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Sample records for positive zeta potential

  1. Positive zeta potential of a negatively charged semi-permeable plasma membrane

    Science.gov (United States)

    Sinha, Shayandev; Jing, Haoyuan; Das, Siddhartha

    2017-08-01

    The negative charge of the plasma membrane (PM) severely affects the nature of moieties that may enter or leave the cells and controls a large number of ion-interaction-mediated intracellular and extracellular events. In this letter, we report our discovery of a most fascinating scenario, where one interface (e.g., membrane-cytosol interface) of the negatively charged PM shows a positive surface (or ζ) potential, while the other interface (e.g., membrane-electrolyte interface) still shows a negative ζ potential. Therefore, we encounter a completely unexpected situation where an interface (e.g., membrane-cytosol interface) that has a negative surface charge density demonstrates a positive ζ potential. We establish that the attainment of such a property by the membrane can be ascribed to an interplay of the nature of the membrane semi-permeability and the electrostatics of the electric double layer established on either side of the charged membrane. We anticipate that such a membrane property can lead to such capabilities of the cell (in terms of accepting or releasing certain kinds of moieties as well regulating cellular signaling) that was hitherto inconceivable.

  2. A zeta potential value determines the aggregate's size of penta-substituted [60]fullerene derivatives in aqueous suspension whereas positive charge is required for toxicity against bacterial cells.

    Science.gov (United States)

    Deryabin, Dmitry G; Efremova, Ludmila V; Vasilchenko, Alexey S; Saidakova, Evgeniya V; Sizova, Elena A; Troshin, Pavel A; Zhilenkov, Alexander V; Khakina, Ekaterina A; Khakina, Ekaterina E

    2015-08-08

    The cause-effect relationships between physicochemical properties of amphiphilic [60]fullerene derivatives and their toxicity against bacterial cells have not yet been clarified. In this study, we report how the differences in the chemical structure of organic addends in 10 originally synthesized penta-substituted [60]fullerene derivatives modulate their zeta potential and aggregate's size in salt-free and salt-added aqueous suspensions as well as how these physicochemical characteristics affect the bioenergetics of freshwater Escherichia coli and marine Photobacterium phosphoreum bacteria. Dynamic light scattering, laser Doppler micro-electrophoresis, agarose gel electrophoresis, atomic force microscopy, and bioluminescence inhibition assay were used to characterize the fullerene aggregation behavior in aqueous solution and their interaction with the bacterial cell surface, following zeta potential changes and toxic effects. Dynamic light scattering results indicated the formation of self-assembled [60]fullerene aggregates in aqueous suspensions. The measurement of the zeta potential of the particles revealed that they have different surface charges. The relationship between these physicochemical characteristics was presented as an exponential regression that correctly described the dependence of the aggregate's size of penta-substituted [60]fullerene derivatives in salt-free aqueous suspension from zeta potential value. The prevalence of DLVO-related effects was shown in salt-added aqueous suspension that decreased zeta potential values and affected the aggregation of [60]fullerene derivatives expressed differently for individual compounds. A bioluminescence inhibition assay demonstrated that the toxic effect of [60]fullerene derivatives against E. coli cells was strictly determined by their positive zeta potential charge value being weakened against P. phosphoreum cells in an aquatic system of high salinity. Atomic force microscopy data suggested that the

  3. Wettability Studies Using Zeta Potential Measurements

    Directory of Open Access Journals (Sweden)

    Ghada Bassioni

    2015-01-01

    Full Text Available Wettability studies have been carried out on reservoir rocks using different techniques such as the Amott-Harvey method, the USBM method, and the contact angle method, all with limitations. In this study, the wettability is studied by discussing the surface charge using zeta potential measurements. The study relies on the finding that carbonated reservoir rocks, consisting of CaCO3 mainly, are positively charged and their surface has the potential to adsorb significant quantities of anions. Moreover, heavy fractions such as asphaltenes are reported to remain afloat depending on dispersive forces present in the oil and its various fractions. Experiments are carried out on aqueous limestone suspension with the addition of crude oil. The experiment is repeated with the use of polymeric inhibitors, A and B. The zeta potential is found to alter depending on the sequence of polymeric inhibitor in oil/water addition. The inhibitor is found to adsorb on the limestone surface, with a net negative charge, causing repulsion between crude oil and the inhibitor and, hence, preventing the deposition of heavy fractions and particularly asphaltenes. This study gives a comprehensive insight on the mechanism of polymeric inhibitor interaction with the surface and the effect of wettability on its performance.

  4. Zeta potential in colloid science principles and applications

    CERN Document Server

    Hunter, Robert J; Rowell, R L

    2013-01-01

    Zeta Potential in Colloid Science: Principles and Applications covers the concept of the zeta potential in colloid chemical theory. The book discusses the charge and potential distribution at interfaces; the calculation of the zeta potential; and the experimental techniques used in the measurement of electrokinetic parameters. The text also describes the electroviscous and viscoelectric effects; applications of the zeta potential to areas of colloid science; and the influence of simple inorganic ions or more complex adsorbates on zeta potential. Physical chemists and people involved in the stu

  5. Zeta-potential of fouled thin film composite membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, K.; Hachisuka, H.; Nakamura, T. [Nitto denko Corp., Ibaraki, (Japan); Kimura, S. [Kogakuin University, Tokyo (Japan). Dept. of Environ. Chemical Engineering; Ueyama, K. [Osaka University, Osaka (Japan). Dept. of Chemical Engineering

    1999-10-01

    The surface zeta-potential of a cross-linked polyamide thin film composite reverse osmosis membrane was measured using an electrophoresis method. It was confirmed that this method could be effectively applied to analyze the fouling of such membranes. It is known that the water flux of membranes drastically decreases as a result of fouling by surfactants. Although the surfactants adsorbed on reverse osmosis membranes could not be detected by conventional methods such as SEM, EDX and FT-IR, their presence could be clarified by the profile measurements of the surface zeta-potential. The profiles of the membrane surface zeta-potentials changed to more positive values in the measured pH range as a result of fouling by cationic or amphoteric surfactants. This measuring method of surface zeta-potentials allowed us to analyze a very small amount of fouling of a thin film composite reverse osmosis membrane. This method could be used to analyze the fouled surface of the thin film composite reverse osmosis membrane which is used for production of ultrapure water and shows a remarkable decrease in flux. It also became clear that this method is easy and effective for the reverse osmosis membrane surface analysis of adsorbed materials such as surfactants. (author)

  6. Surface Complexation Modeling of Calcite Zeta Potential Measurement in Mixed Brines for Carbonate Wettability Characterization

    Science.gov (United States)

    Song, J.; Zeng, Y.; Biswal, S. L.; Hirasaki, G. J.

    2017-12-01

    We presents zeta potential measurements and surface complexation modeling (SCM) of synthetic calcite in various conditions. The systematic zeta potential measurement and the proposed SCM provide insight into the role of four potential determining cations (Mg2+, SO42- , Ca2+ and CO32-) and CO2 partial pressure in calcite surface charge formation and facilitate the revealing of calcite wettability alteration induced by brines with designed ionic composition ("smart water"). Brines with varying potential determining ions (PDI) concentration in two different CO2 partial pressure (PCO2) are investigated in experiments. Then, a double layer SCM is developed to model the zeta potential measurements. Moreover, we propose a definition for contribution of charged surface species and quantitatively analyze the variation of charged species contribution when changing brine composition. After showing our model can accurately predict calcite zeta potential in brines containing mixed PDIs, we apply it to predict zeta potential in ultra-low and pressurized CO2 environments for potential applications in carbonate enhanced oil recovery including miscible CO2 flooding and CO2 sequestration in carbonate reservoirs. Model prediction reveals that pure calcite surface will be positively charged in all investigated brines in pressurized CO2 environment (>1atm). Moreover, the sensitivity of calcite zeta potential to CO2 partial pressure in the various brine is found to be in the sequence of Na2CO3 > Na2SO4 > NaCl > MgCl2 > CaCl2 (Ionic strength=0.1M).

  7. Zeta-potential and flotability of the scheelite mineral in different type of waters, Part 1: Zeta-potential

    Directory of Open Access Journals (Sweden)

    Milanović Dragan B.

    2009-01-01

    Full Text Available The aim of this work is the investigation of zeta-potential of the mineral scheelite from mine 'Rudnik', located in central Serbia. Electrophoresis measurements using zeta-meter were carried out on four different types of water, namely: tap water, distilled water, rain water and spring water. All types of water had different hardness and conductivity as well as natural pH values. It was found that the zeta-potential of mineral scheelite depends on the hardness and electro-conductivity of the chosen type of water as well as on Ca2+ content. The results obtained reveal the importance of proper choice of water as well as the type of reagents for flotation processes.

  8. Zeta-function approach to Casimir energy with singular potentials

    International Nuclear Information System (INIS)

    Khusnutdinov, Nail R.

    2006-01-01

    In the framework of zeta-function approach the Casimir energy for three simple model system: single delta potential, step function potential and three delta potentials are analyzed. It is shown that the energy contains contributions which are peculiar to the potentials. It is suggested to renormalize the energy using the condition that the energy of infinitely separated potentials is zero which corresponds to subtraction all terms of asymptotic expansion of zeta-function. The energy obtained in this way obeys all physically reasonable conditions. It is finite in the Dirichlet limit, and it may be attractive or repulsive depending on the strength of potential. The effective action is calculated, and it is shown that the surface contribution appears. The renormalization of the effective action is discussed

  9. Measuring the zeta potential. The relationships with sandstone fineness

    Directory of Open Access Journals (Sweden)

    de Luxán, M. P.

    1989-09-01

    Full Text Available The application of the zeta potential technique in the area of construction materials and Portland cement is quite recent. The initial research work involved the study of cement suspensions or suspensions of one of the components of cement, such as alite, tricalcium alumínate, in the presence of additives and, more specifically, superplasticizers. The studies of this sort were extended with the mixing of active additions into cement (fly ashes, etc.. The present study discusses the application of siliceous materials (sandstone as a basis of the research into the behaviour of sandstone mortars containing repair products.

    La aplicación de la técnica del potencial zeta en el campo de los materiales de construcción y del cemento portland es muy reciente. Las primeras investigaciones se refieren al estudio de suspensiones de cemento o de alguno de sus compuestos que lo forman como alita, aluminato tricálcico, en presencia de aditivos y, más concretamente, de superfluidificantes. Con la incorporación de adiciones activas al cemento (cenizas volantes,... se amplían los estudios de este tipo de cementos. En este trabajo se considera la aplicación a los materiales silíceos (arenisca como base para la investigación del comportamiento de los morteros de arenisca conteniendo productos de reparación.

  10. Chitosan-magnesium aluminum silicate composite dispersions: characterization of rheology, flocculate size and zeta potential.

    Science.gov (United States)

    Khunawattanakul, Wanwisa; Puttipipatkhachorn, Satit; Rades, Thomas; Pongjanyakul, Thaned

    2008-03-03

    Composite dispersions of chitosan (CS), a positively charged polymer, and magnesium aluminum silicate (MAS), a negatively charged clay, were prepared and rheology, flocculate size and zeta potential of the CS-MAS dispersions were investigated. High and low molecular weights of CS (HCS and LCS, respectively) were used in this study. Moreover, the effects of heat treatment at 60 degrees C on the characteristics of the CS-MAS dispersions and the zeta potential of MAS upon addition of CS at different pHs were examined. Incorporation of MAS into CS dispersions caused an increase in viscosity and a shift of CS flow type from Newtonian to pseudoplastic flow with thixotropic properties. Heat treatment brought about a significant decrease in viscosity and hysteresis area of the composite dispersions. Microscopic studies showed that flocculation of MAS occurred after mixing with CS. The size and polydispersity index of the HCS-MAS flocculate were greater than those of the LCS-MAS flocculate. However, a narrower size distribution and the smaller size of the HCS-MAS flocculate were found after heating at 60 degrees C. Zeta potentials of the CS-MAS flocculates were positive and slightly increased with increasing MAS content. In the zeta potential studies, the negative charge of the MAS could be neutralized by the addition of CS. Increasing the pH and molecular weight of CS resulted in higher CS concentrations required to neutralize the charge of MAS. These findings suggest that the electrostatic interaction between CS and MAS caused a change in flow behavior and flocculation of the composite dispersions, depending on the molecular weight of CS. Heat treatment affected the rheological properties and the flocculate size of the composite dispersions. Moreover, pH of medium and molecular weight of CS influence the zeta potential of MAS.

  11. Entrapment of ovalbumin into liposomes--factors affecting entrapment efficiency, liposome size, and zeta potential.

    Science.gov (United States)

    Brgles, Marija; Jurasin, Darija; Sikirić, Maja Dutour; Frkanec, Ruza; Tomasić, Jelka

    2008-01-01

    Various amounts of Ovalbumin (OVA) were encapsulated into positively and negatively charged multilamellar liposomes, with the aim to investigate the entrapment efficiency in different buffers and to study their effects on the liposome size and zeta potential. Results showed that the entrapment efficiency of OVA in anionic liposomes was the same in 10 mM Phosphate Buffer (PB) as in Phosphate-Buffered Saline (PBS; PB + 0.15 M NaCl). Also, liposome size was approximately 1200 nm for all anionic liposomes incorporating OVA. The entrapment efficiency of OVA in cationic liposomes was highly dependent on ionic strength. The size of cationic liposomes was approximately 1200 nm in PBS, regardless of protein content, but increased with the amount of the incorporated protein in PB. Aggregation of cationic liposomes in PB was observed when the mass of the protein was 2.5 mg or greater. The zeta potential of anionic liposomes was negative and of cationic liposomes positive in the whole range of protein mass tested. These results show how different compositions of lipid and aqueous phases can be used to vary the entrapment efficiency, liposome size, and zeta potential--the factors that are of great importance for the use of liposomes as drug carriers.

  12. Zeta potentials in the flotation of oxide and silicate minerals.

    Science.gov (United States)

    Fuerstenau, D W; Pradip

    2005-06-30

    Adsorption of collectors and modifying reagents in the flotation of oxide and silicate minerals is controlled by the electrical double layer at the mineral-water interface. In systems where the collector is physically adsorbed, flotation with anionic or cationic collectors depends on the mineral surface being charged oppositely. Adjusting the pH of the system can enhance or prevent the flotation of a mineral. Thus, the point of zero charge (PZC) of the mineral is the most important property of a mineral in such systems. The length of the hydrocarbon chain of the collector is important because of chain-chain association enhances the adsorption once the surfactant ions aggregate to form hemimicelles at the surface. Strongly chemisorbing collectors are able to induce flotation even when collector and the mineral surface are charged similarly, but raising the pH sufficiently above the PZC can repel chemisorbing collectors from the mineral surface. Zeta potentials can be used to delineate interfacial phenomena in these various systems.

  13. Oscillatory electroosmotic flow in a parallel-plate microchannel under asymmetric zeta potentials

    Science.gov (United States)

    Peralta, M.; Arcos, J.; Méndez, F.; Bautista, O.

    2017-06-01

    In this work, we conduct a theoretical analysis of the start-up of an oscillatory electroosmotic flow (EOF) in a parallel-plate microchannel under asymmetric zeta potentials. It is found that the transient evolution of the flow field is controlled by the parameters {R}ω , {R}\\zeta , and \\bar{κ }, which represent the dimensionless frequency, the ratio of the zeta potentials of the microchannel walls, and the electrokinetic parameter, which is defined as the ratio of the microchannel height to the Debye length. The analysis is performed for both low and high zeta potentials; in the former case, an analytical solution is derived, whereas in the latter, a numerical solution is obtained. These solutions provide the fundamental characteristics of the oscillatory EOFs for which, with suitable adjustment of the zeta potential and the dimensionless frequency, the velocity profiles of the fluid flow exhibit symmetric or asymmetric shapes.

  14. Influence of surface conductivity on the apparent zeta potential of calcite.

    Science.gov (United States)

    Li, Shuai; Leroy, Philippe; Heberling, Frank; Devau, Nicolas; Jougnot, Damien; Chiaberge, Christophe

    2016-04-15

    Zeta potential is a physicochemical parameter of particular importance in describing the surface electrical properties of charged porous media. However, the zeta potential of calcite is still poorly known because of the difficulty to interpret streaming potential experiments. The Helmholtz-Smoluchowski (HS) equation is widely used to estimate the apparent zeta potential from these experiments. However, this equation neglects the influence of surface conductivity on streaming potential. We present streaming potential and electrical conductivity measurements on a calcite powder in contact with an aqueous NaCl electrolyte. Our streaming potential model corrects the apparent zeta potential of calcite by accounting for the influence of surface conductivity and flow regime. We show that the HS equation seriously underestimates the zeta potential of calcite, particularly when the electrolyte is diluted (ionic strength ⩽ 0.01 M) because of calcite surface conductivity. The basic Stern model successfully predicted the corrected zeta potential by assuming that the zeta potential is located at the outer Helmholtz plane, i.e. without considering a stagnant diffuse layer at the calcite-water interface. The surface conductivity of calcite crystals was inferred from electrical conductivity measurements and computed using our basic Stern model. Surface conductivity was also successfully predicted by our surface complexation model. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Zeta potential of microfluidic substrates: 1. Theory, experimental techniques, and effects on separations.

    Science.gov (United States)

    Kirby, Brian J; Hasselbrink, Ernest F

    2004-01-01

    This paper summarizes theory, experimental techniques, and the reported data pertaining to the zeta potential of silica and silicon with attention to use as microfluidic substrate materials, particularly for microchip chemical separations. Dependence on cation concentration, buffer and cation type, pH, cation valency, and temperature are discussed. The Debye-Hückel limit, which is often correctly treated as a good approximation for describing the ion concentration in the double layer, can lead to serious errors if it is extended to predict the dependence of zeta potential on the counterion concentration. For indifferent univalent electrolytes (e.g., sodium and potassium), two simple scalings for the dependence of zeta potential on counterion concentration can be derived in high- and low-zeta limits of the nonlinear Poisson-Boltzman equation solution in the double layer. It is shown that for most situations relevant to microchip separations, the high-zeta limit is most applicable, leading to the conclusion that the zeta potential on silica substrates is approximately proportional to the logarithm of the molar counterion concentration. The zeta vs. pH dependence measurements from several experiments are compared by normalizing the zeta based on concentration.

  16. Cellular internalization of polycation-coated microparticles and its dependence on their zeta potential

    Science.gov (United States)

    Kato, Noritaka; Kondo, Ryosuke

    2018-03-01

    By applying microparticles to HeLa cells, the number of particles adhered on the cell and that of the ones internalized in the cells were evaluated. Three-dimensional tomographic images of the cells with the particles were obtained by multiphoton excitation laser scanning microscopy, and the adhered and internalized particles were counted separately. When the surface charge of the particles was reversed from negative to positive by coating the particles with polycations, both numbers significantly increased owing to the electrostatic attraction between the cells and the polycation-coated particles. Four different positively charged particles were prepared using four different polycations, and the numbers of adhered and internalized particles were compared. Our results suggest that these numbers depended on the zeta potential rather than the molecular structure of the polycation.

  17. An induced current method for measuring zeta potential of electrolyte solution-air interface.

    Science.gov (United States)

    Song, Yongxin; Zhao, Kai; Wang, Junsheng; Wu, Xudong; Pan, Xinxiang; Sun, Yeqing; Li, Dongqing

    2014-02-15

    This paper reports a novel and very simple method for measuring the zeta potential of electrolyte solution-air interface. When a measuring electrode contacts the electrolyte solution-air interface, an electrical current will be generated due to the potential difference between the electrode-air surface and the electrolyte solution-air interface. The amplitude of the measured electric signal is linearly proportional to this potential difference; and depends only on the zeta potential at the electrolyte solution-air interface, regardless of the types and concentrations of the electrolyte. A correlation between the zeta potential and the measured voltage signal is obtained based on the experimental data. Using this equation, the zeta potential of any electrolyte solution-air interface can be evaluated quickly and easily by inserting an electrode through the electrolyte solution-air interface and measuring the electrical signal amplitude. This method was verified by comparing the obtained results of NaCl, MgCl2 and CaCl2 solutions of different pH values and concentrations with the zeta potential data reported in the published journal papers. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Effect of Zeta Potential on the Properties of Nano-Drug Delivery ...

    African Journals Online (AJOL)

    Zeta potential is a scientific term for electrokinetic potential in colloidal systems which has a major effect on the various properties of nano-drug delivery systems. Presently, colloidal nano-carriers are growing at a remarkable rate owing to their strong potential for overcoming old challenges such as poor drug solubility and ...

  19. Application of the zeta potential for stationary phase characterization in ion chromatography.

    Science.gov (United States)

    Buszewski, Bogusław; Jaćkowska, Magdalena; Bocian, Szymon; Dziubakiewicz, Ewelina

    2013-01-01

    Two series of homemade stationary bonded phases for ion chromatography were investigated according to their zeta potential. One set of dendrimer anion exchanger was synthesized on the polymer support whereas the second material was prepared on the silica gel. The zeta potential data in water environment as well as buffered water solution were obtained. The influence of the length of anion-exchanger chains, the type of the support of the modified surface, and charge distribution on these data was investigated. Additionally, the zeta potential was correlated with retention factor of inorganic ions to describe their influence on the retention mechanism in ion chromatography. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Analyte preconcentration in nanofluidic channels with nonuniform zeta potential

    Science.gov (United States)

    Eden, A.; McCallum, C.; Storey, B. D.; Pennathur, S.; Meinhart, C. D.

    2017-12-01

    It is well known that charged analytes in the presence of nonuniform electric fields concentrate at locations where the relevant driving forces balance, and a wide range of ionic stacking and focusing methods are commonly employed to leverage these physical mechanisms in order to improve signal levels in biosensing applications. In particular, nanofluidic channels with spatially varying conductivity distributions have been shown to provide increased preconcentration of charged analytes due to the existence of a finite electric double layer (EDL), in which electrostatic attraction and repulsion from charged surfaces produce nonuniform transverse ion distributions. In this work, we use numerical simulations to show that one can achieve greater levels of sample accumulation by using field-effect control via wall-embedded electrodes to tailor the surface potential heterogeneity in a nanochannel with overlapped EDLs. In addition to previously demonstrated stacking and focusing mechanisms, we find that the coupling between two-dimensional ion distributions and the axial electric field under overlapped EDL conditions can generate an ion concentration polarization interface in the middle of the channel. Under an applied electric field, this interface can be used to concentrate sample ions between two stationary regions of different surface potential and charge density. Our numerical model uses the Poisson-Nernst-Planck system of equations coupled with the Stokes equation to demonstrate the phenomenon, and we discuss in detail the driving forces behind the predicted sample enhancement. The numerical velocity and salt concentration profiles exhibit good agreement with analytical results from a simplified one-dimensional area-averaged model for several limiting cases, and we show predicted amplification ratios of up to 105.

  1. Synthesis, bioactivity and zeta potential investigations of chlorine and fluorine substituted hydroxyapatite.

    Science.gov (United States)

    Fahami, Abbas; Beall, Gary W; Betancourt, Tania

    2016-02-01

    Chlorine and fluorine substituted hydroxyapatites (HA-Cl-F) with different degrees of ion replacement were successfully prepared by the one step mechanochemical activation method. X-ray diffraction (XRD) and FT-IR spectra indicated that substitution of these anions in milled powders resulted in the formation of pure hydroxyapatite phase except for the small observed change in the lattice parameters and unit cell volumes of the resultant hydroxyapatite. Microscopic observations showed that the milled product had a cluster-like structure made up of polygonal and spherical particles with an average particle size of approximately ranged from 20±5 to 70±5nm. The zeta potential of milled samples was performed at three different pH (5, 7.4, and 9). The obtained zeta potential values were negative for all three pH values. Negative zeta potential was described to favor osseointegration, apatite nucleation, and bone regeneration. The bioactivity of samples was investigated on sintered pellets soaked in simulated body fluid (SBF) solution and apatite crystals formed on the surface of the pellets after being incubated for 14days. Zeta potential analysis and bioactivity experiment suggested that HA-Cl-F will lead to the formation of new apatite particles and therefore be a potential implant material. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Effect of Zeta Potential on the Properties of Nano-Drug Delivery ...

    African Journals Online (AJOL)

    The zeta potential (ZP) of colloidal systems and nano-medicines, as well as their particle size exert a major effect on the various properties of nano-drug delivery systems. Not only the stability of dosage forms and their release rate are affected but also their circulation in the blood stream and absorption into body membranes ...

  3. Zeta potential of Polish copper-bearing shale in the absence and presence of flotation frothers

    Directory of Open Access Journals (Sweden)

    Mengsu Peng

    2014-09-01

    Full Text Available In this paper, zeta potential as a function of pH of copper-bearing shale, which is mined in Poland by KGHM, was investigated. The measurements were conducted in water and aqueous solutions of selected flotation frothers. It was established that for investigated copper-bearing shale, after dispersion in water, the isoelectric point (IEP occurs at pH=3.5. Addition of frothers decreased the IEP on the pH scale and the IEP for butanol was 1.93, for MIBC 2.90 and for eicosaethylene glycol hexadecyl ether (C16E20 2.76. In the case of introducing frothers changed, the zeta potential becomes less negative. An empirical equation, having two adjustable parameters, was used in the paper to approximate the course of the zeta potential-pH curve. The equation showed a very good approximation of the zeta potential of the investigated shale either in water or frother aqueous solutions.

  4. Reduced Zeta potential through use of cationic adhesion promoter for improved resist process performance and minimizing material consumption

    Science.gov (United States)

    Hodgson, Lorna; Thompson, Andrew

    2012-03-01

    This paper presents the results of a non-HMDS (non-silane) adhesion promoter that was used to reduce the zeta potential for very thin (proprietary) polymer on silicon. By reducing the zeta potential, as measured by the minimum sample required to fully coat a wafer, the amount of polymer required to coat silicon substrates was significantly reduced in the manufacture of X-ray windows used for high transmission of low-energy X-rays. Moreover, this approach used aqueous based adhesion promoter described as a cationic surface active agent that has been shown to improve adhesion of photoresists (positive, negative, epoxy [SU8], e-beam and dry film). As well as reducing the amount of polymer required to coat substrates, this aqueous adhesion promoter is nonhazardous, and contains non-volatile solvents.

  5. Synthesis, bioactivity and zeta potential investigations of chlorine and fluorine substituted hydroxyapatite

    International Nuclear Information System (INIS)

    Fahami, Abbas; Beall, Gary W.; Betancourt, Tania

    2016-01-01

    Chlorine and fluorine substituted hydroxyapatites (HA-Cl–F) with different degrees of ion replacement were successfully prepared by the one step mechanochemical activation method. X-ray diffraction (XRD) and FT-IR spectra indicated that substitution of these anions in milled powders resulted in the formation of pure hydroxyapatite phase except for the small observed change in the lattice parameters and unit cell volumes of the resultant hydroxyapatite. Microscopic observations showed that the milled product had a cluster-like structure made up of polygonal and spherical particles with an average particle size of approximately ranged from 20 ± 5 to 70 ± 5 nm. The zeta potential of milled samples was performed at three different pH (5, 7.4, and 9). The obtained zeta potential values were negative for all three pH values. Negative zeta potential was described to favor osseointegration, apatite nucleation, and bone regeneration. The bioactivity of samples was investigated on sintered pellets soaked in simulated body fluid (SBF) solution and apatite crystals formed on the surface of the pellets after being incubated for 14 days. Zeta potential analysis and bioactivity experiment suggested that HA-Cl–F will lead to the formation of new apatite particles and therefore be a potential implant material. - Highlights: • Cl"− and F"− substituted hydroxyapatite was synthesized by mechanochemical process. • Structural features were influenced strongly by incorporation of different ions. • Microscopic observations showed a mean particle size of around 20 ± 5 to 70 ± 5 nm. • The bioactivity properties indicated that apatite was successfully formed.

  6. Synthesis, bioactivity and zeta potential investigations of chlorine and fluorine substituted hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Fahami, Abbas, E-mail: fahami@txstate.edu [Materials Science, Engineering and Commercialization Program, Texas State University, San Marcos, TX 78666 (United States); Beall, Gary W. [Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX 78666 (United States); Physics Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Betancourt, Tania [Materials Science, Engineering and Commercialization Program, Texas State University, San Marcos, TX 78666 (United States); Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX 78666 (United States)

    2016-02-01

    Chlorine and fluorine substituted hydroxyapatites (HA-Cl–F) with different degrees of ion replacement were successfully prepared by the one step mechanochemical activation method. X-ray diffraction (XRD) and FT-IR spectra indicated that substitution of these anions in milled powders resulted in the formation of pure hydroxyapatite phase except for the small observed change in the lattice parameters and unit cell volumes of the resultant hydroxyapatite. Microscopic observations showed that the milled product had a cluster-like structure made up of polygonal and spherical particles with an average particle size of approximately ranged from 20 ± 5 to 70 ± 5 nm. The zeta potential of milled samples was performed at three different pH (5, 7.4, and 9). The obtained zeta potential values were negative for all three pH values. Negative zeta potential was described to favor osseointegration, apatite nucleation, and bone regeneration. The bioactivity of samples was investigated on sintered pellets soaked in simulated body fluid (SBF) solution and apatite crystals formed on the surface of the pellets after being incubated for 14 days. Zeta potential analysis and bioactivity experiment suggested that HA-Cl–F will lead to the formation of new apatite particles and therefore be a potential implant material. - Highlights: • Cl{sup −} and F{sup −} substituted hydroxyapatite was synthesized by mechanochemical process. • Structural features were influenced strongly by incorporation of different ions. • Microscopic observations showed a mean particle size of around 20 ± 5 to 70 ± 5 nm. • The bioactivity properties indicated that apatite was successfully formed.

  7. Influence of synthesis parameters on iron nanoparticle size and zeta potential

    Science.gov (United States)

    Goldstein, Nikki; Greenlee, Lauren F.

    2012-03-01

    Zero valent iron nanoparticles are of increasing interest in clean water treatment applications due to their reactivity toward organic contaminants and their potential to degrade a variety of compounds. This study focuses on the effect of organophosphate stabilizers on nanoparticle characteristics, including particle size distribution and zeta potential, when the stabilizer is present during nanoparticle synthesis. Particle size distributions from DLS were obtained as a function of stabilizer type and iron precursor (FeSO4·7H2O or FeCl3), and nanoparticles from 2 to 200 nm were produced. Three different organophosphate stabilizer compounds were compared in their ability to control nanoparticle size, and the size distributions obtained for particle volume demonstrated differences caused by the three stabilizers. A range of stabilizer-to-iron (0.05-0.9) and borohydride-to-iron (0.5-8) molar ratios were tested to determine the effect of concentration on nanoparticle size distribution and zeta potential. The combination of ferrous sulfate and ATMP or DTPMP phosphonate stabilizer produced stabilized nanoparticle suspensions, and the stabilizers tested resulted in varying particle size distributions. In general, higher stabilizer concentrations resulted in smaller nanoparticles, and excess borohydride did not decrease nanoparticle size. Zeta potential measurements were largely consistent with particle size distribution data and indicated the stability of the suspensions. Probe sonication, as a nanoparticle resuspension method, was minimally successful in several different organic solvents.

  8. Influence of synthesis parameters on iron nanoparticle size and zeta potential

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, Nikki; Greenlee, Lauren F., E-mail: lauren.greenlee@nist.gov [National Institute of Standards and Technology, Materials Reliability Division (United States)

    2012-03-15

    Zero valent iron nanoparticles are of increasing interest in clean water treatment applications due to their reactivity toward organic contaminants and their potential to degrade a variety of compounds. This study focuses on the effect of organophosphate stabilizers on nanoparticle characteristics, including particle size distribution and zeta potential, when the stabilizer is present during nanoparticle synthesis. Particle size distributions from DLS were obtained as a function of stabilizer type and iron precursor (FeSO{sub 4}{center_dot}7H{sub 2}O or FeCl{sub 3}), and nanoparticles from 2 to 200 nm were produced. Three different organophosphate stabilizer compounds were compared in their ability to control nanoparticle size, and the size distributions obtained for particle volume demonstrated differences caused by the three stabilizers. A range of stabilizer-to-iron (0.05-0.9) and borohydride-to-iron (0.5-8) molar ratios were tested to determine the effect of concentration on nanoparticle size distribution and zeta potential. The combination of ferrous sulfate and ATMP or DTPMP phosphonate stabilizer produced stabilized nanoparticle suspensions, and the stabilizers tested resulted in varying particle size distributions. In general, higher stabilizer concentrations resulted in smaller nanoparticles, and excess borohydride did not decrease nanoparticle size. Zeta potential measurements were largely consistent with particle size distribution data and indicated the stability of the suspensions. Probe sonication, as a nanoparticle resuspension method, was minimally successful in several different organic solvents.

  9. Influence of synthesis parameters on iron nanoparticle size and zeta potential

    International Nuclear Information System (INIS)

    Goldstein, Nikki; Greenlee, Lauren F.

    2012-01-01

    Zero valent iron nanoparticles are of increasing interest in clean water treatment applications due to their reactivity toward organic contaminants and their potential to degrade a variety of compounds. This study focuses on the effect of organophosphate stabilizers on nanoparticle characteristics, including particle size distribution and zeta potential, when the stabilizer is present during nanoparticle synthesis. Particle size distributions from DLS were obtained as a function of stabilizer type and iron precursor (FeSO 4 ·7H 2 O or FeCl 3 ), and nanoparticles from 2 to 200 nm were produced. Three different organophosphate stabilizer compounds were compared in their ability to control nanoparticle size, and the size distributions obtained for particle volume demonstrated differences caused by the three stabilizers. A range of stabilizer-to-iron (0.05–0.9) and borohydride-to-iron (0.5–8) molar ratios were tested to determine the effect of concentration on nanoparticle size distribution and zeta potential. The combination of ferrous sulfate and ATMP or DTPMP phosphonate stabilizer produced stabilized nanoparticle suspensions, and the stabilizers tested resulted in varying particle size distributions. In general, higher stabilizer concentrations resulted in smaller nanoparticles, and excess borohydride did not decrease nanoparticle size. Zeta potential measurements were largely consistent with particle size distribution data and indicated the stability of the suspensions. Probe sonication, as a nanoparticle resuspension method, was minimally successful in several different organic solvents.

  10. Electroosmotic flow of Phan-Thien-Tanner fluids at high zeta potentials: An exact analytical solution

    Science.gov (United States)

    Sarma, Rajkumar; Deka, Nabajit; Sarma, Kuldeep; Mondal, Pranab Kumar

    2018-06-01

    We present a mathematical model to study the electroosmotic flow of a viscoelastic fluid in a parallel plate microchannel with a high zeta potential, taking hydrodynamic slippage at the walls into account in the underlying analysis. We use the simplified Phan-Thien-Tanner (s-PTT) constitutive relationships to describe the rheological behavior of the viscoelastic fluid, while Navier's slip law is employed to model the interfacial hydrodynamic slip. Here, we derive analytical solutions for the potential distribution, flow velocity, and volumetric flow rate based on the complete Poisson-Boltzmann equation (without considering the frequently used Debye-Hückel linear approximation). For the underlying electrokinetic transport, this investigation primarily reveals the influence of fluid rheology, wall zeta potential as modulated by the interfacial electrochemistry and interfacial slip on the velocity distribution, volumetric flow rate, and fluid stress, as well as the apparent viscosity. We show that combined with the viscoelasticity of the fluid, a higher wall zeta potential and slip coefficient lead to a phenomenal enhancement in the volumetric flow rate. We believe that this analysis, besides providing a deep theoretical insight to interpret the transport process, will also serve as a fundamental design tool for microfluidic devices/systems under electrokinetic influence.

  11. Effects on functional groups and zeta potential of SAP1pulsed electric field technology.

    Science.gov (United States)

    Liang, Rong; Li, Xuenan; Lin, Songyi; Wang, Jia

    2017-01-01

    SAP 1 pulsed electric field (PEF) technology. The effects of electric field intensity and pulse frequency on SAP 1 electric field intensity 15 kV cm -1 , pulse frequency 1600 Hz and flow velocity 2.93 mL min -1 ). Furthermore, the PEF-treated SAP 1 < MW < 3kDa under optimal conditions lacked the characteristic absorbance of N-H, C = C and the amide band and the zeta potential was reduced to -18.0 mV. Overall, the results of the present study suggest that the improvement of antioxidant activity of SAP 1 < MW < 3kDa is a result of the contribution of the functional groups and the change in zeta potential when treated with PEF. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  12. A Comparison of Streaming and Microelectrophoresis Methods for Obtaining the zeta Potential of Granular Porous Media Surfaces.

    Science.gov (United States)

    Johnson

    1999-01-01

    The electrokinetic behavior of granular quartz sand in aqueous solution is investigated by both microelectrophoresis and streaming potential methods. zeta potentials of surfaces composed of granular quartz obtained via streaming potential methods are compared to electrophoretic mobility zeta potential values of colloid-sized quartz fragments. The zeta values generated by these alternate methods are in close agreement over a wide pH range and electrolyte concentrations spanning several orders of magnitude. Streaming measurements performed on chemically heterogeneous mixtures of physically homogeneous sand are shown to obey a simple mixing model based on the surface area-weighted average of the streaming potentials associated with the individual end members. These experimental results support the applicability of the streaming potential method as a means of determining the zeta potential of granular porous media surfaces. Copyright 1999 Academic Press.

  13. Improving the Efficiency of a Coagulation-Flocculation Wastewater Treatment of the Semiconductor Industry through Zeta Potential Measurements

    OpenAIRE

    López-Maldonado, Eduardo Alberto; Oropeza-Guzmán, Mercedes Teresita; Ochoa-Terán, Adrián

    2014-01-01

    Efficiency of coagulation-flocculation process used for semiconductor wastewater treatment was improved by selecting suitable conditions (pH, polyelectrolyte type, and concentration) through zeta potential measurements. Under this scenario the zeta potential, ζ, is the right parameter that allows studying and predicting the interactions at the molecular level between the contaminants in the wastewater and polyelectrolytes used for coagulation-flocculation. Additionally, this parameter is a k...

  14. Effective flocculation of Chlorella vulgaris using chitosan with zeta potential measurement

    Science.gov (United States)

    Low, Y. J.; Lau, S. W.

    2017-06-01

    Microalgae are considered as one promising source of third-generation biofuels due to their fast growth rates, potentially higher yield rates and wide ranges of growth conditions. However, the extremely low biomass concentration in microalgae cultures presents a great challenge to the harvesting of microalgae because a large volume of water needs to be removed to obtain dry microalgal cells for the subsequent oil extraction process. In this study, the fresh water microalgae Chlorella vulgaris (C. vulgaris) was effectively harvested using both low molecular weight (MW) and high MW chitosan flocculants. The flocculation efficiency was evaluated by physical appearance, supernatant absorbance, zeta potential and solids content after centrifugal dewatering. High flocculation efficiency of 98.0-99.0% was achieved at the optimal dosage of 30-40 mg/g with formation of large microalgae flocs. This study suggests that the polymer bridging mechanism was governing the flocculation behaviour of C. vulgaris using high MW chitosan. Besides, charge patch neutralisation mechanism prevailed at low MW chitosan where lower dosage was sufficient to reach near-zero zeta potential compared with the high MW chitosan. The amount of chitosan polymer present in the culture may also affect the mechanism of flocculation.

  15. Zeta potential control in decontamination with inorganic membranes and inorganic adsorbents

    Energy Technology Data Exchange (ETDEWEB)

    Andalaft, E; Vega, R; Correa, M; Araya, R; Loyola, P [Comision Chilena de Energia Nuclear, Santiago (Chile)

    1997-02-01

    The application of some advanced separation processes such as microfiltration and ultrafiltration, electroosmosis and electrodialysis for treating nuclear waste from different aqueous streams is under examination at the Chilean Commission for Nuclear Energy. The application of these techniques can be extended to regular industrial wastes when economically advisable. This report deals mainly with electrodialysis, electroosmosis and adsorption with inorganic materials. Special attention is paid to zeta potential control as a driving factor to electroosmosis. For radioactive contaminants that are present in the form of cations, anions, non-ionic solutions, colloids and suspended matter, appropriate combination of the processes may considerably increase the efficiency of processes used. As an example, colloids and suspended particles may be retained in porous ceramic membranes by nanofiltration, ultrafiltration or microfiltration depending on the particle size of the particles. The control of zeta potential by acting in the solid phase or else on the liquid phase has been studied; a mathematical model to predict electrodialysis data has been developed, and finally, the use of a home-made inorganic adsorbent illustrated. The effect of gamma irradiation on the membranes has also been studied. Properties such as salt retention, water flux and pore size diameter determined on both organic and inorganic membranes before and after irradiation indicate deterioration of the organic membrane. (author). 13 refs, 15 figs, 2 tabs.

  16. Zeta potential control in decontamination with inorganic membranes and inorganic adsorbents

    International Nuclear Information System (INIS)

    Andalaft, E.; Vega, R.; Correa, M.; Araya, R.; Loyola, P.

    1997-01-01

    The application of some advanced separation processes such as microfiltration and ultrafiltration, electroosmosis and electrodialysis for treating nuclear waste from different aqueous streams is under examination at the Chilean Commission for Nuclear Energy. The application of these techniques can be extended to regular industrial wastes when economically advisable. This report deals mainly with electrodialysis, electroosmosis and adsorption with inorganic materials. Special attention is paid to zeta potential control as a driving factor to electroosmosis. For radioactive contaminants that are present in the form of cations, anions, non-ionic solutions, colloids and suspended matter, appropriate combination of the processes may considerably increase the efficiency of processes used. As an example, colloids and suspended particles may be retained in porous ceramic membranes by nanofiltration, ultrafiltration or microfiltration depending on the particle size of the particles. The control of zeta potential by acting in the solid phase or else on the liquid phase has been studied; a mathematical model to predict electrodialysis data has been developed, and finally, the use of a home-made inorganic adsorbent illustrated. The effect of gamma irradiation on the membranes has also been studied. Properties such as salt retention, water flux and pore size diameter determined on both organic and inorganic membranes before and after irradiation indicate deterioration of the organic membrane. (author). 13 refs, 15 figs, 2 tabs

  17. Stability of fenbendazole suspensions for veterinary use. Correlation between zeta potential and sedimentation.

    Science.gov (United States)

    Arias, José L; López-Viota, Margarita; Clares, Beatriz; Ruiz, Ma Adolfina

    2008-08-07

    In this paper we have carried out a detailed investigation of the stability and redispersibility characteristics of fenbendazole aqueous suspensions, through a thermodynamic and electrokinetic characterization, considering the effect of both pH and ionic strength. The hydrophobic character of the drug, and the surface charge and electrical double-layer thickness play an essential role in the stability of the system, hence the need for a full characterization of fenbendazole. It was found that the drug suspensions displays "delayed" or "hindered" sedimentation, determined by their hydrophobic character and their low zeta potential (indicating a small electrokinetic charge on the particles). The electrostatic repulsion between the particles is responsible for the low sedimentation volume and poor redispersibility of the drug. However, only low concentrations of AlCl(3) induced a significant effect on both the zeta potential and stability of the drug, leading to a "free-layered" sedimentation and a very easy redispersion which could be of great interest in the design of an oral pharmaceutical dosage form for veterinary.

  18. The Isolation of DNA by Polycharged Magnetic Particles: An Analysis of the Interaction by Zeta Potential and Particle Size.

    Science.gov (United States)

    Haddad, Yazan; Xhaxhiu, Kledi; Kopel, Pavel; Hynek, David; Zitka, Ondrej; Adam, Vojtech

    2016-04-20

    Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated), MAN127 (polyvinylpyrrolidone-coated), MAN158 (phosphate-coated), and MAN164 (tripolyphosphate-coated). All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of -0.22 mV under binding conditions (high ionic strength, low pH, and dehydration). A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.

  19. ZETA POTENTIAL AND COLOR INVESTIGATIONS OF VEGETABLE OIL BASED EMULSIONS AS ECO-FRIENDLY LUBRICANTS

    Directory of Open Access Journals (Sweden)

    ROMICĂ CREŢU

    2017-06-01

    Full Text Available In the past 10 years, the need for biodegradable lubricants has been more and more emphasized. The use of vegetable oils as lubricants offers several advantages. The vegetable oils are biodegradable; thus, the environmental pollution is minimal either during or after their use. The aim of this paper is to presents a preliminary study concerning the influence of some preparation conditions on the stability of vegetable oil-in-water (O/W emulsions as eco-friendly lubricants stabilized by nonionic surfactant. In this context, vegetable oil-in-water emulsions characteristics where assessed using microscopically observation and zeta potential. In addition, the color of these emulsions can be evaluated. It can be observed that the emulsions tend to stabilize in time.

  20. Hydrodynamic dispersion in a combined magnetohydrodynamic- electroosmotic-driven flow through a microchannel with slowly varying wall zeta potentials

    Science.gov (United States)

    Vargas, C.; Arcos, J.; Bautista, O.; Méndez, F.

    2017-09-01

    The effective dispersion coefficient of a neutral solute in the combined electroosmotic (EO) and magnetohydrodynamic (MHD)-driven flow of a Newtonian fluid through a parallel flat plate microchannel is studied. The walls of the microchannel are assumed to have modulated and low zeta potentials that vary slowly in the axial direction in a sinusoidal manner. The flow field required to obtain the dispersion coefficient is solved using the lubrication approximation theory. The solution of the electrical potential is based on the Debye-Hückel approximation for a symmetric (Z :Z ) electrolyte solution. The EO and MHD effects, together with the variations in the zeta potentials of the walls, are observed to notably modify the axial distribution of the effective dispersion coefficient. The problem is formulated for two cases of the zeta potential function. Note that the dispersion coefficient primarily depends on the Hartmann number, on the ratio of the half height of the microchannel to the Debye length, and on the assumed variation in the zeta potentials of the walls.

  1. Effects of image charges, interfacial charge discreteness, and surface roughness on the zeta potential of spherical electric double layers.

    Science.gov (United States)

    Gan, Zecheng; Xing, Xiangjun; Xu, Zhenli

    2012-07-21

    We investigate the effects of image charges, interfacial charge discreteness, and surface roughness on spherical electric double layer structures in electrolyte solutions with divalent counterions in the setting of the primitive model. By using Monte Carlo simulations and the image charge method, the zeta potential profile and the integrated charge distribution function are computed for varying surface charge strengths and salt concentrations. Systematic comparisons were carried out between three distinct models for interfacial charges: (1) SURF1 with uniform surface charges, (2) SURF2 with discrete point charges on the interface, and (3) SURF3 with discrete interfacial charges and finite excluded volume. By comparing the integrated charge distribution function and the zeta potential profile, we argue that the potential at the distance of one ion diameter from the macroion surface is a suitable location to define the zeta potential. In SURF2 model, we find that image charge effects strongly enhance charge inversion for monovalent interfacial charges, and strongly suppress charge inversion for multivalent interfacial charges. For SURF3, the image charge effect becomes much smaller. Finally, with image charges in action, we find that excluded volumes (in SURF3) suppress charge inversion for monovalent interfacial charges and enhance charge inversion for multivalent interfacial charges. Overall, our results demonstrate that all these aspects, i.e., image charges, interfacial charge discreteness, their excluding volumes, have significant impacts on zeta potentials of electric double layers.

  2. Surface and zeta-potentials of silver halide single crystals: pH-dependence in comparison to particle systems

    International Nuclear Information System (INIS)

    Selmani, Atiða; Kallay, Nikola; Preočanin, Tajana; Lützenkirchen, Johannes

    2014-01-01

    We have carried out surface and zeta-potential measurements on AgCl and AgBr single crystals. As for particle systems we find that, surprisingly and previously unnoted, the zeta-potential exhibits pH-dependence, while the surface potential does not. A possible interpretation of these observations is the involvement of water ions in the interfacial equilibria and in particular, stronger affinity of the hydroxide ion compared to the proton. The pH-dependence of the zeta-potential can be suppressed at sufficiently high silver concentrations, which agrees with previous measurements in particle systems where no pH-dependence was found at high halide ion concentrations. The results suggest a subtle interplay between the surface potential determining the halide and silver ion concentrations, and the water ions. Whenever the charge due to the halide and silver ions is sufficiently high, the influence of the proton/hydroxide ion on the zeta-potential vanishes. This might be related to the water structuring at the relevant interfaces which should be strongly affected by the surface potential. Another interesting observation is accentuation of the assumed water ion effect on the zeta-potential at the flat single crystal surfaces compared to the corresponding silver halide colloids. Previous generic MD simulations have indeed predicted that hydroxide ion adsorption is accentuated on flat/rigid surfaces. A thermodynamic model for AgI single crystals was developed to describe the combined effects of iodide, silver and water ions, based on two independently previously published models for AgI (that only consider constituent and background electrolyte ions) and inert surfaces (that only consider water and background electrolyte ions). The combined model correctly predicts all the experimentally observed trends. (paper)

  3. Estimation of Nanodiamond Surface Charge Density from Zeta Potential and Molecular Dynamics Simulations.

    Science.gov (United States)

    Ge, Zhenpeng; Wang, Yi

    2017-04-20

    Molecular dynamics simulations of nanoparticles (NPs) are increasingly used to study their interactions with various biological macromolecules. Such simulations generally require detailed knowledge of the surface composition of the NP under investigation. Even for some well-characterized nanoparticles, however, this knowledge is not always available. An example is nanodiamond, a nanoscale diamond particle with surface dominated by oxygen-containing functional groups. In this work, we explore using the harmonic restraint method developed by Venable et al., to estimate the surface charge density (σ) of nanodiamonds. Based on the Gouy-Chapman theory, we convert the experimentally determined zeta potential of a nanodiamond to an effective charge density (σ eff ), and then use the latter to estimate σ via molecular dynamics simulations. Through scanning a series of nanodiamond models, we show that the above method provides a straightforward protocol to determine the surface charge density of relatively large (> ∼100 nm) NPs. Overall, our results suggest that despite certain limitation, the above protocol can be readily employed to guide the model construction for MD simulations, which is particularly useful when only limited experimental information on the NP surface composition is available to a modeler.

  4. Interaction of cement model systems with superplasticizers investigated by atomic force microscopy, zeta potential, and adsorption measurements.

    Science.gov (United States)

    Ferrari, Lucia; Kaufmann, Josef; Winnefeld, Frank; Plank, Johann

    2010-07-01

    Polyelectrolyte-based dispersants are commonly used in a wide range of industrial applications to provide specific workability to colloidal suspensions. Their working mechanism is based on adsorption onto the surfaces of the suspended particles. The adsorbed polymer layer can exercise an electrostatic and/or a steric effect which is responsible for achieving dispersion. This study is focused on the dispersion forces induced by polycarboxylate ether-based superplasticizers (PCEs) commonly used in concrete. They are investigated by atomic force microscopy (AFM) applying standard silicon nitride tips exposed to solutions with different ionic compositions in a wet cell. Adsorption isotherms and zeta potential analysis were performed to characterize polymer displacement in the AFM system on nonreactive model substrates (quartz, mica, calcite, and magnesium oxide) in order to avoid the complexity of cement hydration products. The results show that PCE is strongly adsorbed by positively charged materials. This fact reveals that, being silicon nitride naturally positively charged, in most cases the superplasticizer adsorbs preferably on the silicon nitride tip than on the AFM substrate. However, the force-distance curves displayed repulsive interactions between tip and substrates even when polymer was poorly adsorbed on both. These observations allow us to conclude that the dispersion due to PCE strongly depends on the particle charge. It differs between colloids adsorbing and not adsorbing PCE, and leads to different forces acting between the particles. Copyright 2010 Elsevier Inc. All rights reserved.

  5. Zeta potentials of the rare earth element fluorcarbonate minerals focusing on bastnäsite and parisite.

    Science.gov (United States)

    Owens, C L; Nash, G R; Hadler, K; Fitzpatrick, R S; Anderson, C G; Wall, F

    2018-06-01

    Rare earth elements (REE) are critical to a wide range of technologies ranging from mobile phones to wind turbines. Processing and extraction of REE minerals from ore bodies is, however, both challenging and relatively poorly understood, as the majority of deposits contain only limited enrichment of REEs. An improved understanding of the surface properties of the minerals is important in informing and optimising their processing, in particular for separation by froth flotation. The measurement of zeta potential can be used to extract information regarding the electrical double layer, and hence surface properties of these minerals. There are over 34 REE fluorcarbonate minerals currently identified, however bastnäsite, synchysite and parisite are of most economic importance. Bastnäsite-(Ce), the most common REE fluorcarbonate, supplies over 50% of the world's REE. Previous studies of bastnäsite have showed a wide range of surface behaviour, with the iso-electric point (IEP), being measured between pH values of 4.6 and 9.3. In contrast, no values of IEP have been reported for parisite or synchysite. In this work, we review previous studies of the zeta potentials of bastnäsite to investigate the effects of different methodologies and sample preparation. In addition, measurements of zeta potentials of parisite under water, collector and supernatant conditions were conducted, the first to be reported. These results showed an iso-electric point for parisite of 5.6 under water, with a shift to a more negative zeta potential with both collector (hydroxamic and fatty acids) and supernatant conditions. The IEP with collectors and supernatant was <3.5. As zeta potential measurements in the presence of reagents and supernatants are the most rigorous way of determining the efficiency of a flotation reagent, the agreement between parisite zeta potentials obtained here and previous work on bastnäsite suggests that parisite may be processed using similar reagent schemes to

  6. Flotation of algae for water reuse and biomass production: role of zeta potential and surfactant to separate algal particles.

    Science.gov (United States)

    Kwak, Dong-Heui; Kim, Mi-Sug

    2015-01-01

    The effect of chemical coagulation and biological auto-flocculation relative to zeta potential was examined to compare flotation and sedimentation separation processes for algae harvesting. Experiments revealed that microalgae separation is related to auto-flocculation of Anabaena spp. and requires chemical coagulation for the whole period of microalgae cultivation. In addition, microalgae separation characteristics which are associated with surfactants demonstrated optimal microalgae cultivation time and separation efficiency of dissolved CO2 flotation (DCF) as an alternative to dissolved air flotation (DAF). Microalgae were significantly separated in response to anionic surfactant rather than cationic surfactant as a function of bubble size and zeta potential. DAF and DCF both showed slightly efficient flotation; however, application of anionic surfactant was required when using DCF.

  7. Visualizing the transient electroosmotic flow and measuring the zeta potential of microchannels with a micro-PIV technique.

    Science.gov (United States)

    Yan, Deguang; Nguyen, Nam-Trung; Yang, Chun; Huang, Xiaoyang

    2006-01-14

    We have demonstrated a transient micro particle image velocimetry (micro-PIV) technique to measure the temporal development of electroosmotic flow in microchannels. Synchronization of different trigger signals for the laser, the CCD camera, and the high-voltage switch makes this measurement possible with a conventional micro-PIV setup. Using the transient micro-PIV technique, we have further proposed a method on the basis of inertial decoupling between the particle electrophoretic motion and the fluid electroosmotic flow to determine the electrophoretic component in the particle velocity and the zeta potential of the channel wall. It is shown that using the measured zeta potentials, the theoretical predictions agree well with the transient response of the electroosmotic velocities measured in this work.

  8. Zeta potential study of Sb2S3 nanoparticles synthesized by a facile polyol method in various surfactants

    Science.gov (United States)

    Saxena, Monika; Okram, Gunadhor Singh

    2018-05-01

    In the present work, we report the successful synthesis of stibnite Sb2S3 nanoparticles (NPs) by a facile polyol method using various surfactant. The structural and optical properties were investigated by X-ray diffraction (XRD), Raman spectroscopy and Zeta potential. Rietveld refinement of XRD data confirms the single phase orthorhombic crystal structure of stibnite Sb2S3. Presence of six obvious Raman modes further confirmed their stoichiometric formation. Effect of different surfactants on the surface charge of Sb2S3 NPs was studied using Zeta potential measurement in deionized water at different pH values. They reveal that these NPs are more stable when it was synthesized in presence of EDTA than that of CTAB or without surfactant samples with high zeta potential. The isoelectronic point was found at pH = 6.4 for pure sample, 3.5 and 7.2 for CTAB and not found for EDTA Sb2S3 samples. This information can be useful for many industrial applications like pharmaceuticals, ceramics, waste water treatment and medicines.

  9. Towards the Development of Global Nano-Quantitative Structure–Property Relationship Models: Zeta Potentials of Metal Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Andrey A. Toropov

    2018-04-01

    Full Text Available Zeta potential indirectly reflects a charge of the surface of nanoparticles in solutions and could be used to represent the stability of the colloidal solution. As processes of synthesis, testing and evaluation of new nanomaterials are expensive and time-consuming, so it would be helpful to estimate an approximate range of properties for untested nanomaterials using computational modeling. We collected the largest dataset of zeta potential measurements of bare metal oxide nanoparticles in water (87 data points. The dataset was used to develop quantitative structure–property relationship (QSPR models. Essential features of nanoparticles were represented using a modified simplified molecular input line entry system (SMILES. SMILES strings reflected the size-dependent behavior of zeta potentials, as the considered quasi-SMILES modification included information about both chemical composition and the size of the nanoparticles. Three mathematical models were generated using the Monte Carlo method, and their statistical quality was evaluated (R2 for the training set varied from 0.71 to 0.87; for the validation set, from 0.67 to 0.82; root mean square errors for both training and validation sets ranged from 11.3 to 17.2 mV. The developed models were analyzed and linked to aggregation effects in aqueous solutions.

  10. Interlaboratory comparison for the measurement of particle size and zeta potential of silica nanoparticles in an aqueous suspension

    Science.gov (United States)

    Lamberty, Andrée; Franks, Katrin; Braun, Adelina; Kestens, Vikram; Roebben, Gert; Linsinger, Thomas P. J.

    2011-12-01

    The Institute for Reference Materials and Measurements has organised an interlaboratory comparison (ILC) to allow the participating laboratories to demonstrate their proficiency in particle size and zeta potential measurements on monomodal aqueous suspensions of silica nanoparticles in the 10-100 nm size range. The main goal of this ILC was to identify competent collaborators for the production of certified nanoparticle reference materials. 38 laboratories from four different continents participated in the ILC with different methods for particle sizing and determination of zeta potential. Most of the laboratories submitted particle size results obtained with centrifugal liquid sedimentation (CLS), dynamic light scattering (DLS) or electron microscopy (EM), or zeta potential values obtained via electrophoretic light scattering (ELS). The results of the laboratories were evaluated using method-specific z scores, calculated on the basis of consensus values from the ILC. For CLS (13 results) and EM (13 results), all reported values were within the ±2 | z| interval. For DLS, 25 of the 27 results reported were within the ±2 | z| interval, the two other results were within the ±3 | z| interval. The standard deviations of the corresponding laboratory mean values varied between 3.7 and 6.5%, which demonstrates satisfactory interlaboratory comparability of CLS, DLS and EM particle size values. From the received test reports, a large discrepancy was observed in terms of the laboratory's quality assurance systems, which are equally important for the selection of collaborators in reference material certification projects. Only a minority of the participating laboratories is aware of all the items that are mandatory in test reports compliant to ISO/IEC 17025 (ISO General requirements for the competence of testing and calibration laboratories. International Organisation for Standardization, Geneva, 2005b). The absence of measurement uncertainty values in the reports, for

  11. The influence of zeta potential and yield stress on the filtration characteristics of a magnesium hydroxide simulant

    International Nuclear Information System (INIS)

    Biggs, Simon; Nabi, Rafiq; Poole, Colin; Patel, Ashok

    2007-01-01

    In the UK, irradiated fuels from Magnox reactors are often stored in water-filled ponds under alkaline conditions, so as to minimise corrosion of fuel cladding. This is important to prevent or reduce leakage of soluble fission products and actinides to the pond water. A variety of intermediate level wastes derived from Magnox materials are stored at power stations. Under these alkaline conditions, various species of magnesium are formed, of which magnesium hydroxide is the dominant material. The particle-fluid interactions are significant for the design and operation of facilities for hydraulic retrieval, filtration, dewatering and ion exchange treatment of fuel storage pond water and stored wet Magnox wastes. Here we describe a study of particulate properties and filtration characteristics of oxide particle simulants under laboratory conditions. Cake and medium resistance data were correlated across a range of pH conditions with electro-acoustic zeta potential and shear yield stress measurements, as a function of particle volume fractions. The influence of zeta potential on filtration properties arises directly from the interaction of particles within the sediment cake. (authors)

  12. Zeta potential and Raman studies of PVP capped Bi2S3 nanoparticles synthesized by polyol method

    Science.gov (United States)

    Tarachand, Sathe, Vasant G.; Okram, Gunadhor S.

    2018-05-01

    Here we report the synthesis and characterisation of polyvinylpyrrolidone (PVP) capped Bi2S3 nanoparticles via one step catalyst-free polyol method. Raman spectroscopy, dynamic light scattering and zeta potential analysis were performed on it. Rietveld refinement of powder XRD of PVP capped samples confirmed the formation of single phase orthorhombic Bi2S3 for all PVP capped samples. The presence of eight obvious Raman modes further confirmed the formation of stoichiometric Bi2S3. Dynamic light scattering (DLS) studies show a clear increase in hydrodynamic diameter for samples made with increasing PVP concentration. Particle size obtained from DLS and XRD (using Scherrer's formula) combine with change in full width half maxima of Raman modes collectively suggest overall improvement in crystallinity and quality of product on introducing PVP. In zeta potential (ζ) measurement, steric hindrance of carbon chains plays very crucial role and a systematic reduction of ζ value is observed for samples made with decreasing PVP concentration. An isoelectric point is obtained for sample made with low PVP (1g). Present results are likely to open a window for its medical and catalytic applications.

  13. Improving the Efficiency of a Coagulation-Flocculation Wastewater Treatment of the Semiconductor Industry through Zeta Potential Measurements

    Directory of Open Access Journals (Sweden)

    Eduardo Alberto López-Maldonado

    2014-01-01

    Full Text Available Efficiency of coagulation-flocculation process used for semiconductor wastewater treatment was improved by selecting suitable conditions (pH, polyelectrolyte type, and concentration through zeta potential measurements. Under this scenario the zeta potential, ζ, is the right parameter that allows studying and predicting the interactions at the molecular level between the contaminants in the wastewater and polyelectrolytes used for coagulation-flocculation. Additionally, this parameter is a key factor for assessing the efficiency of coagulation-flocculation processes based on the optimum dosages and windows for polyelectrolytes coagulation-flocculation effectiveness. In this paper, strategic pH variations allowed the prediction of the dosage of polyelectrolyte on wastewater from real electroplating baths, including the isoelectric point (IEP of the dispersions of water and commercial polyelectrolytes used in typical semiconductor industries. The results showed that there is a difference between polyelectrolyte demand required for the removal of suspended solids, turbidity, and organic matter from wastewater (23.4 mg/L and 67 mg/L, resp.. It was also concluded that the dose of polyelectrolytes and coagulation-flocculation window to achieve compliance with national and international regulations as EPA in USA and SEMARNAT in Mexico is influenced by the physicochemical characteristics of the dispersions and treatment conditions (pH and polyelectrolyte dosing strategy.

  14. Joule heating effects on electromagnetohydrodynamic flow through a peristaltically induced micro-channel with different zeta potential and wall slip

    Science.gov (United States)

    Ranjit, N. K.; Shit, G. C.

    2017-09-01

    This paper aims to develop a mathematical model for magnetohydrodynamic flow of biofluids through a hydrophobic micro-channel with periodically contracting and expanding walls under the influence of an axially applied electric field. The velocity slip effects have been taken into account at the channel walls by employing different slip lengths due to hydrophobic gating. Different temperature jump factors have also been used to investigate the thermomechanical interactions at the fluid-solid interface. The electromagnetohydrodynamic flow in a microchannel is simplified under the framework of Debye-Hückel linearization approximation. We have derived the closed-form solutions for the linearized dimensionless boundary value problem under the assumptions of long wave length and low Reynolds number. The axial velocity, temperature, pressure distribution, stream function, wall shear stress and the Nusselt number have been appraised for diverse values of the parameters approaching into the problem. Our main focus is to determine the effects of different zeta potential on the axial velocity and temperature distribution under electromagnetic environment. This study puts forward an important observation that the different zeta potential plays an important role in controlling fluid velocity. The study further reveals that the temperature increases significantly with the Joule heating parameter and the Brinkman number (arises due to the dissipation of energy).

  15. Mixtures of latex particles and the surfactant of opposite charge used as interface stabilizers--influence of particle contact angle, zeta potential, flocculation and shear energy.

    Science.gov (United States)

    Deleurence, Rémi; Parneix, Caroline; Monteux, Cécile

    2014-09-28

    We investigate the stabilization of air-water interfaces by mixtures of negatively charged latex particles (sulfate polystyrene) and cationic surfactants (alkyl trimethylammonium bromides). First we report results concerning the binding of surfactant molecules to the latex particles. As the surfactant concentration increases, the charge of the particles reverses, from negative to positive, because CnTAB first binds electrostatically to the latex particles and then through hydrophobic interaction with the monolayer already adsorbed on the particles as well as directly with the hydrophobic surface of the latex. Over a large range of surfactant concentrations around the charge inversion, a strong flocculation is observed and 100 μm large aggregates form in the suspension. Unlike previous studies published on mixtures of inorganic particles with oppositely charged surfactants, we show that we can vary the sign of the zeta potential of the particles without changing the contact angle of the particles over a large range of surfactant concentrations. Indeed, the latex particles that we study are more hydrophobic than inorganic particles, hence adding moderate concentrations of the surfactant results in a weak variation of the contact angle while the charge of the particles can be reversed. This enables decoupling of the effect of zeta potential and contact angle on the interfacial properties of the mixtures. Our study shows that the contact angle and the charge of the particles are not sufficient parameters to control the foam properties, and the key-parameters are the flocculation state and the shear energy applied to produce the foam. Indeed, flocculated samples, whatever the sign of the zeta potential, enable production of a stable armour at the interface. The large aggregates do not adsorb spontaneously at the interface because of their large size, however when a large shear energy is used to produce the foam very stable foam is obtained, where particles are trapped

  16. Biosynthesis and characterization of cadmium sulfide nanoparticles – An emphasis of zeta potential behavior due to capping

    International Nuclear Information System (INIS)

    Sankhla, Aryan; Sharma, Rajeshwar; Yadav, Raghvendra Singh; Kashyap, Diwakar; Kothari, S.L.; Kachhwaha, S.

    2016-01-01

    Biological approaches have been amongst the most promising protocols for synthesis of nanomaterials. In this study, Cadmium sulfide nanoparticles (CdS NPs) were synthesized by incubating their precursor salts with Escherichia coli and zeta potential (ζ-potential) measurement with varying pH was carried out to evaluate stability of the colloidal dispersion. Formation of CdS NPs was studied in synchrony with microbial growth. TEM analysis confirmed the uniform distribution of NPs. Average size (5 ± 0.4 nm) and electron diffraction pattern revealed polycrystalline cubic crystal phase of these nanoparticles. X-ray diffractogram ascertained the formation of CdS nanoparticles with phase formation and particle size distribution in accordance with the particle size obtained from TEM. Absorption edge of biosynthesized CdS NPs showed a blue shift at ∼400 nm in comparison to their bulk counterpart. A hump at 279 nm indicated presence of biomolecules in the solution in addition to the particles. FT-IR spectrum of capped CdS NPs showed peaks of protein. This confirms adsorption of protein molecules on nanoparticle surface. They act as a capping agent hence responsible for the stability of NPs. The enhanced stability of the particles was confirmed by Zeta potential analysis. The presence of charge on the surface of capped CdS NPs gave a detail understanding of dispersion mechanism and colloidal stability at the NP interface. This stability study of biosynthesized semiconductor nanoparticles utilizing microbial cells had not been done in the past by any research group providing an impetus for the same. Surface area of capped CdS NPs and bare CdS NPs were found to be 298 ± 2.65 m 2 /g and 117 ± 2.41 m 2 /g respectively. A possible mechanism is also proposed for the biosynthesis of CdS NPs. - Highlights: • Synthesis of CdS NPs utilizing reproducible molecular machinery viz. Escherichia coli biomass. • Uniform and Polydispersed NPs with high surface area and

  17. Biosynthesis and characterization of cadmium sulfide nanoparticles – An emphasis of zeta potential behavior due to capping

    Energy Technology Data Exchange (ETDEWEB)

    Sankhla, Aryan, E-mail: aaryansankhla@gmail.com [Centre for Converging Technologies, University of Rajasthan, Jaipur, 302015 (India); Sharma, Rajeshwar; Yadav, Raghvendra Singh [Centre for Converging Technologies, University of Rajasthan, Jaipur, 302015 (India); Kashyap, Diwakar [Department of Biological Chemistry, Ariel University, Ariel, 40700 (Israel); Kothari, S.L. [Institute of Biotechnology, Amity University, Jaipur, 303002 (India); Kachhwaha, S. [Department of Botany, University of Rajasthan, Jaipur, 302004 (India)

    2016-02-15

    Biological approaches have been amongst the most promising protocols for synthesis of nanomaterials. In this study, Cadmium sulfide nanoparticles (CdS NPs) were synthesized by incubating their precursor salts with Escherichia coli and zeta potential (ζ-potential) measurement with varying pH was carried out to evaluate stability of the colloidal dispersion. Formation of CdS NPs was studied in synchrony with microbial growth. TEM analysis confirmed the uniform distribution of NPs. Average size (5 ± 0.4 nm) and electron diffraction pattern revealed polycrystalline cubic crystal phase of these nanoparticles. X-ray diffractogram ascertained the formation of CdS nanoparticles with phase formation and particle size distribution in accordance with the particle size obtained from TEM. Absorption edge of biosynthesized CdS NPs showed a blue shift at ∼400 nm in comparison to their bulk counterpart. A hump at 279 nm indicated presence of biomolecules in the solution in addition to the particles. FT-IR spectrum of capped CdS NPs showed peaks of protein. This confirms adsorption of protein molecules on nanoparticle surface. They act as a capping agent hence responsible for the stability of NPs. The enhanced stability of the particles was confirmed by Zeta potential analysis. The presence of charge on the surface of capped CdS NPs gave a detail understanding of dispersion mechanism and colloidal stability at the NP interface. This stability study of biosynthesized semiconductor nanoparticles utilizing microbial cells had not been done in the past by any research group providing an impetus for the same. Surface area of capped CdS NPs and bare CdS NPs were found to be 298 ± 2.65 m{sup 2}/g and 117 ± 2.41 m{sup 2}/g respectively. A possible mechanism is also proposed for the biosynthesis of CdS NPs. - Highlights: • Synthesis of CdS NPs utilizing reproducible molecular machinery viz. Escherichia coli biomass. • Uniform and Polydispersed NPs with high surface area

  18. Adsorbed polymers in aqueous media. The relation between zeta-potential, layer thickness and ionic strength

    NARCIS (Netherlands)

    Cohen Stuart, M.A.; Mulder, J.W.

