Sample records for strong suppressive effect
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Bonilla, Nuria; Vida, Carmen; Martínez-Alonso, Maira; Landa, Blanca B.; Gaju, Nuria; Cazorla, Francisco M.
2015-01-01
One of the main avocado diseases in southern Spain is white root rot caused by the fungus Rosellinia necatrix Prill. The use of organic soil amendments to enhance the suppressiveness of natural soil is an inviting approach that has successfully controlled other soilborne pathogens. This study tested the suppressive capacity of different organic amendments against R. necatrix and analyzed their effects on soil microbial communities and enzymatic activities. Two-year-old avocado trees were grown in soil treated with composted organic amendments and then used for inoculation assays. All of the organic treatments reduced disease development in comparison to unamended control soil, especially yard waste (YW) and almond shells (AS). The YW had a strong effect on microbial communities in bulk soil and produced larger population levels and diversity, higher hydrolytic activity and strong changes in the bacterial community composition of bulk soil, suggesting a mechanism of general suppression. Amendment with AS induced more subtle changes in bacterial community composition and specific enzymatic activities, with the strongest effects observed in the rhizosphere. Even if the effect was not strong, the changes caused by AS in bulk soil microbiota were related to the direct inhibition of R. necatrix by this amendment, most likely being connected to specific populations able to recolonize conducive soil after pasteurization. All of the organic amendments assayed in this study were able to suppress white root rot, although their suppressiveness appears to be mediated differentially. PMID:25769825
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Bonilla, Nuria; Vida, Carmen; Martínez-Alonso, Maira; Landa, Blanca B; Gaju, Nuria; Cazorla, Francisco M; de Vicente, Antonio
2015-05-15
One of the main avocado diseases in southern Spain is white root rot caused by the fungus Rosellinia necatrix Prill. The use of organic soil amendments to enhance the suppressiveness of natural soil is an inviting approach that has successfully controlled other soilborne pathogens. This study tested the suppressive capacity of different organic amendments against R. necatrix and analyzed their effects on soil microbial communities and enzymatic activities. Two-year-old avocado trees were grown in soil treated with composted organic amendments and then used for inoculation assays. All of the organic treatments reduced disease development in comparison to unamended control soil, especially yard waste (YW) and almond shells (AS). The YW had a strong effect on microbial communities in bulk soil and produced larger population levels and diversity, higher hydrolytic activity and strong changes in the bacterial community composition of bulk soil, suggesting a mechanism of general suppression. Amendment with AS induced more subtle changes in bacterial community composition and specific enzymatic activities, with the strongest effects observed in the rhizosphere. Even if the effect was not strong, the changes caused by AS in bulk soil microbiota were related to the direct inhibition of R. necatrix by this amendment, most likely being connected to specific populations able to recolonize conducive soil after pasteurization. All of the organic amendments assayed in this study were able to suppress white root rot, although their suppressiveness appears to be mediated differentially. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
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Haertzen, C A; Ross, F E
1980-08-01
Male prisoners who were opiate addicts (N = 47) were given three Process Association Tests of Addiction containing stimuli which evoked responses characteristic of three levels of drug habits: beginning and ending stage of addiction, intermediate stage of addiction, and an advanced level of addiction. Each test required subjects to associate 278 word stimuli with one of five options which were randomly selected from among 20 options covering the stages of addiction, steps in drug taking, and drug effects. The purpose of the study was to determine whether responses to particular options suppressed or enhanced responses to other options. A strong interaction was found between the classes of stimuli and the response options which produced suppression or enhancement. This interaction made it possible to develop a suppression scale to measure the effect of each class of stimulus. Popular responses most frequently suppressed responses of other options. Thus, when the stimuli were clean, responses of "to be clean" and "to live a normal life," which are sensitive indicators of the beginning or ending stages of addiction , suppressed responses of other stages. The response of "to be high," a prime indicator of an intermediate habit, suppressed responses of other options when the stimuli were drug names. Responses of "to be hooked" and "to fix," which are specific indicators of a strong habit, and "to be high," which is a nonspecific indicator of a strong habit, suppressed responses of many other options. In the development of new association tests the analysis of suppression could provide a basis for selectively varying option groupings in order to increase or decrease the frequently of certain responses.
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Silva, F W N; Costa, A L M T; Liu, Lei; Barros, E B
2016-11-04
The effects of edge vacancies on the electron transport properties of zigzag MoS2/WSe2 nanoribbons are studied using a density functional theory (DFT)-based tight-binding model with a sp(3)d(5) basis set for the electronic structure calculation and applying the Landauer-Büttiker approach for the electronic transport. Our results show that the presence of a single edge vacancy, with a missing MoS2/WSe2 triplet, is enough to suppress the conductance of the system by almost one half for most energies around the Fermi level. Furthermore, the presence of other single defects along the same edge has little effect on the overall conductance, indicating that the conductance of that particular edge has been strongly suppressed by the first defect. The presence of another defect on the opposite edge further suppresses the quantum conductance, independently of the relative position between the two defects in opposite edges. The introduction of other defects cause the suppression to be energy dependent, leading to conductance peaks which depend on the geometry of the edges. The strong conductance dependence on the presence of edge defects is corroborated by DFT calculations using SIESTA, which show that the electronic bands near the Fermi energy are strongly localized at the edge.
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Brotons, Lluís; Aquilué, Núria; de Cáceres, Miquel; Fortin, Marie-Josée; Fall, Andrew
2013-01-01
Available data show that future changes in global change drivers may lead to an increasing impact of fires on terrestrial ecosystems worldwide. Yet, fire regime changes in highly humanised fire-prone regions are difficult to predict because fire effects may be heavily mediated by human activities We investigated the role of fire suppression strategies in synergy with climate change on the resulting fire regimes in Catalonia (north-eastern Spain). We used a spatially-explicit fire-succession model at the landscape level to test whether the use of different firefighting opportunities related to observed reductions in fire spread rates and effective fire sizes, and hence changes in the fire regime. We calibrated this model with data from a period with weak firefighting and later assess the potential for suppression strategies to modify fire regimes expected under different levels of climate change. When comparing simulations with observed fire statistics from an eleven-year period with firefighting strategies in place, our results showed that, at least in two of the three sub-regions analysed, the observed fire regime could not be reproduced unless taking into account the effects of fire suppression. Fire regime descriptors were highly dependent on climate change scenarios, with a general trend, under baseline scenarios without fire suppression, to large-scale increases in area burnt. Fire suppression strategies had a strong capacity to compensate for climate change effects. However, strong active fire suppression was necessary to accomplish such compensation, while more opportunistic fire suppression strategies derived from recent fire history only had a variable, but generally weak, potential for compensation of enhanced fire impacts under climate change. The concept of fire regime in the Mediterranean is probably better interpreted as a highly dynamic process in which the main determinants of fire are rapidly modified by changes in landscape, climate and socioeconomic factors such as fire suppression strategies. PMID:23658726
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Brotons, Lluís; Aquilué, Núria; de Cáceres, Miquel; Fortin, Marie-Josée; Fall, Andrew
2013-01-01
Available data show that future changes in global change drivers may lead to an increasing impact of fires on terrestrial ecosystems worldwide. Yet, fire regime changes in highly humanised fire-prone regions are difficult to predict because fire effects may be heavily mediated by human activities We investigated the role of fire suppression strategies in synergy with climate change on the resulting fire regimes in Catalonia (north-eastern Spain). We used a spatially-explicit fire-succession model at the landscape level to test whether the use of different firefighting opportunities related to observed reductions in fire spread rates and effective fire sizes, and hence changes in the fire regime. We calibrated this model with data from a period with weak firefighting and later assess the potential for suppression strategies to modify fire regimes expected under different levels of climate change. When comparing simulations with observed fire statistics from an eleven-year period with firefighting strategies in place, our results showed that, at least in two of the three sub-regions analysed, the observed fire regime could not be reproduced unless taking into account the effects of fire suppression. Fire regime descriptors were highly dependent on climate change scenarios, with a general trend, under baseline scenarios without fire suppression, to large-scale increases in area burnt. Fire suppression strategies had a strong capacity to compensate for climate change effects. However, strong active fire suppression was necessary to accomplish such compensation, while more opportunistic fire suppression strategies derived from recent fire history only had a variable, but generally weak, potential for compensation of enhanced fire impacts under climate change. The concept of fire regime in the Mediterranean is probably better interpreted as a highly dynamic process in which the main determinants of fire are rapidly modified by changes in landscape, climate and socioeconomic factors such as fire suppression strategies.
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Progress in Fire Detection and Suppression Technology for Future Space Missions
NASA Technical Reports Server (NTRS)
Friedman, Robert; Urban, David L.
2000-01-01
Fire intervention technology (detection and suppression) is a critical part of the strategy of spacecraft fire safety. This paper reviews the status, trends, and issues in fire intervention, particularly the technology applied to the protection of the International Space Station and future missions beyond Earth orbit. An important contribution to improvements in spacecraft fire safety is the understanding of the behavior of fires in the non-convective (microgravity) environment of Earth-orbiting and planetary-transit spacecraft. A key finding is the strong influence of ventilation flow on flame characteristics, flammability limits and flame suppression in microgravity. Knowledge of these flow effects will aid the development of effective processes for fire response and technology for fire suppression.
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Near-source noise suppression of AMT by compressive sensing and mathematical morphology filtering
NASA Astrophysics Data System (ADS)
Li, Guang; Xiao, Xiao; Tang, Jing-Tian; Li, Jin; Zhu, Hui-Jie; Zhou, Cong; Yan, Fa-Bao
2017-12-01
In deep mineral exploration, the acquisition of audio magnetotelluric (AMT) data is severely affected by ambient noise near the observation sites; This near-field noise restricts investigation depths. Mathematical morphological filtering (MMF) proved effective in suppressing large-scale strong and variably shaped noise, typically low-frequency noise, but can not deal with pulse noise of AMT data. We combine compressive sensing and MMF. First, we use MMF to suppress the large-scale strong ambient noise; second, we use the improved orthogonal match pursuit (IOMP) algorithm to remove the residual pulse noise. To remove the noise and protect the useful AMT signal, a redundant dictionary that matches with spikes and is insensitive to the useful signal is designed. Synthetic and field data from the Luzong field suggest that the proposed method suppresses the near-source noise and preserves the signal well; thus, better results are obtained that improve the output of either MMF or IOMP.
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Anomalous Suppression of Valley Splittings in Lead Salt Nanocrystals
NASA Astrophysics Data System (ADS)
Poddubny, Alexander; Nestoklon, Mikhail; Goupalov, Serguei
2012-02-01
Atomistic sp^3d^5s^* tight-binding theory of PbSe and PbS nanocrystals is developed. It is demonstrated, that the valley splittings of confined electrons and holes strongly and peculiarly depend on the geometry of a nanocrystal. When the nanocrystal lacks a microscopic center of inversion and has Td symmetry, the splittings are strongly suppressed as compared to the more symmetric nanocrystals with Oh symmetry, having an inversion center. This effect is quite unusual because typically a higher symmetry of a physical system implies a higher degeneracy of its energy levels, while in our case the suppression of the splittings occurs in NCs having lower symmetry. Nevertheless, we were able to explain this puzzling behavior using mathematical apparatus of the group theory.
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Filamentation instability in a quantum magnetized plasma
DOE Office of Scientific and Technical Information (OSTI.GOV)
Bret, A.; and Instituto de Investigaciones Energeticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real
2008-02-15
The filamentation instability occurring when a nonrelativistic electron beam passes through a quantum magnetized plasma is investigated by means of a cold quantum magnetohydrodynamic model. It is proved that the instability can be completely suppressed by quantum effects if and only if a finite magnetic field is present. A dimensionless parameter is identified that measures the strength of quantum effects. Strong quantum effects allow for a much smaller magnetic field to suppress the instability than in the classical regime.
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Kitamura, Toshihiko; Todo, Hiroaki; Sugibayashi, Kenji
2009-02-01
The effects of several electrolyzed waters were evaluated on the permeation of model base, acid and non-ionized compounds, lidocaine (LC), benzoic acid (BA), and isosorbide mononitrate (ISMN), respectively, through excised hairless rat skin. Strong alkaline-electrolyzed reducing water (ERW) enhanced and suppressed the skin permeation of LC and BA, respectively, and it also increased the skin permeation of ISMN, a non-ionized compound. On the contrary, strong acidic electrolyzed oxidizing water (EOW) enhanced BA permeation, whereas suppressing LC permeation. Only a marginal effect was observed on the skin permeation of ISMN by EOW. These marked enhancing effects of ERW on the skin permeation of LC and ISMN were explained by pH partition hypothesis as well as a decrease in skin impedance. The present results strongly support that electrolyzed waters, ERW and EOW, can be used as a new vehicle in topical pharmaceuticals or cosmetics to modify the skin permeation of drugs without severe skin damage.
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Suppression of cooling by strong magnetic fields in white dwarf stars.
Valyavin, G; Shulyak, D; Wade, G A; Antonyuk, K; Zharikov, S V; Galazutdinov, G A; Plachinda, S; Bagnulo, S; Machado, L Fox; Alvarez, M; Clark, D M; Lopez, J M; Hiriart, D; Han, Inwoo; Jeon, Young-Beom; Zurita, C; Mujica, R; Burlakova, T; Szeifert, T; Burenkov, A
2014-11-06
Isolated cool white dwarf stars more often have strong magnetic fields than young, hotter white dwarfs, which has been a puzzle because magnetic fields are expected to decay with time but a cool surface suggests that the star is old. In addition, some white dwarfs with strong fields vary in brightness as they rotate, which has been variously attributed to surface brightness inhomogeneities similar to sunspots, chemical inhomogeneities and other magneto-optical effects. Here we describe optical observations of the brightness and magnetic field of the cool white dwarf WD 1953-011 taken over about eight years, and the results of an analysis of its surface temperature and magnetic field distribution. We find that the magnetic field suppresses atmospheric convection, leading to dark spots in the most magnetized areas. We also find that strong fields are sufficient to suppress convection over the entire surface in cool magnetic white dwarfs, which inhibits their cooling evolution relative to weakly magnetic and non-magnetic white dwarfs, making them appear younger than they truly are. This explains the long-standing mystery of why magnetic fields are more common amongst cool white dwarfs, and implies that the currently accepted ages of strongly magnetic white dwarfs are systematically too young.
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Kuhlmann, F E; Apffel, A; Fischer, S M; Goldberg, G; Goodley, P C
1995-12-01
Trifluoroacetic acid (TFA) and other volatile strong acids, used as modifiers in reverse-phase high-performance liquid chromatography, cause signal suppression for basic compounds when analyzed by electrospray ionization mass spectrometry (ESI-MS). Evidence is presented that signal suppression is caused by strong ion pairing between the TFA anion and the protonated sample cation of basic sample molecules. The ion-pairing process "masks" the protonated sample cations from the ESI-MS electric fields by rendering them "neutral. " Weakly basic molecules are not suppressed by this process. The TFA signal suppression effect is independent from the well-known spray problem that electrospray has with highly aqueous solutions that contain TFA. This previously reported spray problem is caused by the high conductivity and surface tension of aqueous TFA solutions. A practical method to enhance the signal for most basic analytes in the presence of signal-suppressing volatile strong acids has been developed. The method employs postcolumn addition of a solution of 75% propionic acid and 25% isopropanol in a ratio 1:2 to the column flow. Signal enhancement is typically 10-50 times for peptides and other small basic molecules. Thus, peptide maps that use ESI-MS for detection can be performed at lower levels, with conventional columns, without the need to use capillary chromatography or reduced mass spectral resolution to achieve satisfactory sensitivity. The method may be used with similar results for heptafluorobutyric acid and hydrochloric acid. A mechanism for TFA signal suppression and signal enhancement by the foregoing method, is proposed.
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Moderate Levels of Activation Lead to Forgetting In the Think/No-Think Paradigm
Detre, Greg J.; Natarajan, Annamalai; Gershman, Samuel J.; Norman, Kenneth A.
2013-01-01
Using the think/no-think paradigm (Anderson & Green, 2001), researchers have found that suppressing retrieval of a memory (in the presence of a strong retrieval cue) can make it harder to retrieve that memory on a subsequent test. This effect has been replicated numerous times, but the size of the effect is highly variable. Also, it is unclear from a neural mechanistic standpoint why preventing recall of a memory now should impair your ability to recall that memory later. Here, we address both of these puzzles using the idea, derived from computational modeling and studies of synaptic plasticity, that the function relating memory activation to learning is U-shaped, such that moderate levels of memory activation lead to weakening of the memory and higher levels of activation lead to strengthening. According to this view, forgetting effects in the think/no-think paradigm occur when the suppressed item activates moderately during the suppression attempt, leading to weakening; the effect is variable because sometimes the suppressed item activates strongly (leading to strengthening) and sometimes it does not activate at all (in which case no learning takes place). To test this hypothesis, we ran a think/no-think experiment where participants learned word-picture pairs; we used pattern classifiers, applied to fMRI data, to measure how strongly the picture associates were activating when participants were trying not to retrieve these associates, and we used a novel Bayesian curve-fitting procedure to relate this covert neural measure of retrieval to performance on a later memory test. In keeping with our hypothesis, the curve-fitting procedure revealed a nonmonotonic relationship between memory activation (as measured by the classifier) and subsequent memory, whereby moderate levels of activation of the to-be-suppressed item led to diminished performance on the final memory test, and higher levels of activation led to enhanced performance on the final test. PMID:23499722
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Moderate levels of activation lead to forgetting in the think/no-think paradigm.
Detre, Greg J; Natarajan, Annamalai; Gershman, Samuel J; Norman, Kenneth A
2013-10-01
Using the think/no-think paradigm (Anderson & Green, 2001), researchers have found that suppressing retrieval of a memory (in the presence of a strong retrieval cue) can make it harder to retrieve that memory on a subsequent test. This effect has been replicated numerous times, but the size of the effect is highly variable. Also, it is unclear from a neural mechanistic standpoint why preventing recall of a memory now should impair your ability to recall that memory later. Here, we address both of these puzzles using the idea, derived from computational modeling and studies of synaptic plasticity, that the function relating memory activation to learning is U-shaped, such that moderate levels of memory activation lead to weakening of the memory and higher levels of activation lead to strengthening. According to this view, forgetting effects in the think/no-think paradigm occur when the suppressed item activates moderately during the suppression attempt, leading to weakening; the effect is variable because sometimes the suppressed item activates strongly (leading to strengthening) and sometimes it does not activate at all (in which case no learning takes place). To test this hypothesis, we ran a think/no-think experiment where participants learned word-picture pairs; we used pattern classifiers, applied to fMRI data, to measure how strongly the picture associates were activating when participants were trying not to retrieve these associates, and we used a novel Bayesian curve-fitting procedure to relate this covert neural measure of retrieval to performance on a later memory test. In keeping with our hypothesis, the curve-fitting procedure revealed a nonmonotonic relationship between memory activation (as measured by the classifier) and subsequent memory, whereby moderate levels of activation of the to-be-suppressed item led to diminished performance on the final memory test, and higher levels of activation led to enhanced performance on the final test. Copyright © 2013 Elsevier Ltd. All rights reserved.
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Climate Change and ENSO Effects on Southeastern US Climate Patterns and Maize Yield.
Mourtzinis, Spyridon; Ortiz, Brenda V; Damianidis, Damianos
2016-07-19
Climate change has a strong influence on weather patterns and significantly affects crop yields globally. El Niño Southern Oscillation (ENSO) has a strong influence on the U.S. climate and is related to agricultural production variability. ENSO effects are location-specific and in southeastern U.S. strongly connect with climate variability. When combined with climate change, the effects on growing season climate patterns and crop yields might be greater than expected. In our study, historical monthly precipitation and temperature data were coupled with non-irrigated maize yield data (33-43 years depending on the location) to show a potential yield suppression of ~15% for one °C increase in southeastern U.S. growing season maximum temperature. Yield suppression ranged between -25 and -2% among locations suppressing the southeastern U.S. average yield trend since 1981 by 17 kg ha(-1)year(-1) (~25%), mainly due to year-to-year June temperature anomalies. Yields varied among ENSO phases from 1971-2013, with greater yields observed during El Niño phase. During La Niña years, maximum June temperatures were higher than Neutral and El Niño, whereas June precipitation was lower than El Niño years. Our data highlight the importance of developing location-specific adaptation strategies quantifying both, climate change and ENSO effects on month-specific growing season climate conditions.
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Effect of Timing of Proton Pump Inhibitor Administration on Acid Suppression.
Furuta, Kenji; Adachi, Kyoichi; Aimi, Masahito; Shimura, Shino; Mikami, Hironobu; Nishimura, Nobuhiro; Ishimura, Norihisa; Ishihara, Shunji; Naora, Kohji; Kinoshita, Yoshikazu
2016-01-01
Esomeprazole has been reported to show a strong acid suppression following preprandial as compared to postprandial administration, though no known study has compared the acid suppressing effects of other proton pump inhibitors between those administrations. The aim of this study was to compare intragastric pH levels following pre- and postprandial administrations of rabeprazole and esomeprazole. In 15 Helicobacter pylori-negative healthy volunteers, we measured intragastric pH after 7 days of pre- and postprandial administrations of rabeprazole (10 mg) or esomeprazole (20 mg) using a 5-way crossover design. Preprandial administration of esomeprazole showed stronger acid suppression than postprandial administration. The values for percent time at pH >4.0 over a 24-hour period increased from 45.3% with postprandial administration of esomeprazole to 54.4% with preprandial administration, while the percent time at pH >4.0 during daytime was increased to a greater extent from 51.4 to 66.5% with preprandial administration (p = 0.05). On the other hand, the acid suppressing effect of rabeprazole was not influenced by the timing of administration. The acid suppressing effect of esomeprazole is influenced by administration timing. In contrast, the acid suppressing effect of rabeprazole is not augmented by preprandial administration. © 2015 S. Karger AG, Basel.
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Constraints on black hole remnants
DOE Office of Scientific and Technical Information (OSTI.GOV)
Giddings, S.B.
1994-01-15
One possible fate of information lost to black holes is its preservation in black hole remnants. It is argued that a type of effective field theory describes such remnants (generically referred to as informons). The general structure of such a theory is investigated and the infinite pair production problem is revisited. A toy model for remnants clarifies some of the basic issues; in particular, infinite remnant production is not suppressed simply by the large internal volumes as proposed in cornucopion scenarios. Criteria for avoiding infinite production are stated in terms of couplings in the effective theory. Such instabilities remain amore » problem barring what would be described in that theory as a strong coupling conspiracy. The relation to Euclidean calculations of cornucopion production is sketched, and potential flaws in that analysis are outlined. However, it is quite plausible that pair production of ordinary black holes (e.g., Reissner-Noerdstrom or others) is suppressed due to strong effective couplings. It also remains an open possibility that a microsopic dynamics can be found yielding an appropriate strongly coupled effective theory of neutral informons without infinite pair production.« less
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Electrophysiological indices of surround suppression in humans
Vanegas, M. Isabel; Blangero, Annabelle
2014-01-01
Surround suppression is a well-known example of contextual interaction in visual cortical neurophysiology, whereby the neural response to a stimulus presented within a neuron's classical receptive field is suppressed by surrounding stimuli. Human psychophysical reports present an obvious analog to the effects seen at the single-neuron level: stimuli are perceived as lower-contrast when embedded in a surround. Here we report on a visual paradigm that provides relatively direct, straightforward indices of surround suppression in human electrophysiology, enabling us to reproduce several well-known neurophysiological and psychophysical effects, and to conduct new analyses of temporal trends and retinal location effects. Steady-state visual evoked potentials (SSVEP) elicited by flickering “foreground” stimuli were measured in the context of various static surround patterns. Early visual cortex geometry and retinotopic organization were exploited to enhance SSVEP amplitude. The foreground response was strongly suppressed as a monotonic function of surround contrast. Furthermore, suppression was stronger for surrounds of matching orientation than orthogonally-oriented ones, and stronger at peripheral than foveal locations. These patterns were reproduced in psychophysical reports of perceived contrast, and peripheral electrophysiological suppression effects correlated with psychophysical effects across subjects. Temporal analysis of SSVEP amplitude revealed short-term contrast adaptation effects that caused the foreground signal to either fall or grow over time, depending on the relative contrast of the surround, consistent with stronger adaptation of the suppressive drive. This electrophysiology paradigm has clinical potential in indexing not just visual deficits but possibly gain control deficits expressed more widely in the disordered brain. PMID:25411464
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Electron attachment to molecules in a cluster environment: suppression and enhancement effects
NASA Astrophysics Data System (ADS)
Fabrikant, Ilya I.
2018-05-01
Cluster environments can strongly influence dissociative electron attachment (DEA) processes. These effects are important in many applications, particularly for surface chemistry, radiation damage, and atmospheric physics. We review several mechanisms for DEA suppression and enhancement due to cluster environments, particularly due to microhydration. Long-range electron-molecule and electron-cluster interactions play often a significant role in these effects and can be analysed by using theoretical models. Nevertheless many observations remain unexplained due to complexity of the physics and chemistry of interaction of DEA fragments with the cluster environment.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Xie, H.; School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287-6106; Prioli, R.
The properties of InAs quantum dots (QDs) have been studied for application in intermediate band solar cells. It is found that suppression of plastic relaxation in the QDs has a significant effect on the optoelectronic properties. Partial capping plus annealing is shown to be effective in controlling the height of the QDs and in suppressing plastic relaxation. A force balancing model is used to explain the relationship between plastic relaxation and QD height. A strong luminescence has been observed from strained QDs, indicating the presence of localized states in the desired energy range. No luminescence has been observed from plasticallymore » relaxed QDs.« less
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Echolocation versus echo suppression in humans
Wallmeier, Ludwig; Geßele, Nikodemus; Wiegrebe, Lutz
2013-01-01
Several studies have shown that blind humans can gather spatial information through echolocation. However, when localizing sound sources, the precedence effect suppresses spatial information of echoes, and thereby conflicts with effective echolocation. This study investigates the interaction of echolocation and echo suppression in terms of discrimination suppression in virtual acoustic space. In the ‘Listening’ experiment, sighted subjects discriminated between positions of a single sound source, the leading or the lagging of two sources, respectively. In the ‘Echolocation’ experiment, the sources were replaced by reflectors. Here, the same subjects evaluated echoes generated in real time from self-produced vocalizations and thereby discriminated between positions of a single reflector, the leading or the lagging of two reflectors, respectively. Two key results were observed. First, sighted subjects can learn to discriminate positions of reflective surfaces echo-acoustically with accuracy comparable to sound source discrimination. Second, in the Listening experiment, the presence of the leading source affected discrimination of lagging sources much more than vice versa. In the Echolocation experiment, however, the presence of both the lead and the lag strongly affected discrimination. These data show that the classically described asymmetry in the perception of leading and lagging sounds is strongly diminished in an echolocation task. Additional control experiments showed that the effect is owing to both the direct sound of the vocalization that precedes the echoes and owing to the fact that the subjects actively vocalize in the echolocation task. PMID:23986105
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Nanoparticle Motion in Entangled Melts of Linear and Nonconcatenated Ring Polymers
2017-01-01
The motion of nanoparticles (NPs) in entangled melts of linear polymers and nonconcatenated ring polymers are compared by large-scale molecular dynamics simulations. The comparison provides a paradigm for the effects of polymer architecture on the dynamical coupling between NPs and polymers in nanocomposites. Strongly suppressed motion of NPs with diameter d larger than the entanglement spacing a is observed in a melt of linear polymers before the onset of Fickian NP diffusion. This strong suppression of NP motion occurs progressively as d exceeds a and is related to the hopping diffusion of NPs in the entanglement network. In contrast to the NP motion in linear polymers, the motion of NPs with d > a in ring polymers is not as strongly suppressed prior to Fickian diffusion. The diffusion coefficient D decreases with increasing d much slower in entangled rings than in entangled linear chains. NP motion in entangled nonconcatenated ring polymers is understood through a scaling analysis of the coupling between NP motion and the self-similar entangled dynamics of ring polymers. PMID:28392603
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Zha, Hao; Latina, Andrea; Grudiev, Alexej; ...
2016-01-20
The baseline design of CLIC (Compact Linear Collider) uses X-band accelerating structures for its main linacs. In order to maintain beam stability in multibunch operation, long-range transverse wakefields must be suppressed by 2 orders of magnitude between successive bunches, which are separated in time by 0.5 ns. Such strong wakefield suppression is achieved by equipping every accelerating structure cell with four damping waveguides terminated with individual rf loads. A beam-based experiment to directly measure the effectiveness of this long-range transverse wakefield and benchmark simulations was made in the FACET test facility at SLAC using a prototype CLIC accelerating structure. Furthermore,more » the experiment showed good agreement with the simulations and a strong suppression of the wakefields with an unprecedented minimum resolution of 0.1 V/(pC mm m).« less
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QUIESCENCE CORRELATES STRONGLY WITH DIRECTLY MEASURED BLACK HOLE MASS IN CENTRAL GALAXIES
DOE Office of Scientific and Technical Information (OSTI.GOV)
Terrazas, Bryan A.; Bell, Eric F.; Henriques, Bruno M. B.
Roughly half of all stars reside in galaxies without significant ongoing star formation. However, galaxy formation models indicate that it is energetically challenging to suppress the cooling of gas and the formation of stars in galaxies that lie at the centers of their dark matter halos. In this Letter, we show that the dependence of quiescence on black hole and stellar mass is a powerful discriminant between differing models for the mechanisms that suppress star formation. Using observations of 91 star-forming and quiescent central galaxies with directly measured black hole masses, we find that quiescent galaxies host more massive blackmore » holes than star-forming galaxies with similar stellar masses. This observational result is in qualitative agreement with models that assume that effective, more-or-less continuous active galactic nucleus feedback suppresses star formation, strongly suggesting the importance of the black hole in producing quiescence in central galaxies.« less
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Development of Inhibitors of Salicylic Acid Signaling.
Jiang, Kai; Kurimoto, Tetsuya; Seo, Eun-kyung; Miyazaki, Sho; Nakajima, Masatoshi; Nakamura, Hidemitsu; Asami, Tadao
2015-08-19
Salicylic acid (SA) plays important roles in the induction of systemic acquired resistance (SAR) in plants. Determining the mechanism of SAR will extend our understanding of plant defenses against pathogens. We recently reported that PAMD is an inhibitor of SA signaling, which suppresses the expression of the pathogenesis-related PR genes and is expected to facilitate the understanding of SA signaling. However, PAMD strongly inhibits plant growth. To minimize the side effects of PAMD, we synthesized a number of PAMD derivatives, and identified compound 4 that strongly suppresses the expression of the PR genes with fewer adverse effects on plant growth than PAMD. We further showed that the adverse effects on plant growth were partially caused the stabilization of DELLA, which is also related to the pathogen responses. These results indicate that compound 4 would facilitate our understanding of SA signaling and its cross talk with other plant hormones.
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Degree of suppression of associations to stages of addiction by the response of "high".
Haertzen, C A; Ross, F E
1980-05-01
Male heroin or opiate addicts (N = 78) had a great inclination to give the association "to be high" to the names of nine drugs of abuse in a multiple-forced-choice association test irrespective of whether they had weak or strong habits for the drugs used as stimulus words. The tendency to give the "high" response was so great that other responses indicative of stages of addiction, steps in drug-taking, or drug effects were suppressed below the chance level. When scales were scored so that the response of "high" had no effect, the habit status of the sample revealed by associations with a specific set of words became clearer. A pattern of a strong habit for opiates evoked by opiate names became more evident after elimination of the effect of the response to "high," as did the strong habit pattern in response to drug relevant words. However, the pattern of responses characteristic of a nonaddictive status evoked by clean words remained relatively stable even including the effect of the response of "high." The study suggests that more meaningful responses are found when the response options are multiple rather than fixed.
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NASA Astrophysics Data System (ADS)
Sarwar, T.; Qamar, A.; Nadeem, M.
2017-07-01
Dynamics of spin ordering in the manganite Nd0.5Ca0.5MnO3 have been investigated in this paper. It was observed that the complex mixed magnetic ordering in pellets is comprised of antiferromagnetic ordering at 160 K (TN) and complete charge ordering at 250 K (TCO). Under ac field, appearance of unstable ferromagnetic correlations is observed above TCO, which is badly frustrated due to strong spin disorder induced by Jahn Teller distortions. Impedance measurements reveal the spin glass like scenario, suppressing the strong antiferromagnetic and charge ordering states below TN.
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Seaweed prevents breast cancer?
Funahashi, H; Imai, T; Mase, T; Sekiya, M; Yokoi, K; Hayashi, H; Shibata, A; Hayashi, T; Nishikawa, M; Suda, N; Hibi, Y; Mizuno, Y; Tsukamura, K; Hayakawa, A; Tanuma, S
2001-05-01
To investigate the chemopreventive effects of seaweed on breast cancer, we have been studying the relationship between iodine and breast cancer. We found earlier that the seaweed, wakame, showed a suppressive effect on the proliferation of DMBA (dimethylbenz(a)anthracene)-induced rat mammary tumors, possibly via apoptosis induction. In the present study, powdered mekabu was placed in distilled water, and left to stand for 24 h at 4 degrees C. The filtered supernatant was used as mekabu solution. It showed an extremely strong suppressive effect on rat mammary carcinogenesis when used in daily drinking water, without toxicity. In vitro, mekabu solution strongly induced apoptosis in 3 kinds of human breast cancer cells. These effects were stronger than those of a chemotherapeutic agent widely used to treat human breast cancer. Furthermore, no apoptosis induction was observed in normal human mammary cells. In Japan, mekabu is widely consumed as a safe, inexpensive food. Our results suggest that mekabu has potential for chemoprevention of human breast cancer.
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Regulation of connexin26 and connexin43 expression in rat endometrium by ovarian steroid hormones.
Grümmer, R; Chwalisz, K; Mulholland, J; Traub, O; Winterhager, E
1994-12-01
A distinct spatial and temporal pattern of connexin26 and connexin43 (cx26 and cx43) expression was observed in the rat endometrium in response to embryo implantation; however, connexin expression was suppressed during the preimplantation period. Pseudopregnant rats did not show connexin mRNA, while artificial decidualization induced by a scratch led to a strong expression of cx26 and cx43 in the endometrium of these animals. In order to examine the regulatory effects of ovarian steroid hormones on connexin expression, ovariectomized rats were treated with progesterone (P) and/or estradiol-17 beta (E2). Untreated, ovariectomized animals expressed mRNA for cx43, but not for cx26. Endometrial expression of mRNA for both connexins was strongly enhanced by E2 treatment; immunolabeling revealed protein for cx26 in the uterine luminal epithelial cells and for cx43 in the uterine stromal cells. P treatment, either alone or in combination with E2, suppressed expression of connexin mRNA. P suppression in the presence of E2 was reversible when P was withdrawn. When administered on Days 0-2 of pregnancy, the antiprogestin onapristone inhibited the effect of P and gave rise to strong expression of both connexin transcripts. These results demonstrate that expression of cx26 and cx43 in the rat uterine endometrium is differentially regulated by E2 and P during early pregnancy.
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Hung, Hui-Chen; Shih, Shin-Ru; Chang, Teng-Yuan; Fang, Ming-Yu; Hsu, John T-A
2014-01-01
Enterovirus 71 (EV-A71) is a neurotropic virus that can cause severe complications involving the central nervous system. No effective antiviral therapeutics are available for treating EV-A71 infection and drug discovery efforts are rarely focused to target this disease. Thus, the main goal of this study was to discover existing drugs with novel indications that may effectively inhibit EV-A71 replication and the inflammatory cytokines elevation. In this study, we showed that LiCl, a GSK3β inhibitor, effectively suppressed EV-A71 replication, apoptosis and inflammatory cytokines production (Interleukin 6, Interleukin-1β) in infected cells. Furthermore, LiCl and an immunomodular agent were shown to strongly synergize with each other in suppressing EV-A71 replication. The results highlighted potential new treatment regimens in suppressing sequelae caused by EV-A71 replication.
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Dan-Glauser, Elise S.; Gross, James J.
2011-01-01
This study examines the early affective consequences of two close forms of suppression. Participants (N=37) were shown negative, positive, and neutral pictures and cued either to attend to the pictures, or to perform expressive or physiological suppression (i.e. reduce body reactions). Continuous measures of experience, expressivity, and autonomic responses showed that both suppression strategies produced rapid response modulation. Common effects of the two strategies included a transient increase in negative feeling, a durable decrease in positive feeling, and a decrease in expressivity, cardiovascular activity, and oxygenation. The two strategies were significantly different only in response to positive stimuli, with physiological suppression showing a larger decrease in experience intensity and blood pressure. These results suggest a strong overlap between the two suppression strategies in terms of their early impact on emotional responses. PMID:21361967
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Oku, Tsuneyuki; Murata-Takenoshita, Yoko; Yamazaki, Yuko; Shimura, Fumio; Nakamura, Sadako
2014-11-01
In an attempt to develop D-sorbose as a new sweetener that could help in preventing lifestyle-related diseases, we investigated the inhibitory effect of D-sorbose on disaccharidase activity, using the brush border membrane vesicles of rat small intestines. The inhibitory effect was compared with that of L-sorbose and other rare sugars, and the small intestinal disaccharidases in rats was compared with that of humans as well. In humans and the small intestines of rats, d-sorbose strongly inhibited sucrase activity and weakly inhibited maltase activity. Inhibition by D-sorbose of sucrase activity was similar to that of L-arabinose, and the K(i) of D-sorbose was 7.5 mM. Inhibition by D-sorbose was very strong in comparison with that of L-sorbose (K(i), 60.8 mM), whereas inhibition of d-tagatose was between that of D-sorbose and L-sorbose. The inhibitory mode of D-sorbose for sucrose and maltase was uncompetitive, and that of L-sorbose was competitive. To determine a suppressive effect on postprandial blood levels of glucose and insulin via inhibition of sucrase activity, sucrose solution with or without D-sorbose was administered to rats. Increments in the blood levels of glucose and insulin were suppressed significantly after administration of sucrose solution with D-sorbose to rats, in comparison to administration of sucrose solution without D-sorbose. In contrast, the suppressive effect of L-sorbose on postprandial blood levels of glucose and insulin was very weak. These results suggest that D-sorbose may have an inhibitory effect on disaccharidase activity and could be used as a sweetener to suppress the postprandial elevation of blood levels of glucose and insulin. The use of D-sorbose as a sweetener may contribute to the prevention of lifestyle-related diseases, such as type 2 diabetes mellitus. Copyright © 2014 Elsevier Inc. All rights reserved.
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Dexamethasone suppression test
DST; ACTH suppression test; Cortisol suppression test ... During this test, you will receive dexamethasone. This is a strong man-made (synthetic) glucocorticoid medicine. Afterward, your blood is drawn ...
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Ahn, Sora; Jo, Sumin; Jun, Sang Beom; Lee, Hyang Woon; Lee, Seungjun
2017-01-01
In this paper, we identified factors that can affect seizure suppression via electrical stimulation by an integrative study based on experimental and computational approach. Preferentially, we analyzed the characteristics of seizure-like events (SLEs) using our previous in vitro experimental data. The results were analyzed in two groups classified according to the size of the effective region, in which the SLE was able to be completely suppressed by local stimulation. However, no significant differences were found between these two groups in terms of signal features or propagation characteristics (i.e., propagation delays, frequency spectrum, and phase synchrony). Thus, we further investigated important factors using a computational model that was capable of evaluating specific influences on effective region size. In the proposed model, signal transmission between neurons was based on two different mechanisms: synaptic transmission and the electrical field effect. We were able to induce SLEs having similar characteristics with differentially weighted adjustments for the two transmission methods in various noise environments. Although the SLEs had similar characteristics, their suppression effects differed. First of all, the suppression effect occurred only locally where directly received the stimulation effect in the high noise environment, but it occurred in the entire network in the low noise environment. Interestingly, in the same noise environment, the suppression effect was different depending on SLE propagation mechanism; only a local suppression effect was observed when the influence of the electrical field transmission was very weak, whereas a global effect was observed with a stronger electrical field effect. These results indicate that neuronal activities synchronized by a strong electrical field effect respond more sensitively to partial changes in the entire network. In addition, the proposed model was able to predict that stimulation of a seizure focus region is more effective for suppression. In conclusion, we confirmed the possibility of a computational model as a simulation tool to analyze the efficacy of deep brain stimulation (DBS) and investigated the key factors that determine the size of an effective region in seizure suppression via electrical stimulation.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Ge, Ting; Kalathi, Jagannathan T.; Halverson, Jonathan D.
The motion of nanoparticles (NPs) in entangled melts of linear polymers and non-concatenated ring polymers are compared by large-scale molecular dynamics simulations. The comparison provides a paradigm for the effects of polymer architecture on the dynamical coupling between NPs and polymers in nanocomposites. Strongly suppressed motion of NPs with diameter d larger than the entanglement spacing a is observed in a melt of linear polymers before the onset of Fickian NP diffusion. This strong suppression of NP motion occurs progressively as d exceeds a, and is related to the hopping diffusion of NPs in the entanglement network. In contrast tomore » the NP motion in linear polymers, the motion of NPs with d > a in ring polymers is not as strongly suppressed prior to Fickian diffusion. The diffusion coefficient D decreases with increasing d much slower in entangled rings than in entangled linear chains. NP motion in entangled non-concatenated ring polymers is understood through a scaling analysis of the coupling between NP motion and the self-similar entangled dynamics of ring polymers.« less
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Ge, Ting; Kalathi, Jagannathan T.; Halverson, Jonathan D.; ...
2017-02-13
The motion of nanoparticles (NPs) in entangled melts of linear polymers and non-concatenated ring polymers are compared by large-scale molecular dynamics simulations. The comparison provides a paradigm for the effects of polymer architecture on the dynamical coupling between NPs and polymers in nanocomposites. Strongly suppressed motion of NPs with diameter d larger than the entanglement spacing a is observed in a melt of linear polymers before the onset of Fickian NP diffusion. This strong suppression of NP motion occurs progressively as d exceeds a, and is related to the hopping diffusion of NPs in the entanglement network. In contrast tomore » the NP motion in linear polymers, the motion of NPs with d > a in ring polymers is not as strongly suppressed prior to Fickian diffusion. The diffusion coefficient D decreases with increasing d much slower in entangled rings than in entangled linear chains. NP motion in entangled non-concatenated ring polymers is understood through a scaling analysis of the coupling between NP motion and the self-similar entangled dynamics of ring polymers.« less
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Shot-noise at a Fermi-edge singularity: Non-Markovian dynamics
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ubbelohde, N.; Maire, N.; Haug, R. J.
2013-12-04
For an InAs quantum dot we study the current shot noise at a Fermi-edge singularity in low temperature cross-correlation measurements. In the regime of the interaction effect the strong suppression of noise observed at zero magnetic field and the sequence of enhancement and suppression in magnetic field go beyond a Markovian master equation model. Qualitative and quantitative agreement can however be achieved by a generalized master equation model taking non-Markovian dynamics into account.
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Noise suppression in surface microseismic data by τ-p transform
Forghani-Arani, Farnoush; Batzle, Mike; Behura, Jyoti; Willis, Mark; Haines, Seth; Davidson, Michael
2013-01-01
Surface passive seismic methods are receiving increased attention for monitoring changes in reservoirs during the production of unconventional oil and gas. However, in passive seismic data the strong cultural and ambient noise (mainly surface-waves) decreases the effectiveness of these techniques. Hence, suppression of surface-waves is a critical step in surface microseismic monitoring. We apply a noise suppression technique, based on the τ — p transform, to a surface passive seismic dataset recorded over a Barnett Shale reservoir undergoing a hydraulic fracturing process. This technique not only improves the signal-to-noise ratios of added synthetic microseismic events, but it also preserves the event waveforms.
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Neutrino conversion in a neutrino flux: towards an effective theory of collective oscillations
NASA Astrophysics Data System (ADS)
Hansen, Rasmus S. L.; Smirnov, Alexei Yu.
2018-04-01
Collective oscillations of supernova neutrinos above the neutrino sphere can be completely described by the propagation of individual neutrinos in external potentials and are in this sense a linear phenomenon. An effective theory of collective oscillations can be developed based on certain assumptions about time dependence of these potentials. General conditions for strong flavor transformations are formulated and these transformations can be interpreted as parametric resonance effects induced by periodic modulations of the potentials. We study a simplified and solvable example, where a probe neutrino is propagating in a flux of collinear neutrinos, such that ν ν‑ interactions in the flux are absent. Still, this example retains the main feature—the coherent flavor exchange. Properties of the parametric resonance are studied, and it is shown that integrations over energies and emission points of the flux neutrinos suppress modulations of the potentials and therefore strong transformations. The transformations are also suppressed by changes in densities of background neutrinos and electrons.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Litvinenko,V.; Yakimenko, V.
We propose undertaking a demonstration experiment on suppressing spontaneous undulator radiation from an electron beam at BNL's Accelerator Test Facility (ATF). We describe the method, the proposed layout, and a possible schedule. There are several advantages in strongly suppressing shot noise in the electron beam, and the corresponding spontaneous radiation. The self-amplified spontaneous (SASE) emission originating from shot noise in the electron beam is the main source of noise in high-gain FEL amplifiers. It may negatively affect several HG FEL applications ranging from single- to multi-stage HGHG FELs. SASE saturation also imposes a fundamental hard limit on the gain ofmore » an FEL amplifier in a coherent electron-cooling scheme. A novel active method for suppressing shot noise in relativistic electron beams by many orders-of-magnitude was recently proposed. While theoretically such strong suppression appears feasible, the performance and applicability of this novel method must be evaluated experimentally. Several practical questions about the proposed noise suppressor, such as 3D effects and/or sensitivity to the e-beam parameters also require experimental clarification. To do this, we propose here a proof-of-principle experiment using elements of the VISA FEL at BNL's Accelerator Test Facility.« less
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Suppressing unwanted memories reduces their unconscious influence via targeted cortical inhibition
Gagnepain, Pierre; Henson, Richard N.; Anderson, Michael C.
2014-01-01
Suppressing retrieval of unwanted memories reduces their later conscious recall. It is widely believed, however, that suppressed memories can continue to exert strong unconscious effects that may compromise mental health. Here we show that excluding memories from awareness not only modulates medial temporal lobe regions involved in explicit retention, but also neocortical areas underlying unconscious expressions of memory. Using repetition priming in visual perception as a model task, we found that excluding memories of visual objects from consciousness reduced their later indirect influence on perception, literally making the content of suppressed memories harder for participants to see. Critically, effective connectivity and pattern similarity analysis revealed that suppression mechanisms mediated by the right middle frontal gyrus reduced activity in neocortical areas involved in perceiving objects and targeted the neural populations most activated by reminders. The degree of inhibitory modulation of the visual cortex while people were suppressing visual memories predicted, in a later perception test, the disruption in the neural markers of sensory memory. These findings suggest a neurobiological model of how motivated forgetting affects the unconscious expression of memory that may be generalized to other types of memory content. More generally, they suggest that the century-old assumption that suppression leaves unconscious memories intact should be reconsidered. PMID:24639546
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Suzuki, Y.; Kobayashi, A.
1983-04-01
In the acute phase of Toxoplasma infection, the function of both helper T and B cells was suppressed in primary antibody responses to dinitrophenol (DNP)-conjugated protein antigens. During the course of infection, the suppressive effect on T cells seems to continue longer than that on B cells, since suppression in responses to sheep erythrocytes, a T-dependent antigen, persisted longer than those to DNP-Ficoll, a T-independent antigen. Plastic-adherent cells from the spleens of Toxoplasma-infected and X-irradiated (400 rads) mice had strong suppressor activity in primary anti-sheep erythrocyte antibody responses of normal mouse spleen cells in vitro. These data suggest that themore » activation of irradiation-resistant and plastic-adherent suppressor cells causes the suppression of both T and B cells in Toxoplasma-infected mice.« less
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The Role of Inhibition in Avoiding Distraction by Salient Stimuli.
Gaspelin, Nicholas; Luck, Steven J
2018-01-01
Researchers have long debated whether salient stimuli can involuntarily 'capture' visual attention. We review here evidence for a recently discovered inhibitory mechanism that may help to resolve this debate. This evidence suggests that salient stimuli naturally attempt to capture attention, but capture can be avoided if the salient stimulus is suppressed before it captures attention. Importantly, the suppression process can be more or less effective as a result of changing task demands or lapses in cognitive control. Converging evidence for the existence of this suppression mechanism comes from multiple sources, including psychophysics, eye-tracking, and event-related potentials (ERPs). We conclude that the evidence for suppression is strong, but future research will need to explore the nature and limits of this mechanism. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Lou, Xianwen; van Dongen, Joost L J; Milroy, Lech-Gustav; Meijer, E W
2016-12-30
Ionization in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a very complicated process. It has been reported that quaternary ammonium salts show extremely strong matrix and analyte suppression effects which cannot satisfactorily be explained by charge transfer reactions. Further investigation of the reasons causing these effects can be useful to improve our understanding of the MALDI process. The dried-droplet and modified thin-layer methods were used as sample preparation methods. In the dried-droplet method, analytes were co-crystallized with matrix, whereas in the modified thin-layer method analytes were deposited on the surface of matrix crystals. Model compounds, tetrabutylammonium iodide ([N(Bu) 4 ]I), cesium iodide (CsI), trihexylamine (THA) and polyethylene glycol 600 (PEG 600), were selected as the test analytes given their ability to generate exclusively pre-formed ions, protonated ions and metal ion adducts respectively in MALDI. The strong matrix suppression effect (MSE) observed using the dried-droplet method might disappear using the modified thin-layer method, which suggests that the incorporation of analytes in matrix crystals contributes to the MSE. By depositing analytes on the matrix surface instead of incorporating in the matrix crystals, the competition for evaporation/ionization from charged matrix/analyte clusters could be weakened resulting in reduced MSE. Further supporting evidence for this inference was found by studying the analyte suppression effect using the same two sample deposition methods. By comparing differences between the mass spectra obtained via the two sample preparation methods, we present evidence suggesting that the generation of gas-phase ions from charged matrix/analyte clusters may induce significant suppression of matrix and analyte ions. The results suggest that the generation of gas-phase ions from charged matrix/analyte clusters is an important ionization step in MALDI-MS. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
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Hashimoto, Keisuke; Amano, Taku; Kasakura, Akiko; Uhl, George R; Sora, Ichiro; Sakai, Norio; Kuzumaki, Naoko; Suzuki, Tsutomu; Narita, Minoru
2009-03-27
Most reports in the literature have shown that the effects of opioid analgesics are primarily mediated by mu-opioid receptor (MOR), whereas other potential targets of opioid analgesics have not been thoroughly characterized. In this study, we found that extracellular application of morphine, fentanyl or oxycodone, which are all considered to be MOR agonists, at relatively high concentrations, but not endogenous mu-opioid peptides, produced a concentration-dependent suppression of sodium currents in cultured thalamic neurons. These effects of opioids were not affected by either a MOR antagonist naloxone or a deletion of MOR gene. Among these opioids, fentanyl strongly suppressed sodium currents to the same degree as lidocaine, and both morphine and oxycodone slightly but significantly reduced sodium currents when they were present extracellularly. In contrast, the intracellular application of morphine, but not oxycodone, fentanyl or lidocaine, reduced sodium currents. These results suggest that morphine, fentanyl and oxycodone each produce the MOR-independent suppression of sodium currents by distinct mechanisms in thalamic neurons.
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Fletcher, Rebecca A; Callaway, Ragan M; Atwater, Daniel Z
2016-06-01
Exotic invasive plants can exert strong selective pressure for increased competitive ability in native plants. There are two fundamental components of competitive ability: suppression and tolerance, and the current paradigm that these components have equal influences on a species' overall competitive ability has been recently questioned. If these components do not have equal influences on overall ability, then selection on competitive tolerance and suppression may be disproportionate. We used naturally invaded communities to study the effects of selection caused by an invasive forb, Centaurea stoebe, on a native grass, Pseudoroegneria spicata. P. spicata plants were harvested from within dense C. stoebe patches and from nearby uninvaded areas, divided clonally into replicates, then transplanted into a common garden where they grew alone or competed with C. stoebe. We found that P. spicata plants collected from within C. stoebe patches were significantly more tolerant of competition with C. stoebe than P. spicata plants collected from uninvaded areas, but plants from inside invaded patches were not superior at suppressing C. stoebe. These results are consistent with the hypothesis that strong competitors may select for tolerance to competition more than for the ability to suppress neighbors. This has important implications for how native plant communities may respond to invasion over time, and how invasive and native species may ultimately coexist.
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Hoose, Scott A.; Duran, Camille; Malik, Indranil; Eslamfam, Shabnam; Shasserre, Samantha C.; Downing, S. Sabina; Hoover, Evelyn M.; Dowd, Katherine E.; Smith, Roger; Polymenis, Michael
2012-01-01
Screening chemical libraries to identify compounds that affect overall cell proliferation is common. However, in most cases, it is not known whether the compounds tested alter the timing of particular cell cycle transitions. Here, we evaluated an FDA-approved drug library to identify pharmaceuticals that alter cell cycle progression in yeast, using DNA content measurements by flow cytometry. This approach revealed strong cell cycle effects of several commonly used pharmaceuticals. We show that the antilipemic gemfibrozil delays initiation of DNA replication, while cells treated with the antidepressant fluoxetine severely delay progression through mitosis. Based on their effects on cell cycle progression, we also examined cell proliferation in the presence of both compounds. We discovered a strong suppressive interaction between gemfibrozil and fluoxetine. Combinations of interest among diverse pharmaceuticals are difficult to identify, due to the daunting number of possible combinations that must be evaluated. The novel interaction between gemfibrozil and fluoxetine suggests that identifying and combining drugs that show cell cycle effects might streamline identification of drug combinations with a pronounced impact on cell proliferation. PMID:22567160
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Hoose, Scott A; Duran, Camille; Malik, Indranil; Eslamfam, Shabnam; Shasserre, Samantha C; Downing, S Sabina; Hoover, Evelyn M; Dowd, Katherine E; Smith, Roger; Polymenis, Michael
2012-01-01
Screening chemical libraries to identify compounds that affect overall cell proliferation is common. However, in most cases, it is not known whether the compounds tested alter the timing of particular cell cycle transitions. Here, we evaluated an FDA-approved drug library to identify pharmaceuticals that alter cell cycle progression in yeast, using DNA content measurements by flow cytometry. This approach revealed strong cell cycle effects of several commonly used pharmaceuticals. We show that the antilipemic gemfibrozil delays initiation of DNA replication, while cells treated with the antidepressant fluoxetine severely delay progression through mitosis. Based on their effects on cell cycle progression, we also examined cell proliferation in the presence of both compounds. We discovered a strong suppressive interaction between gemfibrozil and fluoxetine. Combinations of interest among diverse pharmaceuticals are difficult to identify, due to the daunting number of possible combinations that must be evaluated. The novel interaction between gemfibrozil and fluoxetine suggests that identifying and combining drugs that show cell cycle effects might streamline identification of drug combinations with a pronounced impact on cell proliferation.
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The neural basis of suppression and amblyopia in strabismus.
Sengpiel, F; Blakemore, C
1996-01-01
The neurophysiological consequences of artificial strabismus in cats and monkeys have been studied for 30 years. However, until very recently no clear picture has emerged of neural deficits that might account for the powerful interocular suppression that strabismic humans experience, nor for the severe amblyopia that is often associated with convergent strabismus. Here we review the effects of squint on the integrative capacities of the primary visual cortex and propose a hypothesis about the relationship between suppression and amblyopia. Most neurons in the visual cortex of normal cats and monkeys can be excited through either eye and show strong facilitation during binocular stimulation with contours of similar orientation in the two eyes. But in strabismic animals, cortical neurons tend to fall into two populations of monocularly excitable cells and exhibit suppressive binocular interactions that share key properties with perceptual suppression in strabismic humans. Such interocular suppression, if prolonged and asymmetric (with input from the squinting eye habitually suppressed by that from the fixating eye), might lead to neural defects in the representation of the deviating eye and hence to amblyopia.
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Effects of hypnotic bromovalerylurea on microglial BV2 cells.
Kawasaki, Shun; Abe, Naoki; Ohtake, Fumito; Islam, Afsana; Choudhury, Mohammed Emamussalehin; Utsunomiya, Ryo; Kikuchi, Satoshi; Nishihara, Tasuku; Kuwabara, Jun; Yano, Hajime; Watanabe, Yuji; Aibiki, Mayuki; Yorozuya, Toshihiro; Tanaka, Junya
2017-06-01
An old sedative and hypnotic bromovalerylurea (BU) has anti-inflammatory effects. BU suppressed nitric oxide (NO) release and proinflammatory cytokine expression by lipopolysaccharide (LPS)-treated BV2 cells, a murine microglial cell line. However, BU did not inhibit LPS-induced nuclear translocation of nuclear factor-κB and subsequent transcription. BU suppressed LPS-induced phosphorylation of signal transducer and activator of transcription 1 (STAT1) and expression of interferon regulatory factor 1 (IRF1). The Janus kinase 1 (JAK1) inhibitor filgotinib suppressed the NO release much more weakly than that of BU, although filgotinib almost completely prevented LPS-induced STAT1 phosphorylation. Knockdown of JAK1, STAT1, or IRF1 did not affect the suppressive effects of BU on LPS-induced NO release by BV2 cells. A combination of BU and filgotinib synergistically suppressed the NO release. The mitochondrial complex I inhibitor rotenone, which did not prevent STAT1 phosphorylation or IRF1 expression, suppressed proinflammatory mediator expression less significantly than BU. BU and rotenone reduced intracellular ATP (iATP) levels to a similar extent. A combination of rotenone and filgotinib suppressed NO release by LPS-treated BV2 cells as strongly as BU. These results suggest that anti-inflammatory actions of BU may be attributable to the synergism of inhibition of JAK1/STAT1-dependent pathways and reduction in iATP level. Copyright © 2017 The Authors. Production and hosting by Elsevier B.V. All rights reserved.
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Antibacterial agent triclosan suppresses RBL-2H3 mast cell function
DOE Office of Scientific and Technical Information (OSTI.GOV)
Palmer, Rachel K., E-mail: rachel.palmer@maine.edu; Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME 04469; Hutchinson, Lee M.
2012-01-01
Triclosan is a broad-spectrum antibacterial agent, which has been shown previously to alleviate human allergic skin disease. The purpose of this study was to investigate the hypothesis that the mechanism of this action of triclosan is, in part, due to effects on mast cell function. Mast cells play important roles in allergy, asthma, parasite defense, and carcinogenesis. In response to various stimuli, mast cells degranulate, releasing allergic mediators such as histamine. In order to investigate the potential anti-inflammatory effect of triclosan on mast cells, we monitored the level of degranulation in a mast cell model, rat basophilic leukemia cells, clonemore » 2H3. Having functional homology to human mast cells, as well as a very well defined signaling pathway leading to degranulation, this cell line has been widely used to gain insight into mast-cell driven allergic disorders in humans. Using a fluorescent microplate assay, we determined that triclosan strongly dampened the release of granules from activated rat mast cells starting at 2 μM treatment, with dose-responsive suppression through 30 μM. These concentrations were found to be non-cytotoxic. The inhibition was found to persist when early signaling events (such as IgE receptor aggregation and tyrosine phosphorylation) were bypassed by using calcium ionophore stimulation, indicating that the target for triclosan in this pathway is likely downstream of the calcium signaling event. Triclosan also strongly suppressed F-actin remodeling and cell membrane ruffling, a physiological process that accompanies degranulation. Our finding that triclosan inhibits mast cell function may explain the clinical data mentioned above and supports the use of triclosan or a mechanistically similar compound as a topical treatment for allergic skin disease, such as eczema. -- Highlights: ►The effects of triclosan on mast cell function using a murine mast cell model. ►Triclosan strongly inhibits degranulation of mast cells. ►Triclosan suppresses membrane ruffling of activated mast cells. ►Triclosan's effects persist when early mast cell signaling events are bypassed. ►Supports use of triclosan as a topical treatment for eczema.« less
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Suppression of soybean aphid by generalist predators results in a trophic cascade in soybeans.
Costamagna, Alejandro C; Landis, Douglas A; Difonzo, Christina D
2007-03-01
Top-down regulation of herbivores in terrestrial ecosystems is pervasive and can lead to trophic cascades that release plants from herbivory. Due to their relatively simplified food webs, agroecosystems may be particularly prone to trophic cascades, a rationale that underlies biological control. However, theoretical and empirical studies show that, within multiple enemy assemblages, intraguild predation (IGP) may lead to a disruption of top-down control by predators. We conducted a factorial field study to test the separate and combined effects of predators and parasitoids in a system with asymmetric IGP. Specifically we combined ambient levels of generalist predators (mainly Coccinellidae) of the soybean aphid, Aphis glycines Matsumura, with controlled releases of the native parasitoid Lysiphlebus testaceipes (Cresson) and measured their impact on aphid population growth and soybean biomass and yield. We found that generalist predators provided strong, season-long aphid suppression, which resulted in a trophic cascade that doubled soybean biomass and yield. However, contrary to our expectations, L. testaceipes provided minor aphid suppression and only when predators were excluded, which resulted in nonadditive effects when both groups were combined. We found direct and indirect evidence of IGP, but because percentage parasitism did not differ between predator exclusion and ambient predator treatments, we concluded that IGP did not disrupt parasitism during this study. Our results support theoretical predictions that intraguild predators which also provide strong herbivore suppression do not disrupt top-down control of herbivores.
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Kato, Taigo; Inoue, Hiroyuki; Imoto, Seiya; Tamada, Yoshinori; Miyamoto, Takashi; Matsuo, Yo; Nakamura, Yusuke; Park, Jae-Hyun
2016-01-01
T–lymphokine-activated killer cell–originated protein kinase (TOPK) and maternal embryonic leucine zipper kinase (MELK) have been reported to play critical roles in cancer cell proliferation and maintenance of stemness. In this study, we investigated possible roles of TOPK and MELK in kidney cancer cells and found their growth promotive effect as well as some feedback mechanism between these two molecules. Interestingly, the blockade of either of these two kinases effectively caused downregulation of forkhead box protein M1 (FOXM1) activity which is known as an oncogenic transcriptional factor in various types of cancer cells. Small molecular compound inhibitors against TOPK (OTS514) and MELK (OTS167) effectively suppressed the kidney cancer cell growth, and the combination of these two compounds additively worked and showed the very strong growth suppressive effect on kidney cancer cells. Collectively, our results suggest that both TOPK and MELK are promising molecular targets for kidney cancer treatment and that dual blockade of OTS514 and OTS167 may bring additive anti-tumor effects with low risk of side effects. PMID:26933922
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Kato, Taigo; Inoue, Hiroyuki; Imoto, Seiya; Tamada, Yoshinori; Miyamoto, Takashi; Matsuo, Yo; Nakamura, Yusuke; Park, Jae-Hyun
2016-04-05
T-lymphokine-activated killer cell-originated protein kinase (TOPK) and maternal embryonic leucine zipper kinase (MELK) have been reported to play critical roles in cancer cell proliferation and maintenance of stemness. In this study, we investigated possible roles of TOPK and MELK in kidney cancer cells and found their growth promotive effect as well as some feedback mechanism between these two molecules. Interestingly, the blockade of either of these two kinases effectively caused downregulation of forkhead box protein M1 (FOXM1) activity which is known as an oncogenic transcriptional factor in various types of cancer cells. Small molecular compound inhibitors against TOPK (OTS514) and MELK (OTS167) effectively suppressed the kidney cancer cell growth, and the combination of these two compounds additively worked and showed the very strong growth suppressive effect on kidney cancer cells. Collectively, our results suggest that both TOPK and MELK are promising molecular targets for kidney cancer treatment and that dual blockade of OTS514 and OTS167 may bring additive anti-tumor effects with low risk of side effects.
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Cooperative Effects in Closely Packed Quantum Emitters with Collective Dephasing
NASA Astrophysics Data System (ADS)
Prasanna Venkatesh, B.; Juan, M. L.; Romero-Isart, O.
2018-01-01
In a closely packed ensemble of quantum emitters, cooperative effects are typically suppressed due to the dephasing induced by the dipole-dipole interactions. Here, we show that by adding sufficiently strong collective dephasing, cooperative effects can be restored. Specifically, we show that the dipole force on a closely packed ensemble of strongly driven two-level quantum emitters, which collectively dephase, is enhanced in comparison to the dipole force on an independent noninteracting ensemble. Our results are relevant to solid-state systems with embedded quantum emitters such as color centers in diamond and superconducting qubits in microwave cavities and waveguides.
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Enhancement of runaway production by resonant magnetic perturbation on J-TEXT
NASA Astrophysics Data System (ADS)
Chen, Z. Y.; Huang, D. W.; Izzo, V. A.; Tong, R. H.; Jiang, Z. H.; Hu, Q. M.; Wei, Y. N.; Yan, W.; Rao, B.; Wang, S. Y.; Ma, T. K.; Li, S. C.; Yang, Z. J.; Ding, D. H.; Wang, Z. J.; Zhang, M.; Zhuang, G.; Pan, Y.; J-TEXT Team
2016-07-01
The suppression of runaways following disruptions is key for the safe operation of ITER. The massive gas injection (MGI) has been developed to mitigate heat loads, electromagnetic forces and runaway electrons (REs) during disruptions. However, MGI may not completely prevent the generation of REs during disruptions on ITER. Resonant magnetic perturbation (RMP) has been applied to suppress runaway generation during disruptions on several machines. It was found that strong RMP results in the enhancement of runaway production instead of runaway suppression on J-TEXT. The runaway current was about 50% pre-disruption plasma current in argon induced reference disruptions. With moderate RMP, the runway current decreased to below 30% pre-disruption plasma current. The runaway current plateaus reach 80% of the pre-disruptive current when strong RMP was applied. Strong RMP may induce large size magnetic islands that could confine more runaway seed during disruptions. This has important implications for runaway suppression on large machines.
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Chourasia, T K; Joy, K P
2010-12-12
A radiometric assay was used to measure microsomal EH activity from tritiated H(2)O formed during the conversion of [2,4 (3)H] estradiol-17β into catecholestrogens in the microsomal fractions of liver, brain and ovary of the catfish Heteropneustes fossilis. The validation data show that enzyme activity increased with incubation time, and substrate and cofactor (NADPH) concentrations, elicited temperature optima of 30-37°C and pH optima of 6.8-7.8. EH activity was strongly NADPH-dependent and in its absence only 13.48% activity was recorded. Liver recorded the highest enzyme activity, followed by brain and ovary. EH activity showed a significant seasonal variation with the peak activity in spawning phase and the lowest activity in resting phase. In the ovary, the follicular layer (theca and granulosa) elicited the highest activity over that of the denuded oocytes. Modulatory effects of steroids on ovarian enzyme activity were further demonstrated. The incubation of postvitellogenic follicles with 1, 10 or 100 nM concentrations of various steroids for 24 h produced varied effects on EH activity. Progesterone and 2-hydroxyestradiol-17β elicited strong suppressive effects on enzyme activity. Estrogens (E(1), E(2) and E(3)) suppressed the activity in a concentration-dependent manner. Among the progestins tested, 17,20α-dihydroxy-4-pregnen-3-one, the isomer of 17,20β-dihydroxy-4-pregnen-3-one (a teleost maturation-inducing steroid) showed the lowest depressing effect. Among androgens, the testosterone metabolite 11-ketotestosterone (functional teleost androgen) showed a high suppressing effect. Corticosteroids elicited low activity with cortisol suppressed the activity at higher concentrations. The study will form a basis to understand the physiological role of catecholestrogens in ovarian functions. Copyright © 2010 Elsevier Inc. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Kim, Hwan; Translational Research Center for Protein Function Control; Kim, Nam Doo
2013-07-26
Highlights: •FAK signaling cascade in cancer cells is profoundly inhibited by methyl violet 2B. •Methyl violet 2B identified by virtual screening is a novel allosteric FAK inhibitor. •Methyl violet 2B possesses extremely high kinase selectivity. •Methyl violet 2B suppresses strongly the proliferation of cancer cells. •Methyl violet 2B inhibits focal adhesion, invasion and migration of cancer cells. -- Abstract: The focal adhesion kinase (FAK) signaling cascade in cancer cells was profoundly inhibited by methyl violet 2B identified with the structure-based virtual screening. Methyl violet 2B was shown to be a non-competitive inhibitor of full-length FAK enzyme vs. ATP. It turnedmore » out that methyl violet 2B possesses extremely high kinase selectivity in biochemical kinase profiling using a large panel of kinases. Anti-proliferative activity measurement against several different cancer cells and Western blot analysis showed that this substance is capable of suppressing significantly the proliferation of cancer cells and is able to strongly block FAK/AKT/MAPK signaling pathways in a dose dependent manner at low nanomolar concentration. Especially, phosphorylation of Tyr925-FAK that is required for full activation of FAK was nearly completely suppressed even with 1 nM of methyl violet 2B in A375P cancer cells. To the best of our knowledge, it has never been reported that methyl violet possesses anti-cancer effects. Moreover, methyl violet 2B significantly inhibited FER kinase phosphorylation that activates FAK in cell. In addition, methyl violet 2B was found to induce cell apoptosis and to exhibit strong inhibitory effects on the focal adhesion, invasion, and migration of A375P cancer cells at low nanomolar concentrations. Taken together, these results show that methyl violet 2B is a novel, potent and selective blocker of FAK signaling cascade, which displays strong anti-proliferative activities against a variety of human cancer cells and suppresses adhesion/migration/invasion of tumor cells.« less
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Poon, Gary T; Maherali, Hafiz
2015-01-01
The widespread invasion of the nonmycorrhizal biennial plant, Alliaria petiolata in North America is hypothesized to be facilitated by the production of novel biochemical weapons that suppress the growth of mycorrhizal fungi. As a result, A. petiolata is expected to be a strong competitor against plant species that rely on mycorrhizal fungi for nutrient uptake services. If A. petiolata is also a strong competitor for soil resources, it should deplete nutrients to levels lower than can be tolerated by weaker competitors. Because the negative effect of losing the fungal symbiont for mycorrhizal plants is greatest when nutrients are low, the ability of A. petiolata to simultaneously suppress fungi and efficiently take up soil nutrients should further strengthen its competitive ability against mycorrhizal plants. To test this hypothesis, we grew 27 mycorrhizal tree, forb and grass species that are representative of invaded habitats in the absence or presence of competition with A. petiolata in soils that had previously been experimentally planted with the invader or left as a control. A history of A. petiolata in soil reduced plant available forms of nitrogen by >50% and phosphorus by 17% relative to control soil. Average mycorrhizal colonization of competitor species was reduced by >50% in A. petiolata history versus control soil. Contrary to expectations, competition between A. petiolata and other species was stronger in control than history soil. The invader suppressed the biomass of 70% of competitor species in control soil but only 26% of species in history soil. In addition, A. petiolata biomass was reduced by 56% in history versus control soil, whereas the average biomass of competitor species was reduced by 15%. Thus, our results suggest that the negative effect of nutrient depletion on A. petiolata was stronger than the negative effect of suppressing mycorrhizal colonization on competitor species. These findings indicate that the inhibitory potential of A. petiolata on competitor species via mycorrhizal suppression is not enhanced under nutrient limitation.
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Poon, Gary T.
2015-01-01
The widespread invasion of the nonmycorrhizal biennial plant, Alliaria petiolata in North America is hypothesized to be facilitated by the production of novel biochemical weapons that suppress the growth of mycorrhizal fungi. As a result, A. petiolata is expected to be a strong competitor against plant species that rely on mycorrhizal fungi for nutrient uptake services. If A. petiolata is also a strong competitor for soil resources, it should deplete nutrients to levels lower than can be tolerated by weaker competitors. Because the negative effect of losing the fungal symbiont for mycorrhizal plants is greatest when nutrients are low, the ability of A. petiolata to simultaneously suppress fungi and efficiently take up soil nutrients should further strengthen its competitive ability against mycorrhizal plants. To test this hypothesis, we grew 27 mycorrhizal tree, forb and grass species that are representative of invaded habitats in the absence or presence of competition with A. petiolata in soils that had previously been experimentally planted with the invader or left as a control. A history of A. petiolata in soil reduced plant available forms of nitrogen by >50% and phosphorus by 17% relative to control soil. Average mycorrhizal colonization of competitor species was reduced by >50% in A. petiolata history versus control soil. Contrary to expectations, competition between A. petiolata and other species was stronger in control than history soil. The invader suppressed the biomass of 70% of competitor species in control soil but only 26% of species in history soil. In addition, A. petiolata biomass was reduced by 56% in history versus control soil, whereas the average biomass of competitor species was reduced by 15%. Thus, our results suggest that the negative effect of nutrient depletion on A. petiolata was stronger than the negative effect of suppressing mycorrhizal colonization on competitor species. These findings indicate that the inhibitory potential of A. petiolata on competitor species via mycorrhizal suppression is not enhanced under nutrient limitation. PMID:26213654
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Suppression of runaway electrons with a resonant magnetic perturbation in MST tokamak plasmas
NASA Astrophysics Data System (ADS)
Munaretto, Stefano; Chapman, B. E.; Almagri, A. F.; Cornille, B. S.; Dubois, A. M.; Goetz, J. A.; McCollam, K. J.; Sovinec, C. R.
2016-10-01
Runaway electrons generated in MST tokamak plasmas are now being probed with resonant magnetic perturbations (RMP's). An RMP with m =3 strongly suppresses the runaway electrons. Initial modeling of these plasmas with NIMROD shows the degradation of flux surfaces with an m =3 RMP, which may account for the runaway electron suppression. These MST tokamak plasmas have Bt =0.14 T, Ip =50kA, and q(a) =2.2, with a bulk electron density and temperature of 5x1017 m-3 and 150 eV. Runaway electrons are detected via x-ray emission. The RMP is produced by a poloidal array of 32 saddle coils at the narrow vertical insulated cut in MST's thick conducting shell. Each RMP has a single m but a broad n spectrum. A sufficiently strong m =3 RMP completely suppresses the runaway electrons, while a comparable m =1 RMP has little effect. The impact of the RMP's on the magnetic topology of these plasmas is being studied with the nonlinear MHD code, NIMROD. With an m =3 RMP, stochasticity is introduced in the outer third of the plasma. No such change is observed with the m =1 RMP. NIMROD also predicts regularly occurring sawtooth oscillations with a period comparable to MHD activity observed in the experiment. Work supported by USDOE.
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Presence of pups suppresses hunger-induced feeding in virgin adult mice of both sexes.
Han, Ying; Li, Xing-Yu; Wang, Shao-Ran; Wei, Yi-Chao; Xu, Xiao-Hong
2017-10-24
Despite recent progress on neural pathways underlying individual behaviors, how an animal balances and prioritizes behavioral outputs remains poorly understood. While studying the relationship between hunger-induced feeding and pup-induced maternal behaviors in virgin female mice, we made the unexpected discovery that presence of pups strongly delayed and decreased food consumption. Strikingly, presence of pups also suppressed feeding induced by optogenetic activation of Agrp neurons. Such a suppressive effect inversely correlated with the extents of maternal behaviors, but did not rely on the display of these behaviors, and was also present in virgin males. Furthermore, chemogenetic activation of Vglut2+ neurons in the medial preoptic area (mPOA), a region critical for maternal behaviors and motivation, was sufficient to suppress hunger-induced feeding. However, muscimol inhibition of the mPOA, while disrupting maternal behaviors, did not prevent pup suppression of feeding, indicating that neural pathways in other brain regions may also mediate such an effect. Together, these results provide novel insights into neural coordination of pup care and feeding in mice and organizations of animal behaviors in general. Copyright © 2017. Published by Elsevier Ltd.
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NASA Astrophysics Data System (ADS)
Kuzmenko, Alexey B.
We measure broadband far-infrared magneto-optical conductivity spectra of pure bismuth separately for left- and right-handed circular polarizations in magnetic fields up to 7 T that allows us to obtain the magnetic circular dichroism (MCD). Thanks to a high spectral resolution we distinguish the Landau level (LL) transitions in the Dirac-like electron and the parabolic hole bands. The hole transitions exhibit a full (100%) MCD as is indeed expected for a circular cyclotron orbit. However, the MCD for electron-pocket transitions is reduced to only 13 +/-1%. This strong suppression can be attributed to the huge effective-mass anisotropy ( 200) in the electron pockets and can be generally interpreted as a signature of the mismatch between the spatial metric experienced by the photons and the electrons. An important consequence of this observation is that the magneto-absorption in bismuth is highly valley sensitive, which paves the way to future valleytronic applications in materials with a strong effective-mass anisotropy.
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NASA Astrophysics Data System (ADS)
Hanai, Ryo; Littlewood, Peter B.; Ohashi, Yoji
2018-06-01
We investigate theoretically nonequilibrium effects on photoluminescence and gain/absorption spectra of a driven-dissipative exciton-polariton condensate, by employing the combined Hartree-Fock-Bogoliubov theory with the generalized random phase approximation extended to the Keldysh formalism. Our calculated photoluminescence spectra is in semiquantitative agreement with experiments, where features such as a blue shift of the emission from the condensate, the appearance of the dispersionless feature of a diffusive Goldstone mode, and the suppression of the dispersive profile of the mode are obtained. We show that the nonequilibrium nature of the exciton-polariton condensate strongly suppresses the visibility of the Bogoliubov dispersion in the negative energy branch (ghost branch) in photoluminescence spectra. We also show that the trace of this branch can be captured as a hole burning effect in gain/absorption spectra. Our results indicate that the nonequilibrium nature of the exciton-polariton condensate strongly reduces quantum depletion, while a scattering channel to the ghost branch is still present.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Takatani-Nakase, Tomoka, E-mail: nakase@mukogawa-u.ac.jp; Takahashi, Koichi, E-mail: koichi@mukogawa-u.ac.jp
Caspase-independent, non-apoptotic cell death is an important therapeutic target in myocardial ischemia. Leptin, an adipose-derived hormone, is known to exhibit cytoprotective effects on the ischemic heart, but the mechanisms are poorly understood. In this research, we found that pretreatment of leptin strongly suppressed ischemic-augmented nuclear shrinkage and non-apoptotic cell death on cardiomyocytes. Leptin was also shown to significantly inhibit the activity of iPLA{sub 2}, which is considered to play crucial roles in non-apoptotic cell death, resulting in effective prevention of ischemia-induced myocyte death. These findings provide the first evidence of a protective mechanism of leptin against ischemia-induced non-apoptotic cardiomyocyte death.more » - Highlights: • Myocardial ischemia-model induces in caspase-independent, non-apoptotic cell death. • Leptin strongly inhibits ischemic-augmented non-apoptotic cell death. • Leptin reduces iPLA{sub 2} activity, leading to avoidance of non-apoptotic cell death.« less
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Suppression of thermally excited capillary waves by shear flow.
Derks, Didi; Aarts, Dirk G A L; Bonn, Daniel; Lekkerkerker, Henk N W; Imhof, Arnout
2006-07-21
We investigate the thermal fluctuations of the colloidal gas-liquid interface subjected to a shear flow parallel to the interface. Strikingly, we find that the shear strongly suppresses capillary waves, making the interface smoother. This phenomenon can be described by introducing an effective interfacial tension that increases with the shear rate. The increase of sigma(eff) is a direct consequence of the loss of interfacial entropy caused by the flow, which affects especially the slow fluctuations. This demonstrates that the interfacial tension of fluids results from an intrinsic as well as a fluctuation contribution.
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GABA predicts visual intelligence.
