Dona~ka fault zone composed of tectonic lenses of differentlithostratigraphic units (of paleozoic, triassic and tertiary age, massive dolomite (lower triassic and Smrekovecseries of oligocene age. Main faults have east – west direction and are subvertical.

  17. Projection operator method for collective tunneling transitions

    International Nuclear Information System (INIS)

    Collective tunneling transitions take place in the case that a system has two nearly degenerate ground states with a slight energy splitting, which provides the time scale of the tunneling. The Liouville equation determines the evolution of the density matrix, while the Schroedinger equation determines that of a state. The Liouville equation seems to be more powerful for calculating accurately the energy splitting of two nearly degenerate eigenstates. However, no method to exactly solve the Liouville eigenvalue equation has been established. The usual projection operator method for the Liouville equation is not feasible. We analytically solve the Liouville evolution equation for nuclear collective tunneling from one Hartree minimum to another, proposing a simple and solvable model Hamiltonian for the transition. We derive an analytical expression for the splitting of energy eigenvalues from a spectral function of the Liouville evolution using a half-projected operator method. A full-order analytical expression for the energy splitting is obtained. We define the collective tunneling path of a microscopic Hamiltonian for collective tunneling, projecting the nuclear ground states onto n-particle n-hole state spaces. It is argued that the collective tunneling path sector of a microscopic Hamiltonian can be transformed into the present solvable model Hamiltonian. (author)

  18. Heme uptake in bacterial pathogens

    OpenAIRE

    Contreras, Heidi; Chim, Nicholas; Credali, Alfredo; Goulding, Celia W.

    2014-01-01

    Iron is an essential nutrient for the survival of organisms. Bacterial pathogens possess specialized pathways to acquire heme from their human hosts. In this review, we present recent structural and biochemical data that provide mechanistic insights into several bacterial heme uptake pathways, encompassing the sequestration of heme from human hemoproteins to secreted or membrane-associated bacterial proteins, the transport of heme across bacterial membranes, and the degradation of heme within...

  19. Disposable bioluminescence-based biosensor for detection of bacterial count in food.

    Science.gov (United States)

    Luo, Jinping; Liu, Xiaohong; Tian, Qing; Yue, Weiwei; Zeng, Jing; Chen, Guangquan; Cai, Xinxia

    2009-11-01

    A biosensor for rapid detection of bacterial count based on adenosine 5'-triphosphate (ATP) bioluminescence has been developed. The biosensor is composed of a key sensitive element and a photomultiplier tube used as a detector element. The disposable sensitive element consists of a sampler, a cartridge where intracellular ATP is chemically extracted from bacteria, and a microtube where the extracted ATP reacts with the luciferin-luciferase reagent to produce bioluminescence. The bioluminescence signal is transformed into relevant electrical signal by the detector and further measured with a homemade luminometer. Parameters affecting the amount of the extracted ATP, including the types of ATP extractants, the concentrations of ATP extractant, and the relevant neutralizing reagent, were optimized. Under the optimal experimental conditions, the biosensor showed a linear response to standard bacteria in a concentration range from 10(3) to 10(8) colony-forming units (CFU) per milliliter with a correlation coefficient of 0.925 (n=22) within 5min. Moreover, the bacterial count of real food samples obtained by the biosensor correlated well with those by the conventional plate count method. The proposed biosensor, with characteristics of low cost, easy operation, and fast response, provides potential application to rapid evaluation of bacterial contamination in the food industry, environment monitoring, and other fields.

  20. Some Caves in tunnels in Dinaric karst of Croatia

    Science.gov (United States)

    Garasic, Mladen; Garasic, Davor

    2016-04-01

    In the last 50 years during the construction of almost all the tunnels in the Croatian Dinaric Karst thousands of caves have been encountered that represented the major problems during the construction works. Geological features (fissures, folding, faults, etc.) are described in this contribution, together with the hydrogeological conditions (rapid changes in groundwater levels). Special engineering geological exploration and survey of each cave, together with the stabilization of the tunnel ceiling, and groundwater protection actions according to basic engineering geological parameters are also presented. In karst tunneling in Croatia over 150 caves longer than 500 m have been investigated. Several caves are over 300 m deep (St. Ilija tunnel in Biokovo Mt), and 10 are longer than 1000 m (St.Rok tunnel, HE Senj and HE Velebit tunnels in Velebit Mt, Ucka tunnel in Ucka Mt, Mala kapela tunnel in Kapela Mt, caverns in HE Plat tunnel etc). Different solutions were chosen to cross the caves depending on the size and purpose of the tunnels (road, rail, pedestrian tunnel, or hydrotechnical tunnels). This is presentations of interesting examples of ceiling stabilization in big cave chambers, construction of bridges inside tunnels, deviations of tunnels, filling caves, grouting, etc. A complex type of karstification has been found in the cavern at the contact between the Palaeozoic clastic impervious formations and the Mesozoic complex of dolomitic limestones in the Vrata Tunnel and at the contact with flysch in the Učka Tunnel. However, karstification advancing in all directions at a similar rate is quite rare. The need to have the roadway and/or tunnel above water from a spring is the biggest possible engineering-geological, hydrogeological and civil engineering challenge. Significant examples are those above the Jadro spring (Mravinci tunnel) in flysch materials or above the Zvir spring in Rijeka (Katarina tunnel), and in fractured Mesozoic carbonates. Today in Croatian

  1. Tunneling and Transport in Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, Allen M. [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-08-16

    The goal of this program was to study new physical phenomena that might be relevant to the performance of conductive devices and circuits of the smallest realizable feature sizes possible using physical rather than biological techniques. Although the initial scientific work supported involved the use of scanning tunneling microscopy and spectroscopy to ascertain the statistics of the energy level distribution of randomly sized and randomly shaped quantum dots, or nano-crystals, the main focus was on the investigation of selected properties, including superconductivity, of conducting and superconducting nanowires prepared using electron-beam-lithography. We discovered a magnetic-field-restoration of superconductivity in out-of-equilibrium nanowires driven resistive by current. This phenomenon was explained by the existence of a state in which dissipation coexisted with nonvanishing superconducting order. We also produced ultra-small superconducting loops to study a predicted anomalous fluxoid quantization, but instead, found a magnetic-field-dependent, high-resistance state, rather than superconductivity. Finally, we developed a simple and controllable nanowire in an induced charged layer near the surface of a masked single-crystal insulator, SrTiO3. The layer was induced using an electric double layer transistor employing an ionic liquid (IL). The transport properties of the induced nanowire resembled those of collective electronic transport through an array of quantum dots.

  2. Theory of dissociative tunneling ionization

    Science.gov (United States)

    Svensmark, Jens; Tolstikhin, Oleg I.; Madsen, Lars Bojer

    2016-05-01

    We present a theoretical study of the dissociative tunneling ionization process. Analytic expressions for the nuclear kinetic energy distribution of the ionization rates are derived. A particularly simple expression for the spectrum is found by using the Born-Oppenheimer (BO) approximation in conjunction with the reflection principle. These spectra are compared to exact non-BO ab initio spectra obtained through model calculations with a quantum mechanical treatment of both the electronic and nuclear degrees of freedom. In the regime where the BO approximation is applicable, imaging of the BO nuclear wave function is demonstrated to be possible through reverse use of the reflection principle, when accounting appropriately for the electronic ionization rate. A qualitative difference between the exact and BO wave functions in the asymptotic region of large electronic distances is shown. Additionally, the behavior of the wave function across the turning line is seen to be reminiscent of light refraction. For weak fields, where the BO approximation does not apply, the weak-field asymptotic theory describes the spectrum accurately.

  3. Le LHC, un tunnel cosmique

    CERN Document Server

    CERN. Geneva

    2009-01-01

    Et si la lumière au bout du tunnel du LHC était cosmique ? En d’autres termes, qu’est-ce que le LHC peut nous apporter dans la connaissance de l’Univers ? Car la montée en énergie des accélérateurs de particules nous permet de mieux appréhender l’univers primordial, chaud et dense. Mais dans quel sens dit-on que le LHC reproduit des conditions proches du Big bang ? Quelles informations nous apporte-t-il sur le contenu de l’Univers ? La matière noire est-elle détectable au LHC ? L’énergie noire ? Pourquoi l’antimatière accumulée au CERN est-elle si rare dans l’Univers ? Et si le CERN a bâti sa réputation sur l’exploration des forces faibles et fortes qui opèrent au sein des atomes et de leurs noyaux, est-ce que le LHC peut nous apporter des informations sur la force gravitationnelle qui gouverne l’évolution cosmique ? Depuis une trentaine d’années, notre compréhension de l’univers dans ses plus grandes dimensions et l’appréhension de son comportement aux plus peti...

  4. Study on calculation of rock pressure for ultra-shallow tunnel in poor surrounding rock and its tunneling procedure

    Institute of Scientific and Technical Information of China (English)

    Xiaojun Zhou; Jinghe Wang; Bentao Lin

    2014-01-01

    A computational method of rock pressure applied to an ultra-shallow tunnel is presented by key block theory, and its mathematical formula is proposed according to a mechanical tunnel model with super-shallow depth. Theoretical analysis shows that the tunnel is subject to asymmetric rock pressure due to oblique topography. The rock pressure applied to the tunnel crown and sidewall is closely related to the surrounding rock bulk density, tunnel size, depth and angle of oblique ground slope. The rock pressure applied to the tunnel crown is much greater than that to the sidewalls, and the load applied to the left side-wall is also greater than that to the right sidewall. Mean-while, the safety of the lining for an ultra-shallow tunnel in strata with inclined surface is affected by rock pressure and tunnel support parameters. Steel pipe grouting from ground surface is used to consolidate the unfavorable surrounding rock before tunnel excavation, and the reinforcing scope is proposed according to the analysis of the asymmetric load induced by tunnel excavation in weak rock with inclined ground surface. The tunneling procedure of bench cut method with pipe roof protection is still discussed and carried out in this paper according to the special geological condition. The method and tunneling procedure have been successfully utilized to design and drive a real expressway tunnel. The practice in building the super-shallow tunnel has proved the feasibility of the calculation method and tunneling procedure presented in this paper.

  5. A Tunnel Compress Scheme for Multi-Tunneling in PMIPv6-based Nested NEMO

    Directory of Open Access Journals (Sweden)

    Youn-Hee Han

    2010-11-01

    Full Text Available In nested NEMO, a multi-tunneling causes a pinball routing problem. Several solutions proposed tosolve the pinball routing problem in NEMO BSP cannot be used at PMIPv6-based NEMO due todifferent environment such as no route optimization with CN. We propose a tunnel compress scheme formulti-tunneling in PMIPv6-based NEMO. The scheme consists of two parts: the first part is an interdomainor wired Internet part. The other is an intra part of nested mobile networks. In the inter-domainpart, single IP-in-IP tunnel is created by connecting an innermost entry point with an outermost exitpoint in original multi-tunnels. As the same way used in the inter-domain part, single IP-in-IP tunnel iscreated from the outermost exit point and an innermost exit point in original multi-tunnels. In theproposed scheme, IP-in-IP encapsulated packets are forwarded using host-based routing withoutmodifying the outer header. The information to compress multi-tunnels is piggybacked at the PMIPv6signaling.

  6. Tunnelling in Soft Soil: Tunnel Boring Machine Operation and Soil Response

    NARCIS (Netherlands)

    Festa, D.; Broere, W.; Bosch, J.W.

    2013-01-01

    Constructing tunnels in soft soil with the use of Tunnel Boring Machines may induce settlements including soil movements ahead of the face, soil relaxation into the tail void, possible heave due to grouting, long lasting consolidation processes, and potentially several other mechanisms. A considerab

  7. Quantum dot resonant tunneling diode single photon detector with aluminum oxide aperture defined tunneling area

    DEFF Research Database (Denmark)

    Li, H.W.; Kardynal, Beata; Ellis, D.J.P.;

    2008-01-01

    Quantum dot resonant tunneling diode single photon detector with independently defined absorption and sensing areas is demonstrated. The device, in which the tunneling is constricted to an aperture in an insulating layer in the emitter, shows electrical characteristics typical of high quality res...

  8. Microwave-induced co-tunneling in single electron tunneling transistors

    DEFF Research Database (Denmark)

    Ejrnaes, M.; Savolainen, M.; Manscher, M.;

    2002-01-01

    The influence of microwaves on the co-tunneling in single electron tunneling transistors has been investigated as function of frequency and power in the temperature range from 150 to 500 mK. All 20 low frequency connections and the RF line were filtered, and the whole cryostat was suspended on ru...