    1985-01-01

    Streaming potentials for glass capillaries with and without adsorbed poly(vinyl pyrrolidone) were used to determine the thickness of the adsorbed polymer layer. It was found that the thickness determined in this way is a strong function of the ionic strength of the solution. The results are compared

  19. Effect of hydrodynamic slippage on electro-osmotic flow in zeta potential patterned nanochannels

    Energy Technology Data Exchange (ETDEWEB)

    Datta, S; Choudhary, J N, E-mail: subhra-datta@iitd.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India)

    2013-10-01

    The effect of hydrodynamic slippage on the electro-osmotic flow in a nanochannel with thick electrical double layers whose wall surface potential has a periodic axial variation is studied. The equations of Stokes flow are solved exactly with the help of the Navier slip boundary condition and the Debye-Huckel linearization of the equation governing the potential of the electrical double layer. Each periodic cell of the flow field consists of four counter-rotating vortices. The cross-channel profile of the axial velocity at the center of the cell exhibits three extrema and a reversed velocity zone near the channel axis of symmetry. The size of the extrema and that of the reversed velocity zone increases with increase in the degree of slippage. In the limit when the wavelength of axial variation in surface potential is much larger than the channel width, the flow characteristics are interpreted in terms of the lubrication approximation. In the limit when the electrical double layer is much thinner than the channel height, the effect of slip is modeled by a Helmholtz-Smoluchowski apparent slip boundary condition that depends on the pattern wavelength. (paper)

  20. Effect of Tannic Acid on the zeta Potential, Sorption, and Surface Free Energy in the Process of Dyeing of Leacril with a Cationic Dye.

    Science.gov (United States)

    Espinosa-Jiménez; Giménez-Martín; Ontiveros-Ortega

    1998-11-01

    The behavior of the surface free energy in the process of dyeing Leacril pretreated with tannic acid and subsequently dyeing with the cationic dye Rhodamine B has been studied. Also the electrokinetic behavior of these systems has been analyzed by studying the zeta potential, which has been obtained by means of the streaming potential technique. Values more significative of the zeta potential of these systems have been obtained using the three models of capillaries existing in the literature. The qualitative behavior of the zeta potential is the same for the three models of capillaries tested in this paper. These models are those of Goring and Mason, Biefer and Mason, and Chang and Robertson. The zeta potential of the systems analyzed is negative in the range of concentration of the dye in the liquid phase from 10(-6) to ca. 10(-4) M of dye. In the range of low concentrations (from 10(-6) to ca. 10(-5) M of dye) the zeta potential of the system untreated Leacril/Rhodamine B increases in absolute value due to increasing hydrophobic attractions between both the hydrophobic chains of the dye and the Leacril fibers in aqueous media. In the system Leacril treated with tannic acid/Rhodamine B, this increase is also due to the presence of hydrogen bonding between the phenolic hydroxyl groups of the tannic acid and the sulfonate and sulfate end groups of Leacril fibers. For concentrations of dye between 10(-5) and 10(-4) M of dye in solution, the zeta potential decreases in absolute value due to the electrostatic attractions between the groups negatively charged in the fiber and the cation of the dye. The zeta potential changes its sign at the highest concentrations of dye used in this work. The adsorption of Rhodamine B onto both untreated Leacril and Leacril treated with tannic acid is favored by the increasing temperature of adsorption. The behavior of the components of the surface free energy obtained by the thin-layer wicking technique led us to consider that the

  1. Determination of zeta-potential, charge, and number of organic ligands on the surface of water soluble quantum dots by capillary electrophoresis

    Czech Academy of Sciences Publication Activity Database

    Voráčová, Ivona; Klepárník, Karel; Lišková, Marcela; Foret, František

    2015-01-01

    Roč. 36, č. 6 (2015), s. 867-874 ISSN 0173-0835 R&D Projects: GA ČR(CZ) GA14-28254S Institutional support: RVO:68081715 Keywords : CE * LIF * zeta-potential * quantum dots Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.482, year: 2015

  2. Rheology and zeta potential of cement pastes containing calcined silt and ground granulated blast-furnace slag

    Directory of Open Access Journals (Sweden)

    Safi, B.

    2011-09-01

    Full Text Available This study aimed to analyse the re-use of dam silt as a supplementary binder for self-compacting concrete (SCC. When burnt, silt becomes more reactive because the kaolin it contains is converted into metakaolin. Portland cement, calcined or burnt silt and ground granulated blast furnace slag were used in this research. Cement pastes were prepared with blends containing two or three of these materials. The replacement ratio for burnt silt in both cases was 10 % and 20 % by cement weight and the ratio for the slag was a constant 30 % by weight of the blend. Rheological and zeta potential tests were conducted to evaluate paste electrokinetics and rheological behaviour. The findings showed that burnt silt is apt for use as an addition to cement for SCC manufacture.

    En el presente trabajo se ha analizado la posibilidad de utilizar los lodos procedentes de embalses como adición en la fabricación del hormigón autocompactante (HAC. Con la calcinación, estos materiales se vuelven más reactivos debido a la transformación en metacaolín, del caolín que forma parte de su composición. Las materias primas empleadas en esta investigación son: cemento Pórtland, lodos de embalse calcinados y escorias granuladas de horno alto. Se prepararon pastas de cemento con mezclas que contenían dos o tres de estos materiales. El porcentaje de reemplazo de los lodos calcinados osciló entre el 10 y el 20 % en peso del cemento, mientras que el de la escoria fue del 30 % en peso de la mezcla. Se llevaron a cabo ensayos reológicos y de potencial zeta para evaluar el comportamiento electrocinético y reológico de las distintas pastas. De acuerdo con los resultados obtenidos, una vez calcinados, los lodos de embalse son aprovechables como adición al cemento con destino a la preparación de HAC.

  3. The effect of the electrical double layer on hydrodynamic lubrication: a non-monotonic trend with increasing zeta potential

    Directory of Open Access Journals (Sweden)

    Dalei Jing

    2017-07-01

    Full Text Available In the present study, a modified Reynolds equation including the electrical double layer (EDL-induced electroviscous effect of lubricant is established to investigate the effect of the EDL on the hydrodynamic lubrication of a 1D slider bearing. The theoretical model is based on the nonlinear Poisson–Boltzmann equation without the use of the Debye–Hückel approximation. Furthermore, the variation in the bulk electrical conductivity of the lubricant under the influence of the EDL is also considered during the theoretical analysis of hydrodynamic lubrication. The results show that the EDL can increase the hydrodynamic load capacity of the lubricant in a 1D slider bearing. More importantly, the hydrodynamic load capacity of the lubricant under the influence of the EDL shows a non-monotonic trend, changing from enhancement to attenuation with a gradual increase in the absolute value of the zeta potential. This non-monotonic hydrodynamic lubrication is dependent on the non-monotonic electroviscous effect of the lubricant generated by the EDL, which is dominated by the non-monotonic electrical field strength and non-monotonic electrical body force on the lubricant. The subject of the paper is the theoretical modeling and the corresponding analysis.

  4. Electroosmotic flow in a rectangular channel with variable wall zeta-potential: comparison of numerical simulation with asymptotic theory.

    Science.gov (United States)

    Datta, Subhra; Ghosal, Sandip; Patankar, Neelesh A

    2006-02-01

    Electroosmotic flow in a straight micro-channel of rectangular cross-section is computed numerically for several situations where the wall zeta-potential is not constant but has a specified spatial variation. The results of the computation are compared with an earlier published asymptotic theory based on the lubrication approximation: the assumption that any axial variations take place on a long length scale compared to a characteristic channel width. The computational results are found to be in excellent agreement with the theory even when the scale of axial variations is comparable to the channel width. In the opposite limit when the wavelength of fluctuations is much shorter than the channel width, the lubrication theory fails to describe the solution either qualitatively or quantitatively. In this short wave limit the solution is well described by Ajdari's theory for electroosmotic flow between infinite parallel plates (Ajdari, A., Phys. Rev. E 1996, 53, 4996-5005.) The infinitely thin electric double layer limit is assumed in the theory as well as in the simulation.

  5. An application of zeta potential method for the selection of nano-fluids to enhance IVR capability

    International Nuclear Information System (INIS)

    Pham Quynh Trang; Kim, Tae Il; Chang, Soon Heung

    2009-01-01

    In-vessel Retention (IVR) is one of the key severe accident management strategies that have been applied currently for advanced light water reactors such as APR1000 or APR1400. The concept of IVR consists of external cooling of the reactor vessel by flooding the reactor cavity to remove the decay heat from the molten core through the lower head of the vessel. However, the heat removal process is limited by the occurrence of critical heat flux (CHF) at the reactor vessel outer surface that may lead to a sharp increase of local temperature, damaging the integrity of the reactor vessel. In order to obtain higher power of nuclear reactors and to assure the achievement of the IVR capability during accident conditions, an enhancement of CHF at the outer surface of the vessel is required. The potential use of nano-fluids to increase the CHF is among the main IVR enhancing approaches. In this study, Al 2 O 3 and CNT nano-fluids with different concentrations have been used as the potential coolant to enhance IVR capabilities. The dispersion stability of the nano-fluids was verified by zeta potential measurements. The results showed effects of time, concentration and pH on the stability of nanofluids. Three types of nano-fluids were selected as the candidates to apply for the IVR. A series of experiments have been performed in this study to understand the pool-boiling critical heat flux behavior on downward facing surfaces submerged in a pool of nano-fluids at very low concentration. The inclination angle was changed from horizontal to vertical to investigate the effect of orientation on CHF enhancement which is needed for the application in IVR

  6. Unfolding of hemoglobin variants--insights from urea gradient gel electrophoresis photon correlation spectroscopy and zeta potential measurements

    International Nuclear Information System (INIS)

    Bhattacharya, Jaydeep; GhoshMoulick, Ranjita; Choudhuri, Utpal; Chakrabarty, Prantar; Bhattacharya, Pranab K.; Lahiri, Prabir; Chakraborti, Bikas; Dasgupta, Anjan Kr.

    2004-01-01

    The unfolding pattern of crystal human hemoglobin and variants of hemoglobin obtained from hemolysate were studied using transverse urea gradient gel electrophoresis (TUGGE). A smooth sigmoid like increase of electrophoretic mobility was observed with increasing urea concentrations. A decrease in electrophoretic mobility resulted, if the protein was unfolded with guanidium hydrochloride (GdnHCl). The anomaly was resolved after the Stoke's radii (obtained using the photon correlation spectroscopy) and zeta potential (measured using laser Doppler velocimetry) measurements were made at different denaturant concentrations. Addition of denaturant led to formation of extended structure, irrespective of the nature of the denaturant, as indicated by increase in Stoke's radii in both cases (urea and GdnHCl). The unexpected increase in electrophoretic mobility in case of urea could be explained in terms of a critical redistribution of negative charge at intermediate stages of the unfolding process. In case of GdnHCl, the higher ionic strength masked the charge effect. The mobility, being solely dependent on size, decreased at higher denaturant concentration. Incidentally, folding loci of other hemoglobin variants (e.g. HbE) or that of post-translationally modified hemoglobin (e.g. HbA1c) could be determined by studying the charge distribution and hydrodynamic radius at varying denaturing stress and in each case the gel migration profile could be approximately scaled by the ratio of charge and hydrodynamic diameter of the protein. While unfolding induced charge effect was most pronounced in HbA0 (and crystal ferrous hemoglobin), the unfolding induced aggregation (manifested by the increase in Stoke's radii) was predominantly observed in the variant forms HbE and HbA1c. Representing the proteins by a plot, in which charge and hydrodynamic diameter are on independent axes, may be a useful way of characterizing protein variants having similar migration profiles on native gels

  7. Unfolding of hemoglobin variants--insights from urea gradient gel electrophoresis photon correlation spectroscopy and zeta potential measurements

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Jaydeep; GhoshMoulick, Ranjita; Choudhuri, Utpal; Chakrabarty, Prantar; Bhattacharya, Pranab K.; Lahiri, Prabir; Chakraborti, Bikas; Dasgupta, Anjan Kr

    2004-09-27

    The unfolding pattern of crystal human hemoglobin and variants of hemoglobin obtained from hemolysate were studied using transverse urea gradient gel electrophoresis (TUGGE). A smooth sigmoid like increase of electrophoretic mobility was observed with increasing urea concentrations. A decrease in electrophoretic mobility resulted, if the protein was unfolded with guanidium hydrochloride (GdnHCl). The anomaly was resolved after the Stoke's radii (obtained using the photon correlation spectroscopy) and zeta potential (measured using laser Doppler velocimetry) measurements were made at different denaturant concentrations. Addition of denaturant led to formation of extended structure, irrespective of the nature of the denaturant, as indicated by increase in Stoke's radii in both cases (urea and GdnHCl). The unexpected increase in electrophoretic mobility in case of urea could be explained in terms of a critical redistribution of negative charge at intermediate stages of the unfolding process. In case of GdnHCl, the higher ionic strength masked the charge effect. The mobility, being solely dependent on size, decreased at higher denaturant concentration. Incidentally, folding loci of other hemoglobin variants (e.g. HbE) or that of post-translationally modified hemoglobin (e.g. HbA1c) could be determined by studying the charge distribution and hydrodynamic radius at varying denaturing stress and in each case the gel migration profile could be approximately scaled by the ratio of charge and hydrodynamic diameter of the protein. While unfolding induced charge effect was most pronounced in HbA0 (and crystal ferrous hemoglobin), the unfolding induced aggregation (manifested by the increase in Stoke's radii) was predominantly observed in the variant forms HbE and HbA1c. Representing the proteins by a plot, in which charge and hydrodynamic diameter are on independent axes, may be a useful way of characterizing protein variants having similar migration profiles on

  8. Zeta-potential data reliability of gold nanoparticle biomolecular conjugates and its application in sensitive quantification of surface absorbed protein.

    Science.gov (United States)

    Wang, Wenjie; Ding, Xiaofan; Xu, Qing; Wang, Jing; Wang, Lei; Lou, Xinhui

    2016-12-01

    Zeta potentials (ZP) of gold nanoparticle bioconjugates (AuNP-bios) provide important information on surface charge that is critical for many applications including drug delivery, biosensing, and cell imaging. The ZP measurements (ZPMs) are conducted under an alternative electrical field at a high frequency under laser irradiation, which may strongly affect the status of surface coating of AuNP-bios and generate unreliable data. In this study, we systemically evaluated the ZP data reliability (ZPDR) of citrate-, thiolated single stranded DNA-, and protein-coated AuNPs mainly according to the consistence of ZPs in the repeated ZPMs and the changes of the hydrodynamic size before and after the ZPMs. We found that the ZPDR was highly dependent on both buffer conditions and surface modifications. Overall, the higher ionic strength of the buffer and the lower affinity of surface bounders were related with the worse ZPDR. The ZPDR of citrate-coated AuNP was good in water, but bad in 10mM phosphate buffer (PB), showing substantially decrease of the absolute ZP values after each measurement, probably due to the electrical field facilitated adsorption of negatively charged phosphate ions on AuNPs. The significant desorption of DNAs from AuNP was observed in the PB containing medium concentration of NaCl, but not in PB. The excellent ZPDR of bovine serum albumin (BSA)-coated AuNP was observed at high salt concentrations and low surface coverage, enabling ZPM as an ultra-sensitive tool for protein quantification on the surface of AuNPs with a single molecule resolution. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Cell surface groups of two picocyanobacteria strains studied by zeta potential investigations, potentiometric titration, and infrared spectroscopy.

    Science.gov (United States)

    Dittrich, Maria; Sibler, Sabine

    2005-06-15

    In order to clarify the role of picocyanobacteria in aquatic biogeochemical processes (e.g., calcite precipitation), cell surface properties need to be investigated. An experimental study of the cell surface characteristics of two Synechococcus-type unicellular autotrophic picocyanobacterial strains was carried out. One strain was isolated from Lake Plon and contained phycocyanin, the other strain came from Lago Maggiore and was rich in phycoerythrin. Potentiometric titrations were conducted to determine the different types of sites present on the bacteria cell walls. Infrared spectroscopy allowed characterization of the various functional groups (RNH(2), RCOOH, ROH, RPO(2)) and investigations of zeta potential provided insight into the isoelectrical points of the strains. Titrations reveal three distinct sites on the bacterial surfaces of phycocyanin- and phycoerythrin-rich strains with pK values of 4.8+/-0.3/5.0+/-0.2, 6.6+/-0.2/6.7+/-0.4, and 8.8+/-0.1/8.7+/-0.2, corresponding to carboxyl, phosphate, and amine groups with surface densities of 2.6+/-0.4/7.4+/-1.6 x 10(-4), 1.9+/-0.5/4.4+/-0.8 x 10(-4), and 2.5+/-0.4/4.8+/-0.7 x 10(-4) mol/g of dry bacteria. The deprotonation constants are similar to those of bacterial strains and site densities are also within an order of magnitude of other strains. The phycoerythrin-rich strain had a higher number of binding sites than the phycocyanin-rich strain. The results showed that picocyanobacteria may adsorb either calcium cations or carbonate anions and therefore strongly influence the biogeochemical cycling of calcite in pelagic systems.

  10. Evaluating Zeta Potential and the Calcite/Aragonite Ratio as Potential Success Indicators for Magnetic Water Treatment

    National Research Council Canada - National Science Library

    Lambert, Kevin

    1999-01-01

    The potential benefits of anti-scale magnetic treatment (AMT) are not realized or reliably predicted because the factors measuring performance of magnetic treatment have either not been identified or are poorly defined...

  11. Multireference configuration interaction treatment of potential energy surfaces: symmetric dissociation of H/sub 2/O in a double-zeta basis

    Energy Technology Data Exchange (ETDEWEB)

    Brown, F B; Shavitt, I; Shepard, R

    1984-03-23

    Multiconfiguration self-consistent fields (SCF) and multireference configurational interaction (CI) calculations have been performed for the H/sub 2/O molecule in a double-zeta basis for four symmetric geometries, for comparison with full CI results. Unlike single-reference results, the energy errors are almost independent of geometry, allowing unbiased treatments of potential energy surfaces. 35 references, 1 figure, 2 tables.

  12. Comparison of methods of zeta potential and residual turbidity of pectin solutions using calcium sulphate/aluminium sulphate as a precipitant

    Directory of Open Access Journals (Sweden)

    Kuljanin Tatjana A.

    2017-01-01

    Full Text Available The affinity of calcium ion binding from CaO used in the most common process of purification of sugar beet juice is relatively low. Therefore, large amounts of this compound are required. This paper presents the theoretical basis of a novel sugar beet juice purification method based on the application of the binary system CaSO4/Al2(SO4 . In order to monitor the process of coagulation and precipitation of pectin in the presence of CaSO4/Al2(SO43, two methods were compared: measurement of the zeta potential and of residual solution turbidity. The zeta potential of pectin solution was determined by electrophoretic method, while the residual turbidity was determined by spectrophotometry. Two model solutions of pectin (0.1 % w/w were investigated. Studies were performed with 10 different concentrations of the binary solution CaSO4/Al2(SO43 (50 - 500 g dm-3. The amount of the precipitant CaSO4/Al2(SO43 (1:1 w/w needed to achieve the minimum solution turbidity and charge neutralization of pectin particles (zero zeta potential were measured and compared. Colloidal destabilization occurred before a complete neutralization of the surface charge of pectin particles (zeta potential ~ 0 mV. Optimal quantities (490 - 705 mg g-1 pectin of the applied binary mixture, were obtained using both methods. This is much lower than the amount of CaO that is commonly used in the conventional process of sugar beet juice purification (about 9 g• g-1 pectin. The use of these precipitants could be important from both economic and environmental point of view. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 31055

  13. Design and assembly of ternary Pt/Re/SnO2 NPs by controlling the zeta potential of individual Pt, Re, and SnO2 NPs

    Science.gov (United States)

    Drzymała, Elżbieta; Gruzeł, Grzegorz; Pajor-Świerzy, Anna; Depciuch, Joanna; Socha, Robert; Kowal, Andrzej; Warszyński, Piotr; Parlinska-Wojtan, Magdalena

    2018-05-01

    In this study Pt, Re, and SnO2 nanoparticles (NPs) were combined in a controlled manner into binary and ternary combinations for a possible application for ethanol oxidation. For this purpose, zeta potentials as a function of the pH of the individual NPs solutions were measured. In order to successfully combine the NPs into Pt/SnO2 and Re/SnO2 NPs, the solutions were mixed together at a pH guaranteeing opposite zeta potentials of the metal and oxide NPs. The individually synthesized NPs and their binary/ternary combinations were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDS) analysis. FTIR and XPS spectroscopy showed that the individually synthesized Pt and Re NPs are metallic and the Sn component was oxidized to SnO2. STEM showed that all NPs are well crystallized and the sizes of the Pt, Re, and SnO2 NPs were 2.2, 1.0, and 3.4 nm, respectively. Moreover, EDS analysis confirmed the successful formation of binary Pt/SnO2 and Re/SnO2 NP, as well as ternary Pt/Re/SnO2 NP combinations. This study shows that by controlling the zeta potential of individual metal and oxide NPs, it is possible to assemble them into binary and ternary combinations. [Figure not available: see fulltext.

  14. Generation of nanobubbles by ceramic membrane filters: The dependence of bubble size and zeta potential on surface coating, pore size and injected gas pressure.

    Science.gov (United States)

    Ahmed, Ahmed Khaled Abdella; Sun, Cuizhen; Hua, Likun; Zhang, Zhibin; Zhang, Yanhao; Zhang, Wen; Marhaba, Taha

    2018-07-01

    Generation of gaseous nanobubbles (NBs) by simple, efficient, and scalable methods is critical for industrialization and applications of nanobubbles. Traditional generation methods mainly rely on hydrodynamic, acoustic, particle, and optical cavitation. These generation processes render issues such as high energy consumption, non-flexibility, and complexity. This research investigated the use of tubular ceramic nanofiltration membranes to generate NBs in water with air, nitrogen and oxygen gases. This system injects pressurized gases through a tubular ceramic membrane with nanopores to create NBs. The effects of membrane pores size, surface energy, and the injected gas pressures on the bubble size and zeta potential were examined. The results show that the gas injection pressure had considerable effects on the bubble size, zeta potential, pH, and dissolved oxygen of the produced NBs. For example, increasing the injection air pressure from 69 kPa to 414 kPa, the air bubble size was reduced from 600 to 340 nm respectively. Membrane pores size and surface energy also had significant effects on sizes and zeta potentials of NBs. The results presented here aim to fill out the gaps of fundamental knowledge about NBs and development of efficient generation methods. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Interaction between ropinirole hydrochloride and aspirin with human serum albumin as binary and ternary systems by multi-spectroscopic, molecular modeling and zeta potential

    International Nuclear Information System (INIS)

    Mahaki, Hanie; Memarpoor-Yazdi, Mina; Chamani, Jamshidkhan; Reza Saberi, Mohammad

    2013-01-01

    The aim of the present study was to describe the competition of ropinirole hydrochloride (RP) and aspirin (ASA) in binding to human serum albumin (HSA) in physiological buffer (pH=7.4) using multi-spectroscopic, molecular modeling and zeta-potential measurements. Fluorescence analysis was used to define the binding and quenching properties of drug-HSA complexes in binary and ternary systems. Fluorescence spectroscopy showed that in the presence of RP, the binding constant of HSA–ASA was increased. Static quenching was confirmed to result in the fluorescence quenching and FRET. The effect of drugs on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy, three-dimensional fluorescence spectra and circular dichroism (CD). The RLS method determined the critical aggregation concentration of drugs on HSA in binary and ternary systems that confirmed the zeta potential results. Structural modeling showed that the affinity of each of the drugs to HSA in binary and ternary systems confirms the spectroscopic results. - Highlights: ► We studied the interaction of ropinirole hydrochloride and aspirin with HSA. ► Molecular modeling and zeta-potential used to describe competitive interaction. ► We determined the critical induced aggregation concentration of both drugs on HSA. ► The binding mechanism of drugs as separate and simultaneous to HSA has been compared. ► The binding site of both drugs as simultaneous effects on HSA has been determined.

  16. Interaction between ropinirole hydrochloride and aspirin with human serum albumin as binary and ternary systems by multi-spectroscopic, molecular modeling and zeta potential

    Energy Technology Data Exchange (ETDEWEB)

    Mahaki, Hanie, E-mail: hanieh.mahaki@gmail.com [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Memarpoor-Yazdi, Mina; Chamani, Jamshidkhan [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Reza Saberi, Mohammad [Medical Chemistry Department, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of)

    2013-02-15

    The aim of the present study was to describe the competition of ropinirole hydrochloride (RP) and aspirin (ASA) in binding to human serum albumin (HSA) in physiological buffer (pH=7.4) using multi-spectroscopic, molecular modeling and zeta-potential measurements. Fluorescence analysis was used to define the binding and quenching properties of drug-HSA complexes in binary and ternary systems. Fluorescence spectroscopy showed that in the presence of RP, the binding constant of HSA-ASA was increased. Static quenching was confirmed to result in the fluorescence quenching and FRET. The effect of drugs on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy, three-dimensional fluorescence spectra and circular dichroism (CD). The RLS method determined the critical aggregation concentration of drugs on HSA in binary and ternary systems that confirmed the zeta potential results. Structural modeling showed that the affinity of each of the drugs to HSA in binary and ternary systems confirms the spectroscopic results. - Highlights: Black-Right-Pointing-Pointer We studied the interaction of ropinirole hydrochloride and aspirin with HSA. Black-Right-Pointing-Pointer Molecular modeling and zeta-potential used to describe competitive interaction. Black-Right-Pointing-Pointer We determined the critical induced aggregation concentration of both drugs on HSA. Black-Right-Pointing-Pointer The binding mechanism of drugs as separate and simultaneous to HSA has been compared. Black-Right-Pointing-Pointer The binding site of both drugs as simultaneous effects on HSA has been determined.

  17. Interpretation of colloidal dyeing of polyester fabrics pretreated with ethyl xanthogenate in terms of zeta potential and surface free energy balance.

    Science.gov (United States)

    Espinosa-Jiménez, M; Padilla-Weigand, R; Ontiveros-Ortega, A; Ramos-Tejada, M M; Perea-Carpio, R

    2003-09-15

    Data are presented on the adsorption of the colloidal dye Disperse Blue 3 onto polyester fabric (Dacron 54, Stile 777), the fabric being pretreated with different amounts of the surfactant potassium ethyl xanthogenate (PEX). This study has been made by means of both the evolution of the zeta potential of the fiber/dye interface and the behaviour of the surface free energy components of the above systems. The kinetics of adsorption of the process of dyeing, using 10(-4) M of PEX in the pretreatment of the fabric, shows that increasing temperature of adsorption decrease the amount of colloidal dye adsorbed onto the fabric. This fact shows that the principal mechanism involved in this adsorption process is physical in nature. The adsorption isotherms of the colloidal dye onto polyester pretreated with different amounts of PEX, shows that the adsorption of the dye is favored with the increase in the concentration of the surfactant used in the pretreatment. This fact shows that the pretreatment with PEX is a very interesting aspect of interest in textile industry. The zeta potential of the system fabric/surfactant shows that this parameter is negative (about -25 mV) for the untreated fiber and decreases in absolute value for increasing concentration of the surfactant on the fiber, the value of the zeta potential of the system being -5 mV for 10(-2) M of PEX. This behavior can be explained for the chemical reaction nucleophilic attack between the carboxyl groups of polyester, ionized at pH 8, and the thiocarbonyl group of the xanthogenate ion. On the other hand, the zeta potential of the system polyester pretreated with PEX/Disperse Blue 3 at increasing concentrations of the surfactant and the dye shows that this parameter increases its negative value strongly with increasing concentration of the surfactant used in the treatment. This can be explained for the hydrogen bonds between the hydroxy groups of the dye and the S- ions of the thiocarbonyl group of the surfactant

  18. Characterization of the startup transient electrokinetic flow in rectangular channels of arbitrary dimensions, zeta potential distribution, and time-varying pressure gradient.

    Science.gov (United States)

    Miller, Andrew; Villegas, Arturo; Diez, F Javier

    2015-03-01

    The solution to the startup transient EOF in an arbitrary rectangular microchannel is derived analytically and validated experimentally. This full 2D transient solution describes the evolution of the flow through five distinct periods until reaching a final steady state. The derived analytical velocity solution is validated experimentally for different channel sizes and aspect ratios under time-varying pressure gradients. The experiments used a time resolved micro particle image velocimetry technique to calculate the startup transient velocity profiles. The measurements captured the effect of time-varying pressure gradient fields derived in the analytical solutions. This is tested by using small reservoirs at both ends of the channel which allowed a time-varying pressure gradient to develop with a time scale on the order of the transient EOF. Results showed that under these common conditions, the effect of the pressure build up in the reservoirs on the temporal development of the transient startup EOF in the channels cannot be neglected. The measurements also captured the analytical predictions for channel walls made of different materials (i.e., zeta potentials). This was tested in channels that had three PDMS and one quartz wall, resulting in a flow with an asymmetric velocity profile due to variations in the zeta potential between the walls. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Use of Spectroscopic, Zeta Potential and Molecular Dynamic Techniques to Study the Interaction between Human Holo-Transferrin and Two Antagonist Drugs: Comparison of Binary and Ternary Systems

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Saberi

    2012-03-01

    Full Text Available For the first time, the binding of ropinirole hydrochloride (ROP and aspirin (ASA to human holo-transferrin (hTf has been investigated by spectroscopic approaches (fluorescence quenching, synchronous fluorescence, time-resolved fluorescence, three-dimensional fluorescence, UV-vis absorption, circular dichroism, resonance light scattering, as well as zeta potential and molecular modeling techniques, under simulated physiological conditions. Fluorescence analysis was used to estimate the effect of the ROP and ASA drugs on the fluorescence of hTf as well as to define the binding and quenching properties of binary and ternary complexes. The synchronized fluorescence and three-dimensional fluorescence spectra demonstrated some micro-environmental and conformational changes around the Trp and Tyr residues with a faint red shift. Thermodynamic analysis displayed the van der Waals forces and hydrogen bonds interactions are the major acting forces in stabilizing the complexes. Steady-state and time-resolved fluorescence data revealed that the fluorescence quenching of complexes are static mechanism. The effect of the drugs aggregating on the hTf resulted in an enhancement of the resonance light scattering (RLS intensity. The average binding distance between were computed according to the forster non-radiation energy transfer theory. The circular dichroism (CD spectral examinations indicated that the binding of the drugs induced a conformational change of hTf. Measurements of the zeta potential indicated that the combination of electrostatic and hydrophobic interactions between ROP, ASA and hTf formed micelle-like clusters. The molecular modeling confirmed the experimental results. This study is expected to provide important insight into the interaction of hTf with ROP and ASA to use in various toxicological and therapeutic processes.

  20. Riemann zeta function from wave-packet dynamics

    DEFF Research Database (Denmark)

    Mack, R.; Dahl, Jens Peder; Moya-Cessa, H.

    2010-01-01

    We show that the time evolution of a thermal phase state of an anharmonic oscillator with logarithmic energy spectrum is intimately connected to the generalized Riemann zeta function zeta(s, a). Indeed, the autocorrelation function at a time t is determined by zeta (sigma + i tau, a), where sigma...... index of JWKB. We compare and contrast exact and approximate eigenvalues of purely logarithmic potentials. Moreover, we use a numerical method to find a potential which leads to exact logarithmic eigenvalues. We discuss possible realizations of Riemann zeta wave-packet dynamics using cold atoms...

  1. Stability Investigation of Ligand-Exchanged CdSe/ZnS-Y (Y = 3-Mercaptopropionic Acid or Mercaptosuccinic Acid through Zeta Potential Measurements

    Directory of Open Access Journals (Sweden)

    Ngoc Thuy Vo

    2016-01-01

    Full Text Available Quantum dots have been considered to be promising candidates for bioapplications because of their high sensitivity, rapid response, and reliability. The synthesis of high-quality quantum dots that can be dissolved in water and other biological media is a crucial step toward their further application in biology. Starting with a one-pot reaction and the successive ionic layer adsorption and reaction (SILAR method, we produced the CdSe/ZnS core/shell structure. Through a ligand-exchange mechanism, we coated the as-made CdSe/ZnS structure with 3-mercaptopropionic acid (MPA or mercaptosuccinic acid (MSA. Various techniques, including photoluminescence (PL, ultraviolet-visible (UV-Vis spectroscopy, transmission electron microscopy (TEM, X-ray diffraction (XRD, and Fourier transform infrared (FTIR spectroscopy, were utilized to characterize the ligand-coated CdSe/ZnS structure. The results show enhanced luminescence intensity, CdSe surface passivation by ZnS, and successful coating with MPA and MSA. The stability of quantum dots in solutions with different pH values was investigated by performing zeta potential measurements. The results revealed that the quantum dots shifted from displaying hydrophobic to hydrophilic behavior and could be connected with bioagents.

  2. The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO2 nanostructures of different shapes

    International Nuclear Information System (INIS)

    Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali

    2013-01-01

    Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO 2 catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na 2 Ti 2 O 5 ·H 2 O) particles (W = 9–12 nm and L = 82–115 nm) and rice like pure anatase-TNR particles (W = 8–13 nm and L = 81–134 nm) are obtained by the hydrothermal treatment of P25-TiO 2 with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = −2.82 (P25-TiO 2 ), −13.5 (TNT) and −22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C 9 H 10 ClN 5 O 2 ) degradation to CO 2 formation under UV irradiation because of its largest surface area 176 m 2 g −1 among the catalysts studied.

  3. The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO2 nanostructures of different shapes

    Science.gov (United States)

    Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali

    2013-09-01

    Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO2 catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na2Ti2O5·H2O) particles (W = 9-12 nm and L = 82-115 nm) and rice like pure anatase-TNR particles (W = 8-13 nm and L = 81-134 nm) are obtained by the hydrothermal treatment of P25-TiO2 with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = -2.82 (P25-TiO2), -13.5 (TNT) and -22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C9H10ClN5O2) degradation to CO2 formation under UV irradiation because of its largest surface area 176 m2 g-1 among the catalysts studied.

  4. The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO{sub 2} nanostructures of different shapes

    Energy Technology Data Exchange (ETDEWEB)

    Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali, E-mail: bpal@thapar.edu

    2013-09-01

    Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO{sub 2} catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na{sub 2}Ti{sub 2}O{sub 5}·H{sub 2}O) particles (W = 9–12 nm and L = 82–115 nm) and rice like pure anatase-TNR particles (W = 8–13 nm and L = 81–134 nm) are obtained by the hydrothermal treatment of P25-TiO{sub 2} with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = −2.82 (P25-TiO{sub 2}), −13.5 (TNT) and −22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C{sub 9}H{sub 10}ClN{sub 5}O{sub 2}) degradation to CO{sub 2} formation under UV irradiation because of its largest surface area 176 m{sup 2} g{sup −1} among the catalysts studied.

  5. Unintended Positional Drift and Its Potential Solutions

    DEFF Research Database (Denmark)

    Nilsson, Niels Christian; Serafin, Stefania; Nordahl, Rolf

    2013-01-01

    many users unintentionally move forward while walking in place. We refer to this phenomenon accidental movement as Unintended Positional Drift. The poster presents evidence of the phenomenon's existence and subsequently discusses different design solutions which potentially could circumvent the problem....

  6. Probing the interaction of human serum albumin with vitamin B2 (riboflavin) and L-Arginine (L-Arg) using multi-spectroscopic, molecular modeling and zeta potential techniques

    Energy Technology Data Exchange (ETDEWEB)

    Memarpoor-Yazdi, Mina [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Mahaki, Hanie, E-mail: hanieh.mahaki@gmail.com [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of)

    2013-04-15

    This study was designed to examine the interaction of Riboflavin (RB) and L-Arginine (L-Arg) with human serum albumin (HSA) using different spectroscopic, zeta potential and molecular modeling techniques under imitated physiological conditions. The resonance light scattering (RLS) method determined the critical aggregation concentration of RB on HSA in the presence and absence of L-Arg which confirmed the zeta potential results. The binding constants (K{sub a}) of HSA–RB were 2.5×10{sup 4} and 9.7×10{sup 3} M{sup −1}, respectively in binary and ternary system at the excitation wavelength of 280 nm, also were 7.5×10{sup 3} and 7.3×10{sup 3}, respectively in binary and ternary system at the excitation wavelength of 295 nm. Fluorescence spectroscopy demonstrated that in the presence of L-Arg, the binding constant of HSA–RB was increased. Static quenching was confirmed to results in the fluorescence quenching and FRET. The binding distances between HSA and RB in two- and three-component systems were estimated by the Forster theory which revealed that nonradiative energy transfer from HSA to RB occurred with a high probability. The effect of RB on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy and circular dichroism (CD) in both systems. Docking studies demonstrated a reduction in the binding affinity between RB and HSA in the presence of L-Arg. -- Highlights: ► We studied the interaction of riboflavin with HSA in presence and absence of L-Arg. ► Molecular modeling and zeta-potential used to describe competitive interaction. ► We compared the binding mechanism of riboflavin (RB) to HSA in both systems. ► We determined critical aggregation concentration of RB on HSA in both systems. ► The binding site of RB on HSA in both systems has been determined.

  7. Probing the interaction of human serum albumin with vitamin B2 (riboflavin) and L-Arginine (L-Arg) using multi-spectroscopic, molecular modeling and zeta potential techniques

    International Nuclear Information System (INIS)

    Memarpoor-Yazdi, Mina; Mahaki, Hanie

    2013-01-01

    This study was designed to examine the interaction of Riboflavin (RB) and L-Arginine (L-Arg) with human serum albumin (HSA) using different spectroscopic, zeta potential and molecular modeling techniques under imitated physiological conditions. The resonance light scattering (RLS) method determined the critical aggregation concentration of RB on HSA in the presence and absence of L-Arg which confirmed the zeta potential results. The binding constants (K a ) of HSA–RB were 2.5×10 4 and 9.7×10 3 M −1 , respectively in binary and ternary system at the excitation wavelength of 280 nm, also were 7.5×10 3 and 7.3×10 3 , respectively in binary and ternary system at the excitation wavelength of 295 nm. Fluorescence spectroscopy demonstrated that in the presence of L-Arg, the binding constant of HSA–RB was increased. Static quenching was confirmed to results in the fluorescence quenching and FRET. The binding distances between HSA and RB in two- and three-component systems were estimated by the Forster theory which revealed that nonradiative energy transfer from HSA to RB occurred with a high probability. The effect of RB on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy and circular dichroism (CD) in both systems. Docking studies demonstrated a reduction in the binding affinity between RB and HSA in the presence of L-Arg. -- Highlights: ► We studied the interaction of riboflavin with HSA in presence and absence of L-Arg. ► Molecular modeling and zeta-potential used to describe competitive interaction. ► We compared the binding mechanism of riboflavin (RB) to HSA in both systems. ► We determined critical aggregation concentration of RB on HSA in both systems. ► The binding site of RB on HSA in both systems has been determined

  8. Wind models for zeta Orionis

    International Nuclear Information System (INIS)

    Olson, G.L.

    1979-01-01

    Several models for the winds of O stars have been proposed to explain the unexpected presence of high ionization potential ions such as N +4 and O +5 . Lamers and Snow (1978) proposed that the winds of stars showing N V and O VI lines have elevated temperatures near 4 +- 2 x 10 5 K while cooler stars with anomalous Si IV lines have Tsub(e) approximately 7+-3 x 10 4 K. Alternately, Cassinelli and Olson (1978, CO) and Olson (1978) have explained the presence of these ions by showing that a thin corona at the base of a cool wind (Tsub(e) < approximately Tsub(eff)) can produce these ions by the Auger photoionization process where a single X-ray photon causes the ejection of two electrons. A third possibility is that the winds are at only slightly elevated temperatures (40 000 to 60 000K) and photoionization in an optically thick wind produces the unexpected ions. The present analysis tests the ability of these three wind models to fit the observations of zeta Orionis A 09.7 Ib. (Auth.)

  9. Relativistic double-zeta, triple-zeta, and quadruple-zeta basis sets for the lanthanides La–Lu

    NARCIS (Netherlands)

    Dyall, K.G.; Gomes, A.S.P.; Visscher, L.

    2010-01-01

    Relativistic basis sets of double-zeta, triple-zeta, and quadruple-zeta quality have been optimized for the lanthanide elements La-Lu. The basis sets include SCF exponents for the occupied spinors and for the 6p shell, exponents of correlating functions for the valence shells (4f, 5d and 6s) and the

  10. Bernoulli numbers and zeta functions

    CERN Document Server

    Arakawa, Tsuneo; Kaneko, Masanobu

    2014-01-01

    Two major subjects are treated in this book. The main one is the theory of Bernoulli numbers and the other is the theory of zeta functions. Historically, Bernoulli numbers were introduced to give formulas for the sums of powers of consecutive integers. The real reason that they are indispensable for number theory, however, lies in the fact that special values of the Riemann zeta function can be written by using Bernoulli numbers. This leads to more advanced topics, a number of which are treated in this book: Historical remarks on Bernoulli numbers and the formula for the sum of powers of consecutive integers; a formula for Bernoulli numbers by Stirling numbers; the Clausen–von Staudt theorem on the denominators of Bernoulli numbers; Kummer's congruence between Bernoulli numbers and a related theory of p-adic measures; the Euler–Maclaurin summation formula; the functional equation of the Riemann zeta function and the Dirichlet L functions, and their special values at suitable integers; various formulas of ...

  11. Lectures on zeta functions over finite fields

    OpenAIRE

    Wan, Daqing

    2007-01-01

    These are the notes from the summer school in G\\"ottingen sponsored by NATO Advanced Study Institute on Higher-Dimensional Geometry over Finite Fields that took place in 2007. The aim was to give a short introduction on zeta functions over finite fields, focusing on moment zeta functions and zeta functions of affine toric hypersurfaces.

  12. Multifractal and higher-dimensional zeta functions

    International Nuclear Information System (INIS)

    Véhel, Jacques Lévy; Mendivil, Franklin

    2011-01-01

    In this paper, we generalize the zeta function for a fractal string (as in Lapidus and Frankenhuijsen 2006 Fractal Geometry, Complex Dimensions and Zeta Functions: Geometry and Spectra of Fractal Strings (New York: Springer)) in several directions. We first modify the zeta function to be associated with a sequence of covers instead of the usual definition involving gap lengths. This modified zeta function allows us to define both a multifractal zeta function and a zeta function for higher-dimensional fractal sets. In the multifractal case, the critical exponents of the zeta function ζ(q, s) yield the usual multifractal spectrum of the measure. The presence of complex poles for ζ(q, s) indicates oscillations in the continuous partition function of the measure, and thus gives more refined information about the multifractal spectrum of a measure. In the case of a self-similar set in R n , the modified zeta function yields asymptotic information about both the 'box' counting function of the set and the n-dimensional volume of the ε-dilation of the set

  13. Microencapsulation of β-Carotene Based on Casein/Guar Gum Blend Using Zeta Potential-Yield Stress Phenomenon: an Approach to Enhance Photo-stability and Retention of Functionality.

    Science.gov (United States)

    Thakur, Deepika; Jain, Ashay; Ghoshal, Gargi; Shivhare, U S; Katare, O P

    2017-07-01

    β-Carotene, abundant majorly in carrot, pink guava yams, spinach, kale, sweet potato, and palm oil, is an important nutrient for human health due to its scavenging action upon reactive free radicals wherever produced in the body. Inclusion of liposoluble β-carotene in foods and food ingredients is a challenging aspect due to its labile nature and low absorption from natural sources. This fact has led to the application of encapsulation of β-carotene to improve stability and bioavailability. The present work was aimed to fabricate microcapsules (MCs) of β-carotene oily dispersion using the complex coacervation technique with casein (CA) and guar gum (GG) blend. The ratio of CA:GG was found to be 1:0.5 (w/v) when optimized on the basis of zeta potential-yield stress phenomenon. These possessed a higher percentage yield (71.34 ± 0.55%), lower particle size (176.47 ± 4.65 μm), higher encapsulation efficiency (65.95 ± 5.33%), and in general, a uniform surface morphology was observed with particles showing optimized release behavior. Prepared MCs manifested effective and controlled release (up to 98%) following zero-order kinetics which was adequately explained by the Korseymer-Peppas model. The stability of the freeze-dried MCs was established in simulated gastrointestinal fluids (SGF, SIF) for 8 h. Antioxidant activity of the MCs was studied and revealed the retention of the functional architecture of β-carotene in freeze-dried MCs. Minimal photolytic degradation upon encapsulation of β-carotene addressed the challenge regarding photo-stability of β-carotene as confirmed via mass spectroscopy.

  14. Status of the zeta(8.3)

    International Nuclear Information System (INIS)

    Lowe, S.T.

    1985-05-01

    Results are presented from 22.1 pb -1 of UPSILON(1S) data, taken with the Crystal Ball detector at DORIS. These data were taken to further explore the zeta(8.3) signal originally seen in 10.4 pb -1 of UPSILON(1S) data. No evidence for the zeta is observed in this new sample. Data quality checks and possible explanations are discussed

  15. Heat kernels and zeta functions on fractals

    International Nuclear Information System (INIS)

    Dunne, Gerald V

    2012-01-01

    On fractals, spectral functions such as heat kernels and zeta functions exhibit novel features, very different from their behaviour on regular smooth manifolds, and these can have important physical consequences for both classical and quantum physics in systems having fractal properties. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical in honour of Stuart Dowker's 75th birthday devoted to ‘Applications of zeta functions and other spectral functions in mathematics and physics’. (paper)

  16. Spatial distribution of potential and positive Aedes aegypti breeding sites

    Directory of Open Access Journals (Sweden)

    Daniel Elías Cuartas

    2017-03-01

    Conclusions: The spatial relationship between positive and potential A. aegypti breeding sites both indoors and outdoors is dynamic and highly sensitive to the characteristics of each territory. Knowing how positive and potential breeding sites are distributed contributes to the prioritization of resources and actions in vector control programs.

  17. Lectures on the Riemann zeta function

    CERN Document Server

    Iwaniec, H

    2014-01-01

    The Riemann zeta function was introduced by L. Euler (1737) in connection with questions about the distribution of prime numbers. Later, B. Riemann (1859) derived deeper results about the prime numbers by considering the zeta function in the complex variable. The famous Riemann Hypothesis, asserting that all of the non-trivial zeros of zeta are on a critical line in the complex plane, is one of the most important unsolved problems in modern mathematics. The present book consists of two parts. The first part covers classical material about the zeros of the Riemann zeta function with applications to the distribution of prime numbers, including those made by Riemann himself, F. Carlson, and Hardy-Littlewood. The second part gives a complete presentation of Levinson's method for zeros on the critical line, which allows one to prove, in particular, that more than one-third of non-trivial zeros of zeta are on the critical line. This approach and some results concerning integrals of Dirichlet polynomials are new. Th...

  18. Brainstem Auditory Evoked Potential in HIV-Positive Adults.

    Science.gov (United States)

    Matas, Carla Gentile; Samelli, Alessandra Giannella; Angrisani, Rosanna Giaffredo; Magliaro, Fernanda Cristina Leite; Segurado, Aluísio C

    2015-10-20

    To characterize the findings of brainstem auditory evoked potential in HIV-positive individuals exposed and not exposed to antiretroviral treatment. This research was a cross-sectional, observational, and descriptive study. Forty-five HIV-positive individuals (18 not exposed and 27 exposed to the antiretroviral treatment - research groups I and II, respectively - and 30 control group individuals) were assessed through brainstem auditory evoked potential. There were no significant between-group differences regarding wave latencies. A higher percentage of altered brainstem auditory evoked potential was observed in the HIV-positive groups when compared to the control group. The most common alteration was in the low brainstem. HIV-positive individuals have a higher percentage of altered brainstem auditory evoked potential that suggests central auditory pathway impairment when compared to HIV-negative individuals. There was no significant difference between individuals exposed and not exposed to antiretroviral treatment.

  19. Zeta function methods and quantum fluctuations

    International Nuclear Information System (INIS)

    Elizalde, Emilio

    2008-01-01

    A review of some recent advances in zeta function techniques is given, in problems of pure mathematical nature but also as applied to the computation of quantum vacuum fluctuations in different field theories, and specially with a view to cosmological applications

  20. 77 FR 72975 - Zeta Cypermethrin; Pesticide Tolerances

    Science.gov (United States)

    2012-12-07

    ... for quantifying risks, there is no increase in hazard with increasing dosing duration. Therefore, the... exposure models in the dietary exposure analysis and risk assessment for zeta-cypermethrin in drinking... the dietary exposure model. For acute dietary risk assessment, the water concentration value of 3.77...

  1. New inequalities for the Hurwitz zeta function

    Indian Academy of Sciences (India)

    We establish various new inequalities for the Hurwitz zeta function. Our results generalize some known results ... mention here two of them: The first is the evaluation by Kolbig [10] of integrals of the form. Rm(μ, υ) = ∫ ∞. 0 e. −μttυ−1 log m t dt,.

  2. Bernoulli Polynomials, Fourier Series and Zeta Numbers

    DEFF Research Database (Denmark)

    Scheufens, Ernst E

    2013-01-01

    Fourier series for Bernoulli polynomials are used to obtain information about values of the Riemann zeta function for integer arguments greater than one. If the argument is even we recover the well-known exact values, if the argument is odd we find integral representations and rapidly convergent...

  3. Euler Polynomials, Fourier Series and Zeta Numbers

    DEFF Research Database (Denmark)

    Scheufens, Ernst E

    2012-01-01

    Fourier series for Euler polynomials is used to obtain information about values of the Riemann zeta function for integer arguments greater than one. If the argument is even we recover the well-known exact values, if the argument is odd we find integral representations and rapidly convergent series....

  4. Fractal diffusion coefficient from dynamical zeta functions

    Energy Technology Data Exchange (ETDEWEB)

    Cristadoro, Giampaolo [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Str. 38, D 01187 Dresden (Germany)

    2006-03-10

    Dynamical zeta functions provide a powerful method to analyse low-dimensional dynamical systems when the underlying symbolic dynamics is under control. On the other hand, even simple one-dimensional maps can show an intricate structure of the grammar rules that may lead to a non-smooth dependence of global observables on parameters changes. A paradigmatic example is the fractal diffusion coefficient arising in a simple piecewise linear one-dimensional map of the real line. Using the Baladi-Ruelle generalization of the Milnor-Thurnston kneading determinant, we provide the exact dynamical zeta function for such a map and compute the diffusion coefficient from its smallest zero. (letter to the editor)

  5. Fractal diffusion coefficient from dynamical zeta functions

    International Nuclear Information System (INIS)

    Cristadoro, Giampaolo

    2006-01-01

    Dynamical zeta functions provide a powerful method to analyse low-dimensional dynamical systems when the underlying symbolic dynamics is under control. On the other hand, even simple one-dimensional maps can show an intricate structure of the grammar rules that may lead to a non-smooth dependence of global observables on parameters changes. A paradigmatic example is the fractal diffusion coefficient arising in a simple piecewise linear one-dimensional map of the real line. Using the Baladi-Ruelle generalization of the Milnor-Thurnston kneading determinant, we provide the exact dynamical zeta function for such a map and compute the diffusion coefficient from its smallest zero. (letter to the editor)

  6. The design and performance of ZETA

    Energy Technology Data Exchange (ETDEWEB)

    Butt, E P; Carruthers, R; Mitchell, J T.D.; Pease, R S; Thonemann, P C [U.K. Atomic Energy Authority, AERE Harwell (United Kingdom); Bird, M A; Blears, J; Hartill, E R [Metropolitan Vickers Electrical Co. Ltd., Trafiord Park, Manchester 17 (United Kingdom)

    1958-07-01

    ZETA is an experimental apparatus for studying the pinched ring discharge as a possible method of producing controlled thermonuclear power. The principle of this method is that the self-magnetic field of the discharge current isolates the plasma from the walls of the discharge tube. The present paper reports the principal mechanical and electrical parameters, the performance as an electrical circuit, and our present knowledge of the physical characteristics of the plasma.

  7. Ten physical applications of spectral zeta functions

    CERN Document Server

    Elizalde, Emilio

    1995-01-01

    Zeta-function regularization is a powerful method in perturbation theory. This book is meant as a guide for the student of this subject. Everything is explained in detail, in particular the mathematical difficulties and tricky points, and several applications are given to show how the procedure works in practice (e.g. Casimir effect, gravity and string theory, high-temperature phase transition, topological symmetry breaking). The formulas some of which are new can be used for accurate numerical calculations. The book is to be considered as a basic introduction and a collection of exercises for those who want to apply this regularization procedure in practice.

  8. Zeta functions for the spectrum of the non-commutative harmonic oscillators

    CERN Document Server

    Ichinose, T

    2004-01-01

    This paper investigates the spectral zeta function of the non-commutative harmonic oscillator studied in \\cite{PW1, 2}. It is shown, as one of the basic analytic properties, that the spectral zeta function is extended to a meromorphic function in the whole complex plane with a simple pole at $s=1$, and further that it has a zero at all non-positive even integers, i.e. at $s=0$ and at those negative even integers where the Riemann zeta function has the so-called trivial zeros. As a by-product of the study, both the upper and the lower bounds are also given for the first eigenvalue of the non-commutative harmonic oscillator.

  9. Ten physical applications of spectral zeta functions

    CERN Document Server

    Elizalde, Emilio

    2012-01-01

    Zeta-function regularization is a powerful method in perturbation theory, and this book is a comprehensive guide for the student of this subject. Everything is explained in detail, in particular the mathematical difficulties and tricky points, and several applications are given to show how the procedure works in practice, for example in the Casimir effect, gravity and string theory, high-temperature phase transition, topological symmetry breaking, and non-commutative spacetime. The formulae, some of which are new, can be directly applied in creating physically meaningful, accurate numerical calculations. The book acts both as a basic introduction and a collection of exercises for those who want to apply this regularization procedure in practice. Thoroughly revised, updated and expanded, this new edition includes novel, explicit formulas on the general quadratic, the Chowla-Selberg series case, an interplay with the Hadamard calculus, and also features a fresh chapter on recent cosmological applications, inclu...

  10. Are AMPA Receptor Positive Allosteric Modulators Potential Pharmacotherapeutics for Addiction?

    Directory of Open Access Journals (Sweden)

    Lucas R. Watterson

    2013-12-01

    Full Text Available Positive allosteric modulators (PAMs of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA receptors are a diverse class of compounds that increase fast excitatory transmission in the brain. AMPA PAMs have been shown to facilitate long-term potentiation, strengthen communication between various cortical and subcortical regions, and some of these compounds increase the production and release of brain-derived neurotrophic factor (BDNF in an activity-dependent manner. Through these mechanisms, AMPA PAMs have shown promise as broad spectrum pharmacotherapeutics in preclinical and clinical studies for various neurodegenerative and psychiatric disorders. In recent years, a small collection of preclinical animal studies has also shown that AMPA PAMs may have potential as pharmacotherapeutic adjuncts to extinction-based or cue-exposure therapies for the treatment of drug addiction. The present paper will review this preclinical literature, discuss novel data collected in our laboratory, and recommend future research directions for the possible development of AMPA PAMs as anti-addiction medications.

  11. The multiple zeta value data mine

    Energy Technology Data Exchange (ETDEWEB)

    Buemlein, J. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Broadhurst, D.J. [Open Univ., Milton Keynes (United Kingdom). Physics and Astronomy Dept.; Vermaseren, J.A.M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); NIKHEF, Amsterdam (Netherlands)

    2009-07-15

    We provide a data mine of proven results for multiple zeta values (MZVs) of the form {zeta}(s{sub 1},s{sub 2},..,s{sub k}) = sum {sup {infinity}}{sub n{sub 1}}{sub >n{sub 2}}{sub >...>n{sub k}}{sub >0} {l_brace}1/(n{sub 1}{sup s{sub 1}}..n{sub k}{sup s{sub k}}){r_brace} with weight w = sum {sup K}{sub i=1}s{sub i} and depth k and for Euler sums of the form sum {sup {infinity}}{sub n{sub 1}}{sub >n{sub 2}}{sub >...>n{sub k}}{sub >0} {l_brace}({epsilon}{sub 1}{sup n{sub 1}}..{epsilon}{sub 1}{sup n{sub k}})/(n{sub 1}{sup s{sub 1}}..n{sub k}{sup s{sub k}}){r_brace} with signs {epsilon}{sub i} = {+-} 1. Notably, we achieve explicit proven reductions of all MZVs with weights w{<=}22, and all Euler sums with weights w{<=}12, to bases whose dimensions, bigraded by weight and depth, have sizes in precise agreement with the Broadhurst. Kreimer and Broadhurst conjectures. Moreover, we lend further support to these conjectures by studying even greater weights (w{<=}30), using modular arithmetic. To obtain these results we derive a new type of relation for Euler sums, the Generalized Doubling Relations. We elucidate the ''pushdown'' mechanism, whereby the ornate enumeration of primitive MZVs, by weight and depth, is reconciled with the far simpler enumeration of primitive Euler sums. There is some evidence that this pushdown mechanism finds its origin in doubling relations. We hope that our data mine, obtained by exploiting the unique power of the computer algebra language FORM, will enable the study of many more such consequences of the double-shuffle algebra of MZVs, and their Euler cousins, which are already the subject of keen interest, to practitioners of quantum field theory, and to mathematicians alike. (orig.)

  12. Neural substrate of the late positive potential in emotional processing

    Science.gov (United States)

    Liu, Yuelu; Huang, Haiqing; McGinnis, Menton; Keil, Andreas; Ding, Mingzhou

    2012-01-01

    The late positive potential (LPP) is a reliable electrophysiological index of emotional perception in humans. Despite years of research the brain structures that contribute to the generation and modulation of LPP are not well understood. Recording EEG and fMRI simultaneously, and applying a recently proposed single-trial ERP analysis method, we addressed the problem by correlating the single-trial LPP amplitude evoked by affective pictures with the blood-oxygen-level-dependent (BOLD) activity. Three results were found. First, relative to neutral pictures, pleasant and unpleasant pictures elicited enhanced LPP, as well as heightened BOLD activity in both visual cortices and emotion-processing structures such as amygdala and prefrontal cortex, consistent with previous findings. Second, the LPP amplitude across three picture categories was significantly correlated with BOLD activity in visual cortices, temporal cortices, amygdala, orbitofrontal cortex, and insula. Third, within each picture category, LPP-BOLD coupling revealed category-specific differences. For pleasant pictures, the LPP amplitude was coupled with BOLD in occipitotemporal junction, medial prefrontal cortex, amygdala, and precuneus, whereas for unpleasant pictures, significant LPP-BOLD correlation was observed in ventrolateral prefrontal cortex, insula, and posterior cingulate cortex. These results suggest that LPP is generated and modulated by an extensive brain network comprised of both cortical and subcortical structures associated with visual and emotional processing and the degree of contribution by each of these structures to the LPP modulation is valence-specific. PMID:23077042

  13. The multiple zeta value data mine

    International Nuclear Information System (INIS)

    Buemlein, J.; Broadhurst, D.J.

    2009-07-01

    We provide a data mine of proven results for multiple zeta values (MZVs) of the form ζ(s 1 ,s 2 ,..,s k ) = sum ∞ n 1 >n 2 >...>n k >0 {1/(n 1 s 1 ..n k s k )} with weight w = sum K i=1 s i and depth k and for Euler sums of the form sum ∞ n 1 >n 2 >...>n k >0 {(ε 1 n 1 ..ε 1 n k )/(n 1 s 1 ..n k s k )} with signs ε i = ± 1. Notably, we achieve explicit proven reductions of all MZVs with weights w≤22, and all Euler sums with weights w≤12, to bases whose dimensions, bigraded by weight and depth, have sizes in precise agreement with the Broadhurst. Kreimer and Broadhurst conjectures. Moreover, we lend further support to these conjectures by studying even greater weights (w≤30), using modular arithmetic. To obtain these results we derive a new type of relation for Euler sums, the Generalized Doubling Relations. We elucidate the ''pushdown'' mechanism, whereby the ornate enumeration of primitive MZVs, by weight and depth, is reconciled with the far simpler enumeration of primitive Euler sums. There is some evidence that this pushdown mechanism finds its origin in doubling relations. We hope that our data mine, obtained by exploiting the unique power of the computer algebra language FORM, will enable the study of many more such consequences of the double-shuffle algebra of MZVs, and their Euler cousins, which are already the subject of keen interest, to practitioners of quantum field theory, and to mathematicians alike. (orig.)

  14. Mayer Transfer Operator Approach to Selberg Zeta Function

    DEFF Research Database (Denmark)

    Momeni, Arash; Venkov, Alexei

    . In a special situation the dynamical zeta function is defined for a geodesic flow on a hyperbolic plane quotient by an arithmetic cofinite discrete group. More precisely, the flow is defined for the corresponding unit tangent bundle. It turns out that the Selberg zeta function for this group can be expressed...... in terms of a Fredholm determinant of a classical transfer operator of the flow. The transfer operator is defined in a certain space of holomorphic functions and its matrix representation in a natural basis is given in terms of the Riemann zeta function and the Euler gamma function....

  15. Potential predictive factors of positive prostate biopsy in the Chinese ...

    African Journals Online (AJOL)

    Yomi

    2012-01-16

    Jan 16, 2012 ... Therefore, it might be inappropriate that we apply these western models to the. Chinese population that has a lower incidence of PCa. Therefore, this retrospective study aimed to determine predictive factors for a positive prostate biopsy in Chinese men. Our ultimate goal is to develop a simple model for ...

  16. Involvement of proteasomal subunits zeta and iota in RNA degradation.

    Science.gov (United States)

    Petit, F; Jarrousse, A S; Dahlmann, B; Sobek, A; Hendil, K B; Buri, J; Briand, Y; Schmid, H P

    1997-01-01

    We have identified two distinct subunits of 20 S proteasomes that are associated with RNase activity. Proteasome subunits zeta and iota, eluted from two-dimensional Western blots, hydrolysed tobacco mosaic virus RNA, whereas none of the other subunits degraded this substrate under the same conditions. Additionally, proteasomes were dissociated by 6 M urea, and subunit zeta, containing the highest RNase activity, was isolated by anion-exchange chromatography and gel filtration. Purified subunit zeta migrated as a single spot on two-dimensional PAGE with a molecular mass of approx. 28 kDa. Addition of anti-(subunit zeta) antibodies led to the co-precipitation of this proteasome subunit and nuclease activity. This is the first evidence that proteasomal alpha-type subunits are associated with an enzymic activity, and our results provide further evidence that proteasomes may be involved in cellular RNA metabolism. PMID:9337855

  17. Mast cells: potential positive and negative roles in tumor biology.

    Science.gov (United States)

    Marichal, Thomas; Tsai, Mindy; Galli, Stephen J

    2013-11-01

    Mast cells are immune cells that reside in virtually all vascularized tissues. Upon activation by diverse mechanisms, mast cells can secrete a broad array of biologically active products that either are stored in the cytoplasmic granules of the cells (e.g., histamine, heparin, various proteases) or are produced de novo upon cell stimulation (e.g., prostaglandins, leukotrienes, cytokines, chemokines, and growth factors). Mast cells are best known for their effector functions during anaphylaxis and acute IgE-associated allergic reactions, but they also have been implicated in a wide variety of processes that maintain health or contribute to disease. There has been particular interest in the possible roles of mast cells in tumor biology. In vitro studies have shown that mast cells have the potential to influence many aspects of tumor biology, including tumor development, tumor-induced angiogenesis, and tissue remodeling, and the shaping of adaptive immune responses to tumors. Yet, the actual contributions of mast cells to tumor biology in vivo remain controversial. Here, we review some basic features of mast cell biology with a special emphasis on those relevant to their potential roles in tumors. We discuss how using in vivo tumor models in combination with models in which mast cell function can be modulated has implicated mast cells in the regulation of host responses to tumors. Finally, we summarize data from studies of human tumors that suggest either beneficial or detrimental roles for mast cells in tumors. ©2013 AACR.

  18. Cytokeratin positivity in myxopapillary ependymoma – a potential diagnostic pitfall

    Directory of Open Access Journals (Sweden)

    Sur Monalisa

    2008-10-01

    Full Text Available Abstract Background Myxopapillary ependymomas (MPE occur in the filum terminale of the spinal cord, but also present in extra-spinal locations such as subcutaneous tissue and brain. They are slow growing grade I gliomas. Areas of solid growth pattern with aggregates of cells with "epithelioid morphology" seen in MPE can mimic metastatic carcinoma. The presence of occasional cells with clear cytoplasm and morphology can resemble Chordoma. Diagnosis can be missed due to these morphological similarities, which could affect patient management and hence, long term survival. Case presentation We describe two cases of MPE with cytokeratin (AE1 AE3, CAM 5.2, Cytokeratin 7 and cytokeratin 20 expression. Conclusion MPE can be positive for Cytokeratins (CAM 5.2, AE1 AE3, CK7 and focally for EMA, which could be misdiagnosed as metastatic carcinoma. In cases demonstrating epithelioid and clear cell morphology, the diagnosis of MPE should be made in conjunction with histology, proper immunohistochemical profile which includes co-expression of GFAP, S-100 protein and epithelial markers, radiologic findings and site. It is important to be aware of the cytokeratin profile in MPE to avoid erroneous diagnosis with other tumour entities.

  19. Positive organizational potential as a valuable resource of the contemporary company

    Directory of Open Access Journals (Sweden)

    Bohdan Godziszewski

    2014-12-01

    Full Text Available The main aim of the article is to present an outcome of the research project concerning the essence and importance of positive organizational potential understood as state, levels and configurations of companies’ resources which stimulate positive organizational climate, positive organizational culture and positive employees’ behaviour, supporting comprehensive companies’ development. Within the project framework was necessary to identify the internal structure of positive potential, positive culture, positive climate and positive employees’ behaviours. Correlations among the above phenomena and companies’ performances were calculated, within a group of 103 Polish companies, as well.

  20. Empathy and the Internet: Positive Potentials vs. Risks

    Directory of Open Access Journals (Sweden)

    Tatjana Milivojević

    2015-09-01

    Full Text Available Internet enables the exchange of information with incredible speed, allowing at the same time users to share their feelings, thoughts and opinions. This exchange that can be carried out virally spreading the interest about people and events that transcends our geographical and social horizons, represents a civilizational progress when it’s not recognized just as technological progress, but also as an increasing process of humanization of man and society. Empathy, which was once reserved for the narrowest community, can now be expanded globally. This optimistic view, however, doesn’t take under consideration that human capacity for empathy isn't limitless. Perceptual, cognitive, and emotional overload can lead to saturation and desensitization or dissociation where there is apperception of others, but without any emotional involvement. The paradox of empathy lays within its possibility of being used as a means of control and manipulation: it’s then a pure mimicry of empathy. It can serve a better acquaintance, rapprochement and understanding of other people and cultures, or, on the contrary, non-relations such as impersonation, inauthentic communication, and ultimately online harassment. Therefore, the possibility that Internet gives us to be connected to others is less important than the personal attitude that each individual has towards it and to others via the network. Internet isn't empathic by itself, but it can help one’s basic empathy, which is developing in vivid interpersonal contacts in the real world, to expand to the remote and sensory unobservable others. In this article we’ll analyze the empathic potential of social networks, as well as their features that can narrow or even shut down empathy.

  1. Relationship between phospholipase C-zeta, semen parameters, and chromatin status.

    Science.gov (United States)

    Tavalaee, Marziyeh; Kiani-Esfahani, Abbas; Nasr-Esfahani, Mohammad H

    2017-08-01

    The need for additional tests to complement basic sperm analysis in clinics is well appreciated. In this regard, a number of tests such as sperm DNA integrity test as a tool in diagnosis and treatment of infertility are suggested. But recent studies have focused on main sperm factors involved in oocyte activation such as phospholipase C-zeta (PLCζ) that initiate intracellular Ca 2+ signaling and embryogenesis. Therefore, this study aimed to investigate the relationship between PLCζ, basic semen parameters, sperm DNA fragmentation (SDF), and protamine deficiency in men with normal (n=32) and abnormal (n=23) semen parameters. Unlike SDF and protamine deficiency, as negative factors related to fertility, the mean value of PLCζ as positive factor related to infertility was significantly lower in men with abnormal semen parameters compared to men with normal semen parameters. Significant correlations were also observed between sperm concentration, motility, and abnormal morphology with the percentage of PLCζ positive spermatozoa. In addition, logistic regression analysis revealed that sperm morphology is more predictive than sperm motility and concentration for PLCζ presence. In addition, a statistically significant negative relationship was observed between the percentage of PLCζ positive spermatozoa and SDF. These findings suggested during ICSI, selection of sperm based on morphology has a profound effect on its ability to induce oocyte activation based on the likelihood of PLCζ expression. Therefore, assessment of PLCζ as an index for fertilization potential of a semen sample in men with severe teratozoospermia may define individuals who are candidates for artificial oocyte activation (AOA) and may avoid failed fertilization post ICSI.

