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Sample records for cell firing patterns

  1. Patterned firing of parietal cells in a haptic working memory task.

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    Bodner, M; Shafi, M; Zhou, Y-D; Fuster, J M

    2005-05-01

    Abstract Cells in the somatosensory cortex of the monkey are known to exhibit sustained elevations of firing frequency during the short-term mnemonic retention of tactile information in a haptic delay task. In this study, we examine the possibility that those firing elevations are accompanied by changes in firing pattern. Patterns are identified by the application of a pattern-searching algorithm to the interspike intervals of spike trains. By sequential use of sets of pattern templates with a range of temporal resolutions, we find patterned activity in the majority of the cells investigated. In general, the degree of patterning significantly increases during active memory. Surrogate analysis suggests that the observed patterns may not be simple linear stochastic functions of instantaneous or average firing frequency. Therefore, during the active retention of a memorandum, the activity of a 'memory cell' may be characterized not only by changes in frequency but also by changes in pattern.

  2. Sharp-Wave Ripples Orchestrate the Induction of Synaptic Plasticity during Reactivation of Place Cell Firing Patterns in the Hippocampus

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    Josef H.L.P. Sadowski

    2016-03-01

    Full Text Available Place cell firing patterns reactivated during hippocampal sharp-wave ripples (SWRs in rest or sleep are thought to induce synaptic plasticity and thereby promote the consolidation of recently encoded information. However, the capacity of reactivated spike trains to induce plasticity has not been directly tested. Here, we show that reactivated place cell firing patterns simultaneously recorded from CA3 and CA1 of rat dorsal hippocampus are able to induce long-term potentiation (LTP at synapses between CA3 and CA1 cells but only if accompanied by SWR-associated synaptic activity and resulting dendritic depolarization. In addition, we show that the precise timing of coincident CA3 and CA1 place cell spikes in relation to SWR onset is critical for the induction of LTP and predictive of plasticity generated by reactivation. Our findings confirm an important role for SWRs in triggering and tuning plasticity processes that underlie memory consolidation in the hippocampus during rest or sleep.

  3. Sharp-Wave Ripples Orchestrate the Induction of Synaptic Plasticity during Reactivation of Place Cell Firing Patterns in the Hippocampus

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    Sadowski, Josef H.L.P.; Jones, Matthew W.; Mellor, Jack R.

    2016-01-01

    Summary Place cell firing patterns reactivated during hippocampal sharp-wave ripples (SWRs) in rest or sleep are thought to induce synaptic plasticity and thereby promote the consolidation of recently encoded information. However, the capacity of reactivated spike trains to induce plasticity has not been directly tested. Here, we show that reactivated place cell firing patterns simultaneously recorded from CA3 and CA1 of rat dorsal hippocampus are able to induce long-term potentiation (LTP) at synapses between CA3 and CA1 cells but only if accompanied by SWR-associated synaptic activity and resulting dendritic depolarization. In addition, we show that the precise timing of coincident CA3 and CA1 place cell spikes in relation to SWR onset is critical for the induction of LTP and predictive of plasticity generated by reactivation. Our findings confirm an important role for SWRs in triggering and tuning plasticity processes that underlie memory consolidation in the hippocampus during rest or sleep. PMID:26904941

  4. [Patterns of action potential firing in cortical neurons of neonatal mice and their electrophysiological property].

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    Furong, Liu; Shengtian, L I

    2016-05-25

    To investigate patterns of action potential firing in cortical heurons of neonatal mice and their electrophysiological properties. The passive and active membrane properties of cortical neurons from 3-d neonatal mice were observed by whole-cell patch clamp with different voltage and current mode. Three patterns of action potential firing were identified in response to depolarized current injection. The effects of action potential firing patterns on voltage-dependent inward and outward current were found. Neurons with three different firing patterns had different thresholds of depolarized current. In the morphology analysis of action potential, the three type neurons were different in rise time, duration, amplitude and threshold of the first action potential evoked by 80 pA current injection. The passive properties were similar in three patterns of action potential firing. These results indicate that newborn cortical neurons exhibit different patterns of action potential firing with different action potential parameters such as shape and threshold.

  5. Spatial patterns in vegetation fires in the Indian region.

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    Vadrevu, Krishna Prasad; Badarinath, K V S; Anuradha, Eaturu

    2008-12-01

    In this study, we used fire count datasets derived from Along Track Scanning Radiometer (ATSR) satellite to characterize spatial patterns in fire occurrences across highly diverse geographical, vegetation and topographic gradients in the Indian region. For characterizing the spatial patterns of fire occurrences, observed fire point patterns were tested against the hypothesis of a complete spatial random (CSR) pattern using three different techniques, the quadrat analysis, nearest neighbor analysis and Ripley's K function. Hierarchical nearest neighboring technique was used to depict the 'hotspots' of fire incidents. Of the different states, highest fire counts were recorded in Madhya Pradesh (14.77%) followed by Gujarat (10.86%), Maharastra (9.92%), Mizoram (7.66%), Jharkhand (6.41%), etc. With respect to the vegetation categories, highest number of fires were recorded in agricultural regions (40.26%) followed by tropical moist deciduous vegetation (12.72), dry deciduous vegetation (11.40%), abandoned slash and burn secondary forests (9.04%), tropical montane forests (8.07%) followed by others. Analysis of fire counts based on elevation and slope range suggested that maximum number of fires occurred in low and medium elevation types and in very low to low-slope categories. Results from three different spatial techniques for spatial pattern suggested clustered pattern in fire events compared to CSR. Most importantly, results from Ripley's K statistic suggested that fire events are highly clustered at a lag-distance of 125 miles. Hierarchical nearest neighboring clustering technique identified significant clusters of fire 'hotspots' in different states in northeast and central India. The implications of these results in fire management and mitigation were discussed. Also, this study highlights the potential of spatial point pattern statistics in environmental monitoring and assessment studies with special reference to fire events in the Indian region.

  6. Natural Firing Patterns Imply Low Sensitivity of Synaptic Plasticity to Spike Timing Compared with Firing Rate.

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    Graupner, Michael; Wallisch, Pascal; Ostojic, Srdjan

    2016-11-02

    Synaptic plasticity is sensitive to the rate and the timing of presynaptic and postsynaptic action potentials. In experimental protocols inducing plasticity, the imposed spike trains are typically regular and the relative timing between every presynaptic and postsynaptic spike is fixed. This is at odds with firing patterns observed in the cortex of intact animals, where cells fire irregularly and the timing between presynaptic and postsynaptic spikes varies. To investigate synaptic changes elicited by in vivo-like firing, we used numerical simulations and mathematical analysis of synaptic plasticity models. We found that the influence of spike timing on plasticity is weaker than expected from regular stimulation protocols. Moreover, when neurons fire irregularly, synaptic changes induced by precise spike timing can be equivalently induced by a modest firing rate variation. Our findings bridge the gap between existing results on synaptic plasticity and plasticity occurring in vivo, and challenge the dominant role of spike timing in plasticity. Synaptic plasticity, the change in efficacy of connections between neurons, is thought to underlie learning and memory. The dominant paradigm posits that the precise timing of neural action potentials (APs) is central for plasticity induction. This concept is based on experiments using highly regular and stereotyped patterns of APs, in stark contrast with natural neuronal activity. Using synaptic plasticity models, we investigated how irregular, in vivo-like activity shapes synaptic plasticity. We found that synaptic changes induced by precise timing of APs are much weaker than suggested by regular stimulation protocols, and can be equivalently induced by modest variations of the AP rate alone. Our results call into question the dominant role of precise AP timing for plasticity in natural conditions. Copyright © 2016 Graupner et al.

  7. Dynamics, patterns and causes of fires in Northwestern Amazonia.

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    Armenteras, Dolors; Retana, Javier

    2012-01-01

    According to recent studies, two widespread droughts occurred in the Amazon basin, one during 2005 and one during 2010. The drought increased the prevalence of climate-driven fires over most of the basin. Given the importance of human-atmosphere-vegetation interactions in tropical rainforests, these events have generated concerns over the vulnerability of this area to climate change. This paper focuses on one of the wettest areas of the basin, Northwestern Amazonia, where the interactions between the climate and fires are much weaker and where little is known about the anthropogenic drivers of fires. We have assessed the response of fires to climate over a ten-year period, and analysed the socio-economic and demographic determinants of fire occurrence. The patterns of fires and climate and their linkages in Northwestern Amazonia differ from the enhanced fire response to climate variation observed in the rest of Amazonia. The highest number of recorded fires in Northwestern Amazonia occurred in 2004 and 2007, and this did not coincide with the periods of extreme drought experienced in Amazonia in 2005 and 2010. Rather, during those years, Northwestern Amazonia experienced a relatively small numbers of fire hotspots. We have shown that fire occurrence correlated well with deforestation and was determined by anthropogenic drivers, mainly small-scale agriculture, cattle ranching (i.e., pastures) and active agricultural frontiers (including illegal crops). Thus, the particular climatic conditions for air convergence and rainfall created by proximity to the Andes, coupled with the presence of one of the most active colonisation fronts in the region, make this region differently affected by the general drought-induced fire patterns experienced by the rest of the Amazon. Moreover, the results suggest that, even in this wet region, humans are able to modify the frequency of fires and impact these historically well preserved forests.

  8. Dynamics, patterns and causes of fires in Northwestern Amazonia.

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    Dolors Armenteras

    Full Text Available According to recent studies, two widespread droughts occurred in the Amazon basin, one during 2005 and one during 2010. The drought increased the prevalence of climate-driven fires over most of the basin. Given the importance of human-atmosphere-vegetation interactions in tropical rainforests, these events have generated concerns over the vulnerability of this area to climate change. This paper focuses on one of the wettest areas of the basin, Northwestern Amazonia, where the interactions between the climate and fires are much weaker and where little is known about the anthropogenic drivers of fires. We have assessed the response of fires to climate over a ten-year period, and analysed the socio-economic and demographic determinants of fire occurrence. The patterns of fires and climate and their linkages in Northwestern Amazonia differ from the enhanced fire response to climate variation observed in the rest of Amazonia. The highest number of recorded fires in Northwestern Amazonia occurred in 2004 and 2007, and this did not coincide with the periods of extreme drought experienced in Amazonia in 2005 and 2010. Rather, during those years, Northwestern Amazonia experienced a relatively small numbers of fire hotspots. We have shown that fire occurrence correlated well with deforestation and was determined by anthropogenic drivers, mainly small-scale agriculture, cattle ranching (i.e., pastures and active agricultural frontiers (including illegal crops. Thus, the particular climatic conditions for air convergence and rainfall created by proximity to the Andes, coupled with the presence of one of the most active colonisation fronts in the region, make this region differently affected by the general drought-induced fire patterns experienced by the rest of the Amazon. Moreover, the results suggest that, even in this wet region, humans are able to modify the frequency of fires and impact these historically well preserved forests.

  9. Fire Patterns and Drivers of Fires in the West African Tropical Forest

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    Dwomoh, F. K.; Wimberly, M. C.

    2015-12-01

    The West African tropical forest (referred to as the Upper Guinean forest, UGF), is a global biodiversity hotspot providing vital ecosystem services for the region's socio-economic and environmental wellbeing. It is also one of the most fragmented and human-modified tropical forest ecosystems, with the only remaining large patches of original forests contained in protected areas. However, these remnant forests are susceptible to continued fire-mediated degradation and forest loss due to intense climatic, demographic and land use pressures. We analyzed human and climatic drivers of fire activity in the sub-region to better understand the spatial and temporal patterns of these risks. We utilized MODIS active fire and burned area products to identify fire activity within the sub-region. We measured climatic variability using TRMM rainfall data and derived indicators of human land use from a variety of geospatial datasets. We used a boosted regression trees model to determine the influences of predictor variables on fire activity. Our analyses indicated that the spatial and temporal variability of precipitation is a key driving factor of fire activity in the UGF. Anthropogenic effects on fire activity in the area were evident through the influences of agriculture and low-density populations. These human footprints in the landscape make forests more susceptible to fires through forest fragmentation, degradation, and fire spread from agricultural areas. Forested protected areas within the forest savanna mosaic experienced frequent fires, whereas the more humid forest areas located in the south and south-western portions of the study area had fewer fires as these rainforests tend to offer some buffering against fire encroachment. These results improve characterization of UGF fire regime and expand our understanding of the spatio-temporal dynamics of tropical forest fires in response to human and climatic pressures.

  10. Pattern formation and firing synchronization in networks of map neurons

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    Wang Qingyun; Duan Zhisheng; Huang Lin; Chen Guanrong; Lu Qishao

    2007-01-01

    Patterns and collective phenomena such as firing synchronization are studied in networks of nonhomogeneous oscillatory neurons and mixtures of oscillatory and excitable neurons, with dynamics of each neuron described by a two-dimensional (2D) Rulkov map neuron. It is shown that as the coupling strength is increased, typical patterns emerge spatially, which propagate through the networks in the form of beautiful target waves or parallel ones depending on the size of networks. Furthermore, we investigate the transitions of firing synchronization characterized by the rate of firing when the coupling strength is increased. It is found that there exists an intermediate coupling strength; firing synchronization is minimal simultaneously irrespective of the size of networks. For further increasing the coupling strength, synchronization is enhanced. Since noise is inevitable in real neurons, we also investigate the effects of white noise on firing synchronization for different networks. For the networks of oscillatory neurons, it is shown that firing synchronization decreases when the noise level increases. For the missed networks, firing synchronization is robust under the noise conditions considered in this paper. Results presented in this paper should prove to be valuable for understanding the properties of collective dynamics in real neuronal networks

  11. Maximum likelihood estimation of motor unit firing pattern statistics.

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    Navallas, Javier; Malanda, Armando; Rodriguez-Falces, Javier

    2014-05-01

    Estimation of motor unit firing pattern statistics is a valuable method in physiological studies and a key procedure in electromyographic (EMG) decomposition algorithms. However, if any firings within the pattern are undetected or missed during the decomposition process, the estimation procedure can be disrupted. In order to provide an optimal solution, we present a maximum likelihood estimator of EMG firing pattern statistics, taking into account that some firings may be undetected. A model of the inter-discharge interval (IDI) probability density function with missing firings has been employed to derive the maximum likelihood estimator of the mean and standard deviation of the IDIs. Actual calculation of the maximum likelihood solution has been obtained by means of numerical optimization. The proposed estimator has been evaluated and compared to other previously developed algorithms by means of simulation experiments and has been tested on real signals. The new estimator was found to be robust and reliable in diverse conditions: IDI distributions with a high coefficient of variance or considerable skewness. Moreover, the proposed estimator outperforms previous algorithms both in simulated and real conditions.

  12. Spatiotemporal distribution patterns of forest fires in northern Mexico

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    Gustavo Pérez-Verdin; M. A. Márquez-Linares; A. Cortes-Ortiz; M. Salmerón-Macias

    2013-01-01

    Using the 2000-2011 CONAFOR databases, a spatiotemporal analysis of the occurrence of forest fires in Durango, one of the most affected States in Mexico, was conducted. The Moran's index was used to determine a spatial distribution pattern; also, an analysis of seasonal and temporal autocorrelation of the data collected was completed. The geographically weighted...

  13. Evaluating fire danger in Brazilian biomes: present and future patterns

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    Silva, Patrícia; Bastos, Ana; DaCamara, Carlos; Libonati, Renata

    2017-04-01

    Climate change is expected to have a significant impact on fire occurrence and activity, particularly in Brazil, a region known to be fire-prone [1]. The Brazilian savanna, commonly referred to as cerrado, is a fire-adapted biome covering more than 20% of the country's total area. It presents the highest numbers of fire events, making it particularly susceptible to changes in climate. It is thus essential to understand the present fire regimes in Brazilian biomes, in order to better evaluate future patterns. The CPTEC/INPE, the Brazilian Center for Weather Forecasting and Climate Research at the Brazilian National Institute of Space Research developed a fire danger index based on the occurrence of hundreds of thousands of fire events in the main Brazilian biomes [2]: the Meteorological Fire Danger Index (MFDI). This index indicates the predisposition of vegetation to be burned on a given day, for given climate conditions preceding that day. It relies on daily values of air temperature, relative humidity, accumulated precipitation and vegetation cover. In this study we aim to access the capability of the MFDI to accurately replicate present fire conditions for different biomes, with a special focus on cerrado. To this end, we assess the link between the MFDI as calculated by three different reanalysis (ERA-Interim, NCEP/DOE Reanalysis 2 and MERRA-2) and the observed burned area. We further calculate the validated MFDI using a regional climate model, the RCA4 as forced by EC-Earth from CORDEX, to understand the ability of the model to characterize present fire danger. Finally, the need to calibrate the model to better characterize future fire danger was also evaluated. This work was developed within the framework of the Brazilian Fire-Land-Atmosphere System (BrFLAS) Project financed by the Portuguese and Brazilian science foundations, FCT and FAPESP (project references FAPESP/1389/2014 and 2014/20042-2). [1] KRAWCHUK, M.A.; MORITZ, M.A.; PARISIEN, M.A.; VAN DORN, J

  14. Interannual variations in fire weather, fire extent, and synoptic-scale circulation patterns in northern California and Oregon

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    Trouet, Valerie; Taylor, Alan H.; Carleton, Andrew M.; Skinner, Carl N.

    2009-03-01

    The Mediterranean climate region on the west coast of the United States is characterized by wet winters and dry summers, and by high fire activity. The importance of synoptic-scale circulation patterns (ENSO, PDO, PNA) on fire-climate interactions is evident in contemporary fire data sets and in pre-Euroamerican tree-ring-based fire records. We investigated how interannual variability in two fire weather indices, the Haines index (HI) and the Energy Release Component (ERC), in the Mediterranean region of southern Oregon and northern California is related to atmospheric circulation and fire extent. Years with high and low fire weather index values corresponded to years with a high and low annual area burned, respectively. HI combines atmospheric moisture with atmospheric instability and variation in HI was more strongly associated with interannual variation in wildfire extent than ERC, which is based on moisture alone. The association between fire extent and HI was also higher for fires in southern Oregon than in northern California. In terms of synoptic-scale circulation patterns, years of high fire risk (i.e., increased potential for erratic fire behavior, represented by HI and ERC) were associated with positive winter PNA and PDO conditions, characterized by enhanced regional mid-tropospheric ridging and low atmospheric moisture. The time lag we found between fire risk potential and prior winter circulation patterns could contribute to the development of long-lead fire-climate forecasting.

  15. Relating neuronal firing patterns to functional differentiation of cerebral cortex.

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    Shigeru Shinomoto

    2009-07-01

    Full Text Available It has been empirically established that the cerebral cortical areas defined by Brodmann one hundred years ago solely on the basis of cellular organization are closely correlated to their function, such as sensation, association, and motion. Cytoarchitectonically distinct cortical areas have different densities and types of neurons. Thus, signaling patterns may also vary among cytoarchitectonically unique cortical areas. To examine how neuronal signaling patterns are related to innate cortical functions, we detected intrinsic features of cortical firing by devising a metric that efficiently isolates non-Poisson irregular characteristics, independent of spike rate fluctuations that are caused extrinsically by ever-changing behavioral conditions. Using the new metric, we analyzed spike trains from over 1,000 neurons in 15 cortical areas sampled by eight independent neurophysiological laboratories. Analysis of firing-pattern dissimilarities across cortical areas revealed a gradient of firing regularity that corresponded closely to the functional category of the cortical area; neuronal spiking patterns are regular in motor areas, random in the visual areas, and bursty in the prefrontal area. Thus, signaling patterns may play an important role in function-specific cerebral cortical computation.

  16. Satellite observations for describing fire patterns and climate-related fire drivers in the Brazilian savannas

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    G. A. V. Mataveli

    2018-01-01

    Full Text Available In the Brazilian savannas (Cerrado biome fires are natural and a tool for shifting land use; therefore, temporal and spatial patterns result from the interaction of climate, vegetation condition and human activities. Moreover, orbital sensors are the most effective approach to establish patterns in the biome. We aimed to characterize fire, precipitation and vegetation condition regimes and to establish spatial patterns of fire occurrence and their correlation with precipitation and vegetation condition in the Cerrado. The Cerrado was first and second biome for the occurrence of burned areas (BA and hotspots, respectively. Occurrences are higher during the dry season and in the savanna land use. Hotspots and BA tend to decrease, and concentrate in the north, but more intense hotspots are not necessarily located where concentration is higher. Spatial analysis showed that averaged and summed values can hide patterns, such as for precipitation, which has the lowest average in August, but minimum precipitation in August was found in 7 % of the Cerrado. Usually, there is a 2–3-month lag between minimum precipitation and maximum hotspots and BA, while minimum VCI and maximum hotspots and BA occur in the same month. Hotspots and BA are better correlated with VCI than precipitation, qualifying VCI as an indicator of the susceptibility of vegetation to ignition.

  17. Satellite observations for describing fire patterns and climate-related fire drivers in the Brazilian savannas

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    Verola Mataveli, Guilherme Augusto; Siqueira Silva, Maria Elisa; Pereira, Gabriel; da Silva Cardozo, Francielle; Shinji Kawakubo, Fernando; Bertani, Gabriel; Cezar Costa, Julio; de Cássia Ramos, Raquel; Valéria da Silva, Viviane

    2018-01-01

    In the Brazilian savannas (Cerrado biome) fires are natural and a tool for shifting land use; therefore, temporal and spatial patterns result from the interaction of climate, vegetation condition and human activities. Moreover, orbital sensors are the most effective approach to establish patterns in the biome. We aimed to characterize fire, precipitation and vegetation condition regimes and to establish spatial patterns of fire occurrence and their correlation with precipitation and vegetation condition in the Cerrado. The Cerrado was first and second biome for the occurrence of burned areas (BA) and hotspots, respectively. Occurrences are higher during the dry season and in the savanna land use. Hotspots and BA tend to decrease, and concentrate in the north, but more intense hotspots are not necessarily located where concentration is higher. Spatial analysis showed that averaged and summed values can hide patterns, such as for precipitation, which has the lowest average in August, but minimum precipitation in August was found in 7 % of the Cerrado. Usually, there is a 2-3-month lag between minimum precipitation and maximum hotspots and BA, while minimum VCI and maximum hotspots and BA occur in the same month. Hotspots and BA are better correlated with VCI than precipitation, qualifying VCI as an indicator of the susceptibility of vegetation to ignition.

  18. Firing patterns of muscle vasoconstrictor neurones in respiratory disease

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    Vaughan G Macefield

    2012-05-01

    Full Text Available Because the cardiovascular system and respiration are so intimately coupled, disturbances in respiratory control often lead to disturbances in cardiovascular control. Obstructive Sleep Apnoea (OSA, Chronic Obstructive Pulmonary Disease (COPD and Bronchiectasis (BE are all associated with a greatly elevated muscle vasoconstrictor drive (muscle sympathetic nerve activity; MSNA. Indeed, the increase in MSNA is comparable to that seen in congestive heart failure (CHF, in which the increase in MSNA compensates for the reduced cardiac output and thereby assists in maintaining blood pressure. However, in OSA – but not COPD or BE – the increase in MSNA can lead to hypertension. Here, the features of the sympathoexcitation in OSA, COPD and BE are reviewed in terms of the firing properties of post-ganglionic muscle vasoconstrictor neurones. Compared to healthy subjects with low levels of resting MSNA, single-unit recordings revealed that the augmented MSNA seen in OSA, BE, COPD and CHF were each associated with an increase in firing probability and mean firing rates of individual neurones. However, unlike patients with heart failure, all patients with respiratory disease exhibited an increase in multiple within-burst firing which, it is argued, reflects an increase in central sympathetic drive. Similar patterns to those seen in OSA, COPD and BE were seen in healthy subjects during an acute increase in muscle vasoconstrictor drive. These observations emphasise the differences by which the sympathetic nervous system grades its output in health and disease, with an increase in firing probability of active neurones and recruitment of additional neurones being the dominant mechanisms.

  19. Histomorphological patterns in osseous rests exposed at fire

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    Medina, C.; Tiesler, V.; Oliva, A.I.; Quintana, P.

    2005-01-01

    Histomorphology as part of morphological research studies bony structure on the tissue level. Its methods are applied in this investigation to evaluate histomorphological impact patterns in heat-exposed bony material, particularly color changes, fissure patterns, volumetric reduction, and changes in the size of Haversian canals. These variables were evaluated in exposed thin sections of porcine long bones, obtained during two experimental series. The first one was conducted under stable thermal conditions in a furnace by measuring heat impact in stepped time (I to S hours) and temperature intervals (200 to 800 C). During a second experimental phase, bony samples were exposed to direct fire in defined time and heat intervals. The treated specimens were then sectioned and microscopically scrutinized. The results presented here were designed to offer new analytical, measurable standards in the investigation of forms of heat exposition of the human body, applicable in forensics and the study of ancient Maya posthumous body treatments. (Author)

  20. Normalized burn ratios link fire severity with patterns of avian occurrence

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    Rose, Eli T.; Simons, Theodore R.; Klein, Rob; McKerrow, Alexa

    2016-01-01

    ContextRemotely sensed differenced normalized burn ratios (DNBR) provide an index of fire severity across the footprint of a fire. We asked whether this index was useful for explaining patterns of bird occurrence within fire adapted xeric pine-oak forests of the southern Appalachian Mountains.ObjectivesWe evaluated the use of DNBR indices for linking ecosystem process with patterns of bird occurrence. We compared field-based and remotely sensed fire severity indices and used each to develop occupancy models for six bird species to identify patterns of bird occurrence following fire.MethodsWe identified and sampled 228 points within fires that recently burned within Great Smoky Mountains National Park. We performed avian point counts and field-assessed fire severity at each bird census point. We also used Landsat™ imagery acquired before and after each fire to quantify fire severity using DNBR. We used non-parametric methods to quantify agreement between fire severity indices, and evaluated single season occupancy models incorporating fire severity summarized at different spatial scales.ResultsAgreement between field-derived and remotely sensed measures of fire severity was influenced by vegetation type. Although occurrence models using field-derived indices of fire severity outperformed those using DNBR, summarizing DNBR at multiple spatial scales provided additional insights into patterns of occurrence associated with different sized patches of high severity fire.ConclusionsDNBR is useful for linking the effects of fire severity to patterns of bird occurrence, and informing how high severity fire shapes patterns of bird species occurrence on the landscape.

  1. Identification of neural firing patterns, frequency and temporal coding mechanisms in individual aortic baroreceptors

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    Huaguang eGu

    2015-08-01

    Full Text Available In rabbit depressor nerve fibers, an on-off firing pattern, period-1 firing, and integer multiple firing with quiescent state were observed as the static pressure level was increased. A bursting pattern with bursts at the systolic phase of blood pressure, continuous firing, and bursting with burst at diastolic phase and quiescent state at systolic phase were observed as the mean level of the dynamic blood pressure was increased. For both static and dynamic pressures, the firing frequency of the first two firing patterns increased and of the last firing pattern decreased due to the quiescent state. If the quiescent state is disregarded, the spike frequency becomes an increasing trend. The instantaneous spike frequency of the systolic phase bursting, continuous firing, and diastolic phase bursting can reflect the temporal process of the systolic phase, whole procedure, and diastolic phase of the dynamic blood pressure signal, respectively. With increasing the static current corresponding to pressure level, the deterministic Hodgkin-Huxley (HH model manifests a process from a resting state first to period-1 firing via a subcritical Hopf bifurcation and then to a resting state via a supercritical Hopf bifurcation, and the firing frequency increases. The on-off firing and integer multiple firing were here identified as noise-induced firing patterns near the subcritical and supercritical Hopf bifurcation points, respectively, using the stochastic HH model. The systolic phase bursting and diastolic phase bursting were identified as pressure-induced firings near the subcritical and supercritical Hopf bifurcation points, respectively, using an HH model with a dynamic signal. The firing, spike frequency, and instantaneous spike frequency observed in the experiment were simulated and explained using HH models. The results illustrate the dynamics of different firing patterns and the frequency and temporal coding mechanisms of aortic baroreceptor.

  2. Global fire activity patterns (1996─2006 and climatic influence: an analysis using the World Fire Atlas

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    D. Oom

    2008-04-01

    Full Text Available Vegetation fires have been acknowledged as an environmental process of global scale, which affects the chemical composition of the troposphere, and has profound ecological and climatic impacts. However, considerable uncertainty remains, especially concerning intra and inter-annual variability of fire incidence. The main goals of our global-scale study were to characterise spatial-temporal patterns of fire activity, to identify broad geographical areas with similar vegetation fire dynamics, and to analyse the relationship between fire activity and the El Niño-Southern Oscillation. This study relies on 10 years (mid 1996–mid 2006 of screened European Space Agency World Fire Atlas (WFA data, obtained from Along Track Scanning Radiometer (ATSR and Advanced ATSR (AATSR imagery. Empirical Orthogonal Function analysis was used to reduce the dimensionality of the dataset. Regions of homogeneous fire dynamics were identified with cluster analysis, and interpreted based on their eco-climatic characteristics. The impact of 1997–1998 El Niño is clearly dominant over the study period, causing increased fire activity in a variety of regions and ecosystems, with variable timing. Overall, this study provides the first global decadal assessment of spatial-temporal fire variability and confirms the usefulness of the screened WFA for global fire ecoclimatology research.

  3. Post-fire vegetation and fuel development influences fire severity patterns in reburns.

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    Coppoletta, Michelle; Merriam, Kyle E; Collins, Brandon M

    2016-04-01

    In areas where fire regimes and forest structure have been dramatically altered, there is increasing concern that contemporary fires have the potential to set forests on a positive feedback trajectory with successive reburns, one in which extensive stand-replacing fire could promote more stand-replacing fire. Our study utilized an extensive set of field plots established following four fires that occurred between 2000 and 2010 in the northern Sierra Nevada, California, USA that were subsequently reburned in 2012. The information obtained from these field plots allowed for a unique set of analyses investigating the effect of vegetation, fuels, topography, fire weather, and forest management on reburn severity. We also examined the influence of initial fire severity and time since initial fire on influential predictors of reburn severity. Our results suggest that high- to moderate-severity fire in the initial fires led to an increase in standing snags and shrub vegetation, which in combination with severe fire weather promoted high-severity fire effects in the subsequent reburn. Although fire behavior is largely driven by weather, our study demonstrates that post-fire vegetation composition and structure are also important drivers of reburn severity. In the face of changing climatic regimes and increases in extreme fire weather, these results may provide managers with options to create more fire-resilient ecosystems. In areas where frequent high-severity fire is undesirable, management activities such as thinning, prescribed fire, or managed wildland fire can be used to moderate fire behavior not only prior to initial fires, but also before subsequent reburns.

  4. Phasic firing in vasopressin cells: understanding its functional significance through computational models.

    Directory of Open Access Journals (Sweden)

    Duncan J MacGregor

    Full Text Available Vasopressin neurons, responding to input generated by osmotic pressure, use an intrinsic mechanism to shift from slow irregular firing to a distinct phasic pattern, consisting of long bursts and silences lasting tens of seconds. With increased input, bursts lengthen, eventually shifting to continuous firing. The phasic activity remains asynchronous across the cells and is not reflected in the population output signal. Here we have used a computational vasopressin neuron model to investigate the functional significance of the phasic firing pattern. We generated a concise model of the synaptic input driven spike firing mechanism that gives a close quantitative match to vasopressin neuron spike activity recorded in vivo, tested against endogenous activity and experimental interventions. The integrate-and-fire based model provides a simple physiological explanation of the phasic firing mechanism involving an activity-dependent slow depolarising afterpotential (DAP generated by a calcium-inactivated potassium leak current. This is modulated by the slower, opposing, action of activity-dependent dendritic dynorphin release, which inactivates the DAP, the opposing effects generating successive periods of bursting and silence. Model cells are not spontaneously active, but fire when perturbed by random perturbations mimicking synaptic input. We constructed one population of such phasic neurons, and another population of similar cells but which lacked the ability to fire phasically. We then studied how these two populations differed in the way that they encoded changes in afferent inputs. By comparison with the non-phasic population, the phasic population responds linearly to increases in tonic synaptic input. Non-phasic cells respond to transient elevations in synaptic input in a way that strongly depends on background activity levels, phasic cells in a way that is independent of background levels, and show a similar strong linearization of the response

  5. Dynamics and Physiological Roles of Stochastic Firing Patterns Near Bifurcation Points

    Science.gov (United States)

    Jia, Bing; Gu, Huaguang

    2017-06-01

    Different stochastic neural firing patterns or rhythms that appeared near polarization or depolarization resting states were observed in biological experiments on three nervous systems, and closely matched those simulated near bifurcation points between stable equilibrium point and limit cycle in a theoretical model with noise. The distinct dynamics of spike trains and interspike interval histogram (ISIH) of these stochastic rhythms were identified and found to build a relationship to the coexisting behaviors or fixed firing frequency of four different types of bifurcations. Furthermore, noise evokes coherence resonances near bifurcation points and plays important roles in enhancing information. The stochastic rhythms corresponding to Hopf bifurcation points with fixed firing frequency exhibited stronger coherence degree and a sharper peak in the power spectrum of the spike trains than those corresponding to saddle-node bifurcation points without fixed firing frequency. Moreover, the stochastic firing patterns changed to a depolarization resting state as the extracellular potassium concentration increased for the injured nerve fiber related to pathological pain or static blood pressure level increased for aortic depressor nerve fiber, and firing frequency decreased, which were different from the physiological viewpoint that firing frequency increased with increasing pressure level or potassium concentration. This shows that rhythms or firing patterns can reflect pressure or ion concentration information related to pathological pain information. Our results present the dynamics of stochastic firing patterns near bifurcation points, which are helpful for the identification of both dynamics and physiological roles of complex neural firing patterns or rhythms, and the roles of noise.

  6. Mixed-Severity Fire Fosters Heterogeneous Spatial Patterns of Conifer Regeneration in a Dry Conifer Forest

    Directory of Open Access Journals (Sweden)

    Sparkle L. Malone

    2018-01-01

    Full Text Available We examined spatial patterns of post-fire regenerating conifers in a Colorado, USA, dry conifer forest 11–12 years following the reintroduction of mixed-severity fire. We mapped and measured all post-fire regenerating conifers, as well as all other post-fire regenerating trees and all residual (i.e., surviving trees, in three 4-ha plots following the 2002 Hayman Fire. Residual tree density ranged from 167 to 197 trees ha−1 (TPH, and these trees were clustered at distances up to 30 m. Post-fire regenerating conifers, which ranged in density from 241 to 1036 TPH, were also clustered at distances up to at least 30 m. Moreover, residual tree locations drove post-fire regenerating conifer locations, with the two showing a pattern of repulsion. Topography and post-fire sprouting tree species locations further drove post-fire conifer regeneration locations. These results provide a foundation for anticipating how the reintroduction of mixed-severity fire may affect long-term forest structure, and also yield insights into how historical mixed-severity fire may have regulated the spatially heterogeneous conditions commonly described for pre-settlement dry conifer forests of Colorado and elsewhere.

  7. Climate controls on fire pattern in African and Australian continents

    Science.gov (United States)

    Zubkova, M.; Boschetti, L.; Abatzoglou, J. T.

    2017-12-01

    Studies have primarily attributed the recent decrease in global fire activity in many savanna and grassland regions as detected by the Global Fire Emission Database (GFEDv4s) to anthropogenic changes such as deforestation and cropland expansion (Andela et al. 2017, van der Werf et al. 2008). These changes have occurred despite increases in fire weather season length (Jolly et al. 2015). Efforts to better resolve retrospective and future changes in fire activity require refining the host of influences on societal and environmental factors on fire activity. In this study, we analyzed how climate variability influences interannual fire activity in Africa and Australia, the two continents most affected by fire and responsible for over half of the global pyrogenic emissions. We expand on the analysis presented in Andela et al. (2017) by using the most recent Collection 6 MODIS MCD64 Burned Area Product and exploring the explanatory power of a broader suite of climate variables that have been previously shown to explain fire variability (Bowman et al. 2017). We examined which climate metrics show a strong interannual relationship with the amount of burned area and fire size accounting for antecedent and in-season atmospheric conditions. Fire characteristics were calculated using the 500m resolution MCD64A1 product (2002-2016); the analysis was conducted at the ecoregion scale, and further stratified by landcover using a broad aggregation (forest, shrublands and grasslands) of the Landcover CCI maps (CCI-LC, 2014); all agricultural areas fires were excluded from the analysis. The results of the analysis improve our knowledge of climate controls on fire dynamics in the most fire-prone places in the world which is critical for statistical fire and vegetation models. Being able to predict the impact of climate on fire activity has a strategic importance in designing future fire management scenarios, help to avoid degradation of biodiversity and ecosystem services and improve

  8. Dense pattern multiple pass cells

    Science.gov (United States)

    Silver, Joel A.; Bomse, David S.

    2010-09-21

    An optical cell and a method of operating an optical cell comprising employing a first mirror comprising a first hole therein at approximately a center of the first mirror and through which laser light enters the cell, employing a second mirror comprising a second hole therein at approximately a center of the second mirror and through which laser light exits the cell, and forming a Lissajous pattern of spots on the mirrors by repeated reflection of laser light entering the cell.

  9. Activity patterns of neurosecretory cells releasing pheromonotropic neuropeptides in the moth Bombyx mori

    OpenAIRE

    Ichikawa, Toshio

    1998-01-01

    Short- and long-term firing patterns of neurosecretory cells releasing pheromonotropic neuropeptides in the silkworm moth Bombyx mori were examined. The cells showed three types of rhythmic changes in firing activity. Bursting activities with an interval of several seconds were synchronized with rhythmic abdominal motions for calling behavior. A slow fluctuation in firing activity over a period of several minutes depended on cyclic alternations of the flow of hemolymph. The electrical activit...

  10. The influence of a fire-induced convection column on radiological fallout patterns

    Science.gov (United States)

    A. Broido; A.W. McMasters

    1959-01-01

    Since no nuclear devices have been detonated by the United States under conditions leading to both mass fires and radiological fallout, a theoretical and small-scale experimental study was undertaken to see if fire-induced convection columns could significantly affect fallout patterns. Experiments were conducted in a 6- by 6-foot low-velocity wind tunnel using full-...

  11. Predicting the effect of fire on large-scale vegetation patterns in North America.

    Science.gov (United States)

    Donald McKenzie; David L. Peterson; Ernesto. Alvarado

    1996-01-01

    Changes in fire regimes are expected across North America in response to anticipated global climatic changes. Potential changes in large-scale vegetation patterns are predicted as a result of altered fire frequencies. A new vegetation classification was developed by condensing Kuchler potential natural vegetation types into aggregated types that are relatively...

  12. Effect of inhibitory firing pattern on coherence resonance in random neural networks

    Science.gov (United States)

    Yu, Haitao; Zhang, Lianghao; Guo, Xinmeng; Wang, Jiang; Cao, Yibin; Liu, Jing

    2018-01-01

    The effect of inhibitory firing patterns on coherence resonance (CR) in random neuronal network is systematically studied. Spiking and bursting are two main types of firing pattern considered in this work. Numerical results show that, irrespective of the inhibitory firing patterns, the regularity of network is maximized by an optimal intensity of external noise, indicating the occurrence of coherence resonance. Moreover, the firing pattern of inhibitory neuron indeed has a significant influence on coherence resonance, but the efficacy is determined by network property. In the network with strong coupling strength but weak inhibition, bursting neurons largely increase the amplitude of resonance, while they can decrease the noise intensity that induced coherence resonance within the neural system of strong inhibition. Different temporal windows of inhibition induced by different inhibitory neurons may account for the above observations. The network structure also plays a constructive role in the coherence resonance. There exists an optimal network topology to maximize the regularity of the neural systems.

  13. Synoptic circulation and temperature pattern during severe wildland fires

    Science.gov (United States)

    Warren E. Heilman

    1996-01-01

    Large-scale changes in the atmosphere associated with a globally changed climate and changes in climatic variability may have important regional impacts on the frequency and severity of wildland fires in the future.

  14. Patterning: Cells nourished by nanodrops

    Science.gov (United States)

    Healy, Kevin E.

    2009-09-01

    Delivering biomolecules to living cells in a spatially defined way in vitro could help us to understand more in vivo processes. Using an aqueous two-phase system enables the formation of patterns at the nanolitre scale that can serve as a confined reagent-delivery system for mammalian cells.