  9. European Tunnelling Review Quality, Environment and Safety Focus

    Institute of Scientific and Technical Information of China (English)

    Bill Weburn

    2004-01-01

    This paper provides an overview of tunnelling projects with some of the themes covered by the Chengdu Tunnelling Conference.(a) Environmental issues and tunnels under high groundwater pressure (Hallandsis Rail Tunnel, Sweden)(b) Fire -fighting and tunnel safety on long highway tunnels (Socatop Tunnel, West Paris)(c) Mechanised tunnelling below the world's largest airport (Heathrow T5) of a quality that avoids disruption to its operation.Each of these overviews show an enhanced performance in regard to project specific events or objectives. Particularly in tunnelling, project owners expect more than just a facility delivered on time for their money: they expect an all round performance respecting deadlines, budget, environmental protection, safety, quality and community harmony. Funding agencies do not always have the same agenda as project owners, acknowledging peripheral selection criteria but often demanding that the lowest bidder be awarded work. All round performance requires all round project selection criteria.

  10. Bacterial chemoreceptors and chemoeffectors.

    Science.gov (United States)

    Bi, Shuangyu; Lai, Luhua

    2015-02-01

    Bacteria use chemotaxis signaling pathways to sense environmental changes. Escherichia coli chemotaxis system represents an ideal model that illustrates fundamental principles of biological signaling processes. Chemoreceptors are crucial signaling proteins that mediate taxis toward a wide range of chemoeffectors. Recently, in deep study of the biochemical and structural features of chemoreceptors, the organization of higher-order clusters in native cells, and the signal transduction mechanisms related to the on-off signal output provides us with general insights to understand how chemotaxis performs high sensitivity, precise adaptation, signal amplification, and wide dynamic range. Along with the increasing knowledge, bacterial chemoreceptors can be engineered to sense novel chemoeffectors, which has extensive applications in therapeutics and industry. Here we mainly review recent advances in the E. coli chemotaxis system involving structure and organization of chemoreceptors, discovery, design, and characterization of chemoeffectors, and signal recognition and transduction mechanisms. Possible strategies for changing the specificity of bacterial chemoreceptors to sense novel chemoeffectors are also discussed.

  11. Bacterial Colony Optimization

    Directory of Open Access Journals (Sweden)

    Ben Niu

    2012-01-01

    Full Text Available This paper investigates the behaviors at different developmental stages in Escherichia coli (E. coli lifecycle and developing a new biologically inspired optimization algorithm named bacterial colony optimization (BCO. BCO is based on a lifecycle model that simulates some typical behaviors of E. coli bacteria during their whole lifecycle, including chemotaxis, communication, elimination, reproduction, and migration. A newly created chemotaxis strategy combined with communication mechanism is developed to simplify the bacterial optimization, which is spread over the whole optimization process. However, the other behaviors such as elimination, reproduction, and migration are implemented only when the given conditions are satisfied. Two types of interactive communication schemas: individuals exchange schema and group exchange schema are designed to improve the optimization efficiency. In the simulation studies, a set of 12 benchmark functions belonging to three classes (unimodal, multimodal, and rotated problems are performed, and the performances of the proposed algorithms are compared with five recent evolutionary algorithms to demonstrate the superiority of BCO.

  12. [Bacterial diseases of rape].

    Science.gov (United States)

    Zakharova, O M; Mel'nychuk, M D; Dankevych, L A; Patyka, V P

    2012-01-01

    Bacterial destruction of the culture was described and its agents identified in the spring and winter rape crops. Typical symptoms are the following: browning of stem tissue and its mucilagization, chlorosis of leaves, yellowing and beginning of soft rot in the place of leaf stalks affixion to stems, loss of pigmentation (violet). Pathogenic properties of the collection strains and morphological, cultural, physiological, and biochemical properties of the agents of rape's bacterial diseases isolated by the authors have been investigated. It was found that all the isolates selected by the authors are highly or moderately aggressive towards different varieties of rape. According to the complex of phenotypic properties 44% of the total number of isolates selected by the authors are related to representatives of the genus Pseudomonas, 37% - to Xanthomonas and 19% - to Pectobacterium. PMID:23293826

  13. Fluorometric determination of 2'-beta-fluoro-2',3'-dideoxyadenosine 5'-triphosphate, the active metabolite of a new anti-human immunodeficiency virus drug, in human lymphocytes.

    Science.gov (United States)

    Dai, F; Kelley, J A; Zhang, H; Malinowski, N; Kavlick, M F; Lietzau, J; Welles, L; Yarchoan, R; Ford, H

    2001-01-01

    A sensitive precolumn derivatization method has been developed to measure the 5'-triphosphate of 2'-beta-fluoro-2',3'-dideoxyadenosine (F-ddA, lodenosine), a new anti-HIV drug, in human lymphocytes by HPLC using fluorescence detection. Reaction of chloroacetaldehyde with F-ddA triphosphate in extracts from human lymphocytes produces a highly fluorescent etheno adduct. This derivative is then separated and quantitated by reverse-phase paired-ion chromatography. Degradation of natural nucleic acid ribosides, such as ATP, using periodate oxidation simplifies the chromatogram and minimizes interference with detection of the target analyte. This method, modeled using cultured MOLT-4 T-lymphocytes, achieves a linear detector response for peak area measurements over the range 2.5 to 22.5 pmol (50-450 nM using 50 microl sample). Analyte recovery is greater than 90%, and the method achieves a limit of detection and limit of quantitation of 1.4 and 2.5 pmol per HPLC injection (50 microl sample containing cellular extract from 2.5 x 10(6) cells), respectively. Application of this method to measure F-ddATP in peripheral blood mononuclear cells from HIV-infected patients treated with F-ddA at 3.2 mg/kg twice daily for 22 days shows F-ddATP levels which range from 1.5 to 3.5 pmol/10(6) cells. PMID:11141306

  14. Isolation of a gene encoding a developmentally regulated T cell-specific protein with a guanine nucleotide triphosphate-binding motif

    Energy Technology Data Exchange (ETDEWEB)

    Carlow, D.A.; Teh, H.S.; Marth, J. [Univ. of British Columbia, Vancouver (Canada)] [and others

    1995-02-15

    In this study, we describe a novel full length cDNA clone designated Tgtp that encodes a predicted 415-amino acid a T cell-specific guanine nucleotide triphosphate-binding protein (TGTP) bearing the characteristic motifs of a guanine nucleotide triphosphate (GTP) binding protein. Tgtp is expressed preferentially, if not exclusively, in T cells, and is up-regulated in both unfractionated and in purified CD4{sup +}8{sup +} thymocytes upon TCR cross-linking. In contrast, expression of Tgtp in peripheral T cells is maintained at relatively high levels and is not grossly affected by TCR cross-linking. Antiserum generated against synthetic peptides from the predicted TGTP amino acid sequence recognized a single protein with a molecular mass of {approx}50 kDa, corresponding well with the computed molecular mass of 47 kDa. The only known relative of Tgtp is MUSGTP, which is reportedly expressed in B cells and bears a GTP binding motif. Thus, the discovery of Tgtp resolves a subfamily of molecules with GTP binding motifs and apparent lymphoid lineage-restricted expression. Given the restricted expression pattern in T cells, the up-regulated expression observed in response to TCR signaling in immature thymocytes, and the presence of the motifs characteristic of GTP binding proteins, we suggest that TGTP may have an important function in T cell development and/or T cell activation. 51 refs., 6 figs.

  15. Pharmacogenetic research progress of inosine triphosphate pyrophosphatase%三磷酸肌苷焦磷酸酶药理遗传学的研究进展

    Institute of Scientific and Technical Information of China (English)

    李兴军

    2013-01-01

    嘌呤类药物主要用于治疗自身免疫性疾病、器官移植、急性淋巴细胞白血病等,其不良反应的发生率为15% ~28%,严重影响了药物在临床中的应用.三磷酸肌苷焦磷酸酶(inosine triphosphate pyrophosphatase,ITPA)存在个体间的差异,ITPA缺陷的患者在应用嘌呤类药物时会发生一定的不良反应,因此,有必要了解ITPA对嘌呤类药物临床应用的影响,该文综述了ⅡPA的药理遗传学方面的研究进展.%Purine drugs are for the treatment of autoimmune diseases,organ transplantation,acute lymphoblastic leukemia.The adverse reaction rate is 15% ~ 28%,which impacts on the clinical application in recent years.Studies have shown that inosine triphosphate pyrophosphatase (ITPA) are different between individuals,and there are adverse reactions in patients with defects of ITPA when purine drugs are used.This paper reviewes the ITPA pharmacogenetic research progresses.

  16. Simple, Fast and Selective Detection of Adenosine Triphosphate at Physiological pH Using Unmodified Gold Nanoparticles as Colorimetric Probes and Metal Ions as Cross-Linkers

    Directory of Open Access Journals (Sweden)

    Huan Pang

    2012-11-01

    Full Text Available We report a simple, fast and selective colorimetric assay of adenosine triphosphate (ATP using unmodified gold nanoparticles (AuNPs as probes and metal ions as cross-linkers. ATP can be assembled onto the surface of AuNPs through interaction between the electron-rich nitrogen atoms and the electron-deficient surface of AuNPs. Accordingly, Cu2+ ions induce a change in the color and UV/Vis absorbance of AuNPs by coordinating to the triphosphate groups and a ring nitrogen of ATP. A detection limit of 50 nM was achieved, which is comparable to or lower than that achievable by the currently used electrochemical, spectroscopic or chromatographic methods. The theoretical simplicity and high selectivity reported herein demonstrated that AuNPs-based colorimetric assay could be applied in a wide variety of fields by rationally designing the surface chemistry of AuNPs. In addition, our results indicate that ATP-modified AuNPs are less stable in Cu2+, Cd2+ or Zn2+-containing solutions due to the formation of the corresponding dimeric metal-ATP complexes.

  17. Radioimmunoassay for guanosin-5'-diphosphate-3'-diphosphate and adenosine-5'-triphosphate-3'-diphosphate

    Energy Technology Data Exchange (ETDEWEB)

    Hamagishi, Y.; Oki, T.; Tone, H.; Inui, T. (Sanraku-Ocean Co. Ltd., Fujisawa, Kanagawa (Japan). Central Research Lab.)

    1980-12-01

    A radioimmunoassay for guanosine-5'-diphosphate-3'-diphosphate (ppGpp) and adenosine-5'-triphosphate-3'-diphosphate (pppApp) has been developed. The assay method is based on competition of an unlabeled highly phosphorylated nucleotide with /sup 3/H-labeled highly phosphorylated nucleotide for binding sites on a specific antibody. Antibodies to ppGpp and pppApp were obtained by immunizing rabbits with the antigen prepared by conjugating ppGpp with human serum albumin using 1-ethyl-3-(3-dimethylaminoprophyl)carbodiimide, and with the antigen prepared by conjugating 8-(6-aminohexyl)amino-adenosine-5'-triphosphate-3'-diphosphate with human serum albumin using glutaraldehyde, respectively. Antibody-bound /sup 3/H-labeled highly phosphorylated nucleotides were separated from the free /sup 3/H-labeled highly phosphorylated nucleotides by selective adsorption on dextran-coated charcoal. Displacement plots were linear over a concentration range of 5 - 1,000 pmol/assay tube in a log-probit percentage plot. Application of this method to biological systems offers improved accuracy and convenience compared with the previous /sup 32/PO/sub 4/-labeling technique.

  18. Bacterial transformation of terpenoids

    International Nuclear Information System (INIS)

    Data on the bacterial transformation of terpenoids published in the literature in the past decade are analyzed. Possible pathways for chemo-, regio- and stereoselective modifications of terpenoids are discussed. Considerable attention is given to new technological approaches to the synthesis of terpenoid derivatives suitable for the use in the perfume and food industry and promising as drugs and chiral intermediates for fine organic synthesis. The bibliography includes 246 references

  19. Supramolecular bacterial systems

    OpenAIRE

    Sankaran, Shrikrishnan

    2015-01-01

    For nearly over a decade, a wide variety of dynamic and responsive supramolecular architectures have been investigated and developed to address biological systems. Since the non-covalent interactions between individual molecular components in such architectures are similar to the interactions found in living systems, it was possible to integrate chemically-synthesized and naturally-occurring components to create platforms with interesting bioactive properties. Bacterial cells and recombinant ...

  20. Bacterial Colony Optimization

    OpenAIRE

    Ben Niu; Hong Wang

    2012-01-01

    This paper investigates the behaviors at different developmental stages in Escherichia coli (E. coli) lifecycle and developing a new biologically inspired optimization algorithm named bacterial colony optimization (BCO). BCO is based on a lifecycle model that simulates some typical behaviors of E. coli bacteria during their whole lifecycle, including chemotaxis, communication, elimination, reproduction, and migration. A newly created chemotaxis strategy combined with communication mechanism i...