  2. From Fourier Series to Rapidly Convergent Series for Zeta(3)

    DEFF Research Database (Denmark)

    Scheufens, Ernst E

    2011-01-01

    The article presents a mathematical study which investigates the exact values of the Riemann zeta (ζ) function. It states that exact values can be determined from Fourier series for periodic versions of even power functions. It notes that using power series for logarithmic functions on this such ......The article presents a mathematical study which investigates the exact values of the Riemann zeta (ζ) function. It states that exact values can be determined from Fourier series for periodic versions of even power functions. It notes that using power series for logarithmic functions...

  3. Gender moderates valence effects on the late positive potential to emotional distracters

    OpenAIRE

    Syrjänen, Elmeri

    2013-01-01

    Attention is captured more strongly by emotional pictures than by neutral pictures. This allocation of attention to emotional pictures is commonly indexed by the late positive potential (LPP), an event-related potential (ERP) that is larger for negative and positive pictures than for neutral pictures. However, findings are mixed in regards to valence effects, that is, whether the LPP is larger for negative pictures than for positive pictures (negativity bias) or vice versa (positivity bias). ...

  4. Positive technology–A powerful partnership between positive psychology and interactive technology. A discussion of potential and challenges.

    Directory of Open Access Journals (Sweden)

    Sarah Diefenbach

    2017-11-01

    Full Text Available Under the umbrella term "positive computing" concepts of positive psychology are transferred to the domain of human-computer interaction (HCI. In an interdisciplinary community psychologist, computer scientists, designers and others are exploring promising ways how to utilize interactive technology to support wellbeing and human flourishing. Along with this, the recent popularity of smartphone apps aiming at the improvement of health behavior, mindfulness and positive routines, suggests the general acceptance of technology as a facilitator of personal development. Given this, there generally seems a high potential for a technology mediated trigger of positive behavior change, especially in context of positive psychology and resource oriented approaches such as solution-focused coaching. At the same time, there is still a lack of well-founded approaches to design such technology which consider its responsible role as an "interactive coach" and systematically integrate the needed expertise of different disciplines. The present article discusses the general potential and particular challenges to support the goals of positive psychology and human desire for self-improvement through interactive technology and highlights critical steps for a successful partnership between both.

  5. Crossing the entropy barrier of dynamical zeta functions

    International Nuclear Information System (INIS)

    Aurich, R.; Bolte, J.; Matthies, C.; Sieber, M.; Steiner, F.

    1992-01-01

    Dynamical zeta functions are an important tool to quantize chaotic dynamical systems. The basic quantization rules require the computation of the zeta functions on the real energy axis, where the Euler product representations running over the classical periodic orbits usually do not converge due to the existence of the so-called entropy barrier determined by the topological entropy of the classical system. We shown that the convergence properties of the dynamical zeta functions rewritten as Dirichlet series are governed not only by the well-known topological and metric entropy, but depend crucially on subtle statistical properties of the Maslow indices and of the multiplicities of the periodic orbits that are measured by a new parameter for which we introduce the notion of a third entropy. If and only if the third entropy is nonvanishing, one can cross the entropy barrier; if it exceeds a certain value, one can even compute the zeta function in the physical region by means of a convergent Dirichlet series. A simple statistical model is presented which allows to compute the third entropy. Four examples of chaotic systems are studied in detail to test the model numerically. (orig.)

  6. Dynamical zeta functions for piecewise monotone maps of the interval

    CERN Document Server

    Ruelle, David

    2004-01-01

    Consider a space M, a map f:M\\to M, and a function g:M \\to {\\mathbb C}. The formal power series \\zeta (z) = \\exp \\sum ^\\infty _{m=1} \\frac {z^m}{m} \\sum _{x \\in \\mathrm {Fix}\\,f^m} \\prod ^{m-1}_{k=0} g (f^kx) yields an example of a dynamical zeta function. Such functions have unexpected analytic properties and interesting relations to the theory of dynamical systems, statistical mechanics, and the spectral theory of certain operators (transfer operators). The first part of this monograph presents a general introduction to this subject. The second part is a detailed study of the zeta functions associated with piecewise monotone maps of the interval [0,1]. In particular, Ruelle gives a proof of a generalized form of the Baladi-Keller theorem relating the poles of \\zeta (z) and the eigenvalues of the transfer operator. He also proves a theorem expressing the largest eigenvalue of the transfer operator in terms of the ergodic properties of (M,f,g).

  7. On calculation of zeta function of integral matrix

    Czech Academy of Sciences Publication Activity Database

    Janáček, Jiří

    2009-01-01

    Roč. 134, č. 1 (2009), s. 49-58 ISSN 0862-7959 R&D Projects: GA AV ČR(CZ) IAA100110502 Institutional research plan: CEZ:AV0Z50110509 Keywords : Epstein zeta function * integral lattice * Riemann theta function Subject RIV: BA - General Mathematics

  8. Crossing the entropy barrier of dynamical zeta functions

    Energy Technology Data Exchange (ETDEWEB)

    Aurich, R.; Bolte, J.; Matthies, C.; Sieber, M.; Steiner, F. (Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik)

    1992-01-01

    Dynamical zeta functions are an important tool to quantize chaotic dynamical systems. The basic quantization rules require the computation of the zeta functions on the real energy axis, where the Euler product representations running over the classical periodic orbits usually do not converge due to the existence of the so-called entropy barrier determined by the topological entropy of the classical system. We shown that the convergence properties of the dynamical zeta functions rewritten as Dirichlet series are governed not only by the well-known topological and metric entropy, but depend crucially on subtle statistical properties of the Maslow indices and of the multiplicities of the periodic orbits that are measured by a new parameter for which we introduce the notion of a third entropy. If and only if the third entropy is nonvanishing, one can cross the entropy barrier; if it exceeds a certain value, one can even compute the zeta function in the physical region by means of a convergent Dirichlet series. A simple statistical model is presented which allows to compute the third entropy. Four examples of chaotic systems are studied in detail to test the model numerically. (orig.).

  9. The Effectiveness of Positive Coping Program on Reduction of Addiction Potential in Students

    Directory of Open Access Journals (Sweden)

    Fatemeh Nematollahi

    2010-02-01

    Full Text Available Objective: This study aimed to study the effectiveness of positive coping program on reduction of addiction potential in dormitory girl students. Method: The research method was semi experimental method namely: pre test-post test with witness group. In selection of sample, first addiction potential scale administered among 160 dormitory girl students, and 20 of them who were scored higher than cutoff score on addiction potential scale selected and divided to two experimental and witness groups. Experimental group received 10 sessions training which each session was 90 minutes. Positive coping program was based on three components of Bob Murray’s theory namely: social relationships, goal setting and spirituality. After finishing of training Post test were administered in both experimental and witness groups. Results: The results showed positive coping training was significantly reduced students’ addiction potential. Conclusion: The training of positive coping can be affect on reduction of girl students’ addiction potential.

  10. Lecture notes: string theory and zeta-function

    Energy Technology Data Exchange (ETDEWEB)

    Toppan, Francesco [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). E-mail: toppan@cbpf.br

    2001-11-01

    These lecture notes are based on a revised and LaTexed version of the Master thesis defended at ISAS. The research part being omitted, they included a review of the bosonic closed string a la Polyakov and of the one-loop background field method of quantisation defined through the zeta-function. In an appendix some basic features of the Riemann zeta-function are also reviewed. The pedagogical aspects of the material here presented are particularly emphasized. These notes are used, together with the Scherk's article in Rev. Mod. Phys. and the first volume of the Polchinski book, for the mini-course on String Theory (16-hours of lectures) held at CBPF. In this course the Green-Schwarz-Witten two-volumes book is also used for consultative purposes. (author)

  11. Relating zeta functions of discrete and quantum graphs

    Science.gov (United States)

    Harrison, Jonathan; Weyand, Tracy

    2018-02-01

    We write the spectral zeta function of the Laplace operator on an equilateral metric graph in terms of the spectral zeta function of the normalized Laplace operator on the corresponding discrete graph. To do this, we apply a relation between the spectrum of the Laplacian on a discrete graph and that of the Laplacian on an equilateral metric graph. As a by-product, we determine how the multiplicity of eigenvalues of the quantum graph, that are also in the spectrum of the graph with Dirichlet conditions at the vertices, depends on the graph geometry. Finally we apply the result to calculate the vacuum energy and spectral determinant of a complete bipartite graph and compare our results with those for a star graph, a graph in which all vertices are connected to a central vertex by a single edge.

  12. Zeta functional equation on Jordan algebras of type II

    International Nuclear Information System (INIS)

    Kayoya, J.B.

    2003-10-01

    Using the Jordan algebras method, specially the properties of Peirce decomposition and the Frobenius transformation, we compute the coefficients of the zeta functional equation, in the case of Jordan algebras of Type II. As particular cases of our result, we can cite the case of V M (n, R) studied by Gelbart and Godement-Jacquet, and the case of V Herm(3, O s ) studied by Muro. Let us also mention, that recently, Bopp and Rubenthaler have obtained a more general result on the zeta functional equation by using methods based on the algebraic properties of regular graded algebras which are in one to one correspondence with simple Jordan algebras. The method used in this paper is a direct application of specific properties of Jordan algebras of Type H. (author)

  13. Potencial zeta de sulfatos de de bario y de estroncio

    OpenAIRE

    Delgado M., Edgar

    2010-01-01

    Por medio de la electroforesis se determinó las movilidades electroforéticas y los potenciales zeta del sulfato de bario a 25,0 °C como función de la fuerza iónica de NaCI, así como del Sulfato de estroncio en función de la fuerza iónica del cloruro de sodio y del pH. Se encontró que el amento de la fuerza iónica de NaCI causa un cambio del Potencial Zeta negativo del sulfato de estroncio a positivo con valor cero a aprox. 0,06 de fuerza iónica. El P.Z. del sulfato de estroncio es positivo...

  14. Multiple zeta values and application to the Lacunary recurrence formulas of Bernoulli numbers

    International Nuclear Information System (INIS)

    Chen, Y-H

    2008-01-01

    This paper obtains a recurrence related to multiple zeta function, which generalizes the Newton recurrence for multiple zeta values for period 1. Moreover, we obtain some new Lacunary recurrence formulas of Bernoulli numbers

  15. Evaluation of spectral zeta-functions with the renormalization group

    International Nuclear Information System (INIS)

    Boettcher, Stefan; Li, Shanshan

    2017-01-01

    We evaluate spectral zeta-functions of certain network Laplacians that can be treated exactly with the renormalization group. As specific examples we consider a class of Hanoi networks and those hierarchical networks obtained by the Migdal–Kadanoff bond moving scheme from regular lattices. As possible applications of these results we mention quantum search algorithms as well as synchronization, which we discuss in more detail. (paper)

  16. A zeta function approach to the semiclassical quantization of maps

    International Nuclear Information System (INIS)

    Smilansky, Uzi.

    1993-11-01

    The quantum analogue of an area preserving map on a compact phase space is a unitary (evolution) operator which can be represented by a matrix of dimension L∝ℎ -1 . The semiclassical theory for spectrum of the evolution operator will be reviewed with special emphasize on developing a dynamical zeta function approach, similar to the one introduced recently for a semiclassical quantization of hamiltonian systems. (author)

  17. Justification of the zeta-function renormalization in rigid string model

    International Nuclear Information System (INIS)

    Nesterenko, V.V.; Pirozhenko, I.G.

    1997-01-01

    A consistent procedure for regularization of divergences and for the subsequent renormalization of the string tension is proposed in the framework of the one-loop calculation of the interquark potential generated by the Polyakov-Kleinert string. In this way, a justification of the formal treatment of divergences by analytic continuation of the Riemann and Epstein-Hurwitz zeta-functions is given. A spectral representation for the renormalized string energy at zero temperature is derived, which enables one to find the Casimir energy in this string model at nonzero temperature very easy

  18. Functional equation for the Mordell-Tornheim multiple zeta-function

    OpenAIRE

    Okamoto, Takuya; Onozuka, Tomokazu

    2016-01-01

    We show a relation between the Mordell-Tornheim multiple zeta-function and the confluent hypergeometric function, and using it, we give the functional equation for the Mordell-Tornheim multiple zeta-function. In the double case, the functional equation includes the known functional equation for the Euler-Zagier double zeta-function.

  19. Comparative study of potential whiplash injuries for different occupant seated positions during rear end accidents.

    Science.gov (United States)

    Omerović, Senad; Tomasch, Ernst; Gutsche, Andreas J; Prebil, Ivan

    2016-01-01

    Whiplash injuries to the cervical spine represent a considerable economic burden on society with medical conditions, in some cases persisting for more than a year. Numerous studies of whiplash injuries have been made for occupant normal seated position, leaving the analysis of neck injuries for out-of-normal positions not well documented. For that purpose, a detailed human cervical spine finite element model was developed. The analysis was made for four most common occupant seated positions, such as: Normal Position with the torso against the seat back and the head looking straight ahead, Torso Lean forward position with the torso away from the seat back for approximately 10°, Head Flexed position with the head flexed forward approximately 20° from the normal position and Head-Flexed with Torso Lean forward position with the head flexed forward approximately 20° and torso 10° from the normal position. The comparative study included the analysis of capsular ligament deformation and the level of S-curvature of the cervical spine. The model developed predicted that Head Flexed seated position and Head-Flexed with Torso Lean forward seated position are most threatening for upper and lower cervical spine capsular ligament, respectively. As for the level of S-curvature, the model predicted that Head-Flexed with Torso Lean forward seated position would be most prone to neck injuries associated with it. This study demonstrated that the occupant seated position has a significant influence on potential whiplash injuries.

  20. Isospectral Trigonometric Pöschl-Teller Potentials with Position Dependent Mass Generated by Supersymmetry

    International Nuclear Information System (INIS)

    Santiago-Cruz, C

    2016-01-01

    In this work a position dependent mass Hamiltonian with the same spectrum of the trigonometric Pöschl-Teller one was constructed by means of the underlying potential algebra. The corresponding wave functions are determined by using the factorization method. A new family of isospectral potentials are constructed by applying a Darboux transformation. An example is presented in order to illustrate the formalism. (paper)

  1. Potential for false positive HIV test results with the serial rapid HIV testing algorithm

    Directory of Open Access Journals (Sweden)

    Baveewo Steven

    2012-03-01

    Full Text Available Abstract Background Rapid HIV tests provide same-day results and are widely used in HIV testing programs in areas with limited personnel and laboratory infrastructure. The Uganda Ministry of Health currently recommends the serial rapid testing algorithm with Determine, STAT-PAK, and Uni-Gold for diagnosis of HIV infection. Using this algorithm, individuals who test positive on Determine, negative to STAT-PAK and positive to Uni-Gold are reported as HIV positive. We conducted further testing on this subgroup of samples using qualitative DNA PCR to assess the potential for false positive tests in this situation. Results Of the 3388 individuals who were tested, 984 were HIV positive on two consecutive tests, and 29 were considered positive by a tiebreaker (positive on Determine, negative on STAT-PAK, and positive on Uni-Gold. However, when the 29 samples were further tested using qualitative DNA PCR, 14 (48.2% were HIV negative. Conclusion Although this study was not primarily designed to assess the validity of rapid HIV tests and thus only a subset of the samples were retested, the findings show a potential for false positive HIV results in the subset of individuals who test positive when a tiebreaker test is used in serial testing. These findings highlight a need for confirmatory testing for this category of individuals.

  2. Potential for false positive HIV test results with the serial rapid HIV testing algorithm.

    Science.gov (United States)

    Baveewo, Steven; Kamya, Moses R; Mayanja-Kizza, Harriet; Fatch, Robin; Bangsberg, David R; Coates, Thomas; Hahn, Judith A; Wanyenze, Rhoda K

    2012-03-19

    Rapid HIV tests provide same-day results and are widely used in HIV testing programs in areas with limited personnel and laboratory infrastructure. The Uganda Ministry of Health currently recommends the serial rapid testing algorithm with Determine, STAT-PAK, and Uni-Gold for diagnosis of HIV infection. Using this algorithm, individuals who test positive on Determine, negative to STAT-PAK and positive to Uni-Gold are reported as HIV positive. We conducted further testing on this subgroup of samples using qualitative DNA PCR to assess the potential for false positive tests in this situation. Of the 3388 individuals who were tested, 984 were HIV positive on two consecutive tests, and 29 were considered positive by a tiebreaker (positive on Determine, negative on STAT-PAK, and positive on Uni-Gold). However, when the 29 samples were further tested using qualitative DNA PCR, 14 (48.2%) were HIV negative. Although this study was not primarily designed to assess the validity of rapid HIV tests and thus only a subset of the samples were retested, the findings show a potential for false positive HIV results in the subset of individuals who test positive when a tiebreaker test is used in serial testing. These findings highlight a need for confirmatory testing for this category of individuals.

  3. Activation-induced proteolysis of cytoplasmic domain of zeta in T cell receptors and Fc receptors.

    Science.gov (United States)

    Taupin, J L; Anderson, P

    1994-12-01

    The CD3-T cell receptor (TCR) complex on T cells and the Fc gamma receptor type III (Fc gamma RIII)-zeta-gamma complex on natural killer cells are functionally analogous activation receptors that associate with a family of disulfide-linked dimers composed of the related subunits zeta and gamma. Immunochemical analysis of receptor complexes separated on two-dimensional diagonal gels allowed the identification of a previously uncharacterized zeta-p14 heterodimer. zeta-p14 is a component of both CD3-TCR and Fc gamma RIII-zeta-gamma. Peptide mapping analysis shows that p14 is structurally related to zeta, suggesting that it is either: (i) derived from zeta proteolytically or (ii) the product of an alternatively spliced mRNA. The observation that COS cells transformed with a cDNA encoding zeta express zeta-p14 supports the former possibility. The expression of CD3-TCR complexes including zeta-p14 increases following activation with phorbol 12-myristate 13-acetate or concanavalin A, suggesting that proteolysis of zeta may contribute to receptor modulation or desensitization.

  4. The semi-simple zeta function of quaternionic Shimura varieties

    CERN Document Server

    Reimann, Harry

    1997-01-01

    This monograph is concerned with the Shimura variety attached to a quaternion algebra over a totally real number field. For any place of good (or moderately bad) reduction, the corresponding (semi-simple) local zeta function is expressed in terms of (semi-simple) local L-functions attached to automorphic representations. In an appendix a conjecture of Langlands and Rapoport on the reduction of a Shimura variety in a very general case is restated in a slightly stronger form. The reader is expected to be familiar with the basic concepts of algebraic geometry, algebraic number theory and the theory of automorphic representation.

  5. The Riemann zeta-function theory and applications

    CERN Document Server

    Ivic, Aleksandar

    2003-01-01

    ""A thorough and easily accessible account.""-MathSciNet, Mathematical Reviews on the Web, American Mathematical Society. This extensive survey presents a comprehensive and coherent account of Riemann zeta-function theory and applications. Starting with elementary theory, it examines exponential integrals and exponential sums, the Voronoi summation formula, the approximate functional equation, the fourth power moment, the zero-free region, mean value estimates over short intervals, higher power moments, and omega results. Additional topics include zeros on the critical line, zero-density estim

  6. Exploring the Riemann zeta function 190 years from Riemann's birth

    CERN Document Server

    Nikeghbali, Ashkan; Rassias, Michael

    2017-01-01

    This book is concerned with the Riemann Zeta Function, its generalizations, and various applications to several scientific disciplines, including Analytic Number Theory, Harmonic Analysis, Complex Analysis and Probability Theory. Eminent experts in the field illustrate both old and new results towards the solution of long-standing problems and include key historical remarks. Offering a unified, self-contained treatment of broad and deep areas of research, this book will be an excellent tool for researchers and graduate students working in Mathematics, Mathematical Physics, Engineering and Cryptography.

  7. The Stokes phenomenon and the Lerch zeta function

    Directory of Open Access Journals (Sweden)

    R. B. Paris

    2016-05-01

    Full Text Available We examine the exponentially improved asymptotic expansion of the Lerch zeta function $L(\\lambda,a,s=\\sum_{n=0}^\\infty \\exp (2\\pi ni\\lambda/(n+a^s$ for large complex values of $a$, with $\\lambda$ and $s$ regarded as parameters. It is shown that an infinite number of subdominant exponential terms switch on across the Stokes lines $\\arg\\,a=\\pm\\fs\\pi$. In addition, it is found that the transition across the upper and lower imaginary $a$-axes is associated, in general, with unequal scales. Numerical calculations are presented to confirm the theoretical predictions.

  8. Fluctuations of quantum fields via zeta function regularization

    International Nuclear Information System (INIS)

    Cognola, Guido; Zerbini, Sergio; Elizalde, Emilio

    2002-01-01

    Explicit expressions for the expectation values and the variances of some observables, which are bilinear quantities in the quantum fields on a D-dimensional manifold, are derived making use of zeta function regularization. It is found that the variance, related to the second functional variation of the effective action, requires a further regularization and that the relative regularized variance turns out to be 2/N, where N is the number of the fields, thus being independent of the dimension D. Some illustrating examples are worked through. The issue of the stress tensor is also briefly addressed

  9. Introduction of an Elementary Method to Express $\\zeta(2n+1)$ in Terms of $\\zeta(2k)$ with $k\\geq 1$

    OpenAIRE

    Fujii, Kazuyuki; Suzuki, Tatsuo

    2008-01-01

    In this note we give the most elementary method (as far as we know) to express $\\zeta(2n+1)$ in terms of $\\{\\zeta(2k)|k\\geq 1\\}$. The method is based on only some elementary works by Leonhard Euler, so it is very instructive to non-experts or students.

  10. Algorithms for Some Euler-Type Identities for Multiple Zeta Values

    Directory of Open Access Journals (Sweden)

    Shifeng Ding

    2013-01-01

    Full Text Available Multiple zeta values are the numbers defined by the convergent series ζ(s1,s2,…,sk=∑n1>n2>⋯>nk>0(1/n1s1 n2s2⋯nksk, where s1, s2, …, sk are positive integers with s1>1. For k≤n, let E(2n,k be the sum of all multiple zeta values with even arguments whose weight is 2n and whose depth is k. The well-known result E(2n,2=3ζ(2n/4 was extended to E(2n,3 and E(2n,4 by Z. Shen and T. Cai. Applying the theory of symmetric functions, Hoffman gave an explicit generating function for the numbers E(2n,k and then gave a direct formula for E(2n,k for arbitrary k≤n. In this paper we apply a technique introduced by Granville to present an algorithm to calculate E(2n,k and prove that the direct formula can also be deduced from Eisenstein's double product.

  11. Ocular vestibular evoked myogenic potential in patients with benign paroxysmal positional vertigo

    Directory of Open Access Journals (Sweden)

    Mozhgan Masoom

    2014-06-01

    Full Text Available Background and Aim: Since utricle is the main damaged organ in benign paroxysmal positional vertigo (BPPV, ocular vestibular evoked myogenic potential (oVEMP may be an appropriate method to evaluate the utricule dysfunction and the effect of disease recurrence rate on it. This study aimed to record myogenic potential in patients with benign paroxysmal positional vertigo.Methods: In a cross-sectional study, ocular myogenic potential was recorded in 25 healthy subjects and 20 patients with benign paroxysmal positional vertigo using 500 Hz-tone bursts (95 dB nHL.Results: In the affected ear, mean amplitude was lower and mean threshold was higher than those in the unaffected ear and in the normal group (p<0.05. Mean amplitude asymmetry ratio of patients was more than the healthy subjects (p0.05. Frequencies of abnormal responses in the affected ears were higher than in unaffected ears and in the normal group (p<0.05. Furthermore, the patients with recurrent vertigo showed more abnormalities than the patients with non-recurrent (p=0.030.Conclusion: In the recurrent benign paroxysmal positional vertigo, ocular vestibular evoked myogenic potential showed more damage in the utricle, suggesting this response could be used to evaluate the patients with benign paroxysmal positional vertigo.

  12. Looking on the bright side in social anxiety: the potential benefit of promoting positive mental imagery.

    Directory of Open Access Journals (Sweden)

    Arnaud ePictet

    2014-02-01

    Full Text Available Current cognitive models of social phobia converge on the view that negative imagery is a key factor in the development and maintenance of the disorder. Research to date has predominantly focussed on the detrimental impact of negative imagery on cognitive bias and anxiety symptoms, while the potential benefit of promoting positive imagery has been relatively unexplored. Emerging evidence suggests however that positive imagery could have multiple benefits such as improving positive affect, self-esteem and positive interpretation bias, and enhancing social performance. The present article defends the view that combining bias induction with a repeated practice in generating positive imagery in a cognitive bias modification procedure could represent a promising area for future research and clinical innovation in social anxiety disorder.

  13. Potencial zeta de sulfatos de de bario y de estroncio

    Directory of Open Access Journals (Sweden)

    Edgar Delgado M.

    2010-06-01

    Full Text Available Por medio de la electroforesis se determinó las movilidades electroforéticas y los potenciales zeta del sulfato de bario a 25,0 °C como función de la fuerza iónica de NaCI, así como del Sulfato de estroncio en función de la fuerza iónica del cloruro de sodio y del pH. Se encontró que el amento de la fuerza iónica de NaCI causa un cambio del Potencial Zeta negativo del sulfato de estroncio a positivo con valor cero a aprox. 0,06 de fuerza iónica. El P.Z. del sulfato de estroncio es positivo a pH inferiores a aprox. 2,5 y negativo a pH superiores. El sulfato de bario presenta P.Z. negativas a fuerza iónicas de NaCI inferiores a aprox. 0.06 y PZ positivos a fuerzas iónicas mayores

  14. Can Eccentric Debris Disks Be Long-lived? A First Numerical Investigation and Application to Zeta(exp 2) Reticuli

    Science.gov (United States)

    Faramaz, V.; Beust, H.; Thebault, P.; Augereau, J.-C.; Bonsor, A.; delBurgo, C.; Ertel, S.; Marshall, J. P.; Milli, J.; Montesinos, B.; hide

    2014-01-01

    Context. Imaging of debris disks has found evidence for both eccentric and offset disks. One hypothesis is that they provide evidence for massive perturbers, for example, planets or binary companions, which sculpt the observed structures. One such disk was recently observed in the far-IR by the Herschel Space Observatory around Zeta2 Reticuli. In contrast with previously reported systems, the disk is significantly eccentric, and the system is several Gyr old. Aims. We aim to investigate the long-term evolution of eccentric structures in debris disks caused by a perturber on an eccentric orbit around the star. We hypothesise that the observed eccentric disk around Zeta2 Reticuli might be evidence of such a scenario. If so, we are able to constrain the mass and orbit of a potential perturber, either a giant planet or a binary companion. Methods. Analytical techniques were used to predict the effects of a perturber on a debris disk. Numerical N-body simulations were used to verify these results and further investigate the observable structures that may be produced by eccentric perturbers. The long-term evolution of the disk geometry was examined, with particular application to the Zeta2 Reticuli system. In addition, synthetic images of the disk were produced for direct comparison with Herschel observations. Results. We show that an eccentric companion can produce both the observed offsets and eccentric disks. These effects are not immediate, and we characterise the timescale required for the disk to develop to an eccentric state (and any spirals to vanish). For Zeta2 Reticuli, we derive limits on the mass and orbit of the companion required to produce the observations. Synthetic images show that the pattern observed around Zeta2 Reticuli can be produced by an eccentric disk seen close to edge-on, and allow us to bring additional constraints on the disk parameters of our model (disk flux and extent). Conclusions. We conclude that eccentric planets or stellar companions

  15. A study of the bound states for square potential wells with position-dependent mass

    International Nuclear Information System (INIS)

    Ganguly, A.; Kuru, S.; Negro, J.; Nieto, L.M.

    2006-01-01

    A potential well with position-dependent mass is studied for bound states. Applying appropriate matching conditions, a transcendental equation is derived for the energy eigenvalues. Numerical results are presented graphically and the variation of the energy of the bound states are calculated as a function of the well-width and mass

  16. CASE REPORT PET/CT-positive brown tumour – a potentially ...

    African Journals Online (AJOL)

    Brown tumor of bone: a potential source of false-positive Thallium-201 localization. J Nucl Med 1989; 30: 1264-1267. 4. Nassar GM, Ayus JC. Images in clinical medicine. Brown tumor in end stage renal disease. N Engl J Med. 1999; 341: 1652. 5. Keyser JS, Postma GN. Brown tumor of the mandible. Am J Otolaryngol 1996; ...

  17. A singular position-dependent mass particle in an infinite potential well

    International Nuclear Information System (INIS)

    Mustafa, Omar; Mazharimousavi, S. Habib

    2009-01-01

    An unusual singular position-dependent-mass particle in an infinite potential well is considered. The corresponding Hamiltonian is mapped through a point-canonical-transformation and an explicit correspondence between the target Hamiltonian and a Poeschl-Teller type reference Hamiltonian is obtained. New ordering ambiguity parametric setting are suggested

  18. Toward precise potential energy curves for diatomic molecules, derived from experimental line positions

    International Nuclear Information System (INIS)

    Helm, H.

    1984-01-01

    An inverted, first-order perturbation approach is used to derive potential energy curves for diatomic molecules from experimental line positions of molecular bands. The concept adopted here is based on the inverted perturbation analysis (IPA) proposed by Kozman and Hinze, but uses radial eigenfunctions of the trial potential energy curves as basis sets for the perturbation correction. Using molecular linepositions rather than molecular energy levels we circumvent the necessity of defining molecular constants for the molecule prior to the derivation of the potential energy curves. (Author)

  19. Harm avoidance in adolescents modulates late positive potentials during affective picture processing.

    Science.gov (United States)

    Zhang, Wenhai; Lu, Jiamei; Ni, Ziyin; Liu, Xia; Wang, Dahua; Shen, Jiliang

    2013-08-01

    Research in adults has shown that individual differences in harm avoidance (HA) modulate electrophysiological responses to affective stimuli. To determine whether HA in adolescents modulates affective information processing, we collected event-related potentials from 70 adolescents while they viewed 90 pictures from the Chinese affective picture system. Multiple regressions revealed that HA negatively predicted late positive potential (LPP) for positive pictures and positively predicted for negative pictures; however, HA did not correlate with LPP for neutral pictures. The results suggest that at the late evaluative stage, high-HA adolescents display attentional bias to negative pictures while low-HA adolescents display attentional bias to negative pictures. Moreover, these dissociable attentional patterns imply that individual differences in adolescents' HA modulate the late selective attention mechanism of affective information. Copyright © 2013. Published by Elsevier Ltd.

  20. Is Education a Fundamental Right? People's Lay Theories About Intellectual Potential Drive Their Positions on Education.

    Science.gov (United States)

    Savani, Krishna; Rattan, Aneeta; Dweck, Carol S

    2017-09-01

    Does every child have a fundamental right to receive a high-quality education? We propose that people's beliefs about whether "nearly everyone" or "only some people" have high intellectual potential drive their positions on education. Three studies found that the more people believed that nearly everyone has high potential, the more they viewed education as a fundamental human right. Furthermore, people who viewed education as a fundamental right, in turn (a) were more likely to support the institution of free public education, (b) were more concerned upon learning that students in the country were not performing well academically compared with students in peer nations, and (c) were more likely to support redistributing educational funds more equitably across wealthier and poorer school districts. The studies show that people's beliefs about intellectual potential can influence their positions on education, which can affect the future quality of life for countless students.

  1. Effects of positive potential in the catastrophe theory study of the point model for bumpy tori

    Energy Technology Data Exchange (ETDEWEB)

    Punjabi, A; Vahala, G [College of William and Mary, Williamsburg, VA (USA). Dept. of Physics

    1985-02-01

    With positive ambipolar potential, ion non-resonant neoclassical transport leads to increased particle confinement times. In certain regimes of filling pressure, microwave powers (ECRH and ICRH) and positive potential, new folds can now emerge from previously degenerate equilibrium surfaces allowing for distinct C, T, and M modes of operation. A comparison in the equilibrium fold structure is also made between (i) equal particle and energy confinement times, and (ii) particle confinement times enhanced over the energy confinement time. The nonlinear time evolution of these point model equations is considered and confirms the delay convention occurrences at the fold edges. It is clearly seen that the time-asymptotic equilibrium state is very sensitive, not only to the values of the control parameters (neutral density, ambipolar electrostatic potential, electron and ion cyclotron power densities) but also to the initial conditions on the plasma density, and electron and ion temperatures.

  2. Zeta-function regularization approach to finite temperature effects in Kaluza-Klein space-times

    International Nuclear Information System (INIS)

    Bytsenko, A.A.; Vanzo, L.; Zerbini, S.

    1992-01-01

    In the framework of heat-kernel approach to zeta-function regularization, in this paper the one-loop effective potential at finite temperature for scalar and spinor fields on Kaluza-Klein space-time of the form M p x M c n , where M p is p-dimensional Minkowski space-time is evaluated. In particular, when the compact manifold is M c n = H n /Γ, the Selberg tracer formula associated with discrete torsion-free group Γ of the n-dimensional Lobachevsky space H n is used. An explicit representation for the thermodynamic potential valid for arbitrary temperature is found. As a result a complete high temperature expansion is presented and the roles of zero modes and topological contributions is discussed

  3. Early visual evoked potentials are modulated by eye position in humans induced by whole body rotations

    Directory of Open Access Journals (Sweden)

    Petit Laurent

    2004-09-01

    Full Text Available Abstract Background To reach and grasp an object in space on the basis of its image cast on the retina requires different coordinate transformations that take into account gaze and limb positioning. Eye position in the orbit influences the image's conversion from retinotopic (eye-centered coordinates to an egocentric frame necessary for guiding action. Neuroimaging studies have revealed eye position-dependent activity in extrastriate visual, parietal and frontal areas that is along the visuo-motor pathway. At the earliest vision stage, the role of the primary visual area (V1 in this process remains unclear. We used an experimental design based on pattern-onset visual evoked potentials (VEP recordings to study the effect of eye position on V1 activity in humans. Results We showed that the amplitude of the initial C1 component of VEP, acknowledged to originate in V1, was modulated by the eye position. We also established that putative spontaneous small saccades related to eccentric fixation, as well as retinal disparity cannot explain the effects of changing C1 amplitude of VEP in the present study. Conclusions The present modulation of the early component of VEP suggests an eye position-dependent activity of the human primary visual area. Our findings also evidence that cortical processes combine information about the position of the stimulus on the retinae with information about the location of the eyes in their orbit as early as the stage of primary visual area.

  4. RNA secondary structures in a polymer-zeta model how foldings should be shaped for sparsification to establish a linear speedup

    DEFF Research Database (Denmark)

    Jin, Emma Yu; Nebel, M. E.

    2016-01-01

    that the corresponding conditional probabilities behave according to a polymer-zeta probability model. We show that even if some of the structural parameters exhibit an almost realistic behavior on average, the expected shape of a folding in that model must be assumed to highly differ from those observed in nature. More...... sparsification) may reduce the runtime to n2 on average, assuming that nucleotides of distance d form a hydrogen bond (i.e. are paired) with probability (Formula Presented.) for some constants b > 0, c > 1. The latter is called the polymer-zeta model and plays a crucial role in speeding up the above mentioned...... algorithm. In this paper we discuss the application of the polymer-zeta property for the analysis of sparsification, showing that it must be applied conditionally on first and last positions to pair. Afterwards, we will investigate the combinatorics of RNA secondary structures assuming...

  5. On Montgomery's pair correlation conjecture to the zeros of Riedmann zeta function

    OpenAIRE

    Li, Pei

    2005-01-01

    In this thesis, we are interested in Montgomery's pair correlation conjecture which is about the distribution of.the spacings between consecutive zeros of the Riemann Zeta function. Our goal is to explain and study Montgomery's pair correlation conjecture and discuss its connection with the random matrix theory. In Chapter One, we will explain how to define the Ftiemann Zeta function by using the analytic continuation. After this, several classical properties of the Ftiemann Zeta function wil...

  6. A Possible Massive Asteroid Belt Around $\\zeta$ Lep

    CERN Document Server

    Chen Chuan Hung

    2001-01-01

    We have used the Keck I telescope to image at 11.7 microns and 17.9 microns the dust emission around zeta Lep, a main sequence A-type star at 21.5 pc from the Sun with an infrared excess. The excess is at most marginally resolved at 17.9 microns. The dust distance from the star is probably less than or equal to 6 AU, although some dust may extend to 9 AU. The mass of observed dust is \\~10^22 g. Since the lifetime of dust particles is about 10,000 years because of the Poytning-Robertson effect, we robustly estimate at least 4 10^26 g must reside in parent bodies which may be asteroids if the system is in a steady state and has an age of ~300 Myr. This mass is approximately 200 times that contained within the main asteroid belt in our solar system.

  7. Dirac Particle for the Position Dependent Mass in the Generalized Asymmetric Woods-Saxon Potential

    Directory of Open Access Journals (Sweden)

    Soner Alpdoğan

    2014-01-01

    Full Text Available The one-dimensional Dirac equation with position dependent mass in the generalized asymmetric Woods-Saxon potential is solved in terms of the hypergeometric functions. The transmission and reflection coefficients are obtained by considering the one-dimensional electric current density for the Dirac particle and the equation describing the bound states is found by utilizing the continuity conditions of the obtained wave function. Also, by using the generalized asymmetric Woods-Saxon potential solutions, the scattering states are found out without making calculation for the Woods-Saxon, Hulthen, cusp potentials, and so forth, which are derived from the generalized asymmetric Woods-Saxon potential and the conditions describing transmission resonances and supercriticality are achieved. At the same time, the data obtained in this work are compared with the results achieved in earlier studies and are observed to be consistent.

  8. Is education a fundamental right? People's lay theories about intellectual potential drive their positions on education

    OpenAIRE

    Savani, K; Rattan, A; Dweck, C S

    2017-01-01

    Does every child have a fundamental right to receive a high quality education? We propose that people’s beliefs about whether “nearly everyone” or “only some people” have high intellectual potential drive their positions on education. Three studies found that the more people believed that nearly everyone has high potential, the more they viewed education as a fundamental human right. Further, people who viewed education as a fundamental right, in turn, (1) were more likely to support the inst...

  9. Relativistic total energy and chemical potential of heavy atoms and positive ions

    International Nuclear Information System (INIS)

    Hill, S.H.; Grout, P.J.; March, N.H.

    1984-01-01

    The relativistic Thomas-Fermi theory, with a finite nucleus, is used to study the variation of the chemical potential μ with atomic number Z and number of electrons N (N <= Z). The difference between the total energy of positive ions and that of the corresponding neutral atom has been obtained. The scaling predictions are confirmed by numerical calculations. The first principles calculation of the relativistic Thomas-Fermi total energy of neutral atoms is also studied. (author)

  10. Dissociating the Influence of Affective Word Content and Cognitive Processing Demands on the Late Positive Potential.

    Science.gov (United States)

    Nowparast Rostami, Hadiseh; Ouyang, Guang; Bayer, Mareike; Schacht, Annekathrin; Zhou, Changsong; Sommer, Werner

    2016-01-01

    The late positive potential (LPP) elicited by affective stimuli in the event-related brain potential (ERP) is often assumed to be a member of the P3 family. The present study addresses the relationship of the LPP to the classic P3b in a published data set, using a non-parametric permutation test for topographical comparisons, and residue iteration decomposition to assess the temporal features of the LPP and the P3b by decomposing the ERP into several component clusters according to their latency variability. The experiment orthogonally manipulated arousal and valence of words, which were either read or judged for lexicality. High-arousing and positive valenced words induced a larger LPP than low-arousing and negative valenced words, respectively, and the LDT elicited a larger P3b than reading. The experimental manipulation of arousal, valence, and task yielded main effects without any interactions on ERP amplitude in the LPP/P3b time range. The arousal and valence effects partially differed from the task effect in scalp topography; in addition, whereas the late positive component elicited by affective stimuli, defined as LPP, was stimulus-locked, the late positive component elicited by task demand, defined as P3b, was mainly latency-variable. Therefore LPP and P3b manifest different subcomponents.

  11. Two-dimensional potential and charge distributions of positive surface streamer

    International Nuclear Information System (INIS)

    Tanaka, Daiki; Matsuoka, Shigeyasu; Kumada, Akiko; Hidaka, Kunihiko

    2009-01-01

    Information on the potential and the field profile along a surface discharge is required for quantitatively discussing and clarifying the propagation mechanism. The sensing technique with a Pockels crystal has been developed for directly measuring the potential and electric field distribution on a dielectric material. In this paper, the Pockels sensing system consists of a pulse laser and a CCD camera for measuring the instantaneous two-dimensional potential distribution on a 25.4 mm square area with a 50 μm sampling pitch. The temporal resolution is 3.2 ns which is determined by the pulse width of the laser emission. The transient change in the potential distribution of a positive surface streamer propagating in atmospheric air is measured with this system. The electric field and the charge distributions are also calculated from the measured potential profile. The propagating direction component of the electric field near the tip of the propagating streamer reaches 3 kV mm -1 . When the streamer stops, the potential distribution along a streamer forms an almost linear profile with the distance from the electrode, and its gradient is about 0.5 kV mm -1 .

  12. Position-Dependent Mass Schrödinger Equation for the Morse Potential

    International Nuclear Information System (INIS)

    Ovando, G; Peña, J J; Morales, J; López-Bonilla, J

    2017-01-01

    The position dependent mass Schrödinger equation (PDMSE) has a wide range of quantum applications such as the study of semiconductors, quantum wells, quantum dots and impurities in crystals, among many others. On the other hand, the Morse potential is one of the most important potential models used to study the electronic properties of diatomic molecules. In this work, the solution of the effective mass one-dimensional Schrödinger equation for the Morse potential is presented. This is done by means of the canonical transformation method in algebraic form. The PDMSE is solved for any model of the proposed kinetic energy operators as for example the BenDaniel-Duke, Gora-Williams, Zhu-Kroemer or Li-Kuhn. Also, in order to solve the PDMSE with Morse potential, we consider a superpotential leading to a special form of the exactly solvable Schrödinger equation of constant mass for a class of multiparameter exponential-type potential along with a proper mass distribution. The proposed approach is general and can be applied in the search of new potentials suitable on science of materials by looking into the viable choices of the mass function. (paper)

  13. Zeta Function Expression of Spin Partition Functions on Thermal AdS3

    Directory of Open Access Journals (Sweden)

    Floyd L.Williams

    2015-07-01

    Full Text Available We find a Selberg zeta function expression of certain one-loop spin partition functions on three-dimensional thermal anti-de Sitter space. Of particular interest is the partition function of higher spin fermionic particles. We also set up, in the presence of spin, a Patterson-type formula involving the logarithmic derivative of zeta.

  14. Note on asymptotic series expansions for the derivative of the Hurwitz zeta function and related functions

    International Nuclear Information System (INIS)

    Rudaz, S.

    1990-01-01

    Asymptotic series for the Hurwitz zeta function, its derivative, and related functions (including the Riemann zeta function of odd integer argument) are derived as an illustration of a simple, direct method of broad applicability, inspired by the calculus of finite differences

  15. Generalized Riemann zeta-function regularization and Casimir energy for a piecewise uniform string

    International Nuclear Information System (INIS)

    Li Xinzhou; Shi Xin; Zhang Jianzu.

    1990-12-01

    The generalized zeta-function techniques will be utilized to investigate the Casimir energy for the transverse oscillations of a piecewise uniform closed string. We find that zeta-function regularization method can lead straightforwardly to a correct result. (author). 6 refs

  16. The potential of positive deviance approach for the sustainable control of neglected tropical diseases.

    Science.gov (United States)

    Ong, Ken Ing Cherng; Araki, Hitomi; Kano, Shigeyuki; Jimba, Masamine

    2016-01-01

    Neglected tropical diseases (NTDs) have gained much attention in recent years due to the support from various agencies. However, the main approach to combat NTDs has been to cure rather than to prevent. As many NTD infections are closely linked with human behaviors such as hygienic practices and tradition, behavior change is also very crucial to prevent relapse or reinfection. Therefore, we would like to suggest a potential new approach-the positive deviance approach-to tackle NTDs by focusing on the preventive phase. What makes this approach unique is that the solution comes from the affected population themselves and not from the expert outsiders. Preventive chemotherapy that relies on outside aid has serious sustainability issues as reinfection is also high after the aid program has ended. Learning from the success story in Vietnam on preventing childhood malnutrition, the positive deviance approach could end the spread of NTDs once and for all by making full use of the available local solutions.

  17. Visual evoked potentials show strong positive association with intracranial pressure in patients with cryptococcal meningitis

    Directory of Open Access Journals (Sweden)

    Marcelo Adriano da Cunha Silva Vieira

    2015-04-01

    Full Text Available Objective : To verify the relationship between intracranial pressure and flash visual evoked potentials (F-VEP in patients with cryptococcal meningitis. Method The sample included adults diagnosed with cryptococcal meningitis admitted at a reference hospital for infectious diseases. The patients were subjected to F-VEP tests shortly before lumbar puncture. The Pearson’s linear correlation coefficient was calculated and the linear regression analysis was performed. Results : Eighteen individuals were subjected to a total of 69 lumbar punctures preceded by F-VEP tests. At the first lumbar puncture performed in each patient, N2 latency exhibited a strong positive correlation with intracranial pressure (r = 0.83; CI = 0.60 - 0.94; p < 0.0001. The direction of this relationship was maintained in subsequent punctures. Conclusion : The intracranial pressure measured by spinal tap manometry showed strong positive association with the N2 latency F-VEP in patients with cryptococcal meningitis.

  18. Personality and emotional processing: A relationship between extraversion and the late positive potential in adolescence.

    Science.gov (United States)

    Speed, Brittany C; Nelson, Brady D; Perlman, Greg; Klein, Daniel N; Kotov, Roman; Hajcak, Greg

    2015-08-01

    Neuroticism and extraversion are multifaceted affective-laden personality traits that have been associated with major depressive disorder (MDD). Research and theory have argued that extraversion, and particularly its facet positive emotionality, is specific to MDD, while neuroticism is common across internalizing disorders. Converging evidence has suggested that MDD is associated with reduced engagement with emotional stimuli, but it remains unclear whether either extraversion, neuroticism, or both modulate reactivity to emotional cues. The late positive potential (LPP) is an event-related brain potential that is uniquely suited to assess engagement with emotional stimuli because it reflects sustained attention toward emotional content. The current study examined the LPP in relation to personality traits that may confer risk for depression by examining the relationship between the LPP and both neuroticism and extraversion in never-depressed adolescent girls. Specifically, 550 girls aged 13.5-15.5 with no lifetime history of depression completed an emotional picture-viewing task, and the LPP was measured in response to neutral, pleasant, and unpleasant pictures. Personality traits were gathered via self- and informant report. Results indicated that high extraversion was associated with a potentiated LPP to emotional pictures-and this effect was accounted for by positive emotionality in particular. In contrast, there was no association between the LPP and neuroticism or its facets. The present study is one of the first to demonstrate that extraversion is associated with variation in neural indices of emotional picture processing, similar to what has been observed among individuals with depression and at high risk for depression. © 2015 Society for Psychophysiological Research.

  19. Detection of interstellar (C-13)N toward Zeta Ophiuchi

    International Nuclear Information System (INIS)

    Crane, P.; Hegyi, D.J.

    1988-01-01

    Observations of a diffuse interstellar cloud toward Zeta Oph, obtained with resolution 100,000-150,000 near the 3874.608-A R(0) line of (C-12)N using a coude echelle spectrograph on the 1.4-m telescope at ESO during 1984 and 1985, are reported. Data from 54 20-min runs were fitted to Gaussian line shapes using the line center, depth, and width of the R(0) and R(1) lines of (C-12)N and the line center and depth of the R(0) line of (C-13)N as fitting parameters. The (C-13)N R(0) line, with equivalent width 0.190 + or - 0.020 mA, was detected 173.7 + or - 0.8 mA to the red of (C-12)N R(0); the corresponding isotope abundance ratio, (C-12)N/(C-13)N = 47.3 + 5.5 or -4.4, is shown to be in good agreement with previous measurements for CH(+) (Hawkins et al., 1985). 13 references

  20. Beyond Massive MIMO: The Potential of Positioning With Large Intelligent Surfaces

    Science.gov (United States)

    Hu, Sha; Rusek, Fredrik; Edfors, Ove

    2018-04-01

    We consider the potential for positioning with a system where antenna arrays are deployed as a large intelligent surface (LIS), which is a newly proposed concept beyond massive-MIMO where future man-made structures are electronically active with integrated electronics and wireless communication making the entire environment \\lq\\lq{}intelligent\\rq\\rq{}. In a first step, we derive Fisher-information and Cram\\'{e}r-Rao lower bounds (CRLBs) in closed-form for positioning a terminal located perpendicular to the center of the LIS, whose location we refer to as being on the central perpendicular line (CPL) of the LIS. For a terminal that is not on the CPL, closed-form expressions of the Fisher-information and CRLB seem out of reach, and we alternatively find approximations of them which are shown to be accurate. Under mild conditions, we show that the CRLB for all three Cartesian dimensions ($x$, $y$ and $z$) decreases quadratically in the surface-area of the LIS, except for a terminal exactly on the CPL where the CRLB for the $z$-dimension (distance from the LIS) decreases linearly in the same. In a second step, we analyze the CRLB for positioning when there is an unknown phase $\\varphi$ presented in the analog circuits of the LIS. We then show that the CRLBs are dramatically increased for all three dimensions but decrease in the third-order of the surface-area. Moreover, with an infinitely large LIS the CRLB for the $z$-dimension with an unknown $\\varphi$ is 6 dB higher than the case without phase uncertainty, and the CRLB for estimating $\\varphi$ converges to a constant that is independent of the wavelength $\\lambda$. At last, we extensively discuss the impact of centralized and distributed deployments of LIS, and show that a distributed deployment of LIS can enlarge the coverage for terminal-positioning and improve the overall positioning performance.

  1. Incongruence between Verbal and Non-Verbal Information Enhances the Late Positive Potential.

    Science.gov (United States)

    Morioka, Shu; Osumi, Michihiro; Shiotani, Mayu; Nobusako, Satoshi; Maeoka, Hiroshi; Okada, Yohei; Hiyamizu, Makoto; Matsuo, Atsushi

    2016-01-01

    Smooth social communication consists of both verbal and non-verbal information. However, when presented with incongruence between verbal information and nonverbal information, the relationship between an individual judging trustworthiness in those who present the verbal-nonverbal incongruence and the brain activities observed during judgment for trustworthiness are not clear. In the present study, we attempted to identify the impact of incongruencies between verbal information and facial expression on the value of trustworthiness and brain activity using event-related potentials (ERP). Combinations of verbal information [positive/negative] and facial expressions [smile/angry] expressions were presented randomly on a computer screen to 17 healthy volunteers. The value of trustworthiness of the presented facial expression was evaluated by the amount of donation offered by the observer to the person depicted on the computer screen. In addition, the time required to judge the value of trustworthiness was recorded for each trial. Using electroencephalography, ERP were obtained by averaging the wave patterns recorded while the participants judged the value of trustworthiness. The amount of donation offered was significantly lower when the verbal information and facial expression were incongruent, particularly for [negative × smile]. The amplitude of the early posterior negativity (EPN) at the temporal lobe showed no significant difference between all conditions. However, the amplitude of the late positive potential (LPP) at the parietal electrodes for the incongruent condition [negative × smile] was higher than that for the congruent condition [positive × smile]. These results suggest that the LPP amplitude observed from the parietal cortex is involved in the processing of incongruence between verbal information and facial expression.

  2. On the $a$-points of the derivatives of the Riemann zeta function

    OpenAIRE

    Onozuka, Tomokazu

    2016-01-01

    We prove three results on the $a$-points of the derivatives of the Riemann zeta function. The first result is a formula of the Riemann-von Mangoldt type; we estimate the number of the $a$-points of the derivatives of the Riemann zeta function. The second result is on certain exponential sum involving $a$-points. The third result is an analogue of the zero density theorem. We count the $a$-points of the derivatives of the Riemann zeta function in $1/2-(\\log\\log T)^2/\\log T

  3. Galectin-7 Expression Potentiates HER-2-Positive Phenotype in Breast Cancer.

    Directory of Open Access Journals (Sweden)

    Andrée-Anne Grosset

    Full Text Available HER-2 positive tumors are among the most aggressive subtypes of breast cancer and are frequently associated with metastasis and poor outcome. As with other aggressive subtypes of breast cancer, these tumors are associated with abnormally high expression of galectin-7 (gal-7, which confers metastatic breast tumor cells with increased invasive behavior. Although previous studies in the rat model of breast tumorigenesis have shown that gal-7 is also increased in primary breast tumor, its contribution to the development of the primary breast tumors remains unclear. In the present work, we have used genetically-engineered gal-7-deficient mice to examine the role of gal-7 in the development of the mammary gland and of breast cancer. Using histological and immunohistological analysis of whole mammary glands at different stages of development, we detected no significant changes between normal and gal-7-deficient mice. To test the involvement of gal-7 in breast cancer, we next examined the effects of loss of gal-7 on mammary tumor development by crossing gal-7-deficient mice with the mammary tumor transgenic mouse strain FVB-Tg(MMTV-Erbb2NK1Mul/J. Finally, assessment of mice survival and tumor volume showed a delay of mammary tumor growth in the absence of systemic gal-7. These data suggest that gal-7 could potentiate the phenotype of HER-2 positive primary breast cancer.

  4. Salpeter equation in position space: Numerical solution for arbitrary confining potentials

    International Nuclear Information System (INIS)

    Nickisch, L.J.; Durand, L.; Durand, B.

    1984-01-01

    We present and test two new methods for the numerical solution of the relativistic wave equation [(-del 2 +m 1 2 )/sup 1/2/+(-del 2 +m 2 2 )/sup 1/2/+V(r)-M]psi( r ) = 0, which appears in the theory of relativistic quark-antiquark bound states. Our methods work directly in position space, and hence have the desirable features that we can vary the potential V(r) locally in fitting the qq-bar mass spectrum, and can easily build in the expected behavior of V for r→0,infinity. Our first method converts the nonlocal square-root operators to mildly singular integral operators involving hyperbolic Bessel functions. The resulting integral equation can be solved numerically by matrix techniques. Our second method approximates the square-root operators directly by finite matrices. Both methods converge rapidly with increasing matrix size (the square-root matrix method more rapidly) and can be used in fast-fitting routines. We present some tests for oscillator and Coulomb interactions, and for the realistic Coulomb-plus-linear potential used in qq-bar phenomenology

  5. Beta receptor-mediated modulation of the late positive potential in humans.

    Science.gov (United States)

    de Rover, Mischa; Brown, Stephen B R E; Boot, Nathalie; Hajcak, Greg; van Noorden, Martijn S; van der Wee, Nic J A; Nieuwenhuis, Sander

    2012-02-01

    Electrophysiological studies have identified a scalp potential, the late positive potential (LPP), which is modulated by the emotional intensity of observed stimuli. Previous work has shown that the LPP reflects the modulation of activity in extrastriate visual cortical structures, but little is known about the source of that modulation. The present study investigated whether beta-adrenergic receptors are involved in the generation of the LPP. We used a genetic individual differences approach (experiment 1) and a pharmacological manipulation (experiment 2) to test the hypothesis that the LPP is modulated by the activation of β-adrenergic receptors. In experiment 1, we found that LPP amplitude depends on allelic variation in the β1-receptor gene polymorphism. In experiment 2, we found that LPP amplitude was modulated by the β-blocker propranolol in a direction dependent on subjects' level of trait anxiety: In participants with lower trait anxiety, propranolol led to a (nonsignificant) decrease in the LPP modulation; in participants with higher trait anxiety, propranolol increased the emotion-related LPP modulation. These results provide initial support for the hypothesis that the LPP reflects the downstream effects, in visual cortical areas, of β-receptor-mediated activation of the amygdala.

  6. Vestibular evoked myogenic potentials and digital vectoelectronystagmography's study in patients with benign paroxysmal positional vertigo

    Directory of Open Access Journals (Sweden)

    Lira-Batista, Marta Maria da Silva

    2013-04-01

    Full Text Available Introduction: Benign Paroxysmal Positional Vertigo (BPPV is a very common vestibular disorder characterized by brief but intense attacks of rotatory vertigo triggered by simple rapid movement of the head. The integrity of the vestibular pathways can be assessed using tests such as digital vectoelectronystagmography (VENG and vestibular evoked myogenic potentials (VEMP. Aim: This study aimed to determine the VEMP findings with respect to latency, amplitude, and waveform peak to peak and the results of the oculomotor and vestibular components of VENG in patients with BPPV. Method: Although this otoneurological condition is quite common, little is known of the associated VEMP and VENG changes, making it important to research and describe these results. Results: We examined the records of 4438 patients and selected 35 charts after applying the inclusion and exclusion criteria. Of these, 26 patients were women and 9 men. The average age at diagnosis was 52.7 years, and the most prevalent physiological cause, accounting for 97.3% of cases, was ductolithiasis. There was a statistically significant association between normal hearing and mild contralateral sensorineural hearing loss. The results of the oculomotor tests were within the normal reference ranges for all subjects. Patients with BPPV exhibited symmetrical function of the semicircular canals in their synergistic pairs (p < 0.001. The caloric test showed statistically normal responses from the lateral canals. The waveforms of all patients were adequate, but the VEMP results for the data-crossing maneuver with positive positioning showed a trend toward a relationship for the left ear Lp13. There was also a trend towards an association between normal reflexes in the caloric test and the inter-peak VEMP of the left ear. It can be concluded that although there are some differences between the average levels of the VENG and VEMP results, these differences were not statistically significant

  7. Zeta-function regularization of the quantum fluctuations around the Yang-Mills pseudoparticle

    International Nuclear Information System (INIS)

    Chadha, S.; Di Vecchia, P.; D'Adda, A.; Nicodemi, F.

    1977-01-01

    The hypersphere stereographic projection and the zeta-function regularization procedure are used to compute the one loop correction around the Yang-Mills pseudoparticle with scalars and fermions in an arbitrary representation of the SU(2) gauge group. (Auth.)

  8. Instabilities of the zeta-function regularization in the presence of symmetries

    International Nuclear Information System (INIS)

    Rasetti, M.

    1980-01-01

    The zeta-function regularization method requires the calculation of the spectrum-generating function zeta sub(M) of a generic real, elliptic, self-adjoint differential operator on a manifold M. An asymptotic expansion for zeta sub(M) is given for the class of all symmetric spaces of rank 1, sufficient to compute its Mellin transform and deduce the regularization of the corresponding quadratic path integrals. The summability properties of the generalized zeta-function introduce physical instabilities in the system as negative specific heat. The technique (and the instability as well) is shown to hold - under the assumed symmetry properties - in any dimension (preserving both the global and local properties of the manifold, as opposed to the dimensional regularization, where one adds extra flat dimensions only). (author)

  9. Zeta function of self-adjoint operators on surfaces of revolution

    International Nuclear Information System (INIS)

    Lu, Tianshi; Jeffres, Thalia; Kirsten, Klaus

    2015-01-01

    In this article we analyze the zeta function for the Laplace operator on a surface of revolution. A variety of boundary conditions, separated and unseparated, are considered. Formulas for several residues and values of the zeta function as well as for the determinant of the Laplacian are obtained. The analysis is based upon contour integration techniques in combination with a WKB analysis of solutions of related initial value problems. (paper)

  10. Probability laws related to the Jacobi theta and Riemann zeta function and Brownian excursions

    OpenAIRE

    Biane, P.; Pitman, J.; Yor, M.

    1999-01-01

    This paper reviews known results which connect Riemann's integral representations of his zeta function, involving Jacobi's theta function and its derivatives, to some particular probability laws governing sums of independent exponential variables. These laws are related to one-dimensional Brownian motion and to higher dimensional Bessel processes. We present some characterizations of these probability laws, and some approximations of Riemann's zeta function which are related to these laws.

  11. Antimicrobial-Resistance Genetic Markers in Potentially Pathogenic Gram Positive Cocci Isolated from Brazilian Soft Cheese.

    Science.gov (United States)

    Resende, Juliana Alves; Fontes, Cláudia Oliveira; Ferreira-Machado, Alessandra Barbosa; Nascimento, Thiago César; Silva, Vânia Lúcia; Diniz, Cláudio Galuppo

    2018-02-01

    Although most Brazilian dairy products meet high technological standards, there are quality issues regarding milk production, which may reduce the final product quality. Several microbial species may contaminate milk during manufacture and handling. If antimicrobial usage remains uncontrolled in dairy cattle, the horizontal transfer of antimicrobial resistance genes in foodstuffs may be of particular concern for both food producers and dairy industry. This study focused on the evaluation of putative Gram positive cocci in Minas cheese and of antimicrobial and biocide resistance genes among the isolated bacteria. Representative samples of 7 different industrially trademarked Minas cheeses (n = 35) were processed for selective culture and isolation of Gram positive cocci. All isolated bacteria were identified by DNA sequencing of the 16S rRNA gene. Antimicrobial resistance genes were screened by PCR. Overall, 208 strains were isolated and identified as follows: Enterococcus faecalis (47.6%), Macrococcus caseolyticus (18.3%), Enterococcus faecium (11.5%), Enterococcus caseliflavus (7.7%), Staphylococcus haemolyticus (7.2%), Staphylococcus aureus (4.3%), Staphylococcus epidermidis (2.9%), and Enterococcus hirae (0.5%). The genetic markers mecA (78.0%) and smr (71.4%) were the most prevalent, but others were also detected, such as blaZ (65.2%), msrA (60.9%), msrB (46.6%), linA (54.7%), and aacA-aphD (47.6%). The occurrence of opportunist pathogenic bacteria harboring antimicrobial resistance markers in the cheese samples are of special concern, since these bacteria are not considered harmful contaminating agents according to the Brazilian sanitary regulations. However, they are potentially pathogenic bacteria and the cheese may be considered a reservoir for antimicrobial resistance genes available for horizontal transfer through the food chain, manufacturing personnel and consumers. © 2018 Institute of Food Technologists®.

  12. Diacylglycerol kinase zeta positively controls the development of iNKT-17 cells.

    Directory of Open Access Journals (Sweden)

    Jinhong Wu

    Full Text Available Invariant natural killer T (iNKT cells play important roles in bridging innate and adaptive immunity via rapidly producing a variety of cytokines. A small subset of iNKT cells produces IL-17 and is generated in the thymus during iNKT-cell ontogeny. The mechanisms that control the development of these IL-17-producing iNKT-17 cells (iNKT-17 are still not well defined. Diacylglycerol kinase ζ (DGKζ belongs to a family of enzymes that catalyze the phosphorylation and conversion of diacylglycerol to phosphatidic acid, two important second messengers involved in signaling from numerous receptors. We report here that DGKζ plays an important role in iNKT-17 development. A deficiency of DGKζ in mice causes a significant reduction of iNKT-17 cells, which is correlated with decreased RORγt and IL-23 receptor expression. Interestingly, iNKT-17 defects caused by DGKζ deficiency can be corrected in chimeric mice reconstituted with mixed wild-type and DGKζ-deficient bone marrow cells. Taken together, our data identify DGKζ as an important regulator of iNKT-17 development through iNKT-cell extrinsic mechanisms.

  13. Working memory load reduces the late positive potential and this effect is attenuated with increasing anxiety.

    Science.gov (United States)

    MacNamara, Annmarie; Ferri, Jamie; Hajcak, Greg

    2011-09-01

    Emotion regulation decreases the processing of arousing stimuli, as indexed by the late positive potential (LPP), an electrocortical component that varies in amplitude with emotional arousal. Emotion regulation increases activity in the prefrontal areas associated with cognitive control, including the dosolateral prefrontal cortex (DLPFC). The present study manipulated working memory load, known to activate the DLPFC, and recorded the LPP elicited by aversive and neutral IAPS pictures presented during the retention interval. The LPP was larger on low-load compared to high-load trials, and on trials with aversive compared to neutral pictures. These LPP data suggest that emotional content and working memory load have opposing effects on attention to distracting stimuli. State anxiety was associated with reduced modulation of the LPP by working memory load. Results are discussed in terms of competition for attention between emotion and cognition and suggest a relationship between DLPFC activation and the allocation of attentional resources to distracting visual stimuli-a relationship that may be disrupted with increasing anxiety.

  14. Decision ambiguity is mediated by a late positive potential originating from cingulate cortex.

    Science.gov (United States)

    Sun, Sai; Zhen, Shanshan; Fu, Zhongzheng; Wu, Daw-An; Shimojo, Shinsuke; Adolphs, Ralph; Yu, Rongjun; Wang, Shuo

    2017-08-15

    People often make decisions in the face of ambiguous information, but it remains unclear how ambiguity is represented in the brain. We used three types of ambiguous stimuli and combined EEG and fMRI to examine the neural representation of perceptual decisions under ambiguity. We identified a late positive potential, the LPP, which differentiated levels of ambiguity, and which was specifically associated with behavioral judgments about choices that were ambiguous, rather than passive perception of ambiguous stimuli. Mediation analyses together with two further control experiments confirmed that the LPP was generated only when decisions are made (not during mere perception of ambiguous stimuli), and only when those decisions involved choices on a dimension that is ambiguous. A further control experiment showed that a stronger LPP arose in the presence of ambiguous stimuli compared to when only unambiguous stimuli were present. Source modeling suggested that the LPP originated from multiple loci in cingulate cortex, a finding we further confirmed using fMRI and fMRI-guided ERP source prediction. Taken together, our findings argue for a role of an LPP originating from cingulate cortex in encoding decisions based on task-relevant perceptual ambiguity, a process that may in turn influence confidence judgment, response conflict, and error correction. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Application of positive matrix factorization to identify potential sources of PAHs in soil of Dalian, China

    International Nuclear Information System (INIS)

    Wang Degao; Tian Fulin; Yang Meng; Liu Chenlin; Li Yifan

    2009-01-01

    Soil derived sources of polycyclic aromatic hydrocarbons (PAHs) in the region of Dalian, China were investigated using positive matrix factorization (PMF). Three factors were separated based on PMF for the statistical investigation of the datasets both in summer and winter. These factors were dominated by the pattern of single sources or groups of similar sources, showing seasonal and regional variations. The main sources of PAHs in Dalian soil in summer were the emissions from coal combustion average (46%), diesel engine (30%), and gasoline engine (24%). In winter, the main sources were the emissions from coal-fired boiler (72%), traffic average (20%), and gasoline engine (8%). These factors with strong seasonality indicated that coal combustion in winter and traffic exhaust in summer dominated the sources of PAHs in soil. These results suggested that PMF model was a proper approach to identify the sources of PAHs in soil. - PMF model is a proper approach to identify potential sources of PAHs in soil based on the PAH profiles measured in the field and those published in the literature.

  16. Abscisic Acid Accumulates at Positive Turgor Potential in Excised Soybean Seedling Growing Zones 1

    Science.gov (United States)

    Creelman, Robert A.; Mullet, John E.

    1991-01-01

    Abscisic acid (ABA) accumulated in soybean (Glycine max [L.] Merr. cv Williams) hypocotyl elongating regions when seedlings were transferred to low water potential vermiculite (Ψ = −0.3 megapascals) even though positive turgor is retained in this tissue. Accumulation of ABA in growing zones could occur from de novo biosynthesis within this tissue or transport from adjacent nongrowing zones. Both growing and nongrowing hypocotyl and root tissues accumulated significant levels of ABA when excised and dehydrated to reduce turgor. Surprisingly, excised growing zones (which experienced no water loss) also accumulated ABA when incubated in darkness for 4 hours at 100% relative humidity and 29°C. Induction of ABA accumulation in the excised elongating region of the hypocotyl was not caused by disruption of root pressure or wounding. While excision of hypocotyl elongating regions induced ABA accumulation, no change in either extensin or p33 mRNA levels was observed. Accumulation of extensin or p33 mRNA required more severe wounding. This suggests that ABA is not involved in the response of these genes in wounded tissue and that wound signals are not causing ABA accumulation in excised tissue. Accumulation of ABA in excised elongating regions was correlated with growth inhibition and a decline in turgor to the yield threshold (Ψ;p = 0.37 megapascals; R Matyssek, S Maruyama, JS Boyer [1988] Plant Physiol 86: 1163-1167). Inhibiting hypocotyl growth by transferring seedlings to lower temperatures or light did not cause ABA accumulation. We conclude that induction of ABA accumulation in growing zones is more sensitive to changes in turgor than the induction which occurs in mature tissues. Images Figure 2 PMID:16668113

  17. Abscisic Acid accumulates at positive turgor potential in excised soybean seedling growing zones.

    Science.gov (United States)

    Creelman, R A; Mullet, J E

    1991-04-01

    Abscisic acid (ABA) accumulated in soybean (Glycine max [L.] Merr. cv Williams) hypocotyl elongating regions when seedlings were transferred to low water potential vermiculite (Psi = -0.3 megapascals) even though positive turgor is retained in this tissue. Accumulation of ABA in growing zones could occur from de novo biosynthesis within this tissue or transport from adjacent nongrowing zones. Both growing and nongrowing hypocotyl and root tissues accumulated significant levels of ABA when excised and dehydrated to reduce turgor. Surprisingly, excised growing zones (which experienced no water loss) also accumulated ABA when incubated in darkness for 4 hours at 100% relative humidity and 29 degrees C. Induction of ABA accumulation in the excised elongating region of the hypocotyl was not caused by disruption of root pressure or wounding. While excision of hypocotyl elongating regions induced ABA accumulation, no change in either extensin or p33 mRNA levels was observed. Accumulation of extensin or p33 mRNA required more severe wounding. This suggests that ABA is not involved in the response of these genes in wounded tissue and that wound signals are not causing ABA accumulation in excised tissue. Accumulation of ABA in excised elongating regions was correlated with growth inhibition and a decline in turgor to the yield threshold (Psi;(p) = 0.37 megapascals; R Matyssek, S Maruyama, JS Boyer [1988] Plant Physiol 86: 1163-1167). Inhibiting hypocotyl growth by transferring seedlings to lower temperatures or light did not cause ABA accumulation. We conclude that induction of ABA accumulation in growing zones is more sensitive to changes in turgor than the induction which occurs in mature tissues.

