ON

Distribution by Scientific Domains

Kinds of ON

  • acute on
  • went on

  • Terms modified by ON

  • on average
  • on cell
  • on cone bipolar cell
  • on terror
  • on the edge
  • on the web

  • Selected Abstracts


    WE WERE DANCING IN THE CLUB, NOT ON THE BERLIN WALL: Black Bodies, Street Bureaucrats, and Exclusionary Incorporation into the New Europe

    CULTURAL ANTHROPOLOGY, Issue 4 2008
    DAMANI JAMES PARTRIDGE
    ABSTRACT In this essay, I explore the micropolitics of citizenship and sovereignty via the emerging street bureaucratic status of "white" German women in relationships with "black" men in Germany and Berlin. In the midst of the fallen Berlin Wall and increasing Europe-wide restrictions on immigration and asylum, it examines further the extent to which a consistent "black" male hypersexual performance is necessary for legal recognition via "white" German women who, taking on an informal bureaucratic status, ultimately decide which "black" subjects to marry. A history of desiring "black" bodies, the essay argues, coincides with several important moments of sexual liberation (incl. post,World War II African American military occupation, 1970s West German feminism, and the fall of the Berlin Wall), which make these relationships both possible and public; however, the hypersexualized conditions under which "black" subjects get incorporated into contemporary German life are also ultimately exclusionary. [source]


    Distribution of neurotrophin-3 during the ontogeny and regeneration of the lizard (Gallotia galloti) visual system

    DEVELOPMENTAL NEUROBIOLOGY, Issue 1 2008
    E. Santos
    Abstract We have previously described the spontaneous regeneration of retinal ganglion cell axons after optic nerve (ON) transection in the adult Gallotia galloti. As neurotrophin-3 (NT-3) is involved in neuronal differentiation, survival and synaptic plasticity, we performed a comparative immunohistochemical study of NT-3 during the ontogeny and regeneration (after 0.5, 1, 3, 6, 9, and 12 months postlesion) of the lizard visual system to reveal its distribution and changes during these events. For characterization of NT-3+ cells, we performed double labelings using the neuronal markers HuC-D, Pax6 and parvalbumin (Parv), the microglial marker tomato lectin or Lycopersicon esculentum agglutinin (LEA), and the astroglial markers vimentin (Vim) and glial fibrillary acidic protein (GFAP). Subpopulations of retinal and tectal neurons were NT-3+ from early embryonic stages to adulthood. Nerve fibers within the retinal nerve fiber layer, both plexiform layers and the retinorecipient layers in the optic tectum (OT) were also stained. In addition, NT-3+/GFAP+ and NT-3+/Vim+ astrocytes were detected in the ON, chiasm and optic tract in postnatal and adult lizards. At 1 month postlesion, abundant NT-3+/GFAP+ astrocytes and NT-3,/LEA+ microglia/macrophages were stained in the lesioned ON, whereas NT-3 became downregulated in the experimental retina and OT. Interestingly, at 9 and 12 months postlesion, the staining in the experimental retina resembled that in control animals, whereas bundles of putative regrown fibers showed a disorganized staining pattern in the OT. Altogether, we demonstrate that NT-3 is widely distributed in the lizard visual system and its changes after ON transection might be permissive for the successful axonal regrowth. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2008 [source]


    [Commentary] HAVING FUN AND DEFYING ADULTS: SPECULATIONS ON WHY MOST YOUNG PEOPLE IGNORE NEGATIVE INFORMATION ON THE DANGERS OF DRINKING ALCOHOL

    ADDICTION, Issue 4 2009
    RODNEY SKAGER
    No abstract is available for this article. [source]


    Dissolved fraction of standard laboratory cladoceran food alters toxicity of waterborne silver to Ceriodaphnia dubia,

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2008
    Jason M. Kolts
    Abstract The biotic ligand model (BLM) for the acute toxicity of cationic metals to aquatic organisms incorporates the toxicity-modifying effects of dissolved organic matter (DOM), but the default parameterization (i.e., assuming 10% of DOM is humic acid) does not differentiate DOM from different sources. We exposed a cladoceran (Ceriodaphnia dubia) to Ag in the presence of DOM from filtered YCT (standard yeast,Cerophyll®,trout chow food recommended by the U.S. Environmental Protection Agency [EPA] for cladocerans), from the Suwannee River (GA, USA; relatively little anthropogenic input), and from the Desjardins Canal in Hamilton (ON, Canada; receives treated municipal wastewater effluent). In all three treatments, the dissolved organic carbon (DOC) concentration was 2 mg/L (the concentration following addition of YCT slurry at the U.S. EPA,recommended volume ratio). The average 48-h median effects concentration (EC50) ratios for dissolved Ag in the presence and absence of DOM [i.e., (EC50 with DOM)/(EC50 without DOM)] were as follows: Suwannee River, 1.6; Desjardins Canal, 2.2; and YCT filtrate, 26.8. Therefore, YCT filtrate provided much more protection against Ag toxicity than that provided by DOM from the surface waters. The major spectral characteristic that differentiated YCT filtrate from the other two types of DOM was a strong tryptophan peak in the excitation,emission matrix for YCT. These results have important implications for interpreting Ag toxicity tests in which organisms are fed YCT, and they suggest BLM-calculated toxicity predictions might be improved by incorporating specific chemical constituents or surrogate indices of DOM. Another component of the protective effect against Ag toxicity, however, might be that the dissolved fraction of YCT served as an energy and/or nutrient source for C. dubia. [source]


    Effects of estimates from different geochemical models on metal fate predicted by coupled speciation-fate models,