  1. The Cause of Shallow Tunnel Collapse and Simulation Analysis of Consolidation for a Collapsed Tunnel

    Directory of Open Access Journals (Sweden)

    Shucai Li

    2013-03-01

    Full Text Available In order to ensure the safety of the shallow tunnels construction, it is very important to find the reasons of the collapse. During Fujiachong tunnel construction, collapse of the section Yk25 + 547~Yk25 + 552. Distributions of cracked surrounding rock, rainfall, geological forecast were discussed for reason of tunnel collapse. According to in-situ construction condition, reinforced support program was applied to the surrounding rock consolidation of the tunnel. In order to assess consolidation effect, a cross-sections of collapse zone measurement was increased and simulation analysis was applied to the section. The results of in-situ measurement and simulation results show that tunneling collapse zone was consolidated by reinforced support program successfully.

  2. Flow Cytometric Assessment of Bacterial Abundance in Soils, Sediments and Sludge.

    Science.gov (United States)

    Frossard, Aline; Hammes, Frederik; Gessner, Mark O

    2016-01-01

    Bacterial abundance is a fundamental measure in microbiology, but its assessment is often tedious, especially for soil, and sediment samples. To overcome this limitation, we adopted a time-efficient flow-cytometric (FCM) counting method involving cell detachment and separation from matrix particles by centrifugation in tubes receiving sample suspensions and Histodenz(®) solution. We used this approach to assess bacterial abundances in diverse soils (natural and agricultural), sediments (streams and lakes) and sludge from sand-filters in a drinking water treatment plant and compared the results to bacterial abundances determined by two established methods, epifluorescence microscopy (EM) and adenosine triphosphate (ATP) quantification. Cell abundances determined by FCM and EM correlated fairly well, although absolute cell abundances were generally lower when determined by FCM. FCM also showed significant relations with cell counts converted from ATP concentrations, although estimates derived from ATP determinations were typically higher, indicating the presence of ATP sources other than bacteria. Soil and sediment organic matter (OM) content influenced the goodness of fit between counts obtained with EM and FCM. In particular, bacterial abundance determined by FCM in samples containing less than 10% OM, such as stream sediment, was particularly well correlated with the cell counts assessed by EM. Overall, these results suggest that FCM following cell detachment and purification is a useful approach to increase sample throughput for determining bacterial abundances in soils, sediments and sludge. However, notable scatter and only partial concordance among the FCM and reference methods suggests that protocols require further improvement for assessments requiring high precision, especially when OM contents in samples are high. PMID:27379043

  3. Flow Cytometric Assessment of Bacterial Abundance in Soils, Sediments and Sludge.

    Science.gov (United States)

    Frossard, Aline; Hammes, Frederik; Gessner, Mark O

    2016-01-01

    Bacterial abundance is a fundamental measure in microbiology, but its assessment is often tedious, especially for soil, and sediment samples. To overcome this limitation, we adopted a time-efficient flow-cytometric (FCM) counting method involving cell detachment and separation from matrix particles by centrifugation in tubes receiving sample suspensions and Histodenz(®) solution. We used this approach to assess bacterial abundances in diverse soils (natural and agricultural), sediments (streams and lakes) and sludge from sand-filters in a drinking water treatment plant and compared the results to bacterial abundances determined by two established methods, epifluorescence microscopy (EM) and adenosine triphosphate (ATP) quantification. Cell abundances determined by FCM and EM correlated fairly well, although absolute cell abundances were generally lower when determined by FCM. FCM also showed significant relations with cell counts converted from ATP concentrations, although estimates derived from ATP determinations were typically higher, indicating the presence of ATP sources other than bacteria. Soil and sediment organic matter (OM) content influenced the goodness of fit between counts obtained with EM and FCM. In particular, bacterial abundance determined by FCM in samples containing less than 10% OM, such as stream sediment, was particularly well correlated with the cell counts assessed by EM. Overall, these results suggest that FCM following cell detachment and purification is a useful approach to increase sample throughput for determining bacterial abundances in soils, sediments and sludge. However, notable scatter and only partial concordance among the FCM and reference methods suggests that protocols require further improvement for assessments requiring high precision, especially when OM contents in samples are high.

  4. Flow Cytometric Assessment of Bacterial Abundance in Soils, Sediments and Sludge

    Science.gov (United States)

    Frossard, Aline; Hammes, Frederik; Gessner, Mark O.

    2016-01-01

    Bacterial abundance is a fundamental measure in microbiology, but its assessment is often tedious, especially for soil, and sediment samples. To overcome this limitation, we adopted a time-efficient flow-cytometric (FCM) counting method involving cell detachment and separation from matrix particles by centrifugation in tubes receiving sample suspensions and Histodenz® solution. We used this approach to assess bacterial abundances in diverse soils (natural and agricultural), sediments (streams and lakes) and sludge from sand-filters in a drinking water treatment plant and compared the results to bacterial abundances determined by two established methods, epifluorescence microscopy (EM) and adenosine triphosphate (ATP) quantification. Cell abundances determined by FCM and EM correlated fairly well, although absolute cell abundances were generally lower when determined by FCM. FCM also showed significant relations with cell counts converted from ATP concentrations, although estimates derived from ATP determinations were typically higher, indicating the presence of ATP sources other than bacteria. Soil and sediment organic matter (OM) content influenced the goodness of fit between counts obtained with EM and FCM. In particular, bacterial abundance determined by FCM in samples containing less than 10% OM, such as stream sediment, was particularly well correlated with the cell counts assessed by EM. Overall, these results suggest that FCM following cell detachment and purification is a useful approach to increase sample throughput for determining bacterial abundances in soils, sediments and sludge. However, notable scatter and only partial concordance among the FCM and reference methods suggests that protocols require further improvement for assessments requiring high precision, especially when OM contents in samples are high. PMID:27379043

  5. Uncertainty analysis of tunnel squeezing for two tunnel cases from Nepal Himalaya

    Energy Technology Data Exchange (ETDEWEB)

    Panthi, K.K.; Nilsen, B. [Norwegian University of Science and Technology, Trondheim (Norway). Department of Geology and Mineral Resources Engineering

    2007-01-15

    Weak rocks such as shale, slate, phyllite and schist, and the rock mass of weakness/fault zones are incapable of sustaining high tangential stress. Severe tunnel squeezing is therefore common in the tectonically active Himalayan rock mass is one of the major areas of concern regarding stability. A reliable prediction of the extent of squeezing is essential so that a strategy can be established regarding stabilizing measures and for optimizing the support well in advance (during planning and design). In this paper, a probabilistic approach to uncertainty analysis that focuses on the effect of the variation in each input parameter of squeezing is used for analyzing and predicting the extent of tunnel squeezing for two tunnel cases in Nepal; Kalingandaki 'A' (completed) and Middle Marsyangdi (under construction). A semi-analytical method suggested by Hoek and Marinos [Predicting tunnel squeezing problems in weak heterogeneous rock masses. Tunnels Tunnell Int, 2000; 32(11 and 12): 45-51 and 34-36] for predicting squeezing, an empirical formula proposed by Panthi [Analysis of engineering geological uncertainties related to tunnelling in Himalayan rock mass conditions. PhD thesis, Department of Geology and Mineral Resources Engineering. Norwegian University of Science and Technology (NTNU), Norway, 2006] and the Palisade's 2002 version of 'At' Risk statistical software program have been used for the uncertainty analysis. The analysis results for Kaligandaki indicate fairly good correlation between predicted and actually measured squeezing. The same approach has been used for predicting the degree of tunnel squeezing at Middle Marsyangdi tunnel. It is concluded that the methodology proposed in this paper has potential for predicting the squeezing of future tunnel projects in weak rock mass conditions. (author)

  6. Particle detection with superconducting tunnel junctions

    International Nuclear Information System (INIS)

    At the Institute of Experimental Nuclear Physics of the University of Karlsruhe (TH) and at the Institute for Nuclear Physics of the Kernforschungszentrum Karlsruhe we started to produce superconducting tunnel junctions and to investigate them for their suitability as particle detectors. The required facilities for the production of tunnel junctions and the experimental equipments to carry out experiments with them were erected. Experiments are presented in which radiations of different kinds of particles could successfully be measured with the tunnel junctions produced. At first we succeeded in detectioning light pulses of a laser. In experiments with alpha-particles of an energy of 4,6 MeV the alpha-particles were detected with an energy resolution of 1,1%, and it was shown in specific experiments that the phonons originating from the deposition of energy by an alpha-particle in the substrate can be detected with superconducting tunnel junctions at the surface. On that occasion it turned out that the signals could be separated with respect to their point of origin (tunnel junction, contact leads, substrate). Finally X-rays with an energy of 6 keV were detected with an energy resolution of 8% in a test arrangement that makes use of the so-called trapping effect to read out a larger absorber volume. (orig.)

  7. Tunnel Ventilation Control Using Reinforcement Learning Methodology

    Science.gov (United States)

    Chu, Baeksuk; Kim, Dongnam; Hong, Daehie; Park, Jooyoung; Chung, Jin Taek; Kim, Tae-Hyung

    The main purpose of tunnel ventilation system is to maintain CO pollutant concentration and VI (visibility index) under an adequate level to provide drivers with comfortable and safe driving environment. Moreover, it is necessary to minimize power consumption used to operate ventilation system. To achieve the objectives, the control algorithm used in this research is reinforcement learning (RL) method. RL is a goal-directed learning of a mapping from situations to actions without relying on exemplary supervision or complete models of the environment. The goal of RL is to maximize a reward which is an evaluative feedback from the environment. In the process of constructing the reward of the tunnel ventilation system, two objectives listed above are included, that is, maintaining an adequate level of pollutants and minimizing power consumption. RL algorithm based on actor-critic architecture and gradient-following algorithm is adopted to the tunnel ventilation system. The simulations results performed with real data collected from existing tunnel ventilation system and real experimental verification are provided in this paper. It is confirmed that with the suggested controller, the pollutant level inside the tunnel was well maintained under allowable limit and the performance of energy consumption was improved compared to conventional control scheme.

  8. Performance Analysis of VOIP over GRE Tunnel

    Directory of Open Access Journals (Sweden)

    Aria. Asadi Eskandar

    2015-11-01

    Full Text Available Voice over IP (VoIP is commonly known as phone service over the Internet. Any service using public IP network requires certain extent of security. Demand for security in VOIP technology is increasing. VPN is one of the commonly used methods to secure VOIP traffic. In this paper we simulated behavior of a VOIP communication while running over a GRE VPN Tunnel using OPNET Modeler 17.5. During the simulation, such performance parameters as: choice of voice signaling protocol, voice Codec, parameters arising from network QoS (in this study, homogenous vs. heterogeneous network environment and type of VPN tunneling protocol, were examined. We evaluated performance of VOIP communications in homogenous and heterogeneous network environments, configured based on two different signaling protocols, namely H.323 and SIP. Also, G.711 and G.723 were configured and tested as the choice for voice Codecs. GRE was implemented as the tunneling protocol. Result analysis of this study indicated that GRE Tunnel didn't show a significant increase in such call quality of service (QoS performance factors as: end-to-end delay, call setup time, or a decrease in call MOS value. Even though in a non-ideal (heterogeneous network environment, call quality of service (QoS performance factors shoed poor results; however, there was no significant evidence to suggest that GRE Tunnel is the root cause for such poor results.

  9. Graphene-based magnetic tunnel junctions

    Science.gov (United States)

    Cobas, Enrique

    2013-03-01

    Graphene's in-plane transport has been widely researched and has yielded extraordinary carrier mobilities of 105 cm2/Vs and spin diffusion lengths of exceeding 100 μm. These properties bode well for graphene in future electronics and spintronics technologies. Its out-of-plane transport has been far less studied, although its parent material, graphite, shows a large conductance anisotropy. Recent calculations show graphene's interaction with close-packed ferromagnetic metal surfaces should produce highly spin-polarized transport out-of-plane, an enabling breakthrough for spintronics technology. In this work, we fabricate and measure FM/graphene/FM magnetic tunnel junctions using CVD-grown single-layer graphene. The resulting juctions show non-linear current-voltage characteristics and a very weak temperature dependence consistent with charge tunneling transport. Furthermore, we study spin transport across the junction as a function of bias voltage and temperature. The tunneling magnetoresistance (TMR) peaks at two percent for single-layer graphene junctions and exhibits the expected bias asymmetry and a temperature dependence that fits well with established spin-polarized tunneling models. Results of mutli-layer graphene tunnel junctions will also be discussed.