  18. Composition dependence of the thermodynamic activity and lattice parameter of zeta nickel-indium

    International Nuclear Information System (INIS)

    Bhattacharya, B.; Masson, D.B.

    1976-01-01

    The vapor pressure of indium over six alloys in the zeta phase of the nickel-indium system was measured by the method of atomic absorption. Values of thermodynamic activity were calculated from the vapor pressure, and partial heat and entropy of indium were calculated from the temperature coefficients. The lattice parameters of the hexagonal B8 2 unit cell of all alloys were calculated from X-ray diffraction powder patterns. It was found that the a lattice parameter passed through a minimum at the same composition that the excess chemical potential showed a sharp change of slope, when graphed as a function of composition. These effects were similar to those observed previously which have been attributed to overlap by the Fermi surface of a Brillouin zone face. In the present case they were attributed to overlap of the Fermi surface across faces tentatively identified as the [110] faces of the Brillouin zone of the B8 2 structure. The influence of substitutional disorder was also considered as a cause of the thermodynamic effects, but this was rejected because it does not explain the minimum in lattice parameter. (Auth.)

  19. Hippocampal Infusion of Zeta Inhibitory Peptide Impairs Recent, but Not Remote, Recognition Memory in Rats

    Directory of Open Access Journals (Sweden)

    Jena B. Hales

    2015-01-01

    Full Text Available Spatial memory in rodents can be erased following the infusion of zeta inhibitory peptide (ZIP into the dorsal hippocampus via indwelling guide cannulas. It is believed that ZIP impairs spatial memory by reversing established late-phase long-term potentiation (LTP. However, it is unclear whether other forms of hippocampus-dependent memory, such as recognition memory, are also supported by hippocampal LTP. In the current study, we tested recognition memory in rats following hippocampal ZIP infusion. In order to combat the limited targeting of infusions via cannula, we implemented a stereotaxic approach for infusing ZIP throughout the dorsal, intermediate, and ventral hippocampus. Rats infused with ZIP 3–7 days after training on the novel object recognition task exhibited impaired object recognition memory compared to control rats (those infused with aCSF. In contrast, rats infused with ZIP 1 month after training performed similar to control rats. The ability to form new memories after ZIP infusions remained intact. We suggest that enhanced recognition memory for recent events is supported by hippocampal LTP, which can be reversed by hippocampal ZIP infusion.

  20. Where do developing countries go after Doha?:An analysis of WTO positions and potential alliances

    OpenAIRE

    Bjørnskov, Christian; Lind, Kim Martin Hjorth

    2002-01-01

    In the wake of the November 2001 Ministerial Conference in Doha, the positions of most members of the World Trade Organisation diverge, reflecting a large extent of disagreement within the organisation. This paper attempts to organise these positions and thereby inspire a debate on the possibility of collusion in the coming round of trade negotiations with a particular focus on the options of developing countries. Members' positions on a range of issues identified as important in the coming r...

  1. Positive emotion in distress as a potentially effective emotion regulation strategy for depression: A preliminary investigation.

    Science.gov (United States)

    Yamaguchi, Keiko; Ito, Masaya; Takebayashi, Yoshitake

    2018-03-12

    Emotion regulation utilizing positive emotion during negative emotional states might be one of the effective ways to alleviate depression and anxiety problems among people with emotional disorders. This study examined the psychometric properties and incremental validity of the Positive Emotion In Distress Scale (PEIDS), a newly developed self-report scale, in a sample of university students in Japan. To examine the psychometric properties of the PEIDS, the scale was completed by Japanese university students (396 men and 363 women; mean age of 19.92). Participants additionally answered the Emotion Regulation Questionnaire, Rumination and Reflection Questionnaire - Shorter Version, Affective Style Questionnaire, Positive and Negative Affective Schedule, and Hospital Anxiety and Depression Scale. The survey was conducted at two time points separated by 1 month to assess test-retest reliability and validity of the PEIDS. Exploratory and confirmatory factor analyses confirmed a one-factor structure. Reliability was confirmed by high internal consistency and test-retest stability; the convergent and discriminant validity was confirmed by correlations with related and unrelated variables. The results of hierarchical regression analyses demonstrated that positive emotion in distress might predict depression above and beyond the effect of baseline depression and other common emotion regulation strategies. The PEIDS showed acceptable reliability and validity within young adults and a non-clinical population in Japan. Further research will be needed to examine the effect of positive emotion among clinical populations. Previous research suggests that positive emotions play a key role in recovery from depression and anxiety problems through some forms of psychotherapy. The Positive Emotion In Distress Scale (PEIDS) measures individual differences regarding the extent to which people can experience positive emotions in negative emotional states. Results suggested that the

  2. Identifying potential engaging leaders within medical education: The role of positive influence on peers.

    Science.gov (United States)

    Michalec, Barret; Veloski, J Jon; Hojat, Mohammadreza; Tykocinski, Mark L

    2014-08-26

    Abstract Background: Previous research has paid little to no attention towards exploring methods of identifying existing medical student leaders. Aim: Focusing on the role of influence and employing the tenets of the engaging leadership model, this study examines demographic and academic performance-related differences of positive influencers and if students who have been peer-identified as positive influencers also demonstrate high levels of genuine concern for others. Methods: Three separate fourth-year classes were asked to designate classmates that had significant positive influences on their professional and personal development. The top 10% of those students receiving positive influence nominations were compared with the other students on demographics, academic performance, and genuine concern for others. Results: Besides age, no demographic differences were found between positive influencers and other students. High positive influencers were not found to have higher standardized exam scores but did receive significantly higher clinical clerkship ratings. High positive influencers were found to possess a higher degree of genuine concern for others. Conclusion: The findings lend support to (a) utilizing the engaging model to explore leaders and leadership within medical education, (b) this particular method of identifying existing medical student leaders, and (c) return the focus of leadership research to the power of influence.

  3. Selberg zeta functions and transfer operators an experimental approach to singular perturbations

    CERN Document Server

    Fraczek, Markus Szymon

    2017-01-01

    This book presents a method for evaluating Selberg zeta functions via transfer operators for the full modular group and its congruence subgroups with characters. Studying zeros of Selberg zeta functions for character deformations allows us to access the discrete spectra and resonances of hyperbolic Laplacians under both singular and non-singular perturbations. Areas in which the theory has not yet been sufficiently developed, such as the spectral theory of transfer operators or the singular perturbation theory of hyperbolic Laplacians, will profit from the numerical experiments discussed in this book. Detailed descriptions of numerical approaches to the spectra and eigenfunctions of transfer operators and to computations of Selberg zeta functions will be of value to researchers active in analysis, while those researchers focusing more on numerical aspects will benefit from discussions of the analytic theory, in particular those concerning the transfer operator method and the spectral theory of hyperbolic spac...

  4. Zeta functions and regularized determinants related to the Selberg trace formula

    DEFF Research Database (Denmark)

    Momeni, Arash; Venkov, Alexei

    determinants of one dimensional Schroedinger operator for harmonic oscillator. We decompose the determinant of the automorphic Laplacian into a product of the determinants where each factor is a determinant representation of a zeta function related to Selberg's trace formula. Then we derive an identity...... connecting the determinants of the automorphic Laplacians on different Riemannian surfaces related to the arithmetical groups. Finally, by using the Jacquet-Langlands correspondence we connect the determinant of the automorphic Laplacian for the unit group of quaternions to the product of the determinants......For a general Fuchsian group of the first kind with an arbitrary unitary representation we define the zeta functions related to the contributions of the identity, hyperbolic, elliptic and parabolic conjugacy classes in Selberg's trace formula. We present Selberg's zeta function in terms...

  5. Disciplinary style and child abuse potential: association with indicators of positive functioning in children with behavior problems.

    Science.gov (United States)

    Rodriguez, Christina M; Eden, Ann M

    2008-06-01

    Reduction of ineffective parenting is promoted in parent training components of mental health treatment for children with externalizing behavior disorders, but minimal research has considered whether disciplinary style and lower abuse risk could also be associated with positive functioning in such children. The present study examined whether lower dysfunctional disciplinary style and child abuse risk was associated with children's positive self-concept, adaptive attributional style, and hopefulness. Recruited from children undergoing treatment for disruptive behavior disorders, 69 mother-child dyads participated, with maternal caregivers reporting on their disciplinary style and abuse potential and children reporting independently on their positive functioning (adaptive attributional style, overall self-concept, and hopelessness). Findings supported the hypothesized association, with lower scores on mothers' dysfunctional discipline style and abuse potential significantly predicting children's reported positive functioning. Future research directions pertaining to more adaptive functioning in children with behavior problems are discussed.

  6. Ascending colon rotation following patient positional change during CT colonography: a potential pitfall in interpretation

    International Nuclear Information System (INIS)

    Kim, Ji Yeon; Park, Seong Ho; Lee, Seung Soo; Kim, Ah Young; Ha, Hyun Kwon

    2011-01-01

    To investigate the degree and pattern of ascending colonic rotation as patients moved from supine to prone positions during CTC. A search of our CTC and colonoscopy database found 37 patients (43 eligible lesions) who fulfilled the following criteria: colonoscopy-proven sessile polyps ≥6 mm in the straight mid-ascending colon, lesion visualisation in both supine and prone CTC, and optimal colonic distension. A coordinate system was developed to designate the polyp radial location ( ) along the luminal circumference, unaffected by rotation of the torso. The degree/direction of polyp radial location change (i.e. ascending colonic rotation) between supine and prone positions correlated with anthropometric measurements. Movement from supine to prone positions resulted in a change in the radial polyp location of between -23 and 79 (median, 21 ), demonstrating external rotation of the ascending colon in almost all cases (2 to 79 in 36/37 patients and 42/43 lesions). The degree/direction of rotation mildly correlated with the degree of abdominal compression in the anterior-posterior direction in prone position (r = 0.427 [P = 0.004] and r = 0.404 [P = 0.007]). The ascending colon was usually found to rotate externally as patients moved from supine to prone positions, partly dependent on the degree of abdominal compression. (orig.)

  7. A Rising Female Empire? : Exploring the potential barriers women face in achieving leadership positions in the humanitarian sector

    OpenAIRE

    Eriksson, Lina Elisabeth

    2015-01-01

    This research aims to explore how women and men view and perceive potential barriers to women achieving leadership positions in the humanitarian sector. Female leadership is so far an under-researched area within the humanitarian sector, so it is unknown whether females encounter any barriers in accessing and attaining leadership positions. Three categories were identified; identity, perception and challenges through which the views and barriers are explored. Semi-structured interviews were c...

  8. LETTER TO THE EDITOR: Fractal diffusion coefficient from dynamical zeta functions

    Science.gov (United States)

    Cristadoro, Giampaolo

    2006-03-01

    Dynamical zeta functions provide a powerful method to analyse low-dimensional dynamical systems when the underlying symbolic dynamics is under control. On the other hand, even simple one-dimensional maps can show an intricate structure of the grammar rules that may lead to a non-smooth dependence of global observables on parameters changes. A paradigmatic example is the fractal diffusion coefficient arising in a simple piecewise linear one-dimensional map of the real line. Using the Baladi-Ruelle generalization of the Milnor-Thurnston kneading determinant, we provide the exact dynamical zeta function for such a map and compute the diffusion coefficient from its smallest zero.

  9. Zeta Function Regularization in Casimir Effect Calculations and J. S. Dowker's Contribution

    Science.gov (United States)

    Elizalde, Emilio

    2012-07-01

    A summary of relevant contributions, ordered in time, to the subject of operator zeta functions and their application to physical issues is provided. The description ends with the seminal contributions of Stephen Hawking and Stuart Dowker and collaborators, considered by many authors as the actual starting point of the introduction of zeta function regularization methods in theoretical physics, in particular, for quantum vacuum fluctuation and Casimir effect calculations. After recalling a number of the strengths of this powerful and elegant method, some of its limitations are discussed. Finally, recent results of the so called operator regularization procedure are presented.

  10. Effective action for scalar fields and generalized zeta-function regularization

    International Nuclear Information System (INIS)

    Cognola, Guido; Zerbini, Sergio

    2004-01-01

    Motivated by the study of quantum fields in a Friedmann-Robertson-Walker space-time, the one-loop effective action for a scalar field defined in the ultrastatic manifold RxH 3 /Γ, H 3 /Γ being the finite volume, noncompact, hyperbolic spatial section, is investigated by a generalization of zeta-function regularization. It is shown that additional divergences may appear at the one-loop level. The one-loop renormalizability of the model is discussed and, making use of a generalization of zeta-function regularization, the one-loop renormalization group equations are derived

  11. On the construction of coherent states of position dependent mass Schroedinger equation endowed with effective potential

    International Nuclear Information System (INIS)

    Chithiika Ruby, V.; Senthilvelan, M.

    2010-01-01

    In this paper, we propose an algorithm to construct coherent states for an exactly solvable position dependent mass Schroedinger equation. We use point canonical transformation method and obtain ground state eigenfunction of the position dependent mass Schroedinger equation. We fix the ladder operators in the deformed form and obtain explicit expression of the deformed superpotential in terms of mass distribution and its derivative. We also prove that these deformed operators lead to minimum uncertainty relations. Further, we illustrate our algorithm with two examples, in which the coherent states given for the second example are new.

  12. Exact solutions of the Schrodinger equation with the position-dependent mass for a hard-core potential

    International Nuclear Information System (INIS)

    Dong Shihai; Lozada-Cassou, M.

    2005-01-01

    The exact solutions of two-dimensional Schrodinger equation with the position-dependent mass for a hard-core potential are obtained. The eigenvalues related to the position-dependent masses μ 1 and μ 2 , the potential well depth V 0 and the effective range r 0 can be calculated by the boundary condition. We generalize this quantum system to three-dimensional case. The special cases for l=0,1 are studied in detail. For l=0 and c=0, we find that the energy levels will increase with the parameters μ 2 , V 0 and r 0 if μ 1 >μ 2

  13. Interaction of nucleosome assembly proteins abolishes nuclear localization of DGK{zeta} by attenuating its association with importins

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Masashi; Hozumi, Yasukazu [Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585 (Japan); Ichimura, Tohru [Department of Chemistry, Graduate School of Sciences and Engineering, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); Tanaka, Toshiaki; Hasegawa, Hiroshi; Yamamoto, Masakazu; Takahashi, Nobuya [Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585 (Japan); Iseki, Ken [Department of Emergency and Critical Care Medicine, Yamagata University School of Medicine, Yamagata 990-9585 (Japan); Yagisawa, Hitoshi [Laboratory of Biological Signaling, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297 (Japan); Shinkawa, Takashi; Isobe, Toshiaki [Department of Chemistry, Graduate School of Sciences and Engineering, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); Goto, Kaoru, E-mail: kgoto@med.id.yamagata-u.ac.jp [Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585 (Japan)

    2011-12-10

    Diacylglycerol kinase (DGK) is involved in the regulation of lipid-mediated signal transduction through the metabolism of a second messenger diacylglycerol. Of the DGK family, DGK{zeta}, which contains a nuclear localization signal, localizes mainly to the nucleus but translocates to the cytoplasm under pathological conditions. However, the detailed mechanism of translocation and its functional significance remain unclear. To elucidate these issues, we used a proteomic approach to search for protein targets that interact with DGK{zeta}. Results show that nucleosome assembly protein (NAP) 1-like 1 (NAP1L1) and NAP1-like 4 (NAP1L4) are identified as novel DGK{zeta} binding partners. NAP1Ls constitutively shuttle between the nucleus and the cytoplasm in transfected HEK293 cells. The molecular interaction of DGK{zeta} and NAP1Ls prohibits nuclear import of DGK{zeta} because binding of NAP1Ls to DGK{zeta} blocks import carrier proteins, Qip1 and NPI1, to interact with DGK{zeta}, leading to cytoplasmic tethering of DGK{zeta}. In addition, overexpression of NAP1Ls exerts a protective effect against doxorubicin-induced cytotoxicity. These findings suggest that NAP1Ls are involved in a novel molecular basis for the regulation of nucleocytoplasmic shuttling of DGK{zeta} and provide a clue to examine functional significance of its translocation under pathological conditions.

  14. Zeros da função zeta de Riemann e o teorema dos números primos

    OpenAIRE

    Oliveira, Willian Diego [UNESP

    2013-01-01

    We studied various properties of the Riemann’s zeta function. Three proofs of the Prime Number Theorem were provides. Classical results on zero-free region of the zeta function, as well as their relation to the error term in the Prime Number Theorem, were studied in details Estudamos várias propriedades da função zeta de Riemann. Três provas do Teorema dos Números Primos foram fornecidas. Resultados clássicos sobre regiões livres de zeros da função zeta, bem como sua relação com o termo do...

  15. Functionally Independent Components of the Late Positive Event-Related Potential During Visual Spatial Attention

    National Research Council Canada - National Science Library

    Makeig, Scott; Westeifleld, Marissa; Jung, Tzyy-Ping; Covington, James; Townsend, Jeanne; Sejnowski, Terrence J; Courchesne, Eric

    1999-01-01

    Human event-related potentials (ERPs) were recorded from 10 subjects presented with visual target and nontarget stimuli at five screen locations and responding to targets presented at one of the locations...

  16. Position-dependent patterning of spontaneous action potentials in immature cochlear inner hair cells

    Science.gov (United States)

    Johnson, Stuart L.; Eckrich, Tobias; Kuhn, Stephanie; Zampini, Valeria; Franz, Christoph; Ranatunga, Kishani M.; Roberts, Terri P.; Masetto, Sergio; Knipper, Marlies; Kros, Corné J.; Marcotti, Walter

    2011-01-01

    Spontaneous action potential activity is crucial for mammalian sensory system development. In the auditory system, patterned firing activity has been observed in immature spiral ganglion cells and brain-stem neurons and is likely to depend on cochlear inner hair cell (IHC) action potentials. It remains uncertain whether spiking activity is intrinsic to developing IHCs and whether it shows patterning. We found that action potentials are intrinsically generated by immature IHCs of altricial rodents and that apical IHCs exhibit bursting activity as opposed to more sustained firing in basal cells. We show that the efferent neurotransmitter ACh, by fine-tuning the IHC’s resting membrane potential (Vm), is crucial for the bursting pattern in apical cells. Endogenous extracellular ATP also contributes to the Vm of apical and basal IHCs by activating SK2 channels. We hypothesize that the difference in firing pattern along the cochlea instructs the tonotopic differentiation of IHCs and auditory pathway. PMID:21572434

  17. Structural changes at the myrtenol backbone reverse its positive allosteric potential into inhibitory GABAA receptor modulation

    DEFF Research Database (Denmark)

    Milanos, Sinem; Kuenzel, Katharina; Gilbert, Daniel F

    2017-01-01

    monoterpenes, e.g. myrtenol as positive allosteric modulator at α1β2 GABAA receptors. Here, along with pharmacophore-based virtual screening studies, we demonstrate that scaffold modifications of myrtenol resulted in loss of modulatory activity. Two independent approaches, fluorescence-based compound analysis...

  18. Beyond 1984: The Positive and Negative Potential of Computer Supported School Focused Information Systems.

    Science.gov (United States)

    Klein, Susan S.

    Although educators' use of computers to track student and school information with the attendant positive and negative outcomes is still in an early stage of development, accessible data from such systems could improve the objective rationality of educational and instructional decision-making as long as no one places unwarranted credibility in the…

  19. Assessment of potential false positives via orbitrap-based untargeted lipidomics from rat tissues.

    Science.gov (United States)

    Xu, Lina; Wang, Xueying; Jiao, Yupei; Liu, Xiaohui

    2018-02-01

    Untargeted lipidomics is increasingly popular due to the broad coverage of lipid species. Data dependent MS/MS acquisition is commonly used in order to acquire sufficient information for confident lipid assignment. However, although lipids are identified based on MS/MS confirmation, a number of false positives are still observed. Here, we discuss several causes of introducing lipid false identifications in untargeted analysis. Phosphotidylcholines and cholesteryl esters generate in-source fragmentation to produce dimethylated phosphotidylethanolamine and free cholesterol. Dimerization of fatty acid results in false identification of fatty acid ester of hydroxyl fatty acid. Realizing these false positives is able to improve confidence of results acquired from untargeted analysis. Besides, thresholds are established for lipids identified using LipidSearch v4.1.16 software to reduce unreliable results. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. A Potential Role for mu-Opioids in Mediating the Positive Effects of Gratitude.

    Science.gov (United States)

    Henning, Max; Fox, Glenn R; Kaplan, Jonas; Damasio, Hanna; Damasio, Antonio

    2017-01-01

    Gratitude is a complex emotional feeling associated with universally desirable positive effects in personal, social, and physiological domains. Why or how gratitude achieves these functional outcomes is not clear. Toward the goal of identifying its' underlying physiological processes, we recently investigated the neural correlates of gratitude. In our study, participants were exposed to gratitude-inducing stimuli, and rated each according to how much gratitude it provoked. As expected, self-reported gratitude intensity correlated with brain activity in distinct regions of the medial pre-frontal cortex associated with social reward and moral cognition. Here we draw from our data and existing literature to offer a theoretical foundation for the physiological correlates of gratitude. We propose that mu-opioid signaling (1) accompanies the mental experience of gratitude, and (2) may account for the positive effects of gratitude on social relationships, subjective wellbeing, and physiological health.

  1. Improved UUV Positioning Using Acoustic Communications and a Potential for Real-Time Networking and Collaboration

    Science.gov (United States)

    2017-06-01

    model the environment is proposed for real-time applications . To be able to establish the submersible vehicle’s position, a tracking algorithm ...approximation, which in certain cases can lead to coarse accuracy in the results. In high frequency applications , however, ray tracing algorithms are very...intelligence techniques, as in the genetic algorithms or simulated annealing algorithms . START Initial Choice for Run UKF for  , , , ,  x R Q

  2. Control of secondary electrons from ion beam impact using a positive potential electrode

    Energy Technology Data Exchange (ETDEWEB)

    Crowley, T. P., E-mail: tpcrowley@xanthotechnologies.com; Demers, D. R.; Fimognari, P. J. [Xantho Technologies, LLC, Madison, Wisconsin 53705 (United States)

    2016-11-15

    Secondary electrons emitted when an ion beam impacts a detector can amplify the ion beam signal, but also introduce errors if electrons from one detector propagate to another. A potassium ion beam and a detector comprised of ten impact wires, four split-plates, and a pair of biased electrodes were used to demonstrate that a low-voltage, positive electrode can be used to maintain the beneficial amplification effect while greatly reducing the error introduced from the electrons traveling between detector elements.

  3. Potential Effects of Climate Change on Treeline Position in the Swedish Mountains

    Directory of Open Access Journals (Sweden)

    Jon Moen

    2004-06-01

    Full Text Available Climate change may strongly influence species distribution and, thus, the structure and function of ecosystems. This paper describes simulated changes in the position of the upper treeline in the Swedish mountains in response to predicted climate change. Data on predicted summer temperature changes, the current position of the treeline, and a digital elevation model were used to predict the position of the treeline over a 100-year timeframe. The results show the treeline advancing upward by 233-667 m, depending on the climate scenario used and location within the mountain chain. Such changes hypothetically caused a 75-85% reduction in treeless alpine heaths, with 60-93% of the remaining areas being scree slopes and boulder fields. For this change to occur, the migration rate of the trees would be in the order of 23-221 m yr-1, which is well within published migration rates for wind-dispersed deciduous trees. The remaining alpine areas would be strongly fragmented. These drastic changes would influence all aspects of mountain ecosystems, including biodiversity conservation and human land-use patterns.

  4. Position-dependent patterning of spontaneous action potentials in immature cochlear inner hair cells.

    Science.gov (United States)

    Johnson, Stuart L; Eckrich, Tobias; Kuhn, Stephanie; Zampini, Valeria; Franz, Christoph; Ranatunga, Kishani M; Roberts, Terri P; Masetto, Sergio; Knipper, Marlies; Kros, Corné J; Marcotti, Walter

    2011-06-01

    Spontaneous action potential activity is crucial for mammalian sensory system development. In the auditory system, patterned firing activity has been observed in immature spiral ganglion and brain-stem neurons and is likely to depend on cochlear inner hair cell (IHC) action potentials. It remains uncertain whether spiking activity is intrinsic to developing IHCs and whether it shows patterning. We found that action potentials were intrinsically generated by immature IHCs of altricial rodents and that apical IHCs showed bursting activity as opposed to more sustained firing in basal cells. We show that the efferent neurotransmitter acetylcholine fine-tunes the IHC's resting membrane potential (V(m)), and as such is crucial for the bursting pattern in apical cells. Endogenous extracellular ATP also contributes to the V(m) of apical and basal IHCs by triggering small-conductance Ca(2+)-activated K(+) (SK2) channels. We propose that the difference in firing pattern along the cochlea instructs the tonotopic differentiation of IHCs and auditory pathway.

  5. Evaluation of human skin tests for potential dermal irritant and contact sensitizing products: a position paper

    NARCIS (Netherlands)

    Loveren H van; Jong WH de; Garssen J; LPI

    1998-01-01

    Prediction of human cutaneous irritation and sensitization in view of hazard identification has primarily relied on the use of laboratory animals. Such studies in laboratory animals have been very instrumental in the detection of potential contact sensitizing agents. There are however many

  6. Broadway teatrites näeb Denzel Washingtoni ja Catherine Zeta-Jonesi / Andres Laasik

    Index Scriptorium Estoniae

    Laasik, Andres, 1960-2016

    2010-01-01

    New Yorgis välja antud Tony teatriauhinna pälvisid filminäitlejad Denzel Washington, Catherine Zeta-Jones ja Scarlett Johansson. Parim lavale naasnud näidend - "Piirdeaed", parim uus näidend - draama "Punane", mis räägib läti päritolu maalikunstnikust Mark Rothkost. Parim muusikal - "Memphis"

  7. Certain Subclasses of Analytic and Bi-Univalent Functions Involving Double Zeta Functions

    OpenAIRE

    Siregar, Saibah; Raman, Sintuja

    2012-01-01

    In the present paper, we introduce two new subclasses of the functions class Σ of bi-univalent functions involving double zeta functions in the open unit disc U={z:zEC, |z|<1}. The estimates on the coefficients |a2| and |a3| for functions in these new subclasses of the function class Σ are obtained in our investigation.

  8. "Armastuse retsepti" tippkokk Zeta Jones ei oska muna keeta / Triin Tael

    Index Scriptorium Estoniae

    Tael, Triin

    2007-01-01

    Scott Hicksi romantiline komöödiafilm "Armastuse retsept" ("No Reservations"), mille peaosas Walesist pärit näitlejanna Catherine Zeta Jones. Näitlejanna muljeid oma rolliks ettevalmistustest, mille hulka käis ka praktika pärisrestoranis

  9. Boundary Conditions for the Maintenance of Memory by PKM[zeta] in Neocortex

    Science.gov (United States)

    Shema, Reul; Hazvi, Shoshi; Sacktor, Todd C.; Dudai, Yadin

    2009-01-01

    We report here that ZIP, a selective inhibitor of the atypical protein kinase C isoform PKM[zeta], abolishes very long-term conditioned taste aversion (CTA) associations in the insular cortex of the behaving rat, at least 3 mo after encoding. The effect of ZIP is not replicated by a general serine/threonine protein kinase inhibitor that is…

  10. Asymptotic analysis on a pseudo-Hermitian Riemann-zeta Hamiltonian

    Science.gov (United States)

    Bender, Carl M.; Brody, Dorje C.

    2018-04-01

    The differential-equation eigenvalue problem associated with a recently-introduced Hamiltonian, whose eigenvalues correspond to the zeros of the Riemann zeta function, is analyzed using Fourier and WKB analysis. The Fourier analysis leads to a challenging open problem concerning the formulation of the eigenvalue problem in the momentum space. The WKB analysis gives the exact asymptotic behavior of the eigenfunction.

  11. Critical dimension of bosonic string theory and zeta-function regularization

    International Nuclear Information System (INIS)

    Vanzo, L.; Zerbini, S.; Istituto Nazionale di Fisica Nucleare, Povo

    1988-01-01

    A derivation of the critical dimension of the Polyakov bosonic string is presented. It is based on the use of the anholonomic formalism, a ghost-anti-ghost symmetric action, zeta-function regularization and the Seeley method of pseudo-differential operators. (orig.)

  12. Cancer-associated fibroblasts are positively correlated with metastatic potential of human gastric cancers

    Directory of Open Access Journals (Sweden)

    Zhang Hao

    2010-06-01

    Full Text Available Abstract Background The prognosis of gastric cancer patients is difficult to predict because of defects in establishing the surgical-pathological features. Cancer-associated fibroblasts (CAFs have been found to play prominent role in promoting tumor growth, invasion and metastasis. Thus raises the hypothesis that the extent of CAFs prevalence may help to establish the prognosis of gastric cancer patients. Methods Immunochemistry and realtime-PCR experiments were carried out to compare the expression of proteins which are specific markers of CAFs or secreted by CAFs in the tumor and normal tissue specimens. The extent of CAFs' prevalence was graded according to immunochemical staining, and correlation was further analyzed between CAFs' prevalence and other tumor characteristics which may influence the prognosis of gastric cancer patients. Results Nearly 80 percent of normal gastric tissues were negative or weak positive for CAFs staining, while more than 60 percent of gastric cancer tissues were moderate or strong positive for CAFs staining. Realtime-PCR results also showed significant elevated expression of FAP, SDF-1 and TGF-β1 in gastric cancer tissues compared to normal gastric tissues. Further analysis showed that CAFs' prevalence was correlated with tumor size, depth of the tumor, lymph node metastasis, liver metastasis or peritoneum metastasis. Conclusions Reactive cancer associated fibroblasts (CAFs were frequently accumulated in gastric cancer tissues, and the prevalence of CAFs was correlated with tumor size, depth of the tumor and tumor metastasis, thus give some supports for establishing the prognosis of the gastric cancer patients.

  13. Integrated module inverter using a zeta DC-DC converter with feedforward MPPT (Maximum Power Point Tracking) control; Inversor modulo integrado utilizando um conversor CC-CC zeta com controle MPPT feedforward

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Henrique Fioravanti Miguel

    2009-08-15

    This work presents the study and development of a processing power system that could be used in the connection of renewable energy sources to commercial power grid. The system consists of a ZETA converter associated with a bridge inverter operating at low frequency. The Zeta converter, operating in discontinuous conduction mode (DCM), plays the main role in this arrangement, producing a rectified sinusoidal current waveform synchronized with the electric grid. The function of the full-bridge inverter, connected in cascade with the Zeta converter, is to reverse every 180 deg the current generated by the Zeta converter. Initially it presents the analysis of the Zeta converter operating in DCM, as well as a design criterion. Following by the control strategy and the experimental results for the proposed system are presented and discussed. (author)

  14. The Summating Potential Is a Reliable Marker of Electrode Position in Electrocochleography: Cochlear Implant as a Theragnostic Probe.

    Science.gov (United States)

    Helmstaedter, Victor; Lenarz, Thomas; Erfurt, Peter; Kral, Andrej; Baumhoff, Peter

    2017-12-14

    For the increasing number of cochlear implantations in subjects with residual hearing, hearing preservation, and thus the prevention of implantation trauma, is crucial. A method for monitoring the intracochlear position of a cochlear implant (CI) and early indication of imminent cochlear trauma would help to assist the surgeon to achieve this goal. The aim of this study was to evaluate the reliability of the different electric components recorded by an intracochlear electrocochleography (ECochG) as markers for the cochleotopic position of a CI. The measurements were made directly from the CI, combining intrasurgical diagnostics with the therapeutical use of the CI, thus, turning the CI into a "theragnostic probe." Intracochlear ECochGs were measured in 10 Dunkin Hartley guinea pigs of either sex, with normal auditory brainstem response thresholds. All subjects were fully implanted (4 to 5 mm) with a custom six contact CI. The ECochG was recorded simultaneously from all six contacts with monopolar configuration (retroauricular reference electrode). The gross ECochG signal was filtered off-line to separate three of its main components: compound action potential, cochlear microphonic, and summating potential (SP). Additionally, five cochleae were harvested and histologically processed to access the spatial position of the CI contacts. Both ECochG data and histological reconstructions of the electrode position were fitted with the Greenwood function to verify the reliability of the deduced cochleotopic position of the CI. SPs could be used as suitable markers for the frequency position of the recording electrode with an accuracy of ±1/4 octave in the functioning cochlea, verified by histology. Cochlear microphonics showed a dependency on electrode position but were less reliable as positional markers. Compound action potentials were not suitable for CI position information but were sensitive to "cochlear health" (e.g., insertion trauma). SPs directly recorded from

  15. The interaction between saliva and Actinobacillus actinomycetemcomitans influenced by the Zeta potential

    NARCIS (Netherlands)

    Groenink, J; Veerman, ECI; Zandvoort, MS; van der Mei, HC; Busscher, HJ; Amerongen, AVN

    The adhesion of Actinobacillus actinomycetemcomitans is a virulence factor in the aetiology of periodontitis and is determined by physico-chemical properties, e.g. surface charge and hydrophobicity, of the bacterial cell surface. Although oral surfaces are constantly coated with saliva, few studies

  16. Special values of the spectral zeta function of the non-commutative harmonic oscillator and confluent Heun equations

    CERN Document Server

    Ichinose, T

    2004-01-01

    We study the special values at $s=2$ and $3$ of the spectral zeta function $\\zeta_Q(s)$ of the non-commutative harmonic oscillator $Q(x,D_x)$ introduced in \\cite{PW1, 2}. It is shown that the series defining $\\zeta_Q(s)$ converges absolutely for Re $s>1$ and further the respective values $\\zeta_Q(2)$ and $\\zeta_Q(3)$ are represented essentially by contour integrals of the solutions, respectively, of a singly confluent Heun's ordinary differential equation and of exactly the same but an inhomogeneous equation. As a by-product of these results, we obtain integral representations of the solutions of these equations by rational functions. \\par\

  17. The uterine blush. A potential false-positive in Meckel's scan interpretation

    International Nuclear Information System (INIS)

    Fink-Bennett, D.

    1982-01-01

    To determine the presence, prevalence, and clinical importance of /sup 99m/Tc pertechnetate uterine uptake, this retrospective analysis of 71 Meckel's scans was undertaken. Specifically, each study was evaluated for the presence of a focal accumulation of radiotracer cephalad to the bladder. Patients received an intravenous dose of 150 microCi/kg of /sup 99m/Tc pertechnetate. Each study consisted of 15 one minute anterior serial gamma camera images, and a 15, 30, and 60 minute anterior, right lateral and posterior scintiscan. Menstrual histories were obtained from all patients except two. No males (33/33), nor premenstrual (13/13), menopausal (4/4) or posthysterectomy (2/2) patients revealed a uterine blush. Eleven of 15 patients (73%) with regular menses demonstrated a uterine blush. They were in the menstrual or secretory phases of their cycle. Four demonstrated no uterine uptake, had regular periods, but were in the proliferative phase of their cycle. Two with irregular periods, and one with no recorded menstrual history, manifested the blush. Radiotracer should be expected in the uterus during the menstrual and secretory phases of the menstrual cycle. It is a manifestation of a normal physiologic phenomenon, and must be recognized to prevent false-positive Meckel's scan interpretations

  18. Barriers Inhibiting Inquiry-Based Science Teaching and Potential Solutions: Perceptions of Positively Inclined Early Adopters

    Science.gov (United States)

    Fitzgerald, Michael; Danaia, Lena; McKinnon, David H.

    2017-07-01

    In recent years, calls for the adoption of inquiry-based pedagogies in the science classroom have formed a part of the recommendations for large-scale high school science reforms. However, these pedagogies have been problematic to implement at scale. This research explores the perceptions of 34 positively inclined early-adopter teachers in relation to their implementation of inquiry-based pedagogies. The teachers were part of a large-scale Australian high school intervention project based around astronomy. In a series of semi-structured interviews, the teachers identified a number of common barriers that prevented them from implementing inquiry-based approaches. The most important barriers identified include the extreme time restrictions on all scales, the poverty of their common professional development experiences, their lack of good models and definitions for what inquiry-based teaching actually is, and the lack of good resources enabling the capacity for change. Implications for expectations of teachers and their professional learning during educational reform and curriculum change are discussed.

  19. The uterine blush. A potential false-positive in Meckel's scan interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Fink-Bennett, D.

    1982-10-01

    To determine the presence, prevalence, and clinical importance of /sup 99m/Tc pertechnetate uterine uptake, this retrospective analysis of 71 Meckel's scans was undertaken. Specifically, each study was evaluated for the presence of a focal accumulation of radiotracer cephalad to the bladder. Patients received an intravenous dose of 150 microCi/kg of /sup 99m/Tc pertechnetate. Each study consisted of 15 one minute anterior serial gamma camera images, and a 15, 30, and 60 minute anterior, right lateral and posterior scintiscan. Menstrual histories were obtained from all patients except two. No males (33/33), nor premenstrual (13/13), menopausal (4/4) or posthysterectomy (2/2) patients revealed a uterine blush. Eleven of 15 patients (73%) with regular menses demonstrated a uterine blush. They were in the menstrual or secretory phases of their cycle. Four demonstrated no uterine uptake, had regular periods, but were in the proliferative phase of their cycle. Two with irregular periods, and one with no recorded menstrual history, manifested the blush. Radiotracer should be expected in the uterus during the menstrual and secretory phases of the menstrual cycle. It is a manifestation of a normal physiologic phenomenon, and must be recognized to prevent false-positive Meckel's scan interpretations.

  20. Technetium labeled WH701 for its potential use to image TNF-receptor-positive hepatocarcinoma

    International Nuclear Information System (INIS)

    Xia Jinsong; Wu Hua; Xiang Yan

    2004-01-01

    Objective: In this investigation, TNF analogs (WH701) was labeled with technetium (A number of TNF analogs had been selected and synthesized in our lab using random phage-display peptides library ) and pharmacokinetics and feasibility studies were performed for its potential use as diagnostic radiopharmaceutical. Methods WH701 was radiolabeled with 99m Tc then the complexes were characterized by thin layer chromatography. In vitro stability of the radiolabeled WH701 was examined simultaneity. Biodistribution and tumor uptake studies were also conducted to determine its in vivo characteristics. Results: The peptide analog WH701 permitted efficient incorporation of 99m Tc. The preparation of 99m Tc-WH701 was stable in vitro. Studies in vivo suggested that the biological activity of the peptide was not compromised. The agent was cleared rapidly from the blood and excreted mainly from kidney. The labeled peptide was shown in the nude mouse model to localize rapidly and specifically in site of tumor. Conclusions: The TNF analogue peptide WH701 can be radiolabeled with 99m Tc without loss of affinity, and the 99m Tc-WH701 shows radiochemical stability for an extended period of time in vitro. The high specific tumor uptake, rapid blood clearance, and predominantly renal excretion make 99m Tc-WH701 a promising candidate for tumor imaging. This agent is worthy of further investigation.

  1. Technetium labeled WH701 for its potential use to image TNF-receptor-positive hepatocarcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Jinsong, Xia; Hua, Wu; Yan, Xiang [Department of Nuclear Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan (China)

    2004-07-01

    Objective: In this investigation, TNF analogs (WH701) was labeled with technetium (A number of TNF analogs had been selected and synthesized in our lab using random phage-display peptides library ) and pharmacokinetics and feasibility studies were performed for its potential use as diagnostic radiopharmaceutical. Methods WH701 was radiolabeled with {sup 99m}Tc then the complexes were characterized by thin layer chromatography. In vitro stability of the radiolabeled WH701 was examined simultaneity. Biodistribution and tumor uptake studies were also conducted to determine its in vivo characteristics. Results: The peptide analog WH701 permitted efficient incorporation of {sup 99m}Tc. The preparation of {sup 99m}Tc-WH701 was stable in vitro. Studies in vivo suggested that the biological activity of the peptide was not compromised. The agent was cleared rapidly from the blood and excreted mainly from kidney. The labeled peptide was shown in the nude mouse model to localize rapidly and specifically in site of tumor. Conclusions: The TNF analogue peptide WH701 can be radiolabeled with {sup 99m}Tc without loss of affinity, and the {sup 99m}Tc-WH701 shows radiochemical stability for an extended period of time in vitro. The high specific tumor uptake, rapid blood clearance, and predominantly renal excretion make {sup 99m}Tc-WH701 a promising candidate for tumor imaging. This agent is worthy of further investigation.

  2. The Analytic Solution of Schroedinger Equation with Potential Function Superposed by Six Terms with Positive-power and Inverse-power Potentials

    International Nuclear Information System (INIS)

    Hu Xianquan; Luo Guang; Cui Lipeng; Niu Lianbin; Li Fangyu

    2009-01-01

    The analytic solution of the radial Schroedinger equation is studied by using the tight coupling condition of several positive-power and inverse-power potential functions in this article. Furthermore, the precisely analytic solutions and the conditions that decide the existence of analytic solution have been searched when the potential of the radial Schroedinger equation is V(r) = α 1 r 8 + α 2 r 3 + α 3 r 2 + β 3 r -1 + β 2 r -3 + β 1 r -4 . Generally speaking, there is only an approximate solution, but not analytic solution for Schroedinger equation with several potentials' superposition. However, the conditions that decide the existence of analytic solution have been found and the analytic solution and its energy level structure are obtained for the Schroedinger equation with the potential which is motioned above in this paper. According to the single-value, finite and continuous standard of wave function in a quantum system, the authors firstly solve the asymptotic solution through the radial coordinate r → and r → 0; secondly, they make the asymptotic solutions combining with the series solutions nearby the neighborhood of irregular singularities; and then they compare the power series coefficients, deduce a series of analytic solutions of the stationary state wave function and corresponding energy level structure by tight coupling among the coefficients of potential functions for the radial Schroedinger equation; and lastly, they discuss the solutions and make conclusions. (general)

  3. Fluctuations of estradiol during women's menstrual cycle: Influences on reactivity towards erotic stimuli in the late positive potential.

    Science.gov (United States)

    Munk, Aisha J L; Zoeller, Aaron C; Hennig, Juergen

    2018-05-01

    While several studies examined the reactivity towards negative emotional stimuli across women's menstrual cycle, only few investigated responses to positive emotional cues in association with sexual hormones on a neural level. Therefore, the aim of the current EEG-experiment was to study the differential reactivity towards positive (erotic) words during the menstrual cycle (i.e. with fluctuations in the steroids estradiol and progesterone) in the late positive potential (LPP). Regarding reactivity towards erotic stimuli, the LPP is seen as the most relevant ERP-component, as more positive amplitudes in the LPP reflect larger incentive salience and higher arousal. The LPP towards erotic words was expected to be more pronounced during fertile phases of the menstrual cycle (around ovulation). Furthermore, associations with hormonal concentrations of estradiol and progesterone were investigated. 19 young, free cycling women were tested in an Erotic Stroop paradigm during the follicular phase, ovulation, and the luteal phase in a balanced cross-over design, while electroencephalogram (EEG) was recorded. LPPs in reaction to erotic compared to neutral words were larger in every phase. During the follicular phase and ovulation, higher estradiol-concentrations were associated with more positive LPP-amplitudes towards erotic- than to neutral words. No effects of progesterone, as well as no effects of cycle phase, were evident. Results are being discussed regarding implications for further research. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Germanium CMOS potential from material and process perspectives: Be more positive about germanium

    Science.gov (United States)

    Toriumi, Akira; Nishimura, Tomonori

    2018-01-01

    practically viable, we need to understand why electron mobility is severely degraded in the inversion layer in Ge n-channel MOSFETs and to find out how it can be increased. In the Si CMOS technology, the SiO2/Si interface has long been investigated and cannot be ignored even after the introduction of high-k gate stack technology. In that sense, the GeO2/Ge interface should be intensively studied to make the best of Ge’s advantages. Therefore we first discuss the GeO2/Ge interface with regard to its physical and electrical characteristics. When we regard Ge as a channel material beyond Si for high performance ULSIs, we also have to seriously consider the gate stack scalability and reliability. The source/drain engineering, as well as the gate stack formation, is another challenge in Ge MOSFET design. Both the higher metal/Ge contact resistance and the larger p/n junction leakage current may be the consequences of Ge’s intrinsic properties because they are derived from the strong Fermi-level pinning and the narrow energy band gap, respectively. Even if the carrier transport in the channel may be ideally ballistic, these properties should degrade FET properties. The narrower energy band gap of Ge is often addressed, but the higher dielectric constant of Ge is rarely discussed. This is also the case for most of the other high-mobility materials. The dielectric constant is directly and negatively related to short-channel effects, and we have not been able to provide a substantial solution to overcome this hardship. We have to keep this in mind for the short-channel FET operation. Although a number of problems remain to be solved, in this paper, we view the current status of Ge FET technology positively. A number of (but not all) Ge-related challenges have been overcome in the past 10 years, which seems to be a good time to summarize the status of Ge technology, particularly materials engineering aspects rather than device integration issues. Since we cannot cover all of the

  5. Influence of the Level of the Development of Skills on Labour Potential, its Implementation and Choice of Work Position

    Directory of Open Access Journals (Sweden)

    Kseniya Aleksandrovna Ustinova

    2016-09-01

    Full Text Available The article deals with the sociological assessment of the skills level and identification of its influence on some aspects of labour activity: the realization of labour potential, choice of the scope of activity, position and occupation. It suggests an approach based on the subjective evaluation of the population as an instrument of the skills level assessment. The received results are compared with the indirect estimates allowing to characterize some particular components of labour potential which are similar to the considered skills. A specific feature of the research is not only the determination of the professional sphere, occupation and position on the skills level, but also the accounting of the reverse effect. The methodological tools including the methods for the assessment of skills level, labour potential and extent of its implementation in a labour activity have been approved in the Vologda region. The study revealed that, at the present time, the most developed skills are the teamwork, communication and mutual understanding while the least developed ones are the initiative and creativity as well as ability to be retrained and readiness to increase the professional level. It shows that the employees of socially oriented spheres and also the representatives of state structures have more developed skills. At the same time, the development of innovative skills not only leads to the growth of labour potential, but also creates conditions for the employment in workplaces with higher skills requirements. The paper shows that higher skills level along with higher skills requirements leads to more complete implementation of cumulative potential in the labour activity. The received results can be used by regional authorities for the development of the analytical system of labour market, the development of labour force and the labour potential of the population.

  6. Non-Commutative Integration, Zeta Functions and the Haar State for SU{sub q}(2)

    Energy Technology Data Exchange (ETDEWEB)

    Matassa, Marco, E-mail: marco.matassa@gmail.com [SISSA (Italy)

    2015-12-15

    We study a notion of non-commutative integration, in the spirit of modular spectral triples, for the quantum group SU{sub q}(2). In particular we define the non-commutative integral as the residue at the spectral dimension of a zeta function, which is constructed using a Dirac operator and a weight. We consider the Dirac operator introduced by Kaad and Senior and a family of weights depending on two parameters, which are related to the diagonal automorphisms of SU{sub q}(2). We show that, after fixing one of the parameters, the non-commutative integral coincides with the Haar state of SU{sub q}(2). Moreover we can impose an additional condition on the zeta function, which also fixes the second parameter. For this unique choice the spectral dimension coincides with the classical dimension.

  7. Averages of ratios of the Riemann zeta-function and correlations of divisor sums

    Science.gov (United States)

    Conrey, Brian; Keating, Jonathan P.

    2017-10-01

    Nonlinearity has published articles containing a significant number-theoretic component since the journal was first established. We examine one thread, concerning the statistics of the zeros of the Riemann zeta function. We extend this by establishing a connection between the ratios conjecture for the Riemann zeta-function and a conjecture concerning correlations of convolutions of Möbius and divisor functions. Specifically, we prove that the ratios conjecture and an arithmetic correlations conjecture imply the same result. This provides new support for the ratios conjecture, which previously had been motivated by analogy with formulae in random matrix theory and by a heuristic recipe. Our main theorem generalises a recent calculation pertaining to the special case of two-over-two ratios.

  8. Resonance chains in open systems, generalized zeta functions and clustering of the length spectrum

    International Nuclear Information System (INIS)

    Barkhofen, S; Faure, F; Weich, T

    2014-01-01

    In many non-integrable open systems in physics and mathematics, resonances have been found to be surprisingly ordered along curved lines in the complex plane. In this article we provide a unifying approach to these resonance chains by generalizing dynamical zeta functions. By means of a detailed numerical study we show that these generalized zeta functions explain the mechanism that creates the chains of quantum resonance and classical Ruelle resonances for three-disk systems as well as geometric resonances on Schottky surfaces. We also present a direct system-intrinsic definition of the continuous lines on which the resonances are strung together as a projection of an analytic variety. Additionally, this approach shows that the existence of resonance chains is directly related to a clustering of the classical length spectrum on multiples of a base length. Finally, this link is used to construct new examples where several different structures of resonance chains coexist. (paper)

  9. Non-Commutative Integration, Zeta Functions and the Haar State for SUq(2)

    International Nuclear Information System (INIS)

    Matassa, Marco

    2015-01-01

    We study a notion of non-commutative integration, in the spirit of modular spectral triples, for the quantum group SU q (2). In particular we define the non-commutative integral as the residue at the spectral dimension of a zeta function, which is constructed using a Dirac operator and a weight. We consider the Dirac operator introduced by Kaad and Senior and a family of weights depending on two parameters, which are related to the diagonal automorphisms of SU q (2). We show that, after fixing one of the parameters, the non-commutative integral coincides with the Haar state of SU q (2). Moreover we can impose an additional condition on the zeta function, which also fixes the second parameter. For this unique choice the spectral dimension coincides with the classical dimension

  10. Unusual poles of the {zeta}-functions for some regular singular differential operators

    Energy Technology Data Exchange (ETDEWEB)

    Falomir, H [IFLP, Departamento de Fisica-Facultad de Ciencias Exactas, UNLP, CC 67 (1900) La Plata (Argentina); Muschietti, M A [Departamento de Matematica-Facultad de Ciencias Exactas, UNLP, CC 172 (1900) La Plata (Argentina); Pisani, P A G [IFLP, Departamento de Fisica-Facultad de Ciencias Exactas, UNLP, CC 67 (1900) La Plata (Argentina); Seeley, R [University of Massachusetts at Boston, Boston, MA 02125 (United States)

    2003-10-03

    We consider the resolvent of a system of first-order differential operators with a regular singularity, admitting a family of self-adjoint extensions. We find that the asymptotic expansion for the resolvent in the general case presents powers of {lambda} which depend on the singularity, and can take even irrational values. The consequences for the pole structure of the corresponding {zeta}- and {eta}-functions are also discussed.

  11. Fractal zeta functions and fractal drums higher-dimensional theory of complex dimensions

    CERN Document Server

    Lapidus, Michel L; Žubrinić, Darko

    2017-01-01

    This monograph gives a state-of-the-art and accessible treatment of a new general higher-dimensional theory of complex dimensions, valid for arbitrary bounded subsets of Euclidean spaces, as well as for their natural generalization, relative fractal drums. It provides a significant extension of the existing theory of zeta functions for fractal strings to fractal sets and arbitrary bounded sets in Euclidean spaces of any dimension. Two new classes of fractal zeta functions are introduced, namely, the distance and tube zeta functions of bounded sets, and their key properties are investigated. The theory is developed step-by-step at a slow pace, and every step is well motivated by numerous examples, historical remarks and comments, relating the objects under investigation to other concepts. Special emphasis is placed on the study of complex dimensions of bounded sets and their connections with the notions of Minkowski content and Minkowski measurability, as well as on fractal tube formulas. It is shown for the f...

  12. Spectral zeta function and non-perturbative effects in ABJM Fermi-gas

    International Nuclear Information System (INIS)

    Hatsuda, Yasuyuki

    2015-03-01

    The exact partition function in ABJM theory on three-sphere can be regarded as a canonical partition function of a non-interacting Fermi-gas with an unconventional Hamiltonian. All the information on the partition function is encoded in the discrete spectrum of this Hamiltonian. We explain how (quantum mechanical) non-perturbative corrections in the Fermi-gas system appear from a spectral consideration. Basic tools in our analysis are a Mellin-Barnes type integral representation and a spectral zeta function. From a consistency with known results, we conjecture that the spectral zeta function in the ABJM Fermi-gas has an infinite number of ''non-perturbative'' poles, which are invisible in the semi-classical expansion of the Planck constant. We observe that these poles indeed appear after summing up perturbative corrections. As a consequence, the perturbative resummation of the spectral zeta function causes non-perturbative corrections to the grand canonical partition function. We also present another example associated with a spectral problem in topological string theory. A conjectured non-perturbative free energy on the resolved conifold is successfully reproduced in this framework.

  13. Clinical and Laboratory Potential Predictors of Blood Culture Positivity in Under Five Children with Clinically Severe Pneumonia - Khartoum -Sudan.

    Science.gov (United States)

    Salih, Karimeldin Mohamed Ali; El-Samani, El-Fatih; Bilal, Jalal Ali; Eldouch, Widad; Ibrahim, Salah Ahmed

    2015-08-01

    Blood culture is necessary for appropriate management of clinically severe pneumonia in children under five years of age. However, in limited resource countries it might be unduly costly and waste of valuable time because of the high negative culture rate. This study aims to identify clinical and laboratory parameters that potentially predict a positive blood culture in cases of severe pneumonia. A hospital based study, enrolled 189 cases satisfying the WHO definition of severe pneumonia. Age, gender, clinical history, physical examination, temperature, complete blood count, C-reactive protein, blood culture and Chest X Ray for all the patients were recorded. Forty one patients had positive blood culture giving a prevalence of 21.7%. All variables were used in a dichotomous manner. White Blood Count (WBC) more than 20 000, very high C-reactive protein (C-RP ≥8mg/L) and Temperature more than 40(o)C, had a positive predictive value of 46.1%, 44.3% and 40.0% respectively for a positive culture as well as a Negative Predictive Value of 91.1%, 91.6% and 91.7% respectively. The WBC more than 20 000 and temperature above 40(o)C had a significant association with a positive blood culture. Their adjusted Odds Ratios were 3.9 (95% CI: 1.4-10.90) and 3.1 (95% CI: 1.2-8.4) respectively. This was not the case for C-RP (Odds Ratio=2.2, 95% CI: 0.7-2.2) or positive Chest X Ray (Odds Ratio=1.5, 95% CI: 0.6-3.6). Temperature of more than 40(o)C, Very high C-RP and WBC of more than 20 000 are good indicators of a potential positive blood culture. It is therefore recommended that further research be undertaken to refine these predictors as screening tools before resorting to blood culture. It is also recommended that antibiotic treatment may be initiated on the basis of the high temperature and WBC, while waiting for the culture results.

  14. State Anxiety Carried Over From Prior Threat Increases Late Positive Potential Amplitude During an Instructed Emotion Regulation Task

    Science.gov (United States)

    Pedersen, Walker S.; Larson, Christine L.

    2018-01-01

    Emotion regulation has important consequences for emotional and mental health (Saxena, Dubey & Pandey, 2011) and is dependent on executive function (Eisenberg, Smith & Spinrad, 2011). Because state anxiety disrupts executive function (Robinson, Vytal, Cornwell & Grillon, 2013), we tested whether state anxiety disrupts emotion regulation by having participants complete an instructed emotion regulation task, while under threat of unpredictable shock and while safe from shock. We used the late positive potential (LPP) component of the event related potential to measure emotion regulation success. We predicted that LPP responses to negatively valenced images would be modulated by participants’ attempts to increase and decrease their emotions when safe from shock, but not while under threat of shock. Our manipulation check revealed an order effect such that for participants who completed the threat of shock condition first self-reported state anxiety carried over into the subsequent safe condition. Additionally, we found that although instructions to regulate affected participants’ ratings of how unpleasant the images made them feel, instructions to regulate had no effect on LPP amplitude regardless of threat condition. Instead we found that participants who received the threat condition prior to safe had greater LPP responses to all images in the safe condition. We posit that the carryover of anxiety resulted in misattribution of arousal and potentiation of neural responses to the images in the safe condition. Thus, our results imply that physiological arousal and cognition combine to influence the basic neural response to emotional stimuli. PMID:27055095

  15. Can empathy, other personality attributes, and level of positive social influence in medical school identify potential leaders in medicine?

    Science.gov (United States)

    Hojat, Mohammadreza; Michalec, Barret; Veloski, J Jon; Tykocinski, Mark L

    2015-04-01

    To test the hypotheses that medical students recognized by peers as the most positive social influencers would score (1) high on measures of engaging personality attributes that are conducive to relationship building (empathy, sociability, activity, self-esteem), and (2) low on disengaging personality attributes that are detrimental to interpersonal relationships (loneliness, neuroticism, aggression-hostility, impulsive sensation seeking). The study included 666 Jefferson Medical College students who graduated in 2011-2013. Students used a peer nomination instrument to identify classmates who had a positive influence on their professional and personal development. At matriculation, these students had completed a survey that included the Jefferson Scale of Empathy and Zuckerman-Kuhlman Personality Questionnaire short form and abridged versions of the Rosenberg Self-Esteem Scale and UCLA Loneliness Scale. In multivariate analyses of variance, the method of contrasted groups was used to compare the personality attributes of students nominated most frequently by their peers as positive influencers (top influencers [top 25% in their class distribution], n = 176) with those of students nominated least frequently (bottom influencers [bottom 25%], n = 171). The top influencers scored significantly higher on empathy, sociability, and activity and significantly lower on loneliness compared with the bottom influencers. However, the effect size estimates of the differences were moderate at best. The research hypotheses were partially confirmed. Positive social influencers appear to possess personality attributes conducive to relationship building, which is an important feature of effective leadership. The findings have implications for identifying and training potential leaders in medicine.

  16. Assessing the Electrode-Neuron Interface with the Electrically Evoked Compound Action Potential, Electrode Position, and Behavioral Thresholds.

    Science.gov (United States)

    DeVries, Lindsay; Scheperle, Rachel; Bierer, Julie Arenberg

    2016-06-01

    Variability in speech perception scores among cochlear implant listeners may largely reflect the variable efficacy of implant electrodes to convey stimulus information to the auditory nerve. In the present study, three metrics were applied to assess the quality of the electrode-neuron interface of individual cochlear implant channels: the electrically evoked compound action potential (ECAP), the estimation of electrode position using computerized tomography (CT), and behavioral thresholds using focused stimulation. The primary motivation of this approach is to evaluate the ECAP as a site-specific measure of the electrode-neuron interface in the context of two peripheral factors that likely contribute to degraded perception: large electrode-to-modiolus distance and reduced neural density. Ten unilaterally implanted adults with Advanced Bionics HiRes90k devices participated. ECAPs were elicited with monopolar stimulation within a forward-masking paradigm to construct channel interaction functions (CIF), behavioral thresholds were obtained with quadrupolar (sQP) stimulation, and data from imaging provided estimates of electrode-to-modiolus distance and scalar location (scala tympani (ST), intermediate, or scala vestibuli (SV)) for each electrode. The width of the ECAP CIF was positively correlated with electrode-to-modiolus distance; both of these measures were also influenced by scalar position. The ECAP peak amplitude was negatively correlated with behavioral thresholds. Moreover, subjects with low behavioral thresholds and large ECAP amplitudes, averaged across electrodes, tended to have higher speech perception scores. These results suggest a potential clinical role for the ECAP in the objective assessment of individual cochlear implant channels, with the potential to improve speech perception outcomes.

  17. Finite temperature Casimir energy in closed rectangular cavities: a rigorous derivation based on a zeta function technique

    International Nuclear Information System (INIS)

    Lim, S C; Teo, L P

    2007-01-01

    We derive rigorously explicit formulae of the Casimir free energy at finite temperature for massless scalar field and electromagnetic field confined in a closed rectangular cavity with different boundary conditions by a zeta regularization method. We study both the low and high temperature expansions of the free energy. In each case, we write the free energy as a sum of a polynomial in temperature plus exponentially decay terms. We show that the free energy is always a decreasing function of temperature. In the cases of massless scalar field with the Dirichlet boundary condition and electromagnetic field, the zero temperature Casimir free energy might be positive. In each of these cases, there is a unique transition temperature (as a function of the side lengths of the cavity) where the Casimir energy changes from positive to negative. When the space dimension is equal to two and three, we show graphically the dependence of this transition temperature on the side lengths of the cavity. Finally we also show that we can obtain the results for a non-closed rectangular cavity by letting the size of some directions of a closed cavity go to infinity, and we find that these results agree with the usual integration prescription adopted by other authors

  18. Plant operator selection system for evaluating employment candidates' potential for success in electric power plant operations positions

    International Nuclear Information System (INIS)

    Dunnette, M.D.

    1982-01-01

    The Plant Operator Selection System is a battery of tests and questionnaires that can be administered to job candidates in less than three hours. Various components of the battery measure what a job candidate has accomplished in previous educational and work situations, how well a candidate compares with others on a number of important aptitudes or abilities, and whether or not a candidate possesses the kind of personal stability required in power plant operations positions. A job candidate's answers to the tests and questionnaires of the Plant Operator Selection System are scored and converted to an OVERALL POTENTIAL INDEX. Values of the OVERALL POTENTIAL INDEX [OPI] range between 0 and 15. Candidates with high OPI values are much more likely to become effective and successful plant operators than candidates with low OPI values. It is possible to estimate the financial advantages to a company of using the Plant Operator Selection System in evaluating candidates for plant operations jobs

  19. Spatial profile measurements of ion-confining potentials using novel position-sensitive ion-energy spectrometer arrays

    International Nuclear Information System (INIS)

    Yoshida, M.; Cho, T.; Hirata, M.; Ito, H.; Kohagura, J.; Yatsu, K.; Miyoshi, S.

    2003-01-01

    The first experimental demonstration of simultaneous measurements of temporally and spatially resolved ion-confining potentials phi c and end-loss-ion fluxes I ELA has been carried out during a single plasma discharge alone by the use of newly designed ion-energy-spectrometer arrays installed in both end regions of the GAMMA 10 tandem mirror. This position-sensitive ion-detector structure is proposed to obtain precise ion-energy spectra without any perturbations from simultaneously incident energetic electrons into the arrays. The relation between phi c and I ELA is physically interpreted in terms of Pastukhov's potential confinement theory. In particular, the importance of axisymmetric phi c formation is found for the plasma confinement

  20. The dynamic allocation of attention to emotion: simultaneous and independent evidence from the late positive potential and steady state visual evoked potentials.

    Science.gov (United States)

    Hajcak, Greg; MacNamara, Annmarie; Foti, Dan; Ferri, Jamie; Keil, Andreas

    2013-03-01

    Emotional stimuli capture and hold attention without explicit instruction. The late positive potential (LPP) component of the event related potential can be used to track motivated attention toward emotional stimuli, and is larger for emotional compared to neutral pictures. In the frequency domain, the steady state visual evoked potential (ssVEP) has also been used to track attention to stimuli flickering at a particular frequency. Like the LPP, the ssVEP is also larger for emotional compared to neutral pictures. Prior work suggests that both the LPP and ssVEP are sensitive to "top-down" manipulations of attention, however the LPP and ssVEP have not previously been examined using the same attentional manipulation in the same participants. In the present study, LPP and ssVEP amplitudes were simultaneously elicited by unpleasant and neutral pictures. Partway through picture presentation, participants' attention was directed toward an arousing or non-arousing region of unpleasant pictures. In line with prior work, the LPP was reduced when attention was directed toward non-arousing compared to arousing regions of unpleasant pictures; similar results were observed for the ssVEP. Thus, both electrocortical measures index affective salience and are sensitive to directed (here: spatial) attention. Variation in the LPP and ssVEP was unrelated, suggesting that these measures are not redundant with each other and may capture different neurophysiological aspects of affective stimulus processing and attention. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Statistical properties of the zeros of zeta functions - beyond the Riemann case

    International Nuclear Information System (INIS)

    Bogomolny, E.; Leboeuf, P.

    1993-09-01

    The statistical distribution of the zeros of Dirichlet L-functions is investigated both analytically and numerically. Using the Hardy-Littlewood conjecture about the distribution of primes it is shown that the two-point correlation function of these zeros coincides with that for eigenvalues of the Gaussian unitary ensemble of random matrices, and that the distributions of zeros of different L-functions are statistically independent. Applications of these results to Epstein's zeta functions are shortly discussed. (authors) 30 refs., 3 figs., 1 tab

  2. Fractional parts and their relations to the values of the Riemann zeta function

    KAUST Repository

    Alabdulmohsin, Ibrahim

    2017-09-06

    A well-known result, due to Dirichlet and later generalized by de la Vallée–Poussin, expresses a relationship between the sum of fractional parts and the Euler–Mascheroni constant. In this paper, we prove an asymptotic relationship between the summation of the products of fractional parts with powers of integers on the one hand, and the values of the Riemann zeta function, on the other hand. Dirichlet’s classical result falls as a particular case of this more general theorem.

  3. On the irrationality measure for a q-analogue of \\zeta(2)

    Science.gov (United States)

    Zudilin, W. V.

    2002-08-01

    A Liouville-type estimate is proved for the irrationality measure of the quantities \\displaystyle \\zeta_q(2)=\\sum_{n=1}^\\infty\\frac{q^n}{(1-q^n)^2}with q^{-1}\\in\\mathbb Z\\setminus\\{0,\\pm1\\}. The proof is based on the application of a q-analogue of the arithmetic method developed by Chudnovsky, Rukhadze, and Hata and of the transformation group for hypergeometric series-the group-structure approach introduced by Rhin and Viola.

  4. Fractional parts and their relations to the values of the Riemann zeta function

    KAUST Repository

    Alabdulmohsin, Ibrahim

    2017-01-01

    A well-known result, due to Dirichlet and later generalized by de la Vallée–Poussin, expresses a relationship between the sum of fractional parts and the Euler–Mascheroni constant. In this paper, we prove an asymptotic relationship between the summation of the products of fractional parts with powers of integers on the one hand, and the values of the Riemann zeta function, on the other hand. Dirichlet’s classical result falls as a particular case of this more general theorem.

  5. Applications of Wirtinger Inequalities on the Distribution of Zeros of the Riemann Zeta-Function

    Directory of Open Access Journals (Sweden)

    Saker SamirH

    2010-01-01

    Full Text Available On the hypothesis that the th moments of the Hardy -function are correctly predicted by random matrix theory and the moments of the derivative of are correctly predicted by the derivative of the characteristic polynomials of unitary matrices, we establish new large spaces between the zeros of the Riemann zeta-function by employing some Wirtinger-type inequalities. In particular, it is obtained that which means that consecutive nontrivial zeros often differ by at least 6.1392 times the average spacing.

  6. Hearing the music of the primes: auditory complementarity and the siren song of zeta

    International Nuclear Information System (INIS)

    Berry, M V

    2012-01-01

    A counting function for the primes can be rendered as a sound signal whose harmonies, spanning the gamut of musical notes, are the Riemann zeros. But the individual primes cannot be discriminated as singularities in this ‘music’, because the intervals between them are too short. Conversely, if the prime singularities are detected as a series of clicks, the Riemann zeros correspond to frequencies too low to be heard. The sound generated by the Riemann zeta function itself is very different: a rising siren howl, which can be understood in detail from the Riemann–Siegel formula. (fast track communication)

  7. Trial sequential analysis reveals insufficient information size and potentially false positive results in many meta-analyses

    DEFF Research Database (Denmark)

    Brok, J.; Thorlund, K.; Gluud, C.

    2008-01-01

    in 80% (insufficient information size). TSA(15%) and TSA(LBHIS) found that 95% and 91% had absence of evidence. The remaining nonsignificant meta-analyses had evidence of lack of effect. CONCLUSION: TSA reveals insufficient information size and potentially false positive results in many meta......OBJECTIVES: To evaluate meta-analyses with trial sequential analysis (TSA). TSA adjusts for random error risk and provides the required number of participants (information size) in a meta-analysis. Meta-analyses not reaching information size are analyzed with trial sequential monitoring boundaries...... analogous to interim monitoring boundaries in a single trial. STUDY DESIGN AND SETTING: We applied TSA on meta-analyses performed in Cochrane Neonatal reviews. We calculated information sizes and monitoring boundaries with three different anticipated intervention effects of 30% relative risk reduction (TSA...

  8. Potential clinical applications of {sup 18}F-fluorodeoxyglucose position emission tomography/magnetic resonance mammography in breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Ihn Ho; Kong, Eun Jung [Dept. of Nuclear Medicine, Yeugnam University Hospital, Daegu (Korea, Republic of)

    2017-09-15

    The whole-body positron emission tomography (PET)/magnetic resonance (MR) scan is a cutting edge technology providing comprehensive structural information from MR imaging and functional features from PET in a single session. Recent research findings and clinical experience have shown that 18F-fluorodeoxyglucose (FDG) whole-body PET/MR imaging has a diagnostic performance comparable with or superior to that of PET/CT in the field of oncology, including for breast cancer. In particular, FDG PET/MR mammography in the prone position with the breast hanging in a pendant manner can provide more comprehensive information about the metabolism, anatomy, and functional features of a breast lesion than a whole-body PET/MR scan. This article reports on current state-of-the-art PET/MR mammography in patients with breast cancer and the prospects for potential application in the future.

  9. Presence and potential for horizontal transfer of antibiotic resistance in oxidase-positive bacteria populating raw salad vegetables.