  15. Dynamics and transitions of firing patterns in deterministic and stochastic neuronal systems

    Energy Technology Data Exchange (ETDEWEB)

    Lu Qishao [School of Science, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)], E-mail: qishaolu@hotmail.com; Yang Zhuoqin; Duan Lixia [School of Science, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Gu Huaguang; Ren Wei [Institute of Space Medico-Engineering, P.O. Box 5104, Branch 15, Beijing 100094 (China)

    2009-04-30

    Some recent work on experimental and theoretical studies on complex firing patterns of neurons and their dynamical mechanisms is reviewed. At first, experimental results on various neural firings and the bifurcation scenarios of ISI series are discovered in neural pacemakers. Next, a thorough analysis on dynamical behaviour and transitions of neuronal firing patterns, including the period-adding bursting sequence without chaos, the integer multiple firing and GWN-induced firing activities, are demonstrated in both the deterministic and stochastic Chay neuronal systems by means of the bifurcation theory and fast/slow dynamics. Finally, the parameter regions for different types of bursting as well as their transitions in the Chay and ML neuronal systems are presented.

  16. Spontaneous firings of carnivorous aquatic Utricularia traps: temporal patterns and mechanical oscillations.

    Directory of Open Access Journals (Sweden)

    Olivier Vincent

    Full Text Available Aquatic species of Utricularia are carnivorous plants living in environments poor in nutrients. Their trapping mechanism has fascinated generations of scientists and is still debated today. It was reported recently that Utricularia traps can fire spontaneously. We show here that these spontaneous firings follow an unexpected diversity of temporal patterns, from "metronomic" traps which fire at fixed time intervals to "random" patterns, displaying more scattered firing times. Some "bursting" traps even combine both aspects, with groups of fast regular firings separated by a variable amount of time. We propose a physical model to understand these very particular behaviors, showing that a trap of Utricularia accomplishes mechanical oscillations, based on continuous pumping and sudden opening of the trap door (buckling. We isolate the key parameters governing these oscillations and discuss the effect of their fluctuations.

  17. Sequentially firing neurons confer flexible timing in neural pattern generators

    International Nuclear Information System (INIS)

    Urban, Alexander; Ermentrout, Bard

    2011-01-01

    Neuronal networks exhibit a variety of complex spatiotemporal patterns that include sequential activity, synchrony, and wavelike dynamics. Inhibition is the primary means through which such patterns are implemented. This behavior is dependent on both the intrinsic dynamics of the individual neurons as well as the connectivity patterns. Many neural circuits consist of networks of smaller subcircuits (motifs) that are coupled together to form the larger system. In this paper, we consider a particularly simple motif, comprising purely inhibitory interactions, which generates sequential periodic dynamics. We first describe the dynamics of the single motif both for general balanced coupling (all cells receive the same number and strength of inputs) and then for a specific class of balanced networks: circulant systems. We couple these motifs together to form larger networks. We use the theory of weak coupling to derive phase models which, themselves, have a certain structure and symmetry. We show that this structure endows the coupled system with the ability to produce arbitrary timing relationships between symmetrically coupled motifs and that the phase relationships are robust over a wide range of frequencies. The theory is applicable to many other systems in biology and physics.

  18. Rainfall patterns after fire differentially affect the recruitment of three Mediterranean shrubs

    Directory of Open Access Journals (Sweden)

    J. M. Moreno

    2011-12-01

    Full Text Available In fire-prone environments, the "event-dependent hypothesis" states that plant population changes are driven by the unique set of conditions of a fire (e.g. fire season, climate. Climate variability, in particular changes in rainfall patterns, can be most important for seeder species, since they regenerate after fire from seeds, and for Mediterranean shrublands, given the high yearly variability of rainfall in these ecosystems. Yet, the role of rainfall variability and its interaction with fire characteristics (e.g. fire season on plant populations has received little attention. Here we investigated the changes in seedling emergence and recruitment of three seeder species (Cistus ladanifer, Erica umbellata and Rosmarinus officinalis after fires lit during three different years and at two times (early and late during the fire season. Three plots were burned at each season, for a total of 18 plots burned during the three years. After fire, emerged seedlings were tallied, tagged and monitored during three years (two in the last burning year. Rainfall during the study period was rather variable and, in some years, it was well below average. Postfire seedling emergence varied by a factor of 3 to 12, depending on the species and on the burning year. The bulk of seedling emergence occurred during the first year after fire; seedling recruitment at the end of the study period was tightly correlated with this early emergence. Emergence in Erica and Rosmarinus, but not in Cistus, was correlated with precipitation in the fall and winter immediately after fire, with Erica being the most sensitive to reduced rainfall. Fire season was generally neither an important factor in controlling emergence nor, in particular, recruitment. We discuss how projected changes in rainfall patterns with global warming could alter the balance of species in this shrubland, and could drive some species to near local extinction.

  19. Bistability in spinal motoneurons in vivo: systematic variations in rhythmic firing patterns.

    Science.gov (United States)

    Lee, R H; Heckman, C J

    1998-08-01

    In the presence of the monoamines serotonin and norepinephrine, spinal motoneurons can exhibit bistable behavior, in which a brief period of excitatory input evokes prolonged self-sustained firing. A brief inhibitory input returns the cell to the quiescent state. To determine whether motoneurons differ in their capacity for bistable behavior, intracellular recordings were obtained in the decerebrate cat preparation. To enhance the likelihood of encountering bistable behavior, the noradrenergic alpha1 agonist methoxamine was applied to the ventral surface of the cord. The capacity of the cells to produce bistable behavior was assessed from the duration of self-sustained firing evoked by a brief (1.5 s) excitatory synaptic input from muscle spindle Ia afferents. About 35% (17 of 49) of the cells produced steady self-sustained firing for >3 s and were considered fully bistable. The other 32 cells ( approximately 65%) were partially bistable, with self-sustained firing lasting zero current, so that the ascending current threshold was positive while the descending current threshold was negative. This negative offset meant that fully bistable cells could exhibit tonic firing without depolarizing injected current. Partially bistable cells exhibited very different F-I characteristics. Firing rate acceleration was just as large as in fully bistable cells but did not occur until well above the current level needed to initiate rhythmic firing. F-I gain after acceleration was negative, there was little to no hysteresis between the ascending and descending firing thresholds, and both thresholds were above the zero current level. These properties of partially bistable cells suggest their functional role is in tasks requiring relatively brief, high forces. The low thresholds of fully bistable cells mean they will be readily recruited in low force tasks like posture, where their prolonged self-sustained firing would be advantageous.

  20. Learning causes reorganization of neuronal firing patterns to represent related experiences within a hippocampal schema.

    Science.gov (United States)

    McKenzie, Sam; Robinson, Nick T M; Herrera, Lauren; Churchill, Jordana C; Eichenbaum, Howard

    2013-06-19

    According to schema theory as proposed by Piaget and Bartlett, learning involves the assimilation of new memories into networks of preexisting knowledge, as well as alteration of the original networks to accommodate the new information. Recent evidence has shown that rats form a schema of goal locations and that the hippocampus plays an essential role in adding new memories to the spatial schema. Here we examined the nature of hippocampal contributions to schema updating by monitoring firing patterns of multiple CA1 neurons as rats learned new goal locations in an environment in which there already were multiple goals. Before new learning, many neurons that fired on arrival at one goal location also fired at other goals, whereas ensemble activity patterns also distinguished different goal events, thus constituting a neural representation that linked distinct goals within a spatial schema. During new learning, some neurons began to fire as animals approached the new goals. These were primarily the same neurons that fired at original goals, the activity patterns at new goals were similar to those associated with the original goals, and new learning also produced changes in the preexisting goal-related firing patterns. After learning, activity patterns associated with the new and original goals gradually diverged, such that initial generalization was followed by a prolonged period in which new memories became distinguished within the ensemble representation. These findings support the view that consolidation involves assimilation of new memories into preexisting neural networks that accommodate relationships among new and existing memories.

  1. Spatiotemporal patterns of fire-induced forest mortality in boreal regions and its potential drivers

    Science.gov (United States)

    Yang, J.; Tian, H.; Pan, S.; Hansen, M.; Wang, Y.

    2017-12-01

    Wildfire is the major natural disturbance in boreal forests, which have substantially affected various biological and biophysical processes. Although a few previous studies examined fire severity in boreal regions and reported a higher fire-induced forest mortality in boreal North America than in boreal Eurasia, it remains unclear how this mortality changes over time and how environmental factors affect the temporal dynamics of mortality at a large scale. By using a combination of multiple sources of satellite observations, we investigate the spatiotemporal patterns of fire-induced forest mortality in boreal regions, and examine the contributions of potential drivers. Our results show that forest composition is the key factor influencing the spatial variations of fire mortality across ecoregions. For the temporal variations, we find that the late-season burning was associated with higher fire intensity, which lead to greater forest mortality than the early-season burning. Forests burned in the warm and dry years had greater mortality than those burned in the cool and wet years. Our findings suggest that climate warming and drying not only stimulated boreal fire frequency, but also enhanced fire severity and forest mortality. Due to the significant effects of forest mortality on vegetation structure and ecosystem carbon dynamics, the spatiotemporal changes of fire-induced forest mortality should be explicitly considered to better understand fire impacts on regional and global climate change.

  2. Extreme Fire Severity Patterns in Topographic, Convective and Wind-Driven Historical Wildfires of Mediterranean Pine Forests

    Science.gov (United States)

    Lecina-Diaz, Judit; Alvarez, Albert; Retana, Javier

    2014-01-01

    Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR) from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1) determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together) and (2) ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires). The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires) showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn as extreme

  3. Extreme fire severity patterns in topographic, convective and wind-driven historical wildfires of Mediterranean pine forests.

    Science.gov (United States)

    Lecina-Diaz, Judit; Alvarez, Albert; Retana, Javier

    2014-01-01

    Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR) from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1) determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together) and (2) ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires). The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires) showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn as extreme

  4. Twentieth-century fire patterns in the Selway-Bitterroot Wilderness Area, Idaho/Montana, and the Gila/Aldo Leopold Wilderness Complex, New Mexico

    Science.gov (United States)

    Matthew Rollins; Tom Swetnam; Penelope Morgan

    2000-01-01

    Twentieth century fire patterns were analyzed for two large, disparate wilderness areas in the Rocky Mountains. Spatial and temporal patterns of fires were represented as GIS-based digital fire atlases compiled from archival Forest Service data. We find that spatial and temporal fire patterns are related to landscape features and changes in land use. The rate and...

  5. Patterns of fire activity over Indonesia and Malaysia from polar and geostationary satellite observations

    Science.gov (United States)

    Hyer, Edward J.; Reid, Jeffrey S.; Prins, Elaine M.; Hoffman, Jay P.; Schmidt, Christopher C.; Miettinen, Jukka I.; Giglio, Louis

    2013-03-01

    Biomass burning patterns over the Maritime Continent of Southeast Asia are examined using a new active fire detection product based on application of the Wildfire Automated Biomass Burning Algorithm (WF_ABBA) to data from the imagers on the MTSAT geostationary satellites operated by the Japanese space agency JAXA. Data from MTSAT-1R and MTSAT-2 covering 34 months from September 2008 to July 2011 are examined for a study region consisting of Indonesia, Malaysia, and nearby environs. The spatial and temporal distributions of fires detected in the MTSAT WF_ABBA product are described and compared with active fire observations from MODIS MOD14 data. Land cover distributions for the two instruments are examined using a new 250 m land cover product from the National University of Singapore. The two products show broadly similar patterns of fire activity, land cover distribution of fires, and pixel fire radiative power (FRP). However, the MTSAT WF_ABBA data differ from MOD14 in important ways. Relative to MODIS, the MTSAT WF_ABBA product has lower overall detection efficiency, but more fires detected due to more frequent looks, a greater relative fraction of fires in forest and a lower relative fraction of fires in open areas, and significantly higher single-pixel retrieved FRP. The differences in land cover distribution and FRP between the MTSAT and MODIS products are shown to be qualitatively consistent with expectations based on pixel size and diurnal sampling. The MTSAT WF_ABBA data are used to calculate coverage-corrected diurnal cycles of fire for different regions within the study area. These diurnal cycles are preliminary but demonstrate that the fraction of diurnal fire activity sampled by the two MODIS sensors varies significantly by region and vegetation type. Based on the results from comparison of the two fire products, a series of steps is outlined to account for some of the systematic biases in each of these satellite products in order to produce a

  6. Forest and Land Fire Prevention Through the Hotspot Movement Pattern Approach

    Science.gov (United States)

    Turmudi, T.; Kardono, P.; Hartanto, P.; Ardhitasari, Y.

    2018-02-01

    Indonesia has experienced a great forest fire disaster in 2015. The losses incurred were enormous. But actually the incidence of forest and land fires occurs almost every year. Various efforts were made to cope with the fire disaster. The appearance of a hotspot becomes an early indication of the fire incident both location and time. By studying the location and time of the hotspot's appearance indicates that the hotspot has certain movement patterns from year to year. This study aims to show the pattern of movement of hotspots from year to year that can be used for the prevention of forest and land fires. The method used is time series analysis of land cover and hotspot distribution. The data used were land cover data from 2005 to 2016, hotspot data from 2005 to 2016. The location of this study is the territory of Meranti Kepulauan District. The results show that the highest hotspot is 425 hotspots occurs in the shrubs and bushes. From year to year, the pattern of hotspot movement occurs in the shrubs and bushes cover. The hotspot pattern follows the direction of unused land for cultivation and is dominated by shrubs. From these results, we need to pay more attentiont for the land with the cover of shrubs adjacent to the cultivated land.

  7. Pattern and process of prescribed fires influence effectiveness at reducing wildfire severity in dry coniferous forests

    Science.gov (United States)

    Arkle, Robert S.; Pilliod, David S.; Welty, Justin L.

    2012-01-01

    We examined the effects of three early season (spring) prescribed fires on burn severity patterns of summer wildfires that occurred 1–3 years post-treatment in a mixed conifer forest in central Idaho. Wildfire and prescribed fire burn severities were estimated as the difference in normalized burn ratio (dNBR) using Landsat imagery. We used GIS derived vegetation, topography, and treatment variables to generate models predicting the wildfire burn severity of 1286–5500 30-m pixels within and around treated areas. We found that wildfire severity was significantly lower in treated areas than in untreated areas and significantly lower than the potential wildfire severity of the treated areas had treatments not been implemented. At the pixel level, wildfire severity was best predicted by an interaction between prescribed fire severity, topographic moisture, heat load, and pre-fire vegetation volume. Prescribed fire severity and vegetation volume were the most influential predictors. Prescribed fire severity, and its influence on wildfire severity, was highest in relatively warm and dry locations, which were able to burn under spring conditions. In contrast, wildfire severity peaked in cooler, more mesic locations that dried later in the summer and supported greater vegetation volume. We found considerable evidence that prescribed fires have landscape-level influences within treatment boundaries; most notable was an interaction between distance from the prescribed fire perimeter and distance from treated patch edges, which explained up to 66% of the variation in wildfire severity. Early season prescribed fires may not directly target the locations most at risk of high severity wildfire, but proximity of these areas to treated patches and the discontinuity of fuels following treatment may influence wildfire severity and explain how even low severity treatments can be effective management tools in fire-prone landscapes.

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

    Science.gov (United States)

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

    2011-01-01

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

  9. Detection of Variability of the Motor Unit Action Potential Shape by Means of the Firing Patterns

    DEFF Research Database (Denmark)

    Krarup, Christian; Nikolic, Mile; Dahl, Kristian

    1997-01-01

    The motor unit action potential is a summation of the potentials of the individual muscle fibers from the same motor unit.By using a newly developed automatic EMG decomposition system, variability of the firing patterns of the muscle fibers are analyzed.......The motor unit action potential is a summation of the potentials of the individual muscle fibers from the same motor unit.By using a newly developed automatic EMG decomposition system, variability of the firing patterns of the muscle fibers are analyzed....

  10. Setting FIRES to Stem Cell Research

    Science.gov (United States)

    Miller, Roxanne Grietz

    2005-01-01

    The goal of this lesson is to present the basic scientific knowledge about stem cells, the promise of stem cell research to medicine, and the ethical considerations and arguments involved. One of the challenges of discussing stem cell research is that the field is constantly evolving and the most current information changes almost daily. Few…

  11. Landscape Patterns of Burn Severity in the Soberanes Fire of 2016

    Science.gov (United States)

    Potter, Christopher

    2016-01-01

    The Soberanes Fire started on July 22, 2016 in Monterey County on the California Central Coast from an illegal campfire. This fire burned for 10 weeks at a record cost of more than $208 million for protection and control. A progressive analysis of the normalized burn ratio from the Landsat satellite showed that the final high burn severity (HBS) area for the Soberanes Fire comprised 22 percent of the total area burned, whereas final moderate burn severity (MBS) area comprised about 10 percent of the total area burned of approximately 53,470 ha (132,130 acres). The resulting landscape pattern of burn severity classes from the 2016 Soberanes Fire revealed that the majority of HBS area was located in the elevation zone between 500 and 1000 m, in the slope zone between 15 percent and 30 percent, or on south-facing aspects.

  12. Fire patterns in the range of the greater sage-grouse, 1984-2013 — Implications for conservation and management

    Science.gov (United States)

    Brooks, Matthew L.; Matchett, John R.; Shinneman, Douglas J.; Coates, Peter S.

    2015-09-10

    Fire ranks among the top three threats to the greater sage-grouse (Centrocercus urophasianus) throughout its range, and among the top two threats in the western part of its range. The national research strategy for this species and the recent U.S. Department of the Interior Secretarial Order 3336 call for science-based threats assessment of fire to inform conservation planning and fire management efforts. The cornerstone of such assessments is a clear understanding of where fires are occurring and what aspects of fire regimes may be shifting outside of their historical range of variation. This report fulfills this need by describing patterns of fire area, fire size, fire rotation, and fire season length and timing from 1984 to 2013 across the range of the greater sage-grouse. This information need is further addressed by evaluating the ecological and management implications of these fire patterns. Analyses are stratified by major vegetation types and the seven greater sage-grouse management zones, delineated regionally as four western and three eastern management zones. Soil temperature and moisture indicators of resilience to fire and resistance to cheatgrass invasion, and the potential for establishment of a grass/fire cycle, are used as unifying concepts in developing fire threat assessments for each analysis strata.

  13. Post-fire spatial patterns of soil nitrogen mineralization and microbial abundance.

    Directory of Open Access Journals (Sweden)

    Erica A H Smithwick

    Full Text Available Stand-replacing fires influence soil nitrogen availability and microbial community composition, which may in turn mediate post-fire successional dynamics and nutrient cycling. However, fires create patchiness at both local and landscape scales and do not result in consistent patterns of ecological dynamics. The objectives of this study were to (1 quantify the spatial structure of microbial communities in forest stands recently affected by stand-replacing fire and (2 determine whether microbial variables aid predictions of in situ net nitrogen mineralization rates in recently burned stands. The study was conducted in lodgepole pine (Pinus contorta var. latifolia and Engelmann spruce/subalpine fir (Picea engelmannii/Abies lasiocarpa forest stands that burned during summer 2000 in Greater Yellowstone (Wyoming, USA. Using a fully probabilistic spatial process model and Bayesian kriging, the spatial structure of microbial lipid abundance and fungi-to-bacteria ratios were found to be spatially structured within plots two years following fire (for most plots, autocorrelation range varied from 1.5 to 10.5 m. Congruence of spatial patterns among microbial variables, in situ net N mineralization, and cover variables was evident. Stepwise regression resulted in significant models of in situ net N mineralization and included variables describing fungal and bacterial abundance, although explained variance was low (R²<0.29. Unraveling complex spatial patterns of nutrient cycling and the biotic factors that regulate it remains challenging but is critical for explaining post-fire ecosystem function, especially in Greater Yellowstone, which is projected to experience increased fire frequencies by mid 21(st Century.

  14. Land-use and fire drive temporal patterns of soil solution chemistry and nutrient fluxes.

    Science.gov (United States)

    Potthast, Karin; Meyer, Stefanie; Crecelius, Anna C; Schubert, Ulrich S; Tischer, Alexander; Michalzik, Beate

    2017-12-15

    Land-use type and ecosystem disturbances are important drivers for element cycling and bear the potential to modulate soil processes and hence ecosystem functions. To better understand the effect of such drivers on the magnitude and temporal patterns of organic matter (OM) and associated nutrient fluxes in soils, continuous flux monitoring is indispensable but insufficiently studied yet. We conducted a field study to elucidate the impact of land-use and surface fires on OM and nutrient fluxes with soil solution regarding seasonal and temporal patterns analyzing short (Linear mixed model analyses exhibited that mean annual DOM and POM fluxes did not differ between the two land-use types, but were subjected to strong seasonal patterns. Fire disturbance significantly lowered the annual soil solution pH in both land-uses and increased water fluxes, while DOC fluxes remained unaffected. A positive response of POC and S to fire was limited to short-term effects, while amplified particulate and dissolved nitrogen fluxes were observed in the longer run and co-ocurred with accelerated Ca and Mg fluxes. In summary, surface fires generated stronger effects on element fluxes than the land-use. Fire-induced increases in POM fluxes suggest that the particulate fraction represent a major pathway of OM translocation into the subsoil and beyond. With regard to ecosystem functions, pasture ecosystems were less prone to the risk of nutrient losses following fire events than the forest. In pastures, fire-induced base cation export may accelerate soil acidification, consequently exhausting soil buffer systems and thus may reduce the resilience to acidic depositions and disturbances. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Calcium-Induced calcium release during action potential firing in developing inner hair cells.

    Science.gov (United States)

    Iosub, Radu; Avitabile, Daniele; Grant, Lisa; Tsaneva-Atanasova, Krasimira; Kennedy, Helen J

    2015-03-10

    In the mature auditory system, inner hair cells (IHCs) convert sound-induced vibrations into electrical signals that are relayed to the central nervous system via auditory afferents. Before the cochlea can respond to normal sound levels, developing IHCs fire calcium-based action potentials that disappear close to the onset of hearing. Action potential firing triggers transmitter release from the immature IHC that in turn generates experience-independent firing in auditory neurons. These early signaling events are thought to be essential for the organization and development of the auditory system and hair cells. A critical component of the action potential is the rise in intracellular calcium that activates both small conductance potassium channels essential during membrane repolarization, and triggers transmitter release from the cell. Whether this calcium signal is generated by calcium influx or requires calcium-induced calcium release (CICR) is not yet known. IHCs can generate CICR, but to date its physiological role has remained unclear. Here, we used high and low concentrations of ryanodine to block or enhance CICR to determine whether calcium release from intracellular stores affected action potential waveform, interspike interval, or changes in membrane capacitance during development of mouse IHCs. Blocking CICR resulted in mixed action potential waveforms with both brief and prolonged oscillations in membrane potential and intracellular calcium. This mixed behavior is captured well by our mathematical model of IHC electrical activity. We perform two-parameter bifurcation analysis of the model that predicts the dependence of IHCs firing patterns on the level of activation of two parameters, the SK2 channels activation and CICR rate. Our data show that CICR forms an important component of the calcium signal that shapes action potentials and regulates firing patterns, but is not involved directly in triggering exocytosis. These data provide important insights

  16. Control of clustered action potential firing in a mathematical model of entorhinal cortex stellate cells.

    Science.gov (United States)

    Tait, Luke; Wedgwood, Kyle; Tsaneva-Atanasova, Krasimira; Brown, Jon T; Goodfellow, Marc

    2018-04-11

    The entorhinal cortex is a crucial component of our memory and spatial navigation systems and is one of the first areas to be affected in dementias featuring tau pathology, such as Alzheimer's disease and frontotemporal dementia. Electrophysiological recordings from principle cells of medial entorhinal cortex (layer II stellate cells, mEC-SCs) demonstrate a number of key identifying properties including subthreshold oscillations in the theta (4-12 Hz) range and clustered action potential firing. These single cell properties are correlated with network activity such as grid firing and coupling between theta and gamma rhythms, suggesting they are important for spatial memory. As such, experimental models of dementia have revealed disruption of organised dorsoventral gradients in clustered action potential firing. To better understand the mechanisms underpinning these different dynamics, we study a conductance based model of mEC-SCs. We demonstrate that the model, driven by extrinsic noise, can capture quantitative differences in clustered action potential firing patterns recorded from experimental models of tau pathology and healthy animals. The differential equation formulation of our model allows us to perform numerical bifurcation analyses in order to uncover the dynamic mechanisms underlying these patterns. We show that clustered dynamics can be understood as subcritical Hopf/homoclinic bursting in a fast-slow system where the slow sub-system is governed by activation of the persistent sodium current and inactivation of the slow A-type potassium current. In the full system, we demonstrate that clustered firing arises via flip bifurcations as conductance parameters are varied. Our model analyses confirm the experimentally suggested hypothesis that the breakdown of clustered dynamics in disease occurs via increases in AHP conductance. Copyright © 2018. Published by Elsevier Ltd.

  17. The effect of firing temperature profiles for the high efficiency of crystalline Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Taeyoung; Kim, Sungchul; Kyung, Dohyeon; Jung, Woowon; Kim, Sunyong; Lee, Yongwoo; Kim, Youngkuk; Jang, Kyungsoo; Jung, Sungwook; Shin, Myungchul [School of Information and Communication Engineering, Sungkyunkwan University (SKKU), Suwon 440-746 (Korea); Yi, Junsin [School of Information and Communication Engineering, Sungkyunkwan University (SKKU), Suwon 440-746 (Korea); Department of Energy Science, Sungkyunkwan University (SKKU), Suwon 440-746 (Korea)

    2010-05-15

    In the mass production of crystalline Si solar cell, metallization is a very important process because it strongly affects various properties of the solar cell, such as I{sub sc}, V{sub oc}, R{sub s}, R{sub sh}, and FF. However, it is not easy to optimize the firing process because it has to be changed with the diffusion process. In this research, we examined the influence of firing conditions on different R{sub sheet} emitters by varying the sheet resistance from 30 to 60 {omega}/sq. The peak temperature and ramp-up rate during the firing process were varied by changing belt speeds and were also varied by changing the temperature settings in different belt furnace zones. As the grid pattern of the front electrode has a significant influence on R{sub s} and FF, we optimized the front grid pattern for each R{sub sheet} emitter. With an increase in the R{sub sheet} of the emitters, V{sub oc} was slightly decreased, as the dopant concentration decreased in the emitter. However, I{sub sc} was increased to a higher degree, which was ascribed to the improvement of blue-response and the reduction of recombination in the front surface. For the same R{sub sheet} of emitters, BSF layers and ohmic contacts were established distinctly at the faster firing condition, which led to a V{sub oc} of around 622 mV and FF of 80.6% by Suns-V{sub oc} measurement. Using the result, we were able to obtain an optimized firing process window for improving V{sub oc} and FF with different R{sub sheet} emitters. These optimized conditions can be applied to the mass production of crystalline Si solar cells. (author)

  18. Vasopressin regularizes the phasic firing pattern of rat hypothalamic magnocellular vasopressin neurons.

    Science.gov (United States)

    Gouzènes, L; Desarménien, M G; Hussy, N; Richard, P; Moos, F C

    1998-03-01

    Vasopressin (AVP) magnocellular neurons of hypothalamic nuclei express specific phasic firing (successive periods of activity and silence), which conditions the mode of neurohypophyseal vasopression release. In situations favoring plasmatic secretion of AVP, the hormone is also released at the somatodendritic level, at which it is believed to modulate the activity of AVP neurons. We investigated the nature of this autocontrol by testing the effects of juxtamembrane applications of AVP on the extracellular activity of presumed AVP neurons in paraventricular and supraoptic nuclei of anesthetized rats. AVP had three effects depending on the initial firing pattern: (1) excitation of faintly active neurons (periods of activity of <10 sec), which acquired or reinforced their phasic pattern; (2) inhibition of quasi-continuously active neurons (periods of silences of <10 sec), which became clearly phasic; and (3) no effect on neurons already showing an intermediate phasic pattern (active and silent periods of 10-30 sec). Consequently, AVP application resulted in a narrower range of activity patterns of the population of AVP neurons, with a Gaussian distribution centered around a mode of 57% of time in activity, indicating a homogenization of the firing pattern. The resulting phasic pattern had characteristics close to those established previously for optimal release of AVP from neurohypophyseal endings. These results suggest a new role for AVP as an optimizing factor that would foster the population of AVP neurons to discharge with a phasic pattern known to be most efficient for hormone release.

  19. Landscape-scale patterns of fire and drought on the high plains, USA

    Science.gov (United States)

    Paulette Ford; Charles Jackson; Matthew Reeves; Benjamin Bird; Dave Turner

    2015-01-01

    We examine 31 years (1982-2012) of temperature, precipitation and natural wildfire occurrence data for Federal and Tribal lands to determine landscape-scale patterns of drought and fire on the southern and central High Plains of the western United States. The High Plains states of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas and...

  20. Shoulder muscle firing patterns during the windmill softball pitch.

    Science.gov (United States)

    Maffet, M W; Jobe, F W; Pink, M M; Brault, J; Mathiyakom, W

    1997-01-01

    The purpose of this study was to describe the activity of eight shoulder muscles during the windmill fast-pitch softball throw. Ten collegiate female pitchers were analyzed with intramuscular electromyography, high-speed cinematography, and motion analysis. The supraspinatus muscle fired maximally during arm elevation from the 6 to 3 o'clock position phase, centralizing the humeral head within the glenoid. The posterior deltoid and teres minor muscles acted maximally from the 3 to 12 o'clock position phase to continue arm elevation and externally rotate the humerus. The pectoralis major muscle accelerated the arm from the 12 o'clock position to ball release phase. The serratus anterior muscle characteristically acted to position the scapula for optimal glenohumeral congruency, and the subscapularis muscle functioned as an internal rotator and to protect the anterior capsule. Although the windmill softball pitch is overtly different from the baseball pitch, several surprising similarities were revealed. The serratus anterior and pectoralis major muscles work in synchrony and seem to have similar functions in both pitches. Although the infraspinatus and teres minor muscles are both posterior cuff muscles, they are characteristically uncoupled during the 6 to 3 o'clock position phase, with the infraspinatus muscle acting more independently below 90 degrees. Subscapularis muscle activity seems important in dynamic anterior glenohumeral stabilization and as an internal rotator in both the baseball and softball throws.

  1. Changing patterns of fire occurrence in proximity to forest edges, roads and rivers between NW Amazonian countries

    Directory of Open Access Journals (Sweden)

    D. Armenteras

    2017-06-01

    Full Text Available Tropical forests in NW Amazonia are highly threatened by the expansion of the agricultural frontier and subsequent deforestation. Fire is used, both directly and indirectly, in Brazilian Amazonia to propagate deforestation and increase forest accessibility. Forest fragmentation, a measure of forest degradation, is also attributed to fire occurrence in the tropics. However, outside the Brazilian Legal Amazonia the role of fire in increasing accessibility and forest fragmentation is less explored. In this study, we compared fire regimes in five countries that share this tropical biome in the most north-westerly part of the Amazon Basin (Venezuela, Colombia, Ecuador, Peru and Brazil. We analysed spatial differences in the timing of peak fire activity and in relation to proximity to roads and rivers using 12 years of MODIS active fire detections. We also distinguished patterns of fire in relation to forest fragmentation by analysing fire distance to the forest edge as a measure of fragmentation for each country. We found significant hemispheric differences in peak fire occurrence with the highest number of fires in the south in 2005 vs. 2007 in the north. Despite this, both hemispheres are equally affected by fire. We also found difference in peak fire occurrence by country. Fire peaked in February in Colombia and Venezuela, whereas it peaked in September in Brazil and Peru, and finally Ecuador presented two fire peaks in January and October. We confirmed the relationship between fires and forest fragmentation for all countries and also found significant differences in the distance between the fire and the forest edge for each country. Fires were associated with roads and rivers in most countries. These results can inform land use planning at the regional, national and subnational scales to minimize the contribution of road expansion and subsequent access to the Amazonian natural resources to fire occurrence and the associated deforestation and

  2. Changing patterns of fire occurrence in proximity to forest edges, roads and rivers between NW Amazonian countries

    Science.gov (United States)

    Armenteras, Dolors; Barreto, Joan Sebastian; Tabor, Karyn; Molowny-Horas, Roberto; Retana, Javier

    2017-06-01

    Tropical forests in NW Amazonia are highly threatened by the expansion of the agricultural frontier and subsequent deforestation. Fire is used, both directly and indirectly, in Brazilian Amazonia to propagate deforestation and increase forest accessibility. Forest fragmentation, a measure of forest degradation, is also attributed to fire occurrence in the tropics. However, outside the Brazilian Legal Amazonia the role of fire in increasing accessibility and forest fragmentation is less explored. In this study, we compared fire regimes in five countries that share this tropical biome in the most north-westerly part of the Amazon Basin (Venezuela, Colombia, Ecuador, Peru and Brazil). We analysed spatial differences in the timing of peak fire activity and in relation to proximity to roads and rivers using 12 years of MODIS active fire detections. We also distinguished patterns of fire in relation to forest fragmentation by analysing fire distance to the forest edge as a measure of fragmentation for each country. We found significant hemispheric differences in peak fire occurrence with the highest number of fires in the south in 2005 vs. 2007 in the north. Despite this, both hemispheres are equally affected by fire. We also found difference in peak fire occurrence by country. Fire peaked in February in Colombia and Venezuela, whereas it peaked in September in Brazil and Peru, and finally Ecuador presented two fire peaks in January and October. We confirmed the relationship between fires and forest fragmentation for all countries and also found significant differences in the distance between the fire and the forest edge for each country. Fires were associated with roads and rivers in most countries. These results can inform land use planning at the regional, national and subnational scales to minimize the contribution of road expansion and subsequent access to the Amazonian natural resources to fire occurrence and the associated deforestation and carbon emissions.

  3. Mid-term successional patterns after fire of mixed pine oak forests in NE Spain

    Science.gov (United States)

    Gracia, Marc; Retana, Javier; Roig, Pere

    2002-12-01

    This study analyzes the factors affecting the current variability in density and age and size structure of mixed pine-oak forests of Pinus nigra and Quercus faginea in Central Catalonia (NE Spain), 37 years after a wildfire. The objective is to determine whether different post-disturbance responses may be obtained from the same pre-fire community and which factors can determine these different potential responses. The two factors analyzed were the distance to the unburned forest and site conditions (represented in this case by different aspects). The response of pines and oaks was different to the pattern expected for the Mediterranean Basin. Oaks resprouted immediately from stools already present before the fire and dominated during the first years, independent of both disturbance and site conditions. Pines established later, and their response depended on both factors: pine density decreased sharply from the forest edge to the burned area, and the number of pines was also higher in the more mesic than in the more xeric conditions. The age structure analysis for pines and oaks in the different aspects also revealed site-dependent rates of succession manifested by initial differences in post-fire establishment. In mesic plots, the establishment of pines occurred quite early, while in xeric plots, pine recruitment was delayed several years. These different patterns of post-fire recovery have led to pine dominance in more mesic sites and codominance of pines and oaks in more xeric ones, suggesting that different mid-term post-fire patterns can be identified for the same pre-fire forest type, depending on variations in environmental conditions.

  4. Modeling the differentiation of A- and C-type baroreceptor firing patterns

    DEFF Research Database (Denmark)

    Sturdy, Jacob; Ottesen, Johnny T.; Olufsen, Mette

    2017-01-01

    The baroreceptor neurons serve as the primary transducers of blood pressure for the autonomic nervous system and are thus critical in enabling the body to respond effectively to changes in blood pressure. These neurons can be separated into two types (A and C) based on the myelination...... of their axons and their distinct firing patterns elicited in response to specific pressure stimuli. This study has developed a comprehensive model of the afferent baroreceptor discharge built on physiological knowledge of arterial wall mechanics, firing rate responses to controlled pressure stimuli, and ion...

  5. Remote Sensing Techniques in Monitoring Post-Fire Effects and Patterns of Forest Recovery in Boreal Forest Regions: A Review

    Directory of Open Access Journals (Sweden)

    Thuan Chu

    2013-12-01

    Full Text Available The frequency and severity of forest fires, coupled with changes in spatial and temporal precipitation and temperature patterns, are likely to severely affect the characteristics of forest and permafrost patterns in boreal eco-regions. Forest fires, however, are also an ecological factor in how forest ecosystems form and function, as they affect the rate and characteristics of tree recruitment. A better understanding of fire regimes and forest recovery patterns in different environmental and climatic conditions will improve the management of sustainable forests by facilitating the process of forest resilience. Remote sensing has been identified as an effective tool for preventing and monitoring forest fires, as well as being a potential tool for understanding how forest ecosystems respond to them. However, a number of challenges remain before remote sensing practitioners will be able to better understand the effects of forest fires and how vegetation responds afterward. This article attempts to provide a comprehensive review of current research with respect to remotely sensed data and methods used to model post-fire effects and forest recovery patterns in boreal forest regions. The review reveals that remote sensing-based monitoring of post-fire effects and forest recovery patterns in boreal forest regions is not only limited by the gaps in both field data and remotely sensed data, but also the complexity of far-northern fire regimes, climatic conditions and environmental conditions. We expect that the integration of different remotely sensed data coupled with field campaigns can provide an important data source to support the monitoring of post-fire effects and forest recovery patterns. Additionally, the variation and stratification of pre- and post-fire vegetation and environmental conditions should be considered to achieve a reasonable, operational model for monitoring post-fire effects and forest patterns in boreal regions.

  6. A spiking network model of cerebellar Purkinje cells and molecular layer interneurons exhibiting irregular firing

    Directory of Open Access Journals (Sweden)

    William eLennon

    2014-12-01

    Full Text Available While the anatomy of the cerebellar microcircuit is well studied, how it implements cerebellar function is not understood. A number of models have been proposed to describe this mechanism but few emphasize the role of the vast network Purkinje cells (PKJs form with the molecular layer interneurons (MLIs – the stellate and basket cells. We propose a model of the MLI-PKJ network composed of simple spiking neurons incorporating the major anatomical and physiological features. In computer simulations, the model reproduces the irregular firing patterns observed in PKJs and MLIs in vitro and a shift toward faster, more regular firing patterns when inhibitory synaptic currents are blocked. In the model, the time between PKJ spikes is shown to be proportional to the amount of feedforward inhibition from an MLI on average. The two key elements of the model are: (1 spontaneously active PKJs and MLIs due to an endogenous depolarizing current, and (2 adherence to known anatomical connectivity along a parasagittal strip of cerebellar cortex. We propose this model to extend previous spiking network models of the cerebellum and for further computational investigation into the role of irregular firing and MLIs in cerebellar learning and function.

  7. Remotely-sensed active fire data for protected area management: eight-year patterns in the Manas National Park, India.

    Science.gov (United States)

    Takahata, Chihiro; Amin, Rajan; Sarma, Pranjit; Banerjee, Gitanjali; Oliver, William; Fa, John E

    2010-02-01

    The Terai-Duar savanna and grasslands, which once extended along most of the Himalayan foothills, now only remain in a number of protected areas. Within these localities, grassland burning is a major issue, but data on frequency and distribution of fires are limited. Here, we analysed the incidence of active fires, which only occur during the dry season (Nov.-Mar.), within a significant area of Terai grasslands: the Manas National Park (MNP), India. We obtained locations of 781 fires during the 2000-2008 dry seasons, from the Fire Information for Resource Management System (FIRMS) that delivers global MODIS hotspot/fire locations using remote sensing and GIS technologies. Annual number of fires rose significantly from around 20 at the start of the study period to over 90 after 2002, with most (85%) detected between December and January. Over half of the fires occurred in tall grasslands, but fire density was highest in wetland and riverine vegetation, dry at the time. Most burning took place near rivers, roads and the park boundary, suggesting anthropogenic origins. A kernel density map of all recorded fires indicated three heavily burnt areas in the MNP, all within the tall grasslands. Our study demonstrates, despite some technical caveats linked to fire detection technology, which is improving, that remote fire data can be a practical tool in understanding fire concentration and burning temporal patterns in highly vulnerable habitats, useful in guiding management.

  8. The use of satellite data for monitoring temporal and spatial patterns of fire: a comprehensive review

    Science.gov (United States)

    Lasaponara, R.