Cook, Emily; Hammett, Stephen T; Larsson, Jonas
2016-10-06
Early psychological researchers proposed a link between intelligence and low-level perceptual performance. It was recently suggested that this link is driven by individual variations in the ability to suppress irrelevant information, evidenced by the observation of strong correlations between perceptual surround suppression and cognitive performance. However, the neural mechanisms underlying such a link remain unclear. A candidate mechanism is neural inhibition by gamma-aminobutyric acid (GABA), but direct experimental support for GABA-mediated inhibition underlying suppression is inconsistent. Here we report evidence consistent with a global suppressive mechanism involving GABA underlying the link between sensory performance and intelligence. We measured visual cortical GABA concentration, visuo-spatial intelligence and visual surround suppression in a group of healthy adults. Levels of GABA were strongly predictive of both intelligence and surround suppression, with higher levels of intelligence associated with higher levels of GABA and stronger surround suppression. These results indicate that GABA-mediated neural inhibition may be a key factor determining cognitive performance and suggests a physiological mechanism linking surround suppression and intelligence. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Blanco-Pillado, Jose J.; Frazer, Jonathan; Sousa, Kepa
Power suppression of the cosmic microwave background on the largest observable scales could provide valuable clues about the particle physics underlying inflation. Here we consider the prospect of power suppression in the context of the multifield landscape. Based on the assumption that our observable universe emerges from a tunnelling event and that the relevant features originate purely from inflationary dynamics, we find that the power spectrum not only contains information on single-field dynamics, but also places strong constraints on all scalar fields present in the theory. We find that the simplest single-field models giving rise to power suppression do notmore » generalise to multifield models in a straightforward way, as the resulting superhorizon evolution of the curvature perturbation tends to erase any power suppression present at horizon crossing. On the other hand, multifield effects do present a means of generating power suppression which to our knowledge has so far not been considered. We propose a mechanism to illustrate this, which we dub flume inflation.« less
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Arina, Ainhoa; Schreiber, Karin; Binder, David C.; Karrison, Theodore; Liu, Rebecca B.; Schreiber, Hans
2014-01-01
Myeloid-derived CD11b+Gr1+ suppressor cells (MDSC) and tumor-associated macrophages (TAM) are considered a major obstacle for effective adoptive T cell therapy. Myeloid cells suppress naive T cell proliferation ex vivo and can prevent the generation of T cell responses in vivo. We find, however, that immune T cells adoptively transferred eradicate well-established tumors in the presence of MDSC and TAM which are strongly immunosuppressive ex vivo. These MDSC and TAM were comparable in levels and immunosuppression among different tumor models. Longitudinal microscopy of tumors in vivo revealed that after T cell transfer tumor vasculature and cancer cells disappeared simultaneously. During T-cell mediated tumor destruction, the tumor stroma contained abundant myeloid cells (mainly TAM) that retained their suppressive properties. Preimmunized but not naive mice resisted immune suppression caused by an unrelated tumor-burden supporting the idea that in vivo, myeloid immunosuppressive cells can suppress naive but not memory T cell responses. PMID:24367029
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NASA Astrophysics Data System (ADS)
Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Veres, G. I.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wysłouch, B.; Zhang, J.
Transverse momentum spectra of charged hadrons with pT < 6 GeV/c have been measured near mid-rapidity (0.2 < ɛ < 1.4) by the PHOBOS experiment at RHIC in Au + Au and d + Au collisions at {√ {s{NN}} = {200 GeV}}. The spectra for different collision centralities are compared to {p + ¯ {p}} collisions at the same energy. The resulting nuclear modification factor for central Au + Au collisions shows evidence of strong suppression of charged hadrons in the high-pT region (>2 GeV/c). In contrast, the d + Au nuclear modification factor exhibits no suppression of the high-pT yields. These measurements suggest a large energy loss of the high-pT particles in the highly interacting medium created in the central Au + Au collisions. The lack of suppression in d + Au collisions suggests that it is unlikely that initial state effects can explain the suppression in the central Au + Au collisions. PACS: 25.75.-q
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Rassin, E; Muris, P; Schmidt, H; Merckelbach, H
2000-09-01
Research has shown that there are strong similarities in content between the obsessions and compulsions that characterize obsessive-compulsive disorder and nonclinical obsessions and compulsions. However, clinical and nonclinical obsessions and compulsions do differ with respect to characteristics like frequency, intensity, discomfort and elicited resistance. Two separate concepts have been invoked to explain how normal obsessions and compulsions may develop into clinical phenomena. First, it is suggested that thought-action fusion (TAF) contributes to obsessive-compulsive symptoms. Second, thought suppression may intensify obsessive-compulsive symptoms due to its paradoxical effect on intrusive thoughts. Although both phenomena have been found to contribute to obsessive-compulsive symptoms, possible interactions between these two have never been investigated. The current study explored how TAF and thought suppression interact in the development of obsessive-compulsive symptoms. Undergraduate psychology students (N = 173) completed questionnaires pertaining to TAF, thought suppression and obsessive-compulsive symptoms. Covariances between the scores on these questionnaires were analyzed by means of structural equation modeling. Results suggest that TAF triggers thought suppression, while thought suppression, in turn, promotes obsessive-compulsive symptoms.
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The status of the strong coupling from tau decays in 2016
NASA Astrophysics Data System (ADS)
Boito, Diogo; Golterman, Maarten; Maltman, Kim; Peris, Santiago
2017-06-01
While the idea of using the operator product expansion (OPE) to extract the strong coupling from hadronic τ decay data is not new, there is an ongoing controversy over how to include quark-hadron ;duality violations; (i.e., resonance effects) which are not described by the OPE. One approach attempts to suppress duality violations enough that they might become negligible, but pays the price of an uncontrolled OPE truncation. We critically examine a recent analysis using this approach and show that it fails to properly account for non-perturbative effects, making the resulting determination of the strong coupling unreliable. In a different approach duality violations are taken into account with a model, avoiding the OPE truncation. This second approach provides a self-consistent determination of the strong coupling from τ decays.
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Nakada, Chisako; Satoh, Shinya; Tabata, Yoko; Arai, Ken-ichi; Watanabe, Sumiko
2006-10-01
We identified zebra fish forkhead transcription factor l1 (zfoxl1) as a gene strongly expressed in neural tissues such as midbrain, hindbrain, and the otic vesicle at the early embryonic stage. Loss of the function of zfoxl1 effected by morpholino antisense oligonucleotide resulted in defects in midbrain and eye development, and in that of formation of the pectoral fins. Interestingly, ectopic expression of shh in the midbrain and elevated pax2a expression in the optic stalk were observed in foxl1 MO-injected embryos. In contrast, expression of pax6a, which is negatively regulated by shh, was suppressed in the thalamus and pretectum regions, supporting the idea of augmentation of the shh signaling pathway by suppression of foxl1. Expression of zfoxl1-EnR (repressing) rather than zfoxl1-VP16 (activating) resulted in a phenotype similar to that induced by foxl1-mRNA, suggesting that foxl1 may act as a transcriptional repressor of shh in zebra fish embryos. Supporting this notion, foxl1 suppressed isolated 2.7-kb shh promoter activity in PC12 cells, and the minimal region of foxl1 required for its transcriptional repressor activity showed strong homology with the groucho binding motif, which is found in genes encoding various homeodomain proteins. In view of all of our data taken together, we propose zfoxl1 to be a novel regulator of neural development that acts by suppressing shh expression.
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Nakada, Chisako; Satoh, Shinya; Tabata, Yoko; Arai, Ken-ichi; Watanabe, Sumiko
2006-01-01
We identified zebra fish forkhead transcription factor l1 (zfoxl1) as a gene strongly expressed in neural tissues such as midbrain, hindbrain, and the otic vesicle at the early embryonic stage. Loss of the function of zfoxl1 effected by morpholino antisense oligonucleotide resulted in defects in midbrain and eye development, and in that of formation of the pectoral fins. Interestingly, ectopic expression of shh in the midbrain and elevated pax2a expression in the optic stalk were observed in foxl1 MO-injected embryos. In contrast, expression of pax6a, which is negatively regulated by shh, was suppressed in the thalamus and pretectum regions, supporting the idea of augmentation of the shh signaling pathway by suppression of foxl1. Expression of zfoxl1-EnR (repressing) rather than zfoxl1-VP16 (activating) resulted in a phenotype similar to that induced by foxl1-mRNA, suggesting that foxl1 may act as a transcriptional repressor of shh in zebra fish embryos. Supporting this notion, foxl1 suppressed isolated 2.7-kb shh promoter activity in PC12 cells, and the minimal region of foxl1 required for its transcriptional repressor activity showed strong homology with the groucho binding motif, which is found in genes encoding various homeodomain proteins. In view of all of our data taken together, we propose zfoxl1 to be a novel regulator of neural development that acts by suppressing shh expression. PMID:16980626
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The Nematicidal Effect of Camellia Seed Cake on Root-Knot Nematode Meloidogyne javanica of Banana
Yang, Xiujuan; Wang, Xuan; Wang, Kang; Su, Lanxi; Li, Hongmei; Li, Rong; Shen, Qirong
2015-01-01
Suppression of root-knot nematodes is crucially important for maintaining the worldwide development of the banana industry. Growing concerns about human and environmental safety have led to the withdrawal of commonly used nematicides and soil fumigants, thus motivating the development of alternative nematode management strategies. In this study, Meloidogyne javanica was isolated, and the nematicidal effect of Camellia seed cake on this pest was investigated. The results showed that in dish experiments, Camellia seed cake extracts under low concentration (2 g/L) showed a strong nematicidal effect. After treatment for 72 h, the eggs of M. javanica were gradually dissolved, and the intestine of the juveniles gradually became indistinct. Nematicidal compounds, including saponins identified by HPLC-ESI-MS and 8 types of volatile compounds identified by GC-MS, exhibited effective nematicidal activities, especially 4-methylphenol. The pot experiments demonstrated that the application of Camellia seed cake suppressed M. javanica, and promoted the banana plant growth. This study explored an effective nematicidal agent for application in soil and revealed its potential mechanism of nematode suppression. PMID:25849382
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Reversal of infectious mononucleosis-associated suppressor T cell activity by D-mannose
1983-01-01
Epstein-Barr virus-induced infectious mononucleosis (IM) is associated with the activation of suppressor T lymphocytes that profoundly inhibit immunoglobulin (Ig) production in vitro. We have examined the nature of signals operating in the interaction between IM suppressor T cells and their targets, and explored the possibility that a lectin-like receptor molecule and its specific sugar might provide specificity to this interaction. When D-mannose or some of its derivatives, including alpha- methyl-D-mannoside, mannose-6-phosphate, and mannan, were added to suppressed cultures containing IM T lymphocytes and pokeweed mitogen (PWM)-stimulated normal mononuclear cells, a significant enhancement of Ig production was observed. These sugars had little or no effect on Ig production by the PWM-stimulated responder cells alone and thus the enhanced Ig production could be attributed to the reversal of suppression in the co-cultures by these sugars. This was further confirmed by the observation that the sugars were effective only if present during the first 24 h of culture, a time when IM suppressor T cells exert their principal effect. The effect of sugars on Ig production by suppressed cultures was similar to that achieved by decreasing by about fourfold the number of IM T cells in culture. The effect of the sugars is unlikely to represent a form of nonspecific toxicity, since inhibited cultures become responders in the presence of the sugar. Furthermore, toxicity restricted to the suppressor T cells is unlikely, since preincubation of the T cells with the sugars did not reduce their subsequent ability to suppress in secondary indicator cultures. In addition, there was no correlation between the effect of the sugars on T cell proliferation and their effect on T cell-mediated suppression. The reversal of suppression by sugars was dose dependent and demonstrated stereo-specificity in that L-mannose was without effect while D-mannose reversed suppression. These data indicate that D- mannose and some of its derivatives consistently reverse suppression of Ig production by IM T cells and strongly suggest a role for saccharides as critical components in the cellular receptors involved in certain physiologic immune cell interactions. PMID:6225821
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Tsujita, Takahiro; Takaku, Takeshi; Suzuki, Tsuneo
2008-02-01
Inhibitors of carbohydrate-hydrolyzing enzyme play an important role to control postprandial blood glucose levels. In this paper, we investigated the effect of an ethanol extract from chestnut astringent skin (CAS) on alpha-amylase. Chestnut astringent skin extract strongly inhibited human and porcine pancreatic alpha-amylase. We also investigated the effect of CAS extract on carbohydrate absorption in rats and humans. Oral administration of CAS extract to normal rats fed corn starch (2 g/kg body weight), significantly suppressed the increase of blood glucose levels after starch loading in a dose-dependent manner. The effective dose of CAS extract required to achieve 20 and 40% suppression of the rise in blood glucose level was estimated to be 40 and 155 mg/kg body weight, respectively. Chestnut astringent skin extract also suppressed the rise in plasma insulin level and the fall in plasma non-esterified fatty acid level. In the type 2 diabetic rat model, CAS extract significantly suppressed the rise in blood glucose level after starch loading in a dose-dependent manner. Chestnut astringent skin extract also suppressed the rise in plasma glucose level after boiled rice loading in a dose-dependent manner in humans. The amount of CAS extract required to achieve 11 and 23% suppression in the rise in plasma glucose level was 300 and 600 mg/person, respectively. These results suggest that CAS extract retards absorption of carbohydrate and reduces post-prandial hyperglycemia.
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Granzow, Kara
2014-06-01
In the early-twenty-first century, extended cycle oral contraception (ECOC) became available by physician prescription in North America. Researchers speculate that this drug, with its capacity to reduce or eliminate menstrual bleeding, may shift not only women's biological processes but also their experiences of menstruation. In this paper, I discuss women's experiences of menstrual suppression drawing on findings from a qualitative study conducted before ECOC was available, and examine these findings against recently published research on menstrual suppression in an ECOC era. Findings suggest that the body as a natural entity figures strongly in women's discourses on suppression. They further suggest that suppression is a contingent, paradoxical and practical achievement, not a securely or fully realised embodied state. This paper reads women's accounts of menstrual suppression prior to ECOC as a challenge to the modern artifice of a mind/body split, and questions whether this challenge is perhaps made less discernible in an ECOC era, where attention may no longer be paid to the daily practices of menstrual suppression. Hence, a case is made for the varied political effects of ongoing non-menstruation versus event-specific practices of non-menstruation.
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Deconstructing continuous flash suppression
Yang, Eunice; Blake, Randolph
2012-01-01
In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular “Mondrian” CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS. PMID:22408039
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Deconstructing continuous flash suppression.
Yang, Eunice; Blake, Randolph
2012-03-08
In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular "Mondrian" CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS.
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2014-01-01
Introduction Transforming growth factor-βs (TGF-βs) play a dual role in breast cancer, with context-dependent tumor-suppressive or pro-oncogenic effects. TGF-β antagonists are showing promise in early-phase clinical oncology trials to neutralize the pro-oncogenic effects. However, there is currently no way to determine whether the tumor-suppressive effects of TGF-β are still active in human breast tumors at the time of surgery and treatment, a situation that could lead to adverse therapeutic responses. Methods Using a breast cancer progression model that exemplifies the dual role of TGF-β, promoter-wide chromatin immunoprecipitation and transcriptomic approaches were applied to identify a core set of TGF-β-regulated genes that specifically reflect only the tumor-suppressor arm of the pathway. The clinical significance of this signature and the underlying biology were investigated using bioinformatic analyses in clinical breast cancer datasets, and knockdown validation approaches in tumor xenografts. Results TGF-β-driven tumor suppression was highly dependent on Smad3, and Smad3 target genes that were specifically enriched for involvement in tumor suppression were identified. Patterns of Smad3 binding reflected the preexisting active chromatin landscape, and target genes were frequently regulated in opposite directions in vitro and in vivo, highlighting the strong contextuality of TGF-β action. An in vivo-weighted TGF-β/Smad3 tumor-suppressor signature was associated with good outcome in estrogen receptor-positive breast cancer cohorts. TGF-β/Smad3 effects on cell proliferation, differentiation and ephrin signaling contributed to the observed tumor suppression. Conclusions Tumor-suppressive effects of TGF-β persist in some breast cancer patients at the time of surgery and affect clinical outcome. Carefully tailored in vitro/in vivo genomic approaches can identify such patients for exclusion from treatment with TGF-β antagonists. PMID:24890385
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Magnetic annihilation of the dark mode in a strongly coupled bright-dark terahertz metamaterial.
Manjappa, Manukumara; Turaga, Shuvan Prashant; Srivastava, Yogesh Kumar; Bettiol, Andrew Anthony; Singh, Ranjan
2017-06-01
Dark mode in metamaterials has become a vital component in determining the merit of the Fano type of interference in the system. Its strength dictates the enhancement and suppression in the amplitude and Q-factors of resulting resonance features. In this work, we experimentally probe the effect of strong near-field coupling on the strength of the dark mode in a concentrically aligned bright resonator and a dark split ring resonator (SRR) system exhibiting the classical analog of the electromagnetically induced transparency effect. An enhanced strong magnetic field between the bright-dark resonators destructively interferes with the inherent magnetic field of the dark mode to completely annihilate its effect in the coupled system. Moreover, the observed annihilation effect in the dark mode has a direct consequence on the disappearance of the SRR effect in the proposed system, wherein under the strong magnetic interactions, the LC resonance feature of the split ring resonator becomes invisible to the incident terahertz wave.
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NASA Astrophysics Data System (ADS)
Simpson, Emma; Connolly, Paul; McFiggans, Gordon
2016-04-01
Processes such as precipitation and radiation depend on the concentration and size of different hydrometeors within clouds therefore it is important to accurately predict them in weather and climate models. A large fraction of clouds present in our atmosphere are mixed phase; contain both liquid and ice particles. The number of drops and ice crystals present in mixed phase clouds strongly depends on the size distribution of aerosols. Cloud condensation nuclei (CCN), a subset of atmospheric aerosol particles, are required for liquid drops to form in the atmosphere. These particles are ubiquitous in the atmosphere. To nucleate ice particles in mixed phase clouds ice nucleating particles (INP) are required. These particles are rarer than CCN. Here we investigate the case where CCN and INPs are in direct competition with each other for water vapour within a cloud. Focusing on the immersion and condensation modes of freezing (where an INP must be immersed within a liquid drop before it can freeze) we show that the presence of CCN can suppress the formation of ice. CCN are more hydrophilic than IN and as such are better able to compete for water vapour than, typically insoluble, INPs. Therefore water is more likely to condense onto a CCN than INP, leaving the INP without enough condensed water on it to be able to freeze in the immersion or condensation mode. The magnitude of this suppression effect strongly depends on a currently unconstrained quantity. Here we refer to this quantity as the critical mass of condensed water required for freezing, Mwc. Mwc is the threshold amount of water that must be condensed onto a INP before it can freeze in the immersion or condensation mode. Using the detailed cloud parcel model, Aerosol-Cloud-Precipiation-Interaction Model (ACPIM), developed at the University of Manchester we show that if only a small amount of water is required for freezing there is little suppression effect and if a large amount of water is required there is a large suppression effect. In this poster possible ways to constrain Mwc are discussed as well as conditions where the suppression effect is likely to be greatest. Key Words: Clouds, aerosol, CCN, IN, modelling
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Goode, P.R.; Barrett, B.R.; Portilho, O.
1979-02-01
The earlier calculations of Goode and Barrett are repeated using the super-soft-core potential of Gogny, Pires, and de Tourreil. The particular third-order folded diagram which they calculated now converges in its intermediate-state energy summation, because of the suppression of the strong short-range repulsive effects present in earlier calculations.
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NASA Astrophysics Data System (ADS)
Zheng, Jun-Hui; Cazalilla, Miguel A.
2018-06-01
We investigate nonperturbatively the effect of a magnetic dopant impurity on the edge transport of a quantum spin Hall (QSH) insulator. We show that for a strongly coupled magnetic dopant located near the edge of a system, a pair of transmission antiresonances appear. When the chemical potential is on resonance, interaction effects broaden the antiresonance width with decreasing temperature, thus suppressing transport for both repulsive and moderately attractive interactions. Consequences for the recently observed QSH insulating phase of the 1 -T' of WTe2 are briefly discussed.
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Immunomodulatory properties of titanium dioxide nanostructural materials.
Latha, T Sree; Reddy, Madhava C; R Durbaka, Prasad V; Muthukonda, Shankar V; Lomada, Dakshayani
2017-01-01
Although titanium dioxide (TiO 2 ) nanostructural materials have been widely used in Biology and Medicine, very little is known about immunomodulation mechanism of these materials. Objectives of this study are to investigate in vitro immunomodulatory effects of TiO 2 . Immunosuppressant may lower immune responses and are helpful for the treatment of graft versus host diseases and autoimmune disorders. In this study, we used H 2 Ti 3 O 7 titanium dioxide nanotubes (TNT) nanotubes along with commercial TiO 2 nanoparticles (TNP) and TiO 2 fine particles (TFP). We investigated the in vitro immunomodulatory effects of TNP, TNT, and TFP using mixed lymphocyte reaction (MLR). Suppression was studied by 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. Cytokine profile was measured by enzyme-linked immunosorbent assay (ELISA). The results from this study illustrated that the TiO 2 nanostructural materials strongly suppressed splenocytes proliferation in MLR. For TNP and TNT, at 50 μg/ml suppression of 20%-25% and 30%-35%, respectively, and for TFP at 100 μg/ml suppression was 25%-30% was observed. Suppression of splenocytes proliferation in the presence of TNP, TNT, and TFP demonstrated that these nanostructural materials probably block T-cell-mediated responses in vitro . Our ELISA results confirmed that significantly lower levels of Th1 type cytokines (interleukin-2, interferon-γ) in the 48 h MLR culture supernatants. Our data suggest that TiO 2 nanostructural materials suppress splenocytes proliferation by suppressing Th1 cytokines.
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Arioka, Masaki; Takahashi-Yanaga, Fumi; Kubo, Momoko; Igawa, Kazunobu; Tomooka, Katsuhiko; Sasaguri, Toshiyuki
2017-08-15
Differentiation-inducing factor-1 (DIF-1) isolated from Dictyostelium discoideum strongly inhibits the proliferation of various mammalian cells through the activation of glycogen synthase kinase-3 (GSK-3). To evaluate DIF-1 as a novel anti-cancer agent for malignant melanoma, we examined whether DIF-1 has anti-proliferative, anti-migratory, and anti-invasive effects on melanoma cells using in vitro and in vivo systems. DIF-1 reduced the expression levels of cyclin D1 and c-Myc by facilitating their degradation via GSK-3 in mouse (B16BL6) and human (A2058) malignant melanoma cells, and thereby strongly inhibited their proliferation. DIF-1 suppressed the canonical Wnt signaling pathway by lowering the expression levels of transcription factor 7-like 2 and β-catenin, key transcription factors in this pathway. DIF-1 also inhibited cell migration and invasion, reducing the expression of matrix metalloproteinase-2; however, this effect was not dependent on GSK-3 activity. In a mouse lung tumor formation model, repeated oral administrations of DIF-1 markedly reduced melanoma colony formation in the lung. These results suggest that DIF-1 inhibits cell proliferation by a GSK-3-dependent mechanism and suppresses cell migration and invasion by a GSK-3-independent mechanism. Therefore, DIF-1 may have a potential as a novel anti-cancer agent for the treatment of malignant melanoma. Copyright © 2017 Elsevier Inc. All rights reserved.
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Kaur, Balveen; Cork, Sarah M; Sandberg, Eric M; Devi, Narra S; Zhang, Zhaobin; Klenotic, Philip A; Febbraio, Maria; Shim, Hyunsuk; Mao, Hui; Tucker-Burden, Carol; Silverstein, Roy L; Brat, Daniel J; Olson, Jeffrey J; Van Meir, Erwin G
2008-01-01
Angiogenesis is a critical physiological process that is appropriated during tumorigenesis. Little is known about how this process is specifically regulated in the brain. Brain Angiogenesis Inhibitor-1 (BAI1) is a primarily brain specific seven-transmembrane protein that contains five anti-angiogenic thrombospondin type-1 repeats (TSR). We recently showed that BAI1 is cleaved at a conserved proteolytic cleavage site releasing a soluble, 120 kDa anti-angiogenic factor called Vasculostatin (Vstat120). Vstat120 has been shown to inhibit in vitro angiogenesis and suppress subcutaneous tumor growth. Here, we examine its effect on intracranial growth of malignant gliomas and further study the mechanism of its anti-tumor effects. First, we show that expression of Vstat120 strongly suppresses the intracranial growth of malignant gliomas, even in the presence of the strong pro-angiogenic stimulus mediated by the oncoprotein Epidermal Growth Factor Receptor variant III (EGFRvIII). This tumor suppressive effect is accompanied by a decrease in vascular density in the tumors, suggesting a potent anti-angiogenic effect in the brain. Second, and consistent with this interpretation, we find that treatment with Vstat120 reduces the migration of cultured microvascular endothelial cells in vitro and inhibits corneal angiogenesis in vivo. Third, we demonstrate that these anti-vascular effects are critically dependent on the presence of the cell surface receptor CD36 on endothelial cells in vitro and in vivo, supporting a role of the Vstat120 TSRs in mediating these effects. These results advance the understanding of brain-specific angiogenic regulation, and suggest that Vstat120 has therapeutic potential in the treatment of brain tumors and other intra-cerebral vasculopathies. PMID:19176395
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Local suppression of the superfluid density of PuCoGa5 by strong onsite disorder
NASA Astrophysics Data System (ADS)
Das, Tanmoy; Zhu, Jian-Xin; Graf, Matthias J.
2011-10-01
We present superfluid density calculations for the unconventional superconductor PuCoGa5 by solving the real-space Bogoliubov-de Gennes equations on a square lattice within the Swiss-cheese model in the presence of strong onsite disorder. We find that, despite strong electronic inhomogeneity, one can establish a one-to-one correspondence between the local maps of the density of states, superconducting order parameter, and superfluid density. In this model, strong onsite impurity scattering punches localized holes into the fabric of d-wave superconductivity similar to a Swiss cheese. Already, a two-dimensional impurity concentration of nimp=4% gives rise to a pronounced short-range suppression of the order parameter and a suppression of the superconducting transition temperature Tc by roughly 20% compared to its pure limit value Tc0, whereas the superfluid density ρs is reduced drastically by about 70%. This result is consistent with available experimental data for aged (400-day-old) and fresh (25-day-old) PuCoGa5 superconducting samples. In addition, we show that the T2 dependence of the low-T superfluid density, a signature of dirty d-wave superconductivity, originates from a combined effect in the density of states of “gap filling” and “gap closing.” Finally, we demonstrate that the Uemuera plot of Tc versus ρs deviates sharply from the conventional Abrikosov-Gor’kov theory for radiation-induced defects in PuCoGa5, but follows the same trend of short-coherence-length high-Tc cuprate superconductors.
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Deconfinement as an entropic self-destruction: A solution for the quarkonium suppression puzzle?
Kharzeev, Dmitri E.
2014-10-02
The entropic approach to dissociation of bound states immersed in strongly coupled systems is developed. In such systems, the excitations of the bound state are often delocalized and characterized by a large entropy, so that the bound state is strongly entangled with the rest of the statistical system. If this entropy S increases with the separation r between the constituents of the bound state, S=S(r), then the resulting entropic force F=T ∂S/∂r (T is temperature) can drive the dissociation process. As a specific example, we consider the case of heavy quarkonium in strongly coupled quark-gluon plasma, where lattice QCD indicatesmore » a large amount of entropy associated with the heavy quark pair at temperatures 0.9T c ≤ T ≤ 1.5T c (T c is the deconfinement temperature); this entropy S(r) grows with the interquark distance r. We argue that the entropic mechanism results in an anomalously strong quarkonium suppression in the temperature range near T c. This entropic self-destruction may thus explain why the experimentally measured quarkonium nuclear modification factor at RHIC (lower energy density) is smaller than at LHC (higher energy density), possibly resolving the “quarkonium suppression puzzle”—all of the previously known mechanisms of quarkonium dissociation operate more effectively at higher energy densities, and this contradicts the data. As a result, we find that near T c the entropic force leads to delocalization of the bound hadron states; we argue that this delocalization may be the mechanism underlying deconfinement.« less
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Experimental study on parasitic mode suppression using FeSiAl in relativistic klystron amplifier
NASA Astrophysics Data System (ADS)
Zhang, Zehai
2015-03-01
Experimental study of parasitic mode suppression using electromagnetic attenuate material FeSiAl in an S-band Relativistic Klystron Amplifier (RKA) is presented in this paper. The FeSiAl powder is coated and sintered onto the inner surface of a drift tube which locates between the input and the middle cavity of the RKA. Cold tests show that the attenuate rate of the tube against parasitic mode TE11 is about 50%. Experiments carried out on the Torch-01 accelerator present that the tube is effective in suppressing the parasitic mode. Two typical outputs are obtained. When the diode voltage is on a moderate level, the RKA operates well and the parasitic mode is totally suppressed. The pulse length of the High Power Microwave (HPM) almost equals the electron beam pulse length and the HPM average output power is about 300 MW, with a power efficiency of 10%. When the diode voltage is on a higher level, the output power and efficiency rise but the parasitic mode oscillation occurred and the pulse length is shortened. By contrast, the parasitic mode oscillation is too strong for the RKA to operate normally with un-sintered drift tube. The experimental study implies that FeSiAl is effective in suppressing the parasitic mode oscillation in a certain extent. However, total suppression needs a deeper attenuate rate and further investigation.
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Experimental study on parasitic mode suppression using FeSiAl in Relativistic Klystron Amplifier.
Zhang, Zehai
2015-03-01
Experimental study of parasitic mode suppression using electromagnetic attenuate material FeSiAl in an S-band Relativistic Klystron Amplifier (RKA) is presented in this paper. The FeSiAl powder is coated and sintered onto the inner surface of a drift tube which locates between the input and the middle cavity of the RKA. Cold tests show that the attenuate rate of the tube against parasitic mode TE11 is about 50%. Experiments carried out on the Torch-01 accelerator present that the tube is effective in suppressing the parasitic mode. Two typical outputs are obtained. When the diode voltage is on a moderate level, the RKA operates well and the parasitic mode is totally suppressed. The pulse length of the High Power Microwave (HPM) almost equals the electron beam pulse length and the HPM average output power is about 300 MW, with a power efficiency of 10%. When the diode voltage is on a higher level, the output power and efficiency rise but the parasitic mode oscillation occurred and the pulse length is shortened. By contrast, the parasitic mode oscillation is too strong for the RKA to operate normally with un-sintered drift tube. The experimental study implies that FeSiAl is effective in suppressing the parasitic mode oscillation in a certain extent. However, total suppression needs a deeper attenuate rate and further investigation.
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Prediction suppression and surprise enhancement in monkey inferotemporal cortex.
Ramachandran, Suchitra; Meyer, Travis; Olson, Carl R
2017-07-01
Exposing monkeys, over the course of days and weeks, to pairs of images presented in fixed sequence, so that each leading image becomes a predictor for the corresponding trailing image, affects neuronal visual responsiveness in area TE. At the end of the training period, neurons respond relatively weakly to a trailing image when it appears in a trained sequence and, thus, confirms prediction, whereas they respond relatively strongly to the same image when it appears in an untrained sequence and, thus, violates prediction. This effect could arise from prediction suppression (reduced firing in response to the occurrence of a probable event) or surprise enhancement (elevated firing in response to the omission of a probable event). To identify its cause, we compared firing under the prediction-confirming and prediction-violating conditions to firing under a prediction-neutral condition. The results provide strong evidence for prediction suppression and limited evidence for surprise enhancement. NEW & NOTEWORTHY In predictive coding models of the visual system, neurons carry signed prediction error signals. We show here that monkey inferotemporal neurons exhibit prediction-modulated firing, as posited by these models, but that the signal is unsigned. The response to a prediction-confirming image is suppressed, and the response to a prediction-violating image may be enhanced. These results are better explained by a model in which the visual system emphasizes unpredicted events than by a predictive coding model. Copyright © 2017 the American Physiological Society.
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Liberati, Stefano; Maccione, Luca; Sotiriou, Thomas P
2012-10-12
Hořava-Lifshitz gravity models contain higher-order operators suppressed by a characteristic scale, which is required to be parametrically smaller than the Planck scale. We show that recomputed synchrotron radiation constraints from the Crab Nebula suffice to exclude the possibility that this scale is of the same order of magnitude as the Lorentz breaking scale in the matter sector. This highlights the need for a mechanism that suppresses the percolation of Lorentz violation in the matter sector and is effective for higher-order operators as well.
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The role of local repulsion in superconductivity in the Hubbard-Holstein model
NASA Astrophysics Data System (ADS)
Lin, Chungwei; Wang, Bingnan; Teo, Koon Hoo
2017-01-01
We examine the superconducting solution in the Hubbard-Holstein model using Dynamical Mean Field Theory. The Holstein term introduces the site-independent Boson fields coupling to local electron density, and has two competing influences on superconductivity: The Boson field mediates the effective electron-electron attraction, which is essential for the S-wave electron pairing; the same coupling to the Boson fields also induces the polaron effect, which makes the system less metallic and thus suppresses superconductivity. The Hubbard term introduces an energy penalty U when two electrons occupy the same site, which is expected to suppress superconductivity. By solving the Hubbard-Holstein model using Dynamical Mean Field theory, we find that the Hubbard U can be beneficial to superconductivity under some circumstances. In particular, we demonstrate that when the Boson energy Ω is small, a weak local repulsion actually stabilizesthe S-wave superconducting state. This behavior can be understood as an interplay between superconductivity, the polaron effect, and the on-site repulsion: As the polaron effect is strong and suppresses superconductivity in the small Ω regime, the weak on-site repulsion reduces the polaron effect and effectively enhances superconductivity. Our calculation elucidates the role of local repulsion in the conventional S-wave superconductors.
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Sleep deprivation suppresses aggression in Drosophila
Kayser, Matthew S; Mainwaring, Benjamin; Yue, Zhifeng; Sehgal, Amita
2015-01-01
Sleep disturbances negatively impact numerous functions and have been linked to aggression and violence. However, a clear effect of sleep deprivation on aggressive behaviors remains unclear. We find that acute sleep deprivation profoundly suppresses aggressive behaviors in the fruit fly, while other social behaviors are unaffected. This suppression is recovered following post-deprivation sleep rebound, and occurs regardless of the approach to achieve sleep loss. Genetic and pharmacologic approaches suggest octopamine signaling transmits changes in aggression upon sleep deprivation, and reduced aggression places sleep-deprived flies at a competitive disadvantage for obtaining a reproductive partner. These findings demonstrate an interaction between two phylogenetically conserved behaviors, and suggest that previous sleep experiences strongly modulate aggression with consequences for reproductive fitness. DOI: http://dx.doi.org/10.7554/eLife.07643.001 PMID:26216041
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Suppressing hillock formation in Si-supported pure Al films
NASA Astrophysics Data System (ADS)
Liu, N. Z.; Liu, Y.
2018-04-01
To suppress the hillock formation and hence improve the service performance of pure Al thin films deposited on Si substrate, dependence of hillock formation on film thickness and annealing temperature was systematically investigated. Experimental results revealed that the hillock volume increased linearly with both the film thickness and annealing temperature. While the evolution of hillock density with film thickness was complicated, strongly depending on the annealing temperature. It was evident that the hillock formation could be effectively suppressed at a critical annealing temperature especially in thinner thickness, similar to the previous findings in Mo/glass-supported pure Al films. These experimental evidences clearly demonstrated that the hillock formation should be controlled by the plastic deformation in the surrounding film, which was further rationalized by a micromechanics model.
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Penman, T D; Collins, L; Price, O F; Bradstock, R A; Metcalf, S; Chong, D M O
2013-12-15
Large budgets are spent on both suppression and fuel treatments in order to reduce the risk of wildfires. There is little evidence regarding the relative contribution of fire weather, suppression and fuel treatments in determining the risk posed from wildfires. Here we undertake a simulation study in the Sydney Basin, Australia, to examine this question using a fire behaviour model (Phoenix Rapidfire). Results of the study indicate that fire behaviour is most strongly influenced by fire weather. Suppression has a greater influence on whether a fire reaches 5 ha in size compared to fuel treatments. In contrast, fuel treatments have a stronger effect on the fire size and maximum distance the fire travels. The study suggests that fire management agencies will receive additional benefits from fuel treatment if they are located in areas which suppression resources can respond rapidly and attempt to contain the fires. No combination of treatments contained all fires, and the proportion of uncontained fires increased under more severe fire weather when the greatest number of properties are lost. Our study highlights the importance of alternative management strategies to reduce the risk of property loss. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.
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Magnetic field control of microstructural development in melt-spun Pr2Co14 B
NASA Astrophysics Data System (ADS)
McGuire, Michael A.; Rios, Orlando; Conner, Ben S.; Carter, William G.; Huang, Mianliang; Sun, Kewei; Palasyuk, Olena; Jensen, Brandt; Zhou, Lin; Dennis, Kevin; Nlebedim, Ikenna C.; Kramer, Matthew J.
2017-05-01
In the processing of commercial rare earth permanent magnets, use of external magnetic fields is limited mainly to the alignment of anisotropic particles and the polarization of the finished magnets. Here we explore the effects of high magnetic fields on earlier stages of magnet synthesis, including the crystallization and chemical phase transformations that produce the 2:14:1 phase in the Pr-Co-B system. Pr2Co14 B alloys produced by melt-spinning were annealed in the presence of strong applied magnetic fields (H=90 kOe). The resulting materials were characterized by x-ray diffraction, electron microscopy, and magnetization measurements. We find that magnetic fields suppress the nucleation and growth of crystalline phases, resulting in significantly smaller particle sizes. In addition, magnetic fields applied during processing strongly affects chemical phase selection, suppressing the formation of Pr2Co14 B and α-Co in favor of Pr2Co17 . The results demonstrate that increased control over key microstructural properties is achievable by including a strong magnetic field as a processing parameter for rare-earth magnet materials.
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Starenki, Dmytro
2013-01-01
Context: Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor mainly caused by mutations in the RET proto-oncogene. For MTC therapy, the U.S. Food and Drug Administration recently approved vandetanib and cabozantinib, multikinase inhibitors targeting RET and other tyrosine kinase receptors of vascular endothelial growth factor, epidermal growth factor, or hepatocyte growth factor. Nevertheless, not all patients with the progressive MTC respond to these drugs, requiring the development of additional therapeutic modalities that have distinct activity. Objective: We aimed to evaluate mitochondria-targeted carboxy-proxyl (Mito-CP), a mitochondria-targeted redox-sensitive agent, for its tumor-suppressive efficacy against MTC. Design: In vitro cultures of 2 human MTC cell lines, TT and MZ-CRC-1, and TT xenografts in mice were treated with Mito-CP in comparison with vandetanib. The effects on cell survival/death, RET expression, mitochondrial integrity, and oxidative stress were determined. Results: Contrary to vandetanib, Mito-CP induced RET downregulation and strong cytotoxic effects in both cell lines in vitro, including caspase-dependent apoptosis. These effects were accompanied by mitochondrial membrane depolarization, decreased oxygen consumption, and increased oxidative stress in cells. Intriguingly, Mito-CP–induced cell death, but not RET downregulation, was partially inhibited by the reactive oxygen species scavenger, N-acetyl-cysteine, indicating that Mito-CP mediates tumor-suppressive effects via redox-dependent as well as redox-independent mechanisms. Orally administered Mito-CP effectively suppressed TT xenografts in mice, with an efficacy comparable to vandetanib and relatively low toxicity to animals. Conclusion: Our results suggest that Mito-CP can effectively suppress MTC cell growth/survival via a mechanism distinct from vandetanib effects. Mitochondrial targeting may be a potential strategy for MTC therapy. PMID:23509102
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NASA Astrophysics Data System (ADS)
Liu, Wei; Guo, Huazhong; He, Jianhong; Gao, Jie
2018-05-01
We have measured the dynamic admittance of an interacting coherent capacitor in the quantum Hall regime. Our experiments demonstrate that, in the fully coherent regime, the charge relaxation resistance is universal and independent of the transmission even in the presence of strong charge interactions. Conversely, we observe strong suppression of the electrochemical capacitance, which is related to the density of states of the charge excitations due to strong interactions. Our experiments form the building blocks for the realization of electron quantum optics experiments with strong charge interactions, and they should prove useful for quantum bits in interacting ballistic conductors.
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A new method to quantify the effects of baryons on the matter power spectrum
DOE Office of Scientific and Technical Information (OSTI.GOV)
Schneider, Aurel; Teyssier, Romain, E-mail: aurel@physik.uzh.ch, E-mail: teyssier@physik.uzh.ch
2015-12-01
Future large-scale galaxy surveys have the potential to become leading probes for cosmology provided the influence of baryons on the total mass distribution is understood well enough. As hydrodynamical simulations strongly depend on details in the feedback implementations, no unique and robust predictions for baryonic effects currently exist. In this paper we propose a baryonic correction model that modifies the density field of dark-matter-only N-body simulations to mimic the effects of baryons from any underlying adopted feedback recipe. The model assumes haloes to consist of 4 components: 1- hot gas in hydrostatical equilibrium, 2- ejected gas from feedback processes, 3-more » central galaxy stars, and 4- adiabatically relaxed dark matter, which all modify the initial dark-matter-only density profiles. These altered profiles allow to define a displacement field for particles in N-body simulations and to modify the total density field accordingly. The main advantage of the baryonic correction model is to connect the total matter density field to the observable distribution of gas and stars in haloes, making it possible to parametrise baryonic effects on the matter power spectrum. We show that the most crucial quantities are the mass fraction of ejected gas and its corresponding ejection radius. The former controls how strongly baryons suppress the power spectrum, while the latter provides a measure of the scale where baryonic effects become important. A comparison with X-ray and Sunyaev-Zel'dovich cluster observations suggests that baryons suppress wave modes above k∼0.5 h/Mpc with a maximum suppression of 10-25 percent around k∼ 2 h/Mpc. More detailed observations of the gas in the outskirts of groups and clusters are required to decrease the large uncertainties of these numbers.« less
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NASA Astrophysics Data System (ADS)
Koren, Gad
2018-07-01
We report properties of a topological insulator–ferromagnet–superconductor trilayers comprised of thin films of 20 nm thick {Bi}}2{Se}}3 on 10 nm SrRuO3 on 30 nm {YBa}}2{Cu}}3{{{O}}}x. As deposited trilayers are underdoped and have a superconductive transition with {{T}}{{c}} onset at 75 K, zero resistance at 65 K, {{T}}Cueri} at 150 K and {{T}}* of about 200 K. Further reannealing under vacuum yields the 60 K phase of {YBa}}2{Cu}}3{{{O}}}x which still has zero resistance below about 40 K. Only when 10 × 100 microbridges were patterned in the trilayer, some of the bridges showed resistive behavior all the way down to low temperatures. Magnetoresistance versus temperature of the superconductive ones showed the typical peak due to flux flow against pinning below {{T}}{{c}}, while the resistive ones showed only the broad leading edge of such a peak. All this indicates clearly weak-link superconductivity in the resistive bridges between superconductive {YBa}}2{Cu}}3{{{O}}}x grains via the topological and ferromagnetic cap layers. Comparing our results to those of a reference trilayer (RTL) with the topological {Bi}}2{Se}}3 layer substituted by a non-superconducting highly overdoped {La}}1.65{Sr}}0.35{CuO}}4, indicates that the superconductive proximity effect as well as ferromagnetism in the topological trilayer are actually strongly suppressed compared to the non-topological RTL. This strong suppression could originate in lattice and Fermi levels mismatch as well as in short coherence length and unfavorable effects of strong spin–orbit coupling in {Bi}}2{Se}}3 on the d-wave pairing of {YBa}}2{Cu}}3{{{O}}}x. Proximity induced edge currents in the SRO/YBCO layer could lead to Majorana bound states, a possible signature of which is observed in the present study as zero bias conductance peaks.
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NASA Astrophysics Data System (ADS)
Lee, Myoung-Jae; Jung, Young-Dae
2017-10-01
The influence of quantum shielding on the Ramsauer-Townsend phenomena for the total electron-atom polarisation collision cross-section is investigated in partially ionised strongly coupled semiclassic plasmas. The result shows that the quantum shielding effect changes the position of the Ramsauer energy in partially ionised strongly coupled plasmas. It is also found that the quantum shielding effect enhances the total electron-atom collision cross-section when the collision energy is greater than the Ramsauer energy; however, it suppresses the collision cross-section when the collision energy is smaller than the Ramsauer energy. In addition, it is shown that the plasma screening effect significantly changes the position of the Ramsauer energy and the influence of plasma screening on the magnitude of the collision cross-section is more significant near the Ramsauer energy domain. The variations of the Ramsauer energy and the collision cross-section due to the quantum shielding effect are also discussed.
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NASA Astrophysics Data System (ADS)
Jia, M.; Sun, Y.; Paz-Soldan, C.; Nazikian, R.; Gu, S.; Liu, Y. Q.; Abrams, T.; Bykov, I.; Cui, L.; Evans, T.; Garofalo, A.; Guo, W.; Gong, X.; Lasnier, C.; Logan, N. C.; Makowski, M.; Orlov, D.; Wang, H. H.
2018-05-01
Experiments using Resonant Magnetic Perturbations (RMPs), with a rotating n = 2 toroidal harmonic combined with a stationary n = 3 toroidal harmonic, have validated predictions that divertor heat and particle flux can be dynamically controlled while maintaining Edge Localized Mode (ELM) suppression in the DIII-D tokamak. Here, n is the toroidal mode number. ELM suppression over one full cycle of a rotating n = 2 RMP that was mixed with a static n = 3 RMP field has been achieved. Prominent heat flux splitting on the outer divertor has been observed during ELM suppression by RMPs in low collisionality regime in DIII-D. Strong changes in the three dimensional heat and particle flux footprint in the divertor were observed during the application of the mixed toroidal harmonic magnetic perturbations. These results agree well with modeling of the edge magnetic field structure using the TOP2D code, which takes into account the plasma response from the MARS-F code. These results expand the potential effectiveness of the RMP ELM suppression technique for the simultaneous control of divertor heat and particle load required in ITER.
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Luoma, Jarkko; Pekkonen, Eero; Airaksinen, Katja; Helle, Liisa; Nurminen, Jussi; Taulu, Samu; Mäkelä, Jyrki P
2018-06-22
Advanced Parkinson's disease (PD) is characterized by an excessive oscillatory beta band activity in the subthalamic nucleus (STN). Deep brain stimulation (DBS) of STN alleviates motor symptoms in PD and suppresses the STN beta band activity. The effect of DBS on cortical sensorimotor activity is more ambiguous; both increases and decreases of beta band activity have been reported. Non-invasive studies with simultaneous DBS are problematic due to DBS-induced artifacts. We recorded magnetoencephalography (MEG) from 16 advanced PD patients with and without STN DBS during rest and wrist extension. The strong magnetic artifacts related to stimulation were removed by temporal signal space separation. MEG oscillatory activity at 5-25 Hz was suppressed during DBS in a widespread frontoparietal region, including the sensorimotor cortex identified by the cortico-muscular coherence. The strength of suppression did not correlate with clinical improvement. Our results indicate that alpha and beta band oscillations are suppressed at the frontoparietal cortex by STN DBS in PD. Copyright © 2018. Published by Elsevier B.V.
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Tuning the electrical transport of type II Weyl semimetal WTe2 nanodevices by Mo doping
NASA Astrophysics Data System (ADS)
Fu, Dongzhi; Pan, Xingchen; Bai, Zhanbin; Fei, Fucong; Umana-Membreno, Gilberto A.; Song, Honglian; Wang, Xuelin; Wang, Baigeng; Song, Fengqi
2018-04-01
We fabricated nanodevices from MoxW1-xTe2 (x = 0, 0.07, 0.35), and conducted a systematic comparative study of their electrical transport. Magnetoresistance measurements show that Mo doping can significantly suppress mobility and magnetoresistance. The results for the analysis of the two band model show that doping with Mo does not break the carrier balance. Through analysis of Shubnikov-de Haas oscillations, we found that Mo doping also has a strong suppressive effect on the quantum oscillation of the sample, and the higher the ratio of Mo, the fewer pockets were observed in our experiments. Furthermore, the effective mass of electron and hole increases gradually with increasing Mo ratio, while the corresponding quantum mobility decreases rapidly.
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Electronic screening in stacked graphene flakes revealed by scanning tunneling microscopy
NASA Astrophysics Data System (ADS)
Feng, Xiaofeng; Salmeron, Miquel
2013-02-01
Electronic doping and screening effects in stacked graphene flakes on Ru and Cu substrates have been observed using scanning tunneling microscopy (STM). The screening affects the apparent STM height of each flake in successive layers reflecting the density of states near the Fermi level and thus the doping level. It is revealed in this way that the strong doping of the first graphene layer on Ru(0001) is attenuated in the second one, and almost eliminated in the third and fourth layers. Similar effect is also observed in graphene flakes on Cu(111). In contrast, the strong doping effect is suppressed immediately by a water layer intercalated between the graphene and Ru.
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Gravitational radiation from compact binary systems in screened modified gravity
NASA Astrophysics Data System (ADS)
Zhang, Xing; Liu, Tan; Zhao, Wen
2017-05-01
Screened modified gravity (SMG) is a kind of scalar-tensor theory with screening mechanisms, which can suppress the fifth force in dense regions and allow theories to evade the solar system and laboratory tests. In this paper, we investigate how the screening mechanisms in SMG affect the gravitational radiation damping effects, calculate in detail the rate of the energy loss due to the emission of tensor and scalar gravitational radiations, and derive their contributions to the change in the orbital period of the binary system. We find that the scalar radiation depends on the screened parameters and the propagation speed of scalar waves, and the scalar dipole radiation dominates the orbital decay of the binary system. For strongly self-gravitating bodies, all effects of scalar sector are strongly suppressed by the screening mechanisms in SMG. By comparing our results to observations of binary system PSR J 1738 +0333 , we place the stringent constraints on the screening mechanisms in SMG. As an application of these results, we focus on three specific models of SMG (chameleon, symmetron, and dilaton), and derive the constraints on the model parameters, respectively.
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Suppression of spin and optical gaps in phosphorene quantum dots
NASA Astrophysics Data System (ADS)
Zhang, Yingjie; Sheng, Weidong
2018-05-01
Electronic structure and optical properties of triangular phosphorene quantum dots have been investigated theoretically. Based on systematic configuration interaction calculations, the ground and excited states of the interacting many-electron system together with its optical absorption spectrum are obtained. For the nanodot with 60 phosphorus atoms in various dielectric environments, it is found that the spin gap of the correlated system surprisingly overlaps its optical gap over a large range of the effective dielectric constant. The overlapping of the spin and optical gaps can be attributed to the fact that the extra correlation energy in the spin singlet almost compensates the exchange energy in the spin triplet in the presence of strong long-range electron-electron interactions. Moreover, both the spin and optical gaps are shown to be greatly suppressed as the screening effect becomes strong. When the dielectric constant decreases below 2.65, it is seen that the spin gap becomes negative and the quantum dot undergoes a phase transition from nonmagnetic to ferromagnetic. Our results are compared with the previous experimental and theoretical works.
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The Analysis and Suppression of the spike noise in vibrator record
NASA Astrophysics Data System (ADS)
Jia, H.; Jiang, T.; Xu, X.; Ge, L.; Lin, J.; Yang, Z.
2013-12-01
During the seismic exploration with vibrator, seismic recording systems have often been affected by random spike noise in the background, which leads to strong data distortions as a result of the cross-correlation processing of the vibrator method. Partial or total loss of the desired seismic information is possible if no automatic spike reduction is available in the field prior to correlation of the field record. Generally speaking, original record of vibrator is uncorrelated data, in which the signal is non-wavelet form. In order to obtain the seismic record similar to explosive source, the signal of uncorrelated data needs to use the correlation algorithm to compress into wavelet form. The correlation process results in that the interference of spike in correlated data is not only being suppressed, but also being expanded. So the spike noise suppression of vibrator is indispensable. According to numerical simulation results, the effect of spike in the vibrator record is mainly affected by the amplitude and proportional points in the uncorrelated record. When the spike noise ratio in uncorrelated record reaches 1.5% and the average amplitude exceeds 200, it will make the SNR(signal-to-noise ratio) of the correlated record lower than 0dB, so that it is difficult to separate the signal. While the amplitude and ratio is determined by the intensity of background noise. Therefore, when the noise level is strong, in order to improve SNR of the seismic data, the uncorrelated record of vibrator need to take necessary steps to suppress spike noise. For the sake of reducing the influence of the spike noise, we need to make the detection and suppression of spike noise process for the uncorrelated record. Because vibrator works by inputting sweep signal into the underground long time, ideally, the peak and valley values of each trace have little change. On the basis of the peak and valley values, we can get a reference amplitude value. Then the spike can be detected and suppressed. After this process, it can reduce the effection of spike noise in the uncorrelated record to improve the SNR. At present, because the memory space of vibrator uncorrelated data is always very large, in order to reduce acquisition costs, we usually record correlated data directly. It's reasonable if there is no strong spike sneaking into uncorrelated record. However, due to the fact that the random spike in the background is not avoidable in the acquisition process, and the instantaneous input energy of the vibrator is probably smaller than spike noise, which makes the uncorrelated data contain a certain amount of spike noise, it severely reduces the acquisition quality of vibrator if there is no noise suppression module beforehand. Of course, the suppressing process of spike noise can be carried out in the field acquisition or data processing stage. In the field of vibrator acquisition system, we can use the spike noise suppression before the correlated module, so that it can directly record correlated data without the spike affection. If in the stage of data processing, it is necessary to record uncorrelated data.
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Acute inhibition of neurosteroid estrogen synthesis suppresses status epilepticus in an animal model
Sato, Satoru M; Woolley, Catherine S
2016-01-01
Status epilepticus (SE) is a common neurological emergency for which new treatments are needed. In vitro studies suggest a novel approach to controlling seizures in SE: acute inhibition of estrogen synthesis in the brain. Here, we show in rats that systemic administration of an aromatase (estrogen synthase) inhibitor after seizure onset strongly suppresses both electrographic and behavioral seizures induced by kainic acid (KA). We found that KA-induced SE stimulates synthesis of estradiol (E2) in the hippocampus, a brain region commonly involved in seizures and where E2 is known to acutely promote neural activity. Hippocampal E2 levels were higher in rats experiencing more severe seizures. Consistent with a seizure-promoting effect of hippocampal estrogen synthesis, intra-hippocampal aromatase inhibition also suppressed seizures. These results reveal neurosteroid estrogen synthesis as a previously unknown factor in the escalation of seizures and suggest that acute administration of aromatase inhibitors may be an effective treatment for SE. DOI: http://dx.doi.org/10.7554/eLife.12917.001 PMID:27083045
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2004-01-01
Autophagic activity in isolated rat hepatocytes is strongly suppressed by OA (okadaic acid) and other PP (protein phosphatase)-inhibitory toxins as well as by AICAR (5-aminoimidazole-4-carboxamide riboside), a direct activator of AMPK (AMP-activated protein kinase). To investigate whether AMPK is a mediator of the effects of the toxin, a phosphospecific antibody directed against the activation of phosphorylation of the AMPK α (catalytic)-subunit at Thr172 was used to assess the activation status of this enzyme. AICAR as well as all the toxins tested (OA, microcystin-LR, calyculin A, cantharidin and tautomycin) induced strong, dose-dependent AMPKα phosphorylation, correlating with AMPK activity in situ (in intact hepatocytes) as measured by the AMPK-dependent phosphorylation of acetyl-CoA carboxylase at Ser79. All treatments induced the appearance of multiple, phosphatase-sensitive, low-mobility forms of the AMPK α-subunit, consistent with phosphorylation at several sites other than Thr172. The flavonoid naringin, an effective antagonist of OA-induced autophagy suppression, inhibited the AMPK phosphorylation and mobility shifting induced by AICAR, OA or microcystin, but not the changes induced by calyculin A or cantharidin. AMPK may thus be activated both by a naringin-sensitive and a naringin-resistant mechanism, probably involving the PPs PP2A and PP1 respectively. Neither the Thr172-phosphorylating protein kinase LKB1 nor the Thr172-dephosphorylating PP, PP2C, were mobility-shifted after treatment with toxins or AICAR, whereas a slight mobility shifting of the regulatory AMPK β-subunit was indicated. Immunoblotting with a phosphospecific antibody against pSer108 at the β-subunit revealed a naringin-sensitive phosphorylation induced by OA, microcystin and AICAR and a naringin-resistant phosphorylation induced by calyculin A and cantharidin, suggesting that β-subunit phosphorylation could play a role in AMPK activation. Naringin antagonized the autophagy-suppressive effects of AICAR and OA, but not the autophagy suppression caused by cantharidin, consistent with AMPK-mediated inhibition of autophagy by toxins as well as by AICAR. PMID:15461583
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Behavioral and Environmental Modification of the Genetic Influence on Body Mass Index: A Twin Study.
Horn, Erin E; Turkheimer, Eric; Strachan, Eric; Duncan, Glen E
2015-07-01
Body mass index (BMI) has a strong genetic basis, with a heritability around 0.75, but is also influenced by numerous behavioral and environmental factors. Aspects of the built environment (e.g., environmental walkability) are hypothesized to influence obesity by directly affecting BMI, by facilitating or inhibiting behaviors such as physical activity that are related to BMI, or by suppressing genetic tendencies toward higher BMI. The present study investigated relative influences of physical activity and walkability on variance in BMI using 5079 same-sex adult twin pairs (70 % monozygotic, 65 % female). High activity and walkability levels independently suppressed genetic variance in BMI. Estimating their effects simultaneously, however, suggested that the walkability effect was mediated by activity. The suppressive effect of activity on variance in BMI was present even with a tendency for low-BMI individuals to select into environments that require higher activity levels. Overall, our results point to community- or macro-level interventions that facilitate individual-level behaviors as a plausible approach to addressing the obesity epidemic among US adults.
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Behavioral and environmental modification of the genetic influence on body mass index: A twin study
Horn, Erin E.; Turkheimer, Eric; Strachan, Eric; Duncan, Glen E.
2015-01-01
Body mass index (BMI) has a strong genetic basis, with a heritability around 0.75, but is also influenced by numerous behavioral and environmental factors. Aspects of the built environment (e.g., environmental walkability) are hypothesized to influence obesity by directly affecting BMI, by facilitating or inhibiting behaviors such as physical activity that are related to BMI, or by suppressing genetic tendencies toward higher BMI. The present study investigated relative influences of physical activity and walkability on variance in BMI using 5,079 same-sex adult twin pairs (70% monozygotic, 65% female). High activity and walkability levels independently suppressed genetic variance in BMI. Estimating their effects simultaneously, however, suggested that the walkability effect was mediated by activity. The suppressive effect of activity on variance in BMI was present even with a tendency for low-BMI individuals to select into environments that require higher activity levels. Overall, our results point to community- or macro-level interventions that facilitate individual-level behaviors as a plausible approach to addressing the obesity epidemic among U.S. adults. PMID:25894925
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Controllable nonlinearity in a dual-coupling optomechanical system under a weak-coupling regime
NASA Astrophysics Data System (ADS)
Zhu, Gui-Lei; Lü, Xin-You; Wan, Liang-Liang; Yin, Tai-Shuang; Bin, Qian; Wu, Ying
2018-03-01
Strong quantum nonlinearity gives rise to many interesting quantum effects and has wide applications in quantum physics. Here we investigate the quantum nonlinear effect of an optomechanical system (OMS) consisting of both linear and quadratic coupling. Interestingly, a controllable optomechanical nonlinearity is obtained by applying a driving laser into the cavity. This controllable optomechanical nonlinearity can be enhanced into a strong coupling regime, even if the system is initially in the weak-coupling regime. Moreover, the system dissipation can be suppressed effectively, which allows the appearance of phonon sideband and photon blockade effects in the weak-coupling regime. This work may inspire the exploration of a dual-coupling optomechanical system as well as its applications in modern quantum science.
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Single-particle spectral functions in the normal phase of a strongly attractive Bose-Fermi mixture
NASA Astrophysics Data System (ADS)
Fratini, E.; Pieri, P.
2013-07-01
We calculate the single-particle spectral functions and quasiparticle dispersions for a Bose-Fermi mixture when the boson-fermion attraction is sufficiently strong to suppress completely the condensation of bosons at zero temperature. Within a T-matrix diagrammatic approach, we vary the boson-fermion attraction from the critical value where the boson condensate first disappears to the strongly attractive (molecular) regime and study the effect of both mass and density imbalance on the spectral weights and dispersions. An interesting spectrum of particle-hole excitations mixing two different Fermi surfaces is found. These unconventional excitations could be produced and explored experimentally with radio-frequency spectroscopy.
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Pathogenesis of occult chronic hepatitis B virus infection
de la Fuente, Rocio Aller; Gutiérrez, María L; Garcia-Samaniego, Javier; Fernández-Rodriguez, Conrado; Lledó, Jose Luis; Castellano, Gregorio
2011-01-01
Occult hepatitis B infection (OBI) is characterized by hepatitis B virus (HBV) DNA in serum in the absence of hepatitis B surface antigen (HBsAg) presenting HBsAg-negative and anti-HBc positive serological patterns. Occult HBV status is associated in some cases with mutant viruses undetectable by HBsAg assays; but more frequently it is due to a strong suppression of viral replication and gene expression. OBI is an entity with world-wide diffusion. The failure to detect HBsAg, despite the persistence of the viral DNA, is due in most cases to the strong suppression of viral replication and gene expression that characterizes this “occult” HBV infection; although the mechanisms responsible for suppression of HBV are not well understood. The majority of OBI cases are secondary to overt HBV infection and represent a residual low viremia level suppressed by a strong immune response together with histological derangements which occurred during acute or chronic HBV infection. Much evidence suggests that it can favour the progression of liver fibrosis and the development of hepatocellular carcinoma. PMID:21472118
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Lignans from Carthamus tinctorius suppress tryptophan breakdown via indoleamine 2,3-dioxygenase
Kuehnl, Susanne; Schroecksnadel, Sebastian; Temml, Veronika; Gostner, Johanna M.; Schennach, Harald; Schuster, Daniela; Schwaiger, Stefan; Rollinger, Judith M.; Fuchs, Dietmar; Stuppner, Hermann
2013-01-01
Seed extracts of Carthamus tinctorius L. (Asteraceae), safflower, have been traditionally used to treat coronary disease, thrombotic disorders, and menstrual problems but also against cancer and depression. A possible effect of C. tinctorius compounds on tryptophan-degrading activity of enzyme indoleamine 2,3-dioxygenase (IDO) could explain many of its activities. To test for an effect of C. tinctorius extracts and isolated compounds on cytokine-induced IDO activity in immunocompetent cells in vitro methanol and ethylacetate seed extracts were prepared from cold pressed seed cakes of C. tinctorius and three lignan derivatives, trachelogenin, arctigenin and matairesinol were isolated. The influence on tryptophan breakdown was investigated in peripheral blood mononuclear cells (PBMCs). Effects were compared to neopterin production in the same cellular assay. Both seed extracts suppressed tryptophan breakdown in stimulated PBMC. The three structurally closely related isolates exerted differing suppressive activity on PBMC: arctigenin (IC50 26.5 μM) and trachelogenin (IC50 of 57.4 μM) showed higher activity than matairesinol (IC50 >200 μM) to inhibit tryptophan breakdown. Effects on neopterin production were similar albeit generally less strong. Data show an immunosuppressive property of compounds which slows down IDO activity. The in vitro results support the view that some of the anti-inflammatory, anti-cancer and antidepressant properties of C. tinctorius lignans might relate to their suppressive influence on tryptophan breakdown. PMID:23867649
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HSP90 Inhibition Suppresses Lipopolysaccharide-Induced Lung Inflammation In Vivo
Lilja, Andrew; Weeden, Clare E.; McArthur, Kate; Nguyen, Thao; Donald, Alastair; Wong, Zi Xin; Dousha, Lovisa; Bozinovski, Steve; Vlahos, Ross; Burns, Christopher J.; Asselin-Labat, Marie-Liesse; Anderson, Gary P.
2015-01-01
Inflammation is an important component of cancer diathesis and treatment-refractory inflammation is a feature of many chronic degenerative lung diseases. HSP90 is a 90kDa protein which functions as an ATP-dependent molecular chaperone that regulates the signalling conformation and expression of multiple protein client proteins especially oncogenic mediators. HSP90 inhibitors are in clinical development as cancer therapies but the myeleosuppressive and neutropenic effect of first generation geldanamycin-class inhibitors has confounded studies on the effects on HSP90 inhibitors on inflammation. To address this we assessed the ability of Ganetespib, a non-geldanamycin HSP90 blocker, to suppress lipopolysaccharide (LPS)-induced cellular infiltrates, proteases and inflammatory mediator and transcriptional profiles. Ganetespib (10–100mg/kg, i.v.) did not directly cause myelosuppression, as assessed by video micrography and basal blood cell count, but it strongly and dose-dependently suppressed LPS-induced neutrophil mobilization into blood and neutrophil- and mononuclear cell-rich steroid-refractory lung inflammation. Ganetespib also suppressed B cell and NK cell accumulation, inflammatory cytokine and chemokine induction and MMP9 levels. These data identify non-myelosuppresssive HSP90 inhibitors as potential therapies for inflammatory diseases refractory to conventional therapy, in particular those of the lung. PMID:25615645
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Experimental study on parasitic mode suppression using FeSiAl in relativistic klystron amplifier
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhang, Zehai
2015-03-15
Experimental study of parasitic mode suppression using electromagnetic attenuate material FeSiAl in an S-band Relativistic Klystron Amplifier (RKA) is presented in this paper. The FeSiAl powder is coated and sintered onto the inner surface of a drift tube which locates between the input and the middle cavity of the RKA. Cold tests show that the attenuate rate of the tube against parasitic mode TE{sub 11} is about 50%. Experiments carried out on the Torch-01 accelerator present that the tube is effective in suppressing the parasitic mode. Two typical outputs are obtained. When the diode voltage is on a moderate level,more » the RKA operates well and the parasitic mode is totally suppressed. The pulse length of the High Power Microwave (HPM) almost equals the electron beam pulse length and the HPM average output power is about 300 MW, with a power efficiency of 10%. When the diode voltage is on a higher level, the output power and efficiency rise but the parasitic mode oscillation occurred and the pulse length is shortened. By contrast, the parasitic mode oscillation is too strong for the RKA to operate normally with un-sintered drift tube. The experimental study implies that FeSiAl is effective in suppressing the parasitic mode oscillation in a certain extent. However, total suppression needs a deeper attenuate rate and further investigation.« less
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van Agtmaal, Maaike; van Os, Gera J.; Hol, W.H. Gera; Hundscheid, Maria P.J.; Runia, Willemien T.; Hordijk, Cornelis A.; de Boer, Wietse
2015-01-01
There is increasing evidence that microbial volatiles (VOCs) play an important role in natural suppression of soil-borne diseases, but little is known on the factors that influence production of suppressing VOCs. In the current study we examined whether a stress-induced change in soil microbial community composition would affect the production by soils of VOCs suppressing the plant-pathogenic oomycete Pythium. Using pyrosequencing of 16S ribosomal gene fragments we compared the composition of bacterial communities in sandy soils that had been exposed to anaerobic disinfestation (AD), a treatment used to kill harmful soil organisms, with the composition in untreated soils. Three months after the AD treatment had been finished, there was still a clear legacy effect of the former anaerobic stress on bacterial community composition with a strong increase in relative abundance of the phylum Bacteroidetes and a significant decrease of the phyla Acidobacteria, Planctomycetes, Nitrospirae, Chloroflexi, and Chlorobi. This change in bacterial community composition coincided with loss of production of Pythium suppressing soil volatiles (VOCs) and of suppression of Pythium impacts on Hyacinth root development. One year later, the composition of the bacterial community in the AD soils was reflecting that of the untreated soils. In addition, both production of Pythium-suppressing VOCs and suppression of Pythium in Hyacinth bioassays had returned to the levels of the untreated soil. GC/MS analysis identified several VOCs, among which compounds known to be antifungal, that were produced in the untreated soils but not in the AD soils. These compounds were again produced 15 months after the AD treatment. Our data indicate that soils exposed to a drastic stress can temporarily lose pathogen suppressive characteristics and that both loss and return of these suppressive characteristics coincides with shifts in the soil bacterial community composition. Our data are supporting the suggested importance of microbial VOCs in the natural buffer of soils against diseases caused by soil-borne pathogens. PMID:26217330
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Reflection/suppression coatings for 900 - 1200 A radiation
NASA Technical Reports Server (NTRS)
Edelstein, Jerry
1989-01-01
The design and performance of multiple-layer, selective-reflection, selective-suppression coatings for the 900 - 1200 A band are described. These coatings are designed to optimize both high reflectivity at a desirable wavelength and low reflectivity at an undesirable wavelength. The minimum structure for a selective coating consists of a thin metal or metal oxide layer (50 - 150 A thickness) over an aluminum substrate protected with a semi-transparent dielectric (100 - 1000 A thickness). Predicted coating performance is strongly effected by varying the layer combination and thickness. A graphical method of optimizing the coating layer structure is developed. Aluminum, silicon, their oxides, and gold have been investigated as coating layer materials. A very simple coating with a 1026 to 1216 A reflectivity ratio greater than 100 was fabricated. Such reflection/suppression coatings may be of great utility to spaceborne EUV spectrographs.
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OK-432 Suppresses Proliferation and Metastasis by Tumor Associated Macrophages in Bladder Cancer.
Tian, Yuan-Feng; Tang, Kun; Guan, Wei; Yang, Tao; Xu, Hua; Zhuang, Qian-Yuan; Ye, Zhang-Qun
2015-01-01
OK-432, a Streptococcus-derived anticancer immunotherapeutic agent, has been applied in clinic for many years and achieved great progress in various cancers. In the present study, we investigated its anticancer effect on bladder cancer through tumor associated macrophages (TAMs). MTS assay validated OK-432 could inhibit proliferation in both T24 and EJ bladder cell lines. OK-432 also induced apoptosis of bladder cancer cells in vitro. Consequently, we demonstrated that OK-432 could suppress the bladder cancer cells migration and invasion by altering the EMT-related factors. Furthermore, using SD rat model, we revealed that OK-432 inhibited tumor growth, suppressed PCNA expression and inhibited metastasis in vivo. Taken together, these findings strongly suggest that OK-432 inhibits cell proliferation and metastasis through inducing macrophages to secret cytokines in bladder cancer.
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NASA Astrophysics Data System (ADS)
Mu, Penghua; Pan, Wei; Yan, Lianshan; Luo, Bin; Zou, Xihua
2017-04-01
In this contribution, the effects of two key internal parameters, i.e. the linewidth-enhancement factor (α) and gain nonlinearity (𝜀), on time-delay signatures (TDS) concealment of two mutually-coupled semiconductor lasers (MCSLs) are numerically investigated. In particular, the influences of α and 𝜀 on the TDS concealment are compared and discussed systematically by setting different values of frequency detuning (Δf) and injection strength (η). The results show that the TDS can be better suppressed with high α or lower 𝜀 in the MCSLs. Two sets of desired optical chaos with TDS being strongly suppressed can be generated simultaneously in a wide injection parameter plane provided that α and 𝜀 are properly chosen, indicating that optimizing TDS suppression through controlling internal parameters can be generalized to any delayed-coupled laser systems.
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Perceptual Sensitivity and Response to Strong Stimuli Are Related
Bolders, Anna C.; Tops, Mattie; Band, Guido P. H.; Stallen, Pieter Jan M.
2017-01-01
To shed new light on the long-standing debate about the (in)dependence of sensitivity to weak stimuli and overreactivity to strong stimuli, we examined the relation between these tendencies within the neurobehavioral framework of the Predictive and Reactive Control Systems (PARCS) theory (Tops et al., 2010, 2014). Whereas previous studies only considered overreactivity in terms of the individual tendency to experience unpleasant affect (punishment reactivity) resulting from strong sensory stimulation, we also took the individual tendency to experience pleasant affect (reward reactivity) resulting from strong sensory stimulation into account. According to PARCS theory, these temperamental tendencies overlap in terms of high reactivity toward stimulation, but oppose each other in terms of the response orientation (approach or avoid). PARCS theory predicts that both types of reactivity to strong stimuli relate to sensitivity to weak stimuli, but that these relationships are suppressed due to the opposing relationship between reward and punishment reactivity. We measured punishment and reward reactivity to strong stimuli and sensitivity to weak stimuli using scales from the Adult Temperament Questionnaire (Evans and Rothbart, 2007). Sensitivity was also measured more objectively using the masked auditory threshold. We found that sensitivity to weak stimuli (both self-reported and objectively assessed) was positively associated with self-reported punishment and reward reactivity to strong stimuli, but only when these reactivity measures were controlled for each other, implicating a mutual suppression effect. These results are in line with PARCS theory and suggest that sensitivity to weak stimuli and overreactivity are dependent, but this dependency is likely to be obscured if punishment and reward reactivity are not both taken into account. PMID:29018377
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NASA Astrophysics Data System (ADS)
Yasuda, Hideki; Matsuno, Ryo; Koito, Naoki; Hosoda, Hidemasa; Tani, Takeharu; Naya, Masayuki
2017-12-01
Suppression of visible-light reflection from material surfaces is an important technology for many applications such as flat-panel displays, camera lenses, and solar panels. In this study, we developed an anti-reflective coating design based on a silver nanodisc metasurface. The effective refractive index of a 10-nm-thick monolayer of silver nanodiscs was less than 1.0, which enabled strong suppression of reflection from the underlying substrate. The nanodisc structure was easy to fabricate using a conventional roll-to-roll wet-coating method. The anti-reflective structure was fabricated over a large area.
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Suppression of angiogenesis by atmospheric pressure plasma in human aortic endothelial cells
NASA Astrophysics Data System (ADS)
Gweon, Bomi; Kim, Hyeonyu; Kim, Kijung; Kim, Mina; Shim, Eunyoung; Kim, Sunja; Choe, Wonho; Shin, Jennifer H.
2014-03-01
Atmospheric pressure plasma (APP) has been recognized as a promising tool for cancer therapy based on its ability to remove cancer cells by causing apoptosis and necrosis. However, the effect of APP on the neighboring tissues of tumors remains unknown. Moreover, the role of APP on the vessels near tumors could be very important, because once a tumor becomes vascularized, the potential for metastasis can increase dramatically. We show in the present study that APP can induce cell cycle arrest in endothelial cells and further suppress the angiogenesis process. These results strongly support the use of APP in cancer treatment.
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Zadorsky, S P; Sopova, Y V; Andreichuk, D Y; Startsev, V A; Medvedeva, V P; Inge-Vechtomov, S G
2015-06-01
The SUP35 gene of the yeast Saccharomyces cerevisiae encodes the translation termination factor eRF3. Mutations in this gene lead to the suppression of nonsense mutations and a number of other pleiotropic phenotypes, one of which is impaired chromosome segregation during cell division. Similar effects result from replacing the S. cerevisiae SUP35 gene with its orthologues. A number of genetic and epigenetic changes that occur in the sup35 background result in partial compensation for this suppressor effect. In this study we showed that in S. cerevisiae strains in which the SUP35 orthologue from the yeast Pichia methanolica replaces the S. cerevisiae SUP35 gene, chromosome VIII disomy results in decreased efficiency of nonsense suppression. This antisuppressor effect is not associated with decreased stop codon read-through. We identified SBP1, a gene that localizes to chromosome VIII, as a dosage-dependent antisuppressor that strongly contributes to the overall antisuppressor effect of chromosome VIII disomy. Disomy of chromosome VIII also leads to a change in the yeast strains' tolerance of a number of transition metal salts. Copyright © 2015 John Wiley & Sons, Ltd.
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Chung, Kyung-Sook; An, Hyo-Jin; Cheon, Se-Yun; Kwon, Ki-Rok; Lee, Kwang-Ho
2015-12-01
Benign prostatic hyperplasia (BPH), which is a common disorder in aging men, involves inflammation that is associated with an imbalance between cell proliferation and cell death. Because current BPH drug treatments have undesirable side effects, the development of well-tolerated and effective alternative medicines to treat BPH is of interest. Bee venom (BV) has been used in traditional medicine to treat conditions, such as arthritis and rheumatism, and pain. Although inflammation has been associated with BPH and BV has strong anti-inflammatory effects, the effects of BV on BPH are not fully understood. Therefore, in this study, we evaluated the efficacy of BV against testosterone-induced BPH in rats. BV decreased prostate weight compared to the untreated group. In addition, BV suppressed serum dihydrotestosterone concentration levels and the levels of proliferating cell nuclear antigen in the histological analysis. Furthermore, BV significantly decreased the levels of the apoptotic suppressors, Bcl-2 and Bcl-xL, and increased the levels of the proapoptotic factors, Bax and caspase-3 activation. These results suggested that BV suppressed the development of BPH and has good potential as a treatment for BPH. © 2015 by the Society for Experimental Biology and Medicine.
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Chung, Kyung-Sook; An, Hyo-Jin; Cheon, Se-Yun; Kwon, Ki-Rok
2015-01-01
Benign prostatic hyperplasia (BPH), which is a common disorder in aging men, involves inflammation that is associated with an imbalance between cell proliferation and cell death. Because current BPH drug treatments have undesirable side effects, the development of well-tolerated and effective alternative medicines to treat BPH is of interest. Bee venom (BV) has been used in traditional medicine to treat conditions, such as arthritis and rheumatism, and pain. Although inflammation has been associated with BPH and BV has strong anti-inflammatory effects, the effects of BV on BPH are not fully understood. Therefore, in this study, we evaluated the efficacy of BV against testosterone-induced BPH in rats. BV decreased prostate weight compared to the untreated group. In addition, BV suppressed serum dihydrotestosterone concentration levels and the levels of proliferating cell nuclear antigen in the histological analysis. Furthermore, BV significantly decreased the levels of the apoptotic suppressors, Bcl-2 and Bcl-xL, and increased the levels of the proapoptotic factors, Bax and caspase-3 activation. These results suggested that BV suppressed the development of BPH and has good potential as a treatment for BPH. PMID:26085572
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Ketones prevent synaptic dysfunction induced by mitochondrial respiratory complex inhibitors
Kim, Do Young; Vallejo, Johana; Rho, Jong M
2010-01-01
Abstract Ketones have previously shown beneficial effects in models of neurodegenerative disorders, particularly against associated mitochondrial dysfunction and cognitive impairment. However, evidence of a synaptic protective effect of ketones remains lacking. We tested the effects of ketones on synaptic impairment induced by mitochondrial respiratory complex (MRC) inhibitors using electrophysiological, reactive oxygen species (ROS) imaging and biochemical techniques. MRC inhibitors dose-dependently suppressed both population spike (PS) and field potential amplitudes in the CA1 hippocampus. Pre-treatment with ketones strongly prevented changes in the PS, whereas partial protection was seen in the field potential. Rotenone (Rot; 100 nmol/L), a MRC I inhibitor, suppressed synaptic function without altering ROS levels and PS depression by Rot was unaffected by antioxidants. In contrast, antioxidant-induced PS recovery against the MRC II inhibitor 3-nitropropionic acid (3-NP; 1 mmol/L) was similar to the synaptic protective effects of ketones. Ketones also suppressed ROS generation induced by 3-NP. Finally, ketones reversed the decreases in ATP levels caused by Rot and 3-NP. In summary, our data demonstrate that ketones can preserve synaptic function in CA1 hippocampus induced by MRC dysfunction, likely through an antioxidant action and enhanced ATP generation. PMID:20374433
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Tunability of the fractional quantum Hall states in buckled Dirac materials
NASA Astrophysics Data System (ADS)
Apalkov, Vadym M.; Chakraborty, Tapash
2014-12-01
We report on the fractional quantum Hall states of germanene and silicene where one expects a strong spin-orbit interaction. This interaction causes an enhancement of the electron-electron interaction strength in one of the Landau levels corresponding to the valence band of the system. This enhancement manifests itself as an increase of the fractional quantum Hall effect gaps compared to that in graphene and is due to the spin-orbit induced coupling of the Landau levels of the conduction and valence bands, which modifies the corresponding wave functions and the interaction within a single level. Due to the buckled structure, a perpendicular electric field lifts the valley degeneracy and strongly modifies the interaction effects within a single Landau level: in one valley the perpendicular electric field enhances the interaction strength in the conduction band Landau level, while in another valley, the electric field strongly suppresses the interaction effects.
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USDA-ARS?s Scientific Manuscript database
Monocyte chemoattractant protein-1 (MCP-1) is a well-known chemokine critically involved in the pathophysiological progression of cardiovascular diseases such as arthrosclerosis. N-caffeoyltryptamine is a phenolic amide with strong anti-inflammatory effects. Therefore, in this paper, the potential e...
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USDA-ARS?s Scientific Manuscript database
As the dysregulation of IL-17 is implicated in the pathogenesis of various autoimmune and inflammatory diseases, the suppression of IL-17 production by Th2 cytokines could alleviate the development of these diseases. Previously, we confirmed that inflammatory cytokines including IL-17A are strongly...