    Science.gov (United States)

    Bezanson, G S; MacInnis, R; Potter, G; Hughes, T

    2008-09-30

    To assess whether domestically grown fresh salad vegetables constitute a possible reservoir of antibiotic resistance for Canadian consumers, aerobic bacteria capable of forming colonies at 30 degrees C on nutrient-limited media were recovered from a single sampling of Romaine lettuce, Savoy spinach and alfalfa sprouts, then examined for their susceptibility to ten antibiotics and the carriage of potentially mobile R-plasmids and integrons. Of the 140 isolates resistant to one or more antibiotic, 93.5 and 90.0% were resistant to ampicillin and cephalothin; 35.7% to chloramphenicol, 10.0% to streptomycin, 4.2% to nalidixic acid, 4.2% to kanamycin, and 2.8% to gentamicin. Gram-positive isolates accounted for less than 4% of the antibiotic resistant strains. A small portion (23.1%) of the predominant oxidase-positive, gram-negative isolates was resistant to two or more antimicrobials. Members of the Pseudomonas fluorescens/putida complex were most prevalent among the 34 resistant strains identified. Sphingobacterium spp. and Acinetobacter baumanni also were detected. Ten of 52 resistant strains carried plasmids, 3 of which were self-transmissible and bore resistance to ampicillin and kanamycin. Eighteen of 48 gave PCR evidence for integron DNA. Class 2 type integrons were the most prevalent, followed by class 1. We conclude that the foods examined here carry antibiotic resistant bacteria at the retail level. Further, our determination that resistant strains contain integron-specific DNA sequences and self-transmissible R-plasmids indicates their potential to influence the pool of antibiotic resistance in humans via lateral gene transfer subsequent to ingestion.

  10. The effect of emotional content on brain activation and the late positive potential in a word n-back task.

    Directory of Open Access Journals (Sweden)

    Juliane Kopf

    Full Text Available INTRODUCTION: There is mounting evidence for the influence of emotional content on working memory performance. This is particularly important in light of the emotion processing that needs to take place when emotional content interferes with executive functions. In this study, we used emotional words of different valence but with similar arousal levels in an n-back task. METHODS: We examined the effects on activation in the prefrontal cortex by means of functional near-infrared spectroscopy (fNIRS and on the late positive potential (LPP. FNIRS and LPP data were examined in 30 healthy subjects. RESULTS: BEHAVIORAL RESULTS SHOW AN INFLUENCE OF VALENCE ON THE ERROR RATE DEPENDING ON THE DIFFICULTY OF THE TASK: more errors were made when the valence was negative and the task difficult. Brain activation was dependent both on the difficulty of the task and on the valence: negative valence of a word diminished the increase in activation, whereas positive valence did not influence the increase in activation, while difficulty levels increased. The LPP also differentiated between the different valences, and in addition was influenced by the task difficulty, the more difficult the task, the less differentiation could be observed. CONCLUSIONS: Summarized, this study shows the influence of valence on a verbal working memory task. When a word contained a negative valence, the emotional content seemed to take precedence in contrast to words containing a positive valence. Working memory and emotion processing sites seemed to overlap and compete for resources even when words are carriers of the emotional content.

  11. Streaming Potential and Electroosmosis Measurements to Characterize Porous Materials

    NARCIS (Netherlands)

    Luong, D.T.; Sprik, R.

    2013-01-01

    Characterizing the streaming potential and electroosmosis properties of porous media is essential in applying seismoelectric and electroseismic phenomena for oil exploration. Some parameters such as porosity, permeability, formation factor, pore size, the number of pores, and the zeta potential of

  12. The late positive potential as a marker of motivated attention to underweight bodies in girls with anorexia nervosa.

    Science.gov (United States)

    Horndasch, Stefanie; Heinrich, Hartmut; Kratz, Oliver; Moll, Gunther H

    2012-12-01

    In anorexia nervosa (AN), aspects of motivational salience and reward are increasingly discussed. Event related potentials, particularly the late positive potential (LPP), have been investigated as a marker for motivational salience of stimuli, for example in addictive disorders. The aim of this study was to assess the LPP as a possible indicator of motivated attention towards disease-specific pictures of underweight female bodies in adolescents with AN in comparison to typically developing (TD) adolescent girls. 13 girls with AN and 18 TD adolescent girls (aged 12 to 18 years) viewed pictures of underweight, normal-weight and overweight women while EEG activity was recorded. An earlier (450-680 ms after stimulus onset) as well as a later time window (850-1250 ms after stimulus onset) of the LPP were examined for the different picture categories. Participants were also asked to rate subjective emotions (fear, disgust, happiness) elicited by the pictures. Subjective ratings showed no differential experience of emotions for the two groups. For AN patients, highest LPP amplitudes were found for underweight women in the earlier as well as in the later time window. In TD girls, highest amplitudes for pictures of overweight women were observed in the earlier time window. A differential LPP pattern for girls with AN and TD girls when viewing pictures of women's bodies of different weight categories was obtained. Highest amplitudes in AN patients for pictures of underweight women may reflect motivational significance of strongly underweight body shapes. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Mutations in the maize zeta-carotene desaturase gene lead to viviparous kernel.

    Directory of Open Access Journals (Sweden)

    Yan Chen

    Full Text Available Preharvest sprouting reduces the maize quality and causes a significant yield loss in maize production. vp-wl2 is a Mutator (Mu-induced viviparous mutant in maize, causing white or pale yellow kernels, dramatically reduced carotenoid and ABA content, and a high level of zeta-carotene accumulation. Here, we reported the cloning of the vp-wl2 gene using a modified digestion-ligation-amplification method (DLA. The results showed that an insertion of Mu9 in the first intron of the zeta-carotene desaturase (ZDS gene results in the vp-wl2 mutation. Previous studies have suggested that ZDS is likely the structural gene of the viviparous9 (vp9 locus. Therefore, we performed an allelic test using vp-wl2 and three vp9 mutants. The results showed that vp-wl2 is a novel allele of the vp9 locus. In addition, the sequences of ZDS gene were identified in these three vp9 alleles. The vp-wl2 mutant gene was subsequently introgressed into four maize inbred lines, and a viviparous phenotype was observed with yield losses from 7.69% to 13.33%.

  14. Potential mechanism of corpus-predominant gastritis after PPI therapy in Helicobacter pylori-positive patients with GERD.

    Science.gov (United States)

    Mukaisho, Ken-ichi; Hagiwara, Tadashi; Nakayama, Takahisa; Hattori, Takanori; Sugihara, Hiroyuki

    2014-09-14

    The long-term use of proton pump inhibitors (PPIs) exacerbates corpus atrophic gastritis in patients with Helicobacter pylori (H. pylori) infection. To identify a potential mechanism for this change, we discuss interactions between pH, bile acids, and H. pylori. Duodenogastric reflux, which includes bile, occurs in healthy individuals, and bile reflux is increased in patients with gastroesophageal reflux disease (GERD). Diluted human plasma and bile acids have been found to be significant chemoattractants and chemorepellents, respectively, for the bacillus H. pylori. Although only taurine conjugates, with a pKa of 1.8-1.9, are soluble in an acidic environment, glycine conjugates, with a pKa of 4.3-5.2, as well as taurine-conjugated bile acids are soluble in the presence of PPI therapy. Thus, the soluble bile acid concentrations in the gastric contents of patients with GERD after continuous PPI therapy are considerably higher than that in those with intact acid production. In the distal stomach, the high concentration of soluble bile acids is likely to act as a bactericide or chemorepellent for H. pylori. In contrast, the mucous layer in the proximal stomach has an optimal bile concentration that forms chemotactic gradients with plasma components required to direct H. pylori to the epithelial surface. H. pylori may then colonize in the stomach body rather than in the pyloric antrum, which may explain the occurrence of corpus-predominant gastritis after PPI therapy in H. pylori-positive patients with GERD.

  15. Use of Anthropogenic Sea Floor Structures by Australian Fur Seals: Potential Positive Ecological Impacts of Marine Industrial Development?

    Science.gov (United States)

    Arnould, John P Y; Monk, Jacquomo; Ierodiaconou, Daniel; Hindell, Mark A; Semmens, Jayson; Hoskins, Andrew J; Costa, Daniel P; Abernathy, Kyler; Marshall, Greg J

    2015-01-01

    Human-induced changes to habitats can have deleterious effects on many species that occupy them. However, some species can adapt and even benefit from such modifications. Artificial reefs have long been used to provide habitat for invertebrate communities and promote local fish populations. With the increasing demand for energy resources within ocean systems, there has been an expansion of infrastructure in near-shore benthic environments which function as de facto artificial reefs. Little is known of their use by marine mammals. In this study, the influence of anthropogenic sea floor structures (pipelines, cable routes, wells and shipwrecks) on the foraging locations of 36 adult female Australian fur seals (Arctocephalus pusillus doriferus) was investigated. For 9 (25%) of the individuals, distance to anthropogenic sea floor structures was the most important factor in determining the location of intensive foraging activity. Whereas the influence of anthropogenic sea floor structures on foraging locations was not related to age and mass, it was positively related to flipper length/standard length (a factor which can affect manoeuvrability). A total of 26 (72%) individuals tracked with GPS were recorded spending time in the vicinity of structures (from 75% of the foraging trip duration) with pipelines and cable routes being the most frequented. No relationships were found between the amount of time spent frequenting anthropogenic structures and individual characteristics. More than a third (35%) of animals foraging near anthropogenic sea floor structures visited more than one type of structure. These results further highlight potentially beneficial ecological outcomes of marine industrial development.

  16. High mobility group box-1 is phosphorylated by protein kinase C zeta and secreted in colon cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hanna; Park, Minhee; Shin, Nara; Kim, Gamin [Department of Pathology, Yonsei University College of Medicine, 134 Shinchon-Dong, Seodaemoon-Ku, Seoul (Korea, Republic of); Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, 134 Shinchon-Dong, Seodaemoon-Ku, Seoul (Korea, Republic of); Kim, Yun Gi [Department of Internal Medicine, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-744 (Korea, Republic of); Shin, Jeon-Soo [Department of Microbiology, Yonsei University College of Medicine, 134 Shinchon-Dong, Seodaemoon-Ku, Seoul (Korea, Republic of); Kim, Hoguen, E-mail: hkyonsei@yuhs.ac [Department of Pathology, Yonsei University College of Medicine, 134 Shinchon-Dong, Seodaemoon-Ku, Seoul (Korea, Republic of); Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, 134 Shinchon-Dong, Seodaemoon-Ku, Seoul (Korea, Republic of)

    2012-07-27

    Highlights: Black-Right-Pointing-Pointer Specific enzyme for HMGB1 phosphorylation and its secretion is proposed. Black-Right-Pointing-Pointer Inhibition of PKC-{zeta} leads to significant reduction of the secreted HMGB1. Black-Right-Pointing-Pointer Phosphorylation of specific site of HMGB1 redirects its secretion in cancer cells. Black-Right-Pointing-Pointer Activation of PKC-{zeta} in cancers explains the enhanced HMGB1 secretion. -- Abstract: High mobility group box-1 (HMGB1), a nuclear protein, is overexpressed and secreted in cancer cells. Phosphorylation on two different nuclear localization signal regions are known to be important for the nuclear-to-cytoplasmic transport and secretion of HMGB1. However, little is known about the biochemical mechanism of HMGB1 modifications and its subsequent secretion from cancer cells. To identify the specific enzyme and important sites for HMGB1 phosphorylation, we screened the protein kinase C (PKC) family in a colon cancer cell line (HCT116) for HMGB1 binding by pull-down experiments using a 3XFLAG-HMGB1 construct. Strong interactions between atypical PKCs (PKC-{zeta}, {lambda}, and {iota}) and cytoplasmic HMGB1 were observed in HCT116 cells. We further identified the most critical PKC isotype that regulates HMGB1 secretion is PKC-{zeta} by using PKC inhibitors and siRNA experiments. The serine residues at S39, S53 and S181 of HMGB1 were related to enhancing HMGB1 secretion. We also demonstrated overexpression and activation of PKC-{zeta} in colon cancer tissues. Our findings suggest that PKC-{zeta} is involved in the phosphorylation of HMGB1, and the phosphorylation of specific serine residues in the nuclear localization signal regions is related to enhanced HMGB1 secretion in colon cancer cells.

  17. Dynamical zeta functions and dynamical determinants for hyperbolic maps a functional approach

    CERN Document Server

    Baladi, Viviane

    2018-01-01

    The spectra of transfer operators associated to dynamical systems, when acting on suitable Banach spaces, contain key information about the ergodic properties of the systems. Focusing on expanding and hyperbolic maps, this book gives a self-contained account on the relation between zeroes of dynamical determinants, poles of dynamical zeta functions, and the discrete spectra of the transfer operators. In the hyperbolic case, the first key step consists in constructing a suitable Banach space of anisotropic distributions. The first part of the book is devoted to the easier case of expanding endomorphisms, showing how the (isotropic) function spaces relevant there can be studied via Paley–Littlewood decompositions, and allowing easier access to the construction of the anisotropic spaces which is performed in the second part. This is the first book describing the use of anisotropic spaces in dynamics. Aimed at researchers and graduate students, it presents results and techniques developed since the beginning of...

  18. Relations between elliptic multiple zeta values and a special derivation algebra

    International Nuclear Information System (INIS)

    Broedel, Johannes; Matthes, Nils; Schlotterer, Oliver

    2016-01-01

    We investigate relations between elliptic multiple zeta values (eMZVs) and describe a method to derive the number of indecomposable elements of given weight and length. Our method is based on representing eMZVs as iterated integrals over Eisenstein series and exploiting the connection with a special derivation algebra. Its commutator relations give rise to constraints on the iterated integrals over Eisenstein series relevant for eMZVs and thereby allow to count the indecomposable representatives. Conversely, the above connection suggests apparently new relations in the derivation algebra. Under https://tools.aei.mpg.de/emzv we provide relations for eMZVs over a wide range of weights and lengths. (paper)

  19. Uncoupling of T Cell Receptor Zeta Chain Function during the Induction of Anergy by the Superantigen, Staphylococcal Enterotoxin A

    Directory of Open Access Journals (Sweden)

    William D. Cornwell

    2010-06-01

    Full Text Available Staphylococcus aureus enterotoxins have immunomodulatory properties. In this study, we show that Staphylococcal enterotoxin A (SEA induces a strong proliferative response in a murine T cell clone independent of MHC class II bearing cells. SEA stimulation also induces a state of hypo-responsiveness (anergy. We characterized the components of the T cell receptor (TCR during induction of anergy by SEA. Most interestingly, TCR zeta chain phosphorylation was absent under SEA anergizing conditions, which suggests an uncoupling of zeta chain function. We characterize here a model system for studying anergy in the absence of confounding costimulatory signals.

  20. Use of Anthropogenic Sea Floor Structures by Australian Fur Seals: Potential Positive Ecological Impacts of Marine Industrial Development?

    Directory of Open Access Journals (Sweden)

    John P Y Arnould

    Full Text Available Human-induced changes to habitats can have deleterious effects on many species that occupy them. However, some species can adapt and even benefit from such modifications. Artificial reefs have long been used to provide habitat for invertebrate communities and promote local fish populations. With the increasing demand for energy resources within ocean systems, there has been an expansion of infrastructure in near-shore benthic environments which function as de facto artificial reefs. Little is known of their use by marine mammals. In this study, the influence of anthropogenic sea floor structures (pipelines, cable routes, wells and shipwrecks on the foraging locations of 36 adult female Australian fur seals (Arctocephalus pusillus doriferus was investigated. For 9 (25% of the individuals, distance to anthropogenic sea floor structures was the most important factor in determining the location of intensive foraging activity. Whereas the influence of anthropogenic sea floor structures on foraging locations was not related to age and mass, it was positively related to flipper length/standard length (a factor which can affect manoeuvrability. A total of 26 (72% individuals tracked with GPS were recorded spending time in the vicinity of structures (from 75% of the foraging trip duration with pipelines and cable routes being the most frequented. No relationships were found between the amount of time spent frequenting anthropogenic structures and individual characteristics. More than a third (35% of animals foraging near anthropogenic sea floor structures visited more than one type of structure. These results further highlight potentially beneficial ecological outcomes of marine industrial development.

  1. Protein kinase C zeta suppresses low- or high-grade colorectal cancer (CRC) phenotypes by interphase centrosome anchoring.

    Science.gov (United States)

    Deevi, Ravi Kiran; Javadi, Arman; McClements, Jane; Vohhodina, Jekaterina; Savage, Kienan; Loughrey, Maurice Bernard; Evergren, Emma; Campbell, Frederick Charles

    2018-04-01

    Histological grading provides prognostic stratification of colorectal cancer (CRC) by scoring heterogeneous phenotypes. Features of aggressiveness include aberrant mitotic spindle configurations, chromosomal breakage, and bizarre multicellular morphology, but pathobiology is poorly understood. Protein kinase C zeta (PKCz) controls mitotic spindle dynamics, chromosome segregation, and multicellular patterns, but its role in CRC phenotype evolution remains unclear. Here, we show that PKCz couples genome segregation to multicellular morphology through control of interphase centrosome anchoring. PKCz regulates interdependent processes that control centrosome positioning. Among these, interaction between the cytoskeletal linker protein ezrin and its binding partner NHERF1 promotes the formation of a localized cue for anchoring interphase centrosomes to the cell cortex. Perturbation of these phenomena induced different outcomes in cells with single or extra centrosomes. Defective anchoring of a single centrosome promoted bipolar spindle misorientation, multi-lumen formation, and aberrant epithelial stratification. Collectively, these disturbances induce cribriform multicellular morphology that is typical of some categories of low-grade CRC. By contrast, defective anchoring of extra centrosomes promoted multipolar spindle formation, chromosomal instability (CIN), disruption of glandular morphology, and cell outgrowth across the extracellular matrix interface characteristic of aggressive, high-grade CRC. Because PKCz enhances apical NHERF1 intensity in 3D epithelial cultures, we used an immunohistochemical (IHC) assay of apical NHERF1 intensity as an indirect readout of PKCz activity in translational studies. We show that apical NHERF1 IHC intensity is inversely associated with multipolar spindle frequency and high-grade morphology in formalin-fixed human CRC samples. To conclude, defective PKCz control of interphase centrosome anchoring may underlie distinct categories of

  2. Streaming potential near a rotating porous disk.

    Science.gov (United States)

    Prieve, Dennis C; Sides, Paul J

    2014-09-23

    Theory and experimental results for the streaming potential measured in the vicinity of a rotating porous disk-shaped sample are described. Rotation of the sample on its axis draws liquid into its face and casts it from the periphery. Advection within the sample engenders streaming current and streaming potential that are proportional to the zeta potential and the disk's major dimensions. When Darcy's law applies, the streaming potential is proportional to the square of the rotation at low rate but becomes invariant with rotation at high rate. The streaming potential is invariant with the sample's permeability at low rate and is proportional to the inverse square of the permeability at high rate. These predictions were tested by determining the zeta potential and permeability of the loop side of Velcro, a sample otherwise difficult to characterize; reasonable values of -56 mV for zeta and 8.7 × 10(-9) m(2) for the permeability were obtained. This approach offers the ability to determine both the zeta potential and the permeability of materials having open structures. Compressing them into a porous plug is unnecessary. As part of the development of the theory, a convenient formula for a flow-weighted volume-averaged space-charge density of the porous medium, -εζ/k, was obtained, where ε is the permittivity, ζ is the zeta potential, and k is the Darcy permeability. The formula is correct when Smoluchowski's equation and Darcy's law are both valid.

  3. Cellular uptake and cytotoxicity of positively charged chitosan gold nanoparticles in human lung adenocarcinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seon Young; Jang, Soo Hwa [Seoul National University, Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Institute for Veterinary Science (Korea, Republic of); Park, Jin; Jeong, Saeromi; Park, Jin Ho; Ock, Kwang Su [Soongsil University, Department of Chemistry (Korea, Republic of); Lee, Kangtaek [Yonsei University, Department of Chemical and Biomolecular Engineering (Korea, Republic of); Yang, Sung Ik [Kyung Hee University, College of Environment and Applied Chemistry (Korea, Republic of); Joo, Sang-Woo, E-mail: sjoo@ssu.ac.kr [Soongsil University, Department of Chemistry (Korea, Republic of); Ryu, Pan Dong; Lee, So Yeong, E-mail: leeso@snu.ac.kr [Seoul National University, Laboratory of Veterinary Pharmacology, College of Veterinary Medicine and Institute for Veterinary Science (Korea, Republic of)

    2012-12-15

    Cellular uptake, cytotoxicity, and mechanisms of cytotoxicity of the positively charged Au nanoparticles (NPs) were examined in A549 cells, which are one of the most characterized pulmonary cellular systems. Positively charged Au NPs were prepared by chemical reduction using chitosan. The dimension and surface charge of Au NPs were examined by transmission electron microscopy (TEM), dynamic light scattering, and zeta potential measurements. The uptake of Au NPs into A549 cells was also monitored using TEM and dark-field microscopy (DFM) and z-stack confocal microRaman spectroscopy. DFM live cell imaging was also performed to monitor the entry of chitosan Au NPs in real time. The cytotoxic assay, using both methylthiazol tetrazolium and lactate dehydrogenase assays revealed that positively charged Au NPs decreased cell viability. Flow cytometry, DNA fragmentation, real-time PCR, and western blot analysis suggest that positively charged chitosan Au NPs provoke cell damage through both apoptotic and necrotic pathways.

  4. Cellular uptake and cytotoxicity of positively charged chitosan gold nanoparticles in human lung adenocarcinoma cells

    International Nuclear Information System (INIS)

    Choi, Seon Young; Jang, Soo Hwa; Park, Jin; Jeong, Saeromi; Park, Jin Ho; Ock, Kwang Su; Lee, Kangtaek; Yang, Sung Ik; Joo, Sang-Woo; Ryu, Pan Dong; Lee, So Yeong

    2012-01-01

    Cellular uptake, cytotoxicity, and mechanisms of cytotoxicity of the positively charged Au nanoparticles (NPs) were examined in A549 cells, which are one of the most characterized pulmonary cellular systems. Positively charged Au NPs were prepared by chemical reduction using chitosan. The dimension and surface charge of Au NPs were examined by transmission electron microscopy (TEM), dynamic light scattering, and zeta potential measurements. The uptake of Au NPs into A549 cells was also monitored using TEM and dark-field microscopy (DFM) and z-stack confocal microRaman spectroscopy. DFM live cell imaging was also performed to monitor the entry of chitosan Au NPs in real time. The cytotoxic assay, using both methylthiazol tetrazolium and lactate dehydrogenase assays revealed that positively charged Au NPs decreased cell viability. Flow cytometry, DNA fragmentation, real-time PCR, and western blot analysis suggest that positively charged chitosan Au NPs provoke cell damage through both apoptotic and necrotic pathways.

  5. Redirecting Therapeutic T Cells against Myelin-Specific T Lymphocytes Using a Humanized Myelin Basic Protein-HLA-DR2-{zeta} Chimeric Receptor

    DEFF Research Database (Denmark)

    Moisini, Ioana; Nguyen, Phuong; Fugger, Lars

    2008-01-01

    Therapies that Ag-specifically target pathologic T lymphocytes responsible for multiple sclerosis (MS) and other autoimmune diseases would be expected to have improved therapeutic indices compared with Ag-nonspecific therapies. We have developed a cellular immunotherapy that uses chimeric receptors...... mouse model system. Finally, the chimeric receptor-modified CTL ameliorated or blocked experimental allergic encephalomyelitis (EAE) disease mediated by MBP(84-102)/DR2-specific T lymphocytes. These results provide support for the further development of redirected therapeutic T cells able to counteract...... pathologic, self-specific T lymphocytes, and specifically validate humanized MBP-DR2-zeta chimeric receptors as a potential therapeutic in MS. Udgivelsesdato: 2008-Mar-1...

  6. Igusa's $p$-Adic local zeta function and the monodromy conjecture for non-degenerate surface singularities

    CERN Document Server

    Bories, Bart

    2016-01-01

    In 2011 Lemahieu and Van Proeyen proved the Monodromy Conjecture for the local topological zeta function of a non-degenerate surface singularity. The authors start from their work and obtain the same result for Igusa's p-adic and the motivic zeta function. In the p-adic case, this is, for a polynomial f\\in\\mathbf{Z}[x,y,z] satisfying f(0,0,0)=0 and non-degenerate with respect to its Newton polyhedron, we show that every pole of the local p-adic zeta function of f induces an eigenvalue of the local monodromy of f at some point of f^{-1}(0)\\subset\\mathbf{C}^3 close to the origin. Essentially the entire paper is dedicated to proving that, for f as above, certain candidate poles of Igusa's p-adic zeta function of f, arising from so-called B_1-facets of the Newton polyhedron of f, are actually not poles. This turns out to be much harder than in the topological setting. The combinatorial proof is preceded by a study of the integral points in three-dimensional fundamental parallelepipeds. Together with the work of L...

  7. Methamphetamine-induced short-term increase and long-term decrease in spatial working memory affects protein Kinase M zeta (PKMζ), dopamine, and glutamate receptors.

    Science.gov (United States)

    Braren, Stephen H; Drapala, Damian; Tulloch, Ingrid K; Serrano, Peter A

    2014-01-01

    Methamphetamine (MA) is a toxic, addictive drug shown to modulate learning and memory, yet the neural mechanisms are not fully understood. We investigated the effects of 2 weekly injections of MA (30 mg/kg) on working memory using the radial 8-arm maze (RAM) across 5 weeks in adolescent-age mice. MA-treated mice show a significant improvement in working memory performance 1 week following the first MA injection compared to saline-injected controls. Following 5 weeks of MA abstinence mice were re-trained on a reference and working memory version of the RAM to assess cognitive flexibility. MA-treated mice show significantly more working memory errors without effects on reference memory performance. The hippocampus and dorsal striatum were assessed for expression of glutamate receptors subunits, GluA2 and GluN2B; dopamine markers, dopamine 1 receptor (D1), dopamine transporter (DAT) and tyrosine hydroxylase (TH); and memory markers, protein kinase M zeta (PKMζ) and protein kinase C zeta (PKCζ). Within the hippocampus, PKMζ and GluA2 are both significantly reduced after MA supporting the poor memory performance. Additionally, a significant increase in GluN2B and decrease in D1 identifies dysregulated synaptic function. In the striatum, MA treatment increased cytosolic DAT and TH levels associated with dopamine hyperfunction. MA treatment significantly reduced GluN2B while increasing both PKMζ and PKCζ within the striatum. We discuss the potential role of PKMζ/PKCζ in modulating dopamine and glutamate receptors after MA treatment. These results identify potential underlying mechanisms for working memory deficits induced by MA.

  8. Methamphetamine-induced short-term increase and long-term decrease in spatial working memory affects Protein Kinase M zeta (PKMζ, dopamine, and glutamate receptors

    Directory of Open Access Journals (Sweden)

    Stephen H Braren

    2014-12-01

    Full Text Available Methamphetamine (MA is a toxic, addictive drug shown to modulate learning and memory, yet the neural mechanisms are not fully understood. We investigated the effects of 2 weekly injections of MA (30 mg/kg on working memory using the radial 8-arm maze (RAM across 5 weeks in adolescent-age mice. MA-treated mice show a significant improvement in working memory performance 1 week following the first MA injection compared to saline-injected controls. Following 5 weeks of MA abstinence mice were re-trained on a reference and working memory version of the RAM to assess cognitive flexibility. MA-treated mice show significantly more working memory errors without effects on reference memory performance. The hippocampus and dorsal striatum were assessed for expression of glutamate receptors subunits, GluA2 and GluN2B; dopamine markers, dopamine 1 receptor (D1, dopamine transporter (DAT and tyrosine hydroxylase (TH; and memory markers, protein kinase M zeta (PKMζ and protein kinase C zeta (PKCζ. Within the hippocampus, PKMζ and GluA2 are both significantly reduced after MA supporting the poor memory performance. Additionally, a significant increase in GluN2B and decrease in D1 identifies dysregulated synaptic function. In the striatum, MA treatment increased cytosolic DAT and TH levels associated with dopamine hyperfunction. MA treatment significantly reduced GluN2B while increasing both PKMζ and PKCζ within the striatum. We discuss the potential role of PKMζ/PKCζ in modulating dopamine and glutamate receptors after MA treatment. These results identify potential underlying mechanisms for working memory deficits induced by MA.

  9. On the issue of the {zeta} series convergence and loop corrections in the generation of observable primordial non-Gaussianity in slow-roll inflation: I. The bispectrum

    Energy Technology Data Exchange (ETDEWEB)

    Cogollo, Heiner R S; Rodriguez, Yeinzon; Valenzuela-Toledo, Cesar A, E-mail: heiner.sarmiento@ciencias.uis.edu.co, E-mail: yeinzon.rodriguez@uan.edu.co, E-mail: cavalto@ciencias.uis.edu.co [Escuela de Fisica, Universidad Industrial de Santander, Ciudad Universitaria, Bucaramanga (Colombia)

    2008-08-15

    We show in this paper that it is possible to attain very high, including observable, values for the level of non-Gaussianity f{sub NL} associated with the bispectrum B{sub {zeta}} of the primordial curvature perturbation {zeta}, in a subclass of small-field slow-roll models of inflation with canonical kinetic terms. Such a result is obtained by taking care of loop corrections both in the spectrum P{sub {zeta}} and in the bispectrum B{sub {zeta}}. Sizable values for f{sub NL} arise even if {zeta} is generated during inflation. Five issues are considered when constraining the available parameter space: (1) We must ensure that we are in a perturbative regime so that the {zeta} series expansion, and its truncation, are valid. (2) We must apply the correct condition for the (possible) loop dominance in B{sub {zeta}} and/or P{sub {zeta}}. (3) We must satisfy the spectrum normalization condition. (4) We must satisfy the spectral tilt constraint. (5) We must have enough inflation to solve the horizon problem.

  10. Laboratory investigation on streaming potential for sandy soil and weathered rock; Shitsunai jikken ni yoru sashitsu jiban oyobi fuka ganban no ryudo den`i no kento

    Energy Technology Data Exchange (ETDEWEB)

    Sato, H; Shima, H [OYO Corp., Tokyo (Japan)

    1996-10-01

    Laboratory experiment on sandy soil and weathered rock was conducted to clarify the generation mechanism of streaming potential due to underground fluid. Streaming potential is caused by underground fluid flow, namely by fluid flow in porous substances as electrokinetic phenomenon. In experiment, Inagi sand, Toyoura sand and strongly decomposed weathered granite were used. In Inagi and Toyoura sands, positive streaming potential was observed downstream in fluid flow. Streaming potential could be nearly determined as primary function of fluid velocity, and generated streaming potential increased with fluid resistivity. Streaming potential was higher in Inagi sand than Toyoura sand, probably depending on hydraulic radius, size of bleeding channel, and conductivity of sand surface. In weathered granite, negative streaming potential was measured. In the case of positive {zeta} potential, negative streaming potential is theoretically generated downstream in fluid flow. This experiment suggested possible generation of negative streaming potential in some kinds of ground. 2 refs., 6 figs., 1 tab.

  11. Atoms confined in a penetrable potential: effect of the atom position on the electric and magnetic responses

    Energy Technology Data Exchange (ETDEWEB)

    Acosta Coden, Diego S; Gomez, Sergio S; Romero, Rodolfo H, E-mail: rhromero@exa.unne.edu.ar [Instituto de Modelado e Innovacion Tecnologica, CONICET and Facultad de Ciencias Exactas y Naturales y Agrimensura, Universidad Nacional del Nordeste, Avenida Libertad 5500 (3400) Corrientes (Argentina)

    2011-02-14

    We report results of the calculation of polarizability and the nuclear magnetic shielding tensors of two-electron atoms confined within an attractive Gaussian potential well. The electric and magnetic responses are obtained within the random phase approximation (RPA) of the polarization propagator. The influence of the depth and range of the potential on the electronic structure is also studied. The dependence of the parallel (along the displacement) and perpendicular components of the polarizability and shielding tensors on the distance of the atom to the centre of the well is calculated and rationalized as a dissociation-type process of the artificial diatomic molecule formed between the Coulomb and the well potentials.

  12. Atoms confined in a penetrable potential: effect of the atom position on the electric and magnetic responses

    International Nuclear Information System (INIS)

    Acosta Coden, Diego S; Gomez, Sergio S; Romero, Rodolfo H

    2011-01-01

    We report results of the calculation of polarizability and the nuclear magnetic shielding tensors of two-electron atoms confined within an attractive Gaussian potential well. The electric and magnetic responses are obtained within the random phase approximation (RPA) of the polarization propagator. The influence of the depth and range of the potential on the electronic structure is also studied. The dependence of the parallel (along the displacement) and perpendicular components of the polarizability and shielding tensors on the distance of the atom to the centre of the well is calculated and rationalized as a dissociation-type process of the artificial diatomic molecule formed between the Coulomb and the well potentials.

  13. Nuclear translocation of phospholipase C-zeta, an egg-activating factor, during early embryonic development

    International Nuclear Information System (INIS)

    Sone, Yoshie; Ito, Masahiko; Shirakawa, Hideki; Shikano, Tomohide; Takeuchi, Hiroyuki; Kinoshita, Katsuyuki; Miyazaki, Shunichi

    2005-01-01

    Phospholipase C-zeta (PLCζ), a strong candidate of the egg-activating sperm factor, causes intracellular Ca 2+ oscillations and egg activation, and is subsequently accumulated into the pronucleus (PN), when expressed in mouse eggs by injection of RNA encoding PLCζ. Changes in the localization of expressed PLCζ were investigated by tagging with a fluorescent protein. PLCζ began to translocate into the PN formed at 5-6 h after RNA injection and increased there. Observation in the same embryo revealed that PLCζ in the PN dispersed to the cytoplasm upon nuclear envelope breakdown and translocated again into the nucleus after cleavage. The dynamics was found in the second mitosis as well. When RNA was injected into fertilization-originated 1-cell embryos or blastomere(s) of 2-8-cell embryos, the nuclear localization of expressed PLCζ was recognized in every embryo up to blastocyst. Thus, PLCζ exhibited alternative cytoplasm/nucleus localization during development. This supports the view that the sperm factor could control cell cycle-dependent generation of Ca 2+ oscillations in early embryogenesis

  14. Multiple zeta functions and double wrapping in planar N=4 SYM

    Science.gov (United States)

    Leurent, Sébastien; Volin, Dmytro

    2013-10-01

    Using the FiNLIE solution of the AdS/CFT Y-system, we compute the anomalous dimension of the Konishi operator in planar N=4 SYM up to eight loops, i.e. up to the leading double wrapping order. At this order a non-reducible Euler-Zagier sum, ζ1,2,8, appears for the first time. We find that at all orders in perturbation, every spectral-dependent quantity of the Y-system is expressed through multiple Hurwitz zeta functions, hence we provide a Mathematica package to manipulate these functions, including the particular case of Euler-Zagier sums. Furthermore, we conjecture that only Euler-Zagier sums can appear in the answer for the anomalous dimension at any order in perturbation theory. We also resum the leading transcendentality terms of the anomalous dimension at all orders, obtaining a simple result in terms of Bessel functions. Finally, we demonstrate that exact Bethe equations should be related to an absence of poles condition that becomes especially non-trivial at double wrapping.

  15. Perancangan Zeta Converter yang dilengkapi Power Factor Correction pada Aplikasi Pengaturan Kecepatan Motor Brushless DC

    Directory of Open Access Journals (Sweden)

    Adhika Prajna Nandiwardhana

    2017-01-01

    Full Text Available Penggunaan motor brushless DC telah banyak digunakan dalam berbagai bidang seperti peralatan rumah tangga maupun industri dikarenakan motor ini memiliki struktur yang sederhana, efisiensi dan torsi yang tinggi, serta menggunakan konsep komutasi elektris yang berbeda dari motor DC lainnya. Namun pengoperasian pada umumnya yang menggunakan sumber AC, penyearah serta inverter membuat tingginya nilai harmonisa arus (THD sebesar 73,33% dan power factor sebesar 0,803 dimana nilai ini kurang baik dalam pengaplikasiannya. Pada penelitian ini akan dikaji mengenai proses power factor correction yang mereduksi harmonisa arus (THD sumber AC dengan menggunakan zeta converter dalam pengaplikasian motor brushless DC, serta pengoperasian motor dengan mengamati respon motor terhadap kecepatan referensi yang berubah-ubah dan mengamati kestabilan motor terhadap pembebanan yang bervariasi. Dalam menerapkan metode yang dilakukan pada penelitian ini, pengoperasian motor brushless DC yang telah dirancang dapat bekerja dengan baik meliputi respon motor yang dapat mengikuti kecepatan referensi yang berubah-ubah, serta kestabilan motor dalam mempertahankan kecepatannya pada pembebanan yang bervariasi. Proses power factor correction dapat meningkatkan kualitas daya pada berbagai kecepatan dan mode penerapan yang berbeda-beda, dimana peningkatan tersebut membuktikan kinerja yang baik dalam sistem ini dan memiliki nilai kualitas daya yang baik.

  16. Tc Trends and Terrestrial Planet Formation: The Case of Zeta Reticuli

    Science.gov (United States)

    Adibekyan, Vardan; Delgado-Mena, Elisa; Figueira, Pedro; Sousa, Sergio; Santos, Nuno; Faria, Joao; González Hernández, Jonay; Israelian, Garik; Harutyunyan, Gohar; Suárez-Andrés, Lucia; Hakobyan, Artur

    2016-11-01

    During the last decade astronomers have been trying to search for chemical signatures of terrestrial planet formation in the atmospheres of the hosting stars. Several studies suggested that the chemical abundance trend with the condensation temperature, Tc, is a signature of rocky planet formation. In particular, it was suggested that the Sun shows 'peculiar' chemical abundances due to the presence of the terrestrial planets in our solar-system. However, the rocky material accretion or the trap of rocky materials in terrestrial planets is not the only explanation for the chemical 'peculiarity' of the Sun, or other Sun-like stars with planets. In this talk I madea very brief review of this topic, and presented our last results for the particular case of Zeta Reticuli binary system: A very interesting and well-known system (known in science fiction and ufology as the world of Grey Aliens, or Reticulans) where one of the components hosts an exo-Kuiper belt, and the other component is a 'single', 'lonely' star.

  17. Giants of eclipse the ζ [Zeta] Aurigae stars and other binary systems

    CERN Document Server

    Griffin, Elizabeth

    2015-01-01

    The zeta Aurigae stars are the rare but illustrious sub-group of binary stars that undergo the dramatic phenomenon of "chromospheric eclipse". This book provides detailed descriptions of the ten known systems, illustrates them richly with examples of new spectra, and places them in the context of stellar structure and evolution. Comprised of a large cool giant plus a small hot dwarf, these key eclipsing binaries reveal fascinating changes in their spectra very close to total eclipse, when the hot star shines through differing heights of the "chromosphere", or outer atmosphere, of the giant star. The phenomenon provides astrophysics with the means of analyzing the outer atmosphere of a giant star and how that material is shed into space. The physics of these critical events can be explained qualitatively, but it is more challenging to extract hard facts from the observations, and tough to model the chromosphere in any detail. The book offers current thinking on mechanisms for heating a star's chromosphere an...

  18. Disciplinary Style and Child Abuse Potential: Association with Indicators of Positive Functioning in Children with Behavior Problems

    Science.gov (United States)

    Rodriguez, Christina M.; Eden, Ann M.

    2008-01-01

    Reduction of ineffective parenting is promoted in parent training components of mental health treatment for children with externalizing behavior disorders, but minimal research has considered whether disciplinary style and lower abuse risk could also be associated with positive functioning in such children. The present study examined whether lower…

  19. Localization of s-Wave and Quantum Effective Potential of a Quasi-free Particle with Position-Dependent Mass

    International Nuclear Information System (INIS)

    Ju Guoxing; Xiang Yang; Ren Zhongzhou

    2006-01-01

    The properties of the s-wave for a quasi-free particle with position-dependent mass (PDM) have been discussed in details. Differed from the system with constant mass in which the localization of the s-wave for the free quantum particle around the origin only occurs in two dimensions, the quasi-free particle with PDM can experience attractive forces in D dimensions except D = 1 when its mass function satisfies some conditions. The effective mass of a particle varying with its position can induce effective interaction, which may be attractive in some cases. The analytical expressions of the eigenfunctions and the corresponding probability densities for the s-waves of the two- and three-dimensional systems with a special PDM are given, and the existences of localization around the origin for these systems are shown.

  20. Potential involvement of Notch1 signalling in the pathogenesis of primary cutaneous CD30-positive lymphoproliferative disorders

    DEFF Research Database (Denmark)

    Kamstrup, M.R.; Ralfkiaer, E.; Skovgaard, G.L.

    2008-01-01

    Background The central role of Notch signalling in T-cell development and oncogenesis raises the question of the importance of this pathway in cutaneous T-cell lymphomas. Objectives To investigate the pattern of expression of Notch and its ligands, Jagged and Delta, in skin samples of primary...... obtained from three patients with LyP and two patients with primary cutaneous ALCL. Results We identified single Notch1-positive cells or small clusters of atypical cells in LyP. Similarly, strongly positive Jagged1 cells tended to be localized in clusters. Primary cutaneous ALCL had higher expression...... of Notch1 and Jagged1 compared with LyP. Cells expressing Notch1 and Jagged1 were colocalized and a subset of cells expressed both the receptor and the ligand. The expression of the ligand Delta1 was low to undetectable in both types of lymphoproliferations. A subpopulation of lymphoma cells was found...

  1. Pressure-induced basilar membrane position shifts and the stimulus-evoked potentials in the low-frequency region of the guinea pig cochlea

    NARCIS (Netherlands)

    Fridberger, A; vanMaarseveen, JTPW; Scarfone, E; Ulfendahl, M; Flock, B; Flock, A

    1997-01-01

    We have used the guinea pig isolated temporal bone preparation to investigate changes in the nonlinear properties of the tone-evoked cochlear potentials during reversible step displacements of the basilar membrane towards either the scala tympani or the scala vestibuli. The position shifts were

  2. Positive modulation of glutamatergic receptors potentiates the suppressive effects of antipsychotics on conditioned avoidance responding in rats

    DEFF Research Database (Denmark)

    Olsen, Christina Kurre; Kreilgaard, Mads; Didriksen, Michael

    2006-01-01

    .c.), olanzapine (0.63 mg/kg, s.c.) and clozapine (1.3 mg/kg, s.c.) without causing additional motor disturbances. Thus, the adjunct enhancement of NMDA or AMPA receptor function observed clinically, appears reflected in the present rat CAR study. Consequently, our data lend further support to the potential use...

  3. Can older adults resist the positivity effect in neural responding? The impact of verbal framing on event-related brain potentials elicited by emotional images.

    Science.gov (United States)

    Rehmert, Andrea E; Kisley, Michael A

    2013-10-01

    Older adults have demonstrated an avoidance of negative information, presumably with a goal of greater emotional satisfaction. Understanding whether avoidance of negative information is a voluntary, motivated choice or an involuntary, automatic response will be important to differentiate, as decision making often involves emotional factors. With the use of an emotional framing event-related potential (ERP) paradigm, the present study investigated whether older adults could alter neural responses to negative stimuli through verbal reframing of evaluative response options. The late positive potential (LPP) response of 50 older adults and 50 younger adults was recorded while participants categorized emotional images in one of two framing conditions: positive ("more or less positive") or negative ("more or less negative"). It was hypothesized that older adults would be able to overcome a presumed tendency to down-regulate neural responding to negative stimuli in the negative framing condition, thus leading to larger LPP wave amplitudes to negative images. A similar effect was predicted for younger adults, but for positively valenced images, such that LPP responses would be increased in the positive framing condition compared with the negative framing condition. Overall, younger adults' LPP wave amplitudes were modulated by framing condition, including a reduction in the negativity bias in the positive frame. Older adults' neural responses were not significantly modulated, even though task-related behavior supported the notion that older adults were able to successfully adopt the negative framing condition.

  4. Pharmacological stimuli decreasing nucleus accumbens dopamine can act as positive reinforcers but have a low addictive potential.

    Science.gov (United States)

    Marinelli, M; Barrot, M; Simon, H; Oberlander, C; Dekeyne, A; Le Moal, M; Piazza, P V

    1998-10-01

    Opioid peptides, through mu and delta receptors, play an important part in reward. In contrast, the role of kappa receptors is more controversial. We examined the possible positive reinforcing effects of a selective kappa agonist, RU 51599, by studying intravenous self-administration in the rat. The effect of RU 51599 on dopamine release in the nucleus accumbens was also studied, as opioids and dopamine seem to interact in the mediation of reward. The behavioural and dopaminergic effects of RU 51599 were compared with those of the mu agonist heroin. Rats self-administered both RU 51599 (6.5, 20 and 60 microg/inj) and heroin (30 microg/inj) at low ratio requirement. When the ratio requirement, i.e. the number of responses necessary to receive one drug infusion, was increased, self-administration of RU 51599 rapidly extinguished, whereas self-administration of heroin was maintained. Intravenous infusion of RU 51599 (100, 200 and 400 microg) dose-dependently decreased (25, 30 and 40%, respectively) extracellular concentrations of dopamine, as measured by means of microdialysis in freely moving rats. In contrast, heroin increased accumbens dopamine (130% over baseline). These results indicate that kappa receptors, similarly to mu ones, can mediate positive reinforcing effects of opioid peptides. However, the strength of the reinforcement is very low for kappa receptors. This suggests that changes in accumbens dopamine do not correlate with the capacity of a stimulus to induce reward or aversion. In contrast, a parallel seems to exist between an increase in accumbens dopamine and the drive to reach or obtain a positive reinforcer.

  5. Positive deviance as a novel tool in malaria control and elimination: methodology, qualitative assessment and future potential.

    Science.gov (United States)

    Shafique, Muhammad; Edwards, Hannah M; De Beyl, Celine Zegers; Thavrin, Bou Kheng; Min, Myo; Roca-Feltrer, Arantxa

    2016-02-16

    Positive deviance (PD) is an asset-based, community-driven approach to behaviour change that has successfully been applied to address many health and social problems. It is yet to have been assessed for malaria control but may represent a promising tool for malaria elimination given its suitability in targeting small and remote population groups, apparent sustainability and ability to instil a high amount of community mobilisation. Here, the PD methodology as applied to malaria is explained, with focus upon and qualitative assessment of a proof of concept study in Cambodia. Three villages in Battambang, northwestern Cambodia were selected for the intervention, with an estimated population of 5036 including both residents and migrant workers. In August 2010, field teams conducted a 1 week PD process to sensitise and mobilise the community, establish normative behaviours in relation to malaria control and prevention, identify positive deviant behaviours from within the community, and identify PD volunteers. Until March 2011, PD volunteers were supported by field teams via monthly meetings to conduct activities in their respective communities to increase practice of PD behaviours. In February 2012, 1 year following the end of external support, evaluative interviews were conducted with community members to qualitatively assess community acceptance and interpretation of the PD intervention, perceived behaviour changes, and perceived positive outcomes. Qualitative data from focus group discussions and in-depth interviews showed that the PD approach was well-accepted into the communities and created a strong sense of community empowerment. Positive behaviour change was linked to the PD intervention, including greater usage of nets by forest goers, and use of public health facilities for malaria diagnosis and treatment. One year following the end of external assistance, PD volunteers were still conducting activities in their respective communities. PD offers a promising

  6. How can a place conquer a position in the mind of potential business investors? : A case study on Dubai

    OpenAIRE

    Kindblom, Henrik; Karlsson, David

    2006-01-01

    Abstract In the age of globalization it has become more and more common that places – cities, regions and nations – work actively to attract business investors; all with the aim to support economic development. Nevertheless, the competition is tough and it is hard to get through the information clutter and conquer a position in the mind of the business investors. Dubai, one of the seven Emirates that form the nation United Arab Emirates, was for many years a general unknown place for business...

  7. An unusual class of anthracyclines potentiate Gram-positive antibiotics in intrinsically resistant Gram-negative bacteria.

    Science.gov (United States)

    Cox, Georgina; Koteva, Kalinka; Wright, Gerard D

    2014-07-01

    An orthogonal approach taken towards novel antibacterial drug discovery involves the identification of small molecules that potentiate or enhance the activity of existing antibacterial agents. This study aimed to identify natural-product rifampicin adjuvants in the intrinsically resistant organism Escherichia coli. E. coli BW25113 was screened against 1120 actinomycete fermentation extracts in the presence of subinhibitory (2 mg/L) concentrations of rifampicin. The active molecule exhibiting the greatest rifampicin potentiation was isolated using activity-guided methods and identified using mass and NMR spectroscopy. Susceptibility testing and biochemical assays were used to determine the mechanism of antibiotic potentiation. The anthracycline Antibiotic 301A(1) was isolated from the fermentation broth of a strain of Streptomyces (WAC450); the molecule was shown to be highly synergistic with rifampicin (fractional inhibitory concentration index = 0.156) and moderately synergistic with linezolid (FIC index = 0.25) in both E. coli and Acinetobacter baumannii. Activity was associated with inhibition of efflux and the synergistic phenotype was lost when tested against E. coli harbouring mutations within the rpoB gene. Structure-activity relationship studies revealed that other anthracyclines do not synergize with rifampicin and removal of the sugar moiety of Antibiotic 301A(1) abolishes activity. Screening only a subsection of our natural product library identified a small-molecule antibiotic adjuvant capable of sensitizing Gram-negative bacteria to antibiotics to which they are ordinarily intrinsically resistant. This result demonstrates the great potential of this approach in expanding antibiotic effectiveness in the face of the growing challenge of resistance in Gram-negatives. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  8. An unusual class of anthracyclines potentiate Gram-positive antibiotics in intrinsically resistant Gram-negative bacteria

    Science.gov (United States)

    Cox, Georgina; Koteva, Kalinka; Wright, Gerard D.

    2014-01-01

    Objectives An orthogonal approach taken towards novel antibacterial drug discovery involves the identification of small molecules that potentiate or enhance the activity of existing antibacterial agents. This study aimed to identify natural-product rifampicin adjuvants in the intrinsically resistant organism Escherichia coli. Methods E. coli BW25113 was screened against 1120 actinomycete fermentation extracts in the presence of subinhibitory (2 mg/L) concentrations of rifampicin. The active molecule exhibiting the greatest rifampicin potentiation was isolated using activity-guided methods and identified using mass and NMR spectroscopy. Susceptibility testing and biochemical assays were used to determine the mechanism of antibiotic potentiation. Results The anthracycline Antibiotic 301A1 was isolated from the fermentation broth of a strain of Streptomyces (WAC450); the molecule was shown to be highly synergistic with rifampicin (fractional inhibitory concentration index = 0.156) and moderately synergistic with linezolid (FIC index = 0.25) in both E. coli and Acinetobacter baumannii. Activity was associated with inhibition of efflux and the synergistic phenotype was lost when tested against E. coli harbouring mutations within the rpoB gene. Structure–activity relationship studies revealed that other anthracyclines do not synergize with rifampicin and removal of the sugar moiety of Antibiotic 301A1 abolishes activity. Conclusions Screening only a subsection of our natural product library identified a small-molecule antibiotic adjuvant capable of sensitizing Gram-negative bacteria to antibiotics to which they are ordinarily intrinsically resistant. This result demonstrates the great potential of this approach in expanding antibiotic effectiveness in the face of the growing challenge of resistance in Gram-negatives. PMID:24627312

  9. Epoetin zeta in the management of anemia associated with chronic kidney disease, differential pharmacology and clinical utility

    Directory of Open Access Journals (Sweden)

    Davis-Ajami ML

    2014-04-01

    Full Text Available Mary Lynn Davis-Ajami,1 Jun Wu,2 Katherine Downton,3 Emilie Ludeman,3 Virginia Noxon4 1Organizational Systems and Adult Health, University of Maryland School of Nursing, Baltimore, MD, USA; 2South Carolina College of Pharmacy, University of South Carolina, Greenville, SC, USA; 3Health Sciences and Human Services Library, University of Maryland, Baltimore, MD, USA; 4Department of Clinical Pharmacy and Outcomes Science, South Carolina College of Pharmacy, University of South Carolina, Columbia, SC, USA Abstract: Epoetin zeta was granted marketing authorization in October 2007 by the European Medicines Agency as a recombinant human erythropoietin erythropoiesis-stimulating agent to treat symptomatic anemia of renal origin in adult and pediatric patients on hemodialysis and adults on peritoneal dialysis, as well as for symptomatic renal anemia in adult patients with renal insufficiency not yet on dialysis. Currently, epoetin zeta can be administered either subcutaneously or intravenously to correct for hemoglobin concentrations ≤10 g/dL (6.2 mmol/L or with dose adjustment to maintain hemoglobin levels at desired levels not in excess of 12 g/dL (7.5 mmol/L. This review article focuses on epoetin zeta indications in chronic kidney disease, its use in managing anemia of renal origin, and discusses its pharmacology and clinical utility. Keywords: biosimilar, chronic kidney disease, epoetin alfa, erythropoiesis, renal anemia, Retacrit®

  10. Investigation on Fuzzy Logic Based Centralized Control in Four-Port SEPIC/ZETA Bidirectional Converter for Photovoltaic Applications

    Directory of Open Access Journals (Sweden)

    VENMATHI, M.

    2016-02-01

    Full Text Available In this paper, a new four-port DC-DC converter topology is proposed to interface renewable energy sources and the load along with the energy storage device. The proposed four-port SEPIC/ZETA bidirectional converter (FP-SEPIC/ZETA BDC converter comprises an isolated output port with two unidirectional and one bidirectional input ports. This converter topology is obtained by the fusion of SEPIC/ZETA BDC and full-bridge converter. This converter topology ensures the non-reversal of output voltage hence it is preferred mostly for battery charging applications. In this work, photovoltaic (PV source is considered and the power balance in the system is achieved by means of distributed maximum power point tracking (DMPPT in the PV ports. The centralized controller is implemented using fuzzy logic controller (FLC and the performance is compared with conventional proportional integral (PI controller. The results offer useful information to obtain the desired output under line and load regulations. Experimental results are also provided to validate the simulation results.

  11. The development of fluoroandrogens and fluoroprogestins as potential imaging agents for receptor-positive prostate and breast tumors

    International Nuclear Information System (INIS)

    Brandes, S.J.; Katzenellenbogen, J.A.

    1986-01-01

    The assay of progesterone receptor (PR) concentration in breast tumors and androgen receptor (AR) concentration in prostate tumors enables hormone responsive neoplasms to be distinguished from those that are non-responsive. In principle, a positron-emitting progestin or androgen with suitably high affinity and selectivity for PR and AR, respectively, and an adequately high specific activity might provide a means for imaging receptor-positive tumors and quantifying their receptor content in vivo. The use of fluorine-18 as a radiolabel, coupled with the use of positron emission transaxial tomography, appears to be a most favorable approach in the development of receptor binding radiopharmaceuticals for in vivo imaging. Therefore, we have begun a systematic investigation of the development of fluorine-substituted androgens and progestins that might be prepared in F-18 labeled form as probes for AR and PR. (author)

  12. Trichome density and its UV-B protective potential are affected by shading and leaf position on the canopy

    International Nuclear Information System (INIS)

    Liakoura, V.; Stefanou, M.; Manetas, Y.; Cholevas, C.; Karabourniotis, G.

    1997-01-01

    In Olea europaea trichome density and UV-B absorbing compounds of leaf hairs and the lamina proper of leaves located in south-facing, north-facing and the internal of the canopy were positively correlated to the UV-B midday instant irradiance measured in September at these three different positions of the canopy. The correlation between these three parameters and the receiving photosynthetically active radiation (PAR), however, was weaker. In Quercus ilex, trichome density and its UV-B absorbing capacity were considerably higher in the exposed, south-facing leaves, compared to the deeply shaded ones; the UV-B absorbing capacity of the de-haired lamina, however, was the same. In the broad-leaved, alpine rosette of Verbascum speciosum, one could distinguish two areas on the leaves, one exposed and one shaded by the superimposed lamina. Although trichome density and the UV-B absorbing compounds of the de-haired leaf were the same in the two areas, the UV-B absorbing capacity of hairs was considerably increased in the exposed region. In V. speciosum, exposure induced also qualitative changes in the UV-B absorbance profile, apparently due to the formation of new flavonoid compounds absorbing maximally at 345–350 nm. In all other cases, the differences were mainly quantitative. The results support the postulate of a function of leaf hairs as a UV-B radiation screen and suggest that trichome density and/or its UV-B absorbing capacity may depend on irradiance during leaf development

  13. Can Older Adults Resist the Positivity Effect in Neural Responding: The Impact of Verbal Framing on Event-Related Brain Potentials Elicited by Emotional Images

    Science.gov (United States)

    Rehmert, Andrea E.; Kisley, Michael A.

    2014-01-01

    Older adults have demonstrated an avoidance of negative information presumably with a goal of greater emotional satisfaction. Understanding whether avoidance of negative information is a voluntary, motivated choice, or an involuntary, automatic response will be important to differentiate, as decision-making often involves emotional factors. With the use of an emotional framing event-related potential (ERP) paradigm, the present study investigated whether older adults could alter neural responses to negative stimuli through verbal reframing of evaluative response options. The late-positive potential (LPP) response of 50 older adults and 50 younger adults was recorded while participants categorized emotional images in one of two framing conditions: positive (“more or less positive”) or negative (“more or less negative”). It was hypothesized that older adults would be able to overcome a presumed tendency to down-regulate neural responding to negative stimuli in the negative framing condition thus leading to larger LPP wave amplitudes to negative images. A similar effect was predicted for younger adults but for positively valenced images such that LPP responses would be increased in the positive framing condition compared to the negative framing condition. Overall, younger adults' LPP wave amplitudes were modulated by framing condition, including a reduction in the negativity bias in the positive frame. Older adults' neural responses were not significantly modulated even though task-related behavior supported the notion that older adults were able to successfully adopt the negative framing condition. PMID:23731435

  14. Masking of the CD3 gamma di-leucine-based motif by zeta is required for efficient T-cell receptor expression

    DEFF Research Database (Denmark)

    Lauritsen, Jens Peter H; Bonefeld, Charlotte Menné; von Essen, Marina

    2004-01-01

    containing the di-leucine-based endocytosis motif of the TCR subunit CD3 gamma have indicated that the zeta chain can mask this motif. In this study, we show that successive truncations of the cytoplasmic tail of zeta led to reduced surface expression levels of completely assembled TCR complexes. The reduced...... TCR expression levels were caused by an increase in the TCR endocytic rate constant in combination with an unaffected exocytic rate constant. Furthermore, the TCR degradation rate constant was increased in cells with truncated zeta. Introduction of a CD3 gamma chain with a disrupted di-leucine...

  15. A new approach to triggering mechanism of volcano landslides based on zeta potential and surface free energy balance

    Science.gov (United States)

    Plaza, I.; Ontiveros-Ortega, A.; Calero, J.; Romero, C.

    2018-01-01

    The layers of Almagre (iron-rich deposits) from Tenerife Island are the result of thermal metamorphism of soils in contact with lava flow (1073-1273 K). These layers of small thickness relative to the basaltic wash, are interesting for geotechnical study, because the stability of the deposits is determined by the weakest element, in this case Almagre, which acts as a sliding plane. The flow of maritime air over the hillsides of the volcanic islands increases the content of cations in ashes deposits. This modifies the superficial properties of material that composes the substratum. This modification affects the retention of water and the cohesion of material making up the deposit. The results show that the presence of sodium and magnesium increased the hydrophobicity of the material, which had a weak water retention capacity and strong cohesion at basic pH. When there is iron in solution, repulsion between the particles is greater than one obtained with other studied electrolytes. Hence, the deposit is less stable, and Almagre under saturated water conditions constitutes an ideal layer for landslides.

  16. IMPLICATIONS OF MICROBIAL ADHESION TO HYDROCARBONS FOR EVALUATING CELL-SURFACE HYDROPHOBICITY .1. ZETA-POTENTIALS OF HYDROCARBON DROPLETS

    NARCIS (Netherlands)

    BUSSCHER, HJ; VANDEBELTGRITTER, B; VANDERMEI, HC

    1995-01-01

    Microbial adhesion to hydrocarbons (MATH) is generally considered to be a measure of the organisms cell surface hydrophobicity. As microbial adhesion is a complicated interplay of long-range van der Waals and electrostatic forces and various short-range interactions, the above statement only holds

  17. Zeta-potential and flotability of the scheelite mineral in different type of waters, Part 2: Flotability

    Directory of Open Access Journals (Sweden)

    Milanović Dragan B.

    2009-01-01

    Full Text Available The aim of this work was to study floatability of the mineral sheelite from mine 'Rudnik', central Serbia. Flotation tests of the mineral in a Hallimond tube cell were carried out in four different types of water, namely: tap water, distilled water, rain water and spring water. All types of water had different hardness and conductivity as well as natural pH values. It was found that the flotability of mineral scheelite depends on the hardness and electro-conductivity of the chosen type of water as well as on Ca2+ content. Also, it was found the floatability of mineral depends on the scheelite particle size fraction used in microflotation experiments. Presented results may be useful for proper selection of type of water, as well of the type of reagents used in flotation processes.

  18. Ion Adsorption Parameters Determined from Zeta Potential and Titration Data for a y-Alumina Nanofiltration Membrane

    NARCIS (Netherlands)

    de Lint, W.B.S.; Benes, Nieck Edwin; Lyklema, Johannes; Bouwmeester, Henricus J.M.; van der Linde, Ab J.; Wessling, Matthias

    2003-01-01

    Theoretical models for the prediction of nanofiltration separation performance as a function of, e.g., pH and electrolyte composition require knowledge on the ion-surface adsorption chemistry. Adsorption parameters have been extracted from electrophoretic mobility measurements on a ceramic y-alumina

  19. Ion adsorption parameters determined from zeta potential and titration data for a gamma-alumina nanofiltration membrane

    NARCIS (Netherlands)

    Samuel de Lint, W.B.; Benes, N.E.; Lyklema, J.; Bouwmeester, H.J.M.; Linde, van der A.J.; Wessling, M.

    2003-01-01

    Theoretical models for the prediction of nanofiltration separation performance as a function of, e.g., pH and electrolyte composition require knowledge on the ion-surface adsorption chemistry. Adsorption parameters have been extracted from electrophoretic mobility measurements on a ceramic -alumina

  20. Modulation of late positive potentials by sexual images in problem users and controls inconsistent with "porn addiction".

    Science.gov (United States)

    Prause, Nicole; Steele, Vaughn R; Staley, Cameron; Sabatinelli, Dean; Hajcak, Greg

    2015-07-01

    "Excessive" viewing of visual sexual stimuli (VSS) is the most commonly reported hypersexual behavior problem and is especially amenable to laboratory study. A pattern of enhanced sexual cue responsiveness is expected in this sample if hypersexuality shares features of other addiction models. Participants (N=122) who either reported or denied problematic VSS use were presented with emotional, including explicit sexual, images while their evoked response potentials were recorded. An interaction of hypersexual problem group and the level of desire for sex with a partner predicted LPP amplitude. Specifically, those reporting problems regulating their VSS use who also reported higher sexual desire had lower LPP in response to VSS. This pattern appears different from substance addiction models. These are the first functional physiological data of persons reporting VSS regulation problems. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Enhanced CO2 uptake at a shallow Arctic Ocean seep field overwhelms the positive warming potential of emitted methane.

    Science.gov (United States)

    Pohlman, John W; Greinert, Jens; Ruppel, Carolyn; Silyakova, Anna; Vielstädte, Lisa; Casso, Michael; Mienert, Jürgen; Bünz, Stefan

    2017-05-23

    Continued warming of the Arctic Ocean in coming decades is projected to trigger the release of teragrams (1 Tg = 10 6 tons) of methane from thawing subsea permafrost on shallow continental shelves and dissociation of methane hydrate on upper continental slopes. On the shallow shelves (shallow ebullitive methane seep field on the Svalbard margin reveal atmospheric CO 2 uptake rates (-33,300 ± 7,900 μmol m -2 ⋅d -1 ) twice that of surrounding waters and ∼1,900 times greater than the diffusive sea-air methane efflux (17.3 ± 4.8 μmol m -2 ⋅d -1 ). The negative radiative forcing expected from this CO 2 uptake is up to 231 times greater than the positive radiative forcing from the methane emissions. Surface water characteristics (e.g., high dissolved oxygen, high pH, and enrichment of 13 C in CO 2 ) indicate that upwelling of cold, nutrient-rich water from near the seafloor accompanies methane emissions and stimulates CO 2 consumption by photosynthesizing phytoplankton. These findings challenge the widely held perception that areas characterized by shallow-water methane seeps and/or strongly elevated sea-air methane flux always increase the global atmospheric greenhouse gas burden.

  2. 14-3-3 zeta is a molecular target in guggulsterone induced apoptosis in Head and Neck cancer cells

    International Nuclear Information System (INIS)

    Macha, Muzafar A; Matta, Ajay; Chauhan, SS; Siu, KW Michael; Ralhan, Ranju

    2010-01-01

    The five-year survival rates for head and neck squamous cell carcinoma (HNSCC) patients are less than 50%, and the prognosis has not improved, despite advancements in standard multi-modality therapies. Hence major emphasis is being laid on identification of novel molecular targets and development of multi-targeted therapies. 14-3-3 zeta, a multifunctional phospho-serine/phospho-threonine binding protein, is emerging as an effector of pro-survival signaling by binding to several proteins involved in apoptosis (Bad, FKHRL1 and ASK1) and may serve as an appropriate target for head and neck cancer therapy. Herein, we determined effect of guggulsterone (GS), a farnesoid X receptor antagonist, on 14-3-3 zeta associated molecular pathways for abrogation of apoptosis in head and neck cancer cells. Head and neck cancer cells were treated with guggulsterone (GS). Effect of GS-treatment was evaluated using cell viability (MTT) assay and apoptosis was verified by annexin V, DNA fragmentation and M30 CytoDeath antibody assay. Mechanism of GS-induced apoptosis was determined by western blotting and co-IP assays using specific antibodies. Using in vitro models of head and neck cancer, we showed 14-3-3 zeta as a key player regulating apoptosis in GS treated SCC4 cells. Treatment with GS releases BAD from the inhibitory action of 14-3-3 zeta in proliferating HNSCC cells by activating protein phosphatase 2A (PP2A). These events initiate the intrinsic mitochondrial pathway of apoptosis, as revealed by increased levels of cytochrome c in cytoplasmic extracts of GS-treated SCC4 cells. In addition, GS treatment significantly reduced the expression of anti-apoptotic proteins, Bcl-2, xIAP, Mcl1, survivin, cyclin D1 and c-myc, thus committing cells to apoptosis. These events were followed by activation of caspase 9, caspase 8 and caspase 3 leading to cleavage of its downstream target, poly-ADP-ribose phosphate (PARP). GS targets 14-3-3 zeta associated cellular pathways for reducing

  3. ApoA-I/A-II-HDL positively associates with apoB-lipoproteins as a potential atherogenic indicator.

    Science.gov (United States)

    Kido, Toshimi; Kondo, Kazuo; Kurata, Hideaki; Fujiwara, Yoko; Urata, Takeyoshi; Itakura, Hiroshige; Yokoyama, Shinji

    2017-11-29

    We recently reported distinct nature of high-density lipoproteins (HDL) subgroup particles with apolipoprotein (apo) A-I but not apoA-II (LpAI) and HDL having both (LpAI:AII) based on the data from 314 Japanese. While plasma HDL level almost exclusively depends on concentration of LpAI having 3 to 4 apoA-I molecules, LpAI:AII appeared with almost constant concentration regardless of plasma HDL levels having stable structure with two apoA-I and one disulfide-dimeric apoA-II molecules (Sci. Rep. 6; 31,532, 2016). The aim of this study is further characterization of LpAI:AII with respect to its role in atherogenesis. Association of LpAI, LpAI:AII and other HDL parameters with apoB-lipoprotein parameters was analyzed among the cohort data above. ApoA-I in LpAI negatively correlated with the apoB-lipoprotein parameters such as apoB, triglyceride, nonHDL-cholesterol, and nonHDL-cholesterol + triglyceride, which are apparently reflected in the relations of the total HDL parameters to apoB-lipoproteins. In contrast, apoA-I in LpAI:AII and apoA-II positively correlated to the apoB-lipoprotein parameters even within their small range of variation. These relationships are independent of sex, but may slightly be influenced by the activity-related CETP mutations. The study suggested that LpAI:AII is an atherogenic indicator rather than antiatherogenic. These sub-fractions of HDL are to be evaluated separately for estimating atherogenic risk of the patients.

  4. Clinical Trials Using Anti-CD19/CD28/CD3zeta CAR Gammaretroviral Vector-transduced Autologous T Lymphocytes KTE-C19

    Science.gov (United States)

    NCI supports clinical trials that test new and more effective ways to treat cancer. Find clinical trials studying anti-cd19/cd28/cd3zeta car gammaretroviral vector-transduced autologous t lymphocytes kte-c19.

  5. The Potential and Challenges of Digital Well-Being Interventions: Positive Technology Research and Design in Light of the Bitter-Sweet Ambivalence of Change.