  10. Positioning systems for underground tunnel environments

    CERN Document Server

    Leite Pereira, Fernando; Theis, Christian

    In the last years the world has witnessed a remarkable change in the computing concept by entering the mobile era. Incredibly powerful smartphones have proliferated at stunning pace and tablet computers are capable of running demanding applications and meet new business requirements. Being wireless, localization has become crucial not only to serve individuals but also help companies in industrial and safety processes. In the context of the Radiation Protection group at CERN, automatic localization, besides allowing to find people, would help improving the radiation surveys performed regularly along the accelerator tunnels. The research presented in this thesis attempts to answer questions relatively to the viability of localization in a harsh conditions tunnel: “Is localization in a very long tunnel possible, meeting its restrictions and without incurring prohibitive costs and infrastructure?”, “Can one achieve meter-level accuracy with GSM deployed over leaky-feeder?”, “Is it possible to prototype...

  11. High Performance Single Nanowire Tunnel Diodes

    DEFF Research Database (Denmark)

    Wallentin, Jesper; Persson, Johan Mikael; Wagner, Jakob Birkedal;

    is the tunnel (Esaki) diode, which provides a low-resistance connection between junctions. We demonstrate an InP-GaAs NW axial heterostructure with tunnel diode behavior. InP and GaAs can be readily n- and p-doped, respectively, and the heterointerface is expected to have an advantageous type II band alignment...... NWs were contacted in a NW-FET setup. Electrical measurements at room temperature display typical tunnel diode behavior, with a Peak-to-Valley Current Ratio (PVCR) as high as 8.2 and a peak current density as high as 329 A/cm2. Low temperature measurements show improved PVCR of up to 27.6....

  12. Phonon tunneling through a double barrier system

    Energy Technology Data Exchange (ETDEWEB)

    Villegas, Diosdado [Departamento de Física, Universidad Central “Marta Abreu” de Las Villas, CP 54830, Santa Clara, Villa Clara (Cuba); Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico); León-Pérez, Fernando de [Centro Universitario de la Defensa de Zaragoza, Ctra. de Huesca s/n, E-50090 Zaragoza (Spain); Pérez-Álvarez, R. [Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca (Mexico); Arriaga, J., E-mail: arriaga@ifuap.buap.mx [Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico)

    2015-04-15

    The tunneling of optical and acoustic phonons at normal incidence on a double-barrier is studied in this paper. Transmission coefficients and resonance conditions are derived theoretically under the assumption that the long-wavelength approximation is valid. It is shown that the behavior of the transmission coefficients for the symmetric double barrier has a Lorentzian form close to resonant frequencies and that Breit–Wigner's formula have a general validity in one-dimensional phonon tunneling. Authors also study the so-called generalized Hartman effect in the tunneling of long-wavelength phonons and show that this effect is a numerical artifact resulting from taking the opaque limit before exploring the variation with a finite barrier width. This study could be useful for the design of acoustic devices.

  13. Quantum tunneling from paths in complex time

    CERN Document Server

    Bramberger, Sebastian F; Lehners, Jean-Luc

    2016-01-01

    We study quantum mechanical tunneling using complex solutions of the classical field equations. Simple visualization techniques allow us to unify and generalize previous treatments, and straightforwardly show the connection to the standard approach using Euclidean instanton solutions. We demonstrate that the negative modes of solutions along various contours in the complex time plane reveal which paths contribute to tunneling and which do not, and we provide a criterion for identifying the negative modes. Central to our approach is the solution of the background and perturbation equations not only along a single path, but over an extended region of the complex time plane. Our approach allows for a fully continuous and coherent treatment of classical evolution interspersed by quantum tunneling events, and is applicable in situations where singularities are present and also where Euclidean solutions might not exist.

  14. Scanning Tunneling Spectroscope Use in Electrocatalysis Testing

    Directory of Open Access Journals (Sweden)

    Turid Knutsen

    2010-06-01

    Full Text Available The relationship between the electrocatalytic properties of an electrode and its ability to transfer electrons between the electrode and a metallic tip in a scanning tunneling microscope (STM is investigated. The alkaline oxygen evolution reaction (OER was used as a test reaction with four different metallic glasses, Ni78Si8B14, Ni70Mo20Si5B5, Ni58Co20Si10B12, and Ni25Co50Si15B10, as electrodes. The electrocatalytic properties of the electrodes were determined. The electrode surfaces were then investigated with an STM. A clear relationship between the catalytic activity of an electrode toward the OER and its tunneling characteristics was found. The use of a scanning tunneling spectroscope (STS in electrocatalytic testing may increase the efficiency of the optimization of electrochemical processes.

  15. Tunneling spectra of graphene on copper unraveled

    DEFF Research Database (Denmark)

    Zhang, Xin; Stradi, Daniele; Liu, Lei;

    2016-01-01

    of the variability in tunneling spectra is the variation in graphene-substrate coupling under various experimental conditions, providing a salutary perspective on the important role of 2D material-substrate interactions. The conclusions are drawn from measured data and theoretical calculations for monolayer, AB......Scanning tunneling spectroscopy is often employed to study two-dimensional (2D) materials on conductive growth substrates, in order to gain information on the electronic structures of the 2D material-substrate systems, which can lead to insight into 2D material-substrate interactions, growth...... mechanisms, etc. The interpretation of the spectra can be complicated, however. Specifically for graphene grown on copper, there have been conflicting reports of tunneling spectra. A clear understanding of the mechanisms behind the variability is desired. In this work, we have revealed that the root cause...

  16. Vibration Compensation for Scanning Tunneling Microscope

    Institute of Scientific and Technical Information of China (English)

    LI Meng-chao; FU Xing; WEI Xiao-lei; HU Xiao-tang

    2003-01-01

    The influence of vibration is already one of main obstacles for improving the nano measuring accuracy.The techniques of anti-vibration,vibration isolation and vibration compensation become an important branch in nano measuring field.Starting with the research of sensitivity to vibration of scanning tunneling microscope(STM),the theory,techniques and realization methods of nano vibration sensor based on tunnel effect are initially investigated,followed by developing the experimental devices.The experiments of the vibration detection and vibration compensation are carried out.The experimental results show that vibration sensor based on tunnel effect is characterized by high sensitivity,good frequency characteristic and the same vibratory response characteristic consistent with STM.

  17. Vibration analysis of wind tunnel support

    Institute of Scientific and Technical Information of China (English)

    张旭; 张家泰; 董国庆; 张国友; 刘德富

    2004-01-01

    In order to enable a wind tunnel support to have a high enough natural frequency to prevent experiencing mechanical resonance and excessive vibration displacement, five kinds of wind tunnel support structures have been simulated and analyzed individually under five different load conditions by means of a nonlinear finite element numerical method. With natural frequency and three directions vibration displacement given, simulation and analyses indicated that additional supports is more beneficial than heightening the rigidity of steel reinforced concrete in support pillars and adopting steel wrappers on the pillars to increase natural frequency of support structure. Increasing the rigidity of steel reinforced concrete, adopting steel wrappers and providing additional supports are all helpful in reducing three directions vibration Max displacement. and additional supports are comparatively more effective. Therefore, a structure scheme with steel reinforced concrete support pillars,steel wrappers and additional supports should be adopted in practical wind tunnel support construction.

  18. Numerical studies of electron tunnelling in liquids

    International Nuclear Information System (INIS)

    The diffusion equation, derived from Fick's second law, with an added exponential sink term to simulate electron tunnelling, is integrated numerically to determine the rate of electron decay at times greater than 1 ps. The effect of a Coulomb interaction with a charged scavenger is examined and the steady-state rate constant shown to approximate closely to that obtained by combining the separate effects of tunnelling and charge-affected diffusion, which can be expressed analytically. Diffusion in the presence of a charge-induced dipole interaction is investigated for the case of scavenging of localised electrons in alkanes. The rate constant is shown to be dominated by random diffusion and tunnelling and the bias induced by the interaction is of little consequence. The sensitivity of the rate constant to changes in the pre-exponential factor in the sink term is shown to be most favourable at short times. (author)

  19. Electronic thermometry in tunable tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Maksymovych, Petro

    2016-03-15

    A tunable tunnel junction thermometry circuit includes a variable width tunnel junction between a test object and a probe. The junction width is varied and a change in thermovoltage across the junction with respect to the change in distance across the junction is determined. Also, a change in biased current with respect to a change in distance across the junction is determined. A temperature gradient across the junction is determined based on a mathematical relationship between the temperature gradient, the change in thermovoltage with respect to distance and the change in biased current with respect to distance. Thermovoltage may be measured by nullifying a thermoelectric tunneling current with an applied voltage supply level. A piezoelectric actuator may modulate the probe, and thus the junction width, to vary thermovoltage and biased current across the junction. Lock-in amplifiers measure the derivatives of the thermovoltage and biased current modulated by varying junction width.

  20. Electrodiagnostic approach to carpal tunnel syndrome

    Directory of Open Access Journals (Sweden)

    Cherian Ajith

    2006-01-01

    Full Text Available An algorithm for an electrophysiological approach to carpal tunnel syndrome is proposed. This technical note takes into account the standard tests, comparison tests and needle electromyography. If the standard tests are negative, a comparison study can be done to identify cases of minimal or very mild carpal tunnel syndrome (CTS. If comparison studies are negative, CTS can be ruled out and a search for other causes have to be made. If the standard tests are positive, carpal tunnel syndrome can be divided into extreme, severe,moderate and mild cases. Motor comparison study is useful in extreme CTS cases. Needle electromyography is a must in all cases where the standard tests are positive. This streamlined approach allows accurate diagnosis with minimum essential tests.

  1. SKB - PNC. Development of tunnel radar antennas

    International Nuclear Information System (INIS)

    Tunnel antennas for the RAMAC borehole radar system have been developed and tested in the field. The antennas are of the loaded dipole type and the receiver and transmitter electronics have been rebuilt to screen them from the antennas. A series of measurements has demonstrated that the radar pulse is short and well shaped and relatively free from ringing, even compared with the existing borehole antennas. Two antenna sets were tested: one centered at 60 MHz and another above 100 MHz. Both produced excellent radar pictures when tested in tunnels in Stripa mine. The antennas have been designed to be easy to carry, since the signal quality often depends on the way the antenna is held relative to electric conductors in the tunnels. (au) (46 figs., 57 refs.)

  2. The Tunnel Boring Machine Advancements in Horizontal and Up-Hill Tunnels

    Directory of Open Access Journals (Sweden)

    Stefano Fuoco

    2009-01-01

    Full Text Available Problem statement: Nowadays high levels of experience have been acquired in the excavation of horizontal tunnels using TBM, especially as far as tunnels with small diameters (about 4 m wide are concerned. Less experience has been acquired in the excavation of tunnels under difficult alignment conditions, as in the case of steeply inclined excavations (up-hill tunnels. Approach: This study presented the results of studies which compare the production data collected for tunnels excavated with TBM in "normal" conditions (horizontal tunnel, with those derived from steeply inclined excavations (up-hill tunnels. Results: From an examination of the results obtained in the studied cases a net difference appears evident in terms of productivity between horizontal and up-hill excavations. Conclusion: Such net difference between horizontal and up-hill excavation productions can be attributed to the greater burdens of times necessary for the supply of materials and personnel, the regripping operations with fall preventer systems and, in general, the greater difficulties of carrying out ordinary and extraordinary maintenance of the machines in particularly difficult altrimetric conditions.

  3. Carpal tunnel syndrome after 22 years of Colle's fracture

    Directory of Open Access Journals (Sweden)

    Goyal V

    2003-01-01

    Full Text Available Delayed carpal tunnel syndrome is rare. We describe the electrophysiological findings in a patient with Colle's fracture, who developed carpal tunnel syndrome 22 years after a wrist injury.

  4. Carpal tunnel syndrome: an unusual presentation of brachial hypertrophy.

    OpenAIRE

    Shenoy, K T; Saha, P. K.; Ravindran, M

    1980-01-01

    A patient with carpal tunnel syndrome in association with congenital hypertrophy of right upper limb is described. The median nerve also showed hypertrophy. The symptoms were relieved by decompression of the carpal tunnel.

  5. Wind Tunnel Measurements at LM Wind Power

    DEFF Research Database (Denmark)

    Bertagnolio, Franck

    2012-01-01

    This section presents the results obtained during the experimental campaign that was conducted in the wind tunnel at LM Wind Power in Lunderskov from August 16th to 26th, 2010. The goal of this study is to validate the so-called TNO trailing edge noise model through measurements of the boundary...... layer turbulence characteristics and the far-field noise generated by the acoustic scattering of the turbulent boundary layer vorticies as they convect past the trailing edge. This campaign was conducted with a NACA0015 airfoil section that was placed in the wind tunnel section. It is equipped with high...