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NASA Astrophysics Data System (ADS)
Gentili, Rodolfo; Montagnani, Chiara; Gilardelli, Federica; Guarino, Maria Francesca; Citterio, Sandra
2017-07-01
Ambrosia artemisiifolia is able to dominate the early stages of vegetation succession in open/disturbed habitats, spreading out into available empty niches, after which it can be progressively replaced by perennial plants. In this study, we considered the time-span in which the species is suppressed during active (restoration actions) and passive (spontaneous) vegetation recovery. In particular, we envisaged that A. artemisiifolia growth and fitness may be strongly reduced and that the species may rapidly be suppressed within a short time during succession as a consequence of the increase of vegetation cover, both natural or artificially induced, in a disturbed area of northern Italy. Three different treatments were applied within an abandoned quarry area commonly invaded by A. artemisiifolia: (i) spontaneous succession i.e. (control), (ii) hayseed and (iii) a commercial seed mixture. We determined the effect of mixtures of grassland species, established from native hayseed or from a commercial seed mixture, on A. artemisiifolia growth and fitness traits over time in comparison to a non-seeded area left to spontaneous succession. The results demonstrated that, after the first growing season, compared with spontaneous succession, both commercial seed and hayseed resulted in a strong reduction of A. artemisiifolia abundance and growth rate, in terms of both vegetative and reproductive traits. After the second growing season, A. artemisiifolia was completely suppressed in the commercial seed treatment, and after the third growing season it was also suppressed in the spontaneous succession and hayseed treatments. This study indicated that both active and passive vegetation recovery (by niche filling and competitive exclusion) could be used as methods individually or in combination with other methods, such as mowing and biological control, to suppress A. artemisiifolia from anthropogenic habitats.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Wingen, Andreas; Ferraro, Nathaniel M.; Shafer, Morgan W.
Calculations of the plasma response to applied non-axisymmetric fields in several DIII-D discharges show that predicted displacements depend strongly on the edge current density. This result is found using both a linear two-fluid-MHD model (M3D-C1) and a nonlinear ideal-MHD model (VMEC). Furthermore, it is observed that the probability of a discharge being edge localized mode (ELM)-suppressed is most closely related to the edge current density, as opposed to the pressure gradient. It is found that discharges with a stronger kink response are closer to the peeling–ballooning stability limit in ELITE simulations and eventually cross into the unstable region, causing ELMsmore » to reappear. Thus for effective ELM suppression, the RMP has to prevent the plasma from generating a large kink response, associated with ELM instability. Experimental observations are in agreement with the finding; discharges which have a strong kink response in the MHD simulations show ELMs or ELM mitigation during the RMP phase of the experiment, while discharges with a small kink response in the MHD simulations are fully ELM suppressed in the experiment by the applied resonant magnetic perturbation. The results are cross-checked against modeled 3D ideal MHD equilibria using the VMEC code. The procedure of constructing optimal 3D equilibria for diverted H-mode discharges using VMEC is presented. As a result, kink displacements in VMEC are found to scale with the edge current density, similar to M3D-C1, but the displacements are smaller. A direct correlation in the flux surface displacements to the bootstrap current is shown.« less
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Wingen, Andreas; Ferraro, Nathaniel M.; Shafer, Morgan W.; ...
2015-09-03
Calculations of the plasma response to applied non-axisymmetric fields in several DIII-D discharges show that predicted displacements depend strongly on the edge current density. This result is found using both a linear two-fluid-MHD model (M3D-C1) and a nonlinear ideal-MHD model (VMEC). Furthermore, it is observed that the probability of a discharge being edge localized mode (ELM)-suppressed is most closely related to the edge current density, as opposed to the pressure gradient. It is found that discharges with a stronger kink response are closer to the peeling–ballooning stability limit in ELITE simulations and eventually cross into the unstable region, causing ELMsmore » to reappear. Thus for effective ELM suppression, the RMP has to prevent the plasma from generating a large kink response, associated with ELM instability. Experimental observations are in agreement with the finding; discharges which have a strong kink response in the MHD simulations show ELMs or ELM mitigation during the RMP phase of the experiment, while discharges with a small kink response in the MHD simulations are fully ELM suppressed in the experiment by the applied resonant magnetic perturbation. The results are cross-checked against modeled 3D ideal MHD equilibria using the VMEC code. The procedure of constructing optimal 3D equilibria for diverted H-mode discharges using VMEC is presented. As a result, kink displacements in VMEC are found to scale with the edge current density, similar to M3D-C1, but the displacements are smaller. A direct correlation in the flux surface displacements to the bootstrap current is shown.« less
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PDE5 Inhibitors Enhance Celecoxib Killing in Multiple Tumor Types
BOOTH, LAURENCE; ROBERTS, JANE L.; CRUICKSHANKS, NICHOLA; TAVALLAI, SEYEDMEHRAD; WEBB, TIMOTHY; SAMUEL, PETER; CONLEY, ADAM; BINION, BRITTANY; YOUNG, HAROLD F.; POKLEPOVIC, ANDREW; SPIEGEL, SARAH; DENT, PAUL
2015-01-01
The present studies determined whether clinically relevant phosphodiesterase 5 (PDE5) inhibitors interacted with a clinically relevant NSAID, celecoxib, to kill tumor cells. Celecoxib and PDE5 inhibitors interacted in a greater than additive fashion to kill multiple tumor cell types. Celecoxib and sildenafil killed ex vivo primary human glioma cells as well as their associated activated microglia. Knock down of PDE5 recapitulated the effects of PDE5 inhibitor treatment; the nitric oxide synthase inhibitor L-NAME suppressed drug combination toxicity. The effects of celecoxib were COX2 independent. Over-expression of c-FLIP-s or knock down of CD95/FADD significantly reduced killing by the drug combination. CD95 activation was dependent on nitric oxide and ceramide signaling. CD95 signaling activated the JNK pathway and inhibition of JNK suppressed cell killing. The drug combination inactivated mTOR and increased the levels of autophagy and knock down of Beclin1 or ATG5 strongly suppressed killing by the drug combination. The drug combination caused an ER stress response; knock down of IRE1α/XBP1 enhanced killing whereas knock down of eIF2α/ATF4/CHOP suppressed killing. Sildenafil and celecoxib treatment suppressed the growth of mammary tumors in vivo. Collectively our data demonstrate that clinically achievable concentrations of celecoxib and sildenafil have the potential to be a new therapeutic approach for cancer. PMID:25303541
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Grasman, K A; Fox, G A; Scanlon, P F; Ludwig, J P
1996-01-01
The objectives of study were to determine whether contaminant-associated immunosuppression occurs in prefledgling herring gulls and Caspian terns from the Great Lakes and to evaluate immunological biomarkers for monitoring health effects in wild birds. During 1992 to 1994, immunological responses and related variables were measured in prefledgling chicks at colonies distributed across a broad gradient of organochlorine contamination (primarily polychlorinated biphenyls), which was measured in eggs. The phytohemagglutinin skin test was used to assess T-lymphocyte function. In both species, there was a strong exposure-response relationship between organochlorines and suppressed T-cell-mediated immunity. Suppression was most severe (30-45%) in colonies in Lake Ontario (1992) and Saginaw Bay (1992-1994) for both species and in western Lake Erie (1992) for herring gulls. Both species exhibited biologically significant differences among sites in anti-sheep red blood cells antibody titers, but consistent exposure-response relationships with organochlorines were not observed. In Caspian terns and, to a lesser degree, in herring gulls, there was an exposure-response relationship between organochlorines and reduced plasma retinol (vitamin A). In 1992, altered White blood cell numbers were associated with elevated organochlorine concentrations in Caspian terns but not herring gulls. The immunological and hematological biomarkers used in this study revealed contaminant-associated health effects in wild birds. An epidemiological analysis strongly supported the hypothesis that suppression of T-cell-mediated immunity was associated with high perinatal exposure to persistent organochlorine contaminants. PMID:8880006
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Okai, Y; Higashi-Okai, K; Nakamura, S; Yano, Y; Otani, S
1994-11-25
Some of epidemiological data indicated that ubiquitous consumption of seaweeds in Japan may be a possible protective factor against some types of tumor. To analyse this problem, the authors studied the antimutagenic and antitumor promotion activities in methanol-soluble extracts of typical edible seaweeds which showed suppressive effects on 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indol (Trp-P-1)-induced umu C gene expression in SOS response of Salmonella typhimurium (TA 1535/pSK 1002) and 12-O-tetradecanoylphorbol-13-acetate (TPA)-dependent ornithine decarboxylase induction in BALB/c 3T3 fibroblast cells. Although eight varieties of edible seaweeds including chlorophyta, Phaenophyta and Rhodophyta showed significant antimutagenic and antipromotion activities, they expressed the activities different from each other. Among these seaweeds, Enteromorpha prolifera ('Sujiaonori' in Japanese) and Porphyra tenera ('Asakusanori') showed relatively strong suppressive activities in both antimutagenic and antipromotion assays compared with other seaweeds. These seaweeds contained considerable amounts of beta-carotene as a possible active principle with anticarcinogenic activity. This compound was partially associated with the antimutagenic activity in the seaweed extract, but did not contribute to the antipromotion activity of seaweed extract under our experimental conditions. These results strongly suggest that Japanese edible seaweeds have possible antimutagenic and antipromotion activities probably associated with antitumor activity.
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Quarkonia suppression in PbPb collisions at s N N = 2.76 TeV
Kumar, Vineet; Shukla, Prashant; Vogt, Ramona
2015-08-14
We estimate the modification of quarkonia yields due to different processes in the medium produced in PbPb collisions at LHC energy. The quarkonia and heavy flavor cross sections calculated up to next-to-leading order (NLO) are used in the study. Shadowing corrections are obtained with the NLO EPS09 parametrization. A kinetic model is employed which incorporates quarkonia suppression inside a QGP, suppression due to hadronic comovers, and regeneration from charm pairs. The quarkonia dissociation cross section due to gluon collisions has been considered and the regeneration rate has been obtained using the principle of detailed balance. The modification in quarkonia yieldsmore » due to collisions with hadronic comovers has been estimated assuming that the comovers are pions. The manifestations of these effects on the nuclear modification factors for both J/ψ and Υ in different kinematic regions has been demonstrated for PbPb collisions at √ sNN = 2.76 TeV in comparison with the measurements. Both the suppression and regeneration due to a deconfined medium strongly affect the low and intermediate pT range. As a result, the large observed suppression of J/ψ at p T > 10GeV/c exceeds the estimates of suppression by gluon dissociation.« less
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Graversen, Jonas H; Svendsen, Pia; Dagnæs-Hansen, Frederik; Dal, Jakob; Anton, Gabriele; Etzerodt, Anders; Petersen, Mikkel D; Christensen, Peter A; Møller, Holger J; Moestrup, Søren K
2012-01-01
Synthetic glucocorticoids are potent anti-inflammatory drugs but serious side effects such as bone mobilization, muscle mass loss, immunosuppression, and metabolic alterations make glucocorticoid therapy a difficult balance. The therapeutic anti-inflammatory effect of glucocorticoids relies largely on the suppressed release of tumor-necrosis factor-α and other cytokines by macrophages at the sites of inflammation. We have now developed a new biodegradable anti-CD163 antibody-drug conjugate that specifically targets the glucocorticoid, dexamethasone to the hemoglobin scavenger receptor CD163 in macrophages. The conjugate, that in average contains four dexamethasone molecules per antibody, exhibits retained high functional affinity for CD163. In vitro studies in rat macrophages and in vivo studies of Lewis rats showed a strong anti-inflammatory effect of the conjugate measured as reduced lipopolysaccharide-induced secretion of tumor-necrosis factor-α. The in vivo potency of conjugated dexamethasone was about 50-fold that of nonconjugated dexamethasone. In contrast to a strong systemic effect of nonconjugated dexamethasone, the equipotent dose of the conjugate had no such effect, measured as thymus lymphocytes apoptosis, body weight loss, and suppression of endogenous cortisol levels. In conclusion, the study shows antibody-drug conjugates as a future approach in anti-inflammatory macrophage-directed therapy. Furthermore, the data demonstrate CD163 as an excellent macrophage target for anti-inflammatory drug delivery. PMID:22643864
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2007-10-01
regulates androgen receptor, and finasteride , a 5α-reductase inhibitor, has a synerigistic effect in inhibiting the growth of prostate cancer cells...impact of the selenium and finasteride combination on androgen signaling; 2) Identifying the pro-apoptotic target genes of FOXO1 that are induced by...selenium; 3) studying the potential AR antagonistic effect of finasteride . The last was not proposed in the original application. But we strongly
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Magnetic field control of microstructural development in melt-spun Pr 2 Co 14 B
DOE Office of Scientific and Technical Information (OSTI.GOV)
McGuire, Michael A.; Rios, Orlando; Conner, Ben S.
In the processing of commercial rare earth permanent magnets, use of external magnetic fields is limited mainly to the alignment of anisotropic particles and the polarization of the finished magnets. Here we explore the effects of high magnetic fields on earlier stages of magnet synthesis, including the crystallization and chemical phase transformations that produce the 2:14:1 phase in the Pr-Co-B system. Pr 2Co 14B alloys produced by melt-spinning were annealed in the presence of strong applied magnetic fields (H=90 kOe). The resulting materials were characterized by x-ray diffraction, electron microscopy, and magnetization measurements. We find that magnetic fields suppress themore » nucleation and growth of crystalline phases, resulting in significantly smaller particle sizes. In addition, magnetic fields applied during processing strongly affects chemical phase selection, suppressing the formation of Pr 2Co 14B and α-Co in favor of Pr 2Co 17. Here, the results demonstrate that increased control over key microstructural properties is achievable by including a strong magnetic field as a processing parameter for rare-earth magnet materials.« less
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Magnetic field control of microstructural development in melt-spun Pr 2 Co 14 B
McGuire, Michael A.; Rios, Orlando; Conner, Ben S.; ...
2017-01-27
In the processing of commercial rare earth permanent magnets, use of external magnetic fields is limited mainly to the alignment of anisotropic particles and the polarization of the finished magnets. Here we explore the effects of high magnetic fields on earlier stages of magnet synthesis, including the crystallization and chemical phase transformations that produce the 2:14:1 phase in the Pr-Co-B system. Pr 2Co 14B alloys produced by melt-spinning were annealed in the presence of strong applied magnetic fields (H=90 kOe). The resulting materials were characterized by x-ray diffraction, electron microscopy, and magnetization measurements. We find that magnetic fields suppress themore » nucleation and growth of crystalline phases, resulting in significantly smaller particle sizes. In addition, magnetic fields applied during processing strongly affects chemical phase selection, suppressing the formation of Pr 2Co 14B and α-Co in favor of Pr 2Co 17. Here, the results demonstrate that increased control over key microstructural properties is achievable by including a strong magnetic field as a processing parameter for rare-earth magnet materials.« less
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Yamane, Hitomi; Ihara, Setsunosuke; Kuroda, Masaaki; Nishikawa, Akio
2011-08-01
Larval-to-adult myogenic conversion occurs in the dorsal muscle but not in the tail muscle during Xenopus laevis metamorphosis. To know the mechanism for tail-specific suppression of adult myogenesis, response character was compared between adult myogenic cells (Ad-cells) and larval tail myogenic cells (La-cells) to a Sonic hedgehog (Shh) inhibitor, notochord (Nc) cells, and spinal cord (SC) cells in vitro. Cyclopamine, an Shh inhibitor, suppressed the differentiation of cultured Ad (but not La) cells, suggesting the significance of Shh signaling in promoting adult myogenesis. To test the possibility that Shh-producing axial elements (notochord and spinal cord) regulate adult myogenesis, Ad-cells or La-cells were co-cultured with Nc or SC cells. The results showed that differentiation of Ad-cells were strongly inhibited by Nc cells but promoted by SC cells. If Ad-cells were "separately" co-cultured with Nc cells without direct cell-cell interactions, adult differentiation was not inhibited but rather promoted, suggesting that Nc cells have two roles, one is a short-range suppression and another is a long-range promotion for adult myogenesis. Immunohistochemical analysis showed both notochord and spinal cord express the N-terminal Shh fragment throughout metamorphosis. The "spinal cord-promotion" and long-range effect by Nc cells on adult myogenesis is thus involved in Shh signaling, while the signaling concerning the short-range "Nc suppression" will be determined by future studies. Interestingly, these effects, "Nc suppression" and "SC promotion" were not observed for La-cells. Situation where the spinal cord/notochord cross-sectional ratio is quite larger in tadpole trunk than in the tail seems to contribute to trunk-specific promotion and tail-specific suppression of adult myogenesis during Xenopus metamorphosis.
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Cavity Quantum Acoustic Device in the Multimode Strong Coupling Regime
NASA Astrophysics Data System (ADS)
Moores, Bradley A.; Sletten, Lucas R.; Viennot, Jeremie J.; Lehnert, K. W.
2018-06-01
We demonstrate an acoustical analog of a circuit quantum electrodynamics system that leverages acoustic properties to enable strong multimode coupling in the dispersive regime while suppressing spontaneous emission to unconfined modes. Specifically, we fabricate and characterize a device that comprises a flux tunable transmon coupled to a 300 μ m long surface acoustic wave resonator. For some modes, the qubit-cavity coupling reaches 6.5 MHz, exceeding the cavity loss rate (200 kHz), qubit linewidth (1.1 MHz), and the cavity free spectral range (4.8 MHz), placing the device in both the strong coupling and strong multimode regimes. With the qubit detuned from the confined modes of the cavity, we observe that the qubit linewidth strongly depends on its frequency, as expected for spontaneous emission of phonons, and we identify operating frequencies where this emission rate is suppressed.
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Turbulent edge transport in the Princeton Beta Experiment-Modified high confinement mode
NASA Astrophysics Data System (ADS)
Tynan, G. R.; Schmitz, L.; Blush, L.; Boedo, J. A.; Conn, R. W.; Doerner, R.; Lehmer, R.; Moyer, R.; Kugel, H.; Bell, R.; Kaye, S.; Okabayashi, M.; Sesnic, S.; Sun, Y.
1994-10-01
The first probe measurements of edge turbulence and transport in a neutral beam induced high confinement mode (H-mode) are reported. A strong negative radial electric field is directly observed in H-mode. A transient suppression of normalized ion saturation and floating potential fluctuation levels occurs at the low confinement mode to high confinement mode (L-H) transition, followed by a recovery to near low mode (L-mode) levels. The average poloidal wave number and the poloidal wave-number spectral width are decreased, and the correlation between fluctuating density and potential is reduced. A large-amplitude coherent oscillation, localized to the strong radial electric field region, is observed in H-mode but does not cause transport. In H-mode the effective turbulent diffusion coefficient is reduced by an order of magnitude inside the last closed flux surface and in the scrape-off layer. The results are compared with a heuristic model of turbulence suppression by velocity-shear stabilization.
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Lappaol F, a novel anticancer agent isolated from plant arctium Lappa L.
Sun, Qing; Liu, Kanglun; Shen, Xiaoling; Jin, Weixin; Jiang, Lingyan; Sheikh, M Saeed; Hu, Yingjie; Huang, Ying
2014-01-01
In an effort to search for new cancer-fighting therapeutics, we identified a novel anticancer constituent, Lappaol F, from plant Arctium Lappa L. Lappaol F suppressed cancer cell growth in a time- and dose-dependent manner in human cancer cell lines of various tissue types. We found that Lappaol F induced G(1) and G(2) cell-cycle arrest, which was associated with strong induction of p21 and p27 and reduction of cyclin B1 and cyclin-dependent kinase 1 (CDK1). Depletion of p21 via genetic knockout or short hairpin RNA (shRNA) approaches significantly abrogated Lappaol F-mediated G(2) arrest and CDK1 and cyclin B1 suppression. These results suggest that p21 seems to play a crucial role in Lappaol F-mediated regulation of CDK1 and cyclin B1 and G(2) arrest. Lappaol F-mediated p21 induction was found to occur at the mRNA level and involved p21 promoter activation. Lappaol F was also found to induce cell death in several cancer cell lines and to activate caspases. In contrast with its strong growth inhibitory effects on tumor cells, Lappaol F had minimal cytotoxic effects on nontumorigenic epithelial cells tested. Importantly, our data also demonstrate that Lappaol F exhibited strong growth inhibition of xenograft tumors in nude mice. Lappaol F was well tolerated in treated animals without significant toxicity. Taken together, our results, for the first time, demonstrate that Lappaol F exhibits antitumor activity in vitro and in vivo and has strong potential to be developed as an anticancer therapeutic.
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Resveratrol suppresses growth of cancer stem-like cells by inhibiting fatty acid synthase.
Pandey, Puspa R; Okuda, Hiroshi; Watabe, Misako; Pai, Sudha K; Liu, Wen; Kobayashi, Aya; Xing, Fei; Fukuda, Koji; Hirota, Shigeru; Sugai, Tamotsu; Wakabayashi, Go; Koeda, Keisuke; Kashiwaba, Masahiro; Suzuki, Kazuyuki; Chiba, Toshimi; Endo, Masaki; Fujioka, Tomoaki; Tanji, Susumu; Mo, Yin-Yuan; Cao, Deliang; Wilber, Andrew C; Watabe, Kounosuke
2011-11-01
Resveratrol is a natural polyphenolic compound and has been shown to exhibit cardio-protective as well as anti-neoplastic effects on various types of cancers. However, the exact mechanism of its anti-tumor effect is not clearly defined. Resveratrol has been shown to have strong hypolipidemic effect on normal adipocytes and as hyper-lipogenesis is a hallmark of cancer cell physiology, the effect of resveratrol on lipid synthesis in cancer stem-like cells (CD24(-)/CD44(+)/ESA(+)) that were isolated from both ER+ and ER- breast cancer cell lines was examined. The authors found that resveratrol significantly reduced the cell viability and mammosphere formation followed by inducing apoptosis in cancer stem-like cells. This inhibitory effect of resveratrol is accompanied by a significant reduction in lipid synthesis which is caused by the down-regulation of the fatty acid synthase (FAS) gene followed by up-regulation of pro-apoptotic genes, DAPK2 and BNIP3. The activation of apoptotic pathway in the cancer stem-like cells was suppressed by TOFA and by Fumonisin B1, suggesting that resveratrol-induced apoptosis is indeed through the modulation of FAS-mediated cell survival signaling. Importantly, resveratrol was able to significantly suppress the growth of cancer stem-like cells in an animal model of xenograft without showing apparental toxicity. Taken together, the results of this study indicate that resveratrol is capable of inducing apoptosis in the cancer stem-like cells through suppression of lipogenesis by modulating FAS expression, which highlights a novel mechanism of anti-tumor effect of resveratrol.
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Resveratrol suppresses growth of cancer stem-like cells by inhibiting fatty acid synthase
Pandey, Puspa R.; Okuda, Hiroshi; Watabe, Misako; Pai, Sudha K.; Liu, Wen; Kobayashi, Aya; Xing, Fei; Fukuda, Koji; Hirota, Shigeru; Sugai, Tamotsu; Wakabayashi, Go; Koeda, Keisuke; Kashiwaba, Masahiro; Suzuki, Kazuyuki; Chiba, Toshimi; Endo, Masaki; Fujioka, Tomoaki; Tanji, Susumu; Mo, Yin-Yuan; Cao, Deliang; Wilber, Andrew C.; Watabe, Kounosuke
2012-01-01
Resveratrol is a natural polyphenolic compound and has been shown to exhibit cardio-protective as well as anti-neoplastic effects on various types of cancers. However, the exact mechanism of its anti-tumor effect is not clearly defined. Resveratrol has been shown to have strong hypolipidemic effect on normal adipocytes and as hyper-lipogenesis is a hallmark of cancer cell physiology, we examined the effect of resveratrol on lipid synthesis in cancer stem-like cells (CD24−/CD44+/ESA+) that were isolated from both ER+ and ER− breast cancer cell lines. We found that resveratrol significantly reduced the cell viability and mammosphere formation followed by inducing apoptosis in cancer stem-like cells. This inhibitory effect of resveratrol is accompanied by a significant reduction in lipid synthesis which is caused by the down-regulation of the fatty acid synthase (FAS) gene followed by up-regulation of pro-apoptotic genes, DAPK2 and BNIP3. The activation of apoptotic pathway in the cancer stem-like cells was suppressed by TOFA and by Fumonisin B1, suggesting that resveratrol-induced apoptosis is indeed through the modulation of FAS-mediated cell survival signaling. Importantly, resveratrol was able to significantly suppress the growth of cancer stem-like cells in an animal model of xenograft without showing apparental toxicity. Taken together, our results indicate that resveratrol is capable of inducing apoptosis in the cancer stem-like cells through suppression of lipogenesis by modulating FAS expression, which highlights a novel mechanism of anti-tumor effect of resveratrol. PMID:21188630
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Suppression of Self-Induced Flavor Conversion in the Supernova Accretion Phase
NASA Astrophysics Data System (ADS)
Sarikas, Srdjan; Raffelt, Georg G.; Hüdepohl, Lorenz; Janka, Hans-Thomas
2012-02-01
Self-induced flavor conversions of supernova (SN) neutrinos can strongly modify the flavor-dependent fluxes. We perform a linearized flavor stability analysis with accretion-phase matter profiles of a 15M⊙ spherically symmetric model and corresponding neutrino fluxes. We use realistic energy and angle distributions, the latter deviating strongly from quasi-isotropic emission, thus accounting for both multiangle and multienergy effects. For our matter and neutrino density profile we always find stable conditions: flavor conversions are limited to the usual Mikheyev-Smirnov-Wolfenstein effect. In this case one may distinguish the neutrino mass hierarchy in a SN neutrino signal if the mixing angle θ13 is as large as suggested by recent experiments.
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Suppression of self-induced flavor conversion in the supernova accretion phase.
Sarikas, Srdjan; Raffelt, Georg G; Hüdepohl, Lorenz; Janka, Hans-Thomas
2012-02-10
Self-induced flavor conversions of supernova (SN) neutrinos can strongly modify the flavor-dependent fluxes. We perform a linearized flavor stability analysis with accretion-phase matter profiles of a 15M[symbol: see text] spherically symmetric model and corresponding neutrino fluxes. We use realistic energy and angle distributions, the latter deviating strongly from quasi-isotropic emission, thus accounting for both multiangle and multienergy effects. For our matter and neutrino density profile we always find stable conditions: flavor conversions are limited to the usual Mikheyev-Smirnov-Wolfenstein effect. In this case one may distinguish the neutrino mass hierarchy in a SN neutrino signal if the mixing angle θ13 is as large as suggested by recent experiments.
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Xu, Huawei; Zhang, Jianjun; Zeng, Jiwu; Jiang, Linrong; Liu, Ee; Peng, Changlian; He, Zhenghui; Peng, Xinxiang
2009-01-01
Photorespiration is one of the most intensively studied topics in plant biology. While a number of mutants deficient in photorespiratory enzymes have been identified and characterized for their physiological functions, efforts on glycolate oxidase (GLO; EC 1.1.3.15) have not been so successful. This is a report about the generation of transgenic rice (Oryza sativa L.) plants carrying a GLO antisense gene driven by an estradiol-inducible promoter, which allowed for controllable suppressions of GLO and its detailed functional analyses. The GLO-suppressed plants showed typical photorespiration-deficient phenotypes. More intriguingly, it was found that a positive and linear correlation existed between GLO activities and the net photosynthetic rates (P(N)), and photoinhibition subsequently occurred once P(N) reduction surpassed 60%, indicating GLO can exert a strong regulation over photosynthesis. Various expression analyses identified that Rubisco activase was transcriptionally suppressed in the GLO-suppressed plants, consistent with the decreased Rubisco activation states. While the substrate glycolate accumulated substantially, few changes were observed for the product glyoxylate, and for some other downstream metabolites or genes as well in the transgenic plants. Further analyses revealed that isocitrate lyase and malate synthase, two key enzymes in the glyoxylate cycle, were highly up-regulated under GLO deficiency. Taken together, the results suggest that GLO is a typical photorespiratory enzyme and that it can exert a strong regulation over photosynthesis, possibly through a feed-back inhibition on Rubisco activase, and that the glyoxylate cycle may be partially activated to compensate for the photorespiratory glyoxylate when GLO is suppressed in rice.
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Productions of η, ρ0 and ϕ at large transverse momentum in Heavy ion Collisions
NASA Astrophysics Data System (ADS)
Dai, Wei; Zhang, Ben-Wei
2017-08-01
The suppression of the productions of the η meson in relativistic heavy-ion collisions and its ratio of η /π0 are computed theoretically in the framework of the perturbative QCD(pQCD) to confront the experimental data which matches well. We explore how the hadron production ratios as η /π0 would further disclose the informations of the production suppressions due to the energy loss of the energetic jet that propagating though the QGP medium. Also, we present our further studies on vector mesons such as ρ0 and ϕ within the same framework. The theoretical predictions based on pQCD are thus firstly given which give a decent description on the experimental measurements. It paved the way to the uniformly understanding of the strong suppression of single hadron productions at large transverse momentum which is a convincing evidence of the jet quenching effect.
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MIRDAMADI, J. L.; SUZUKI, L. Y.; MEEHAN, S. K.
2018-01-01
Knowledge of the properties that govern the effectiveness of transcranial magnetic stimulation (TMS) interventions is critical to clinical application. Extrapolation to clinical populations has been limited by high inter-subject variability and a focus on intrinsic muscles of the hand in healthy populations. Therefore, the current study assessed variability of continuous theta burst stimulation (cTBS), a patterned TMS protocol, across an agonist–antagonist pair of extrinsic muscles of the hand. Secondarily, we assessed whether concurrent agonist contraction could enhance the efficacy of cTBS. Motor evoked potentials (MEP) were simultaneously recorded from the agonist flexor (FCR) and antagonist extensor (ECR) carpi radialis before and after cTBS over the FCR hotspot. cTBS was delivered with the FCR relaxed (cTBS-Relax) or during isometric wrist flexion (cTBS-Contract). cTBS-Relax suppressed FCR MEPs evoked from the FCR hotspot. However, the extent of FCR MEP suppression was strongly correlated with the relative difference between FCR and ECR resting motor thresholds. cTBS-Contract decreased FCR suppression but increased suppression of ECR MEPs elicited from the FCR hotspot. The magnitude of ECR MEP suppression following cTBS-Contract was independent of the threshold-amplitude relationships observed with cTBS-Relax. Contraction alone had no effect confirming the effect of cTBS-Contract was driven by the interaction between neuromuscular activity and cTBS. Interactions across muscle representations should be taken into account when predicting cTBS outcomes in healthy and clinical populations. Contraction during cTBS may be a useful means of focusing aftereffects when differences in baseline excitability across overlapping agonist–antagonist cortical representations may mitigate the inhibitory effect of cTBS. PMID:27425211
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Kuroyanagi, Gen; Otsuka, Takanobu; Yamamoto, Naohiro; Matsushima-Nishiwaki, Rie; Nakakami, Akira; Mizutani, Jun; Kozawa, Osamu; Tokuda, Haruhiko
2014-01-01
It is firmly established that resveratrol, a natural food compound abundantly found in grape skins and red wine, has beneficial properties for human health. In the present study, we investigated the effect of basic fibroblast growth factor (FGF-2) on osteoprotegerin (OPG) synthesis in osteoblast-like MC3T3-E1 cells and whether resveratrol affects the OPG synthesis. FGF-2 stimulated both the OPG release and the expression of OPG mRNA. Resveratrol significantly suppressed the FGF-2-stimulated OPG release and the mRNA levels of OPG. SRT1720, an activator of SIRT1, reduced the FGF-2-induced OPG release and the OPG mRNA expression. PD98059, an inhibitor of upstream kinase activating p44/p42 mitogen-activated protein (MAP) kinase, had little effect on the FGF-2-stimulated OPG release. On the other hand, SB203580, an inhibitor of p38 MAP kinase, SP600125, an inhibitor of stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), and Akt inhibitor suppressed the OPG release induced by FGF-2. Resveratrol failed to affect the FGF-2-induced phosphorylation of p44/p42 MAP kinase, p38 MAP kinase or SAPK/JNK. The phosphorylation of Akt induced by FGF-2 was significantly suppressed by resveratrol or SRT1720. These findings strongly suggest that resveratrol down-regulates FGF-2-stimulated OPG synthesis through the suppression of the Akt pathway in osteoblasts and that the inhibitory effect of resveratrol is mediated at least in part by SIRT1 activation. PMID:25290095
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Schallmo, Michael-Paul; Grant, Andrea N; Burton, Philip C; Olman, Cheryl A
2016-08-01
Although V1 responses are driven primarily by elements within a neuron's receptive field, which subtends about 1° visual angle in parafoveal regions, previous work has shown that localized fMRI responses to visual elements reflect not only local feature encoding but also long-range pattern attributes. However, separating the response to an image feature from the response to the surrounding stimulus and studying the interactions between these two responses demands both spatial precision and signal independence, which may be challenging to attain with fMRI. The present study used 7 Tesla fMRI with 1.2-mm resolution to measure the interactions between small sinusoidal grating patches (targets) at 3° eccentricity and surrounds of various sizes and orientations to test the conditions under which localized, context-dependent fMRI responses could be predicted from either psychophysical or electrophysiological data. Targets were presented at 8%, 16%, and 32% contrast while manipulating (a) spatial extent of parallel (strongly suppressive) or orthogonal (weakly suppressive) surrounds, (b) locus of attention, (c) stimulus onset asynchrony between target and surround, and (d) blocked versus event-related design. In all experiments, the V1 fMRI signal was lower when target stimuli were flanked by parallel versus orthogonal context. Attention amplified fMRI responses to all stimuli but did not show a selective effect on central target responses or a measurable effect on orientation-dependent surround suppression. Suppression of the V1 fMRI response by parallel surrounds was stronger than predicted from psychophysics but showed a better match to previous electrophysiological reports.
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Li, Ai-Rong; Smith, Sally E; Smith, F Andrew; Guan, Kai-Yun
2012-05-01
Plant parasitism and arbuscular mycorrhizal (AM) associations have many parallels and share a number of regulatory pathways. Despite a rapid increase in investigations addressing the roles of AM fungi in regulating interactions between parasitic plants and their hosts, few studies have tested the effect of AM fungi on the initiation and differentiation of haustoria, the parasite-specific structures exclusively responsible for host attachment and nutrient transfer. In this study, we tested the influence of AM fungi on haustorium formation in a root hemiparasitic plant. Using a facultative root hemiparasitic species (Pedicularis tricolor) with the potential to form AM associations, the effects of inoculation were tested with two AM fungal species, Glomus mosseae and Glomus intraradices, on haustorium initiation in P. tricolor grown alone or with Hordeum vulgare 'Fleet' (barley) as the host plant. This study consisted of two greenhouse pot experiments. Both AM fungal species dramatically suppressed intraspecific haustorium initiation in P. tricolor at a very low colonization level. The suppression over-rode inductive effects of the parasite's host plant on haustoria production and caused significant growth depression of P. tricolor. AM fungi had strong and direct suppressive effects on haustorium formation in the root hemiparasite. The significant role of AM fungi in haustorium initiation of parasitic plants was demonstrated for the first time. This study provides new clues for the regulation of haustorium formation and a route to development of new biocontrol strategies in management of parasitic weeds.
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On viscoelastic cavitating flows: A numerical study
NASA Astrophysics Data System (ADS)
Naseri, Homa; Koukouvinis, Phoevos; Malgarinos, Ilias; Gavaises, Manolis
2018-03-01
The effect of viscoelasticity on turbulent cavitating flow inside a nozzle is simulated for Phan-Thien-Tanner (PTT) fluids. Two different flow configurations are used to show the effect of viscoelasticity on different cavitation mechanisms, namely, cloud cavitation inside a step nozzle and string cavitation in an injector nozzle. In incipient cavitation condition in the step nozzle, small-scale flow features including cavitating microvortices in the shear layer are suppressed by viscoelasticity. Flow turbulence and mixing are weaker compared to the Newtonian fluid, resulting in suppression of microcavities shedding from the cavitation cloud. Moreover, mass flow rate fluctuations and cavity shedding frequency are reduced by the stabilizing effect of viscoelasticity. Time averaged values of the liquid volume fraction show that cavitation formation is strongly suppressed in the PTT viscoelastic fluid, and the cavity cloud is pushed away from the nozzle wall. In the injector nozzle, a developed cloud cavity covers the nozzle top surface, while a vortex-induced string cavity emerges from the turbulent flow inside the sac volume. Similar to the step nozzle case, viscoelasticity reduces the vapor volume fraction in the cloud region. However, formation of the streamwise string cavity is stimulated as turbulence is suppressed inside the sac volume and the nozzle orifice. Vortical perturbations in the vicinity of the vortex are damped, allowing more vapor to develop in the string cavity region. The results indicate that the effect of viscoelasticity on cavitation depends on the alignment of the cavitating vortices with respect to the main flow direction.
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Varadarajan, Deepa K; Karthikeyan, Athikkattuvalasu S; Matilda, Paino Durzo; Raghothama, Kashchandra G
2002-07-01
Phosphate (Pi) and its analog phosphite (Phi) are acquired by plants via Pi transporters. Although the uptake and mobility of Phi and Pi are similar, there is no evidence suggesting that plants can utilize Phi as a sole source of phosphorus. Phi is also known to interfere with many of the Pi starvation responses in plants and yeast (Saccharomyces cerevisiae). In this study, effects of Phi on plant growth and coordinated expression of genes induced by Pi starvation were analyzed. Phi suppressed many of the Pi starvation responses that are commonly observed in plants. Enhanced root growth and root to shoot ratio, a hallmark of Pi stress response, was strongly inhibited by Phi. The negative effects of Phi were not obvious in plants supplemented with Pi. The expression of Pi starvation-induced genes such as LePT1, LePT2, AtPT1, and AtPT2 (high-affinity Pi transporters); LePS2 (a novel acid phosphatase); LePS3 and TPSI1 (novel genes); and PAP1 (purple acid phosphatase) was suppressed by Phi in plants and cell cultures. Expression of luciferase reporter gene driven by the Pi starvation-induced AtPT2 promoter was also suppressed by Phi. These analyses showed that suppression of Pi starvation-induced genes is an early response to addition of Phi. These data also provide evidence that Phi interferes with gene expression at the level of transcription. Synchronized suppression of multiple Pi starvation-induced genes by Phi points to its action on the early molecular events, probably signal transduction, in Pi starvation response.
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Non-Maxwellian fast particle effects in gyrokinetic GENE simulations
NASA Astrophysics Data System (ADS)
Di Siena, A.; Görler, T.; Doerk, H.; Bilato, R.; Citrin, J.; Johnson, T.; Schneider, M.; Poli, E.; JET Contributors
2018-04-01
Fast ions have recently been found to significantly impact and partially suppress plasma turbulence both in experimental and numerical studies in a number of scenarios. Understanding the underlying physics and identifying the range of their beneficial effect is an essential task for future fusion reactors, where highly energetic ions are generated through fusion reactions and external heating schemes. However, in many of the gyrokinetic codes fast ions are, for simplicity, treated as equivalent-Maxwellian-distributed particle species, although it is well known that to rigorously model highly non-thermalised particles, a non-Maxwellian background distribution function is needed. To study the impact of this assumption, the gyrokinetic code GENE has recently been extended to support arbitrary background distribution functions which might be either analytical, e.g., slowing down and bi-Maxwellian, or obtained from numerical fast ion models. A particular JET plasma with strong fast-ion related turbulence suppression is revised with these new code capabilities both with linear and nonlinear gyrokinetic simulations. It appears that the fast ion stabilization tends to be less strong but still substantial with more realistic distributions, and this improves the quantitative power balance agreement with experiments.
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Nonlinear simulations of particle source effects on edge localized mode
DOE Office of Scientific and Technical Information (OSTI.GOV)
Huang, J.; Tang, C. J.; Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064
2015-12-15
The effects of particle source (PS) with different intensities and located positions on Edge Localized Mode (ELM) are systematically studied with BOUT++ code. The results show the ELM size strongly decreases with increasing the PS intensity once the PS is located in the middle or bottom of the pedestal. The effects of PS on ELM depend on the located position of PS. When it is located at the top of the pedestal, peeling-ballooning (P-B) modes can extract more free energy from the pressure gradient and grow up to be a large filament at the initial crash phase and the broadeningmore » of mode spectrum can be suppressed by PS, which leads to more energy loss. When it is located in the middle or bottom of the pedestal, the extraction of free energy by P-B modes can be suppressed, and a small filament is generated. During the turbulence transport phase, the broader mode spectrum suppresses the turbulence transport when PS is located in the middle, while the zonal flow plays an important role in damping the turbulence transport when PS is located at the bottom.« less
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Vandecasteele, Marie; Varga, Viktor; Berényi, Antal; Papp, Edit; Barthó, Péter; Venance, Laurent; Freund, Tamás F; Buzsáki, György
2014-09-16
Theta oscillations in the limbic system depend on the integrity of the medial septum. The different populations of medial septal neurons (cholinergic and GABAergic) are assumed to affect different aspects of theta oscillations. Using optogenetic stimulation of cholinergic neurons in ChAT-Cre mice, we investigated their effects on hippocampal local field potentials in both anesthetized and behaving mice. Cholinergic stimulation completely blocked sharp wave ripples and strongly suppressed the power of both slow oscillations (0.5-2 Hz in anesthetized, 0.5-4 Hz in behaving animals) and supratheta (6-10 Hz in anesthetized, 10-25 Hz in behaving animals) bands. The same stimulation robustly increased both the power and coherence of theta oscillations (2-6 Hz) in urethane-anesthetized mice. In behaving mice, cholinergic stimulation was less effective in the theta (4-10 Hz) band yet it also increased the ratio of theta/slow oscillation and theta coherence. The effects on gamma oscillations largely mirrored those of theta. These findings show that medial septal cholinergic activation can both enhance theta rhythm and suppress peri-theta frequency bands, allowing theta oscillations to dominate.
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NASA Astrophysics Data System (ADS)
Zhao, Defeng; Schmitt, Sebastian H.; Wang, Mingjin; Acir, Ismail-Hakki; Tillmann, Ralf; Tan, Zhaofeng; Novelli, Anna; Fuchs, Hendrik; Pullinen, Iida; Wegener, Robert; Rohrer, Franz; Wildt, Jürgen; Kiendler-Scharr, Astrid; Wahner, Andreas; Mentel, Thomas F.
2018-02-01
Anthropogenic emissions such as NOx and SO2 influence the biogenic secondary organic aerosol (SOA) formation, but detailed mechanisms and effects are still elusive. We studied the effects of NOx and SO2 on the SOA formation from the photooxidation of α-pinene and limonene at ambient relevant NOx and SO2 concentrations (NOx: < 1to 20 ppb, SO2: < 0.05 to 15 ppb). In these experiments, monoterpene oxidation was dominated by OH oxidation. We found that SO2 induced nucleation and enhanced SOA mass formation. NOx strongly suppressed not only new particle formation but also SOA mass yield. However, in the presence of SO2 which induced a high number concentration of particles after oxidation to H2SO4, the suppression of the mass yield of SOA by NOx was completely or partly compensated for. This indicates that the suppression of SOA yield by NOx was largely due to the suppressed new particle formation, leading to a lack of particle surface for the organics to condense on and thus a significant influence of vapor wall loss on SOA mass yield. By compensating for the suppressing effect on nucleation of NOx, SO2 also compensated for the suppressing effect on SOA yield. Aerosol mass spectrometer data show that increasing NOx enhanced nitrate formation. The majority of the nitrate was organic nitrate (57-77 %), even in low-NOx conditions (< ˜ 1 ppb). Organic nitrate contributed 7-26 % of total organics assuming a molecular weight of 200 g mol-1. SOA from α-pinene photooxidation at high NOx had a generally lower hydrogen to carbon ratio (H / C), compared to low NOx. The NOx dependence of the chemical composition can be attributed to the NOx dependence of the branching ratio of the RO2 loss reactions, leading to a lower fraction of organic hydroperoxides and higher fractions of organic nitrates at high NOx. While NOx suppressed new particle formation and SOA mass formation, SO2 can compensate for such effects, and the combining effect of SO2 and NOx may have an important influence on SOA formation affected by interactions of biogenic volatile organic compounds (VOCs) with anthropogenic emissions.
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Suppressive effects of fisetin on mice T lymphocytes in vitro and in vivo.
Song, Bocui; Guan, Shuang; Lu, Jing; Chen, Zhibao; Huang, Guoren; Li, Gen; Xiong, Ying; Zhang, Shuang; Yue, Zhanpeng; Deng, Xuming
2013-11-01
Most of the immunosuppressive drugs have satisfactory therapeutic effects on organ transplantation and autoimmune disease. However, their clinical application is limited by side effects. Therefore, new and safe immunosuppressive drugs against acute and chronic rejections are eagerly awaited. Fisetin, a flavonoid present in various types of vegetables and fruits, has few side effects and low level of toxicity, which would be a desirable clinical feature. In the present study, we investigated the immunosuppressive effects and underlying mechanisms of fisetin against T-cell activation in vitro and in vivo. We measured the effect of fisetin on T-lymphocyte proliferation, T-cell subsets, cell cycle progression, cytokine production, and nuclear factor activation in vitro, as well as its influence on T cell-mediated delayed-type hypersensitivity reaction in vivo. In vitro, the results showed that fisetin significantly suppressed mouse splenocytes proliferation, Th1 and Th2 cytokine production, cell cycle and the ratio of CD4(+)/CD8(+) T cells. Furthermore, fisetin exerts an immunosuppressive effect in mouse T lymphocytes through the suppression of nuclear factor kappa B activation and nuclear factor of activated T cells signaling in a dose-dependent manner. In vivo, fisetin treatment also significantly inhibited the dinitrofluorobenzene-induced delayed-type hypersensitivity reactions in mice. Fisetin had strong immunosuppressive activity in vitro and in vivo, suggesting a potential role for fisetin as an immunosuppressive agent. Copyright © 2013. Published by Elsevier Inc.
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NASA Astrophysics Data System (ADS)
Sadeghi, Seyed M.; Wing, Waylin J.; Gutha, Rithvik R.; Sharp, Christina
2018-01-01
We demonstrate that a metal-oxide plasmonic metafilm consisting of a Si/Al oxide junction in the vicinity of a thin gold layer can quarantine excitons in colloidal semiconductor quantum dots against their defect environments. This process happens while the plasmon fields of the gold layer enhance spontaneous emission decay rates of the quantum dots. We study the emission dynamics of such quantum dots when the distance between the Si/Al oxide junction and the gold thin layer is varied. The results show that for distances less than a critical value the lifetime of the quantum dots can be elongated while they experience intense plasmon fields. This suggests that the metal-oxide metafilm can keep photo-excited electrons in the cores of the quantum dots, suppressing their migration to the surface defect sites. This leads to suppression of Auger recombination, offering quantum dot super-emitters with emission that is enhanced not only by the plasmon fields (Purcell effect), but also by strong suppression of the non-radiative decay caused by the defect sites.
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Cavity Quantum Acoustic Device in the Multimode Strong Coupling Regime.
Moores, Bradley A; Sletten, Lucas R; Viennot, Jeremie J; Lehnert, K W
2018-06-01
We demonstrate an acoustical analog of a circuit quantum electrodynamics system that leverages acoustic properties to enable strong multimode coupling in the dispersive regime while suppressing spontaneous emission to unconfined modes. Specifically, we fabricate and characterize a device that comprises a flux tunable transmon coupled to a 300 μm long surface acoustic wave resonator. For some modes, the qubit-cavity coupling reaches 6.5 MHz, exceeding the cavity loss rate (200 kHz), qubit linewidth (1.1 MHz), and the cavity free spectral range (4.8 MHz), placing the device in both the strong coupling and strong multimode regimes. With the qubit detuned from the confined modes of the cavity, we observe that the qubit linewidth strongly depends on its frequency, as expected for spontaneous emission of phonons, and we identify operating frequencies where this emission rate is suppressed.
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Influence of removal of invisible fixation on the saccadic and manual gap effect.
Ueda, Hiroshi; Takahashi, Kohske; Watanabe, Katsumi
2014-01-01
Saccadic and manual reactions to a peripherally presented target are facilitated by removing a central fixation stimulus shortly before a target onset (the gap effect). The present study examined the effects of removal of a visible and invisible fixation point on the saccadic gap effect and the manual gap effect. Participants were required to fixate a central fixation point and respond to a peripherally presented target as quickly and accurately as possible by making a saccade (Experiment 1) or pressing a corresponding key (Experiment 2). The fixation point was dichoptically presented, and visibility was manipulated by using binocular rivalry and continuous flash suppression technique. In both saccade and key-press tasks, removing the visible fixation strongly quickened the responses. Furthermore, the invisible fixation, which remained on the display but suppressed, significantly delayed the saccadic response. Contrarily, the invisible fixation had no effect on the manual task. These results indicate that partially different processes mediate the saccadic gap effect and the manual gap effect. In particular, unconscious processes might modulate an oculomotor-specific component of the saccadic gap effect, presumably via subcortical mechanisms.
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NASA Astrophysics Data System (ADS)
van de Voort, Freeke; Davis, Timothy A.; Matsushita, Satoki; Rowlands, Kate; Shabala, Stanislav S.; Allison, James R.; Ting, Yuan-Sen; Sansom, Anne E.; van der Werf, Paul P.
2018-05-01
Gas-rich minor mergers contribute significantly to the gas reservoir of early-type galaxies (ETGs) at low redshift, yet the star formation efficiency (SFE; the star formation rate divided by the molecular gas mass) appears to be strongly suppressed following some of these events, in contrast to the more well-known merger-driven starbursts. We present observations with the Atacama Large Millimeter/submillimeter Array (ALMA) of six ETGs, which have each recently undergone a gas-rich minor merger, as evidenced by their disturbed stellar morphologies. These galaxies were selected because they exhibit extremely low SFEs. We use the resolving power of ALMA to study the morphology and kinematics of the molecular gas. The majority of our galaxies exhibit spatial and kinematical irregularities, such as detached gas clouds, warps, and other asymmetries. These asymmetries support the interpretation that the suppression of the SFE is caused by dynamical effects stabilizing the gas against gravitational collapse. Through kinematic modelling we derive high velocity dispersions and Toomre Q stability parameters for the gas, but caution that such measurements in edge-on galaxies suffer from degeneracies. We estimate merger ages to be about 100 Myr based on the observed disturbances in the gas distribution. Furthermore, we determine that these galaxies lie, on average, two orders of magnitude below the Kennicutt-Schmidt relation for star-forming galaxies as well as below the relation for relaxed ETGs. We discuss potential dynamical processes responsible for this strong suppression of star formation surface density at fixed molecular gas surface density.
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NASA Astrophysics Data System (ADS)
Takenaga, H.; Ide, S.; Sakamoto, Y.; Fujita, T.; JT-60 Team
2008-07-01
Effects of low central fuelling on density and ion temperature profiles have been investigated using negative ion based neutral beam injection and electron cyclotron heating (ECH) in reversed shear plasmas on JT-60U. Strong internal transport barrier (ITB) was maintained in density and ion temperature profiles, when central fuelling was decreased by switching positive ion based neutral beam injection to ECH after the strong ITB formation. Similar density and ion temperature ITBs were formed for the low and high central fuelling cases during the plasma current ramp-up phase. Strong correlation between the density gradient and the ion temperature gradient was observed, indicating that particle transport and ion thermal transport are strongly coupled or the density gradient assists the ion temperature ITB formation through suppression of drift wave instabilities such as ion temperature gradient mode. These results support that the density and ion temperature ITBs can be formed under reactor relevant conditions.
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Phenytoin attenuates the hyper-exciting neurotransmission in cultured embryonic cortical neurons.
Chou, Ming-Yi; Lee, Chun-Yao; Liou, Horng-Huei; Pan, Chien-Yuan
2014-08-01
Phenytoin is an effective anti-epileptic drug that inhibits Na(+) channel activities; however, how phenytoin modulates synaptic transmission to soothe epileptic symptoms is not clear. To characterize the effects of phenytoin regulation on neurotransmission, we studied the electrophysical properties of cultured embryonic cortical neurons. Phenytoin inhibited the inward Na(+) current in a dose-dependent manner with an IC50 of 16.8 μM, and at 100 μM, the inhibitory effect of phenytoin on the Na(+) current was proportional to the frequency applied. In cultured neurons, phenytoin significantly decreased the action potential firing rate and the peak potential. To study the effect of phenytoin in neurotransmission, we measured the Ca(2+) responses from stimulated target neurons and their neighboring neurons. Phenytoin significantly suppressed the Ca(2+) responses evoked by strong stimulations in the target and neighboring neurons, and exerted a decreased inhibitory effect under moderate stimulation. Picrotoxin, a GABAA receptor antagonist, enhanced the recorded spontaneous excitatory postsynaptic current activities. After picrotoxin-induced enhancement, phenytoin had a more pronounced effect on the suppression of the spontaneous hyper-exciting excitatory postsynaptic current (>100 pA), but it only mildly inhibited the general excitatory postsynaptic current. Our results demonstrate that phenytoin suppresses the efficacy of neurotransmission especially for the high-frequency stimulation by reducing the Na(+) channel activity and can potentially alleviate epileptiform activity. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Peripheral Prism Glasses: Effects of Dominance, Suppression and Background
Ross, Nicole C.; Bowers, Alex R.; Optom, M.C.; Peli, Eli
2012-01-01
Purpose Unilateral peripheral prisms for homonymous hemianopia (HH) place different images on corresponding peripheral retinal points, a rivalrous situation in which local suppression of the prism image could occur and thus limit device functionality. Detection with peripheral prisms has primarily been evaluated using conventional perimetry where binocular rivalry is unlikely to occur. We quantified detection over more visually complex backgrounds and examined the effects of ocular dominance. Methods Detection rates of 8 participants with HH or quadranopia and normal binocularity wearing unilateral peripheral prism glasses were determined for static perimetry targets briefly presented in the prism expansion area (in the blind hemifield) and the seeing hemifield, under monocular and binocular viewing, over uniform gray and more complex patterned backgrounds. Results Participants with normal binocularity had mixed sensory ocular dominance, demonstrated no difference in detection rates when prisms were fitted on the side of the HH or the opposite side (p>0.2), and had detection rates in the expansion area that were not different for monocular and binocular viewing over both backgrounds (p>0.4). However, two participants with abnormal binocularity and strong ocular dominance demonstrated reduced detection in the expansion area when prisms were fitted in front of the non-dominant eye. Conclusions We found little evidence of local suppression of the peripheral prism image for HH patients with normal binocularity. However, in cases of strong ocular dominance, consideration should be given to fitting prisms before the dominant eye. Although these results are promising, further testing in more realistic conditions including image motion is needed. PMID:22885783
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Warita, Katsuhiko; Oshima, Nana; Takeda-Okuda, Naoko; Tamura, Jun-Ichi; Hosaka, Yoshinao Z
2016-10-21
Chondroitin sulfate (CS), a type of glycosaminoglycan (GAG), is a factor involved in the suppression of myogenic differentiation. CS comprises two repeating sugars and has different subtypes depending on the position and number of bonded sulfate groups. However, the effect of each subtype on myogenic differentiation remains unclear. In this study, we spiked cultures of C₂C 12 myoblasts, cells which are capable of undergoing skeletal muscle differentiation, with one of five types of CS (CS-A, -B, -C, -D, or -E) and induced differentiation over a fixed time. After immunostaining of the formed myotubes with an anti-MHC antibody, we counted the number of nuclei in the myotubes and then calculated the fusion index (FI) as a measure of myotube differentiation. The FI values of all the CS-treated groups were lower than the FI value of the control group, especially the group treated with CS-E, which displayed notable suppression of myotube formation. To confirm that the sugar chain in CS-E is important in the suppression of differentiation, chondroitinase ABC (ChABC), which catabolizes CS, was added to the media. The addition of ChABC led to the degradation of CS-E, and neutralized the suppression of myotube formation by CS-E. Collectively, it can be concluded that the degree of suppression of differentiation depends on the subtype of CS and that CS-E strongly suppresses myogenic differentiation. We conclude that the CS sugar chain has inhibitory action against myoblast cell fusion.
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The Ni and Co substitutions in iron chalcogenide single crystals
NASA Astrophysics Data System (ADS)
Bezusyy, V. L.; Gawryluk, D. J.; Malinowski, A.; Berkowski, M.; Cieplak, Marta Z.
2015-03-01
We study the ab-plane resistivity and Hall effect in Fe1-yMyTe0.65Se0.35 single crystals with M =Co or Ni, and y up to 0.2. The crystals are grown by Bridgman's method. The low-temperature Hall coefficient RH changes sign to negative for crystals with y exceeding 0.135 (Co) and 0.06 (Ni), consistent with the electron doping induced by these impurities. However, the RH remains positive for all samples at high T, suggesting that remnant hole pockets survive the doping, but the holes become localized at low T in heavily doped crystals. Superconducting transition temperature (Tc) approaches zero for y = 0.14 (Co), and 0.03 (Ni), while the resistivity at the Tc onset is only weakly affected by Co doping, but it increases strongly for the Ni. These results suggest that in case of Co impurity the Tc suppression may be attributed to electron doping. On the other hand, the Ni substitution, in addition to electron doping, induces strong localization effects at small impurity contents. Using two-band conduction model we argue that the localization of electron carriers is responsible for strong superconductivity suppression by Ni impurity. Supported by EC through the FunDMS Advanced Grant of the ERC (FP7 Ideas), by the Polish NCS Grant 2011/01/B/ST3/00462, and by the French-Polish Program PICS 2012. Performed in the laboratories co-financed by NanoFun Project POIG.02.02.00-00-025/09.
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A Midwinter Minimum in North Atlantic Storm Track Intensity in Years of a Strong Jet
NASA Astrophysics Data System (ADS)
Afargan, H.; Kaspi, Y.
2017-12-01
This study investigates the occurrence of a midwinter suppression in synoptic eddy activity within the North Atlantic storm track. It is found that eddy kinetic energy over the Atlantic is reduced during winter relative to fall and spring, despite the stronger wintertime jet and enhanced baroclinicity. This behavior is similar to the well-known Pacific midwinter minimum, yet the reduction over the Atlantic is smaller and persists for a shorter period. To examine the conditions favorable for this phenomenon, we present an analysis of years with stronger jet intensity versus years of weaker jets over the Atlantic and Pacific basins. When the wintertime jet is stronger, the midwinter suppression of eddy activity is more pronounced, and the jet is more equatorward. Since the climatological Atlantic jet is weaker relative to the Pacific jet, the conditions for a midwinter suppression in the Atlantic are generally less favorable, yet a midwinter suppression often occurs in years of a strong jet.
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Raman mapping probing of tip-induced anomalous polarization behavior in V2O5 waveguiding nanoribbons
NASA Astrophysics Data System (ADS)
Yan, Bin; Du, Chaoling; Liao, Lei; You, Yumeng; Cheng, Hao; Shen, Zexiang; Yu, Ting
2010-02-01
Spatially resolved and polarized micro-Raman spectroscopy has been performed on individual V2O5 waveguiding nanoribbons. The experimental results establish that the Raman-antenna patterns are strongly correlated with the local positions of the sample, which gives rise to a pronounced intensity contrast in the polarized mapping for certain phonon modes. The suppressed phonon signals at the body of a ribbon can be enhanced at the end facets, resulting from the effective waveguiding propagation along the nanoribbon and strong local electric field intensity at the ends. The phenomena reported here, in addition to providing insight into the tip effects on optoelectronic nanodevices, will facilitate the rational design of Raman detection in nanostructures.
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Cross-Modal Attention Effects in the Vestibular Cortex during Attentive Tracking of Moving Objects.
Frank, Sebastian M; Sun, Liwei; Forster, Lisa; Tse, Peter U; Greenlee, Mark W
2016-12-14
The midposterior fundus of the Sylvian fissure in the human brain is central to the cortical processing of vestibular cues. At least two vestibular areas are located at this site: the parietoinsular vestibular cortex (PIVC) and the posterior insular cortex (PIC). It is now well established that activity in sensory systems is subject to cross-modal attention effects. Attending to a stimulus in one sensory modality enhances activity in the corresponding cortical sensory system, but simultaneously suppresses activity in other sensory systems. Here, we wanted to probe whether such cross-modal attention effects also target the vestibular system. To this end, we used a visual multiple-object tracking task. By parametrically varying the number of tracked targets, we could measure the effect of attentional load on the PIVC and the PIC while holding the perceptual load constant. Participants performed the tracking task during functional magnetic resonance imaging. Results show that, compared with passive viewing of object motion, activity during object tracking was suppressed in the PIVC and enhanced in the PIC. Greater attentional load, induced by increasing the number of tracked targets, was associated with a corresponding increase in the suppression of activity in the PIVC. Activity in the anterior part of the PIC decreased with increasing load, whereas load effects were absent in the posterior PIC. Results of a control experiment show that attention-induced suppression in the PIVC is stronger than any suppression evoked by the visual stimulus per se. Overall, our results suggest that attention has a cross-modal modulatory effect on the vestibular cortex during visual object tracking. In this study we investigate cross-modal attention effects in the human vestibular cortex. We applied the visual multiple-object tracking task because it is known to evoke attentional load effects on neural activity in visual motion-processing and attention-processing areas. Here we demonstrate a load-dependent effect of attention on the activation in the vestibular cortex, despite constant visual motion stimulation. We find that activity in the parietoinsular vestibular cortex is more strongly suppressed the greater the attentional load on the visual tracking task. These findings suggest cross-modal attentional modulation in the vestibular cortex. Copyright © 2016 the authors 0270-6474/16/3612720-09$15.00/0.
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Interface-facilitated energy transport in coupled Frenkel-Kontorova chains
NASA Astrophysics Data System (ADS)
Su, Rui-Xia; Yuan, Zong-Qiang; Wang, Jun; Zheng, Zhi-Gang
2016-04-01
The role of interface couplings on the energy transport of two coupled Frenkel-Kontorova (FK) chains is explored through numerical simulations. In general, it is expected that the interface couplings result in the suppression of heat conduction through the coupled system due to the additional interface phonon-phonon scattering. In the present paper, it is found that the thermal conductivity increases with increasing intensity of interface interactions for weak inter-chain couplings, whereas the heat conduction is suppressed by the interface interaction in the case of strong inter-chain couplings. Based on the phonon spectral energy density method, we demonstrate that the enhancement of energy transport results from the excited phonon modes (in addition to the intrinsic phonon modes), while the strong interface phonon-phonon scattering results in the suppressed energy transport.
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Effects of multiple organic ligands on size uniformity and optical properties of ZnSe quantum dots
DOE Office of Scientific and Technical Information (OSTI.GOV)
Archana, J., E-mail: archana.jayaram@yahoo.com; Navaneethan, M.; Hayakawa, Y.
2012-08-15
Highlights: ► Highly monodispersed ZnSe quantum dots have been synthesized by wet chemical route. ► Strong quantum confinement effect have been observed in ∼ 4 nm ZnSe quantum dots. ► Enhanced ultraviolet near band emission have been obtained using long chain polymer. -- Abstract: The effects of multi-ligands on the formation and optical transitions of ZnSe quantum dots have been investigated. The dots are synthesized using 3-mercapto-1,2-propanediol and polyvinylpyrrolidone ligands, and have been characterized by X-ray diffraction, transmission electron microscopy (TEM), UV–visible absorption spectroscopy, photoluminescence spectroscopy, and Fourier transform infrared spectroscopy. TEM reveals high monodispersion with an average size ofmore » 4 nm. Polymer-stabilized, organic ligand-passivated ZnSe quantum dots exhibit strong UV emission at 326 nm and strong quantum confinement in the UV–visible absorption spectrum. Uniform size and suppressed surface trap emission are observed when the polymer ligand is used. The possible growth mechanism is discussed.« less
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Model of gas adsorption on magnetic surfaces
NASA Astrophysics Data System (ADS)
Pick, S.˛te˛´n.; D´, Hugues
1997-12-01
The semi-empirical self-consistent tight-binding model of gas (C, N, O) chemisorption is suggested to study its influence on surface magnetism. For the strongly ferromagnetic Fe(001), we find that the adsorbates are not effective in magnetism reduction. For the hypothetical magnetic V(001) surface, the magnetization is very sensitive to the vanadium d-band occupation used in the calculation. Supposing that the magnetization is weak, it can be essentially suppressed by the gas contamination. The effect is explained by the Stoner criterion.
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Yoon, Taesook; Cheon, Myeong Sook; Lee, A Yeong; Lee, Do Yeon; Moon, Byeong Cheol; Chun, Jin Mi; Choo, Byung Kil; Kim, Ho Kyoung
2010-01-01
Glehnia littoralis (Umbelliferae) has been used traditionally in Korean, Japanese, and Chinese medicine for the treatment of immune-related diseases; however, its anti-inflammatory activity and underlying mechanism remain to be defined. We investigated the anti-inflammatory effect and inhibitory mechanism on inflammation by the methylene chloride fraction from Glehnia littoralis extract (MCF-GLE), which was more effective than Glehnia littoralis extract (GLE). MCF-GLE inhibited 12-O-Tetradecanoyl-phorbol-13-acetate (TPA)-induced inflammation in an inflammatory edema mouse model. Also, MCF-GLE strongly inhibited the releases of nitric oxide (NO), prostaglandin E(2) (PGE(2)), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) and significantly suppressed the mRNA and protein expression of inducible nitric oxide synthase and cyclooxygenase-2 in lipopolysaccharide-stimulated RAW 264.7 macrophage cells in a dose-dependent manner. Furthermore, MCF-GLE suppressed NF-kappaB activation and IkappaB-alpha degradation. MCF-GLE also attenuated the activation of ERK and JNK in a dose-dependent manner. These results indicate that MCF-GLE has an inhibitory effect on the in vivo and in vitro inflammatory reaction and is a possible therapeutic agent. Our results suggest that the anti-inflammatory properties of MCF-GLE may result from the inhibition of pro-inflammatory mediators, such as NO, PGE(2), TNF-alpha, and IL-1beta via suppression of NF-kappaB- and mitogen-activated protein kinases-dependent pathways.
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Aeroacoustic Characteristics of a Rectangular Multi-Element Supersonic Jet Mixer-Ejector Nozzle
NASA Technical Reports Server (NTRS)
Raman, Ganesh; Taghavi, Ray
1996-01-01
This paper provides a unique, detailed evaluation of the acoustics and aerodynamics of a rectangular multi-element supersonic jet mixer-ejector noise suppressor. The performance of such mixer-ejectors is important in aircraft engine application for noise suppression and thrust augmentation. In contrast to most prior experimental studies on ejectors that reported either aerodynamic or acoustic data, our work documents both types of data. We present information on the mixing, pumping, ejector wall pressure distribution, thrust augmentation and noise suppression characteristics of four simple, multi-element, jet mixer-ejector configurations. The four configurations included the effect of ejector area ratio (AR = ejector area/primary jet area) and the effect of non-parallel ejector walls. We also studied in detail the configuration that produced the best noise suppression characteristics. Our results show that ejector configurations that produced the maximum maximum pumping (entrained flow per secondary inlet area) also exhibited the lowest wall pressures in the inlet region, and the maximum thrust augmentation. When cases having the same total mass flow were compared, we found that noise suppression trends corresponded with those for pumping. Surprisingly, the mixing (quantified by the peak Mach number, and flow uniformity) at the ejector exit exhibited no relationship to the noise suppression at moderate primary jet fully expanded Mach numbers (Mj is less than 1.4). However, the noise suppression dependence on the mixing was apparent at higher Mj. The above observations are justified by noting that the mixing at the ejector exit is ot a strong factor in determining the radiated noise when noise produced internal to the ejector dominates the noise field outside the ejector.
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Stein, Timo; Hebart, Martin N.; Sterzer, Philipp
2011-01-01
Until recently, it has been thought that under interocular suppression high-level visual processing is strongly inhibited if not abolished. With the development of continuous flash suppression (CFS), a variant of binocular rivalry, this notion has now been challenged by a number of reports showing that even high-level aspects of visual stimuli, such as familiarity, affect the time stimuli need to overcome CFS and emerge into awareness. In this “breaking continuous flash suppression” (b-CFS) paradigm, differential unconscious processing during suppression is inferred when (a) speeded detection responses to initially invisible stimuli differ, and (b) no comparable differences are found in non-rivalrous control conditions supposed to measure non-specific threshold differences between stimuli. The aim of the present study was to critically evaluate these assumptions. In six experiments we compared the detection of upright and inverted faces. We found that not only under CFS, but also in control conditions upright faces were detected faster and more accurately than inverted faces, although the effect was larger during CFS. However, reaction time (RT) distributions indicated critical differences between the CFS and the control condition. When RT distributions were matched, similar effect sizes were obtained in both conditions. Moreover, subjective ratings revealed that CFS and control conditions are not perceptually comparable. These findings cast doubt on the usefulness of non-rivalrous control conditions to rule out non-specific threshold differences as a cause of shorter detection latencies during CFS. Thus, at least in its present form, the b-CFS paradigm cannot provide unequivocal evidence for unconscious processing under interocular suppression. Nevertheless, our findings also demonstrate that the b-CFS paradigm can be fruitfully applied as a highly sensitive device to probe differences between stimuli in their potency to gain access to awareness. PMID:22194718
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Different Neuroplasticity for Task Targets and Distractors
Spingath, Elsie Y.; Kang, Hyun Sug; Plummer, Thane; Blake, David T.
2011-01-01
Adult learning-induced sensory cortex plasticity results in enhanced action potential rates in neurons that have the most relevant information for the task, or those that respond strongly to one sensory stimulus but weakly to its comparison stimulus. Current theories suggest this plasticity is caused when target stimulus evoked activity is enhanced by reward signals from neuromodulatory nuclei. Prior work has found evidence suggestive of nonselective enhancement of neural responses, and suppression of responses to task distractors, but the differences in these effects between detection and discrimination have not been directly tested. Using cortical implants, we defined physiological responses in macaque somatosensory cortex during serial, matched, detection and discrimination tasks. Nonselective increases in neural responsiveness were observed during detection learning. Suppression of responses to task distractors was observed during discrimination learning, and this suppression was specific to cortical locations that sampled responses to the task distractor before learning. Changes in receptive field size were measured as the area of skin that had a significant response to a constant magnitude stimulus, and these areal changes paralleled changes in responsiveness. From before detection learning until after discrimination learning, the enduring changes were selective suppression of cortical locations responsive to task distractors, and nonselective enhancement of responsiveness at cortical locations selective for target and control skin sites. A comparison of observations in prior studies with the observed plasticity effects suggests that the non-selective response enhancement and selective suppression suffice to explain known plasticity phenomena in simple spatial tasks. This work suggests that differential responsiveness to task targets and distractors in primary sensory cortex for a simple spatial detection and discrimination task arise from nonselective increases in response over a broad cortical locus that includes the representation of the task target, and selective suppression of responses to the task distractor within this locus. PMID:21297962
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Immunosuppression induced by talc granulomatosis in the rat.
Radić, I; Vucak, I; Milosević, J; Marusić, A; Vukicević, S; Marusić, M
1988-01-01
Granulomatosis caused by four subcutaneous talc powder-suspension injections induced strong immunosuppression in rats. The disturbance included reduction of mononuclear white blood cell count in the peripheral blood, atrophy of the thymic cortex, spleen enlargement with predominance of red over the white pulp, increase in the number of lymph node germinal centres and a significant delay of the first-set and second-set allograft rejection. Neither phagocytic function of reticuloendothelial system nor erythrocyte count and humoral immune response were found to be altered. Indomethacin suppression of prostaglandin production did not normalize the allograft rejection dynamics. In contrast, splenectomy completely abolished the immunosuppressive effects of granulomatosis. In splenectomized, talc-treated animals WBC counts were not altered and the rejection of allografts was not delayed. Suppression of immune response to alloantigens was transferred to normal and splenectomized recipients by both serum and spleen cells of talc-injected animals. Also, in a cell mixture-transfer experiment, spleen cells from talc-granulomatosis-bearing donors suppressed the immune response induced by lymph node cells from immune donors in T cell-deficient rats. The inability of serum from splenectomized talc-injected rats to transfer the suppression suggested the crucial role of the spleen in the mechanisms leading to suppression in rats bearing talc-granulomatosis. PMID:3052948
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Mutations in eukaryotic release factors 1 and 3 act as general nonsense suppressors in Drosophila.
Chao, Anna T; Dierick, Herman A; Addy, Tracie M; Bejsovec, Amy
2003-01-01
In a screen for suppressors of the Drosophila wingless(PE4) nonsense allele, we isolated mutations in the two components that form eukaryotic release factor. eRF1 and eRF3 comprise the translation termination complex that recognizes stop codons and catalyzes the release of nascent polypeptide chains from ribosomes. Mutations disrupting the Drosophila eRF1 and eRF3 show a strong maternal-effect nonsense suppression due to readthrough of stop codons and are zygotically lethal during larval stages. We tested nonsense mutations in wg and in other embryonically acting genes and found that different stop codons can be suppressed but only a subset of nonsense alleles are subject to suppression. We suspect that the context of the stop codon is significant: nonsense alleles sensitive to suppression by eRF1 and eRF3 encode stop codons that are immediately followed by a cytidine. Such suppressible alleles appear to be intrinsically weak, with a low level of readthrough that is enhanced when translation termination is disrupted. Thus the eRF1 and eRF3 mutations provide a tool for identifying nonsense alleles that are leaky. Our findings have important implications for assigning null mutant phenotypes and for selecting appropriate alleles to use in suppressor screens. PMID:14573473
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Zechmann, Bernd; Hillmer, Morten; Doehlemann, Gunther
2012-01-01
The corn smut Ustilago maydis establishes a biotrophic interaction with its host plant maize. This interaction requires efficient suppression of plant immune responses, which is attributed to secreted effector proteins. Previously we identified Pep1 (Protein essential during penetration-1) as a secreted effector with an essential role for U. maydis virulence. pep1 deletion mutants induce strong defense responses leading to an early block in pathogenic development of the fungus. Using cytological and functional assays we show that Pep1 functions as an inhibitor of plant peroxidases. At sites of Δpep1 mutant penetrations, H2O2 strongly accumulated in the cell walls, coinciding with a transcriptional induction of the secreted maize peroxidase POX12. Pep1 protein effectively inhibited the peroxidase driven oxidative burst and thereby suppresses the early immune responses of maize. Moreover, Pep1 directly inhibits peroxidases in vitro in a concentration-dependent manner. Using fluorescence complementation assays, we observed a direct interaction of Pep1 and the maize peroxidase POX12 in vivo. Functional relevance of this interaction was demonstrated by partial complementation of the Δpep1 mutant defect by virus induced gene silencing of maize POX12. We conclude that Pep1 acts as a potent suppressor of early plant defenses by inhibition of peroxidase activity. Thus, it represents a novel strategy for establishing a biotrophic interaction. PMID:22589719
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Lee, Eunjung; Son, Joe Eun; Byun, Sanguine; Lee, Seung Joon; Kim, Yeong A; Liu, Kangdong; Kim, Jiyoung; Lim, Soon Sung; Park, Jung Han Yoon; Dong, Zigang; Lee, Ki Won; Lee, Hyong Joo
2013-10-01
Licorice extract which is used as a natural sweetener has been shown to possess inhibitory effects against prostate cancer, but the mechanisms responsible are poorly understood. Here, we report a compound, isoangustone A (IAA) in licorice that potently suppresses the growth of aggressive prostate cancer and sought to clarify its mechanism of action. We analyzed its inhibitory effects on the growth of PTEN-deleted human prostate cancer cells, in vitro and in vivo. Administration of IAA significantly attenuated the growth of prostate cancer cell cultures and xenograft tumors. These effects were found to be attributable to inhibition of the G1/S phase cell cycle transition and the accumulation of p27(kip1). The elevated p27(kip1) expression levels were concurrent with the decrease of its phosphorylation at threonine 187 through suppression of CDK2 kinase activity and the reduced phosphorylation of Akt at Serine 473 by diminishing the kinase activity of the mammalian target of rapamycin (mTOR). Further analysis using recombinant proteins and immunoprecipitated cell lysates determined that IAA exerts suppressive effects against CDK2 and mTOR kinase activity by direct binding with both proteins. These findings suggested that the licorice compound IAA is a potent molecular inhibitor of CDK2 and mTOR, with strong implications for the treatment of prostate cancer. Thus, licorice-derived extracts with high IAA content warrant further clinical investigation for nutritional sources for prostate cancer patients. Copyright © 2013 Elsevier Inc. All rights reserved.
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Whisker motor cortex reorganization after superior colliculus output suppression in adult rats.
Veronesi, Carlo; Maggiolini, Emma; Franchi, Gianfranco
2013-10-01
The effect of unilateral superior colliculus (SC) output suppression on the ipsilateral whisker motor cortex (WMC) was studied at different time points after tetrodotoxin and quinolinic acid injections, in adult rats. The WMC output was assessed by mapping the movement evoked by intracortical microstimulation (ICMS) and by recording the ICMS-evoked electromyographic (EMG) responses from contralateral whisker muscles. At 1 h after SC injections, the WMC showed: (i) a strong decrease in contralateral whisker sites, (ii) a strong increase in ipsilateral whisker sites and in ineffective sites, and (iii) a strong increase in threshold current values. At 6 h after injections, the WMC size had shrunk to 60% of the control value and forelimb representation had expanded into the lateral part of the normal WMC. Thereafter, the size of the WMC recovered, returning to nearly normal 12 h later (94% of control) and persisted unchanged over time (1-3 weeks). The ICMS-evoked EMG response area decreased at 1 h after SC lesion and had recovered its baseline value 12 h later. Conversely, the latency of ICMS-evoked EMG responses had increased by 1 h and continued to increase for as long as 3 weeks following the lesion. These findings provide physiological evidence that SC output suppression persistently withdrew the direct excitatory drive from whisker motoneurons and induced changes in the WMC. We suggest that the changes in the WMC are a form of reversible short-term reorganization that is induced by SC lesion. The persistent latency increase in the ICMS-evoked EMG response suggested that the recovery of basic WMC excitability did not take place with the recovery of normal explorative behaviour. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
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Feng, Hui; Beck, Jürgen; Nassal, Michael; Hu, Kang-hong
2011-01-01
Background The specific interaction between hepatitis B virus (HBV) polymerase (P protein) and the ε RNA stem-loop on pregenomic (pg) RNA is crucial for viral replication. It triggers both pgRNA packaging and reverse transcription and thus represents an attractive antiviral target. RNA decoys mimicking ε in P protein binding but not supporting replication might represent novel HBV inhibitors. However, because generation of recombinant enzymatically active HBV polymerase is notoriously difficult, such decoys have as yet not been identified. Methodology/Principal Findings Here we used a SELEX approach, based on a new in vitro reconstitution system exploiting a recombinant truncated HBV P protein (miniP), to identify potential ε decoys in two large ε RNA pools with randomized upper stem. Selection of strongly P protein binding RNAs correlated with an unexpected strong enrichment of A residues. Two aptamers, S6 and S9, displayed particularly high affinity and specificity for miniP in vitro, yet did not support viral replication when part of a complete HBV genome. Introducing S9 RNA into transiently HBV producing HepG2 cells strongly suppressed pgRNA packaging and DNA synthesis, indicating the S9 RNA can indeed act as an ε decoy that competitively inhibits P protein binding to the authentic ε signal on pgRNA. Conclusions/Significance This study demonstrates the first successful identification of human HBV ε aptamers by an in vitro SELEX approach. Effective suppression of HBV replication by the S9 aptamer provides proof-of-principle for the ability of ε decoy RNAs to interfere with viral P-ε complex formation and suggests that S9-like RNAs may further be developed into useful therapeutics against chronic hepatitis B. PMID:22125633
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NASA Astrophysics Data System (ADS)
Dombrovsky, Leonid A.; Dembele, Siaka; Wen, Jennifer X.
2018-06-01
The computational analysis of downward motion and evaporation of water droplets used to suppress a typical transient pool fire shows local regions of a high volume fraction of relatively small droplets. These droplets are comparable in size with the infrared wavelength in the range of intense flame radiation. The estimated scattering of the radiation by these droplets is considerable throughout the entire spectrum except for a narrow region in the vicinity of the main absorption peak of water where the anomalous refraction takes place. The calculations of infrared radiation field in the model pool fire indicate the strong effect of scattering which can be observed experimentally to validate the fire computational model.