    2009-04-01

    fire regimes from Earth observation data Global Change Biology vo. 14. doi: 10.1111/j.1365-2486.2008.01585.x 1-15, Chuvieco E., P. Englefield, Alexander P. Trishchenko, Yi Luo Generation of long time series of burn area maps of the boreal forest from NOAA-AVHRR composite data. Remote Sensing of Environment, Volume 112, Issue 5, 15 May 2008, Pages 2381-2396 Chuvieco Emilio 2006, Remote Sensing of Forest Fires: Current limitations and future prospects in Observing Land from Space: Science, Customers and Technology, Advances in Global Change Research Vol. 4 pp 47-51 De Santis A., E. Chuvieco Burn severity estimation from remotely sensed data: Performance of simulation versus empirical models, Remote Sensing of Environment, Volume 108, Issue 4, 29 June 2007, Pages 422-435. De Santis A., E. Chuvieco, Patrick J. Vaughan, Short-term assessment of burn severity using the inversion of PROSPECT and GeoSail models, Remote Sensing of Environment, Volume 113, Issue 1, 15 January 2009, Pages 126-136 García M., E. Chuvieco, H. Nieto, I. Aguado Combining AVHRR and meteorological data for estimating live fuel moisture content Remote Sensing of Environment, Volume 112, Issue 9, 15 September 2008, Pages 3618-3627 Ichoku C., L. Giglio, M. J. Wooster, L. A. Remer Global characterization of biomass-burning patterns using satellite measurements of fire radiative energy. Remote Sensing of Environment, Volume 112, Issue 6, 16 June 2008, Pages 2950-2962. Lasaponara R. and Lanorte, On the capability of satellite VHR QuickBird data for fuel type characterization in fragmented landscape Ecological Modelling Volume 204, Issues 1-2, 24 May 2007, Pages 79-84 Lasaponara R., A. Lanorte, S. Pignatti,2006 Multiscale fuel type mapping in fragmented ecosystems: preliminary results from Hyperspectral MIVIS and Multispectral Landsat TM data, Int. J. Remote Sens., vol. 27 (3) pp. 587-593. Lasaponara R., V. Cuomo, M. F. Macchiato, and T. Simoniello, 2003 .A self-adaptive algorithm based on AVHRR multitemporal

  9. Rootstock-regulated gene expression patterns associated with fire blight resistance in apple

    Directory of Open Access Journals (Sweden)

    Jensen Philip J

    2012-01-01

    Full Text Available Abstract Background Desirable apple varieties are clonally propagated by grafting vegetative scions onto rootstocks. Rootstocks influence many phenotypic traits of the scion, including resistance to pathogens such as Erwinia amylovora, which causes fire blight, the most serious bacterial disease of apple. The purpose of the present study was to quantify rootstock-mediated differences in scion fire blight susceptibility and to identify transcripts in the scion whose expression levels correlated with this response. Results Rootstock influence on scion fire blight resistance was quantified by inoculating three-year old, orchard-grown apple trees, consisting of 'Gala' scions grafted to a range of rootstocks, with E. amylovora. Disease severity was measured by the extent of shoot necrosis over time. 'Gala' scions grafted to G.30 or MM.111 rootstocks showed the lowest rates of necrosis, while 'Gala' on M.27 and B.9 showed the highest rates of necrosis. 'Gala' scions on M.7, S.4 or M.9F56 had intermediate necrosis rates. Using an apple DNA microarray representing 55,230 unique transcripts, gene expression patterns were compared in healthy, un-inoculated, greenhouse-grown 'Gala' scions on the same series of rootstocks. We identified 690 transcripts whose steady-state expression levels correlated with the degree of fire blight susceptibility of the scion/rootstock combinations. Transcripts known to be differentially expressed during E. amylovora infection were disproportionately represented among these transcripts. A second-generation apple microarray representing 26,000 transcripts was developed and was used to test these correlations in an orchard-grown population of trees segregating for fire blight resistance. Of the 690 transcripts originally identified using the first-generation array, 39 had expression levels that correlated with fire blight resistance in the breeding population. Conclusions Rootstocks had significant effects on the fire blight

  10. Pattern recognition monitoring of PEM fuel cell

    Science.gov (United States)

    Meltser, Mark Alexander

    1999-01-01

    The CO-concentration in the H.sub.2 feed stream to a PEM fuel cell stack is monitored by measuring current and voltage behavior patterns from an auxiliary cell attached to the end of the stack. The auxiliary cell is connected to the same oxygen and hydrogen feed manifolds that supply the stack, and discharges through a constant load. Pattern recognition software compares the current and voltage patterns from the auxiliary cell to current and voltage signature determined from a reference cell similar to the auxiliary cell and operated under controlled conditions over a wide range of CO-concentrations in the H.sub.2 fuel stream.

  11. Dynamical mechanisms for sensitive response of aperiodic firing cells to external stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Xie Yong E-mail: xie813@263.net; Xu Jianxue; Hu Sanjue; Kang Yanmei; Yang Hongjun; Duan Yubin

    2004-10-01

    An interesting phenomenon that aperiodic firing neurons have a higher sensitivity to drugs than periodic firing neurons have been reported for the chronically compressed dorsal root ganglion neurons in rats. In this study, the dynamical mechanisms for such a phenomenon are uncovered from the viewpoint of dynamical systems theory. We use the Rose-Hindmarsh neuron model to illustrate our opinions. Periodic orbit theory is introduced to characterize the dynamical behavior of aperiodic firing neurons. It is considered that bifurcations, crises and sensitive dependence of chaotic motions on control parameters can be the underlying mechanisms. And then, a similar analysis is applied to the modified Chay model describing the firing behavior of pancreatic beta cells. The same dynamical mechanisms can be obtained underlying that aperiodic firing cells are more sensitive to external stimulation than periodic firing ones. As a result, we conjecture that sensitive response of aperiodic firing cells to external stimulation is a universal property of excitable cells.

  12. Landscape patterns of montane forest age structure relative to fire history at Cheesman Lake in the Colorado Front Range

    Science.gov (United States)

    Laurie S. Huckaby; Merrill R. Kaufmann; Jason M. Stoker; Paula J. Fornwalt

    2001-01-01

    Lack of Euro-American disturbance, except fire suppression, has preserved the patterns of forest structure that resulted from the presettlement disturbance regime in a ponderosa pine/Douglas-fir landscape at Cheesman Lake in the Colorado Front Range. A mixed-severity fire regime and variable timing of tree recruitment created a heterogeneous forest age structure with...

  13. Striatal fast-spiking interneurons: from firing patterns to postsynaptic impact

    Directory of Open Access Journals (Sweden)

    Andreas eKlaus

    2011-07-01

    Full Text Available In the striatal microcircuit, fast-spiking (FS interneurons have an important role in mediating inhibition onto neighboring medium spiny (MS projection neurons. In this study, we combined computational modeling with in vitro and in vivo electrophysiological measurements to investigate FS cells in terms of their discharge properties and their synaptic efficacies onto MS neurons. In vivo firing of striatal FS interneurons is characterized by a high firing variability. It is not known, however, if this variability results from the input that FS cells receive, or if it is promoted by the stuttering spike behavior of these neurons. Both our model and measurements in vitro show that FS neurons that exhibit random stuttering discharge in response to steady depolarization, do not show the typical stuttering behavior when they receive fluctuating input. Importantly, our model predicts that electrically coupled FS cells show substantial spike synchronization only when they are in the stuttering regime. Therefore, together with the lack of synchronized firing of striatal FS interneurons that has been reported in vivo, these results suggest that neighboring FS neurons are not in the stuttering regime simultaneously and that in vivo FS firing variability is more likely determined by the input fluctuations. Furthermore, the variability in FS firing is translated to variability in the postsynaptic amplitudes in MS neurons due to the strong synaptic depression of the FS-to-MS synapse. Our results support the idea that these synapses operate over a wide range from strongly depressed to almost fully recovered. The strong inhibitory effects that FS cells can impose on their postsynaptic targets, and the fact that the FS-to-MS synapse model showed substantial depression over extended periods of time might indicate the importance of cooperative effects of multiple presynaptic FS interneurons and the precise orchestration of their activity.

  14. The relationship between landscape patterns and human-caused fire occurrence in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Castafreda-Aumedes, S.; Garcia-Martin, A.; Vega-Garcia, C.

    2013-05-01

    Aim of study: Human settlements and activities have completely modified landscape structure in the Mediterranean region. Vegetation patterns show the interactions between human activities and natural processes on the territory, and allow understanding historical ecological processes and socioeconomic factors. The arrangement of land uses in the rural landscape can be perceived as a proxy for human activities that often lead to the use, and escape, of fire, the most important disturbance in our forest landscapes. In this context, we tried to predict human-caused fire occurrence in a 5-year period by quantifying landscape patterns. Area of study: This study analyses the Spanish territory included in the Iberian Peninsula and Balearic Islands (497,166 km{sup 2}). Material and Methods: We evaluated spatial pattern applying a set of commonly used landscape ecology metrics to landscape windows of 10x10 sq km (4751 units in the UTM grid) overlaid on the Forest Map of Spain, MFE200. Main results: The best logistic regression model obtained included Shannon's Diversity Index, Mean Patch Edge and Mean Shape Index as explicative variables and the global percentage of correct predictions was 66.3 %. Research highlights: Our results suggested that the highest probability of fire occurrence at that time was associated with areas with a greater diversity of land uses and with more compact patches with fewer edges. (Author) 58 refs.

  15. The Chronotron: A Neuron That Learns to Fire Temporally Precise Spike Patterns

    Science.gov (United States)

    Florian, Răzvan V.

    2012-01-01

    In many cases, neurons process information carried by the precise timings of spikes. Here we show how neurons can learn to generate specific temporally precise output spikes in response to input patterns of spikes having precise timings, thus processing and memorizing information that is entirely temporally coded, both as input and as output. We introduce two new supervised learning rules for spiking neurons with temporal coding of information (chronotrons), one that provides high memory capacity (E-learning), and one that has a higher biological plausibility (I-learning). With I-learning, the neuron learns to fire the target spike trains through synaptic changes that are proportional to the synaptic currents at the timings of real and target output spikes. We study these learning rules in computer simulations where we train integrate-and-fire neurons. Both learning rules allow neurons to fire at the desired timings, with sub-millisecond precision. We show how chronotrons can learn to classify their inputs, by firing identical, temporally precise spike trains for different inputs belonging to the same class. When the input is noisy, the classification also leads to noise reduction. We compute lower bounds for the memory capacity of chronotrons and explore the influence of various parameters on chronotrons' performance. The chronotrons can model neurons that encode information in the time of the first spike relative to the onset of salient stimuli or neurons in oscillatory networks that encode information in the phases of spikes relative to the background oscillation. Our results show that firing one spike per cycle optimizes memory capacity in neurons encoding information in the phase of firing relative to a background rhythm. PMID:22879876

  16. The chronotron: a neuron that learns to fire temporally precise spike patterns.

    Directory of Open Access Journals (Sweden)

    Răzvan V Florian

    Full Text Available In many cases, neurons process information carried by the precise timings of spikes. Here we show how neurons can learn to generate specific temporally precise output spikes in response to input patterns of spikes having precise timings, thus processing and memorizing information that is entirely temporally coded, both as input and as output. We introduce two new supervised learning rules for spiking neurons with temporal coding of information (chronotrons, one that provides high memory capacity (E-learning, and one that has a higher biological plausibility (I-learning. With I-learning, the neuron learns to fire the target spike trains through synaptic changes that are proportional to the synaptic currents at the timings of real and target output spikes. We study these learning rules in computer simulations where we train integrate-and-fire neurons. Both learning rules allow neurons to fire at the desired timings, with sub-millisecond precision. We show how chronotrons can learn to classify their inputs, by firing identical, temporally precise spike trains for different inputs belonging to the same class. When the input is noisy, the classification also leads to noise reduction. We compute lower bounds for the memory capacity of chronotrons and explore the influence of various parameters on chronotrons' performance. The chronotrons can model neurons that encode information in the time of the first spike relative to the onset of salient stimuli or neurons in oscillatory networks that encode information in the phases of spikes relative to the background oscillation. Our results show that firing one spike per cycle optimizes memory capacity in neurons encoding information in the phase of firing relative to a background rhythm.

  17. Fire Tests on E-vehicle Battery Cells and Packs.

    Science.gov (United States)

    Sturk, David; Hoffmann, Lars; Ahlberg Tidblad, Annika

    2015-01-01

    The purpose of this study was to investigate the effects of abuse conditions, including realistic crash scenarios, on Li ion battery systems in E-vehicles in order to develop safe practices and priorities when responding to accidents involving E-vehicles. External fire tests using a single burning item equipment were performed on commercial Li ion battery cells and battery packs for electric vehicle (E-vehicle) application. The 2 most common battery cell technologies were tested: Lithium iron phosphate (LFP) and mixed transition metal oxide (lithium nickel manganese cobalt oxide, NMC) cathodes against graphite anodes, respectively. The cell types investigated were "pouch" cells, with similar physical dimensions, but the NMC cells have double the electric capacity of the LFP cells due to the higher energy density of the NMC chemistry, 7 and 14 Ah, respectively. Heat release rate (HRR) data and concentrations of toxic gases were acquired by oxygen consumption calorimetry and Fourier transform infrared spectroscopy (FTIR), respectively. The test results indicate that the state of charge (SOC) affects the HRR as well as the amount of toxic hydrogen fluoride (HF) gas formed during combustion. A larger number of cells increases the amount of HF formed per cell. There are significant differences in response to the fire exposure between the NMC and LFP cells in this study. The LFP cells generate a lot more HF per cell, but the overall reactivity of the NMC cells is higher. However, the total energy released by both batteries during combustion was independent of SOC, which indicates that the electric energy content of the test object contributes to the activation energy of the thermal and heat release process, whereas the chemical energy stored in the materials is the main source of thermal energy in the batteries. The results imply that it is difficult to draw conclusions about higher order system behavior with respect to HF emissions based on data from tests on single

  18. A Simulation Study on the Effects of Dendritic Morphology on Layer V Prefontal Pyramidal Cell Firing Behavior

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    Maria ePsarrou

    2014-09-01

    Full Text Available Pyramidal cells, the most abundant neurons in neocortex, exhibit significant structural variability across different brain areas and layers in different species. Moreover, in response to a somatic step current, these cells display a range of firing behaviors, the most common being (1 repetitive action potentials (Regular Spiking - RS, and (2 an initial cluster of 2-5 action potentials with short ISIs followed by single spikes (Intrinsic Bursting - IB. A correlation between firing behavior and dendritic morphology has recently been reported. In this work we use computational modeling to investigate quantitatively the effects of the basal dendritic tree morphology on the firing behavior of 112 three-dimensional reconstructions of layer V PFC rat pyramidal cells. Particularly, we focus on how different morphological (diameter, total length, volume and branch number and passive (Mean Electrotonic Path length features of basal dendritic trees shape somatic firing when the spatial distribution of ionic mechanisms in the basal dendritic trees is uniform or non-uniform. Our results suggest that total length, volume and branch number are the best morphological parameters to discriminate the cells as RS or IB, regardless of the distribution of ionic mechanisms in basal trees. The discriminatory power of total length, volume and branch number remains high in the presence of different apical dendrites. These results suggest that morphological variations in the basal dendritic trees of layer V pyramidal neurons in the PFC influence their firing patterns in a predictive manner and may in turn influence the information processing capabilities of these neurons.

  19. Grid cell hexagonal patterns formed by fast self-organized learning within entorhinal cortex.

    Science.gov (United States)

    Mhatre, Himanshu; Gorchetchnikov, Anatoli; Grossberg, Stephen

    2012-02-01

    Grid cells in the dorsal segment of the medial entorhinal cortex (dMEC) show remarkable hexagonal activity patterns, at multiple spatial scales, during spatial navigation. It has previously been shown how a self-organizing map can convert firing patterns across entorhinal grid cells into hippocampal place cells that are capable of representing much larger spatial scales. Can grid cell firing fields also arise during navigation through learning within a self-organizing map? This article describes a simple and general mathematical property of the trigonometry of spatial navigation which favors hexagonal patterns. The article also develops a neural model that can learn to exploit this trigonometric relationship. This GRIDSmap self-organizing map model converts path integration signals into hexagonal grid cell patterns of multiple scales. GRIDSmap creates only grid cell firing patterns with the observed hexagonal structure, predicts how these hexagonal patterns can be learned from experience, and can process biologically plausible neural input and output signals during navigation. These results support an emerging unified computational framework based on a hierarchy of self-organizing maps for explaining how entorhinal-hippocampal interactions support spatial navigation. Copyright © 2010 Wiley Periodicals, Inc.

  20. Spatial Patterns of Fire Recurrence Using Remote Sensing and GIS in the Brazilian Savanna: Serra do Tombador Nature Reserve, Brazil

    Directory of Open Access Journals (Sweden)

    Gabriel Antunes Daldegan

    2014-10-01

    Full Text Available The Cerrado is the second largest biome in Brazil after the Amazon and is the savanna with the highest biodiversity in the world. Serra Tombador Natural Reserve (STNR is the largest private reserve located in Goiás State, and the fourth largest in the Cerrado biome. The present study aimed to map the burnt areas and to describe the spatial patterns of fire recurrence and its interactions with the classes of land-cover that occurred in STNR and its surroundings in the period between 2001 and 2010. Several Landsat TM images acquired around the months of July, August and September, coinciding with the region’s dry season when fire events intensify, were employed to monitor burnt areas. Fire scars were mapped using the supervised Mahalanobis-distance classifier and further refined using expert visual interpretation. Burnt area patterns were described by spatial landscape metrics. The effects of fire on landscape structure were obtained by comparing results among different land-cover classes, and results summarized in terms of fire history and frequencies. During the years covered by the study, 69% of the areas analyzed had fire events. The year with the largest burnt area was 2004, followed by 2001, 2007 and 2010. Thus, the largest fire events occurred in a 3-year cycle, which is compatible with other areas of the Brazilian savanna. The regions with higher annual probabilities of fire recurrence occur in the buffer zone around the park. The year 2004 also had the highest number of burnt area patches (831. In contrast, the burnt area in 2007 showed the most extensive fires with low number of patches (82. The physiognomies that suffered most fires were the native savanna formations. The study also identified areas where fires are frequently recurrent, highlighting priority areas requiring special attention. Thus, the methodology adopted in this study assists in monitoring and recovery of areas affected by fire over time.

  1. Dense pattern optical multipass cell

    Science.gov (United States)

    Silver, Joel A [Santa Fe, NM

    2009-01-13

    A multiple pass optical cell and method comprising providing a pair of opposed cylindrical mirrors having curved axes with substantially equal focal lengths, positioning an entrance hole for introducing light into the cell and an exit hole for extracting light from the cell, wherein the entrance hole and exit hole are coextensive or non-coextensive, introducing light into the cell through the entrance hole, and extracting light from the cell through the exit hole.

  2. Customized color patterning of photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Campa, Jose Luis; Nielson, Gregory N.; Okandan, Murat; Lentine, Anthony L.; Resnick, Paul J.; Gupta, Vipin P.

    2016-11-15

    Photovoltaic cells and photovoltaic modules, as well as methods of making and using such photovoltaic cells and photovoltaic modules, are disclosed. More particularly, embodiments of the photovoltaic cells selectively reflect visible light to provide the photovoltaic cells with a colorized appearance. Photovoltaic modules combining colorized photovoltaic cells may be used to harvest solar energy while providing a customized appearance, e.g., an image or pattern.

  3. New aspects of firing pattern autocontrol in oxytocin and vasopressin neurones.

    Science.gov (United States)

    Moos, F; Gouzènes, L; Brown, D; Dayanithi, G; Sabatier, N; Boissin, L; Rabié, A; Richard, P

    1998-01-01

    In the rat, oxytocin (OT) and vasopressin (AVP) neurones exhibit specific electrical activities which are controlled by OT and AVP released from soma and dendrites within the magnocellular hypothalamic nuclei. OT enhances amplitude and frequency of suckling-induced bursts, and changes basal firing characteristics: spike patterning becomes very irregular (spike clusters separated by long silences), firing rate is highly variable, oscillating before facilitated bursts. This unstable behaviour which markedly decreases during hyperosmotic stimulation (interrupting bursting) could be a prerequisite for bursting. The effects of AVP depend on the initial phasic pattern of AVP neurones: AVP excites weakly active neurones (increasing burst duration, decreasing silences) and inhibits highly active neurones; neurones with intermediate phasic activity are unaffected. Thus, AVP ensures all AVP neurones discharge with moderate phasic activity (bursts and silences lasting 20-40 s), known to optimise systemic AVP release. V1a-type receptors are involved in AVP actions. In conclusion, OT and AVP control their respective neurones in a complex manner to favour the patterns of activity which are the best suited for an efficient systemic hormone release.

  4. Acute ethanol exposure inhibits silencing of cerebellar Golgi cell firing induced by granule cell axon input

    Directory of Open Access Journals (Sweden)

    Paolo eBotta

    2014-02-01

    Full Text Available Golgi cells (GoCs are specialized interneurons that provide inhibitory input to granule cells in the cerebellar cortex. GoCs are pacemaker neurons that spontaneously fire action potentials, triggering spontaneous inhibitory postsynaptic currents in granule cells and also contributing to the generation tonic GABAA receptor-mediated currents in granule cells. In turn, granule cell axons provide feedback glutamatergic input to GoCs. It has been shown that high frequency stimulation of granule cell axons induces a transient pause in GoC firing in a type 2-metabotropic glutamate receptor (mGluR2-dependent manner. Here, we investigated the effect ethanol on the pause of GoC firing induced by high frequency stimulation of granule cell axons. GoC electrophysiological recordings were performed in parasagittal cerebellar vermis slices from postnatal day 23 to 26 rats. Loose-patch cell-attached recordings revealed that ethanol (40 mM reversibly decreases the pause duration. An antagonist of mGluR2 reduced the pause duration but did not affect the effect of ethanol. Whole-cell voltage-clamp recordings showed that currents evoked by an mGluR2 agonist were not significantly affected by ethanol. Perforated-patch experiments in which hyperpolarizing and depolarizing currents were injected into GoCs demonstrated that there is an inverse relationship between spontaneous firing and pause duration. Slight inhibition of the Na+/K+ pump mimicked the effect of ethanol on pause duration. In conclusion, ethanol reduces the granule cell axon-mediated feedback mechanism by reducing the input responsiveness of GoCs. This would result in a transient increase of GABAA receptor-mediated inhibition of granule cells, limiting information flow at the input stage of the cerebellar cortex.

  5. Spider trait assembly patterns and resilience under fire-induced vegetation change in South Brazilian grasslands.

    Directory of Open Access Journals (Sweden)

    Luciana R Podgaiski

    Full Text Available Disturbances induce changes on habitat proprieties that may filter organism's functional traits thereby shaping the structure and interactions of many trophic levels. We tested if communities of predators with foraging traits dependent on habitat structure respond to environmental change through cascades affecting the functional traits of plants. We monitored the response of spider and plant communities to fire in South Brazilian Grasslands using pairs of burned and unburned plots. Spiders were determined to the family level and described in feeding behavioral and morphological traits measured on each individual. Life form and morphological traits were recorded for plant species. One month after fire the abundance of vegetation hunters and the mean size of the chelicera increased due to the presence of suitable feeding sites in the regrowing vegetation, but irregular web builders decreased due to the absence of microhabitats and dense foliage into which they build their webs. Six months after fire rosette-form plants with broader leaves increased, creating a favourable habitat for orb web builders which became more abundant, while graminoids and tall plants were reduced, resulting in a decrease of proper shelters and microclimate in soil surface to ground hunters which became less abundant. Hence, fire triggered changes in vegetation structure that lead both to trait-convergence and trait-divergence assembly patterns of spiders along gradients of plant biomass and functional diversity. Spider individuals occurring in more functionally diverse plant communities were more diverse in their traits probably because increased possibility of resource exploitation, following the habitat heterogeneity hypothesis. Finally, as an indication of resilience, after twelve months spider communities did not differ from those of unburned plots. Our findings show that functional traits provide a mechanistic understanding of the response of communities to

  6. Spider trait assembly patterns and resilience under fire-induced vegetation change in South Brazilian grasslands.

    Science.gov (United States)

    Podgaiski, Luciana R; Joner, Fernando; Lavorel, Sandra; Moretti, Marco; Ibanez, Sebastien; Mendonça, Milton de S; Pillar, Valério D

    2013-01-01

    Disturbances induce changes on habitat proprieties that may filter organism's functional traits thereby shaping the structure and interactions of many trophic levels. We tested if communities of predators with foraging traits dependent on habitat structure respond to environmental change through cascades affecting the functional traits of plants. We monitored the response of spider and plant communities to fire in South Brazilian Grasslands using pairs of burned and unburned plots. Spiders were determined to the family level and described in feeding behavioral and morphological traits measured on each individual. Life form and morphological traits were recorded for plant species. One month after fire the abundance of vegetation hunters and the mean size of the chelicera increased due to the presence of suitable feeding sites in the regrowing vegetation, but irregular web builders decreased due to the absence of microhabitats and dense foliage into which they build their webs. Six months after fire rosette-form plants with broader leaves increased, creating a favourable habitat for orb web builders which became more abundant, while graminoids and tall plants were reduced, resulting in a decrease of proper shelters and microclimate in soil surface to ground hunters which became less abundant. Hence, fire triggered changes in vegetation structure that lead both to trait-convergence and trait-divergence assembly patterns of spiders along gradients of plant biomass and functional diversity. Spider individuals occurring in more functionally diverse plant communities were more diverse in their traits probably because increased possibility of resource exploitation, following the habitat heterogeneity hypothesis. Finally, as an indication of resilience, after twelve months spider communities did not differ from those of unburned plots. Our findings show that functional traits provide a mechanistic understanding of the response of communities to environmental change

  7. Caenorhabditis elegans vulval cell fate patterning

    International Nuclear Information System (INIS)

    Félix, Marie-Anne

    2012-01-01

    The spatial patterning of three cell fates in a row of competent cells is exemplified by vulva development in the nematode Caenorhabditis elegans. The intercellular signaling network that underlies fate specification is well understood, yet quantitative aspects remain to be elucidated. Quantitative models of the network allow us to test the effect of parameter variation on the cell fate pattern output. Among the parameter sets that allow us to reach the wild-type pattern, two general developmental patterning mechanisms of the three fates can be found: sequential inductions and morphogen-based induction, the former being more robust to parameter variation. Experimentally, the vulval cell fate pattern is robust to stochastic and environmental challenges, and minor variants can be detected. The exception is the fate of the anterior cell, P3.p, which is sensitive to stochastic variation and spontaneous mutation, and is also evolving the fastest. Other vulval precursor cell fates can be affected by mutation, yet little natural variation can be found, suggesting stabilizing selection. Despite this fate pattern conservation, different Caenorhabditis species respond differently to perturbations of the system. In the quantitative models, different parameter sets can reconstitute their response to perturbation, suggesting that network variation among Caenorhabditis species may be quantitative. Network rewiring likely occurred at longer evolutionary scales. (paper)

  8. Histomorphological patterns in osseous rests exposed at fire; Patrones histomorfologicos en restos oseos expuestos al fuego

    Energy Technology Data Exchange (ETDEWEB)

    Medina, C.; Tiesler, V. [Facultad de Ciencias Antropologicas, UADY, 97000 Merida, Yucatan (Mexico); Oliva, A.I.; Quintana, P. [CINVESTAV, IPN Unidad Merida, Depto. Fisica Aplicada, 97310 Merida (Mexico)

    2005-07-01

    Histomorphology as part of morphological research studies bony structure on the tissue level. Its methods are applied in this investigation to evaluate histomorphological impact patterns in heat-exposed bony material, particularly color changes, fissure patterns, volumetric reduction, and changes in the size of Haversian canals. These variables were evaluated in exposed thin sections of porcine long bones, obtained during two experimental series. The first one was conducted under stable thermal conditions in a furnace by measuring heat impact in stepped time (I to S hours) and temperature intervals (200 to 800 C). During a second experimental phase, bony samples were exposed to direct fire in defined time and heat intervals. The treated specimens were then sectioned and microscopically scrutinized. The results presented here were designed to offer new analytical, measurable standards in the investigation of forms of heat exposition of the human body, applicable in forensics and the study of ancient Maya posthumous body treatments. (Author)

  9. Effect of an autapse on the firing pattern transition in a bursting neuron

    Science.gov (United States)

    Wang, Hengtong; Ma, Jun; Chen, Yueling; Chen, Yong

    2014-09-01

    On the basis of the Hindmarsh-Rose (HR) neuron model, the dynamics of electrical activity and the transition of firing patterns induced by three types of autapses have been investigated in detail. The dynamic effect of an autapse is detected by imposing a feedback term with a specific time-delay and autaptic intensity. We found that the delayed autaptic feedback connection switches the electrical activities of the HR neuron among quiescent, periodic and chaotic firing patterns. In the case of an electrical autapse, the transition from a periodic to a chaotic state occurs depending on the specific autaptic intensity and the time-delay. The excitatory chemical autapse plays a positive role in generating and enhancing the chaotic state. A time delay could decrease and suppress the chaotic state in the case of inhibitory chemical self-connections with a proper autaptic intensity. The bifurcation diagram vs. time-delay and autaptic intensity has been extensively studied, and the time series of membrane potentials and the distribution of information entropy have also been calculated to confirm the bifurcation analysis.

  10. Protein and cell patterning for cell-based biosensor applications

    Science.gov (United States)

    Veiseh, Mandana

    Patterned platforms that alternately promote or prevent the attachment of biomolecules promise to advance bio-micro-electro-mechanical systems (Bio-MEMS) and cell-based biosensors (CBBs) for medical diagnostic, therapeutic, and prosthetic applications. When integrated with microelectronic or optical technologies, arrays of cells can be fabricated onto "biochips" to simultaneously process numerous analytes. Among the benefits are rapid and sensitive analysis, portability and ability to obtain functional information from analytes. This integration requires cells to be selectively patterned on platforms composed of more than one material, particularly in an electrode-insulator format. Current cell patterning technologies cannot yet provide effective solutions to patterning cells on desired substrates, largely because most of the techniques pattern cells on substrates of single material. In addition, they generally employ a mechanical device to guide selective protein or cell attachment, which may degrade their biological functionality. The other major challenges, especially in development of CBBs, include long-term cell selectivity and creation of uniform "single-cell" patterns. The central component of this research is to develop novel techniques to pattern multiple and/or single cells with high precision, selectivity, reproducibility, and long-term cell selectivity. First, a novel surface engineering approach was developed to covalently immobilize proteins or peptides on the gold substrates and bio-inert poly(ethylene glycol)-silane molecules on silicon substrates. Next, photolithography and surface engineering were combined to pattern microarrays of cell-adhesive proteins on gold electrodes to mediate cell adhesion. The versatility of this approach for immobilization of various proteins on different types of gold patterns was characterized by florescence microscopy, ToF-SIMS, and AFM. Optical-DIC microscopy illustrated selective attachment of various cells on

  11. Change in sympathetic nerve firing pattern associated with dietary weight loss in the metabolic syndrome

    Directory of Open Access Journals (Sweden)

    Elisabeth Annie Lambert

    2011-08-01

    Full Text Available Sympathetic activation in subjects with the metabolic syndrome (MS plays a role in the pathogenesis of cardiovascular disease development. Diet-induced weight loss decreases sympathetic outflow. However the mechanisms that account for sympathetic inhibition are not known. We sought to provide a detailed description of the sympathetic response to diet by analyzing the firing behavior of single-unit sympathetic nerve fibres. Fourteen subjects (57±2 years, 9 men, 5 females fulfilling ATP III criteria for the MS underwent a 3-month low calorie diet. Metabolic profile, hemodynamic parameters and multi-unit and single unit muscle sympathetic nerve activity (MSNA, microneurography were assessed prior to and at the end of the diet. Patients’ weight dropped from 96±4 to 88±3 kg (P<0.001. This was associated with a decrease in systolic and diastolic blood pressure (-12 ±3 and -5±2 mmHg, P<0.05, and in heart rate (-7±2 bpm, P<0.01 and an improvement in all metabolic parameters (fasting glucose: -0.302.1±0.118 mmol/l, total cholesterol: -0.564±0.164 mmol/l, triglycerides: -0.414±0.137 mmol/l, P<0.05. Multi-unit MSNA decreased from 68±4 to 59±5 bursts per 100 heartbeats (P<0.05. Single-unit MSNA indicated that the firing rate of individual vasoconstrictor fibres decreased from 59±10 to 32±4 spikes per 100 heart beats (P<0.05. The probability of firing decreased from 34±5 to 23±3 % of heartbeats (P<0.05, and the incidence of multiple firing decreased from 14±4 to 6±1 % of heartbeats (P<0.05. Cardiac and sympathetic baroreflex function were significantly improved (cardiac slope: 6.57±0.69 to 9.57±1.20 msec.mmHg-1; sympathetic slope: -3.86±0.34 to -5.05±0.47 bursts per 100 heartbeats.mmHg-1 P<0.05 for both. Hypocaloric diet decreased sympathetic activity and improved hemodynamic and metabolic parameters. The sympathoinhibition associated with weight loss involves marked changes, not only in the rate but also in the firing pattern of

  12. Unusual scintigraphic pattern in sickle cell patients

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, A.M.; Chen, D.C.P.; Siegel, M.E.; Norris, S.L.; Haywood, L.J.

    1989-07-01

    We reviewed the nuclear medicine files of all patients enrolled in the sickle cell disease clinic who had had scans performed within the previous 5 years. We specifically looked for patterns of tracer uptake in these scans that would correlate with the severe anemia and consequent bone marrow hyperactivity of sickle cell patients. Thirty-three patients were included (21 men and 12 women) with a mean age of 26.8 years (range 17-48 years). The appearance of each of these patients' most recent scans was examined in the areas of the distal femurs, the proximal tibias and the distal tibias; a distinct triangular shaped pattern of increased activity was identified in these areas in a majority of patients. Thirty-three patients without sickle cell disease served as age-matched controls. This pattern was seen in 65.1% (95 out of 146 images) of the sickle cell patients' delayed images and 80.4% (82 out of 102 images) of their blood pool images. In contrast, the control patients demonstrated the triangular pattern in none of their blood pool studies (0%) and only 10.9% of their delayed bone images (P<0.001). The mean age of sickle cell patients with this pattern is 25.6 years which was significantly lower than that of those without this pattern (mean=37.5 years, P<0.05). Given the high prevalence of this unique scintigraphic pattern in a group of patients with known accelerated bone marrow function, these findings may be scintigraphic evidence of bone marrow expansion. The patient's age appears to be an important factor in visualization of this pattern.

  13. Different patterns of neuronal activity trigger distinct responses of oligodendrocyte precursor cells in the corpus callosum.

    Directory of Open Access Journals (Sweden)

    Balint Nagy

    2017-08-01

    Full Text Available In the developing and adult brain, oligodendrocyte precursor cells (OPCs are influenced by neuronal activity: they are involved in synaptic signaling with neurons, and their proliferation and differentiation into myelinating glia can be altered by transient changes in neuronal firing. An important question that has been unanswered is whether OPCs can discriminate different patterns of neuronal activity and respond to them in a distinct way. Here, we demonstrate in brain slices that the pattern of neuronal activity determines the functional changes triggered at synapses between axons and OPCs. Furthermore, we show that stimulation of the corpus callosum at different frequencies in vivo affects proliferation and differentiation of OPCs in a dissimilar way. Our findings suggest that neurons do not influence OPCs in "all-or-none" fashion but use their firing pattern to tune the response and behavior of these nonneuronal cells.

  14. Fabrication of microstamps and patterned cell network

    International Nuclear Information System (INIS)

    Seong, Nak Seon; Pak, James Jung Ho; Choi, Ju Hee; Ahn, Dong June; Hwang, Seong Min; Lee, Kyung J.

    2002-01-01

    Elastomeric stamps with micrometer-sized grids are fabricated for building biological cell networks by design. Polymerized polydimethyl-siloxane (PDMS) stamps are cast in a variety of different molds prepared by micro-electro mechanical systems (MEMS) technology. Micro square-grid patterns of 3-aminopropyl triethoxy silane (APS) are successfully imprinted on glass plates, and patterned networks of cardiac cells are obtained as designed. The resulting cellular networks clearly demonstrate that cell attachment and growth are greatly favored on APS-treated thin tracks. Here, we report the technical details related to the fabrication of microstamps, to the stamping procedure, and to the culture method. The potential applications of patterned cellular networks are also discussed

  15. Adaptation in the visual cortex: influence of membrane trajectory and neuronal firing pattern on slow afterpotentials.

    Directory of Open Access Journals (Sweden)

    Vanessa F Descalzo

    Full Text Available The input/output relationship in primary visual cortex neurons is influenced by the history of the preceding activity. To understand the impact that membrane potential trajectory and firing pattern has on the activation of slow conductances in cortical neurons we compared the afterpotentials that followed responses to different stimuli evoking similar numbers of action potentials. In particular, we compared afterpotentials following the intracellular injection of either square or sinusoidal currents lasting 20 seconds. Both stimuli were intracellular surrogates of different neuronal responses to prolonged visual stimulation. Recordings from 99 neurons in slices of visual cortex revealed that for stimuli evoking an equivalent number of spikes, sinusoidal current injection activated a slow afterhyperpolarization of significantly larger amplitude (8.5 ± 3.3 mV and duration (33 ± 17 s than that evoked by a square pulse (6.4 ± 3.7 mV, 28 ± 17 s; p<0.05. Spike frequency adaptation had a faster time course and was larger during plateau (square pulse than during intermittent (sinusoidal depolarizations. Similar results were obtained in 17 neurons intracellularly recorded from the visual cortex in vivo. The differences in the afterpotentials evoked with both protocols were abolished by removing calcium from the extracellular medium or by application of the L-type calcium channel blocker nifedipine, suggesting that the activation of a calcium-dependent current is at the base of this afterpotential difference. These findings suggest that not only the spikes, but the membrane potential values and firing patterns evoked by a particular stimulation protocol determine the responses to any subsequent incoming input in a time window that spans for tens of seconds to even minutes.

  16. Spatial patterns in the effects of fire on savanna vegetation three-dimensional structure.

    Science.gov (United States)

    Levick, Shaun R; Asner, Gregory P; Smit, Izak P J

    2012-12-01

    Spatial variability in the effects of fire on savanna vegetation structure is seldom considered in ecology, despite the inherent heterogeneity of savanna landscapes. Much has been learned about the effects of fire on vegetation structure from long-term field experiments, but these are often of limited spatial extent and do not encompass different hillslope catena elements. We mapped vegetation three-dimensional (3-D) structure over 21 000 ha in nine savanna landscapes (six on granite, three on basalt), each with contrasting long-term fire histories (higher and lower fire frequency), as defined from a combination of satellite imagery and 67 years of management records. Higher fire frequency areas contained less woody canopy cover than their lower fire frequency counterparts in all landscapes, and woody cover reduction increased linearly with increasing difference in fire frequency (r2 = 0.58, P = 0.004). Vegetation height displayed a more heterogeneous response to difference in fire frequency, with taller canopies present in the higher fire frequency areas of the wetter sites. Vegetation 3-D structural differences between areas of higher and lower fire frequency differed between geological substrates and varied spatially across hillslopes. Fire had the greatest relative impact on vegetation structure on nutrient-rich basalt substrates, and it imparted different structural responses upon vegetation in upland, midslope, and lowland topographic positions. These results highlight the complexity of fire vegetation relationships in savanna systems, and they suggest that underlying landscape heterogeneity needs more explicit incorporation into fire management policies.

  17. Altered neuronal firing pattern of the basal ganglia nucleus plays a role in levodopa-induced dyskinesia in patients with Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Xiaoyu eLi

    2015-11-01

    Full Text Available Background: Levodopa therapy alleviates the symptoms of Parkinson's disease (PD, but long-term treatment often leads to motor complications such as levodopa-induced dyskinesia (LID. Aim: To explore the neuronal activity in the basal ganglia nuclei in patients with PD and LID. Methods: Thirty patients with idiopathic PD (age, 55.1±11.0 years; disease duration, 8.7±5.6 years were enrolled between August 2006 and August 2013 at the Xuanwu Hospital, Capital Medical University, China. Their Hoehn and Yahr scores ranged from 2 to 4 and their UPDRS III scores were 28.5±5.2. Fifteen of them had severe LID (UPDRS IV scores of 6.7±1.6. Microelectrode recording was performed in the globus pallidus internus (GPi and subthalamic nucleus (STN during pallidotomy (n=12 or STN deep brain stimulation (DBS; bilateral, n=12; unilateral, n=6. The firing patterns and frequencies of various cell types were analyzed by assessing single cell interspike intervals (ISIs and the corresponding coefficient of variation (CV. Results: A total of 295 neurons were identified from the GPi (n=12 and STN (n=18. These included 26 (8.8% highly grouped discharge, 30 (10.2% low frequency firing, 78 (26.4% rapid tonic discharge, 103 (34.9% irregular activity, and 58 (19.7% tremor-related activity. There were significant differences between the two groups (P<0.05 for neurons with irregular firing, highly irregular cluster-like firing, and low-frequency firing. Conclusion: Altered neuronal activity was observed in the basal ganglia nucleus of GPi and STN, and may play important roles in the pathophysiology of PD and LID.

  18. Cell pattern in adult human corneal endothelium.

    Directory of Open Access Journals (Sweden)

    Carlos H Wörner

    Full Text Available A review of the current data on the cell density of normal adult human endothelial cells was carried out in order to establish some common parameters appearing in the different considered populations. From the analysis of cell growth patterns, it is inferred that the cell aging rate is similar for each of the different considered populations. Also, the morphology, the cell distribution and the tendency to hexagonallity are studied. The results are consistent with the hypothesis that this phenomenon is analogous with cell behavior in other structures such as dry foams and grains in polycrystalline materials. Therefore, its driving force may be controlled by the surface tension and the mobility of the boundaries.