  6. Phonoemissive Spin Tunneling in Molecular Nanomagnets

    OpenAIRE

    Garg, Anupam

    2011-01-01

    A new mechanism is proposed for the magnetization reversal of molecular nanomagnets such as \\Fe8. In this process the spin tunnels from the lowest state near one easy direction to the first excited state near the opposite easy direction, and subsequently decays to the second easy direction with the emission of a phonon, or it first emits a phonon and then tunnels to the final state. This mechanism is the simplest imaginable one that allows magnetization relaxation in the presence of a longitu...

  7. Quantum time scales in alpha tunneling

    CERN Document Server

    Kelkar, N G; Nowakowski, M

    2008-01-01

    The theoretical treatment of alpha decay by Gamow is revisited by investigating the quantum time scales in tunneling. The time spent by an alpha particle in front of the barrier and traversing it before escape is evaluated using microscopic alpha nucleus potentials. The half-life of a nucleus is shown to correspond to the time spent by the alpha knocking in front of the barrier. Calculations for medium and super heavy nuclei show that from a multitude of available tunneling time definitions, the transmission dwell time gives the bulk of the lifetime of the decaying state, in most cases.

  8. Reliability assessment of tunneling flow charts

    International Nuclear Information System (INIS)

    When driving horizontal workings of different kinds it is typical to reserve excessive redundant equipment. However, the lack of resources (facilities, people) and poor management don't ensure goal achievement [3]. The paper presents reliability assessment method of tunneling with the help of mathematical modeling. The mathematical model is developed on the basis of factual data of tunneling conditions and no-failure operation probabilities of the flow chart elements are estimated. The method of reliability assessment allows identifying organizational, technological and technical elements of the reserves to increases drive efficiency and improve feasibility characteristics

  9. Reliability assessment of tunneling flow charts

    Science.gov (United States)

    Antropova, N. A.; Krets, V. G.; Luk'yanov, V. G.; Baranova, A. V.

    2015-02-01

    When driving horizontal workings of different kinds it is typical to reserve excessive redundant equipment. However, the lack of resources (facilities, people) and poor management don't ensure goal achievement [3]. The paper presents reliability assessment method of tunneling with the help of mathematical modeling. The mathematical model is developed on the basis of factual data of tunneling conditions and no-failure operation probabilities of the flow chart elements are estimated. The method of reliability assessment allows identifying organizational, technological and technical elements of the reserves to increases drive efficiency and improve feasibility characteristics.

  10. A study for the KAERI research tunnel

    International Nuclear Information System (INIS)

    Major goal of the R and D on the KAERI Research Tunnel in 1997 are 1) concept development of the KAERI research tunnel and its major units 2) computer simulation of facilities 3) study on thermo-hydro mechanical coupling in the vicinity of a waste repository 4) effect of excavated distrubed zone. In addition supplementary site investigation to understand the distribution of stresses in the site was done along with long term monitoring of the water table. (author). 44 refs., 16 tabs., 36 figs

  11. Generalized Bessel functions in tunnelling ionization

    CERN Document Server

    Reiss, H R

    2003-01-01

    We develop two new approximations for the generalized Bessel function that frequently arises in the analytical treatment of strong-field processes, especially in non-perturbative multiphoton ionization theories. Both these new forms are applicable to the tunnelling environment in atomic ionization, and are analytically much simpler than the currently used low-frequency asymptotic approximation for the generalized Bessel function. The second of the new forms is an approximation to the first, and it is the second new form that exhibits the well-known tunnelling exponential.

  12. Dephasing of quantum tunnelling in molecular nanomagnets

    Institute of Scientific and Technical Information of China (English)

    Zhang Shu-Qun; Chen Zhi-De

    2008-01-01

    Dephasing mechanism of quantum tunnelling in molecular magnets has been studied by means of the spin-coherentstate path integral in a mean field approximation. It is found that the fluctuating uncompensated transverse field from the dipolar-dipolar interaction between molecular magnets contributes a random phase to the quantum interference phase. The resulting transition rate is determined by the average tunnel splitting over the random phase. Such a dephasing process leads to the suppression of quenching due to the quantum phase interference, and to the steps due to odd resonances in hysteresis loop survived, which is in good agreement with experimental observations in molecular nanomagnets Fee and Mn12.

  13. Prevalence of carpal tunnel syndrome in motorcyclists.

    Science.gov (United States)

    Manes, Harvey R

    2012-05-01

    Carpal tunnel syndrome is prevalent in patients who have a repetitive motion, vibration, or pressure exerted on the wrist joint for an extended period of time. The prevalence of this condition in the general population is approximately 5%. Motorcyclists subject themselves to high levels of vibration from the road and use their wrists to control the motorcycle's brakes, gas intake, and gears via the handlebars. Under these conditions, the author hypothesized that an increased prevalence of carpal tunnel syndrome would be observed in this population.

  14. Treatment of repetitive use carpal tunnel syndrome

    Science.gov (United States)

    Smith, Chadwick F.; Vangsness, C. Thomas; Anderson, Thomas; Good, Wayne

    1995-05-01

    In 1990, a randomized, double-blind study was initiated to evaluate the use of an eight-point conservative treatment program in carpal tunnel syndrome. A total of 160 patients were delineated with symptoms of carpal tunnel syndrome. These patients were then divided into two groups. Both groups were subjected to an ergonomically correct eight-point work modification program. A counterfeit low level laser therapy unit was utilized in Group A, while an actual low level laser therapy unit was utilized in Group B. The difference between Groups A and B was statistically significant in terms of return to work, conduction study improvement, and certain range of motion and strength studies.

  15. Resonant tunneling in graphene pseudomagnetic quantum dots.

    Science.gov (United States)

    Qi, Zenan; Bahamon, D A; Pereira, Vitor M; Park, Harold S; Campbell, D K; Neto, A H Castro

    2013-06-12

    Realistic relaxed configurations of triaxially strained graphene quantum dots are obtained from unbiased atomistic mechanical simulations. The local electronic structure and quantum transport characteristics of y-junctions based on such dots are studied, revealing that the quasi-uniform pseudomagnetic field induced by strain restricts transport to Landau level- and edge state-assisted resonant tunneling. Valley degeneracy is broken in the presence of an external field, allowing the selective filtering of the valley and chirality of the states assisting in the resonant tunneling. Asymmetric strain conditions can be explored to select the exit channel of the y-junction.

  16. Vibration measurement and modal analysis for tunneller

    Institute of Scientific and Technical Information of China (English)

    HUANG Min; WU Miao; WEI Ren-zhi

    2001-01-01

    In this paper, the method of vibration measurement and modal analysis for AM~50 Tunneller machine is presented. When the machine was used for cutting man-made coal bed and real coal bed, the vibration of the machine was measured and the results of signal analysis show that the vibration characteristics under the two kinds of working situations are similar. The modal model of the machine is established, and then, the intrinsic vibration characteristics of AM50 tunneller are investigated by means of the method of experimental modal analysis. The vibration response simulation under a set of loading spectra measured is carried out by force response simulation software.

  17. Fire Resistant Panels for the Tunnel Linings

    Directory of Open Access Journals (Sweden)

    Gravit Marina

    2016-01-01

    Full Text Available Presents the results of studies of innovative materials in the field of experimental and theoretical research fire resistance fireproof panels Pyro-Safe Aestuver T. Owing to the assembly simplicity, materials cheapness, high ecological standard, recycling, reuse potential, are benefit. Research work is running to improve the knowledge about fireproof panels Pyro-Safe Aestuver T for tunnel lining, its basic performance, its long term behavior and in particular also its fire proof for example when used for the lining of road tunnels.

  18. Microscopic tunneling theory of long Josephson junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, N.; Hattel, Søren A.; Samuelsen, Mogens Rugholm

    1992-01-01

    We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate that the detai......We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate...

  19. Traceable long range scanning tunneling microscopy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Dimensionally correct and directly traceable measurement is not feasible with conventional scanning tunneling microscopy (STMs) due to severe hysteresis and non-linearity of the commonly applied piezo tube scanners and the very short range.By integrating a custom made probing system based on tunneling current measurement into a commercially available and laser-interferometrically position controlled positioning system, an STM with a principal measuring range of 25 mm×25 mm×5 mm and traceable position measurement has been set-up and tested.

  20. Dielectric Engineered Tunnel Field-Effect Transistor

    OpenAIRE

    Ilatikhameneh, Hesameddin; Tarek A. Ameen; Klimeck, Gerhard; Appenzeller, Joerg; Rahman, Rajib

    2015-01-01

    The dielectric engineered tunnel field-effect transistor (DE-TFET) as a high performance steep transistor is proposed. In this device, a combination of high-k and low-k dielectrics results in a high electric field at the tunnel junction. As a result a record ON-current of about 1000 uA/um and a subthreshold swing (SS) below 20mV/dec are predicted for WTe2 DE-TFET. The proposed TFET works based on a homojunction channel and electrically doped contacts both of which are immune to interface stat...

  1. A Tunnel Compress Scheme for Multi-Tunneling in PMIPv6-based Nested NEMO

    OpenAIRE

    Youn-Hee Han; Hyo-Beom Lee; Min-Soo Woo; Sung-Gi Min

    2010-01-01

    In nested NEMO, a multi-tunneling causes a pinball routing problem. Several solutions proposed tosolve the pinball routing problem in NEMO BSP cannot be used at PMIPv6-based NEMO due todifferent environment such as no route optimization with CN. We propose a tunnel compress scheme formulti-tunneling in PMIPv6-based NEMO. The scheme consists of two parts: the first part is an interdomainor wired Internet part. The other is an intra part of nested mobile networks. In the inter-domainpart, singl...

  2. Spin-polarized tunneling in MgO-based tunnel junctions with superconducting electrodes

    Science.gov (United States)

    Schebaum, Oliver; Fabretti, Savio; Moodera, Jagadeesh S.; Thomas, Andy

    2012-03-01

    We prepared magnetic tunnel junctions with one ferromagnetic and one superconducting Al-Si electrode. Pure cobalt electrodes were compared with a Co-Fe-B alloy and the Heusler compound Co2FeAl. The polarization of the tunneling electrons was determined using the Maki-Fulde model and is discussed along with the spin-orbit scattering and the total pair-breaking parameters. The junctions were post-annealed at different temperatures to investigate the symmetry filtering mechanism responsible for the giant tunneling magnetoresistance ratios in Co-Fe-B/MgO/Co-Fe-B junctions.

  3. The effect of the tortoise coordinates on the tunnel effect

    CERN Document Server

    Gui-hua, T; Wang, S; Gui-hua, Tian; Zheng, Zhao; Wang, Shi-kun

    2006-01-01

    The tunnel process of the quantum wave from the light cone is carefully discussed. They are applied in the massive quantum particles from the Schwarzschild black hole in the Kruskal metric. The tortoise coordinates prevent one from understanding the tunnel process, and are investigated with care. Furthermore, the massive particles could come out of the black hole either by the Hawking radiation or by the tunnel effect; the tunnel effect might give more information about the black hole.

  4. Energetically constrained co-tunneling of cold atoms

    OpenAIRE

    Kolovsky, Andrey R.; Link, Julia; Wimberger, Sandro

    2011-01-01

    We study under-barrier tunneling for a pair of energetically bound bosonic atoms in an optical lattice with a barrier. We identify conditions under which this exotic molecule tunnels as a point particle with the coordinate given by the bound pair center of mass and discuss the atomic co-tunneling beyond this regime. In particular, we quantitatively analyze resonantly enhanced co-tunneling, where two interacting atoms penetrate the barrier with higher probability than a single atom.

  5. Dynamic Instability of Tunnel in Blocky Rock Mass

    Institute of Scientific and Technical Information of China (English)

    QI Chengzhi; CHEN Canshou; QIAN Qihu; LUO Jian

    2008-01-01

    The displacements and geometry of the rock blocks and the properties of the rock structure play an important role in the stability of tunnels.Based on the key block model, the dynamic instability analysis of underground tunnel subjected to intensive short-time compressional wave was conducted.The instability of the tunnel caused by the spallation and the inertial effect was distinguished.And the influence of the roof contour curvature of tunnel was also determined.

  6. An Exact Solution for Quantum Tunneling in a Dissipative System

    OpenAIRE

    Yu, Li Hua

    1996-01-01

    Applying a technique developed recently [1,2] for an harmonic oscillator coupled to a bath of harmonic oscillators, we present an exact solution for the tunneling problem in an Ohmic dissipative system with inverted harmonic potential. The result shows that while the dissipation tends to suppress the tunneling, the Brownian motion tends to enhance the tunneling. Whether the tunneling rate increases or not would then depend on the initial conditions. We give a specific formula to calculate the...