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Connolly, John; Sebastià, Maria-Teresa; Kirwan, Laura; Finn, John Anthony; Llurba, Rosa; Suter, Matthias; Collins, Rosemary P; Porqueddu, Claudio; Helgadóttir, Áslaug; Baadshaug, Ole H; Bélanger, Gilles; Black, Alistair; Brophy, Caroline; Čop, Jure; Dalmannsdóttir, Sigridur; Delgado, Ignacio; Elgersma, Anjo; Fothergill, Michael; Frankow-Lindberg, Bodil E; Ghesquiere, An; Golinski, Piotr; Grieu, Philippe; Gustavsson, Anne-Maj; Höglind, Mats; Huguenin-Elie, Olivier; Jørgensen, Marit; Kadziuliene, Zydre; Lunnan, Tor; Nykanen-Kurki, Paivi; Ribas, Angela; Taube, Friedhelm; Thumm, Ulrich; De Vliegher, Alex; Lüscher, Andreas
2018-03-01
Grassland diversity can support sustainable intensification of grassland production through increased yields, reduced inputs and limited weed invasion. We report the effects of diversity on weed suppression from 3 years of a 31-site continental-scale field experiment.At each site, 15 grassland communities comprising four monocultures and 11 four-species mixtures based on a wide range of species' proportions were sown at two densities and managed by cutting. Forage species were selected according to two crossed functional traits, "method of nitrogen acquisition" and "pattern of temporal development".Across sites, years and sown densities, annual weed biomass in mixtures and monocultures was 0.5 and 2.0 t DM ha -1 (7% and 33% of total biomass respectively). Over 95% of mixtures had weed biomass lower than the average of monocultures, and in two-thirds of cases, lower than in the most suppressive monoculture (transgressive suppression). Suppression was significantly transgressive for 58% of site-years. Transgressive suppression by mixtures was maintained across years, independent of site productivity.Based on models, average weed biomass in mixture over the whole experiment was 52% less (95% confidence interval: 30%-75%) than in the most suppressive monoculture. Transgressive suppression of weed biomass was significant at each year across all mixtures and for each mixture.Weed biomass was consistently low across all mixtures and years and was in some cases significantly but not largely different from that in the equiproportional mixture. The average variability (standard deviation) of annual weed biomass within a site was much lower for mixtures (0.42) than for monocultures (1.77). Synthesis and applications . Weed invasion can be diminished through a combination of forage species selected for complementarity and persistence traits in systems designed to reduce reliance on fertiliser nitrogen. In this study, effects of diversity on weed suppression were consistently strong across mixtures varying widely in species' proportions and over time. The level of weed biomass did not vary greatly across mixtures varying widely in proportions of sown species. These diversity benefits in intensively managed grasslands are relevant for the sustainable intensification of agriculture and, importantly, are achievable through practical farm-scale actions.
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Active suppression of vortex-driven combustion instability using controlled liquid-fuel injection
NASA Astrophysics Data System (ADS)
Pang, Bin
Combustion instabilities remain one of the most challenging problems encountered in developing propulsion and power systems. Large amplitude pressure oscillations, driven by unsteady heat release, can produce numerous detrimental effects. Most previous active control studies utilized gaseous fuels to suppress combustion instabilities. However, using liquid fuel to suppress combustion instabilities is more realistic for propulsion applications. Active instability suppression in vortex-driven combustors using a direct liquid fuel injection strategy was theoretically established and experimentally demonstrated in this dissertation work. Droplet size measurements revealed that with pulsed fuel injection management, fuel droplet size could be modulated periodically. Consequently, desired heat release fluctuation could be created. If this oscillatory heat release is coupled with the natural pressure oscillation in an out of phase manner, combustion instabilities can be suppressed. To identify proper locations of supplying additional liquid fuel for the purpose of achieving control, the natural heat release pattern in a vortex-driven combustor was characterized in this study. It was found that at high Damkohler number oscillatory heat release pattern closely followed the evolving vortex front. However, when Damkohler number became close to unity, heat release fluctuation wave no longer coincided with the coherent structures. A heat release deficit area was found near the dump plane when combustor was operated in lean premixed conditions. Active combustion instability suppression experiments were performed in a dump combustor using a controlled liquid fuel injection strategy. High-speed Schlieren results illustrated that vortex shedding plays an important role in maintaining self-sustained combustion instabilities. Complete combustion instability control requires total suppression of these large-scale coherent structures. The sound pressure level at the excited dominant frequency was reduced by more than 20 dB with controlled liquid fuel injection method. Scaling issues were also investigated in this dump combustor to test the effectiveness of using pulsed liquid fuel injection strategies to suppress instabilities at higher power output conditions. With the liquid fuel injection control method, it was possible to suppress strong instabilities with initial amplitude of +/-5 psi down to the background noise level. The stable combustor operating range was also expanded from equivalence ratio of 0.75 to beyond 0.9.
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Naringin suppresses the development of glioblastoma by inhibiting FAK activity.
Li, Jinjiang; Dong, Yushu; Hao, Guangzhi; Wang, Bao; Wang, Julei; Liang, Yong; Liu, Yangyang; Zhen, Endi; Feng, Dayun; Liang, Guobiao
2017-01-01
As the most common and lethal primary malignant brain cancer, glioblastoma is hard to timely diagnose and sensitive therapeutic monitoring. It is essential to develop new and effective drugs for glioblastoma multiform. Naringin belongs to citrus flavonoids and was found to display strong anti-inflammatory, antioxidant and antitumor activities. In this report, we found that naringin can specifically inhibit the kinase activity of FAK and suppress the FAK p-Try397 and its downstream pathway in glioblastoma cells. Our study showed out that naringin can inhibit cell proliferation by inhibiting FAK/cyclin D1 pathway, promote cell apoptosis through influencing FAK/bads pathway, at the same time, it can also inhibit cell invasion and metastasis by inhibiting the FAK/mmps pathway. All these showed that naringin exerts the anti-tumor effects in U87 MG by inhibiting the kinase activity of FAK.
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NASA Astrophysics Data System (ADS)
Zhang, Lanhe; Elupula, Ravinder; Grayson, Scott; Torkelson, John
Cyclic or ring polymers represent an exciting class of topologically distinctive polymers. The influence of ``end-to-end'' tethering and the unusual conformational properties associated with cyclic topologies have led to polymer dynamics significantly different from the linear counterpart. Bulk cyclic polystyrene (c-PS) exhibits very weak Tg- and fragility-molecular weight (MW) dependences compared to linear PS. In stark contrast to the substantial Tg-confinement effects in linear PS, a nearly completely suppressed confinement effect is discovered in low MW c-PS. The cyclic topology strongly restricts polymer-substrate interactions. Therefore, the near elimination of the Tg-confinement effect in c-PS originates mainly from a very weak perturbation to Tg near the free surface. Upon nanoscale confinement, linear PS films have been shown to have significantly reduced fragility compared to bulk. Despite having similar bulk fragility as high MW linear PS, low MW c-PS films show major suppression in fragility reduction with decreasing thickness. Due to a lack of chain ends, properties associated with the ring structure are not prone to be perturbed by either MW reduction or confinement. This result indicates a strong correlation between the susceptibility of fragility perturbation and the susceptibility of Tg perturbation, caused by chain topology and/or by confinement. This work was supported by The Dow Chemical Company, a McCormick School of Engineering Fellowship, and the NSF.
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Lass, Christian; Vocanson, Marc; Wagner, Steffen; Schempp, Christoph M; Nicolas, Jean-Francois; Merfort, Irmgard; Martin, Stefan F
2008-10-01
Sesquiterpene lactones (SL), secondary plant metabolites from flowerheads of Arnica, exert anti-inflammatory effects mainly by preventing nuclear factor (NF)-kappaB activation because of alkylation of the p65 subunit. Despite its known immunosuppressive action, Arnica has been classified as a plant with strong potency to induce allergic contact dermatitis. Here we examined the dual role of SL as anti-inflammatory compounds and contact allergens in vitro and in vivo. We tested the anti-inflammatory and allergenic potential of SL in the mouse contact hypersensitivity model. We also used dendritic cells to study the activation of NF-kappaB and the secretion of interleukin (IL)-12 in the presence of different doses of SL in vitro. Arnica tinctures and SL potently suppressed NF-kappaB activation and IL-12 production in dendritic cells at high concentrations, but had immunostimulatory effects at low concentrations. Contact hypersensitivity could not be induced in the mouse model, even when Arnica tinctures or SL were applied undiluted to inflamed skin. In contrast, Arnica tinctures suppressed contact hypersensitivity to the strong contact sensitizer trinitrochlorobenzene and activation of dendritic cells. However, contact hypersensitivity to Arnica tincture could be induced in acutely CD4-depleted MHC II knockout mice. These results suggest that induction of contact hypersensitivity by Arnica is prevented by its anti-inflammatory effect and immunosuppression as a result of immune regulation in immunocompetent mice.
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Plasmonic distributed feedback lasers at telecommunications wavelengths.
Marell, Milan J H; Smalbrugge, Barry; Geluk, Erik Jan; van Veldhoven, Peter J; Barcones, Beatrix; Koopmans, Bert; Nötzel, Richard; Smit, Meint K; Hill, Martin T
2011-08-01
We investigate electrically pumped, distributed feedback (DFB) lasers, based on gap-plasmon mode metallic waveguides. The waveguides have nano-scale widths below the diffraction limit and incorporate vertical groove Bragg gratings. These metallic Bragg gratings provide a broad bandwidth stop band (~500 nm) with grating coupling coefficients of over 5000/cm. A strong suppression of spontaneous emission occurs in these Bragg grating cavities, over the stop band frequencies. This strong suppression manifests itself in our experimental results as a near absence of spontaneous emission and significantly reduced lasing thresholds when compared to similar length Fabry-Pérot waveguide cavities. Furthermore, the reduced threshold pumping requirements permits us to show strong line narrowing and super linear light current curves for these plasmon mode devices even at room temperature.
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Nishi, Takashi; Hara, Hiroshi; Tomita, Fusao
2003-02-01
Cholecystokinin (CCK) is an important physiologic mediator that regulates satiety and gastric emptying. We demonstrated previously that soybean peptone acts directly on rat small intestinal mucosal cells to stimulate CCK release. In the present study, we examined the effects of beta-conglycinin, a major component of soy protein, and its peptone on food intake and gastric emptying after an intraduodenal infusion of beta-conglycinin peptone in relation to CCK release and interaction with the mucosal cell membrane. Intraduodenal infusion of beta-conglycinin peptone inhibited food intake in a dose-dependent manner, but that of whole soy peptone or camostat did not. The suppression of food intake by beta-conglycinin peptone was abolished by an intravenous injection of devazepide, a selective peripheral CCK receptor antagonist. The beta-conglycinin peptone infusion strongly suppressed gastric emptying with marked increases in portal CCK levels. We also observed that the beta-conglycinin peptone dose dependently and more potently stimulated CCK release from isolated dispersed mucosal cells of the rat jejunum than did beta-conglycinin itself. This stimulation corresponded to the binding activity of the peptide or protein to solubilized components of the rat jejunum membrane as evaluated by surface plasmon biosensor. These results indicate that beta-conglycinin peptone suppresses food intake, and this effect may be due to beta-conglycinin peptone in the lumen stimulating endogenous CCK release with direct acceptance to the intestinal cells.
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Woo, Tae-Gyun; Yoon, Min-Ho; Hong, Shin-Deok; Choi, Jiyun; Ha, Nam-Chul; Sun, Hokeun; Park, Bum-Joon
2017-04-04
Hyper-activation of PAK1 (p21-activated kinase 1) is frequently observed in human cancer and speculated as a target of novel anti-tumor drug. In previous, we also showed that PAK1 is highly activated in the Smad4-deficient condition and suppresses PUMA (p53 upregulated modulator of apoptosis) through direct binding and phosphorylation. On the basis of this result, we have tried to find novel PAK1-PUMA binding inhibitors. Through ELISA-based blind chemical library screening, we isolated single compound, IPP-14 (IPP; Inhibitor of PAK1-PUMA), which selectively blocks the PAK1-PUMA binding and also suppresses cell proliferation via PUMA-dependent manner. Indeed, in PUMA-deficient cells, this chemical did not show anti-proliferating effect. This chemical possessed very strong PAK1 inhibition activity that it suppressed BAD (Bcl-2-asoociated death promoter) phosphorylation and meta-phase arrest via Aurora kinase inactivation in lower concentration than that of previous PAK1 kinase, FRAX486 and AG879. Moreover, our chemical obviously induced p21/WAF1/CIP1 (Cyclin-dependent kinase inhibitor 1A) expression by releasing from Bcl-2 (B-cell lymphoma-2) and by inhibition of AKT-mediated p21 suppression. Considering our result, IPP-14 and its derivatives would be possible candidates for PAK1 and p21 induction targeted anti-cancer drug.
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Bee products prevent VEGF-induced angiogenesis in human umbilical vein endothelial cells.
Izuta, Hiroshi; Shimazawa, Masamitsu; Tsuruma, Kazuhiro; Araki, Yoko; Mishima, Satoshi; Hara, Hideaki
2009-11-17
Vascular endothelial growth factor (VEGF) is a key regulator of pathogenic angiogenesis in diseases such as cancer and diabetic retinopathy. Bee products [royal jelly (RJ), bee pollen, and Chinese red propolis] from the honeybee, Apis mellifera, have been used as traditional health foods for centuries. The aim of this study was to investigate the anti-angiogenic effects of bee products using human umbilical vein endothelial cells (HUVECs). In an in vitro tube formation assay, HUVECs and fibroblast cells were incubated for 14 days with VEGF and various concentrations of bee products [RJ, ethanol extract of bee pollen, ethanol extract of Chinese red propolis and its constituent, caffeic acid phenethyl ester (CAPE)]. To clarify the mechanism of in vitro angiogenesis, HUVEC proliferation and migration were induced by VEGF with or without various concentrations of RJ, bee pollen, Chinese red propolis, and CAPE. RJ, bee pollen, Chinese red propolis, and CAPE significantly suppressed VEGF-induced in vitro tube formation in the descending order: CAPE > Chinese red propolis > bee pollen > RJ. RJ and Chinese red propolis suppressed both VEGF-induced HUVEC proliferation and migration. In contrast, bee pollen and CAPE suppressed only the proliferation. Among the bee products, Chinese red propolis and CAPE in particular showed strong suppressive effects against VEGF-induced angiogenesis. These findings indicate that Chinese red propolis and CAPE may have potential as preventive and therapeutic agents against angiogenesis-related human diseases.
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Solid tumor therapy by selectively targeting stromal endothelial cells
Liu, Shihui; Liu, Jie; Ma, Qian; Cao, Liu; Fattah, Rasem J.; Yu, Zuxi; Bugge, Thomas H.; Finkel, Toren; Leppla, Stephen H.
2016-01-01
Engineered tumor-targeted anthrax lethal toxin proteins have been shown to strongly suppress growth of solid tumors in mice. These toxins work through the native toxin receptors tumor endothelium marker-8 and capillary morphogenesis protein-2 (CMG2), which, in other contexts, have been described as markers of tumor endothelium. We found that neither receptor is required for tumor growth. We further demonstrate that tumor cells, which are resistant to the toxin when grown in vitro, become highly sensitive when implanted in mice. Using a range of tissue-specific loss-of-function and gain-of-function genetic models, we determined that this in vivo toxin sensitivity requires CMG2 expression on host-derived tumor endothelial cells. Notably, engineered toxins were shown to suppress the proliferation of isolated tumor endothelial cells. Finally, we demonstrate that administering an immunosuppressive regimen allows animals to receive multiple toxin dosages and thereby produces a strong and durable antitumor effect. The ability to give repeated doses of toxins, coupled with the specific targeting of tumor endothelial cells, suggests that our strategy should be efficacious for a wide range of solid tumors. PMID:27357689
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Turbulence Model Predictions of Strongly Curved Flow in a U-Duct
NASA Technical Reports Server (NTRS)
Rumsey, Christopher L.; Gatski, Thomas B.; Morrison, Joseph H.
2000-01-01
The ability of three types of turbulence models to accurately predict the effects of curvature on the flow in a U-duct is studied. An explicit algebraic stress model performs slightly better than one- or two-equation linear eddy viscosity models, although it is necessary to fully account for the variation of the production-to-dissipation-rate ratio in the algebraic stress model formulation. In their original formulations, none of these turbulence models fully captures the suppressed turbulence near the convex wall, whereas a full Reynolds stress model does. Some of the underlying assumptions used in the development of algebraic stress models are investigated and compared with the computed flowfield from the full Reynolds stress model. Through this analysis, the assumption of Reynolds stress anisotropy equilibrium used in the algebraic stress model formulation is found to be incorrect in regions of strong curvature. By the accounting for the local variation of the principal axes of the strain rate tensor, the explicit algebraic stress model correctly predicts the suppressed turbulence in the outer part of the boundary layer near the convex wall.
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Sharma, Rishi; Lodhi, Shafi; Sahota, Pradeep; Thakkar, Mahesh M
2015-10-01
Nicotine and alcohol co-abuse is highly prevalent, although the underlying causes are unclear. It has been suggested that nicotine enhances pleasurable effects of alcohol while reducing aversive effects. Recently, we reported that nicotine acts via the basal forebrain (BF) to activate nucleus accumbens and increase alcohol consumption. Does nicotine suppress alcohol-induced aversive effects via the BF? We hypothesized that nicotine may act via the BF to suppress sleep-promoting effects of alcohol. To test this hypothesis, adult male Sprague-Dawley rats were implanted with sleep-recording electrodes and bilateral guides targeted toward the BF. Nicotine (75 pmol/500 nL/side) or artificial cerebrospinal fluid (ACSF; 500 nL/side) was microinjected into the BF followed by intragastric alcohol (ACSF + EtOH and NiC + EtOH groups; 3 g/kg) or water (NiC + W and ACSF + W groups; 10 mL/kg) administration. On completion, rats were killed and processed to localize injection sites in the BF. The statistical analysis revealed a significant effect of treatment on sleep-wakefulness. While rats exposed to alcohol (ACSF + EtOH) displayed strong sleep promotion, nicotine pre-treatment in the BF (NiC + EtOH) attenuated alcohol-induced sleep and normalized sleep-wakefulness. These results suggest that nicotine acts via the BF to suppress the aversive, sleep-promoting effects of alcohol, further supporting the role of BF in alcohol-nicotine co-use. © 2015 International Society for Neurochemistry.
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A SONOS device with a separated charge trapping layer for improvement of charge injection
NASA Astrophysics Data System (ADS)
Ahn, Jae-Hyuk; Moon, Dong-Il; Ko, Seung-Won; Kim, Chang-Hoon; Kim, Jee-Yeon; Kim, Moon-Seok; Seol, Myeong-Lok; Moon, Joon-Bae; Choi, Ji-Min; Oh, Jae-Sub; Choi, Sung-Jin; Choi, Yang-Kyu
2017-03-01
A charge trapping layer that is separated from the primary gate dielectric is implemented on a FinFET SONOS structure. By virtue of the reduced effective oxide thickness of the primary gate dielectric, a strong gate-to-channel coupling is obtained and thus short-channel effects in the proposed device are effectively suppressed. Moreover, a high program/erase speed and a large shift in the threshold voltage are achieved due to the improved charge injection by the reduced effective oxide thickness. The proposed structure has potential for use in high speed flash memory.
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Kaku, S; Yamada, K; Hassan, N; Watanabe, T; Sugano, M
1997-03-01
To clarify the immunoglobulin production-regulating activity of vegetable extracts, mesenteric lymph node lymphocytes of Sprague-Dawley rats were cultured in the presence of 25 different vegetable extracts. The immunoglobulin content in the culture medium determined by ELISA indicated that the lily family (Liliaceae) vegetables most strongly enhanced the production of IgA and IgG, whereas they suppressed IgE production.
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H. Grant Pearce
2007-01-01
On March 24, 1998, a crew of eight rural firefighters were burned over while attempting to suppress a backburning sector of the Bucklands Crossing Fire in North Otago, New Zealand. The fire demonstrates how factors typical of the New Zealand fire environment â steep slopes, highly flammable shrub fuels, and a strong foehn wind effect â combined to produce extreme fire...
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Binding mechanism and electrochemical properties of M13 phage-sulfur composite.
Dong, Dexian; Zhang, Yongguang; Sutaria, Sanjana; Konarov, Aishuak; Chen, Pu
2013-01-01
Self-assembly of nanostructured materials has been proven a powerful technique in material design and synthesis. By phage display screening, M13 phage was found to strongly bind sulfur particles. Fourier transform infrared and X-ray photoelectron spectroscopy measurements indicated that the strong sulfur-binding ability of M13 phage derives from newly generated S-O and C-S bonds. Using this phage assembled sulfur composite in a lithium battery, the first discharge capacity reached 1117 mAh g(-1), which is more than twice that of the sulfur only cathode. Besides, the negative polysulfide shuttle effect in a lithium-sulfur battery was significantly suppressed.
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Binding Mechanism and Electrochemical Properties of M13 Phage-Sulfur Composite
Dong, Dexian; Zhang, Yongguang; Sutaria, Sanjana; Konarov, Aishuak; Chen, Pu
2013-01-01
Self-assembly of nanostructured materials has been proven a powerful technique in material design and synthesis. By phage display screening, M13 phage was found to strongly bind sulfur particles. Fourier transform infrared and X-ray photoelectron spectroscopy measurements indicated that the strong sulfur-binding ability of M13 phage derives from newly generated S-O and C-S bonds. Using this phage assembled sulfur composite in a lithium battery, the first discharge capacity reached 1117 mAh g-1, which is more than twice that of the sulfur only cathode. Besides, the negative polysulfide shuttle effect in a lithium-sulfur battery was significantly suppressed. PMID:24324560
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhao, Yukun; Solid-State Lighting Engineering Research Center, Xi'an Jiaotong University, Xi'an, Shaanxi 710049; Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool L69 3GJ
Size-tunable bimetallic bowtie nanoantennas have been utilized to suppress the efficiency roll-off characteristics in organic light-emitting diodes (OLEDs) using both the numerical and experimental approaches. The resonant range can be widened by the strong dual-atomic couplings in bimetallic bowtie nanoantennas. Compared with the green OLED with conventional bowtie nanoantennas at a high current density of 800 mA/cm{sup 2}, the measured efficiency roll-off ratio of the OLED with size-modulated bowtie nanoantennas is decreased from 53.2% to 41.8%, and the measured current efficiency is enhanced by 29.9%. When the size-modulated bowtie nanoantennas are utilized in blue phosphorescent OLEDs, the experimental roll-off ratio ismore » suppressed from 43.6% to 25.9% at 250 mA/cm{sup 2}, and the measured current efficiency is also enhanced significantly. It is proposed that the efficiency roll-off suppression is mainly related to the enhanced localized surface plasmon effect, which leads to a shorter radiative lifetime.« less
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NASA Astrophysics Data System (ADS)
Xing, Yong-Zhong; Lu, Fei-Ping; Wei, Xiao-Ping; Zheng, Yu-Ming
2014-08-01
The nucleon-nucleon cross sections in the dense nuclear matter are microscopically calculated by using Dirac—Brueckner—Hartree—Fock (DBHF) approximation with different covariant representations of the T-matrix, i.e., complete pseudo-vector (CPV), pseudoscalar (PS) and pseudo-vector (PV) choices. Special attention is paid to the discrepancies among the cross sections calculated with these different T-matrix project choices. The results show that the medium suppression of the cross section given by DBHF in the CPV choice is not only smaller than those obtained in both PS and PV choices, but also smaller than the predictions with a nonrelativistic Brueckner—Hartree—Fock (BHF) method including three body force (3BF). The further analysis reveals that the influence of the different choices on the cross section in the DBHF approximation is mainly determined by the state of smaller total angular momentum due to the medium effect being strongly suppressed in the higher angular momentum.
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Acid suppression and surgical therapy for Barrett's oesophagus.
de Jonge, Pieter J F; Spaander, Manon C; Bruno, Marco J; Kuipers, Ernst J
2015-02-01
Gastro-oesophageal reflux disease is a common medical problem in developed countries, and is a risk factor for the development of Barrett's oesophagus and oesophageal adenocarcinoma. Both proton pump inhibitor therapy and antireflux surgery are effective at controlling endoscopic signs and symptoms of gastro-oesophageal reflux in patients with Barrett's oesophagus, but often fail to eliminate pathological oesophageal acid exposure. The current available studies strongly suggest that acid suppressive therapy, both pharmacological as well as surgical acid suppression, can reduce the risk the development and progression in patients with Barrett's oesophagus, but are not capable of complete prevention. No significant differences have been found between pharmacological and surgical therapy. For clinical practice, patients should be prescribed a proton pump inhibitor once daily as maintenance therapy, with the dose guided by symptoms. Antireflux surgery can be a good alternative to proton pump inhibitor therapy, but should be primarily offered to patients with symptomatic reflux, and not to asymptomatic patients with the rationale to protect against cancer. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Dennis, Allison M.; Mangum, Benjamin D.; Piryatinski, Andrei; Park, Young-Shin; Hannah, Daniel C.; Casson, Joanna L.; Williams, Darrick J.; Schaller, Richard D.; Htoon, Han; Hollingsworth, Jennifer A.
2012-01-01
Non-blinking excitonic emission from near-infrared and type-II nanocrystal quantum dots (NQDs) is reported for the first time. To realize this unusual degree of stability at the single-dot level, novel InP/CdS core/shell NQDs were synthesized for a range of shell thicknesses (~1–11 monolayers of CdS). Ensemble spectroscopy measurements (photoluminescence peak position and radiative lifetimes) and electronic structure calculations established the transition from type-I to type-II band alignment in these heterostructured NQDs. More significantly, single-NQD studies revealed clear evidence for blinking suppression that was not strongly shell-thickness dependent, while photobleaching and biexciton lifetimes trended explicitly with extent of shelling. Specifically, very long biexciton lifetimes—up to >7 ns—were obtained for the thickest-shell structures, indicating dramatic suppression of non-radiative Auger recombination. This new system demonstrates that electronic structure and shell thickness can be employed together to effect control over key single-dot and ensemble NQD photophysical properties. PMID:23030497
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Coffee phenolic phytochemicals suppress colon cancer metastasis by targeting MEK and TOPK.
Kang, Nam Joo; Lee, Ki Won; Kim, Bo Hyun; Bode, Ann M; Lee, Hyo-Jeong; Heo, Yong-Seok; Boardman, Lisa; Limburg, Paul; Lee, Hyong Joo; Dong, Zigang
2011-06-01
Epidemiological studies suggest that coffee consumption reduces the risk of cancers, including colon cancer, but the molecular mechanisms and target(s) underlying the chemopreventive effects of coffee and its active ingredient(s) remain unknown. Based on serving size or daily units, coffee contains larger amounts of phenolic phytochemicals than tea or red wine. Coffee or chlorogenic acid inhibited CT-26 colon cancer cell-induced lung metastasis by blocking phosphorylation of ERKs. Coffee or caffeic acid (CaA) strongly suppressed mitogen-activated MEK1 and TOPK activities and bound directly to either MEK1 or TOPK in an ATP-noncompetitive manner. Coffee or CaA, but not caffeine, inhibited ERKs phosphorylation, AP-1 and NF-κB transactivation and subsequently inhibited TPA-, EGF- and H-Ras-induced neoplastic transformation of JB6 P+ cells. Coffee consumption was also associated with a significant attenuation of ERKs phosphorylation in colon cancer patients. These results suggest that coffee and CaA target MEK1 and TOPK to suppress colon cancer metastasis and neoplastic cell transformation.
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Study on GaN nanostructures: Growth and the suppression of the yellow emission
NASA Astrophysics Data System (ADS)
Wang, Ting; Chen, Fei; Ji, Xiaohong; Zhang, Qinyuan
2018-07-01
GaN nanostructures were synthesized via a simple chemical vapor deposition using Ga2O3 and NH3 as precursors. Structural and morphological properties were systematically characterized by field emission scanning electron microscopy, X-ray diffractometer, transmission electron microscopy, and Raman spectroscopy. The configuration of GaN nanostructures was found to be strongly dependent on the growth temperature and the NH3 flow rate. Photoluminescence analysis revealed that all the fabricated GaN NSs exhibited a strong ultra-violet emission (∼364 nm), and the yellow emission of GaN nanorods can be suppressed at appropriate III/V ratio. The suppression of the yellow emission was attributed to the low density of surface or the VGa defect. The work demonstrates that the GaN nanostructures have potential applications in the optoelectronic and nanoelectronic devices.
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Kondo physics in non-local metallic spin transport devices.
O'Brien, L; Erickson, M J; Spivak, D; Ambaye, H; Goyette, R J; Lauter, V; Crowell, P A; Leighton, C
2014-05-29
The non-local spin-valve is pivotal in spintronics, enabling separation of charge and spin currents, disruptive potential applications and the study of pressing problems in the physics of spin injection and relaxation. Primary among these problems is the perplexing non-monotonicity in the temperature-dependent spin accumulation in non-local ferromagnetic/non-magnetic metal structures, where the spin signal decreases at low temperatures. Here we show that this effect is strongly correlated with the ability of the ferromagnetic to form dilute local magnetic moments in the NM. This we achieve by studying a significantly expanded range of ferromagnetic/non-magnetic combinations. We argue that local moments, formed by ferromagnetic/non-magnetic interdiffusion, suppress the injected spin polarization and diffusion length via a manifestation of the Kondo effect, thus explaining all observations. We further show that this suppression can be completely quenched, even at interfaces that are highly susceptible to the effect, by insertion of a thin non-moment-supporting interlayer.
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Parra, Carolina; Montero-Silva, Francisco; Henríquez, Ricardo; Flores, Marcos; Garín, Carolina; Ramírez, Cristian; Moreno, Macarena; Correa, Jonathan; Seeger, Michael; Häberle, Patricio
2015-04-01
Understanding biological interaction with graphene and hexagonal-boron nitride (h-BN) membranes has become essential for the incorporation of these unique materials in contact with living organisms. Previous reports show contradictions regarding the bacterial interaction with graphene sheets on metals. Here, we present a comprehensive study of the interaction of bacteria with copper substrates coated with single-layer graphene and h-BN. Our results demonstrate that such graphitic coatings substantially suppress interaction between bacteria and underlying Cu substrates, acting as an effective barrier to prevent physical contact. Bacteria do not "feel" the strong antibacterial effect of Cu, and the substrate does not suffer biocorrosion due to bacteria contact. Effectiveness of these systems as barriers can be understood in terms of graphene and h-BN impermeability to transfer Cu(2+) ions, even when graphene and h-BN domain boundary defects are present. Our results seem to indicate that as-grown graphene and h-BN films could successfully protect metals, preventing their corrosion in biological and medical applications.
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Non-kinematic Flux-transport Dynamos Including the Effects of Diffusivity Quenching
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ichimura, Chiaki; Yokoyama, Takaaki
2017-04-10
Turbulent magnetic diffusivity is quenched when strong magnetic fields suppress turbulent motion in a phenomenon known as diffusivity quenching. Diffusivity quenching can provide a mechanism for amplifying magnetic field and influencing global velocity fields through Lorentz force feedback. To investigate this effect, we conducted mean field flux-transport dynamo simulations that included the effects of diffusivity quenching in a non-kinematic regime. We found that toroidal magnetic field strength is amplified by up to approximately 1.5 times in the convection zone as a result of diffusivity quenching. This amplification is much weaker than that in kinematic cases as a result of Lorentzmore » force feedback on the system’s differential rotation. While amplified toroidal fields lead to the suppression of equatorward meridional flow locally near the base of the convection zone, large-scale equatorward transport of magnetic flux via meridional flow, which is the essential process of the flux-transport dynamo, is sustainable in our calculations.« less
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Baker, Amelia H; Watt, James; Huang, Cassie K; Gerstenfeld, Louis C; Schlezinger, Jennifer J
2015-06-15
Organotins are members of the environmental obesogen class of contaminants because they activate peroxisome proliferator-activated receptor γ (PPARγ), the essential regulator of adipogenesis. Exposure to thiazolidinediones (PPARγ ligands used to treat type 2 diabetes) is associated with increased fractures. Diminished bone quality likely results from PPARγ's role in promoting adipogenesis while suppressing osteogenesis of bone marrow multipotent mesenchymal stromal cells (BM-MSC). We hypothesized that tributyltin (TBT) would be a potent modifier of BM-MSC differentiation and a negative regulator of bone formation. Organotins interact with both PPARγ and retinoid X receptors (RXR), suggesting that they activate multiple nuclear receptor pathways. To investigate the role of RXR in the actions of TBT, the effects of PPARγ (rosiglitazone) and RXR (bexarotene, LG100268) agonists were compared to the effects of TBT in BMS2 cells and primary mouse BM-MSC cultures. In BMS2 cells, TBT induced the expression of Fabp4, Abca1, and Tgm2 in an RXR-dependent manner. All agonists suppressed osteogenesis in primary mouse BM-MSC cultures, based on decreased alkaline phosphatase activity, mineralization, and expression of osteoblast-related genes. While rosiglitazone and TBT strongly activated adipogenesis, based on lipid accumulation and expression of adipocyte-related genes, the RXR agonists did not. Extending these analyses to other RXR heterodimers showed that TBT and the RXR agonists activated the liver X receptor pathway, whereas rosiglitazone did not. Application of either a PPARγ antagonist (T0070907) or an RXR antagonist (HX531) significantly reduced rosiglitazone-induced suppression of bone nodule formation. Only the RXR antagonist significantly reduced LG100268- and TBT-induced bone suppression. The RXR antagonist also inhibited LG100268- and TBT-induced expression of Abca1, an LXR target gene, in primary BM-MSC cultures. These results provide novel evidence that TBT activates multiple nuclear receptor pathways in BM-MSCs, activation of RXR is sufficient to suppress osteogenesis, and TBT suppresses osteogenesis largely through its direct interaction with RXR.
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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.
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Wang, Xingfu; Peng, Wenbo; Yu, Ruomeng; Zou, Haiyang; Dai, Yejing; Zi, Yunlong; Wu, Changsheng; Li, Shuti; Wang, Zhong Lin
2017-06-14
Achievement of p-n homojuncted GaN enables the birth of III-nitride light emitters. Owing to the wurtzite-structure of GaN, piezoelectric polarization charges present at the interface can effectively control/tune the optoelectric behaviors of local charge-carriers (i.e., the piezo-phototronic effect). Here, we demonstrate the significantly enhanced light-output efficiency and suppressed efficiency droop in GaN microwire (MW)-based p-n junction ultraviolet light-emitting diode (UV LED) by the piezo-phototronic effect. By applying a -0.12% static compressive strain perpendicular to the p-n junction interface, the relative external quantum efficiency of the LED is enhanced by over 600%. Furthermore, efficiency droop is markedly reduced from 46.6% to 7.5% and corresponding droop onset current density shifts from 10 to 26.7 A cm -2 . Enhanced electrons confinement and improved holes injection efficiency by the piezo-phototronic effect are revealed and theoretically confirmed as the physical mechanisms. This study offers an unconventional path to develop high efficiency, strong brightness and high power III-nitride light sources.
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Collective atomic scattering and motional effects in a dense coherent medium
Bromley, S. L.; Zhu, B.; Bishof, M.; Zhang, X.; Bothwell, T.; Schachenmayer, J.; Nicholson, T. L.; Kaiser, R.; Yelin, S. F.; Lukin, M. D.; Rey, A. M.; Ye, J.
2016-01-01
We investigate collective emission from coherently driven ultracold 88Sr atoms. We perform two sets of experiments using a strong and weak transition that are insensitive and sensitive, respectively, to atomic motion at 1 μK. We observe highly directional forward emission with a peak intensity that is enhanced, for the strong transition, by >103 compared with that in the transverse direction. This is accompanied by substantial broadening of spectral lines. For the weak transition, the forward enhancement is substantially reduced due to motion. Meanwhile, a density-dependent frequency shift of the weak transition (∼10% of the natural linewidth) is observed. In contrast, this shift is suppressed to <1% of the natural linewidth for the strong transition. Along the transverse direction, we observe strong polarization dependences of the fluorescence intensity and line broadening for both transitions. The measurements are reproduced with a theoretical model treating the atoms as coherent, interacting radiating dipoles. PMID:26984643
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Strong quantum squeezing of mechanical resonator via parametric amplification and coherent feedback
NASA Astrophysics Data System (ADS)
You, Xiang; Li, Zongyang; Li, Yongmin
2017-12-01
A scheme to achieve strong quantum squeezing of a mechanical resonator in a membrane-in-the-middle optomechanical system is developed. To this end, simultaneous linear and nonlinear coupling between the mechanical resonator and the cavity modes is applied. A two-tone driving light field, comprising unequal red-detuned and blue-detuned sidebands, helps in generating a coherent feedback force through the linear coupling with the membrane resonator. Another driving light field with its amplitude modulated at twice the mechanical frequency drives the mechanical parametric amplification through a second-order coupling with the resonator. The combined effect produces strong quantum squeezing of the mechanical state. The proposed scheme is quite robust to excess second-order coupling observed in coherent feedback operations and can suppress the fluctuations in the mechanical quadrature to far below the zero point and achieve strong squeezing (greater than 10 dB) for realistic parameters.
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Adaptive threshold shearlet transform for surface microseismic data denoising
NASA Astrophysics Data System (ADS)
Tang, Na; Zhao, Xian; Li, Yue; Zhu, Dan
2018-06-01
Random noise suppression plays an important role in microseismic data processing. The microseismic data is often corrupted by strong random noise, which would directly influence identification and location of microseismic events. Shearlet transform is a new multiscale transform, which can effectively process the low magnitude of microseismic data. In shearlet domain, due to different distributions of valid signals and random noise, shearlet coefficients can be shrunk by threshold. Therefore, threshold is vital in suppressing random noise. The conventional threshold denoising algorithms usually use the same threshold to process all coefficients, which causes noise suppression inefficiency or valid signals loss. In order to solve above problems, we propose the adaptive threshold shearlet transform (ATST) for surface microseismic data denoising. In the new algorithm, we calculate the fundamental threshold for each direction subband firstly. In each direction subband, the adjustment factor is obtained according to each subband coefficient and its neighboring coefficients, in order to adaptively regulate the fundamental threshold for different shearlet coefficients. Finally we apply the adaptive threshold to deal with different shearlet coefficients. The experimental denoising results of synthetic records and field data illustrate that the proposed method exhibits better performance in suppressing random noise and preserving valid signal than the conventional shearlet denoising method.
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Berry phase jumps and giant nonreciprocity in Dirac quantum dots
NASA Astrophysics Data System (ADS)
Rodriguez-Nieva, Joaquin F.; Levitov, Leonid S.
2016-12-01
We predict that a strong nonreciprocity in the resonance spectra of Dirac quantum dots can be induced by the Berry phase. The nonreciprocity arises in relatively weak magnetic fields and is manifest in anomalously large field-induced splittings of quantum dot resonances which are degenerate at B =0 due to time-reversal symmetry. This exotic behavior, which is governed by field-induced jumps in the Berry phase of confined electronic states, is unique to quantum dots in Dirac materials and is absent in conventional quantum dots. The effect is strong for gapless Dirac particles and can overwhelm the B -induced orbital and Zeeman splittings. A finite Dirac mass suppresses the effect. The nonreciprocity, predicted for generic two-dimensional Dirac materials, is accessible through Faraday and Kerr optical rotation measurements and scanning tunneling spectroscopy.
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Fenik, V; Davies, R O; Pack, A I; Kubin, L
1998-10-01
Microinjections of carbachol into the pontine tegmentum of decerebrate cats have been used to study the mechanisms underlying the suppression of postural and respiratory motoneuronal activity during the resulting rapid eye movement (REM) sleep-like atonia. During REM sleep, distinct respiratory muscles are differentially affected; e.g., the activity of the diaphragm shows little suppression, whereas the activity of some upper airway muscles is quite strong. To determine the pattern of the carbachol-induced changes in the activity of different groups of upper airway motoneurons, we simultaneously recorded the efferent activity of the recurrent laryngeal nerve (RL), pharyngeal branch of the vagus nerve (Phar), and genioglossal branch of the hypoglossal (XII) and phrenic (Phr) nerves in 12 decerebrate, paralyzed, vagotomized, and artificially ventilated cats. Pontine carbachol caused a stereotyped suppression of the spontaneous activity that was significantly larger in Phar expiratory (to 8.3% of control) and XII inspiratory motoneurons (to 15%) than in Phr inspiratory (to 87%), RL inspiratory (to 79%), or RL expiratory motoneurons (to 72%). The suppression in upper airway motor output was significantly greater than the depression caused by a level of hypocapnia that reduced Phr activity as much as carbachol. We conclude that pontine carbachol evokes a stereotyped pattern of suppression of upper airway motor activity. Because carbachol evokes a state having many neurophysiological characteristics similar to those of REM sleep, it is likely that pontine cholinoceptive neurons have similar effects on the activity of upper airway motoneurons during both states.
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NASA Technical Reports Server (NTRS)
Fu, Rong; Del Genio, Anthony D.; Rossow, William B.
1994-01-01
The authors analyze the influence of Sea Surface Temperature (SST) and surface wind divergence on atmospheric thermodynamic structure and the resulting effects on the occurrence of deep convection using National Meteorological Center radiosonde data and International Satellite Cloud Climatology Program data for July 1983-July 1985. The onset of deep convection requires not only the existence of positive convective available potential energy (CAPE), but also an unstable planetary boundary layer (PBL). A stable PBL is observed to suppress deep convection even when CAPE is positive. Variations of SST have a major effect on CAPE, but surface wind divergence can also affect deep convection by changing the lapse rate in the lower troposphere and humidity in the PBL. Specifically, when SST is greater than or equal to 28 C, CAPE is always positive, and surface wind divergence does not qualitatively change the buoyancy profile above the PBL. Strong surface wind divergence, however, stabilizes the PBL so as to suppress the initiation of deep convection. In warm SST regions, CAPE is greater than 0 regardless of assumptions about condensate loading, although the pseudoadiabatic limit is more consistent with the observed deep convection than the reversible moist-adiabatic limit under these circumstances. When SST is less than 27 C, CAPE is usually negative and inhibits convection, but strong surface wind convergence can destabilize the inversion layer and moisten the PBL enough to make the atmosphere neutrally stable in the mean. As a result, deep convection is generally enhanced either when SST is greater than or equal to 28 C in the absence of strong surface wind divergence or when strong surface wind convergence occurs even if SST is less than 27 C. The anomalous suppression of deep convection in the warm area of the equatorial west Pacific lying between the intertropical convergence zone (ITCZ) and south Pacific convergence zone (SPCZ) is probably caused by dryness in the PBL and an inversion in that area. The seasonal cycles of deep convection and surface wind divergence are in phase with the maximum solar radiation and lead SST for one to three months in the central Pacific. The change of PBL relative humidity plays a critical role in the changeover to convective instability in this case. The seasonal change of deep convection and associated clouds seems not to have important effects on the seasonal change of local SST in the central Pacific.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Torgomyan, Heghine; Trchounian, Armen, E-mail: Trchounian@ysu.am
2011-10-14
Highlights: {yields} Low intensity 70.6 and 73 GHz electromagnetic irradiation (EMI) strongly suppressed Escherichia coli growth at 73 GHz and pH 7.3. {yields} Reducer DL-dithiothreitol had bactericidal effect and disturbed the SH-groups number. {yields} EMI enhanced E. coli sensitivity toward dithiothreitol. {yields} EMI decreased the SH-groups number of membrane disturbed by ATP and N,N'-dicyclohexycarbodiimide. {yields} The changed membrane oxidation-reduction state could be the primary mechanisms in EMI effects. -- Abstract: Low-intensity electromagnetic irradiation (EMI) of 70.6 and 73 GHz frequencies (flux capacity - 0.06 mW cm{sup -2}) had bactericidal effects on Escherichia coli. This EMI (1 h) exposure suppressed themore » growth of E. coli K-12({lambda}). The pH value (6.0-8.0) did not significantly affect the growth. The lag-phase duration was prolonged, and the growth specific rate was inhibited, and these effects were more noticeable after 73 GHz irradiation. These effects were enhanced by the addition of DL-dithiothreitol (DTT), a strong reducer of disulfide bonds in surface membrane proteins, which in its turn also has bactericidal effect. Further, the number of accessible SH-groups in membrane vesicles was markedly decreased by EMI that was augmented by N,N'-dicyclohexycarbodiimide and DTT. These results indicate a change in the oxidation-reduction state of bacterial cell membrane proteins that could be the primary membranous mechanism in the bactericidal effects of low-intensity EMI of the 70.6 and 73 GHz frequencies.« less
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NASA Astrophysics Data System (ADS)
Trouet, V.; Taylor, A. H.; Skinner, C. N.; Stephens, S.
2016-12-01
In California, large wildfires cause significant socio-ecological impacts and they incur high federal funding costs for fire suppression. Future fire activity is projected to increase with climate change, but anthropogenic effects can modulate or even override climatic effects causing large uncertainty in fire projections. We developed a 415-year fire history record (1600-2015 CE) based on tree-ring fire-scar data from 29 sites throughout the Sierra Nevada, California. Changes in socio-ecological systems from the Native American to the current period drove large historical fire regime shifts in our record and socio-ecological conditions amplified and buffered fire response to climate. Fire activity was highest and fire-climate relationships were strongest after Native American depopulation - following mission establishment ca. 1775 CE - reduced the self-limiting effect of Native American burns on fire spread. With the Gold Rush and Euro-American immigration (ca. 1865 CE), area burned declined and the strong multidecadal relationship between temperature and fire decayed and then disappeared after implementation of fire suppression (ca. 1900 CE). The past anthropogenic modulation of fire-climate relationships underscores the need for nuanced representations of human-fire interactions to improve the skill of future fire-climate projections. In California, large wildfires cause significant socio-ecological impacts and they incur high federal funding costs for fire suppression. Future fire activity is projected to increase with climate change, but anthropogenic effects can modulate or even override climatic effects causing large uncertainty in fire projections. We developed a 415-year fire history record (1600-2015 CE) based on tree-ring fire-scar data from 29 sites throughout the Sierra Nevada, California. Changes in socio-ecological systems from the Native American to the current period drove large historical fire regime shifts in our record and socio-ecological conditions amplified and buffered fire response to climate. Fire activity was highest and fire-climate relationships were strongest after Native American depopulation - following mission establishment ca. 1775 CE - reduced the self-limiting effect of Native American burns on fire spread. With the Gold Rush and Euro-American immigration (ca. 1865 CE), area burned declined and the strong multidecadal relationship between temperature and fire decayed and then disappeared after implementation of fire suppression (ca. 1900 CE). The past anthropogenic modulation of fire-climate relationships underscores the need for nuanced representations of human-fire interactions to improve the skill of future fire-climate projections.
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Matsushita, Kazuyuki; Shimada, Hideaki; Ueda, Yasuji; Inoue, Makoto; Hasegawa, Mamoru; Tomonaga, Takeshi; Matsubara, Hisahiro; Nomura, Fumio
2014-01-01
AIM: To investigate a novel therapeutic strategy to target and suppress c-myc in human cancers using far up stream element (FUSE)-binding protein-interacting repressor (FIR). METHODS: Endogenous c-Myc suppression and apoptosis induction by a transient FIR-expressing vector was examined in vivo via a HA-tagged FIR (HA-FIR) expression vector. A fusion gene-deficient, non-transmissible, Sendai virus (SeV) vector encoding FIR cDNA, SeV/dF/FIR, was prepared. SeV/dF/FIR was examined for its gene transduction efficiency, viral dose dependency of antitumor effect and apoptosis induction in HeLa (cervical squamous cell carcinoma) cells and SW480 (colon adenocarcinoma) cells. Antitumor efficacy in a mouse xenograft model was also examined. The molecular mechanism of the anti-tumor effect and c-Myc suppression by SeV/dF/FIR was examined using Spliceostatin A (SSA), a SAP155 inhibitor, or SAP155 siRNA which induce c-Myc by increasing FIR∆exon2 in HeLa cells. RESULTS: FIR was found to repress c-myc transcription and in turn the overexpression of FIR drove apoptosis through c-myc suppression. Thus, FIR expressing vectors are potentially applicable for cancer therapy. FIR is alternatively spliced by SAP155 in cancer cells lacking the transcriptional repression domain within exon 2 (FIR∆exon2), counteracting FIR for c-Myc protein expression. Furthermore, FIR forms a complex with SAP155 and inhibits mutual well-established functions. Thus, both the valuable effects and side effects of exogenous FIR stimuli should be tested for future clinical application. SeV/dF/FIR, a cytoplasmic RNA virus, was successfully prepared and showed highly efficient gene transduction in in vivo experiments. Furthermore, in nude mouse tumor xenograft models, SeV/dF/FIR displayed high antitumor efficiency against human cancer cells. SeV/dF/FIR suppressed SSA-activated c-Myc. SAP155 siRNA, potentially produces FIR∆exon2, and led to c-Myc overexpression with phosphorylation at Ser62. HA-FIR suppressed endogenous c-Myc expression and induced apoptosis in HeLa and SW480 cells. A c-myc transcriptional suppressor FIR expressing SeV/dF/FIR showed high gene transduction efficiency with significant antitumor effects and apoptosis induction in HeLa and SW480 cells. CONCLUSION: SeV/dF/FIR showed strong tumor growth suppression with no significant side effects in an animal xenograft model, thus SeV/dF/FIR is potentially applicable for future clinical cancer treatment. PMID:24764668
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Ayoka, Abiodun O; Owolabi, Rotimi A; Bamitale, Samuel K; Akomolafe, Rufus O; Aladesanmi, Joseph A; Ukponmwan, Eghe O
2013-01-01
This study attempted to elucidate the neurotransmitter systems involved in the neurophysiological properties of ethanolic extract, fractions and pure isolates of Spondias mombin leaves in mice (n = 6) after intraperitoneal (i.p.) route of administration.The crude ethanolic extract of Spondian mombin leaves was fractionated using the partitioning method to obtain the ethylacetate, butanolic and aqueous fractions. Open column chromatographic fractionation of the ethylacetate fraction yielded seven sub-fractions, out of which the pure coumaroyl, quercetin and gallic acid derivatives were obtained after purification on Sephadex LH 20. The ethanolic extract, butanolic fraction, ethylacetate subfractions and pure isolates of the Spondian mombin leaves were tested on novelty-induced rearing and grooming behaviours in mice with standard pharmacological tools using the open field method. The extract and its fractions decreased novelty-induced rearing in a dose-dependent manner. While the Coumaroyl derivative had no effect on novelty-induced rearing, it significantly reversed the inhibitory effect of yohimbine, propranolol and haloperidol on novelty-induced rearing. Quercetin significantly potentiated the inhibitory effect of yohimbine on novelty-induced rearing. Naloxone significantly potentiated the quercetin-induced suppression of novelty-induced rearing. Gallic acid derivative significantly potentiated the inhibitory effect of yohimbine on novelty-induced rearing. Naloxone, atropine and haloperidol pretreatments significantly potentiated gallic acid derivative-induced suppression of novelty-induced rearing.The extract and its fractions had biphasic effect on novelty-induced grooming in mice. Coumaroyl derivative significantly increased novelty-induced grooming, while quercetin and gallic acid derivative decreased novelty-induced grooming significantly. The three pure isolates significantly reversed the effects of yohimbine and atropine on the novelty-induced grooming in mice. Propranolol-induced increase in novelty-induced grooming was significantly reversed by coumaroyl and gallic acid derivatives. Pre-treatment with naloxone significantly increased the gallic acid derivative-induced suppression of novelty-induced grooming. Pre-treatment with haloperidol reversed the effect of coumaroyl derivative and potentiated the inhibitory effect of quercetin derivative and gallic acid derivative significantly. This study suggested that adrenergic and dopaminergic neuro-transmissions are strongly involved in the neural mechanisms of the effect of the three pure isolates derivative, while opioid neuro-transmission is strongly linked with the neural mechanism of behavioural effect of coumaroyl derivative.
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Kawabata, Tetsu; Tokuda, Haruhiko; Fujita, Kazuhiko; Kainuma, Shingo; Sakai, Go; Matsushima-Nishiwaki, Rie; Kozawa, Osamu; Otsuka, Takanobu
2017-01-01
Resveratrol is a polyphenol enriched in the skins of grapes and berries, that shows various beneficial effects for human health. In the present study, we investigated the mechanism behind the epidermal growth factor (EGF)-induced migration of osteoblast-like MC3T3-E1 cells, and the effect of resveratrol on this cell migration. The cell migration was examined using Boyden chamber, and phosphorylation of each kinase was analyzed by Western blotting. The EGF-induced migration was suppressed by PD98059, an inhibitor of MEK1/2, as well as SB203580, an inhibitor of p38 MAP kinase, SP600125, an inhibitor of SAPK/JNK, and deguelin, an inhibitor of Akt. In contrast, rapamycin, an inhibitor of upstream kinase of p70 S6 kinase, and fasudil, an inhibitor of Rho-kinase, hardly affected the migration. Resveratrol significantly reduced the EGF-induced migration in a dose-dependent manner. SRT1720, an SIRT1 activator, suppressed the migration by EGF. In addition, resveratrol markedly attenuated the EGF-induced phosphorylation of SAPK/JNK and Akt without affecting the phosphorylation of p44/p42 MAP kinase or p38 MAP kinase. The phosphorylation of SAPK/JNK and Akt induced by EGF was down-regulated by SRT1720. Our results strongly suggest that resveratrol reduces the EGF-stimulated migration of osteoblasts via suppression of SAPK and Akt, and that the inhibitory effect of resveratrol is mediated in part via SIRT1. © 2017 The Author(s). Published by S. Karger AG, Basel.
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The Role of Diffusivity Quenching in Flux-transport Dynamo Models
NASA Astrophysics Data System (ADS)
Guerrero, Gustavo; Dikpati, Mausumi; de Gouveia Dal Pino, Elisabete M.
2009-08-01
In the nonlinear phase of a dynamo process, the back-reaction of the magnetic field upon the turbulent motion results in a decrease of the turbulence level and therefore in a suppression of both the magnetic field amplification (the α-quenching effect) and the turbulent magnetic diffusivity (the η-quenching effect). While the former has been widely explored, the effects of η-quenching in the magnetic field evolution have rarely been considered. In this work, we investigate the role of the suppression of diffusivity in a flux-transport solar dynamo model that also includes a nonlinear α-quenching term. Our results indicate that, although for α-quenching the dependence of the magnetic field amplification with the quenching factor is nearly linear, the magnetic field response to η-quenching is nonlinear and spatially nonuniform. We have found that the magnetic field can be locally amplified in this case, forming long-lived structures whose maximum amplitude can be up to ~2.5 times larger at the tachocline and up to ~2 times larger at the center of the convection zone than in models without quenching. However, this amplification leads to unobservable effects and to a worse distribution of the magnetic field in the butterfly diagram. Since the dynamo cycle period increases when the efficiency of the quenching increases, we have also explored whether the η-quenching can cause a diffusion-dominated model to drift into an advection-dominated regime. We have found that models undergoing a large suppression in η produce a strong segregation of magnetic fields that may lead to unsteady dynamo-oscillations. On the other hand, an initially diffusion-dominated model undergoing a small suppression in η remains in the diffusion-dominated regime.
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Kang, Chi Gu; Im, Eunji; Lee, Hyo-Jeong; Lee, Eun-Ok
2017-05-01
Lung cancer is the second most commonly diagnosed cancer and the leading cause of cancer deaths in both men and women in the United States. It has been recently demonstrated that osteopontin (OPN) effectively inhibits cofilin activity through the focal adhesion kinase (FAK)/AKT/Rho-associated kinase (ROCK) pathway to induce the invasion of human non-small cell lung cancer (NSCLC) cells. Plumbagin was isolated from the roots of the medicinal plant Plumbago zeylanica L. and has been reported to possess anticancer activities. However, the molecular mechanisms by which plumbagin inhibits the invasion of cancer cells is still unclear. In this study, the anti-invasive and anti-metastatic mechanisms of plumbagin were investigated in OPN-treated NSCLC A549 cells. OPN effectively induced the motility and invasion of NSCLC A549 cells and H1299 cells, which was strongly suppressed by plumbagin with no evidence of cytotoxicity. In addition, lamellipodia formation at the leading edge of cells by OPN was dramatically decreased in plumbagin-treated cells. Plumbagin caused an effective inhibition in OPN-induced the expression of ROCK1 as well as the phosphorylation of LIM kinase 1 and 2 (LIMK1/2), and cofilin. OPN-induced the phosphorylation of FAK and AKT was impaired without affecting their total forms by plumbagin treatment. OPN facilitated metastatic lung colonization, which was effectively suppressed in plumbagin-treated mice. Taken together, these results suggest that plumbagin reduces OPN-induced the invasion of NSCLC A549 cells, which resulted from inhibiting the ROCK pathway mediated by the FAK/AKT pathway and suppresses lung metastasis in vivo. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Effects of pH on frog gustatory responses to chloride salts of alkali-metal and alkali-earth-metal.
Kumai, T; Nomura, H
1980-01-01
The pH effects on frog gustatory responses to alkali-metal and alkali-earth-metal chloride salts were examined using single fungi-form papilla preparations. Responses to 0.1-0.5 M NaCl were clearly dependent upon the pH of the stimulating solutions. The responses increased as the pH decreased from 6.5 to 4.5 and were almost completely suppressed at pH's above 6.5. There was no significant difference in the pH dependency of the response among alkali-metal chlorides. HCl solutions elicited only a poor response under conditions in which the water response was suppressed by the simultaneous presence of a low NaCl concentration. Responses to alkali-earth-metal chlorides varied in their pH dependency. Response to CaCl2 was slightly affected by pH changes from 4.5 to 9.0, response to SrCl2 was considerably suppressed in the alkaline region, and responses to BaCl2 and MgCl2 were strongly suppressed at pH's above 6.5. BeCl2 solutions showed less marked stimulating effects over the pH range tested. The differences in pH dependency described above suggest the existence of two kinds of receptor sites, one being pH-insensitive sites responsible for the calcium response and the other pH-sensitive sites responsible for the sodium response. A cross-adaptation test appeared to support this possibility. Assuming that the pH effect mentioned is related to changes in the state of ionization of the receptor molecule, the pKa of the ionizable group responsible for the sodium response was determined to be approximately 5.5.
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d -wave superconductivity in the presence of nearest-neighbor Coulomb repulsion
DOE Office of Scientific and Technical Information (OSTI.GOV)
Jiang, M.; Hahner, U. R.; Schulthess, T. C.
Dynamic cluster quantum Monte Carlo calculations for a doped two-dimensional extended Hubbard model are used to study the stability and dynamics of d-wave pairing when a nearest-neighbor Coulomb repulsion V is present in addition to the on-site Coulomb repulsion U. We find that d-wave pairing and the superconducting transition temperature Tc are only weakly suppressed as long as V does not exceed U/2. This stability is traced to the strongly retarded nature of pairing that allows the d-wave pairs to minimize the repulsive effect of V. When V approaches U/2, large momentum charge fluctuations are found to become important andmore » to give rise to a more rapid suppression of d-wave pairing and T c than for smaller V.« less
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Research on the range side lobe suppression method for modulated stepped frequency radar signals
NASA Astrophysics Data System (ADS)
Liu, Yinkai; Shan, Tao; Feng, Yuan
2018-05-01
The magnitude of time-domain range sidelobe of modulated stepped frequency radar affects the imaging quality of inverse synthetic aperture radar (ISAR). In this paper, the cause of high sidelobe in modulated stepped frequency radar imaging is analyzed first in real environment. Then, the chaos particle swarm optimization (CPSO) is used to select the amplitude and phase compensation factors according to the minimum sidelobe criterion. Finally, the compensated one-dimensional range images are obtained. Experimental results show that the amplitude-phase compensation method based on CPSO algorithm can effectively reduce the sidelobe peak value of one-dimensional range images, which outperforms the common sidelobe suppression methods and avoids the coverage of weak scattering points by strong scattering points due to the high sidelobes.
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Djordjevic, Ivan B; Vasic, Bane
2006-05-29
A maximum a posteriori probability (MAP) symbol decoding supplemented with iterative decoding is proposed as an effective mean for suppression of intrachannel nonlinearities. The MAP detector, based on Bahl-Cocke-Jelinek-Raviv algorithm, operates on the channel trellis, a dynamical model of intersymbol interference, and provides soft-decision outputs processed further in an iterative decoder. A dramatic performance improvement is demonstrated. The main reason is that the conventional maximum-likelihood sequence detector based on Viterbi algorithm provides hard-decision outputs only, hence preventing the soft iterative decoding. The proposed scheme operates very well in the presence of strong intrachannel intersymbol interference, when other advanced forward error correction schemes fail, and it is also suitable for 40 Gb/s upgrade over existing 10 Gb/s infrastructure.
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Cloaks for suppression or enhancement of scattering of diffuse photon density waves
NASA Astrophysics Data System (ADS)
Renthlei, Lalruatfela; Ramakrishna, S. Anantha; Wanare, Harshawardhan
2018-07-01
Enhancement of wave-like characteristics of heavily damped diffuse photon density waves in a random medium by amplification can induce strongly localised resonances. These resonances can be used to either suppress or enhance scattering from an inhomogeneity in the random medium by cloaking the inhomogeneous region by a shell of random medium with the correct levels of absorption or amplification. A spherical core-shell structure consisting of a shell of a random amplifying medium is shown to enhance or suppress specific resonant modes. A shell with an absorbing random medium is also shown to suppress scattering which can also be used for cloaking the core region.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhang, Yu, E-mail: zhy@yangtze.hku.hk; Chen, GuanHua, E-mail: ghc@everest.hku.hk; Yam, ChiYung
2015-04-28
A time-dependent inelastic electron transport theory for strong electron-phonon interaction is established via the equations of motion method combined with the small polaron transformation. In this work, the dissipation via electron-phonon coupling is taken into account in the strong coupling regime, which validates the small polaron transformation. The corresponding equations of motion are developed, which are used to study the quantum interference effect and phonon-induced decoherence dynamics in molecular junctions. Numerical studies show clearly quantum interference effect of the transport electrons through two quasi-degenerate states with different couplings to the leads. We also found that the quantum interference can bemore » suppressed by the electron-phonon interaction where the phase coherence is destroyed by phonon scattering. This indicates the importance of electron-phonon interaction in systems with prominent quantum interference effect.« less
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Suppression of slip and rupture velocity increased by thermal pressurization: Effect of dilatancy
NASA Astrophysics Data System (ADS)
Urata, Yumi; Kuge, Keiko; Kase, Yuko
2013-11-01
investigated the effect of dilatancy on dynamic rupture propagation on a fault where thermal pressurization (TP) is in effect, taking into account permeability varying with porosity; the study is based on three-dimensional (3-D) numerical simulations of spontaneous ruptures obeying a slip-weakening friction law and Coulomb failure criterion. The effects of dilatancy on dynamic ruptures interacting with TP have been often investigated in one- or two-dimensional numerical simulations. The sole 3-D numerical simulation gave attention only to the behavior at a single point on a fault. Moreover, with the sole exception based on a single-degree-freedom spring-slider model, the previous simulations including dilatancy and TP have not considered changes in hydraulic diffusivity. However, the hydraulic diffusivity, which strongly affects TP, can vary as a power of porosity. In this study, we apply a power law relationship between permeability and porosity. We consider both reversible and irreversible changes in porosity, assuming that the irreversible change is proportional to the slip rate and dilatancy coefficient ɛ. Our numerical simulations suggest that the effects of dilatancy can suppress slip and rupture velocity increased by TP. The results reveal that the amount of slip on the fault decreases with increasing ɛ or exponent of the power law, and the rupture velocity is predominantly suppressed by ɛ. This was observed regardless of whether the applied stresses were high or low. The deficit of the final slip in relation to ɛ can be smaller as the fault size is larger.
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Static Magnetic Fields in Semiconductor Floating-Zone Growth
NASA Technical Reports Server (NTRS)
Croll, Arne; Benz, K. W.
1999-01-01
Heat and mass transfer in semiconductor float-zone processing are strongly influenced by convective flows in the zone, originating from sources such as buoyancy convection, thermocapillary (Marangoni) convection, differential rotation, or radio frequency heating. Because semiconductor melts are conducting, flows can be damped by the use of static magnetic fields to influence the interface shape and the segregation of dopants and impurities. An important objective is often the suppression of time-dependent flows and the ensuing dopant striations. In RF-heated Si-FZ - crystals, fields up to O.STesla show some flattening of the interface curvature and a reduction of striation amplitudes. In radiation-heated (small-scale) SI-FZ crystals, fields of 0.2 - 0.5 Tesla already suppress the majority of the dopant striations. The uniformity of the radial segregation is often compromised by using a magnetic field, due to the directional nature of the damping. Transverse fields lead to an asymmetric interface shape and thus require crystal rotation (resulting in rotational dopant striations) to achieve a radially symmetric interface, whereas axial fields introduce a coring effect. A complete suppression of dopant striations and a reduction of the coring to insignificant values, combined with a shift of the axial segregation profile towards a more diffusion-limited case, are possible with axial static fields in excess of 1 Tesla. Strong static magnetic fields, however, can also lead to the appearance of thermoelectromagnetic convection, caused by the interaction of thermoelectric currents with the magnetic field.
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Inhibitory effects of Physalis angulata on tumor metastasis and angiogenesis.
Hseu, You-Cheng; Wu, Chi-Rei; Chang, Hsueh-Wei; Kumar, K J Senthil; Lin, Ming-Kuem; Chen, Chih-Sheng; Cho, Hsin-Ju; Huang, Chun-Yin; Huang, Chih-Yang; Lee, Hong-Zin; Hsieh, Wen-Tsong; Chung, Jing-Gung; Wang, Hui-Min; Yang, Hsin-Ling
2011-06-01
ETHNOPHARMACOLOGICAL RELAVENCE: Physalis angulata is well-known in traditional Chinese medicine as a ingredient for various herbal formulation; also, it has been shown to exhibit anti-cancer and anti-inflammatory effects. In this study, the ability of P. angulata to inhibit tumor metastasis and angiogenesis was investigated. Anti-proliferative activity of ethyl acetate extracts of P. angulata (PA extracts), was determined against human oral squamous carcinoma (HSC-3) and human umbilical vein endothelial cells (HUVECs) by trypan blue exclusion method. Wound-healing migration, trans-well invasion, Western blotting and chick chorioallantoic membrane assay were carried out to determine the anti-metastatic and anti-angiogenic effects of PA extracts in vitro and in vivo. We demonstrated that at sub-cytotoxic concentrations of PA extracts (5-15 μg/mL) markedly inhibited the migration and invasion of highly metastatic HSC-3 cells as shown by wound-healing repair assay and trans-well assay. Gelatin zymography assay showed that PA extracts suppressed the activity of matrix metalloproteinase (MMP)-9 and -2, and urokinase plasminogen activator (u-PA) in HSC-3 cells. In addition, Western blot analysis confirmed that PA extracts significantly decreased MMP-2 and u-PA protein expression in HSC-3 cells. Notably, PA extracts significantly augmented the expression of their endogenous inhibitors, including tissue inhibitors of MMP (TIMP-1 and -2), and plasminogen activator inhibitors (PAI-1 and -2). Further investigations revealed that non-cytotoxic concentration of PA extracts (5-15 μg/mL) inhibited vascular endothelial growth factor (VEGF)-induced proliferation, and migration/invasion of HUVECs in vitro. PA extracts also suppressed the activity of MMP-9, but not MMP-2, in HUVECs. Further, we observed, PA extracts strongly suppressed neovessel formation in the chorioallantoic membrane of chick embryos in vivo. These results strongly support an anti-metastatic and anti-angiogenic activity of P. angulata that may contribute to the development of better chemopreventive agent for cancer and inflammation. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
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Seasonal changes in the human alteration of fire regimes beyond the climate forcing
NASA Astrophysics Data System (ADS)
Fréjaville, Thibaut; Curt, Thomas
2017-03-01
Human activities have altered fire regimes for millennia by suppressing or enhancing natural fire activity. However, whether these anthropogenic pressures on fire activity have exceeded and will surpass climate forcing still remains uncertain. We tested if, how and the extent to which seasonal fire activity in southern France has recently (1976-2009) deviated from climate-expected trends. The latter were simulated using an ensemble of detrended fire-climate models. We found both seasonal and regional contrasts in climatic effects through a mixture of drought-driven and fuel-limited fire regimes. Dry contemporary conditions chiefly drove fire frequency and burned area, although higher fire activity was related to wetter conditions in the last three years. Surprisingly, the relative importance of preceding wet conditions was higher in winter than in summer, illustrating the strong potential dependency of regional fire-climate relationships on the human use and control of fires. In the Mediterranean mountains, warm winters and springs favour extensive fires in the following dry summer. These results highlight that increasing dryness with climate change could have antagonistic effects on fire regime by leading to larger fires in summer (moisture-limited), but lower fire activity in winter (fuel-limited fire regime). Furthermore, fire trends have significantly diverged from climatic expectations, with a strong negative alteration in fire activity in the Mediterranean lowlands and the summer burned area in the mountains. In contrast, alteration of winter fire frequency in the Mediterranean and Temperate mountains has shifted from positive to negative (or null) trends during the mid-1990s, a period when fire suppression policy underwent major revisions. Our findings demonstrate that changes in land-use and fire suppression policy have probably exceeded the strength of climate change effects on changing fire regime in southern Europe, making regional predictions of future fires highly challenging.
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Tan, Huanbo; Xu, Mingkai; Li, Xinyu; Zhang, Huiwen; Zhang, Chenggang
2013-09-15
Chlorimuron-ethyl (CE) has been widely used in modern agriculture, but little is known regarding the influence of CE on ammonia-oxidizing bacteria (AOB) and archaea (AOA) populations in soils. In this study, microcosm incubation of aquic brown soil was conducted for 60 d. Associated changes in the population sizes of AOB and AOA in response to CE application with or without urea fertilization were examined via quantitative real-time PCR (qPCR) assays of the ammonia monooxygenase gene (amoA). The half-life of CE ranged from 11.80 d to 14.54 d in the tested soil. Compared to the untreated control, the application of CE alone had no strong effects on soil pH, and urea fertilization temporarily increased soil pH in the first 7 days. The abundance of the AOA amoA gene was greater than the abundance of the AOB amoA gene in all treatments, but both were significantly suppressed by CE application in a dose-dependent manner. Urea fertilization generally increased AOB and AOA amoA gene abundances, except that the AOA amoA gene level was slightly reduced at the early stage of the incubation period. AOB and AOA preferred different N levels for growth, with AOB only growing significantly at high NH4(+) levels and AOA growing substantially at low NH₄(+) levels. The stimulation effects of urea fertilization on AOA and AOB amoA gene abundances were strongly suppressed by the CE application. This study indicated that the CE application substantially suppressed soil nitrification via inhibiting the AOB and AOA population regardless of urea fertilization, which resulted in significant changes in the soil NH₄(+)-N and NO₃(-)-N levels. Furthermore, AOB and AOA inhabiting separate ecological niches with different NH₄(+) levels played various roles in N cycling. Copyright © 2013 Elsevier B.V. All rights reserved.
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Spin-orbit coupling and electric-dipole spin resonance in a nanowire double quantum dot.
Liu, Zhi-Hai; Li, Rui; Hu, Xuedong; You, J Q
2018-02-02
We study the electric-dipole transitions for a single electron in a double quantum dot located in a semiconductor nanowire. Enabled by spin-orbit coupling (SOC), electric-dipole spin resonance (EDSR) for such an electron can be generated via two mechanisms: the SOC-induced intradot pseudospin states mixing and the interdot spin-flipped tunneling. The EDSR frequency and strength are determined by these mechanisms together. For both mechanisms the electric-dipole transition rates are strongly dependent on the external magnetic field. Their competition can be revealed by increasing the magnetic field and/or the interdot distance for the double dot. To clarify whether the strong SOC significantly impact the electron state coherence, we also calculate relaxations from excited levels via phonon emission. We show that spin-flip relaxations can be effectively suppressed by the phonon bottleneck effect even at relatively low magnetic fields because of the very large g-factor of strong SOC materials such as InSb.
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Correia, Patrícia A; Lottem, Eran; Banerjee, Dhruba; Machado, Ana S; Carey, Megan R; Mainen, Zachary F
2017-01-01
Serotonin (5-HT) is associated with mood and motivation but the function of endogenous 5-HT remains controversial. Here, we studied the impact of phasic optogenetic activation of 5-HT neurons in mice over time scales from seconds to weeks. We found that activating dorsal raphe nucleus (DRN) 5-HT neurons induced a strong suppression of spontaneous locomotor behavior in the open field with rapid kinetics (onset ≤1 s). Inhibition of locomotion was independent of measures of anxiety or motor impairment and could be overcome by strong motivational drive. Repetitive place-contingent pairing of activation caused neither place preference nor aversion. However, repeated 15 min daily stimulation caused a persistent increase in spontaneous locomotion to emerge over three weeks. These results show that 5-HT transients have strong and opposing short and long-term effects on motor behavior that appear to arise from effects on the underlying factors that motivate actions. DOI: http://dx.doi.org/10.7554/eLife.20975.001 PMID:28193320
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Nickerson, Angela; Garber, Benjamin; Ahmed, Ola; Asnaani, Anu; Cheung, Jessica; Hofmann, Stefan G; Huynh, Ly; Liddell, Belinda; Litz, Brett T; Pajak, Rosanna; Bryant, Richard A
2016-08-30
While clinical reports suggest that torture survivors may try to suppress their emotions during torture, little is known about the use of emotional suppression following torture. In this study, 82 refugees and asylum-seekers (including 33 torture survivors) completed self-report measures of trait suppression, PTSD symptoms and baseline negative affect before being exposed to images depicting scenes of interpersonal trauma. The use of suppression while viewing the images was indexed and negative affect was measured both immediately after viewing the images and following a five minute rest period. Findings indicated that torture survivors did not show higher rates of trait suppression or state emotional suppression during the experimental session compared to non-torture survivors. However, torture survivors who endorsed state suppression higher levels of distress, and this relationship was especially strong for those with more severe PTSD symptoms. In contrast, there was a negative relationship between state suppression and distress for non-torture survivors with high levels of PTSD symptoms. These findings suggest that, while torture exposure does not lead to greater use of suppression, it does influence the impact of suppression on emotional responses to stimuli. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
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Crystal S. Stonesifer; David E. Calkin; Michael S. Hand
2017-01-01
Wildland firefighting in the United States is a complex and costly enterprise. While there are strong seasonal signatures for fire occurrence in specific regions of the United States, spatiotemporal occurrence of wildfire activity can have high inter-annual variability. Suppression resources come from a variety of jurisdictions and provide a wide range of skills,...
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Okai, Y; Higashi-Okai, K
Many experimental studies for anticarcinogenic activity of green tea (Camellia sinensis) and tea-derived polyphenols have been carried out. However, the anticarcinogenic activity of the nonpolyphenolic fraction of green tea has been poorly elucidated. To study this problem, the effect of the nonpolyphenolic fraction of green tea leaves was analyzed using in vitro and in vivo experiments associated with tumor initiation and promotion as follows: 1) The nonpolyphenolic fraction caused a strong suppressive effect on umu C gene expression in Salmonella typhimurium (TA 1535/pSK 1002) induced by genotoxic substances such as 2-amino-6-methyldipirido[1,2-a:3',2'-d]imidazole (Glu-P-1) and 2-aminoanthracene (2-AA) in the presence of a hepatic metabolizing enzyme mixture. 2) The same fraction showed a dose-dependent inhibition of ornithine decarboxylase (ODC) in BALB/c 3T3 fibroblasts induced by a tumor promotor, 12-O-tetradecanoylphorbol-13-acetate (TPA). 3) The same fraction also exhibited a significant suppression against mouse skin tumorigenesis induced by 7,12-dimethylbenz[a]anthracene (DMBA) (initiator) and TPA (promotor) through inhibition at both stages of tumor initiation and promotion. These results suggest that the nonpolyphenolic fraction of green tea has a potent suppressing activity against carcinogenesis associated with tumor initiation and promotion.
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Bee products prevent VEGF-induced angiogenesis in human umbilical vein endothelial cells
2009-01-01
Background Vascular endothelial growth factor (VEGF) is a key regulator of pathogenic angiogenesis in diseases such as cancer and diabetic retinopathy. Bee products [royal jelly (RJ), bee pollen, and Chinese red propolis] from the honeybee, Apis mellifera, have been used as traditional health foods for centuries. The aim of this study was to investigate the anti-angiogenic effects of bee products using human umbilical vein endothelial cells (HUVECs). Methods In an in vitro tube formation assay, HUVECs and fibroblast cells were incubated for 14 days with VEGF and various concentrations of bee products [RJ, ethanol extract of bee pollen, ethanol extract of Chinese red propolis and its constituent, caffeic acid phenethyl ester (CAPE)]. To clarify the mechanism of in vitro angiogenesis, HUVEC proliferation and migration were induced by VEGF with or without various concentrations of RJ, bee pollen, Chinese red propolis, and CAPE. Results RJ, bee pollen, Chinese red propolis, and CAPE significantly suppressed VEGF-induced in vitro tube formation in the descending order: CAPE > Chinese red propolis >> bee pollen > RJ. RJ and Chinese red propolis suppressed both VEGF-induced HUVEC proliferation and migration. In contrast, bee pollen and CAPE suppressed only the proliferation. Conclusion Among the bee products, Chinese red propolis and CAPE in particular showed strong suppressive effects against VEGF-induced angiogenesis. These findings indicate that Chinese red propolis and CAPE may have potential as preventive and therapeutic agents against angiogenesis-related human diseases. PMID:19917137
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Woo, Tae-Gyun; Yoon, Min-Ho; Hong, Shin-Deok; Choi, Jiyun; Ha, Nam-Chul; Sun, Hokeun; Park, Bum-Joon
2017-01-01
Hyper-activation of PAK1 (p21-activated kinase 1) is frequently observed in human cancer and speculated as a target of novel anti-tumor drug. In previous, we also showed that PAK1 is highly activated in the Smad4-deficient condition and suppresses PUMA (p53 upregulated modulator of apoptosis) through direct binding and phosphorylation. On the basis of this result, we have tried to find novel PAK1-PUMA binding inhibitors. Through ELISA-based blind chemical library screening, we isolated single compound, IPP-14 (IPP; Inhibitor of PAK1-PUMA), which selectively blocks the PAK1-PUMA binding and also suppresses cell proliferation via PUMA-dependent manner. Indeed, in PUMA-deficient cells, this chemical did not show anti-proliferating effect. This chemical possessed very strong PAK1 inhibition activity that it suppressed BAD (Bcl-2-asoociated death promoter) phosphorylation and meta-phase arrest via Aurora kinase inactivation in lower concentration than that of previous PAK1 kinase, FRAX486 and AG879. Moreover, our chemical obviously induced p21/WAF1/CIP1 (Cyclin-dependent kinase inhibitor 1A) expression by releasing from Bcl-2 (B-cell lymphoma-2) and by inhibition of AKT-mediated p21 suppression. Considering our result, IPP-14 and its derivatives would be possible candidates for PAK1 and p21 induction targeted anti-cancer drug. PMID:28423593
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KOMARNYTSKY, SLAVKO; ESPOSITO, DEBORA; POULEV, ALEXANDER; RASKIN, ILYA
2013-01-01
A group of bioactive steroidal glycosides (pregnanes) with anorectic activity in animals was isolated from several genera of milkweeds including Hoodia and Asclepias. In this study, we investigated the effects, structure-activity relationships, and mechanism of action of pregnane glycosides on steroidogenesis in human adrenocortical H295R cells. Administration of pregnane glycosides for 24 h suppressed the basal and forskolin-stimulated release of androstenedione, corticosterone, and cortisone from H295R cells. The conversion of progesterone to 11-deoxycorticosterone and 17-hydroxyprogesterone to either androstenedione or 11-deoxycortisol was most strongly affected, with 12-cinnamoyl-, benzoyl-, and tigloyl-containing pregnanes showing the highest activity. Incubation of pregnane glycosides for 24 h had no effect on mRNA transcripts of CYP11A1, CYP21A1, CYP11B1 cytochrome enzymes and steroidogenic acute regulatory protein (StaR) protein, yet resulted in twofold decrease in HSD3B1 mRNA levels. At the same time, pregnane glycosides had no effect on the CYP1, 2, or 3 drug and steroid metabolism enzymes and showed weak Na+/K+ ATPase and glucocorticoid receptor binding. Taken together, these data suggest that pregnane glycosides specifically suppress steroidogenesis through strong inhibition of 11β-hydroxylase and steroid 17-alpha-monooxygenase, and weak inhibition of cytochrome P450 side chain cleavage enzyme and 21β-hydroxylase, but not 3β-hydroxysteroid dehydrogenase/isomerase. PMID:23065845
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Kodela, Ravinder; Nath, Niharika; Chattopadhyay, Mitali; Nesbitt, Diandra E; Velázquez-Martínez, Carlos A; Kashfi, Khosrow
2015-01-01
Colorectal cancer (CRC) is the second leading cause of death due to cancer and the third most common cancer in men and women in the USA. Nuclear factor kappa B (NF-κB) is known to be activated in CRC and is strongly implicated in its development and progression. Therefore, activated NF-κB constitutes a bona fide target for drug development in this type of malignancy. Many epidemiological and interventional studies have established nonsteroidal anti-inflammatory drugs (NSAIDs) as a viable chemopreventive strategy against CRC. Our previous studies have shown that several novel hydrogen sulfide-releasing NSAIDs are promising anticancer agents and are safer derivatives of NSAIDs. In this study, we examined the growth inhibitory effect of a novel H2S-releasing naproxen (HS-NAP), which has a repertoire as a cardiovascular-safe NSAID, for its effects on cell proliferation, cell cycle phase transitions, and apoptosis using HT-29 human colon cancer cells. We also investigated its effect as a chemo-preventive agent in a xenograft mouse model. HS-NAP suppressed the growth of HT-29 cells by induction of G0/G1 arrest and apoptosis and downregulated NF-κB. Tumor xenografts in mice were significantly reduced in volume. The decrease in tumor mass was associated with a reduction of cell proliferation, induction of apoptosis, and decreases in NF-κB levels in vivo. Therefore, HS-NAP demonstrates strong anticancer potential in CRC.