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2008
    Satyendra P. Bhavsar
    Abstract Coupled metal speciation-fate models are an improvement over stand-alone fate-transport models for accurately assessing metal fate and transport. These coupled models estimate fate-controlling partition coefficients using geochemical speciation/complexation models. Commercially available geochemical models are practical options for a two-step, loose coupling with fate-transport models. These models differ in their partitioning estimates because of differences in assumptions, databases, and so on. The present study examines the effects of differences in estimates from geochemical models on estimates of cationic metal fate using two geochemical models: the Windermere humic aqueous model (WHAM) and the minicomputer equilibrium+ model (MINEQL+). The results from each geochemical model were used as input to the fate module of TRANSPEC (a general, coupled metal transport and speciation model). The two versions of the TRANSPEC model were then used to assess the fate of five cationic metals (Cd, Cu, Ni, Pb, and Zn) in Ross Lake (Flin Flon, MB, Canada; alkaline, eutrophic, mine impacted), Kelly Lake (Sudbury, ON, Canada; circumneutral, mesotrophic, mine influenced), and Lake Tantaré (Quebec City, QC, Canada; acidic, oligotrophic, pristine). For relatively soluble metals (Cd, Ni, and Zn), the WHAM and MINEQL+ estimates of speciation/complexation were similar for Ross and Kelly lakes but differed for Lake Tantaré. These differences, however, did not result in significant differences in overall fate estimates. Marked differences were observed between the WHAM and MINEQL+ estimates of partition coefficient, Kd, for more particle-reactive Cu and Pb that translated into the greatest impact on fate in mesotrophic Kelly Lake, in which particle movement is important for fate. [source]


    Seasonality effects on pharmaceuticals and s -triazine herbicides in wastewater effluent and surface water from the Canadian side of the upper Detroit River

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2006
    Wen Yi Hua
    Abstract The influence of seasonal changes in water conditions and parameters on several major pharmacologically active compounds (PhACs) and s -triazine herbicides was assessed in the wastewater and sewage treatment plant (WSTP) effluent as well as the downstream surface water from sites on the Canadian side of the upper Detroit River, between the Little River WSTP and near the water intake of a major drinking water treatment facility for the City of Windsor (ON, Canada). The assessed PhACs were of neutral (carbamazepine, cotinine, caffeine, cyclophosphamide, fluoxetine, norfluoxetine, pentoxifylline, and trimethoprim) and acidic (ibuprofen, bezafibrate, clofibric acid, diclofenac, fenoprofen, gemfibrozil, indomethacin, naproxen, and ketoprofen) varieties. The major assessed s -triazine herbicides were atrazine, simazine, propazine, prometon, ametryn, prometryn, and terbutryn. At sampling times from September 2002 to June 2003, 15 PhACs were detected in the WSTP effluent at concentrations ranging from 1.7 to 1,244 ng/L. The PhAC concentrations decreased by as much 92 to 100% at the Little River/Detroit River confluence because of the river dilution effect, with further continual decreases at sites downstream from the WSTP. The only quantifiable s -triazine in WSTP effluent, atrazine, ranged from 6.7 to 200 ng/L and was higher in Detroit River surface waters than in WSTP effluent. Only carbamazepine, cotinine, and atrazine were detectable at the low-nanogram and subnanogram levels in surface waters near a drinking water intake site. Unlike the PhACs, atrazine in the Detroit River is not attributable to point sources, and it is heavily influenced by seasonal agricultural usage and runoff. Detroit River surface water concentrations of carbamazepine, cotinine, and atrazine may present a health concern to aquatic wildlife and to humans via the consumption of drinking water. [source]


    Use of paired fathead minnow (Pimephales promelas) reproductive test.

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2006
    Part 2: Source identification of biological effects at a bleached kraft pulp mill
    Abstract Reproductive effects of pulp mill effluents on fish continue to be reported in Canadian waters. Spawning delays, reduced gonad size, and altered levels of sex steroid hormones have been found in both sexes of various fish species exposed to effluents. We initiated a project to identify the source/cause of such effects. In part 1 of this two-part series, we exposed mature adult fathead minnow (FHM; Pimephales promelas) for 21 d to final treated effluent (1% and 100% v/v) from a bleached kraft pulp mill in Terrace Bay (ON, Canada). Results suggested pulp mill effluent from this mill affected reproductive indicators in FHM and effects were dependent on effluent concentration, duration of exposure, and method of data analysis. The main objective of this paper was to use the FHM assay to identify waste stream sources within the mill that affect reproductive indicators. Various process streams were selected, characterized with respect to effluent chemistry and acute toxicity, and a subset was tested on-site with the 21-d FHM bioassay. Results showed that both the combined mill effluent (before secondary treatment) and the combined alkaline stream (CALK) caused both decreased spawning events (,55% for both streams) and decreased egg production (28 and 74%, respectively), and the CALK stream resulted in significant male ovipositor development. By comparing response patterns we were able to identify the CALK stream as a source of compounds at this mill affecting reproductive indicators in FHM and highlight this stream for further toxicity identification evaluation. [source]


    Using artificial streams to assess the effects of metal-mining effluent on the life cycle of the freshwater midge (Chironomus tentans) in situ

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2004
    Kimberly A. Hruska
    Abstract In 2002, we developed an in situ life-cycle bioassay with Chironomus tentans in artificial streams to evaluate the effects of a complex metal mine effluent under ambient environmental conditions. The bioassay was tested in the field using effluent from the Copper Cliff Waste Water Treatment Plant at INCO (Sudbury, ON, Canada). Chironomus tentans were exposed throughout the life cycle to 45% Copper Cliff effluent, which is the average effluent concentration measured in Junction Creek (ON, Canada), the natural receiving environment. Chironomus tentans in the effluent treatment exhibited reduced survival (p = 0.001), reduced total emergence (p = 0.001), increased time-to-emergence (p = 0.001), and reduced hatching success (p = 0.001) relative to animals in the reference water treatment. Chironomus tentans in the effluent treatment were not significantly different from the reference in terms of growth, sex ratio, number of egg cases/female, and number of eggs/egg case. This research showed how a life-cycle bioassay could be used in situ to assess metal mine effluent effects on a benthic invertebrate. [source]