  7. Spontaneous bacterial peritonitis

    Institute of Scientific and Technical Information of China (English)

    Anastasios Koulaouzidis; Shivaram Bhat; Athar A Saeed

    2009-01-01

    Since its initial description in 1964, research has transformed spontaneous bacterial peritonitis (SBP) from a feared disease (with reported mortality of 90%) to a treatable complication of decompensated cirrhosis,albeit with steady prevalence and a high recurrence rate. Bacterial translocation, the key mechanism in the pathogenesis of SBP, is only possible because of the concurrent failure of defensive mechanisms in cirrhosis.Variants of SBP should be treated. Leucocyte esterase reagent strips have managed to shorten the 'tap-toshot' time, while future studies should look into their combined use with ascitic fluid pH. Third generation cephalosporins are the antibiotic of choice because they have a number of advantages. Renal dysfunction has been shown to be an independent predictor of mortality in patients with SBP. Albumin is felt to reduce the risk of renal impairment by improving effective intravascular volume, and by helping to bind proinflammatory molecules. Following a single episode of SBP, patients should have long-term antibiotic prophylaxis and be considered for liver transplantation.

  8. Antimicrobials for bacterial bioterrorism agents.

    Science.gov (United States)

    Sarkar-Tyson, Mitali; Atkins, Helen S

    2011-06-01

    The limitations of current antimicrobials for highly virulent pathogens considered as potential bioterrorism agents drives the requirement for new antimicrobials that are suitable for use in populations in the event of a deliberate release. Strategies targeting bacterial virulence offer the potential for new countermeasures to combat bacterial bioterrorism agents, including those active against a broad spectrum of pathogens. Although early in the development of antivirulence approaches, inhibitors of bacterial type III secretion systems and cell division mechanisms show promise for the future.

  9. Particles' Tunneling in Spherically Symmetric Spacetimes with Dark Matter

    Science.gov (United States)

    Li, Guo-Ping; Zhou, Yun-Gang; Zu, Xiao-Tao

    2013-11-01

    Applying the Hamilton-Jacobi method, we investigate particles’ tunneling behavior in a spherically symmetric spacetime with dark matter. The tunneling rate and Hawking temperature at the event horizon are obtained. The result shows that the dark matter parameter β has an important influence on the Hawking temperature and the tunneling rate.

  10. Structural Design of Linings for Bored Tunnels in Soft Ground

    NARCIS (Netherlands)

    Bakker, K.J.

    2003-01-01

    The increase of bored tunnels in the Netherlands has raised the question how to design the tunnel structure in an efficient way. As a large part of the cost of a bore tunnel is related to the cost of the lining, it is important to design the lining in a cost-effective way. In the Netherlands it is c

  11. Tunnel operator training with a conversational agent-assistant

    NARCIS (Netherlands)

    Buiel, E.; Lubbers, J.; Doesburg, W. van; Muller, T.

    2009-01-01

    A tunnel operator monitors and regulates the flow of traffic inside a tunnel. Tunnel operators need to train in a simulator regularly in order to maintain proficiency in handling incident situations. During quiet working hours, the operator has enough time for training. But generally at that time no

  12. CFD for Better Understanding of Wind Tunnel Tests

    OpenAIRE

    Qin, N.

    2003-01-01

    In this paper, we discuss how CFD may be used for better understanding of wind tunnel tests. Three examples are used to illustrate the potential use of CFD to help the understanding of phenomena observed in the wind tunnel tests, to extend/derive simple aerodynamic criteria based on CFD, and to use CFD to improve the accuracy of wind tunnel measurements.

  13. Theoretical vibrational spectroscopy of intermediates and the reaction mechanism of the guanosine triphosphate hydrolysis by the protein complex Ras-GAP.

    Science.gov (United States)

    Khrenova, Maria G; Grigorenko, Bella L; Nemukhin, Alexander V

    2016-09-01

    The structures and vibrational spectra of the reacting species upon guanosine triphosphate (GTP) hydrolysis to guanosine diphosphate and inorganic phosphate (Pi) trapped inside the protein complex Ras-GAP were analyzed following the results of QM/MM simulations. The frequencies of the phosphate vibrations referring to the reactants and to Pi were compared to those observed in the experimental FTIR studies. A good correlation between the theoretical and experimental vibrational data provides a strong support to the reaction mechanism of GTP hydrolysis by the Ras-GAP enzyme system revealed by the recent QM/MM modeling. Evolution of the vibrational bands associated with the inorganic phosphate Pi during the elementary stages of GTP hydrolysis is predicted. PMID:27214270

  14. Theoretical vibrational spectroscopy of intermediates and the reaction mechanism of the guanosine triphosphate hydrolysis by the protein complex Ras-GAP

    Science.gov (United States)

    Khrenova, Maria G.; Grigorenko, Bella L.; Nemukhin, Alexander V.

    2016-09-01

    The structures and vibrational spectra of the reacting species upon guanosine triphosphate (GTP) hydrolysis to guanosine diphosphate and inorganic phosphate (Pi) trapped inside the protein complex Ras-GAP were analyzed following the results of QM/MM simulations. The frequencies of the phosphate vibrations referring to the reactants and to Pi were compared to those observed in the experimental FTIR studies. A good correlation between the theoretical and experimental vibrational data provides a strong support to the reaction mechanism of GTP hydrolysis by the Ras-GAP enzyme system revealed by the recent QM/MM modeling. Evolution of the vibrational bands associated with the inorganic phosphate Pi during the elementary stages of GTP hydrolysis is predicted.

  15. Macroscopic and Fluorescent Discrimination of Adenosine Triphosphate via Selective Metallo-hydrogel Formation: A Visual, Practical, and Reliable Rehearsal toward Cellular Imaging.

    Science.gov (United States)

    Fang, Weiwei; Liu, Cong; Yu, Fabiao; Liu, Yaoqi; Li, Zhenhua; Chen, Lingxin; Bao, Xiaoling; Tu, Tao

    2016-08-17

    With use of simple terpyridine zinc nitrate complexes, intriguing visual recognition of adenosine triphosphate (ATP) via selective coordination assembly leading to two-component metallo-hydrogel formation has been realized. With intensive fluorescent study and density functional theory calculations, it may be inferred, besides the selective metal-ligand interaction between Zn center and phosphate groups, the intramolecular π-stacking between the planar nucleobases of ATP and the metal-hybrid aromatic ring of pincer complex strongly affected the geometry of the coordinated adducts and possible molecular self-assembly process, which constitute a completely new sensing strategy in comparison with the conventional approaches. Furthermore, in light of extreme sensitivity of pincer zinc complexes toward ATP at micromolar scale (1.85 μM) and remarkable fluorescent enhancement (ca. 44-fold) upon ATP addition, the feasibility of the low cytotoxicity pincer zinc complexes in monitoring ATP in HeLa cells has been fulfilled with confocal fluorescence microscopy. PMID:27420773

  16. Variants of the inosine triphosphate pyrophosphatase gene are associated with reduced relapse risk following treatment for HCV genotype 2/3

    DEFF Research Database (Denmark)

    Rembeck, Karolina; Waldenström, Jesper; Hellstrand, Kristoffer;

    2014-01-01

    The present study evaluated the impact of variations in the inosine triphosphate pyrophosphatase (ITPase) gene (ITPA) on treatment outcome in patients with hepatitis C virus (HCV) genotype 2/3 infection receiving peginterferon-α2a and lower, conventional 800 mg daily dose of ribavirin. Previous...... naïve HCV genotype 2/3 infected patients, enrolled in a phase III trial (NORDynamIC), were genotyped for ITPA (rs1127354 and rs7270101). Homo- or heterozygosity at Ars1127354 or Crs7270101, entailing reduced ITPase activity, was observed in 37% of patients and was associated with increased likelihood...... duration arms, HCV genotype, fibrosis stage and IL28B genotype, and was not secondary to improved adherence to therapy or less pronounced anemia. Gene variants predicting reduced predicted ITPase activity also were associated with decreased risk of anemia (P

  17. Dielectric spectra broadening as a signature for dipole-matrix interaction. III. Water in adenosine monophosphate/adenosine-5'-triphosphate solutions.

    Science.gov (United States)

    Puzenko, Alexander; Levy, Evgeniya; Shendrik, Andrey; Talary, Mark S; Caduff, Andreas; Feldman, Yuri

    2012-11-21

    In this, the third part of our series on the dielectric spectrum symmetrical broadening of water, we consider the nucleotide aqueous solutions. Where in Parts I [E. Levy et al., J. Chem. Phys. 136, 114502 (2012)] and II [E. Levy et al., J. Chem. Phys. 136, 114503 (2012)], the dipole-dipole or ion-dipole interaction had a dominant feature, now the interplay between these two types of dipole-matrix interactions will be considered. We present the results of high frequency dielectric measurements of different concentrations of adenosine monophosphate/adenosine-5'-triphosphate aqueous solutions. We observed the Cole-Cole broadening of the main relaxation peak of the solvent in the solutions. Moreover, depending on the nucleotide concentration, we observed both types of dipole-matrix interaction. The 3D trajectory approach (described in detail in Part I) is applied in order to highlight the differences between the two types of interaction.

  18. Dielectric spectra broadening as a signature for dipole-matrix interaction. III. Water in adenosine monophosphate/adenosine-5'-triphosphate solutions.

    Science.gov (United States)

    Puzenko, Alexander; Levy, Evgeniya; Shendrik, Andrey; Talary, Mark S; Caduff, Andreas; Feldman, Yuri

    2012-11-21

    In this, the third part of our series on the dielectric spectrum symmetrical broadening of water, we consider the nucleotide aqueous solutions. Where in Parts I [E. Levy et al., J. Chem. Phys. 136, 114502 (2012)] and II [E. Levy et al., J. Chem. Phys. 136, 114503 (2012)], the dipole-dipole or ion-dipole interaction had a dominant feature, now the interplay between these two types of dipole-matrix interactions will be considered. We present the results of high frequency dielectric measurements of different concentrations of adenosine monophosphate/adenosine-5'-triphosphate aqueous solutions. We observed the Cole-Cole broadening of the main relaxation peak of the solvent in the solutions. Moreover, depending on the nucleotide concentration, we observed both types of dipole-matrix interaction. The 3D trajectory approach (described in detail in Part I) is applied in order to highlight the differences between the two types of interaction. PMID:23181321

  19. Alendronate reduced peri-tunnel bone loss and enhanced tendon graft to bone tunnel healing in anterior cruciate ligament reconstruction

    Directory of Open Access Journals (Sweden)

    PPY Lui

    2013-01-01

    Full Text Available Peri-tunnel bone loss after anterior cruciate ligament (ACL reconstruction is commonly observed, both clinically and experimentally. We aimed to study the effect and mechanisms of different doses of alendronate in the reduction of peri-tunnel bone loss and promotion of graft-bone tunnel healing in ACL reconstruction. Eighty-four ACL-reconstructed rats were divided into 4 groups. Alendronate at different dosages, or saline, were injected subcutaneously weekly, for 2 or 6 weeks post-reconstruction, for vivaCT (computed tomography imaging, biomechanical tests, histology and immunohistochemistry. Alendronate significantly increased bone mass and density of tissue inside bone tunnels except at the epiphyseal region of tibial tunnel. The femoral tunnel diameter decreased significantly in the mid-dose and high-dose alendronate groups compared to that in the saline group at week 6. Alendronate significantly increased the peri-tunnel bone mass and density along all tunnel regions at week 6. Better graft-bone tunnel integration and intra-tunnel graft integrity were observed in the alendronate groups. The ultimate load was significantly higher in the mid-dose and high-dose alendronate groups at week 2, but not at week 6. There was a reduction in matrix metalloprotein (MMP1, MMP13 and CD68-positive cells at the peri-tunnel region and graft-bone interface in the alendronate-treated group compared to the saline group. Alendronate reduced peri-tunnel bone resorption, increased mineralised tissue inside bone tunnel as well as histologically and biomechanically promoted graft-bone tunnel healing, probably by reducing the expression of MMP1, MMP13 and CD68-positive cells. Alendronate might be used for reducing peri-tunnel bone loss and promoting graft-bone tunnel healing at early stage post-ACL reconstruction.

  20. An analysis of combustion studies in shock expansion tunnels and reflected shock tunnels

    Science.gov (United States)

    Jachimowski, Casimir J.

    1992-01-01

    The effect of initial nonequilibrium dissociated air constituents on the combustion of hydrogen in high-speed flows for a simulated Mach 17 flight condition was investigated by analyzing the results of comparative combustion experiments performed in a reflected shock tunnel test gas and in a shock expansion tunnel test gas. The results were analyzed and interpreted with a one-dimensional quasi-three-stream combustor code that includes finite rate combustion chemistry. The results of this study indicate that the combustion process is kinetically controlled in the experiments in both tunnels and the presence of the nonequilibrium partially dissociated oxygen in the reflected shock tunnel enhances the combustion. Methods of compensating for the effect of dissociated oxygen are discussed.