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

    Science.gov (United States)

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

    2011-06-01

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

  20. Comparison of the sensitivity of landscape-fire-succession models to variation in terrain, fuel pattern, climate and weather.

    Science.gov (United States)

    Geoffrey J. Cary; Robert E. Keane; Robert H. Gardner; Sandra Lavorel; Mike D. Flannigan; Ian D. Davies; Chao Li; James M. Lenihan; T. Scott Rupp; Florent. Mouillot

    2006-01-01

    The purpose of this study was to compare the sensitivity of nlodelled area burned to environmental factors across a range of independently-developed landscape-fire-succession models. The sensitivity of area burned to variation in four factors, namely terrain (flat, undulating and mountainous), fuel pattern (finely and coarsely clumped), climate (observed, warmer &...

  1. Fire patterns of South Eastern Queensland in a global context: A review

    Science.gov (United States)

    Philip Le C. F. Stewart; Patrick T. Moss

    2015-01-01

    Fire is an important driver in ecosystem evolution, composition, structure and distribution, and is vital for maintaining ecosystems of the Great Sandy Region (GSR). Charcoal records for the area dating back over 40, 000 years provide evidence of the great changes in vegetation composition, distribution and abundance in the region over time as a result of fire. Fires...

  2. Wildfire and Spatial Patterns in Forests in Northwestern Mexico: The United States Wishes It Had Similar Fire Problems

    Directory of Open Access Journals (Sweden)

    Scott L. Stephens

    2008-12-01

    Full Text Available Knowledge of the ecological effect of wildfire is important to resource managers, especially from forests in which past anthropogenic influences, e.g., fire suppression and timber harvesting, have been limited. Changes to forest structure and regeneration patterns were documented in a relatively unique old-growth Jeffrey pine-mixed conifer forest in northwestern Mexico after a July 2003 wildfire. This forested area has never been harvested and fire suppression did not begin until the 1970s. Fire effects were moderate especially considering that the wildfire occurred at the end of a severe, multi-year (1999-2003 drought. Shrub consumption was an important factor in tree mortality and the dominance of Jeffrey pine increased after fire. The Baja California wildfire enhanced or maintained a patchy forest structure; similar spatial heterogeneity should be included in US forest restoration plans. Most US forest restoration plans include thinning from below to separate tree crowns and attain a narrow range for residual basal area/ha. This essentially produces uniform forest conditions over broad areas that are in strong contrast to the resilient forests in northern Baja California. In addition to producing more spatial heterogeneity in restoration plans of forests that once experienced frequent, low-moderate intensity fire regimes, increased use of US wildfire management options such as wildland fire use as well as appropriate management responses to non-natural ignitions could also be implemented at broader spatial scales to increase the amount of burning in western US forests.

  3. Spatial patterns of two co-occurring savanna and forest tree species in a dense fire-protected savanna fragment

    Directory of Open Access Journals (Sweden)

    Rafael Carvalho da Costa

    Full Text Available ABSTRACT Savanna-forest transition under fire-exclusion could be explained by differential competitive performance of savanna and forest species under shading/fire-exclusion. Aiming to understand strategies related to either habitat affinity, we investigated spatial patterns of a savanna and a forest species in a fire-protected savanna. We predicted that: savanna species would have lower abundance than the forest species due to a restriction in the number of open microsites; segregation of size classes and a trend from clumping to regularity with size for forest species due to absence of microsite limitation and intra-specifc competition; and spatial association and increasing clustering with size for savanna species due to microsite limitation. To test these predictions, we described spatial patterns of plants in two size classes in three plots of 0.5 ha. We analyzed spatial patterns and associations of size classes using SADIE methodology. Different from what we expected, both species were more abundant among the studied plots and exhibited an increasing aggregation from small to large size classes. We also found a positive spatial association between size classes of both. These results suggest that both savanna and forest species produce similar spatial patterns independently of habitat affinity. We discuss the possible processes responsible for the observed patterns.

  4. Cell adhesion pattern created by OSTE polymers.

    Science.gov (United States)

    Liu, Wenjia; Li, Yiyang; Ding, Xianting

    2017-04-24

    Engineering surfaces with functional polymers is a crucial issue in the field of micro/nanofabrication and cell-material interface studies. For many applications of surface patterning, it does not need cells to attach on the whole surface. Herein, we introduce a novel polymer fabrication protocol of off-stoichiometry thiol-ene (OSTE) polymers to create heterogeneity on the surface by utilizing 3D printing and soft-lithography. By choosing two OSTE polymers with different functional groups, we create a pattern where only parts of the surface can facilitate cell adhesion. We also study the hydrophilic property of OSTE polymers by mixing poly(ethylene glycol) (PEG) directly with pre-polymers and plasma treatments afterwards. Moreover, we investigate the effect of functional groups' excess ratio and hydrophilic property on the cell adhesion ability of OSTE polymers. The results show that the cell adhesion ability of OSTE materials can be tuned within a wide range by the coupling effect of functional groups' excess ratio and hydrophilic property. Meanwhile, by mixing PEG with pre-polymers and undergoing oxygen plasma treatment afterward can significantly improve the hydrophilic property of OSTE polymers.

  5. Advanced Manufacturing Technologies (AMT): Additive Manufactured Hot Fire Planning and Testing in GRC Cell 32 Project

    Science.gov (United States)

    Fikes, John C.

    2014-01-01

    The objective of this project is to hot fire test an additively manufactured thrust chamber assembly TCA (injector and thrust chamber). GRC will install the additively manufactured Inconel 625 injector, two additively manufactured (SLM) water cooled Cu-Cr thrust chamber barrels and one additively manufactured (SLM) water cooled Cu-Cr thrust chamber nozzle on the test stand in Cell 32 and perform hot fire testing of the integrated TCA.

  6. Cell patterning through inkjet printing of one cell per droplet

    International Nuclear Information System (INIS)

    Yamaguchi, Shuichi; Akiyama, Yoshitake; Morishima, Keisuke; Ueno, Akira

    2012-01-01

    The inkjet ejection technology used in printers has been adopted and research has been conducted on manufacturing artificial tissue by patterning cells through micronozzle ejection of small droplets containing multiple cells. However, stable injection of cells has proven difficult, owing to the frequent occurrence of nozzle clogging. In this paper, a piezoelectric inkjet head constructed with a glass capillary that enabled viewing of the nozzle section was developed, the movement of cells ejected from the nozzle tip was analyzed, and a method for stably ejecting cells was verified. A pull–push ejection method was compared with a push–pull ejection method regarding the voltage waveform applied to the piezoelectric element of the head. The push–pull method was found to be more suitable for stable ejection. Further, ejection of one cell per droplet was realized by detecting the position of the cell in the nozzle section and utilizing these position data. Thus, a method for more precise patterning of viable cells at desired position and number was established. This method is very useful and promising not only for biofabrication, 3D tissue construction, cell printing, but also for a number of biomedical application, such as bioMEMS, lab on a chip research field. (paper)

  7. Oblique electron fire hose instability: Particle-in-cell simulations

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr; Trávníček, Pavel M.; Decyk, V.; Schriver, D.

    2014-01-01

    Roč. 119, č. 1 (2014), s. 59-68 ISSN 2169-9380 R&D Projects: GA ČR GAP209/12/2041 Institutional support: RVO:67985815 Keywords : electron temperature anisotropy * fire hose instability Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.426, year: 2014

  8. Fire patterns in piñon and juniper land cover types in the Semiarid Western United States from 1984 through 2013

    Science.gov (United States)

    David I. Board; Jeanne C. Chambers; Richard F. Miller; Peter J. Weisberg

    2018-01-01

    Increases in area burned and fire size have been reported across a wide range of forest and shrubland types in the Western United States in recent decades, but little is known about potential changes in fire regimes of piñon and juniper land cover types. We evaluated spatio-temporal patterns of fire in piñon and juniper land cover types from the National Gap Analysis...

  9. Non-respiratory neurons in the Bötzinger complex exhibiting appropriate firing patterns to generate the emetic act in dogs.

    Science.gov (United States)

    Fukuda, H; Koga, T

    1992-08-01

    This work was performed to prove the hypothesis that the pattern generator for the emetic act exists in the Bötzinger complex (BOT) and is driven by vagal afferents via the subpostrema portion of the nucleus of the solitary tract (mNST). Non-respiratory neurons (78) intermingling with BOT respiratory neurons in decerebrate dogs responded to pulse train stimulation of vagal afferents with a mean latency of 387 ms. During retching induced by vagal stimulation, one-half of the non-respiratory neurons exhibited high frequency burst firings synchronous with each retch (SH-firing, SH-neurons) and one-third of these neurons showed similar firings synchronous with the periods between retches (BH-firing, BH-neurons). Two-thirds of the SH-neurons and one-half of the BH-neurons fired with gradually augmenting frequencies (augmenting firing) during the period prior to retching, which may correspond to the period of prodromal signs of vomiting. Three SH-neurons were observed at fictive expulsion: all 3 exhibited burst firings concomitant with expulsion. During cooling block of transmission in the mNST, stimulation of the vagus nerve ipsilateral to the cooling failed to induce not only retching but also augmenting firing and SH-firing in all 11 BOT SH-neurons observed. In contrast, contralateral vagal stimulation induced retching and neuronal firings which had been observed before the cooling. These results support the hypothesis mentioned above. Respiratory firings were changed during retching in all BOT respiratory neurons observed. Respiratory firings were depressed during retching in the majority (15/25) of inspiratory (I) neurons and in a few expiratory (E) neurons (6/45). SH-firing was exhibited by 3 I- and 13 E-neurons. A few (2) I- and half (23) E-neurons showed BH-firing. These results indicate that all BOT respiratory neurons participate in central patterning of the emetic act.

  10. Oblique electron fire hose instability: Particle-in-cell simulations

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr; Trávníček, Pavel M.; Decyk, V.; Schriver, D.

    2014-01-01

    Roč. 119, č. 1 (2014), s. 59-68 ISSN 2169-9380 R&D Projects: GA ČR GAP209/12/2041 Grant - others:European Commission(XE) 284515 Institutional support: RVO:68378289 Keywords : electron temperature anisotropy * fire hose instability Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.426, year: 2014 http://onlinelibrary.wiley.com/doi/10.1002/2013JA019227/abstract

  11. Model cerebellar granule cells can faithfully transmit modulated firing rate signals

    Directory of Open Access Journals (Sweden)

    Christian eRössert

    2014-10-01

    Full Text Available A crucial assumption of many high-level system models of the cerebellum is that information in the granular layer is encoded in a linear manner. However, granule cells are known for their non-linear and resonant synaptic and intrinsic properties that could potentially impede linear signal transmission.In this modelling study we analyse how electrophysiological granule cell properties and spike sampling influence information coded by firing rate modulation, assuming no signal-related, i.e. uncorrelated inhibitory feedback (open-loop mode.A detailed one-compartment granule cell model was excited in simulation by either direct current or mossy-fibre synaptic inputs. Vestibular signals were represented as tonic inputs to the flocculus modulated at frequencies up to 20 Hz (approximate upper frequency limit of vestibular-ocular reflex, VOR. Model outputs were assessed using estimates of both the transfer function, and the fidelity of input-signal reconstruction measured as variance-accounted-for.The detailed granule cell model with realistic mossy-fibre synaptic inputs could transmit information faithfully and linearly in the frequency range of the vestibular-ocular reflex. This was achieved most simply if the model neurons had a firing rate at least twice the highest required frequency of modulation, but lower rates were also adequate provided a population of neurons was utilized, especially in combination with push-pull coding. The exact number of neurons required for faithful transmission depended on the precise values of firing rate and noise. The model neurons were also able to combine excitatory and inhibitory signals linearly, and could be replaced by a simpler (modified integrate-and-fire neuron in the case of high tonic firing rates.These findings suggest that granule cells can in principle code modulated firing-rate inputs in a linear manner, and are thus consistent with the high-level adaptive-filter model of the cerebellar microcircuit.

  12. Rationalization design on large equipment dismantling facility. The cell fire-extinguishing examination. 1. Technical report

    International Nuclear Information System (INIS)

    Donomae, Yasushi; Matsumoto, Yoshihiro; Kikuchi, Yutaka; Katoh, Noriyoshi; Miyazaki, Hitoshi; Tanimoto, Kenichi

    2002-01-01

    In order to rationalize for Large Equipment Dismantling Facility (LEDF), the plan of removing vaporizer belong to Cell-fire-extinguishing-system was investigated. In this test, in order to study the behavior of pressure in cell, when the liquefaction carbon dioxide (liq-CO 2 ) is emitted, and the performance of extinguishing fires, the test of behavior. of pressure and the extinguishing fires take effect. Also the extinguishing fires test used water-mist take effect for complement liq-CO 2 . The results as follows; (1) In the test of behavior of pressure, Liq-CO 2 was emitted test room under -40 mmAq negative pressure. Room pressure was increase about 0.8 mmAq/sec at first. After 20 sec, the pressure was increase slowly about 0.1 mmAq/sec. After 120 sec,the increase was drastic about 1.5 mmAq/s. (2) In the test of extinguishing fires by liq-CO 2 , under -40 mmAq, Polyethylene and wooden chips + cotton (crib) was burn. Polyethylene was extinguished perfectly, but the embers remained in cribs. While the room pressure was increase about 1.3 mmAq/sec for 10 sec at first. After 30 sec, the pressure was increase about 1 mmAq/sec. On the other hand, the drastic increase of pressure disappeared between 100 sec to 120 sec by change the nozzle size from 14 mm 2 to 10 mm 2 . (3) In the test of extinguishing fires by water-mist, Cribs was extinguished perfectly, but Polyethylene was extinguished difficulty under the same condition of liq-CO 2 test. (4) Therefore the results, It's coped with the fire extinguishing and the keeping negative 2 pressure for LEDF cells. Therefore nozzle size is fitted cell volume as changing 14 mm 2 to 10 mm 2 (5) As the performance of extinguishing fires by liq-CO 2 , It is necessity the concentration of above 50% CO 2 for combustibles as cribs, remaining the embers. (6) On the other hand, It is necessity most study for the adoption of water-mist. Therefore water-mist was not effective for polyethylene, and it needed water for fire in great volume

  13. Global Characterization of Biomass-Burning Patterns using Satellite Measurements of Fire Radiative Energy

    Science.gov (United States)

    Ichoku, Charles; Giglio, Louis; Wooster, Martin J.; Remer, Lorraine A.

    2008-01-01

    Remote sensing is the most practical means of measuring energy release from large open-air biomass burning. Satellite measurement of fire radiative energy (FRE) release rate or power (FRP) enables distinction between fires of different strengths. Based on a 1-km resolution fire data acquired globally by the MODerate-resolution Imaging Spectro-radiometer (MODIS) sensor aboard the Terra and Aqua satellites from 2000 to 2006, instanteaneous FRP values ranged between 0.02 MW and 1866 MW, with global daily means ranging between 20 and 40 MW. Regionally, at the Aqua-MODIS afternoon overpass, the mean FRP values for Alaska, Western US, Western Australia, Quebec and the rest of Canada are significantly higher than these global means, with Quebec having the overall highest value of 85 MW. Analysis of regional mean FRP per unit area of land (FRP flux) shows that a peak fire season in certain regions, fires can be responsible for up to 0.2 W/m(sup 2) at peak time of day. Zambia has the highest regional monthly mean FRP flux of approximately 0.045 W/m(sup 2) at peak time of day and season, while the Middle East has the lowest value of approximately 0.0005 W/m(sup 2). A simple scheme based on FRP has been devised to classify fires into five categories, to facilitate fire rating by strength, similar to earthquakes and hurricanes. The scheme uses MODIS measurements of FRP at 1-km resolution as follows: catagory 1 (less than 100 MW), category 2 (100 to less than 500 MW), category 3 (500 to less than 1000 MW), category 4 (1000 to less than 1500 MW), catagory 5 (greater than or equal to 1500 MW). In most regions of the world, over 90% of fires fall into category 1, while only less than 1% fall into each of categories 3 to 5, although these proportions may differ significantly from day to day and by season. The frequency of occurence of the larger fires is region specific, and could not be explained by ecosystem type alone. Time-series analysis of the propertions of higher category

  14. Patterns of canopy and surface layer consumption in a boreal forest fire from repeat airborne lidar

    Science.gov (United States)

    Alonzo, Michael; Morton, Douglas C.; Cook, Bruce D.; Andersen, Hans-Erik; Babcock, Chad; Pattison, Robert

    2017-05-01

    Fire in the boreal region is the dominant agent of forest disturbance with direct impacts on ecosystem structure, carbon cycling, and global climate. Global and biome-scale impacts are mediated by burn severity, measured as loss of forest canopy and consumption of the soil organic layer. To date, knowledge of the spatial variability in burn severity has been limited by sparse field sampling and moderate resolution satellite data. Here, we used pre- and post-fire airborne lidar data to directly estimate changes in canopy vertical structure and surface elevation for a 2005 boreal forest fire on Alaska’s Kenai Peninsula. We found that both canopy and surface losses were strongly linked to pre-fire species composition and exhibited important fine-scale spatial variability at sub-30 m resolution. The fractional reduction in canopy volume ranged from 0.61 in lowland black spruce stands to 0.27 in mixed white spruce and broadleaf forest. Residual structure largely reflects standing dead trees, highlighting the influence of pre-fire forest structure on delayed carbon losses from aboveground biomass, post-fire albedo, and variability in understory light environments. Median loss of surface elevation was highest in lowland black spruce stands (0.18 m) but much lower in mixed stands (0.02 m), consistent with differences in pre-fire organic layer accumulation. Spatially continuous depth-of-burn estimates from repeat lidar measurements provide novel information to constrain carbon emissions from the surface organic layer and may inform related research on post-fire successional trajectories. Spectral measures of burn severity from Landsat were correlated with canopy (r = 0.76) and surface (r = -0.71) removal in black spruce stands but captured less of the spatial variability in fire effects for mixed stands (canopy r = 0.56, surface r = -0.26), underscoring the difficulty in capturing fire effects in heterogeneous boreal forest landscapes using proxy measures of burn

  15. Topographic Patterns of Mortality and Succession in the Alpine Treeline Ecotone Suggest Hydrologic Controls on Post-Fire Tree Establishment

    Science.gov (United States)

    McCaffrey, D. R.; Hopkinson, C.

    2017-12-01

    Alpine Treeline Ecotone (ATE), the transition zone between closed canopy forest and alpine tundra, is a prominent vegetation pattern in mountain regions. At continental scales, the elevation of ATE is negatively correlated with latitude and is generally explained by thermal limitations. However, at landscape scales, precipitation and moisture regimes can suppress ATE elevation below thermal limits, causing variability and patterning in ATE position. Recent studies have investigated the relative effects of hydroclimatic variables on ATE position at multiple scales, but less attention has been given to interactions between hydroclimatic variables and disturbance agents, such as fire. Observing change in the ATE at sufficient spatial resolution and temporal extent to identify correlations between topographic variables and disturbance agents has proved challenging. Recent advances in monoplotting have enabled the extraction of canopy cover information from oblique photography, at a resolution of 20 m. Using airborne lidar and repeat photography from the Mountain Legacy Project, we observed canopy cover change in West Castle Watershed (Alberta, Canada; 103 km2; 49.3° N, 114.4° W) over a 92-year period (i.e. 1914-2006). Two wildfires, occurring 1934 and 1936, affected 63% of the watershed area, providing an opportunity to contrast topographic patterns of mortality and succession in the ATE, while factoring by exposure to fire. Slope aspect was a strong predictor of mortality and succession: the frequency of mortality was four times higher in fire-exposed areas, with 72% of all mortality occurring on south- and east-facing slope aspects; the frequency of succession was balanced between fire-exposed and unexposed areas, with 66% of all succession occurred on north- and east-facing slope aspects. Given previous experiments have demonstrated that moisture limitation inhibits tree establishment, suppressing elevation of ATE below thermal growth boundaries, we hypothesize

  16. Firing properties of identified interneuron populations in the mammalian hindlimb central pattern generator

    DEFF Research Database (Denmark)

    Butt, S. J B; Harris-Warrick, Ronald M.; Kiehn, Ole

    2002-01-01

    a heterogenous population with neurons that fired in all phases of the locomotor cycle and exhibited varying degrees of rhythmicity, from strongly rhythmic to nonrhythmic. Among the rhythmic, putative CPG dCINs were populations that fired inphase with the ipsilateral or with the contralateral L2 locomotorlike...... activity. There was a high degree of organization in the dorsoventral location of rhythmic dCINs, with neurons in-phase with the ipsilateral L2 activity located more ventrally. Spikes of rhythmically active dCINs were superimposed on membrane oscillations that were generated predominantly by synaptic input...

  17. 40 CFR Appendix A to Part 76 - Phase I Affected Coal-Fired Utility Units With Group 1 or Cell Burner Boilers

    Science.gov (United States)

    2010-07-01

    ... Units With Group 1 or Cell Burner Boilers A Appendix A to Part 76 Protection of Environment... 1 or Cell Burner Boilers Table 1—Phase I Tangentially Fired Units State Plant Unit Operator ALABAMA... Vertically fired boiler. 2 Arch-fired boiler. Table 3—Phase I Cell Burner Technology Units State Plant Unit...

  18. Synchronized Firings in Retinal Ganglion Cells in Response to Natural Stimulation

    International Nuclear Information System (INIS)

    Zhang Ying-Ying; Xiao Lei; Liu Wen-Zhong; Gong Hai-Qing; Liang Pei-Ji

    2011-01-01

    The response of synchronously firing groups of population retinal ganglion cells (RGCs) to natural movies (NMs) and pseudo-random white-noise checker-board flickering (CB, as control) are investigated using an information-theoretic algorithm. The main results are: (1) the population RGCs tend to fire in synchrony far more frequently than expected by chance during both NM and CB stimulation; (2) more synchronous groups could be formed and each group contains more neurons under NM than CB stimulation; (3) the individual neurons also participate in more groups and have more distinct partners in NM than CB stimulation. All these results suggest that the synchronized firings in RGCs are more extensive and diverse, which may account for more effective information processing in representing the natural visual environment. (cross-disciplinary physics and related areas of science and technology)

  19. Indirect-fired gas turbine dual fuel cell power cycle

    Science.gov (United States)

    Micheli, Paul L.; Williams, Mark C.; Sudhoff, Frederick A.

    1996-01-01

    A fuel cell and gas turbine combined cycle system which includes dual fuel cell cycles combined with a gas turbine cycle wherein a solid oxide fuel cell cycle operated at a pressure of between 6 to 15 atms tops the turbine cycle and is used to produce CO.sub.2 for a molten carbonate fuel cell cycle which bottoms the turbine and is operated at essentially atmospheric pressure. A high pressure combustor is used to combust the excess fuel from the topping fuel cell cycle to further heat the pressurized gas driving the turbine. A low pressure combustor is used to combust the excess fuel from the bottoming fuel cell to reheat the gas stream passing out of the turbine which is used to preheat the pressurized air stream entering the topping fuel cell before passing into the bottoming fuel cell cathode. The CO.sub.2 generated in the solid oxide fuel cell cycle cascades through the system to the molten carbonate fuel cell cycle cathode.

  20. Spatial patterning of fuels and fire hazard across a central U.S. deciduous forest region

    Science.gov (United States)

    Michael C. Stambaugh; Daniel C. Dey; Richard P. Guyette; Hong S. He; Joseph M. Marschall

    2011-01-01

    Information describing spatial and temporal variability of forest fuel conditions is essential to assessing overall fire hazard and risk. Limited information exists describing spatial characteristics of fuels in the eastern deciduous forest region, particularly in dry oak-dominated regions that historically burned relatively frequently. From an extensive fuels survey...

  1. Contemporary patterns of burn severity heterogeneity from fires in the Northwestern U.S.

    Science.gov (United States)

    R. Travis Belote

    2015-01-01

    Historically, frequent, low-severity fires maintained opengrown structure of dry ponderosa pine forests (Hessburg and Agee 2003). Thus, an open forest structure may be a reasonable template for ecological restoration in those particular forest types (Allen and others 2002). In contrast, setting goals for ecosystem management and restoration targets in the vast majority...

  2. Current and future patterns of fire-induced forest degradation in Amazonia

    Science.gov (United States)

    De Faria, Bruno L.; Brando, Paulo M.; Macedo, Marcia N.; Panday, Prajjwal K.; Soares-Filho, Britaldo S.; Coe, Michael T.

    2017-09-01

    Amazon droughts directly increase forest flammability by reducing forest understory air and fuel moisture. Droughts also increase forest flammability indirectly by decreasing soil moisture, triggering leaf shedding, branch loss, and tree mortality—all of which contribute to increased fuel loads. These direct and indirect effects can cause widespread forest fires that reduce forest carbon stocks in the Amazon, with potentially important consequences for the global carbon cycle. These processes are expected to become more widespread, common, and intense as global climate changes, yet the mechanisms linking droughts, wildfires, and associated changes in carbon stocks remain poorly understood. Here, we expanded the capabilities of a dynamic forest carbon model to better represent (1) drought effects on carbon and fuel dynamics and (2) understory fire behavior and severity. We used the refined model to quantify changes in Pan-Amazon live carbon stocks as a function of the maximum climatological water deficit (MCWD) and fire intensity, under both historical and future climate conditions. We found that the 2005 and 2010 droughts increased potential fire intensity by 226 kW m‑1 and 494 kW m‑1, respectively. These increases were due primarily to increased understory dryness (109 kW m‑1 in 2005; 124 kW m‑1 in 2010) and altered forest structure (117 kW m‑1 in 2005; 370 kW m‑1 in 2010) effects. Combined, these historic droughts drove total simulated reductions in live carbon stocks of 0.016 (2005) and 0.027 (2010) PgC across the Amazon Basin. Projected increases in future fire intensity increased simulated carbon losses by up to 90% per unit area burned, compared with modern climate. Increased air temperature was the primary driver of changes in simulated future fire intensity, while reduced precipitation was secondary, particularly in the eastern portion of the Basin. Our results show that fire-drought interactions strongly affect live carbon stocks and that

  3. Sensory renal innervation: a kidney-specific firing activity due to a unique expression pattern of voltage-gated sodium channels?

    Science.gov (United States)

    Freisinger, Wolfgang; Schatz, Johannes; Ditting, Tilmann; Lampert, Angelika; Heinlein, Sonja; Lale, Nena; Schmieder, Roland; Veelken, Roland

    2013-03-01

    Sensory neurons with afferent axons from the kidney are extraordinary in their response to electrical stimulation. More than 50% exhibit a tonic firing pattern, i.e., sustained action potential firing throughout depolarizing, pointing to an increased excitability, whereas nonrenal neurons show mainly a phasic response, i.e., less than five action potentials. Here we investigated whether these peculiar firing characteristics of renal afferent neurons are due to differences in the expression of voltage-gated sodium channels (Navs). Dorsal root ganglion (DRG) neurons from rats (Th11-L2) were recorded by the current-clamp technique and distinguished as "tonic" or "phasic." In voltage-clamp recordings, Navs were characterized by their tetrodotoxoxin (TTX) sensitivity, and their molecular identity was revealed by RT-PCR. The firing pattern of 66 DRG neurons (41 renal and 25 nonrenal) was investigated. Renal neurons exhibited more often a tonic firing pattern (56.1 vs. 12%). Tonic neurons showed a more positive threshold (-21.75 ± 1.43 vs.-29.33 ± 1.63 mV; P sodium currents. Interestingly, mRNA expression of TTX-resistant sodium channels was significantly increased in renal, predominantly tonic, DRG neurons. Hence, under physiological conditions, renal sensory neurons exhibit predominantly a firing pattern associated with higher excitability. Our findings support that this is due to an increased expression and activation of TTX-resistant Navs.

  4. Evaluation of the oscillatory interference model of grid cell firing through analysis and measured period variance of some biological oscillators.

    Directory of Open Access Journals (Sweden)

    Eric A Zilli

    2009-11-01

    Full Text Available Models of the hexagonally arrayed spatial activity pattern of grid cell firing in the literature generally fall into two main categories: continuous attractor models or oscillatory interference models. Burak and Fiete (2009, PLoS Comput Biol recently examined noise in two continuous attractor models, but did not consider oscillatory interference models in detail. Here we analyze an oscillatory interference model to examine the effects of noise on its stability and spatial firing properties. We show analytically that the square of the drift in encoded position due to noise is proportional to time and inversely proportional to the number of oscillators. We also show there is a relatively fixed breakdown point, independent of many parameters of the model, past which noise overwhelms the spatial signal. Based on this result, we show that a pair of oscillators are expected to maintain a stable grid for approximately t = 5mu(3/(4pisigma(2 seconds where mu is the mean period of an oscillator in seconds and sigma(2 its variance in seconds(2. We apply this criterion to recordings of individual persistent spiking neurons in postsubiculum (dorsal presubiculum and layers III and V of entorhinal cortex, to subthreshold membrane potential oscillation recordings in layer II stellate cells of medial entorhinal cortex and to values from the literature regarding medial septum theta bursting cells. All oscillators examined have expected stability times far below those seen in experimental recordings of grid cells, suggesting the examined biological oscillators are unfit as a substrate for current implementations of oscillatory interference models. However, oscillatory interference models can tolerate small amounts of noise, suggesting the utility of circuit level effects which might reduce oscillator variability. Further implications for grid cell models are discussed.

  5. Changing distributions of carbon monoxide (CO) over Africa from climate and land use driven fire patterns

    Science.gov (United States)

    Worden, Helen; Bloom, Anthony; Worden, John

    2017-04-01

    Satellite measurements of atmospheric carbon monoxide (CO) provide a signature for biomass burning and anthropogenic combustion-related pollution emissions. CO plays an important role in both air quality and climate as a precursor for tropospheric ozone and as a major sink of OH, the atmospheric "detergent" that affects the lifetime of methane and other pollutants. Worden et al., [2013] showed decreasing global CO values in time series of satellite total column CO measurements over the past decade. All of the satellite instruments that measure CO in the thermal infrared showed consistent inter-annual variability due to fires and possibly the global recession in late 2008. Observed decreases in CO over N. America and Europe were consistent with expected decreases in CO emissions inventories [Granier et al., 2011], however, the decrease is not uniform globally. In particular, some regions of Africa show negligible trends in CO. Here we examine the 14-year time series (2002-2015) of surface and total column CO concentrations from MOPITT and fire radiative power (FRP) from MODIS over Africa to study the attribution of changes in CO. We are interested in changes in fires due to climate variability (El Nino) and land-use, including urbanization, and their effect on atmospheric CO burden.

  6. Autonomous patterning of cells on microstructured fine particles

    International Nuclear Information System (INIS)

    Takeda, Iwori; Kawanabe, Masato; Kaneko, Arata

    2015-01-01

    Regularly patterned cells can clarify cellular function and are required in some biochip applications. This study examines cell patterning along microstructures and the effect of microstructural geometry on selective cellular adhesion. Particles can be autonomously assembled on a soda-lime glass substrate that is chemically patterned by immersion in a suspension of fine particles. By adopting various sizes of fine particles, we can control the geometry of the microstructure. Cells adhere more readily to microstructured fine particles than to flat glass substrate. Silica particles hexagonally packed in 5–40 μm line and space microstructures provide an effective cell scaffold on the glass substrate. Cultured cells tend to attach and proliferate along the microstructured region while avoiding the flat region. The difference in cell adhesion is attributed to their geometries, as both of the silica particles and soda-lime glass are hydrophilic related with cell adhesiveness. After cell seeding, cells adhered to the flat region migrated toward the microstructured region. For most of the cells to assemble on the scaffold, the scaffolding microstructures must be spaced by at most 65 μm. - Highlights: • PS and SiO 2 particles provide effective scaffolds for cells. • Cells that adhere to microstructured particles successfully proliferate and differentiate. • Selective adhesion and growth along the scaffold can be achieved by patterning the fine particle microstructure. • Cells adhered to flat regions migrate toward microstructured regions. • Selective adhesion by cells depends on the microstructural geometry; specifically, on the inter-line spacing

  7. Quantifying erosion and deposition patterns using airborne LiDAR following the 2012 High Park Fire and 2013 Colorado Flood

    Science.gov (United States)

    Brogan, D. J.; Nelson, P. A.; MacDonald, L. H.

    2015-12-01

    Quantifying and predicting geomorphic change over large spatial scales is increasingly feasible and of growing interest as repeat high resolution topography becomes available. We began detailed field studies of channel geomorphic change using RTK-GPS in two 15 km2 watersheds following the 2012 High Park Fire; the watersheds were then subjected to a several-hundred year flood in September 2013. During this time a series of airborne LiDAR datasets were collected, and the objectives of this study were to: 1) determine and compare the spatial variability in channel and valley erosion and deposition over time from the LiDAR; and 2) determine if the observed changes can be predicted from channel and valley bottom characteristics. Data quality issues in the initial LiDAR required us to rotate and translate flight lines in order to co-register ground-classified point clouds between successive datasets; uncertainty was then estimated using our RTK-GPS field measurements. Topographic changes were calculated using the Multiscale Model to Model Cloud Comparison (M3C2) algorithm. Results indicate that the 2013 flood mobilized much more sediment than was mobilized due to the fire alone; unfortunately the uncertainty in differencing is still frequently greater than the observed changes, especially within transfer reaches. Valley expansion and constriction are major controls on spatial patterns of erosion and deposition, suggesting that topographic metrics such as longitudinal distributions of channel slope and valley confinement may provide quasi-physically based estimates of sediment deposition and delivery potential.

  8. The cell pattern correction through design-based metrology

    Science.gov (United States)

    Kim, Yonghyeon; Lee, Kweonjae; Chang, Jinman; Kim, Taeheon; Han, Daehan; Lee, Kyusun; Hong, Aeran; Kang, Jinyoung; Choi, Bumjin; Lee, Joosung; Yeom, Kyehee; Lee, Jooyoung; Hong, Hyeongsun; Lee, Kyupil; Jin, Gyoyoung

    2015-03-01

    Starting with the sub 2Xnm node, the process window becomes smaller and tighter than before. Pattern related error budget is required for accurate critical-dimension control of Cell layers. Therefore, lithography has been faced with its various difficulties, such as weird distribution, overlay error, patterning difficulty etc. The distribution of cell pattern and overlay management are the most important factors in DRAM field. We had been experiencing that the fatal risk is caused by the patterns located in the tail of the distribution. The overlay also induces the various defect sources and misalignment issues. Even though we knew that these elements are important, we could not classify the defect type of Cell patterns. Because there is no way to gather massive small pattern CD samples in cell unit block and to compare layout with cell patterns by the CD-SEM. The CD- SEM is used in order to gather these data through high resolution, but CD-SEM takes long time to inspect and extract data because it measures the small FOV. (Field Of View) However, the NGR(E-beam tool) provides high speed with large FOV and high resolution. Also, it's possible to measure an accurate overlay between the target layout and cell patterns because they provide DBM. (Design Based Metrology) By using massive measured data, we extract the result that it is persuasive by applying the various analysis techniques, as cell distribution and defects, the pattern overlay error correction etc. We introduce how to correct cell pattern, by using the DBM measurement, and new analysis methods.

  9. Vegetation pattern and diversity in S. E. labrador, canada: Betula papyrifera (birch) forest development in relation to fire history and physiography. [Picea mariana; Abies balsamea

    Energy Technology Data Exchange (ETDEWEB)

    Foster, D.R.; King, G.A.

    1986-06-01

    The Betula papyrifera (paper birch) forest of the wilderness of southeastern Labrador is described. B. papyrifera forests range in size from less than 1 ha to several km/sup 2/, display sharp borders with the adjoining conifer forests and are restricted to steep slopes that have burned in the previous 110 years. Floristically, the B papyrifera community is distinguished from conifer forests by the presence of fourteen differential species, by the scarcity of terrestrial cryptograms and by the development of a diverse understory of vascular plants. Three minimum conditions are necessary for B. papyrifera forest development: (i) moist and well-drained soils, (ii) a nearby seed source, and (iii) an open site. The nearly exclusive restriction of B. papyrifera forest to areas that have burned in the last 110 years indicates that the open-site conditions necessary for stand initiation are largely created by lightning fires. Age-structure analysis demonstrates that, following fire, regeneration by B. papyrifera is rapid and results in the formation of an even-aged overstory. Gradual invasion of canopy openings by Picea mariana and Abies balsamea results in the progressive conversion to conifer forest. Fire maintains B. papyrifera and other early post-fire communities in a mosaic pattern and increases regional vegetation diversity. The pattern is not random, but is controlled by species autoecologies, the pattern of fires and physiography. The vegetation of southeastern Labrador is in a state of dynamic equilibrium.

  10. Prevalence and pattern of sickle cell disease in premarital couples ...

    African Journals Online (AJOL)

    Context: Premarital haemoglobin screening is an important strategy for the control of Sickle Cell Disease. Aims: To determine the prevalence and pattern of sickle cell disease among premarital couples and to assess their attitude to the risk of sickle cell anaemia in their offspring. Settings and Design: A cross sectional ...

  11. Robotic Patterning a Superhydrophobic Surface for Collective Cell Migration Screening.

    Science.gov (United States)

    Pang, Yonggang; Yang, Jing; Hui, Zhixin; Grottkau, Brian E

    2018-04-01

    Collective cell migration, in which cells migrate as a group, is fundamental in many biological and pathological processes. There is increasing interest in studying the collective cell migration in high throughput. Cell scratching, insertion blocker, and gel-dissolving techniques are some methodologies used previously. However, these methods have the drawbacks of cell damage, substrate surface alteration, limitation in medium exchange, and solvent interference. The superhydrophobic surface, on which the water contact angle is greater than 150 degrees, has been recently utilized to generate patterned arrays. Independent cell culture areas can be generated on a substrate that functions the same as a conventional multiple well plate. However, so far there has been no report on superhydrophobic patterning for the study of cell migration. In this study, we report on the successful development of a robotically patterned superhydrophobic array for studying collective cell migration in high throughput. The array was developed on a rectangular single-well cell culture plate consisting of hydrophilic flat microwells separated by the superhydrophobic surface. The manufacturing process is robotic and includes patterning discrete protective masks to the substrate using 3D printing, robotic spray coating of silica nanoparticles, robotic mask removal, robotic mini silicone blocker patterning, automatic cell seeding, and liquid handling. Compared with a standard 96-well plate, our system increases the throughput by 2.25-fold and generates a cell-free area in each well non-destructively. Our system also demonstrates higher efficiency than conventional way of liquid handling using microwell plates, and shorter processing time than manual operating in migration assays. The superhydrophobic surface had no negative impact on cell viability. Using our system, we studied the collective migration of human umbilical vein endothelial cells and cancer cells using assays of endpoint

  12. Multiple remote sensing data sources to assess spatio-temporal patterns of fire incidence over Campos Amazônicos Savanna Vegetation Enclave (Brazilian Amazon).

    Science.gov (United States)

    Alves, Daniel Borini; Pérez-Cabello, Fernando

    2017-12-01

    Fire activity plays an important role in the past, present and future of Earth system behavior. Monitoring and assessing spatial and temporal fire dynamics have a fundamental relevance in the understanding of ecological processes and the human impacts on different landscapes and multiple spatial scales. This work analyzes the spatio-temporal distribution of burned areas in one of the biggest savanna vegetation enclaves in the southern Brazilian Amazon, from 2000 to 2016, deriving information from multiple remote sensing data sources (Landsat and MODIS surface reflectance, TRMM pluviometry and Vegetation Continuous Field tree cover layers). A fire scars database with 30 m spatial resolution was generated using a Landsat time series. MODIS daily surface reflectance was used for accurate dating of the fire scars. TRMM pluviometry data were analyzed to dynamically establish time limits of the yearly dry season and burning periods. Burned area extent, frequency and recurrence were quantified comparing the results annually/seasonally. Additionally, Vegetation Continuous Field tree cover layers were used to analyze fire incidence over different types of tree cover domains. In the last seventeen years, 1.03millionha were burned within the study area, distributed across 1432 fire occurrences, highlighting 2005, 2010 and 2014 as the most affected years. Middle dry season fires represent 86.21% of the total burned areas and 32.05% of fire occurrences, affecting larger amount of higher density tree surfaces than other burning periods. The results provide new insights into the analysis of burned areas of the neotropical savannas, spatially and statistically reinforcing important aspects linked to the seasonality patterns of fire incidence in this landscape. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Analysis of chemical signals in red fire ants by gas chromatography and pattern recognition techniques

    Science.gov (United States)

    The combination of gas chromatography and pattern recognition (GC/PR) analysis is a powerful tool for investigating complicated biological problems. Clustering, mapping, discriminant development, etc. are necessary to analyze realistically large chromatographic data sets and to seek meaningful relat...