    Science.gov (United States)

    Diefenbach, Sarah

    2018-01-01

    Along with the dissemination of technical assistance in nearly every part of life, there has been growing interest in the potential of technology to support well-being and human flourishing. "Positive technology" thereby takes the responsible role of a "digital coach," supporting people in achieving personal goals and behavior change. The design of such technology requires knowledge of different disciplines such as psychology, design and human-computer interaction. However, possible synergies are not yet used to full effect, and it needs common frameworks to support a more deliberate design of the "therapeutic interaction" mediated through technology. For positive technology design, positive psychology, and resource oriented approaches appear as particularly promising starting point. Besides a general fit of the basic theoretical conceptions of human change, many elements of established interventions could possibly be transferred to technology design. However, besides the power of focusing on the positive, another psychological aspect to consider are the bitter components inherent to change, such as the confrontation with a negative status quo, threat of self-esteem, and the effort required. The present research discusses the general potential and challenges within positive technology design from an interdisciplinary perspective with theoretical and practical contributions. Based on the bitter-sweet ambivalence of change as present in many psychological approaches of motivation and behavior change, the bitter-sweet continuum serves as a proxy for the mixed emotions and cognitions related to change. An empirical investigation of those factors among 177 users of self-improvement technologies provides initial support for the usefulness of the bitter-sweet perspective in understanding change dynamics. In a next step, the bitter-sweet concept is transformed into different design strategies to support positive change. The present article aims to deepen the discussion

  6. The Potential and Challenges of Digital Well-Being Interventions: Positive Technology Research and Design in Light of the Bitter-Sweet Ambivalence of Change

    Directory of Open Access Journals (Sweden)

    Sarah Diefenbach

    2018-03-01

    Full Text Available Along with the dissemination of technical assistance in nearly every part of life, there has been growing interest in the potential of technology to support well-being and human flourishing. “Positive technology” thereby takes the responsible role of a “digital coach,” supporting people in achieving personal goals and behavior change. The design of such technology requires knowledge of different disciplines such as psychology, design and human-computer interaction. However, possible synergies are not yet used to full effect, and it needs common frameworks to support a more deliberate design of the “therapeutic interaction” mediated through technology. For positive technology design, positive psychology, and resource oriented approaches appear as particularly promising starting point. Besides a general fit of the basic theoretical conceptions of human change, many elements of established interventions could possibly be transferred to technology design. However, besides the power of focusing on the positive, another psychological aspect to consider are the bitter components inherent to change, such as the confrontation with a negative status quo, threat of self-esteem, and the effort required. The present research discusses the general potential and challenges within positive technology design from an interdisciplinary perspective with theoretical and practical contributions. Based on the bitter-sweet ambivalence of change as present in many psychological approaches of motivation and behavior change, the bitter-sweet continuum serves as a proxy for the mixed emotions and cognitions related to change. An empirical investigation of those factors among 177 users of self-improvement technologies provides initial support for the usefulness of the bitter-sweet perspective in understanding change dynamics. In a next step, the bitter-sweet concept is transformed into different design strategies to support positive change. The present article

  7. The Potential and Challenges of Digital Well-Being Interventions: Positive Technology Research and Design in Light of the Bitter-Sweet Ambivalence of Change

    Science.gov (United States)

    Diefenbach, Sarah

    2018-01-01

    Along with the dissemination of technical assistance in nearly every part of life, there has been growing interest in the potential of technology to support well-being and human flourishing. “Positive technology” thereby takes the responsible role of a “digital coach,” supporting people in achieving personal goals and behavior change. The design of such technology requires knowledge of different disciplines such as psychology, design and human-computer interaction. However, possible synergies are not yet used to full effect, and it needs common frameworks to support a more deliberate design of the “therapeutic interaction” mediated through technology. For positive technology design, positive psychology, and resource oriented approaches appear as particularly promising starting point. Besides a general fit of the basic theoretical conceptions of human change, many elements of established interventions could possibly be transferred to technology design. However, besides the power of focusing on the positive, another psychological aspect to consider are the bitter components inherent to change, such as the confrontation with a negative status quo, threat of self-esteem, and the effort required. The present research discusses the general potential and challenges within positive technology design from an interdisciplinary perspective with theoretical and practical contributions. Based on the bitter-sweet ambivalence of change as present in many psychological approaches of motivation and behavior change, the bitter-sweet continuum serves as a proxy for the mixed emotions and cognitions related to change. An empirical investigation of those factors among 177 users of self-improvement technologies provides initial support for the usefulness of the bitter-sweet perspective in understanding change dynamics. In a next step, the bitter-sweet concept is transformed into different design strategies to support positive change. The present article aims to deepen the

  8. In vitro phosphorylation of insulin receptor substrate 1 by protein kinase C-zeta: functional analysis and identification of novel phosphorylation sites.

    Science.gov (United States)

    Sommerfeld, Mark R; Metzger, Sabine; Stosik, Magdalene; Tennagels, Norbert; Eckel, Jürgen

    2004-05-18

    Protein kinase C-zeta (PKC-zeta) participates both in downstream insulin signaling and in the negative feedback control of insulin action. Here we used an in vitro approach to identify PKC-zeta phosphorylation sites within insulin receptor substrate 1 (IRS-1) and to characterize the functional implications. A recombinant IRS-1 fragment (rIRS-1(449)(-)(664)) containing major tyrosine motifs for interaction with phosphatidylinositol (PI) 3-kinase strongly associated to the p85alpha subunit of PI 3-kinase after Tyr phosphorylation by the insulin receptor. Phosphorylation of rIRS-1(449)(-)(664) by PKC-zeta induced a prominent inhibition of this process with a mixture of classical PKC isoforms being less effective. Both PKC-zeta and the classical isoforms phosphorylated rIRS-1(449)(-)(664) on Ser(612). However, modification of this residue did not reduce the affinity of p85alpha binding to pTyr-containing peptides (amino acids 605-615 of rat IRS-1), as determined by surface plasmon resonance. rIRS-1(449)(-)(664) was then phosphorylated by PKC-zeta using [(32)P]ATP and subjected to tryptic phosphopeptide mapping based on two-dimensional HPLC coupled to mass spectrometry. Ser(498) and Ser(570) were identified as novel phosphoserine sites targeted by PKC-zeta. Both sites were additionally confirmed by phosphopeptide mapping of the corresponding Ser --> Ala mutants of rIRS-1(449)(-)(664). Ser(570) was specifically targeted by PKC-zeta, as shown by immunoblotting with a phosphospecific antiserum against Ser(570) of IRS-1. Binding of p85alpha to the S570A mutant was less susceptible to inhibition by PKC-zeta, when compared to the S612A mutant. In conclusion, our in vitro data demonstrate a strong inhibitory action of PKC-zeta at the level of IRS-1/PI 3-kinase interaction involving multiple serine phosphorylation sites. Whereas Ser(612) appears not to participate in the negative control of insulin signaling, Ser(570) may at least partly contribute to this process.

  9. A position-dependent mass model for the Thomas–Fermi potential: Exact solvability and relation to δ-doped semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Schulze-Halberg, Axel, E-mail: xbataxel@gmail.com [Department of Mathematics and Actuarial Science, Indiana University Northwest, 3400 Broadway, Gary IN 46408 (United States); García-Ravelo, Jesús; Pacheco-García, Christian [Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Unidad Profesional Adolfo López Mateos, Zacatenco, 07738 México D.F. (Mexico); Juan Peña Gil, José [Universidad Autónoma Metropolitana - Azcapotzalco, CBI - Area de Física Atómica Molecular Aplicada, Av. San Pablo 180, Reynosa Azcapotzalco, 02200 México D.F. (Mexico)

    2013-06-15

    We consider the Schrödinger equation in the Thomas–Fermi field, a model that has been used for describing electron systems in δ-doped semiconductors. It is shown that the problem becomes exactly-solvable if a particular effective (position-dependent) mass distribution is incorporated. Orthogonal sets of normalizable bound state solutions are constructed in explicit form, and the associated energies are determined. We compare our results with the corresponding findings on the constant-mass problem discussed by Ioriatti (1990) [13]. -- Highlights: ► We introduce an exactly solvable, position-dependent mass model for the Thomas–Fermi potential. ► Orthogonal sets of solutions to our model are constructed in closed form. ► Relation to delta-doped semiconductors is discussed. ► Explicit subband bottom energies are calculated and compared to results obtained in a previous study.

  10. A position-dependent mass model for the Thomas–Fermi potential: Exact solvability and relation to δ-doped semiconductors

    International Nuclear Information System (INIS)

    Schulze-Halberg, Axel; García-Ravelo, Jesús; Pacheco-García, Christian; Juan Peña Gil, José

    2013-01-01

    We consider the Schrödinger equation in the Thomas–Fermi field, a model that has been used for describing electron systems in δ-doped semiconductors. It is shown that the problem becomes exactly-solvable if a particular effective (position-dependent) mass distribution is incorporated. Orthogonal sets of normalizable bound state solutions are constructed in explicit form, and the associated energies are determined. We compare our results with the corresponding findings on the constant-mass problem discussed by Ioriatti (1990) [13]. -- Highlights: ► We introduce an exactly solvable, position-dependent mass model for the Thomas–Fermi potential. ► Orthogonal sets of solutions to our model are constructed in closed form. ► Relation to delta-doped semiconductors is discussed. ► Explicit subband bottom energies are calculated and compared to results obtained in a previous study

  11. Consistent gaussian basis sets of double- and triple-zeta valence with polarization quality of the fifth period for solid-state calculations.

    Science.gov (United States)

    Laun, Joachim; Vilela Oliveira, Daniel; Bredow, Thomas

    2018-02-22

    Consistent basis sets of double- and triple-zeta valence with polarization quality for the fifth period have been derived for periodic quantum-chemical solid-state calculations with the crystalline-orbital program CRYSTAL. They are an extension of the pob-TZVP basis sets, and are based on the full-relativistic effective core potentials (ECPs) of the Stuttgart/Cologne group and on the def2-SVP and def2-TZVP valence basis of the Ahlrichs group. We optimized orbital exponents and contraction coefficients to supply robust and stable self-consistent field (SCF) convergence for a wide range of different compounds. The computed crystal structures are compared to those obtained with standard basis sets available from the CRYSTAL basis set database. For the applied hybrid density functional PW1PW, the average deviations of calculated lattice constants from experimental references are smaller with pob-DZVP and pob-TZVP than with standard basis sets. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

  12. Casimir energies in M4≥/sup N/ for even N. Green's-function and zeta-function techniques

    International Nuclear Information System (INIS)

    Kantowski, R.; Milton, K.A.

    1987-01-01

    The Green's-function technique developed in the first paper in this series is generalized to apply to massive scalar, vector, second-order tensor, and Dirac spinor fields, as a preliminary to a full graviton calculation. The Casimir energies are of the form u/sub Casimir/ = (1/a 4 )[α/sub N/lna/b)+β/sub N/], where N (even) is the dimension of the internal sphere, a is its radius, and b/sup -1/ is an ultraviolet cutoff (presumably at the Planck scale). The coefficient of the divergent logarithm, α/sub N/, is unambiguously obtained for each field considered. The Green's-function technique gives rise to no difficulties in the evaluation of imaginary-mass-mode contributions to the Casimir energy. In addition, a new, simplified zeta-function technique is presented which is very easily implemented by symbolic programs, and which, of course, gives the same results. An error in a previous zeta-function calculation of the Casimir energy for even N is pointed out

  13. Beta-and gamma-turns in proteins revisited: a new set of amino acid turn-type dependent positional preferences and potentials.

    Science.gov (United States)

    Guruprasad, K; Rajkumar, S

    2000-06-01

    The number of beta-turns in a representative set of 426 protein three-dimensional crystal structures selected from the recent Protein Data Bank has nearly doubled and the number of gamma-turns in a representative set of 320 proteins has increased over seven times since the previous analysis. Beta-turns (7153) and gamma-turns (911) extracted from these proteins were used to derive a revised set of type-dependent amino acid positional preferences and potentials. Compared with previous results, the preference for proline, methionine and tryptophan has increased and the preference for glutamine, valine, glutamic acid and alanine has decreased for beta-turns. Certain new amino acid preferences were observed for both turn types and individual amino acids showed turn-type dependent positional preferences. The rationale for new amino acid preferences are discussed in the light of hydrogen bonds and other interactions involving the turns. Where main-chain hydrogen bonds of the type NH(i + 3) --> CO(i) were not observed for some beta-turns, other main-chain hydrogen bonds or solvent interactions were observed that possibly stabilize such beta-turns. A number of unexpected isolated beta-turns with proline at i + 2 position were also observed. The NH(i + 2) --> CO(i) hydrogen bond was observed for almost all gamma-turns. Nearly 20% classic gamma-turns and 43% inverse gamma-turns are isolated turns.

  14. Influence of basis-set size on the X Σ 1 /2 +2 , A Π 1 /2 2 , A Π 3 /2 2 , and B Σ 1 /2 +2 potential-energy curves, A Π 3 /2 2 vibrational energies, and D1 and D2 line shapes of Rb+He

    Science.gov (United States)

    Blank, L. Aaron; Sharma, Amit R.; Weeks, David E.

    2018-03-01

    The X Σ 1 /2 +2 , A Π 1 /2 2 , A Π 3 /2 2 , and B2Σ1/2 + potential-energy curves for Rb+He are computed at the spin-orbit multireference configuration interaction level of theory using a hierarchy of Gaussian basis sets at the double-zeta (DZ), triple-zeta (TZ), and quadruple-zeta (QZ) levels of valence quality. Counterpoise and Davidson-Silver corrections are employed to remove basis-set superposition error and ameliorate size-consistency error. An extrapolation is performed to obtain a final set of potential-energy curves in the complete basis-set (CBS) limit. This yields four sets of systematically improved X Σ 1 /2 +2 , A Π 1 /2 2 , A Π 3 /2 2 , and B2Σ1/2 + potential-energy curves that are used to compute the A Π 3 /2 2 bound vibrational energies, the position of the D2 blue satellite peak, and the D1 and D2 pressure broadening and shifting coefficients, at the DZ, TZ, QZ, and CBS levels. Results are compared with previous calculations and experimental observation.

  15. Fuzzy-PI-based centralised control of semi-isolated FP-SEPIC/ZETA BDC in a PV/battery hybrid system

    Science.gov (United States)

    Mahendran, Venmathi; Ramabadran, Ramaprabha

    2016-11-01

    Multiport converters with centralised controller have been most commonly used in stand-alone photovoltaic (PV)/battery hybrid system to supply the load smoothly without any disturbances. This study presents the performance analysis of four-port SEPIC/ZETA bidirectional converter (FP-SEPIC/ZETA BDC) using various types of centralised control schemes like Fuzzy tuned proportional integral controller (Fuzzy-PI), fuzzy logic controller (FLC) and conventional proportional integral (PI) controller. The proposed FP-SEPIC/ZETA BDC with various control strategy is derived for simultaneous power management of a PV source using distributed maximum power point tracking (DMPPT) algorithm, a rechargeable battery, and a load by means of centralised controller. The steady state and the dynamic response of the FP-SEPIC/ZETA BDC are analysed using three different types of controllers under line and load regulation. The Fuzzy-PI-based control scheme improves the dynamic response of the system when compared with the FLC and the conventional PI controller. The power balance between the ports is achieved by pseudorandom carrier modulation scheme. The response of the FP-SEPIC/ZETA BDC is also validated experimentally using hardware prototype model of 500 W system. The effectiveness of the control strategy is validated using simulation and experimental results.

  16. Positively Charged Nanostructured Lipid Carriers and Their Effect on the Dissolution of Poorly Soluble Drugs

    Directory of Open Access Journals (Sweden)

    Kyeong-Ok Choi

    2016-05-01

    Full Text Available The objective of this study is to develop suitable formulations to improve the dissolution rate of poorly water soluble drugs. We selected lipid-based formulation as a drug carrier and modified the surface using positively charged chitosan derivative (HTCC to increase its water solubility and bioavailability. Chitosan and HTCC-coated lipid particles had higher zeta-potential values than uncoated one over the whole pH ranges and improved encapsulation efficiency. In vitro drug release showed that all NLC formulations showed higher in vitro release efficiency than drug particle at pH 7.4. Furthermore, NLC formulation prepared with chitosan or HTCC represented good sustained release property. The results indicate that chitosan and HTCC can be excellent formulating excipients of lipid-based delivery carrier for improving poorly water soluble drug delivery.

  17. Positively Charged Nanostructured Lipid Carriers and Their Effect on the Dissolution of Poorly Soluble Drugs.

    Science.gov (United States)

    Choi, Kyeong-Ok; Choe, Jaehyeog; Suh, Seokjin; Ko, Sanghoon

    2016-05-20

    The objective of this study is to develop suitable formulations to improve the dissolution rate of poorly water soluble drugs. We selected lipid-based formulation as a drug carrier and modified the surface using positively charged chitosan derivative (HTCC) to increase its water solubility and bioavailability. Chitosan and HTCC-coated lipid particles had higher zeta-potential values than uncoated one over the whole pH ranges and improved encapsulation efficiency. In vitro drug release showed that all NLC formulations showed higher in vitro release efficiency than drug particle at pH 7.4. Furthermore, NLC formulation prepared with chitosan or HTCC represented good sustained release property. The results indicate that chitosan and HTCC can be excellent formulating excipients of lipid-based delivery carrier for improving poorly water soluble drug delivery.

  18. Permeability dependence of streaming potential coefficient in porous media

    NARCIS (Netherlands)

    Thanh, L.D.; Sprik, R.

    2015-01-01

    In theory, the streaming potential coefficient depends not only on the zeta potential but also on the permeability of the rocks that partially determines the surface conductivity of the rocks. However, in practice, it is hard to show the permeability dependence of streaming potential coefficients

  19. Interferon Potentiates Toll-Like Receptor-Induced Prostaglandin D2 Production through Positive Feedback Regulation between Signal Transducer and Activators of Transcription 1 and Reactive Oxygen Species

    Directory of Open Access Journals (Sweden)

    Ji-Yun Kim

    2017-12-01

    Full Text Available Prostaglandin D2 (PGD2 is a potent lipid mediator that controls inflammation, and its dysregulation has been implicated in diverse inflammatory disorders. Despite significant progress made in understanding the role of PGD2 as a key regulator of immune responses, the molecular mechanism underlying PGD2 production remains unclear, particularly upon challenge with different and multiple inflammatory stimuli. Interferons (IFNs potentiate macrophage activation and act in concert with exogenous inflammatory mediators such as toll-like receptor (TLR ligands to amplify inflammatory responses. A recent study found that IFN-γ enhanced lipopolysaccharide-induced PGD2 production, indicating a role of IFNs in PGD2 regulation. Here, we demonstrate that TLR-induced PGD2 production by macrophages was significantly potentiated by signaling common to IFN-β and IFN-γ in a signal transducer and activators of transcription (STAT1-dependent mechanism. Such potentiation by IFNs was also observed for PGE2 production, despite the differential regulation of PGD synthase and PGE synthase isoforms mediating PGD2 and PGE2 production under inflammatory conditions. Mechanistic analysis revealed that the generation of intracellular reactive oxygen species (ROS was remarkably potentiated by IFNs and required for PGD2 production, but was nullified by STAT1 deficiency. Conversely, the regulation of STAT1 level and activity by IFNs was largely dependent on ROS levels. Using a model of zymosan-induced peritonitis, the relevance of this finding in vivo was supported by marked inhibition of PGD2 and ROS produced in peritoneal exudate cells by STAT1 deficiency. Collectively, our findings suggest that IFNs, although not activating on their own, are potent amplifiers of TLR-induced PGD2 production via positive-feedback regulation between STAT1 and ROS.

  20. Effect of adsorption of charged macromolecules on streaming and membrane potential values measured with a microporous polysulfone membrane

    DEFF Research Database (Denmark)

    Benavente, J.; Jonsson, Gunnar Eigil

    1997-01-01

    with a polyanion (dextran sulfate or DS) and a polycation (diethylaminoethyl or DEAE-dextran). From electrokinetic and electrochemical measurements, information about characteristic membrane parameters (transport number and ionic permselectivity) and membrane/solution interactions (zeta potential) can be obtained...

  1. Therapeutic Potential of a Scorpion Venom-Derived Antimicrobial Peptide and Its Homologs Against Antibiotic-Resistant Gram-Positive Bacteria

    Directory of Open Access Journals (Sweden)

    Gaomin Liu

    2018-05-01

    Full Text Available The alarming rise in the prevalence of antibiotic resistance among pathogenic bacteria poses a unique challenge for the development of effective therapeutic agents. Antimicrobial peptides (AMPs have attracted a great deal of attention as a possible solution to the increasing problem of antibiotic-resistant bacteria. Marcin-18 was identified from the scorpion Mesobuthus martensii at both DNA and protein levels. The genomic sequence revealed that the marcin-18 coding gene contains a phase-I intron with a GT-AG splice junction located in the DNA region encoding the N-terminal part of signal peptide. The peptide marcin-18 was also isolated from scorpion venom. A protein sequence homology search revealed that marcin-18 shares extremely high sequence identity to the AMPs meucin-18 and megicin-18. In vitro, chemically synthetic marcin-18 and its homologs (meucin-18 and megicin-18 showed highly potent inhibitory activity against Gram-positive bacteria, including some clinical antibiotic-resistant strains. Importantly, in a mouse acute peritonitis model, these peptides significantly decreased the bacterial load in ascites and rescued nearly all mice heavily infected with clinical methicillin-resistant Staphylococcus aureus from lethal bacteremia. Peptides exerted antimicrobial activity via a bactericidal mechanism and killed bacteria through membrane disruption. Taken together, marcin-18 and its homologs have potential for development as therapeutic agents for treating antibiotic-resistant, Gram-positive bacterial infections.

  2. [The importance of vestibular evoked myogenic potentials for the assessment of the otolith function in the patients presenting with benign paroxysmal positional vertigo].

    Science.gov (United States)

    Kunel'skaya, N L; Baybakova, E V; Guseva, A L; Chugunova, M A; Manaenkova, E A

    The objective of the present study was to evaluate the otolith function in the patients presenting with idiopathic benign paroxysmal positional vertigo (pBPPV) attributable to the occlusion of the posterior semicircular canal (PSCC) of the inner ear with the use of vestibular evoked myogenic potentials (VEMP). Cervical (cVEMP) and ocular VEMP (oVEMP) were measured in 34 patients with idiopathic pBPPV before and 7 days after the treatment by means of reposition maneuvers. The results of the repeated Dix-Hallpike test performed 7 days after the repositioning maneuver were negative in 27 patients and positive in 7 patients. There was no statistically significant difference in the amplitude of cervical VEMP between the healthy and affected ears either before or after the repositioning treatment. The measurement of oVEMP revealed a reduction of the response amplitude on the affected side. The average values of the plnl on the healthy side were 12.84±1.09 and those on the affected side 4.62±0.69 (potolith function.

  3. The Moderating Effect of Self-Reported State and Trait Anxiety on the Late Positive Potential to Emotional Faces in 6–11-Year-Old Children

    Directory of Open Access Journals (Sweden)

    Georgia Chronaki

    2018-02-01

    Full Text Available Introduction: The emergence of anxiety during childhood is accompanied by the development of attentional biases to threat. However, the neural mechanisms underlying these biases are poorly understood. In addition, previous research has not examined whether state and trait anxiety are independently associated with threat-related biases.Methods: We compared ERP waveforms during the processing of emotional faces in a population sample of 58 6–11-year-olds who completed self-reported measures of trait and state anxiety and depression.Results: The results showed that the P1 was larger to angry than neutral faces in the left hemisphere, though early components (P1, N170 were not strongly associated with child anxiety or depression. In contrast, Late Positive Potential (LPP amplitudes to angry (vs. neutral faces were significantly and positively associated with symptoms of anxiety/depression. In addition, the difference between LPPs for angry (vs. neutral faces was independently associated with state and trait anxiety symptoms.Discussion: The results showed that neural responses to facial emotion in children with elevated symptoms of anxiety and depression were most evident at later processing stages characterized as evaluative and effortful. The findings support cognitive models of threat perception in anxiety and indicate that trait elements of anxiety and more transitory fluctuations in anxious affect are important in understanding individual variation in the neural response to threat in late childhood.

  4. Quantitative determination of caffeine and alcohol in energy drinks and the potential to produce positive transdermal alcohol concentrations in human subjects.

    Science.gov (United States)

    Ayala, Jessica; Simons, Kelsie; Kerrigan, Sarah

    2009-01-01

    The purpose of this study was to determine whether non-alcoholic energy drinks could result in positive "alcohol alerts" based on transdermal alcohol concentration (TAC) using a commercially available electrochemical monitoring device. Eleven energy drinks were quantitatively assayed for both ethanol and caffeine. Ethanol concentrations for all of the non-alcoholic energy drinks ranged in concentration from 0.03 to 0.230% (w/v) and caffeine content per 8-oz serving ranged from 65 to 126 mg. A total of 15 human subjects participated in the study. Subjects consumed between 6 and 8 energy drinks over an 8-h period. The SCRAM II monitoring device was used to determine TACs every 30 min before, during, and after the study. None of the subjects produced TAC readings that resulted in positive "alcohol alerts". TAC measurements for all subjects before, during and after the energy drink study period (16 h total) were study consumed a quantity of non-alcoholic energy drink that greatly exceeds what would be considered typical. Based on these results, it appears that energy drink consumption is an unlikely explanation for elevated TACs that might be identified as potential drinking episodes or "alcohol alerts" using this device.

  5. Underlying Mechanisms of Cooperativity, Input Specificity, and Associativity of Long-Term Potentiation Through a Positive Feedback of Local Protein Synthesis

    Directory of Open Access Journals (Sweden)

    Lijie Hao

    2018-05-01

    Full Text Available Long-term potentiation (LTP is a specific form of activity-dependent synaptic plasticity that is a leading mechanism of learning and memory in mammals. The properties of cooperativity, input specificity, and associativity are essential for LTP; however, the underlying mechanisms are unclear. Here, based on experimentally observed phenomena, we introduce a computational model of synaptic plasticity in a pyramidal cell to explore the mechanisms responsible for the cooperativity, input specificity, and associativity of LTP. The model is based on molecular processes involved in synaptic plasticity and integrates gene expression involved in the regulation of neuronal activity. In the model, we introduce a local positive feedback loop of protein synthesis at each synapse, which is essential for bimodal response and synapse specificity. Bifurcation analysis of the local positive feedback loop of brain-derived neurotrophic factor (BDNF signaling illustrates the existence of bistability, which is the basis of LTP induction. The local bifurcation diagram provides guidance for the realization of LTP, and the projection of whole system trajectories onto the two-parameter bifurcation diagram confirms the predictions obtained from bifurcation analysis. Moreover, model analysis shows that pre- and postsynaptic components are required to achieve the three properties of LTP. This study provides insights into the mechanisms underlying the cooperativity, input specificity, and associativity of LTP, and the further construction of neural networks for learning and memory.

  6. Mapping the brain pathways of traumatic memory: inactivation of protein kinase M zeta in different brain regions disrupts traumatic memory processes and attenuates traumatic stress responses in rats.

    Science.gov (United States)

    Cohen, Hagit; Kozlovsky, Nitsan; Matar, Michael A; Kaplan, Zeev; Zohar, Joseph

    2010-04-01

    Protein kinase M zeta (PKMzeta), a constitutively active isoform of protein kinase C, has been implicated in protein synthesis-dependent maintenance of long-term potentiation and memory storage in the brain. Recent studies reported that local application of ZIP, a membrane-permeant PKMzeta inhibitor, into the insular cortex (IC) of behaving rats abolished long-term memory of taste associations. This study assessed the long-term effects of local applications of ZIP microinjected immediately (1 h) or 10 days after predator scent stress exposure, in a controlled prospectively designed animal model for PTSD. Four brain structures known to be involved in memory processes and in anxiety were investigated: lateral ventricle (LV), dorsal hippocampus (DH), basolateral amygdala and IC. The outcome measures included behavior in an elevated plus maze and acoustic startle response 7 days after microinjection, and freezing behavior upon exposure to trauma-related cue 8 days after microinjection. Previously acquired/encoded memories associated with the IC were also assessed. Inactivation of PKMzeta in the LV or DH within 1h of exposure effectively reduced PTSD-like behavioral disruption and trauma cue response 8 days later. Inactivation of PKMzeta 10 days after exposure had equivalent effects only when administered in the IC. The effect was demonstrated to be specific for trauma memories, whereas previously acquired data were unaffected by the procedure. Predator scent related memories are located in different brain areas at different times beginning with an initial hippocampus-dependent consolidation process, and are eventually stored in the IC. These bring the IC to the forefront as a potential region of significance in processes related to traumatic stress-induced disorders. 2010 Elsevier B.V. and ECNP. All rights reserved.

  7. A novel conductivity mechanism of highly disordered carbon systems based on an investigation of graph zeta function

    Science.gov (United States)

    Matsutani, Shigeki; Sato, Iwao

    2017-09-01

    In the previous report (Matsutani and Suzuki, 2000 [21]), by proposing the mechanism under which electric conductivity is caused by the activational hopping conduction with the Wigner surmise of the level statistics, the temperature-dependent of electronic conductivity of a highly disordered carbon system was evaluated including apparent metal-insulator transition. Since the system consists of small pieces of graphite, it was assumed that the reason why the level statistics appears is due to the behavior of the quantum chaos in each granular graphite. In this article, we revise the assumption and show another origin of the Wigner surmise, which is more natural for the carbon system based on a recent investigation of graph zeta function in graph theory. Our method can be applied to the statistical treatment of the electronic properties of the randomized molecular system in general.

  8. Generalized zeta function representation of groups and 2-dimensional topological Yang-Mills theory: The example of GL(2, _q) and PGL(2, _q)

    International Nuclear Information System (INIS)

    Roche, Ph.

    2016-01-01

    We recall the relation between zeta function representation of groups and two-dimensional topological Yang-Mills theory through Mednikh formula. We prove various generalisations of Mednikh formulas and define generalization of zeta function representations of groups. We compute some of these functions in the case of the finite group GL(2, _q) and PGL(2, _q). We recall the table characters of these groups for any q, compute the Frobenius-Schur indicator of their irreducible representations, and give the explicit structure of their fusion rings.

  9. Failure to synthesize the human T-cell CD3-zeta chain and its consequence for the T-cell receptor-CD3 complex expression

    DEFF Research Database (Denmark)

    Geisler, C; Kuhlmann, J; Plesner, T

    1989-01-01

    components, the human T-cell tumour line Jurkat was chemically mutagenized followed by negative selection with F101.01 (a monoclonal antibody against the TcR-CD3 complex), and cloning. Growing clones were analysed for TcR-CD3 expression by immunofluorescence. One clone, J79, was found to express greatly...... diminished levels of TcR-CD3. This clone produced all the TcR-CD3 components except the CD3-zeta, as demonstrated by metabolic labelling and immunoprecipitation followed by one- and two-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. These data indicate that the CD3-zeta determines...

  10. Hydrogen exchange rate of tyrosine hydroxyl groups in proteins as studied by the deuterium isotope effect on C(zeta) chemical shifts.

    Science.gov (United States)

    Takeda, Mitsuhiro; Jee, Jungoo; Ono, Akira Mei; Terauchi, Tsutomu; Kainosho, Masatsune

    2009-12-30

    We describe a new NMR method for monitoring the individual hydrogen exchange rates of the hydroxyl groups of tyrosine (Tyr) residues in proteins. The method utilizes (2S,3R)-[beta(2),epsilon(1,2)-(2)H(3);0,alpha,beta,zeta-(13)C(4);(15)N]-Tyr, zeta-SAIL Tyr, to detect and assign the (13)C(zeta) signals of Tyr rings efficiently, either by indirect (1)H-detection through 7-8 Hz (1)H(delta)-(13)C(zeta) spin couplings or by direct (13)C(zeta) observation. A comparison of the (13)C(zeta) chemical shifts of three Tyr residues of an 18.2 kDa protein, EPPIb, dissolved in H(2)O and D(2)O, revealed that all three (13)C(zeta) signals in D(2)O appeared at approximately 0.13 ppm ( approximately 20 Hz at 150.9 MHz) higher than those in H(2)O. In a H(2)O/D(2)O (1:1) mixture, however, one of the three signals for (13)C(zeta) appeared as a single peak at the averaged chemical shifts, and the other two appeared as double peaks at exactly the same chemical shifts in H(2)O and D(2)O, in 50 mM phosphate buffer (pH 6.6) at 40 degrees C. These three peaks were assigned to Tyr-36, Tyr-120, and Tyr-30, from the lower to higher chemical shifts, respectively. The results indicate that the hydroxyl proton of Tyr-120 exchanges faster than a few milliseconds, whereas those of Tyr-30 and Tyr-36 exchange more slowly. The exchange rate of the Tyr-30 hydroxyl proton, k(ex), under these conditions was determined by (13)C NMR exchange spectroscopy (EXSY) to be 9.2 +/- 1.1 s(-1). The Tyr-36 hydroxyl proton, however, exchanges too slowly to be determined by EXSY. These profound differences among the hydroxyl proton exchange rates are closely related to their relative solvent accessibility and the hydrogen bonds associated with the Tyr hydroxyl groups in proteins.

  11. More on zeta-function regularization of high-temperature expansions

    International Nuclear Information System (INIS)

    Actor, A.

    1987-01-01

    A recent paper using the Riemann ζ-function to regularize the (divergent) coefficients occurring in the high-temperature expansions of one-loop thermodynamic potentials is extended. This method proves to be a powerful tool for converting Dirichlet-type series Σ m a m (x i )/m s into power series in the dimensionless parameters x i . The coefficients occurring in the power series are (proportional to) ζ-functions evaluated away from their poles - this is where the regularization occurs. High-temperature expansions are just one example of this highly-nontrivial rearrangement of Dirichlet series into power series form. We discuss in considerable detail series in which a m (x i ) is a product of trigonometric, algebraic and Bessel function factors. The ζ-function method is carefully explained, and a large number of new formulae are provided. The means to generalize these formulae are also provided. Previous results on thermodynamic potentials are generalized to include a nonzero constant term in the gauge potential (time component) which can be used to probe the electric sector of temperature gauge theories. (author)

  12. Potentially traumatic events have negative and positive effects on loneliness, depending on PTSD-symptom levels: evidence from a population-based prospective comparative study.

    Science.gov (United States)

    van der Velden, Peter G; Pijnappel, Bas; van der Meulen, Erik

    2018-02-01

    Examine to what extent adults affected by recent potentially traumatic events (PTE) with different PTSD-symptom levels are more at risk for post-event loneliness than non-affected adults are in the same study period. We extracted data from the Dutch longitudinal LISS panel to measure pre-event loneliness (2011) and post-event loneliness (2013 and 2014), pre-event mental health problems (2011), PTE and PTSD symptoms (2012). This panel is based on a traditional random sample drawn from the population register by Statistics Netherlands. Results of the multinomial logistic regression analyses showed that affected adults with high levels of PTSD symptoms were more at risk for high levels of post-event loneliness than affected adults with very low PTSD-symptom levels and non-affected adults, while controlling for pre-event loneliness, pre-event mental health problems and demographics. However, affected adults with very low levels of PTSD symptoms compared to non-affected adults were less at risk for medium and high levels of post-event loneliness while controlling for the same variables. Yet, pre-event loneliness appeared to be the strongest independent predictor of loneliness at later stages: more than 80% with high pre-event levels had high post-event levels at both follow-ups. Remarkably, potentially traumatic events have depending on PTSD-symptom levels both negative and positive effects on post-event loneliness in favor of affected adults with very low PTSD symptoms levels. However, post-event levels at later stages are predominantly determined by pre-event loneliness levels.

  13. Target Antigen Density Governs the Efficacy of Anti-CD20-CD28-CD3 zeta Chimeric Antigen Receptor-Modified Effector CD8(+) T Cells

    NARCIS (Netherlands)

    Watanabe, Keisuke; Terakura, Seitaro; Martens, Anton C.; van Meerten, Tom; Uchiyama, Susumu; Imai, Misa; Sakemura, Reona; Goto, Tatsunori; Hanajiri, Ryo; Imahashi, Nobuhiko; Shimada, Kazuyuki; Tomita, Akihiro; Kiyoi, Hitoshi; Nishida, Tetsuya; Naoe, Tomoki; Murata, Makoto

    2015-01-01

    The effectiveness of chimeric Ag receptor (CAR)-transduced T (CAR-T) cells has been attributed to supraphysiological signaling through CARs. Second-and later-generation CARs simultaneously transmit costimulatory signals with CD3 zeta signals upon ligation, but may lead to severe adverse effects

  14. H{sub 2} EXCITATION STRUCTURE ON THE SIGHTLINES TO {delta} SCORPII AND {zeta} OPHIUCI: FIRST RESULTS FROM THE SUB-ORBITAL LOCAL INTERSTELLAR CLOUD EXPERIMENT

    Energy Technology Data Exchange (ETDEWEB)

    France, Kevin; Nell, Nicholas; Kane, Robert; Green, James C. [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Burgh, Eric B. [SOFIA/USRA, NASA Ames Research Center, M/S N232-12, Moffett Field, CA 94035 (United States); Beasley, Matthew, E-mail: kevin.france@colorado.edu [Planetary Resources, Inc., 93 S Jackson St 50680, Seattle, WA 98104-2818 (United States)

    2013-07-20

    We present the first science results from the Sub-orbital Local Interstellar Cloud Experiment (SLICE): moderate resolution 1020-1070 A spectroscopy of four sightlines through the local interstellar medium. High signal-to-noise (S/N) spectra of {eta} Uma, {alpha} Vir, {delta} Sco, and {zeta} Oph were obtained during a 2013 April 21 rocket flight. The SLICE observations constrain the density, molecular photoexcitation rates, and physical conditions present in the interstellar material toward {delta} Sco and {zeta} Oph. Our spectra indicate a factor of two lower total N(H{sub 2}) than previously reported for {delta} Sco, which we attribute to higher S/N and better scattered light control in the new SLICE observations. We find N(H{sub 2}) = 1.5 Multiplication-Sign 10{sup 19} cm{sup -2} on the {delta} Sco sightline, with kinetic and excitation temperatures of 67 and 529 K, respectively, and a cloud density of n{sub H} = 56 cm{sup -3}. Our observations of the bulk of the molecular sightline toward {zeta} Oph are consistent with previous measurements (N(H{sub 2}) Almost-Equal-To 3 Multiplication-Sign 10{sup 20} cm{sup -2} at T{sub 01}(H{sub 2}) = 66 K and T{sub exc} = 350 K). However, we detect significantly more rotationally excited H{sub 2} toward {zeta} Oph than previously observed. We infer a cloud density in the rotationally excited component of n{sub H} Almost-Equal-To 7600 cm{sup -3} and suggest that the increased column densities of excited H{sub 2} are a result of the ongoing interaction between {zeta} Oph and its environment; also manifest as the prominent mid-IR bowshock observed by WISE and the presence of vibrationally excited H{sub 2} molecules observed by the Hubble Space Telescope.

  15. Assessment of potential positive effects of nZVI surface modification and concentration levels on TCE dechlorination in the presence of competing strong oxidants, using an experimental design.

    Science.gov (United States)

    Kaifas, Delphine; Malleret, Laure; Kumar, Naresh; Fétimi, Wafa; Claeys-Bruno, Magalie; Sergent, Michelle; Doumenq, Pierre

    2014-05-15

    Nanoscale zero-valent iron (nZVI) particles are efficient for the remediation of aquifers polluted by trichloroethylene (TCE). But for on-site applications, their reactivity can be affected by the presence of common inorganic co-pollutants, which are equally reduced by nZVI particles. The aim of this study was to assess the potential positive effects of nZVI surface modification and concentration level on TCE removal in the concomitant presence of two strong oxidants, i.e., Cr(VI) and NO3(-). A design of experiments, testing four factors (i.e. nZVI concentration, nZVI surface modification, Cr(VI) concentration and NO3(-) concentration), was used to select the best trials for the identification of the main effects of the factors and of the factors interactions. The effects of these factors were studied by measuring the following responses: TCE removal rates at different times, degradation kinetic rates, and the transformation products formed. As expected, TCE degradation was delayed or inhibited in most of the experiments, due to the presence of inorganics. The negative effects of co-pollutants can be palliated by combining surface modification with a slight increase in nZVI concentration. Encouragingly, complete TCE removal was achieved for some given experimental conditions. Noteworthily, nZVI surface modification was found to promote the efficient degradation of TCE. When degradation occurred, TCE was mainly transformed into innocuous non-chlorinated transformation products, while hazardous chlorinated transformation products accounted for a small percentage of the mass-balance. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Gram-Positive Bacteria with Probiotic Potential for the Apis mellifera L. Honey Bee: The Experience in the Northwest of Argentina.

    Science.gov (United States)

    Audisio, Marcela Carina

    2017-03-01

    Apis mellifera L. is one of the most important natural pollinators of significant crops and flowers around the world. It can be affected by different types of illnesses: american foulbrood, nosemosis, varroasis, viruses, among others. Such infections mainly cause a reduction in honey production and in extreme situations, the death of the colony. Argentina is the world's second largest honey exporter and the third largest honey producer, after China and Turkey. Given both the prominence of the honey bee in nature and the economic importance of apiculture in Argentina and the world, it is crucial to develop efficient and sustainable strategies to control honey bee diseases and to improve bee colony health. Gram-positive bacteria, such as lactic acid bacteria, mainly Lactobacillus, and Bacillus spp. are promising options. In the Northwest of Argentina, several Lactobacillus and Bacillus strains from the honey bee gut and honey were isolated by our research group and characterized by using in vitro tests. Two strains were selected because of their potential probiotic properties: Lactobacillus johnsonii CRL1647 and Bacillus subtilis subsp. subtilis Mori2. Under independent trials with both experimental and commercial hives, it was determined that each strain was able to elicit probiotic effects on bee colonies reared in the northwestern region of Argentina. One result was the increase in egg-laying by the queen which therefore produced an increase in bee number and, consequently, a higher honey yield. Moreover, the beneficial bacteria reduced the incidence of two important bee diseases: nosemosis and varroosis. These results are promising and extend the horizon of probiotic bacteria to the insect world, serving beekeepers worldwide as a natural tool that they can administer as is, or combine with other disease-controlling methods.

  17. The CD3-zeta chimeric antigen receptor overcomes TCR Hypo-responsiveness of human terminal late-stage T cells.

    Directory of Open Access Journals (Sweden)

    Gunter Rappl

    Full Text Available Adoptive therapy of malignant diseases with tumor-specific cytotoxic T cells showed remarkable efficacy in recent trials. Repetitive T cell receptor (TCR engagement of target antigen, however, inevitably ends up in hypo-responsive cells with terminally differentiated KLRG-1(+ CD57(+ CD7(- phenotype limiting their therapeutic efficacy. We here revealed that hypo-responsiveness of CMV-specific late-stage CD8(+ T cells is due to reduced TCR synapse formation compared to younger cells. Membrane anchoring of TCR components contributes to T cell hypo-responsiveness since dislocation of galectin-3 from the synapse by swainsonine restored both TCR synapse formation and T cell response. Transgenic expression of a CD3-zeta signaling chimeric antigen receptor (CAR recovered hypo-responsive T cells to full effector functions indicating that the defect is restricted to TCR membrane components while synapse formation of the transgenic CAR was not blocked. CAR engineered late-stage T cells released cytokines and mediated redirected cytotoxicity as efficiently as younger effector T cells. Our data provide a rationale for TCR independent, CAR mediated activation in the adoptive cell therapy to avoid hypo-responsiveness of late-stage T cells upon repetitive antigen encounter.

  18. Transgenic overexpression of 14-3-3 zeta protects hippocampus against endoplasmic reticulum stress and status epilepticus in vivo.

    Directory of Open Access Journals (Sweden)

    Gary P Brennan

    Full Text Available 14-3-3 proteins are ubiquitous molecular chaperones that are abundantly expressed in the brain where they regulate cell functions including metabolism, the cell cycle and apoptosis. Brain levels of several 14-3-3 isoforms are altered in diseases of the nervous system, including epilepsy. The 14-3-3 zeta (ζ isoform has been linked to endoplasmic reticulum (ER function in neurons, with reduced levels provoking ER stress and increasing vulnerability to excitotoxic injury. Here we report that transgenic overexpression of 14-3-3ζ in mice results in selective changes to the unfolded protein response pathway in the hippocampus, including down-regulation of glucose-regulated proteins 78 and 94, activating transcription factors 4 and 6, and Xbp1 splicing. No differences were found between wild-type mice and transgenic mice for levels of other 14-3-3 isoforms or various other 14-3-3 binding proteins. 14-3-3ζ overexpressing mice were potently protected against cell death caused by intracerebroventricular injection of the ER stressor tunicamycin. 14-3-3ζ overexpressing mice were also potently protected against neuronal death caused by prolonged seizures. These studies demonstrate that increased 14-3-3ζ levels protect against ER stress and seizure-damage despite down-regulation of the unfolded protein response. Delivery of 14-3-3ζ may protect against pathologic changes resulting from prolonged or repeated seizures or where injuries provoke ER stress.

  19. Development of an investigation method for redox condition of rocks by self potential (SP) method

    International Nuclear Information System (INIS)

    Kubota, Kenji; Inohara, Yoshiki; Oyama, Takahiro

    2012-01-01

    One of the major issues in subsurface disposal of low level radioactive wastes is that long term behaviors of sedimentary rocks can be affected by geochemical factors. Redox conditions can affect to corrosion of metal included in artificial barrier or wastes and adsorption characteristics of a nuclide. Therefore, it is necessary to develop a method for evaluating the redox conditions around natural barrier at waste facilities. In general, geochemical properties are acquired by rock samples or water sampling at a borehole. However, there is a possibility not to acquire data we want to evaluate. If geophysical methods are applied, redox conditions can be evaluated widely and briefly. There is a possibility that self potential (SP) and redox conditions have a correlation. So we have conducted self potential method around test caverns where redox front can be observed at the Rokkasho site. The results demonstrated that self potential decreased around redox front. There was a positive correlation between self potential and pH. One of the factors of self potential change is difference of elevation, however, self potential change around redox front was larger than that expected from elevation difference. Zeta potential is one of the important factors for determination of self potential, and it had a correlation with self potential or pH. Therefore, there is a possibility that self potential change occurs by geochemical condition changes around redox front, and redox condition can be detected by self potential method. (author)

  20. Phosphorylated Protein Kinase C (Zeta/Lambda) Expression in Colorectal Adenocarcinoma and Its Correlation with Clinicopathologic Characteristics and Prognosis.

    Science.gov (United States)

    Yeo, Min-Kyung; Kim, Ji Yeon; Seong, In-Ock; Kim, Jin-Man; Kim, Kyung-Hee

    2017-01-01

    Background: Protein kinase C zeta/lambda (PKCζ/λ) is a family of protein kinase enzymes that contributes to cell proliferation and regulation, which are important for cancer development. PKCζ/λ has been shown to be an important regulator of tumorigenesis in intestinal cancer. The phosphorylated form of PKCζ/λ, p-PKCζ/λ, is suggested as an active form of PKCζ/λ. However, p-PKCζ/λ expression and its clinicopathologic implication in colorectal adenocarcinoma (CRAC) are unclear. Methods: Seven whole-tissue sections of malignant polyps containing both non-neoplastic and neoplastic mucosa, 11 adenomas with low-grade dysplasia, and 173 CRACs were examined by immunohistochemistry and western blot assay for p-PKCζ/λ protein expression. The association of p-PKCζ/λ expression with clinicopathologic factors including patient survival was studied. Results: In non-neoplastic epithelia, p-PKCζ/λ showed a weak cytoplasmic immunostaining. Adenomas and CRACs demonstrated up-regulated p-PKCζ/λ detection. Cytoplasmic p-PKCζ/λ expression was higher in CRAC than in adenoma. In CRACs, p-PKCζ/λ expression was inversely correlated with pathologic TNM stage (I-II versus III-IV) and poor differentiation. Statistical correlations between low expression of p-PKCζ/λ with shortened overall survival and disease-free survival were seen (p=0.004 and p=0.034, respectively). Conclusions: P-PKCζ/λ overexpression is implicated in tumorigenesis but down-regulation was a poor prognostic factor in CRAC.

  1. HST-WFC3 Near-Infrared Spectroscopy of Quenched Galaxies at zeta approx 1.5 from the WISP Survey: Stellar Populations Properties

    Science.gov (United States)

    Bedregal, A. G.; Scarlata, C.; Henry, A. L.; Atek, H.; Rafelski, M.; Teplitz, H. I.; Dominguez, A.; Siana, B.; Colbert, J. W.; Malkan, M.; hide

    2013-01-01

    We combine Hubble Space Telescope (HST) G102 and G141 near-IR (NIR) grism spectroscopy with HST/WFC3- UVIS, HST/WFC3-IR, and Spitzer/IRAC [3.6 microns] photometry to assemble a sample of massive (log(Mstar/M solar mass) at approx 11.0) and quenched (specific star formation rate spectroscopy for quenched sources at these redshifts. In contrast to the local universe, zeta approx 1.5 quenched galaxies in the high-mass range have a wide range of stellar population properties. We find that their spectral energy distributions (SEDs) are well fitted with exponentially decreasing star formation histories and short star formation timescales (tau less than or equal to 100 M/yr). Quenched galaxies also show a wide distribution in ages, between 1 and 4 G/yr. In the (u - r)0-versus-mass space quenched galaxies have a large spread in rest-frame color at a given mass. Most quenched galaxies populate the zeta appro. 1.5 red sequence (RS), but an important fraction of them (32%) have substantially bluer colors. Although with a large spread, we find that the quenched galaxies on the RS have older median ages (3.1 G/yr) than the quenched galaxies off the RS (1.5 G/yr). We also show that a rejuvenated SED cannot reproduce the observed stacked spectra of (the bluer) quenched galaxies off the RS. We derive the upper limit on the fraction of massive galaxies on the RS at zeta approx 1.5 to be 2 and the zeta approx 1.5 RS. According to their estimated ages, the time required for quenched galaxies off the RS to join their counterparts on the z approx. 1.5 RS is of the order of approx. 1G/yr.

  2. 'Syncing' Up with the Quinn-Rand-Strogatz Constant: Hurwitz-ZetaFunctions in Non-Linear physics

    Energy Technology Data Exchange (ETDEWEB)

    Durgin, Natalie J.; Garcia, Sofia M.; Flournoy, Tamara; Bailey,David H.

    2007-12-01

    This work extends the analytical and computationalinvestigation of the Quinn-Rand-Strogatz (QRS) constants from non-linearphysics. The QRS constants (c1, c2, ..., cN) are found in a Winfreeoscillator mean-field system used to examine the transition of coupledoscillators as they lose synchronization. The constants are part of anasymptotic expansion of a function related to the oscillatorsynchronization. Previous work used high-precision software packages toevaluate c1 to 42 decimal-digits, which made it possible to recognize andprove that c1 was the root of a certain Hurwitz-zeta function. Thisallowed a value of c2 to beconjectured in terms of c1. Therefore thereis interest in determining the exact values of these constants to highprecision in the hope that general relationships can be establishedbetween the constants and the zeta functions. Here, we compute the valuesof the higher order constants (c3, c4) to more than 42-digit precision byextending an algorithm developed by D.H. Bailey, J.M. Borwein and R.E.Crandall. Several methods for speeding up the computation are exploredand an alternate proof that c1 is the root of a Hurwitz-zeta function isattempted.

  3. Human Papillomavirus DNA Methylation as a Biomarker for Cervical Precancer: Consistency across 12 Genotypes and Potential Impact on Management of HPV-Positive Women.

    Science.gov (United States)

    Clarke, Megan A; Gradissimo, Ana; Schiffman, Mark; Lam, Jessica; Sollecito, Christopher C; Fetterman, Barbara; Lorey, Thomas; Poitras, Nancy; Raine-Bennett, Tina R; Castle, Philip E; Wentzensen, Nicolas; Burk, Robert D

    2018-05-01

    Purpose: Human papillomavirus (HPV) DNA methylation testing is a promising triage option for women testing HPV positive during cervical cancer screening. However, the extent to which methylation indicates precancer for all 12 carcinogenic HPV types has not been evaluated. Experimental Design: In this nested case-control study, we tested up to 30 cases of precancer [cervical intraepithelial neoplasia grade 3 (CIN3)/adenocarcinoma in situ (AIS)] and 30 normal controls for each carcinogenic type (single infections with 16/18/31/33/35/39/45/51/52/56/58/59). Next-generation bisulfite sequencing was performed on CpG sites within the L1 and L2 genes. We calculated differences in methylation, ORs, and AUC. Using a fixed sensitivity of 80%, we evaluated the specificity and the risk of CIN3/AIS for best performing CpG sites, and compared the performance of an explorative multi-type methylation assay with current triage strategies. Results: Methylation was positively associated with CIN3/AIS across all 12 types. AUCs for the top sites ranged from 0.71 (HPV51 and HPV56) to 0.86 (HPV18). A combined 12-type methylation assay had the highest Youden index (0.46), compared with cytology (0.31) and a 5-type methylation assay, including only previously described types (0.26). The 12-type methylation assay had higher sensitivity (80% vs. 76.6%) and lower test positivity compared with cytology (38.5% vs. 48.7%). The risk of CIN3/AIS was highest for methylation positives and lowest for cytology or HPV16/18 positives. Conclusions: HPV DNA methylation is a general phenomenon marking the transition from HPV infection to precancer for all 12 carcinogenic types. Development of a combined multitype methylation assay may serve as a triage test for HPV-positive women. Clin Cancer Res; 24(9); 2194-202. ©2018 AACR . ©2018 American Association for Cancer Research.

  4. Effects of the fullerene (C{sub 60}) potential and position of the atom (A) on spectral characteristics of endohedral atoms A and C{sub 60}

    Energy Technology Data Exchange (ETDEWEB)

    Baltenkov, A S [Arifov Institute of Electronics, 100125 Tashkent (Uzbekistan); Becker, U [Fritz-Haber-Institute der Max-Planck-Gesellschaft, D-14195 Berlin (Germany); Manson, S T [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Msezane, A Z, E-mail: arkbalt@mail.r, E-mail: becker@fhi-berlin.mpg.d, E-mail: manson@phy-astr.gsu.ed, E-mail: amsezane@cau.ed [Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta, GA 30314 (United States)

    2010-06-14

    Within the framework of a model representing the potential of a C{sub 60} cage as a spherical electro-neutral layer U(r) formed by smeared carbon atoms, the effect of the details of the potential on spectral characteristics of atoms localized inside the fullerene shell has been studied. Using examples of encapsulated H and He atoms, it is shown that for potential shell thickness not exceeding 1.3-1.5 au, confinement resonance oscillations in the photoionization cross section weakly depend on the shape of the function U(r). With increasing width of the potential well, the confinement resonances in the energy dependence of the photoionization cross section disappear. In addition, it is demonstrated that displacing the doped atom from the centre of the cavity also diminishes the amplitude of the confinement resonance.

  5. Positive allosteric modulators of the α7 nicotinic acetylcholine receptor potentiate glutamate release in the prefrontal cortex of freely-moving rats

    DEFF Research Database (Denmark)

    Bortz, D M; Upton, B A; Mikkelsen, J D

    2016-01-01

    Positive allosteric modulators (PAMs) of α7 nicotinic acetylcholine receptors (α7nAChRs) exhibit pro-cognitive effects in animal models of schizophrenia and are targets for the discovery of cognition-enhancing drugs. However, little is known about their in vivo mechanism of action because...

  6. Can Older Adults Resist the Positivity Effect in Neural Responding: The Impact of Verbal Framing on Event-Related Brain Potentials Elicited by Emotional Images

    OpenAIRE

    Rehmert, Andrea E.; Kisley, Michael A.

    2013-01-01

    Older adults have demonstrated an avoidance of negative information presumably with a goal of greater emotional satisfaction. Understanding whether avoidance of negative information is a voluntary, motivated choice, or an involuntary, automatic response will be important to differentiate, as decision-making often involves emotional factors. With the use of an emotional framing event-related potential (ERP) paradigm, the present study investigated whether older adults could alter neural respon...

  7. Avian metapneumovirus RT-nested-PCR: a novel false positive reducing inactivated control virus with potential applications to other RNA viruses and real time methods.

    Science.gov (United States)

    Falchieri, Marco; Brown, Paul A; Catelli, Elena; Naylor, Clive J

    2012-12-01

    Using reverse genetics, an avian metapneumovirus (AMPV) was modified for use as a positive control for validating all stages of a popular established RT-nested PCR, used in the detection of the two major AMPV subtypes (A and B). Resultant amplicons were of increased size and clearly distinguishable from those arising from unmodified virus, thus allowing false positive bands, due to control virus contamination of test samples, to be identified readily. Absorption of the control virus onto filter paper and subsequent microwave irradiation removed all infectivity while its function as an efficient RT-nested-PCR template was unaffected. Identical amplicons were produced after storage for one year. The modified virus is likely to have application as an internal standard as well as in real time methods. Additions to AMPV of RNA from other RNA viruses, including hazardous examples such HIV and influenza, are likely to yield similar safe RT-PCR controls. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Cumulative and current exposure to potentially nephrotoxic antiretrovirals and development of chronic kidney disease in HIV-positive individuals with a normal baseline estimated glomerular filtration rate

    DEFF Research Database (Denmark)

    Mocroft, Amanda; Lundgren, Jens D; Ross, Michael

    2016-01-01

    BACKGROUND: Whether or not the association between some antiretrovirals used in HIV infection and chronic kidney disease is cumulative is a controversial topic, especially in patients with initially normal renal function. In this study, we aimed to investigate the association between duration...... of exposure to antiretrovirals and the development of chronic kidney disease in people with initially normal renal function, as measured by estimated glomerular filtration rate (eGFR). METHODS: In this prospective international cohort study, HIV-positive adult participants (aged ≥16 years) from the D......:A:D study (based in Europe, the USA, and Australia) with first eGFR greater than 90 mL/min per 1·73 m(2) were followed from baseline (first eGFR measurement after Jan 1, 2004) until the occurrence of one of the following: chronic kidney disease; last eGFR measurement; Feb 1, 2014; or final visit plus 6...

  9. Switching addictions between HER2 and FGFR2 in HER2-positive breast tumor cells: FGFR2 as a potential target for salvage after lapatinib failure

    International Nuclear Information System (INIS)

    Azuma, Koichi; Tsurutani, Junji; Sakai, Kazuko; Kaneda, Hiroyasu; Fujisaka, Yasuhito; Takeda, Masayuki; Watatani, Masahiro; Arao, Tokuzo; Satoh, Taroh; Okamoto, Isamu; Kurata, Takayasu; Nishio, Kazuto; Nakagawa, Kazuhiko

    2011-01-01

    Highlights: → A lapatinib-resistant breast cancer cell line, UACC812 (UACC812/LR), was found to harbor amplification of the FGFR2 gene. → Inhibition of the molecule by a specific inhibitor of FGFR dramatically induced growth inhibition accompanied by cell death. → Immunohistochemical analysis of patients with HER2-positive breast cancer demonstrated an association between FGFR2 expression and poor outcome for lapatinib-containing chemotherapy. -- Abstract: Agents that target HER2 have improved the prognosis of patients with HER2-amplified breast cancers. However, patients who initially respond to such targeted therapy eventually develop resistance to the treatment. We have established a line of lapatinib-resistant breast cancer cells (UACC812/LR) by chronic exposure of HER2-amplified and lapatinib-sensitive UACC812 cells to the drug. The mechanism by which UACC812/LR acquired resistance to lapatinib was explored using comprehensive gene hybridization. The FGFR2 gene in UACC812/LR was highly amplified, accompanied by overexpression of FGFR2 and reduced expression of HER2, and a cell proliferation assay showed that the IC 50 of PD173074, a small-molecule inhibitor of FGFR tyrosine kinase, was 10,000 times lower in UACC812/LR than in the parent cells. PD173074 decreased the phosphorylation of FGFR2 and substantially induced apoptosis in UACC812/LR, but not in the parent cells. FGFR2 appeared to be a pivotal molecule for the survival of UACC812/LR as they became independent of the HER2 pathway, suggesting that a switch of addiction from the HER2 to the FGFR2 pathway enabled cancer cells to become resistant to HER2-targeted therapy. The present study is the first to implicate FGFR in the development of resistance to lapatinib in cancer, and suggests that FGFR-targeted therapy might become a promising salvage strategy after lapatinib failure in patients with HER2-positive breast cancer.

  10. Switching addictions between HER2 and FGFR2 in HER2-positive breast tumor cells: FGFR2 as a potential target for salvage after lapatinib failure

    Energy Technology Data Exchange (ETDEWEB)

    Azuma, Koichi [Department of Medical Oncology, Kinki University Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511 (Japan); Tsurutani, Junji, E-mail: tsurutani_j@dotd.med.kindai.ac.jp [Department of Medical Oncology, Kinki University Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511 (Japan); Sakai, Kazuko; Kaneda, Hiroyasu [Department of Genome Biology, Kinki University Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511 (Japan); Fujisaka, Yasuhito; Takeda, Masayuki [Department of Medical Oncology, Kinki University Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511 (Japan); Watatani, Masahiro [Department of Surgery, Kinki University Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511 (Japan); Arao, Tokuzo [Department of Genome Biology, Kinki University Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511 (Japan); Satoh, Taroh; Okamoto, Isamu; Kurata, Takayasu [Department of Medical Oncology, Kinki University Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511 (Japan); Nishio, Kazuto [Department of Genome Biology, Kinki University Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511 (Japan); Nakagawa, Kazuhiko [Department of Medical Oncology, Kinki University Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511 (Japan)

    2011-04-01

    Highlights: {yields} A lapatinib-resistant breast cancer cell line, UACC812 (UACC812/LR), was found to harbor amplification of the FGFR2 gene. {yields} Inhibition of the molecule by a specific inhibitor of FGFR dramatically induced growth inhibition accompanied by cell death. {yields} Immunohistochemical analysis of patients with HER2-positive breast cancer demonstrated an association between FGFR2 expression and poor outcome for lapatinib-containing chemotherapy. -- Abstract: Agents that target HER2 have improved the prognosis of patients with HER2-amplified breast cancers. However, patients who initially respond to such targeted therapy eventually develop resistance to the treatment. We have established a line of lapatinib-resistant breast cancer cells (UACC812/LR) by chronic exposure of HER2-amplified and lapatinib-sensitive UACC812 cells to the drug. The mechanism by which UACC812/LR acquired resistance to lapatinib was explored using comprehensive gene hybridization. The FGFR2 gene in UACC812/LR was highly amplified, accompanied by overexpression of FGFR2 and reduced expression of HER2, and a cell proliferation assay showed that the IC{sub 50} of PD173074, a small-molecule inhibitor of FGFR tyrosine kinase, was 10,000 times lower in UACC812/LR than in the parent cells. PD173074 decreased the phosphorylation of FGFR2 and substantially induced apoptosis in UACC812/LR, but not in the parent cells. FGFR2 appeared to be a pivotal molecule for the survival of UACC812/LR as they became independent of the HER2 pathway, suggesting that a switch of addiction from the HER2 to the FGFR2 pathway enabled cancer cells to become resistant to HER2-targeted therapy. The present study is the first to implicate FGFR in the development of resistance to lapatinib in cancer, and suggests that FGFR-targeted therapy might become a promising salvage strategy after lapatinib failure in patients with HER2-positive breast cancer.

  11. Position Information

    Data.gov (United States)

    Social Security Administration — The Position Information Data Asset provides the ability to search for active SSA position descriptions using various search criteria. An individual may search by PD...

  12. Positive Psychology

    Science.gov (United States)

    Peterson, Christopher

    2009-01-01

    Positive psychology is a deliberate correction to the focus of psychology on problems. Positive psychology does not deny the difficulties that people may experience but does suggest that sole attention to disorder leads to an incomplete view of the human condition. Positive psychologists concern themselves with four major topics: (1) positive…

  13. Energy policy in the EU and in Russia. Positions, potential conflicts, approaches for cooperation.; Energiepolitik in der EU und Russland. Interessenlagen, Konfliktpotenziale, Kooperationsansaetze

    Energy Technology Data Exchange (ETDEWEB)

    Liebing, Stefan

    2010-06-01

    The paper under the above mentioned title tries to develop an understanding of the question why energy relations and cooperation between the European Union and Russia in energy matters haven't been very successful over the last decade and why relations are affected by crises frequently. In order to answer these questions meaningfully, several steps need to be made: First, the paper offers a summary of recent policy debate on energy questions on the EU side. It identifies relevant participants in the ''political arena'' and describes their positioning and interaction, based on a multi-level-governance approach. Following a look at history of European energy policy developments, the paper concludes that a complex European policy field has developed recently, although there is no direct responsibility for energy matters with European institutions so far, but that the justification for any law-making in the said areas is deducted from secondary EU level responsibilities such as common market, competition law or environmental matters. However, there is a huge bandwidth of positions between political actors, civil service, parliaments, industry associations, consumers - organizations etc as well as between community and national level organizations. Not only a battle for power and competence between these levels hinders a straight and consistent energy policy across the EU, there is also significantly different focus with different players on where to put effort between conflicting objectives of the ''European Energy Triangle'', demanding (1) secure and reliable, (2) cheap and competitive as well as (3) environmentally friendly energy supplies. Despite all these differences, within the EU, a strong and well-regarded new area of policy debate has developed in the energy sector and a lot has been achieved. Observers frequently demand the EU to ''speak with one voice'' towards third parties, eg gas producing

  14. Proactive management strategies for potential gastrointestinal adverse reactions with ceritinib in patients with advanced ALK-positive non-small-cell lung cancer

    International Nuclear Information System (INIS)

    Schaefer, Eric S; Baik, Christina

    2016-01-01

    Anaplastic lymphoma kinase (ALK) gene fusions occur in 3%–7% of non-small-cell lung cancer (NSCLC) cases. Ceritinib, a once-daily, oral ALK inhibitor, has activity against crizotinib-resistant and crizotinib-naïve NSCLC, including brain metastases. Ceritinib (Zykadia™) was granted accelerated approval by the US Food and Drug Administration in 2014 for treating crizotinib-resistant ALK-positive NSCLC. Adverse events (AEs), particularly gastrointestinal (GI) AEs, are commonly experienced at the recommended dose of 750 mg/d and ∼38% of patients require dose interruption or reduction for GI AEs. This case study details our experience with the use of proactive GI AE management regimens in patients treated with ceritinib (750 mg/d) across two study sites. Proactive Regimens A and B were implemented in patients with metastatic ALK-positive NSCLC treated with ceritinib to manage drug-related GI AEs. Regimen A comprised ondansetron and diphenoxylate/atropine or loperamide, taken 30 minutes prior to ceritinib dose. Regimen B included dicyclomine (taken with the first ceritinib dose), ondansetron (taken 30 minutes prior to ceritinib dose for the first seven doses), and loperamide (taken as needed with the onset of diarrhea). The proactive medications were tapered off depending on patient tolerability to ceritinib. Nine patient cases are presented. Starting Regimens A or B before the first dose of ceritinib, or as soon as GI symptoms were encountered, prevented the need for dose reduction due to GI toxicity in eight of the nine patients. Using these regimens, 78% of patients were able to remain on 750 mg/d fasting. Two patients received 23 months and 16 months of therapy and remain on ceritinib 750 mg/d and 600 mg/d, respectively. Although not currently recommended or implemented in clinical studies, based on the patients evaluated here, upfront or proactive treatment plans that address AEs early on can allow the majority of patients to remain on the approved 750 mg

  15. Ubiquitous positioning

    CERN Document Server

    Mannings, Robin

    2008-01-01

    This groundbreaking resource offers a practical, in-depth understanding of Ubiquitous Positioning - positioning systems that identify the location and position of people, vehicles and objects in time and space in the digitized networked economy. The future and growth of ubiquitous positioning will be fueled by the convergence of many other areas of technology, from mobile telematics, Internet technology, and location systems, to sensing systems, geographic information systems, and the semantic web. This first-of-its-kind volume explores ubiquitous positioning from a convergence perspective, of

  16. Positioning consumption

    DEFF Research Database (Denmark)

    Halkier, Bente; Keller, Margit

    2014-01-01

    positionings emerges based on empirical examples of research in parent–children consumption. Positionings are flexible discursive fixations of the relationship between the performances of the practitioner, other practitioners, media discourse and consumption activities. The basic positioning types...... are the practice maintenance and the practice change position, with different sorts of adapting in between. Media discourse can become a resource for a resistant position against social control or for an appropriating position in favour of space for action. Regardless of the current relation to a particular media......This article analyses the ways in which media discourses become a part of contested consumption activities. We apply a positioning perspective with practice theory to focus on how practitioners relate to media discourse as a symbolic resource in their everyday practices. A typology of performance...

  17. Can a Positive Allosteric Modulation of GABAergic Receptors Improve Motor Symptoms in Patients with Parkinson's Disease? The Potential Role of Zolpidem in the Treatment of Parkinson's Disease

    Science.gov (United States)

    Daniele, Antonio; Panza, Francesco; Greco, Antonio; Logroscino, Giancarlo; Seripa, Davide

    2016-01-01

    At present, patients with advanced Parkinson's disease (PD) are unsatisfactorily controlled by currently used anti-Parkinsonian dopaminergic drugs. Various studies suggest that therapeutic strategies based on nondopaminergic drugs might be helpful in PD. Zolpidem, an imidazopyridine widely used as sleep inducer, shows high affinity only for GABAA receptors containing the α-1 subunit and facilitates GABAergic neurotransmission through a positive allosteric modulation of GABAA receptors. Various observations, although preliminary, consistently suggest that in PD patients zolpidem may induce beneficial (and sometimes remarkable) effects on motor symptoms even after single doses and may also improve dyskinesias. Since a high density of zolpidem binding sites is in the two main output structures of the basal ganglia which are abnormally overactive in PD (internal globus pallidus, GPi, and substantia nigra pars reticulata, SNr), it was hypothesized that in PD patients zolpidem may induce through GABAA receptors an inhibition of GPi and SNr (and, possibly, of the subthalamic nucleus also), resulting in an increased activity of motor cortical areas (such as supplementary motor area), which may give rise to improvement of motor symptoms of PD. Randomized clinical trials are needed in order to assess the efficacy, safety, and tolerability of zolpidem in treating motor symptoms of PD. PMID:27293955

  18. Clarification of sugar beet juice using Cu2+ and Al3+ ions: Method of measurement residual solution turbidity and zeta potential

    OpenAIRE

    Kuljanin, Tatjana; Jevtić-Mučibabić, Rada; Ćurčić, Biljana; Nićetin, Milica; Filipović, Vladimir; Knežević, Violeta

    2013-01-01

    Processing of raw sugar beet juice and molasses are important operations which are used to remove pectin and protein substances in order to obtain the final product - white sugar. Separation of these compounds in our country is mostly done by compounds with calcium ion. Quantities of used limestone are very high (1 – 3 % w/w, calculated on the beet). The aim of study is application of coagulants with divalent and trivalent cations which cause the process of charge neutralization of pectin and...