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Yoon, M J; Kang, Y J; Lee, J A; Kim, I Y; Kim, M A; Lee, Y S; Park, J H; Lee, B Y; Kim, I A; Kim, H S; Kim, S-A; Yoon, A-R; Yun, C-O; Kim, E-Y; Lee, K; Choi, K S
2014-01-01
Although curcumin suppresses the growth of a variety of cancer cells, its poor absorption and low systemic bioavailability have limited its translation into clinics as an anticancer agent. In this study, we show that dimethoxycurcumin (DMC), a methylated, more stable analog of curcumin, is significantly more potent than curcumin in inducing cell death and reducing the clonogenicity of malignant breast cancer cells. Furthermore, DMC reduces the tumor growth of xenografted MDA-MB 435S cells more strongly than curcumin. We found that DMC induces paraptosis accompanied by excessive dilation of mitochondria and the endoplasmic reticulum (ER); this is similar to curcumin, but a much lower concentration of DMC is required to induce this process. DMC inhibits the proteasomal activity more strongly than curcumin, possibly causing severe ER stress and contributing to the observed dilation. DMC treatment upregulates the protein levels of CCAAT-enhancer-binding protein homologous protein (CHOP) and Noxa, and the small interfering RNA-mediated suppression of CHOP, but not Noxa, markedly attenuates DMC-induced ER dilation and cell death. Interestingly, DMC does not affect the viability, proteasomal activity or CHOP protein levels of human mammary epithelial cells, suggesting that DMC effectively induces paraptosis selectively in breast cancer cells, while sparing normal cells. Taken together, these results suggest that DMC triggers a stronger proteasome inhibition and higher induction of CHOP compared with curcumin, giving it more potent anticancer effects on malignant breast cancer cells. PMID:24625971
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The Basis of the Syllable Hierarchy: Articulatory Pressures or Universal Phonological Constraints?
Zhao, Xu; Berent, Iris
2018-02-01
Across languages, certain syllable types are systematically preferred to others (e.g., [Formula: see text] lbif, where [Formula: see text] indicates a preference). Previous research has shown that these preferences are active in the brains of individual speakers, they are evident even when none of these syllable types exists in participants' language, and even when the stimuli are presented in print. These results suggest that the syllable hierarchy cannot be reduced to either lexical or auditory/phonetic pressures. Here, we examine whether the syllable hierarchy is due to articulatory pressures. According to the motor embodiment view, the perception of a linguistic stimulus requires simulating its production; dispreferred syllables (e.g., lbif) are universally disliked because their production is harder to simulate. To address this possibility, we assessed syllable preferences while articulation was mechanically suppressed. Our four experiments each found significant effects of suppression. Remarkably, people remained sensitive to the syllable hierarchy regardless of suppression. Specifically, results with auditory materials (Experiments 1-2) showed strong effects of syllable structure irrespective of suppression. Moreover, syllable structure uniquely accounted for listeners' behavior even when controlling for several phonetic characteristics of our auditory materials. Results with printed stimuli (Experiments 3-4) were more complex, as participants in these experiments relied on both phonological and graphemic information. Nonetheless, readers were sensitive to most of the syllable hierarchy (e.g., [Formula: see text]), and these preferences emerged when articulation was suppressed, and even when the statistical properties of our materials were controlled via a regression analysis. Together, these findings indicate that speakers possess broad grammatical preferences that are irreducible to either sensory or motor factors.
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Allen, J.C.; Krieger, S.M.; Walters, J.R.; Collazo, J.A.
2006-01-01
We determined the effects of fire history and a riparian-upland gradient on the breeding bird community at Fort Bragg Military Installation in North Carolina, one of the largest remnant areas of the endangered longleaf pine (Pinus palustris) ecosystem. Study sites were classified into two treatments: fire-intense (areas experiencing growing-season burns) and fire-suppressed (areas lacking fires). Within each treatment, bird and vegetation data were recorded at point-count stations positioned at three distances from streamhead pocosins to characterize the riparian-upland habitat gradient: 0, 75, and ≥150 m. Total bird abundance and species richness varied significantly along the riparian-upland gradient, with pocosins contributing greatly to avian biodiversity. Our data revealed strong effects of fire history and riparian-upland gradient on bird species, which we described in terms of breeding-bird assemblages. Members of the open longleaf assemblage (e.g., Red- cockaded Woodpecker [Picoides borealis], Bachman's Sparrow [Aimophila aestivalis]) were most common in fire-intense areas and at upland locations. Members of the fire-suppressed assemblage (e.g., Wood Thrush [Hylocichla mustelina], Ovenbird [Seiurus aurocapilla]) were confined to pocosins in fire-intense areas, but became more abundant in fire-suppressed areas. Members of the pocosin assemblage (e.g., Eastern Towhee [Pipilo erythropthalamus], Common Yellowthroat [Geothlypis trichas]) were largely confined to pocosins and, in some cases, were most abundant in fire-intense pocosins. Fire suppression increased structural diversity of vegetation and promoted one breeding-bird assemblage (fire-suppressed), but at the expense of two others (open longleaf, pocosin). Continued management of Fort Bragg to promote longleaf pine restoration is essential for supporting conservation of the open-longleaf bird assemblage; in addition, it will benefit the pocosin assemblage.
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Oh, You-Chang; Cho, Won-Kyung; Jeong, Yun Hee; Im, Ga Young; Kim, Aeyung; Hwang, Youn-Hwan; Kim, Taesoo; Song, Kwang Hoon; Ma, Jin Yeul
2012-01-01
KIOM-MA was recently reported as a novel herbal medicine effective for atopic dermatitis and asthma. In this study, we have demonstrated the inhibitory effect of KIOM-MA on proinflammatory mediator produced in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. KIOM-MA significantly inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) as well as nitric oxide (NO) and prostaglandin E(2) (PGE(2)). Consistent with the inhibitory effect on PGE(2), KIOM-MA suppresses the LPS-induced migration of macrophages and gelatinase activity and the expression of matrix metalloprotease-9 (MMP-9) in a dose-dependent manner. Additionally, KIOM-MA showed a strong suppressive effect on the inflammatory cytokines production such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). We also found that KIOM-MA inhibits the activation of nuclear factor-κB (NF-κB) and represses the activity of extracellular signal-regulated kinase (ERK), p38, and c-Jun NH(2)-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs). Taken together, we elucidated the mechanism of anti-inflammatory effect of KIOM-MA using RAW 264.7 cells stimulated by LPS.
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Oh, You-Chang; Cho, Won-Kyung; Jeong, Yun Hee; Im, Ga Young; Kim, Aeyung; Hwang, Youn-Hwan; Kim, Taesoo; Song, Kwang Hoon; Ma, Jin Yeul
2012-01-01
KIOM-MA was recently reported as a novel herbal medicine effective for atopic dermatitis and asthma. In this study, we have demonstrated the inhibitory effect of KIOM-MA on proinflammatory mediator produced in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. KIOM-MA significantly inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) as well as nitric oxide (NO) and prostaglandin E2 (PGE2). Consistent with the inhibitory effect on PGE2, KIOM-MA suppresses the LPS-induced migration of macrophages and gelatinase activity and the expression of matrix metalloprotease-9 (MMP-9) in a dose-dependent manner. Additionally, KIOM-MA showed a strong suppressive effect on the inflammatory cytokines production such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). We also found that KIOM-MA inhibits the activation of nuclear factor-κB (NF-κB) and represses the activity of extracellular signal-regulated kinase (ERK), p38, and c-Jun NH2-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs). Taken together, we elucidated the mechanism of anti-inflammatory effect of KIOM-MA using RAW 264.7 cells stimulated by LPS. PMID:23243447
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NASA Astrophysics Data System (ADS)
Chakraborty, Sovan; Mirizzi, Alessandro; Saviano, Ninetta; Seixas, David de Sousa
2014-05-01
It has been recently pointed out that by removing the axial symmetry in the "multi-angle effects" associated with the neutrino-neutrino interactions for supernova (SN) neutrinos a new multi-azimuthal-angle (MAA) instability would arise. In particular, for a flux ordering Fνe>Fν ¯e>Fνx, as expected during the SN accretion phase, this instability occurs in the normal neutrino mass hierarchy. However, during this phase, the ordinary matter density can be larger than the neutrino one, suppressing the self-induced conversions. In this regard, we investigate the matter suppression of the MAA effects, performing a linearized stability analysis of the neutrino equations of motion, in the presence of realistic SN density profiles. We compare these results with the numerical solution of the SN neutrino nonlinear evolution equations. Assuming axially symmetric distributions of neutrino momenta, we find that the large matter term strongly inhibits the MAA effects. In particular, the hindrance becomes stronger including realistic forward-peaked neutrino angular distributions. As a result, in our model for a 10.8 M⊙ iron-core SNe, MAA instability does not trigger any flavor conversion during the accretion phase. Instead, for a 8.8 M⊙ O-Ne-Mg core SN model, with lower matter density profile and less forward-peaked angular distributions, flavor conversions are possible also at early times.
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Sone, Hideyuki; Kamiyama, Shin; Higuchi, Mutsumi; Fujino, Kaho; Kubo, Shizuka; Miyazawa, Masami; Shirato, Saya; Hiroi, Yuka; Shiozawa, Kota
2016-07-29
It is known that biotin prevents the development of diabetes by increasing the functions of pancreatic beta-cells and improving insulin sensitivity in the periphery. However, its anti-obesity effects such as anorectic effects remain to be clarified. Acetyl CoA carboxylase (ACC), a biotin-dependent enzyme, has two isoforms (ACC1 and ACC2) and serves to catalyze the reaction of acetyl CoA to malonyl CoA. In the hypothalamus, ACC2 increases the production of malonyl CoA, which acts as a satiety signal. In this study, we investigated whether biotin increases the gene expression of ACC2 in the hypothalamus and suppresses food intake in mice administered excessive biotin. Food intake was significantly decreased by biotin, but plasma regulators of appetite, including glucose, ghrelin, and leptin, were not affected. On the other hand, biotin notably accumulated in the hypothalamus and enhanced ACC2 gene expression there, but it did not change the gene expression of ACC1, malonyl CoA decarboxylase (a malonyl CoA-degrading enzyme), and AMP-activated protein kinase α-2 (an ACC-inhibitory enzyme). These findings strongly suggest that biotin potentiates the suppression of appetite by upregulating ACC2 gene expression in the hypothalamus. This effect of biotin may contribute to the prevention of diabetes by biotin treatment. Copyright © 2016 Elsevier Inc. All rights reserved.
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Maenhout, Sarah K.; Four, Stephanie Du; Corthals, Jurgen; Neyns, Bart; Thielemans, Kris; Aerts, Joeri L.
2014-01-01
AZD1480 is a potent, competitive small-molecule inhibitor of JAK1/2 kinase which inhibits STAT3 phosphorylation and tumor growth. Here we investigated the effects of AZD1480 on the function of different immune cell populations in a melanoma model. When MO4 tumor-bearing mice were treated with AZD1480 we observed a strong inhibition of tumor growth as well as a prolonged survival. Moreover, a significant decrease in the percentage of myeloid-derived suppressor cells (MDSCs) was observed after treatment with AZD1480. However, AZD1480 enhanced the suppressive capacity of murine MDSCs while at the same time impairing the proliferative as well as the IFN-γ secretion capacity of murine T cells. The addition of AZD1480 to co-cultures of human MDSCs and T cells does not affect the suppressive activity of MDSCs but it does reduce the IFN-γ secretion and the proliferative capacity of T cells. We showed that although AZD1480 has the ability to delay the tumor growth of MO4 tumor-bearing mice, this drug has detrimental effects on several aspects of the immune system. These data indicate that systemic targeting of the JAK/STAT pathway by JAK1/2 inhibition can have divergent effects on tumor growth and anti-tumor immune responses. PMID:25149535
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Way, Danielle A; Ghirardo, Andrea; Kanawati, Basem; Esperschütz, Jürgen; Monson, Russell K; Jackson, Robert B; Schmitt-Kopplin, Philippe; Schnitzler, Jörg-Peter
2013-10-01
Isoprene, a volatile organic compound produced by some plant species, enhances abiotic stress tolerance under current atmospheric CO2 concentrations, but its biosynthesis is negatively correlated with CO2 concentrations. We hypothesized that losing the capacity to produce isoprene would require stronger up-regulation of other stress tolerance mechanisms at low CO2 than at higher CO2 concentrations. We compared metabolite profiles and physiological performance in poplars (Populus × canescens) with either wild-type or RNAi-suppressed isoprene emission capacity grown at pre-industrial low, current atmospheric, and future high CO2 concentrations (190, 390 and 590 ppm CO2 , respectively). Suppression of isoprene biosynthesis led to significant rearrangement of the leaf metabolome, increasing stress tolerance responses such as xanthophyll cycle pigment de-epoxidation and antioxidant levels, as well as altering lipid, carbon and nitrogen metabolism. Metabolic and physiological differences between isoprene-emitting and suppressed lines diminished as growth CO2 concentrations rose. The CO2 dependence of our results indicates that the effects of isoprene biosynthesis are strongest at pre-industrial CO2 concentrations. Rising CO2 may reduce the beneficial effects of biogenic isoprene emission, with implications for species competition. This has potential consequences for future climate warming, as isoprene emitted from vegetation has strong effects on global atmospheric chemistry. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.
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Suppression of the E. coli SOS response by dNTP pool changes.
Maslowska, Katarzyna H; Makiela-Dzbenska, Karolina; Fijalkowska, Iwona J; Schaaper, Roel M
2015-04-30
The Escherichia coli SOS system is a well-established model for the cellular response to DNA damage. Control of SOS depends largely on the RecA protein. When RecA is activated by single-stranded DNA in the presence of a nucleotide triphosphate cofactor, it mediates cleavage of the LexA repressor, leading to expression of the 30(+)-member SOS regulon. RecA activation generally requires the introduction of DNA damage. However, certain recA mutants, like recA730, bypass this requirement and display constitutive SOS expression as well as a spontaneous (SOS) mutator effect. Presently, we investigated the possible interaction between SOS and the cellular deoxynucleoside triphosphate (dNTP) pools. We found that dNTP pool changes caused by deficiencies in the ndk or dcd genes, encoding nucleoside diphosphate kinase and dCTP deaminase, respectively, had a strongly suppressive effect on constitutive SOS expression in recA730 strains. The suppression of the recA730 mutator effect was alleviated in a lexA-deficient background. Overall, the findings suggest a model in which the dNTP alterations in the ndk and dcd strains interfere with the activation of RecA, thereby preventing LexA cleavage and SOS induction. Published by Oxford University Press on behalf of Nucleic Acids Research 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.
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THE EFFECTS OF TRANSIENTS ON PHOTOSPHERIC AND CHROMOSPHERIC POWER DISTRIBUTIONS
DOE Office of Scientific and Technical Information (OSTI.GOV)
Samanta, T.; Banerjee, D.; Pant, V.
2016-09-01
We have observed a quiet-Sun region with the Swedish 1 m Solar Telescope equipped with the CRISP Imaging SpectroPolarimeter. High-resolution, high-cadence, H α line scanning images were taken to observe different layers of the solar atmosphere from the photosphere to upper chromosphere. We study the distribution of power in different period bands at different heights. Power maps of the upper photosphere and the lower chromosphere show suppressed power surrounding the magnetic-network elements, known as “magnetic shadows.” These also show enhanced power close to the photosphere, traditionally referred to as “power halos.” The interaction between acoustic waves and inclined magnetic fieldsmore » is generally believed to be responsible for these two effects. In this study we explore whether small-scale transients can influence the distribution of power at different heights. We show that the presence of transients, like mottles, Rapid Blueshifted Excursions (RBEs), and Rapid Redshifted Excursions (RREs), can strongly influence the power maps. The short and finite lifetime of these events strongly affects all power maps, potentially influencing the observed power distribution. We show that Doppler-shifted transients like RBEs and RREs that occur ubiquitously can have a dominant effect on the formation of the power halos in the quiet Sun. For magnetic shadows, transients like mottles do not seem to have a significant effect on the power suppression around 3 minutes, and wave interaction may play a key role here. Our high-cadence observations reveal that flows, waves, and shocks manifest in the presence of magnetic fields to form a nonlinear magnetohydrodynamic system.« less
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Regulation of Cell Survival and Motility in Human Breast Cancer Cells by Sphingosine Kinase
2002-01-01
mononoclonal anti-IGF-II and anti-IGFR1 antibodies strongly suppressed proliferation induced by S IP. However, in the presence of serum where overexpression...of SPHK1 significantly enhanced cell growth, addition of anti-IGF-IR antibody which blocks the effects of both IGF-I and IGF-II, did not have a marked... antibody specific for phosphotyrosine 418, an autophosphorylation site located in the Src catalytic domain required for full activity. In contrast
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Photodynamic therapy affects the expression of IL-6 and IL-10 in vivo
NASA Astrophysics Data System (ADS)
Gollnick, Sandra O.; Musser, David A.; Henderson, Barbara W.
1998-05-01
Photodynamic therapy (PDT), which can effectively destroy malignant tissue, also induces a complex immune response which potentiates anti-tumor immunity, but also inhibits skin contact hypersensitivity (CHS) and prolongs skin graft survival. The underlying mechanisms responsible for these effects are poorly understood, but are likely to involve meditation by cytokines. We demonstrate in a BALB/c mouse model that PDT delivered to normal and tumor tissue in vivo causes marked changes in the expression of cytokines interleukin (IL)-6 and IL-10. IL-6 mRNA and protein are rapidly and strongly enhanced in the PDT treated EMT6 tumor. Previous studies have shown that intratumoral injection of IL- 6 or transduction of the IL-6 gene into tumor cells can enhance tumor immunogenicity and inhibit tumor growth in experimental murine tumor systems. Thus, PDT may enhance local anti-tumor immunity by up-regulating IL-6. PDT also results in an increase in IL-10 mRNA and protein in the skin. The same PDT regime which enhances IL-10 production in the skin has been shown to strongly inhibit the CHS response. The kinetics of IL-10 expression coincide with the known kinetics of PDT induced CHS suppression and we propose that the enhanced IL-10 expression plays a role in the observed suppression of cell mediated responses seen following PDT.
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Reevaluation of immune activation in the era of cART and an aging HIV-infected population
de Armas, Lesley R.; Pallikkuth, Suresh; George, Varghese; Rinaldi, Stefano; Pahwa, Rajendra; Arheart, Kristopher L.
2017-01-01
Biological aging is associated with immune activation (IA) and declining immunity due to systemic inflammation. It is widely accepted that HIV infection causes persistent IA and premature immune senescence despite effective antiretroviral therapy and virologic suppression; however, the effects of combined HIV infection and aging are not well defined. Here, we assessed the relationship between markers of IA and inflammation during biological aging in HIV-infected and -uninfected populations. Antibody response to seasonal influenza vaccination was implemented as a measure of immune competence and relationships between IA, inflammation, and antibody responses were explored using statistical modeling appropriate for integrating high-dimensional data sets. Our results show that markers of IA, such as coexpression of HLA antigen D related (HLA-DR) and CD38 on CD4+ T cells, exhibit strong associations with HIV infection but not with biological age. Certain variables that showed a strong relationship with aging, such as declining naive and CD38+ CD4 and CD8+ T cells, did so regardless of HIV infection. Interestingly, the variable of biological age was not identified in a predictive model as significantly impacting vaccine responses in either group, while distinct IA and inflammatory variables were closely associated with vaccine response in HIV-infected and -uninfected populations. These findings shed light on the most relevant and persistent immune defects during virological suppression with antiretroviral therapy. PMID:29046481
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Reevaluation of immune activation in the era of cART and an aging HIV-infected population.
de Armas, Lesley R; Pallikkuth, Suresh; George, Varghese; Rinaldi, Stefano; Pahwa, Rajendra; Arheart, Kristopher L; Pahwa, Savita
2017-10-19
Biological aging is associated with immune activation (IA) and declining immunity due to systemic inflammation. It is widely accepted that HIV infection causes persistent IA and premature immune senescence despite effective antiretroviral therapy and virologic suppression; however, the effects of combined HIV infection and aging are not well defined. Here, we assessed the relationship between markers of IA and inflammation during biological aging in HIV-infected and -uninfected populations. Antibody response to seasonal influenza vaccination was implemented as a measure of immune competence and relationships between IA, inflammation, and antibody responses were explored using statistical modeling appropriate for integrating high-dimensional data sets. Our results show that markers of IA, such as coexpression of HLA antigen D related (HLA-DR) and CD38 on CD4+ T cells, exhibit strong associations with HIV infection but not with biological age. Certain variables that showed a strong relationship with aging, such as declining naive and CD38+ CD4 and CD8+ T cells, did so regardless of HIV infection. Interestingly, the variable of biological age was not identified in a predictive model as significantly impacting vaccine responses in either group, while distinct IA and inflammatory variables were closely associated with vaccine response in HIV-infected and -uninfected populations. These findings shed light on the most relevant and persistent immune defects during virological suppression with antiretroviral therapy.
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On dark matter interactions with the Standard Model through an anomalous Z'
NASA Astrophysics Data System (ADS)
Ismail, Ahmed; Katz, Andrey; Racco, Davide
2017-10-01
We study electroweak scale Dark Matter (DM) whose interactions with baryonic matter are mediated by a heavy anomalous Z'. We emphasize that when the DM is a Majorana particle, its low-velocity annihilations are dominated by loop suppressed annihilations into the gauge bosons, rather than by p-wave or chirally suppressed annihilations into the SM fermions. Because the Z ' is anomalous, these kinds of DM models can be realized only as effective field theories (EFTs) with a well-defined cutoff, where heavy spectator fermions restore gauge invariance at high energies. We formulate these EFTs, estimate their cutoff and properly take into account the effect of the Chern-Simons terms one obtains after the spectator fermions are integrated out. We find that, while for light DM collider and direct detection experiments usually provide the strongest bounds, the bounds at higher masses are heavily dominated by indirect detection experiments, due to strong annihilation into W + W -, ZZ, Zγ and possibly into gg and γγ. We emphasize that these annihilation channels are generically significant because of the structure of the EFT, and therefore these models are prone to strong indirect detection constraints. Even though we focus on selected Z' models for illustrative purposes, our setup is completely generic and can be used for analyzing the predictions of any anomalous Z'-mediated DM model with arbitrary charges.
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MiR-26b Mimic Inhibits Glioma Proliferation In Vitro and In Vivo Suppressing COX-2 Expression.
Chen, Zheng-Gang; Zheng, Chuan-Yi; Cai, Wang-Qing; Li, Da-Wei; Ye, Fu-Yue; Zhou, Jian; Wu, Ran; Yang, Kun
2017-08-11
Glioma is the most common malignant tumor of the nervous system. Studies have shown the microRNA (miR)-26b/cyclooxygenase (COX)-2 axis in the development and progression in many tumor cells. Our study aims to investigate the effect and mechanism of miR-26b/COX-2 axis in glioma. Decreased expression of miR-26b with increased level of COX-2 was found in glioma tissues compared with matched normal tissues. A strong negative correlation was observed between the level of miR-26b and COX-2 in 30 glioma tissues. The miR-26b was then overexpressed by transfecting miR-26b mimic into U-373 cells. The invasive cell number and wounld closing rate were reduced in U-373 cells transfected with miR-26b mimic. Besides, COX2 siRNA enhanced the effect of miR-26b mimic in suppressing the expression of p-ERK1 and p-JNK. Finally, the in vivo experiment revealed that miR-26b mimic transfection strongly reduced the tumor growth, tumor volume and the expression of matrix metalloproteinase (MMP)-2, MMP-9). Taken together, our research indicated a miR-26b/COX-2/ERK/JNK axis in regulating the motility of glioma in vitro and in vivo, providing a new sight for treatment of glioma.
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NASA Astrophysics Data System (ADS)
Bell, T. L.; Rosenfeld, D.; Kim, K.; Hahnenberger, M.
2006-05-01
Persistent and strong dependence of rain rate on the day of the week has been found in Tropical Rainfall Measuring Mission (TRMM) satellite estimates of summer afternoon rainfall over the southeast U.S. and the nearby Atlantic from 1998 to 2005. Midweek (Tue--Thu) rain rates and rain area appear to increase over land, and this increase is accompanied by a corresponding diminution of rainfall over nearby waters. Reanalysis data from atmospheric models suggest that there is a corresponding weekly variation in atmospheric winds consistent with the changes in rainfall. These variations are almost certainly caused by weekly variations in human activity. The most likely cause of the observed changes in rainfall is the well documented weekly variation in atmospheric pollution. Particulate pollution is highest in the middle of the week. Considerable observational and modeling evidence has accumulated concerning the effects of aerosols on precipitation. Most of this evidence relates to the suppression of precipitation by aerosols, but it has been argued that storms in highly unstable moist environments can be invigorated by aerosols, and some modeling studies seem to confirm this. The strong weekly cycle in rainfall observed over the southeast U.S. along with what appears to be dynamical suppression of rainfall over the nearby Atlantic, and the lack of an observable cycle over the southwest U.S., are consistent with this theory.
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NASA Technical Reports Server (NTRS)
Bell, Thomas L.; Rosenfeld, Daniel; Kim, Kyu-Myong; Hahnenberger, Maura
2006-01-01
Persistent and strong dependence of rain rate on the day of the week has been found in Tropical Rainfall Measuring Mission (TRMM) satellite estimates of summer afternoon rainfall over the southeast U.S. and the nearby Atlantic from 1998 to 2005. Midweek (Tue-Thu) rain rates and rain area appear to increase over land, and this increase is accompanied by a corresponding diminution of rainfall over nearby waters. Reanalysis data from atmospheric models, suggest that there is a corresponding weekly variation in atmospheric winds consistent with the changes in rainfall. These variations are almost certainly caused by weekly variations in human activity. The most likely cause of the observed changes in rainfall is the well documented weekly variation in atmospheric pollution. Particulate pollution is highest in the middle of the week. Considerable observational and modeling evidence has accumulated concerning the effects of aerosols on precipitation. Most of this evidence relates to the suppression of precipitation by aerosols, but it has been argued that storms in highly unstable moist environments can be invigorated by aerosols, and some modeling studies seem to confirm this. The strong weekly cycle in rainfall observed over the southeast U.S. along with what appears to be dynamical suppression of rainfall over the nearby Atlantic, and the lack of an observable cycle over the southwest U.S., are consistent with this theory.
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Hussen, Sophia A; Easley, Kirk A; Smith, Justin C; Shenvi, Neeta; Harper, Gary W; Camacho-Gonzalez, Andres F; Stephenson, Rob; Del Rio, Carlos
2018-04-04
Social capital, the sum of an individual's resource-containing social network connections, has been proposed as a facilitator of successful HIV care engagement. We explored relationships between social capital, psychological covariates (depression, stigma and internalized homonegativity), and viral suppression in a sample of young Black gay, bisexual and other men who have sex with men (YB-GBMSM). We recruited 81 HIV-positive YB-GBMSM 18-24 years of age from a clinic setting. Participants completed a cross-sectional survey, and HIV-1 viral load (VL) measurements were extracted from the medical record. Sixty-five percent (65%) were virally suppressed (HIV-1 VL ≤ 40 copies/ml). Forty-seven percent (47%) had a positive depression screen. Depressive symptoms affected viral suppression differently in YB-GBMSM with lower vs. higher social capital (p = 0.046, test for statistical interaction between depression and social capital). The odds of viral suppression among YB-GBMSM with lower social capital was 93% lower among those with depressive symptoms (OR 0.07, p = 0.002); however, there was no association between depressive symptoms and viral suppression among those with higher social capital. Our results suggest that social capital may buffer the strong negative effects of depressive symptoms on clinical outcomes in YB-GBMSM living with HIV. In addition to treating depression, there is a role for interventions to augment social capital among YB-GBMSM living with HIV as a strategy for enhancing care engagement.
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Lu, Yusheng; Li, Yong; Yang, Qiaosong; Zhang, Zhisheng; Chen, Yan; Zhang, Sheng; Peng, Xin-Xiang
2014-03-01
Glycolate oxidase (GLO) is a key enzyme for photorespiration in plants. Previous studies have demonstrated that suppression of GLO causes photosynthetic inhibition, and the accumulated glycolate with the deactivated Rubisco is likely involved in the regulation. Using isolated Rubisco and chloroplasts, it has been found that only glyoxylate can effectively inactivate Rubisco and meanwhile inhibit photosynthesis, but little in vivo evidence has been acquired and reported. In this study, we have generated the transgenic rice (Oryza sativa) plants with GLO being constitutively silenced, and conducted the physiological and biochemical analyses on these plants to explore the regulatory mechanism. When GLO was downregulated, the net photosynthetic rate (Pn) was reduced and the plant growth was correspondingly stunted. Surprisingly, glyoxylate, as a product of the GLO catalysis, was accumulated in response to the GLO suppression, like its substrate glycolate. Furthermore, the glyoxylate content was found to be inversely proportional to the Pn while the Pn is directly proportional to the Rubisco activation state in the GLO-suppressed plants. A mathematical fitting equation using least square method also demonstrated that the Rubisco activation state was inversely proportional to the glyoxylate content. Despite that the further analyses we have conducted failed to reveal how glyoxylate was accumulated in response to the GLO suppression, the current results do strongly suggest that there may exist an unidentified, alternative pathway to produce glyoxylate, and that the accumulated glyoxylate inhibits photosynthesis by deactivating Rubisco, and causes the photorespiratory phenotype in the GLO-suppressed rice plants. © 2013 Scandinavian Plant Physiology Society.
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Tompkins, Connie A.; Blake, Margaret T.; Wambaugh, Julie; Meigh, Kimberly
2012-01-01
Background This manuscript reports the initial phase of testing for a novel, “Contextual constraint” treatment, designed to stimulate inefficient language comprehension processes in adults with right hemisphere brain damage (RHD). Two versions of treatment were developed to target two normal comprehension processes that have broad relevance for discourse comprehension and that are often disrupted by RHD: coarse semantic coding and suppression. The development of the treatment was informed by two well-documented strengths of the RHD population. The first is consistently better performance on assessments that are implicit, or nearly so, than on explicit, metalinguistic measures of language and cognitive processing. The second is improved performance when given linguistic context that moderately-to-strongly biases an intended meaning. Treatment consisted of providing brief context sentences to prestimulate, or constrain, intended interpretations. Participants made no explicit associations or judgments about the constraint sentences; rather, these contexts served only as implicit primes. Aims This Phase I treatment study aimed to determine the effects of a novel, implicit, Contextual Constraint treatment in adults with RHD whose coarse coding or suppression processes were inefficient. Treatment was hypothesized to speed coarse coding or suppression function in these individuals. Methods & Procedures Three adults with RHD participated in this study, one (P1) with a coarse coding deficit and two (P2, P3) with suppression deficits. Probe tasks were adapted from prior studies of coarse coding and suppression in RHD. The dependent measure was the percentage of responses that met predetermined response time criteria. When pre-treatment baseline performance was stable, treatment was initiated. There were two levels of contextual constraint, Strong and Moderate, and treatment for each item began with the provision of the Strong constraint context. Outcomes & Results Treatment-contingent gains were evident after brief periods of treatment, for P1 on two treatment lists, and for P2. P3 made slower but still substantial gains. Maintenance of gains was evident for P1, the only participant for whom it was measured. Conclusions This Phase I treatment study documents the potential for considerable gains from an implicit, Contextual constraint treatment. If replicated, this approach to treatment may hold promise for individuals who do poorly with effortful, metalinguistic treatment tasks, or for whom it is desirable to minimize errors during treatment. The real test of this treatment’s benefit will come from later phase studies of study, which will test broad-based generalization to various aspects of discourse comprehension. PMID:22368317
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Mishra, Vivek; Chatterjee, U.; Campuzano, J. C.; ...
2014-03-30
We present cuprates that possess a large pseudogap that spans much of their phase diagram. The origin of this pseudogap is as debated as the mechanism for high-temperature superconductivity. In one class of theories, the pseudogap arises from some instability not related to pairing, typically charge, spin or orbital current ordering. Evidence of this has come from a variety of measurements indicating symmetry breaking. On the other side are theories where the pseudogap is associated with pairing. This ranges from preformed pairs to resonating valence bond theories where spin singlets become charge coherent. Here, we study pairing in the cupratesmore » by constructing the pair vertex using spectral functions derived from angle-resolved photoemission data. Assuming that the pseudogap is not due to pairing, we find that the superconducting instability is strongly suppressed, in stark contrast to what is actually observed. We trace this suppression to the destruction of the BCS logarithmic singularity from a combination of the pseudogap and lifetime broadening. In conclusion, our findings strongly support those theories of the cuprates where the pseudogap is instead due to pairing.« less
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Diffusion of Sticky Nanoparticles in a Polymer Melt: Crossover from Suppressed to Enhanced Transport
Carroll, Bobby; Bocharova, Vera; Carrillo, Jan-Michael Y.; ...
2018-03-09
The self-diffusion of a single large particle in a fluid is usually described by the classic Stokes–Einstein (SE) hydrodynamic relation. However, there are many fluids where the SE prediction for nanoparticles diffusion fails. These systems include diffusion of nanoparticles in porous media, in entangled and unentangled polymer melts and solutions, and protein diffusion in biological environments. A fundamental understanding of the microscopic parameters that govern nanoparticle diffusion is relevant to a wide range of applications. Here in this work, we present experimental measurements of the tracer diffusion coefficient of small and large nanoparticles that experience strong attractions with unentangled andmore » entangled polymer melt matrices. For the small nanoparticle system, a crossover from suppressed to enhanced diffusion is observed with increasing polymer molecular weight. We interpret these observations based on our theoretical and simulation insights of the preceding article (paper 1) as a result of a crossover from an effective hydrodynamic core–shell to a nonhydrodynamic vehicle mechanism of transport, with the latter strongly dependent on polymer–nanoparticle desorption time. In conclusion, a general zeroth-order qualitative picture for small sticky nanoparticle diffusion in polymer melts is proposed.« less
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Diffusion of Sticky Nanoparticles in a Polymer Melt: Crossover from Suppressed to Enhanced Transport
DOE Office of Scientific and Technical Information (OSTI.GOV)
Carroll, Bobby; Bocharova, Vera; Carrillo, Jan-Michael Y.
The self-diffusion of a single large particle in a fluid is usually described by the classic Stokes–Einstein (SE) hydrodynamic relation. However, there are many fluids where the SE prediction for nanoparticles diffusion fails. These systems include diffusion of nanoparticles in porous media, in entangled and unentangled polymer melts and solutions, and protein diffusion in biological environments. A fundamental understanding of the microscopic parameters that govern nanoparticle diffusion is relevant to a wide range of applications. Here in this work, we present experimental measurements of the tracer diffusion coefficient of small and large nanoparticles that experience strong attractions with unentangled andmore » entangled polymer melt matrices. For the small nanoparticle system, a crossover from suppressed to enhanced diffusion is observed with increasing polymer molecular weight. We interpret these observations based on our theoretical and simulation insights of the preceding article (paper 1) as a result of a crossover from an effective hydrodynamic core–shell to a nonhydrodynamic vehicle mechanism of transport, with the latter strongly dependent on polymer–nanoparticle desorption time. In conclusion, a general zeroth-order qualitative picture for small sticky nanoparticle diffusion in polymer melts is proposed.« less
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Tunable zero-line modes via magnetic field in bilayer graphene
NASA Astrophysics Data System (ADS)
Wang, Ke; Qiao, Zhenhua
Zero-line modes appear in bilayer graphene at the internal boundary between two opposite vertical electrostatic confinements. These one-dimensional modes are metallic along the boundary and exhibit quantized conductance in the absence of inter-valley scattering. However, experimental results show that the conductance is around 0.5 e2/h rather than quantized. This observation can be explained from our numerical results, which suggest that the scattering between zero-line mode and bound states and the presence of atomic scale disorders that provide inter-valley scattering can effectively reduce the conductance to about 0.5 e2/h. We further find that out-of-plane magnetic field can strongly suppress these scattering mechanisms and gives rise to nearly quantized conductance. On one hand, the presence of magnetic field makes bound states become Landau levels, which reduces the scattering between zero-line mode and bound states. On the other hand, the wave function distributions of oppositely propagating zero-line modes at different valleys are spatially separated, which can strongly suppress the inter-valley scattering. Specifically speaking, the conductance can be increased to 3.2 e2/h at 8 T even when the atomic Anderson type disorders are considered.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Do, Minh Truong; Kim, Hyung Gyun; Khanal, Tilak
2013-09-01
Resistance to therapy is the major obstacle to more effective cancer treatment. Heme oxygenase-1 (HO-1) is often highly up-regulated in tumor tissues, and its expression is further increased in response to therapies. It has been suggested that inhibition of HO-1 expression is a potential therapeutic approach to sensitize tumors to chemotherapy and radiotherapy. In this study, we tested the hypothesis that the anti-tumor effects of metformin are mediated by suppression of HO-1 expression in cancer cells. Our results indicate that metformin strongly suppresses HO-1 mRNA and protein expression in human hepatic carcinoma HepG2, cervical cancer HeLa, and non-small-cell lung cancermore » A549 cells. Metformin also markedly reduced Nrf2 mRNA and protein levels in whole cell lysates and suppressed tert-butylhydroquinone (tBHQ)-induced Nrf2 protein stability and antioxidant response element (ARE)-luciferase activity in HepG2 cells. We also found that metformin regulation of Nrf2 expression is mediated by a Keap1-independent mechanism and that metformin significantly attenuated Raf-ERK signaling to suppress Nrf2 expression in cancer cells. Inhibition of Raf-ERK signaling by PD98059 decreased Nrf2 mRNA expression in HepG2 cells, confirming that the inhibition of Nrf2 expression is mediated by an attenuation of Raf-ERK signaling in cancer cells. The inactivation of AMPK by siRNA, DN-AMPK or the pharmacological AMPK inhibitor compound C, revealed that metformin reduced HO-1 expression in an AMPK-independent manner. These results highlight the Raf-ERK-Nrf2 axis as a new molecular target in anticancer therapy in response to metformin treatment. - Highlights: • Metformin inhibits HO-1 expression in cancer cells. • Metformin attenuates Raf-ERK-Nrf2 signaling. • Suppression of HO-1 by metformin is independent of AMPK. • HO-1 inhibition contributes to anti-proliferative effects of metformin.« less
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Tanaka, Kazunari; Tamaru, Shizuka; Nishizono, Shoko; Miyata, Yuji; Tamaya, Kei; Matsui, Toshiro; Tanaka, Takashi; Echizen, Yoshie; Ikeda, Ikuo
2010-01-01
We manufactured a new fermented tea by tea-rolling processing of third-crop green tea (Camellia sinensis) leaves and loquat (Eriobotrya japonica) leaves. The mixed fermented tea extract inhibited pancreatic lipase activity in vitro, and effectively suppressed postprandial hypertriacylglycerolemia in rats. Rats fed a diet containing 1% freeze-dried fermented tea extract for 4 weeks had a significantly lower liver triacylglycerol concentration and white adipose tissue weight than those fed the control diet lacking fermented tea extract. The activity of fatty acid synthase in hepatic cytosol markedly decreased in the fermented tea extract group as compared to the control group. The serum and liver triacylglycerol- and body fat-lowering effects of the mixed fermented tea extract were strong relative to the level of dietary supplementation. These results suggest that the new fermented tea product exhibited hypotriacylglycerolemic and antiobesity properties through suppression of both liver fatty acid synthesis and postprandial hypertriacylglycerolemia by inhibition of pancreatic lipase.
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Renormalization of dijet operators at order 1 /Q 2 in soft-collinear effective theory
NASA Astrophysics Data System (ADS)
Goerke, Raymond; Inglis-Whalen, Matthew
2018-05-01
We make progress towards resummation of power-suppressed logarithms in dijet event shapes such as thrust, which have the potential to improve high-precision fits for the value of the strong coupling constant. Using a newly developed formalism for Soft-Collinear Effective Theory (SCET), we identify and compute the anomalous dimensions of all the operators that contribute to event shapes at order 1 /Q 2. These anomalous dimensions are necessary to resum power-suppressed logarithms in dijet event shape distributions, although an additional matching step and running of observable-dependent soft functions will be necessary to complete the resummation. In contrast to standard SCET, the new formalism does not make reference to modes or λ-scaling. Since the formalism does not distinguish between collinear and ultrasoft degrees of freedom at the matching scale, fewer subleading operators are required when compared to recent similar work. We demonstrate how the overlap subtraction prescription extends to these subleading operators.
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Thermoelectric effects in disordered branched nanowires
NASA Astrophysics Data System (ADS)
Roslyak, Oleksiy; Piriatinskiy, Andrei
2013-03-01
We shall develop formalism of thermal and electrical transport in Si1 - x Gex and BiTe nanowires. The key feature of those nanowires is the possibility of dendrimer type branching. The branching tree can be of size comparable to the short wavelength of phonons and by far smaller than the long wavelength of conducting electrons. Hence it is expected that the branching may suppress thermal and let alone electrical conductance. We demonstrate that the morphology of branches strongly affects the electronic conductance. The effect is important to the class of materials known as thermoelectrics. The small size of the branching region makes large temperature and electrical gradients. On the other hand the smallness of the region would allow the electrical transport being ballistic. As usual for the mesoscopic systems we have to solve macroscopic (temperature) and microscopic ((electric potential, current)) equations self-consistently. Electronic conductance is studied via NEGF formalism on the irreducible electron transfer graph. We also investigate the figure of merit ZT as a measure of the suppressed electron conductance.
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A new strategy for controlling invasive weeds: selecting valuable native plants to defeat them
NASA Astrophysics Data System (ADS)
Li, Weihua; Luo, Jianning; Tian, Xingshan; Soon Chow, Wah; Sun, Zhongyu; Zhang, Taijie; Peng, Shaolin; Peng, Changlian
2015-06-01
To explore replacement control of the invasive weed Ipomoea cairica, we studied the competitive effects of two valuable natives, Pueraria lobata and Paederia scandens, on growth and photosynthetic characteristics of I. cairica, in pot and field experiments. When I. cairica was planted in pots with P. lobata or P. scandens, its total biomass decreased by 68.7% and 45.8%, and its stem length by 33.3% and 34.1%, respectively. The two natives depressed growth of the weed by their strong effects on its photosynthetic characteristics, including suppression of leaf biomass and the abundance of the CO2-fixing enzyme RUBISCO. The field experiment demonstrated that sowing seeds of P. lobata or P. scandens in plots where the weed had been largely cleared produced 11.8-fold or 2.5-fold as much leaf biomass of the two natives, respectively, as the weed. Replacement control by valuable native species is potentially a feasible and sustainable means of suppressing I. cairica.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Mitani, M.; Cianciolo, G.J.; Snyderman, R.
1987-01-01
Purified feline leukemia virus, UV light-inactivated feline leukemia virus, and a synthetic peptide (CKS-17) homologous to a well-conserved region of the transmembrane components of several human and animal retroviruses were each studied for their effect on IgG production by feline peripheral blood lymphocytes. Using a reverse hemolytic plaque assay, both the viable virus and the UV-inactivated feline leukemia virus, but not the CKS-17, activated B lymphocytes to secrete IgG. When staphylococcal protein A, a polyclonal B-cell activator, was used to stimulate IgG synthesis by feline lymphocytes, the viable virus, the UV-inactivated virus, and the CKS-17 peptide each strongly suppressed IgGmore » secretion without compromising viability of the lymphocytes. These finding suggest that the immunosuppressive influences of feline leukemia virus on immunoglobulin synthesis may reside in a conserved portion of the envelope glycoprotein that includes the region homologous to CKS-17.« less
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A new strategy for controlling invasive weeds: selecting valuable native plants to defeat them
Li, Weihua; Luo, Jianning; Tian, Xingshan; Soon Chow, Wah; Sun, Zhongyu; Zhang, Taijie; Peng, Shaolin; Peng, Changlian
2015-01-01
To explore replacement control of the invasive weed Ipomoea cairica, we studied the competitive effects of two valuable natives, Pueraria lobata and Paederia scandens, on growth and photosynthetic characteristics of I. cairica, in pot and field experiments. When I. cairica was planted in pots with P. lobata or P. scandens, its total biomass decreased by 68.7% and 45.8%, and its stem length by 33.3% and 34.1%, respectively. The two natives depressed growth of the weed by their strong effects on its photosynthetic characteristics, including suppression of leaf biomass and the abundance of the CO2-fixing enzyme RUBISCO. The field experiment demonstrated that sowing seeds of P. lobata or P. scandens in plots where the weed had been largely cleared produced 11.8-fold or 2.5-fold as much leaf biomass of the two natives, respectively, as the weed. Replacement control by valuable native species is potentially a feasible and sustainable means of suppressing I. cairica. PMID:26047489
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Abe, I; Umehara, K; Morita, R; Nemoto, K; Degawa, M; Noguchi, H
2001-02-16
The effect of natural and synthetic galloyl esters on glucocorticoid-induced gene expression was evaluated by using rat fibroblast 3Y1 cells stably transfected with a luciferase reporter gene under the transcriptional regulation of the mouse mammary tumor virus promoter. The glucocorticoid-induced gene transcription was strongly suppressed by synthetic alkyl esters; n-dodecyl gallate showed the most potent inhibition (66% inhibition at 10 microM), which was far more potent than that of crude tannic acid. n-Octyl and n-cetyl gallate also showed good inhibition, while gallic acid itself was not so active, suggesting that the presence of hydrophobic side chain is important for the suppressive effect. On the other hand, surprisingly, green tea gallocatechins, (-)-epigallocatechin-3-O-gallate and theasinensin A, potently enhanced the promoter activity (182 and 247% activity at 1 microM, respectively). The regulation of the level of the glucocorticoid-induced gene expression by the antioxidative gallates is of great interest from a therapeutic point of view.
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NASA Astrophysics Data System (ADS)
Chi, Xiaoqin; Yin, Zhenyu; Jin, Jianbin; Li, Hui; Zhou, Jian; Zhao, Zhenghuan; Zhang, Sheng; Zhao, Wenxiu; Xie, Chengrong; Li, Jie; Feng, Min; Lin, Hongyu; Wang, Xiaomin; Gao, Jinhao
2017-11-01
Postoperative recurrence and metastasis are the major problems for the current treatment of hepatocellular carcinomas (HCC) in the clinic, including hepatectomy and liver transplantation. Here, we report that arsentic-loaded nanoparticles (ALNPs) are able to reduce the invasion of HCC cells in vitro, and, more importantly, can strongly suppress the invasion and metastasis of HCC in vivo without adverse side effects. Compared to free drug arsenic trioxide , ALNPs can deliver the drug into cancer cells more efficiently, destroy the structure of microtubules and reduce the aggregation of microfilaments in cell membranes more significantly. Furthermore, our results also reveal that tumor cells in murine blood were reduced remarkably after intravenous injection of ALNPs, indicating that this nano-drug may efficiently kill circulating tumor cells in vivo. In conclusion, our nano-drug ALNPs have great potential for the suppression of metastasis of HCC, which may open up a new avenue for the effective treatment of HCC without metastasis and recurrence.
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A new strategy for controlling invasive weeds: selecting valuable native plants to defeat them.
Li, Weihua; Luo, Jianning; Tian, Xingshan; Soon Chow, Wah; Sun, Zhongyu; Zhang, Taijie; Peng, Shaolin; Peng, Changlian
2015-06-05
To explore replacement control of the invasive weed Ipomoea cairica, we studied the competitive effects of two valuable natives, Pueraria lobata and Paederia scandens, on growth and photosynthetic characteristics of I. cairica, in pot and field experiments. When I. cairica was planted in pots with P. lobata or P. scandens, its total biomass decreased by 68.7% and 45.8%, and its stem length by 33.3% and 34.1%, respectively. The two natives depressed growth of the weed by their strong effects on its photosynthetic characteristics, including suppression of leaf biomass and the abundance of the CO2-fixing enzyme RUBISCO. The field experiment demonstrated that sowing seeds of P. lobata or P. scandens in plots where the weed had been largely cleared produced 11.8-fold or 2.5-fold as much leaf biomass of the two natives, respectively, as the weed. Replacement control by valuable native species is potentially a feasible and sustainable means of suppressing I. cairica.
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Rittling, S R; Wejse, P L; Yagiz, K; Warot, G A; Hui, T
2014-03-04
The integrin-binding protein osteopontin is strongly associated with tumour development, yet is an abundant dietary component as a constituent of human and bovine milk. Therefore, we tested the effect of orally administered osteopontin (o-OPN) on the development of subcutaneous tumours in mice. Bovine milk osteopontin was administered in drinking water to tumour-bearing immune-competent mice. Tumour growth, proliferation, necrosis, apoptosis and blood vessel size and number were measured. Expression of the α₉ integrin was determined. o-OPN suppressed tumour growth, increased the extent of necrosis, and induced formation of abnormally large blood vessels. Anti-OPN reactivity detected in the plasma of OPN-null mice fed OPN suggested that tumour-blocking peptides were absorbed during digestion, but the o-OPN effect was likely distinct from that of an RGD peptide. Expression of the α₉ integrin was detected on both tumour cells and blood vessels. Potential active peptides from the α₉ binding site of OPN were identified by mass spectrometry following in vitro digestion, and injection of these peptides suppressed tumour growth. These results suggest that peptides derived from o-OPN are absorbed and interfere with tumour growth and normal vessel development. o-OPN-derived peptides that target the α₉ integrin are likely involved.
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Kim, Jeong-Mi; Noh, Eun-Mi; Kwon, Kang-Beam; Kim, Jong-Suk; You, Yong-Ouk; Hwang, Jin-Ki; Hwang, Bo-Mi; Kim, Byeong-Soo; Lee, Sung-Hoo; Lee, Seung Jin; Jung, Sung Hoo; Youn, Hyun Jo; Lee, Young-Rae
2012-09-15
Curcumin (diferuloylmethane) is a polyphenol derived from the plant turmeric (Curcuma longa), which is commonly used as a spice. Although anti-carcinogenic, anti-oxidant, anti-inflammation, and anti-angiogenic properties have been reported, the effect of curcumin on breast cancer metastasis is unknown. Matrix metalloproteinase-9 (MMP-9) is a major component in cancer cell invasion. In this study, we investigated the inhibitory effect of curcumin on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced MMP-9 expression and cell invasion and the molecular mechanisms involved in MCF-7 cells. Our results showed that curcumin inhibits TPA-induced MMP-9 expression and cell invasion through suppressing NF-κB and AP-1 activation. Also, curcumin strongly repressed the TPA-induced phosphorylation of p38 and JNK and inhibited TPA-induced translocation of PKCα from the cytosol to the membrane, but did not affect the translocation of PKCδ. These results indicate that curcumin-mediated inhibition of TPA-induced MMP-9 expression and cell invasion involves the suppression of the PKCα, MAPK and NF-κB/AP-1 pathway in MCF-7 cells. Curcumin may have potential value in restricting breast cancer metastasis. Copyright © 2012 Elsevier GmbH. All rights reserved.
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Yamamoto, Shunsuke; Ohta, Noriyuki; Matsumoto, Atsuhiro; Horiguchi, Yu; Koide, Moe; Fujino, Yuji
2016-01-01
Background Haloperidol, a tranquilizing agent, is administered both to treat symptoms of psychotic disorders and to sedate agitated and delirious patients. Notably, haloperidol has been suggested to inhibit the immune response through unknown mechanisms. We hypothesized that the sedative modulates the immune response via NF-κB. Material/Methods Using flow cytometry, we analyzed the effects of haloperidol on expression CD80 and CD86 in RAW 264 cells and in primary macrophages derived from bone marrow. Secretion of interleukin (IL)-1β, IL-6, and IL-12 p40 was measured by enzyme-linked immunosorbent assay. In addition, NF-κB activation was evaluated using a reporter assay based on secretory embryonic alkaline phosphatase. Finally, synthetic antagonists were used to identify the dopamine receptor that mediates the effects of haloperidol. Results Haloperidol inhibited NF-κB activation, and thereby suppressed expression of CD80, as well as secretion of IL-1β, IL-6, and IL-12 p40. CD80 and IL-6 levels were similarly attenuated by a D2-like receptor antagonist, but not by a D1-like receptor antagonist. Conclusions The data strongly suggest that haloperidol inhibits the immune response by suppressing NF-κB signaling via the dopamine D2 receptor. PMID:26842661
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Yamamoto, Shunsuke; Ohta, Noriyuki; Matsumoto, Atsuhiro; Horiguchi, Yu; Koide, Moe; Fujino, Yuji
2016-02-04
BACKGROUND Haloperidol, a tranquilizing agent, is administered both to treat symptoms of psychotic disorders and to sedate agitated and delirious patients. Notably, haloperidol has been suggested to inhibit the immune response through unknown mechanisms. We hypothesized that the sedative modulates the immune response via NF-κB. MATERIAL AND METHODS Using flow cytometry, we analyzed the effects of haloperidol on expression CD80 and CD86 in RAW 264 cells and in primary macrophages derived from bone marrow. Secretion of interleukin (IL)-1β, IL-6, and IL-12 p40 was measured by enzyme-linked immunosorbent assay. In addition, NF-κB activation was evaluated using a reporter assay based on secretory embryonic alkaline phosphatase. Finally, synthetic antagonists were used to identify the dopamine receptor that mediates the effects of haloperidol. RESULTS Haloperidol inhibited NF-κB activation, and thereby suppressed expression of CD80, as well as secretion of IL-1β, IL-6, and IL-12 p40. CD80 and IL-6 levels were similarly attenuated by a D2-like receptor antagonist, but not by a D1-like receptor antagonist. CONCLUSIONS The data strongly suggest that haloperidol inhibits the immune response by suppressing NF-kB signaling via the dopamine D2 receptor.
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Suppression of stochastic pulsation in laser-plasma interaction by smoothing methods
NASA Astrophysics Data System (ADS)
Hora, Heinrich; Aydin, Meral
1992-04-01
The control of the very complex behavior of a plasma with laser interaction by smoothing with induced spatial incoherence or other methods was related to improving the lateral uniformity of the irradiation. While this is important, it is shown from numerical hydrodynamic studies that the very strong temporal pulsation (stuttering) will mostly be suppressed by these smoothing methods too.
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Coffee phenolic phytochemicals suppress colon cancer metastasis by targeting MEK and TOPK
Kang, Nam Joo; Lee, Ki Won; Kim, Bo Hyun; Bode, Ann M.; Lee, Hyo-Jeong; Heo, Yong-Seok; Boardman, Lisa; Limburg, Paul; Lee, Hyong Joo; Dong, Zigang
2011-01-01
Epidemiological studies suggest that coffee consumption reduces the risk of cancers, including colon cancer, but the molecular mechanisms and target(s) underlying the chemopreventive effects of coffee and its active ingredient(s) remain unknown. Based on serving size or daily units, coffee contains larger amounts of phenolic phytochemicals than tea or red wine. Coffee or chlorogenic acid inhibited CT-26 colon cancer cell-induced lung metastasis by blocking phosphorylation of ERKs. Coffee or caffeic acid (CaA) strongly suppressed mitogen-activated MEK1 and TOPK activities and bound directly to either MEK1 or TOPK in an ATP-noncompetitive manner. Coffee or CaA, but not caffeine, inhibited ERKs phosphorylation, AP-1 and NF-κB transactivation and subsequently inhibited TPA-, EGF- and H-Ras-induced neoplastic transformation of JB6 P+ cells. Coffee consumption was also associated with a significant attenuation of ERKs phosphorylation in colon cancer patients. These results suggest that coffee and CaA target MEK1 and TOPK to suppress colon cancer metastasis and neoplastic cell transformation. PMID:21317303
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Feedback amplification of fibrosis through matrix stiffening and COX-2 suppression
Liu, Fei; Mih, Justin D.; Shea, Barry S.; Kho, Alvin T.; Sharif, Asma S.; Tager, Andrew M.
2010-01-01
Tissue stiffening is a hallmark of fibrotic disorders but has traditionally been regarded as an outcome of fibrosis, not a contributing factor to pathogenesis. In this study, we show that fibrosis induced by bleomycin injury in the murine lung locally increases median tissue stiffness sixfold relative to normal lung parenchyma. Across this pathophysiological stiffness range, cultured lung fibroblasts transition from a surprisingly quiescent state to progressive increases in proliferation and matrix synthesis, accompanied by coordinated decreases in matrix proteolytic gene expression. Increasing matrix stiffness strongly suppresses fibroblast expression of COX-2 (cyclooxygenase-2) and synthesis of prostaglandin E2 (PGE2), an autocrine inhibitor of fibrogenesis. Exogenous PGE2 or an agonist of the prostanoid EP2 receptor completely counteracts the proliferative and matrix synthetic effects caused by increased stiffness. Together, these results demonstrate a dominant role for normal tissue compliance, acting in part through autocrine PGE2, in maintaining fibroblast quiescence and reveal a feedback relationship between matrix stiffening, COX-2 suppression, and fibroblast activation that promotes and amplifies progressive fibrosis. PMID:20733059
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Substructure of fuzzy dark matter haloes
NASA Astrophysics Data System (ADS)
Du, Xiaolong; Behrens, Christoph; Niemeyer, Jens C.
2017-02-01
We derive the halo mass function (HMF) for fuzzy dark matter (FDM) by solving the excursion set problem explicitly with a mass-dependent barrier function, which has not been done before. We find that compared to the naive approach of the Sheth-Tormen HMF for FDM, our approach has a higher cutoff mass and the cutoff mass changes less strongly with redshifts. Using merger trees constructed with a modified version of the Lacey & Cole formalism that accounts for suppressed small-scale power and the scale-dependent growth of FDM haloes and the semi-analytic GALACTICUS code, we study the statistics of halo substructure including the effects from dynamical friction and tidal stripping. We find that if the dark matter is a mixture of cold dark matter (CDM) and FDM, there will be a suppression on the halo substructure on small scales which may be able to solve the missing satellites problem faced by the pure CDM model. The suppression becomes stronger with increasing FDM fraction or decreasing FDM mass. Thus, it may be used to constrain the FDM model.
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NASA Astrophysics Data System (ADS)
Sung, Z. H.; Polyanskii, A. A.; Lee, P. J.; Gurevich, A.; Larbalestier, D. C.
2011-03-01
Significant performance degradation of superconducting RF (radio frequency) niobium cavities in high RF field is strongly associated with the breakdown of superconductivity on localized multi-scale surface defects lying within the 40 nm penetration depth. These defects may be on the nanometer scale, like grain boundaries and dislocations or even at the much larger scale of surface roughness and welding pits. By combining multiple superconducting characterization techniques including magneto-optical (MO) imaging and direct transport measurement with non-contact characterization of the surface topology using scanning confocal microscopy, we were able to show clear evidence of suppression of surface superconductivity at chemically treated RF-quality niobium. We found that pinning of vortices along GBs is weaker than pinning of vortices in the grains, which may indicate suppressed superfluid density on GBs. We also directly measured the local magnetic characteristics of BCP-treated Nb sample surface using a micro-Hall sensor in order to further understanding of the effect of surface topological features on the breakdown of superconducting state in RF mode.
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Investigation of Magnetic Reconnection Suppression at Saturn's Magnetopause
NASA Astrophysics Data System (ADS)
Sawyer, R.; Fuselier, S. A.; Mukherjee, J.; Steven, P. M.; Masters, A.
2017-12-01
At Earth, one of the fundamental processes that govern the interaction between the solar wind and the magnetosphere is magnetic reconnection. It remains to be seen how significant a role magnetic reconnection plays in the magnetospheric dynamics of the outer planets. In particular, there may be conditions that cause suppression of reconnection. For fast rotators, like Saturn, the strong co-rotation may be dominant throughout the magnetosphere, out to the magnetopause. These strong internal co-rotational flows may create a shear flow across the magnetopause that may act to suppress reconnection, especially on the dawn flank. Cassini has given us an extraordinary insight into the plasma environment around Saturn. The electron spectrometer (ELS) on the Cassini plasma spectrometer (CAPS) instrument provides data on the plasma density and temperatures as well as electron pitch angle distributions and their associated energies. In this study we examine magnetopause crossing events where heated electrons were observed in the magnetosheath. We use a modified empirical model for the location of the reconnection X-line to show where reconnection may be taking place at Saturn's magnetopause. From these results, we determine if any events considered fall in the predicted suppression region along the dawn flanks.
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Abnormal blueshift of the absorption edge in graphene nanodots
NASA Astrophysics Data System (ADS)
Sheng, Weidong
2018-06-01
In a conventional semiconductor, when the dielectric screening effect is suppressed, the exciton binding energy increases and the corresponding excitonic transition would exhibit a redshift in the spectrum. In this work, I study the optical properties of hexagonal graphene nanodots by using a configuration interaction approach and reveal that the edge of the absorption spectrum shows an abnormal blueshift as the environmental dielectric constant ɛr decreases. The two dominant many-body effects in the nanodot: the quasiparticle and excitonic effects are both found to scale almost linearly with ɛr-1. The former is shown to have a larger proportionality constant and thus accounts for the blueshift of the absorption edge. In contrast to the long-range Coulomb interaction, the on-site Coulomb energy is found to have a negative impact on the bright excitonic states. In the presence of a strong dielectric screening effect, a strong short-range Coulomb interaction is revealed to be responsible for the disintegration of the bright exciton.
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Diverse Effects of Cyclosporine on Hepatitis C Virus Strain Replication
Ishii, Naoto; Watashi, Koichi; Hishiki, Takayuki; Goto, Kaku; Inoue, Daisuke; Hijikata, Makoto; Wakita, Takaji; Kato, Nobuyuki; Shimotohno, Kunitada
2006-01-01
Recently, a production system for infectious particles of hepatitis C virus (HCV) utilizing the genotype 2a JFH1 strain has been developed. This strain has a high capacity for replication in the cells. Cyclosporine (CsA) has a suppressive effect on HCV replication. In this report, we characterize the anti-HCV effect of CsA. We observe that the presence of viral structural proteins does not influence the anti-HCV activity of CsA. Among HCV strains, the replication of genotype 1b replicons was strongly suppressed by treatment with CsA. In contrast, JFH1 replication was less sensitive to CsA and its analog, NIM811. Replication of JFH1 did not require the cellular replication cofactor, cyclophilin B (CyPB). CyPB stimulated the RNA binding activity of NS5B in the genotype 1b replicon but not the genotype 2a JFH1 strain. These findings provide an insight into the mechanisms of diversity governing virus-cell interactions and in the sensitivity of these strains to antiviral agents. PMID:16611911
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NASA Astrophysics Data System (ADS)
Mirzadeh, Mohammad; Bazant, Martin
2017-11-01
Interfacial instabilities are ubiquitous in Fluid Mechanics and have been one of the main the subjects of pattern formation. However, these instabilities could lead to inefficiencies which are undesired in many applications. For instance, viscous fingering results in residual trapping of oil during secondary recovery when a low-viscosity fluid, e.g. water, is used for injection. In their seminal work, Saffman and Taylor showed that the onset of this instability is controlled by the viscosity ratio of the two fluids. However, other physiochemical processes could enhance or suppress viscous fingering. Here we consider the role of salinity effects on the front stability. Our recent theory suggests that viscous fingering could be controlled, and even suppressed, by appropriately injecting electric currents. However, even in the absence of any external currents, strong electrokinetic coupling (present in small pores when the electric double layers overlap) can reduce viscous fingering by increasing the ``effective viscosity'' of the injected fluid. These findings suggest that it might be possible to improve extraction efficiencies by appropriately controlling the salt concentration of the injected fluid.
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Chou, Ruey-Hwang; Hsieh, Shu-Ching; Yu, Yung-Luen; Huang, Min-Hsien; Huang, Yi-Chang; Hsieh, Yi-Hsien
2013-01-01
Fisetin (3,3’,4’,7-tetrahydroxyflavone), a naturally occurring flavonoid, has been reported to inhibit proliferation and induce apoptosis in several cancer types. However, its effect on the anti-metastatic potential of cervical cancer cells remains unclear. In the present study, we found that fisetin inhibits the invasion and migration of cervical cancer cells. The expression and activity of urokinase plasminogen activator (uPA) was significantly suppressed by fisetin in a dose-dependent manner. We also demonstrated that fisetin reduces the phosphorylation of p38 MAPK, but not that of ERK1/2, JNK1/2, or AKT. Addition of a p38 MAPK inhibitor, SB203580, further enhanced the inhibitory effect of fisetin on the expression and activity of uPA and the invasion and motility in cervical cancer cells. Fisetin suppressed the TPA (tetradecanoylphorbol-13-acetate)-induced activation of p38 MAPK and uPA, and inhibited the TPA-enhanced migratory and invasive abilities. Furthermore, the promoter activity of the uPA gene was dramatically repressed by fisetin, which disrupted the nuclear translocation of NF-κB and its binding amount on the promoter of the uPA gene, and these suppressive effects could be further enhanced by SB203580. This study provides strong evidence for the molecular mechanism of fisetin in inhibiting the aggressive phenotypes by repression of uPA via interruption of p38 MAPK-dependent NF-κB signaling pathway in cervical cancer cells and thus contributes insight to the potential of using fisetin as a therapeutic strategy against cervical cancer by inhibiting migration and invasion. PMID:23940799
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Greco, Rita; Li, Zhifang; Sun, Fangxian; Barberis, Claude; Tabart, Michel; Patel, Vinod; Schio, Laurent; Hurley, Raelene; Chen, Bo; Cheng, Hong; Lengauer, Christoph; Pollard, Jack; Watters, James; Garcia-Echeverria, Carlos; Wiederschain, Dmitri; Adrian, Francisco; Zhang, JingXin
2014-01-01
Inhibitors of JAK2 kinase are emerging as an important treatment modality for myeloproliferative neoplasms (MPN). However, similar to other kinase inhibitors, resistance to JAK2 inhibitors may eventually emerge through a variety of mechanisms. Effective drug combination is one way to enhance therapeutic efficacy and combat resistance against JAK2 inhibitors. To identify potential combination partners for JAK2 compounds in MPN cell lines, we performed pooled shRNA screen targeting 5,000 genes in the presence or absence of JAK2 blockade. One of the top hits identified was MYC, an oncogenic transcription factor that is difficult to inhibit directly, but could be targeted by modulation of upstream regulatory elements such as kinases. We demonstrate herein that PIM kinase inhibitors efficiently suppress MYC protein levels in MPN cell lines. Overexpression of MYC restores the viability of PIM inhibitor-treated cells, revealing causal relationship between MYC down-regulation and cell growth inhibition by PIM compounds. Combination of various PIM inhibitors with a JAK2 inhibitor results in significant synergistic growth inhibition of multiple MPN cancer cell lines and induction of apoptosis. Mechanistic studies revealed strong downregulation of phosphorylated forms of S6 and 4EBP1 by JAK2/PIM inhibitor combination treatment. Finally, such combination was effective in eradicating in vitro JAK2 inhibitor-resistant MPN clones, where MYC is consistently up-regulated. These findings demonstrate that simultaneous suppression of JAK2 and PIM kinase activity by small molecule inhibitors is more effective than either agent alone in suppressing MPN cell growth. Our data suggest that JAK2 and PIM combination might warrant further investigation for the treatment of JAK2-driven hematologic malignancies. PMID:24830942
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Dong, Ying; Gao, Guirong; Fan, Hongyan; Li, Shengxian; Li, Xuhang; Liu, Wei
2015-01-01
Activation of Liver X receptors (LXRs), key transcriptional regulators of glucose metabolism, normalizes glycemia and improves insulin sensitivity in rodent models with insulin resistance. However, the molecular mechanism is unclear. This study is aimed to elucidate the mechanism of LXRs-mediated liver glucose metabolic regulation in vitro and in vivo. Db/db mice were used as an in vivo model of diabetes; palmitate (PA)-stimulated HepG2 cells were used as an in vitro cell model with impairment of insulin signaling. TO901317 (TO) was chosen as the LXRs agonist. We demonstrated that TO treatment for 14 days potently improved the hepatic glucose metabolism in db/db mice, including fasting blood glucose, fasting insulin level, and HOMA-IR. TO had no effect on the glucose metabolism in normal WT mice. TO-mediated activation of hepatic LXRs led to strong inhibition of ROS production accompanied by inactivation of JNK pathway and re-activation of Akt pathway. TO also suppressed the expression of gluconeogenic genes such as PEPCK and G-6-pase in db/db mice, but not in WT mice. In HepG2 cells, TO almost completely restored PA-induced Akt inactivation, and suppressed PA-stimulated ROS production and JNK activation. Interestingly, basal level of ROS was also inhibited by TO in HepG2 cells. TO significantly inhibited PA-stimulated expressions of gluconeogenic genes. Finally, we found that anti-oxidative genes, such as Nrf2, were up-regulated after LXRs activation by TO. These results strongly support the notion that activation of LXRs is critical in suppression of liver gluconeogenesis and improvement of insulin sensitivity in diabetic individuals. At molecular levels, the mode of action appears to be as fellows: under diabetic condition, ROS production is increased, JNK is activated, and Akt activity is inhibited; TO-mediated LXR activation potently inhibits ROS production, increases anti-oxidative gene expressions, suppresses JNK activation, and restores Akt activity. Our data provide new evidence to support LXRs as promising therapeutic targets for anti-diabetic drug development.
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Anisotropic stress inhibits crystallization in Cu-Zr glass-forming liquids
NASA Astrophysics Data System (ADS)
Pang, H. H.; Bi, Q. L.; Huang, H. S.; Lü, Y. J.
2017-12-01
Liquids attain a metastable state without crystallizing by cooling rapidly to a given temperature below the melting point. With increasing supercooling, the nucleation rate would show an increase based on the prediction of the classical nucleation theory. It is generally thought that the nucleation rate will reach the maximum upon approaching the glass transition temperature, Tg, for glass-forming liquids. We report that there exists a supercooled region above Tg in which the crystallization has actually been severely suppressed. Our molecular dynamics simulations show that the growth of embryos in the supercooled Cu60Zr40 melt is subjected to a strong anisotropic stress associated with the dynamic heterogeneity. Its long-range effect drives the embryo to grow into a ramified morphology so that the interface energy dominates over the embryo growth, leading to the suppression of nucleation.
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Sugathan, Aarathi; Biagioli, Marta; Golzio, Christelle; Erdin, Serkan; Blumenthal, Ian; Manavalan, Poornima; Ragavendran, Ashok; Brand, Harrison; Lucente, Diane; Miles, Judith; Sheridan, Steven D.; Stortchevoi, Alexei; Kellis, Manolis; Haggarty, Stephen J.; Katsanis, Nicholas; Gusella, James F.; Talkowski, Michael E.
2014-01-01
Truncating mutations of chromodomain helicase DNA-binding protein 8 (CHD8), and of many other genes with diverse functions, are strong-effect risk factors for autism spectrum disorder (ASD), suggesting multiple mechanisms of pathogenesis. We explored the transcriptional networks that CHD8 regulates in neural progenitor cells (NPCs) by reducing its expression and then integrating transcriptome sequencing (RNA sequencing) with genome-wide CHD8 binding (ChIP sequencing). Suppressing CHD8 to levels comparable with the loss of a single allele caused altered expression of 1,756 genes, 64.9% of which were up-regulated. CHD8 showed widespread binding to chromatin, with 7,324 replicated sites that marked 5,658 genes. Integration of these data suggests that a limited array of direct regulatory effects of CHD8 produced a much larger network of secondary expression changes. Genes indirectly down-regulated (i.e., without CHD8-binding sites) reflect pathways involved in brain development, including synapse formation, neuron differentiation, cell adhesion, and axon guidance, whereas CHD8-bound genes are strongly associated with chromatin modification and transcriptional regulation. Genes associated with ASD were strongly enriched among indirectly down-regulated loci (P < 10−8) and CHD8-bound genes (P = 0.0043), which align with previously identified coexpression modules during fetal development. We also find an intriguing enrichment of cancer-related gene sets among CHD8-bound genes (P < 10−10). In vivo suppression of chd8 in zebrafish produced macrocephaly comparable to that of humans with inactivating mutations. These data indicate that heterozygous disruption of CHD8 precipitates a network of gene-expression changes involved in neurodevelopmental pathways in which many ASD-associated genes may converge on shared mechanisms of pathogenesis. PMID:25294932
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Obia, Alfred; Cornelissen, Gerard; Mulder, Jan; Dörsch, Peter
2015-01-01
Biochar (BC) application to soil suppresses emission of nitrous- (N2O) and nitric oxide (NO), but the mechanisms are unclear. One of the most prominent features of BC is its alkalizing effect in soils, which may affect denitrification and its product stoichiometry directly or indirectly. We conducted laboratory experiments with anoxic slurries of acid Acrisols from Indonesia and Zambia and two contrasting BCs produced locally from rice husk and cacao shell. Dose-dependent responses of denitrification and gaseous products (NO, N2O and N2) were assessed by high-resolution gas kinetics and related to the alkalizing effect of the BCs. To delineate the pH effect from other BC effects, we removed part of the alkalinity by leaching the BCs with water and acid prior to incubation. Uncharred cacao shell and sodium hydroxide (NaOH) were also included in the study. The untreated BCs suppressed N2O and NO and increased N2 production during denitrification, irrespective of the effect on denitrification rate. The extent of N2O and NO suppression was dose-dependent and increased with the alkalizing effect of the two BC types, which was strongest for cacao shell BC. Acid leaching of BC, which decreased its alkalizing effect, reduced or eliminated the ability of BC to suppress N2O and NO net production. Just like untreated BCs, NaOH reduced net production of N2O and NO while increasing that of N2. This confirms the importance of altered soil pH for denitrification product stoichiometry. Addition of uncharred cacao shell stimulated denitrification strongly due to availability of labile carbon but only minor effects on the product stoichiometry of denitrification were found, in accordance with its modest effect on soil pH. Our study indicates that stimulation of denitrification was mainly due to increases in labile carbon whereas change in product stoichiometry was mainly due to a change in soil pH. PMID:26397367
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Obia, Alfred; Cornelissen, Gerard; Mulder, Jan; Dörsch, Peter
2015-01-01
Biochar (BC) application to soil suppresses emission of nitrous- (N2O) and nitric oxide (NO), but the mechanisms are unclear. One of the most prominent features of BC is its alkalizing effect in soils, which may affect denitrification and its product stoichiometry directly or indirectly. We conducted laboratory experiments with anoxic slurries of acid Acrisols from Indonesia and Zambia and two contrasting BCs produced locally from rice husk and cacao shell. Dose-dependent responses of denitrification and gaseous products (NO, N2O and N2) were assessed by high-resolution gas kinetics and related to the alkalizing effect of the BCs. To delineate the pH effect from other BC effects, we removed part of the alkalinity by leaching the BCs with water and acid prior to incubation. Uncharred cacao shell and sodium hydroxide (NaOH) were also included in the study. The untreated BCs suppressed N2O and NO and increased N2 production during denitrification, irrespective of the effect on denitrification rate. The extent of N2O and NO suppression was dose-dependent and increased with the alkalizing effect of the two BC types, which was strongest for cacao shell BC. Acid leaching of BC, which decreased its alkalizing effect, reduced or eliminated the ability of BC to suppress N2O and NO net production. Just like untreated BCs, NaOH reduced net production of N2O and NO while increasing that of N2. This confirms the importance of altered soil pH for denitrification product stoichiometry. Addition of uncharred cacao shell stimulated denitrification strongly due to availability of labile carbon but only minor effects on the product stoichiometry of denitrification were found, in accordance with its modest effect on soil pH. Our study indicates that stimulation of denitrification was mainly due to increases in labile carbon whereas change in product stoichiometry was mainly due to a change in soil pH.
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Consequences of omnivory for trophic interactions on a salt marsh shrub.
Ho, Chuan-Kai; Pennings, Steven C
2008-06-01
Although omnivory is common in nature, its impact on trophic interactions is variable. Predicting the food web consequences of omnivory is complicated because omnivores can simultaneously produce conflicting direct and indirect effects on the same species or trophic level. We conducted field and laboratory experiments testing the top-down impacts of an omnivorous salt marsh crab, Armases cinereum, on the shrub Iva frutescens and its herbivorous and predatory arthropod fauna. Armases is a "true omnivore," consuming both Iva and arthropods living on Iva. We hypothesized that Armases would benefit Iva through a top-down trophic cascade, and that this benefit would be stronger than the direct negative effect of Armases on Iva. A field experiment on Sapelo Island, Georgia (USA), supported this hypothesis. Although Armases suppressed predators (spiders), it also suppressed herbivores (aphids), and benefited Iva, increasing leaf number, and reducing the proportion of dead shoots. A one-month laboratory experiment, focusing on the most common species in the food web, also supported this hypothesis. Armases strongly suppressed aphids and consumed fewer Iva leaves if aphids were available as an alternate diet. Armases gained more body mass if they could feed on aphids as well as on Iva. Although Armases had a negative effect on Iva when aphids were not present, Armases benefited Iva if aphids were present, because Armases controlled aphid populations, releasing Iva from herbivory. Although Armases is an omnivore, it produced strong top-down forces and a trophic cascade because it fed preferentially on herbivores rather than plants when both were available. At the same time, the ability of Armases to subsist on a plant diet allows it to persist in the food web when animal food is not available. Because omnivores feed on multiple trophic levels, their effects on food webs may differ from those predicted by standard trophic models that assume that each species feeds only on a single trophic level. To better understand the complexity of real food webs, the variable feeding habits and feeding preferences of different omnivorous species must be taken into consideration.
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Role of many-body effects in the coherent dynamics of excitons in low-temperature-grown GaAs
DOE Office of Scientific and Technical Information (OSTI.GOV)
Webber, D.; Hacquebard, L.; Hall, K. C.
2015-10-05
Femtosecond four-wave mixing experiments on low-temperature-grown (LT-) GaAs indicate a polarization-dependent nonlinear optical response at the exciton, which we attribute to Coulomb-mediated coupling between excitons and electron-hole pairs simultaneously excited by the broad-bandwidth laser pulses. Strong suppression of the exciton response through screening by carriers injected by a third pump pulse was observed, an effect that is transient due to rapid carrier trapping. Our findings highlight the need to account for the complex interplay of disorder and many-body effects in the design of ultrafast optoelectronic devices using this material.
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Weak beacon detection for air-to-ground optical wireless link establishment.
Han, Yaoqiang; Dang, Anhong; Tang, Junxiong; Guo, Hong
2010-02-01
In an air-to-ground free-space optical communication system, strong background interference seriously affects the beacon detection, which makes it difficult to establish the optical link. In this paper, we propose a correlation beacon detection scheme under strong background interference conditions. As opposed to traditional beacon detection schemes, the beacon is modulated by an m-sequence at the transmitting terminal with a digital differential matched filter (DDMF) array introduced at the receiving end to detect the modulated beacon. This scheme is capable of suppressing both strong interference and noise by correlation reception of the received image sequence. In addition, the DDMF array enables each pixel of the image sensor to have its own DDMF of the same structure to process its received image sequence in parallel, thus it makes fast beacon detection possible. Theoretical analysis and an outdoor experiment have been demonstrated and show that the proposed scheme can realize fast and effective beacon detection under strong background interference conditions. Consequently, the required beacon transmission power can also be reduced dramatically.