  14. Cell cycles and proliferation patterns in Haematococcus pluvialis

    Science.gov (United States)

    Zhang, Chunhui; Liu, Jianguo; Zhang, Litao

    2017-09-01

    Most studies on Haematococcus pluvialis have been focused on cell growth and astaxanthin accumulation; far less attention has been paid to cell cycles and proliferation patterns. The purpose of this study was to clarify cell cycles and proliferation patterns in H. pluvialis microscopically using a camera and video recorder system. The complicated life history of H. pluvialis can be divided into two stages: the motile stage and the non-motile stage. All the cells can be classified into forms as follows: motile cell, nonmotile cell, zoospore and aplanospore. The main cell proliferation, both in the motile phase and non-motile phase in H. pluvialis, is by asexual reproduction. Under normal growth conditions, a motile cell usually produces two, sometimes four, and exceptionally eight zoospores. Under unfavorable conditions, the motile cell loses its flagella and transforms into a non-motile cell, and the non-motile cell usually produces 2, 4 or 8 aplanospores, and occasionally 20-32 aplanospores, which further develop into non-motile cells. Under suitable conditions, the non-motile cell is also able to release zoospores. The larger non-motile cells produce more than 16 zoospores, and the smaller ones produce 4 or 8 zoospores. Vegetative reproduction is by direct cell division in the motile phase and by occasional cell budding in the non-motile phase. There is, as yet, no convincing direct evidence for sexual reproduction.

  15. The Sodium-Potassium Pump Controls the Intrinsic Firing of the Cerebellar Purkinje Neuron

    Science.gov (United States)

    Forrest, Michael D.; Wall, Mark J.; Press, Daniel A.; Feng, Jianfeng

    2012-01-01

    In vitro, cerebellar Purkinje cells can intrinsically fire action potentials in a repeating trimodal or bimodal pattern. The trimodal pattern consists of tonic spiking, bursting, and quiescence. The bimodal pattern consists of tonic spiking and quiescence. It is unclear how these firing patterns are generated and what determines which firing pattern is selected. We have constructed a realistic biophysical Purkinje cell model that can replicate these patterns. In this model, Na+/K+ pump activity sets the Purkinje cell's operating mode. From rat cerebellar slices we present Purkinje whole cell recordings in the presence of ouabain, which irreversibly blocks the Na+/K+ pump. The model can replicate these recordings. We propose that Na+/K+ pump activity controls the intrinsic firing mode of cerbellar Purkinje cells. PMID:23284664

  16. Systematic regional variations in Purkinje cell spiking patterns.

    Directory of Open Access Journals (Sweden)

    Jianqiang Xiao

    Full Text Available In contrast to the uniform anatomy of the cerebellar cortex, molecular and physiological studies indicate that significant differences exist between cortical regions, suggesting that the spiking activity of Purkinje cells (PCs in different regions could also show distinct characteristics. To investigate this possibility we obtained extracellular recordings from PCs in different zebrin bands in crus IIa and vermis lobules VIII and IX in anesthetized rats in order to compare PC firing characteristics between zebrin positive (Z+ and negative (Z- bands. In addition, we analyzed recordings from PCs in the A2 and C1 zones of several lobules in the posterior lobe, which largely contain Z+ and Z- PCs, respectively. In both datasets significant differences in simple spike (SS activity were observed between cortical regions. Specifically, Z- and C1 PCs had higher SS firing rates than Z+ and A2 PCs, respectively. The irregularity of SS firing (as assessed by measures of interspike interval distribution was greater in Z+ bands in both absolute and relative terms. The results regarding systematic variations in complex spike (CS activity were less consistent, suggesting that while real differences can exist, they may be sensitive to other factors than the cortical location of the PC. However, differences in the interactions between SSs and CSs, including the post-CS pause in SSs and post-pause modulation of SSs, were also consistently observed between bands. Similar, though less strong trends were observed in the zonal recordings. These systematic variations in spontaneous firing characteristics of PCs between zebrin bands in vivo, raises the possibility that fundamental differences in information encoding exist between cerebellar cortical regions.

  17. Evaluation of DGVMs in tropical areas: linking patterns of vegetation cover, climate and fire to ecological processes

    Science.gov (United States)

    D'Onofrio, Donatella; von Hardenberg, Jost; Baudena, Mara

    2017-04-01

    Many current Dynamic Global Vegetation Models (DGVMs), including those incorporated into Earth System Models (ESMs), are able to realistically reproduce the distribution of the most worldwide biomes. However, they display high uncertainty in predicting the forest, savanna and grassland distributions and the transitions between them in tropical areas. These biomes are the most productive terrestrial ecosystems, and owing to their different biogeophysical and biogeochemical characteristics, future changes in their distributions could have also impacts on climate states. In particular, expected increasing temperature and CO2, modified precipitation regimes, as well as increasing land-use intensity could have large impacts on global biogeochemical cycles and precipitation, affecting the land-climate interactions. The difficulty of the DGVMs in simulating tropical vegetation, especially savanna structure and occurrence, has been associated with the way they represent the ecological processes and feedbacks between biotic and abiotic conditions. The inclusion of appropriate ecological mechanisms under present climatic conditions is essential for obtaining reliable future projections of vegetation and climate states. In this work we analyse observed relationships of tree and grass cover with climate and fire, and the current ecological understanding of the mechanisms driving the forest-savanna-grassland transition in Africa to evaluate the outcomes of a current state-of-the-art DGVM and to assess which ecological processes need to be included or improved within the model. Specifically, we analyse patterns of woody and herbaceous cover and fire return times from MODIS satellite observations, rainfall annual average and seasonality from TRMM satellite measurements and tree phenology information from the ESA global land cover map, comparing them with the outcomes of the LPJ-GUESS DGVM, also used by the EC-Earth global climate model. The comparison analysis with the LPJ

  18. Fire safety assessment for a typical hot cell handling failed fuel sub-assembly. Contributed Paper MS-03

    International Nuclear Information System (INIS)

    Ali, Seik Mansoor; Chandran, Krishna; Balasubramaniyan, V.

    2014-01-01

    This paper presents a systematic study of fire hazard potential within a typical hot cell that handles Failed Fuel SubAssemblies (FSA) for cleaning purposes. A hot cell configuration is considered wherein ethyl alcohol is used as the cleaning agent. The potential for generation of ethyl alcohol vapors due to heat load of FSA, hydrogen generation during the cleaning process, possibility of vapour ignition and sustainability of fire within the cell are discussed. Detailed heat transfer and CFD studies were performed using computational tools developed in-house at SRI to address these issues. Based on this, several recommendations and suggestions are provided for safe operating conditions that could preclude the occurrence of fire within the hot cell. (author)

  19. Prevalence and pattern of Lupus erythematosus cell positivity in ...

    African Journals Online (AJOL)

    The prevalence and pattern of lupus erythematosus (LE) cell positivity in diseases in Ile-Ife, Osun state was carried out between January 1999 and June 2004 (5½ years). A total of 96 patients with different diseases were screened for LE cell using standard techniques. Of this number, 63 (65.6%) were females and 33 ...

  20. Topology optimization of front metallization patterns for solar cells

    NARCIS (Netherlands)

    Gupta, D.K.; Langelaar, M.; Barink, M.; Keulen, F. van

    2015-01-01

    This paper presents the application of topology optimization (TO) for designing the front electrode patterns for solar cells. Improving the front electrode design is one of the approaches to improve the performance of the solar cells. It serves to produce the voltage distribution for the front

  1. Serotonin Regulates the Firing of Principal Cells of the Subiculum by Inhibiting a T-type Ca(2+) Current

    DEFF Research Database (Denmark)

    Petersen, Anders V; Jensen, Camilla S; Crépel, Valérie

    2017-01-01

    . The subiculum receives a high density of fibers originating from the raphe nuclei, suggesting that serotonin (5-HT) modulates subicular neurons. Here we investigated if and how 5-HT modulates the firing pattern of bursting neurons. By combining electrophysiological analysis with pharmacology, optogenetics...

  2. Fuel treatment prescriptions alter spatial patterns of fire severity around the wildland-urban interface during the Wallow Fire, Arizona, USA

    Science.gov (United States)

    Maureen C. Kennedy; Morris C. Johnson

    2014-01-01

    Fuel reduction treatments are implemented in the forest surrounding the wildland–urban interface (WUI) to provide defensible space and safe opportunity for the protection of homes during a wildfire. The 2011 Wallow Fire in Arizona USA burned through recently implemented fuel treatments in the wildland surrounding residential communities in the WUI, and those fuel...

  3. Real-time relationship between PKA biochemical signal network dynamics and increased action potential firing rate in heart pacemaker cells

    Science.gov (United States)

    Yaniv, Yael; Ganesan, Ambhighainath; Yang, Dongmei; Ziman, Bruce D.; Lyashkov, Alexey E.; Levchenko, Andre; Zhang, Jin; Lakatta, Edward G.

    2015-01-01

    cAMP-PKA protein kinase is a key nodal signaling pathway that regulates a wide range of heart pacemaker cell functions. These functions are predicted to be involved in regulation of spontaneous action potential (AP) generation of these cells. Here we investigate if the kinetics and stoichiometry of increase in PKA activity match the increase in AP firing rate in response to β-adrenergic receptor (β-AR) stimulation or phosphodiesterase (PDE) inhibition, that alter the AP firing rate of heart sinoatrial pacemaker cells. In cultured adult rabbit pacemaker cells infected with an adenovirous expressing the FRET sensor AKAR3, the EC50 in response to graded increases in the intensity of β-AR stimulation (by Isoproterenol) the magnitude of the increases in PKA activity and the spontaneous AP firing rate were similar (0.4±0.1nM vs. 0.6±0.15nM, respectively). Moreover, the kinetics (t1/2) of the increases in PKA activity and spontaneous AP firing rate in response to β-AR stimulation or PDE inhibition were tightly linked. We characterized the system rate-limiting biochemical reactions by integrating these experimentally derived data into mechanistic-computational model. Model simulations predicted that phospholamban phosphorylation is a potent target of the increase in PKA activity that links to increase in spontaneous AP firing rate. In summary, the kinetics and stoichiometry of increases in PKA activity in response to a physiological (β-AR stimulation) or pharmacological (PDE inhibitor) stimuli match those of changes in the AP firing rate. Thus Ca2+-cAMP/PKA-dependent phosphorylation limits the rate and magnitude of increase in spontaneous AP firing rate. PMID:26241846

  4. An unusual scintigraphic pattern in sickle cell patients

    International Nuclear Information System (INIS)

    Glaser, A.M.; Chen, D.C.P.; Siegel, M.E.; Norris, S.L.; Haywood, L.J.

    1989-01-01

    We reviewed the nuclear medicine files of all patients enrolled in the sickle cell disease clinic who had had scans performed within the previous 5 years. We specifically looked for patterns of tracer uptake in these scans that would correlate with the severe anemia and consequent bone marrow hyperactivity of sickle cell patients. Thirty-three patients were included (21 men and 12 women) with a mean age of 26.8 years (range 17-48 years). The appearance of each of these patients' most recent scans was examined in the areas of the distal femurs, the proximal tibias and the distal tibias; a distinct triangular shaped pattern of increased activity was identified in these areas in a majority of patients. Thirty-three patients without sickle cell disease served as age-matched controls. This pattern was seen in 65.1% (95 out of 146 images) of the sickle cell patients' delayed images and 80.4% (82 out of 102 images) of their blood pool images. In contrast, the control patients demonstrated the triangular pattern in none of their blood pool studies (0%) and only 10.9% of their delayed bone images (P<0.001). The mean age of sickle cell patients with this pattern is 25.6 years which was significantly lower than that of those without this pattern (mean=37.5 years, P<0.05). Given the high prevalence of this unique scintigraphic pattern in a group of patients with known accelerated bone marrow function, these findings may be scintigraphic evidence of bone marrow expansion. The patient's age appears to be an important factor in visualization of this pattern. (orig.)

  5. Generating patterns from fields of cells. Examples from Drosophila segmentation.

    Science.gov (United States)

    Sanson, B

    2001-12-01

    In Drosophila, a cascade of maternal, gap, pair-rule and segment polarity genes subdivides the antero/posterior axis of the embryo into repeating segmental stripes. This review summarizes what happens next, i.e. how an intrasegmental pattern is generated and controls the differentiation of specific cell types in the epidermis. Within each segment, cells secreting the signalling molecules Wingless (the homologue of vertebrate Wnt-1) and Hedgehog are found in narrow stripes on both sides of the parasegmental boundary. The Wingless and Hedgehog organizing activities help to establish two more stripes per segment that localize ligands for the Epidermal Growth Factor and the Notch signalling pathways, respectively. These four signals then act at short range and in concert to control epidermal differentiation at the single cell level across the segment. This example from Drosophila provides a paradigm for how organizers generate precise patterns, and ultimately different cell types, in a naïve field of cells.

  6. Generation of a patterned co-culture system composed of adherent cells and immobilized nonadherent cells.

    Science.gov (United States)

    Yamazoe, Hironori; Ichikawa, Takashi; Hagihara, Yoshihisa; Iwasaki, Yasuhiko

    2016-02-01

    Patterned co-culture is a promising technique used for fundamental investigation of cell-cell communication and tissue engineering approaches. However, conventional methods are inapplicable to nonadherent cells. In this study, we aimed to establish a patterned co-culture system composed of adherent and nonadherent cells. Nonadherent cells were immobilized on a substrate using a cell membrane anchoring reagent conjugated to a protein, in order to incorporate them into the co-culture system. Cross-linked albumin film, which has unique surface properties capable of regulating protein adsorption, was used to control their spatial localization. The utility of our approach was demonstrated through the fabrication of a patterned co-culture consisting of micropatterned neuroblastoma cells surrounded by immobilized myeloid cells. Furthermore, we also created a co-culture system composed of cancer cells and immobilized monocytes. We observed that monocytes enhanced the drug sensitivity of cancer cells and its influence was limited to cancer cells located near the monocytes. Therefore, the incorporation of nonadherent cells into a patterned co-culture system is useful for creating culture systems containing immune cells, as well as investigating the influence of these immune cells on cancer drug sensitivity. Various methods have been proposed for creating patterned co-culture systems, in which multiple cell types are attached to a substrate with a desired pattern. However, conventional methods, including our previous report published in Acta Biomaterialia (2010, 6, 526-533), are unsuitable for nonadherent cells. Here, we developed a novel method that incorporates nonadherent cells into the co-culture system, which allows us to precisely manipulate and study microenvironments containing nonadherent and adherent cells. Using this technique, we demonstrated that monocytes (nonadherent cells) could enhance the drug sensitivity of cancer cells and that their influence had a

  7. Imported fire ant immunotherapy prescribing patterns in a large health care system during a 17-year period.

    Science.gov (United States)

    Haymore, Bret R; McCoy, Robert L; Nelson, Michael R

    2009-05-01

    No large evaluation has been performed of the maintenance vial concentration commonly used by physicians when prescribing imported fire ant (IFA) immunotherapy since the publication of the first Stinging Insect Hypersensitivity Practice Parameter 10 years ago. To describe the prescribing patterns for IFA immunotherapy among practicing allergists in a large health care setting and the impact of published Practice Parameter recommendations. Data from the US Army Centralized Allergen Extract Laboratory were analyzed to determine IFA immunotherapy prescribing patterns from 1990 to May 2007. This extract laboratory provides prescriptions for more than 320 US Department of Defense, US Department of Veterans Affairs, and US Public Health Service clinics. A total of 1,091 patients were given 1,437 new or revised prescriptions for IFA immunotherapy. Monotherapy for Solenopsis invicta and Solenopsis richteri was prescribed in 169 (11.8%) and 3 (0.1%) instances, respectively, with the remainder of patients given both IFA antigens. The most commonly prescribed maintenance vial dose was 0.5 mL of a 1:200 (wt/vol) dilution, accounting for 36.3% of prescriptions. A total of 17.3% of prescriptions had a maintenance vial dose of 0.5 mL of a 1:100 (wt/vol) dilution, 4.6% had a dilution of 1:10 (wt/vol), and 50.6% had a dilution between 1:10 and 1:100 (wt/vol). The mean starting dose was 4.4 10-fold dilutions below the maintenance dose (5.4 vials per treatment set). The most commonly prescribed maintenance dose was 0.5 mL of a 1:200 (wt/vol) dilution, although most prescriptions used a maintenance dose consistent with recommended dosing in the Stinging Insect Practice Parameters. Both IFA antigens were used by most physicians. Further study evaluating the effective dose range for IFA immunotherapy is needed.

  8. Cell Patterning for Liver Tissue Engineering via Dielectrophoretic Mechanisms

    Directory of Open Access Journals (Sweden)

    Wan Nurlina Wan Yahya

    2014-07-01

    Full Text Available Liver transplantation is the most common treatment for patients with end-stage liver failure. However, liver transplantation is greatly limited by a shortage of donors. Liver tissue engineering may offer an alternative by providing an implantable engineered liver. Currently, diverse types of engineering approaches for in vitro liver cell culture are available, including scaffold-based methods, microfluidic platforms, and micropatterning techniques. Active cell patterning via dielectrophoretic (DEP force showed some advantages over other methods, including high speed, ease of handling, high precision and being label-free. This article summarizes liver function and regenerative mechanisms for better understanding in developing engineered liver. We then review recent advances in liver tissue engineering techniques and focus on DEP-based cell patterning, including microelectrode design and patterning configuration.

  9. Linking stem cell function and growth pattern of intestinal organoids.

    Science.gov (United States)

    Thalheim, Torsten; Quaas, Marianne; Herberg, Maria; Braumann, Ulf-Dietrich; Kerner, Christiane; Loeffler, Markus; Aust, Gabriela; Galle, Joerg

    2018-01-15

    Intestinal stem cells (ISCs) require well-defined signals from their environment in order to carry out their specific functions. Most of these signals are provided by neighboring cells that form a stem cell niche, whose shape and cellular composition self-organize. Major features of this self-organization can be studied in ISC-derived organoid culture. In this system, manipulation of essential pathways of stem cell maintenance and differentiation results in well-described growth phenotypes. We here provide an individual cell-based model of intestinal organoids that enables a mechanistic explanation of the observed growth phenotypes. In simulation studies of the 3D structure of expanding organoids, we investigate interdependences between Wnt- and Notch-signaling which control the shape of the stem cell niche and, thus, the growth pattern of the organoids. Similar to in vitro experiments, changes of pathway activities alter the cellular composition of the organoids and, thereby, affect their shape. Exogenous Wnt enforces transitions from branched into a cyst-like growth pattern; known to occur spontaneously during long term organoid expansion. Based on our simulation results, we predict that the cyst-like pattern is associated with biomechanical changes of the cells which assign them a growth advantage. The results suggest ongoing stem cell adaptation to in vitro conditions during long term expansion by stabilizing Wnt-activity. Our study exemplifies the potential of individual cell-based modeling in unraveling links between molecular stem cell regulation and 3D growth of tissues. This kind of modeling combines experimental results in the fields of stem cell biology and cell biomechanics constituting a prerequisite for a better understanding of tissue regeneration as well as developmental processes. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Influence of atmospheric rivers on vegetation productivity and fire patterns in the southwestern U.S.

    Science.gov (United States)

    Albano, Christine M.; Dettinger, Michael; Soulard, Christopher E.

    2017-01-01

    In the southwestern U.S., the meteorological phenomenon known as atmospheric rivers (ARs) has gained increasing attention due to its strong connections to floods, snowpacks, and water supplies in the West Coast states. Relatively less is known about the ecological implications of ARs, particularly in the interior Southwest, where AR storms are less common. To address this gap, we compared a chronology of AR landfalls on the west coast between 1989 and 2011 and between 25°N and 42.5°N to annual metrics of the normalized difference vegetation index (NDVI; an indicator of vegetation productivity) and daily resolution precipitation data to assess influences of AR-fed winter precipitation on vegetation productivity across the southwestern U.S. We mapped correlations between winter AR precipitation during landfalling ARs and (1) annual maximum NDVI and (2) area burned by large wildfires summarized by ecoregion during the same year as the landfalls and during the following year. Interannual variations of AR precipitation strongly influenced both NDVI and area burned by wildfire in some dryland ecoregions. The influence of ARs on dryland vegetation varied significantly depending on the latitude of landfall, with those ARs making landfall below 35°N latitude more strongly influencing these systems, and with effects observed as far as 1300 km from the landfall location. As climatologists' understanding of the synoptic patterns associated with the occurrence of ARs continues to evolve, an increased understanding of how AR landfalls, in aggregate, influence vegetation productivity and associated wildfire activity in dryland ecosystems may provide opportunities to better predict ecological responses to climate and climate change.

  11. An 800-year fire history

    Science.gov (United States)

    Stanley G. Kitchen

    2010-01-01

    "Fire in the woods!" The words are a real heart stopper. Yet in spite of its capacity to destroy, fire plays an essential role in shaping plant communities. Knowledge of the patterns of fire over long time periods is critical for understanding this role. Trees often retain evidence of nonlethal fires in the form of injuries or scars in the annual growth rings...

  12. Ordered patterns of cell shape and orientational correlation during spontaneous cell migration.

    Directory of Open Access Journals (Sweden)

    Yusuke T Maeda

    Full Text Available BACKGROUND: In the absence of stimuli, most motile eukaryotic cells move by spontaneously coordinating cell deformation with cell movement in the absence of stimuli. Yet little is known about how cells change their own shape and how cells coordinate the deformation and movement. Here, we investigated the mechanism of spontaneous cell migration by using computational analyses. METHODOLOGY: We observed spontaneously migrating Dictyostelium cells in both a vegetative state (round cell shape and slow motion and starved one (elongated cell shape and fast motion. We then extracted regular patterns of morphological dynamics and the pattern-dependent systematic coordination with filamentous actin (F-actin and cell movement by statistical dynamic analyses. CONCLUSIONS/SIGNIFICANCE: We found that Dictyostelium cells in both vegetative and starved states commonly organize their own shape into three ordered patterns, elongation, rotation, and oscillation, in the absence of external stimuli. Further, cells inactivated for PI3-kinase (PI3K and/or PTEN did not show ordered patterns due to the lack of spatial control in pseudopodial formation in both the vegetative and starved states. We also found that spontaneous polarization was achieved in starved cells by asymmetric localization of PTEN and F-actin. This breaking of the symmetry of protein localization maintained the leading edge and considerably enhanced the persistence of directed migration, and overall random exploration was ensured by switching among the different ordered patterns. Our findings suggest that Dictyostelium cells spontaneously create the ordered patterns of cell shape mediated by PI3K/PTEN/F-actin and control the direction of cell movement by coordination with these patterns even in the absence of external stimuli.

  13. Cortisol patterns are associated with T cell activation in HIV.

    Directory of Open Access Journals (Sweden)

    Sarah Patterson

    Full Text Available The level of T cell activation in untreated HIV disease is strongly and independently associated with risk of immunologic and clinical progression. The factors that influence the level of activation, however, are not fully defined. Since endogenous glucocorticoids are important in regulating inflammation, we sought to determine whether less optimal diurnal cortisol patterns are associated with greater T cell activation.We studied 128 HIV-infected adults who were not on treatment and had a CD4(+ T cell count above 250 cells/µl. We assessed T cell activation by CD38 expression using flow cytometry, and diurnal cortisol was assessed with salivary measurements.Lower waking cortisol levels correlated with greater T cell immune activation, measured by CD38 mean fluorescent intensity, on CD4(+ T cells (r = -0.26, p = 0.006. Participants with lower waking cortisol also showed a trend toward greater activation on CD8(+ T cells (r = -0.17, p = 0.08. A greater diurnal decline in cortisol, usually considered a healthy pattern, correlated with less CD4(+ (r = 0.24, p = 0.018 and CD8(+ (r = 0.24, p = 0.017 activation.These data suggest that the hypothalamic-pituitary-adrenal (HPA axis contributes to the regulation of T cell activation in HIV. This may represent an important pathway through which psychological states and the HPA axis influence progression of HIV.

  14. Microfabricated ratchet structures for concentrating and patterning motile bacterial cells

    International Nuclear Information System (INIS)

    Kim, Sang Yub; Lee, Eun Se; Lee, Ho Jae; Lee, Se Yeon; Lee, Sung Kuk; Kim, Taesung

    2010-01-01

    We present a novel microfabricated concentrator for Escherichia coli that can be a stand-alone and self-contained microfluidic device because it utilizes the motility of cells. First of all, we characterize the motility of E. coli cells and various ratcheting structures that can guide cells to move in a desired direction in straight and circular channels. Then, we combine these ratcheting microstructures with the intrinsic tendency of cells to swim on the right side in microchannels to enhance the concentration rates up to 180 fold until the concentrators are fully filled with cells. Furthermore, we demonstrate that cells can be positioned and concentrated with a constant spacing distance on a surface, allowing spatial patterning of motile cells. These results can be applied to biosorption or biosensor devices that are powered by motile cells because they can be highly concentrated without any external mechanical and electrical energy sources. Hence, we believe that the concentrator design holds considerable potential to be applied for concentrating and patterning other motile microbes and providing a versatile structure for motility study of bacterial cells.

  15. Impact and Recovery Pattern of a Spring Fire on a Pacific Coast Marsh - Observations and Implications for Endangered Species

    Science.gov (United States)

    Brown, L. N.; Willis, K. S.; Ambrose, R. F.; MacDonald, G. M.

    2015-12-01

    The flammability of California coastal marsh vegetation is highest in winter and spring when dominant high marsh plants such as Sarcocornia pacifica are dormant. With climate change the number of cool-season fires are increasing in the state, and marsh systems are becoming more vulnerable to fire disturbance. Very little information exists in peer-reviewed or grey literature on the presence of fire in Pacific Coast tidal marshes. In 1993, the Green Meadows fire in Ventura County, California burned a small portion of tidally influenced Sarcocornia­-dominated marsh at Point Mugu. After the May 2013 Springs Fire burned a similar portion of the salt marsh vegetation, we conducted a two-year vegetation recovery survey using transects of surface vegetation plots and MODIS derived NDVI remote sensing monitoring. Recovery during the first year was limited. Sixteen months into the recovery period, percent plant coverage reached an average of approximately 60% for all plots in the burned area, as opposed to an average of 100% in control plots, and remained at that level for the duration of the study. NDVI did not approach near pre-fire conditions until 19 months after the fire. While recovery may have been influenced by California's current extreme drought conditions, the recurrence of fire and rate of recovery raise many important questions as to the role of fire in Pacific coast tidal marshes. For example, the lack of Salicornia cover over more than an entire breeding season would be detrimental to protected species such as Rallus obsoletus. Fire adds new vulnerabilities on critical tidal marsh habitat already taxed by the threat of sea-level rise, coastal squeeze and invasive species.

  16. CA1 Pyramidal Cell Theta-Burst Firing Triggers Endocannabinoid-Mediated Long-Term Depression at Both Somatic and Dendritic Inhibitory Synapses

    Science.gov (United States)

    Younts, Thomas J.; Chevaleyre, Vivien

    2013-01-01

    Endocannabinoids (eCBs) are retrograde lipid messengers that, by targeting presynaptic type 1 cannabinoid receptors (CB1Rs), mediate short- and long-term synaptic depression of neurotransmitter release throughout the brain. Short-term depression is typically triggered by postsynaptic, depolarization-induced calcium rises, whereas long-term depression is induced by synaptic activation of Gq/11 protein-coupled receptors. Here we report that a physiologically relevant pattern of postsynaptic activity, in the form of theta-burst firing (TBF) of hippocampal CA1 pyramidal neurons, can trigger long-term depression of inhibitory transmission (iLTD) in rat hippocampal slices. Paired recordings between CA1 interneurons and pyramidal cells, followed by post hoc morphological reconstructions of the interneurons' axon, revealed that somatic and dendritic inhibitory synaptic inputs equally expressed TBF-induced iLTD. Simultaneous recordings from neighboring pyramidal cells demonstrated that eCB signaling triggered by TBF was highly restricted to only a single, active cell. Furthermore, pairing submaximal endogenous activation of metabotropic glutamate or muscarinic acetylcholine receptors with submaximal TBF unmasked associative iLTD. Although CB1Rs are also expressed at Schaffer-collateral excitatory terminals, long-term plasticity under various recording conditions was spared at these synapses. Consistent with this observation, TBF also shifted the balance of excitation and inhibition in favor of excitatory throughput, thereby altering information flow through the CA1 circuit. Given the near ubiquity of burst-firing activity patterns and CB1R expression in the brain, the properties described here may be a general means by which neurons fine tune the strength of their inputs in a cell-wide and cell-specific manner. PMID:23966696

  17. Cell state switching factors and dynamical patterning modules ...

    Indian Academy of Sciences (India)

    2009-01-05

    Jan 5, 2009 ... Home; Journals; Journal of Biosciences; Volume 34; Issue 4. Cell state switching factors and dynamical patterning modules: complementary mediators of plasticity in development and evolution. Stuart A Newman Ramray Bhat Nadejda V Mezentseva. Articles Volume 34 Issue 4 October 2009 pp 553-572 ...

  18. Covalent microcontact printing of proteins fro cell patterning

    NARCIS (Netherlands)

    Rozkiewicz, D.I.; Kraan, Yvonne M.; Werten, Marc W.T.; de Wolf, Frits A.; Subramaniam, Vinod; Ravoo, B.J.; Reinhoudt, David

    2006-01-01

    We describe a straightforward approach to the covalent immobilization of cytophilic proteins by microcontact printing, which can be used to pattern cells on substrates. Cytophilic proteins are printed in micropatterns on reactive self-assembled monolayers by using imine chemistry. An

  19. Pattern of presentations seen in sickle cell retinopathy patients at ...

    African Journals Online (AJOL)

    Objective: To describe the pattern of presentation of sickle cell retinopathy patients who presented at the Eye Foundation Hospital Lagos, Nigeria between January 2002 and March 2003. Materials and Methods: The medical records of 27 patients who presented at the Eye Foundation Hospital with retinal changes due to ...

  20. Real-time relationship between PKA biochemical signal network dynamics and increased action potential firing rate in heart pacemaker cells: Kinetics of PKA activation in heart pacemaker cells.

    Science.gov (United States)

    Yaniv, Yael; Ganesan, Ambhighainath; Yang, Dongmei; Ziman, Bruce D; Lyashkov, Alexey E; Levchenko, Andre; Zhang, Jin; Lakatta, Edward G

    2015-09-01

    cAMP-PKA protein kinase is a key nodal signaling pathway that regulates a wide range of heart pacemaker cell functions. These functions are predicted to be involved in regulation of spontaneous action potential (AP) generation of these cells. Here we investigate if the kinetics and stoichiometry of increase in PKA activity match the increase in AP firing rate in response to β-adrenergic receptor (β-AR) stimulation or phosphodiesterase (PDE) inhibition, that alters the AP firing rate of heart sinoatrial pacemaker cells. In cultured adult rabbit pacemaker cells infected with an adenovirus expressing the FRET sensor AKAR3, the EC50 in response to graded increases in the intensity of β-AR stimulation (by Isoproterenol) the magnitude of the increases in PKA activity and the spontaneous AP firing rate were similar (0.4±0.1nM vs. 0.6±0.15nM, respectively). Moreover, the kinetics (t1/2) of the increases in PKA activity and spontaneous AP firing rate in response to β-AR stimulation or PDE inhibition were tightly linked. We characterized the system rate-limiting biochemical reactions by integrating these experimentally derived data into a mechanistic-computational model. Model simulations predicted that phospholamban phosphorylation is a potent target of the increase in PKA activity that links to increase in spontaneous AP firing rate. In summary, the kinetics and stoichiometry of increases in PKA activity in response to a physiological (β-AR stimulation) or pharmacological (PDE inhibitor) stimuli match those of changes in the AP firing rate. Thus Ca(2+)-cAMP/PKA-dependent phosphorylation limits the rate and magnitude of increase in spontaneous AP firing rate. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Engineering systems for the generation of patterned co-cultures for controlling cell-cell interactions.

    Science.gov (United States)

    Kaji, Hirokazu; Camci-Unal, Gulden; Langer, Robert; Khademhosseini, Ali

    2011-03-01

    Inside the body, cells lie in direct contact or in close proximity to other cell types in a tightly controlled architecture that often regulates the resulting tissue function. Therefore, tissue engineering constructs that aim to reproduce the architecture and the geometry of tissues will benefit from methods of controlling cell-cell interactions with microscale resolution. We discuss the use of microfabrication technologies for generating patterned co-cultures. In addition, we categorize patterned co-culture systems by cell type and discuss the implications of regulating cell-cell interactions in the resulting biological function of the tissues. Patterned co-cultures are a useful tool for fabricating tissue engineered constructs and for studying cell-cell interactions in vitro, because they can be used to control the degree of homotypic and heterotypic cell-cell contact. In addition, this approach can be manipulated to elucidate important factors involved in cell-matrix interactions. Patterned co-culture strategies hold significant potential to develop biomimetic structures for tissue engineering. It is expected that they would create opportunities to develop artificial tissues in the future. This article is part of a Special Issue entitled Nanotechnologies - Emerging Applications in Biomedicine. 2010 Elsevier B.V. All rights reserved.

  2. Tuning cell adhesion by direct nanostructuring silicon into cell repulsive/adhesive patterns

    Energy Technology Data Exchange (ETDEWEB)

    Premnath, Priyatha, E-mail: priyatha.premnath@ryerson.ca [Micro/Nanofabrication Laboratory, Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada); Tavangar, Amirhossein, E-mail: atavanga@ryerson.ca [Micro/Nanofabrication Laboratory, Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada); Tan, Bo, E-mail: tanbo@ryerson.ca [Nanocharacterization Laboratory, Department of Aerospace Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada); Venkatakrishnan, Krishnan, E-mail: venkat@ryerson.ca [Micro/Nanofabrication Laboratory, Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada)

    2015-09-10

    Developing platforms that allow tuning cell functionality through incorporating physical, chemical, or mechanical cues onto the material surfaces is one of the key challenges in research in the field of biomaterials. In this respect, various approaches have been proposed and numerous structures have been developed on a variety of materials. Most of these approaches, however, demand a multistep process or post-chemical treatment. Therefore, a simple approach would be desirable to develop bio-functionalized platforms for effectively modulating cell adhesion and consequently programming cell functionality without requiring any chemical or biological surface treatment. This study introduces a versatile yet simple laser approach to structure silicon (Si) chips into cytophobic/cytophilic patterns in order to modulate cell adhesion and proliferation. These patterns are fabricated on platforms through direct laser processing of Si substrates, which renders a desired computer-generated configuration into patterns. We investigate the morphology, chemistry, and wettability of the platform surfaces. Subsequently, we study the functionality of the fabricated platforms on modulating cervical cancer cells (HeLa) behaviour. The results from in vitro studies suggest that the nanostructures efficiently repel HeLa cells and drive them to migrate onto untreated sites. The study of the morphology of the cells reveals that cells evade the cytophobic area by bending and changing direction. Additionally, cell patterning, cell directionality, cell channelling, and cell trapping are achieved by developing different platforms with specific patterns. The flexibility and controllability of this approach to effectively structure Si substrates to cell-repulsive and cell-adhesive patterns offer perceptible outlook for developing bio-functionalized platforms for a variety of biomedical devices. Moreover, this approach could pave the way for developing anti-cancer platforms that selectively repel

  3. Microstructural investigations of materials for low temperature co-fired ceramic (LTCC) based fuel cell using small angle neutron scattering

    Science.gov (United States)

    Mohamed, A. A.; Ahmad, M. H.; Ibrahim, A.; Azman, A.; Alias, R.; Ambak, Z.; Shapee, S.; Putra, E. G.; Patriati, A.; Sharom, M. A.; Yazid, H.; Mamat, M. R.; Karim, J. A.; Idris, F. M.; Yazid, K.; Zin, M. R.

    2013-06-01

    The concept and the realization fuel cell based on LTCC technology require the investigations of fired LTCC microstructures. The majority of the works involved using small angle neutron scattering studies on the microstructural of LTCC ceramic tape and development of neutron tomography for future tool to visualize channels inside the fired tape. Most SANS characterization were carried out at Smarter SANS instrument at BATAN, Indonesia. Standard sample for resolving tens of micron of object size were measured using simple neutron tomography setup utilizing monochromatic SANS beam at Malaysian Nuclear Agency. The initial microstructural findings indicates that organic additives shape the final microstructural of LTCC after firing with the glassy material possibly fill the space left by the burned organic additives. The tomography results showed that 40 micron size object can be differentiated. The conductor deposited on LTCC is preliminary investigated which will later be used as support for catalyst.

  4. Microstructural investigations of materials for low temperature co-fired ceramic (LTCC) based fuel cell using small angle neutron scattering

    International Nuclear Information System (INIS)

    Mohamed, A A; Yazid, K; Ahmad, M H; Azman, A; Yazid, H; Mamat, M R; Karim, J A; Idris, F M; Zin, M R; Ibrahim, A; Alias, R; Ambak, Z; Shapee, S; Putra, E G; Patriati, A; Sharom, M A

    2013-01-01

    The concept and the realization fuel cell based on LTCC technology require the investigations of fired LTCC microstructures. The majority of the works involved using small angle neutron scattering studies on the microstructural of LTCC ceramic tape and development of neutron tomography for future tool to visualize channels inside the fired tape. Most SANS characterization were carried out at Smarter SANS instrument at BATAN, Indonesia. Standard sample for resolving tens of micron of object size were measured using simple neutron tomography setup utilizing monochromatic SANS beam at Malaysian Nuclear Agency. The initial microstructural findings indicates that organic additives shape the final microstructural of LTCC after firing with the glassy material possibly fill the space left by the burned organic additives. The tomography results showed that 40 micron size object can be differentiated. The conductor deposited on LTCC is preliminary investigated which will later be used as support for catalyst.

  5. Stochastic cellular automata model for wildland fire spread dynamics

    International Nuclear Information System (INIS)

    Maduro Almeida, Rodolfo; Macau, Elbert E N

    2011-01-01

    A stochastic cellular automata model for wildland fire spread under flat terrain and no-wind conditions is proposed and its dynamics is characterized and analyzed. One of three possible states characterizes each cell: vegetation cell, burning cell and burnt cell. The dynamics of fire spread is modeled as a stochastic event with an effective fire spread probability S which is a function of three probabilities that characterize: the proportion of vegetation cells across the lattice, the probability of a burning cell becomes burnt, and the probability of the fire spread from a burning cell to a neighboring vegetation cell. A set of simulation experiments is performed to analyze the effects of different values of the three probabilities in the fire pattern. Monte-Carlo simulations indicate that there is a critical line in the model parameter space that separates the set of parameters which a fire can propagate from those for which it cannot propagate. Finally, the relevance of the model is discussed under the light of computational experiments that illustrate the capability of the model catches both the dynamical and static qualitative properties of fire propagation.

  6. Deposition and alignment of cells on laser-patterned quartz

    International Nuclear Information System (INIS)

    George, Sajan D.; Ladiwala, Uma; Thomas, John; Bankapur, Aseefhali; Chidangil, Santhosh; Mathur, Deepak

    2014-01-01

    Linear grooves have been laser-written on quartz surfaces using ultrashort (50 fs) pulses of 800 nm light. Measurements of water contact angle indicate that laser patterning makes the quartz surface more hydrophilic. Fibroblast cells were cultured on such laser-written surfaces; they were observed to align preferentially along the direction of the laser written grooves (width ∼2 μm. Raman spectroscopy results indicate that there are no chemical changes induced in the surface upon our laser writing. Most unexpectedly, there are also no chemical changes induced in the cells that are spatially aligned along the laser-written grooves. Atomic force microscopy measurements confirm that our laser-writing induces dramatic enhancement of surface roughness along the grooves, and the cells appear to respond to this. Thus, cell alignment seems to be in response to physical cues rather than chemical signals.

  7. Patterned Cell Alignment in Response to Macroscale Curvature

    Science.gov (United States)

    Bade, Nathan; Kamien, Randall; Assoian, Richard; Stebe, Kathleen

    The formation of spatial behavior patterns in tissues is a long-standing problem in biology. Decades of research have focused on understanding how biochemical signaling and morphogen gradients establish cell patterns during development and tissue morphogenesis. Here, we show that geometry and physical cues can drive organization and pattern formation. We find that mouse embryonic fibroblasts and human vascular smooth muscle cells sense curvature differently when in monolayers than when isolated on surfaces with various amounts of Gaussian curvature. While the long, apical stress fibers within these cells align in the direction of minimum curvature on cylindrical substrates, a subpopulation of stress fibers beneath the nucleus aligns in the circumferential direction and is bent maximally. We find dramatic reorganization of the actin cytoskeleton upon activation of RhoA, which is associated with increased contractility of the fibers. Thus, stress fiber alignment is likely a result of a complex balance between energy penalties associated with stress fiber bending, contractility, and the dynamics of F-actin assembly.