    The relative sensitivity of four benthic invertebrates to metals in spiked-sediment exposures and application to contaminated field sediment

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2003
    Danielle Milani
    Abstract The relative sensitivity of four benthic invertebrates (Hyalella azteca, Chironomus riparius, Hexagenia spp., and Tubifex tubifex) was determined for Cd, Cu, and Ni in water-only and in spiked-sediment exposures. Survival (median lethal concentrations [LC50s] and the concentrations estimated to be lethal to 25% of test organisms [LC25s]), and endpoints for growth and reproduction (mean inhibitory concentrations [IC25s]) were compared. The sensitivities differed depending on the species and metal, although some trends emerged. In water-only exposures, H. azteca is the most sensitive species to cadmium and nickel, with mean LC50s of 0.013 and 3.6 mg/L, respectively; C. riparius is the most sensitive species to copper, with a mean LC50 of 0.043 mg/L. In the spiked-sediment exposures, the order in decreasing sensitivity to copper is Hyalella = Hexagenia < Chironomus < Tubifex for survival and growth/reproduction. For cadmium, the order in decreasing sensitivity is Hyalella = Chironomus < Hexagenia < Tubifex, and for nickel is Hyalella , Hexagenia < Chironomus < Tubifex. Chironomus riparius and Hexagenia spp. survival can be used to distinguish between toxicity caused by different metals. Species test responses in field-collected sediment (Collingwood Harbour, ON, Canada) were examined in an attempt to determine the causative agent of toxicity throughout, using the established species sensitivities. Sediment toxicity was categorized first by comparing species responses to those established for a reference database. Test responses in the field-collected sediment do not support causality by Cu, a suspected toxicant based on comparison of sediment chemistry with sediment quality guidelines. [source]


    Immunosuppression in the northern leopard frog (Rana pipiens) induced by pesticide exposure

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2003
    Mary-Kate Gilbertson
    Abstract An injection study and a field study were used to investigate the hypothesis that environmental xenobiotics have the potential to alter the immune function of northern leopard frogs (Rana pipiens). Three assays, IgM-specific antibody response to keyhole limpet hemocyanin linked to dinitrophenyl (KLH-DNP), zymozan induced chemiluminescence (CL) of whole blood and the delayed-type hypersensitivity (DTH), were used to assay humoral, innate and cell-mediated immune endpoints. Sublethal doses of DDT (923 ng/g wet wt), malathion (990 ng/g wet wt), and dieldrin (50 ng/g wet wt) were used in the injection study. In all pesticide-injected groups, antibody response was dramatically suppressed, DTH reactions were enhanced, and respiratory burst was lower. When the order of administration of pesticides and antigens was reversed, no differences in immune function between the control and dosed groups were apparent, indicating that frogs exposed to pathogens prior to pesticide exposure can still respond. A field study found significant differences in immune function between frog populations in pesticide-exposed and pesticide-free locations. The antibody response and CL were suppressed and the DTH enhanced in frogs from Essex County (ON, Canada). Overall, the results suggest that exposure to these pesticides can cause both stimulatory and suppressive immune changes in adult frogs and is doing so in wild populations. [source]


    A cautionary note on the use of species presence and absence data in deriving sediment criteria

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2002
    Katherine Von Stackelberg
    Abstract In recent years, a variety of approaches to deriving sediment quality guidelines have been developed. One approach relies on establishing an empirical relationship between the concentration of a contaminant in sediment and the condition of some biological indicator, for example, combining measured sediment concentrations of contaminants combined with data on colocated benthic species to measure in situ community effects of contamination. Biological threshold concentrations derived in this manner are being considered or have already been adopted by some regulatory agencies as a means for deriving sediment guidelines (e.g., Canada's Provincial Sediment Quality Guidelines). In order to test the validity of this method, we constructed several Monte Carlo simulations to illustrate that the methodology used to develop these guidelines is flawed by the effects of sampling and statistical artifacts that emerge from undersampling a lognormal density function. As a case study, this paper will present the screening level concentration method used by the Ontario Ministry of the Environment (Toronto, ON, Canada) and provide the results of several probabilistic exercises highlighting these issues. We present a word of caution on the applicability of methods that rely exclusively on statistical and mathematical relationships between invertebrate data and sediment concentrations to derive sediment quality guidelines. [source]


    COMMENT ON THE PAPER (Are Polish and Swedish dental graduates adequately prepared for dental practice in the UK?

    EUROPEAN JOURNAL OF DENTAL EDUCATION, Issue 2 2002
    A discussion of the transferability of general dental practitioners in Europe by
    No abstract is available for this article. [source]


    Levodopa-induced ocular dyskinesia in Parkinson's disease

    EUROPEAN JOURNAL OF NEUROLOGY, Issue 10 2007
    H. Grötzsch
    Levodopa (LD)-induced dyskinesia (LID), one of the most common motor complications in advanced Parkinson's disease (PD), involve mostly the limbs, trunk and head, but unusual locations have been reported including respiratory muscles, the face and the eyes. The aim of this study was to further investigate the frequency and characteristics of LD-related abnormal involuntary eye movements (AIEMs) in PD. Thirty-two patients with advanced PD and various motor complications were evaluated and videotaped in an ON and OFF state. We found AIEMs in five patients (16%) which were present exclusively during the ON state and which completely disappeared when OFF. They consisted of repeated, stereotyped upward and/or sideways gaze deviation movements, sometimes phasic, brief and jerky, sometimes tonic and sustained for several seconds. The main direction of gaze deviation was toward the side more affected by parkinsonism. AIEMs typically paralleled limb and trunk LID and were modulated by the same facilitation and inhibitory maneuvers. We concluded that AIEMs are not uncommon in advanced PD and represent a particular topography of LID, hence the term ,ocular dyskinesia' to designate these AIEMs that seem to have a specific pattern in PD as compared with other forms of parkinsonism. [source]