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De Vitis, Stefania; Sonia Treglia, Antonella; Ulianich, Luca; Turco, Stefano; Terrazzano, Giuseppe; Lombardi, Angela; Miele, Claudia; Garbi, Corrado; Beguinot, Francesco; Di Jeso, Bruno
2011-02-01
Activation of the Ras-Raf-extracellular signal-regulated kinase (ERK) pathway causes not only proliferation and suppression of apoptosis but also the antioncogenic response of senescence. How these contrasting effects are reconciled to achieve cell transformation and cancer formation is poorly understood. In a system of two-step carcinogenesis (dedifferentiated PC EIA, transformed PC EIA-polyoma-middle T [PC EIA + Py] and PC EIA-v-raf [PC EIA + raf] cells], v-raf cooperated with EIA by virtue of a strong prosurvival effect, not elicited by Py-middle T, evident toward serum-deprivation-and H(2)O(2)-induced apoptosis. Apoptosis was detected by DNA fragmentation and annexin V staining. The prosurvival function of v-raf was, in part, mitogen-activated protein kinase/ERK kinase (MEK)-dependent, as shown by pharmacological MEK inhibition. The MEK-dependent antiapoptotic effect of v-raf was exerted despite a lower level of P-ERK1/2 in EIA + raf cells with respect to EIA + Py/EIA cells, which was dependent on a high tyrosine phosphatase activity, as shown by orthovanadate blockade. An ERK1/2 tyrosine phosphatase was likely involved. The high tyrosine phosphatase activity was instrumental to the complete suppression of senescence, detected by β-galactosidase activity, because tyrosine phosphatase blockade induced senescence in EIA + raf but not in EIA + Py cells. High tyrosine phosphatase activity and evasion from senescence were confirmed in an anaplastic thyroid cancer cell line. Therefore, besides EIA, EIA + raf cells suppress senescence through a new mechanism, namely, phosphatase-mediated P-ERK1/2 inhibition, but, paradoxically, retain the oncogenic effects of the Raf-ERK pathway. We propose that the survival effect of Raf is not a function of absolute P-ERK1/2 levels at a given time but is rather dynamically dependent on greater variations after an apoptotic stimulus.
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Icaritin Synergistically Enhances the Radiosensitivity of 4T1 Breast Cancer Cells
Lv, Wenlong; Zhang, Mei; Chen, Chun; Yang, Shanmin; Li, Shan; Zhang, Lurong; Han, Deping; Zhang, Weijian
2013-01-01
Icaritin (ICT) is a hydrolytic form of icariin isolated from plants of the genus Epimedium. This study was to investigate the radiosensitization effect of icaritin and its possible underlying mechanism using murine 4T1 breast cancer cells. The combination of Icaritin at 3 µM or 6 µM with 6 or 8 Gy of ionizing radiation (IR) in the clonogenic assay yielded an ER (enhancement ratio) of 1.18 or 1.28, CI (combination index) of 0.38 or 0.19 and DRI (dose reducing index) of 2.51 or 5.07, respectively. These strongly suggest that Icaritin exerted a synergistic killing (?) effect with radiation on the tumor cells. This effect might relate with bioactivities of ICT: 1) exert an anti-proliferative effect in a dose- and time-dependent manner, which is different from IR killing effect but likely work together with the IR effect; 2) suppress the IR-induced activation of two survival paths, ERK1/2 and AKT; 3) induce the G2/M blockage, enhancing IR killing effect; and 4) synergize with IR to enhance cell apoptosis. In addition, ICT suppressed angiogenesis in chick embryo chorioallantoic membrane (CAM) assay. Taken together, ICT is a new radiosensitizer and can enhance anti-cancer effect of IR or other therapies. PMID:23977023
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GNOSIS: The First Fiber Bragg Grating-based OH Suppression Unit
NASA Astrophysics Data System (ADS)
Trinh, Christopher; Ellis, S. C.; Bland-Hawthorn, J.; Lawrence, J. S.; Horton, A. J.; Leon-Saval, S. G.; Shortridge, K.; Bryant, J.; Case, S.; Colless, M.; Couch, W.; Freeman, K. C.; Löhmannsröben, H.; Gers, L.; Glazebrook, K.; Haynes, R.; Lee, S.; O'Byrne, J.; Miziarski, S.; Roth, M. M.; Schmidt, B.; Tinney, C. G.; Zheng, J.
2013-01-01
The sky background is over 1000 times brighter in the near-infrared (NIR) than in the visible placing severe limitations on our ability to study the redshifted light from the distant objects formed in the early Universe from the ground. It is well-known that 98% of the NIR background comes from the forest of bright and highly variable emission lines of atmospheric hydroxyl (OH) molecules. Unfortunately, astronomers have been unable to effectively remove this background from their data. We present the first OH suppression unit, GNOSIS, to utilize fiber Bragg gratings (FBGs). Simple FBGs are optical fibers with a periodic refractive index modulation imprinted within the fiber core, which induces a strong reflection in a narrow 0.2 nm) stopband. GNOSIS utilizes “OH suppression fibers” with a complex aperiodic refractive index modulation capable of removing the 103 brightest OH doublets between 1470 and 1700 nm by up 30 dB before dispersion and in a manner purely dependent on wavelength. The OH suppression fibers have high throughput 60%) and over 90% of the H band is available for spectroscopy. OH suppression units like GNOSIS may be utilized with any NIR telescope and spectrograph combination, but we commissioned GNOSIS at the 3.9-meter Anglo-Australian Telescope with the IRIS2 spectrograph for our first demonstration. Commissioning reveals excellent suppression performance. Approximately 78% of the OH lines were suppressed at the target level or greater. GNOSIS reduces the integrated background between 1500 and 1700 nm by a factor of ~ 9 but the signal-to-noise ratio is about the same as standard long-slit IRIS2 observations due to retrofitting to an un-optimized spectrograph. Nevertheless, if paired with a fiber-optimized spectrograph FBG OH suppression technology shows great promise for high sensitivity NIR spectroscopy at moderate to low resolutions from the ground.
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Suppressive mechanisms in visual motion processing: from perception to intelligence
Tadin, Duje
2015-01-01
Perception operates on an immense amount of incoming information that greatly exceeds the brain's processing capacity. Because of this fundamental limitation, the ability to suppress irrelevant information is a key determinant of perceptual efficiency. Here, I will review a series of studies investigating suppressive mechanisms in visual motion processing, namely perceptual suppression of large, background-like motions. These spatial suppression mechanisms are adaptive, operating only when sensory inputs are sufficiently robust to guarantee visibility. Converging correlational and causal evidence links these behavioral results with inhibitory center-surround mechanisms, namely those in cortical area MT. Spatial suppression is abnormally weak in several special populations, including the elderly and those with schizophrenia—a deficit that is evidenced by better-than-normal direction discriminations of large moving stimuli. Theoretical work shows that this abnormal weakening of spatial suppression should result in motion segregation deficits, but direct behavioral support of this hypothesis is lacking. Finally, I will argue that the ability to suppress information is a fundamental neural process that applies not only to perception but also to cognition in general. Supporting this argument, I will discuss recent research that shows individual differences in spatial suppression of motion signals strongly predict individual variations in IQ scores. PMID:26299386
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Drift wave stabilized by an additional streaming ion or plasma population
NASA Astrophysics Data System (ADS)
Bashir, M. F.; Vranjes, J.
2015-03-01
It is shown that the universally unstable kinetic drift wave in an electron-ion plasma can very effectively be suppressed by adding an extra flowing ion (or plasma) population. The effect of the flow of the added ions is essential, their response is of the type (vp h-vf 0) exp[-(vph-vf 0) 2] , where vf 0 is the flow speed and vp h is the phase speed parallel to the magnetic field vector. The damping is strong and it is mainly due to this ion exponential term, and this remains so for vf 0
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Drift wave stabilized by an additional streaming ion or plasma population.
Bashir, M F; Vranjes, J
2015-03-01
It is shown that the universally unstable kinetic drift wave in an electron-ion plasma can very effectively be suppressed by adding an extra flowing ion (or plasma) population. The effect of the flow of the added ions is essential, their response is of the type (vph-vf0)exp[-(vph-vf0)2], where vf0 is the flow speed and vph is the phase speed parallel to the magnetic field vector. The damping is strong and it is mainly due to this ion exponential term, and this remains so for vf0
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Application of 3A molecular sieve layer in dye-sensitized solar cells
DOE Office of Scientific and Technical Information (OSTI.GOV)
Yan, Yuan; Wang, Jinzhong, E-mail: jinzhong-wang@hit.edu.cn, E-mail: qingjiang.yu@hit.edu.cn; Yu, Qingjiang, E-mail: jinzhong-wang@hit.edu.cn, E-mail: qingjiang.yu@hit.edu.cn
2014-08-25
3A molecular sieve layer was used as dehydration and electronic-insulation layer on the TiO{sub 2} electrode of dye-sensitized solar cells. This layer diminished the effect of water in electrolyte efficiently and enhanced the performance of cells. The conversion efficiency increased from 9.58% to 10.2%. The good moisture resistance of cells was attributed to the three-dimensional interconnecting structure of 3A molecular sieve with strong adsorption of water molecule. While the performance enhancement benefited from the suppression of the charge recombination of electronic-insulation layer and scattering effect of large particles.
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Probing the strongly driven spin-boson model in a superconducting quantum circuit.
Magazzù, L; Forn-Díaz, P; Belyansky, R; Orgiazzi, J-L; Yurtalan, M A; Otto, M R; Lupascu, A; Wilson, C M; Grifoni, M
2018-04-11
Quantum two-level systems interacting with the surroundings are ubiquitous in nature. The interaction suppresses quantum coherence and forces the system towards a steady state. Such dissipative processes are captured by the paradigmatic spin-boson model, describing a two-state particle, the "spin", interacting with an environment formed by harmonic oscillators. A fundamental question to date is to what extent intense coherent driving impacts a strongly dissipative system. Here we investigate experimentally and theoretically a superconducting qubit strongly coupled to an electromagnetic environment and subjected to a coherent drive. This setup realizes the driven Ohmic spin-boson model. We show that the drive reinforces environmental suppression of quantum coherence, and that a coherent-to-incoherent transition can be achieved by tuning the drive amplitude. An out-of-equilibrium detailed balance relation is demonstrated. These results advance fundamental understanding of open quantum systems and bear potential for the design of entangled light-matter states.
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Path suppression of strongly collapsing bubbles at finite and low Reynolds numbers.
Rechiman, Ludmila M; Dellavale, Damián; Bonetto, Fabián J
2013-06-01
We study, numerically and experimentally, three different methods to suppress the trajectories of strongly collapsing and sonoluminescent bubbles in a highly viscous sulfuric acid solution. A new numerical scheme based on the window method is proposed to account for the history force acting on a spherical bubble with variable radius. We could quantify the history force, which is not negligible in comparison with the primary Bjerknes force in this type of problem, and results are in agreement with the classical primary Bjerknes force trapping threshold analysis. Moreover, the present numerical implementation reproduces the spatial behavior associated with the positional and path instability of sonoluminescent argon bubbles in strongly gassed and highly degassed sulfuric acid solutions. Finally, the model allows us to demonstrate that spatially stationary bubbles driven by biharmonic excitation could be obtained with a different mode from the one used in previous reported experiments.
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Large velocity dispersion of molecular gas in bars of strongly barred galaxies NGC 1300 and NGC 5383
NASA Astrophysics Data System (ADS)
Maeda, Fumiya; Ohta, Kouji; Fujimoto, Yusuke; Habe, Asao; Baba, Junichi
2018-06-01
We carried out ^{12}CO(J = 1-0) observations toward bar and arm regions of the strongly barred galaxies NGC 1300 and NGC 5383 with the Nobeyama 45 m radio telescope (beam size of 1-2 kpc in the galaxies). The aim of the observations is to qualitatively examine a new scenario for the suppression of star formation in bars based on recent high-resolution numerical simulations: higher speed collisions between molecular clouds in the bar region compared with the arm region suppress the massive star formation. CO emissions were detected from all the regions, indicating the presence of molecular gases in the strong bars without associating clear H II regions. In both galaxies, the velocity width of the CO line profile tends to be larger in the bar region than in the arm region, which is qualitatively consistent with the new scenario.
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Lamsal, Kabir; Kim, Sang Woo; Kim, Yun Seok
2012-01-01
In vitro and greenhouse screening of seven rhizobacterial isolates, AB05, AB10, AB11, AB12, AB14, AB15 and AB17, was conducted to investigate the plant growth promoting activities and inhibition against anthracnose caused by Colletotrichum acutatum in pepper. According to identification based on 16S rDNA sequencing, the majority of the isolates are members of Bacillus and a single isolate belongs to the genus Paenibacillus. All seven bacterial isolates were capable of inhibiting C. acutatum to various degrees. The results primarily showed that antibiotic substances produced by the selected bacteria were effective and resulted in strong antifungal activity against the fungi. However, isolate AB15 was the most effective bacterial strain, with the potential to suppress more than 50% mycelial growth of C. acutatum in vitro. Moreover, antibiotics from Paenibacillus polymyxa (AB15) and volatile compounds from Bacillus subtilis (AB14) exerted efficient antagonistic activity against the pathogens in a dual culture assay. In vivo suppression activity of selected bacteria was also analyzed in a greenhouse with the reference to their prominent in vitro antagonism efficacy. Induced systemic resistance in pepper against C. acutatum was also observed under greenhouse conditions. Where, isolate AB15 was found to be the most effective bacterial strain at suppressing pepper anthracnose under greenhouse conditions. Moreover, four isolates, AB10, AB12, AB15, and AB17, were identified as the most effective growth promoting bacteria under greenhouse conditions, with AB17 inducing the greatest enhancement of pepper growth. PMID:23323049
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Using nonequilibrium dynamics to probe competing orders in a Mott-Peierls system
Wang, Y.; Moritz, B.; Chen, C. -C.; ...
2016-02-24
Competition between ordered phases, and their associated phase transitions, are significant in the study of strongly correlated systems. Here, we examine one aspect, the nonequilibrium dynamics of a photoexcited Mott-Peierls system, using an effective Peierls-Hubbard model and exact diagonalization. Near a transition where spin and charge become strongly intertwined, we observe antiphase dynamics and a coupling-strength-dependent suppression or enhancement in the static structure factors. The renormalized bosonic excitations coupled to a particular photoexcited electron can be extracted, which provides an approach for characterizing the underlying bosonic modes. The results from this analysis for different electronic momenta show an uneven softeningmore » due to a stronger coupling near k F. As a result, this behavior reflects the strong link between the fermionic momenta, the coupling vertices, and ultimately, the bosonic susceptibilities when multiple phases compete for the ground state of the system.« less
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Noise switching at a dynamical critical point in a cavity-conductor hybrid
NASA Astrophysics Data System (ADS)
Armour, Andrew D.; Kubala, Björn; Ankerhold, Joachim
2017-12-01
Coupling a mesoscopic conductor to a microwave cavity can lead to fascinating feedback effects which generate strong correlations between the dynamics of photons and charges. We explore the connection between cavity dynamics and charge transport in a model system consisting of a voltage-biased Josephson junction embedded in a high-Q cavity, focusing on the behavior as the system is tuned through a dynamical critical point. On one side of the critical point the noise is strongly suppressed, signaling the existence of a regime of highly coherent transport, but on the other side it switches abruptly to a much larger value. Using a semiclassical approach we show that this behavior arises because of the strongly nonlinear cavity drive generated by the Cooper pairs. We also uncover an equivalence between charge and photonic current noise in the system which opens up a route to detecting the critical behavior through straightforward microwave measurements.
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Arbuscular mycorrhizal fungi alter the competitive hierarchy among old-field plant species.
Stanescu, Sabina; Maherali, Hafiz
2017-02-01
Inoculation with arbuscular mycorrhizal (AM) fungi is known to increase the species diversity of plant communities. One mechanism that can increase the likelihood of species co-existence, and thus species diversity, is a trade-off between competitive ability and the magnitude of plant growth response to AM fungal inoculation. By suppressing the growth of strong competitors while simultaneously enhancing the growth of weak competitors, this trade-off would cause the competitive hierarchy to be less pronounced in soil inoculated with AM fungi relative to non-inoculated conditions. To test whether such a trade-off exists, we quantified competitive abilities and mycorrhizal growth response (MGR) among 21 species that co-occur in old fields in southern Ontario. Competitive ability was determined by calculating competitive effect (CE), or the degree to which each species suppressed the biomass of a common phytometer species, Plantago lanceolata. Higher CE values represent stronger competitive ability. Old-field species varied in their ability to suppress the biomass of the phytometer and MGR was generally positive. There was a statistically significant negative correlation between CE in non-inoculated soil and MGR (r = -0.49, P = 0.02). In addition, variance in CE was 73% lower in soil inoculated with AM fungi compared to non-inoculated soil (P = 0.0023). These findings support the hypothesis that AM fungi weaken strong competitors while enhancing the performance of weak competitors. Because this trade-off compressed the competitive hierarchy among old-field species in soil inoculated with AM fungi, it may be a mechanism by which mycorrhizal fungi enhance species evenness and diversity.
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Runaway electrons and mitigation studies in MST tokamak plasmas
NASA Astrophysics Data System (ADS)
Goetz, J. A.; Chapman, B. E.; Almagri, A. F.; Cornille, B. S.; Dubois, A.; McCollam, K. J.; Munaretto, S.; Sovinec, C. R.
2016-10-01
Studies of runaway electrons generated in low-density MST tokamak plasmas are being undertaken. The plasmas have Bt <= 0.14 T, Ip <= 50 kA, q (a) = 2.2 , and an electron density and temperature of about 5 ×1017m-3 and 150 eV. Runaway electrons are detected via x-ray bremsstrahlung emission. The density and electric field thresholds for production and suppression have been previously explored with variations in gas puffing for density control. Runaway electrons are now being probed with resonant magnetic perturbations (RMP's). An m = 3 RMP strongly suppresses the runaway electrons and initial NIMROD modeling shows that this may be due to degradation of flux surfaces. The RMP is produced by a poloidal array of 32 saddle coils at the narrow vertical insulated cut in MST's thick conducting shell, with each RMP having a single m but a broad n spectrum. While a sufficiently strong m = 3 RMP suppresses the runaway electrons, an RMP with m = 1 and comparable amplitude has little effect. The impact of the RMP's on the magnetic topology of these plasmas is being studied with the nonlinear MHD code NIMROD. With an m = 3 RMP, stochasticity is introduced in the outer third of the plasma but no such flux surface degradation is observed with an m = 1 RMP. NIMROD also predicts regularly occurring MHD activity similar to that observed in the experiment. These studies have also been done in q (a) = 2.7 plasmas and analysis and modeling is ongoing. This work supported by USDoE.
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Sex steroids and variants of gender identity.
Meyer-Bahlburg, Heino F L
2013-09-01
This article summarizes for the practicing endocrinologist the current literature on the psychobiology of the development of gender identity and its variants in individuals with disorders of sex development (DSD) or with non-DSD transgenderism. Gender reassignment remains the treatment of choice for strong and persistent gender dysphoria in both categories, but more research is needed on the short-term and long-term effects of puberty-suppressing medications and cross-sex hormones on brain and behavior. Copyright © 2013 Elsevier Inc. All rights reserved.
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Theory of disordered unconventional superconductors
DOE Office of Scientific and Technical Information (OSTI.GOV)
Keles, A.; Andreev, A. V.; Spivak, B. Z., E-mail: spivak@uw.edu
In contrast to conventional s-wave superconductivity, unconventional (e.g., p- or d-wave) superconductivity is strongly suppressed even by relatively weak disorder. Upon approaching the superconductormetal transition, the order parameter amplitude becomes increasingly inhomogeneous, leading to effective granularity and a phase ordering transition described by the Mattis model of spin glasses. One consequence of this is that at sufficiently low temperatures, between the clean unconventional superconducting and the diffusive metallic phases, there is necessarily an intermediate superconducting phase that exhibits s-wave symmetry on macroscopic scales.
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Evolution of ferromagnetism in charge ordered manganite: An effect of external pressure
NASA Astrophysics Data System (ADS)
Dash, S.; Pradhan, M. K.; Rao, T. Lakshmana
2018-05-01
Detailed magnetic measurements of the Pr0.75Na0.25MnO3 polycrystalline sample have been carried out under external hydrostatic pressure upto 10kbar. Pressure strongly suppresses the first order magnetic transition, while thermal hysteresis narrows down progressively and then disappears with increase in pressure. The significant enhancement of the field cooled magnetization value at different pressures is due to the antiferromagnetic to ferromagnetic transformation, while ruling out any contribution from the domain alignment within the ferromagnetic phase.
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Feigel'man, M V; Skvortsov, M A
2012-10-05
In disordered superconductors, the local pairing field fluctuates in space, leading to the smearing of the BCS peak in the density of states and the appearance of the subgap tail states. We analyze the universal mesoscopic contributions to these effects and show that they are enhanced by the Coulomb repulsion. In the vicinity of the quantum critical point, where superconductivity is suppressed by the "fermionic mechanism," strong smearing of the peak due to mesoscopic fluctuations is predicted.
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Yang, Woo Seok; Ratan, Zubair Ahmed; Kim, Gihyeon; Lee, Yunmi; Kim, Mi-Yeon; Kim, Jong-Hoon; Cho, Jae Youl
2015-01-01
The Cordyceps species has been a good source of compounds with anticancer and anti-inflammatory activities. Recently, we reported a novel compound (4-isopropyl-2,6-bis(1-phenylethyl)phenol, KTH-13) with anticancer activity isolated from Cordyceps bassiana and created several derivatives to increase its pharmacological activity. In this study, we tested one of the KTH-013 derivatives, 4-isopropyl-2,6-bis(1-phenylethyl)aniline 1 (KTH-13-AD1), with regard to anti-inflammatory activity under macrophage-mediated inflammatory conditions. KTH-13-AD1 clearly suppressed the production of nitric oxide (NO) and reactive oxygen species (ROS) in lipopolysaccharide (LPS) and sodium nitroprusside- (SNP-) treated macrophage-like cells (RAW264.7 cells). Similarly, this compound also reduced mRNA expression of inducible NO synthase (iNOS) and tumor necrosis factor-α (TNF-α), as analyzed by RT-PCR and real-time PCR. Interestingly, KTH-13-AD1 strongly diminished NF-κB-mediated luciferase activities and nuclear translocation of NF-κB family proteins. In accordance, KTH-13-AD1 suppressed the upstream signaling pathway of NF-κB activation, including IκBα, IKKα/β, AKT, p85/PI3K, and Src in a time- and dose-dependent manner. The autophosphorylation of Src and NF-κB observed during the overexpression of Src was also suppressed by KTH-13-AD1. These results strongly suggest that KTH-13-AD1 has strong anti-inflammatory features mediated by suppression of the Src/NF-κB regulatory loop. PMID:26819495
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Kuenzel, Heike E; Steiger, Axel; Held, Katja; Antonijevic, Irina A; Frieboes, Ralf-Michael; Murck, Harald
2005-07-01
Sarizotan is a 5-HT(1A) agonist with high affinity to D(3) and D(4) receptors. In animal experiments, the drug shows a strong anti-cataleptic effect and suppresses effectively dyskinesias in animal models of L: -dopa-induced dyskinesia and of tardive dyskinesia. Data from an open pilot study in patients with Parkinson's disease show clear indication of a treatment effect against L: -dopa-induced dyskinesia. CNS-active drugs are known to modulate sleep electroencephalogram (EEG) and sleep-related hormone secretion. 5-HT(1A) agonists suppress rapid-eye movement (REM) sleep and enhance the secretion of ACTH, cortisol, prolactin and growth hormone (GH) at daytime. We hypothesised that sarizotan shares these effects. Furthermore, we were interested in the influence of sarizotan on leptin, which participates in the regulation of the energy balance and is enhanced after various psychoactive drugs. Ten healthy male subjects were investigated twice in a double-blind, placebo-controlled crossover design. Sleep EEG and nocturnal hormone secretion of ACTH, cortisol, prolactin, GH and leptin were examined after oral administration of either placebo or 20 mg of sarizotan at night. After administration of sarizotan, a significant reduction of REM sleep and total sleep time in conventional sleep EEG and a significant reduction of sigma- and theta-power in spectral analysis were observed. The main effect on nocturnal hormone secretion was a significant elevation of prolactin and of ACTH in the first half of the night. While REM sleep was suppressed, the endocrine effects of 20 mg sarizotan at night were weak. Its sleep-endocrine profile is comparable to the effects provoked by selective 5-HT reuptake inhibitors.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Xu, Wei; Department of cardiology, the Second Affiliated Hospital of Harbin Medical University, 246 Xuefu Road, Harbin 150081; Guo, Ting
2011-05-01
Dexamethasone has been shown to inhibit vascular smooth muscle cell (VSMC) migration, which is required for preventing restenosis. However, the mechanism underlying effect of dexamethasone remains unknown. We have previously demonstrated that peroxisome proliferator-activated receptor gamma (PPAR{gamma}) coactivator-1 alpha (PGC-1{alpha}) can inhibit VSMC migration and proliferation. Here, we investigated the role of PGC-1{alpha} in dexamethasone-reduced VSMC migration and explored the possible mechanism. We first examined PGC-1{alpha} expression in cultured rat aortic VSMCs. The results revealed that incubation of VSMCs with dexamethasone could significantly elevate PGC-1{alpha} mRNA expression. In contrast, platelet-derived growth factor (PDGF) decreased PGC-1{alpha} expression while stimulating VSMC migration.more » Mechanistic study showed that suppression of PGC-1{alpha} by small interfering RNA strongly abrogated the inhibitory effect of dexamethasone on VSMC migration, whereas overexpression of PGC-1{alpha} had the opposite effect. Furthermore, an analysis of MAPK signal pathways showed that dexamethasone inhibited ERK and p38 MAPK phosphorylation in VSMCs. Overexpression of PGC-1{alpha} decreased both basal and PDGF-induced p38 MAPK phosphorylation, but it had no effect on ERK phosphorylation. Finally, inhibition of PPAR{gamma} activation by a PPAR{gamma} antagonist GW9662 abolished the suppressive effects of PGC-1{alpha} on p38 MAPK phosphorylation and VSMC migration. These effects of PGC-1{alpha} were enhanced by a PPAR{gamma} agonist troglitazone. Collectively, our data indicated for the first time that one of the anti-migrated mechanisms of dexamethasone is due to the induction of PGC-1{alpha} expression. PGC-1{alpha} suppresses PDGF-induced VSMC migration through PPAR{gamma} coactivation and, consequently, p38 MAPK inhibition.« less
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Selective Targeting of Cancer Stem Cells by 2-Aminodihydroquinoline Analogs.
Park, Heejoo; Yu, Yeongji; Kim, Hyejin; Lee, Eun; Lee, Hani; Jeon, Raok; Kim, Woo-Young
2017-04-01
Many aminodihydroquinoline compounds have been studied to determine their cytotoxicity to cancer cells. However, anti-cancer stem cells (CSCs) activity of aminodihydroquinoline has not been tested in spite that CSC is believed to do an important roles in chemotherapy resistance and recurrence. The CSC selective targeting activities of 10 recently synthesized 2-aminodihydroquinoline analogs were examined on CSCs and bulk culture of a glioblastoma cell line. A diethylaminopropyl substituted aminodihydroquinoline, 5h, showed a strong anti-CSC effect and general cytotoxicity. However, a benzyl substituted aminodihydroquinoline, 5i, displayed the most effective anti-CSC effect, with no or small significant cytotoxic effect in bulk culture conditions. While 5h temporarily enhanced CSC marker-positive cells and eventually suppressed the CSC population, which is similar to other cytotoxic anticancer reagents reported, 5i selectively eliminated CSC marker-positive cells based on fluorescence activated cell sorter (FACS) analysis. 5h also temporarily activated some genes associated with signaling required for CSC, while 5i selectively suppressed these genes supporting that the differential effects are resulted from different molecular responses. In addition, the selective CSC effect is also found against a colon cancer cell line. Collectively, we suggest that these two novel aminodihydroquinoline compounds possess novel anti-CSC effects in colon and brain tumor derived cell lines probably through independent pathways.
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Subradiant spontaneous undulator emission through collective suppression of shot noise
Ratner, D.; Hemsing, E.; Gover, A.; ...
2015-05-01
The phenomenon of Dicke’s subradiance, in which the collective properties of a system suppress radiation, has received broad interest in atomic physics. Recent theoretical papers in the field of relativistic electron beams have proposed schemes to achieve subradiance through suppression of shot noise current fluctuations. The resulting “quiet” beam generates less spontaneous radiation than emitted even by a shot noise beam when oscillating in an undulator. Quiet beams could have diverse accelerator applications, including lowering power requirements for seeded free-electron lasers and improving efficiency of hadron cooling. In this paper we present experimental observation of a strong reduction in undulatormore » radiation, demonstrating the feasibility of noise suppression as a practical tool in accelerator physics.« less
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Subradiant spontaneous undulator emission through collective suppression of shot noise
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ratner, D.; Hemsing, E.; Gover, A.
The phenomenon of Dicke’s subradiance, in which the collective properties of a system suppress radiation, has received broad interest in atomic physics. Recent theoretical papers in the field of relativistic electron beams have proposed schemes to achieve subradiance through suppression of shot noise current fluctuations. The resulting “quiet” beam generates less spontaneous radiation than emitted even by a shot noise beam when oscillating in an undulator. Quiet beams could have diverse accelerator applications, including lowering power requirements for seeded free-electron lasers and improving efficiency of hadron cooling. In this paper we present experimental observation of a strong reduction in undulatormore » radiation, demonstrating the feasibility of noise suppression as a practical tool in accelerator physics.« less
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NASA Astrophysics Data System (ADS)
Farkašovský, Pavol
2018-05-01
The small-cluster exact-diagonalization calculations and the projector quantum Monte Carlo method are used to examine the competing effects of geometrical frustration and interaction on ferromagnetism in the Hubbard model on the generalised Shastry-Sutherland lattice. It is shown that the geometrical frustration stabilizes the ferromagnetic state at high electron concentrations ( n ≳ 7/4), where strong correlations between ferromagnetism and the shape of the noninteracting density of states are observed. In particular, it is found that ferromagnetism is stabilized for these values of frustration parameters, which lead to the single-peaked noninterating density of states at the band edge. Once, two or more peaks appear in the noninteracting density of states at the band edge the ferromagnetic state is suppressed. This opens a new route towards the understanding of ferromagnetism in strongly correlated systems.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Weymann, Ireneusz, E-mail: weymann@amu.edu.pl
2015-05-07
We analyze the spin-dependent linear-response transport properties of double quantum dots strongly coupled to external ferromagnetic leads. By using the numerical renormalization group method, we determine the dependence of the linear conductance and tunnel magnetoresistance on the degree of spin polarization of the leads and the position of the double dot levels. We focus on the transport regime where the system exhibits the SU(4) Kondo effect. It is shown that the presence of ferromagnets generally leads the suppression of the linear conductance due to the presence of an exchange field. Moreover, the exchange field gives rise to a transition frommore » the SU(4) to the orbital SU(2) Kondo effect. We also analyze the dependence of the tunnel magnetoresistance on the double dot levels' positions and show that it exhibits a very nontrivial behavior.« less
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Hiromoto, Kaho; Kuse, Yoshiki; Tsuruma, Kazuhiro; Tadokoro, Nobuyuki; Kaneko, Nobuyuki; Shimazawa, Masamitsu; Hara, Hideaki
2016-03-01
Blue light-emitting diodes (LEDs) in liquid crystal displays emit high levels of blue light, exposure to which is harmful to the retina. Here, we investigated the protective effects of colored lenses in blue LED light-induced damage to 661W photoreceptor-derived cells. We used eight kinds of colored lenses and one lens that reflects blue light. Moreover, we evaluated the relationship between the protective effects of the lens and the transmittance of lens at 464 nm. Lenses of six colors, except for the SY, PN, and reflective coating lenses, strongly decreased the reduction in cell damage induced by blue LED light exposure. The deep yellow lens showed the most protective effect from all the lenses, but the reflective coating lens and pink lens did not show any effects on photoreceptor-derived cell damage. Moreover, these results were correlated with the lens transmittance of blue LED light (464 nm). These results suggest that lenses of various colors, especially deep yellow lenses, may protect retinal photoreceptor cells from blue LED light in proportion to the transmittance for the wavelength of blue LED and the suppression of reactive oxygen species production and cell damage.
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Hasebe, Masaharu
2016-01-01
The interneurons of the mushroom body, known as Kenyon cells, are essential for the long-term memory of olfactory associative learning in some insects. Some studies have reported that nitric oxide (NO) is strongly related to this long-term memory in Kenyon cells. However, the target molecules and upstream and downstream NO signaling cascades are not completely understood. Here we analyzed the effect of the NO signaling cascade on Na+-activated K+ (KNa) channel activity in Kenyon cells of crickets (Gryllus bimaculatus). We found that two different NO donors, S-nitrosoglutathione (GSNO) and S-nitroso-N-acetyl-dl-penicillamine (SNAP), strongly suppressed KNa channel currents. Additionally, this inhibitory effect of GSNO on KNa channel activity was diminished by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase (sGC), and KT5823, an inhibitor of protein kinase G (PKG). Next, we analyzed the role of ACh in the NO signaling cascade. ACh strongly suppressed KNa channel currents, similar to NO donors. Furthermore, this inhibitory effect of ACh was blocked by pirenzepine, an M1 muscarinic ACh receptor antagonist, but not by 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP) and mecamylamine, an M3 muscarinic ACh receptor antagonist and a nicotinic ACh receptor antagonist, respectively. The ACh-induced inhibition of KNa channel currents was also diminished by the PLC inhibitor U73122 and the calmodulin antagonist W-7. Finally, we found that ACh inhibition was blocked by the nitric oxide synthase (NOS) inhibitor NG-nitro-l-arginine methyl ester (l-NAME). These results suggested that the ACh signaling cascade promotes NO production by activating NOS and NO inhibits KNa channel currents via the sGC/cGMP/PKG signaling cascade in Kenyon cells. PMID:26984419
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Ho, Chun-Yu; Jamison, Timothy F.
2011-01-01
Both a strong electron donor (IPr) and a strong electron acceptor (P(OPh)3) are necessary for a highly selective, nickel-catalyzed coupling reaction between alkenes, aldehydes, and silyltriflates. Without the phosphite, catalysis is not observed and several side reactions are observed. The phosphite appears to suppress the formation of these byproducts and rescue the catalytic cycle by accelerating reductive elimination from an (IPr–Ni–H)(OTf) complex. PMID:17154217
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Communication: Strong laser alignment of solvent-solute aggregates in the gas-phase
NASA Astrophysics Data System (ADS)
Trippel, Sebastian; Wiese, Joss; Mullins, Terry; Küpper, Jochen
2018-03-01
Strong quasi-adiabatic laser alignment of the indole-water-dimer clusters, an amino-acid chromophore bound to a single water molecule through a hydrogen bond, was experimentally realized. The alignment was visualized through ion and electron imaging following strong-field ionization. Molecular-frame photoelectron angular distributions showed a clear suppression of the electron yield in the plane of the ionizing laser's polarization, which was analyzed as strong alignment of the molecular cluster with ⟨cos2 θ2D⟩ ≥ 0.9.
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Catano, Laura B; Barton, Mark B; Boswell, Kevin M; Burkepile, Deron E
2017-03-01
Non-consumptive effects (NCEs) of predators occur as prey alters their habitat use and foraging decisions to avoid predation. Although NCEs are recognized as being important across disparate ecosystems, the factors influencing their strength and importance remain poorly understood. Ecological context, such as time of day, predator identity, and prey condition, may modify how prey species perceive and respond to risk, thereby altering NCEs. To investigate how predator identity affects foraging of herbivorous coral reef fishes, we simulated predation risk using fiberglass models of two predator species (grouper Mycteroperca bonaci and barracuda Sphyraena barracuda) with different hunting modes. We quantified how predation risk alters herbivory rates across space (distance from predator) and time (dawn, mid-day, and dusk) to examine how prey reconciles the conflicting demands of avoiding predation vs. foraging. When we averaged the effect of both predators across space and time, they suppressed herbivory similarly. Yet, they altered feeding differently depending on time of day and distance from the model. Although feeding increased strongly with increasing distance from the predators particularly during dawn, we found that the barracuda model suppressed herbivory more strongly than the grouper model during mid-day. We suggest that prey hunger level and differences in predator hunting modes could influence these patterns. Understanding how context mediates NCEs provides insight into the emergent effects of predator-prey interactions on food webs. These insights have broad implications for understanding how anthropogenic alterations to predator abundances can affect the spatial and temporal dynamics of important ecosystem processes.
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NASA Astrophysics Data System (ADS)
Nam, Hui; Guinan, John J.
2011-11-01
Apical auditory nerve (AN) fibers show two click-response regions that are both strongly inhibited by medial olivocochlear (MOC) efferents: (1) ringing responses from low- level (LL) clicks that are thought to be enhanced by a "cochlear amplifier," and (2) AN initial peak (ANIPr) responses from moderate-to-high level (˜70-100 dB pSPL) rarefaction clicks. Since MOC fibers synapse and act on outer hair cells (OHCs), the MOC inhibition of these responses indicates that OHC processes are heavily involved in the production of both LL and ANIPr responses. Using AN recordings in anesthetized cats, we explored the role of OHC stereocilia position in the production of these click-response regions by presenting rarefaction clicks at different phases of 50 Hz, 70-110 dB SPL bias tones. Bias effects on LL responses followed the traditional biasing pattern of twice-a-bias-tone-cycle suppression with more suppression at one phase than the other. This suppression is attributable to the bias tone moving the OHC stereocilia toward low-slope, saturation regions of the mechano-electric transduction function with the rest position being closer to one saturation region. A somewhat similar pattern was found for ANIPr responses except that the bias phases of the largest suppressions were different in ANIPr versus LL responses, usually by ˜180 degrees. The data are consistent with the LL and ANIPr responses both being due to active processes in OHCs that are controlled by OHC stereocilia position. The different phases of the LL and ANIPr suppressions indicate that different mechanisms, and perhaps different vibration patterns in the organ of Corti, are involved in the production of LL and ANIPr responses.
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Nazikian, R; Paz-Soldan, C; Callen, J D; deGrassie, J S; Eldon, D; Evans, T E; Ferraro, N M; Grierson, B A; Groebner, R J; Haskey, S R; Hegna, C C; King, J D; Logan, N C; McKee, G R; Moyer, R A; Okabayashi, M; Orlov, D M; Osborne, T H; Park, J-K; Rhodes, T L; Shafer, M W; Snyder, P B; Solomon, W M; Strait, E J; Wade, M R
2015-03-13
Rapid bifurcations in the plasma response to slowly varying n=2 magnetic fields are observed as the plasma transitions into and out of edge-localized mode (ELM) suppression. The rapid transition to ELM suppression is characterized by an increase in the toroidal rotation and a reduction in the electron pressure gradient at the top of the pedestal that reduces the perpendicular electron flow there to near zero. These events occur simultaneously with an increase in the inner-wall magnetic response. These observations are consistent with strong resonant field penetration of n=2 fields at the onset of ELM suppression, based on extended MHD simulations using measured plasma profiles. Spontaneous transitions into (and out of) ELM suppression with a static applied n=2 field indicate competing mechanisms of screening and penetration of resonant fields near threshold conditions. Magnetic measurements reveal evidence for the unlocking and rotation of tearinglike structures as the plasma transitions out of ELM suppression.
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Nazikian, Raffi; Paz-Soldan, Carlos; Callen, James D.; ...
2015-03-12
Rapid bifurcations in the plasma response to slowly varying n=2 magnetic fields are observed as the plasma transitions into and out of edge localized mode (ELM) suppression. The rapid transition to ELM suppression is characterized by an increase in the toroidal rotation and a reduction in the electron pressure gradient at the top of the pedestal which reduces the perpendicular electron flow to near zero. These events occur simultaneously with an increase in the inner wall magnetic response. These observations are consistent strong resonant field penetration of n=2 fields at the onset of ELM suppression, based on extended MHD simulationsmore » using measured plasma profiles. Spontaneous transitions into (and out of) ELM suppression with a static applied n=2 field indicate competing mechanisms of screening and penetration of resonant fields near threshold conditions. Magnetic measurements reveal evidence for the unlocking and rotation of tearing-like structures as the plasma transitions out of ELM suppression.« less
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NASA Astrophysics Data System (ADS)
Matin, M.; Mondal, Rajib; Barman, N.; Thamizhavel, A.; Dhar, S. K.
2018-05-01
Here, we report an extremely large positive magnetoresistance (XMR) in a single-crystal sample of MoSi2, approaching almost 107% at 2 K in a 14-T magnetic field without appreciable saturation. Hall resistivity data reveal an uncompensated nature of MoSi2 with an electron-hole compensation level sufficient enough to expect strong saturation of magnetoresistance in the high-field regime. Magnetotransport and the complementary de Haas-van Alphen (dHvA) oscillations results, however, suggest that strong Zeeman effect causes a magnetic field-induced modulation of the Fermi pockets and drives the system towards perfect electron-hole compensation condition in the high-field regime. Thus, the nonsaturating XMR of this semimetal arises under the unconventional situation of Zeeman effect-driven electron-hole compensation, whereas its huge magnitude is decided solely by the ultralarge value of the carrier mobility. Intrinsic ultralarge carrier mobility, strong suppression of backward scattering of the charge carriers, and nontrivial Berry phase in dHvA oscillations attest to the topological character of MoSi2. Therefore, this semimetal represents another material hosting combination of topological and conventional electronic phases.
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Infrared measurement and composite tracking algorithm for air-breathing hypersonic vehicles
NASA Astrophysics Data System (ADS)
Zhang, Zhao; Gao, Changsheng; Jing, Wuxing
2018-03-01
Air-breathing hypersonic vehicles have capabilities of hypersonic speed and strong maneuvering, and thus pose a significant challenge to conventional tracking methodologies. To achieve desirable tracking performance for hypersonic targets, this paper investigates the problems related to measurement model design and tracking model mismatching. First, owing to the severe aerothermal effect of hypersonic motion, an infrared measurement model in near space is designed and analyzed based on target infrared radiation and an atmospheric model. Second, using information from infrared sensors, a composite tracking algorithm is proposed via a combination of the interactive multiple models (IMM) algorithm, fitting dynamics model, and strong tracking filter. During the procedure, the IMMs algorithm generates tracking data to establish a fitting dynamics model of the target. Then, the strong tracking unscented Kalman filter is employed to estimate the target states for suppressing the impact of target maneuvers. Simulations are performed to verify the feasibility of the presented composite tracking algorithm. The results demonstrate that the designed infrared measurement model effectively and continuously observes hypersonic vehicles, and the proposed composite tracking algorithm accurately and stably tracks these targets.
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Carapella, G.; Sabatino, P.; Barone, C.; Pagano, S.; Gombos, M.
2016-01-01
Vortices are topological defects accounting for many important effects in superconductivity, superfluidity, and magnetism. Here we address the stability of a small number of such excitations driven by strong external forces. We focus on Abrikosov-Josephson vortex that appears in lateral superconducting S/S’/S weak links with suppressed superconductivity in S’. In such a system the vortex is nucleated and confined in the narrow S’ region by means of a small magnetic field and moves under the effect of a force proportional to an applied electrical current with a velocity proportional to the measured voltage. Our numerical simulations show that when a slow moving Abrikosov-Josephson vortex is driven by a strong constant current it becomes unstable with respect to a faster moving excitation: the Josephon-like vortex. Such a current-driven transition explains the structured dissipative branches that we observe in the voltage-current curve of the weak link. When vortex matter is strongly confined phenomena as magnetoresistance oscillations and reentrance of superconductivity can possibly occur. We experimentally observe these phenomena in our weak links. PMID:27752137
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Latz, Ellen; Eisenhauer, Nico; Rall, Björn Christian; Scheu, Stefan; Jousset, Alexandre
2016-01-01
Plant diseases cause dramatic yield losses worldwide. Current disease control practices can be deleterious for the environment and human health, calling for alternative and sustainable management regimes. Soils harbour microorganisms that can efficiently suppress pathogens. Uncovering mediators driving their functioning in the field still remains challenging, but represents an essential step in order to develop strategies for increased soil health. We set up plant communities of varying richness to experimentally test the potential of soils differing in plant community history to suppress the pathogen Rhizoctonia solani. The results indicate that plant communities shape soil-disease suppression via changes in abiotic soil properties and the abundance of bacterial groups including species of the genera Actinomyces, Bacillus and Pseudomonas. Further, the results suggest that pairwise interactions between specific plant species strongly affect soil suppressiveness. Using structural equation modelling, we provide a pathway orientated framework showing how the complex interactions between plants, soil and microorganisms jointly shape soil suppressiveness. Our results stress the importance of plant community composition as a determinant of soil functioning, such as the disease suppressive potential of soils. PMID:27021053
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Quantitative characterization of non-classic polarization of cations on clay aggregate stability.
Hu, Feinan; Li, Hang; Liu, Xinmin; Li, Song; Ding, Wuquan; Xu, Chenyang; Li, Yue; Zhu, Longhui
2015-01-01
Soil particle interactions are strongly influenced by the concentration, valence and ion species and the pH of the bulk solution, which will also affect aggregate stability and particle transport. In this study, we investigated clay aggregate stability in the presence of different alkali ions (Li+, Na+, K+, and Cs+) at concentrations from10-5 to 10-1 mol L-1. Strong specific ion effects on clay aggregate stability were observed, and showed the order Cs+>K+>Na+>Li+. We found that it was not the effects of ion size, hydration, and dispersion forces in the cation-surface interactions but strong non-classic polarization of adsorbed cations that resulted in these specific effects. In this study, the non-classic dipole moments of each cation species resulting from the non-classic polarization were estimated. By comparing non-classic dipole moments with classic values, the observed dipole moments of adsorbed cations were up to 104 times larger than the classic values for the same cation. The observed non-classic dipole moments sharply increased with decreasing electrolyte concentration. We conclude that strong non-classic polarization could significantly suppress the thickness of the diffuse layer, thereby weakening the electric field near the clay surface and resulting in improved clay aggregate stability. Even though we only demonstrated specific ion effects on aggregate stability with several alkali ions, our results indicate that these effects could be universally important in soil aggregate stability.
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Quantitative Characterization of Non-Classic Polarization of Cations on Clay Aggregate Stability
Hu, Feinan; Li, Hang; Liu, Xinmin; Li, Song; Ding, Wuquan; Xu, Chenyang; Li, Yue; Zhu, Longhui
2015-01-01
Soil particle interactions are strongly influenced by the concentration, valence and ion species and the pH of the bulk solution, which will also affect aggregate stability and particle transport. In this study, we investigated clay aggregate stability in the presence of different alkali ions (Li+, Na+, K+, and Cs+) at concentrations from10−5 to 10−1 mol L−1. Strong specific ion effects on clay aggregate stability were observed, and showed the order Cs+>K+>Na+>Li+. We found that it was not the effects of ion size, hydration, and dispersion forces in the cation–surface interactions but strong non-classic polarization of adsorbed cations that resulted in these specific effects. In this study, the non-classic dipole moments of each cation species resulting from the non-classic polarization were estimated. By comparing non-classic dipole moments with classic values, the observed dipole moments of adsorbed cations were up to 104 times larger than the classic values for the same cation. The observed non-classic dipole moments sharply increased with decreasing electrolyte concentration. We conclude that strong non-classic polarization could significantly suppress the thickness of the diffuse layer, thereby weakening the electric field near the clay surface and resulting in improved clay aggregate stability. Even though we only demonstrated specific ion effects on aggregate stability with several alkali ions, our results indicate that these effects could be universally important in soil aggregate stability. PMID:25874864
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Munson, Seth M.; Long, A. Lexine; Decker, Cheryl E.; Johnson, Katie A.; Walsh, Kathleen; Miller, Mark E.
2015-01-01
Invasive non-native species pose a large threat to restoration efforts following large-scale disturbances. Bromus tectorum (cheatgrass) is a non-native annual grass in the western U.S. that both spreads quickly following fire and accelerates the fire cycle. Herbicide and seeding applications are common restoration practices to break the positive fire-invasion feedback loop and recover native perennial species, but their interactive effects have infrequently been tested at the landscape-scale and repeated in time to encourage long-lasting effects. We determined the efficacy of repeated post-fire application of the herbicide imazapic and seeding treatments to suppressBromus abundance and promote perennial vegetation recovery. We found that the selective herbicide reduced Bromus cover by ~30 % and density by >50 % across our study sites, but had a strong initial negative effect on seeded species. The most effective treatment to promote perennial seeded species cover was seeding them alone followed by herbicide application 3 years later when the seeded species had established. The efficacy of the treatments was strongly influenced by water availability, as precipitation positively affected the density and cover of Bromus; soil texture and aspect secondarily influenced Bromus abundance and seeded species cover by modifying water retention in this semi-arid region. Warmer temperatures positively affected the non-native annual grass in the cool-season, but negatively affected seeded perennial species in the warm-season, suggesting an important role of seasonality in a region projected to experience large increases in warming in the future. Our results highlight the importance of environmental interactions and repeated treatments in influencing restoration outcomes at the landscape-scale.
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Lim, Eun Joung; Joung, Youn Hee; Hong, Dae Young; Park, Eui U.; Park, Seung Hwa; Choi, Soo Keun; Moon, Eon-Soo; Cho, Byung Wook; Park, Kyung Do; Lee, Hak Kyo; Kim, Myong-Jo; Park, Dong-Sik; Yang, Young Mok
2012-01-01
Background Cancer is one of the highly virulent diseases known to humankind with a high mortality rate. Breast cancer is the most common cancer in women worldwide. Sorghum is a principal cereal food in many parts of the world, and is critical in folk medicine of Asia and Africa. In the present study, we analyzed the effects of HSE in metastatic breast cancer. Methodology/Principal Findings Preliminary studies conducted on MDA-MB 231 and MCF-7 xenograft models showed tumor growth suppression by HSE. Western blotting studies conducted both in vivo and in vitro to check the effect of HSE in Jak/STAT pathways. Anti-metastatic effects of HSE were confirmed using both MDA-MB 231 and MCF-7 metastatic animal models. These studies showed that HSE can modulate Jak/STAT pathways, and it hindered the STAT5b/IGF-1R and STAT3/VEGF pathways not only by down-regulating the expression of these signal molecules and but also by preventing their phosphorylation. The expression of angiogenic factors like VEGF, VEGF-R2 and cell cycle regulators like cyclin D, cyclin E, and pRb were found down-regulated by HSE. In addition, it also targets Brk, p53, and HIF-1α for anti-cancer effects. HSE induced G1 phase arrest and migration inhibition in MDA-MB 231 cells. The metastasis of breast cancer to the lungs also found blocked by HSE in the metastatic animal model. Conclusions/Significance Usage of HS as a dietary supplement is an inexpensive natural cancer therapy, without any side effects. We strongly recommend the use of HS as an edible therapeutic agent as it possesses tumor suppression, migration inhibition, and anti-metastatic effects on breast cancer. PMID:22792362
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Interleukin 6 inhibits HBV entry through NTCP down regulation.
Bouezzedine, Fidaa; Fardel, Olivier; Gripon, Philippe
2015-07-01
Hepatitis B virus (HBV) infection is a major public health problem. Recently, the human liver bile acid transporter Na(+)/taurocholate cotransporting polypeptide (NTCP) has been identified as an HBV specific receptor. NTCP expression is known to be strongly regulated by IL-6. This study was aimed at characterizing the effect of IL-6 on HBV entry. HBV entry was inhibited by up to 90% when cells were pretreated with IL-6 as shown by a strong inhibition of long term HBsAg secretion. This effect was confirmed by showing a severe reduction of intracellular HBV cccDNA. In parallel, we observed a 98% decrease in NTCP mRNA steady state level and an 80% reduction in NTCP-mediated taurocholate uptake. IL-6-mediated inhibition of NTCP-mediated taurocholate uptake and viral entry exhibited similar dose-dependence and kinetics while restoration of NTCP expression suppressed the inhibitory effect of IL-6. NTCP-mediated HBV entry is therefore markedly inhibited by IL-6. Copyright © 2015 Elsevier Inc. All rights reserved.
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Hasebe, Masaharu; Kanda, Shinji; Oka, Yoshitaka
2016-11-01
Close interaction exists between energy-consuming reproduction and nutritional status. However, there are differences in costs and priority for reproduction among species and even between sexes, which leads to diversification of interactions between reproduction and nutritional status. Despite such diversified interactions among species and sexes, most of the analysis of the nutritional status-dependent regulation of reproduction has been limited to an endothermic vertebrate, mammalian species of either sex. Therefore, the mechanisms underlying the diversified interactions remain elusive. In the present study, we demonstrated the effects of malnutritional status on reproduction at both organismal and cellular levels in an ectothermic vertebrate, a teleost medaka of both sexes. First, we analyzed the effects of malnutrition by fasting on gonadosomatic index, number of spawned/fertilized eggs, and courtship behavior. Fasting strongly suppressed reproduction in females but, surprisingly, not in males. Next, we analyzed the effects of fasting on firing activity of hypothalamic GnRH1 neurons, which form the final common pathway for the control of reproduction. An electrophysiological analysis showed that low glucose, which is induced by fasting, directly suppresses the firing activity of GnRH1 neurons specifically in females through intracellular ATP-sensitive potassium channels and AMP-activated protein kinase pathways. Based on the fact that such suppressions occurred only in females, we conclude that nutritional status-dependent, glucose-sensing in GnRH1 neurons may contribute to the most fitted reproductive regulation for each sex.
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Analysis of passive surface-wave noise in surface microseismic data and its implications
Forghani-Arani, F.; Willis, M.; Haines, S.; Batzle, M.; Davidson, M.
2011-01-01
Tight gas reservoirs are projected to be a major portion of future energy resources. Because of their low permeability, hydraulic fracturing of these reservoirs is required to improve the permeability and reservoir productivity. Passive seismic monitoring is one of the few tools that can be used to characterize the changes in the reservoir due to hydraulic fracturing. Although the majority of the studies monitoring hydraulic fracturing exploit down hole microseismic data, surface microseismic monitoring is receiving increased attention because it is potentially much less expensive to acquire. Due to a broader receiver aperture and spatial coverage, surface microseismic data may be more advantageous than down hole microseismic data. The effectiveness of this monitoring technique, however, is strongly dependent on the signal-to-noise ratio of the data. Cultural and ambient noise can mask parts of the waveform that carry information about the subsurface, thereby decreasing the effectiveness of surface microseismic analysis in identifying and locating the microseismic events. Hence, time and spatially varying suppression of the surface-wave noise ground roll is a critical step in surface microseismic monitoring. Here, we study a surface passive dataset that was acquired over a Barnett Shale Formation reservoir during two weeks of hydraulic fracturing, in order to characterize and suppress the surface noise in this data. We apply techniques to identify the characteristics of the passive ground roll. Exploiting those characteristics, we can apply effective noise suppression techniques to the passive data. ?? 2011 Society of Exploration Geophysicists.
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Abdou, R F; Megalla, S E; Moharram, A M; Abdel-Gawad, K M; Sherif, T H; el-Syed Mahmood, A L; Lottfy, A E
1989-01-01
The cytogenetic effects of fungal metabolites produced by 113 strains belonging to 36 fungal species and isolated form 5 substrates of commercial poultry feedstuffs were tested for their effect on the growing root meristems of Allium cepa. The fungal metabolites of Paecilomyces canescens, Aspergillus fumigatus, Syncephalastrum racemosum, Aspergillus terreus and Mucor hiemalis strongly suppressed cell division. Metabolites from other strains had less effect on cell division but permitted the appearance of several abnormalities through different mitotic stages. In general, chromosomal aberrations were more obvious with metabolites of Aspergillus species, Mucor circinelloides and Cladosporium cladosporioides. The mutagenic effects produced by these fungal metabolites reflect the risk that might take place through the consumption of these contaminated feedstuffs.
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NASA Astrophysics Data System (ADS)
Takaya, Y.; Kubo, Y.; Yamaguchi, M.; Vitart, F.; Hirahara, S.; Maeda, S.
2016-12-01
Strong El Niño events have lingering effects on the seasonal variability in the Indo- western Pacific region in the mature-decay phase of El Niño. Specifically, in the decay phase, a low-level anticyclonic circulation and suppressed convection in the western North Pacific are enforced as a result of a local air-sea feedback in the western North Pacific and remote response to the Indian Ocean warming due to El Niño. The typhoon activity in the western North Pacific is also modulated by the lingering effects in the early typhoon season (boreal spring to early summer) following the strong El Niño events. This study investigates underlying mechanisms and predictability by analyzing the historical analysis data, subseasonal and seasonal reforecast data, and sensitivity experiments with the use of an atmosphere-ocean coupled model for the 2016 typhoon season. In this study, we focus on the remote response of the typhoon activity in the Indo-Pacific region. First, we examined the case of 2016, which exhibited the striking inactive typhoon activity and marked the second latest genesis of the first typhoon of the year since 1977 (Typhoon Nipartak on 3 July 2016). The inactive typhoon activity in the early typhoon season of 2016 is plausibly related to the lingering effects of the preceding strong El Niño in 2015/2016 winter. And the inactive typhoon condition and its related atmosphere-ocean conditions in the western north Pacific were successfully predicted with sub-seasonal prediction systems and JMA seasonal prediction system (JMA/MRI-CPS2) well in advance. A composite analysis using historical analysis data indicates that the typhoon activity tends to be suppressed associated with the Indian Ocean warming in boreal spring to summer following El Niño winters. This is relatively well replicated in reforecasts of JMA/MRI-CPS2. We also carried out sensitivity experiments with JMA/MRI-CPS2, where we strongly nudge sea surface temperature (SST) in the Indian Ocean to climatological SST. The typhoon activity in the western North Pacific is enhanced in the sensitivity experiment, implying that the the Indian Ocean played a role in shaping the inactive typhoon conditions in the 2016 typhoon season. We will further discuss the underlying mechanisms and predictability using the series of experiments.
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Regulation of Apoptosis during Flavivirus Infection.
Okamoto, Toru; Suzuki, Tatsuya; Kusakabe, Shinji; Tokunaga, Makoto; Hirano, Junki; Miyata, Yuka; Matsuura, Yoshiharu
2017-08-28
Apoptosis is a type of programmed cell death that regulates cellular homeostasis by removing damaged or unnecessary cells. Its importance in host defenses is highlighted by the observation that many viruses evade, obstruct, or subvert apoptosis, thereby blunting the host immune response. Infection with Flaviviruses such as Japanese encephalitis virus (JEV), Dengue virus (DENV) and West Nile virus (WNV) has been shown to activate several signaling pathways such as endoplasmic reticulum (ER)-stress and AKT/PI3K pathway, resulting in activation or suppression of apoptosis in virus-infected cells. On the other hands, expression of some viral proteins induces or protects apoptosis. There is a discrepancy between induction and suppression of apoptosis during flavivirus infection because the experimental situation may be different, and strong links between apoptosis and other types of cell death such as necrosis may make it more difficult. In this paper, we review the effects of apoptosis on viral propagation and pathogenesis during infection with flaviviruses.
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Graybill, John R.; Bocanegra, Rosie; Najvar, Laura K.; Loebenberg, David; Luther, Mike F.
1998-01-01
Outbred ICR mice were immune suppressed either with hydrocortisone or with 5-fluorouracil and were infected intranasally with Aspergillus fumigatus. Beginning 3 days before infection some groups of mice were given recombinant human granulocyte colony-stimulating factor (G-CSF), SCH56592 (an antifungal triazole), or both. Corticosteroid-pretreated mice responded to SCH56592 and had reduced counts in lung tissue and prolonged survival. In these mice, G-CSF strongly antagonized the antifungal activity of SCH56592. Animals treated with both agents developed large lung abscesses with polymorphonuclear leukocytes and large amounts of Aspergillus. In contrast, mice made neutropenic with 5-fluorouracil and then infected with A. fumigatus conidia benefited from either G-CSF or triazoles, and the effect of the combination was additive rather than antagonistic. Host predisposing factors contribute in different ways to the outcome of growth factor therapy in aspergillosis. PMID:9756743
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Magnetoresistance effect in permalloy nanowires with various types of notches
NASA Astrophysics Data System (ADS)
Gao, Y.; You, B.; Wang, J.; Yuan, Y.; Wei, L. J.; Tu, H. Q.; Zhang, W.; Du, J.
2018-05-01
Suppressing the stochastic domain wall (DW) motion in magnetic nanowires is of great importance for designing DW-related spintronic devices. In this work, we have investigated the pinning/depinning processes of DWs in permalloy nanowires with three different types of notches by using longitudinal magnetoresistance (MR) measurement. The averaged MR curves demonstrate that the stochastic DW depinning is suppressed partly or even completely by a transversely asymmetric notch. The single-shot MR curves show that how the resistance changes with the applied field also depends strongly on the notch type while the DW is pinned around the notch. In the case of two depinning fields, larger (smaller) change of resistance always corresponds to larger (smaller) depinning field, regardless of the notch type. These phenomena can be understood by that the spin structure around the notch changes differently with the notch type when the DW is traveling through the notch.
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Microhydration Prevents Fragmentation of Uracil and Thymine by Low-Energy Electrons.
Kočišek, J; Pysanenko, A; Fárník, M; Fedor, J
2016-09-01
When ionizing radiation passes biological matter, a large number of secondary electrons with very low energies (<3 eV) is produced. It is known that such electrons cause an efficient fragmentation of isolated nucleobases via dissociative electron attachment. We present an experimental study of the electron attachment to microhydrated nucleobases. Our novel approach allows significant control over the hydration of molecules studied in the molecular beam. We directly show for the first time that the presence of a few water molecules suppresses the dissociative channel and leads exclusively to formation of intact molecular and hydrated anions. The suppression of fragmentation is ascribed to caging-like effects and fast energy transfer to the solvent. This is in contrast with theoretical prediction that microhydration strongly enhances the fragmentation of nucleobases. The current observation impacts mechanisms of reductive DNA strand breaks proposed to date on the basis of gas-phase experiments.
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Viral degradasome hijacks mitochondria to suppress innate immunity
Goswami, Ramansu; Majumdar, Tanmay; Dhar, Jayeeta; Chattopadhyay, Saurabh; Bandyopadhyay, Sudip K; Verbovetskaya, Valentina; Sen, Ganes C; Barik, Sailen
2013-01-01
The balance between the innate immunity of the host and the ability of a pathogen to evade it strongly influences pathogenesis and virulence. The two nonstructural (NS) proteins, NS1 and NS2, of respiratory syncytial virus (RSV) are critically required for RSV virulence. Together, they strongly suppress the type I interferon (IFN)-mediated innate immunity of the host cells by degrading or inhibiting multiple cellular factors required for either IFN induction or response pathways, including RIG-I, IRF3, IRF7, TBK1 and STAT2. Here, we provide evidence for the existence of a large and heterogeneous degradative complex assembled by the NS proteins, which we named “NS-degradasome” (NSD). The NSD is roughly ∼300-750 kD in size, and its degradative activity was enhanced by the addition of purified mitochondria in vitro. Inside the cell, the majority of the NS proteins and the substrates of the NSD translocated to the mitochondria upon RSV infection. Genetic and pharmacological evidence shows that optimal suppression of innate immunity requires mitochondrial MAVS and mitochondrial motility. Together, we propose a novel paradigm in which the mitochondria, known to be important for the innate immune activation of the host, are also important for viral suppression of the innate immunity. PMID:23877405
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Long-term contraception in a small implant: A review of Suprelorin (deslorelin) studies in cats.
Fontaine, Christelle
2015-09-01
Deslorelin (Suprelorin®; Virbac) is a gonadotropin-releasing hormone (GnRH) agonist licensed in select countries for the long-term suppression of fertility in adult male dogs and male ferrets. This article summarizes studies investigating the use of deslorelin implants for the long-term suppression of fertility in male and female domestic cats. Slow-release deslorelin implants have been shown to generate effective, safe and reversible long-term contraception in male and female cats. In pubertal cats, a 4.7 mg deslorelin implant suppressed steroid sex hormones for an average of approximately 20 months (range 15-25 months) in males and an average of approximately 24 months (range 16-37 months) in females. Reversibility has been demonstrated by fertile matings approximately 2 years post-treatment in both male and female adult cats. In prepubertal female cats of approximately 4 months of age, puberty was postponed to an average of approximately 10 months of age (range 6-15 months) by a 4.7 mg deslorelin implant. The large variability in the duration of suppression of gonadal activity makes the definition of the optimal time for reimplantation quite challenging. In addition, the temporary stimulation phase occurring in the weeks following deslorelin implantation can induce in adult female cats a fertile estrus that needs to be managed to avoid unwanted pregnancy. Longer duration and larger scale controlled field studies implementing blinding, a negative control group and a carefully controlled randomization to each group are needed. Furthermore, the effects of repeated treatment need to be investigated. Finally, the effect of treatment on growth and bone quality of prepubertal cats needs to be assessed. However, the ease of use, long-lasting effects and reversibility of deslorelin implants are strong positive points supporting their use for controlling feline reproduction. © The Author(s) 2015.
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Taher, Yousef A; van Esch, Betty C A M; Hofman, Gerard A; Henricks, Paul A J; van Oosterhout, Antoon J M
2008-04-15
1alpha,25-Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), a potent inhibitor of NF-kappaB expression, can prevent the maturation of dendritic cells in vitro leading to tolerogenic dendritic cells with increased potential to induce regulatory T cells. Herein, we investigated whether the combination of allergen immunotherapy with 1,25(OH)(2)D(3) potentiates the suppressive effects of immunotherapy and whether the immunoregulatory cytokines IL-10 and TGF-beta are involved in the effector phase. OVA-sensitized and challenged BALB/c mice displayed airway hyperresponsiveness (AHR) and increased serum OVA-specific IgE levels, bronchoalveolar lavage eosinophilia, and Th2 cytokine levels. In this model, the dose response of allergen immunotherapy 10 days before OVA inhalation challenge shows strong suppression of asthma manifestations at 1 mg of OVA, but partial suppression of bronchoalveolar lavage eosinophilia, IgE up-regulation, and no reduction of AHR at 100 microg. Interestingly, coadministration of 10 ng of 1,25(OH)(2)D(3) with 100 microg of OVA immunotherapy significantly inhibited AHR and potentiated the reduction of serum OVA-specific IgE levels, airway eosinophilia, and Th2-related cytokines concomitant with increased IL-10 levels in lung tissues and TGF-beta and OVA-specific IgA levels in serum. Similar effects on suboptimal immunotherapy were observed by inhibition of the NF-kappaB pathway using the selective IkappaB kinase 2 inhibitor PS-1145. The suppressive effects of this combined immunotherapy were partially reversed by treatment with mAb to either IL-10R or TGF-beta before OVA inhalation challenge but completely abrogated when both Abs were given. These data demonstrate that 1,25(OH)(2)D(3) potentiates the efficacy of immunotherapy and that the regulatory cytokines IL-10 and TGF-beta play a crucial role in the effector phase of this mouse model.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Lee, Eunjung; Son, Joe Eun; Byun, Sanguine
Licorice extract which is used as a natural sweetener has been shown to possess inhibitory effects against prostate cancer, but the mechanisms responsible are poorly understood. Here, we report a compound, isoangustone A (IAA) in licorice that potently suppresses the growth of aggressive prostate cancer and sought to clarify its mechanism of action. We analyzed its inhibitory effects on the growth of PTEN-deleted human prostate cancer cells, in vitro and in vivo. Administration of IAA significantly attenuated the growth of prostate cancer cell cultures and xenograft tumors. These effects were found to be attributable to inhibition of the G1/S phasemore » cell cycle transition and the accumulation of p27{sup kip1}. The elevated p27{sup kip1} expression levels were concurrent with the decrease of its phosphorylation at threonine 187 through suppression of CDK2 kinase activity and the reduced phosphorylation of Akt at Serine 473 by diminishing the kinase activity of the mammalian target of rapamycin (mTOR). Further analysis using recombinant proteins and immunoprecipitated cell lysates determined that IAA exerts suppressive effects against CDK2 and mTOR kinase activity by direct binding with both proteins. These findings suggested that the licorice compound IAA is a potent molecular inhibitor of CDK2 and mTOR, with strong implications for the treatment of prostate cancer. Thus, licorice-derived extracts with high IAA content warrant further clinical investigation for nutritional sources for prostate cancer patients. - Highlights: • Isoangustone A suppresses growth of PC3 and LNCaP prostate cancer cells. • Administration of isoangustone A inhibits tumor growth in mice. • Treatment of isoangustone A induces cell cycle arrest and accumulation of p27{sup kip1}. • Isoangustone A inhibits CDK2 and mTOR activity. • Isoangustone A directly binds with CDK2 and mTOR complex in prostate cancer cells.« less
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Sun, Wu; Cai, Yun; Zhang, Xin-Xin; Chen, Hao; Lin, Yan-Die; Li, Hao
2017-08-01
Osthole, a natural coumarin found in traditional Chinese medicinal plants, has shown multiple biological activities. In the present study, we investigated the preventive effects of osthole on inflammatory bowel disease (IBD). Colitis was induced in mice by infusing TNBS into the colonic lumen. Before TNBS treatment, the mice received osthole (100 mg·kg -1 ·d -1 , ip) for 3 d. Pretreatment with osthole significantly ameliorated the clinical scores, colon length shortening, colonic histopathological changes and the expression of inflammatory mediators in TNBS-induced colitis. Pretreatment with osthole elevated serum cAMP levels; but treatment with the PKA inhibitor H89 (10 mg·kg -1 ·d -1 , ip) did not abolish the beneficial effects of osthole on TNBS-induced colitis. In mouse peritoneal macrophages, pretreatment with osthole (50 μmol/L) significantly attenuated the LPS-induced elevation of cytokines at the mRNA level; inhibition of PKA completely reversed the inhibitory effects of osthole on IL-1β, IL-6, COX2, and MCP-1 but not on TNFα. In Raw264.7 cells, the p38 inhibitor SB203580 markedly suppressed LPS-induced upregulation of the cytokines, whereas the PKA inhibitors H89 or KT5720 did not abolish the inhibitory effects of SB203580. Moreover, in LPS-stimulated mouse peritoneal macrophages, SB203580 strongly inhibited the restored expression of IL-1β, IL-6, COX2, and MCP-1, which was achieved by abolishing the suppressive effects of osthole with the PKA inhibitors. Western blot analysis showed that osthole significantly suppressed the phosphorylation of p38, which was induced by TNBS in mice or by LPS in Raw264.7 cells. Inhibition of PKA partially reversed the suppressive effects of osthole on p38 phosphorylation in LPS-stimulated cells. Collectively, our results suggest that osthole is effective in the prevention of TNBS-induced colitis by reducing the expression of inflammatory mediators and attenuating p38 phosphorylation via both cAMP/PKA-dependent and independent pathways, among which the cAMP/PKA-independent pathway plays a major role.
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Dong, Cong; Yu, Jiuru; Zhu, Ying; Dong, Changjin
2013-01-01
Background & objectives: Destruxin A, destruxin B and destruxin E isolated from entomopathogenic fungus Metarhizium anisopliae showed a strong suppressive effect on the replication of hepatitis B virus (HBV) in human hepatoma cells. In this study, the anti-HBV effects of the crude destruxins extracted from M. anisopliae var. dcjhyium were detected both in vitro and in vivo. Methods: HepG2.2.15 cells were cultured to observe the inhibitory effects of the crude destruxins on the gene expression and replication of HBV by radioimmunoassay detection and real-time quantitative PCR. In vivo, duck HBV (DHBV)-infected ducks were treated with the crude destruxins at 2.0, 4.0, 6.0 μg/kg once a day for 15 days, DHBV DNA was examined by real-time quantitative PCR. Results: The crude destruxins suppressed the replication of HBV-DNA and the production of HBsAg and HBeAg with IC50 of about 1.2 and 1.4 μg/ml. Transcript of viral mRNA was significantly suppressed by the crude destruxins in HepG2.2.15 cells. In vivo, the duck serum DHBV-DNA levels were markedly reduced in the group of the crude destruxins. Interpretation & conclusions: The crude destruxins inhibited the gene expression and replication of HBV both in vitro and in vivo, and their anti-HBV effect was stronger than that with destruxin B. Our results indicate that the crude destruxins from M.anisopliae var. dcjhyium may be potential antivirus agents. Further studies need to be done to confirm these findings. PMID:24521644
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Infrared video based gas leak detection method using modified FAST features
NASA Astrophysics Data System (ADS)
Wang, Min; Hong, Hanyu; Huang, Likun
2018-03-01
In order to detect the invisible leaking gas that is usually dangerous and easily leads to fire or explosion in time, many new technologies have arisen in the recent years, among which the infrared video based gas leak detection is widely recognized as a viable tool. However, all the moving regions of a video frame can be detected as leaking gas regions by the existing infrared video based gas leak detection methods, without discriminating the property of each detected region, e.g., a walking person in a video frame may be also detected as gas by the current gas leak detection methods.To solve this problem, we propose a novel infrared video based gas leak detection method in this paper, which is able to effectively suppress strong motion disturbances.Firstly, the Gaussian mixture model(GMM) is used to establish the background model.Then due to the observation that the shapes of gas regions are different from most rigid moving objects, we modify the Features From Accelerated Segment Test (FAST) algorithm and use the modified FAST (mFAST) features to describe each connected component. In view of the fact that the statistical property of the mFAST features extracted from gas regions is different from that of other motion regions, we propose the Pixel-Per-Points (PPP) condition to further select candidate connected components.Experimental results show that the algorithm is able to effectively suppress most strong motion disturbances and achieve real-time leaking gas detection.
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Strangeness production in deep inelastic muon nucleon scattering at 280 GeV
NASA Astrophysics Data System (ADS)
Arneodo, M.; Arvidson, A.; Aubert, J. J.; Badelek, B.; Beaufays, J.; Bee, C. P.; Benchouk, C.; Berghoff, G.; Bird, I.; Blum, D.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S.; Brück, H.; Calen, H.; Chima, J. S.; Ciborowski, J.; Clifft, R.; Coignet, G.; Combley, F.; Coughlan, J.; D'Agostini, G.; Dahlgren, S.; Dengler, F.; Derado, I.; Dreyer, T.; Drees, J.; Düren, M.; Eckhardt, V.; Edwards, A.; Edwards, M.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Gabathuler, E.; Gajewski, J.; Gamet, R.; Gayler, J.; Geddes, N.; Grafström, P.; Grard, F.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Jaffré, M.; Jacholkowska, A.; Janata, F.; Jancso, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Malecki, P.; Manz, A.; Maselli, S.; Mohr, W.; Montanet, F.; Montgomery, H. E.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Pascaud, C.; Pawlik, B.; Payre, P.; Peroni, C.; Peschel, H.; Pessard, H.; Pettingale, J.; Pietrzyk, B.; Pönsgen, B.; Pötsch, M.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Sandacz, A.; Scheer, M.; Schlagböhmer, A.; Schiemann, H.; Schmifz, N.; Schneegans, M.; Scholz, M.; Schröder, T.; Schouten, M.; Schultze, K.; Sloan, T.; Stier, H. E.; Studt, M.; Taylor, G. N.; Thénard, J. M.; Thompson, J. C.; de La Torre, A.; Toth, J.; Urban, L.; Wallucks, W.; Whalley, M.; Wheeler, S.; Williams, W. S. C.; Wimpenny, S. J.; Windmolders, R.
1987-09-01
The production of strange particles has been studied in a 280 GeV muon nucleon scattering experiment with acceptance and particle identification over a large kinematical range. The data show that at large values of x Bj the interactions take place mostly on a u valence quark in agreement with the basic quarkparton model predictions. This feature results in a strong forward-backward asymmetry in the distribution of strangeness along the rapidity axis. The data are compatible with a strange to non-strange quark suppression factor of ≈0.3 and with a strong suppression of strange diquarks. The distributions of K + K - pairs show that the two kaons are preferentially produced at neighbouring values of rapidity.
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Suppressive mechanisms in visual motion processing: From perception to intelligence.
Tadin, Duje
2015-10-01
Perception operates on an immense amount of incoming information that greatly exceeds the brain's processing capacity. Because of this fundamental limitation, the ability to suppress irrelevant information is a key determinant of perceptual efficiency. Here, I will review a series of studies investigating suppressive mechanisms in visual motion processing, namely perceptual suppression of large, background-like motions. These spatial suppression mechanisms are adaptive, operating only when sensory inputs are sufficiently robust to guarantee visibility. Converging correlational and causal evidence links these behavioral results with inhibitory center-surround mechanisms, namely those in cortical area MT. Spatial suppression is abnormally weak in several special populations, including the elderly and individuals with schizophrenia-a deficit that is evidenced by better-than-normal direction discriminations of large moving stimuli. Theoretical work shows that this abnormal weakening of spatial suppression should result in motion segregation deficits, but direct behavioral support of this hypothesis is lacking. Finally, I will argue that the ability to suppress information is a fundamental neural process that applies not only to perception but also to cognition in general. Supporting this argument, I will discuss recent research that shows individual differences in spatial suppression of motion signals strongly predict individual variations in IQ scores. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.
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Dynamic interactions of the cortical networks during thought suppression.
Aso, Toshihiko; Nishimura, Kazuo; Kiyonaka, Takashi; Aoki, Takaaki; Inagawa, Michiyo; Matsuhashi, Masao; Tobinaga, Yoshikazu; Fukuyama, Hidenao
2016-08-01
Thought suppression has spurred extensive research in clinical and preclinical fields, particularly with regard to the paradoxical aspects of this behavior. However, the involvement of the brain's inhibitory system in the dynamics underlying the continuous effort to suppress thoughts has yet to be clarified. This study aims to provide a unified perspective for the volitional suppression of internal events incorporating the current understanding of the brain's inhibitory system. Twenty healthy volunteers underwent functional magnetic resonance imaging while they performed thought suppression blocks alternating with visual imagery blocks. The whole dataset was decomposed by group-independent component analysis into 30 components. After discarding noise components, the 20 valid components were subjected to further analysis of their temporal properties including task-relatedness and between-component residual correlation. Combining a long task period and a data-driven approach, we observed a right-side-dominant, lateral frontoparietal network to be strongly suppression related. This network exhibited increased fluctuation during suppression, which is compatible with the well-known difficulty of suppression maintenance. Between-network correlation provided further insight into the coordinated engagement of the executive control and dorsal attention networks, as well as the reciprocal activation of imagery-related components, thus revealing neural substrates associated with the rivalry between intrusive thoughts and the suppression process.
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Attention and competition in figure-ground perception.
Peterson, Mary A; Salvagio, Elizabeth
2009-01-01
What are the roles of attention and competition in determining where objects lie in the visual field, a phenomenon known as figure-ground perception? In this chapter, we review evidence that attention and other high-level factors such as familiarity affect figure-ground perception, and we discuss models that implement these effects. Next, we consider the Biased Competition Model of Attention in which attention is used to resolve the competition for neural representation between two nearby stimuli; in this model the response to the stimulus that loses the competition is suppressed. In the remainder of the chapter we discuss recent behavioral evidence that figure-ground perception entails between-object competition in which the response to the shape of the losing competitor is suppressed. We also describe two experiments testing whether more attention is drawn to resolve greater figure-ground competition, as would be expected if the Biased Competition Model of Attention extends to figure-ground perception. In these experiments we find that responses to targets on the location of a losing strong competitor are slowed, consistent with the idea that the location of the losing competitor is suppressed, but responses to targets on the winning competitor are not speeded, which is inconsistent with the hypothesis that attention is used to resolve figure-ground competition. In closing, we discuss evidence that attention can operate by suppression as well as by facilitation.
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Coronal Seismology of Flare-Excited Standing Slow-Mode Waves Observed by SDO/AIA
NASA Astrophysics Data System (ADS)
Wang, Tongjiang; Ofman, Leon; Davila, Joseph M.
2016-05-01
Flare-excited longitudinal intensity oscillations in hot flaring loops have been recently detected by SDO/AIA in 94 and 131 Å bandpasses. Based on the interpretation in terms of a slow-mode wave, quantitative evidence of thermal conduction suppression in hot (>9 MK) loops has been obtained for the first time from measurements of the polytropic index and phase shift between the temperature and density perturbations (Wang et al. 2015, ApJL, 811, L13). This result has significant implications in two aspects. One is that the thermal conduction suppression suggests the need of greatly enhanced compressive viscosity to interpret the observed strong wave damping. The other is that the conduction suppression provides a reasonable mechanism for explaining the long-duration events where the thermal plasma is sustained well beyond the duration of impulsive hard X-ray bursts in many flares, for a time much longer than expected by the classical Spitzer conductive cooling. In this study, we model the observed standing slow-mode wave in Wang et al. (2015) using a 1D nonlinear MHD code. With the seismology-derived transport coefficients for thermal conduction and compressive viscosity, we successfully simulate the oscillation period and damping time of the observed waves. Based on the parametric study of the effect of thermal conduction suppression and viscosity enhancement on the observables, we discuss the inversion scheme for determining the energy transport coefficients by coronal seismology.