  8. [Lectin-binding patterns and cell kinetics of head and neck squamous cell carcinomas].

    Science.gov (United States)

    Gotoh, T

    1991-01-01

    In order to elucidate the cell characteristics of head and neck squamous cell carcinomas, the cell kinetics and lectin binding patterns were compared with the histological classification and staging of the tumors, using surgically resected materials (maxillary sinus 10, oral cavity 21, pharynx 8, larynx 11). Eight biotinylated lectins (WGA, 1-PHA, ConA, UEA1, RCA1, SBA, DBA, PNA) were applied to the paraffin-embedded sections, and were visualized histochemically by the streptavidin-alkaline phosphatase method. The DNA contents of the isolated carcinoma cells obtained from the adjacent thick sections were evaluated using an epi-illumination cytofluorometer after propidium iodide staining. On lectin histochemistry, the binding pattern of WGA lectin was similar between carcinoma tissues and normal tissues, but the binding was more intense in well differentiated than less differentiated carcinomas. Lymph node metastasis was found to be related to the presence of cells with poor WGA-binding. In the binding patterns of the other lectins, RCA1, SBA and ConA were related to the differentiation of carcinomas, but they were not related to the TNM-classification. DNA cytofluorometry exhibited marked polyploidization, which progressed with the advancement of the clinical and pathological staging of carcinomas. However, the DNA ploidy pattern was not associated with the cell characteristics such as the degree of histological differentiation and the lectin-binding pattern, except that the appearance of aneuploidy had some relationship with the binding-patterns of UEA1 and 1-PHA.

  9. Fire History

    Data.gov (United States)

    California Department of Resources — The Fire Perimeters data consists of CDF fires 300 acres and greater in size and USFS fires 10 acres and greater throughout California from 1950 to 2002. Some fires...

  10. Fire Perimeters

    Data.gov (United States)

    California Department of Resources — The Fire Perimeters data consists of CDF fires 300 acres and greater in size and USFS fires 10 acres and greater throughout California from 1950 to 2003. Some fires...

  11. Fire Perimeters

    Data.gov (United States)

    California Natural Resource Agency — The Fire Perimeters data consists of CDF fires 300 acres and greater in size and USFS fires 10 acres and greater throughout California from 1950 to 2003. Some fires...

  12. Fire History

    Data.gov (United States)

    California Natural Resource Agency — The Fire Perimeters data consists of CDF fires 300 acres and greater in size and USFS fires 10 acres and greater throughout California from 1950 to 2002. Some fires...

  13. Shavenbaby couples patterning to epidermal cell shape control.

    Directory of Open Access Journals (Sweden)

    Hélène Chanut-Delalande

    2006-09-01

    Full Text Available It is well established that developmental programs act during embryogenesis to determine animal morphogenesis. How these developmental cues produce specific cell shape during morphogenesis, however, has remained elusive. We addressed this question by studying the morphological differentiation of the Drosophila epidermis, governed by a well-known circuit of regulators leading to a stereotyped pattern of smooth cells and cells forming actin-rich extensions (trichomes. It was shown that the transcription factor Shavenbaby plays a pivotal role in the formation of trichomes and underlies all examined cases of the evolutionary diversification of their pattern. To gain insight into the mechanisms of morphological differentiation, we sought to identify shavenbaby's downstream targets. We show here that Shavenbaby controls epidermal cell shape, through the transcriptional activation of different classes of cellular effectors, directly contributing to the organization of actin filaments, regulation of the extracellular matrix, and modification of the cuticle. Individual inactivation of shavenbaby's targets produces distinct trichome defects and only their simultaneous inactivation prevent trichome formation. Our data show that shavenbaby governs an evolutionarily conserved developmental module consisting of a set of genes collectively responsible for trichome formation, shedding new light on molecular mechanisms acting during morphogenesis and the way they can influence evolution of animal forms.

  14. Enteric neural crest cells regulate vertebrate stomach patterning and differentiation.

    Science.gov (United States)

    Faure, Sandrine; McKey, Jennifer; Sagnol, Sébastien; de Santa Barbara, Pascal

    2015-01-15

    In vertebrates, the digestive tract develops from a uniform structure where reciprocal epithelial-mesenchymal interactions pattern this complex organ into regions with specific morphologies and functions. Concomitant with these early patterning events, the primitive GI tract is colonized by the vagal enteric neural crest cells (vENCCs), a population of cells that will give rise to the enteric nervous system (ENS), the intrinsic innervation of the GI tract. The influence of vENCCs on early patterning and differentiation of the GI tract has never been evaluated. In this study, we report that a crucial number of vENCCs is required for proper chick stomach development, patterning and differentiation. We show that reducing the number of vENCCs by performing vENCC ablations induces sustained activation of the BMP and Notch pathways in the stomach mesenchyme and impairs smooth muscle development. A reduction in vENCCs also leads to the transdifferentiation of the stomach into a stomach-intestinal mixed phenotype. In addition, sustained Notch signaling activity in the stomach mesenchyme phenocopies the defects observed in vENCC-ablated stomachs, indicating that inhibition of the Notch signaling pathway is essential for stomach patterning and differentiation. Finally, we report that a crucial number of vENCCs is also required for maintenance of stomach identity and differentiation through inhibition of the Notch signaling pathway. Altogether, our data reveal that, through the regulation of mesenchyme identity, vENCCs act as a new mediator in the mesenchymal-epithelial interactions that control stomach development. © 2015. Published by The Company of Biologists Ltd.

  15. Computational cell model based on autonomous cell movement regulated by cell-cell signalling successfully recapitulates the "inside and outside" pattern of cell sorting

    Directory of Open Access Journals (Sweden)

    Ajioka Itsuki

    2007-09-01

    Full Text Available Abstract Background Development of multicellular organisms proceeds from a single fertilized egg as the combined effect of countless numbers of cellular interactions among highly dynamic cells. Since at least a reminiscent pattern of morphogenesis can be recapitulated in a reproducible manner in reaggregation cultures of dissociated embryonic cells, which is known as cell sorting, the cells themselves must possess some autonomous cell behaviors that assure specific and reproducible self-organization. Understanding of this self-organized dynamics of heterogeneous cell population seems to require some novel approaches so that the approaches bridge a gap between molecular events and morphogenesis in developmental and cell biology. A conceptual cell model in a computer may answer that purpose. We constructed a dynamical cell model based on autonomous cell behaviors, including cell shape, growth, division, adhesion, transformation, and motility as well as cell-cell signaling. The model gives some insights about what cellular behaviors make an appropriate global pattern of the cell population. Results We applied the model to "inside and outside" pattern of cell-sorting, in which two different embryonic cell types within a randomly mixed aggregate are sorted so that one cell type tends to gather in the central region of the aggregate and the other cell type surrounds the first cell type. Our model can modify the above cell behaviors by varying parameters related to them. We explored various parameter sets with which the "inside and outside" pattern could be achieved. The simulation results suggested that direction of cell movement responding to its neighborhood and the cell's mobility are important for this specific rearrangement. Conclusion We constructed an in silico cell model that mimics autonomous cell behaviors and applied it to cell sorting, which is a simple and appropriate phenomenon exhibiting self-organization of cell population. The model

  16. Global Splicing Pattern Reversion during Somatic Cell Reprogramming

    Directory of Open Access Journals (Sweden)

    Sho Ohta

    2013-10-01

    Full Text Available Alternative splicing generates multiple transcripts from a single gene, and cell-type-specific splicing profiles are important for the properties and functions of the cells. Recently, somatic cells have been shown to undergo dedifferentiation after the forced expression of transcription factors. However, it remains unclear whether somatic cell splicing is reorganized during reprogramming. Here, by combining deep sequencing with high-throughput absolute qRT-PCR, we show that somatic splicing profiles revert to pluripotent ones during reprogramming. Remarkably, the splicing pattern in pluripotent stem cells resembles that in testes, and the regulatory regions have specific characteristics in length and sequence. Furthermore, our siRNA screen has identified RNA-binding proteins that regulate splicing events in iPSCs. We have then demonstrated that two of the RNA-binding proteins, U2af1 and Srsf3, play a role in somatic cell reprogramming. Our results indicate that the drastic alteration in splicing represents part of the molecular network involved in the reprogramming process.

  17. Conditional firing probabilities in cultured neuronal networks: a stable underlying structure in widely varying spontaneous activity patterns

    NARCIS (Netherlands)

    le Feber, Jakob; Rutten, Wim; Stegenga, J.; Wolters, P.S.; Ramakers, G.J.A.; van Pelt, J.

    2007-01-01

    To properly observe induced connectivity changes after training sessions, one needs a network model that describes individual relationships in sufficient detail to enable observation of induced changes and yet reveals some kind of stability in these relationships. We analyzed spontaneous firing

  18. Fire-through Ag contact formation for crystalline Si solar cells using single-step inkjet printing.

    Science.gov (United States)

    Kim, Hyun-Gang; Cho, Sung-Bin; Chung, Bo-Mook; Huh, Joo-Youl; Yoon, Sam S

    2012-04-01

    Inkjet-printed Ag metallization is a promising method of forming front-side contacts on Si solar cells due to its non-contact printing nature and fine grid resolution. However, conventional Ag inks are unable to punch through the SiN(x) anti-reflection coating (ARC) layer on emitter Si surfaces. In this study, a novel formulation of Ag ink is examined for the formation of fire-through contacts on a SiN(x)-coated Si substrate using the single-step printing of Ag ink, followed by rapid thermal annealing at 800 degrees C. In order to formulate Ag inks with fire-through contact formation capabilities, a liquid etching agent was first formulated by dissolving metal nitrates in an organic solvent and then mixing the resulting solution with a commercial Ag nanoparticle ink at various volume ratios. During the firing process, the dissolved metal nitrates decomposed into metal oxides and acted in a similar manner to the glass frit contained in Ag pastes for screen-printed Ag metallization. The newly formulated ink with a 1 wt% loading ratio of metal oxides to Ag formed finely distributed Ag crystallites on the Si substrate after firing at 800 degrees C for 1 min.

  19. Floristic patterns and disturbance history in karri ( Eucalyptus diversicolor: Myrtaceae) forest, south-western Australia: 2. Origin, growth form and fire response

    Science.gov (United States)

    Wardell-Johnson, Grant W.; Williams, M. R.; Mellican, A. E.; Annells, A.

    2007-03-01

    We examined the influence of disturbance history on the floristic composition of a single community type in karri forest, south-western Australia. Cover-abundance of 224 plant species and six disturbance and site-based environmental variables were recorded in 91, 20 m × 20 m quadrats. Numerical taxonomic and correlation approaches were used to relate these and 10 plant species-group variables based on origin, growth form and fire response. Ordination revealed no discernable pattern of sites based on floristic composition. However, all 10 species-group variables were significantly correlated with the ordination axes. Species richness within these groups varied with category and with respect to many of the disturbance and site variables. We encountered low diversity of vascular plants at the community level and limited diversity of growth forms. Thus most species were herbs (62.1%) or shrubs (30.3%), and there were no epiphytes and few species of trees or climbers. Although many introduced species were recorded (18.3% of all taxa), virtually all (83%) were herbs that demonstrated little persistence in the community, and there was limited evidence of transformer species. Time-since-fire (and other disturbance) influenced species richness more than the number of recent past fires because of a high proportion of ephemerals associated with the immediate post-fire period. Long-lived shrubs with soil stored seed dominate numerically, and in understorey biomass in comparison with neighboring vegetation types because of their greater flexibility of response following irregular, but intense disturbance events. However, interactions between nutrient status, regeneration mechanisms and community composition may be worthy of further investigation.

  20. Patterns of expression of cell wall related genes in sugarcane

    Directory of Open Access Journals (Sweden)

    Lima D.U.

    2001-01-01

    Full Text Available Our search for genes related to cell wall metabolism in the sugarcane expressed sequence tag (SUCEST database (http://sucest.lbi.dcc.unicamp.br resulted in 3,283 reads (1% of the total reads which were grouped into 459 clusters (potential genes with an average of 7.1 reads per cluster. To more clearly display our correlation coefficients, we constructed surface maps which we used to investigate the relationship between cell wall genes and the sugarcane tissues libraries from which they came. The only significant correlations that we found between cell wall genes and/or their expression within particular libraries were neutral or synergetic. Genes related to cellulose biosynthesis were from the CesA family, and were found to be the most abundant cell wall related genes in the SUCEST database. We found that the highest number of CesA reads came from the root and stem libraries. The genes with the greatest number of reads were those involved in cell wall hydrolases (e.g. beta-1,3-glucanases, xyloglucan endo-beta-transglycosylase, beta-glucosidase and endo-beta-mannanase. Correlation analyses by surface mapping revealed that the expression of genes related to biosynthesis seems to be associated with the hydrolysis of hemicelluloses, pectin hydrolases being mainly associated with xyloglucan hydrolases. The patterns of cell wall related gene expression in sugarcane based on the number of reads per cluster reflected quite well the expected physiological characteristics of the tissues. This is the first work to provide a general view on plant cell wall metabolism through the expression of related genes in almost all the tissues of a plant at the same time. For example, developing flowers behaved similarly to both meristematic tissues and leaf-root transition zone tissues. Besides providing a basis for future research on the mechanisms of plant development which involve the cell wall, our findings will provide valuable tools for plant engineering in the

  1. The Glycoprofile Patterns of Endothelial Cells in Usual Interstitial Pneumonia

    Directory of Open Access Journals (Sweden)

    A Barkhordari

    2014-09-01

    Full Text Available [THIS ARTICLE HAS BEEN RETRACTED FOR DUPLICATE PUBLICATION] Background: The pathological classification of cryptogenic fibrosing alveolitis has been a matter of debate and controversy for histopathologists. Objective: To identify and specify the glycotypes of capillary endothelial cells in usual interstitial pneumonia (UIP compared to those found in normal tissue. Methods: Sections of formalin-fixed, paraffin-embedded blocks from 16 cases of UIP were studied by lectin histochemistry with a panel of 27 biotinylated lectins and an avidin-peroxidase revealing system. Results: High expression of several classes of glycan was seen de novo in capillary endothelial cells from patients with UIP including small complex and bi/tri-antennary bisected complex N-linked sequences bolund by Concanavalin A and erythro-phytohemagglutinin, respectively, GalNAca1 residues bound by Helix pomatia and Maclura pomifera agglutinins, and L-fucosylated derivatives of type II glycan chains recognized by Ulex europaeus agglutinin-I. Glycans bound by agglutinins from Lycopersicon esculentum (β1,4GlcNAc and Wisteria floribunda (GalNAc as well as GlcNAc oligomers bound by Phytolacca americana and succinylated Wheat Germ agglutinin were also seen in the capillary endothelial cells of UIP. In contrast, L-fucosylated derivatives of type I glycan chains were absent in cells from cases of UIP when Anguilla anguilla agglutinin was applied, unlike the situation in normal tissue. Conclusion: These results may indicate existence of two distinct populations of endothelial cell in UIP with markedly different patterns of glycosylation, reflecting a pattern of differentiation and angiogenesis, which is not detectable morphologically.

  2. Pyro-electrification of polymer membranes for cell patterning

    Energy Technology Data Exchange (ETDEWEB)

    Rega, R.; Gennari, O.; Mecozzia, L.; Grilli, S.; Pagliarulo, V.; Ferraro, P. [National Council of Research, Institute of Applied Science & Intelligent Systems (ISASI) ‘E. Caianiello’, Via Campi Flegrei 34, 80078 Pozzuoli (Italy)

    2016-05-18

    In the recent years, much attention has been devoted to the possibility of charging polymer-based materials, due to their potential in developing large-scale and inexpensive flexible thin-film technology. The availability of localized electrostatic fields is in of great interest for a huge amount of applications such as distribution of biomolecules and cells from the liquid phase. Here we report a voltage-free pyro-electrification (PE) process able to induce permanent dipoles into polymer layers; the lithium niobate (LN) crystal is the key component that plays the multi-purpose role of sustaining, heating and poling the polymer layer that is then peeled-off easily in order to have a free-standing charged membrane. The results show the fascinating application for the living cell patterning. It well known that cell behaviour is affected by chemical and topographical cues of substrate. In fact, polymers, such as polystyrene (PS) and poly(methyl methacrylate) (PMMA), are naturally cytophobic and require specific functionalization treatments in order to promote cell adhesion. Through our proposal technique, it’s possible to obtain spontaneous organization and a driven growth of SH-SY5Y cells that is solely dictated by the nature of the charge polymer surface, opening, in this way, the innovative chance to manipulate and transfer biological samples on a free-standing polymer layer [1].

  3. Algorithms for pattern recognition in images of cell cultures

    Science.gov (United States)

    Mendes, Joyce M.; Peixoto, Nathalia L.; Ramirez-Fernandez, Francisco J.

    2001-06-01

    Several applications of silicon microstructures in areas such as neurobiology and electrophysiology have been stimulating the development of microsystems with the objective of mechanical support to monitor and control several parameters in cell cultures. In this work a multi-microelectrode arrays was fabricated over a glass plate to obtain the growth of neuronal cell monitoring their behavior during cell development. To identify the neuron core and axon an approach for implementation of edge detectors algorithms associated to images is described. The necessity of efficient and reliable algorithms for image processing and interpretation is justified by its large field of applications in several areas as well as medicine, robotics, cellular biology, computational vision and pattern recognition. In this work, it is investigated the adequacy of some edge detectors algorithms such as Canny, Marr-Hildreth. Some alterations in those methods are propose to improve the identification of both cell core and axonal growth measure. We compare the operator to edge detector proposed by Canny, Marr-Hildreth operator and application of Hough Transform. For evaluation of algorithms adaptations, we developed a method for automatic cell segmentation and measurement. Our goal is to find a set of parameters defining the location of the objects to compare the original and processed images.

  4. Volatile Hydrocarbon Analysis in Blood by Headspace Solid-Phase Microextraction: The Interpretation of VHC Patterns in Fire-Related Incidents.

    Science.gov (United States)

    Waters, Brian; Hara, Kenji; Ikematsu, Natsuki; Takayama, Mio; Kashiwagi, Masayuki; Matsusue, Aya; Kubo, Shin-Ichi

    2017-05-01

    A headspace solid-phase microextraction (HS-SPME) technique was used to quantitate the concentration of volatile hydrocarbons from the blood of cadavers by cryogenic gas chromatography-mass spectroscopy. A total of 24 compounds including aromatic and aliphatic volatile hydrocarbons were analyzed by this method. The analytes in the headspace of 0.1 g of blood mixed with 1.0 mL of distilled water plus 1 µL of an internal standard solution were adsorbed onto a 100-µm polydimethylsiloxane fiber at 0°C for 15 min, and measured using a GC-MS full scan method. The limit of quantitation for the analytes ranged from 6.8 to 10 ng per 1 g of blood. This method was applied to actual autopsy cases to quantitate the level of volatile hydrocarbons (VHCs) in the blood of cadavers who died in fire-related incidents. The patterns of the VHCs revealed the presence or absence of accelerants. Petroleum-based fuels such as gasoline and kerosene were differentiated. The detection of C8-C13 aliphatic hydrocarbons indicated the presence of kerosene; the detection of C3 alkylbenzenes in the absence of C8-C13 aliphatic hydrocarbons was indicative of gasoline; and elevated levels of styrene or benzene in the absence of C3/C4 alkylbenzenes and aliphatic hydrocarbons indicated a normal construction fire. This sensitive HS-SPME method could help aid the investigation of fire-related deaths by providing a simple pattern to use for the interpretation of VHCs in human blood. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Advanced Manufacturing Technologies (AMT): Additive Manufactured Hot Fire Planning and Testing in GRC Cell 32

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this project is to hot fire test an additively manufactured thrust chamber assembly TCA (injector and thrust chamber). GRC will install the...

  6. The structure and dynamics of patterns of Benard convection cells

    International Nuclear Information System (INIS)

    Rivier, N.; Imperial Coll. of Science and Technology, London; Lausanne Univ.

    1990-08-01

    Benard-Marangoni convection, in containers with large aspect ratio, exhibits space-filling cellular structures, highly deformable, but crystallized. They contain dislocations and grain boundaries generated and moved by elementary topological transformations, and are subjected to a weak shear stress due to the earth's rotation. The cellular structure and its fluctuations are analyzed from a crystallographic viewpoint, by using two complementary approaches. One is a global analysis of cellular structures in cylindrical symmetry. Their structural stability and defect pattern are obtained as topological mode-locking of a continuous structural parameter. The other, a local, molecular dynamics of the cells, gives a realistic parametrization of the forces and the transformations by generalizing the Voronoi cell construction in one extra dimension. 23 refs., 8 figs

  7. Spatial pattern of cell geometry and cell-division orientation in zebrafish lens epithelium

    Directory of Open Access Journals (Sweden)

    Toshiaki Mochizuki

    2014-09-01

    Full Text Available Cell proliferation is a key regulator of tissue morphogenesis. We examined cell proliferation and cell division in zebrafish lens epithelium by visualizing cell-cycle phases and nuclear positions, using fluorescent-labeled geminin and histone proteins. Proliferation was low in the anterior region of lens epithelium and higher in the marginal zone anterior to the equator, suggesting that the proliferation zone, called the germinative zone, is formed in zebrafish lens. Interestingly, cell-division orientation was biased longitudinally in the anterior region, shifted from longitudinal to circumferential along the anterior–posterior axis of lens sphere, and was biased circumferentially in the peripheral region. These data suggest that cell-division orientation is spatially regulated in zebrafish lens epithelium. The Hertwig rule indicates that cells tend to divide along their long axes. Orientation of long axes and cell division were biased similarly in zebrafish lens epithelium, suggesting that cell geometry correlates with cell-division orientation. A cell adhesion molecule, E-cadherin, is expressed in lens epithelium. In a zebrafish e-cadherin mutant, the long axes and cell-division orientation were shifted more longitudinally. These data suggest that E-cadherin is required for the spatial pattern of cell geometry and cell-division orientation in zebrafish lens epithelium.

  8. Inhibition of patterned cell shape change and cell invasion by Discs large during Drosophila oogenesis

    Science.gov (United States)

    Goode, Scott; Perrimon, Norbert

    1997-01-01

    Drosophila Discs large (Dlg) is a tumor suppressor gene whose loss in epithelial tissues causes disrupted cell polarity and increased cell proliferation. A human Dlg homolog, hDlg, has been implicated in tumorigenic processes via its association with the product of the Adenomatous Polyposis Coli (APC) gene. We show for the first time that Drosophila Dlg is required to block cell invasion. Loss of dlg activity during oogenesis causes follicle cells to change shape and invade in a pattern similar to border cells, a small population of cells that break from the post-mitotic follicular epithelium during wild-type oogenesis, yet dlg mutant cells have not adopted a border cell fate. Both functional and morphological evidence indicates that cooperation between germ cell and follicle cell Dlg, probably mediated by Dlg PDZ domains, is crucial for regulating cell mixing, suggesting a novel developmental mechanism and mode of action for the Dlg family of molecules. These findings suggest that Dlg does not simply inhibit individual cell behaviors during oogenesis, but rather acts in a developmental pathway essential for blocking cell proliferation and migration in a spatio-temporally defined manner. A model for Dlg action in blocking cell invasion is presented. PMID:9334318

  9. Melanoma cells influence the differentiation pattern of human epidermal keratinocytes.

    Science.gov (United States)

    Kodet, Ondřej; Lacina, Lukáš; Krejčí, Eliška; Dvořánková, Barbora; Grim, Miloš; Štork, Jiří; Kodetová, Daniela; Vlček, Čestmír; Šáchová, Jana; Kolář, Michal; Strnad, Hynek; Smetana, Karel

    2015-01-05

    Nodular melanoma is one of the most life threatening tumors with still poor therapeutic outcome. Similarly to other tumors, permissive microenvironment is essential for melanoma progression. Features of this microenvironment are arising from molecular crosstalk between the melanoma cells (MC) and the surrounding cell populations in the context of skin tissue. Here, we study the effect of melanoma cells on human primary keratinocytes (HPK). Presence of MC is as an important modulator of the tumor microenvironment and we compare it to the effect of nonmalignant lowly differentiated cells also originating from neural crest (NCSC). Comparative morphometrical and immunohistochemical analysis of epidermis surrounding nodular melanoma (n = 100) was performed. Data were compared to results of transcriptome profiling of in vitro models, in which HPK were co-cultured with MC, normal human melanocytes, and NCSC, respectively. Differentially expressed candidate genes were verified by RT-qPCR. Biological activity of candidate proteins was assessed on cultured HPK. Epidermis surrounding nodular melanoma exhibits hyperplastic features in 90% of cases. This hyperplastic region exhibits aberrant suprabasal expression of keratin 14 accompanied by loss of keratin 10. We observe that MC and NCSC are able to increase expression of keratins 8, 14, 19, and vimentin in the co-cultured HPK. This in vitro finding partially correlates with pseudoepitheliomatous hyperplasia observed in melanoma biopsies. We provide evidence of FGF-2, CXCL-1, IL-8, and VEGF-A participation in the activity of melanoma cells on keratinocytes. We conclude that the MC are able to influence locally the differentiation pattern of keratinocytes in vivo as well as in vitro. This interaction further highlights the role of intercellular interactions in melanoma. The reciprocal role of activated keratinocytes on biology of melanoma cells shall be verified in the future.

  10. Cellulose synthesis inhibition, cell expansion, and patterns of cell wall deposition in Nitella internodes

    International Nuclear Information System (INIS)

    Richmond, P.A.; Metraux, J.P.

    1984-01-01

    The authors have investigated the pattern of wall deposition and maturation and correlated it with cell expansion and cellulose biosynthesis. The herbicide 2,6-dichlorobenzonitrile (DCB) was found to be a potent inhibitor of cellulose synthesis, but not of cell expansion in Nitella internodal cells. Although cellulose synthesis is inhibited during DCB treatment, matrix substances continue to be synthesized and deposited. The inhibition of cellulose microfibril deposition can be demonstrated by various techniques. These results demonstrate that matrix deposition is by apposition, not by intussusception, and that the previously deposited wall moves progressively outward while stretching and thinning as a result of cell expansion

  11. The use of ATSR active fire counts for estimating relative patterns of biomass burning - A study from the boreal forest region

    NARCIS (Netherlands)

    Kasischke, Eric S.; Hewson, Jennifer H.; Stocks, Brian; van der Werf, Guido; Randerson, James T.

    2003-01-01

    Satellite fire products have the potential to construct inter-annual time series of fire activity, but estimating area burned requires considering biases introduced by orbiting geometry, fire behavior, and the presence of clouds and smoke. Here we evaluated the performance of fire counts from the

  12. Patterned arrays for the efficient detection of whole cells

    Science.gov (United States)

    Alexander, Troy A.

    2006-10-01

    Surface-Enhanced-Raman-Spectroscopy (SERS) is potentially a very sensitive technique for the detection of biological agents (i.e., proteins, viruses or whole cell bacteria). However, since initial reports, its utility has not been realized. Its limited acceptance as a routine analysis technique for both chemical and biological agents is largely due to the lack of reproducible SERS-active substrates. Most established SERS substrate fabrication schemes are based on selfassembly of the metallic (typically, Au, Ag, Pt, Pd or Cu) surfaces responsible for enhancement. Further, these protocols do not lend themselves to the stringent control over the enhancing feature shape, size, and placement on a nanometer scale. SERS can be made a more robust and attractive spectroscopic technique for biological agents by developing quantifiable, highly sensitive, and highly selective SERS-active substrates. Recently, novel SERS-active substrates, fabricated from nano-patterned Si and Au have been commercialized and are easily obtained in the marketplace. Commercialized Au SERS-active substrates fabricated using semiconductor manipulation and routine metal vapor deposition techniques used for the spectral analysis of intact bacterial cells. This talk will focus on the substrate characterization (microscopic and spectral) and application towards whole cells.

  13. Cell death patterns in Arabidopsis cells subjected to four physiological stressors indicate multiple signalling pathways and cell cycle phase specificity.

    Science.gov (United States)

    Pathirana, Ranjith; West, Phillip; Hedderley, Duncan; Eason, Jocelyn

    2017-03-01

    Corpse morphology, nuclear DNA fragmentation, expression of senescence-associated genes (SAG) and cysteine protease profiles were investigated to understand cell death patterns in a cell cycle-synchronised Arabidopsis thaliana cell suspension culture treated with four physiological stressors in the late G2 phase. Within 4 h of treatment, polyethylene glycol (PEG, 20 %), mannose (100 mM) and hydrogen peroxide (2 mM) caused DNA fragmentation coinciding with cell permeability to Evans Blue (EB) and produced corpse morphology corresponding to apoptosis-like programmed cell death (AL-PCD) with cytoplasmic retraction from the cell wall. Ethylene (8 mL per 250-mL flask) caused permeability of cells to EB without concomitant nuclear DNA fragmentation and cytoplasmic retraction, suggesting necrotic cell death. Mannose inducing glycolysis block and PEG causing dehydration resulted in relatively similar patterns of upregulation of SAG suggesting similar cell death signalling pathways for these two stress factors, whereas hydrogen peroxide caused unique patterns indicating an alternate pathway for cell death induced by oxidative stress. Ethylene did not cause appreciable changes in SAG expression, confirming necrotic cell death. Expression of AtDAD, BoMT1 and AtSAG2 genes, previously shown to be associated with plant senescence, also changed rapidly during AL-PCD in cultured cells. The profiles of nine distinct cysteine protease-active bands ranging in size from ca. 21.5 to 38.5 kDa found in the control cultures were also altered after treatment with the four stressors, with mannose and PEG again producing similar patterns. Results also suggest that cysteine proteases may have a role in necrotic cell death.

  14. Development of LASER fired contacts on silicon heterojunction solar cells for the application to rear contact structures

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, D.; Desrues, T.; Ribeyron, P.J. [INES-CEA, Le Bourget du Lac (France); Orpella, A.; Martin, I.; Voz, C.; Alcubilla, R. [Grup de Recerca en Micro i Nanotecnologies, Universitat Politecnica de Catalunya, Barcelona (Spain)

    2010-04-15

    In this work, we present our progress in contacting both doped and undoped a-Si:H layers using a LASER tool and show some applications for three different HJ solar cell designs: standard (p-type), rear emitter (n-type) and back contact (n-type). First, we have fabricated 25 cm{sup 2} standard and rear emitter double heterojunction (DHJ) solar cells on planar 1-5 {omega}.cm n-type FZ c-Si wafers using intrinsic instead of the p-doped a-Si:H layers. The influence of the different parameters of the LASER firing (pitch, number of pulses and energy) has been deeply studied to find optimized conditions. Solar cells have been obtained systematically with reasonable efficiencies although we have observed that the V{sub oc} is limiting the efficiency. Finally, we have also performed the Laser Fired Contacts (LFC) on lowly-doped (p) a-Si:H layers to compare the results obtained. We have observed that the LFC of the rear emitter contact enhances both short circuit current and fill factor while keeping the same V{sub oc} (646 mV). This leads to a 0.8% absolute increase of the cell efficiency. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Psychophysiological patterns during cell phone text messaging: a preliminary study.

    Science.gov (United States)

    Lin, I-Mei; Peper, Erik

    2009-03-01

    This study investigated the psychophysiological patterns associated with cell phone text messaging (texting). Twelve college students who were very familiar with texting were monitored with surface electromyography (SEMG) from the shoulder (upper trapezius) and thumb (abductor pollicis brevis/opponens pollicis); blood volume pulse (BVP) from the middle finger, temperature from the index finger, and skin conductance (SC) from the palm of the non-texting hand; and respiration from the thorax and abdomen. The counter-balanced procedure consisted of a 2 min pre-baseline, 1 min receiving text messages, 2 min middle baseline, 1 min sending text messages and 2 min post-baseline. The results indicated that all subjects showed significant increases in respiration rate, heart rate, SC, and shoulder and thumb SEMG as compared to baseline measures. Eighty-three percentage of the participants reported hand and neck pain during texting, and held their breath and experienced arousal when receiving text messages. Subjectively, most subjects were unaware of their physiological changes. The study suggests that frequent triggering of these physiological patterns (freezing for stability and shallow breathing) may increase muscle discomfort symptoms. Thus, participants should be trained to inhibit these responses to prevent illness and discomfort.

  16. Patterns of care for metastatic renal cell carcinoma in Australia.

    Science.gov (United States)

    Day, Daphne; Kanjanapan, Yada; Kwan, Edmond; Yip, Desmond; Lawrentschuk, Nathan; Andrews, Miles; Davis, Ian D; Azad, Arun A; Rosenthal, Mark; Wong, Shirley; Johnstone, Alice; Gibbs, Peter; Tran, Ben

    2015-10-01

    To examine the patterns of care and outcomes for metastatic renal cell carcinoma (mRCC) in Australia, where there are limited reimbursed treatment options. In particular, we aim to explore prescribing patterns for first-line systemic treatment, the practice of an initial watchful-waiting approach, and the use of systemic treatments in elderly patients. Patients with mRCC undergoing treatment between 2006 and 2012 were identified from four academic hospitals in Victoria and Australian Capital Territory. Demographic, clinicopathological, treatment, and survival data were recorded by chart review. Descriptive statistics were used to report findings. Survival was estimated by the Kaplan-Meier method and compared using the log-rank test. The study was supported by a grant from Pfizer Australia. Our study identified 212 patients with mRCC for analysis. Patients were predominantly of clear cell histology (75%), Eastern Cooperative Oncology Group performance status 90 days before initiating treatment; these patients had a median OS of 56.3 months. Elderly patients (50 patients aged ≥70 years) were more likely to receive BSC alone than younger patients (46% vs 16%, P < 0.001). Of those who received systemic therapy, elderly patients were also more likely to have upfront dose reductions (30% vs 8%, P = 0.03). Our study of patients with mRCC treated in Australian centres showed that sunitinib was the most commonly prescribed systemic treatment between 2006 and 2012, associated with survival outcomes similar to pivotal studies. We also found that an initial watchful-waiting approach is commonly adopted without apparent detriment to survival. And finally, we found that age has an impact on the prescribing of systemic therapy. © 2015 The Authors BJU International © 2015 BJU International Published by John Wiley & Sons Ltd.

  17. Report of the Committee of inquiry into a fire which occurred on 18 March 1987 in a radioisotope processing cell, Building 54 at the Lucas Heights Research Laboratories

    International Nuclear Information System (INIS)

    1987-01-01

    At about 1745 hours on Wednesday, 18 March 1987 a fire occurred in a small charcoal filter inside a processing cell (hot cell) in Building 54 at the Lucas Heights Research Laboratories (LHRL). This cell was being used to process irradiated uranium to separate the radioactive isotope molybdenum-99. Some radioactive contamination escaped from the hot cell into the operating area and three AAEC officers were found to have minor radioactive contamination on their skin/hair. The majority of the radioactive material released from the fire was trapped by the main filters outside the cell. The total amounts of radioactive noble gas and of radioiodine released to the environment during the week in which the fire occurred were within the normal range of discharge and were 53% and 2.1%, respectively, of the weekly limit authorised by the NSW Department of Health. On the evidence available to it, the Committee concludes that the fire was caused by spontaneous combustion in the charcoal filter used to trap radioactive gases released by the operations in the hot cell; the mechanism causing the fire cannot be clearly established at this stage; no member of AAEC staff, NSW emergency services personnel or the general public suffered, or will suffer, any adverse health effects from radioactivity as a result of the accident

  18. Cellular pattern formation during retinal regeneration: a role for homotypic control of cell fate acquisition.

    Science.gov (United States)

    Tyler, Melinda J; Cameron, David A

    2007-02-01

    A dominant mechanism of cellular patterning in the growing fish retina is control of cell fate acquisition by negative feedback signals arising from differentiated cells. We tested the ability of a computational model of this pattern formation mechanism to simulate cellular patterns in regenerated goldfish retina. The model successfully simulated quantitative features of in vivo regenerated patterns, indicating that regenerating retina has access to and utilizes patterning mechanisms that are operational during normal growth. The atypical patterns of regenerated retina could arise in part from regenerative progenitors that, compared to normal growth progenitors, are less responsive to the feedback patterning signals.

  19. Sustained oscillations, irregular firing, and chaotic dynamics in hierarchical modular networks with mixtures of electrophysiological cell types.

    Science.gov (United States)

    Tomov, Petar; Pena, Rodrigo F O; Zaks, Michael A; Roque, Antonio C

    2014-01-01

    The cerebral cortex exhibits neural activity even in the absence of external stimuli. This self-sustained activity is characterized by irregular firing of individual neurons and population oscillations with a broad frequency range. Questions that arise in this context, are: What are the mechanisms responsible for the existence of neuronal spiking activity in the cortex without external input? Do these mechanisms depend on the structural organization of the cortical connections? Do they depend on intrinsic characteristics of the cortical neurons? To approach the answers to these questions, we have used computer simulations of cortical network models. Our networks have hierarchical modular architecture and are composed of combinations of neuron models that reproduce the firing behavior of the five main cortical electrophysiological cell classes: regular spiking (RS), chattering (CH), intrinsically bursting (IB), low threshold spiking (LTS), and fast spiking (FS). The population of excitatory neurons is built of RS cells (always present) and either CH or IB cells. Inhibitory neurons belong to the same class, either LTS or FS. Long-lived self-sustained activity states in our network simulations display irregular single neuron firing and oscillatory activity similar to experimentally measured ones. The duration of self-sustained activity strongly depends on the initial conditions, suggesting a transient chaotic regime. Extensive analysis of the self-sustained activity states showed that their lifetime expectancy increases with the number of network modules and is favored when the network is composed of excitatory neurons of the RS and CH classes combined with inhibitory neurons of the LTS class. These results indicate that the existence and properties of the self-sustained cortical activity states depend on both the topology of the network and the neuronal mixture that comprises the network.

  20. Sustained oscillations, irregular firing and chaotic dynamics in hierarchical modular networks with mixtures of electrophysiological cell types

    Directory of Open Access Journals (Sweden)

    Petar eTomov

    2014-09-01

    Full Text Available The cerebral cortex exhibits neural activity even in the absence of externalstimuli. This self-sustained activity is characterized by irregular firing ofindividual neurons and population oscillations with a broad frequency range.Questions that arise in this context, are: What are the mechanismsresponsible for the existence of neuronal spiking activity in the cortexwithout external input? Do these mechanisms depend on the structural organization of the cortical connections? Do they depend onintrinsic characteristics of the cortical neurons? To approach the answers to these questions, we have used computer simulations of cortical network models. Our networks have hierarchical modular architecture and are composedof combinations of neuron models that reproduce the firing behavior of the five main cortical electrophysiological cell classes: regular spiking (RS, chattering (CH, intrinsically bursting (IB, low threshold spiking (LTS and fast spiking (FS. The population of excitatory neurons is built of RS cells(always present and either CH or IB cells. Inhibitoryneurons belong to the same class, either LTS or FS. Long-lived self-sustained activity states in our networksimulations display irregular single neuron firing and oscillatoryactivity similar to experimentally measured ones. The duration of self-sustained activity strongly depends on the initial conditions,suggesting a transient chaotic regime. Extensive analysis of the self-sustainedactivity states showed that their lifetime expectancy increases with the numberof network modules and is favored when the network is composed of excitatory neurons of the RS and CH classes combined with inhibitory neurons of the LTS class. These results indicate that the existence and properties of the self-sustained cortical activity states depend on both the topology of the network and the neuronal mixture that comprises the network.

  1. Creating cellular patterns using genetically engineered, gold- and cell-binding polypeptides.

    Science.gov (United States)

    Li, Linying; Mo, Chia-Kuei; Chilkoti, Ashutosh; Lopez, Gabriel P; Carroll, Nick J

    2016-06-27

    Patterning cells on material surfaces is an important tool for the study of fundamental cell biology, tissue engineering, and cell-based bioassays. Here, the authors report a simple approach to pattern cells on gold patterned silicon substrates with high precision, fidelity, and stability. Cell patterning is achieved by exploiting adsorbed biopolymer orientation to either enhance (gold regions) or impede (silicon oxide regions) cell adhesion at particular locations on the patterned surface. Genetic incorporation of gold binding domains enables C-terminal chemisorption of polypeptides onto gold regions with enhanced accessibility of N-terminal cell binding domains. In contrast, the orientation of polypeptides adsorbed on the silicon oxide regions limit the accessibility of the cell binding domains. The dissimilar accessibility of cell binding domains on the gold and silicon oxide regions directs the cell adhesion in a spatially controlled manner in serum-free medium, leading to the formation of well-defined cellular patterns. The cells are confined within the polypeptide-modified gold regions and are viable for eight weeks, suggesting that bioactive polypeptide modified surfaces are suitable for long-term maintenance of patterned cells. This study demonstrates an innovative surface-engineering approach for cell patterning by exploiting distinct ligand accessibility on heterogeneous surfaces.

  2. The French fire protection concept. Vulnerability analysis

    International Nuclear Information System (INIS)

    Kaercher, M.