    Functional MRI of the visual cortex and visual testing in patients with previous optic neuritis

    EUROPEAN JOURNAL OF NEUROLOGY, Issue 3 2002
    A. R. Langkilde
    The volume of cortical activation as detected by functional magnetic resonance imaging (fMRI) in the visual cortex has previously been shown to be reduced following optic neuritis (ON). In order to understand the cause of this change, we studied the cortical activation, both the size of the activated area and the signal change following ON, and compared the results with results of neuroophthalmological testing. We studied nine patients with previous acute ON and 10 healthy persons served as controls using fMRI with visual stimulation. In addition to a reduced activated volume, patients showed a reduced blood oxygenation level dependent (BOLD) signal increase and a greater asymmetry in the visual cortex, compared with controls. The volume of visual cortical activation was significantly correlated to the result of the contrast sensitivity test. The BOLD signal increase correlated significantly to both the results of the contrast sensitivity test and to the Snellen visual acuity. Our results indicate that fMRI is a useful method for the study of ON, even in cases where the visual acuity is severely impaired. The reduction in activated volume could be explained as a reduced neuronal input; however, the greater asymmetry might point to a cortical reorganization as a consequence of neuronal damage. Future fMRI studies in ON will add to the understanding of the neural adaptive behaviour following ON. [source]


    Tactile responses of hindpaw, forepaw and whisker neurons in the thalamic ventrobasal complex of anesthetized rats

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2008
    J. Aguilar
    Abstract The majority of studies investigating responses of thalamocortical neurons to tactile stimuli have focused on the whisker representation of the rat thalamus: the ventral,posterior,medial nucleus (VPM). To test whether the basic properties of thalamocortical responses to tactile stimuli could be extended to the entire ventrobasal complex, we recorded single neurons from the whisker, forepaw and hindpaw thalamic representations. We performed a systematic analysis of responses to stereotyped tactile stimuli , 500 ms pulses (i.e. ON,OFF stimuli) or 1 ms pulses (i.e. impulsive stimuli) , under two different anesthetics (pentobarbital or urethane). We obtained the following main results: (i) the tuning of cells to ON vs. OFF stimuli displayed a gradient across neurons, so that two-thirds of cells responded more to ON stimuli and one-third responded more to OFF stimuli; (ii) on average, response magnitudes did not differ between ON and OFF stimuli, whereas latencies of response to OFF stimuli were a few milliseconds longer; (iii) latencies of response to ON and OFF stimuli were highly correlated; (iv) responses to impulsive stimuli and ON stimuli showed a strong correlation, whereas the relationship between the responses to impulsive stimuli and OFF stimuli was subtler; (v) unlike ON responses, OFF responses did not decrease when stimuli were moved from the receptive field center to a close location in the excitatory surround. We obtained the same results for hindpaw, forepaw and whisker neurons. Our results support the view of a neurophysiologically homogeneous ventrobasal complex, in which OFF responses participate in the structure of the spatiotemporal receptive field of thalamocortical neurons for tactile stimuli. [source]


    The immunocytochemical localization of connexin 36 at rod and cone gap junctions in the guinea pig retina

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2003
    Eun-Jin Lee
    Abstract Connexin 36 (Cx36) is a channel-forming protein found in the membranes of apposed cells, forming the hexameric hemichannels of intercellular gap junction channels. It localizes to certain neurons in various regions of the brain including the retina. We characterized the expression pattern of neuronal Cx36 in the guinea pig retina by immunocytochemistry using specific antisera against Cx36 and green/red cone opsin or recoverin. Strong Cx36 immunoreactivity was visible in the ON sublamina of the inner plexiform layer and in the outer plexiform layer, as punctate labelling patterns. Double-labelling experiments with antibody directed against Cx36 and green/red cone opsin or recoverin showed that strong clustered Cx36 immunoreactivity localized to the axon terminals of cone or close to rod photoreceptors. By electron microscopy, Cx36 immunoreactivity was visible in the gap junctions as well as in the cytoplasmic matrices of both sides of cone photoreceptors. In the gap junctions between cone and rod photoreceptors, Cx36 immunoreactivity was only visible in the cytoplasmic matrices of cone photoreceptors. These results clearly indicate that Cx36 forms homologous gap junctions between neighbouring cone photoreceptors, and forms heterologous gap junctions between cone and rod photoreceptors in guinea pig retina. This focal location of Cx36 at the terminals of the photoreceptor suggests that rod photoreceptors can transmit rod signals to the pedicle of a neighbouring cone photoreceptor via Cx36, and that the cone in turn signals to corresponding ganglion cells via ON and OFF cone bipolar cells. [source]


    Odour-evoked [Ca2+] transients in mitral cell dendrites of frog olfactory glomeruli