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Robust Small Target Co-Detection from Airborne Infrared Image Sequences.
Gao, Jingli; Wen, Chenglin; Liu, Meiqin
2017-09-29
In this paper, a novel infrared target co-detection model combining the self-correlation features of backgrounds and the commonality features of targets in the spatio-temporal domain is proposed to detect small targets in a sequence of infrared images with complex backgrounds. Firstly, a dense target extraction model based on nonlinear weights is proposed, which can better suppress background of images and enhance small targets than weights of singular values. Secondly, a sparse target extraction model based on entry-wise weighted robust principal component analysis is proposed. The entry-wise weight adaptively incorporates structural prior in terms of local weighted entropy, thus, it can extract real targets accurately and suppress background clutters efficiently. Finally, the commonality of targets in the spatio-temporal domain are used to construct target refinement model for false alarms suppression and target confirmation. Since real targets could appear in both of the dense and sparse reconstruction maps of a single frame, and form trajectories after tracklet association of consecutive frames, the location correlation of the dense and sparse reconstruction maps for a single frame and tracklet association of the location correlation maps for successive frames have strong ability to discriminate between small targets and background clutters. Experimental results demonstrate that the proposed small target co-detection method can not only suppress background clutters effectively, but also detect targets accurately even if with target-like interference.
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Cerebral TOF Angiography at 7T: Impact of B1+ Shimming with a 16-Channel Transceiver Array
Schmitter, Sebastian; Wu, Xiaoping; Adriany, Gregor; Auerbach, Edward J.; Uğurbil, Kâmil; Van de Moortele, Pierre-François
2014-01-01
Purpose Time-of-flight (TOF) MR imaging is clinically among the most common cerebral non-contrast enhanced MR angiography techniques allowing for high spatial resolution. As shown by several groups TOF contrast significantly improves at ultra-high field (UHF) of B0=7T, however, spatially varying transmit B1 (B1+) fields at 7T reduce TOF contrast uniformity, typically resulting in sub-optimal contrast and reduced vessel conspicuity in the brain periphery. Methods Using a 16-channel B1+ shimming system we compare different dynamically applied B1+ phase shimming approaches on the RF excitation to improve contrast homogeneity for a (0.5 mm)3 resolution multi-slab TOF acquisition. In addition, B1+ shimming applied on the venous saturation pulse was investigated to improve venous suppression, subcutaneous fat signal reduction and enhanced background suppression originating from MT effect. Results B1+ excitation homogeneity was improved by a factor 2.2 to 2.6 on average depending on the shimming approach, compared to a standard CP-like phase setting, leading to improved vessel conspicuity particularly in the periphery. Stronger saturation, higher fat suppression and improved background suppression were observed when dynamically applying B1+ shimming on the venous saturation pulse. Conclusion B1+ shimming can significantly improve high resolution TOF vascular investigations at UHF, holding strong promise for non contrast-enhanced clinical applications. PMID:23640915
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Applying Magneto-rheology to Reduce Blood Viscosity and Suppress Turbulence to Prevent Heart Attacks
NASA Astrophysics Data System (ADS)
Tao, R.
Heart attacks are the leading causes of death in USA. Research indicates one common thread, high blood viscosity, linking all cardiovascular diseases. Turbulence in blood circulation makes different regions of the vasculature vulnerable to development of atherosclerotic plaque. Turbulence is also responsible for systolic ejection murmurs and places heavier workload on heart, a possible trigger of heart attacks. Presently, neither medicine nor method is available to suppress turbulence. The only method to reduce the blood viscosity is to take medicine, such as aspirin. However, using medicine to reduce the blood viscosity does not help suppressing turbulence. In fact, the turbulence gets worse as the Reynolds number goes up with the viscosity reduction by the medicine. Here we report our new discovery: application of a strong magnetic field to blood along its flow direction, red blood cells are polarized in the magnetic field and aggregated into short chains along the flow direction. The blood viscosity becomes anisotropic: Along the flow direction the viscosity is significantly reduced, but in the directions perpendicular to the flow the viscosity is considerably increased. In this way, the blood flow becomes laminar, turbulence is suppressed, the blood circulation is greatly improved, and the risk for heart attacks is reduced. While these effects are not permanent, they last for about 24 hours after one magnetic therapy treatment.
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Internal Gravity Waves in the Magnetized Solar Atmosphere. I. Magnetic Field Effects
DOE Office of Scientific and Technical Information (OSTI.GOV)
Vigeesh, G.; Steiner, O.; Jackiewicz, J., E-mail: vigeesh@leibniz-kis.de
Observations of the solar atmosphere show that internal gravity waves are generated by overshooting convection, but are suppressed at locations of magnetic flux, which is thought to be the result of mode conversion into magnetoacoustic waves. Here, we present a study of the acoustic-gravity wave spectrum emerging from a realistic, self-consistent simulation of solar (magneto)convection. A magnetic field free, hydrodynamic simulation and a magnetohydrodynamic (MHD) simulation with an initial, vertical, homogeneous field of 50 G flux density were carried out and compared with each other to highlight the effect of magnetic fields on the internal gravity wave propagation in themore » Sun’s atmosphere. We find that the internal gravity waves are absent or partially reflected back into the lower layers in the presence of magnetic fields and argue that the suppression is due to the coupling of internal gravity waves to slow magnetoacoustic waves still within the high- β region of the upper photosphere. The conversion to Alfvén waves is highly unlikely in our model because there is no strongly inclined magnetic field present. We argue that the suppression of internal waves observed within magnetic flux concentrations may also be due to nonlinear breaking of internal waves due to vortex flows that are ubiquitously present in the upper photosphere and the chromosphere.« less
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Ono, Kazuhiko; Nimura, Satoshi; Nishinakagawa, Takuya; Hideshima, Yuko; Enjyoji, Munechika; Nabeshima, Kazuki; Nakashima, Manabu
2014-03-01
Sodium 4-phenylbutyrate (PBA) exhibits anti-inflammatory effects by suppressing nuclear factor-κB (NF-κB) activation. In the present study, the effects of PBA on a mouse model of dextran sulfate sodium (DSS)-induced colitis were investigated. The therapeutic efficacy of PBA (150 mg/kg body weight) in DSS-induced colitis was assessed based on the disease activity index (DAI), colon length, the production of inflammatory cytokines and histopathological examination. The results showed an increase in the median survival time in the PBA-treated group compared with that of the untreated DSS control group. DAI scores were lower in the PBA-treated group than in the DSS control group during the 12 days of the experiment. Additionally, PBA treatment inhibited shortening of the colon and the production of the inflammatory cytokines tumor necrosis factor-α, interleukin-1β and IL-6, which were measured in the colonic lavage fluids. Histopathological examination of the DSS control group showed diffused clusters of chronic inflammatory cells infiltrating the lamina propria, partial exfoliation of the surface epithelium and decreased numbers of mature goblet cells. By contrast, in the PBA-treated group the histopathological findings were the same as those of the normal healthy controls. These results suggest that PBA strongly prevents DSS-induced colitis by suppressing the mechanisms involved in its pathogenesis.
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Nawrotzki, Raphael J; Riosmena, Fernando; Hunter, Lori M; Runfola, Daniel M
2015-11-01
Increasing rates of climate migration may be of economic and national concern to sending and destination countries. It has been argued that social networks - the ties connecting an origin and destination - may operate as "migration corridors" with the potential to strongly facilitate climate change-related migration. This study investigates whether social networks at the household and community levels amplify or suppress the impact of climate change on international migration from rural Mexico. A novel set of 15 climate change indices was generated based on daily temperature and precipitation data for 214 weather stations across Mexico. Employing geostatistical interpolation techniques, the climate change values were linked to 68 rural municipalities for which sociodemographic data and detailed migration histories were available from the Mexican Migration Project. Multi-level discrete-time event-history models were used to investigate the effect of climate change on international migration between 1986 and 1999. At the household level, the effect of social networks was approximated by comparing the first to the last move, assuming that through the first move a household establishes internal social capital. At the community level, the impact of social capital was explored through interactions with a measure of the proportion of adults with migration experience. The results show that rather than amplifying , social capital may suppress the sensitivity of migration to climate triggers, suggesting that social networks could facilitate climate change adaptation in place.
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Suppression of Biodynamic Interference by Adaptive Filtering
NASA Technical Reports Server (NTRS)
Velger, M.; Merhav, S. J.; Grunwald, A. J.
1984-01-01
Preliminary experimental results obtained in moving base simulator tests are presented. Both for pursuit and compensatory tracking tasks, a strong deterioration in tracking performance due to biodynamic interference is found. The use of adaptive filtering is shown to substantially alleviate these effects, resulting in a markedly improved tracking performance and reduction in task difficulty. The effect of simulator motion and of adaptive filtering on human operator describing functions is investigated. Adaptive filtering is found to substantially increase pilot gain and cross-over frequency, implying a more tight tracking behavior. The adaptive filter is found to be effective in particular for high-gain proportional dynamics, low display forcing function power and for pursuit tracking task configurations.
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Pan, M H; Lin-Shiau, S Y; Ho, C T; Lin, J H; Lin, J K
2000-02-15
We investigated the inhibition of IkappaB kinase (IKK) activity in lipopolysaccharide (LPS)-activated murine macrophages (RAW 264.7 cell line) by various polyphenols including (-)-epigallocatechin-3-gallate, theaflavin, a mixture of theaflavin-3 gallate and theaflavin-3'-gallate, theaflavin-3,3'-digallate (TF-3), pyrocyanidin B-3, casuarinin, geraniin, and penta-O-galloyl-beta-D-glucose (5GG). TF-3 inhibited IKK activity in activated macrophages more strongly than did the other polyphenols. TF-3 strongly inhibited both IKK1 and IKK2 activity and prevented the degradation of IkappaBalpha and IkappaBbeta in activated macrophage cells. The results suggested that the inhibition of IKK activity by TF-3 could occur by a direct effect on IKKs or on upstream events in the signal transduction pathway. Furthermore, geraniin, 5GG, and TF-3 all blocked phosphorylation of IKB from the cytosolic fraction, inhibited nuclear factor-kappaB (NFkappaB) activity, and inhibited increases in inducible nitric oxide synthase levels in activated macrophages. These results suggest that TF-3 may exert its anti-inflammatory and cancer chemopreventive actions by suppressing the activation of NFkappaB through inhibition of IKK activity.
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Magnetic neutron star cooling and microphysics
NASA Astrophysics Data System (ADS)
Potekhin, A. Y.; Chabrier, G.
2018-01-01
Aims: We study the relative importance of several recent updates of microphysics input to the neutron star cooling theory and the effects brought about by superstrong magnetic fields of magnetars, including the effects of the Landau quantization in their crusts. Methods: We use a finite-difference code for simulation of neutron-star thermal evolution on timescales from hours to megayears with an updated microphysics input. The consideration of short timescales (≲1 yr) is made possible by a treatment of the heat-blanketing envelope without the quasistationary approximation inherent to its treatment in traditional neutron-star cooling codes. For the strongly magnetized neutron stars, we take into account the effects of Landau quantization on thermodynamic functions and thermal conductivities. We simulate cooling of ordinary neutron stars and magnetars with non-accreted and accreted crusts and compare the results with observations. Results: Suppression of radiative and conductive opacities in strongly quantizing magnetic fields and formation of a condensed radiating surface substantially enhance the photon luminosity at early ages, making the life of magnetars brighter but shorter. These effects together with the effect of strong proton superfluidity, which slows down the cooling of kiloyear-aged neutron stars, can explain thermal luminosities of about a half of magnetars without invoking heating mechanisms. Observed thermal luminosities of other magnetars are still higher than theoretical predictions, which implies heating, but the effects of quantizing magnetic fields and baryon superfluidity help to reduce the discrepancy.
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Mechanisms underlying a thalamocortical transformation during active tactile sensation
Gutnisky, Diego Adrian; Yu, Jianing; Hires, Samuel Andrew; To, Minh-Son; Svoboda, Karel
2017-01-01
During active somatosensation, neural signals expected from movement of the sensors are suppressed in the cortex, whereas information related to touch is enhanced. This tactile suppression underlies low-noise encoding of relevant tactile features and the brain’s ability to make fine tactile discriminations. Layer (L) 4 excitatory neurons in the barrel cortex, the major target of the somatosensory thalamus (VPM), respond to touch, but have low spike rates and low sensitivity to the movement of whiskers. Most neurons in VPM respond to touch and also show an increase in spike rate with whisker movement. Therefore, signals related to self-movement are suppressed in L4. Fast-spiking (FS) interneurons in L4 show similar dynamics to VPM neurons. Stimulation of halorhodopsin in FS interneurons causes a reduction in FS neuron activity and an increase in L4 excitatory neuron activity. This decrease of activity of L4 FS neurons contradicts the "paradoxical effect" predicted in networks stabilized by inhibition and in strongly-coupled networks. To explain these observations, we constructed a model of the L4 circuit, with connectivity constrained by in vitro measurements. The model explores the various synaptic conductance strengths for which L4 FS neurons actively suppress baseline and movement-related activity in layer 4 excitatory neurons. Feedforward inhibition, in concert with recurrent intracortical circuitry, produces tactile suppression. Synaptic delays in feedforward inhibition allow transmission of temporally brief volleys of activity associated with touch. Our model provides a mechanistic explanation of a behavior-related computation implemented by the thalamocortical circuit. PMID:28591219
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Watts, Alain; Gritton, Howard J; Sweigart, Jamie; Poe, Gina R
2012-09-26
Rapid eye movement (REM) sleep enhances hippocampus-dependent associative memory, but REM deprivation has little impact on striatum-dependent procedural learning. Antidepressant medications are known to inhibit REM sleep, but it is not well understood if antidepressant treatments impact learning and memory. We explored antidepressant REM suppression effects on learning by training animals daily on a spatial task under familiar and novel conditions, followed by training on a procedural memory task. Daily treatment with the antidepressant and norepinephrine reuptake inhibitor desipramine (DMI) strongly suppressed REM sleep in rats for several hours, as has been described in humans. We also found that DMI treatment reduced the spindle-rich transition-to-REM sleep state (TR), which has not been previously reported. DMI REM suppression gradually weakened performance on a once familiar hippocampus-dependent maze (reconsolidation error). DMI also impaired learning of the novel maze (consolidation error). Unexpectedly, learning of novel reward positions and memory of familiar positions were equally and oppositely correlated with amounts of TR sleep. Conversely, DMI treatment enhanced performance on a separate striatum-dependent, procedural T-maze task that was positively correlated with the amounts of slow-wave sleep (SWS). Our results suggest that learning strategy switches in patients taking REM sleep-suppressing antidepressants might serve to offset sleep-dependent hippocampal impairments to partially preserve performance. State-performance correlations support a model wherein reconsolidation of hippocampus-dependent familiar memories occurs during REM sleep, novel information is incorporated and consolidated during TR, and dorsal striatum-dependent procedural learning is augmented during SWS.
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Watts, Alain; Gritton, Howard J.; Sweigart, Jamie
2012-01-01
Rapid eye movement (REM) sleep enhances hippocampus-dependent associative memory, but REM deprivation has little impact on striatum-dependent procedural learning. Antidepressant medications are known to inhibit REM sleep, but it is not well understood if antidepressant treatments impact learning and memory. We explored antidepressant REM suppression effects on learning by training animals daily on a spatial task under familiar and novel conditions, followed by training on a procedural memory task. Daily treatment with the antidepressant and norepinephrine reuptake inhibitor desipramine (DMI) strongly suppressed REM sleep in rats for several hours, as has been described in humans. We also found that DMI treatment reduced the spindle-rich transition-to-REM sleep state (TR), which has not been previously reported. DMI REM suppression gradually weakened performance on a once familiar hippocampus-dependent maze (reconsolidation error). DMI also impaired learning of the novel maze (consolidation error). Unexpectedly, learning of novel reward positions and memory of familiar positions were equally and oppositely correlated with amounts of TR sleep. Conversely, DMI treatment enhanced performance on a separate striatum-dependent, procedural T-maze task that was positively correlated with the amounts of slow-wave sleep (SWS). Our results suggest that learning strategy switches in patients taking REM sleep-suppressing antidepressants might serve to offset sleep-dependent hippocampal impairments to partially preserve performance. State–performance correlations support a model wherein reconsolidation of hippocampus-dependent familiar memories occurs during REM sleep, novel information is incorporated and consolidated during TR, and dorsal striatum-dependent procedural learning is augmented during SWS. PMID:23015432
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The Distress Disclosure Index: a research review and multitrait-multimethod examination.
Kahn, Jeffrey H; Hucke, Brandy E; Bradley, Allyson M; Glinski, Austin J; Malak, Brittany L
2012-01-01
The Distress Disclosure Index (DDI; J. H. Kahn & R. M. Hessling, 2001) is a brief self-report measure of one's tendency to disclose personally distressing information. The purpose of this article was to summarize what is known about the DDI, present new validity evidence, and make recommendations for use of the DDI. This article reviews research on the DDI from the past decade that indicates that distress disclosure is associated with well-being, professional help-seeking attitudes and intentions, and success in brief psychotherapy. On the basis of the reviewed literature, the authors report a reliability generalization study of DDI scores that strongly supports the internal consistency and test-retest reliability of DDI scores, and they review criterion-related and construct validity evidence. Next, the authors present a new multitrait-multimethod validity study of the DDI. Participants (N = 153) and peer informants (N = 153)--one per participant--completed paper-and-pencil questionnaire packets. Convergent validity of self-reported DDI scores was supported by a strong association with self-reports of emotional self-disclosure in response to a specific, unpleasant event, and self- and peer reports on the DDI were moderately correlated. DDI scores were not strongly associated with cognitive reappraisal and ambivalence over emotional expression, thus supporting discriminant validity. DDI scores were strongly associated with expressive suppression, and correlations between DDI scores and affect, depression symptoms, coping, and emotional expressivity were similar to those found with expressive suppression. The authors offer possible hypotheses explaining the overlap between distress disclosure and expressive suppression and present recommendations for future use of the DDI. (c) 2012 APA, all rights reserved.
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Paz, M. L.; Leoni, J.
2016-01-01
Sunlight, composed of different types of radiation, including ultraviolet wavelengths, is an essential source of light and warmth for life on earth but has strong negative effects on human health, such as promoting the malignant transformation of skin cells and suppressing the ability of the human immune system to efficiently detect and attack malignant cells. UV-induced immunosuppression has been extensively studied since it was first described by Dr. Kripke and Dr. Fisher in the late 1970s. However, skin exposure to sunlight has not only this and other unfavorable effects, for example, mutagenesis and carcinogenesis, but also a positive one: the induction of Vitamin D synthesis, which performs several roles within the immune system in addition to favoring bone homeostasis. The impact of low levels of UV exposure on the immune system has not been fully reported yet, but it bears interesting differences with the suppressive effect of high levels of UV radiation, as shown by some recent studies. The aim of this article is to put some ideas in perspective and pose some questions within the field of photoimmunology based on established and new information, which may lead to new experimental approaches and, eventually, to a better understanding of the effects of sunlight on the human immune system. PMID:28070504
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McDonald, Nicholas D; Rands, Sean A; Hill, Francesca; Elder, Charlotte; Ioannou, Christos C
2016-09-01
Whether individual behavior in social settings correlates with behavior when individuals are alone is a fundamental question in collective behavior. However, evidence for whether behavior correlates across asocial and social settings is mixed, and no study has linked observed trends with underlying mechanisms. Consistent differences between individuals in boldness, which describes willingness to accept reward over risk, are likely to be under strong selection pressure. By testing three-spined sticklebacks (Gasterosteus aculeatus) in a risky foraging task alone and repeatedly in shoals, we demonstrate that the expression of boldness in groups is context-specific. Whereas personality is repeatable in a low-risk behavior (leaving a refuge), the collectively made consensus decision to then cross the arena outweighs leadership by bolder individuals, explaining the suppression of personality in this context. However, despite this social coordination, bolder individuals were still more likely to feed. Habituation and satiation over repeated trials degrade the effect of personality on leaving the refuge and also whether crossing the arena is a collective decision. The suppression of personality in groups suggests that individual risk-taking tendency may rarely represent actual risk in social settings, with implications for the evolution and ecology of personality variation.
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Magnetic suppression of turbulence and the star formation activity of molecular clouds
NASA Astrophysics Data System (ADS)
Zamora-Avilés, Manuel; Vázquez-Semadeni, Enrique; Körtgen, Bastian; Banerjee, Robi; Hartmann, Lee
2018-03-01
We present magnetohydrodynamic simulations aimed at studying the effect of the magnetic suppression of turbulence (generated through various instabilities during the formation of molecular clouds by converging) on the subsequent star formation (SF) activity. We study four magnetically supercritical models with magnetic field strengths B = 0, 1, 2, and 3 μG (corresponding to mass-to-flux ratios of ∞, 4.76, 2.38, and 1.59 times the critical value), with the magnetic field, initially being aligned with the flows. We find that, for increasing magnetic field strength, the clouds formed tend to be more massive, denser, less turbulent, and with higher SF activity. This causes the onset of SF activity in the non-magnetic or more weakly magnetized cases to be delayed by a few Myr in comparison to the more strongly magnetized cases. We attribute this behaviour to the suppression of the non-linear thin shell instability (NTSI) by the magnetic field, previously found by Heitsch and coworkers. This result is contrary to the standard notion that the magnetic field provides support to the clouds, thus reducing their star formation rate. However, our result is a completely non-linear one, and could not be foreseen from simple linear considerations.
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Consensus and experience trump leadership, suppressing individual personality during social foraging
McDonald, Nicholas D.; Rands, Sean A.; Hill, Francesca; Elder, Charlotte; Ioannou, Christos C.
2016-01-01
Whether individual behavior in social settings correlates with behavior when individuals are alone is a fundamental question in collective behavior. However, evidence for whether behavior correlates across asocial and social settings is mixed, and no study has linked observed trends with underlying mechanisms. Consistent differences between individuals in boldness, which describes willingness to accept reward over risk, are likely to be under strong selection pressure. By testing three-spined sticklebacks (Gasterosteus aculeatus) in a risky foraging task alone and repeatedly in shoals, we demonstrate that the expression of boldness in groups is context-specific. Whereas personality is repeatable in a low-risk behavior (leaving a refuge), the collectively made consensus decision to then cross the arena outweighs leadership by bolder individuals, explaining the suppression of personality in this context. However, despite this social coordination, bolder individuals were still more likely to feed. Habituation and satiation over repeated trials degrade the effect of personality on leaving the refuge and also whether crossing the arena is a collective decision. The suppression of personality in groups suggests that individual risk-taking tendency may rarely represent actual risk in social settings, with implications for the evolution and ecology of personality variation. PMID:27652342
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Choi, Eun-Sun; Cho, Sung-Dae; Shin, Ji-Ae; Kwon, Ki Han; Cho, Nam-Pyo; Shim, Jung-Hyun
2012-10-01
For thousands of years in Asia, Althaea rosea Cavanil (ARC) and Plantago major L. (PML) have been used as powerful non-toxic therapeutic agents that inhibit inflammation. However, the anticancer mechanisms and molecular targets of ARC and PML are poorly understood, particularly in epidermal growth factor (EGF)-induced neoplastic cell transformation. The aim of this study was to evaluate the chemopreventive effects and mechanisms of the methanol extracts from ARC (MARC) and PML (MPML) in EGF-induced neoplastic cell transformation of JB6 P+ mouse epidermal cells using an MTS assay, anchorage-independent cell transformation assay and western blotting. Our results showed that MARC and MPML significantly suppressed neoplastic cell transformation by inhibiting the kinase activity of the EGF receptor (EGFR). The activation of EGFR by EGF was suppressed by MARC and MPML treatment in EGFR(+/+) cells, but not in EGFR(-/-) cells. In addition, MARC and MPML inhibited EGF-induced cell proliferation in EGFR-expressing murine embryonic fibroblasts (EGFR(+/+)). These results strongly indicate that EGFR targeting by MARC and MPML may be a good strategy for chemopreventive or chemotherapeutic applications.
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del Priore, Lucía; Pigozzi, María I
2015-01-01
In the zebra finch, 2 alternative morphs regarding centromere position were described for chromosome 6. This polymorphism was interpreted to be the result of a pericentric inversion, but other causes of the centromere repositioning were not ruled out. We used immunofluorescence localization to examine the distribution of MLH1 foci on synaptonemal complexes to test the prediction that pericentric inversions cause synaptic irregularities and/or crossover suppression in heterozygotes. We found complete suppression of crossing over in the region involved in the rearrangement in male and female heterozygotes. In contrast, the same region showed high levels of crossing over in homozygotes for the acrocentric form of this chromosome. No inversion loops or synaptic irregularities were detected along bivalent 6 in heterozygotes suggesting that heterologous pairing is achieved during zygotene or early pachytene. Altogether these findings strongly indicate that the polymorphic chromosome 6 originated by a pericentric inversion. Since inversions are common rearrangements in karyotypic evolution in birds, it seems likely that early heterologous pairing could help to fix these rearrangements, preventing crossing overs in heterozygotes and their deleterious effects on fertility. © 2015 S. Karger AG, Basel.
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Simulation of MST tokamak discharges with resonant magnetic perturbations
NASA Astrophysics Data System (ADS)
Cornille, B. S.; Sovinec, C. R.; Chapman, B. E.; Dubois, A.; McCollam, K. J.; Munaretto, S.
2016-10-01
Nonlinear MHD modeling of MST tokamak plasmas with an applied resonant magnetic perturbation (RMP) reveals degradation of flux surfaces that may account for the experimentally observed suppression of runaway electrons with the RMP. Runaway electrons are routinely generated in MST tokamak discharges with low plasma density. When an m = 3 RMP is applied these electrons are strongly suppressed, while an m = 1 RMP of comparable amplitude has little effect. The computations are performed using the NIMROD code and use reconstructed equilibrium states of MST tokamak plasmas with q (0) < 1 and q (a) = 2.2 . Linear computations show that the (1 , 1) -kink and (2 , 2) -tearing modes are unstable, and nonlinear simulations produce sawtoothing with a period of approximately 0.5 ms, which is comparable to the period of MHD activity observed experimentally. Adding an m = 3 RMP in the computation degrades flux surfaces in the outer region of the plasma, while no degradation occurs with an m = 1 RMP. The outer flux surface degradation with the m = 3 RMP, combined with the sawtooth-induced distortion of flux surfaces in the core, may account for the observed suppression of runaway electrons. Work supported by DOE Grant DE-FC02-08ER54975.
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Wilby, Andrew; Anglin, Linda Anderson; Nesbit, Christopher M
2013-01-01
The prediction of pest-control functioning by multi-predator communities is hindered by the non-additive nature of species functioning. Such non-additivity, commonly termed an emergent multi-predator effect, is known to be affected by elements of the ecological context, such as the structure and composition of vegetation, in addition to the traits of the predators themselves. Here we report mesocosm experiments designed to test the influence of plant density and species composition (wheat monoculture or wheat and faba bean polyculture) on the emergence of multi-predator effects between Adalia bipunctata and Chrysoperla carnea, in their suppression of populations of the aphid Metopolophium dirhodum. The mesocosm experiments were followed by a series of behavioural observations designed to identify how interactions among predators are modified by plant species composition and whether these effects are consistent with the observed influence of plant species composition on aphid population suppression. Although plant density was shown to have no influence on the multi-predator effect on aphid population growth, plant composition had a marked effect. In wheat monoculture, Adalia and Chrysoperla mixed treatments caused greater suppression of M. dirhodum populations than expected. However this positive emergent effect was reversed to a negative multi-predator effect in wheat and faba bean polyculture. The behavioural observations revealed that although dominant individuals did not respond to the presence of faba bean plants, the behaviour of sub-dominants was affected markedly, consistent with their foraging for extra-floral nectar produced by the faba bean. This interaction between plant composition and predator community composition on the foraging behaviour of sub-dominants is thought to underlie the observed effect of plant composition on the multi-predator effect. Thus, the emergence of multi-predator effects is shown to be strongly influenced by plant species composition, mediated, in this case, by the provision of extra-floral nectar by one of the plant species.
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Slow Noncollinear Coulomb Scattering in the Vicinity of the Dirac Point in Graphene.
König-Otto, J C; Mittendorff, M; Winzer, T; Kadi, F; Malic, E; Knorr, A; Berger, C; de Heer, W A; Pashkin, A; Schneider, H; Helm, M; Winnerl, S
2016-08-19
The Coulomb scattering dynamics in graphene in energetic proximity to the Dirac point is investigated by polarization resolved pump-probe spectroscopy and microscopic theory. Collinear Coulomb scattering rapidly thermalizes the carrier distribution in k directions pointing radially away from the Dirac point. Our study reveals, however, that, in almost intrinsic graphene, full thermalization in all directions relying on noncollinear scattering is much slower. For low photon energies, carrier-optical-phonon processes are strongly suppressed and Coulomb mediated noncollinear scattering is remarkably slow, namely on a ps time scale. This effect is very promising for infrared and THz devices based on hot carrier effects.
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Drag suppression in anomalous chiral media
Sadofyev, Andrey V.; Yin, Yi
2016-06-01
We study a heavy impurity moving longitudinal with the direction of an external magnetic field in an anomalous chiral medium. Such system would carry a non-dissipative current of chiral magnetic effect associated with the anomaly. We show, by generalizing Landau's criterion for super fluidity, that the "anomalous component" which gives rise to the anomalous transport will not contribute to the drag experienced by an impurity. We argue on a very general basis that those systems with a strong magnetic field would exhibit an interesting transport phenomenon$-$the motion of the heavy impurity is frictionless, in analogy to the case of amore » super fluid. Finally, we demonstrate and confirm our general results with two complementary examples: weakly coupled chiral fermion gases and strongly interacting chiral liquids.« less
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Orbital selective pairing and gap structures of iron-based superconductors
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kreisel, Andreas; Andersen, Brian M.; Sprau, P. O.
We discuss the in uence on spin-fluctuation pairing theory of orbital selective strong correlation effects in Fe-based superconductors, particularly Fe chalcogenide systems. We propose that a key ingredient for an improved itinerant pairing theory is orbital selectivity, i.e., incorporating the reduced coherence of quasiparticles occupying specific orbital states. This modifies the usual spin-fluctuation via suppression of pair scattering processes involving those less coherent states and results in orbital selective Cooper pairing of electrons in the remaining states. We show that this paradigm yields remarkably good agreement with the experimentally observed anisotropic gap structures in both bulk and monolayer FeSe, asmore » well as LiFeAs, indicating that orbital selective Cooper pairing plays a key role in the more strongly correlated iron-based superconductors.« less
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Orbital selective pairing and gap structures of iron-based superconductors
Kreisel, Andreas; Andersen, Brian M.; Sprau, P. O.; ...
2017-05-08
We discuss the in uence on spin-fluctuation pairing theory of orbital selective strong correlation effects in Fe-based superconductors, particularly Fe chalcogenide systems. We propose that a key ingredient for an improved itinerant pairing theory is orbital selectivity, i.e., incorporating the reduced coherence of quasiparticles occupying specific orbital states. This modifies the usual spin-fluctuation via suppression of pair scattering processes involving those less coherent states and results in orbital selective Cooper pairing of electrons in the remaining states. We show that this paradigm yields remarkably good agreement with the experimentally observed anisotropic gap structures in both bulk and monolayer FeSe, asmore » well as LiFeAs, indicating that orbital selective Cooper pairing plays a key role in the more strongly correlated iron-based superconductors.« less
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Driving-induced population trapping and linewidth narrowing via the quantum Zeno effect
NASA Astrophysics Data System (ADS)
Christensen, Charles N.; Iles-Smith, Jake; Petersen, Torkil S.; Mørk, Jesper; McCutcheon, Dara P. S.
2018-06-01
We investigate the suppression of spontaneous emission from a driven three-level system embedded in an optical cavity via a manifestation of the quantum Zeno effect. Strong resonant coupling of the lower two levels to an external optical field results in a decrease of the decay rate of the third upper level. We show that this effect has observable consequences in the form of emission spectra with subnatural linewidths, which should be measurable using, for example, quantum dot-cavity systems in currently obtainable parameter regimes, and may find use in applications requiring the control of single-photon arrival times and wave-packet extent. These results suggest an underappreciated link between the Zeno effect, dressed states, and Purcell enhancement.
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Dauber, Bianca; Poon, David; Dos Santos, Theodore; Duguay, Brett A; Mehta, Ninad; Saffran, Holly A; Smiley, James R
2016-07-01
The herpes simplex virus (HSV) virion host shutoff (vhs) RNase destabilizes cellular and viral mRNAs, suppresses host protein synthesis, dampens antiviral responses, and stimulates translation of viral mRNAs. vhs mutants display a host range phenotype: translation of viral true late mRNAs is severely impaired and stress granules accumulate in HeLa cells, while translation proceeds normally in Vero cells. We found that vhs-deficient virus activates the double-stranded RNA-activated protein kinase R (PKR) much more strongly than the wild-type virus does in HeLa cells, while PKR is not activated in Vero cells, raising the possibility that PKR might play roles in stress granule induction and/or inhibiting translation in restrictive cells. We tested this possibility by evaluating the effects of inactivating PKR. Eliminating PKR in HeLa cells abolished stress granule formation but had only minor effects on viral true late protein levels. These results document an essential role for PKR in stress granule formation by a nuclear DNA virus, indicate that induction of stress granules is the consequence rather than the cause of the translational defect, and are consistent with our previous suggestion that vhs promotes translation of viral true late mRNAs by preventing mRNA overload rather than by suppressing eIF2α phosphorylation. The herpes simplex virus vhs RNase plays multiple roles during infection, including suppressing PKR activation, inhibiting the formation of stress granules, and promoting translation of viral late mRNAs. A key question is the extent to which these activities are mechanistically connected. Our results demonstrate that PKR is essential for stress granule formation in the absence of vhs, but at best, it plays a secondary role in suppressing translation of viral mRNAs. Thus, the ability of vhs to promote translation of viral mRNAs can be largely uncoupled from PKR suppression, demonstrating that this viral RNase modulates at least two distinct aspects of RNA metabolism. Copyright © 2016, American Society for Microbiology. All Rights Reserved.
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Asymmetric Dichoptic Masking in Visual Cortex of Amblyopic Macaque Monkeys
Shooner, Christopher; Hallum, Luke E.; García-Marín, Virginia; Kiorpes, Lynne
2017-01-01
In amblyopia, abnormal visual experience leads to an extreme form of eye dominance, in which vision through the nondominant eye is degraded. A key aspect of this disorder is perceptual suppression: the image seen by the stronger eye often dominates during binocular viewing, blocking the image of the weaker eye from reaching awareness. Interocular suppression is the focus of ongoing work aimed at understanding and treating amblyopia, yet its physiological basis remains unknown. We measured binocular interactions in visual cortex of anesthetized amblyopic monkeys (female Macaca nemestrina), using 96-channel “Utah” arrays to record from populations of neurons in V1 and V2. In an experiment reported recently (Hallum et al., 2017), we found that reduced excitatory input from the amblyopic eye (AE) revealed a form of balanced binocular suppression that is unaltered in amblyopia. Here, we report on the modulation of the gain of excitatory signals from the AE by signals from its dominant fellow eye (FE). Using a dichoptic masking technique, we found that AE responses to grating stimuli were attenuated by the presentation of a noise mask to the FE, as in a normal control animal. Responses to FE stimuli, by contrast, could not be masked from the AE. We conclude that a weakened ability of the amblyopic eye to modulate cortical response gain creates an imbalance of suppression that favors the dominant eye. SIGNIFICANCE STATEMENT In amblyopia, vision in one eye is impaired as a result of abnormal early visual experience. Behavioral observations in humans with amblyopia suggest that much of their visual loss is due to active suppression of their amblyopic eye. Here we describe experiments in which we studied binocular interactions in macaques with experimentally induced amblyopia. In normal monkeys, the gain of neuronal response to stimulation of one eye is modulated by contrast in the other eye, but in monkeys with amblyopia the balance of gain modulation is altered so that the weaker, amblyopic eye has little effect while the stronger fellow eye has a strong effect. This asymmetric suppression may be a key component of the perceptual losses in amblyopia. PMID:28760867
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Asymmetric Dichoptic Masking in Visual Cortex of Amblyopic Macaque Monkeys.
Shooner, Christopher; Hallum, Luke E; Kumbhani, Romesh D; García-Marín, Virginia; Kelly, Jenna G; Majaj, Najib J; Movshon, J Anthony; Kiorpes, Lynne
2017-09-06
In amblyopia, abnormal visual experience leads to an extreme form of eye dominance, in which vision through the nondominant eye is degraded. A key aspect of this disorder is perceptual suppression: the image seen by the stronger eye often dominates during binocular viewing, blocking the image of the weaker eye from reaching awareness. Interocular suppression is the focus of ongoing work aimed at understanding and treating amblyopia, yet its physiological basis remains unknown. We measured binocular interactions in visual cortex of anesthetized amblyopic monkeys (female Macaca nemestrina ), using 96-channel "Utah" arrays to record from populations of neurons in V1 and V2. In an experiment reported recently (Hallum et al., 2017), we found that reduced excitatory input from the amblyopic eye (AE) revealed a form of balanced binocular suppression that is unaltered in amblyopia. Here, we report on the modulation of the gain of excitatory signals from the AE by signals from its dominant fellow eye (FE). Using a dichoptic masking technique, we found that AE responses to grating stimuli were attenuated by the presentation of a noise mask to the FE, as in a normal control animal. Responses to FE stimuli, by contrast, could not be masked from the AE. We conclude that a weakened ability of the amblyopic eye to modulate cortical response gain creates an imbalance of suppression that favors the dominant eye. SIGNIFICANCE STATEMENT In amblyopia, vision in one eye is impaired as a result of abnormal early visual experience. Behavioral observations in humans with amblyopia suggest that much of their visual loss is due to active suppression of their amblyopic eye. Here we describe experiments in which we studied binocular interactions in macaques with experimentally induced amblyopia. In normal monkeys, the gain of neuronal response to stimulation of one eye is modulated by contrast in the other eye, but in monkeys with amblyopia the balance of gain modulation is altered so that the weaker, amblyopic eye has little effect while the stronger fellow eye has a strong effect. This asymmetric suppression may be a key component of the perceptual losses in amblyopia. Copyright © 2017 the authors 0270-6474/17/378734-08$15.00/0.
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Acute Inactivation of Primary Auditory Cortex Causes a Sound Localisation Deficit in Ferrets
Wood, Katherine C.; Town, Stephen M.; Atilgan, Huriye; Jones, Gareth P.
2017-01-01
The objective of this study was to demonstrate the efficacy of acute inactivation of brain areas by cooling in the behaving ferret and to demonstrate that cooling auditory cortex produced a localisation deficit that was specific to auditory stimuli. The effect of cooling on neural activity was measured in anesthetized ferret cortex. The behavioural effect of cooling was determined in a benchmark sound localisation task in which inactivation of primary auditory cortex (A1) is known to impair performance. Cooling strongly suppressed the spontaneous and stimulus-evoked firing rates of cortical neurons when the cooling loop was held at temperatures below 10°C, and this suppression was reversed when the cortical temperature recovered. Cooling of ferret auditory cortex during behavioural testing impaired sound localisation performance, with unilateral cooling producing selective deficits in the hemifield contralateral to cooling, and bilateral cooling producing deficits on both sides of space. The deficit in sound localisation induced by inactivation of A1 was not caused by motivational or locomotor changes since inactivation of A1 did not affect localisation of visual stimuli in the same context. PMID:28099489
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Liu, Yan; Xu, Sisi; Huang, Guoren; Xiong, Ying; Zhang, Shuang; Xu, Linli; Deng, Xuming; Guan, Shuang
2014-01-01
Daphnetin, a plant-derived dihydroxylated derivative of coumarin, is an effective compound extracted from a plant called Daphne Korean Nakai. Coumarin derivates were known for their antithrombotic, anti-inflammatory, and antioxidant activities. The present study was aimed to determine the immunosuppressive effects and the underlying mechanisms of daphnetin on concanavalin A (ConA) induced T lymphocytes in mice. We showed that, in vitro, daphnetin suppressed ConA-induced splenocyte proliferation, influenced production of the cytokines and inhibited cell cycle progression through the G0/G1 transition. The data also revealed that daphnetin could down-regulate activation of ConA induced NF-κB and NFAT signal transduction pathways in mouse T lymphocyte. In vivo, daphnetin treatment significantly inhibited the 2, 4- dinitrofluorobenzene (DNFB) -induced delayed type hypersensitivity (DTH) reactions in mice. Collectively, daphnetin had strong immunosuppressive activity both in vitro and in vivo, suggesting a potential role for daphnetin as an immunosuppressive agent, and established the groundwork for further research on daphnetin. PMID:24800925
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Okai, Y; Higashi-Okai, K; Yano, Y; Otani, S
1996-02-27
Recently, a relatively strong antimutagenic activity has been detected in the extract of Porphyra tenera (Asakusa-nori in Japanese) which showed a suppressive effect on mutagen-induced umu C gene expression in Salmonella typhimurium (TA 1535/pSK 1002 (Okai et al. (1994) Cancer Lett., 87, 25-32). In the present paper, we analyzed the active principles for the antimutagenic activity in an extract of Porphyra tenera and detected three color spots on a silica gel TLC plate which indicated very similar Rf values and absorbance spectra of standard pigments such as beta-carotene, chlorophyll a and lutein. The seaweed pigments recovered from preparative silica gel TLC corresponding to beta-carotene, chlorophyll a and lutein exhibited significant suppressive activities against mutagen-induced umu C gene expression and combined treatment with these pigments showed an additive effect compared with single treatment with each pigment. Furthermore, the standard pigments prepared from other biological sources also exhibited similar anti-mutagenic activities. The significance of this finding is discussed from the protective role of seaweed pigments against mutagenesis probably associated with carcinogenesis.
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Tang, Ning; Shi, Lei; Yu, Zhenlong; Dong, Peipei; Wang, Chao; Huo, Xiaokui; Zhang, Baojing; Huang, Shanshan; Deng, Sa; Liu, Kexin; Ma, Tonghui; Wang, Xiaobo; Wu, Lijun; Ma, Xiao-Chi
2016-01-19
Gamabufotalin (CS-6), a main active compound isolated from Chinese medicine Chansu, has been shown to strongly inhibit cancer cell growth and inflammatory response. However, its effects on angiogenesis have not been known yet. Here, we sought to determine the biological effects of CS-6 on signaling mechanisms during angiogenesis. Our present results fully demonstrate that CS-6 could significantly inhibit VEGF triggered HUVECs proliferation, migration, invasion and tubulogenesis in vitro and blocked vascularization in Matrigel plugs impregnated in C57/BL6 mice as well as reduced vessel density in human lung tumor xenograft implanted in nude mice. Computer simulations revealed that CS-6 interacted with the ATP-binding sites of VEGFR-2 using molecular docking. Furthermore, western blot analysis indicated that CS-6 inhibited VEGF-induced phosphorylation of VEGFR-2 kinase and suppressed the activity of VEGFR-2-mediated signaling cascades. Therefore, our studies demonstrated that CS-6 inhibited angiogenesis by inhibiting the activation of VEGFR-2 signaling pathways and CS-6 could be a potential candidate in angiogenesis-related disease therapy.
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KRC-327, a selective novel inhibitor of c-Met receptor tyrosine kinase with anticancer activity.
Park, Byung Hee; Jung, Kyung Hee; Yun, Sun-Mi; Hong, Sang-Won; Ryu, Jae Wook; Jung, Heejung; Ha, Jae Du; Lee, Jongkook; Hong, Soon-Sun
2013-05-01
c-Met receptor tyrosine kinase and its ligand, hepatocyte growth factor (HGF), have been reported to be involved in tumorigenesis and metastatic progression. We synthesized a novel triazolopyridazine derivative KRC-327 which selectively targets the c-Met. When we performed receptor tyrosine kinases (RTKs) array with 42 different phosphorylated-RTKs, KRC-327 strongly inhibited expression of activated c-Met in MKN-45 cancer cells. This was confirmed by immunofluorescence staining. Also, KRC-327 decreased the expression of Gab1, Akt, signal transducer and activator of transcription 3 (STAT3) and Erk, down-stream signals of c-Met. KRC-327 strongly suppressed the growth of c-Met over-expressed cancer cells (MKN-45, SNU-638, SNU-5), while not in c-Met absent cancer cell lines (MKN-1, SNU-1). Furthermore, KRC-327 effectively induced cell cycle arrest, especially G0/G1 arrest by increasing expression of p21, p27 and decreasing that of cyclin D1. In the ligand-induced functional studies, KRC-327 inhibited proliferation of HGF-stimulated BxPC-3 cells, the migration of HGF-stimulated AGS cancer cells, and suppressed colony formation in HGF-stimulated U-87MG cells. In xenograft animal models, KRC-327 significantly not only delayed tumor growth but also suppressed phosphorylation of c-Met and its signaling cascades as well as proliferation. Taken together, these results demonstrate that KRC-327 selectively targets c-Met, resulting in inhibition of cell growth and proliferation. Therefore, we suggest that KRC-327 may be a novel drug candidate with the therapeutic potential of targeting c-Met in human cancer. Crown Copyright © 2013. Published by Elsevier Ireland Ltd. All rights reserved.
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Microbiomes associated with infective stages of root-knot and lesion nematodes in soil
Elhady, Ahmed; Giné, Ariadna; Topalovic, Olivera; Jacquiod, Samuel; Sørensen, Søren J.; Sorribas, Francisco Javier
2017-01-01
Endoparasitic root-knot (Meloidogyne spp.) and lesion (Pratylenchus spp.) nematodes cause considerable damage in agriculture. Before they invade roots to complete their life cycle, soil microbes can attach to their cuticle or surface coat and antagonize the nematode directly or by induction of host plant defenses. We investigated whether the nematode-associated microbiome in soil differs between infective stages of Meloidogyne incognita and Pratylenchus penetrans, and whether it is affected by variation in the composition of microbial communities among soils. Nematodes were incubated in suspensions of five organically and two integrated horticultural production soils, recovered by sieving and analyzed for attached bacteria and fungi after washing off loosely adhering microbes. Significant effects of the soil type and nematode species on nematode-associated fungi and bacteria were revealed as analyzed by community profiling using denaturing gradient gel electrophoresis. Attached microbes represented a small specific subset of the soil microbiome. Two organic soils had very similar bacterial and fungal community profiles, but one of them was strongly suppressive towards root-knot nematodes. They were selected for deep amplicon sequencing of bacterial 16S rRNA genes and fungal ITS. Significant differences among the microbiomes associated with the two species in both soils suggested specific surface epitopes. Among the 28 detected bacterial classes, Betaproteobacteria, Bacilli and Actinobacteria were the most abundant. The most frequently detected fungal genera were Malassezia, Aspergillus and Cladosporium. Attached microbiomes did not statistically differ between these two soils. However, Malassezia globosa and four fungal species of the family Plectosphaerellaceae, and the bacterium Neorhizobium galegae were strongly enriched on M. incognita in the suppressive soil. In conclusion, the highly specific attachment of microbes to infective stages of phytonematodes in soil suggested an ecological role of this association and might be involved in soil suppressiveness towards them. PMID:28472099
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Li, Lanzhou; Teng, Meiyu; Liu, Yange; Qu, Yidi; Zhang, Yuanzhu; Lin, Feng; Wang, Di
2017-01-01
This study was performed to investigate the therapeutic effects and possible mechanisms of sunflower (Helianthus annuus) head extract (SHE) on gout. First, the components of sunflower head powder and SHE were analyzed systematically. SHE, especially SHEB (extracted with 20% ethanol and 80% double-distilled water), strongly suppressed the swelling of the ankles in rats with acute gout induced by monosodium urate (MSU) crystals and reduced the levels of uric acid and xanthine oxidase (XO) in mice with hyperuricemia induced by oteracil potassium and yeast extract powder. Hematoxylin and eosin staining indicated that SHEB reduced inflammation cells and increased the joint space in the ankle compared with the control rats with MSU-induced gout. In the rats with acute gout, among 13 detected inflammatory cytokines, SHEB significantly enhanced the serum levels of interleukin-10 and the monocyte chemoattractant protein 1 α . In the mice with hyperuricemia, SHEB reduced the levels of glutathione peroxidase, superoxide dismutase, malondialdehyde, and nitrogen monoxide in liver tissues. The potential therapeutic effects of SHE on gout are probably due to the production of anti-inflammatory cytokines and the suppression of XO activity via the modulation of oxidative stress status.
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Hydroquinone Exhibits In Vitro and In Vivo Anti-Cancer Activity in Cancer Cells and Mice.
Byeon, Se Eun; Yi, Young-Su; Lee, Jongsung; Yang, Woo Seok; Kim, Ji Hye; Kim, Jooyoung; Hong, Suntaek; Kim, Jong-Hoon; Cho, Jae Youl
2018-03-19
Hydroquinone (HQ, 1,4-benzenediol) is a hydroxylated benzene metabolite with various biological activities, including anti-oxidative, neuroprotective, immunomodulatory, and anti-inflammatory functions. However, the anti-cancer activity of HQ is not well understood. In this study, the in vitro and in vivo anti-cancer activity of HQ was investigated in various cancer cells and tumor-bearing mouse models. HQ significantly induced the death of A431, SYF, B16F10, and MDA-MB-231 cells and also showed a synergistic effect on A431 cell death with other anti-cancer agents, such as adenosine-2',3'-dialdehyde and buthionine sulfoximine. In addition, HQ suppressed angiogenesis in fertilized chicken embryos. Moreover, HQ prevented lung metastasis of melanoma cells in mice in a dose-dependent manner without toxicity and adverse effects. HQ (10 mg/kg) also suppressed the generation of colon and reduced the thickness of colon tissues in azoxymethane/dextran sodium sulfate-injected mice. This study strongly suggests that HQ possesses in vitro and in vivo anti-cancer activity and provides evidence that HQ could be developed as an effective and safe anti-cancer drug.
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Cassaday, H.J.; Thur, K.E.
2015-01-01
Treatment with selective serotonin reuptake inhibitors (SSRIs) can reduce contextual conditioning. Since contexts comprise a variety of potentially competing cues, impaired overshadowing may provide an account of such effects. The present study therefore compared the effects of two SSRIs on overshadowing and contextual conditioning, testing suppression of an ongoing behavioral response (licking) by cues previously paired with foot shock. Conditioning to a 5 s light stimulus was reduced when it was presented in compound with a 5 s noise, thus overshadowing was demonstrated. In two experiments, this overshadowing was unaffected by treatment with either sertraline or fluvoxamine. However, unconditioned suppression to the noise (tested in a control group previously conditioned to the light alone) was reduced after sertraline (10 mg/kg, i.p.). The successful demonstration of overshadowing required the use of a second conditioning session or an additional conditioning trial within the same conditioning session. Neither weak nor strong overshadowing (of the light by the tone) was affected by any drug treatment. Moreover, counter to prediction, conditioning to contextual cues was increased rather than impaired by treatment with sertraline (10 mg/kg, i.p.) and fluvoxamine (30 mg/kg, i.p.). PMID:25532461
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Cassaday, H J; Thur, K E
2015-02-01
Treatment with selective serotonin reuptake inhibitors (SSRIs) can reduce contextual conditioning. Since contexts comprise a variety of potentially competing cues, impaired overshadowing may provide an account of such effects. The present study therefore compared the effects of two SSRIs on overshadowing and contextual conditioning, testing suppression of an ongoing behavioral response (licking) by cues previously paired with foot shock. Conditioning to a 5 s light stimulus was reduced when it was presented in compound with a 5 s noise, thus overshadowing was demonstrated. In two experiments, this overshadowing was unaffected by treatment with either sertraline or fluvoxamine. However, unconditioned suppression to the noise (tested in a control group previously conditioned to the light alone) was reduced after sertraline (10 mg/kg, i.p.). The successful demonstration of overshadowing required the use of a second conditioning session or an additional conditioning trial within the same conditioning session. Neither weak nor strong overshadowing (of the light by the tone) was affected by any drug treatment. Moreover, counter to prediction, conditioning to contextual cues was increased rather than impaired by treatment with sertraline (10 mg/kg, i.p.) and fluvoxamine (30 mg/kg, i.p.). Copyright © 2015. Published by Elsevier Inc.
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Wang, Haifeng; Cheng, Hua; Wang, Kai; Wen, Tieqiao
2012-11-01
Histone deacetylase inhibitors are involved in proliferation, apoptosis, cell cycle, mRNA transcription, and protein expression in various cells. However, the molecular mechanism underlying such functions is still not fully clear. In this study, we used C17.2 neural stem cell (NSC) line as a model to evaluate the effects of nicotinamide and trichostatin A (TSA) on cell characteristics. Results show that nicotinamide and TSA greatly inhibit cell growth, lead to cell morphology changes, and effectively induce cell apoptosis in a dose-dependent manner. Western blot analyses confirmed that nicotinamide significantly decreases the expression of bcl-2 and p38. Further insight into the molecular mechanisms shows the suppression of phosphorylation in eukaryotic initiation factor 4E-binding protein 1 (4EBP1) by nicotinamide, whereas, an increased expression of bcl-2 and p38 and phosphorylation of 4EBP1 by TSA. However, both nicotinamide and TSA significantly increase the expression of cytochrome c (cyt c). These results strongly suggest that bcl-2, p38, cyt c, and p-4EBP1 could suppress proliferation and induce apoptosis of C17.2 NSCs mediated by histone deacetylase inhibitors, nicotinamide and TSA, involving different molecular mechanisms.
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Li, Lanzhou; Teng, Meiyu; Liu, Yange; Qu, Yidi; Zhang, Yuanzhu
2017-01-01
This study was performed to investigate the therapeutic effects and possible mechanisms of sunflower (Helianthus annuus) head extract (SHE) on gout. First, the components of sunflower head powder and SHE were analyzed systematically. SHE, especially SHEB (extracted with 20% ethanol and 80% double-distilled water), strongly suppressed the swelling of the ankles in rats with acute gout induced by monosodium urate (MSU) crystals and reduced the levels of uric acid and xanthine oxidase (XO) in mice with hyperuricemia induced by oteracil potassium and yeast extract powder. Hematoxylin and eosin staining indicated that SHEB reduced inflammation cells and increased the joint space in the ankle compared with the control rats with MSU-induced gout. In the rats with acute gout, among 13 detected inflammatory cytokines, SHEB significantly enhanced the serum levels of interleukin-10 and the monocyte chemoattractant protein 1α. In the mice with hyperuricemia, SHEB reduced the levels of glutathione peroxidase, superoxide dismutase, malondialdehyde, and nitrogen monoxide in liver tissues. The potential therapeutic effects of SHE on gout are probably due to the production of anti-inflammatory cytokines and the suppression of XO activity via the modulation of oxidative stress status. PMID:28929115
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Ye, Han-Yang; Jin, Jian; Jin, Ling-Wei; Chen, Yan; Zhou, Zhi-Hong; Li, Zhan-Yuan
2017-04-01
Chlorogenic acid (CGA), a polyphenolic compound, exists widely in medicinal herbs, which has been shown a strong antioxidant and anti-inflammatory effect. This study investigated the protective effects and mechanism of CGA on lipopolysaccharide (LPS)-induced acute kidney injury (AKI). Treatment of CGA successfully ameliorates LPS-induced renal function and pathological damage. Moreover, CGA dose-dependently suppressed LPS-induced blood urea nitrogen (BUN), creatinine levels, and inflammatory cytokines TNF-α, IL-6, and IL-1β in serum and tissue. The relative proteins' expression of TLR4/NF-κB signal pathway was assessed by western blot analysis. Our results showed that CGA dose-dependently attenuated LPS-induced kidney histopathologic changes, serum BUN, and creatinine levels. CGA also suppressed LPS-induced TNF-α, IL-6, and IL-1β production both in serum and kidney tissues. Furthermore, our results showed that CGA significantly inhibited the LPS-induced expression of phosphorylated NF-κB p65 and IκB as well as the expression of TLR4 signal. In conclusion, our results provide a mechanistic explanation for the anti-inflammatory effects of CGA in LPS-induced AKI mice through inhibiting TLR4/NF-κB signaling pathway.
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Suppressing turbulence of self-propelling rods by strongly coupled passive particles.
Su, Yen-Shuo; Wang, Hao-Chen; I, Lin
2015-03-01
The strong turbulence suppression, mainly for large-scale modes, of two-dimensional self-propelling rods, by increasing the long-range coupling strength Γ of low-concentration passive particles, is numerically demonstrated. It is found that large-scale collective rod motion in forms of swirls or jets is mainly contributed from well-aligned dense patches, which can push small poorly aligned rod patches and uncoupled passive particles. The more efficient momentum transfer and dissipation through increasing passive particle coupling leads to the formation of a more ordered and slowed down network of passive particles, which competes with coherent dense active rod clusters. The frustration of active rod alignment ordering and coherent motion by the passive particle network, which interrupt the inverse cascading of forming large-scale swirls, is the key for suppressing collective rod motion with scales beyond the interpassive distance, even in the liquid phase of passive particles. The loosely packed active rods are weakly affected by increasing passive particle coupling due to the weak rod-particle interaction. They mainly contribute to the small-scale modes and high-speed motion.
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Tian, Lingmin; Shi, Xiaolong; Yu, Linhong; Zhu, Jiao; Ma, Rui; Yang, Xingbin
2012-05-09
This study was designed to investigate the antioxidant activity, hepatoprotective effect, and phenolic composition of the ethyl acetate fraction (EAF) extracted from Houttuynia cordata tea. EAF was shown to exhibit strong ferric-reducing antioxidant power (FRAP) and scavenging activity against DPPH radical in vitro, and the antioxidant effects were further verified by suppressing CCl₄-induced oxidative stress in mouse liver at three tested doses of EAF (250, 500, and 1000 mg/kg bw). Pretreatment with EAF (1000 mg/kg bw) prior to CCl₄ administration significantly (p < 0.001) decreased the CCl₄-elevated levels of serum AST, ALT, alkaline phosphatase, total bilirubin, and hepatic MDA in mice and prevented the increases in GSH, SOD, and CAT caused by CCl₄. HPLC analysis revealed that three predominantly polyphenolic compounds present in EAF were quercitrin (111.7 μg/mg), quercetin (43.8 μg/mg), and hyperoside (29.1 μg/mg). These results combined with liver histopathology indicate that EAF possesses a significant protective effect against acute hepatotoxicity induced by CCl₄, which may be due to the strong antioxidant activity of phenolic components.
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A Maize Cystatin Suppresses Host Immunity by Inhibiting Apoplastic Cysteine Proteases[C][W
van der Linde, Karina; Hemetsberger, Christoph; Kastner, Christine; Kaschani, Farnusch; van der Hoorn, Renier A.L.; Kumlehn, Jochen; Doehlemann, Gunther
2012-01-01
Ustilago maydis is a biotrophic pathogen causing maize (Zea mays) smut disease. Transcriptome profiling of infected maize plants indicated that a gene encoding a putative cystatin (CC9) is induced upon penetration by U. maydis wild type. By contrast, cc9 is not induced after infection with the U. maydis effector mutant Δpep1, which elicits massive plant defenses. Silencing of cc9 resulted in a strongly induced maize defense gene expression and a hypersensitive response to U. maydis wild-type infection. Consequently, fungal colonization was strongly reduced in cc9-silenced plants, while recombinant CC9 prevented salicylic acid (SA)–induced defenses. Protease activity profiling revealed a strong induction of maize Cys proteases in SA-treated leaves, which could be inhibited by addition of CC9. Transgenic maize plants overexpressing cc9-mCherry showed an apoplastic localization of CC9. The transgenic plants showed a block in Cys protease activity and SA-dependent gene expression. Moreover, activated apoplastic Cys proteases induced SA-associated defense gene expression in naïve plants, which could be suppressed by CC9. We show that apoplastic Cys proteases play a pivotal role in maize defense signaling. Moreover, we identified cystatin CC9 as a novel compatibility factor that suppresses Cys protease activity to allow biotrophic interaction of maize with the fungal pathogen U. maydis. PMID:22454455
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Naringenin targets ERK2 and suppresses UVB-induced photoaging.
Jung, Sung Keun; Ha, Su Jeong; Jung, Chang Hwa; Kim, Yun Tai; Lee, Hoo-Keun; Kim, Myoung Ok; Lee, Mee-Hyun; Mottamal, Madhusoodanan; Bode, Ann M; Lee, Ki Won; Dong, Zigang
2016-05-01
A number of natural phytochemicals have anti-photoaging properties that appear to be mediated through the inhibition of matrix metalloproteinase-1 (MMP-1) expression, but their direct target molecule(s) and mechanism(s) remain unclear. We investigated the effect of naringenin, a major flavonoid found in citrus, on UVB-induced MMP-1 expression and identified its direct target. The HaCaT human skin keratinocyte cell line and 3-dimensional (3-D) human skin equivalent cultures were treated or not treated with naringenin for 1 hr before exposure to UVB. The mechanism and target(s) of naringenin were analysed by kinase assay and multiplex molecular assays. Dorsal skins of hairless mice were exposed to UVB 3 times per week, with a dose of irradiation that was increased weekly by 1 minimal erythema dose (MED; 45 mJ/cm(2)) to 4 MED over 15 weeks. Wrinkle formation, water loss and water content were then assessed. Naringenin suppressed UVB-induced MMP-1 expression and AP-1 activity, and strongly suppressed UVB-induced phosphorylation of Fos-related antigen (FRA)-1 at Ser265. Importantly, UVB irradiation-induced FRA1 protein stability was reduced by treatment with naringenin, as well as with a mitogen-activated protein kinase (MEK) inhibitor. Naringenin significantly suppressed UVB-induced extracellular signal-regulated kinase 2 (ERK2) activity and subsequently attenuated UVB-induced phosphorylation of p90(RSK) by competitively binding with ATP. Constitutively active MEK (CA-MEK) increased FRA1 phosphorylation and expression and also induced MMP-1 expression, whereas dominant-negative ERK2 (DN-ERK2) had opposite effects. U0126, a MEK inhibitor, also decreased FRA1 phosphorylation and expression as well as MMP-1 expression. The photoaging data obtained from mice clearly demonstrated that naringenin significantly inhibited UVB-induced wrinkle formation, trans-epidermal water loss and MMP-13 expression. Naringenin exerts potent anti-photoaging effects by suppressing ERK2 activity and decreasing FRA1 stability, followed by down-regulation of AP-1 transactivation and MMP-1 expression. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.
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Recovery of African wild dogs suppresses prey but does not trigger a trophic cascade.
Ford, Adam T; Goheen, Jacob R; Augustine, David J; Kinnaird, Margaret F; O'Brien, Timothy G; Palmer, Todd M; Pringle, Robert M; Woodroffe, Rosie
2015-10-01
Increasingly, the restoration of large carnivores is proposed as a means through which to restore community structure and ecosystem function via trophic cascades. After a decades-long absence, African wild dogs (Lycaon pictus) recolonized the Laikipia Plateau in central Kenya, which we hypothesized would trigger a trophic cascade via suppression of their primary prey (dik-dik, Madoqua guentheri) and the subsequent relaxation of browsing pressure on trees. We tested the trophic-cascade hypothesis using (1) a 14-year time series of wild dog abundance; (2) surveys of dik-dik population densities conducted before and after wild dog recovery; and (3) two separate, replicated, herbivore-exclusion experiments initiated before and after wild dog recovery. The dik-dik population declined by 33% following wild dog recovery, which is best explained by wild dog predation. Dik-dik browsing suppressed tree abundance, but the strength of suppression did not differ between before and after wild dog recovery. Despite strong, top-down limitation between adjacent trophic levels (carnivore-herbivore and herbivore-plant), a trophic cascade did not occur, possibly because of a time lag in indirect effects, variation in rainfall, and foraging by herbivores other than dik-dik. Our ability to reject the trophic-cascade hypothesis required two important approaches: (1) temporally replicated herbivore exclusions, separately established before and after wild dog recovery; and (2) evaluating multiple drivers of variation in the abundance of dik-dik and trees. While the restoration of large carnivores is often a conservation priority, our results suggest that indirect effects are mediated by ecological context, and that trophic cascades are not a foregone conclusion of such recoveries.
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Riedel, Gernot; Fadda, Paola; McKillop-Smith, Susan; Pertwee, Roger G; Platt, Bettina; Robinson, Lianne
2009-04-01
Obesity is a severe health problem in the modernized world and understanding the central nervous mechanisms underlying food-seeking behaviour and reward are at the forefront of medical research. Cannabinoid receptors have proven an efficient target to suppress hunger and weight gain by their pharmacological inactivation. A standard fasted protocol and a novel long-term home-cage observation system with free-feeding animals were used to assess the feeding behaviour of mice treated with the CB1 antagonist AM251. Similarly, the effects of the phytocannabinoid Delta9-tetrahydrocannabivarin (Delta9-THCV), which behaves like a CB1 antagonist, were also determined in free-feeding animals. AM251 suppressed food intake and weight gain in fasted and non-fasted animals. The suppression of food intake by AM251 (10 mg.kg-1) endured for a period of 6-8 h when administered acutely, and was continuous when injected for four consecutive days. Pure Delta9-THCV also induced hypophagia and weight reduction at doses as low as 3 mg.kg-1. No rebound was observed on the following day with all drug groups returning to normal activity and feeding regimes. However, a Delta9-THCV-rich cannabis-extract failed to suppress food intake and weight gain, possibly due to residual Delta9-tetrahydrocannabinol (Delta9-THC) in the extract. This Delta9-THC effect was overcome by the co-administration of cannabidiol. The data strongly suggest (i) the long-term home-cage observation system is a sensitive and obesity-relevant tool, and (ii) the phytocannabinoid Delta9-THCV is a novel compound with hypophagic properties and a potential treatment for obesity
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Riedel, Gernot; Fadda, Paola; McKillop-Smith, Susan; Pertwee, Roger G; Platt, Bettina; Robinson, Lianne
2009-01-01
Background and purpose: Obesity is a severe health problem in the modernized world and understanding the central nervous mechanisms underlying food-seeking behaviour and reward are at the forefront of medical research. Cannabinoid receptors have proven an efficient target to suppress hunger and weight gain by their pharmacological inactivation. Experimental approach: A standard fasted protocol and a novel long-term home-cage observation system with free-feeding animals were used to assess the feeding behaviour of mice treated with the CB1 antagonist AM251. Similarly, the effects of the phytocannabinoid Δ9-tetrahydrocannabivarin (Δ9-THCV), which behaves like a CB1 antagonist, were also determined in free-feeding animals. Key results: AM251 suppressed food intake and weight gain in fasted and non-fasted animals. The suppression of food intake by AM251 (10 mg·kg−1) endured for a period of 6–8 h when administered acutely, and was continuous when injected for four consecutive days. Pure Δ9-THCV also induced hypophagia and weight reduction at doses as low as 3 mg·kg−1. No rebound was observed on the following day with all drug groups returning to normal activity and feeding regimes. However, a Δ9-THCV-rich cannabis-extract failed to suppress food intake and weight gain, possibly due to residual Δ9-tetrahydrocannabinol (Δ9-THC) in the extract. This Δ9-THC effect was overcome by the co-administration of cannabidiol. Conclusions and implications: The data strongly suggest (i) the long-term home-cage observation system is a sensitive and obesity-relevant tool, and (ii) the phytocannabinoid Δ9-THCV is a novel compound with hypophagic properties and a potential treatment for obesity. PMID:19378378
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Afrin, Sadia; Giampieri, Francesca; Gasparrini, Massimiliano; Forbes-Hernández, Tamara Y; Cianciosi, Danila; Reboredo-Rodriguez, Patricia; Manna, Piera Pia; Zhang, Jiaojiao; Quiles, Josè L; Battino, Maurizio
2018-04-25
Despite its high content of phenolic compounds, the chemopreventive activity of Manuka honey (MH) is still elusive. The aim of the present work was to evaluate the effects of MH on oxidative stress, antioxidant enzymes, cellular metabolism and the metastatic ability in HCT-116 and LoVo cells, paying particular attention to the molecular mechanisms involved. We observed a strong induction of oxidative stress after MH treatment since it augmented the accumulation of reactive oxygen species and increased the damage to proteins, lipids and DNA. Furthermore, MH suppressed the Nrf2-dependent antioxidant enzyme expression (superoxide dismutase (SOD), catalase and heme oxygenase-1) and the activity of SOD, catalase, glutathione peroxidase and glutathione reductase. Cell metabolisms were markedly disrupted after MH treatment. It decreased maximal oxygen consumption and spare respiratory capacity, which could reduce the mitochondrial function that is correlated with cell survival potential. Simultaneously, MH decreased the extracellular acidification rate (glycolysis) of HCT-116 and LoVo cells. Furthermore, MH suppressed the p-AMPK/AMPK, PGC1α and SIRT1 activation, involved in the survival of HCT-116 and LoVo cells under metabolic stress conditions. Dose-dependently, MH reduced the migration and invasion (MMP-2 and MMP-9) ability, and concurrently regulated EMT-related markers (E cadherin, N cadherin, and β-catenin) in both cell types. The above findings indicate that MH induces HCT-116 and LoVo cell death partly by enhancing oxidative stress, as well as by regulating the energy metabolism in both aerobic and anaerobic pathways and suppressing the metastatic ability.
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NASA Astrophysics Data System (ADS)
Yasuda, H.; Kubis, T.; Hosako, I.; Hirakawa, K.
2012-04-01
We theoretically investigated GaN-based resonant phonon terahertz-quantum cascade laser (QCL) structures for possible high-temperature operation by using the non-equilibrium Green's function method. It was found that the GaN-based THz-QCL structures do not necessarily have a gain sufficient for lasing, even though the thermal backfilling and the thermally activated phonon scattering are effectively suppressed. The main reason for this is the broadening of the subband levels caused by a very strong interaction between electrons and longitudinal optical (LO) phonons in GaN.
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Spyridakou, Chrysa; Luxon, Linda M; Bamiou, Doris E
2012-07-01
To compare self-reported symptoms of difficulty hearing speech in noise and hyperacusis in adults with auditory processing disorders (APDs) and normal controls; and to compare self-reported symptoms to objective test results (speech in babble test, transient evoked otoacoustic emission [TEOAE] suppression test using contralateral noise). A prospective case-control pilot study. Twenty-two participants were recruited in the study: 10 patients with reported hearing difficulty, normal audiometry, and a clinical diagnosis of APD; and 12 normal age-matched controls with no reported hearing difficulty. All participants completed the validated Amsterdam Inventory for Auditory Disability questionnaire, a hyperacusis questionnaire, a speech in babble test, and a TEOAE suppression test using contralateral noise. Patients had significantly worse scores than controls in all domains of the Amsterdam Inventory questionnaire (with the exception of sound detection) and the hyperacusis questionnaire (P < .005). Patients also had worse TEOAE suppression test results in both ears than controls; however, this result was not significant after Bonferroni correction. Strong correlations were observed between self-reported symptoms of difficulty hearing speech in noise and speech in babble test results in the right ear (ρ = 0.624, P = .002), and between self-reported symptoms of hyperacusis and TEOAE suppression test results in the right ear (ρ = -0.597 P = .003). There was no significant correlation between the two tests. A strong correlation was observed between right ear speech in babble and patient-reported intelligibility of speech in noise, and right ear TEOAE suppression by contralateral noise and hyperacusis questionnaire. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.
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Zhu, Zhenzhong; Kremer, Penny; Tadmori, Iman; Ren, Yi; Sun, Dongming; He, Xijing; Young, Wise
2011-01-01
Transplanted neural stem and progenitor cells (NSCs) produce mostly astrocytes in injured spinal cords. Lithium stimulates neurogenesis by inhibiting GSK3b (glycogen synthetase kinase 3-beta) and increasing WNT/beta catenin. Lithium suppresses astrogliogenesis but the mechanisms were unclear. We cultured NSCs from subventricular zone of neonatal rats and showed that lithium reduced NSC production of astrocytes as well as proliferation of glia restricted progenitor (GRP) cells. Lithium strongly inhibited STAT3 (signal transducer and activator of transcription 3) activation, a messenger system known to promote astrogliogenesis and cancer. Lithium abolished STAT3 activation and astrogliogenesis induced by a STAT3 agonist AICAR (5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside), suggesting that lithium suppresses astrogliogenesis by inhibiting STAT3. GSK3β inhibition either by a specific GSK3β inhibitor SB216763 or overexpression of GID5-6 (GSK3β Interaction Domain aa380 to 404) did not suppress astrogliogenesis and GRP proliferation. GSK3β inhibition also did not suppress STAT3 activation. Together, these results indicate that lithium inhibits astrogliogenesis through non-GSK3β-mediated inhibition of STAT. Lithium may increase efficacy of NSC transplants by increasing neurogenesis and reducing astrogliogenesis. Our results also may explain the strong safety record of lithium treatment of manic depression. Millions of people take high-dose (>1 gram/day) lithium carbonate for a lifetime. GSK3b inhibition increases WNT/beta catenin, associated with colon and other cancers. STAT3 inhibition may reduce risk for cancer. PMID:21931595
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NASA Astrophysics Data System (ADS)
Sripathi, S.; Banola, S.; Emperumal, K.; Suneel Kumar, B.; Radicella, Sandro M.
2018-03-01
We investigate the role of storm time electrodynamics in suppressing the equatorial plasma bubble (EPB) development using multi-instruments over India during a moderate geomagnetic storm that occurred on 2 October 2013 where Dst minimum reached -80 nT. This storm produced unique signatures in the equatorial ionosphere such that equatorial electrojet strength showed signatures of an abrupt increase of its strength to 150 nT and occurrence of episodes of counter electrojet events. During the main phase of the storm, the interplanetary magnetic field Bz is well correlated with the variations in the equatorial electrojet/counter electrojet suggesting the role of undershielding/overshielding electric fields of magnetospheric origin. Further, observations showed the presence of strong F3 layers at multiple times at multiple stations due to undershielding electric field. Interestingly, we observed simultaneous presence of F3 layers and suppression of EPBs in the dusk sector during the recovery phase. While strong EPBs were observed before and after the day of the geomagnetic storm, suppression of the EPBs on the storm day during "spread F season" is intriguing. Our further analysis using low-latitude station, Hyderabad, during the time of prereversal enhancement suggests that intense Esb layers were observed on the storm day but were absent/weak on quiet days. Based on these results, we suggest that the altitude/latitude variation of disturbance dynamo electric fields/disturbance winds may be responsible for simultaneous detection of F3 layers, occurrence of low-latitude Es layers, and suppression of EPBs during the storm day along the sunset terminator.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Imada, Shinsuke, E-mail: shinimada@stelab.nagoya-u.ac.jp; Murakami, Izumi, E-mail: murakami.izumi@nifs.ac.jp; Department of Fusion Science, SOKENDAI
2015-10-15
We have studied the chromospheric evaporation flow during the impulsive phase of the flare by using the Hinode/EUV Imaging Spectrometer observation and 1D hydrodynamic numerical simulation coupled to the time-dependent ionization. The observation clearly shows that the strong redshift can be observed at the base of the flaring loop only during the impulsive phase. We performed two different numerical simulations to reproduce the strong downflows in FeXII and FeXV during the impulsive phase. By changing the thermal conduction coefficient, we carried out the numerical calculation of chromospheric evaporation in the thermal conduction dominant regime (conductivity coefficient κ{sub 0} = classical value) andmore » the enthalpy flux dominant regime (κ{sub 0} = 0.1 × classical value). The chromospheric evaporation calculation in the enthalpy flux dominant regime could reproduce the strong redshift at the base of the flare during the impulsive phase. This result might indicate that the thermal conduction can be strongly suppressed in some cases of flare. We also find that time-dependent ionization effect is important to reproduce the strong downflows in Fe XII and Fe XV.« less
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Camphor is a white substance with a strong odor that is commonly associated with topical ointments and gels used for cough suppression and muscle aches. Camphor overdose occurs when someone accidentally or intentionally takes ...
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Du Four, Stephanie; Maenhout, Sarah K.; De Pierre, Kari; Renmans, Dries; Niclou, Simone P; Thielemans, Kris; Neyns, Bart; Aerts, Joeri L
2015-01-01
Melanoma patients are at a high risk of developing brain metastases, which are strongly vascularized and therefore have a significant risk of spontaneous bleeding. VEGF not only plays a role in neo-angiogenesis but also in the antitumor immune response. VEGFR-targeted therapy might not only have an impact on the tumor vascularization but also on tumor-infiltrating immune cells. In this study, we investigated the effect of axitinib, a small molecule TKI of VEGFR-1, -2, and -3, on tumor growth and on the composition of tumor-infiltrating immune cells in subcutaneous and intracranial mouse melanoma models. In vivo treatment with axitinib induced a strong inhibition of tumor growth and significantly improved survival in both tumor models. Characterization of the immune cells within the spleen and tumor of tumor-bearing mice respectively showed a significant increase in the number of CD3+CD8+ T cells and CD11b+ cells of axitinib-treated mice. More specifically, we observed a significant increase of intratumoral monocytic myeloid-derived suppressor cells (moMDSCs; CD11b+Ly6ChighLy6G-). Interestingly, in vitro proliferation assays showed that moMDSCs isolated from spleen or tumor of axitinib-treated mice had a reduced suppressive capacity on a per cell basis as compared to those isolated from vehicle-treated mice. Moreover, MDSCs from axitinib-treated animals displayed the capacity to stimulate allogeneic T cells. Thus, treatment with axitinib induces differentiation of moMDSC toward an antigen-presenting phenotype. Based on these observations, we conclude that the impact of axitinib on tumor growth and survival is most likely not restricted to direct anti-angiogenic effects but also involves important effects on tumor immunity. PMID:26137411
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A Novel Derivative of the Natural Agent Deguelin for Cancer Chemoprevention and Therapy
Kim, Woo-Young; Chang, Dong Jo; Hennessy, Bryan; Kang, Hae-Jin; Yoo, Jakyung; Han, Seung-Ho; Kim, Yoo-Shin; Park, Hyun-Ju; Geo, Seung-Yong; Mills, Gordon; Kim, Kyu-Won; Hong, Waun Ki; Suh, Young-Ger; Lee, Ho-Young
2009-01-01
The natural compound deguelin has promising preventive and therapeutic activity against diverse cancers by directly binding to heat-shock protein 90 (Hsp90) and thus suppressing its function. Potential side effects of deguelin over a certain dose, however, could be a substantial obstacle to its clinical use. To develop a derivative(s) of deguelin with reduced potential side effects, we synthesized five deguelin analogues (SH-02, SH-03, SH-09, SH-14 and SH-15) and compared them with the parent compound and each other for structural and biochemical features, solubility, and antiproliferative effects on normal, premalignant and malignant human bronchial epithelial (HBE) and non-small-cell lung cancer (NSCLC) cell lines. Four derivatives destabilized hypoxia-inducible factor-1α as potently as did deguelin. Reverse-phase protein array (RPPA) analysis in H460 NSCLC cells revealed that deguelin and the derivatives suppressed expression of a number of proteins including Hsp90 clients and proteins involved in the phosphoinositide 3 kinase (PI3K)/Akt pathway. One derivative, SH-14, showed several features of potential superiority for clinical use: the highest apoptotic activity; no detectable influence on Src/signal transducer and activator of transcription (STAT) signaling, which can promote cancer progression and is closely related to pathogenesis of Parkinson’s disease (deguelin, SH-02 and SH-03 strongly activated this signaling); better aqueous solubility; and less cytotoxicity to immortalized HBE cells (versus deguelin) at a dose (1 μM) that induced apoptotic activity in most premalignant and malignant HBE and NSCLC cell lines. These collective results suggest that the novel derivative SH-14 has strong potential for cancer chemoprevention and therapy, with equivalent efficacy and lesser toxicity (versus deguelin). PMID:19139008
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Lu, Yujiao; Dong, Yan; Tucker, Donovan; Wang, Ruimin; Ahmed, Mohammad Ejaz; Brann, Darrell; Zhang, Quanguang
2017-01-01
Recent work has suggested that exercise may be beneficial in preventing or ameliorating symptoms of several neurological disorders, although the mechanism is not entirely understood. The current study was designed to examine the potential beneficial effect of treadmill exercise upon cognitive function in a streptozotocin (STZ)-induced rat model of Alzheimer’s disease (AD). Animals underwent treadmill exercise (30 min/day, 5 days/week) for 4 weeks after bilateral STZ intracerebroventricular injection (2.4 mg/kg). We demonstrated that treadmill exercise significantly attenuated STZ-induced neurodegeneration in the rat hippocampal CA1 region and strongly preserved hippocampal-dependent cognitive functioning. Further mechanistic investigation displayed a marked suppression of STZ-induced amyloid-β accumulation and tau phosphorylation. Intriguingly, treadmill exercise remarkably inhibited reactive gliosis following STZ insult and effectively shifted activated microglia from a pro-inflammatory M1 to an anti-inflammatory M2 phenotype, which was correlated with a significantly reduced expression of pro-inflammatory mediators and a corresponding enhancement of anti-inflammatory cytokine expression in the hippocampus. Furthermore, treadmill exercise caused a robust suppression of oxidative damage as evidenced by significantly reduced peroxynitrite production, lipid peroxidation, and oxidized DNA damage. Finally, treadmill exercise strongly attenuated STZ-induced mitochondrial dysfunction manifested by a dramatically elevated intra-mitochondrial cytochrome c oxidase activity and ATP synthesis, and markedly inhibited neuronal apoptosis in the hippocampus. These findings demonstrate that treadmill exercise has a multifactorial effect to attenuate many of the pathological processes that play a key role in AD, and provide further support for the beneficial role of exercise as a potential therapeutic option in AD treatment. PMID:28157094
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Lu, Yujiao; Dong, Yan; Tucker, Donovan; Wang, Ruimin; Ahmed, Mohammad Ejaz; Brann, Darrell; Zhang, Quanguang
2017-01-01
Recent work has suggested that exercise may be beneficial in preventing or ameliorating symptoms of several neurological disorders, although the mechanism is not entirely understood. The current study was designed to examine the potential beneficial effect of treadmill exercise upon cognitive function in a streptozotocin (STZ)-induced rat model of Alzheimer's disease (AD). Animals underwent treadmill exercise (30 min/day, 5 days/week) for 4 weeks after bilateral STZ intracerebroventricular injection (2.4 mg/kg). We demonstrated that treadmill exercise significantly attenuated STZ-induced neurodegeneration in the rat hippocampal CA1 region and strongly preserved hippocampal-dependent cognitive functioning. Further mechanistic investigation displayed a marked suppression of STZ-induced amyloid-β accumulation and tau phosphorylation. Intriguingly, treadmill exercise remarkably inhibited reactive gliosis following STZ insult and effectively shifted activated microglia from a pro-inflammatory M1 to an anti-inflammatory M2 phenotype, which was correlated with a significantly reduced expression of pro-inflammatory mediators and a corresponding enhancement of anti-inflammatory cytokine expression in the hippocampus. Furthermore, treadmill exercise caused a robust suppression of oxidative damage as evidenced by significantly reduced peroxynitrite production, lipid peroxidation, and oxidized DNA damage. Finally, treadmill exercise strongly attenuated STZ-induced mitochondrial dysfunction manifested by a dramatically elevated intra-mitochondrial cytochrome c oxidase activity and ATP synthesis, and markedly inhibited neuronal apoptosis in the hippocampus. These findings demonstrate that treadmill exercise has a multifactorial effect to attenuate many of the pathological processes that play a key role in AD, and provide further support for the beneficial role of exercise as a potential therapeutic option in AD treatment.