    1998-01-01

    The French fire protection concept is based on a principle of three levels of defence in depth: fire prevention, fire containing and fire controlling. Fire prevention is based on arrangements which prevent the fire from starting or which make difficult for the fire to start. Fire containing is based on design measures so that the fire will have no impact on the safety of the installation. For fire controlling, equipment nad personnel are on duty in order to detect, to fight and to gain control over the fire as early as possible. The French fire protection concept gives priority to fire containing based on passive structural measures. All buildings containing safety equipment are divided into fire compartments (or fire areas) and fire cells (or fire zones). Basically, a compartment houses safety equipment belonging to one division (or train) so that the other division is always available to reach the plant safe shut down or to mitigate an accident. Because there is a large number of fire compartments and fire cells, deviations from the general principle can be observed. To this reason the RCC-I (Design and Construction Rules applicable for fire protection) requires to implement an assessment of the principle of division. This assessment is called vulnerability analysis. The vulnerability analysis is usually performed at the end of the project, before erection. It is also possible to perform a vulnerability analysis in an operating nuclear power plant in the scope of a fire safety upgrading programme. In the vulnerability analysis, the functional failure of all the equipment (except for those protected by a qualified fire barrier, designed or able to withstand the fire consequences) within the fire compartment or cell, where the fire breaks out, is postulated. The potential consequences for the plant safety are analysed

  3. Vacuum-assisted Fluid Flow in Microchannels to Pattern Substrates and Cells

    Science.gov (United States)

    Shrirao, Anil B.; Kung, Frank H.; Yip, Derek; Cho, Cheul H.; Townes-Anderson, Ellen

    2014-01-01

    Substrate and cell patterning are widely used techniques in cell biology to study cell-to-cell and cell-to-substrate interactions. Conventional patterning techniques work well only with simple shapes, small areas and selected bio-materials. This paper describes a method to distribute cell suspensions as well as substrate solutions into complex, long, closed (dead-end) polydimethylsiloxane (PDMS) microchannels using negative pressure. Our method builds upon a previous vacuum-assisted method used for micromolding (Jeon, Choi et al. 1999) and successfully patterned collagen-I, fibronectin and Sal-1 substrates on glass and polystyrene surfaces, filling microchannels with lengths up to 120 mm and covering areas up to 13 × 10 mm2. Vacuum-patterned substrates were subsequently used to culture mammalian PC12 and fibroblast cells and amphibian neurons. Cells were also patterned directly by injecting cell suspensions into microchannels using vacuum. Fibroblast and neuronal cells patterned using vacuum showed normal growth and minimal cell death indicating no adverse effects of vacuum on cells. Our method fills reversibly sealed PDMS microchannels. This enables the user to remove the PDMS microchannel cast and access the patterned biomaterial or cells for further experimental purposes. Overall, this is a straightforward technique that has broad applicability for cell biology. PMID:24989641

  4. Evidence of fuels management and fire weather influencing fire severity in an extreme fire event

    Science.gov (United States)

    Lydersen, Jamie M; Collins, Brandon M.; Brooks, Matthew L.; Matchett, John R.; Shive, Kristen L.; Povak, Nicholas A.; Kane, Van R.; Smith, Douglas F.

    2017-01-01

    Following changes in vegetation structure and pattern, along with a changing climate, large wildfire incidence has increased in forests throughout the western U.S. Given this increase there is great interest in whether fuels treatments and previous wildfire can alter fire severity patterns in large wildfires. We assessed the relative influence of previous fuels treatments (including wildfire), fire weather, vegetation and water balance on fire severity in the Rim Fire of 2013. We did this at three different spatial scales to investigate whether the influences on fire severity changed across scales. Both fuels treatments and previous low to moderate severity wildfire reduced the prevalence of high severity fire. In general, areas without recent fuels treatments and areas that previously burned at high severity tended to have a greater proportion of high severity fire in the Rim Fire. Areas treated with prescribed fire, especially when combined with thinning, had the lowest proportions of high severity. Proportion of the landscape burned at high severity was most strongly influenced by fire weather and proportional area previously treated for fuels or burned by low to moderate severity wildfire. The proportion treated needed to effectively reduce the amount of high fire severity fire varied by spatial scale of analysis, with smaller spatial scales requiring a greater proportion treated to see an effect on fire severity. When moderate and high severity fire encountered a previously treated area, fire severity was significantly reduced in the treated area relative to the adjacent untreated area. Our results show that fuels treatments and low to moderate severity wildfire can reduce fire severity in a subsequent wildfire, even when burning under fire growth conditions. These results serve as further evidence that both fuels treatments and lower severity wildfire can increase forest resilience.

  5. Patterning of stomata in the moss Funaria: a simple way to space guard cells

    OpenAIRE

    Merced, Amelia; Renzaglia, Karen S.

    2016-01-01

    Background and Aims Studies on stomatal development and the molecular mechanisms controlling patterning have provided new insights into cell signalling, cell fate determination and the evolution of these processes in plants. To fill a major gap in knowledge of stomatal patterning, this study describes the pattern of cell divisions that give rise to stomata and the underlying anatomical changes that occur during sporophyte development in the moss Funaria.

  6. Three-dimensional cell manipulation and patterning using dielectrophoresis via a multi-layer scaffold structure.

    Science.gov (United States)

    Chu, H K; Huan, Z; Mills, J K; Yang, J; Sun, D

    2015-02-07

    Cell manipulation is imperative to the areas of cellular biology and tissue engineering, providing them a useful tool for patterning cells into cellular patterns for different analyses and applications. This paper presents a novel approach to perform three-dimensional (3D) cell manipulation and patterning with a multi-layer engineered scaffold. This scaffold structure employed dielectrophoresis as the non-contact mechanism to manipulate cells in the 3D domain. Through establishing electric fields via this multi-layer structure, the cells in the medium became polarized and were attracted towards the interior part of the structure, forming 3D cellular patterns. Experiments were conducted to evaluate the manipulation and the patterning processes with the proposed structure. Results show that with the presence of a voltage input, this multi-layer structure was capable of manipulating different types of biological cells examined through dielectrophoresis, enabling automatic cell patterning in the time-scale of minutes. The effects of the voltage input on the resultant cellular pattern were examined and discussed. Viability test was performed after the patterning operation and the results confirmed that majority of the cells remained viable. After 7 days of culture, 3D cellular patterns were observed through SEM. The results suggest that this scaffold and its automated dielectrophoresis-based patterning mechanism can be used to construct artificial tissues for various tissue engineering applications.

  7. Evaluation of the periodontal regenerative properties of patterned human periodontal ligament stem cell sheets.

    Science.gov (United States)

    Kim, Joong-Hyun; Ko, Seok-Yeong; Lee, Justin Ho; Kim, Deok-Ho; Yun, Jeong-Ho

    2017-12-01

    The aim of this study was to determine the effects of patterned human periodontal ligament stem cell (hPDLSC) sheets fabricated using a thermoresponsive substratum. In this study, we fabricated patterned hPDLSC sheets using nanotopographical cues to modulate the alignment of the cell sheet. The hPDLSCs showed rapid monolayer formation on various surface pattern widths. Compared to cell sheets grown on flat surfaces, there were no significant differences in cell attachment and growth on the nanopatterned substratum. However, the patterned hPDLSC sheets showed higher periodontal ligamentogenesis-related gene expression in early stages than the unpatterned cell sheets. This experiment confirmed that patterned cell sheets provide flexibility in designing hPDLSC sheets, and that these stem cell sheets may be candidates for application in periodontal regenerative therapy.

  8. Pattern of failure following surgical resection of renal cell carcinoma

    International Nuclear Information System (INIS)

    Aref, I.; Bociek, G.; Salhani, D.

    1996-01-01

    Purpose/objective: To identify the pattern of failure in patients with resected renal cell carcinoma (RCC). Materials and Methods: The records of 116 patients with unilateral non-metastatic RCC, who were treated with definitive surgery and referred to the Ottawa Regional Cancer Centre between 1977 and 1988, were reviewed. Distribution by stage included: T1 = 3 patients, T2 = 42 patients, T3 =71 patients. The median follow-up was 44 months, with a range of 4-267 months. Results: Loco-regional failure (LRF) developed in 8 patients, yielding a 7-year actuarial incidence of 8% for LRF, as first event. Nine patients developed local or regional recurrence + distant failure, and 58 patients had distant metastases only. Seven-year actuarial incidence of distant failure was 55%. The overall 7-year actuarial survival rate was 40%, and cause-specific survival was 45%. Conclusion: LRF was rare following nephrectomy. This data does not support the role of adjuvant radiation therapy in this disease

  9. Evidence of fuels management and fire weather influencing fire severity in an extreme fire event.

    Science.gov (United States)

    Lydersen, Jamie M; Collins, Brandon M; Brooks, Matthew L; Matchett, John R; Shive, Kristen L; Povak, Nicholas A; Kane, Van R; Smith, Douglas F

    2017-10-01

    Following changes in vegetation structure and pattern, along with a changing climate, large wildfire incidence has increased in forests throughout the western United States. Given this increase, there is great interest in whether fuels treatments and previous wildfire can alter fire severity patterns in large wildfires. We assessed the relative influence of previous fuels treatments (including wildfire), fire weather, vegetation, and water balance on fire-severity in the Rim Fire of 2013. We did this at three different spatial scales to investigate whether the influences on fire severity changed across scales. Both fuels treatments and previous low to moderate-severity wildfire reduced the prevalence of high-severity fire. In general, areas without recent fuels treatments and areas that previously burned at high severity tended to have a greater proportion of high-severity fire in the Rim Fire. Areas treated with prescribed fire, especially when combined with thinning, had the lowest proportions of high severity. The proportion of the landscape burned at high severity was most strongly influenced by fire weather and proportional area previously treated for fuels or burned by low to moderate severity wildfire. The proportion treated needed to effectively reduce the amount of high severity fire varied by spatial scale of analysis, with smaller spatial scales requiring a greater proportion treated to see an effect on fire severity. When moderate and high-severity fire encountered a previously treated area, fire severity was significantly reduced in the treated area relative to the adjacent untreated area. Our results show that fuels treatments and low to moderate-severity wildfire can reduce fire severity in a subsequent wildfire, even when burning under fire growth conditions. These results serve as further evidence that both fuels treatments and lower severity wildfire can increase forest resilience. © 2017 by the Ecological Society of America.

  10. MODIS NDVI Response Following Fires in Siberia

    Science.gov (United States)

    Ranson, K. Jon; Sun, G.; Kovacs, K.; Kharuk, V. I.

    2003-01-01

    The Siberian boreal forest is considered a carbon sink but may become an important source of carbon dioxide if climatic warming predictions are correct. The forest is continually changing through various disturbance mechanisms such as insects, logging, mineral exploitation, and especially fires. Patterns of disturbance and forest recovery processes are important factors regulating carbon flux in this area. NASA's Terra MODIS provides useful information for assessing location of fires and post fire changes in forests. MODIS fire (MOD14), and NDVI (MOD13) products were used to examine fire occurrence and post fire variability in vegetation cover as indicated by NDVI. Results were interpreted for various post fire outcomes, such as decreased NDVI after fire, no change in NDVI after fire and positive NDVI change after fire. The fire frequency data were also evaluated in terms of proximity to population centers, and transportation networks.

  11. Patterns of cell proliferation and cell death in the developing retina and optic tectum of the brown trout.

    NARCIS (Netherlands)

    Candal, E.; Anadon, R.; Grip, W.J. de; Rodriguez-Moldes, I.

    2005-01-01

    We have analyzed the patterns of cell proliferation and cell death in the retina and optic tectum of the brown trout (Salmo trutta fario) throughout embryonic and postembryonic stages. Cell proliferation was detected by immunohistochemistry with an antibody against the proliferating cell nuclear

  12. Synoptic weather types associated with critical fire weather

    Science.gov (United States)

    Mark J. Schroeder; Monte Glovinsky; Virgil F. Hendricks; Frank C. Hood; Melvin K. Hull; Henry L. Jacobson; Robert Kirkpatrick; Daniel W. Krueger; Lester P. Mallory; Albert G. Oeztel; Robert H. Reese; Leo A. Sergius; Charles E. Syverson

    1964-01-01

    Recognizing that weather is an important factor in the spread of both urban and wildland fires, a study was made of the synoptic weather patterns and types which produce strong winds, low relative humidities, high temperatures, and lack of rainfall--the conditions conducive to rapid fire spread. Such historic fires as the San Francisco fire of 1906, the Berkeley fire...

  13. Climatic and weather factors affecting fire occurrence and behavior

    Science.gov (United States)

    Randall P. Benson; John O. Roads; David R. Weise

    2009-01-01

    Weather and climate have a profound influence on wildland fire ignition potential, fire behavior, and fire severity. Local weather and climate are affected by large-scale patterns of winds over the hemispheres that predispose wildland fuels to fire. The characteristics of wildland fuels, especially the moisture content, ultimately determine fire behavior and the impact...

  14. Fire ecology of the forest habitat types of northern Idaho

    Science.gov (United States)

    Jane Kapler Smith; William C. Fischer

    1997-01-01

    Provides information on fire ecology in forest habitat and community types occurring in northern Idaho. Identifies fire groups based on presettlement fire regimes and patterns of succession and stand development after fire. Describes forest fuels and suggests considerations for fire management.

  15. Shift in fire-ecosystems and weather changes

    Science.gov (United States)

    Bongani Finiza

    2013-01-01

    During recent decades too much focus fell on fire suppression and fire engineering methods. Little attention has been given to understanding the shift in the changing fire weather resulting from the global change in weather patterns. Weather change have gradually changed the way vegetation cover respond to fire occurrence and brought about changes in fire behavior and...

  16. Fire protection

    International Nuclear Information System (INIS)

    Janetzky, E.

    1980-01-01

    Safety and fire prevention measurements have to be treated like the activities developing, planning, construction and erection. Therefore it is necessary that these measurements have to be integrated into the activities mentioned above at an early stage in order to guarantee their effectiveness. With regard to fire accidents the statistics of the insurance companies concerned show that the damage caused increased in the last years mainly due to high concentration of material. Organization of fire prevention and fire fighting, reasons of fire break out, characteristics and behaviour of fire, smoke and fire detection, smoke and heat venting, fire extinguishers (portable and stationary), construction material in presence of fire, respiratory protection etc. will be discussed. (orig./RW)

  17. Fire weather and likelihood: characterizing climate space for fire occurrence and extent in Puerto Rico

    Science.gov (United States)

    Ashley E. Van Beusekom; William A. Gould; A. Carolina Monmany; Azad Henareh Khalyani; Maya Quiñones; Stephen J. Fain; Maria José Andrade-Núñez; Grizelle González

    2017-01-01

    Abstract Assessing the relationships between weather patterns and the likelihood of fire occurrence in the Caribbean has not been as central to climate change research as in temperate regions, due in part to the smaller extent of individual fires. However, the cumulative effect of small frequent fires can shape large landscapes, and fire-prone ecosystems are abundant...

  18. Wildland fire as a self-regulating mechanism: the role of previous burns and weather in limiting fire progression

    Science.gov (United States)

    Sean A. Parks; Lisa M. Holsinger; Carol Miller; Cara R. Nelson

    2015-01-01

    Theory suggests that natural fire regimes can result in landscapes that are both self-regulating and resilient to fire. For example, because fires consume fuel, they may create barriers to the spread of future fires, thereby regulating fire size. Top-down controls such as weather, however, can weaken this effect. While empirical examples demonstrating this pattern-...

  19. Liver-cell patterning lab chip: mimicking the morphology of liver lobule tissue.

    Science.gov (United States)

    Ho, Chen-Ta; Lin, Ruei-Zeng; Chen, Rong-Jhe; Chin, Chung-Kuang; Gong, Song-En; Chang, Hwan-You; Peng, Hwei-Ling; Hsu, Long; Yew, Tri-Rung; Chang, Shau-Feng; Liu, Cheng-Hsien

    2013-09-21

    A lobule-mimetic cell-patterning technique for on-chip reconstruction of centimetre-scale liver tissue of heterogeneous hepatic and endothelial cells via an enhanced field-induced dielectrophoresis (DEP) trap is demonstrated and reported. By mimicking the basic morphology of liver tissue, the classic hepatic lobule, the lobule-mimetic-stellate-electrodes array was designed for cell patterning. Through DEP manipulation, well-defined and enhanced spatial electric field gradients were created for in-parallel manipulation of massive individual cells. With this liver-cell patterning labchip design, the original randomly distributed hepatic and endothelial cells inside the microfluidic chamber can be manipulated separately and aligned into the desired pattern that mimicks the morphology of liver lobule tissue. Experimental results showed that both hepatic and endothelial cells were orderly guided, snared, and aligned along the field-induced orientation to form the lobule-mimetic pattern. About 95% cell viability of hepatic and endothelial cells was also observed after cell-patterning demonstration via a fluorescent assay technique. The liver function of CYP450-1A1 enzyme activity showed an 80% enhancement for our engineered liver tissue (HepG2+HUVECs) compared to the non-patterned pure HepG2 for two-day culturing.

  20. Early stage hot spot analysis through standard cell base random pattern generation

    Science.gov (United States)

    Jeon, Joong-Won; Song, Jaewan; Kim, Jeong-Lim; Park, Seongyul; Yang, Seung-Hune; Lee, Sooryong; Kang, Hokyu; Madkour, Kareem; ElManhawy, Wael; Lee, SeungJo; Kwan, Joe

    2017-04-01

    Due to limited availability of DRC clean patterns during the process and RET recipe development, OPC recipes are not tested with high pattern coverage. Various kinds of pattern can help OPC engineer to detect sensitive patterns to lithographic effects. Random pattern generation is needed to secure robust OPC recipe. However, simple random patterns without considering real product layout style can't cover patterning hotspot in production levels. It is not effective to use them for OPC optimization thus it is important to generate random patterns similar to real product patterns. This paper presents a strategy for generating random patterns based on design architecture information and preventing hotspot in early process development stage through a tool called Layout Schema Generator (LSG). Using LSG, we generate standard cell based on random patterns reflecting real design cell structure - fin pitch, gate pitch and cell height. The output standard cells from LSG are applied to an analysis methodology to assess their hotspot severity by assigning a score according to their optical image parameters - NILS, MEEF, %PV band and thus potential hotspots can be defined by determining their ranking. This flow is demonstrated on Samsung 7nm technology optimizing OPC recipe and early enough in the process avoiding using problematic patterns.

  1. Effects of potassium concentration on firing patterns of low-calcium epileptiform activity in anesthetized rat hippocampus: inducing of persistent spike activity.

    Science.gov (United States)

    Feng, Zhouyan; Durand, Dominique M

    2006-04-01

    It has been shown that a low-calcium high-potassium solution can generate ictal-like epileptiform activity in vitro and in vivo. Moreover, during status epileptiform activity, the concentration of [K+]o increases, and the concentration of [Ca2+]o decreases in brain tissue. Therefore we tested the hypothesis that long-lasting persistent spike activity, similar to one of the patterns of status epilepticus, could be generated by a high-potassium, low-calcium solution in the hippocampus in vivo. Artificial cerebrospinal fluid was perfused over the surface of the exposed left dorsal hippocampus of anesthetized rats. A stimulating electrode and a recording probe were placed in the CA1 region. By elevating K+ concentration from 6 to 12 mM in the perfusate solution, the typical firing pattern of low-calcium ictal bursts was transformed into persistent spike activity in the CA1 region with synaptic transmission being suppressed by calcium chelator EGTA. The activity was characterized by double spikes repeated at a frequency approximately 4 Hz that could last for >1 h. The analysis of multiple unit activity showed that both elevating [K+]o and lowering [Ca2+]o decreased the inhibition period after the response of paired-pulse stimulation, indicating a suppression of the after-hyperpolarization (AHP) activity. These results suggest that persistent status epilepticus-like spike activity can be induced by nonsynaptic mechanisms when synaptic transmission is blocked. The unique double-spike pattern of this activity is presumably caused by higher K+ concentration augmenting the frequency of typical low-calcium nonsynaptic burst activity.

  2. Differential and Cooperative Cell Adhesion Regulates Cellular Pattern in Sensory Epithelia.

    Science.gov (United States)

    Togashi, Hideru

    2016-01-01

    Animal tissues are composed of multiple cell types arranged in complex and elaborate patterns. In sensory epithelia, including the auditory epithelium and olfactory epithelium, different types of cells are arranged in unique mosaic patterns. These mosaic patterns are evolutionarily conserved, and are thought to be important for hearing and olfaction. Recent progress has provided accumulating evidence that the cellular pattern formation in epithelia involves cell rearrangements, movements, and shape changes. These morphogenetic processes are largely mediated by intercellular adhesion systems. Differential adhesion and cortical tension have been proposed to promote cell rearrangements. Many different types of cells in tissues express various types of cell adhesion molecules. Although cooperative mechanisms between multiple adhesive systems are likely to contribute to the production of complex cell patterns, our current understanding of the cooperative roles between multiple adhesion systems is insufficient to entirely explain the complex mechanisms underlying cellular patterning. Recent studies have revealed that nectins, in cooperation with cadherins, are crucial for the mosaic cellular patterning in sensory organs. The nectin and cadherin systems are interacted with one another, and these interactions provide cells with differential adhesive affinities for complex cellular pattern formations in sensory epithelia, which cannot be achieved by a single mechanism.

  3. Fire investigation

    Science.gov (United States)

    Gomberg, A.

    There was considerable progress made on several fronts of fire investigation in the United States in recent years. Progress was made in increasing the quantity of fire investigation and reporting, through efforts to develop the National Fire Incident Reporting System. Improving overall quality of fire investigation is the objective of efforts such as the Fire Investigation Handbook, which was developed and published by the National Bureau of Standards, and the upgrading and expanding of the ""dictionary'' of fire investigation and reporting, the NFPA 901, Uniform Coding for Fire Protection, system. The science of fire investigation as furthered also by new approaches to post fire interviews being developed at the University of Washington, and by in-depth research into factors involved in several large loss fires, including the MGM Grand Hotel in Las Vegas. Finally, the use of special study fire investigations - in-depth investigations concentrating on specific fire problems - is producing new glimpses into the nature of the national fire problem. A brief description of the status of efforts in each of these areas is discussed.

  4. Developmental heterogeneity in DNA packaging patterns influences T-cell activation and transmigration.

    Directory of Open Access Journals (Sweden)

    Soumya Gupta

    Full Text Available Cellular differentiation programs are accompanied by large-scale changes in nuclear organization and gene expression. In this context, accompanying transitions in chromatin assembly that facilitates changes in gene expression and cell behavior in a developmental system are poorly understood. Here, we address this gap and map structural changes in chromatin organization during murine T-cell development, to describe an unusual heterogeneity in chromatin organization and associated functional correlates in T-cell lineage. Confocal imaging of DNA assembly in cells isolated from bone marrow, thymus and spleen reveal the emergence of heterogeneous patterns in DNA organization in mature T-cells following their exit from the thymus. The central DNA pattern dominated in immature precursor cells in the thymus whereas both central and peripheral DNA patterns were observed in naïve and memory cells in circulation. Naïve T-cells with central DNA patterns exhibited higher mechanical pliability in response to compressive loads in vitro and transmigration assays in vivo, and demonstrated accelerated expression of activation-induced marker CD69. T-cell activation was characterized by marked redistribution of DNA assembly to a central DNA pattern and increased nuclear size. Notably, heterogeneity in DNA patterns recovered in cells induced into quiescence in culture, suggesting an internal regulatory mechanism for chromatin reorganization. Taken together, our results uncover an important component of plasticity in nuclear organization, reflected in chromatin assembly, during T-cell development, differentiation and transmigration.

  5. Pigment cell interactions and differential xanthophore recruitment underlying zebrafish stripe reiteration and Danio pattern evolution.

    Science.gov (United States)

    Patterson, Larissa B; Bain, Emily J; Parichy, David M

    2014-11-06

    Fishes have diverse pigment patterns, yet mechanisms of pattern evolution remain poorly understood. In zebrafish, Danio rerio, pigment-cell autonomous interactions generate dark stripes of melanophores that alternate with light interstripes of xanthophores and iridophores. Here, we identify mechanisms underlying the evolution of a uniform pattern in D. albolineatus in which all three pigment cell classes are intermingled. We show that in this species xanthophores differentiate precociously over a wider area, and that cis regulatory evolution has increased expression of xanthogenic Colony Stimulating Factor-1 (Csf1). Expressing Csf1 similarly in D. rerio has cascading effects, driving the intermingling of all three pigment cell classes and resulting in the loss of stripes, as in D. albolineatus. Our results identify novel mechanisms of pattern development and illustrate how pattern diversity can be generated when a core network of pigment-cell autonomous interactions is coupled with changes in pigment cell differentiation.

  6. Fire Stations

    Data.gov (United States)

    Department of Homeland Security — Fire Stations in the United States Any location where fire fighters are stationed or based out of, or where equipment that such personnel use in carrying out their...

  7. Embryonic control of epidermal cell patterning in the root and hypocotyl of Arabidopsis.

    Science.gov (United States)

    Lin, Y; Schiefelbein, J

    2001-10-01

    A position-dependent pattern of epidermal cell types is produced during the development of the Arabidopsis seedling root and hypocotyl. To understand the origin and regulation of this patterning mechanism, we have examined the embryonic expression of the GLABRA2 (GL2) gene, which encodes a cell-type-specific transcription factor. Using in situ RNA hybridization and a sensitive GL2::GFP reporter, we discovered that a position-dependent pattern of GL2 expression is established within protodermal cells at the heart stage and is maintained throughout the remainder of embryogenesis. In addition, we show that an exceptional GL2 expression character and epidermal cell pattern arises during development of the root-hypocotyl junction, which represents an anatomical transition zone. Furthermore, we find that two of the genes regulating seedling epidermal patterning, TRANSPARENT TESTA GLABRA (TTG) and WEREWOLF (WER), also control the embryonic GL2 pattern, whereas the CAPRICE (CPC) and GL2 genes are not required to establish this pattern. These results indicate that position-dependent patterning of epidermal cell types begins at an early stage of embryogenesis, before formation of the apical meristems and shortly after the cellular anatomy of the protoderm and outer ground tissue layer is established. Thus, epidermal cell specification in the Arabidopsis seedling relies on the embryonic establishment of a patterning mechanism that is perpetuated postembryonically.

  8. Embryo cell allocation patterns are not altered by biopsy but can be linked with further development.

    Science.gov (United States)

    Sepulveda-Rincon, L P; Islam, N; Marsters, P; Campbell, B K; Beaujean, N; Maalouf, W E

    2017-12-01

    It has been suggested that first embryo cleavage can be related with the embryonic-abembryonic axis at blastocyst stage in mice. Thus, cells of the 2-cell embryo might be already biased to form the inner cell mass or trophectoderm. This study was conducted to observe the possible effects of embryo biopsy on cell allocation patterns during embryo preimplantation in two different mouse strains and the effects of these patterns on further development. First, one blastomere of the 2-cell embryo was injected with a lipophilic tracer and cell allocation patterns were observed at blastocyst stage. Blastocysts were classified into orthogonal, deviant or random pattern. For the first experiment, embryos were biopsied at 8-cell stage and total cell counts (TCC) were annotated. Furthermore, non-biopsied blastocysts were transferred into foster mothers. Then, pups and their organs were weighed two weeks after birth. Random pattern was significantly recurrent (≈60%), against orthogonal (patterns among groups. These patterns were not affected by biopsy procedure. However, TCC on deviant embryos were reduced after biopsy. Moreover, no differences were found between patterns for implantation rates, litter size, live offspring and organ weights (lungs, liver, pancreas and spleen). However, deviant pups presented heavier hearts and orthogonal pups presented lighter kidneys among the group. In conclusion, these results suggest that single blastomere removal does not disturb cell allocation patterns during pre-implantation. Nonetheless, the results suggest that embryos following different cell allocation patterns present different coping mechanisms against in vitro manipulations and further development might be altered. © 2017 Society for Reproduction and Fertility.

  9. Proceedings of the joint contractors meeting: FE/EE Advanced Turbine Systems conference FE fuel cells and coal-fired heat engines conference

    Energy Technology Data Exchange (ETDEWEB)

    Geiling, D.W. [ed.

    1993-08-01

    The joint contractors meeting: FE/EE Advanced Turbine Systems conference FEE fuel cells and coal-fired heat engines conference; was sponsored by the US Department of Energy Office of Fossil Energy and held at the Morgantown Energy Technology Center, P.O. Box 880, Morgantown, West Virginia 26507-0880, August 3--5, 1993. Individual papers have been entered separately.

  10. Symmetric synaptic patterns between starburst amacrine cells and direction selective ganglion cells in the rabbit retina.

    Science.gov (United States)

    Chen, Yung-Cheng; Chiao, Chuan-Chin

    2008-05-01

    Inputs from starburst amacrine cells (SACs) to ON-OFF direction selective ganglion cells (DSGCs) in the rabbit retina are themselves directional. However, the synaptic asymmetry between SACs and DSGCs required for generating direction selectivity has been controversial. We investigated dendritic contacts and distribution of inhibitory synapses between SACs and their overlapped DSGCs. Double injection of SAC/DSGC pairs and quantitative analysis revealed no obvious asymmetry of dendritic contacts between SACs and DSGCs. Furthermore, examination of the inhibitory input pattern on the dendrites of DSGCs using antibodies against GABA(A) receptors also suggested an isotropic arrangement with the overlapping SACs in both the preferred and the null directions. Therefore, the presynaptic mechanism of direction selectivity upon DSGCs may not result from a simple asymmetric arrangement with overlapping SACs. Multiple layer interactions and sophisticated synaptic connections between SACs and DSGCs are necessary. (c) 2008 Wiley-Liss, Inc.

  11. US Fire Administration Fire Statistics

    Data.gov (United States)

    Department of Homeland Security — The U.S. Fire Administration collects data from a variety of sources to provide information and analyses on the status and scope of the fire problem in the United...

  12. Cell state switching factors and dynamical patterning modules ...

    Indian Academy of Sciences (India)

    Prakash

    this, other DPMs (defined as physical forces and processes pertinent to the scale of the aggregates mobilized by a ... Adhesion; cell polarity; lateral inhibition; physical mechanisms of morphogenesis ...... micromass culture of 5-day leg bud apical zone limb mesenchymal cells, visualized by staining with Alcian blue. The cells ...

  13. Levels and patterns of polycyclic aromatic hydrocarbons in coal-fired power plant bottom ash and fly ash from Huainan, China.

    Science.gov (United States)

    Ruwei, Wang; Jiamei, Zhang; Jingjing, Liu; Liu, Guijian

    2013-08-01

    Fly ash and bottom ash samples were collected from a coal-fired power plant located in Anhui province, China. Mineral phases and morphologies of the samples were determined by X-ray diffraction and scanning electron microscopy, respectively. Sixteen polycyclic aromatic hydrocarbon (PAH; 16 compounds specified in United States Environmental Protection Agency Method 610) properties in ash samples were investigated. In fly ashes, ∑16PAH (total amount of 16 PAHs) and ∑CPAH (total amount of 8 carcinogenic PAHs) levels varied from 0.93 to 2.08 μg/g and from 0.26 to 0.87 μg/g, respectively. In bottom ashes, ∑16PAH and ∑CPAH levels varied from 2.83 to 5.32 and 1.76 to 3.76 μg/g, respectively. Fly ashes were dominated by medium molecular-weight PAHs and low molecular-weight PAHs, whereas bottom ashes were abundant in 5- and 6-ring PAH species. The CPAHs levels of some ashes, especially bottom ashes, are greater than the limits regulated by several countries, indicating that this type of coal combustion product requires special treatment before landfill. PAH levels and patterns in fly ash were evidently affected by particle size, and total organic content had a closer correlation with PAH content than particle size in bottom and fly ash, which may be due to unburned carbon existing in bottom ash.

  14. Effect of broadcast baiting on abundance patterns of red imported fire ants (Hymenoptera: Formicidae) and key local ant genera at long-term monitoring sites in Brisbane, Australia.

    Science.gov (United States)

    McNaught, Melinda K; Wylie, F Ross; Harris, Evan J; Alston, Clair L; Burwell, Chris J; Jennings, Craig

    2014-08-01

    In 2001, the red imported fire ant (Solenopsis invicta Buren) was identified in Brisbane, Australia. An eradication program involving broadcast bait treatment with two insect growth regulators and a metabolic inhibitor began in September of that year and is currently ongoing. To gauge the impacts of these treatments on local ant populations, we examined long-term monitoring data and quantified abundance patterns of S. invicta and common local ant genera using a linear mixed-effects model. For S. invicta, presence in pitfalls reduced over time to zero on every site. Significantly higher numbers of S. invicta workers were collected on high-density polygyne sites, which took longer to disinfest compared with monogyne and low-density polygyne sites. For local ants, nine genus groups of the 10 most common genera analyzed either increased in abundance or showed no significant trend. Five of these genus groups were significantly less abundant at the start of monitoring on high-density polygyne sites compared with monogyne and low-density polygyne sites. The genus Pheidole significantly reduced in abundance over time, suggesting that it was affected by treatment efforts. These results demonstrate that the treatment regime used at the time successfully removed S. invicta from these sites in Brisbane, and that most local ant genera were not seriously impacted by the treatment. These results have important implications for current and future prophylactic treatment efforts, and suggest that native ants remain in treated areas to provide some biological resistance to S. invicta.

  15. Characterization of harpy/Rca1/emi1 mutants: patterning in the absence of cell division.

    Science.gov (United States)

    Riley, Bruce B; Sweet, Elly M; Heck, Rebecca; Evans, Adrienne; McFarland, Karen N; Warga, Rachel M; Kane, Donald A

    2010-03-01

    We have characterized mutations in the early arrest gene, harpy (hrp), and show that they introduce premature stops in the coding region of early mitotic inhibitor1 (Rca1/emi1). In harpy mutants, cells stop dividing during early gastrulation. Lineage analysis confirms that there is little change in cell number after approximately cycle-14. Gross patterning occurs relatively normally, and many organ primordia are produced on time but with smaller numbers of cells. Despite the lack of cell division, some organ systems continue to increase in cell number, suggesting recruitment from surrounding areas. Analysis of bromodeoxyuridine incorporation shows that endoreduplication continues in many cells well past the first day of development, but cells cease endoreduplication once they begin to differentiate and express cell-type markers. Despite relatively normal gross patterning, harpy mutants show several defects in morphogenesis, cell migration and differentiation resulting directly or indirectly from the arrest of cell division. Copyright (c) 2010 Wiley-Liss, Inc.

  16. Patterns of cell death in the perinatal mouse forebrain

    OpenAIRE

    Mosley, Morgan; Shah, Charisma; Morse, Kiriana A.; Miloro, Stephen A.; Holmes, Melissa M.; Ahern, Todd H.; Forger, Nancy G.

    2016-01-01

    The importance of cell death in brain development has long been appreciated, but many basic questions remain, such as what initiates or terminates the cell death period. One obstacle has been the lack of quantitative data defining exactly when cell death occurs. We recently created a “cell death atlas,” using the detection of activated caspase-3 (AC3) to quantify apoptosis in the postnatal mouse ventral forebrain and hypothalamus, and found that the highest rates of cell death were seen at th...

  17. Linking Cellular Mechanisms to Behavior: Entorhinal Persistent Spiking and Membrane Potential Oscillations May Underlie Path Integration, Grid Cell Firing, and Episodic Memory

    Directory of Open Access Journals (Sweden)

    Michael E. Hasselmo

    2008-01-01

    Full Text Available The entorhinal cortex plays an important role in spatial memory and episodic memory functions. These functions may result from cellular mechanisms for integration of the afferent input to entorhinal cortex. This article reviews physiological data on persistent spiking and membrane potential oscillations in entorhinal cortex then presents models showing how both these cellular mechanisms could contribute to properties observed during unit recording, including grid cell firing, and how they could underlie behavioural functions including path integration. The interaction of oscillations and persistent firing could contribute to encoding and retrieval of trajectories through space and time as a mechanism relevant to episodic memory.

  18. Forest fires

    International Nuclear Information System (INIS)

    Fuller, M.

    1991-01-01

    This book examines the many complex and sensitive issues relating to wildland fires. Beginning with an overview of the fires of 1980s, the book discusses the implications of continued drought and considers the behavior of wildland fires, from ignition and spread to spotting and firestorms. Topics include the effects of weather, forest fuels, fire ecology, and the effects of fire on plants and animals. In addition, the book examines firefighting methods and equipment, including new minimum impact techniques and compressed air foam; prescribed burning; and steps that can be taken to protect individuals and human structures. A history of forest fire policies in the U.S. and a discussion of solutions to fire problems around the world completes the coverage. With one percent of the earth's surface burning every year in the last decade, this is a penetrating book on a subject of undeniable importance

  19. Uneven distribution pattern and increasing numbers of mesenchyme cells during development in the starfish, Asterina pectinifera.

    Science.gov (United States)

    Hamanaka, Gen; Hosaka, Eri; Kuraishi, Ritsu; Hosoya, Natsumi; Matsumoto, Midori; Kaneko, Hiroyuki

    2011-04-01

    During development, the embryos and larvae of the starfish Asterina pectinifera possess a single type of mesenchyme cell. The aim of this study was to determine the patterns of behavior of mesenchyme cells during the formation of various organs. To this end, we used a monoclonal antibody (mesenchyme cell marker) to identify the distribution patterns and numbers of mesenchyme cells. Our results revealed the following: (i) mesenchyme cell behavior differs in the formation of different organs, showing temporal variations and an uneven pattern of distribution; and (ii) mesenchyme cells continue to be generated throughout development, and their numbers are tightly regulated in proportion to total cell numbers. © 2011 The Authors. Journal compilation © 2011 Japanese Society of Developmental Biologists.

  20. Forest fires in Pennsylvania.

    Science.gov (United States)

    Donald A. Haines; William A. Main; Eugene F. McNamara

    1978-01-01

    Describes factors that contribute to forest fires in Pennsylvania. Includes an analysis of basic statistics; distribution of fires during normal, drought, and wet years; fire cause, fire activity by day-of-week; multiple-fire day; and fire climatology.

  1. A feedback mechanism controlling SCRAMBLED receptor accumulation and cell-type pattern in Arabidopsis.

    Science.gov (United States)

    Kwak, Su-Hwan; Schiefelbein, John

    2008-12-23

    Cellular pattern formation in the root epidermis of Arabidopsis occurs in a position-dependent manner, generating root-hair (H) cells contacting two underlying cortical cells and nonhair (N) cells contacting one cortical cell. SCRAMBLED (SCM), a leucine-rich repeat receptor-like kinase (LRR-RLK), mediates this process through its effect on a downstream transcription factor regulatory network. After perception of a positional cue, the SCM signaling pathway is proposed to preferentially repress WEREWOLF (WER) transcription factor expression in H cells and thereby bias the outcome of mutual lateral inhibition acting between H and N cells. However, the molecular mechanism responsible for this preferential SCM signaling is unknown. Here, we analyze the distribution of the SCM receptor and the biological effect of altering its accumulation pattern. We find that SCM expression and accumulation in the epidermal cell layer is necessary and sufficient to direct the cell-type pattern. Further, SCM preferentially accumulates in H cells, and this accumulation pattern is dependent on the downstream transcription factors. Thus, SCM participates in an autoregulatory feedback loop, enabling cells engaged in SCM signaling to maintain high levels of SCM receptor, which provides a simple mechanism for reinforcing a bias in receptor-mediated signaling to ensure robust pattern formation.

  2. Spike Train Auto-Structure Impacts Post-Synaptic Firing and Timing-Based Plasticity

    OpenAIRE

    Scheller, Bertram; Castellano, Marta; Vicente, Raul; Pipa, Gordon

    2011-01-01

    Cortical neurons are typically driven by several thousand synapses. The precise spatiotemporal pattern formed by these inputs can modulate the response of a post-synaptic cell. In this work, we explore how the temporal structure of pre-synaptic inhibitory and excitatory inputs impact the post-synaptic firing of a conductance-based integrate and fire neuron. Both the excitatory and inhibitory input was modeled by renewal gamma processes with varying shape factors for modeling regular and tempo...