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2001
    Kerry Delaney
    Abstract We measured Ca2+ concentration, [Ca2+], transients in mitral cell distal apical dendritic tufts produced by physiological odour stimulation of the olfactory epithelium and electrical stimulation of the olfactory nerve (ON) using two-photon scanning and conventional wide-field microscopy of Ca2+ -Green-1 dextran in an in vitro frog nose,brain preparation. Weak or strong ON shock-evoked fluorescence transients always had short latency with an onset 0,10 ms after the onset of the bulb local field potential, rapidly increasing to a peak of up to 25% fractional fluorescence change (,F/F) in 10,30 ms, were blocked by 10 µm CNQX, decaying with a time constant of about 1 s. With stronger ON shocks that activated many receptor axons, an additional, delayed, sustained AP5-sensitive component (peak at ,,0.5 s, up to 40% ,F/F maximum) could usually be produced. Odour-evoked [Ca2+] transients sometimes displayed a rapid onset phase that peaked within 50 ms but always had a sustained phase that peaked 0.5,1.5 s after onset, regardless of the strength of the odour or the amplitude of the response. These were considerably larger (up to 150% ,F/F) than those evoked by ON shock. Odour-evoked [Ca2+] transients were also distinguished from ON shock-evoked transients by tufts in different glomeruli responding with different delays (time to onset differed by up to 1.5 s between different tufts for the same odour). Odour-evoked [Ca2+] transients were increased by AMPA-kainate receptor blockade, but substantially blocked by AP5. Electrical stimulation of the lateral olfactory tract (5,6 stimuli at 10 Hz) that evoked granule cell feedback inhibition, blocked 60,100% of the odour-evoked [Ca2+] transient in tufts when delivered within about 0.5 s of the odour. LOT-mediated inhibition was blocked by 10 µm bicuculline. [source]


    Preparation and Memory Performance of a Nanoaggregated Dispersed Red 1-Functionalized Poly (N -vinylcarbazole) Film via Solution-Phase Self-Assembly

    ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010
    Xiao-Dong Zhuang
    Abstract A nanoaggregated dispersed red 1-grafted poly(N -vinylcarbazole) (abbreviated PVDR) is self-assembled via ,,, stacking interactions of the carbazole groups in the polymer system after adding a solution of PVDR in N,N -dimethylformamide to dichloromethane. Upon self-assembly, the nanoaggregated PVDR film displays helical columnar stacks with large grain sizes, whereas a non-aggregated PVDR film exhibits an amorphous morphology with smaller grain size. A write-once read-many-times (WORM) memory device is shown whereby a pre-assembled solution of PVDR is spin-coated as the active layer and is sandwiched between an aluminum electrode and an indium-tin-oxide (ITO) electrode. This device shows very good memory performance, with an ON/OFF current ratio of more than 105 and a low misreading rate through the precise control of the ON and OFF states. The stability of the nanoaggregated PVDR device is much higher than that of the non-nanoaggregated PVDR device. This difference in device stability under constant voltage stress can be mainly attributed to the difference in the film crystallinity and surface morphology. No degradation in current density was observed for the ON- and OFF-states after more than one hundred million (108) continuous read cycles indicating that both states were insensitive to the read cycles. These results render the nanoaggregated PVDR polymer as promising components for high-performance polymer memory devices. [source]


    Air-Operable, High-Mobility Organic Transistors with Semifluorinated Side Chains and Unsubstituted Naphthalenetetracarboxylic Diimide Cores: High Mobility and Environmental and Bias Stress Stability from the Perfluorooctylpropyl Side Chain

    ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010
    Byung Jun Jung
    Abstract N,N,-bis(3-(perfluoroctyl)propyl)-1,4,5,8-naphthalenetetracarboxylic acid diimide (8,3-NTCDI) was newly synthesized, as were related fluorooctylalkyl-NTCDIs and alkyl-NTCDIs. The 8,3-NTCDI-based organic thin-film transistor (OTFT) on an octadecyltrimethoxysilane (OTS)-treated Si/SiO2 substrate shows apparent electron mobility approaching 0.7 cm2 V -1s -1 in air. The fluorooctylethyl-NTCDI (8,2-NTCDI) and fluorooctylbutyl-NTCDI (8,4-NTCDI) had significantly inferior properties even though their chemical structures are only slightly different, and nonfluorinated decyl and undecyl NTCDIs did not operate predictably in air. From atomic force microscopy, the 8,3-NTCDI active layer deposited with the substrate at 120 °C forms a polycrystalline film with grain sizes >4,m. Mobilities were stable in air for one week. After 100 days in air, the average mobility of three OTFTs decreased from 0.62 to 0.12 cm2 V -1s -1, but stabilized thereafter. The threshold voltage (VT) increased by 15 V in air, but only by 3 V under nitrogen, after one week. On/off ratios were stable in air throughout. We also investigated transistor stability to gate bias stress. The transistor on hexamethlydisilazane (HMDS) is more stable than that on OTS with mobility comparable to amorphous Si TFTs. VT shifts caused by ON (30 V) and OFF (,20 V) gate bias stress for the HMDS samples for 1 hour were 1.79 V and 1.27 V under N2, respectively, and relaxation times of 106 and 107 s were obtained using the stretched exponential model. These performances are promising for use in transparent display backplanes. [source]


    Influence of Potsdam sandstone on the trace element signatures of some 19th-century American and Canadian glass: Redwood, Redford, Mallorytown, and Como,Hudson

    GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 5 2008
    J. Victor Owen
    Potsdam sandstone from quarries and outcrops near 19th-century glassworks sites in Redwood, NY, and Saranac, NY, Mallorytown, ON, and Como and Hudson, QC, commonly contains _97% silica, so in terms of its purity can compete with other historical producers of silica sand (e.g., Cheshire quartzite, MA; southern New Jersey sand). Exploratory analysis of trace element data using multidimensional scaling (MDS) shows that geographically distinct sources of Potsdam sandstone can be distinguished from one another and from competing sources of silica sand, particularly in terms of high field strength elements (e.g., Nb, Y, Ti, Zr), the rare earth elements, and radioactive elements (U, Th), and this geochemical signature is carried through to the glass it was used to manufacture. Other trace elements (e.g., Ba, Sr, Rb) are concentrated in various batch ingredients (e.g., limestone, alkali fluxes). The Hf/Nb, La/Ce, Nb/Th, and La/Zr ratios for each type of glass and nearby Potsdam sandstone sources cluster together in distinct fields on MDS plots. These data confirm the use of Potsdam sandstone in these important historical glassworks, and show that except for material sampled from neighboring communities (Mallorytown and Redwood), trace elements can be used to identify specific sources of silica historically used by the glassmaking industry. © 2008 Wiley Periodicals, Inc. [source]


    Glaucomatous optic nerve injury involves early astrocyte reactivity and late oligodendrocyte loss

    GLIA, Issue 7 2010
    Janice L. Son
    Abstract Glaucoma, a neurodegenerative disease affecting retinal ganglion cells (RGC), is a leading cause of blindness. Since gliosis is common in neurodegenerative disorders, it is important to describe the changes occurring in various glial populations in glaucoma animal models in relation to axon loss, as only changes that occur early are likely to be useful therapeutic targets. Here, we describe changes occurring in glia within the myelinated portion of the optic nerve (ON) in both DBA/2J mice and in a rat ocular hypertension model. In both glaucoma animal models, we found only a modest loss of oligodendrocytes that occurred after axons had already degenerated. In DBA/2J mice there was proliferation of oligodendrocyte precursor cells (OPCs) and new oligodendrocyte generation. Activation of microglia was detected only in highly degenerated DBA/2J ONs. In contrast, a large increase in astrocyte reactivity occurred early in both animal models. These results are consistent with astrocytes playing a prominent role in regulating axon loss in glaucoma. © 2010 Wiley-Liss, Inc. [source]


    Crystal Structures and Magnetic Properties of Nitronyl Nitroxide Radicals

    HELVETICA CHIMICA ACTA, Issue 4 2003
    Alexander Zakrassov
    The crystal structures and magnetic properties of the nitronyl nitroxide radicals 4,5-dihydro-4,4,5,5-tetramethyl-3-oxido(1H -imidazol-1-yloxyl) (1), 4,5-dihydro-2,4,4,5,5-pentamethyl-3-oxido(1H -imidazol-1-yloxyl) (2), 2-(4-chlorophenyl)-4,5-dihydro-4,4,5,5-tetramethyl-3-oxido(1H -imidazol-1-yloxyl) (3), and 4,5-dihydro-2-(2-hydroxy-5-nitrophenyl)-4,4,5,5-tetramethyl-3-oxido(1H -imidazol-1-yloxyl) (4) are reported. Compound 1 has two polymorphic forms: the , phase is monoclinic (P21/n space group), with a single molecule in the asymmetric unit, and the , phase is monoclinic (P21/c space group), with four molecules in the asymmetric unit. In the two polymorphs, the molecules are arranged in dimers formed by hydrogen bonds of the type CH,,,ON. The crystal structure of 3 contains layers of antiparallel ribbons of molecules. Compound 4 crystallizes with solvent molecules, and an intramolecular hydrogen bond is formed between the 2-OH group of the phenyl ring and the nitroxide O-atom. Compound 4 also loses the two O-atoms of the nitroxide moiety upon heating to 90°. Magnetic measurements showed that both , and , polymorphs of 1 exhibit antiferromagnetic coupling. The best fit to the experimental data was obtained using BleanyBower's singlet-triplet model (H=,2JSaSb): J=,11.2,K for the , phase and J=,15.0,K for the , phase. Compounds 3 and 4 show no evidence for spin coupling. [source]


    Expedited forwarding end-to-end delay and jitter in DiffServ

    INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 8 2008
    Hamada Alshaer
    Abstract The scheduling disciplines and active buffer management represent the main components employed in the differentiated services (DiffServ) data plane, which provide qualitative per-hop behaviors corresponding to the QoS required by supported traffic classes. In the first part of this paper, we compute the per-hop delay bound that should be guaranteed by the different multiservice scheduling disciplines, so that the end-to-end (e2e) delay required by expedited forwarding (EF) traffic can be guaranteed. Consequently, we derive the e2e delay bound of EF traffic served by priority queuing,weighted fair queuing (PQ,WFQ) at every hop along its routing path. Although real-time flows are principally offered EF service class, some simulations on DiffServ-enabled network show that these flows suffer from delay jitter and they are negatively impacted by lower priority traffic. In the second part of this paper, we clarify the passive impact of delay jitter on EF traffic, where EF flows are represented by renewal periodic ON,OFF flows, and the background (BG) flows are characterized by the Poisson process. We analyze through different scenarios the jitter effects of these BG flows on EF flow patterns when they are served by a single class scheduling discipline, such as first-input first-output, and a multiclass or multiservice scheduling discipline, such as static priority service discipline. As a result, we have found out that the EF per-hop behaviors (PHBs) configuration according to RFCs 2598 and 3246 (IETF RFC 2598, June 1999; RFC 3246, IETF, March 2002) cannot stand alone in guaranteeing the delay jitter required by EF flows. Therefore, playout buffers must be added to DiffServ-enabled networks for handling delay jitter problem that suffers from EF flows. Copyright © 2008 John Wiley & Sons, Ltd. [source]


    Highly Efficient Direct Carboxylation of Propane into Butyric Acids Catalyzed by Vanadium Complexes