  1. Resonant tunnel magnetoresistance in double-barrier planar magnetic tunnel junctions

    KAUST Repository

    Useinov, A. N.

    2011-08-24

    We present a theoretical approach to calculate the spin-dependent current and tunnel magnetoresistance (TMR) in a double-barrier magnetic tunnel junction (DMTJ), in which the magnetization of the middle ferromagnetic metal layer can be aligned parallel or antiparallel in relation to the fixed magnetizations of the left and right ferromagnetic electrodes. The electron transport through the DMTJ is considered as a three-dimensional problem, taking into account all transmitting electron trajectories as well as the spin-dependent momentum conservation law. The dependence of the transmission coefficient and spin-polarized currents on the applied voltage is derived as an exact solution to the quantum-mechanical problem for the spin-polarized transport. In the range of the developed physical model, the resonant tunneling, nonresonant tunneling, and enhanced spin filtering can be explained; the simulation results are in good agreement with experimental data.

  2. Asymmetric voltage behavior of the tunnel magnetoresistance in double barrier magnetic tunnel junctions

    KAUST Repository

    Useinov, Arthur

    2012-06-01

    In this paper, we study the value of the tunnel magnetoresistance (TMR) as a function of the applied voltage in double barrier magnetic tunnel junctions (DMTJs) with the left and right ferromagnetic (FM) layers being pinned and numerically estimate the possible difference of the TMR curves for negative and positive voltages in the homojunctions (equal barriers and electrodes). DMTJs are modeled as two single barrier junctions connected in series with consecutive tunneling (CST). We investigated the asymmetric voltage behavior of the TMR for the CST in the range of a general theoretical model. Significant asymmetries of the experimental curves, which arise due to different annealing regimes, are mostly explained by different heights of the tunnel barriers and asymmetries of spin polarizations in magnetic layers. © (2012) Trans Tech Publications.

  3. Anomalous Tunnel Magnetoresistance and Spin Transfer Torque in Magnetic Tunnel Junctions with Embedded Nanoparticles

    Science.gov (United States)

    Useinov, Arthur; Ye, Lin-Xiu; Useinov, Niazbeck; Wu, Te-Ho; Lai, Chih-Huang

    2015-12-01

    The tunnel magnetoresistance (TMR) in the magnetic tunnel junction (MTJ) with embedded nanoparticles (NPs) was calculated in range of the quantum-ballistic model. The simulation was performed for electron tunneling through the insulating layer with embedded magnetic and non-magnetic NPs within the approach of the double barrier subsystem connected in parallel to the single barrier one. This model can be applied for both MTJs with in-plane magnetization and perpendicular one. We also calculated the in-plane component of the spin transfer torque (STT) versus the applied voltage in MTJs with magnetic NPs and determined that its value can be much larger than in single barrier system (SBS) for the same tunneling thickness. The reported simulation reproduces experimental data of the TMR suppression and peak-like TMR anomalies at low voltages available in leterature.

  4. Interaction of Beta-Hydroxy-Beta-Methylbutyrate Free Acid and Adenosine Triphosphate on Muscle Mass, Strength, and Power in Resistance Trained Individuals.

    Science.gov (United States)

    Lowery, Ryan P; Joy, Jordan M; Rathmacher, John A; Baier, Shawn M; Fuller, John C; Shelley, Mack C; Jäger, Ralf; Purpura, Martin; Wilson, Stephanie M C; Wilson, Jacob M

    2016-07-01

    Lowery, RP, Joy, JM, Rathmacher, JA, Baier, SM, Fuller, JC Jr, Shelley, MC II, Jäger, R, Purpura, M, Wilson, SMC, and Wilson, JM. Interaction of beta-hydroxy-beta-methylbutyrate free acid and adenosine triphosphate on muscle mass, strength, and power in resistance trained individuals. J Strength Cond Res 30(7): 1843-1854, 2016-Adenosine-5'-triphosphate (ATP) supplementation helps maintain performance under high fatiguing contractions and with greater fatigue recovery demands also increase. Current evidence suggests that the free acid form of β-hydroxy-β-methylbutyrate (HMB-FA) acts by speeding regenerative capacity of skeletal muscle after high-intensity or prolonged exercise. Therefore, we investigated the effects of 12 weeks of HMB-FA (3 g) and ATP (400 mg) administration on lean body mass (LBM), strength, and power in trained individuals. A 3-phase double-blind, placebo-, and diet-controlled study was conducted. Phases consisted of an 8-week periodized resistance training program (phase 1), followed by a 2-week overreaching cycle (phase 2), and a 2-week taper (phase 3). Lean body mass was increased by a combination of HMB-FA/ATP by 12.7% (p power were increased in the HMB-FA/ATP-supplemented group compared with the placebo-supplemented group, and the 12-week increases were 21.5 and 23.7%, respectively. During the overreaching cycle, strength and power declined in the placebo group (4.3-5.7%), whereas supplementation with HMB-FA/ATP resulted in continued strength gains (1.3%). In conclusion, HMB-FA and ATP in combination with resistance exercise training enhanced LBM, power, and strength. In addition, HMB-FA plus ATP blunted the typical response to overreaching, resulting in a further increase in strength during that period. It seems that the combination of HMB-FA/ATP could benefit those who continuously train at high levels such as elite athletes or military personnel.

  5. 3D numerical design of tunnel hood

    CERN Document Server

    Uystepruyst, David; Monnoyer, François

    2015-01-01

    This paper relates to the parametric study of tunnel hoods in order to reduce the shape, i.e the temporal gradient, of the pressure wave generated by the entry of a High speed train in tunnel. This is achieved by using an in-house three-dimensional numerical solver which solves the Eulerian equations on a Cartesian and unstructured mesh. The efficiency of the numerical methodology is demonstrated through comparisons with both experimental data and empirical formula. For the tunnel hood design, three parameters, that can influence the wave shape, are considered: the shape, the section and the length of the hood. The numerical results show, (i) that a constant section hood is the most efficient shape when compared to progressive (elliptic or conical) section hoods, (ii) an optimal ratio between hood's section and tunnel section where the temporal gradient of the pressure wave can be reduced by half, (iii) a significant efficiency of the hood's length in the range of 2 to 8 times the length of the train nose. Fi...

  6. Tunnel Diode Discriminator with Fixed Dead Time

    DEFF Research Database (Denmark)

    Diamond, J. M.

    1965-01-01

    A solid state discriminator for the range 0.4 to 10 V is described. Tunnel diodes are used for the discriminator element and in a special fixed dead time circuit. An analysis of temperature stability is presented. The regulated power supplies are described, including a special negative resistance...

  7. Vector particles tunneling from BTZ black holes

    CERN Document Server

    Chen, Ge-Rui; Huang, Yong-Chang

    2014-01-01

    In this paper we investigate vector particles' Hawking radiation from a BTZ black hole. By applying the WKB approximation and the Hamilton-Jacobi Ansatz to the Proca equation, we obtain the tunneling spectrum of vector particles. The expected Hawking temperature is recovered.

  8. Vector particles tunneling from BTZ black holes

    Science.gov (United States)

    Chen, Ge-Rui; Zhou, Shiwei; Huang, Yong-Chang

    2015-11-01

    In this paper we investigate vector particles' Hawking radiation from a Banados-Teitelboim-Zanelli (BTZ) black hole. By applying the Wentzel-Kramers-Brillouin (WKB) approximation and the Hamilton-Jacobi ansatz to the Proca equation, we obtain the tunneling spectrum of vector particles. The expected Hawking temperature is recovered.

  9. Quasiparticle dynamics in superconducting tunnel junctions

    NARCIS (Netherlands)

    Kozorezov, A.G.; Brammertz, G.; Hijmering, R.A.; Wigmore, J.K.; Peacock, A.; Martin, B.; Verhoeve, P.; Golubov, A.A.; Rogalla, H.

    2006-01-01

    Superconducting Tunnel Junctions (STJs) used as single photon detectors possess extreme sensitivity and excellent resolving power. However, like many other cryogenic detectors they operate under extremely non-equilibrium conditions. In order to understand the physics of the non-equilibrium, non-stat

  10. A Student-Built Scanning Tunneling Microscope

    Science.gov (United States)

    Ekkens, Tom

    2015-01-01

    Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself.…

  11. Electron tunnelling into amorphous germanium and silicon.

    Science.gov (United States)

    Smith, C. W.; Clark, A. H.

    1972-01-01

    Measurements of tunnel conductance versus bias, capacitance versus bias, and internal photoemission were made in the systems aluminum-oxide-amorphous germanium and aluminium-oxide-amorphous silicon. A function was extracted which expresses the deviation of these systems from the aluminium-oxide-aluminium system.

  12. 78 FR 46117 - National Tunnel Inspection Standards

    Science.gov (United States)

    2013-07-30

    ... in the Federal Register on July 22, 2010, at 75 FR 42643. That proposal did not address the....com/blogs/headlines/2012/12/japan-orders-immediate-inspections-after-deadly-tunnel-collapse/ . The...), and the National Cooperative Highway Research Program (NCHRP) sponsored a study of equipment,...

  13. Analytic Solutions of Elastic Tunneling Problems

    NARCIS (Netherlands)

    Strack, O.E.

    2002-01-01

    The complex variable method for solving two dimensional linearly elastic problems is used to obtain several fundamental analytical solutions of tunneling problems. The method is used to derive the general mathematical representation of problems involving resultant forces on holes in a half-plane

  14. High-Performance Single Nanowire Tunnel Diodes

    DEFF Research Database (Denmark)

    Wallentin, Jesper; Persson, Johan Mikael; Wagner, Jakob Birkedal;

    2010-01-01

    We demonstrate single nanowire tunnel diodes with room temperature peak current densities of up to 329 A/cm(2). Despite the large surface to volume ratio of the type-II InP-GaAs axial heterostructure nanowires, we measure peak to valley current ratios (PVCR) of up to 8.2 at room temperature and 27...

  15. Towards high-speed scanning tunneling microscopy

    NARCIS (Netherlands)

    Tabak, Femke Chantal

    2013-01-01

    In this thesis, two routes towards high-speed scanning tunneling microscopy (STM) are described. The first possibility for high-speed scanning that is discussed is the use of MEMS (Micro-Electro Mechanical Systems) devices as high-speed add-ons in STM microscopes. The functionality of these devices

  16. Resonant tunneling in a pulsed phonon field

    DEFF Research Database (Denmark)

    Kral, P.; Jauho, Antti-Pekka

    1999-01-01

    We theoretically investigate resonant tunneling through a single level assisted by short LO phonon pulses. The analysis is based on the recently developed nonequilibrium linked-cluster expansion [P. Kral, Phys. Rev. B 56, 7293 (1997)], extended in this work to transient situations, The nonequilib...

  17. Single electron tunneling based arithmetic computation

    NARCIS (Netherlands)

    Lageweg, C.R.

    2004-01-01

    In this dissertation we investigate the implementation of computer arithmetic operations with Single Electron Tunneling (SET) technology based circuits. In our research we focus on the effective utilization of the SET technologys specific characteristic, i.e., the ability to control the transport of

  18. An Optimization Model of Tunnel Support Parameters

    Directory of Open Access Journals (Sweden)

    Su Lijuan

    2015-05-01

    Full Text Available An optimization model was developed to obtain the ideal values of the primary support parameters of tunnels, which are wide-ranging in high-speed railway design codes when the surrounding rocks are at the III, IV, and V levels. First, several sets of experiments were designed and simulated using the FLAC3D software under an orthogonal experimental design. Six factors, namely, level of surrounding rock, buried depth of tunnel, lateral pressure coefficient, anchor spacing, anchor length, and shotcrete thickness, were considered. Second, a regression equation was generated by conducting a multiple linear regression analysis following the analysis of the simulation results. Finally, the optimization model of support parameters was obtained by solving the regression equation using the least squares method. In practical projects, the optimized values of support parameters could be obtained by integrating known parameters into the proposed model. In this work, the proposed model was verified on the basis of the Liuyang River Tunnel Project. Results show that the optimization model significantly reduces related costs. The proposed model can also be used as a reliable reference for other high-speed railway tunnels.