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Physical effects of magnetic fields on the Kelvin-Helmholtz instability in a free shear layer
NASA Astrophysics Data System (ADS)
Liu, Y.; Chen, Z. H.; Zhang, H. H.; Lin, Z. Y.
2018-04-01
The Kelvin-Helmholtz instability of a parallel shear flow with a hyperbolic-tangent velocity profile has been simulated numerically at a high Reynolds number. The fluid is perfectly conducting with low viscosity, and the strength of the applied magnetic field varies from weak to strong. We found that the magnetic field parallel to the mainstream direction has a stabilizing effect on the shear flow. The magnetic field mainly stabilizes short-wave perturbations. Small viscosity and/or slight compressibility could introduce some instability even in the presence of a strong magnetic field in a certain circumstance. The suppressing effect of the magnetic field on the instability is accomplished by two parts: the separating effect of the transverse magnetic pressure and the anti-bending effect of magnetic tension pointing to the center of curvature. The former shows prevailingly stronger effect on the fluid interface than the latter does, which is different from the conventional opinion that magnetic tension dominates. Essentially it is mainly the Maxwell stress that weakens and balances the momentum transport conducted by the Reynolds stress, reducing the mixing degree of the upper fluid and the lower fluid.
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Sayers, W Michael; Sayette, Michael A
2013-09-01
Research on emotion suppression has shown a rebound effect, in which expression of the targeted emotion increases following a suppression attempt. In prior investigations, participants have been explicitly instructed to suppress their responses, which has drawn the act of suppression into metaconsciousness. Yet emerging research emphasizes the importance of nonconscious approaches to emotion regulation. This study is the first in which a craving rebound effect was evaluated without simultaneously raising awareness about suppression. We aimed to link spontaneously occurring attempts to suppress cigarette craving to increased smoking motivation assessed immediately thereafter. Smokers (n = 66) received a robust cued smoking-craving manipulation while their facial responses were videotaped and coded using the Facial Action Coding System. Following smoking-cue exposure, participants completed a behavioral choice task previously found to index smoking motivation. Participants evincing suppression-related facial expressions during cue exposure subsequently valued smoking more than did those not displaying these expressions, which suggests that internally generated suppression can exert powerful rebound effects.
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A Post-Transcriptional Feedback Mechanism for Noise Suppression and Fate Stabilization
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hansen, Maike M. K.; Wen, Winnie Y.; Ingerman, Elena
Diverse biological systems utilize fluctuations (“noise”) in gene expression to drive lineage-commitment decisions. However, once a commitment is made, noise becomes detrimental to reliable function, and the mechanisms enabling post-commitment noise suppression are unclear. Here, we find that architectural constraints on noise suppression are overcome to stabilize fate commitment. Using single-molecule and time-lapse imaging, we find that—after a noise-driven event—human immunodeficiency virus (HIV) strongly attenuates expression noise through a non-transcriptional negative-feedback circuit. Feedback is established through a serial cascade of post-transcriptional splicing, whereby proteins generated from spliced mRNAs auto-deplete their own precursor unspliced mRNAs. Strikingly, this auto-depletion circuitry minimizes noisemore » to stabilize HIV’s commitment decision, and a noise-suppression molecule promotes stabilization. Lastly, this feedback mechanism for noise suppression suggests a functional role for delayed splicing in other systems and may represent a generalizable architecture of diverse homeostatic signaling circuits.« less
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A Post-Transcriptional Feedback Mechanism for Noise Suppression and Fate Stabilization
Hansen, Maike M. K.; Wen, Winnie Y.; Ingerman, Elena; ...
2018-05-10
Diverse biological systems utilize fluctuations (“noise”) in gene expression to drive lineage-commitment decisions. However, once a commitment is made, noise becomes detrimental to reliable function, and the mechanisms enabling post-commitment noise suppression are unclear. Here, we find that architectural constraints on noise suppression are overcome to stabilize fate commitment. Using single-molecule and time-lapse imaging, we find that—after a noise-driven event—human immunodeficiency virus (HIV) strongly attenuates expression noise through a non-transcriptional negative-feedback circuit. Feedback is established through a serial cascade of post-transcriptional splicing, whereby proteins generated from spliced mRNAs auto-deplete their own precursor unspliced mRNAs. Strikingly, this auto-depletion circuitry minimizes noisemore » to stabilize HIV’s commitment decision, and a noise-suppression molecule promotes stabilization. Lastly, this feedback mechanism for noise suppression suggests a functional role for delayed splicing in other systems and may represent a generalizable architecture of diverse homeostatic signaling circuits.« less
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Protection of brain and pancreas from high-fat diet: effects of catechin and caffeine.
Unno, Keiko; Yamamoto, Hiroyuki; Maeda, Ken-Ichi; Takabayashi, Fumiyo; Yoshida, Hirotoshi; Kikunaga, Naomi; Takamori, Nina; Asahina, Shunsuke; Iguchi, Kazuaki; Sayama, Kazutoshi; Hoshino, Minoru
2009-02-16
To investigate the effect of a high-fat diet on brain and pancreas functions, we used SAMP10 mice that have characteristics of brain atrophy and cognitive dysfunction with aging. Simultaneously, we investigated the effect of green tea catechin consumption on high-fat diet feeding, because green tea catechin has been reported to improve brain atrophy, brain dysfunction and obesity. The body weight of mice fed a high-fat diet from 2 to 12 months was higher than that of the control, although the calorie intake was not. The high-fat diet also increased insulin secretion; however, the hypersecretion of insulin and obesity were suppressed when mice were fed a high-fat diet with green tea catechin and caffeine. Furthermore, brain atrophy was suppressed and the working memory, tested using Y-maze, improved in mice fed a high-fat diet containing green tea catechin and caffeine. The secretion of insulin might affect both obesity and brain function. A strong correlation was found between working memory and insulin release in mice fed a high-fat diet with green tea catechin and/or caffeine. The results indicate the protective effect of green tea catechin and caffeine on the functions of brain and pancreas in mice fed a high-fat diet.
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Zhang, Rong; Wu, Qun; Xu, Yan
2014-08-20
Nonvolatile compounds play important roles in the quality of alcoholic beverages. In our previous work, a type of cyclooctapeptide lichenysin was newly identified in Chinese strong-aroma type liquor. In this work, it was found that lichenysin could selectively affect aroma volatility in strong-aroma type (Jiannanchun) liquor. Interaction of lichenysin and volatile phenolic compounds (off-odors in strong-aroma type liquor) was characterized using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS). HS-SPME results indicated that lichenysin very efficiently suppressed the volatility of phenolic compounds by 36-48% (P < 0.05). Thermodynamic analysis showed that the binding process was mainly mediated by hydrogen bonding. Furthermore, the mixture of lichenysin and 4-ethylguaiacol revealed intermolecular cross peaks between the aH (Val) of lichenysin and the 1H of 4-ethylguaiacol, by using nuclear Overhauser effect spectroscopy. This study will help to further understand the interaction mechanisms between flavor and nonvolatile matrix components in Chinese liquors.
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Xu, Bing; Dai, Yaomin M.; Zhao, Lingxiao X.; ...
2017-03-30
Strong coupling between discrete phonon and continuous electron–hole pair excitations can induce a pronounced asymmetry in the phonon line shape, known as the Fano resonance. This effect has been observed in various systems. We reveal explicit evidence for strong coupling between an infrared-active phonon and electronic transitions near the Weyl points through the observation of a Fano resonance in the Weyl semimetal TaAs. The resulting asymmetry in the phonon line shape, conspicuous at low temperatures, diminishes continuously with increasing temperature. Furthermore, this behaviour originates from the suppression of electronic transitions near the Weyl points due to the decreasing occupation ofmore » electronic states below the Fermi level (EF) with increasing temperature, as well as Pauli blocking caused by thermally excited electrons above EF. These findings not only elucidate the mechanism governing the tunable Fano resonance but also open a route for exploring exotic physical phenomena through phonon properties in Weyl semimetals.« less
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NASA Astrophysics Data System (ADS)
Ayuso, David; Decleva, Piero; Patchkovskii, Serguei; Smirnova, Olga
2018-06-01
The generation of high-order harmonics in a medium of chiral molecules driven by intense bi-elliptical laser fields can lead to strong chiroptical response in a broad range of harmonic numbers and ellipticities (Ayuso et al 2018 J. Phys. B: At. Mol. Opt. Phys. 51 06LT01). Here we present a comprehensive analytical model that can describe the most relevant features arising in the high-order harmonic spectra of chiral molecules driven by strong bi-elliptical fields. Our model recovers the physical picture underlying chiral high-order harmonic generation (HHG) based on ultrafast chiral hole motion and identifies the rotationally invariant molecular pseudoscalars responsible for chiral dynamics. Using the chiral molecule propylene oxide as an example, we show that one can control and enhance the chiral response in bi-elliptical HHG by tailoring the driving field, in particular by tuning its frequency, intensity and ellipticity, exploiting a suppression mechanism of achiral background based on the linear Stark effect.
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Top predators negate the effect of mesopredators on prey physiology.
Palacios, Maria M; Killen, Shaun S; Nadler, Lauren E; White, James R; McCormick, Mark I
2016-07-01
Predation theory and empirical evidence suggest that top predators benefit the survival of resource prey through the suppression of mesopredators. However, whether such behavioural suppression can also affect the physiology of resource prey has yet to be examined. Using a three-tier reef fish food web and intermittent-flow respirometry, our study examined changes in the metabolic rate of resource prey exposed to combinations of mesopredator and top predator cues. Under experimental conditions, the mesopredator (dottyback, Pseudochromis fuscus) continuously foraged and attacked resource prey (juveniles of the damselfish Pomacentrus amboinensis) triggering an increase in prey O2 uptake by 38 ± 12·9% (mean ± SE). The visual stimulus of a top predator (coral trout, Plectropomus leopardus) restricted the foraging activity of the mesopredator, indirectly allowing resource prey to minimize stress and maintain routine O2 uptake. Although not as strong as the effect of the top predator, the sight of a large non-predator species (thicklip wrasse, Hemigymnus melapterus) also reduced the impact of the mesopredator on prey metabolic rate. We conclude that lower trophic-level species can benefit physiologically from the presence of top predators through the behavioural suppression that top predators impose on mesopredators. By minimizing the energy spent on mesopredator avoidance and the associated stress response to mesopredator attacks, prey may be able to invest more energy in foraging and growth, highlighting the importance of the indirect, non-consumptive effects of top predators in marine food webs. © 2016 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.
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Brennan, J F; Jastreboff, P J
1991-01-01
Tonal frequency generalization was examined in a total of 114 pigmented male rats, 60 of which were tested under the influence of salicylate-induced phantom auditory perception, introduced before or after lick suppression training. Thirty control subjects received saline injections, and the remaining 24 subjects served as noninjected controls of tonal background effects on generalization. Rats were continuously exposed to background noise alone or with a superimposed tone. Offset of background noise alone (Experiment I), or combined with onset or continuation of the tone (Experiments II and III) served as the conditioned stimulus (CS). In Experiment I, tone presentations were introduced only after suppression training. Depending on the time of salicylate introduction, a strong and differential influence on generalization gradients was observed, which is consistent with subjects' detection of salicylate-induced, high-pitched sound. Moreover, when either 12- or 3 kHz tones were introduced before or after Pavlovian training to mimic salicylate effects in 24 rats, the distortions in generalization gradients resembled trends obtained from respective salicylate injected groups. Experiments II and III were aimed at evaluating the masking effect of salicylate-induced phantom auditory perception on external sounds, with a 5- or a 10-kHz tone imposed continuously on the noise or presented only during the CS. Tests of tonal generalization to frequencies ranging from 4- to 11- kHz showed that in this experimental context salicylate-induced perception did not interfere with the dominant influence of external tones, a result that further strengthens the conclusion of Experiment I.
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Schroecksnadel, Katharina; Winkler, Christiana; Wirleitner, Barbara; Schennach, Harald; Weiss, Günter; Fuchs, Dietmar
2005-01-01
Inflammation, immune activation and oxidative stress play a major role in the pathogenesis of cardiovascular disorders. In addition to markers of inflammation, moderate hyperhomocysteinemia is an independent risk factor for cardiovascular disease, and there is a link between the activation of immunocompetent cells and the enhanced formation of homocysteine in vitro. Likewise, anti-inflammatory drugs and nutrients rich in antioxidant vitamins are able to reduce cardiovascular risk and to slow down the atherogenic process. Resveratrol, a phenolic antioxidant synthesized in grapes and vegetables and present in wine, has also been supposed to be beneficial for the prevention of cardiovascular events. Apart from its strong antioxidant properties, resveratrol has also been demonstrated to act as an anti-inflammatory agent. In this study the influence of resveratrol on the production of homocysteine by stimulated human peripheral blood mononuclear cells (PBMCs) was investigated. Results were compared to earlier described effects of the anti-inflammatory compounds aspirin and salicylic acid and of the lipid-lowering drug atorvastatin. Stimulation of PBMCs with the mitogens concanavalin A and phytohemagglutinin induced significantly higher homocysteine accumulation in supernatants compared with unstimulated cells. Treatment with 10-100 muM resveratrol suppressed homocysteine formation in a dose-dependent manner. Resveratrol did not influence the release of homocysteine from resting PBMCs. The data suggest that resveratrol may prevent homocysteine accumulation in the blood by suppressing immune activation cascades and the proliferation of mitogen-driven T-cells. The effect of resveratrol to down-regulate the release of homo-cysteine was comparable to the decline of neopterin concentrations in the same experiments. The suppressive effect of resveratrol was very similar to results obtained earlier with aspirin, salicylic acid and atorvastatin; however, it appeared that doses of compounds needed to reduce homocysteine levels to 50% of stimulated cells were always slightly lower than those necessary to achieve the same effect on neopterin concentrations. The influence of resveratrol and of all the other compounds on homocysteine production appears to be independent of any direct effect on homocysteine biochemistry.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Obara, Akio; Fujita, Yoshihito; Abudukadier, Abulizi
Metformin, one of the most commonly used drugs for patients with type 2 diabetes, recently has received much attention regarding its anti-cancer action. It is thought that the suppression of mTOR signaling is involved in metformin's anti-cancer action. Although liver cancer is one of the most responsive types of cancer for reduction of incidence by metformin, the molecular mechanism of the suppression of mTOR in liver remains unknown. In this study, we investigated the mechanism of the suppressing effect of metformin on mTOR signaling and cell proliferation using human liver cancer cells. Metformin suppressed phosphorylation of p70-S6 kinase, and ribosomemore » protein S6, downstream targets of mTOR, and suppressed cell proliferation. We found that DEPTOR, an endogenous substrate of mTOR suppression, is involved in the suppressing effect of metformin on mTOR signaling and cell proliferation in human liver cancer cells. Metformin increases the protein levels of DEPTOR, intensifies binding to mTOR, and exerts a suppressing effect on mTOR signaling. This increasing effect of DEPTOR by metformin is regulated by the proteasome degradation system; the suppressing effect of metformin on mTOR signaling and cell proliferation is in a DEPTOR-dependent manner. Furthermore, metformin exerts a suppressing effect on proteasome activity, DEPTOR-related mTOR signaling, and cell proliferation in an AMPK-dependent manner. We conclude that DEPTOR-related mTOR suppression is involved in metformin's anti-cancer action in liver, and could be a novel target for anti-cancer therapy. - Highlights: • We elucidated a novel pathway of metformin's anti-cancer action in HCC cells. • DEPTOR is involved in the suppressing effect of metformin on mTOR signaling. • Metformin increases DEPTOR protein levels via suppression of proteasome activity. • DEPTOR-related mTOR suppression is involved in metformin's anti-cancer action.« less
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Chamberlain, Coral G.; Cerra, Anna
2009-01-01
Purpose The damaging effects of oxidative stress and transforming growth factor-β (TGFβ)-induced transdifferentiation of lens epithelial cells have both been implicated independently in the etiology of cataract. The aim of this study was to investigate whether the presence of antioxidant systems in the lens influences the ability of lens epithelial cells to respond to TGFβ. Methods Whole lenses from young rats were cultured with or without TGFβ in the presence or absence of reduced glutathione (GSH). Lens epithelial explants from weanling rats were used to investigate the effects of GSH and catalase on TGFβ-induced cataract-related changes. Lenses were monitored for opacification for three to four days, photographed, and then processed for routine histology. Explants were assessed by phase contrast microscopy, enzyme-linked immunosorbent assay (ELISA) of α-smooth muscle actin (αSMA), and/or immunolocalization of αSMA and Pax6, markers for transdifferentiation and normal lens epithelial phenotype, respectively. Results In cultured lenses, GSH strongly suppressed TGFβ-induced opacification and subcapsular plaque formation. In explants, both GSH and catalase suppressed changes typically associated with TGFβ-induced transdifferentiation including wrinkling of the lens capsule, cell-surface blebbing, apoptotic cell loss, induction of αSMA, and loss of Pax6 expression. Conclusions This study suggests that antioxidant systems present in the normal lens, which protect the epithelium against the damaging effects of reactive oxygen species, may also serve to protect it against the potentially cataractogenic effects of TGFβ. Taken together with other recent studies, it also raises the possibility that TGFβ may induce cataract-related changes in lens epithelial cells via release of hydrogen peroxide. PMID:19421408
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Yiting; Tu, Qunfei; Yan, Wei
Highlights: • CXC195 exhibited significant anti-proliferative effect and induced cell cycle arrest in LPS-induced HepG2 cells. • CXC195 suppressed the release of pro-inflammatory mediators in LPS-induced HepG2 cells. • CXC195 regulated TLR4-MyD88-TAK1-mediated NF-κB and MAPK pathway in LPS-induced HepG2 cells. - Abstract: CXC195 showed strong protective effects in neuronal apoptosis by exerting its antioxidant activity. However, the anti-cancer effects of CXC195 is still with limited acquaintance. Here, we investigated the role of CXC195 in lipopolysaccharide (LPS)-induced human hepatocellular carcinoma (HCC) cells lines (HepG2) and the possible signaling pathways. CXC195 exhibited significant anti-proliferative effect and induced cell cycle arrest in LPS-inducedmore » HepG2 cells. In addition, CXC195 suppressed the release of pro-inflammatory mediators in LPS-induced HepG2 cells, including TNF-α, iNOS, IL-1β, IL-6, CC chemokine ligand (CCL)-2, CCL-22 and epidermal growth factor receptor (EGFR). Moreover, CXC195 inhibited the expressions and interactions of TLR4, MyD88 and TAK1, NF-κB translocation to nucleus and its DNA binding activity, phosphorylation of ERK1/2, p38 and JNK. Our results suggested that treatment with CXC195 could attenuate the TLR4-mediated proliferation and inflammatory response in LPS-induced HepG2 cells, thus might be beneficial for the treatment of HCC.« less
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Thompson, Dennis; Ooi, Tze C; Anderson, David R; Fisher, Ray; Ewan, Bruce C R
2016-07-01
An earlier demonstration that the relative concentrations of isomers of polychlorinated dibenzofuran do not vary as the flamefront of an iron ore sinter plant progresses through the bed, and profiles are similar for two sinter strands has been widened to include studies of the similarity or otherwise between full scale strand and sinter pot profiles, effect of addition of suppressants and of coke fuel substitution with other combustible materials. For dioxin suppressant addition, a study of the whole of the tetra- penta- and hexaCDF isomer range as separated by the DB5MS chromatography column, indicates no significant change in profile: examination of the ratios of the targeted penta- and hexaCDF isomers suggests the profile is similarly unaffected by coke fuel replacement. Addition of KCl at varied levels has also been shown to have no effect on the 'fingerprint' and there is no indication of any effect by the composition of the sinter mix. The recently published full elution sequence for the DB5MS column is applied to the results obtained using this column. It is confirmed that isomers with 1,9-substitution of chlorine atoms are invariably formed in low concentrations. This is consistent with strong interaction between the 1 and 9 substituted chlorine atoms predicted by DFT thermodynamic calculations. Non-1,9-substituted PCDF equilibrium isomer distributions based on DFT-derived thermodynamic data differ considerably from stack gas distributions obtained using SP2331 column separation. A brief preliminary study indicates the same conclusions (apart from the 1,9-interaction effect) hold for the much smaller content of PCDD. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Developing tTA Transgenic Rats for Inducible and Reversible Gene Expression
Zhou, Hongxia; Huang, Cao; Yang, Min; Landel, Carlisle P; Xia, Pedro Yuxing; Liu, Yong-Jian; Xia, Xu Gang
2009-01-01
To develop transgenic lines for conditional expression of desired genes in rats, we generated several lines of the transgenic rats carrying the tetracycline-controlled transactivator (tTA) gene. Using a vigorous, ubiquitous promoter to drive the tTA transgene, we obtained widespread expression of tTA in various tissues. Expression of tTA was sufficient to strongly activate its reporter gene, but was below the toxicity threshold. We examined the dynamics of Doxycycline (Dox)-regulated gene expression in transgenic rats. In the two transmittable lines, tTA-mediated activation of the reporter gene was fully subject to regulation by Dox. Dox dose-dependently suppressed tTA-activated gene expression. The washout time for the effects of Dox was dose-dependent. We tested a complex regime of Dox administration to determine the optimal effectiveness and washout duration. Dox was administered at a high dose (500 μg/ml in drinking water) for two days to reach the effective concentration, and then was given at a low dose (20 μg/ml) to maintain effectiveness. This regimen of Dox administration can achieve a quick switch between ON and OFF statuses of tTA-activated gene expression. In addition, administration of Dox to pregnant rats fully suppressed postnatal tTA-activated gene expression in their offspring. Sufficient levels of Dox are present in mother's milk to produce maximal efficacy in nursing neonates. Administration of Dox to pregnant or nursing rats can provide a continual suppression of tTA-dependent gene expression during embryonic and postnatal development. The tTA transgenic rat allows for inducible and reversible gene expression in the rat; this important tool will be valuable in the development of genetic rat models of human diseases. PMID:19214245
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NASA Astrophysics Data System (ADS)
Rylkov, V. V.; Nikolaev, S. N.; Demin, V. A.; Emelyanov, A. V.; Sitnikov, A. V.; Nikiruy, K. E.; Levanov, V. A.; Presnyakov, M. Yu.; Taldenkov, A. N.; Vasiliev, A. L.; Chernoglazov, K. Yu.; Vedeneev, A. S.; Kalinin, Yu. E.; Granovsky, A. B.; Tugushev, V. V.; Bugaev, A. S.
2018-03-01
The properties of (CoFeB) x (LiNbO y )100- x nanocomposite films with a ferromagnetic alloy content x = 6-48 at % are comprehensively studied. The films are shown to consist of ensembles of CoFe granules 2-4 nm in size, which are strongly elongated (up to 10-15 nm) in the nanocomposite growth direction and are located in an LiNbO y matrix with a high content of Fe2+ and Co2+ magnetic ions (up to 3 × 1022 cm-3). At T ≤ 25 K, a paramagnetic component of the magnetization of nanocomposites is detected along with a ferromagnetic component, and the contribution of the former component is threefold that of the latter. A hysteresis of the magnetization is observed below the percolation threshold up to x ≈ 33 at %, which indicates the appearance of a superferromagnetic order in the nanocomposites. The temperature dependence of the electrical conductivity of the nanocomposites in the range T ≈ 10-200 K on the metallic side of the metal-insulator transition (44 at % < x < 48 at %) is described by a logarithmic law σ( T) ∝ ln T. This law changes into the law of "1/2" at x ≤ 40 at %. The tunneling anomalous Hall effect is strongly suppressed and the longitudinal conductivity turns out to be lower than in a (CoFeB) x (AlO y )100- x composite material by an order of magnitude. The capacitor structures based on (CoFeB) x (LiNbO y )100- x films exhibit resistive switching effects. They are related to (i) the formation of isolated chains of elongated granules and an anomalously strong decrease in the resistance in fields E > 104 V/cm because of the suppression of Coulomb blockage effects and the generation of oxygen vacancies V O and (ii) the injection (or extraction) of V O vacancies (depending on the sign of voltage) into a strongly oxidized layer in the nanocomposites, which is located near an electrode of the structure and controls its resistance. The number of stable resistive switchings exceeds 105 at a resistance ratio R off/ R on 50.
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Nishimura, Hidekazu
2012-11-01
Several Japanese companies sell electrical devices advertised as effective in inactivating viruses and killing bacteria by releasing special materials, e.g., Plasmacluster ions, Nanoe particle and minus ions, into the air. These companies claim that their devices killed bacteria on plates in their own experiments. We tested device effectiveness using the same experiments from the Plasmacluster ioniser SHARP Co., Japan, the Nanoe generator Panasonic Co., Japan, and the Vion KING JIM Co., Japan, to test their advertising claims. Bactericidal ability on agar plate was tested, using Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus, and Enterococcus faecalis as follows: the medium containing a certain amount of each bacterium was put onto an agar plate and smeared. Plates were kept in a closed chamber (inner volume 14.4 m3) or a glove box (inner volume 0.2 m), with one of the devices run for 2 hours. Plates not exposed to any device were used as controls. Each plate was retrieved and put in an incubator to count the number of bacterial colonies formed on the plate. There was no significant difference in the number of colonies on plates exposed to devices compared to control, in the number for all devices, or in all bacteria tested in experiments in the 14.4 m3 chamber. These results strongly suggest that these devices have almost no bactericidal effect, at least in space exceeding this volume. Colony formation was suppressed in the glove box in all devices and in all bacteria tested except P. aeruginosa, although the degree of suppression differed among experiments. The colony formation suppression mechanism was analyzed, and indicated that:colony formation did not change even after the removal of Plasmacluster ions, Nanoe particles, or negative ions from the air, while colony formation was decreased drastically by the removal of ozone from space, which was revealed to be generated inevitably during device operation. These results strongly suggest that the bactericidal effect seen only on the agar plate in narrow space was explained by ozone released in space as a by-product, not by special materials as advertising claimed. It is thus important to analyze the effect of special materials such as those done in this study and to suggest the involvement of ozone as the true cause, as have been done in this study, in evaluating bactericidal effect or viral inactivation as advertised by these companies.
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Local Dynamics of Acid- and Ion-containing Copolymer Melts
NASA Astrophysics Data System (ADS)
Winey, Karen; Middleton, Robert; Tarver, Jacob; Tyagi, Madhusudan; Soles, Christopher; Frischknecht, Amalie
Interest in acid- and ion-containing polymers arises in part from applications as single-ion conductors for selectively transporting a counter ion for battery applications. Structurally, the low dielectric constant of organic polymers and strong ionic interactions leads to ionic aggregation. Here the polymer backbone motion was investigated through quasi-elastic neutron scattering measurements (QENS) and compared with fully atomistic molecular dynamic simulations of precise poly(ethylene-acrylic acid) copolymers and their ionomers (pxAA-y%Li). The effect of carbon spacer length (x =9, 15, 21) between the acid groups and the degree of neutralization (y) with Li on PE backbone dynamics were considered. Systematic slowing in chain dynamics were observed with increasing neutralization where polymer dynamics appear constrained due to anchoring effects. Simulations provide complementary viewpoints indicating a gradient in chain dynamics as a distance away from acid groups. These results indicate that the addition of pendant acid groups inhibit typical PE backbone motion and the neutralized forms strongly suppress the fraction of mobile PE chain.
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Coherent Exciton Dynamics in the Presence of Underdamped Vibrations
Dijkstra, Arend G.; Wang, Chen; Cao, Jianshu; ...
2015-01-22
Recent ultrafast optical experiments show that excitons in large biological light-harvesting complexes are coupled to molecular vibration modes. These high-frequency vibrations will not only affect the optical response, but also drive the exciton transport. Here, using a model dimer system, the frequency of the underdamped vibration is shown to have a strong effect on the exciton dynamics such that quantum coherent oscillations in the system can be present even in the case of strong noise. Two mechanisms are identified to be responsible for the enhanced transport efficiency: critical damping due to the tunable effective strength of the coupling to themore » bath, and resonance coupling where the vibrational frequency coincides with the energy gap in the system. The interplay of these two mechanisms determines parameters responsible for the most efficient transport, and these optimal control parameters are comparable to those in realistic light-harvesting complexes. Interestingly, oscillations in the excitonic coherence at resonance are suppressed in comparison to the case of an off-resonant vibration.« less
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Van der Does, Dieuwertje; Leon-Reyes, Antonio; Koornneef, Annemart; Van Verk, Marcel C; Rodenburg, Nicole; Pauwels, Laurens; Goossens, Alain; Körbes, Ana P; Memelink, Johan; Ritsema, Tita; Van Wees, Saskia C M; Pieterse, Corné M J
2013-02-01
Antagonism between the defense hormones salicylic acid (SA) and jasmonic acid (JA) plays a central role in the modulation of the plant immune signaling network, but the molecular mechanisms underlying this phenomenon are largely unknown. Here, we demonstrate that suppression of the JA pathway by SA functions downstream of the E3 ubiquitin-ligase Skip-Cullin-F-box complex SCF(COI1), which targets JASMONATE ZIM-domain transcriptional repressor proteins (JAZs) for proteasome-mediated degradation. In addition, neither the stability nor the JA-induced degradation of JAZs was affected by SA. In silico promoter analysis of the SA/JA crosstalk transcriptome revealed that the 1-kb promoter regions of JA-responsive genes that are suppressed by SA are significantly enriched in the JA-responsive GCC-box motifs. Using GCC:GUS lines carrying four copies of the GCC-box fused to the β-glucuronidase reporter gene, we showed that the GCC-box motif is sufficient for SA-mediated suppression of JA-responsive gene expression. Using plants overexpressing the GCC-box binding APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factors ERF1 or ORA59, we found that SA strongly reduces the accumulation of ORA59 but not that of ERF1. Collectively, these data indicate that the SA pathway inhibits JA signaling downstream of the SCF(COI1)-JAZ complex by targeting GCC-box motifs in JA-responsive promoters via a negative effect on the transcriptional activator ORA59.
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Parriot, Sandi; Hudson, Thomas H.; Lang, Thierry; Ngundam, Franklyn; Leed, Susan; Sena, Jenell; Harris, Michael; O'Neil, Michael; Sciotti, Richard; Read, Lisa; Lecoeur, Herve; Grogl, Max
2017-01-01
ABSTRACT In any drug discovery and development effort, a reduction in the time of the lead optimization cycle is critical to decrease the time to license and reduce costs. In addition, ethical guidelines call for the more ethical use of animals to minimize the number of animals used and decrease their suffering. Therefore, any effort to develop drugs to treat cutaneous leishmaniasis requires multiple tiers of in vivo testing that start with higher-throughput efficacy assessments and progress to lower-throughput models with the most clinical relevance. Here, we describe the validation of a high-throughput, first-tier, noninvasive model of lesion suppression that uses an in vivo optical imaging technology for the initial screening of compounds. A strong correlation between luciferase activity and the parasite load at up to 18 days postinfection was found. This correlation allows the direct assessment of the effects of drug treatment on parasite burden. We demonstrate that there is a strong correlation between drug efficacy measured on day 18 postinfection and the suppression of lesion size by day 60 postinfection, which allows us to reach an accurate conclusion on drug efficacy in only 18 days. Compounds demonstrating a significant reduction in the bioluminescence signal compared to that in control animals can be tested in lower-throughput, more definitive tests of lesion cure in BALB/c mice and Golden Syrian hamsters (GSH) using Old World and New World parasites. PMID:28137819
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Gao, Jian-Li; Shui, Yan-Mei; Jiang, Wei; Huang, En-Yi; Shou, Qi-Yang; Ji, Xin; He, Bai-Cheng; Lv, Gui-Yuan; He, Tong-Chuan
2016-01-01
Hypoxic in the tumor mass is leading to the myeloproliferative-like disease (leukemoid reaction) and anemia of body, which characterized by strong extensive extramedullary hematopoiesis (EMH) in spleen. As the key transcription factor of hypoxia, hypoxia-inducible factor-1 (HIF-1) activates the expression of genes essential for EMH processes including enhanced blood cell production and angiogenesis. We found ursolic acid (UA), a natural pentacyclic triterpenoid carboxylic acid, inhibited growth of breast cancer both in vivo and in vitro. The suppression was mediated through the inhibition of multiple cell pathways linked to inflammation, proliferation, angiogenesis, and metastasis. UA also suppressed the leukemoid reaction and the EMH phenomenon of the tumor bearing mice without any significant suppression on body weight (i.p. by 20 mg/kg for 28 days). This is associated with the significant decrease in white blood cells (WBC), platelets (PLT) and spleen weight. During this process, we also detected the down-regulation of cell proliferative genes (PCNA, and β-catenin), and metastatic genes (VEGF, and HIF-1α), as well as the depression of nuclear protein intensity of HIF-1α. Furthermore, the expression of E2F1, p53 and MDM2 genes were increased in UA group when the VEGF and HIF-1α was over-expressed. Cancer cells were sensitive to UA treating after the silencing of HIF-1α and the response of Hypoxic pathway reporter to UA was suppressed when HIF-1α was over expressed. Overall, our results from experimental and predictive studies suggest that the anticancer activity of UA may be at least in part caused by suppressing the cancer hypoxia and hypoxia-mediated EMH. PMID:27708244
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Wu, Kevin J; Gregory, T Stan; Boland, Brian L; Zhao, Wujun; Cheng, Rui; Mao, Leidong; Tse, Zion Tsz Ho
2018-06-01
Higher risk patient populations require continuous physiological monitoring and, in some cases, connected life-support systems, during magnetic resonance imaging examinations. While recently there has been a shift toward wireless technology, some of the magnetic resonance imaging devices are still connected to the outside using cabling that could interfere with the magnetic resonance imaging's radio frequency during scanning, resulting in excessive heating. We developed a passive method for radio frequency suppression on cabling that may assist in making some of these devices magnetic resonance imaging compatible. A barrel-shaped strongly paramagnetic choke was developed to suppress induced radio frequency signals which are overlaid onto physiological monitoring leads during magnetic resonance imaging. It utilized a choke placed along the signal lines, with a gadolinium solution core. The choke's magnetic susceptibility was modeled, for a given geometric design, at increasing chelate concentration levels, and measured using a vibrating sample magnetometer. Radio frequency noise suppression versus frequency was quantified with network-analyzer measurements and tested using cabling placed in the magnetic resonance imaging scanner. Temperature-elevation and image-quality reduction due to the device were measured using American Society for Testing and Materials phantoms. Prototype chokes with gadolinium solution cores exhibited increasing magnetic susceptibility, and insertion loss (S21) also showed higher attenuation as gadolinium concentration increased. Image artifacts extending <4 mm from the choke were observed during magnetic resonance imaging, which agreed well with the predicted ∼3 mm artifact from the electrochemical machining simulation. An accompanying temperature increase of <1 °C was observed in the magnetic resonance imaging phantom trial. An effective paramagnetic choke for radio frequency suppression during magnetic resonance imaging was developed and its performance demonstrated.
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Wei, Ping; Hu, Guo-Hua; Kang, Hou-Yong; Yao, Hong-Bing; Kou, Wei; Liu, Hong; Zhang, Cheng; Hong, Su-Ling
2014-05-01
A predominant Th17 population is a marker of allergic rhinitis (AR). The aryl hydrocarbon receptor (AhR) exhibits strong immunomodulation potential via regulation of the differentiation of T lymphocytes and dendritic cells (DCs) after activation by its ligand, such as 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE). The aim of this study was to analyze the effect of AhR on Th17 differentiation by investigating the action of ITE on DCs and CD4(+) T cells from patients with AR. In all, 26 AR patients and 12 healthy controls were included in this study. The expression of interleukin (IL)-1β, IL-6, IL-10, and IL-17 in the culture supernatant and the presence of Th17 cells in CD4(+) T cells and DC-CD4(+) T-cell co-culture system were measured before and after treatment with ITE. We show that ITE significantly induced cell secretion of IL-10 and inhibited IL-1β and IL-6 production in DCs, and promoted IL-10 production and suppressed IL-17 expression in CD4(+) T cells in vitro. It also suppressed the expansion of Th17 cells in vitro. Our work demonstrates that ITE acts on DCs and CD4(+) T cells to inhibit the Th17 response that suppresses AR; the AhR-DC-Th17 axis may be an important pathway in the treatment of AR. ITE, a nontoxic AhR ligand, attenuated the Th17 response; thus, it appears to be a promising therapeutic candidate for suppressing the inflammatory responses associated with AR.
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Coherent quantum dynamics in steady-state manifolds of strongly dissipative systems.
Zanardi, Paolo; Campos Venuti, Lorenzo
2014-12-12
Recently, it has been realized that dissipative processes can be harnessed and exploited to the end of coherent quantum control and information processing. In this spirit, we consider strongly dissipative quantum systems admitting a nontrivial manifold of steady states. We show how one can enact adiabatic coherent unitary manipulations, e.g., quantum logical gates, inside this steady-state manifold by adding a weak, time-rescaled, Hamiltonian term into the system's Liouvillian. The effective long-time dynamics is governed by a projected Hamiltonian which results from the interplay between the weak unitary control and the fast relaxation process. The leakage outside the steady-state manifold entailed by the Hamiltonian term is suppressed by an environment-induced symmetrization of the dynamics. We present applications to quantum-computation in decoherence-free subspaces and noiseless subsystems and numerical analysis of nonadiabatic errors.
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NASA Astrophysics Data System (ADS)
Sun, Zhiyuan; Basov, Dimitri; Fogler, Michael
We study theoretically the second-order nonlinear optical conductivity σ (2) of graphene as a function of frequency and momentum. We distinguish two regimes. At frequencies ω higher than the temperature-dependent electron-electron collision rate γee- 1 , the conductivity σ (2) can be derived from the semiclassical kinetic equation. The calculation requires taking into account the photon drag (Lorentz force) due to the ac magnetic field. In the low-frequency hydrodynamic regime ω <<γee- 1 , the nonlinear conductivity has a different form and the photon drag effect is suppressed. As a consequence of the nonlinearity, a strong enough photoexcitation can cause spontaneous generation of collective modes in a graphene strip: plasmons in the high-frequency regime and energy waves (demons) in the hydrodynamic one. The dominant instability occurs at frequency ω / 2 .
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Effect of the Crystal Structure on the Electrical Properties of Thin-Film PZT Structures
NASA Astrophysics Data System (ADS)
Delimova, L. A.; Gushchina, E. V.; Zaitseva, N. V.; Seregin, D. S.; Vorotilov, K. A.; Sigov, A. S.
2018-03-01
A new method of two-stage crystallization of lead zirconate-titanate (PZT) films using a seed sublayer with a low excess lead content has been proposed and realized. A seed layer with a strong texture of perovskite Pe(111) grains is formed from a solution with a lead excess of 0-5 wt %; the fast growth of the grains is provided by the deposition of the main film from a solution with high lead content. As a result, a strong Pe(111) texture with complete suppression of the Pe(100) orientation forms. An analysis of current-voltage dependences of the transient currents and the distributions of the local conductivity measured by the contact AFM method reveals two various mechanisms of current percolation that are determined by traps in the bulk and at the perovskite grain interfaces.
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Interbasin effects of the Indian Ocean on Pacific decadal climate change
NASA Astrophysics Data System (ADS)
Mochizuki, Takashi; Kimoto, Masahide; Watanabe, Masahiro; Chikamoto, Yoshimitsu; Ishii, Masayoshi
2016-07-01
We demonstrate the significant impact of the Indian Ocean on the Pacific climate on decadal timescales by comparing two sets of data assimilation experiments (pacemaker experiments) conducted over recent decades. For the Indian Ocean of an atmosphere-ocean coupled global climate model, we assimilate ocean temperature and salinity anomalies defined as deviations from climatology or as anomalies with the area-averaged changes for the Indian Ocean subtracted. When decadal sea surface temperature (SST) trends are observed to be strong over the Indian Ocean, the equatorial thermocline uniformly deepens, and the model simulates the eastward tendencies of surface wind aloft. Surface winds strongly converge around the maritime continent, and the associated strengthening of the Walker circulation suppresses an increasing trend in the equatorial Pacific SST through ocean thermocline shoaling, similar to common changes associated with seasonal Indian Ocean warming.
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Dissociation of face-selective cortical responses by attention.
Furey, Maura L; Tanskanen, Topi; Beauchamp, Michael S; Avikainen, Sari; Uutela, Kimmo; Hari, Riitta; Haxby, James V
2006-01-24
We studied attentional modulation of cortical processing of faces and houses with functional MRI and magnetoencephalography (MEG). MEG detected an early, transient face-selective response. Directing attention to houses in "double-exposure" pictures of superimposed faces and houses strongly suppressed the characteristic, face-selective functional MRI response in the fusiform gyrus. By contrast, attention had no effect on the M170, the early, face-selective response detected with MEG. Late (>190 ms) category-related MEG responses elicited by faces and houses, however, were strongly modulated by attention. These results indicate that hemodynamic and electrophysiological measures of face-selective cortical processing complement each other. The hemodynamic signals reflect primarily late responses that can be modulated by feedback connections. By contrast, the early, face-specific M170 that was not modulated by attention likely reflects a rapid, feed-forward phase of face-selective processing.
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Effect of organic materials used in the synthesis on the emission from CdSe quantum dots
NASA Astrophysics Data System (ADS)
Lee, Jae-Won; Yang, Ho-Soon; Hong, K. S.; Kim, S. M.
2013-12-01
Quantum-dot nanocrystals have particular optical properties due to the quantum confinement effect and the surface effect. This study focuses on the effect of surface conditions on the emission from quantum dots. The quantum dots prepared with 1-hexadecylamine (HDA) in the synthesis show strong emission while the quantum dots prepared without HDA show weak emission, as well as emission from surface energy traps. The comparison of the X-ray patterns of these two sets of quantum dots reveals that HDA forms a layer on the surface of quantum dot during the synthesis. This surface passivation with a layer of HDA reduces surface energy traps, therefore the emission from surface trap levels is suppressed in the quantum dots synthesized with HDA.
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Riosmena, Fernando; Hunter, Lori M.; Runfola, Daniel M.
2015-01-01
Increasing rates of climate migration may be of economic and national concern to sending and destination countries. It has been argued that social networks – the ties connecting an origin and destination – may operate as “migration corridors” with the potential to strongly facilitate climate change-related migration. This study investigates whether social networks at the household and community levels amplify or suppress the impact of climate change on international migration from rural Mexico. A novel set of 15 climate change indices was generated based on daily temperature and precipitation data for 214 weather stations across Mexico. Employing geostatistical interpolation techniques, the climate change values were linked to 68 rural municipalities for which sociodemographic data and detailed migration histories were available from the Mexican Migration Project. Multi-level discrete-time event-history models were used to investigate the effect of climate change on international migration between 1986 and 1999. At the household level, the effect of social networks was approximated by comparing the first to the last move, assuming that through the first move a household establishes internal social capital. At the community level, the impact of social capital was explored through interactions with a measure of the proportion of adults with migration experience. The results show that rather than amplifying, social capital may suppress the sensitivity of migration to climate triggers, suggesting that social networks could facilitate climate change adaptation in place. PMID:26692656
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New antiaxillary odour deodorant made with antimicrobial Ag-zeolite (silver-exchanged zeolite).
Nakane, T; Gomyo, H; Sasaki, I; Kimoto, Y; Hanzawa, N; Teshima, Y; Namba, T
2006-08-01
The causative substances for axillary osmidrosis, which are often found in apocrine sweat, are the decomposed/denatured products of short-chain fatty acid and other biological metabolite compounds produced by axillary-resident bacteria. Conventional underarm deodorants suppress the process of odour production mostly by the following mechanism: (1) suppression of perspiration, (2) reduction in numbers of resident bacteria, (3) deodorization and (4) masking. The most important and effective method to reduce odour is to suppress the growth of resident bacteria with antimicrobials, which have several drawbacks, especially in their safety aspect. To solve these problems, we focused on Ag-zeolite (silver-exchanged zeolite) that hold stable Ag, an inorganic bactericidal agent, in its structure, and therefore, poses less risk in safety. Its bactericidal effect on skin-resident bacteria was found to be excellent and comparable with that of triclosan, a most frequently used organic antimicrobial in this product category. The dose-response study of Ag-zeolite powder spray (0-40 w/w%) using 39 volunteers revealed that 5-40 w/w% Ag-zeolite could show a sufficient antimicrobial effect against skin-resident bacteria. The comparison study using 0.2 w/w% triclosan as the control and 10 w/w% Ag-zeolite indicated that: (1) one application of the powder spray containing 10 w/w% Ag-zeolite could show a sufficient antimicrobial effect against the resident bacteria and its effect continued for 24 h, (2) a powder spray containing 0.2 w/w% triclosan was unable to show a sufficient antimicrobial effect, and (3) no adverse event was observed. These studies show that Ag-zeolite has a superior antimicrobial ability that is rarely found in conventional antimicrobials used in deodorant products and a strong antiaxillary odour deodorant ability because of its long-lasting effect. During clinical study, patch tests with humans and other clinical studies of this product showed no adverse events related to the treatment with the Ag-zeolite product.
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Chen, R H; Su, Y H; Chuang, R L; Chang, T Y
1998-10-15
Insulin and insulin receptor substrate 1 (IRS-1) are capable of protecting liver cells from apoptosis induced by transforming growth factor-beta1 (TGF-beta). The Ras/mitogen-activated protein kinase (MAP kinase) and the phosphatidylinositol 3-kinase (PI 3-kinase)/Akt pathways are both activated upon insulin stimulation and can protect against apoptosis under certain circumstances. We investigated which of these pathways is responsible for the protective effect of insulin on TGF-beta-induced apoptosis. An activated Ras, although elicited a strong mitogenic effect, could not protect Hep3B cells from TGF-beta-induced apoptosis. Furthermore, PD98059, a selective inhibitor of MEK, did not suppress the antiapoptotic effect of insulin. In contrast, the PI 3-kinase inhibitor, LY294002, efficiently blocked the effect of insulin. Protection against TGF-beta-induced apoptosis conferred by PI 3-kinase was further verified by stable transfection of an activated PI 3-kinase. Downstream targets of PI 3-kinase involved in this protection was further investigated. An activated Akt mimicked the antiapoptotic effect of insulin, whereas a dominant-negative Akt inhibited such effect. However, rapamycin, the p70S6 kinase inhibitor, had no effect on the protectivity of insulin against TGF-beta-induced apoptosis, suggesting that the antiapoptotic target of PI 3-kinase/Akt pathway is independent or lies upstream of the p70S6 kinase. The mechanism by which PI 3-kinase/Akt pathway interferes with the apoptotic signaling of TGF-beta was explored. Activation of PI 3-kinase did not lead to a suppression of Smad hetero-oligomerization or nuclear translocation but blocked TGF-beta-induced caspase-3-like activity. In summary, the PI 3-kinase/Akt pathway, but not the Ras/MAP kinase pathway, protects against TGF-beta-induced apoptosis by inhibiting a step downstream of Smad but upstream of caspase-3.
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Cuco, Ana P; Santos, Joana I; Abrantes, Nelson; Gonçalves, Fernando; Wolinska, Justyna; Castro, Bruno B
2017-12-01
Given the importance of pollutant effects on host-parasite relationships and disease spread, the main goal of this study was to assess the influence of different exposure scenarios for the fungicide tebuconazole (concentration×timing of application) on a Daphnia-microparasitic yeast experimental system. Previous results had demonstrated that tebuconazole is able to suppress Metschnikowia bicuspidata infection at ecologically-relevant concentrations; here, we aimed to obtain an understanding of the mechanism underlying the anti-parasitic (fungicidal or fungistatic) action of tebuconazole. We exposed the Daphnia-yeast system to four nominal tebuconazole concentrations at four timings of application (according to the predicted stage of parasite development), replicated on two Daphnia genotypes, in a fully crossed experiment. An "all-or-nothing" effect was observed, with tebuconazole completely suppressing infection from 13.5μgl -1 upwards, independent of the timing of tebuconazole application. A follow-up experiment confirmed that the suppression of infection occurred within a narrow range of tebuconazole concentrations (3.65-13.5μgl -1 ), although a later application of the fungicide had to be compensated for by a slight increase in concentration to elicit the same anti-parasitic effect. The mechanism behind this anti-parasitic effect seems to be the inhibition of M. bicuspidata sporulation, since tebuconazole was effective in preventing ascospore production even when applied at a later time. However, this fungicide also seemed to affect the vegetative growth of the yeast, as demonstrated by the enhanced negative effect of the parasite (increasing mortality in one of the host genotypes) at a later time of application of tebuconazole, when no signs of infection were observed. Fungicide contamination can thus affect the severity and spread of disease in natural populations, as well as the inherent co-evolutionary dynamics in host-parasite systems. Copyright © 2017 Elsevier B.V. All rights reserved.
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2017-08-01
expression of both AR and AR-V7 in CRPC cells, and that knockdown or inhibition of PRMT5 suppresses growth of CRPC cells. These results support our...correlates with the expression of AR [9]. Preliminary data strongly suggest that PRMT5 regulates prostate cancer cell growth through epigenetic...findings as follow. 3B-1. Inhibition of PRMT5 suppresses cell growth and the expression of AR and AR-V7 in CRPC cells. We established inducible
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Strong-coupling Bose polarons out of equilibrium: Dynamical renormalization-group approach
NASA Astrophysics Data System (ADS)
Grusdt, Fabian; Seetharam, Kushal; Shchadilova, Yulia; Demler, Eugene
2018-03-01
When a mobile impurity interacts with a surrounding bath of bosons, it forms a polaron. Numerous methods have been developed to calculate how the energy and the effective mass of the polaron are renormalized by the medium for equilibrium situations. Here, we address the much less studied nonequilibrium regime and investigate how polarons form dynamically in time. To this end, we develop a time-dependent renormalization-group approach which allows calculations of all dynamical properties of the system and takes into account the effects of quantum fluctuations in the polaron cloud. We apply this method to calculate trajectories of polarons following a sudden quench of the impurity-boson interaction strength, revealing how the polaronic cloud around the impurity forms in time. Such trajectories provide additional information about the polaron's properties which are challenging to extract directly from the spectral function measured experimentally using ultracold atoms. At strong couplings, our calculations predict the appearance of trajectories where the impurity wavers back at intermediate times as a result of quantum fluctuations. Our method is applicable to a broader class of nonequilibrium problems. As a check, we also apply it to calculate the spectral function and find good agreement with experimental results. At very strong couplings, we predict that quantum fluctuations lead to the appearance of a dark continuum with strongly suppressed spectral weight at low energies. While our calculations start from an effective Fröhlich Hamiltonian describing impurities in a three-dimensional Bose-Einstein condensate, we also calculate the effects of additional terms in the Hamiltonian beyond the Fröhlich paradigm. We demonstrate that the main effect of these additional terms on the attractive side of a Feshbach resonance is to renormalize the coupling strength of the effective Fröhlich model.
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Perceived emotion suppression and culture: Effects on psychological well-being.
Kwon, Heewon; Kim, Young-Hoon
2018-04-03
Whether the negative effects of emotion suppression on psychological well-being are applicable cross-culturally is a long-debated topic. The present study attempted to shed light on this debate, focusing on the effects of perceived emotion suppression and examining the psychological processes leading from perceived emotion suppression to lower psychological well-being. We used a scale manipulation to lead 196 American and 213 Chinese participants to perceive themselves as having suppressed their emotions to a greater or lesser extent and then measured their life satisfaction. As expected, both the American and Chinese participants reported lower life satisfaction in the high-suppression condition than in the low-suppression condition; this negative effect was mediated by positive affect and moderated by self-esteem. Specifically, perceived high emotion suppression decreased positive affect, which in turn led to lower well-being. This effect was observed only for those with low self-esteem, but the patterns and mechanisms were consistent cross-culturally. © 2018 International Union of Psychological Science.
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NASA Astrophysics Data System (ADS)
Lee, Myoung-Jae; Jung, Young-Dae
2017-05-01
The influence of nonisothermal and quantum shielding on the electron-ion collision process is investigated in strongly coupled two-temperature plasmas. The eikonal method is employed to obtain the eikonal scattering phase shift and eikonal cross section as functions of the impact parameter, collision energy, electron temperature, ion temperature, Debye length, and de Broglie wavelength. The results show that the quantum effect suppresses the eikonal scattering phase shift for the electron-ion collision in two-temperature dense plasmas. It is also found that the differential eikonal cross section decreases for small impact parameters. However, it increases for large impact parameters with increasing de Broglie wavelength. It is also found that the maximum position of the differential eikonal cross section is receded from the collision center with an increase in the nonisothermal character of the plasma. In addition, it is found that the total eikonal cross sections in isothermal plasmas are always greater than those in two-temperature plasmas. The variations of the eikonal cross section due to the two-temperature and quantum shielding effects are also discussed.
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EEHG Performance and Scaling Laws
DOE Office of Scientific and Technical Information (OSTI.GOV)
Penn, Gregory
This note will calculate the idealized performance of echo-enabled harmonic generation performance (EEHG), explore the parameter settings, and look at constraints determined by incoherent synchrotron radiation (ISR) and intrabeam scattering (IBS). Another important effect, time-of-flight variations related to transverse emittance, is included here but without detailed explanation because it has been described previously. The importance of ISR and IBS is that they lead to random energy shifts that lead to temporal shifts after the various beam manipulations required by the EEHG scheme. These effects give competing constraints on the beamline. For chicane magnets which are too compact for a givenmore » R56, the magnetic fields will be sufficiently strong that ISR will blur out the complex phase space structure of the echo scheme to the point where the bunching is strongly suppressed. The effect of IBS is more omnipresent, and requires an overall compact beamline. It is particularly challenging for the second pulse in a two-color attosecond beamline, due to the long delay between the first energy modulation and the modulator for the second pulse.« less
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The immunomodulatory effects of interferon-gamma on mature B-lymphocyte responses.
Jurado, A; Carballido, J; Griffel, H; Hochkeppel, H K; Wetzel, G D
1989-06-15
Interferon-gamma (IFN-gamma) exerts a broad spectrum of activities which affect the responses of mature B-cells. It strongly inhibits B-cell activation, acts as a B-cell growth factor (BCGF), and also induces final differentiation to immunoglobulin (Ig) production. IFN-gamma is deeply involved in the differential control of isotype expression, as it enhances IgG2a production and suppresses both IgG1 and IgE production. Although it is now possible to draw a general scheme of the effects of IFN-gamma on B-cells, a number of paradoxical results still exist in the field. In this manuscript, different experimental systems are analyzed in an attempt to explain these apparent paradoxes.
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NASA Astrophysics Data System (ADS)
Zhavoronkov, N.; Driben, R.; Bregadiolli, B. A.; Nalin, M.; Malomed, B. A.
2011-05-01
We demonstrate experimentally and support by a theoretical analysis an effect of asymmetric spectrum broadening, which results from doping of silver nanoparticles into a heavy-glass matrix, 90(0.5WO3-0.3SbPO4-0.2PbO)-10AgCl. The strong dispersion of the effective nonlinear coefficient of the composite significantly influences the spectral broadening via the self-phase modulation, and leads to a blue upshift of the spectrum. Further extension of the spectrum towards shorter wavelengths is suppressed by a growing loss caused by the plasmon resonance in the silver particles. The red-edge spectral broadening is dominated by the stimulated Raman scattering.
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Edge enhancement and noise suppression for infrared image based on feature analysis
NASA Astrophysics Data System (ADS)
Jiang, Meng
2018-06-01
Infrared images are often suffering from background noise, blurred edges, few details and low signal-to-noise ratios. To improve infrared image quality, it is essential to suppress noise and enhance edges simultaneously. To realize it in this paper, we propose a novel algorithm based on feature analysis in shearlet domain. Firstly, as one of multi-scale geometric analysis (MGA), we introduce the theory and superiority of shearlet transform. Secondly, after analyzing the defects of traditional thresholding technique to suppress noise, we propose a novel feature extraction distinguishing image structures from noise well and use it to improve the traditional thresholding technique. Thirdly, with computing the correlations between neighboring shearlet coefficients, the feature attribute maps identifying the weak detail and strong edges are completed to improve the generalized unsharped masking (GUM). At last, experiment results with infrared images captured in different scenes demonstrate that the proposed algorithm suppresses noise efficiently and enhances image edges adaptively.
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Rolider, A; Van Houten, R
1985-01-01
The effects of a movement suppression time-out, which involved punishing any movement or verbalization while a client is in the time-out area, were evaluated in four experiments. The first experiment examined the effects of a DRO procedure and movement suppression plus DRO in suppressing self-injurious behavior in a psychotic child in three different situations. In Experiment 2, the results of the previous experiment were replicated with two dangerous behaviors in a second psychotic child. In a third experiment, movement suppression plus DRO was compared with contingent restraint in reducing inappropriate poking behavior in two settings. The movement suppression procedure eliminated poking whereas contingent restraint had little effect. In the final experiment, movement suppression time-out alone was compared with exclusionary time-out alone and simple corner time-out alone. Self-stimulation occurred at high levels during the exclusionary and simple corner time-out procedures. Self-stimulation was either suppressed or reduced during movement suppression time-out. The movement suppression time-out procedure produced a larger reduction in the target behavior in all three children. The effectiveness of the movement suppression procedure was explained in terms of the suppression of self-stimulation while the time-out procedure was being applied.
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Topological Constraints in Directed Polymer Melts
NASA Astrophysics Data System (ADS)
Serna, Pablo; Bunin, Guy; Nahum, Adam
2015-11-01
Polymers in a melt may be subject to topological constraints, as in the example of unlinked polymer rings. How to do statistical mechanics in the presence of such constraints remains a fundamental open problem. We study the effect of topological constraints on a melt of directed polymers, using simulations of a simple quasi-2D model. We find that fixing the global topology of the melt to be trivial changes the polymer conformations drastically. Polymers of length L wander in the transverse direction only by a distance of order (ln L )ζ with ζ ≃1.5 . This is strongly suppressed in comparison with the Brownian L1 /2 scaling which holds in the absence of the topological constraint. It is also much smaller than the predictions of standard heuristic approaches—in particular the L1 /4 of a mean-field-like "array of obstacles" model—so our results present a sharp challenge to theory. Dynamics are also strongly affected by the constraints, and a tagged monomer in an infinite system performs logarithmically slow subdiffusion in the transverse direction. To cast light on the suppression of the strands' wandering, we analyze the topological complexity of subregions of the melt: the complexity is also logarithmically small, and is related to the wandering by a power law. We comment on insights the results give for 3D melts, directed and nondirected.
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Topological Constraints in Directed Polymer Melts.
Serna, Pablo; Bunin, Guy; Nahum, Adam
2015-11-27
Polymers in a melt may be subject to topological constraints, as in the example of unlinked polymer rings. How to do statistical mechanics in the presence of such constraints remains a fundamental open problem. We study the effect of topological constraints on a melt of directed polymers, using simulations of a simple quasi-2D model. We find that fixing the global topology of the melt to be trivial changes the polymer conformations drastically. Polymers of length L wander in the transverse direction only by a distance of order (lnL)^{ζ} with ζ≃1.5. This is strongly suppressed in comparison with the Brownian L^{1/2} scaling which holds in the absence of the topological constraint. It is also much smaller than the predictions of standard heuristic approaches-in particular the L^{1/4} of a mean-field-like "array of obstacles" model-so our results present a sharp challenge to theory. Dynamics are also strongly affected by the constraints, and a tagged monomer in an infinite system performs logarithmically slow subdiffusion in the transverse direction. To cast light on the suppression of the strands' wandering, we analyze the topological complexity of subregions of the melt: the complexity is also logarithmically small, and is related to the wandering by a power law. We comment on insights the results give for 3D melts, directed and nondirected.
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Attractive Flicker--Guiding Attention in Dynamic Narrative Visualizations.
Waldner, Manuela; Le Muzic, Mathieu; Bernhard, Matthias; Purgathofer, Werner; Viola, Ivan
2014-12-01
Focus+context techniques provide visual guidance in visualizations by giving strong visual prominence to elements of interest while the context is suppressed. However, finding a visual feature to enhance for the focus to pop out from its context in a large dynamic scene, while leading to minimal visual deformation and subjective disturbance, is challenging. This paper proposes Attractive Flicker, a novel technique for visual guidance in dynamic narrative visualizations. We first show that flicker is a strong visual attractor in the entire visual field, without distorting, suppressing, or adding any scene elements. The novel aspect of our Attractive Flicker technique is that it consists of two signal stages: The first "orientation stage" is a short but intensive flicker stimulus to attract the attention to elements of interest. Subsequently, the intensive flicker is reduced to a minimally disturbing luminance oscillation ("engagement stage") as visual support to keep track of the focus elements. To find a good trade-off between attraction effectiveness and subjective annoyance caused by flicker, we conducted two perceptual studies to find suitable signal parameters. We showcase Attractive Flicker with the parameters obtained from the perceptual statistics in a study of molecular interactions. With Attractive Flicker, users were able to easily follow the narrative of the visualization on a large display, while the flickering of focus elements was not disturbing when observing the context.
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Moyer, Jason T.; Halterman, Benjamin L.; Finkel, Leif H.; Wolf, John A.
2014-01-01
Striatal medium spiny neurons (MSNs) receive lateral inhibitory projections from other MSNs and feedforward inhibitory projections from fast-spiking, parvalbumin-containing striatal interneurons (FSIs). The functional roles of these connections are unknown, and difficult to study in an experimental preparation. We therefore investigated the functionality of both lateral (MSN-MSN) and feedforward (FSI-MSN) inhibition using a large-scale computational model of the striatal network. The model consists of 2744 MSNs comprised of 189 compartments each and 121 FSIs comprised of 148 compartments each, with dendrites explicitly represented and almost all known ionic currents included and strictly constrained by biological data as appropriate. Our analysis of the model indicates that both lateral inhibition and feedforward inhibition function at the population level to limit non-ensemble MSN spiking while preserving ensemble MSN spiking. Specifically, lateral inhibition enables large ensembles of MSNs firing synchronously to strongly suppress non-ensemble MSNs over a short time-scale (10–30 ms). Feedforward inhibition enables FSIs to strongly inhibit weakly activated, non-ensemble MSNs while moderately inhibiting activated ensemble MSNs. Importantly, FSIs appear to more effectively inhibit MSNs when FSIs fire asynchronously. Both types of inhibition would increase the signal-to-noise ratio of responding MSN ensembles and contribute to the formation and dissolution of MSN ensembles in the striatal network. PMID:25505406
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Fladung, Anne-Katharina; Kiefer, Markus
2016-11-01
Men have been frequently found to perform more accurately than women in mental rotation tasks. However, men and women also differ with regard to the habitual use of emotion regulation strategies, particularly with regard to expressive suppression, i.e., the suppression of emotional expression in behavior. As emotional suppression is more often used by men, emotion regulation strategies might be a variable modulating gender differences in mental rotation performance. The present study, therefore, examined the influences of gender and emotion regulation strategies on mental rotation performance accuracy and feedback processing. Twenty-eight men and 28 women matched for relevant demographic variables performed mental rotation tasks of varying difficulty over a prolonged time. Emotional feedback was given immediately after each trial. Results showed that women reported to use expressive suppression less frequently than men. Women made more errors in the mental rotation task than men confirming earlier demonstrations of gender differences. Furthermore, women were more impaired by the negative feedback as indicated by the increased likelihood of subsequent errors compared with men. Task performance of women not habitually using expressive suppression was most inferior and most strongly influenced by failure feedback compared with men. Women using expressive suppression more habitually did not significantly differ in mental rotation accuracy and feedback processing from men. Hence, expressive suppression reduces gender differences in mental rotation accuracy by improving cognitive performance following failure feedback.
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Oda, Hiroaki; Okuda, Yuji; Yoshida, Yukiko; Kimura, Noriko; Kakinuma, Atsushi
2015-10-23
The regulatory mechanism of phosphoenolpyruvate carboykinase (GTP) (EC 4.1.1.32) (PEPCK) gene expression and gluconeogenesis by phenobarbital (PB), which is known to induce drug-metabolizing enzymes, was investigated. Higher level of PEPCK mRNA was observed in spherical rat primary hepatocytes on EHS-gel than monolayer hepatocytes on TIC (type I collagen). We found that PB directly suppressed PEPCK gene expression in spherical hepatocytes on EHS-gel, but not in those on TIC. PB strongly suppressed cAMP-dependent induction of PEPCK gene expression. Tyrosine aminotransferase (TAT), another gluconeogenic enzyme, was induced by cAMP, but not suppressed by PB. Chronic administration of PB reduced hepatic PEPCK mRNA in streptozotocin-induced diabetic and nondiabetic rats, and PB reduced blood glucose level in diabetic rats. Increased TAT mRNA in diabetic rats was not suppressed by PB. These results indicated that PB-dependent reduction is specific to PEPCK. From pyrvate challenge test, PB suppressed the increased gluconeogenesis in diabetic rats. PEPCK gene promoter activity was suppressed by PB in HepG2 cells. In conclusion, we found that spherical hepatocytes cultured on EHS-gel are capable to respond to PB to suppress PEPCK gene expression. Moreover, our results indicate that hypoglycemic action of PB result from transcriptional repression of PEPCK gene and subsequent suppression of gluconeogenesis. Copyright © 2015. Published by Elsevier Inc.
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Effect of thought suppression on desire to smoke and tobacco withdrawal symptoms.
Erskine, James A K; Ussher, Michael; Cropley, Mark; Elgindi, Abdelaziz; Zaman, Manzir; Corlett, Bethan
2012-01-01
Suppressing smoking thoughts has been shown to result in elevated smoking. However, the effect of suppressing smoking thoughts on desire to smoke and withdrawal symptoms has not been investigated. We examined the effects of suppressing smoking thoughts on the subsequent desire to smoke and on tobacco withdrawal symptoms, relative to groups that were either thinking about anything they wished or actively thinking about smoking. A randomised experimental study compared the effects of three manipulations (suppressed smoking thoughts, expressed smoking thoughts and thoughts of anything they wished) on desire and withdrawal immediately after the manipulation and 5 and 10 min after. Suppressing smoking thoughts did not result in elevated subsequent desire to smoke, relative to the other manipulations. Suppressing smoking thoughts resulted in a significant elevation in hunger ratings, relative to the other manipulations, at all measurement times. There were no significant effects for the other withdrawal symptoms. Self-reported greater use of thought suppression in everyday life was significantly associated with greater desire to smoke at baseline and was associated with lower mindfulness scores. Laboratory-instructed suppression of smoking thoughts is associated with increased reports of hunger but did not lead to increases in other withdrawal symptoms or elevated desire to smoke. Reports of everyday use of thought suppression are associated with elevated desire to smoke at baseline. Further investigations need to assess the effect of suppressing smoking cravings, instead of general smoking thoughts, on desire to smoke and tobacco withdrawal.
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TiO2 nanoparticles and bulk material stimulate human peripheral blood mononuclear cells☆
Becker, Kathrin; Schroecksnadel, Sebastian; Geisler, Simon; Carriere, Marie; Gostner, Johanna M.; Schennach, Harald; Herlin, Nathalie; Fuchs, Dietmar
2014-01-01
Nanomaterials are increasingly produced and used throughout recent years. Consequently the probability of exposure to nanoparticles has risen. Because of their small 1–100 nm size, the physicochemical properties of nanomaterials may differ from standard bulk materials and may pose a threat to human health. Only little is known about the effects of nanoparticles on the human immune system. In this study, we investigated the effects of TiO2 nanoparticles and bulk material in the in vitro model of human peripheral blood mononuclear cells (PBMC) and cytokine-induced neopterin formation and tryptophan breakdown was monitored. Both biochemical processes are closely related to the course of diseases like infections, atherogenesis and neurodegeneration. OCTi60 (25 nm diameter) TiO2 nanoparticles and bulk material increased neopterin production in unstimulated PBMC and stimulated cells significantly, the effects were stronger for OCTi60 compared to bulk material, while P25 TiO2 (25 nm diameter) nanoparticles had only little influence. No effect of TiO2 nanoparticles on tryptophan breakdown was detected in unstimulated cells, whereas in stimulated cells, IDO activity and IFN-γ production were suppressed but only at the highest concentrations tested. Because neopterin was stimulated and tryptophan breakdown was suppressed in parallel, data suggests that the total effect of particles would be strongly pro-inflammatory. PMID:24361406
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Inference of cancer-specific gene regulatory networks using soft computing rules.
Wang, Xiaosheng; Gotoh, Osamu
2010-03-24
Perturbations of gene regulatory networks are essentially responsible for oncogenesis. Therefore, inferring the gene regulatory networks is a key step to overcoming cancer. In this work, we propose a method for inferring directed gene regulatory networks based on soft computing rules, which can identify important cause-effect regulatory relations of gene expression. First, we identify important genes associated with a specific cancer (colon cancer) using a supervised learning approach. Next, we reconstruct the gene regulatory networks by inferring the regulatory relations among the identified genes, and their regulated relations by other genes within the genome. We obtain two meaningful findings. One is that upregulated genes are regulated by more genes than downregulated ones, while downregulated genes regulate more genes than upregulated ones. The other one is that tumor suppressors suppress tumor activators and activate other tumor suppressors strongly, while tumor activators activate other tumor activators and suppress tumor suppressors weakly, indicating the robustness of biological systems. These findings provide valuable insights into the pathogenesis of cancer.
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Regulation of Apoptosis during Flavivirus Infection
Okamoto, Toru; Suzuki, Tatsuya; Kusakabe, Shinji; Tokunaga, Makoto; Hirano, Junki; Miyata, Yuka; Matsuura, Yoshiharu
2017-01-01
Apoptosis is a type of programmed cell death that regulates cellular homeostasis by removing damaged or unnecessary cells. Its importance in host defenses is highlighted by the observation that many viruses evade, obstruct, or subvert apoptosis, thereby blunting the host immune response. Infection with Flaviviruses such as Japanese encephalitis virus (JEV), Dengue virus (DENV) and West Nile virus (WNV) has been shown to activate several signaling pathways such as endoplasmic reticulum (ER)-stress and AKT/PI3K pathway, resulting in activation or suppression of apoptosis in virus-infected cells. On the other hands, expression of some viral proteins induces or protects apoptosis. There is a discrepancy between induction and suppression of apoptosis during flavivirus infection because the experimental situation may be different, and strong links between apoptosis and other types of cell death such as necrosis may make it more difficult. In this paper, we review the effects of apoptosis on viral propagation and pathogenesis during infection with flaviviruses. PMID:28846635
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Farazuddin, Mohammad; Dua, Bhavyata; Zia, Qamar; Khan, Aijaz Ahmad; Joshi, Beenu; Owais, Mohammad
2014-01-01
Curcumin (diferuloylmethane) is found in large quantities in the roots of Curcuma longa. It possesses strong antioxidant and anti-inflammatory properties, and inhibits chemically-induced carcinogenesis in the skin, forestomach, colon, and liver. Unfortunately, the poor bioavailability and hydrophobicity of curcumin pose a major hurdle to its use as a potent anticancer agent. To circumvent some of these problems, we developed a novel, dual-core microcell formulation of curcumin. The encapsulation of curcumin in microcells increases its solubility and bioavailability, and facilitates slow release kinetics over extended periods. Besides being safe, these formulations do not bear any toxicity constraints, as revealed by in vitro and in vivo studies. Histopathological analysis revealed that curcumin-bearing microcells helped in regression of hepatocellular carcinoma and the maintenance of cellular architecture in liver tissue. Free curcumin had a very mild effect on cancer suppression. Empty (sham) microcells and microparticles failed to inhibit cancer cells. The novel curcumin formulation was found to suppress hepatocellular carcinoma efficiently in Swiss albino mice. PMID:24627632
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Probing α -RuCl3 Beyond Magnetic Order: Effects of Temperature and Magnetic Field
NASA Astrophysics Data System (ADS)
Winter, Stephen M.; Riedl, Kira; Kaib, David; Coldea, Radu; Valentí, Roser
2018-02-01
Recent studies have brought α -RuCl3 to the forefront of experimental searches for materials realizing Kitaev spin-liquid physics. This material exhibits strongly anisotropic exchange interactions afforded by the spin-orbit coupling of the 4 d Ru centers. We investigate the dynamical response at finite temperature and magnetic field for a realistic model of the magnetic interactions in α -RuCl3 . These regimes are thought to host unconventional paramagnetic states that emerge from the suppression of magnetic order. Using exact diagonalization calculations of the quantum model complemented by semiclassical analysis, we find a very rich evolution of the spin dynamics as the applied field suppresses the zigzag order and stabilizes a quantum paramagnetic state that is adiabatically connected to the fully polarized state at high fields. At finite temperature, we observe large redistributions of spectral weight that can be attributed to the anisotropic frustration of the model. These results are compared to recent experiments and provide a road map for further studies of these regimes.
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2013-01-01
There is an increasing level of interest in the use of black TiO2 prepared by thermal hydrogen treatments (H:TiO2) due to the potential to enhance both the photocatalytic and the light-harvesting properties of TiO2. Here, we examine oxygen-deficient H:TiO2 nanotube arrays that have previously achieved very high solar-to-hydrogen (STH) efficiencies due to incident photon-to-current efficiency (IPCE) values of >90% for photoelectrochemical water splitting at only 0.4 V vs RHE under UV illumination. Our transient absorption (TA) mechanistic study provides strong evidence that the improved electrical properties of oxygen-deficient TiO2 enables remarkably efficient spatial separation of electron–hole pairs on the submicrosecond time scale at moderate applied bias, and this coupled to effective suppression of microsecond to seconds charge carrier recombination is the primary factor behind the dramatically improved photoelectrochemical activity. PMID:24376902
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Enhancement of Ag nanoparticles concentration by prior ion implantation
NASA Astrophysics Data System (ADS)
Mu, Xiaoyu; Wang, Jun; Liu, Changlong
2017-09-01
Thermally grown SiO2 layer on Si substrates were singly or sequentially implanted with Zn or Cu and Ag ions at the same fluence of 2 × 1016/cm2. The profiles of implanted species, structure, and spatial distribution of the formed nanoparticles (NPs) have been characterized by the cross-sectional transmission electron microscope (XTEM) and Rutherford backscattering spectrometry (RBS). It is found that pre-implantation of Zn or Cu ions could suppress the self sputtering of Ag atoms during post Ag ion implantation, which gives rise to fabrication of Ag NPs with a high density. Moreover, it has also been demonstrated that the suppressing effect strongly depends on the applied energy and mobility of pre-implanted ions. The possible mechanism for the enhanced Ag NPs concentration has been discussed in combination with SRIM simulations. Both vacancy-like defects acting as the increased nucleation sites for Ag NPs and a high diffusivity of prior implanted ions in SiO2 play key roles in enhancing the deposition of Ag implants.
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Li, Lili; Zhao, Hui; Liu, Ping; Li, Chunfeng; Quanquin, Natalie; Ji, Xue; Sun, Nina; Du, Peishuang; Qin, Cheng-Feng; Lu, Ning; Cheng, Genhong
2018-06-19
Zika virus infection stimulates a type I interferon (IFN) response in host cells, which suppresses viral replication. Type I IFNs exert antiviral effects by inducing the expression of hundreds of IFN-stimulated genes (ISGs). To screen for antiviral ISGs that restricted Zika virus replication, we individually knocked out 21 ISGs in A549 lung cancer cells and identified PARP12 as a strong inhibitor of Zika virus replication. Our findings suggest that PARP12 mediated the ADP-ribosylation of NS1 and NS3, nonstructural viral proteins that are involved in viral replication and modulating host defense responses. This modification of NS1 and NS3 triggered their proteasome-mediated degradation. These data increase our understanding of the antiviral activity of PARP12 and suggest a molecular basis for the potential development of therapeutics against Zika virus. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.
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Change over time in obedience: The jury's still out, but it might be decreasing.
Twenge, Jean M
2009-01-01
Jerry M. Burger's partial replication of Stanley Milgram's (1974) obedience study shows both the influence of culture and generations on behavior and the power of the situation. In Burger's data, disobedience has nearly doubled among male participants since the 1960s, a shift just as large as the increase in Americans' body mass index that has been labeled the "obesity epidemic." Differences in the ethnic composition of the two studies' samples, particularly the large numbers of Asian Americans in Burger's sample, may have suppressed what might have been an even larger increase in disobedience. Halting the experiment at 150 volts may also have suppressed change. Nevertheless, situations have a strong influence on behavior; thus generational shifts would not be expected to completely eliminate the effect. Burger's results are consistent with documented changes in personality traits over the generations, including increases in nonconformist traits such as assertiveness, self-esteem, and narcissism. PsycINFO Database Record 2009 APA.
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Han, Yan-Hong; Xiang, Hai-Ying; Wang, Qian; Li, Yuan-Yuan; Wu, Wen-Qi; Han, Cheng-Gui; Li, Da-Wei; Yu, Jia-Lin
2010-10-10
Melon aphid-borne yellows virus (MABYV) is a newly identified polerovirus occurring in China. Here, we demonstrate that the MABYV encoded P0 (P0(MA)) protein is a strong suppressor of post-transcriptional gene silencing (PTGS) with activity comparable to tobacco etch virus (TEV) HC-Pro. In addition we have shown that the LP F-box motif present at the N-terminus of P0(MA) is required for suppressor activity. Detailed mutational analyses on P0(MA) revealed that changing the conserved Trp 212 with non-ring structured amino acids altered silencing suppressor functions. Ala substitutions at positions 12 and 211 for Phe had no effect on P0 suppression-activity, whereas Arg and Glu substitutions had greatly decreased suppressor activity. Furthermore, substitutions targeting Phe at position 30 also resulted in reduced P0 suppression-activity. Altogether, these results suggest that ring structured Trp/Phe residues in P0 have important roles in suppressor activity. Copyright © 2010 Elsevier Inc. All rights reserved.