  19. A new approach to treatment of resistant gram-positive infections: potential impact of targeted IV to oral switch on length of stay

    Directory of Open Access Journals (Sweden)

    Trust Sarah

    2006-06-01

    Full Text Available Abstract Background Patients prescribed intravenous (IV glycopeptides usually remain in hospital until completion of this treatment. Some of these patients could be discharged earlier if a switch to an oral antibiotic was made. This study was designed to identify the percentage of inpatients currently prescribed IV glycopeptides who could be discharged earlier if a switch to an oral agent was used, and to estimate the number of bed days that could be saved. We also aimed to identify the patient group(s most likely to benefit, and to estimate the number of days of IV therapy that could be prevented in patients who remained in hospital. Methods Patients were included if they were prescribed an IV glycopeptide for 5 days or more. Predetermined IV to oral antibiotic switch criteria and discharge criteria were applied. A multiple logistic regression model was used to identify the characteristics of the patients most likely to be suitable for earlier discharge. Results Of 211 patients, 62 (29% could have had a reduced length of stay if they were treated with a suitable oral antibiotic. This would have saved a total of 649 inpatient days (median 5 per patient; range 1–54. A further 31 patients (15% could have switched to oral therapy as an inpatient thus avoiding IV line use. The patients most likely to be suitable for early discharge were those with skin and soft tissue infection, under the cardiology, cardiothoracic surgery, orthopaedics, general medical, plastic surgery and vascular specialities, with no high risk comorbidity and less than five other regularly prescribed drugs. Conclusion The need for glycopeptide therapy has a significant impact on length of stay. Effective targeting of oral antimicrobials could reduce the need for IV access, allow outpatient treatment and thus reduce the length of stay in patients with infections caused by antibiotic resistant gram-positive bacteria.

  20. Combining the ABL1 kinase inhibitor ponatinib and the histone deacetylase inhibitor vorinostat: a potential treatment for BCR-ABL-positive leukemia.

    Science.gov (United States)

    Okabe, Seiichi; Tauchi, Tetsuzo; Kimura, Shinya; Maekawa, Taira; Kitahara, Toshihiko; Tanaka, Yoko; Ohyashiki, Kazuma

    2014-01-01

    Resistance to imatinib (Gleevec®) in cancer cells is frequently because of acquired point mutations in the kinase domain of BCR-ABL. Ponatinib, also known as AP24534, is an oral multi-targeted tyrosine kinase inhibitor (TKI), and it has been investigated in a pivotal phase 2 clinical trial. The histone deacetylase inhibitor vorinostat (suberoylanilide hydroxamic acid) has been evaluated for its significant clinical activity in hematological malignancies. Thus, treatments combining ABL TKIs with additional drugs may be a promising strategy in the treatment of leukemia. In the current study, we analyzed the efficacy of ponatinib and vorinostat treatment by using BCR-ABL-positive cell lines. Treatment with ponatinib for 72 h inhibited cell growth and induced apoptosis in K562 cells in a dose-dependent manner. We found that ponatinib potently inhibited the growth of Ba/F3 cells ectopically expressing BCR-ABL T315I mutation. Upon BCR-ABL phosphorylation, Crk-L was decreased, and poly (ADP-ribose) polymerase (PARP) was activated in a dose-dependent manner. Combined treatment of Ba/F3 T315I mutant cells with vorinostat and ponatinib resulted in significantly increased cytotoxicity. Additionally, the intracellular signaling of ponatinib and vorinostat was examined. Caspase 3 and PARP activation increased after combination treatment with ponatinib and vorinostat. Moreover, an increase in the phosphorylation levels of γH2A.X was observed. Previously established ponatinib-resistant Ba/F3 cells were also resistant to imatinib, nilotinib, and dasatinib. We investigated the difference in the efficacy of ponatinib and vorinostat by using ponatinib-resistant Ba/F3 cells. Combined treatment of ponatinib-resistant cells with ponatinib and vorinostat caused a significant increase in cytotoxicity. Thus, combined administration of ponatinib and vorinostat may be a powerful strategy against BCR-ABL mutant cells and could enhance the cytotoxic effects of ponatinib in those BCR

  1. Bromine-80m-labeled estrogens: Auger-electron emitting, estrogen receptor-directed ligands with potential for therapy of estrogen receptor positive cancers

    International Nuclear Information System (INIS)

    DeSombre, E.R.; Mease, R.C.; Hughes, A.; Harper, P.V.; DeJesus, O.T.; Friedman, A.M.

    1988-01-01

    A triphenylbromoethylene, 1,1-bis(p-hydroxyphenyl)-2-bromo-2-phenylethylene, Br-BHPE, and a bromosteroidal estrogen, 17α- bromovinylestradiol, BrVE 2 , were labeled with the Auger electron emitting nuclide bromine-80m, prepared by the [p,n] reaction with 80 Se. To assess their potential as estrogen receptor (ER) directed therapeutic substrates the bromine-80m labeled estrogens were injected into immature female rats and the tissue distribution studied at 0.5 and 2 hours. Both radiobromoestrogens showed substantial diethylstilbesterol (DES)-inhibitable localization in the ER rich tissues, uterus, pituitary, ovary and vagina at both time points. While the percent dose per gram tissue was higher for the Br-BHPE, the BrVE 2 showed higher tissue to blood ratios, especially at 2 hr, reflecting the lower blood concentrations of radiobromine following administration of the steroidal bromoestrogen. Comparing intraperitoneal, intravenous and subcutaneous routes of administration for the radiobromine labeled Br-BHPE, the intraperitoneal route was particularly advantageous to provide maximum, DES-inhibitable concentrations in the peritoneal, ER-rich target organs, the uterus, ovary and vagina. While uterine concentrations after BrBHPE were from 10--48% dose/g and after BrVE 2 were 15--25% dose/g, similar treatment with /sup 80m/Br as sodium bromide showed uniform low concentrations in all tissues at about the levels seen in blood. The effective specific activity of [/sup 80m/Br]BrBHPE, assayed by specific binding to ER in rat uterine cytosol, was 8700 Ci/mmole. 23 refs., 9 figs., 2 tabs

  2. DNA polymerase zeta cooperates with polymerases kappa and iota in translesion DNA synthesis across pyrimidine photodimers in cells from XPV patients.

    Science.gov (United States)

    Ziv, Omer; Geacintov, Nicholas; Nakajima, Satoshi; Yasui, Akira; Livneh, Zvi

    2009-07-14

    Human cells tolerate UV-induced cyclobutane pyrimidine dimers (CPD) by translesion DNA synthesis (TLS), carried out by DNA polymerase eta, the POLH gene product. A deficiency in DNA polymerase eta due to germ-line mutations in POLH causes the hereditary disease xeroderma pigmentosum variant (XPV), which is characterized by sunlight sensitivity and extreme predisposition to sunlight-induced skin cancer. XPV cells are UV hypermutable due to the activity of mutagenic TLS across CPD, which explains the cancer predisposition of the patients. However, the identity of the backup polymerase that carries out this mutagenic TLS was unclear. Here, we show that DNA polymerase zeta cooperates with DNA polymerases kappa and iota to carry out error-prone TLS across a TT CPD. Moreover, DNA polymerases zeta and kappa, but not iota, protect XPV cells against UV cytotoxicity, independently of nucleotide excision repair. This presents an extreme example of benefit-risk balance in the activity of TLS polymerases, which provide protection against UV cytotoxicity at the cost of increased mutagenic load.

  3. Prince of zeta by Petar Konjović: Opera in five/four acts on the 125th anniversary of the composer's birth

    Directory of Open Access Journals (Sweden)

    Mosusova Nadežda

    2008-01-01

    Full Text Available Petar Konjović (Čurug, May 5, 1883 - Belgrade, October 1, 1970 stands out among Serbian composers as an author of instrumental and vocal compositions. Studies at the Prague Conservatory (1904-1906 acquainted Konjović with Czech music, Wagner's opus, and the Russian national-romantic school, which contributed to the evolution of his talent for both music and stage, enabling him to express his ideas more explicitly in operatic works. It was in the Prague that the second opera - Prince of Zeta - was conceived, with new musical vividness and dramatic appeal (first version composed 1906-1926, the second and final 1929-1939, followed by Koštana (1928, Peasants (1951 and Fatherland (1960. Konjović's mature operas are characterized by his masterful handling of form, both in close-ups and in detail, as well as his deeply individual assimilation of musical folklore into his work. The Prince of Zeta is not to be understood as a folk opera, but some main themes are directly derived from folk music, precisely from the Montenegrin folk songs quoted in the Mokranjac's Ninth Garland and treated in Konjović's post-romantic, almost expressionistic way, interwoven with some Italianate leitmotifs, so as to present the opera's two worlds, Montenegrin and Venetian. In the process of forming Konjović's operatic style, with vocal parts based mainly on the principle of declamation, the opera Prince of Zeta (first performed in Belgrade, 1929, conducted by Lovro von Matačić proved to be a work of great impact. Hardly anyone grasped then the wide sweep of inspiration which allowed the composer to set and to solve several important problems connected with music drama, essential also in his subsequent stage works. First of all, Konjović had to handle in his own way the verbal drama the prototype of his opera, Maxim Crnojević by the Serbian poet Laza Kostić (1841-1910. Permission came from the playwright in the first decade of the 1900, Prince of Zeta being partly

  4. Effect of conductivity variations within the electric double layer on the streaming potential estimation in narrow fluidic confinements.

    Science.gov (United States)

    Das, Siddhartha; Chakraborty, Suman

    2010-07-06

    In this article, we investigate the implications of ionic conductivity variations within the electrical double layer (EDL) on the streaming potential estimation in pressure-driven fluidic transport through narrow confinements. Unlike the traditional considerations, we do not affix the ionic conductivities apriori by employing preset values of dimensionless parameters (such as the Dukhin number) to estimate the streaming potential. Rather, utilizing the Gouy-Chapman-Grahame model for estimating the electric potential and charge density distribution within the Stern layer, we first quantify the Stern layer electrical conductivity as a function of the zeta potential and other pertinent parameters quantifying the interaction of the ionic species with the charged surface. Next, by invoking the Boltzmann model for cationic and anionic distribution within the diffuse layer, we obtain the diffuse layer electrical conductivity. On the basis of these two different conductivities pertaining to the two different portions of the EDL as well as the bulk conductivity, we define two separate Dukhin numbers that turn out to be functions of the dimensionless zeta potential and the channel height to Debye length ratio. We derive analytical expressions for the streaming potential as a function of the fundamental governing parameters, considering the above. The results reveal interesting and significant deviations between the streaming potential predictions from the present considerations against the corresponding predictions from the classical considerations in which electrochemically consistent estimates of variable EDL conductivity are not traditionally accounted for. In particular, it is revealed that the variations of streaming potential with zeta potential are primarily determined by the competing effects of EDL electromigration and ionic advection. Over low and high zeta potential regimes, the Stern layer and diffuse layer conductivities predominantly dictate the streaming

  5. Researcher positioning

    DEFF Research Database (Denmark)

    Mørck, Line Lerche; Khawaja, Iram

    2009-01-01

    abstract  This article focuses on the complex and multi-layered process of researcher positioning, specifically in relation to the politically sensitive study of marginalised and ‘othered' groups such as Muslims living in Denmark. We discuss the impact of different ethnic, religious and racial...... political and personal involvement by the researcher, which challenges traditional perspectives on research and researcher positioning. A key point in this regard is the importance of constant awareness of and reflection on the multiple ways in which one's positioning as a researcher influences the research...

  6. Specific Reaction Patterns to Distinct Positive Emotional Cues Related to Incentive Motivation in Dependence of the Taq1A-Polymorphism: Molecular Genetic Associations of Early and Late Event-Related Potentials.

    Science.gov (United States)

    Munk, Aisha J L; Wielpuetz, Catrin; Osinsky, Roman; Müller, Erik M; Grant, Phillip; Hennig, Jürgen

    2016-01-01

    Early and late event-related potential (ERP) responses, representing early subconscious and late motivational processes, were recorded for positive emotional words related to 'wanting' and 'liking', in dependence of the dopamine-related Taq1A genotype (ANKK1/DRD2). Research suggests that 'wanting' as opposed to 'liking' is related to dopaminergic processes. Therefore, it was hypothesized that risk allele carriers of the Taq1A polymorphism exhibit late ERP changes in reaction to words representing incentive motivation, i.e. 'wanting' (word categories 'lust' and 'anticipation'), but not to words representing 'liking' ('closeness'). Seventy-two male participants performed an emotional-word Stroop task during EEG recording and were genotyped according to the Taq1A polymorphism of ANKK1/DRD2. Positive emotional words related to anticipation and lust revealed blunted responses in the late positive potential (LPP) in carriers of the A1 allele, an effect absent in response to 'liking'-related words. These differences were not evident in the earlier posterior negativity (EPN). As no differences in dependence of the Taq1A genotype were observed in reaction to 'wanting'- and 'liking'-related words in the EPN, but merely in the LPP, it can be assumed that incentive-motivational stimuli only modify motivation-related ERP responses in carriers of the A1 allele of the Taq1A polymorphism, indicating the role of dopamine in late ERP components. © 2016 S. Karger AG, Basel.

  7. Radiographic positioning

    International Nuclear Information System (INIS)

    Eisenberg, R.L.; Dennis, C.A.; May, C.

    1989-01-01

    This book concentrates on the routine radiographic examinations commonly performed. It details the wide variety of examinations possible and their place in initial learning and in the radiology department as references for those occasions when an unusual examination is requested. This book provides information ranging from basic terminology to skeletal positioning to special procedures. Positions are discussed and supplemented with a picture of a patient, the resulting radiograph, and a labeled diagram. Immobilization and proper shielding of the patient are also shown

  8. Position encoder

    International Nuclear Information System (INIS)

    Goursky, Vsevolod

    1975-01-01

    A circuitry for deriving the quotient of signal delivered by position-sensitive detectors is described. Digital output is obtained in the form of 10- to 12-bit words. Impact position may be determined with 0.25% accuracy when the dynamic range of the energy signal is less 1:10, and 0.5% accuracy when the dynamic range is 1:20. The division requires an average time of 5μs for 10-bit words

  9. Position encoder

    International Nuclear Information System (INIS)

    Goursky, V.

    1975-05-01

    This paper describes circuitry for deriving the quotient of signals delivered by position-sensitive detectors. Digital output is obtained in the form of 10 to 12 bit words. Impact position may be determined with 0.25% accuracy when the dynamic range of the energy signal is less than 1:10, and 0.5% accuracy when the dynamic range is 1:20. The division requires an average time of 5μs for 10-bit words [fr

  10. Applications of zeta functions and other spectral functions in mathematics and physics: a special issue in honour of Stuart Dowker's 75th birthday Applications of zeta functions and other spectral functions in mathematics and physics: a special issue in honour of Stuart Dowker's 75th birthday

    Science.gov (United States)

    Dowker, Fay; Elizalde, Emilio; Kirsten, Klaus

    2012-09-01

    John Stuart Dowker was born in Sheffield, Yorkshire, on 18 March 1937. His life, therefore, was very much influenced by the Second World War. This is evident as his father died on active service in 1945, after being called up in 1941. His grandfather also died shortly afterwards, so he did not know either of them very well. Nevertheless, it seems that he picked up a positive attitude towards natural sciences as both were technically minded. His mother later provided, often from borrowed money, all the necessary intellectual food in forms of chemistry sets, slide rules and other things that a boy needed to develop his interests. Stuart scored excellently in the 11-plus exam, which was used to decide the type of school a pupil should attend after primary school. Although Stuart was generally allowed to do what he wanted, his mother insisted that he chose King Edward VII Grammar School (KES), the top school in Sheffield at the time. KES allowed Stuart to fully develop his intellectual abilities, and after the S-level exam he received a prestigious state scholarship which allowed him to study at any university in the country. He picked Nottingham over other possibilities, mainly because of his interest in electronics and because of the relative proximity to his family. In Nottingham, where he stayed from 1955 to 1958, his research concentration turned out to be mostly solid state physics. But with time on his hands, Stuart raided the library and taught himself things like complex analysis and quantum mechanics, with de Broglie's La mécanique ondulatoire [1] as one of his favorites. Remarkably, this book already contains a discussion of quantization on curved configuration spaces, a setting so relevant in Stuart's later career. Stuart wanted to investigate quantum field theory for his doctoral thesis. So he wrote, among others, to Rudolph Peierls in Birmingham, and, after being interviewed by Peierls himself and J G Valatin, he received an offer of a PhD position. He

  11. Moringa oleifera Seed Derivatives as Potential Bio-Coagulant for Microalgae Chlorella sp. Harvesting

    International Nuclear Information System (INIS)

    Azizah Endut; Azizah Endut; Siti Hajar Abdul Hamid; Fathurrahman Lananan; Helena Khatoon

    2016-01-01

    Microalgae is an economical and potential raw material of biomass energy, which offer a wide range of commercial potential to produce valuable substances for applications in aquaculture feed, pharmaceutical purposes and bio fuels production. However, lack of an economical, efficient and convenient method to harvest microalgae is a bottleneck to boost their full-scale application. Hence, this study was performed to investigate the potentialities of Moringa oleifera seed derivatives as an environmentally bio-coagulant to harvest microalgae Chlorella sp. biomass from the water column, which acts as a binder to coagulate particulate impurities to form larger aggregates. Results shown M. oleifera to have better biomass recovery of 122.51 % as compared to 37.08 % of alum at similar dosages of 10 mgL"-"1. In addition, it was found that the zeta potential values of mixed microalgae-coagulant suspension shows positive correlation on the flocculation parameters. For biomass recovery, the correlation for M. oleifera protein powder showed the R"2-value of 0.9565 whereas the control chemical flocculant, alum with the R"2-value of 0.7920. It was evidence that M. oleifera has a great potential in efficient and economical for environmentally microalgae harvesting and the adaptation of biological harvesting technology especially for the purpose of aquaculture feed in Malaysia. (author)

  12. Quantification of elemental segregation to lath and grain boundaries in low-alloy steel by STEM X-ray mapping combined with the zeta-factor method

    CERN Document Server

    Watanabe, M

    2003-01-01

    Elemental segregation to two types of boundaries in a low-alloy steel were studied by X-ray mapping using scanning transmission electron microscopy (STEM). To quantify the acquired X-ray maps, the zeta-factor method was applied, and then the compositional maps and the thickness map were obtained. Based on these quantified maps, further information about the analytical sensitivity of solute-element detection and the spatial resolution of segregation analysis were extracted. Furthermore, maps of the number of excess atoms on the boundary were also calculated from the compositional and thickness maps. It was concluded that Cr, Ni and Mo are co-segregated on the prior-austenite grain boundary and only Ni was segregated on the lath boundary. (orig.)

  13. Positional games

    CERN Document Server

    Hefetz, Dan; Stojaković, Miloš; Szabó, Tibor

    2014-01-01

    This text serves as a thorough introduction to the rapidly developing field of positional games. This area constitutes an important branch of combinatorics, whose aim it is to systematically develop an extensive mathematical basis for a variety of two-player perfect information games. These range from such popular games as Tic-Tac-Toe and Hex to purely abstract games played on graphs and hypergraphs. The subject of positional games is strongly related to several other branches of combinatorics such as Ramsey theory, extremal graph and set theory, and the probabilistic method. These notes cover a variety of topics in positional games, including both classical results and recent important developments. They are presented in an accessible way and are accompanied by exercises of varying difficulty, helping the reader to better understand the theory. The text will benefit both researchers and graduate students in combinatorics and adjacent fields.

  14. Generalized zeta function representation of groups and 2-dimensional topological Yang-Mills theory: The example of GL(2, #Mathematical Double-Struck Capital F#{sub q}) and PGL(2, #Mathematical Double-Struck Capital F#{sub q})

    Energy Technology Data Exchange (ETDEWEB)

    Roche, Ph., E-mail: philippe.roche@univ-montp2.fr [Université Montpellier 2, CNRS, L2C, IMAG, Montpellier (France)

    2016-03-15

    We recall the relation between zeta function representation of groups and two-dimensional topological Yang-Mills theory through Mednikh formula. We prove various generalisations of Mednikh formulas and define generalization of zeta function representations of groups. We compute some of these functions in the case of the finite group GL(2, #Mathematical Double-Struck Capital F#{sub q}) and PGL(2, #Mathematical Double-Struck Capital F#{sub q}). We recall the table characters of these groups for any q, compute the Frobenius-Schur indicator of their irreducible representations, and give the explicit structure of their fusion rings.

  15. Researcher Positioning

    DEFF Research Database (Denmark)

    Khawaja, Iram; Mørck, Line Lerche

    2009-01-01

    involvement by the researcher, which challenges traditional perspectives onresearch and researcher positioning. A key point in this regard is the importance ofconstant awareness of and reflection on the multiple ways in which one's positioningas a researcher influences the research process. Studying the other...

  16. Position detector

    International Nuclear Information System (INIS)

    Hayakawa, Toshifumi.

    1985-01-01

    Purpose: To enable to detect the position of an moving object in a control rod position detector, stably in a digital manner at a high accuracy and free from the undesired effects of circumstantial conditions such as the reactor temperature. Constitution: Coils connected in parallel with each other are disposed along the passage of a moving object and variable resistors and relays are connected in series with each of the coils respectively. Light emitting diodes is connected in series with the contacts of the respective relays. The resistance value of the variable resistors are adjusted depending on the changes in the circumstantial conditions and temperature distribution upon carrying out the positional detection. When the object is inserted into a coils, the relevant relay is deenergized, by which the relay contacts are closed to light up the diode. In the same manner, as the object is successively inserted into the coils, the diodes are lighted-up successively thereby enabling highly accurate and stable positional detection in a digital manner, free from the undesired effects of the circumstantial conditions. (Horiuchi, T.)

  17. Positively charged gold nanoparticles capped with folate quaternary chitosan: Synthesis, cytotoxicity, and uptake by cancer cells.

    Science.gov (United States)

    Yen, Hui-Ju; Young, Yen-An; Tsai, Tsung-Neng; Cheng, Kuang-Ming; Chen, Xin-An; Chen, Ying-Chuan; Chen, Cheng-Cheung; Young, Jenn-Jong; Hong, Po-da

    2018-03-01

    In this study, we synthesized various quaternary chitosan derivatives and used them to stabilize gold nanoparticles (AuNPs). These chitosan derivatives comprised N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride (HTCC), folate-HTCC, galactosyl-HTCC, and their fluorescein isothiocyanate-conjugated derivatives. Various positively surface-charged AuNPs were prepared under alkaline conditions using glucose as a reducing agent in the presence of the HTCC derivatives (HTCCs). The effects of the concentration of NaOH, glucose, and HTCCs on the particles size, zeta potential, and stability were studied in detail. Cell cycle assays verify that none of the HTCCs or HTCCs-AuNPs was cytotoxic to human umbilical vein endothelial cells. Flow cytometry analysis showed that the folate HTCC-AuNPs were internalized in Caco-2, HepG2, and HeLa cancer cells to a significantly greater extent than AuNPs without folate. But, galactosyl HTCC-AuNPs only showed high cell uptake by HepG2 cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Formation and stability of manganese-doped ZnS quantum dot monolayers determined by QCM-D and streaming potential measurements.

    Science.gov (United States)

    Oćwieja, Magdalena; Matras-Postołek, Katarzyna; Maciejewska-Prończuk, Julia; Morga, Maria; Adamczyk, Zbigniew; Sovinska, Svitlana; Żaba, Adam; Gajewska, Marta; Król, Tomasz; Cupiał, Klaudia; Bredol, Michael

    2017-10-01

    Manganese-doped ZnS quantum dots (QDs) stabilized by cysteamine hydrochloride were successfully synthesized. Their thorough physicochemical characteristics were acquired using UV-Vis absorption and photoluminescence spectroscopy, X-ray diffraction, dynamic light scattering (DLS), transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared (FT-IR) spectroscopy. The average particle size, derived from HR-TEM, was 3.1nm, which agrees with the hydrodynamic diameter acquired by DLS, that was equal to 3-4nm, depending on ionic strength. The quantum dots also exhibited a large positive zeta potential varying between 75 and 36mV for ionic strength of 10 -4 and 10 -2 M, respectively (at pH 6.2) and an intense luminescent emission at 590nm. The quantum yield was equal to 31% and the optical band gap energy was equal to 4.26eV. The kinetics of QD monolayer formation on silica substrates (silica sensors and oxidized silicon wafers) under convection-controlled transport was quantitatively evaluated by the quartz crystal microbalance (QCM) and the streaming potential measurements. A high stability of the monolayer for ionic strength 10 -4 and 10 -2 M was confirmed in these measurements. The experimental data were adequately reflected by the extended random sequential adsorption model (eRSA). Additionally, thorough electrokinetic characteristics of the QD monolayers and their stability for various ionic strengths and pH were acquired by streaming potential measurements carried out under in situ conditions. These results were quantitatively interpreted in terms of the three-dimensional (3D) electrokinetic model that furnished bulk zeta potential of particles for high ionic strengths that is impractical by other experimental techniques. It is concluded that these results can be used for designing of biosensors of controlled monolayer structure capable to bind various ligands via covalent as well as electrostatic interactions

  19. Determination of the structure of γ-alumina from interatomic potential and first-principles calculations: The requirement of significant numbers of nonspinel positions to achieve an accurate structural model

    International Nuclear Information System (INIS)

    Paglia, Gianluca; Rohl, Andrew L.; Gale, Julian D.; Buckley, Craig E.

    2005-01-01

    We have performed an extensive computational study of γ-Al 2 O 3 , beginning with the geometric analysis of approximately 1.47 billion spinel-based structural candidates, followed by derivative method energy minimization calculations of approximately 122 000 structures. Optimization of the spinel-based structural models demonstrated that structures exhibiting nonspinel site occupancy after simulation were more energetically favorable, as suggested in other computational studies. More importantly, none of the spinel structures exhibited simulated diffraction patterns that were characteristic of γ-Al 2 O 3 . This suggests that cations of γ-Al 2 O 3 are not exclusively held in spinel positions, that the spinel model of γ-Al 2 O 3 does not accurately reflect its structure, and that a representative structure cannot be achieved from molecular modeling when the spinel representation is used as the starting structure. The latter two of these three findings are extremely important when trying to accurately model the structure. A second set of starting models were generated with a large number of cations occupying c symmetry positions, based on the findings from recent experiments. Optimization of the new c symmetry-based structural models resulted in simulated diffraction patterns that were characteristic of γ-Al 2 O 3 . The modeling, conducted using supercells, yields a more accurate and complete determination of the defect structure of γ-Al 2 O 3 than can be achieved with current experimental techniques. The results show that on average over 40% of the cations in the structure occupy nonspinel positions, and approximately two-thirds of these occupy c symmetry positions. The structures exhibit variable occupancy in the site positions that follow local symmetry exclusion rules. This variation was predominantly represented by a migration of cations away from a symmetry positions to other tetrahedral site positions during optimization which were found not to affect the

  20. Current and potential distributions on positive plates with conductive Pb{sub 3}O{sub 4} and BaPbO{sub 3} in their formation and discharge

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yonglang; Liu, Huan [College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350108 (China)

    2008-08-15

    The positive plates with conductive materials, Pb{sub 3}O{sub 4} and BaPbO{sub 3}, in automotive lead-acid batteries were investigated by measuring their current and potential distributions in the course of formation and discharge. It is found that these two conductive materials, especially Pb{sub 3}O{sub 4}, enhance the formation in the initial stage greatly and that they make the current and potential distributions more uniform. In the discharge, the addition of Pb{sub 3}O{sub 4} increases the capacity of the positive plate, but it is unfavorable to the paste curing and causes poor contact between active mass (AM) particles so that the polarization increases greatly at 3 C discharge rate. The BaPbO{sub 3} additive improves not only the formation but also the discharge performance because of its stability in acidic media and at high polarization. The violent charge at high polarization around the plates in the initial formation can lead to poor AM contact and high polarization resistance. (author)

  1. Maintaining positive

    OpenAIRE

    Gheorghe Gh. IONESCU; Adina Letitia NEGRUSA

    2004-01-01

    Maintaining positive work-force relationships includes in effective labor-management relations and making appropriate responses to current employee issues. Among the major current employee issues are protection from arbitrary dismissal, drug and alcohol abuse, privacy rights and family maters and they impact work. In our paper we discus two problems: first, the meanings of industrial democracy; second, the three principal operational concepts of industrial democracy (1) industrial democracy t...

  2. Elaboration of Stable and Antibody Functionalized Positively Charged Colloids by Polyelectrolyte Complexation between Chitosan and Hyaluronic Acid

    Directory of Open Access Journals (Sweden)

    Ramona C. Polexe

    2013-07-01

    Full Text Available In this study, we describe the elaboration of multifunctional positively charged polyelectrolyte complex (PEC nanoparticles, designed to be stable at physiological salt concentration and pH, for effective targeted delivery. These nanoparticles were obtained by charge neutralization between chitosan (CS as polycation and hyaluronic acid (HA as polyanion. We showed that the course of the complexation process and the physico-chemical properties of the resulting colloids were impacted by (i internal parameters such as the Degree of Acetylation (DA, i.e., the molar ration of acetyl glucosamine residues and molar mass of CS, the HA molar mass and (ii external parameters like the charge mixing ratio and the polymer concentrations. As a result, nonstoichiometric colloidal PECs were obtained in water or PBS (pH 7.4 and remained stable over one month. The polymer interactions were characterized by thermal analysis (DSC and TGA and the morphology was studied by scanning electron microscopy. A model antibody, anti-ovalbumine (OVA immunoglobulin A (IgA was sorbed on the particle surface in water and PBS quantitatively in 4 h. The CS-HA/IgA nanoparticles average size was between 425–665 nm with a positive zeta potential. These results pointed out that CS-HA can be effective carriers for use in targeted drug delivery.

  3. zeta-, epsilon-, and gamma-Globin mRNA in blood samples and CD71(+) cell fractions from fetuses and from pregnant and nonpregnant women, with special attention to identification of fetal erythroblasts

    DEFF Research Database (Denmark)

    Høgh, A M; Hviid, T V; Christensen, B

    2001-01-01

    BACKGROUND: Information about the appearance of gamma-, epsilon-, and zeta-globin mRNAs in fetal erythroblasts during gestation and about the presence and amounts of these mRNAs in pregnant and nonpregnant women is important from the perspective of using these molecules as a marker of fetal eryth...

  4. Synthesis, and Characterization, and Evaluation of Cellular Effects of the FOL-PEG-g-PEI-GAL Nanoparticles as a Potential Non-Viral Vector for Gene Delivery

    International Nuclear Information System (INIS)

    Ghiamkazemi, S.; Amanzadeh, A.; Dinarvand, R.; Rafiee-Tehrani, M.; Amini, M.; Ghiamkazemi, S.; Dinarvand, R.; Rafiee-Tehrani, M.; Ghiamkazemi, S.; Rafiee-Tehrani, M.; Amanzadeh, A.; Rafiee-Tehrani, M.

    2010-01-01

    In this manuscript, we synthesized the potential non viral vector for gene delivery with proper transfection efficiency and low cytotoxicity. Polyethylenimine (PEI) is a well-known cationic polymer which has high positive surface charge for condensing plasmid DNA. However; it is highly cytotoxic in many cell lines because of the high surface charge, non-biodegradability and non-biocompatibility. To enhance PEI biodegradability, the graft copolymer PEG-g-PEI was synthesized. To target cancer liver cells, two targeting ligands folic acid and galactose (lactobionic acid) which are over expressed on human hepatocyte carcinoma were attached to graft copolymer and FOL-PEG-g-PEI-GAL copolymer was synthesized. Composition of this grafted copolymer was characterized using 1H-NMR and FTIR spectra. The molecular weight and zeta potential of this copolymer was compared to PEI. The particle size and zeta potential of FOL-PEG-g-PEI-GAL/DNA complexes at various N/P ratio were measured using dynamic light scattering (DLS). Cytotoxicity of the copolymer was also studied in cultured HepG2 human hepatoblastoma cell line. The FOL-PEG-g-PEI-GAL/DNA complexes at various N/P ratios exhibited no cytotoxicity in HepG2 cell line compared to PEI 25K as a control. The novel copolymer showed enhanced biodegradability in physiological conditions in compared with PEI and targeted cultured HepG2 cells. More importantly, significant transfection efficiency was exhibited in cancer liver cells. Together, our results showed that FOL-PEG-g-PEI-GAL nanoparticles could be considered as a useful non-viral vector for targeted gene delivery.

  5. Tracking of [{sup 18}F]FDG-labeled natural killer cells to HER2/neu-positive tumors

    Energy Technology Data Exchange (ETDEWEB)

    Meier, Reinhard [Department of Radiology, University of California San Francisco (United States)], E-mail: reinhardt.meier@gmail.com; Piert, Morand [Department of Radiology, Division of Nuclear Medicine, University of Michigan (United States); Piontek, Guido; Rudelius, Martina [Institute of Pathology, Klinikum rechts der Isar, Technische Universitaet Muenchen (Germany); Oostendorp, Robert A. [3rd Department of Internal Medicine, Klinikum rechts der Isar, Technische Universitaet Muenchen (Germany); Senekowitsch-Schmidtke, Reingard [Department of Nuclear Medicine, Klinikum rechts der Isar, Technische Universitaet Muenchen (Germany); Henning, Tobias D. [Department of Radiology, University of California San Francisco (United States); Wels, Winfried S.; Uherek, Christoph [Chemotherapeutisches Forschungsinstitut, Georg-Speyer-Haus, Frankfurt am Main (Germany); Rummeny, Ernst J. [Department of Radiology, Klinikum rechts der Isar, Technische Universitaet Muenchen (Germany); Daldrup-Link, Heike E. [Department of Radiology, University of California San Francisco (United States)

    2008-07-15

    Introduction: The objective of this study was to label the human natural killer (NK) cell line NK-92 with [{sup 18}F]fluoro-deoxy-glucose (FDG) for subsequent in vivo tracking to HER2/neu-positive tumors. Methods: NK-92 cells were genetically modified to NK-92-scFv(FRP5)-zeta cells, which express a chimeric antigen receptor that is specific to the tumor-associated ErbB2 (HER2/neu) antigen. NK-92 and NK-92-scFv(FRP5)-zeta cells were labeled with [{sup 18}F]FDG by simple incubation at different settings. Labeling efficiency was evaluated by a gamma counter. Subsequently, [{sup 18}F]FDG-labeled parental NK-92 or NK-92-scFv(FRP5)-zeta cells were intravenously injected into mice with implanted HER2/neu-positive NIH/3T3 tumors. Radioactivity in tumors was quantified by digital autoradiography and correlated with histopathology. Results: The NK-92 and NK-92-scFv(FRP5)-zeta cells could be efficiently labeled with [{sup 18}F]FDG by simple incubation. Optimal labeling efficiencies (80%) were achieved using an incubation period of 60 min and additional insulin (10 IU/ml). After injection of 5x10{sup 6} [{sup 18}F]FDG-labeled NK-92-scFv(FRP5)-zeta cells into tumor-bearing mice, digital autoradiography showed an increased uptake of radioactivity in HER2/neu-positive tumors at 60 min postinjection. Conversely, injection of 5x10{sup 6} NK-92 cells not directed against HER2/neu receptors did not result in increased uptake of radioactivity in the tumors. Histopathology confirmed an accumulation of the NK-92-scFv(FRP5)-zeta cells, but not the parental NK cells, in tumor tissues. Conclusion: The human NK cell line NK-92 can be directed against HER2/neu antigens by genetic modification. The genetically modified NK cells can be efficiently labeled with [{sup 18}F]FDG, and the accumulation of these labeled NK cells in HER2/neu-positive tumors can be monitored with autoradiography.

  6. Tracking of [18F]FDG-labeled natural killer cells to HER2/neu-positive tumors

    International Nuclear Information System (INIS)

    Meier, Reinhard; Piert, Morand; Piontek, Guido; Rudelius, Martina; Oostendorp, Robert A.; Senekowitsch-Schmidtke, Reingard; Henning, Tobias D.; Wels, Winfried S.; Uherek, Christoph; Rummeny, Ernst J.; Daldrup-Link, Heike E.

    2008-01-01

    Introduction: The objective of this study was to label the human natural killer (NK) cell line NK-92 with [ 18 F]fluoro-deoxy-glucose (FDG) for subsequent in vivo tracking to HER2/neu-positive tumors. Methods: NK-92 cells were genetically modified to NK-92-scFv(FRP5)-zeta cells, which express a chimeric antigen receptor that is specific to the tumor-associated ErbB2 (HER2/neu) antigen. NK-92 and NK-92-scFv(FRP5)-zeta cells were labeled with [ 18 F]FDG by simple incubation at different settings. Labeling efficiency was evaluated by a gamma counter. Subsequently, [ 18 F]FDG-labeled parental NK-92 or NK-92-scFv(FRP5)-zeta cells were intravenously injected into mice with implanted HER2/neu-positive NIH/3T3 tumors. Radioactivity in tumors was quantified by digital autoradiography and correlated with histopathology. Results: The NK-92 and NK-92-scFv(FRP5)-zeta cells could be efficiently labeled with [ 18 F]FDG by simple incubation. Optimal labeling efficiencies (80%) were achieved using an incubation period of 60 min and additional insulin (10 IU/ml). After injection of 5x10 6 [ 18 F]FDG-labeled NK-92-scFv(FRP5)-zeta cells into tumor-bearing mice, digital autoradiography showed an increased uptake of radioactivity in HER2/neu-positive tumors at 60 min postinjection. Conversely, injection of 5x10 6 NK-92 cells not directed against HER2/neu receptors did not result in increased uptake of radioactivity in the tumors. Histopathology confirmed an accumulation of the NK-92-scFv(FRP5)-zeta cells, but not the parental NK cells, in tumor tissues. Conclusion: The human NK cell line NK-92 can be directed against HER2/neu antigens by genetic modification. The genetically modified NK cells can be efficiently labeled with [ 18 F]FDG, and the accumulation of these labeled NK cells in HER2/neu-positive tumors can be monitored with autoradiography

  7. On the contribution of reclaimed wastewater irrigation to the potential exposure of humans to antibiotics, antibiotic resistant bacteria and antibiotic resistance genes - NEREUS COST Action ES1403 position paper

    DEFF Research Database (Denmark)

    Piña, Benjamin; Bayona, Josep M.; Christou, Anastasis

    2018-01-01

    Antibiotic resistance (AR) is becoming a worldwide threat due to the increasing occurrence of antibiotic-resistant pathogenic bacterial strains. There is a general consensus about the potential implications of the use of antibiotics in livestock on the onset of antibiotic resistant bacteria (ARB......), mainly through meat consumption. However, the ever-increasing use of reclaimed wastewater (RWW) in agriculture may also contribute significantly to the non-accounted exposure to antibiotics, ARB, and antibiotic resistance genes (ARGs). This position paper aims at evaluating the current knowledge...... concerning the occurrence of antibiotics, ARBs, and ARGs in edible parts of different common crops irrigated with RWW. We will discuss which regulations on the use of RWW may contribute to the minimization of the prevalence of these contaminants in crops, and provide recommendations on how to minimize...

  8. [Computer modeling the dependences of the membrane potential for polymeric membrane separated non-homogeneous electrolyte solutions on concentration Rayleigh number].

    Science.gov (United States)

    Slezak, Izabella H; Jasik-Slezak, Jolanta; Bilewicz-Wyrozumska, Teresa; Slezak, Andrzej

    2006-01-01

    On the basis of model equation describing the membrane potential delta psi(s) on concentration Rayleigh number (R(C)), mechanical pressure difference (deltaP), concentration polarization coefficient (zeta s) and ratio concentration of solutions separated by membrane (Ch/Cl), the characteristics delta psi(s) = f(Rc)(delta P, zeta s, Ch/Cl) for steady values of zeta s, R(C) and Ch/Cl in single-membrane system were calculated. In this system neutral and isotropic polymeric membrane oriented in horizontal plane, the non-homogeneous binary electrolytic solutions of various concentrations were separated. Nonhomogeneity of solutions is results from creations of the concentration boundary layers on both sides of the membrane. Calculations were made for the case where on a one side of the membrane aqueous solution of NaCl at steady concentration 10(-3) mol x l(-1) (Cl) was placed and on the other aqueous solutions of NaCl at concentrations from 10(-3) mol x l(-1) to 2 x 10(-2) mol x l(-1) (Ch). Their densities were greater than NaCl solution's at 10(-3) mol x l(-1). It was shown that membrane potential depends on hydrodynamic state of a complex concentration boundary layer-membrane-concentration boundary layer, what is controlled by deltaP, Ch/Cl, Rc and Zeta(s).

  9. Complementation of non-tumorigenicity of HPV18-positive cervical carcinoma cells involves differential mRNA expression of cellular genes including potential tumor suppressor genes on chromosome 11q13.

    Science.gov (United States)

    Kehrmann, Angela; Truong, Ha; Repenning, Antje; Boger, Regina; Klein-Hitpass, Ludger; Pascheberg, Ulrich; Beckmann, Alf; Opalka, Bertram; Kleine-Lowinski, Kerstin

    2013-01-01

    The fusion between human tumorigenic cells and normal human diploid fibroblasts results in non-tumorigenic hybrid cells, suggesting a dominant role for tumor suppressor genes in the generated hybrid cells. After long-term cultivation in vitro, tumorigenic segregants may arise. The loss of tumor suppressor genes on chromosome 11q13 has been postulated to be involved in the induction of the tumorigenic phenotype of human papillomavirus (HPV)18-positive cervical carcinoma cells and their derived tumorigenic hybrid cells after subcutaneous injection in immunocompromised mice. The aim of this study was the identification of novel cellular genes that may contribute to the suppression of the tumorigenic phenotype of non-tumorigenic hybrid cells in vivo. We used cDNA microarray technology to identify differentially expressed cellular genes in tumorigenic HPV18-positive hybrid and parental HeLa cells compared to non-tumorigenic HPV18-positive hybrid cells. We detected several as yet unknown cellular genes that play a role in cell differentiation, cell cycle progression, cell-cell communication, metastasis formation, angiogenesis, antigen presentation, and immune response. Apart from the known differentially expressed genes on 11q13 (e.g., phosphofurin acidic cluster sorting protein 1 (PACS1) and FOS ligand 1 (FOSL1 or Fra-1)), we detected novel differentially expressed cellular genes located within the tumor suppressor gene region (e.g., EGF-containing fibulin-like extracellular matrix protein 2 (EFEMP2) and leucine rich repeat containing 32 (LRRC32) (also known as glycoprotein-A repetitions predominant (GARP)) that may have potential tumor suppressor functions in this model system of non-tumorigenic and tumorigenic HeLa x fibroblast hybrid cells. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Streaming potential revisited: the influence of convection on the surface conductivity.

    Science.gov (United States)

    Saini, Rakesh; Garg, Abhinandan; Barz, Dominik P J

    2014-09-16

    Electrokinetic phenomena play an important role in the electrical characterization of surfaces. In terms of planar or porous substrates, streaming potential and/or streaming current measurements can be used to determine the zeta potential of the substrates in contact with aqueous electrolytes. In this work, we perform electrical impedance spectroscopy measurements to infer the electrical resistance in a microchannel with the same conditions as for a streaming potential experiment. Novel correlations are derived to relate the streaming current and streaming potential to the Reynolds number of the channel flow. Our results not only quantify the influence of surface conductivity, and here especially the contribution of the stagnant layer, but also reveal that channel resistance and therefore zeta potential are influenced by the flow in the case of low ionic strengths. We conclude that convection can have a significant impact on the electrical double layer configuration which is reflected by changes in the surfaces conductivity.

  11. Position paper

    DEFF Research Database (Denmark)

    Heidbuchel, Hein; Papadakis, Michael; Panhuyzen-Goedkoop, Nicole

    2013-01-01

    Sports cardiology is a new and rapidly evolving subspecialty. It aims to elucidate the cardiovascular effects of regular exercise and delineate its benefits and risks, so that safe guidance can be provided to all individuals engaging in sports and/or physical activity in order to attain the maximum...... potential benefit at the lowest possible risk. The European Society of Cardiology (ESC) advocates systematic preparticipation cardiovascular screening in an effort to identify competitive athletes at risk of exercise-related cardiovascular events and sudden cardiac death. However, the implementation...... that the curriculum would facilitate more uniform training and guideline implementation throughout Europe, and safeguard that evaluation and guidance of competitive athletes or individuals who wish to engage in leisure-time sports activities is performed by physicians with expertise in the field. The current...

  12. Positive Psychology and Positive Education: Old Wine in New Bottles?

    Science.gov (United States)

    Kristjansson, Kristjan

    2012-01-01

    The recently fashionable theories of positive psychology have educational ramifications at virtually every level of engagement, culminating in the model of positive education. In this critical review, I scrutinize positive education as a potential theory in educational psychology. Special attention is given to conceptual controversies and…

  13. POTENCIAL ZETA (Z COMO CRITERIO DE OPTIMIZACIÓN DE DOSIFICACIÓN DE COAGULANTE EN PLANTA DE TRATAMIENTO DE AGUA POTABLE

    Directory of Open Access Journals (Sweden)

    BIBIANA BETANCUR C.

    2012-01-01

    Full Text Available La calidad del agua cruda del Río Otún que abastece la planta de tratamiento de agua potable de Aguas y Aguas de Pereira puede presentar fluctuaciones en cortos periodos de tiempo. Por esta razón se requiere un instrumento que permita tomar decisiones rápidas para modificar la dosis de coagulante a utilizar en el tratamiento con base en un criterio cuantificable y preciso como el potencial zeta (ζ. En este estudio se determinó que para un intervalo de ζ desde -2.28 mV a +1.2 mV del agua coagulada se obtienen valores bajos de turbiedad y color del agua sedimentada. Es posible alcanzar un óptimo desempeño del proceso de floculación y sedimentación efectuando mediciones de ζ en el agua coagulada como indicador de desestabilización de las partículas. ζ presenta una correlación positiva con la dosis de coagulante aplicada, modificando la dosis de coagulante es posible alcanzar valores de ζ cercanos a cero.

  14. Introducing Positive Psychology to SLA

    Science.gov (United States)

    MacIntyre, Peter D.; Mercer, Sarah

    2014-01-01

    Positive psychology is a rapidly expanding subfield in psychology that has important implications for the field of second language acquisition (SLA). This paper introduces positive psychology to the study of language by describing its key tenets. The potential contributions of positive psychology are contextualized with reference to prior work,…

  15. Synthesis of Tc-99m labeled 1,2,3-triazole-4-yl c-met binding peptide as a potential c-met receptor kinase positive tumor imaging agent.

    Science.gov (United States)

    Kim, Eun-Mi; Joung, Min-Hee; Lee, Chang-Moon; Jeong, Hwan-Jeong; Lim, Seok Tae; Sohn, Myung-Hee; Kim, Dong Wook

    2010-07-15

    The mesenchymal-epithelial transition factor (c-Met), which is related to tumor cell growth, angiogenesis and metastases, is known to be overexpressed in several tumor types. In this study, we synthesized technetium-99m labeled 1,2,3-triazole-4-yl c-Met binding peptide (cMBP) derivatives, prepared by solid phase peptide synthesis and the 'click-to-chelate' protocol for the introduction of tricarbonyl technetium-99m, as a potential c-Met receptor kinase positive tumor imaging agent, and evaluated their in vitro c-Met binding affinity, cellular uptake, and stability. The (99m)Tc labeled cMBP derivatives ([(99m)Tc(CO)(3)]12, [(99m)Tc(CO)(3)]13, and [(99m)Tc(CO)(3)]14) were prepared in 85-90% radiochemical yields. The cold surrogate cMBP derivatives, [Re(CO)(3)]12, [Re(CO)(3)]13, and [Re(CO)(3)]14, were shown to have high binding affinities (0.13 microM, 0.06 microM, and 0.16 microM, respectively) to a purified cMet/Fc chimeric recombinant protein. In addition, the in vitro cellular uptake and inhibition studies demonstrated the high specific binding of these (99m)Tc labeled cMBP derivatives ([(99m)Tc(CO)(3)]12-14) to c-Met receptor positive U87MG cells. 2010 Elsevier Ltd. All rights reserved.

  16. Oral treatment with a rattlesnake native polypeptide crotamine efficiently inhibits the tumor growth with no potential toxicity for the host animal and with suggestive positive effects on animal metabolic profile.

    Science.gov (United States)

    Campeiro, Joana D; Marinovic, Marcelo P; Carapeto, Fernando Cintra; Dal Mas, Caroline; Monte, Gabriela Guilherme; Carvalho Porta, Lucas; Nering, Marcela B; Oliveira, Eduardo B; Hayashi, Mirian A F

    2018-02-01

    The efficacy of crotamine as antitumoral was first demonstrated by daily intraperitoneal (IP) injections of low doses of this toxin in an animal model bearing melanoma tumors. Significant inhibition of tumor growth and increased lifespan of mice bearing tumor was also noticed after 21 consecutive days of this daily IP administration of crotamine. However, due to the limited acceptance of treatments by IP route in clinical conditions, herein, we evaluated the antitumor effect of this native polypeptide employing the oral route. The efficacy of crotamine in inhibiting the melanoma growth in vivo, even after passing through the gastrointestinal tract of the animal, was confirmed here. In addition, biochemical biomarkers and also histopathological analysis showed both the absence of any potential toxic effects in tissues or organs of the animal in which the highest accumulation of crotamine is expected. Interestingly, a reduction of weight gain was observed mainly in animals with tumor treated with crotamine by IP route, but not by oral administration. Albeit, oral administered crotamine was able to significantly decrease the body weight gain of healthy animals without tumor. Taking advantage of this same experimental animal models receiving crotamine by oral route, it was possible to show metabolic changes as the increased capacity of glucose clearance, which was accompanied by a reduction of the total cholesterol, and by increased high-density lipoprotein levels, both observed mainly in the absence of tumor. Triglycerides and low-density lipoprotein were also significantly decreased, but only in the absence of tumor. Taken together, these data suggest a clear trend for metabolic positive effects and mischaracterize unhealthy condition of animals, with or without tumors, treated with crotamine for 21 days. In addition, this study confirmed the efficacy of crotamine administered by oral route as antitumor agent, which besides the additional advantage of

  17. Effect of Adsorbed Protein on the Hydraulic Permeability, Membrane and Streaming Potential Values Measured across a Microporous Membrane

    DEFF Research Database (Denmark)

    Benavente, Juana; Jonsson, Gunnar Eigil

    1998-01-01

    permeability decreases strongly when the pH decreases, having its minimum value at the isoelectric point of the protein; the apparent zeta potential values are also dependent on both pH and salt concentration. Differences in the streaming potential coefficient determined for two membranes fouled under......The effect of the adsorption of a protein, bovine serum albumin (BSA), on the membrane potential, flux reduction and streaming potential measured across a microporous polysulphone membrane with different NaCl solutions and pH values is studied. From electrokinetic phenomena, information about...... the electrical properties of the membrane (fixed charge concentration and ionic transport numbers) or the membrane/solute interactions (streaming and zeta potentials) can be obtained. The influence of pH and ionic strength on volume flux and streaming potential values is considered. Results show that hydraulic...

  18. Green synthesis of silver nanoparticles from marigold flower and its synergistic antimicrobial potential

    Directory of Open Access Journals (Sweden)

    Hemali Padalia

    2015-09-01

    Full Text Available In the present study, silver nanoparticles were synthesized using flower broth of Tagetes erecta as reductant by a simple and eco-friendly route. The aqueous silver ions when exposed to flower broth were reduced and resulted in green synthesis of silver nanoparticles. The silver nanoparticles were characterized by UV–visible spectroscopy, zeta potential, Fourier transform infra-red spectroscopy (FTIR, X-ray diffraction, Transmission electron microscopy (TEM analysis, Energy dispersive X-ray analysis (EDX and selected area electron diffraction (SAED pattern. UV–visible spectrum of synthesized silver nanoparticles showed maximum peak at 430 nm. TEM analysis revealed that the particles were spherical, hexagonal and irregular in shape and size ranging from 10 to 90 nm and Energy dispersive X-ray (EDX spectrum confirmed the presence of silver metal. Synergistic antimicrobial potential of silver nanoparticles was evaluated with various commercial antibiotics against Gram positive (Staphylococcus aureus and Bacillus cereus, Gram negative (Escherichia coli and Pseudomonas aeruginosa bacteria and fungi (Candida glabrata, Candida albicans, Cryptococcae neoformans. The antifungal activity of AgNPs with antibiotics was better than antibiotics alone against the tested fungal strains and Gram negative bacteria, thus signification of the present study is in production of biomedical products.

  19. Structural analysis of intermolecular interactions in the kinesin adaptor complex fasciculation and elongation protein zeta 1/ short coiled-coil protein (FEZ1/SCOCO.

    Directory of Open Access Journals (Sweden)

    Marcos Rodrigo Alborghetti

    Full Text Available Cytoskeleton and protein trafficking processes, including vesicle transport to synapses, are key processes in neuronal differentiation and axon outgrowth. The human protein FEZ1 (fasciculation and elongation protein zeta 1 / UNC-76, in C. elegans, SCOCO (short coiled-coil protein / UNC-69 and kinesins (e.g. kinesin heavy chain / UNC116 are involved in these processes. Exploiting the feature of FEZ1 protein as a bivalent adapter of transport mediated by kinesins and FEZ1 protein interaction with SCOCO (proteins involved in the same path of axonal growth, we investigated the structural aspects of intermolecular interactions involved in this complex formation by NMR (Nuclear Magnetic Resonance, cross-linking coupled with mass spectrometry (MS, SAXS (Small Angle X-ray Scattering and molecular modelling. The topology of homodimerization was accessed through NMR (Nuclear Magnetic Resonance studies of the region involved in this process, corresponding to FEZ1 (92-194. Through studies involving the protein in its monomeric configuration (reduced and dimeric state, we propose that homodimerization occurs with FEZ1 chains oriented in an anti-parallel topology. We demonstrate that the interaction interface of FEZ1 and SCOCO defined by MS and computational modelling is in accordance with that previously demonstrated for UNC-76 and UNC-69. SAXS and literature data support a heterotetrameric complex model. These data provide details about the interaction interfaces probably involved in the transport machinery assembly and open perspectives to understand and interfere in this assembly and its involvement in neuronal differentiation and axon outgrowth.

  20. [Computer modeling the hydrostatic pressure characteristics of the membrane potential for polymeric membrane, separated non-homogeneous electrolyte solutions].

    Science.gov (United States)

    Slezak, Izabella H; Jasik-Slezak, Jolanta; Rogal, Mirosława; Slezak, Andrzej

    2006-01-01

    On the basis of model equation depending the membrane potential deltapsis, on mechanical pressure difference (deltaP), concentration polarization coefficient (zetas), concentration Rayleigh number (RC) and ratio concentration of solutions separated by membrane (Ch/Cl), the characteristics deltapsis = f(deltaP)zetas,RC,Ch/Cl for steady values of zetas, RC and Ch/Cl in single-membrane system were calculated. In this system neutral and isotropic polymeric membrane oriented in horizontal plane, the non-homogeneous binary electrolytic solutions of various concentrations were separated. Nonhomogeneity of solutions is results from creations of the concentration boundary layers on both sides of the membrane. Calculations were made for the case where on a one side of the membrane aqueous solution of NaCl at steady concentration 10(-3) mol x l(-1) (Cl) was placed and on the other aqueous solutions of NaCl at concentrations from 10(-3) mol x l(-1) to 2 x 10(-2) mol x l(-1) (Ch). Their densities were greater than NaCl solution's at 10(-3) mol x l(-1). It was shown that membrane potential depends on hydrodynamic state of a complex concentration boundary layer-membrane-concentration boundary layer, what is controlled by deltaP, Ch/Cl, RC and zetas.

  1. Comparison of false-negative/positive results of intraoperative evoked potential monitoring between no and partial neuromuscular blockade in patients receiving propofol/remifentanil-based anesthesia during cerebral aneurysm clipping surgery: A retrospective analysis of 685 patients.

    Science.gov (United States)

    Kim, Sung-Hoon; Jin, Seok-Joon; Karm, Myong-Hwan; Moon, Young-Jin; Jeong, Hye-Won; Kim, Jae-Won; Ha, Seung-Il; Kim, Joung-Uk

    2016-08-01

    Although the elicited responses of motor evoked potential (MEP) monitoring are very sensitive to suppression by anesthetic agents and muscle relaxants, the use of neuromuscular blockade (NMB) during MEP monitoring is still controversial because of serious safety concerns and diagnostic accuracy. Here, we evaluated the incidence of unacceptable movement and compared false-negative MEP results between no and partial NMB during cerebral aneurysm clipping surgery. We reviewed patient medical records for demographic data, anesthesia regimen, neurophysiology event logs, MEP results, and clinical outcomes. Patients were divided into 2 groups according to the intraoperative use of NMB: no NMB group (n = 276) and partial NMB group (n = 409). We compared the diagnostic accuracy of MEP results to predict postoperative outcomes between both groups. Additionally, we evaluated unwanted patient movement during MEP monitoring in both groups. Of the 685 patients, 622 (90.8%) manifested no intraoperative changes in MEP and no postoperative motor deficits. Twenty patients showed postoperative neurologic deficits despite preserved intraoperative MEP. False-positive MEP results were 3.6% in the no NMB group and 3.9% in the partial NMB group (P = 1.00). False-negative MEP results were 1.1% in the no NMB group and 4.2% in the partial NMB group (P = 0.02). No spontaneous movement or spontaneous respiration was observed in either group. Propofol/remifentanil-based anesthesia without NMB decreases the stimulation intensity of MEPs, which may reduce the false-negative ratio of MEP monitoring during cerebral aneurysm surgery. Our anesthetic protocol enabled reliable intraoperative MEP recording and patient immobilization during cerebral aneurysm clipping surgery.

  2. S-thanatin functionalized liposome potentially targeting on Klebsiella pneumoniae and its application in sepsis mouse model

    Directory of Open Access Journals (Sweden)

    Xiaobo eFan

    2015-10-01

    Full Text Available S-thanatin (Ts was a short antimicrobial peptide with selective antibacterial activity. In this study, we aimed to design a drug carrier with specific bacterial targeting potential. The positively charged Ts was modified onto the liposome surface by linking Ts to the constituent lipids via a PEG linker. The benefits of this design were evaluated by preparing a series of liposomes and comparing their biological effects in vitro and in vivo. The particle size and Zeta potential of the constructed liposomes were measured with a Zetasizer Nano ZS system and a confocal laser scanning microscope (CLSM. The in vitro drug delivery potential was evaluated by measuring the cellular uptake of encapsulated levofloxacin using HPLC. Ts-linked liposome or its conjugates with quantum dots favored bacterial cells, and increased the bacterial uptake of levofloxacin. In antimicrobial assays, the Ts and levofloxacin combination showed a synergistic effect, and Ts-LPs-LEV exhibited excellent activity against the quality control stain Klebsiella pneumoniae ATCC 700603 and restored the susceptibility of multidrug-resistant K. pneumoniae clinical isolates to levofloxacin in vitro. Furthermore, Ts-LPs-LEV markedly reduced the lethality rate of the septic shock and resulted in rapid bacterial clearance in mouse models receiving clinical MDR isolates. These results suggest that the Ts-functionalized liposome may be a promising antibiotic delivery system for clinical infectious disorders caused by MDR bacteria, in particular the sepsis related diseases.

  3. Accentuate the Positive: Positive Sentiments and Status in Task Groups

    Science.gov (United States)

    Bianchi, Alison J.; Lancianese, Donna A.

    2007-01-01

    We explore the capacity of positive sentiments, those enduring affective states one achieves when one likes another, to impact status structures. Do positive sentiments combine with existing aspects of interaction to create status hierarchies and potentially change the social order, or do they moderate the effects of extant structure by dampening…

  4. Defects in the Zeta Chain Expression (ζ in a Group of Patients with SLE, Scleroderma and Late-onset Arthritis, Colombia 2014

    Directory of Open Access Journals (Sweden)

    Heber Siachoque-Montañez

    2014-09-01

    test. Conclusion: We observed a reduced level of in the zeta chain expression in T cells in patients with autoimmune disease without use of corticosteroids.

  5. Workaholism as positive social deviance

    OpenAIRE

    Belousov, Konstantin

    2014-01-01

    The article justifies a potential research of workaholism as a social phenomenon within the positive deviance approach. In this paper, the authors provide definitions of positive deviance by foreign and Russian scholars as well as analyse how such behaviors depart from the norms of a referent group and adduce a number of studies positively assessing the concept. Finally, the authors conclude that workaholism can be regarded as a supraconformal behavior that can boost economic, cultural and sc...

  6. Ga-66 labeled somatostatin analogue DOTA-DPhe1-Tyr3-octreotide as a potential agent for positron emission tomography imaging and receptor mediated internal radiotherapy of somatostatin receptor positive tumors

    International Nuclear Information System (INIS)

    Ugur, Oemer; Kothari, Paresh J.; Finn, Ronald D.; Zanzonico, Pat; Ruan, Shutian; Guenther, Ilonka; Maecke, Helmut R.; Larson, Steven M.

    2002-01-01

    Radionuclide labeled somatostatin analogues selectively target somatostatin receptor (SSTR)-expressing tumors as a basis for diagnosis and treatment of these tumors. Recently, a DOTA-functionalized somatostatin analogue, DOTATOC (DOTA-DPhe 1 -Tyr 3 -octreotide) has been developed. This compound has been shown to be superior to the other somatostatin analogues as indicated by its uniquely high tumor-to-non-target tissue ratio. DOTATOC can be labeled with a variety of radiometals including gallium radioisotopes. Gallium-66 is a positron emitting radionuclide (T 1/2 =9.5 hr; β + =56%), that can be produced in carrier free form by a low-beam energy cyclotron. In this study we investigated SSTR targeting characteristics of 66 Ga-DOTATOC in AR42J rat pancreas tumor implanted nude mice as a potential agent for diagnosis and receptor-mediated internal radiotherapy of SSTR-expressing tumors. We compared our results with 67 Ga- and 68 Ga- labeled DOTATOC. The radiolabeling procedure gave labeling yield ranged from 85-95% and radiochemical and chemical purity was >95%. In-vitro competitive binding curves and in-vivo competitive displacement studies with an excess of unlabeled peptide indicates that there is specific binding of the radioligand to SSTR. Animal biodistribution data and serial microPET TM images demonstrated rapid tumor uptake and rapid clearance from the blood and all tissues except kidney. Maximum % ID/g values for tumor were 10.0±0.7, 13.2±2.1 and 9.8±1.5 for 66 Ga-, 67 Ga-, and 68 Ga-DOTATOC, respectively. Calculated tumor, kidney and bone marrow doses for 66 Ga-DOTATOC based on biodistribution data were 178, 109 and 1.2 cGy/MBq, respectively. We conclude that 66 Ga labeled DOTATOC can be used for PET diagnosis and quantitative imaging-based dosimetry of SSTR positive tumors. 66 Ga-DOTATOC may also be used in higher doses for ablation of these tumors. However, kidney is the critical organ for toxicity (tumor/kidney ratio 1.64), and high kidney uptake must

  7. Ga-66 labeled somatostatin analogue DOTA-DPhe{sup 1}-Tyr{sup 3}-octreotide as a potential agent for positron emission tomography imaging and receptor mediated internal radiotherapy of somatostatin receptor positive tumors

    Energy Technology Data Exchange (ETDEWEB)

    Ugur, Oemer E-mail: ougur@hacettepe.edu.tr; Kothari, Paresh J.; Finn, Ronald D.; Zanzonico, Pat; Ruan, Shutian; Guenther, Ilonka; Maecke, Helmut R.; Larson, Steven M

    2002-02-01

    Radionuclide labeled somatostatin analogues selectively target somatostatin receptor (SSTR)-expressing tumors as a basis for diagnosis and treatment of these tumors. Recently, a DOTA-functionalized somatostatin analogue, DOTATOC (DOTA-DPhe{sup 1}-Tyr{sup 3}-octreotide) has been developed. This compound has been shown to be superior to the other somatostatin analogues as indicated by its uniquely high tumor-to-non-target tissue ratio. DOTATOC can be labeled with a variety of radiometals including gallium radioisotopes. Gallium-66 is a positron emitting radionuclide (T{sub 1/2} =9.5 hr; {beta}{sup +}=56%), that can be produced in carrier free form by a low-beam energy cyclotron. In this study we investigated SSTR targeting characteristics of {sup 66}Ga-DOTATOC in AR42J rat pancreas tumor implanted nude mice as a potential agent for diagnosis and receptor-mediated internal radiotherapy of SSTR-expressing tumors. We compared our results with {sup 67}Ga- and {sup 68}Ga- labeled DOTATOC. The radiolabeling procedure gave labeling yield ranged from 85-95% and radiochemical and chemical purity was >95%. In-vitro competitive binding curves and in-vivo competitive displacement studies with an excess of unlabeled peptide indicates that there is specific binding of the radioligand to SSTR. Animal biodistribution data and serial microPET{sup TM} images demonstrated rapid tumor uptake and rapid clearance from the blood and all tissues except kidney. Maximum % ID/g values for tumor were 10.0{+-}0.7, 13.2{+-}2.1 and 9.8{+-}1.5 for {sup 66}Ga-, {sup 67}Ga-, and {sup 68}Ga-DOTATOC, respectively. Calculated tumor, kidney and bone marrow doses for {sup 66}Ga-DOTATOC based on biodistribution data were 178, 109 and 1.2 cGy/MBq, respectively. We conclude that {sup 66}Ga labeled DOTATOC can be used for PET diagnosis and quantitative imaging-based dosimetry of SSTR positive tumors. {sup 66}Ga-DOTATOC may also be used in higher doses for ablation of these tumors. However, kidney is the

  8. Elucidation of substituted ester group position in octenylsuccinic anhydride modified sugary maize soluble starch.

    Science.gov (United States)

    Ye, Fan; Miao, Ming; Huang, Chao; Lu, Keyu; Jiang, Bo; Zhang, Tao

    2014-12-03

    The octenylsuccinic groups in esterification-modified sugary maize soluble starches with a low (0.0191) or high (0.0504) degree of substitution (DS) were investigated by amyloglucosidase hydrolysis followed by a combination of chemical and physical analysis. The results showed the zeta-potential remained at approximately the same value regardless of excessive hydrolysis. The weight-average molecular weight decreased rapidly and reached 1.22 × 10(7) and 1.60 × 10(7) g/mol after 120 min for low-DS and high-DS octenylsuccinic anhydride (OSA) modified starch, respectively. The pattern of z-average radius of gyration as well as particle size change was similar to that of Mw, and z-average radius of gyration decreased much more slowly, especially for high-DS OSA starch. Compared to native starch, two characteristic absorption peaks at 1726.76 and 1571.83 cm(-1) were observed in FT-IR spectra, and the intensity of absorption peaks increased with increasing DS. The NMR results showed that OSA starch had several additional peaks at 0.8-3.0 ppm and a shoulder at 5.56 ppm for OSA substituents, which were grafted at O-2 and O-3 positions in soluble starch. The even distribution of OSA groups in the center area of soluble starch particle has been directly shown under CLSM. Most substitutions were located near branching points of soluble starch particles for a low-DS modified starch, whereas the substituted ester groups were located near branching points as well as at the nonreducing ends in OSA starch with a high DS.

  9. Benign positional vertigo

    Science.gov (United States)

    Vertigo - positional; Benign paroxysmal positional vertigo; BPPV: dizziness- positional ... Benign positional vertigo is also called benign paroxysmal positional vertigo (BPPV). It is caused by a problem in the inner ear. ...

  10. Biocompatible Polyelectrolyte Complex Nanoparticles from Lactoferrin and Pectin as Potential Vehicles for Antioxidative Curcumin.

    Science.gov (United States)

    Yan, Jing-Kun; Qiu, Wen-Yi; Wang, Yao-Yao; Wu, Jian-Yong

    2017-07-19

    Polyelectrolyte complex nanoparticles (PEC NPs) were fabricated via electrostatic interactions between positively charged heat-denatured lactoferrin (LF) particles and negatively charged pectin. The obtained PEC NPs were then utilized as curcumin carriers. PEC NPs were prepared by mixing 1.0 mg/mL solutions of heat-denatured LF and pectin at a mass ratio of 1:1 (w/w) in the absence of NaCl at pH 4.50. PEC NPs that were prepared under optimized conditions were spherical in shape with a particle size of ∼208 nm and zeta potential of ∼-32 mV. Hydrophobic curcumin was successfully encapsulated into LF/pectin PEC NPs with high encapsulation efficiency (∼85.3%) and loading content (∼13.4%). The in vitro controlled release and prominent antioxidant activities of curcumin from LF/pectin PEC NPs were observed. The present work provides a facile and fast method to synthesize nanoscale food-grade delivery systems for the improved water solubility, controlled release, and antioxidant activity of hydrophobic curcumin.

  11. The relationship between Mycobacterium tuberculosis MGIT time to positivity and cfu in sputum samples demonstrates changing bacterial phenotypes potentially reflecting the impact of chemotherapy on critical sub-populations

    NARCIS (Netherlands)

    Bowness, R.; Boeree, M.J.; Aarnoutse, R.; Dawson, R.; Diacon, A.; Mangu, C.; Heinrich, N.; Ntinginya, N.E.; Kohlenberg, A.; Mtafya, B.; Phillips, P.P.; Rachow, A.; Plemper van Balen, G.; Gillespie, S.H.