  19. Tunneling times and the Hartman effect revisited

    International Nuclear Information System (INIS)

    In a recent review paper we proposed, within conventional quantum mechanics, new definitions for the sub-barrier tunnelling and reflection times. Aims of the present paper are: presenting and analysing the results of various numerical calculations (based on our equations) on the penetration and return times , , during tunneling inside a rectangular potential barrier, for various penetration depths xf; putting forth and discussing suitable definitions, besides of the mean values, also of the variances (or dispersions) D τT D τR for the time durations of transmission and reflection process; mentioning that our definition τT > for the average transmission time results to constitute an improvement of the ordinary dwell-time τDw formula; commenting upon some recent criticism by C.R. Leavens, on the basis of our new numerical results. We stress that our numerical evaluations confirm that our approach implied and implies, the existence of the Hartman effect: an effect that in these days (due to the theoretical connections between tunneling and evanescent wave propagation) is receiving - at Cologne, Berkeley, Florence and Vienna- indirect, but quite interesting, experimental verifications. At last, we briefly analyze some other definitions of tunnelling times. (author). 24 refs., 5 figs

  20. Electron accelerator for tunneling through hard rock

    International Nuclear Information System (INIS)

    Earlier work demonstrated that intense sub-microsecond bursts of energetic electrons cause significant pulverization and spalling of a variety of rock types. The spall debris generally consists of sand, dust, and small flakes. If carried out at rapid repetition rate, this can lead to a promising technique for increasing the speed and reducing the cost of underground excavation of tunnels, mines, and storage spaces. The conceptual design features of a Pulsed Electron Tunnel Excavator capable of tunneling approximately ten times faster than conventional drill/blast methods are presented with primary emphasis on the electron accelerator and only a brief description of the tunneling aspects. Of several candidate types of accelerators, a linear induction accelerator producing electron pulses (5 MV, 5 kA, 1.0 μs = 25 kJ) at a 360 Hz rate was selected for the conceptual example. This provides the required average electron beam power output of 9 MW. The feasibility of such an accelerator is discussed

  1. Carpal Tunnel Syndrome in ARL Libraries.

    Science.gov (United States)

    Thornton, Joyce K.

    1997-01-01

    A survey of 72 member libraries in the Association of Research Libraries revealed the incidence of carpal tunnel syndrome (CTS) and the measures taken to cope with it. Recommends implementing proactive ergonomics programs; soliciting staff input for solutions; providing report guidelines; using external help; stressing preventive measures and…

  2. Employees' Knowledge of Carpal Tunnel Syndrome.

    Science.gov (United States)

    Gandy-Goldston, Terrie M.

    A study examined employees' knowledge of the causes of carpal tunnel syndrome (CTS), its prevention, and their legal rights after being diagnosed with CTS. A 24-item questionnaire was administered to a random sample of 30 Chicago-area employees who had been afflicted with CTS. Of those surveyed, 99% considered their CTS injury related to their…

  3. Wind Tunnel Measurements at Virginia Tech

    DEFF Research Database (Denmark)

    Fischer, Andreas; Bertagnolio, Franck

    2012-01-01

    In this section, the wind tunnel configuration used for aerodynamic and aeroacoustic measurement is described. Then, the validation of the method for evaluating far-field noise from surface microphones as described in Section 5 is presented. Finally, the design concept proposed in Section 6...

  4. Chaperone binding at the ribosomal exit tunnel

    DEFF Research Database (Denmark)

    Kristensen, Ole; Gajhede, Michael

    2003-01-01

    The exit tunnel region of the ribosome is well established as a focal point for interaction between the components that guide the fate of nascent polypeptides. One of these, the chaperone trigger factor (TF), associates with the 50S ribosomal subunit through its N-terminal domain. Targeting of TF...

  5. Soliton excitations in Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Lomdahl, P. S.; Sørensen, O. H.; Christiansen, Peter Leth

    1982-01-01

    A detailed numerical study of a sine-Gordon model of the Josephson tunnel junction is compared with experimental measurements on junctions with different L / λJ ratios. The soliton picture is found to apply well on both relatively long (L / λJ=6) and intermediate (L / λJ=2) junctions. We find good...

  6. delta-biased Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Monaco, R.; Mygind, Jesper; Koshelet, V.;

    2010-01-01

    Abstract: The behavior of a long Josephson tunnel junction drastically depends on the distribution of the dc bias current. We investigate the case in which the bias current is fed in the central point of a one-dimensional junction. Such junction configuration has been recently used to detect...

  7. Prismatic Blade Measuring on a Wind Tunnel

    Directory of Open Access Journals (Sweden)

    Stech J.

    2013-04-01

    Full Text Available The results from measurement on the straight blade cascade are presented in the paper. The cascade is placed at the outlet of wind tunnel in ŠKODA POWER experimental base. The results in the form of velocity and loss fields behind blade cascade as well as the distribution of the loss coefficient in selected cross-section are evaluated.

  8. WIND TUNNEL SIMULATIONS OF POLLUTION FROM ROADWAYS

    Science.gov (United States)

    A wind tunnel study has been conducted to examine the influence of roadway configurations and nearby structures on the flow and dispersion of traffic related pollutant concentrations within a few hundred meters of the roadway. The study focused four selected configurations (all w...

  9. Wind Tunnel Measurements at Virginia Tech

    OpenAIRE

    Fischer, Andreas; Bertagnolio, Franck

    2012-01-01

    In this section, the wind tunnel configuration used for aerodynamic and aeroacoustic measurement is described. Then, the validation of the method for evaluating far-field noise from surface microphones as described in Section 5 is presented. Finally, the design concept proposed in Section 6 is verified.

  10. Dihydroazulene photoswitch operating in sequential tunneling regime

    DEFF Research Database (Denmark)

    Broman, Søren Lindbæk; Lara-Avila, Samuel; Thisted, Christine Lindbjerg;

    2012-01-01

    to electrodes so that the electron transport goes by sequential tunneling. To assure weak coupling, the DHA switching kernel is modified by incorporating p-MeSC6H4 end-groups. Molecules are prepared by Suzuki cross-couplings on suitable halogenated derivatives of DHA. The synthesis presents an expansion of our...

  11. Bilateral carpal tunnel syndrome in Graves' disease.

    Science.gov (United States)

    Manganelli, P; Pavesi, G; Salaffi, F

    1987-01-01

    Carpal tunnel syndrome (CTS) may be associated with endocrinopathies, such as hypothyroidism and acromegaly. A direct relationship between CTS and hyperthyroidism has recently been suggested. We now report a case in which bilateral CTS developed after treatment of Graves' disease, thus, questioning the possibility of a relationship between these two disease processes.

  12. SCANNING TUNNELING MICROSCOPY STUDIES ON OPTICAL DISC

    Institute of Scientific and Technical Information of China (English)

    徐磊; 顾冬红; 等

    1994-01-01

    Scanning tunneling microscope(STM) is used to investigate the optical dise.The areas with and without data stampers are all observedcarefully.Three-dimensional images of the disc surface clearly demonstrate the period.depth of the grooves and the shape of data stampers.Some phenomena of STM imaging are also discussed.

  13. The Time and Cost Prediction of Tunnel Boring Machine in Tunnelling

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Making use of microsoft visual studio. net platform, the assistant decision-making system of tunnel boring machine in tunnelling has been built to predict the time and cost. Computation methods of the performance parameters have been discussed. New time and cost prediction models have been depicted. The multivariate linear regression has been used to make the parameters more precise, which are the key factor to affect the prediction near to the reality.

  14. Tunnelling in Soft Soil: Tunnel Boring Machine Operation and Soil Response

    OpenAIRE

    Festa, D.; Broere, W.; Bosch, J.W.

    2013-01-01

    Constructing tunnels in soft soil with the use of Tunnel Boring Machines may induce settlements including soil movements ahead of the face, soil relaxation into the tail void, possible heave due to grouting, long lasting consolidation processes, and potentially several other mechanisms. A considerable amount of the total soil displacements seems correlated with the passage of the TBM-shield. Even so, the TBM-induced soil displacements have so far only been coarsely correlated to the total set...

  15. Time Evolution of Tunneling in Thermal Medium -- Environment-driven Excited Tunneling --

    OpenAIRE

    Matsumoto, Sh.; Yoshimura, M.

    2003-01-01

    Time evolution of tunneling phenomena proceeding in thermal medium is studied using a standard model of environment interaction. A semiclassical probability formula for the particle motion in a metastable state of one dimensional system put in thermal medium is combined with the formula of quantum penetration factor through a potential barrier, to derive the tunneling rate in medium. Effect of environment, its influence on time evolution in particular, is clarified in a real-time formalism. A...

  16. Geological Hazards analysis in Urban Tunneling by EPB Machine (Case study: Tehran subway line 7 tunnel)

    OpenAIRE

    Hassan Bakhshandeh Amnieh; Mohammad Saber Zamzam; Mozdianfard, M. R.

    2016-01-01

    Technological progress in tunneling has led to modern and efficient tunneling methods in vast underground spaces even under inappropriate geological conditions. Identification and access to appropriate and sufficient geological hazard data are key elements to successful construction of underground structures. Choice of the method, excavation machine, and prediction of suitable solutions to overcome undesirable conditions depend on geological studies and hazard analysis. Identifying and invest...

  17. Inelastic electron tunnelling and noise spectroscopies in organic magnetic tunnel junctions with PTCDA barrier

    Science.gov (United States)

    Aliev, Farkhad; Martinez, Isidoro; Hong, Jhen-Yong; Cascales, Juan Pedro; Andres, Pablo; Lin, Minn-Tsong

    2015-03-01

    The influence of internal barrier dynamics on spin, charge transport and their fluctuations in organic spintronics remains poorly understood. Here we present inelastic electron tunnelling spectroscopy (IETS) and low frequency noise (LFN) studies in magnetic tunnel junctions with thin (1.2-5nm) organic PTCDA barriers in the tunnelling regime at temperatures down to 0.3K. Shot noise is superpoissonian with a Fano factor exceeding in 1.5-2 times the maximum values reported for magnetic tunnel junctions with inorganic barriers, indicating spin dependent bunching in tunneling. IETS results show energy relaxation of tunneling electrons through the excitation of collective (librons) and internal (phonons) vibrational modes of the molecules. The bias dependence of the normalised 1/f noise studied up to 350mV reveals that the excitation of some phonon modes has a strong impact on LFN with over a 10-fold reproducible increase near some specific biases. The dependence of the IETS and LFN anomalies with the relative magnetic alignment of the electrodes will also be discussed.

  18. [Small intestine bacterial overgrowth].

    Science.gov (United States)

    Leung Ki, E L; Roduit, J; Delarive, J; Guyot, J; Michetti, P; Dorta, G

    2010-01-27

    Small intestine bacterial overgrowth (SIBO) is a condition characterised by nutrient malabsorption and excessive bacteria in the small intestine. It typically presents with diarrhea, flatulence and a syndrome of malabsorption (steatorrhea, macrocytic anemia). However, it may be asymptomatic in the eldery. A high index of suspicion is necessary in order to differentiate SIBO from other similar presenting disorders such as coeliac disease, lactose intolerance or the irritable bowel syndrome. A search for predisposing factor is thus necessary. These factors may be anatomical (stenosis, blind loop), or functional (intestinal hypomotility, achlorydria). The hydrogen breath test is the most frequently used diagnostic test although it lacks standardisation. The treatment of SIBO consists of eliminating predisposing factors and broad-spectrum antibiotic therapy. PMID:20214190

  19. Studying bacterial multispecies biofilms

    DEFF Research Database (Denmark)

    Røder, Henriette Lyng; Sørensen, Søren Johannes; Burmølle, Mette

    2016-01-01

    The high prevalence and significance of multispecies biofilms have now been demonstrated in various bacterial habitats with medical, industrial, and ecological relevance. It is highly evident that several species of bacteria coexist and interact in biofilms, which highlights the need for evaluating...... the approaches used to study these complex communities. This review focuses on the establishment of multispecies biofilms in vitro, interspecies interactions in microhabitats, and how to select communities for evaluation. Studies have used different experimental approaches; here we evaluate the benefits...... and drawbacks of varying the degree of complexity. This review aims to facilitate multispecies biofilm research in order to expand the current limited knowledge on interspecies interactions. Recent technological advances have enabled total diversity analysis of highly complex and diverse microbial communities...

  20. Bacterial proteases and virulence

    DEFF Research Database (Denmark)

    Frees, Dorte; Brøndsted, Lone; Ingmer, Hanne

    2013-01-01

    Bacterial pathogens rely on proteolysis for variety of purposes during the infection process. In the cytosol, the main proteolytic players are the conserved Clp and Lon proteases that directly contribute to virulence through the timely degradation of virulence regulators and indirectly by providing...... tolerance to adverse conditions such as those experienced in the host. In the membrane, HtrA performs similar functions whereas the extracellular proteases, in close contact with host components, pave the way for spreading infections by degrading host matrix components or interfering with host cell...... signalling to short-circuit host cell processes. Common to both intra- and extracellular proteases is the tight control of their proteolytic activities. In general, substrate recognition by the intracellular proteases is highly selective which is, in part, attributed to the chaperone activity associated...