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2007
    Marina
    Abstract A direct and highly efficient carboxylation of propane by carbon monoxide into butyric acids (mainly isobutyric and, in a smaller amount, n -butyric), in the presence of potassium peroxodisulphate (K2S2O8) and in trifluoroacetic acid solution, has been achieved by using a vanadium catalytic system based on Ca[V{ON(CH(CH3)COO)2}2] (synthetic amavadine), its model compounds Ca[V{ON(CH2COO)2}2] or [VO{N(CH2CH2O)3}] , other simpler vanadium compounds, such as [VO(acac)2] or VOSO4, are less active. Overall yields (based on propane) of carboxylic acids up to 70,% and TON values up to 18.4×103 have been reached. The effects of various factors such as the propane and carbon monoxide pressures, temperature, time, catalyst amount and radical traps have been investigated, the reactions are shown to proceed via both C - and O -centred radicals, with K2S2O8 playing the role of an oxidant via a free radical mechanism. [source]


    Neurolytic phenol blockade of the obturator nerve for severe adductor spasticity

    ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2010
    T. AKKAYA
    Background: In this study, we present the 3-month follow-up results of a retrospective analysis of obturator nerve (ON) phenol neurolysis performed between 2000 and 2007 in patients with adductor spasticity. Methods: The study was performed by retrospective investigation of the clinical follow-up results of 80 ON phenol treatments in 62 patients. Neurolysis using 5,10 ml 6% phenol was applied with the guidance of fluoroscopy and a peripheral nerve stimulator. Pain, spasticity and hygiene were evaluated and the hip abduction range of motion (ROM) was measured at the end of the first week and in the first, second and third months following the intervention. Results: The visual analogue scale scores decreased significantly in the first week, first month and the second month, but reached their initial values in the third month. A drastic increase in the ROM values was shown in hip abduction in the first week, first month and second month. An increase in the Ashworth Scale values was observed in the second and third months, but they did not reach their initial values. The hygiene score decreased drastically in the first week and the first and second months, but worsened in the third month. The success rate in nerve localization during ON neurolysis was 100%. Conclusion: ON phenol blockade with fluoroscopy and peripheral nerve stimulator guidance in patients with adductor spasticity led to a decrease in spasticity and pain with an increase in the ROM of the hip and better hygiene with an efficacy lasting for about 3 months. [source]


    Patterns of elephant impact on woody plants in the Hluhluwe-Imfolozi park, Kwazulu-Natal, South Africa

    AFRICAN JOURNAL OF ECOLOGY, Issue 1 2010
    Roger Patrick Boundja
    Abstract This study identifies patterns of elephant Loxodonta africana africana impacts upon tree species and woody plant communities in Hluhluwe-Imfolozi Park, a South African savannahs/woodlands area. Elephants were reintroduced there from 1981, following more than 80 years of absence. Data were collected in 2003 on elephant impact on woodland in the Park. Different vegetation types were susceptible to different types and levels of damage by elephants, suggesting that elephants will not homogenize the vegetation. Elephants targeted larger stems for all types of damage, with a strong preference for some of the less abundant species such as Albizia versicolor (breaking and toppling) and Cordia caffra and Schotia brachypetala (debarking). Elephant impacts tended to be distributed evenly across the park landscape, irrespective of stem density or proximity to permanent water. Overall, elephants have little impact on slowing or reversing the spread of undesirable woody species, but are having a marked impact on certain less common tree species and larger tree size-classes in the Hluhluwe-Imfolozi Park. Résumé Cette étude identifie le schéma des impacts des éléphants Loxodonta africana africana sur des espèces d'arbres et sur des communautés végétales du Parc de Hluhluwe-Imfolozi, une zone de forêts et de savanes d'Afrique du Sud. Des éléphants y furent réintroduits à partir de 1981, après une absence de plus de 80 ans. En 2003, on a récolté des données sur l'impact des éléphants sur les forêts du parc. ON a vu que les différents types de végétation étaient sensibles à des types et à des niveaux différents de dommages causés par les éléphants, ce qui laisse entendre que les éléphants ne vont pas uniformiser la végétation. Les éléphants visaient les plus gros troncs pour tous les types de dommages, avec une préférence marquée pour certaines des espèces les moins abondantes, comme Albizia versicolor (cassés et renversés) et Cordia caffra and Schotia brachypetala (écorcés). Les impacts des éléphants avaient tendance àêtre répartis également dans tout le paysage du parc, quelles que soient la densité des troncs ou la proximité de points d'eau permanents. En général, les éléphants avaient peu d'impact sur le ralentissement ou l'inversion de la dispersion des espèces ligneuses indésirables, mais ils ont un impact réel sur certaines espèces d'arbres moins fréquentes et sur les arbres de classes de taille plus grandes dans le Parc de Hluhluwe-Imfolozi. [source]


    ROLE OF INITIAL MUSCLE pH ON THE SOLUBILITY OF FISH MUSCLE PROTEINS IN WATER

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2004
    STEPHEN D. KELLEHER
    The solubility of the myofibrillar and cytoskeletal proteins in water was determined for the muscle tissue often species offish. The flesh of six white-muscled fish had pH's at the time of processing above pH 6.6 and greater than 80% of their myofibrillar/cytoskeletal proteins were soluble in water. The flesh of three pelagic species and a shark had pH values when processed below 6.6 and the water solubility of their myofibrillar and cytoskeletal proteins was less than 40%. When the washed minced muscle of one of the white-fleshed species, cod, was exposed to low pH, the solubility of its myofibrillar and cytoskeletal proteins decreased substantially. The water solubility of the cod myofibrillar and cytoskeletal proteins could be reestablished by washing the acid-treated cod flesh with neutral salt solutions. It is suggested that pH values below 6.6 modify certain proteins which prevent the water-extractability of the rest of the myofibrillar and cytoskeletal proteins from being expressed. [source]


    Determination of Ortho- and Retronasal Detection Thresholds for 2-Isopropyl-3-Methoxypyrazine in Wine