    2015-01-01

    OBJECTIVES: The relationship between cfu and Mycobacterial Growth Indicator Tube (MGIT) time to positivity (TTP) is uncertain. We attempted to understand this relationship and create a mathematical model to relate these two methods of determining mycobacterial load. METHODS: Sequential

  12. Position automatic determination technology

    International Nuclear Information System (INIS)

    1985-10-01

    This book tells of method of position determination and characteristic, control method of position determination and point of design, point of sensor choice for position detector, position determination of digital control system, application of clutch break in high frequency position determination, automation technique of position determination, position determination by electromagnetic clutch and break, air cylinder, cam and solenoid, stop position control of automatic guide vehicle, stacker crane and automatic transfer control.

  13. MHC class I ligation of human T cells activates the ZAP70 and p56lck tyrosine kinases, leads to an alternative phenotype of the TCR/CD3 zeta-chain, and induces apoptosis

    DEFF Research Database (Denmark)

    Skov, S; Bregenholt, S; Claesson, Mogens Helweg

    1997-01-01

    Cross-linking of MHC class I (MHC-I) molecules on human T cells induces signal-transduction events, including activation of tyrosine kinases, tyrosine phosphorylation of phospholipase C-gamma 1, and elevation of the intracellular free calcium concentration. In this study, we demonstrate...... that the ZAP70 tyrosine kinase is tyrosine phosphorylated in Jurkat T cells and in purified peripheral T cells after MHC-I ligation. The tyrosine-phosphorylated ZAP70 kinase exhibits a particular phenotype with low affinities for proteins at 21, 40, 60, and 120 kDa, proteins normally co-precipitated with ZAP70...... after TCR/CD3 stimulation. The phosphorylation of ZAP70 after MHC-I ligation was dependent on TCR/CD3 surface expression. One of the natural substrates for ZAP70 is the zeta-chain dimer of the TCR/CD3 complex. MHC-I cross-linking induces a phosphorylated zeta-protein that migrates as a dimer at 42 k...

  14. Chemical applicability domain of the Local Lymph Node Assay (LLNA) for skin sensitisation potency. Part 3. Apparent discrepancies between LLNA and GPMT sensitisation potential: False positives or differences in sensitivity?

    Science.gov (United States)

    Roberts, David W; Schultz, Terry W; Api, Anne Marie

    2016-10-01

    The Local Lymph Node Assay (LLNA) is the gold standard regulatory toxicology test for skin sensitisation along with the guinea pig maximisation test (GPMT). Compared with the GPMT, LLNA uses fewer animals, it is quantitative, and it gives a numerical prediction of potency. However several concerns have been raised with this assay, mainly related to false positives and false negatives. Over the years, many authors, including the developers of the assay, have presented cases where there have been discrepancies between the GMPT and LLNA results. Several theories have been put forward for these discrepancies, the main one being the "over-sensitivity" of the GPMT. This paper analyses the data from a systematic study, published in three papers from 2008 to 2011, covering several classes of chemicals, in particular unsaturated fatty acids, sugar surfactants and ethoxylated alcohols, with many cases of chemicals testing positive in the LLNA being negative in the GPMT. Based on consideration of reaction chemistry and structural alerts, it is concluded that these discrepancies are not LLNA false positives, but can be rationalised in terms of the different protocols of the assays. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Positive Psychology: Positive Emotions and Emotional Intelegence

    OpenAIRE

    Miloseva, Lence

    2008-01-01

    The paper focuses on the and emotional intelligence. We try to answer on some questions regarding the role which positive emotions have in our life’s. The broaden-and-build theory (Fredrickson, 1998; 2001) predicts that positive emotions are useful in several ways. They guide present behavior, by broadening one’s attention and cognition, setting the stage for creative, explorative, and innovative pursuits. As well, positive emotions build personal and social resources to help individuals achi...

  16. Introducing positive psychology to SLA

    Directory of Open Access Journals (Sweden)

    Sarah Mercer

    2014-01-01

    Full Text Available Positive psychology is a rapidly expanding subfield in psychology that has important implications for the field of second language acquisition (SLA. This paper introduces positive psychology to the study of language by describing its key tenets. The potential contributions of positive psychology are contextualized with reference to prior work, including the humanistic movement in language teaching, models of motivation, the concept of an affective filter, studies of the good language learner, and the concepts related to the self. There are reasons for both encouragement and caution as studies inspired by positive psychology are undertaken. Papers in this special issue of SSLLT cover a range of quantitative and qualitative methods with implications for theory, research, and teaching practice. The special issue serves as a springboard for future research in SLA under the umbrella of positive psychology.

  17. European Food Safety Authority; Analysis of the baseline survey of Salmonella in holdings with breeding pigs, in the EU, 2008; Part B: Analysis of factors potentially associated with Salmonella pen positivity

    DEFF Research Database (Denmark)

    Hald, Tine

    or slaughter (production holdings) were sampled. In each selected holding, pooled fresh faecal samples were collected from 10 randomly chosen pens of breeding pigs over six months of age, representing the different stages of the breeding herd, and examined for the presence of Salmonella. Analyses at country......, multivariable regression analysis showed that the odds of Salmonella-positive pens with pigs increased with the number of breeding pigs in the holding and with the following pen-level factors: flooring systems other than slatted floors or solid floors with straw, presence of maiden gilts, number of pigs per pen...

  18. Want Positive Behavior? Use Positive Language

    Science.gov (United States)

    Wood, Chip; Freeman-Loftis, Babs

    2012-01-01

    Positive adult language is the professional use of words and tone of voice to enable students to learn in an engaged, active way. This includes learning social skills. To guide children toward choosing and maintaining positive behaviors, adults need to carefully choose the words and tone of voice used when speaking to them. Learning to use…

  19. Free-Living Species of Carnivorous Mammals in Poland: Red Fox, Beech Marten, and Raccoon as a Potential Reservoir of Salmonella, Yersinia, Listeria spp. and Coagulase-Positive Staphylococcus.

    Directory of Open Access Journals (Sweden)

    Aneta Nowakiewicz

    Full Text Available The objective of the study was to examine a population of free-living carnivorous mammals most commonly found in Poland (red fox, beech marten, and raccoon for the occurrence of bacteria that are potentially pathogenic for humans and other animal species and to determine their virulence potential (the presence of selected virulence genes. From the total pool of isolates obtained (n = 328, we selected 90 belonging to species that pose the greatest potential threat to human health: Salmonella spp. (n = 19; 4.51%, Yersinia enterocolitica (n = 10; 2.37%, Listeria monocytogenes and L. ivanovii (n = 21, and Staphylococcus aureus (n = 40; 9.5%. The Salmonella spp. isolates represented three different subspecies; S. enterica subsp. enterica accounted for a significant proportion (15/19, and most of the serotypes isolated (S. Typhimurium, S. Infantis, S. Newport and S. Enteritidis were among the 10 non-typhoidal Salmonella serotypes that are most often responsible for infections in Europe, including Poland. Y. enterococlitica was detected in the smallest percentage of animals, but 60% of strains among the isolates tested possessed the ail gene, which is responsible for attachment and invasion. Potentially pathogenic Listeria species were isolated from approx. 5% of the animals. The presence of all tested virulence genes was shown in 35% of L. monocytogenes strains, while in the case of the other strains, the genes occurred in varying numbers and configurations. The presence of the inlA, inlC, hlyA, and iap genes was noted in all strains, whereas the genes encoding PI-PLC, actin, and internalin Imo2821 were present in varying percentages (from 80% to 55%. S. aureus was obtained from 40 individuals. Most isolates possessed the hla, hld (95% for each, and hlb (32.5% genes encoding hemolysins as well as the gene encoding leukotoxin lukED (70%. In a similar percentage of strains (77.5%, the presence of at least one gene encoding enterotoxin was found, with 12

  20. Free-Living Species of Carnivorous Mammals in Poland: Red Fox, Beech Marten, and Raccoon as a Potential Reservoir of Salmonella, Yersinia, Listeria spp. and Coagulase-Positive Staphylococcus.

    Science.gov (United States)

    Nowakiewicz, Aneta; Zięba, Przemysław; Ziółkowska, Grażyna; Gnat, Sebastian; Muszyńska, Marta; Tomczuk, Krzysztof; Majer Dziedzic, Barbara; Ulbrych, Łukasz; Trościańczyk, Aleksandra

    2016-01-01

    The objective of the study was to examine a population of free-living carnivorous mammals most commonly found in Poland (red fox, beech marten, and raccoon) for the occurrence of bacteria that are potentially pathogenic for humans and other animal species and to determine their virulence potential (the presence of selected virulence genes). From the total pool of isolates obtained (n = 328), we selected 90 belonging to species that pose the greatest potential threat to human health: Salmonella spp. (n = 19; 4.51%), Yersinia enterocolitica (n = 10; 2.37%), Listeria monocytogenes and L. ivanovii (n = 21), and Staphylococcus aureus (n = 40; 9.5%). The Salmonella spp. isolates represented three different subspecies; S. enterica subsp. enterica accounted for a significant proportion (15/19), and most of the serotypes isolated (S. Typhimurium, S. Infantis, S. Newport and S. Enteritidis) were among the 10 non-typhoidal Salmonella serotypes that are most often responsible for infections in Europe, including Poland. Y. enterococlitica was detected in the smallest percentage of animals, but 60% of strains among the isolates tested possessed the ail gene, which is responsible for attachment and invasion. Potentially pathogenic Listeria species were isolated from approx. 5% of the animals. The presence of all tested virulence genes was shown in 35% of L. monocytogenes strains, while in the case of the other strains, the genes occurred in varying numbers and configurations. The presence of the inlA, inlC, hlyA, and iap genes was noted in all strains, whereas the genes encoding PI-PLC, actin, and internalin Imo2821 were present in varying percentages (from 80% to 55%). S. aureus was obtained from 40 individuals. Most isolates possessed the hla, hld (95% for each), and hlb (32.5%) genes encoding hemolysins as well as the gene encoding leukotoxin lukED (70%). In a similar percentage of strains (77.5%), the presence of at least one gene encoding enterotoxin was found, with 12

  1. Benign positional vertigo - aftercare

    Science.gov (United States)

    Vertigo - positional - aftercare; Benign paroxysmal positional vertigo - aftercare; BPPV - aftercare; Dizziness - positional vertigo ... Your health care provider may have treated your vertigo with the Epley maneuver . These are head movements ...

  2. Mallinckrodt's position on SLR production

    International Nuclear Information System (INIS)

    Lee, T.L.

    1985-01-01

    The potential of the short-lived radionuclides used in nuclear medicine applications and Mallinckrodt's position are discussed. An update of Mallinckrodt's activities and future plans are also given. The keen interest of Mallinckrodt, Inc., in the application and development of short-lived radionuclides for medical use is stressed, as well as envisioned innovations

  3. A simple and efficient method for generating Nurr1-positive neuronal stem cells from human wisdom teeth (tNSC) and the potential of tNSC for stroke therapy.

    Science.gov (United States)

    Yang, Kuo-Liang; Chen, Mei-Fang; Liao, Chia-Hsin; Pang, Cheng-Yoong; Lin, Py-Yu

    2009-01-01

    We have isolated human neuronal stem cells from exfoliated third molars (wisdom teeth) using a simple and efficient method. The cultured neuronal stem cells (designated tNSC) expressed embryonic and adult stem cell markers, markers for chemotatic factor and its corresponding ligand, as well as neuron proteins. The tNSC expressed genes of Nurr1, NF-M and nestin. They were used to treat middle cerebral artery occlusion (MCAO) surgery-inflicted Sprague-Dawley (SD) rats to assess their therapeutic potential for stroke therapy. For each tNSC cell line, a normal human impacted wisdom tooth was collected from a donor with consent. The tooth was cleaned thoroughly with normal saline. The molar was vigorously shaken or vortexed for 30 min in a 50-mL conical tube with 15-20mL normal saline. The mixture of dental pulp was collected by centrifugation and cultured in a 25-cm(2) tissue culture flask with 4-5mL Medium 199 supplemented with 5-10% fetal calf serum. The tNSC harvested from tissue culture, at a concentration of 1-2x10(5), were suspended in 3 microL saline solution and injected into the right dorsolateral striatum of experimental animals inflicted with MCAO. Behavioral measurements of the tNSC-treated SD rats showed a significant recovery from neurologic dysfunction after MCAO treatment. In contrast, a sham group of SD rats failed to recover from the surgery. Immunohistochemistry analysis of brain sections of the tNSC-treated SD rats showed survival of the transplanted cells. These results suggest that adult neuronal stem cells may be procured from third molars, and tNSC thus cultivated have potential for treatment of stroke-inflicted rats.

  4. Can a Positive Allosteric Modulation of GABAergic Receptors Improve Motor Symptoms in Patients with Parkinson’s Disease? The Potential Role of Zolpidem in the Treatment of Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Antonio Daniele

    2016-01-01

    Full Text Available At present, patients with advanced Parkinson’s disease (PD are unsatisfactorily controlled by currently used anti-Parkinsonian dopaminergic drugs. Various studies suggest that therapeutic strategies based on nondopaminergic drugs might be helpful in PD. Zolpidem, an imidazopyridine widely used as sleep inducer, shows high affinity only for GABAA receptors containing the α-1 subunit and facilitates GABAergic neurotransmission through a positive allosteric modulation of GABAA receptors. Various observations, although preliminary, consistently suggest that in PD patients zolpidem may induce beneficial (and sometimes remarkable effects on motor symptoms even after single doses and may also improve dyskinesias. Since a high density of zolpidem binding sites is in the two main output structures of the basal ganglia which are abnormally overactive in PD (internal globus pallidus, GPi, and substantia nigra pars reticulata, SNr, it was hypothesized that in PD patients zolpidem may induce through GABAA receptors an inhibition of GPi and SNr (and, possibly, of the subthalamic nucleus also, resulting in an increased activity of motor cortical areas (such as supplementary motor area, which may give rise to improvement of motor symptoms of PD. Randomized clinical trials are needed in order to assess the efficacy, safety, and tolerability of zolpidem in treating motor symptoms of PD.

  5. Estudo do conversor zeta em condução simultânea dos semicondutores aplicada à alimentação de LEDs de potência

    OpenAIRE

    Pedrollo, Guilherme Rodrigues

    2015-01-01

    Este trabalho propõe a operação do conversor Zeta no modo de condução simultânea (MCS), cujo interesse reside na capacidade de implementação de um pré-regulador do fator de potência (PFP) ideal empregando apenas um laço de realimentação. Quando o conversor trabalha no MCS, a chave principal e o diodo conduzem simultaneamente em um de seus estágios de operação. Neste modo de condução, o conversor estático apresenta características de ambos os modos de condução conhecidos até agora: o modo de c...

  6. Ethanol potentiates the genotoxicity of the food-derived mammary carcinogen PhIP in human estrogen receptor-positive mammary cells: mechanistic support for lifestyle factors (cooked red meat and ethanol) associated with mammary cancer.

    Science.gov (United States)

    Malik, Durr-E-Shahwar; David, Rhiannon M; Gooderham, Nigel J

    2018-04-01

    Consumption of cooked/processed meat and ethanol are lifestyle risk factors in the aetiology of breast cancer. Cooking meat generates heterocyclic amines such as 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Epidemiology, mechanistic and animal studies indicate that PhIP is a mammary carcinogen that could be causally linked to breast cancer incidence; PhIP is DNA damaging, mutagenic and oestrogenic. PhIP toxicity involves cytochrome P450 (CYP1 family)-mediated metabolic activation to DNA-damaging species, and transcriptional responses through Aryl hydrocarbon receptor (AhR) and estrogen-receptor-α (ER-α). Ethanol consumption is a modifiable lifestyle factor strongly associated with breast cancer risk. Ethanol toxicity involves alcohol dehydrogenase metabolism to reactive acetaldehyde, and is also a substrate for CYP2E1, which when uncoupled generates reactive oxygen species (ROS) and DNA damage. Here, using human mammary cells that differ in estrogen-receptor status, we explore genotoxicity of PhIP and ethanol and mechanisms behind this toxicity. Treatment with PhIP (10 -7 -10 -4 M) significantly induced genotoxicity (micronuclei formation) preferentially in ER-α positive human mammary cell lines (MCF-7, ER-α+) compared to MDA-MB-231 (ER-α-) cells. PhIP-induced CYP1A2 in both cell lines but CYP1B1 was selectively induced in ER-α(+) cells. ER-α inhibition in MCF-7 cells attenuated PhIP-mediated micronuclei formation and CYP1B1 induction. PhIP-induced CYP2E1 and ROS via ER-α-STAT-3 pathway, but only in ER-α (+) MCF-7 cells. Importantly, simultaneous treatments of physiological concentrations ethanol (10 -3 -10 -1 M) with PhIP (10 -7 -10 -4 M) increased oxidative stress and genotoxicity in MCF-7 cells, compared to the individual chemicals. Collectively, these data offer a mechanistic basis for the increased risk of breast cancer associated with dietary cooked meat and ethanol lifestyle choices.

  7. A different perspective: introducing positive criminology.

    Science.gov (United States)

    Ronel, Natti; Elisha, Ety

    2011-04-01

    Positive criminology is a new conceptual perspective of criminology, encompassing several theories and models. Positive criminology refers to a focus on individuals' encounters with forces and influences that are experienced as positive, which distance them from deviance and crime, whether by means of formal and informal therapy programs and interventions, such as self-help groups; through emphasis of positive social elements, such as exposure to goodness, social acceptance, and reintegrative shaming; or based on positive personal traits, such as resilience and coherence. The perspective of positive criminology broadens that of traditional criminology, which focuses mainly on understanding the factors and processes that lead individuals and groups to what is defined as deviant and criminal behavior. Positive criminology is implemented in treatment and rehabilitation of individuals and groups that have demonstrated deviant and criminal behavior, by emphasizing positive experiences that may potentially prevent or discourage continued criminal behavior. Positive criminology is also expressed in prevention based on a positive approach.

  8. Multi-technology positioning

    CERN Document Server

    Lohan, Elena-Simona; Wymeersch, Henk; Seco-Granados, Gonzalo; Nykänen, Ossi

    2017-01-01

    This book provides an overview of positioning technologies, applications and services in a format accessible to a wide variety of readers. Readers who have always wanted to understand how satellite-based positioning, wireless network positioning, inertial navigation, and their combinations work will find great value in this book. Readers will also learn about the advantages and disadvantages of different positioning methods, their limitations and challenges. Cognitive positioning, adding the brain to determine which technologies to use at device runtime, is introduced as well. Coverage also includes the use of position information for Location Based Services (LBS), as well as context-aware positioning services, designed for better user experience. • Brings understanding of positioning technology to readers from a variety of disciplines • Reviews multiple techniques, providing insight on the pros, cons and challenges related to each • Designed to be a tutorial on basic principles, avoiding unnecessary de...

  9. Navicular bone position determined by positional MRI

    DEFF Research Database (Denmark)

    Hansen, Philip; Johannsen, Finn E; Hangaard, Stine

    2016-01-01

    -scanner). Scanning was performed in supine and standing position, respectively. Two radiologists evaluated the images in a blinded manner. Reliability and agreement were assessed by calculation of intraclass correlation coefficient (ICC) and 95 % limits of agreement as a percentage of the mean (LOA%). RESULTS...

  10. Positive uncertainty: The benefit of the doubt in advertising

    NARCIS (Netherlands)

    Ketelaar, P.E.; Riet, J.P. van 't; Thorbjornsen, H.; Buijzen, M.A.

    2018-01-01

    Positive uncertainty refers to uncertainty surrounding an anticipated positive outcome. It provides consumers with the opportunity to imagine and speculate on a product's or experience's potentially positive characteristics. Research has shown that when uncertainty is associated with something

  11. Pretty Easy Pervasive Positioning

    DEFF Research Database (Denmark)

    Hansen, Rene; Wind, Rico; Jensen, Christian Søndergaard

    2009-01-01

    With the increasing availability of positioning based on GPS, Wi-Fi, and cellular technologies and the proliferation of mobile devices with GPS, Wi-Fi and cellular connectivity, ubiquitous positioning is becoming a reality. While offerings by companies such as Google, Skyhook, and Spotigo render...... positioning possible in outdoor settings, including urban environments with limited GPS coverage, they remain unable to offer accurate indoor positioning. We will demonstrate a software infrastructure that makes it easy for anybody to build support for accurate Wi-Fi based positioning in buildings. All...... that is needed is a building with Wi-Fi coverage, access to the building, a floor plan of the building, and a Wi-Fi enabled device. Specifically, we will explain the software infrastructure and the steps that must be completed to obtain support for positioning. And we will demonstrate the positioning obtained...

  12. Doripenem: position in clinical practice.

    Science.gov (United States)

    Dedhia, Harakh V; McKnight, Richard

    2009-06-01

    Doripenem is a novel carbapenem with a broad spectrum of activity against Gram-positive pathogens, anerobes and Gram-negative bacteria, including Pseudomonas aeruginosa. Doripenem exhibits rapid bactericidal activity with two- to fourfold lower MIC values for Gram-negative bacteria, compared with other carbapenems such as imipenem. Doripenem is approved for the treatment of complicated intra-abdominal infection and urinary tract infections. It has been successfully used in the treatment of nosocomial and ventilator-associated pneumonia. It has a potential to be the drug of choice for these conditions. This evaluation focuses on the general review of the drug, including mechanisms of resistance, clinical efficacy and the position of doripenem in clinical practice. Stability against numerous beta-lactamases, low adverse-event potential and more potent in vitro and possibly in vivo activity against P. aeruginosa and Acinetobacter baumanni compared with existing carbapenems are attractive features.

  13. Synthesis, characterization, and cytocompatibility of potential cockle shell aragonite nanocrystals for osteoporosis therapy and hormonal delivery

    Directory of Open Access Journals (Sweden)

    Jaji AZ

    2017-01-01

    Full Text Available Alhaji Zubair Jaji,1,2 Md Zuki Bin Abu Bakar,1,3 Rozi Mahmud,4 Mohamad Yusof Loqman,5 Mohamad Noor Mohamad Hezmee,1 Tijani Isa,3 Fu Wenliang,3 Nahidah Ibrahim Hammadi1 1Department of Veterinary Pre-Clinical Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 2Department of Veterinary Anatomy, Faculty of Veterinary Medicine, University of Ilorin, Ilorin, Kwara, Nigeria; 3Molecular Biomedicine Laboratory, Institute of Bioscience, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 4Department of Imaging, Faculty of Medicine and Health Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 5Department of Companion Animal Medicine and Surgery, Universiti Putra Malaysia, Serdang, Selangor, Malaysia Abstract: Calcium carbonate is a porous inorganic nanomaterial with huge potential in biomedical applications and controlled drug delivery. This study aimed at evaluating the physicochemical properties and in vitro efficacy and safety of cockle shell aragonite calcium carbonate nanocrystals (ANC as a potential therapeutic and hormonal delivery vehicle for osteoporosis management. Free and human recombinant parathyroid hormone 1-34 (PTH 1-34-loaded cockle shell aragonite calcium carbonate nanocrystals (PTH-ANC were synthesized and evaluated using standard procedures. Transmission electron microscopy and field emission scanning electron microscopy results demonstrated highly homogenized spherical-shaped aragonite nanocrystals of 30±5 nm diameter. PTH-ANC had a zeta potential of −27.6 ± 8.9 mV. The encapsulation efficiency of the formulation was found to be directly proportional to the concentrations of the drug fed. The X-ray diffraction patterns revealed strong crystallizations with no positional change of peaks before and after PTH-ANC synthesis. Fourier transform infrared spectroscopy demonstrated no detectable interactions between micron-sized aragonite and surfactant at molecular level. PTH-ANC formulation was stabilized

  14. TIMP-2 gene transfer by positively charged PEG-lated monosized polycationic carrier to smooth muscle cells

    Energy Technology Data Exchange (ETDEWEB)

    Lacin, Nelisa, E-mail: melisalacin@yahoo.com [Mersin University, Advanced Technology Education, Research and Application Center (Turkey); Utkan, Gueldem [TUBITAK MAM, Enzyme and Fermentation Technology Laboratory, Genetic Engineering and Biotechnology Institute (Turkey); Kutsal, Tuelin [Hacettepe University, Chemical Engineering Department and Bioengineering Division (Turkey); Dedeoglu, Bala Guer; Yulug, Is Latin-Small-Letter-Dotless-I k G. [Bilkent University, Department of Molecular Biology and Genetics, Faculty of Science (Turkey); Piskin, Erhan [Hacettepe University, Chemical Engineering Department and Bioengineering Division and Center for Bioengineering-Biyomedtek (Turkey)

    2012-02-15

    Remodeling of the extracellular matrix resulting from increased secretion of metalloproteinase enzymes is implicated in restenosis following balloon angioplasty. Matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases play an essential role in both normal and pathological extracellular matrix degradation. Tissue inhibitor of matrix metalloproteinase-2 is the most extensively studied tissue inhibitor of metalloproteinases in myocardial tissue in animal models and clinical examples of cardiac disease; therefore it is selected for this study. Gene transfer of tissue inhibitor of matrix metalloproteinase-2 may have a therapeutic potential by inhibition of matrix metalloproteinase activity. We have used PEG-lated nanoparticles poly(St/PEG-EEM/DMAPM) which were synthesized previously in our laboratory. The nanoparticles, with an average size of 77.6 {+-} 2.05 nm with a zeta potential of +64. 4 {+-} 1.14 mV and 201.9 {+-} 1.83 nm with +54.2 {+-} 0.77 mV were used in the transfection studies. Zeta Potential values and size of polyplex were appropriate for an effective transfection. TIMP-2 expression was detected by western blotting. Increased protein level in smooth muscle cells according to non-transfected smooth muscle cells confirms the successful delivery and expression of the tissue inhibitor of matrix metalloproteinase-2 gene with the non-viral vector transfection approach.

  15. TIMP-2 gene transfer by positively charged PEG-lated monosized polycationic carrier to smooth muscle cells

    Science.gov (United States)

    Laçin, Nelisa; Utkan, Güldem; Kutsal, Tülin; Dedeoğlu, Bala Gür; Yuluğ, Işık G.; Pişkin, Erhan

    2012-02-01

    Remodeling of the extracellular matrix resulting from increased secretion of metalloproteinase enzymes is implicated in restenosis following balloon angioplasty. Matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases play an essential role in both normal and pathological extracellular matrix degradation. Tissue inhibitor of matrix metalloproteinase-2 is the most extensively studied tissue inhibitor of metalloproteinases in myocardial tissue in animal models and clinical examples of cardiac disease; therefore it is selected for this study. Gene transfer of tissue inhibitor of matrix metalloproteinase-2 may have a therapeutic potential by inhibition of matrix metalloproteinase activity. We have used PEG-lated nanoparticles poly(St/PEG-EEM/DMAPM) which were synthesized previously in our laboratory. The nanoparticles, with an average size of 77.6 ± 2.05 nm with a zeta potential of +64. 4 ± 1.14 mV and 201.9 ± 1.83 nm with +54.2 ± 0.77 mV were used in the transfection studies. Zeta Potential values and size of polyplex were appropriate for an effective transfection. TIMP-2 expression was detected by western blotting. Increased protein level in smooth muscle cells according to non-transfected smooth muscle cells confirms the successful delivery and expression of the tissue inhibitor of matrix metalloproteinase-2 gene with the non-viral vector transfection approach.

  16. Mesomeric Effects of Graphene Modified with Diazonium Salts: Substituent Type and Position Influence its Properties.

    Science.gov (United States)

    Bouša, Daniel; Jankovský, Ondřej; Sedmidubský, David; Luxa, Jan; Šturala, Jiří; Pumera, Martin; Sofer, Zdeněk

    2015-12-01

    In the last decade, graphene and graphene derivatives have become some of the most intensively studied materials. Tuning of the electronic and electrochemical properties of graphene is of paramount importance. In this study, six diazonium-modified graphenes containing different functional groups according to the diazonium salt precursor were investigated. These diazonium moieties have a strong mesomeric (resonance) effect and act as either electron-donating or -withdrawing species. Different graphene precursors, such as thermally and chemically reduced graphenes were studied. All the products were characterized in detail by elemental combustion analysis, FTIR spectroscopy, Raman spectroscopy, high-resolution X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. Resistivity and zeta potential measurements were consistent with theoretical (DFT) calculations. The results show that chemical modification of graphene by diazotation strongly influences its properties, creating a huge application potential in microelectronics, energy storage and conversion devices, and electrocatalysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Collagen type I from bovine bone. Effect of animal age, bone anatomy and drying methodology on extraction yield, self-assembly, thermal behaviour and electrokinetic potential.

    Science.gov (United States)

    Ferraro, Vincenza; Gaillard-Martinie, Brigitte; Sayd, Thierry; Chambon, Christophe; Anton, Marc; Santé-Lhoutellier, Véronique

    2017-04-01

    Natural collagen is easily available from animal tissues such as bones. Main limitations reported in the use of natural collagen are heterogeneity and loss of integrity during recovery. However, its natural complexity, functionality and bioactivity still remain to be achieved through synthetic and recombinant ways. Variability of physicochemical properties of collagen extracted from bovine bone by acetic acid was then investigated taking into account endogenous and exogenous factors. Endogenous: bovine's bones age (4 and 7 years) and anatomy (femur and tibia); exogenous: thermal treatments (spray-drying and lyophilisation). Scanning electron microscopy, spectroscopy (EDS, FTIR, UV/Vis and CD), differential scanning calorimetry (DSC), centesimal composition, mass spectrometry, amino acids and zeta-potential analysis were used for the purpose. Age correlated negatively with yield of recovery and positively with minerals and proteoglycans content. Comparing the anatomy, higher yields were found for tibias, and higher stability of tibias collagen in solution was noticed. Whatever the age and the anatomy, collagens were able to renature and to self-assemble into tri-dimensional structures. Nonetheless thermal stability and kinetics of renaturation were different. Variability of natural collagen with bone age and anatomy, and drying methodology, may be a crucial advantage to conceive tailor-made applications in either the biological or technical sector. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Positive criminology in practice.

    Science.gov (United States)

    Ronel, Natti; Segev, Dana

    2014-11-01

    The discourse regarding offender rehabilitation has been criticized by various scholars who have claimed that reducing negative causes and managing risk will not automatically prompt positive human development and elements that are associated with desistance. Positive criminology is an innovative concept that challenges the common preoccupation with negative elements, by placing emphasis on human encounters and forces of inclusion that are experienced positively by target individuals and that can promote crime desistance. However, as the concept is relatively new, there are still no guiding principles for the practice of positive criminology that could direct research and the criminal justice system. This article attempts to fill that gap by providing principles that could be practiced by criminal justice personnel and examples of different interventions that reflect positive criminology. The article also provides ideological explanations for adopting the concept of positive criminology in practice. © The Author(s) 2013.

  19. Cadastral Database Positional Accuracy Improvement

    Science.gov (United States)

    Hashim, N. M.; Omar, A. H.; Ramli, S. N. M.; Omar, K. M.; Din, N.

    2017-10-01

    Positional Accuracy Improvement (PAI) is the refining process of the geometry feature in a geospatial dataset to improve its actual position. This actual position relates to the absolute position in specific coordinate system and the relation to the neighborhood features. With the growth of spatial based technology especially Geographical Information System (GIS) and Global Navigation Satellite System (GNSS), the PAI campaign is inevitable especially to the legacy cadastral database. Integration of legacy dataset and higher accuracy dataset like GNSS observation is a potential solution for improving the legacy dataset. However, by merely integrating both datasets will lead to a distortion of the relative geometry. The improved dataset should be further treated to minimize inherent errors and fitting to the new accurate dataset. The main focus of this study is to describe a method of angular based Least Square Adjustment (LSA) for PAI process of legacy dataset. The existing high accuracy dataset known as National Digital Cadastral Database (NDCDB) is then used as bench mark to validate the results. It was found that the propose technique is highly possible for positional accuracy improvement of legacy spatial datasets.

  20. Potential Positive Effects of Pesticides Application on (Walker (Lepidoptera: Insecta

    Directory of Open Access Journals (Sweden)

    Guo-Qing Yang

    2014-01-01

    Full Text Available In China, the pink stem borer (PSB Sesamia inferens (Walker (Lepidoptera: Noctuidae has become a rice pest in some rice-producing regions. The cause of this shift from secondary to major pest is unknown. The major purpose of this study was to examine the effect of five commonly used pesticides in rice fields on reproduction of PSB and on biochemical substances of rice plants. The results showed that the weight of pupae developed from 1st instar larvae treated with 2 mg/L triazophos and the number of eggs laid by emerged females from the treatment were significantly greater than those of the control, increasing by 26.2% and 47%, respectively. In addition, a nontarget insecticide, pymetrozine 100 mg/L, and a target insecticide, chlorantraniliprole 2 mg/L, stimulated reproduction of PSB. Biochemical measurement showed that foliar sprays of these pesticides resulted in significant reductions of contents of resistant substances, flavonoids and phenolic acids, in rice plants. For example, flavonoids and phenolic acids of rice plants treated with triazophos reduced by 48.5% and 22.4%, respectively, compared to the control. Therefore, we predicted that the application of some pesticides, eg triazophos and chlorantraniliprole, may be the cause of the increase in the population numbers of PSB in rice fields.

  1. T cell receptor zeta allows stable expression of receptors containing the CD3gamma leucine-based receptor-sorting motif

    DEFF Research Database (Denmark)

    Dietrich, J; Geisler, C

    1998-01-01

    The leucine-based motif in the T cell receptor (TCR) subunit CD3gamma constitutes a strong internalization signal. In fully assembled TCR this motif is inactive unless phosphorylated. In contrast, the motif is constitutively active in CD4/CD3gamma and Tac/CD3gamma chimeras independently of phosph......The leucine-based motif in the T cell receptor (TCR) subunit CD3gamma constitutes a strong internalization signal. In fully assembled TCR this motif is inactive unless phosphorylated. In contrast, the motif is constitutively active in CD4/CD3gamma and Tac/CD3gamma chimeras independently...... of phosphorylation and leads to rapid internalization and sorting of these chimeras to lysosomal degradation. Because the TCRzeta chain rescues incomplete TCR complexes from lysosomal degradation and allows stable surface expression of fully assembled TCR, we addressed the question whether TCRzeta has the potential...... to mask the CD3gamma leucine-based motif. By studying CD4/CD3gamma and CD16/CD3gamma chimeras, we found that CD16/CD3gamma chimeras associated with TCRzeta. The CD16/CD3gamma-TCRzeta complexes were stably expressed at the cell surface and had a low spontaneous internalization rate, indicating...

  2. Scalability Optimization of Seamless Positioning Service

    Directory of Open Access Journals (Sweden)

    Juraj Machaj

    2016-01-01

    Full Text Available Recently positioning services are getting more attention not only within research community but also from service providers. From the service providers point of view positioning service that will be able to work seamlessly in all environments, for example, indoor, dense urban, and rural, has a huge potential to open new markets. However, such system does not only need to provide accurate position estimates but have to be scalable and resistant to fake positioning requests. In the previous works we have proposed a modular system, which is able to provide seamless positioning in various environments. The system automatically selects optimal positioning module based on available radio signals. The system currently consists of three positioning modules—GPS, GSM based positioning, and Wi-Fi based positioning. In this paper we will propose algorithm which will reduce time needed for position estimation and thus allow higher scalability of the modular system and thus allow providing positioning services to higher amount of users. Such improvement is extremely important, for real world application where large number of users will require position estimates, since positioning error is affected by response time of the positioning server.

  3. Positively charged TiO2 particles in non-polar system for electrophoretic display

    International Nuclear Information System (INIS)

    Chang, Young Seon

    2005-02-01

    Electrophoretic display uses a technique called electrophoresis to represent images and letters electronically with electronic ink. Although it has good characteristics such as wide viewing angle, high contrast ratio and extremely low power consumption, there are still several issues to be resolved to improve its performances. Higher mobility and stability of the ink particles are the most important issues among them. In this study, TiO 2 particles coated with acrylamide were found to be effective ink particles that satisfy higher mobility and stability. The TiO 2 particles coated with 5∼40% acrylamide were prepared by dispersion polymerization using monomers of methyl methacrylate (MMA) and acrylamide. The TiO 2 particles coated with acrylamide were dispersed in isopar-G with sorbitan esters such as span 20, span 80 and span 85. The size of the TiO 2 particles were changed from 200±150 nm to 350∼500 nm by the coating process. The morphology of coated particles was observed using a transmission electron microscope (TEM) and thermogravimetric analysis (TGA). From the TGA results, the weight fraction of TiO 2 and polymer in coated particle were calculated. From the zeta potential measurement, it was shown that as acrylamide concentration was increased from 5% to 30%, zeta potential of the coated TiO 2 particles was increased from 50mV to about 230mV. The zeta potential of the coated TiO 2 particles with 40% acrylamide was decreased to 50mV. As a stabilizer, span 85 was the most effective surfactant to improve stability of the TiO 2 particles coated with acrylamide among used surfactants in this study. Span 85 showed best stability in the storage test with TiO 2 particles coated with 10% acrylamide. The mobility of TiO 2 particles coated with acrylamide with span 85 in dye solution (Oil Blue-N dissolved in isopar-G) were measured by ITO cell test. The mobility of TiO 2 particles coated with 10∼30% acrylamide was over 600μm 2 /Vs while the mobility of TiO 2

  4. Den positive psykologis metoder

    DEFF Research Database (Denmark)

    Andersen, Frans Ørsted; Mørck, Line Lerche; Nissen, Poul Erik

    En antologi der giver en introduktion til en række af de metoder der anvendes til forskning, assessment, test, udviklingsarbejde og intervention indenfor den positive psykologi.......En antologi der giver en introduktion til en række af de metoder der anvendes til forskning, assessment, test, udviklingsarbejde og intervention indenfor den positive psykologi....

  5. Modern management positions

    Directory of Open Access Journals (Sweden)

    Jovanović Petar M.

    2015-01-01

    Full Text Available In this paper we analyze contemporary managerial positions such as program manager, project portfolio manager, crisis manager and others. The idea is to promote managerial positions in Serbia, which is quite unjustifiably undervalued, primarily because of the lack of knowledge in the field of management and other issues related to management education.

  6. Positioning and locking apparatus

    Science.gov (United States)

    Hayward, M.L.; Harper, W.H.

    1985-06-19

    A positioning and locking apparatus including a fixture having a rotatable torque ring provided with a plurality of cam segments for automatically guiding a container into a desired location within the fixture. Rotation of the ring turns the container into a final position in pressure sealing relation against a hatch member.

  7. Positioning health professional identity

    DEFF Research Database (Denmark)

    Lund, Ole; Krogh Christensen, Mette; Mørcke, Anne Mette

    2017-01-01

    Drawing on positioning theory, the purpose of this paper is to characterize the activities and positions of students and supervisors at workplaces and on-campus skills training sites across the higher health professional educations of medicine, sports science, and nursing. Furthermore, the study ...... explored the impact of work-based learning (WBL) and skills training on students’ personal professional identity development....

  8. Phantom position dependence

    International Nuclear Information System (INIS)

    Thorson, M.R.; Endres, G.W.R.

    1981-01-01

    Sensitivity of the Hanford dosimeter response to its position relative to the phantom and the neutron source has always been recognized. A thorough investigation was performed to quantify dosimeter response according to: (a) dosimeter position on phantom, (b) dosimeter distance from phantom, and (c) angular relationship of dosimeter relative to neutron source and phantom. Results were obtained for neutron irradiation at several different energies

  9. Position display device

    International Nuclear Information System (INIS)

    Nishizawa, Yukio.

    1974-01-01

    Object: To provide a device capable of easily and quickly reading mutual mounting relations of control bodies such as control rods mounted on a nuclear reactor and positions to which the control bodies are driven. Structure: A scanning circuit is provided to scan positions of controllably mounted control bodies such as control rods. Values detected by scanning the positions are converted into character signals according to the values and converted into preranked color signals. The character signals and color signals are stored in a memory circuit by synchronous signals in synchronism with the scanning in the scanning circuit. Outputs of the memory circuit are displayed by a display unit such as a color Braun tube in accordance with the synchronous signals to provide color representations according to positions to which control bodies are driven in the same positional relation as the mounting of the control bodies. (Kamimura, M.)

  10. Review of Positional Nystagmus

    Directory of Open Access Journals (Sweden)

    José Ignacio BENITO-OREJAS

    2018-01-01

    Full Text Available Introduction and objective: Any change of position of the head (dynamic or static can trigger a nystagmus or increase the spontaneous. This nystagmus we call it positional. We intend to review in this chapter its definition, clinical features, etiology and the way of exploring it. Method: narrative review. Results: Positional vertigo is the most frequent vestibular disorder, and most of the times of peripheral cause. Characteristics of nystagmus or its association with other neurological symptoms are sufficient grounds to request a magnetic resonance, which will provide additional information on very few occasions. Discussion: The study of the positional nystagmus as a procedure to rule out central pathology has lost much of its relevance. Signs that Nylén defined mixed findings peripheral and central, making complex classification. Conclusion: Regardless of how to bring the patient change position (very slow or fast, if it appears an atypical nystagmus should rule out a central origin.

  11. POSITIONING STRATEGIES DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    Shakhshir Ghassan

    2014-07-01

    Full Text Available The positioning strategy has suffered serious changes in the last few decades, being influenced by the rapid development of competition and the growing focus on specific traits belonging to the market, to the consumer or to the product. The purpose of this paper is to present the developments of theoretical positioning strategies and the orientation from more simple, product oriented strategies, to ones more oriented towards the client and with a briefer period of time. The world is moving in a much faster pace than in the past, thanks to communication development so companies are obliged to adopt more specific strategies in order for them to be effective. This essay represents a literary review presenting a documentary research within the scientific articles and strategy and positioning books. The paper begins with the analysis of company strategies and the marketing strategies in general. The first author to group the product positioning strategies is Porter with his three generic strategies. Following the development of brands and because of the lack of competitiveness in the simple generic positioning strategies, this paper has also presented the newer positioning strategies proposed by Kotler, Treacy & Wiersema, and also more complex ones such as Bowman's Strategy Clock and Blankson and Kalafatis positioning strategy based on the type of the consumer. The fast expansion of local brands in all categories has led to mistakes in positioning strategies, categories also presented in the current essay. The results of this study show that new positioning strategies are more and more based on the consumer and market segments and on the product specification - which have also evolved in the last decades. Adaptability to fast changes in the competitive market will represent the future positioning strategies.

  12. CONTEMPLATIVE POSITIVE PSYCHOLOGY: INTRODUCING MINDFULNESS INTO POSITIVE PSYCHOLOGY

    Directory of Open Access Journals (Sweden)

    Ausiàs Cebolla

    2017-01-01

    Full Text Available Although mindfulness is included in many positive psychology manuals as a “positive” technique, the implications of its use have scarcely been developed and the relationship between mindfulness and human well-being has barely been researched. Analyzing the main strengths of the two fields, the possibilities for their integration and the potential contradictions between their messages is essential in order to establish connections. Mindfulness is more than a meditation technique. It has implicit within it a set of values and ethical conditions that coincide to a great extent with the proposed assumptions from positive psychology, such as the development of kindness, compassion, and positive emotions. The aim of this paper is to present, on the one hand, the commonalities and similarities, and on the other, the differences between mindfulness and positive psychology. We also present the main studies that have investigated the role of mindfulness and contemplative practices on human well-being. Finally future research will be discussed and intervention suggested in order to bring the two proposals together.

  13. Positional Concerns and Institutions

    DEFF Research Database (Denmark)

    Landes, Xavier

    2013-01-01

    that invoking envy or subjective well-being is not fully satisfying for regulating positional concerns. More compelling reasons seem, in complement with efficiency, to be related to considerations for equality. In other words, if institutions could have strong reasons to pay attention to and regulate positional...... their implications for economics, positional concerns imply important normative dimensions. There have been presumed to be a symptom of envy, reduce people’s happiness, and create problems of social interaction or economic inefficiencies. Individuals are, for instance, prone to pick states of the world that improve...... concerns, it would be in virtue of their impact on the social product and individuals’ conditions of living....

  14. False Positives in Exoplanet Detection

    Science.gov (United States)

    Leuquire, Jacob; Kasper, David; Jang-Condell, Hannah; Kar, Aman; Sorber, Rebecca; Suhaimi, Afiq; KELT (Kilodegree Extremely Little Telescope)

    2018-06-01

    Our team at the University of Wyoming uses a 0.6 m telescope at RBO (Red Buttes Observatory) to help confirm results on potential exoplanet candidates from low resolution, wide field surveys shared by the KELT (Kilodegree Extremely Little Telescope) team. False positives are common in this work. We carry out transit photometry, and this method comes with special types of false positives. The most common false positive seen at the confirmation level is an EB (eclipsing binary). Low resolution images are great in detecting multiple sources for photometric dips in light curves, but they lack the precision to decipher single targets at an accurate level. For example, target star KC18C030621 needed RBO’s photometric precision to determine there was a nearby EB causing exoplanet type light curves. Identifying false positives with our telescope is important work because it helps eliminate the waste of time taken by more expensive telescopes trying to rule out negative candidate stars. It also furthers the identification of other types of photometric events, like eclipsing binaries, so they can be studied on their own.

  15. Stress Management: Positive Thinking

    Science.gov (United States)

    Healthy Lifestyle Stress management Positive thinking helps with stress management and can even improve your health. Practice overcoming negative self-talk ... with optimism is a key part of effective stress management. And effective stress management is associated with ...

  16. Den positive psykologis metoder

    DEFF Research Database (Denmark)

    Bogen introducerer til de mange metoder, som anvendes i positiv psykologi. dette sker ud fra en reflekteret tilgang, der ligeledes rummer bidrag fra kritisk psykologi med det formål at nuancere den positive psykologis forståelser...

  17. Clinical Positioning Space

    DEFF Research Database (Denmark)

    Williams, Lars Peter Hedegaard; Christensen, Mette Krogh; Rytter, Carsten

    2014-01-01

    In this article, we present a case study of residents’ clinical experiences and communication in outpatient oncology consultations. We apply positioning theory, a dynamic alternative to role theory, to investigate how oncology residents and patients situate themselves as persons with rights...... and duties. Drawing from seven qualitative interviews and six days of observation, we investigate the residents’ social positioning and their conversations with patients or supervisors. Our focus is on how (a) relational shifts in authority depend on each situation and its participants; (b) storylines...... establish acts and positions and narratively frame what participants can expect from a medical consultation viewed as a social episode; and (c) the positioning of rights and duties can lead to misunderstandings and frustrations. We conclude that residents and patients locate themselves in outpatient...

  18. Fluorescent optical position sensor

    Science.gov (United States)

    Weiss, Jonathan D.

    2005-11-15

    A fluorescent optical position sensor and method of operation. A small excitation source side-pumps a localized region of fluorescence at an unknown position along a fluorescent waveguide. As the fluorescent light travels down the waveguide, the intensity of fluorescent light decreases due to absorption. By measuring with one (or two) photodetectors the attenuated intensity of fluorescent light emitted from one (or both) ends of the waveguide, the position of the excitation source relative to the waveguide can be determined by comparing the measured light intensity to a calibrated response curve or mathematical model. Alternatively, excitation light can be pumped into an end of the waveguide, which generates an exponentially-decaying continuous source of fluorescent light along the length of the waveguide. The position of a photodetector oriented to view the side of the waveguide can be uniquely determined by measuring the intensity of the fluorescent light emitted radially at that location.

  19. POSITIONING STRATEGIES DEVELOPMENT

    OpenAIRE

    Shakhshir Ghassan

    2014-01-01

    The positioning strategy has suffered serious changes in the last few decades, being influenced by the rapid development of competition and the growing focus on specific traits belonging to the market, to the consumer or to the product. The purpose of this paper is to present the developments of theoretical positioning strategies and the orientation from more simple, product oriented strategies, to ones more oriented towards the client and with a briefer period of time. The world is moving in...

  20. Position measuring device

    International Nuclear Information System (INIS)

    Maeda, Kazuyuki; Takahashi, Shuichi; Maruyama, Mayumi

    1998-01-01

    The present invention provides a device capable of measuring accurate position and distance easily even at places where operator can not easily access, such as cell facilities for vitrifying radioactive wastes. Referring to a case of the vitrifying cell, an objective equipment settled in the cell is photographed by a photographing device. The image is stored in a position measuring device by way of an image input device. After several years, when the objective equipment is exchanged, a new objective equipment is photographed by a photographing device. The image is also stored in the position measuring device. The position measuring device compares the data of both of the images on the basis of pixel unit. Based on the image of the equipment before the exchange as a reference, extent of the displacement of the installation position of the equipment on the image after the exchange caused by installation error and manufacturing error is determined to decide the position of the equipment after exchange relative to the equipment before exchange. (I.S.)

  1. Plasma position control device

    International Nuclear Information System (INIS)

    Takase, Haruhiko.

    1987-01-01

    Purpose: To conduct position control stably to various plasmas and reduce the burden on the control coil power source. Constitution: Among the proportional, integration and differentiation controls, a proportional-differentiation control section and an integration control section are connected in parallel. Then, a signal switching circuit is disposed to the control signal input section for the proportional-differentiation control section such that either a present position of plasmas or deviation between the present plasma position and an aimed value can be selected as a control signal depending on the control procedures or the state of the plasmas. For instance, if a rapid response is required for the control, the deviation between the present plasma position and the aimed value is selected as the input signal to conduct proportional, integration and differentiation controls. While on the other hand, if it is intended to reduce the burden on the control coil power source, it is adapted such that the control signal inputted to the proportional-differentiation control section itself can select the present plasma position. (Yoshihara, H.)

  2. In vivo tracking of genetically engineered, anti-HER2/neu directed natural killer cells to HER2/neu positive mammary tumors with magnetic resonance imaging

    International Nuclear Information System (INIS)

    Daldrup-Link, Heike E.; Meier, Reinhardt; Metz, Stephan; Settles, Marcus; Rummeny, Ernst J.; Rudelius, Martina; Piontek, Guido; Schlegel, Juergen; Piert, Morand; Uherek, Christoph; Wels, Winfried

    2005-01-01

    The purpose of this study is to optimize labeling of the human natural killer (NK) cell line NK-92 with iron-oxide-based contrast agents and to monitor the in vivo distribution of genetically engineered NK-92 cells, which are directed against HER2/neu receptors, to HER2/neu positive mammary tumors with magnetic resonance (MR) imaging. Parental NK-92 cells and genetically modified HER2/neu specific NK-92-scFv(FRP5)-zeta cells, expressing a chimeric antigen receptor specific to the tumor-associated ErbB2 (HER2/neu) antigen, were labeled with ferumoxides and ferucarbotran using simple incubation, lipofection and electroporation techniques. Labeling efficiency was evaluated by MR imaging, Prussian blue stains and spectrometry. Subsequently, ferucarbotran-labeled NK-92-scFv(FRP5)-zeta (n=3) or parental NK-92 cells were intravenously injected into the tail vein of six mice with HER2/neu-positive NIH 3T3 mammary tumors, implanted in the mammary fat pad. The accumulation of the cells in the tumors was monitored by MR imaging before and 12 and 24 h after cell injection (p.i.). MR data were correlated with histopathology. Both the parental NK-92 and the genetically modified NK-92-scFv(FRP5)-zeta cells could be labeled with ferucarbotran and ferumoxides by lipofection and electroporation, but not by simple incubation. The intracellular cytoplasmatic iron-oxide uptake was significantly higher after labeling with ferucarbotran than ferumoxides (P 6 NK-92-scFv(FRP5)-zeta cells into tumor-bearing mice, MR showed a progressive signal decline in HER2/neu-positive mammary tumors at 12 and 24 h (p.i.). Conversely, injection of 5 x 10 6 parental NK-92 control cells, not directed against HER2/neu receptors, did not cause significant signal intensity changes of the tumors. Histopathology confirmed an accumulation of the former, but not the latter cells in tumor tissue. The human natural killer cell line NK-92 can be efficiently labeled with clinically applicable iron-oxide contrast

  3. In vivo tracking of genetically engineered, anti-HER2/neu directed natural killer cells to HER2/neu positive mammary tumors with magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Daldrup-Link, Heike E. [UCSF Medical Center, Department of Radiology, San Francisco, CA (United States); Meier, Reinhardt; Metz, Stephan; Settles, Marcus; Rummeny, Ernst J. [Technical University Munich, Department of Radiology, Munich (Germany); Rudelius, Martina; Piontek, Guido; Schlegel, Juergen [Technical University Munich, Institute of Pathology, Division of Neuropathology, Munich (Germany); Piert, Morand [Technical University Munich, Department of Nuclear Medicine, Munich (Germany); Uherek, Christoph; Wels, Winfried [University of Frankfurt, Georg Speyer House, Frankfurt (Germany)

    2005-01-01

    The purpose of this study is to optimize labeling of the human natural killer (NK) cell line NK-92 with iron-oxide-based contrast agents and to monitor the in vivo distribution of genetically engineered NK-92 cells, which are directed against HER2/neu receptors, to HER2/neu positive mammary tumors with magnetic resonance (MR) imaging. Parental NK-92 cells and genetically modified HER2/neu specific NK-92-scFv(FRP5)-zeta cells, expressing a chimeric antigen receptor specific to the tumor-associated ErbB2 (HER2/neu) antigen, were labeled with ferumoxides and ferucarbotran using simple incubation, lipofection and electroporation techniques. Labeling efficiency was evaluated by MR imaging, Prussian blue stains and spectrometry. Subsequently, ferucarbotran-labeled NK-92-scFv(FRP5)-zeta (n=3) or parental NK-92 cells were intravenously injected into the tail vein of six mice with HER2/neu-positive NIH 3T3 mammary tumors, implanted in the mammary fat pad. The accumulation of the cells in the tumors was monitored by MR imaging before and 12 and 24 h after cell injection (p.i.). MR data were correlated with histopathology. Both the parental NK-92 and the genetically modified NK-92-scFv(FRP5)-zeta cells could be labeled with ferucarbotran and ferumoxides by lipofection and electroporation, but not by simple incubation. The intracellular cytoplasmatic iron-oxide uptake was significantly higher after labeling with ferucarbotran than ferumoxides (P<0.05). After intravenous injection of 5 x 10{sup 6} NK-92-scFv(FRP5)-zeta cells into tumor-bearing mice, MR showed a progressive signal decline in HER2/neu-positive mammary tumors at 12 and 24 h (p.i.). Conversely, injection of 5 x 10{sup 6} parental NK-92 control cells, not directed against HER2/neu receptors, did not cause significant signal intensity changes of the tumors. Histopathology confirmed an accumulation of the former, but not the latter cells in tumor tissue. The human natural killer cell line NK-92 can be efficiently

  4. Pumping potential wells

    Science.gov (United States)

    Hershkowitz, N.; Forest, C.; Wang, E. Y.; Intrator, T.

    1987-01-01

    Nonmonotonic plasma potential structures are a common feature of many double layers and sheaths. Steady state plasma potential wells separating regions having different plasma potentials are often found in laboratory experiments. In order to exist, such structures all must find a solution to a common problem. Ions created by charge exchange or ionization in the region of the potential well are electrostatically confined and tend to accumulate and fill up the potential well. The increase in positive charge should eliminate the well. Nevertheless, steady state structures are found in which the wells do not fill up. This means that it is important to take into account processes which 'pump' ions from the well. As examples of ion pumping of plasma wells, potential dips in front of a positively biased electro collecting anode in a relatively cold, low density multidipole plasma is considered. Pumping is provided by ion leaks from the edges of the potential dip or by oscillating the applied potential. In the former case the two dimensional character of the problem is shown to be important.

  5. Pumping potential wells

    International Nuclear Information System (INIS)

    Hershkowitz, N.; Forest, C.; Wang, E.Y.; Intrator, T.

    1987-01-01

    Nonmonotonic plasma potential structures are a common feature of many double layers and sheaths. Steady state plasma potential wells separating regions having different plasma potentials are often found in laboratory experiments. In order to exist, all such structures must find a solution to a common problem. Ions created by charge exchange or ionization in the region of the potential well are electrostatically confined and tend to accumulate and fill up the potential well. The increase in positive charge should eliminate the well. Nevertheless, steady state structures are found in which the wells do not fill up. This means that it is important to take into account processes which pump ions from the well. As examples of ion pumping of plasma wells, potential dips in front of a positively biased electron collecting anode in a relatively cold, low density, multidipole plasma are considered. Pumping is provided by ion leaks from the edges of the potential dip or by oscillating the applied potential. In the former case the two-dimensional character of the problem is shown to be important

  6. Pumping potential wells

    International Nuclear Information System (INIS)

    Hershkowitz, N.; Forest, C.; Wang, E.Y.; Intrator, T.

    1987-01-01

    Nonmonotonic plasma potential structures are a common feature of many double layers and sheaths. Steady state plasma potential wells separating regions having different plasma potentials are often found in laboratory experiments. In order to exist, such structures all must find a solution to a common problem. Ions created by charge exchange or ionization in the region of the potential well are electrostatically confined and tend to accumulate and fill up the potential well. The increase in positive charge should eliminate the well, but steady state structures are found in which the wells do not fill up. This means that it is important to take into account processes which 'pump' ions from the well. As examples of ion pumping of plasma wells, potential dips in front of a positively biased electron collecting anode in a relatively cold, low density multidipole plasma are considered. Pumping is provided by ion leaks from the edges of the potential dip or by oscillating the applied potential. In the former case the two dimensional character of the problem is shown to be important. (author)

  7. Uncharged positive electrode composition

    Science.gov (United States)

    Kaun, Thomas D.; Vissers, Donald R.; Shimotake, Hiroshi

    1977-03-08

    An uncharged positive-electrode composition contains particulate lithium sulfide, another alkali metal or alkaline earth metal compound other than sulfide, e.g., lithium carbide, and a transition metal powder. The composition along with a binder, such as electrolytic salt or a thermosetting resin is applied onto an electrically conductive substrate to form a plaque. The plaque is assembled as a positive electrode within an electrochemical cell opposite to a negative electrode containing a material such as aluminum or silicon for alloying with lithium. During charging, lithium alloy is formed within the negative electrode and transition metal sulfide such as iron sulfide is produced within the positive electrode. Excess negative electrode capacity over that from the transition metal sulfide is provided due to the electrochemical reaction of the other than sulfide alkali metal or alkaline earth metal compound.

  8. Position indication apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, T

    1964-02-24

    A plurality of magnetically operated switches are spaced equally in the hollow tube of a control rod actuating mechanism. One side of each switch is connected, via a low resistance, to a corresponding tap of a low resistance voltage divider network consisting of an equivalent number of low resistance sections with the opposite side of each switch connected to a common conducting wire A. To both ends of the voltage dividing network are connected, respectively, conducting wires B and C. Wires A, B, and C are further coupled to a fuel rod position indicator comprising a voltmeter and power source external to the control rod actuating member. The control rod actuating member is adapted to slide in the hollow tube so that switches passing a position facing a magnet secured to the lower end of the actuating member are rendered closed. Hence, the position of the control rod may be read by reading the voltage off the meter.

  9. Positioning devices for patients

    International Nuclear Information System (INIS)

    Heavens, M.

    1981-01-01

    It has been suggested that it is very important to position patients reproducibly at different stages of radiotherapy treatment planning and treatment, or similar procedures. Devices have been described for positioning a patient's upper and lower thorax. This invention provides reproducible positioning for a female patient's breasts, for example in planning treatment of and treating breast tumours. The patient is placed prone, using for example an upper thorax device. A support device is placed central to and beneath her breasts to partially displace them outwards. The device may be triangular in section with one apex contacting the chest wall at the sternum. Restraining straps may be provided to hold the breasts against the support device. Means may be provided to take a healthy breast from the path of radiation through the tumour. (author)

  10. Positioning and applications

    Directory of Open Access Journals (Sweden)

    Rogowski Jerzy B.

    2015-12-01

    Full Text Available The paper presents national report of Poland for IAG on positioning and applications. The selected research presented was carried out at leading Polish research institutions and concern precise multi-GNSS satellite positioning - relative and absolute - and also GNSS-based ionosphere and troposphere modelling and studies. The research resulted in noticeable advancements in these subjects confirmed by the development of new algorithms and methods. New and improved methods of precise GNSS positioning were developed, and also GNSS metrology was studied. New advanced troposphere models were presented and tested. In particular, these models allowed testing IPW variability on regional and global scales. Also, new regional ionosphere monitoring web-based services were developed and launched.

  11. Massive Galileon positivity bounds

    Science.gov (United States)

    de Rham, Claudia; Melville, Scott; Tolley, Andrew J.; Zhou, Shuang-Yong

    2017-09-01

    The EFT coefficients in any gapped, scalar, Lorentz invariant field theory must satisfy positivity requirements if there is to exist a local, analytic Wilsonian UV completion. We apply these bounds to the tree level scattering amplitudes for a massive Galileon. The addition of a mass term, which does not spoil the non-renormalization theorem of the Galileon and preserves the Galileon symmetry at loop level, is necessary to satisfy the lowest order positivity bound. We further show that a careful choice of successively higher derivative corrections are necessary to satisfy the higher order positivity bounds. There is then no obstruction to a local UV completion from considerations of tree level 2-to-2 scattering alone. To demonstrate this we give an explicit example of such a UV completion.

  12. Nucleosome Positioning and Epigenetics

    Science.gov (United States)

    Schwab, David; Bruinsma, Robijn

    2008-03-01

    The role of chromatin structure in gene regulation has recently taken center stage in the field of epigenetics, phenomena that change the phenotype without changing the DNA sequence. Recent work has also shown that nucleosomes, a complex of DNA wrapped around a histone octamer, experience a sequence dependent energy landscape due to the variation in DNA bend stiffness with sequence composition. In this talk, we consider the role nucleosome positioning might play in the formation of heterochromatin, a compact form of DNA generically responsible for gene silencing. In particular, we discuss how different patterns of nucleosome positions, periodic or random, could either facilitate or suppress heterochromatin stability and formation.

  13. The Role of Novel Substituted Diindolyl Methane Analogues in the Treatment of Triple-Negative and ErbB2-Positive Breast Cancer

    Science.gov (United States)

    2016-05-01

    among FAMU researchers and African American Community about breast cancer biology and therapy. The outcome of this proposal will lead to novel oral...drastically reduced from -23.22 mV to -2.64 mV on addition of 1:0.5 molar DOGS -NTA-Ni:CREKA. Surface complexation of CREKA increased the zeta potential of...Hydrodynamic diameter of DPL after separation of mannitol was 189.3 ± 5.7 nm. However, particle size was nearly similar at all the DOGS -NTA-Ni:CREKA ratios

  14. Inhibition of hydroxyapatite growth by casein, a potential salivary phosphoprotein homologue.

    Science.gov (United States)

    Romero, Maria J R H; Nakashima, Syozi; Nikaido, Toru; Ichinose, Shizuko; Sadr, Alireza; Tagami, Junji

    2015-08-01

    Salivary phosphoproteins are essential in tooth mineral regulation but are often overlooked in vitro. This study aimed to evaluate the effect of casein, as a salivary phosphoprotein homologue, on the deposition and growth of hydroxyapatite (HA) on tooth surfaces. Hydroxyapatite growth was quantified using seeded crystal systems. Artificial saliva (AS) containing HA powder and 0, 10, 20, 50, or 100 μg ml(-1) of casein, or 100 μg ml(-1) of dephosphorylated casein (Dcasein), was incubated for 0-8 h at 37°C, pH 7.2. Calcium concentrations were measured using atomic absorption spectroscopy (AAS). Surface precipitation of HA on bovine enamel and dentine blocks, incubated in similar conditions for 7 d, was examined using field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) with selected area electron diffraction (SAED). Casein adsorption was assessed using modified Lowry assays and zeta-potential measurements. The AAS results revealed a concentration-dependent inhibition of calcium consumption. Hydroxyapatite precipitation occurred when no casein was present, whereas precipitation of HA was apparently completely inhibited in casein-containing groups. Adsorption data demonstrated increasingly negative zeta-potential with increased casein concentration and an affinity constant similar to proline-rich proteins with Langmuir modelling. Casein inhibited the deposition and growth of HA primarily through the binding of esterized phosphate to HA active sites, indicating its potential as a mineral-regulating salivary phosphoprotein homologue in vitro. © 2015 Eur J Oral Sci.

  15. Variance in total levels of phospholipase C zeta (PLC-ζ) in human sperm may limit the applicability of quantitative immunofluorescent analysis as a diagnostic indicator of oocyte activation capability.

    Science.gov (United States)

    Kashir, Junaid; Jones, Celine; Mounce, Ginny; Ramadan, Walaa M; Lemmon, Bernadette; Heindryckx, Bjorn; de Sutter, Petra; Parrington, John; Turner, Karen; Child, Tim; McVeigh, Enda; Coward, Kevin

    2013-01-01

    To examine whether similar levels of phospholipase C zeta (PLC-ζ) protein are present in sperm from men whose ejaculates resulted in normal oocyte activation, and to examine whether a predominant pattern of PLC-ζ localization is linked to normal oocyte activation ability. Laboratory study. University laboratory. Control subjects (men with proven oocyte activation capacity; n = 16) and men whose sperm resulted in recurrent intracytoplasmic sperm injection failure (oocyte activation deficient [OAD]; n = 5). Quantitative immunofluorescent analysis of PLC-ζ protein in human sperm. Total levels of PLC-ζ fluorescence, proportions of sperm exhibiting PLC-ζ immunoreactivity, and proportions of PLC-ζ localization patterns in sperm from control and OAD men. Sperm from control subjects presented a significantly higher proportion of sperm exhibiting PLC-ζ immunofluorescence compared with infertile men diagnosed with OAD (82.6% and 27.4%, respectively). Total levels of PLC-ζ in sperm from individual control and OAD patients exhibited significant variance, with sperm from 10 out of 16 (62.5%) exhibiting levels similar to OAD samples. Predominant PLC-ζ localization patterns varied between control and OAD samples with no predictable or consistent pattern. The results indicate that sperm from control men exhibited significant variance in total levels of PLC-ζ protein, as well as significant variance in the predominant localization pattern. Such variance may hinder the diagnostic application of quantitative PLC-ζ immunofluorescent analysis. Copyright © 2013 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  16. Attitude and position tracking

    CSIR Research Space (South Africa)

    Candy, LP

    2011-01-01

    Full Text Available Several applications require the tracking of attitude and position of a body based on velocity data. It is tempting to use direction cosine matrices (DCM), for example, to track attitude based on angular velocity data, and to integrate the linear...

  17. Logotherapy and positive psychology

    Directory of Open Access Journals (Sweden)

    Oscar R. Oro

    2015-09-01

    Full Text Available Psychology omitted to approach, during almost a century, the positive aspects from persons, like creativity, humor, optimism, hope, forgiveness, life meaning, and happiness. These themes are approached by Positive Psychology, with Seligman like the principal exponent. Psychology was dedicated to explore the negative aspects from human beings improving human health. Nevertheless, this pathogenic model could not prevent mental disease. Concepts of Positive Psychology have a solid antecedent in Víktor Frankl ́s studies, which is the Logotherapy founder. This allows incorporating another perspective to approach positive aspects, from a philosophical and anthropological focus. Although the ways adopted by Frank and Seligman are different, both considered main aspects of human existence. Nevertheless, they investigated in different countries (from Europe and EE.UU.; in different circumstances (concentration camps, deaths, tortures; vs. academic context; in different historical periods and different social contexts (a country that lost the war and other that gave freedom to Europeans. In this work is used the concept life sense as the focus in professional formation and psychotherapy approach. 

  18. Delegation. Position Statement. Revised

    Science.gov (United States)

    Board, Connie; Bushmiaer, Margo; Davis-Alldritt, Linda; Fekaris, Nina; Morgitan, Judith; Murphy, M. Kathleen; Yow, Barbara

    2010-01-01

    It is the position of the National Association of School Nurses (NASN) that the delegation of nursing tasks in the school setting can be a valuable tool for the school nurse, when based on the nursing definition of delegation and in compliance with state nursing regulations and guidance. Delegation in school nursing is a complex process in which…

  19. Precise Point Positioning

    DEFF Research Database (Denmark)

    Zhang, Xiaohong

    the airborne lidar system misalignment angle by automating the matching of lidar data with ground truth. Kinematic GPS positioning has been widely used, but the available commercial software systems are normally only suitable for the short or medium range kinematic baseline. However, in polar areas, airborne...

  20. Positionality at the Center

    Directory of Open Access Journals (Sweden)

    Catherine Vanner

    2015-11-01

    Full Text Available As a Western feminist supporting and researching gender equality in education in postcolonial contexts, I often wonder: Am I doing more harm than good? The privilege of my social location means that my efforts to support education in postcolonial contexts risk being patronizing, insulting, threatening, imperialist, and recolonizing. Yet neglecting and ignoring postcolonial contexts similarly reflects and reproduces a privileged position. I provide a tentative framework designed to address positionality, power, and privilege while creating an ethical research process for working in a postcolonial context. Beginning with an identification of positionality, the objectives of research, and guiding theoretical frameworks to situate the research in relation to the participants and context, I proceed to establish a methodology designed to minimize the negative effects of power and maximize participants’ empowerment. I position myself as a bricoleur, layering feminist standpoint theory and postcolonial theory, and propose the collaborative data collection and analysis techniques, with particular attention to ethical and cultural sensitivity, using a social constructivist approach to grounded theory. This article highlights the need for Western researchers to reflect upon the power dynamics of their research in postcolonial contexts and develop a strategy for conducting empowering research that prevents the misrepresentation and exploitation of participants. Observations from my doctoral thesis data collection provide examples of how these concepts were operationalized in practice as well as reflections on the disconnect between theorizing and conducting ethical research in postcolonial contexts.