    JOURNAL OF FOOD SCIENCE, Issue 7 2007
    G.J. Pickering
    ABSTRACT:, 2-isopropyl-3-methoxypyrazine (IPMP) is a grape-derived component of wine flavor in some wine varieties as well as the causal compound of the off-flavor known as ladybug taint (LBT), which occurs when Harmonia axyridis beetles are incorporated with the grapes during juice and wine processing. The main objective of this study was to obtain robust estimates of the orthonasal (ON) and retronasal (RN) detection thresholds (DTs) for IPMP in wines of differing styles. The ASTM E679 ascending forced choice method of limits was used to determine DTs for 47 individuals in 3 different wines,Chardonnay, Gewürztraminer, and a red wine blend of Baco Noir and Marechel Foch. The group best estimate thresholds (BETs) obtained for IPMP (ng/L) were Chardonnay, ON: 0.32; Gewürztraminer, ON: 1.56, RN: 1.15, and red wine blend, ON: 1.03, RN: 2.29. A large variation in individual DTs was observed. Familiarity with LBT was inversely correlated with DTs for Gewürztraminer, and no difference in thresholds was observed between winemakers and nonwinemakers. We conclude that the human DT for IPMP is extremely low and influenced significantly by wine style and evaluation mode. We recommend against the reporting of single-threshold values for wine flavor compounds, and encourage the determination of consumer rejection thresholds for IPMP in wine. [source]


    Identifying women with severe angiographic coronary disease

    JOURNAL OF INTERNAL MEDICINE, Issue 1 2010
    C. Kreatsoulas
    Abstract., Kreatsoulas C, Natarajan MK, Khatun R, Velianou JL, Anand SS (McMaster University; CARING Network, McMaster University; Population Health Research Institute, McMaster University and Hamilton Health Sciences; Interventional Cardiology, Hamilton Health Sciences; Eli Lilly Canada,May Cohen Chair in Women's Health, McMaster University; Michael G. DeGroote-Heart and Stroke Foundation of Ontario Chair in Population Health Research, McMaster University; Population Genomics Program, McMaster University; McMaster University, Hamilton, ON, Canada). Identifying women with severe angiographic coronary disease. J Intern Med 2010; 268:66,74. Objectives., To determine sex/gender differences in the distribution of risk factors according to age and identify factors associated with the presence of severe coronary artery disease (CAD). Design., We analysed 23 771 consecutive patients referred for coronary angiography from 2000 to 2006. Subjects., Patients did not have previously diagnosed CAD and were referred for first diagnostic angiography. Outcome measures., Patients were classified according to angiographic disease severity. Severe CAD was defined as left main stenosis ,50%, three-vessel disease with ,70% stenosis or two-vessel disease including proximal left anterior descending stenosis of ,70%. Univariate and multivariate logistic regression was used to assess the association between risk factors and angina symptoms with severe CAD. Results., Women were less likely to have severe CAD (22.3% vs. 36.5%) compared with men. Women were also significantly older (69.8 ± 10.6 vs. 66.3 ± 10.7 years), had higher rates of diabetes (35.0% vs. 26.6%), hypertension (74.8% vs. 63.3%) and Canadian Cardiovascular Society (CCS) class IV angina symptoms (56.7% vs. 47.8%). Men were more likely to be smokers (56.9% vs. 37.9%). Factors independently associated with severe CAD included age (OR = 1.05; 95% CI 1.05,1.05, P < 0.01), male sex (OR = 2.43; CI 2.26,2.62, P < 0.01), diabetes (OR = 2.00; CI 1.86,2.18, P < 0.01), hyperlipidaemia (OR = 1.50; CI 1.39,1.61, P < 0.01), smoking (OR = 1.10; CI 1.03,1.18, P = 0.06) and CCS class IV symptoms (OR = 1.43; CI 1.34,1.53, P < 0.01). CCS Class IV angina was a stronger predictor of severe CAD amongst women compared with men (women OR = 1.82; CI 1.61,2.04 vs. men OR = 1.28; CI 1.18,1.39, P < 0.01). Conclusions., Women referred for first diagnostic angiography have lower rates of severe CAD compared with men across all ages. Whilst conventional risk factors, age, sex, diabetes, smoking and hyperlipidaemia are primary determinants of CAD amongst women and men, CCS Class IV angina is more likely to be associated with severe CAD in women than men. [source]


    In vivo diffusion tensor imaging of the human optic nerve: Pilot study in normal controls

    MAGNETIC RESONANCE IN MEDICINE, Issue 2 2006
    C.A.M. Wheeler-Kingshott
    Abstract Diffusion tensor imaging (DTI) of the optic nerve (ON) was acquired in normal controls using zonally oblique multislice (ZOOM) DTI, which excites a small field of view (FOV) using a fast sequence with a shortened EPI echo train. This combines the benefit of low sensitivity to motion (due to the single-shot acquisition used), with the additional advantage of reduced sensitivity to magnetic field susceptibility artifacts. Reducing the bright signal from the fat and cerebrospinal fluid (CSF) surrounding the nerve are key requirements for the success of the presented method. Measurements of mean diffusivity (MD) and fractional anisotropy (FA) indices were made in a coronal section of the middle portion of the optic nerve (ON) in the right (rON) and left (lON) ONs. The average values across 10 healthy volunteers were FArON = 0.64 ± 0.09 and FAlON = 0.57 ± 0.10, and MDrON = (1173 ± 227) × 10,6 mm2 s,1 and MDlON = (1266 ± 170) × 10,6 mm2 s,1. Measurements of the principal eigenvalue of the DT and its orthogonal component were also in agreement with those expected from a highly directional structural organization. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source]