  3. JACKDAW controls epidermal patterning in the Arabidopsis root meristem through a non-cell-autonomous mechanism.

    Science.gov (United States)

    Hassan, Hala; Scheres, Ben; Blilou, Ikram

    2010-05-01

    In Arabidopsis, specification of the hair and non-hair epidermal cell types is position dependent, in that hair cells arise over clefts in the underlying cortical cell layer. Epidermal patterning is determined by a network of transcriptional regulators that respond to an as yet unknown cue from underlying tissues. Previously, we showed that JACKDAW (JKD), a zinc finger protein, localizes in the quiescent centre and the ground tissue, and regulates tissue boundaries and asymmetric cell division by delimiting SHORT-ROOT movement. Here, we provide evidence that JKD controls position-dependent signals that regulate epidermal-cell-type patterning. JKD is required for appropriately patterned expression of the epidermal cell fate regulators GLABRA2, CAPRICE and WEREWOLF. Genetic interaction studies indicate that JKD operates upstream of the epidermal patterning network in a SCRAMBLED (SCM)-dependent fashion after embryogenesis, but acts independent of SCM in embryogenesis. Tissue-specific induction experiments indicate non-cell-autonomous action of JKD from the underlying cortex cell layer to specify epidermal cell fate. Our findings are consistent with a model where JKD induces a signal in every cortex cell that is more abundant in the hair cell position owing to the larger surface contact of cells located over a cleft.

  4. Subalpine vegetation pattern three decades after stand-replacing fire: Effects of landscape context and topography on plant community composition, tree regeneration, and diversity

    Science.gov (United States)

    Jonathan D. Coop; Robert T. Massatti; Anna W. Schoettle

    2010-01-01

    These subalpine wildfires generated considerable, persistent increases in plant species richness at local and landscape scales, and a diversity of plant communities. The findings suggest that fire suppression in such systems must lead to reduced diversity. Concerns about post-fire invasion by exotic plants appear unwarranted in high-elevation wilderness settings.

  5. Investigating the association between weather conditions, calendar events and socio-economic patterns with trends in fire incidence: an Australian case study

    Science.gov (United States)

    Corcoran, Jonathan; Higgs, Gary; Rohde, David; Chhetri, Prem

    2011-06-01

    Fires in urban areas can cause significant economic, physical and psychological damage. Despite this, there has been a comparative lack of research into the spatial and temporal analysis of fire incidence in urban contexts. In this paper, we redress this gap through an exploration of the association of fire incidence to weather, calendar events and socio-economic characteristics in South-East Queensland, Australia using innovative technique termed the quad plot. Analysing trends in five fire incident types, including malicious false alarms (hoax calls), residential buildings, secondary (outdoor), vehicle and suspicious fires, results suggest that risk associated with all is greatly increased during school holidays and during long weekends. For all fire types the lowest risk of incidence was found to occur between one and six a.m. It was also found that there was a higher fire incidence in socially disadvantaged neighbourhoods and there was some evidence to suggest that there may be a compounding impact of high temperatures in such areas. We suggest that these findings may be used to guide the operations of fire services through spatial and temporal targeting to better utilise finite resources, help mitigate risk and reduce casualties.

  6. Patterns of cell death in the perinatal mouse forebrain.

    Science.gov (United States)

    Mosley, Morgan; Shah, Charisma; Morse, Kiriana A; Miloro, Stephen A; Holmes, Melissa M; Ahern, Todd H; Forger, Nancy G

    2017-01-01

    The importance of cell death in brain development has long been appreciated, but many basic questions remain, such as what initiates or terminates the cell death period. One obstacle has been the lack of quantitative data defining exactly when cell death occurs. We recently created a "cell death atlas," using the detection of activated caspase-3 (AC3) to quantify apoptosis in the postnatal mouse ventral forebrain and hypothalamus, and found that the highest rates of cell death were seen at the earliest postnatal ages in most regions. Here we have extended these analyses to prenatal ages and additional brain regions. We quantified cell death in 16 forebrain regions across nine perinatal ages from embryonic day (E) 17 to postnatal day (P) 11 and found that cell death peaks just after birth in most regions. We found greater cell death in several regions in offspring delivered vaginally on the day of parturition compared with those of the same postconception age but still in utero at the time of collection. We also found massive cell death in the oriens layer of the hippocampus on P1 and in regions surrounding the anterior crossing of the corpus callosum on E18 as well as the persistence of large numbers of cells in those regions in adult mice lacking the pro-death Bax gene. Together these findings suggest that birth may be an important trigger of neuronal cell death and identify transient cell groups that may undergo wholesale elimination perinatally. J. Comp. Neurol. 525:47-64, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  7. Patterning of Cells on Bioresist for Tissue Engineering Applications

    National Research Council Canada - National Science Library

    Umar, Yusif; Thiyagarajan, Muthiah; Halberstadt, Craig; Gonsalves, Kenneth E

    2005-01-01

    .... The field of tissue engineering hinges on developing degradable polymeric scaffolds that promote cell proliferation and expression of desired physiological behaviors through careful control of the polymer surface...

  8. Ecological Impacts of the Cerro Grande Fire: Predicting Elk Movement and Distribution Patterns in Response to Vegetative Recovery through Simulation Modeling October 2005

    Energy Technology Data Exchange (ETDEWEB)

    Rupp, Susan P. [Texas Tech Univ., Lubbock, TX (United States)

    2005-10-01

    In May 2000, the Cerro Grande Fire burned approximately 17,200 ha in north-central New Mexico as the result of an escaped prescribed burn initiated by Bandelier National Monument. The interaction of large-scale fires, vegetation, and elk is an important management issue, but few studies have addressed the ecological implications of vegetative succession and landscape heterogeneity on ungulate populations following large-scale disturbance events. Primary objectives of this research were to identify elk movement pathways on local and landscape scales, to determine environmental factors that influence elk movement, and to evaluate movement and distribution patterns in relation to spatial and temporal aspects of the Cerro Grande Fire. Data collection and assimilation reflect the collaborative efforts of National Park Service, U.S. Forest Service, and Department of Energy (Los Alamos National Laboratory) personnel. Geographic positioning system (GPS) collars were used to track 54 elk over a period of 3+ years and locational data were incorporated into a multi-layered geographic information system (GIS) for analysis. Preliminary tests of GPS collar accuracy indicated a strong effect of 2D fixes on position acquisition rates (PARs) depending on time of day and season of year. Slope, aspect, elevation, and land cover type affected dilution of precision (DOP) values for both 2D and 3D fixes, although significant relationships varied from positive to negative making it difficult to delineate the mechanism behind significant responses. Two-dimensional fixes accounted for 34% of all successfully acquired locations and may affect results in which those data were used. Overall position acquisition rate was 93.3% and mean DOP values were consistently in the range of 4.0 to 6.0 leading to the conclusion collar accuracy was acceptable for modeling purposes. SAVANNA, a spatially explicit, process-oriented ecosystem model, was used to simulate successional dynamics. Inputs to the

  9. Collective motion of cells mediates segregation and pattern formation in co-cultures.

    Directory of Open Access Journals (Sweden)

    Elod Méhes

    Full Text Available Pattern formation by segregation of cell types is an important process during embryonic development. We show that an experimentally yet unexplored mechanism based on collective motility of segregating cells enhances the effects of known pattern formation mechanisms such as differential adhesion, mechanochemical interactions or cell migration directed by morphogens. To study in vitro cell segregation we use time-lapse videomicroscopy and quantitative analysis of the main features of the motion of individual cells or groups. Our observations have been extensive, typically involving the investigation of the development of patterns containing up to 200,000 cells. By either comparing keratocyte types with different collective motility characteristics or increasing cells' directional persistence by the inhibition of Rac1 GTP-ase we demonstrate that enhanced collective cell motility results in faster cell segregation leading to the formation of more extensive patterns. The growth of the characteristic scale of patterns generally follows an algebraic scaling law with exponent values up to 0.74 in the presence of collective motion, compared to significantly smaller exponents in case of diffusive motion.

  10. Optical Measurement of Cell Colonization Patterns on Individual Suspended Sediment Aggregates

    Science.gov (United States)

    Nguyen, Thu Ha; Tang, Fiona H. M.; Maggi, Federico

    2017-10-01

    Microbial processes can make substantial differences to the way in which particles settle in aquatic environments. A novel method (OMCEC, optical measurement of cell colonization) is introduced to systematically map the biological spatial distribution over individual suspended sediment aggregates settling through a water column. OMCEC was used to investigate (1) whether a carbon source concentration has an impact on cell colonization, (2) how cells colonize minerals, and (3) if a correlation between colonization patterns and aggregate geometry exists. Incubations of Saccharomyces cerevisiae and stained montmorillonite at four sucrose concentrations were tested in a settling column equipped with a full-color microparticle image velocimetry system. The acquired high-resolution images were processed to map the cell distribution on aggregates based on emission spectra separation. The likelihood of cells colonizing minerals increased with increasing sucrose concentration. Colonization patterns were classified into (i) scattered, (ii) well touched, and (iii) poorly touched, with the second being predominant. Cell clusters in well-touched patterns were found to have lower capacity dimension than those in other patterns, while the capacity dimension of the corresponding aggregates was relatively high. A strong correlation of colonization patterns with aggregate biomass fraction and properties suggests dynamic colonization mechanisms from cell attachment to minerals, to joining of isolated cell clusters, and finally cell growth over the entire aggregate. This paper introduces a widely applicable method for analyses of microbial-affected sediment dynamics and highlights the microbial control on aggregate geometry, which can improve the prediction of large-scale morphodynamics processes.

  11. Development of Spatial Distribution Patterns by Biofilm Cells

    DEFF Research Database (Denmark)

    Haagensen, Janus Anders Juul; Hansen, Susse Kirkelund; Bak Christensen, Bjarke

    2015-01-01

    Confined spatial patterns of microbial distribution are prevalent in nature, such as in microbial mats, soil communities, and water stream biofilms. The symbiotic two-species consortium of Pseudomonas putida and Acinetobacter sp. C6, originally isolated from a creosote-polluted aquifer, has evolved...

  12. Wildland fire limits subsequent fire occurrence

    Science.gov (United States)

    Sean A. Parks; Carol Miller; Lisa M. Holsinger; Scott Baggett; Benjamin J. Bird

    2016-01-01

    Several aspects of wildland fire are moderated by site- and landscape-level vegetation changes caused by previous fire, thereby creating a dynamic where one fire exerts a regulatory control on subsequent fire. For example, wildland fire has been shown to regulate the size and severity of subsequent fire. However, wildland fire has the potential to influence...

  13. Distinct fluorescent pattern of KAT1::GFP in the plasma membrane of Vicia faba guard cells.

    Science.gov (United States)

    Homann, Ulrike; Meckel, Tobias; Hewing, Jennifer; Hütt, Marc-Thorsten; Hurst, Annette C

    2007-08-01

    The organisation of membrane proteins into certain domains of the plasma membrane (PM) has been proposed to be important for signalling in yeast and animal cells. Here we describe the formation of a very distinct pattern of the K(+) channel KAT1 fused to the green fluorescent protein (KAT1::GFP) when transiently expressed in guard cells of Vicia faba. Using confocal laser scanning microscopy we observed a radially striped pattern of KAT1::GFP fluorescence in the PM in about 70% of all transfected guard cells. This characteristic pattern was found to be cell type and protein specific and independent of the stomatal aperture and the cytoskeleton. Staining of the cell wall of guard cells with Calcofluor White revealed a great similarity between the arrangement of cellulose microfibrils and the KAT1::GFP pattern. Furthermore, the radial pattern of KAT1::GFP immediately disappeared when turgor pressure was strongly decreased by changing from hypotonic to hypertonic conditions. The pattern reappeared within 15 min upon reestablishment of high turgor pressure in hypotonic solution. Evaluation of the staining pattern by a mathematical algorithm further confirmed this reversible abolishment of the radial pattern during hypertonic treatment. We therefore conclude that the radial organisation of KAT1::GFP depends on the close contact between the PM and cell wall in turgid guard cells. These results offer the first indication for a role of the cell wall in the localisation of ion channels. We propose a model in which KAT1 is located in the cellulose fibrils intermediate areas of the PM and discuss the physiological role of this phenomenon.

  14. Properties of pattern and component direction-selective cells in area MT of the macaque

    Science.gov (United States)

    Wang, Helena X.

    2015-01-01

    Neurons in area MT/V5 of the macaque visual cortex encode visual motion. Some cells are selective for the motion of oriented features (component direction-selective, CDS); others respond to the true direction of complex patterns (pattern-direction selective, PDS). There is a continuum of selectivity in MT, with CDS cells at one extreme and PDS cells at the other; we compute a pattern index that captures this variation. It is unknown how a neuron's pattern index is related to its other tuning characteristics. We therefore analyzed the responses of 792 MT cells recorded in the course of other experiments from opiate-anesthetized macaque monkeys, as a function of the direction, spatial frequency, drift rate, size, and contrast of sinusoidal gratings and of the direction and speed of random-dot textures. We also compared MT responses to those of 718 V1 cells. As expected, MT cells with higher pattern index tended to have stronger direction selectivity and broader direction tuning to gratings, and they responded better to plaids than to gratings. Strongly PDS cells also tended to have smaller receptive fields and stronger surround suppression. Interestingly, they also responded preferentially to higher drift rates and higher speeds of moving dots. The spatial frequency preferences of PDS cells depended strongly on their preferred temporal frequencies, whereas these preferences were independent in component-selective cells. Pattern direction selectivity is statistically associated with many response properties of MT cells but not strongly associated with any particular property. Pattern-selective signals are thus available in association with most other signals exported by MT. PMID:26561603

  15. Polarization resolved conoscopic patterns in nematic cells: effects induced by the incident light ellipticity

    Science.gov (United States)

    Buinyi, Igor O.; Soskin, Marat S.; Vovk, Roman G.

    2008-05-01

    Topological structure of the polarization resolved conoscopic patterns, calculated theoretically and measured experimentally for nematic liquid crystal (NLC) cells, is described in terms of polarization singularities, saddle points and bifurcation lines. The parametric dynamics of the topological network, induced by the variation of the incident light ellipticity, is analyzed for the nematic cells with uniform and non-uniform director configuration. Different stages of similar dynamics are observed for homeotropically oriented NLC cell. Non-uniform director configuration within the cell results in broken central symmentry in the arrangement of the topological network. Main features of the experimentally obtained polarization resolved conoscopic patterns are the same to the theoretically predicted ones.

  16. Micro-patterned Nafion membranes for direct methanol fuel cell applications

    NARCIS (Netherlands)

    Yildirim, M.H.; te Braake, J.; Aran, H.C.; Stamatialis, Dimitrios; Wessling, Matthias

    2010-01-01

    In this work, we report the direct methanol fuel cell (DMFC) performance of micro-patterned (μp) Nafion® 117 (N117) membranes prepared by hot embossing and compare them with that of normal N117 and heat and pressure treated (hp) N117 non-patterned (smooth) membranes. Our results suggest that the

  17. Combining satellite-based fire observations and ground-based lightning detections to identify lightning fires across the conterminous USA

    Science.gov (United States)

    Bar-Massada, A.; Hawbaker, T.J.; Stewart, S.I.; Radeloff, V.C.

    2012-01-01

    Lightning fires are a common natural disturbance in North America, and account for the largest proportion of the area burned by wildfires each year. Yet, the spatiotemporal patterns of lightning fires in the conterminous US are not well understood due to limitations of existing fire databases. Our goal here was to develop and test an algorithm that combined MODIS fire detections with lightning detections from the National Lightning Detection Network to identify lightning fires across the conterminous US from 2000 to 2008. The algorithm searches for spatiotemporal conjunctions of MODIS fire clusters and NLDN detected lightning strikes, given a spatiotemporal lag between lightning strike and fire ignition. The algorithm revealed distinctive spatial patterns of lightning fires in the conterminous US While a sensitivity analysis revealed that the algorithm is highly sensitive to the two thresholds that are used to determine conjunction, the density of fires it detected was moderately correlated with ground based fire records. When only fires larger than 0.4 km2 were considered, correlations were higher and the root-mean-square error between datasets was less than five fires per 625 km2 for the entire study period. Our algorithm is thus suitable for detecting broad scale spatial patterns of lightning fire occurrence, and especially lightning fire hotspots, but has limited detection capability of smaller fires because these cannot be consistently detected by MODIS. These results may enhance our understanding of large scale patterns of lightning fire activity, and can be used to identify the broad scale factors controlling fire occurrence.

  18. Angora Fire, Lake Tahoe

    Science.gov (United States)

    2007-01-01

    On the weekend of June 23, 2007, a wildfire broke out south of Lake Tahoe, which stretches across the California-Nevada border. By June 28, the Angora Fire had burned more than 200 homes and forced some 2,000 residents to evacuate, according to The Seattle Times and the Central Valley Business Times. On June 27, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the burn scar left by the Angora fire. The burn scar is dark gray, or charcoal. Water bodies, including the southern tip of Lake Tahoe and Fallen Leaf Lake, are pale silvery blue, the silver color a result of sunlight reflecting off the surface of the water. Vegetation ranges in color from dark to bright green. Streets are light gray, and the customary pattern of meandering residential streets and cul-de-sacs appears throughout the image, including the area that burned. The burn scar shows where the fire obliterated some of the residential areas just east of Fallen Leaf Lake. According to news reports, the U.S. Forest Service had expressed optimism about containing the fire within a week of the outbreak, but a few days after the fire started, it jumped a defense, forcing the evacuation of hundreds more residents. Strong winds that had been forecast for June 27, however, did not materialize, allowing firefighters to regain ground in controlling the blaze. On June 27, authorities hoped that the fire would be completely contained by July 3. According to estimates provided in the daily report from the National Interagency Fire Center, the fire had burned 3,100 acres (about 12.5 square kilometers) and was about 55 percent contained as of June 28. Some mandatory evacuations remained in effect. NASA image by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

  19. Alpha7 Nicotinic Acetylcholine Receptors Play a Predominant Role in the Cholinergic Potentiation of N-Methyl-D-Aspartate Evoked Firing Responses of Hippocampal CA1 Pyramidal Cells

    Directory of Open Access Journals (Sweden)

    Zsolt K. Bali

    2017-09-01

    Full Text Available The aim of the present study was to identify in vivo electrophysiological correlates of the interaction between cholinergic and glutamatergic neurotransmission underlying memory. Extracellular spike recordings were performed in the hippocampal CA1 region of anesthetized rats in combination with local microiontophoretic administration of N-methyl-D-aspartate (NMDA and acetylcholine (ACh. Both NMDA and ACh increased the firing rate of the neurons. Furthermore, the simultaneous delivery of NMDA and ACh resulted in a more pronounced excitatory effect that was superadditive over the sum of the two mono-treatment effects and that was explained by cholinergic potentiation of glutamatergic neurotransmission. Next, animals were systemically treated with scopolamine or methyllycaconitine (MLA to assess the contribution of muscarinic ACh receptor (mAChR or α7 nicotinic ACh receptor (nAChR receptor-mediated mechanisms to the observed effects. Scopolamine totally inhibited ACh-evoked firing, and attenuated the firing rate increase evoked by simultaneous application of NMDA and ACh. However, the superadditive nature of the combined effect was preserved. The α7 nAChR antagonist MLA robustly decreased the firing response to simultaneous application of NMDA and ACh, suspending their superadditive effect, without modifying the tonic firing rate increasing effect of ACh. These results provide the first in vivo electrophysiological evidence that, in the hippocampal CA1 region, α7 nAChRs contribute to pyramidal cell activity mainly through potentiation of glutamatergic signaling, while the direct cholinergic modulation of tonic firing is notably mediated by mAChRs. Furthermore, the present findings also reveal cellular physiological correlates of the interplay between cholinergic and glutamatergic agents in behavioral pharmacological models of cognitive decline.

  20. Using self-assembled monolayers to pattern ECM proteins and cells on substrates.

    Science.gov (United States)

    Ostuni, Emanuele; Whitesides, George M; Ingber, Donald E; Chen, Christopher S

    2009-01-01

    We present a method that uses microcontact printing of alkanethiols on gold to generate patterned substrates presenting "islands" of extracellular matrix (ECM) surrounded by nonadhesive regions such that single cells attach and spread only on the adhesive regions. We have used this micropatterning technology to demonstrate that mammalian cells can be switched between growth and apoptosis programs in the presence of saturating concentrations of growth factors by either promoting or preventing cell spreading (Science 276:1425-1428, 1997). From the perspective of fundamental cell biology, these results suggested that the local differentials in growth and viability that are critical for the formation of complex tissue patterns may be generated by local changes in cell-ECM interactions. In the context of cell culture technologies, such as bioreactors and cellular engineering applications, the regulation of cell function by cell shape indicates that the adhesive microenvironment around cells can be carefully optimized by patterning a substrate in addition to using soluble factors (Biotech. Prog. 14:356-363, 1998). Micropatterning technology is playing a central role both in our understanding how ECM and cell shape regulate cell physiology and in facilitating the development of cellular biosensor and tissue engineering applications (Science 264:696-698, 1994; J. Neurosci. Res. 13:213-20, 1985; Biotech. Bioeng. 43:792-800, 1994).

  1. Migration and chemokine receptor pattern of colitis-preventing DX5+NKT cells.

    Science.gov (United States)

    Hornung, Matthias; Werner, Jens M; Farkas, Stefan; Schlitt, Hans J; Geissler, Edward K

    2011-11-01

    DX5(+)NKT cells are a subpopulation of NKT cells expressing both T cell receptor and NK cell markers that show an immune-regulating function. Transferred DX5(+)NKT cells from immune competent Balb/c mice can prevent or reduce induced colitis in severe combined immunodeficient (SCID) mice. Here, we investigated the in vivo migration of DX5(+)NKT cells and their corresponding chemokine receptor patterns. DX5(+)NKT cells were isolated from spleens of Balb/c mice and transferred into Balb/c SCID mice. After 2 and 8 days, in vivo migration was examined using in vivo microscopy. In addition, the chemokine receptor pattern was analyzed with fluorescence-activated cell sorting (FACS) and the migration assay was performed. Our results show that labeled DX5(+)NKT cells were primarily detectable in mesenteric lymph nodes and spleen after transfer. After 8 days, DX5(+)NKT cells were observed in the colonic tissues, especially the appendix. FACS analysis of chemokine receptors in DX5(+)NKT cells revealed expression of CCR3, CCR6, CCR9, CXCR3, CXCR4, and CXCR6, but no CCR5, CXCR5, or the lymphoid homing receptor CCR7. Stimulation upregulated especially CCR7 expression, and chemokine receptor patterns were different between splenic and liver DX5(+)NKT cells. These data indicate that colitis-preventing DX5(+)NKT cells need to traffic through lymphoid organs to execute their immunological function at the site of inflammation. Furthermore, DX5(+)NKT cells express a specific chemokine receptor pattern with an upregulation of the lymphoid homing receptor CCR7 after activation.

  2. Advanced analysis of forest fire clustering

    Science.gov (United States)

    Kanevski, Mikhail; Pereira, Mario; Golay, Jean

    2017-04-01

    Analysis of point pattern clustering is an important topic in spatial statistics and for many applications: biodiversity, epidemiology, natural hazards, geomarketing, etc. There are several fundamental approaches used to quantify spatial data clustering using topological, statistical and fractal measures. In the present research, the recently introduced multi-point Morisita index (mMI) is applied to study the spatial clustering of forest fires in Portugal. The data set consists of more than 30000 fire events covering the time period from 1975 to 2013. The distribution of forest fires is very complex and highly variable in space. mMI is a multi-point extension of the classical two-point Morisita index. In essence, mMI is estimated by covering the region under study by a grid and by computing how many times more likely it is that m points selected at random will be from the same grid cell than it would be in the case of a complete random Poisson process. By changing the number of grid cells (size of the grid cells), mMI characterizes the scaling properties of spatial clustering. From mMI, the data intrinsic dimension (fractal dimension) of the point distribution can be estimated as well. In this study, the mMI of forest fires is compared with the mMI of random patterns (RPs) generated within the validity domain defined as the forest area of Portugal. It turns out that the forest fires are highly clustered inside the validity domain in comparison with the RPs. Moreover, they demonstrate different scaling properties at different spatial scales. The results obtained from the mMI analysis are also compared with those of fractal measures of clustering - box counting and sand box counting approaches. REFERENCES Golay J., Kanevski M., Vega Orozco C., Leuenberger M., 2014: The multipoint Morisita index for the analysis of spatial patterns. Physica A, 406, 191-202. Golay J., Kanevski M. 2015: A new estimator of intrinsic dimension based on the multipoint Morisita index

  3. Prevalence and pattern of sickle cell disease in premarital couples ...

    African Journals Online (AJOL)

    2012-09-04

    Sep 4, 2012 ... 6. Altay C, Yilgor E, Beksac S, Gurgey A. Premarital screening of haemoglobinopathies: A pilot study in Turkey. Hum Hered 1996;46:112-4. 7. Guler E, Caliskan U, UcarAlbayrak C, Karacan M. Prevalence of beta- thalassemia and sickle cell anaemia trait in premarital screening in Konya urban area, Turkey.

  4. Autopsy findings and pattern of mortality in Nigerian sickle cell ...

    African Journals Online (AJOL)

    Introduction: Sickle Cell Disease (SCD) has a high mortality rate in the environment where we practice. There is lack of contemporal autopsy studies describing causes of death among SCD patients at our centre. Methods: This is a retrospective study of SCD patients who died between January 1991 and December 2008 ...

  5. Patterns of efficiency and degradation of composite polymer solar cells

    NARCIS (Netherlands)

    Jeranko, T; Tributsch, H; Sariciftci, NS; Hummelen, JC

    2004-01-01

    Bulk-heterojunction plastic solar cells (PSC) produced from a conjugated polymer, poly(2-methoxy-5-(3',7'-dimethyloctyl-oxy)-1,4-phenylenevinylene) (MDMO-PPV), and a methanofullerene [6,6]-phenyl C-61-butyric acid methyl ester (PCBM) were investigated using photocurrent imaging techniques to

  6. Dietary Preferences and Pattern in Children with Sickle Cell Disease ...

    African Journals Online (AJOL)

    The looks of children with sickle cell anaemia give an impression of malnourishment. Not growing optimally, they have lower weight, height and muscle bulk in the upper limbs than age and sex matched controls. Their underlying state imposes an increased metabolic demand on them. Yet there is simultaneous inadequate ...

  7. Cell state switching factors and dynamical patterning modules ...

    Indian Academy of Sciences (India)

    Prakash

    Plasticity (i.e. stochastic or condition-dependent variability) of developmental outcome in multicellular organisms is due to two principal mechanisms. The first is largely, though not entirely, a function of differential gene expression and is based on the capacity of individual cells to switch between alternative states under ...

  8. Dysfunctional eating patterns and symptoms of pica in children and adolescents with sickle cell disease.

    Science.gov (United States)

    Lemanek, Kathleen L; Brown, Ronald T; Amstrong, F Daniel; Hood, Catherine; Pegelow, Charles; Woods, Gerald

    2002-09-01

    The objective of this study was to examine the incidence and relationship of pica symptoms and dysfunctional eating patterns in children and adolescents with sickle cell disease (SCD). Children and caregivers (n = 146) completed questionnaires assessing eating difficulties and symptoms of pica. Information also was collected from medical records and analyzed for relationships with dysfunctional eating patterns. Incidence of problems and their association with disease parameters of SCD were examined. Dysfunctional eating patterns were found in those with no symptoms of pica and those with severe symptoms of pica. Caregiver-reported dysfunctional eating patterns were associated with caregiver- and child-reported frequency of painful episodes.

  9. Duration of Purkinje cell complex spikes increases with their firing frequency

    NARCIS (Netherlands)

    P.J. Warnaar (Pascal); J. Couto (Joao); M. Negrello (Mario); M. Junker (Marc); A. Smilgin (Aleksandra); A. Ignashchenkova (Alla); M. Giugliano (Michele); P. Thier (Peter); E. de Schutter (Erik)

    2015-01-01

    textabstractClimbing fiber (CF) triggered complex spikes (CS) are massive depolarization bursts in the cerebellar Purkinje cell (PC), showing several high frequency spikelet components (±600 Hz). Since its early observations, the CS is known to vary in shape. In this study we describe CS waveforms,

  10. Fire Whirls

    Science.gov (United States)

    Tohidi, Ali; Gollner, Michael J.; Xiao, Huahua

    2018-01-01

    Fire whirls present a powerful intensification of combustion, long studied in the fire research community because of the dangers they present during large urban and wildland fires. However, their destructive power has hidden many features of their formation, growth, and propagation. Therefore, most of what is known about fire whirls comes from scale modeling experiments in the laboratory. Both the methods of formation, which are dominated by wind and geometry, and the inner structure of the whirl, including velocity and temperature fields, have been studied at this scale. Quasi-steady fire whirls directly over a fuel source form the bulk of current experimental knowledge, although many other cases exist in nature. The structure of fire whirls has yet to be reliably measured at large scales; however, scaling laws have been relatively successful in modeling the conditions for formation from small to large scales. This review surveys the state of knowledge concerning the fluid dynamics of fire whirls, including the conditions for their formation, their structure, and the mechanisms that control their unique state. We highlight recent discoveries and survey potential avenues for future research, including using the properties of fire whirls for efficient remediation and energy generation.

  11. On fire

    DEFF Research Database (Denmark)

    Hansen, Helle Rabøl

    The title of this paper: “On fire”, refers to two (maybe three) aspects: firstly as a metaphor of having engagement in a community of practice according to Lave & Wenger (1991), and secondly it refers to the concrete element “fire” in the work of the fire fighters – and thirdly fire as a signifie...... of frustrations and riots...

  12. Fire Synthesis

    Indian Academy of Sciences (India)

    1000ºC or special infrastructure which require careful maintenance. In such a situation fire synthesis is a simpler method that can be adopted for the bulk production of high purity alumina and related oxides. Fire Synthesis. Preparation of Alumina ...

  13. Fire Power

    Science.gov (United States)

    Denker, Deb; West, Lee

    2009-01-01

    For education administrators, campus fires are not only a distressing loss, but also a stark reminder that a campus faces risks that require special vigilance. In many ways, campuses resemble small communities, with areas for living, working and relaxing. A residence hall fire may raise the specter of careless youth, often with the complication of…

  14. On fire

    DEFF Research Database (Denmark)

    Hansen, Helle Rabøl

    The title of this paper: “On fire”, refers to two (maybe three) aspects: firstly as a metaphor of having engagement in a community of practice according to Lave & Wenger (1991), and secondly it refers to the concrete element “fire” in the work of the fire fighters – and thirdly fire as a signifie...

  15. Classifying and comparing spatial models of fire dynamics

    Science.gov (United States)

    Geoffrey J. Cary; Robert E. Keane; Mike D. Flannigan

    2007-01-01

    Wildland fire is a significant disturbance in many ecosystems worldwide and the interaction of fire with climate and vegetation over long time spans has major effects on vegetation dynamics, ecosystem carbon budgets, and patterns of biodiversity. Landscape-Fire-Succession Models (LFSMs) that simulate the linked processes of fire and vegetation development in a spatial...

  16. Topology optimization: An effective method for designing front metallization patterns of solar cells

    NARCIS (Netherlands)

    Gupta, D.K.; Langelaar, M.; Barink, M.; Keulen, F. van

    2014-01-01

    Optimal front electrode design is one of the approaches to improve the performance of solar cells. This work introduces the application of topology optimization (TO) to design complex front metallization patterns for solar cells. TO optimizes the distribution of electrode material on the front

  17. Forest-fire models

    Science.gov (United States)

    Haiganoush Preisler; Alan Ager

    2013-01-01

    For applied mathematicians forest fire models refer mainly to a non-linear dynamic system often used to simulate spread of fire. For forest managers forest fire models may pertain to any of the three phases of fire management: prefire planning (fire risk models), fire suppression (fire behavior models), and postfire evaluation (fire effects and economic models). In...

  18. The comparative effect of prebiotic, growth promoter antibiotic, probiotic, yeast cell wall and acid fire on broiler chickens performance

    Directory of Open Access Journals (Sweden)

    A Zakeri

    2010-05-01

    Full Text Available In this study 600 Cobb 500 broiler chickens were divided in six similar groups (A, B, C, D, E&F with 100 chickens in each group (with four replicates of 25 chickens in each group. 100 g/ton growth promoter antibiotic in experimental group (B, 100 g/ton Prebiotic in experimental group (C, 800 g/ton Acid fires in experimental group (D, 1 kg/ton MOS in experimental group (E and 4 kg/ton Yeast cell wall in experimental group (F were added to the basic diets however the control group (A chickens were fed only with the basic diet. Every week 100 chickens from each group were selected randomly and productive parameters such as weight gain, FCR, EEF, mortality, feed intake (FI were calculated. On days 9, 17 and 25 of growth (1 day before and 7, 14 days after first Newcastle B1 vaccination, from each groups, each time 20 chickens were chosen randomly and serum antibody titres of these chickens were measured against Newcastle vaccine by HI test. The results obtained from statistical analysis indicated that using natural growth promoting substances not only increases humoral immunity but it also leads to improvement of productive parameters (p

  19. Mixed severity fire effects within the Rim fire: Relative importance of local climate, fire weather, topography, and forest structure

    Science.gov (United States)

    Van R. Kane; C. Alina Cansler; Nicholas A. Povak; Jonathan T. Kane; Robert J. McGaughey; James A. Lutz; Derek J. Churchill; Malcolm P. North

    2015-01-01

    Recent and projected increases in the frequency and severity of large wildfires in the western U.S. makes understanding the factors that strongly affect landscape fire patterns a management priority for optimizing treatment location. We compared the influence of variations in the local environment on burn severity patterns on the large 2013 Rim fire that burned under...

  20. Origins of adult pigmentation: diversity in pigment stem cell lineages and implications for pattern evolution.

    Science.gov (United States)

    Parichy, David M; Spiewak, Jessica E

    2015-01-01

    Teleosts comprise about half of all vertebrate species and exhibit an extraordinary diversity of adult pigment patterns that function in shoaling, camouflage, and mate choice and have played important roles in speciation. Here, we review studies that have identified several distinct neural crest lineages, with distinct genetic requirements, that give rise to adult pigment cells in fishes. These lineages include post-embryonic, peripheral nerve-associated stem cells that generate black melanophores and iridescent iridophores, cells derived directly from embryonic neural crest cells that generate yellow-orange xanthophores, and bipotent stem cells that generate both melanophores and xanthophores. This complexity in adult chromatophore lineages has implications for our understanding of adult traits, melanoma, and the evolutionary diversification of pigment cell lineages and patterns. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Mixed-severity fire regimes in the northern Rocky Mountains: consequences of fire exclusion and options for the future

    Science.gov (United States)

    Stephen F. Arno; David J. Parsons; Robert E. Keane

    2000-01-01

    Findings from fire history studies have increasingly indicated that many forest ecosystems in the northern Rocky Mountains were shaped by mixed-severity fire regimes, characterized by fires of variable severities at intervals averaging between about 30 and 100 years. Perhaps because mixed-severity fire regimes and their resulting vegetational patterns are difficult to...

  2. Bistable firing properties of soleus motor units in unrestrained rats

    DEFF Research Database (Denmark)

    EKEN, T.; KIEHN, O.

    1989-01-01

    of the motoneuron pool by stimulation of la afferents, or inhibition by stimulation of skin afferents. The shifts were not related to gross limb movements. This phenomenon is referred to as a bistable firing pattern. Bistable firing also occurred spontaneously during quiet standing. Typically the firing frequency...... was unchanged or only phasically influenced. These results demonstrate for the first time a bistable firing pattern during postural activity in the intact animal. The firing pattern closely resembles the bistable behaviour described in spinal motoneurons in reduced preparations, where it is due to the presence...... of a plateau potential. This suggests that the bistable firing is unexplained by plateau potentials also in the intact animal....

  3. Cell-fate specification in the epidermis: a common patterning mechanism in the root and shoot.

    Science.gov (United States)

    Schiefelbein, John

    2003-02-01

    The specification of epidermal hairs in Arabidopsis provides a useful model for the study of pattern formation in plants. Although the distributions of hair cells in the root and shoot appear quite different, recent studies show that pattern formation in each relies on a common cassette of transcriptional regulators. During development in each organ, neighboring cells compete to express regulators that specify the primary cell fate (including WEREWOLF [WER]/GLABRA1 [GL1], GL3/bHLH, TRANSPARENT TESTA GLABRA [TTG], and GL2), as well as those that prevent their neighbors from adopting this fate (including CAPRICE [CPC] and TRIPTYCHON [TRY]). The basic mechanism of lateral inhibition with feedback that has been uncovered by recent studies provides a conceptual framework for understanding how patterns of cell fate in general may be specified during plant development.

  4. ESA fire_cci product assessment

    Science.gov (United States)

    Heil, Angelika; Yue, Chao; Mouillot, Florent; Storm, Thomas; Chuvieco, Emilio; Ramo Sanchez, Ruben; Kaiser, Johannes W.

    2017-04-01

    Vegetation fires are a major disturbance in the Earth System. Fires change the biophysical properties and dynamics of ecosystems and alter terrestrial carbon pools. By altering the atmosphere's composition, fire emissions exert a significant climate forcing. To realistically model past and future changes of the Earth System, fire disturbances must be taken into account. Related modelling efforts require consistent global burned area observations covering at least 10 to 20 years. Guided by the specific requirements of a wide range of end users, the ESA fire_cci project has computed a new global burned area dataset. It applies a newly developed spectral change detection algorithm upon the ENVISAT-MERIS archive. The algorithm relies on MODIS active fire information as "seed". It comprises a pixel burned area product (spatial resolution of 333 m) with date detection information and a biweekly grid product at 0.25 degree spatial resolution. We compare fire_cci burned area with other global burned area products (MCD64 Collection 6, MCD45, GFED4, GFED4s and GEOLAND) and a set of active fires data (hotspots from MODIS, TRMM, AATSR and fire radiative power from GFAS). The analysis of patterns of agreement and disagreement between fire_cci and other products provides a better understanding of product characteristics and uncertainties. The intercomparison of the 2005-2011 fire_cci time series shows a close agreement with GFED4 data in terms of global burned area and the general spatial and temporal patterns. Pronounced differences, however, emerge for specific regions or fire events. Burned area mapped by fire_cci tends to be notably higher in regions where small agricultural fires predominate. The improved detection of small agricultural fires by fire_cci can be related to the increased spatial resolution of the MERIS sensor (333 m compared to 500 in MODIS). This is illustrated in detail using the example of the extreme 2006 spring fires in Eastern Europe.

  5. 3D Reconstitution of the Patterned Neural Tube from Embryonic Stem Cells

    OpenAIRE

    Meinhardt, Andrea; Eberle, Dominic; Tazaki, Akira; Ranga, Adrian; Niesche, Marco; Wilsch-Bräuninger, Michaela; Stec, Agnieszka; Schackert, Gabriele; Lutolf, Matthias; Tanaka, Elly M.

    2014-01-01

    Summary Inducing organogenesis in 3D culture is an important aspect of stem cell research. Anterior neural structures have been produced from large embryonic stem cell (ESC) aggregates, but the steps involved in patterning such complex structures have been ill defined, as embryoid bodies typically contained many cell types. Here we show that single mouse ESCs directly embedded in Matrigel or defined synthetic matrices under neural induction conditions can clonally form neuroepithelial cysts c...

  6. Patterns of cell death in the embryonic antenna of the grasshopper Schistocerca gregaria.

    Science.gov (United States)

    Boyan, George; Graf, Philip; Ehrhardt, Erica

    2018-03-06

    We have investigated the pattern of apoptosis in the antennal epithelium during embryonic development of the grasshopper Schistocerca gregaria. The molecular labels lachesin and annulin reveal that the antennal epithelium becomes subdivided into segment-like meristal annuli within which sensory cell clusters later differentiate. To determine whether apoptosis is involved in the development of such sensory cell clusters, we examined the expression pattern of the cell death labels acridine orange and TUNEL in the epithelium. We found stereotypic, age-dependent, wave-like patterns of cell death in the antenna. Early in embryogenesis, apoptosis is restricted to the most basal meristal annuli but subsequently spreads to encompass almost the entire antenna. Cell death then declines in more basal annuli and is only found in the tip region later in embryogenesis. Apoptosis is restricted throughout to the midregion of a given annulus and away from its border with neighboring annuli, arguing against a causal role in annular formation. Double-labeling for cell death and sensory cell differentiation reveals apoptosis occurring within bands of differentiating sensory cell clusters, matching the meristal organization of the apical antenna. Examination of the individual epithelial lineages which generate sensory cells reveals that apoptosis begins peripherally within a lineage and with age expands to encompass the differentiated sensory cell at the base. We conclude that complete lineages can undergo apoptosis and that the youngest cells in these lineages appear to die first, with the sensory neuron dying last. Lineage-based death in combination with cell death patterns in different regions of the antenna may contribute to odor-mediated behaviors in the grasshopper.

  7. Analysis of chlorophyll fluorescence reveals stage specific patterns of chloroplast-containing cells during Arabidopsis embryogenesis

    Directory of Open Access Journals (Sweden)

    RICARDO I TEJOS

    2010-01-01

    Full Text Available The basic body plan of a plant is established early in embryogenesis when cells differentiate, giving rise to the apical and basal regions of the embryo. Using chlorophyll fluorescence as a marker for chloroplasts, we have detected specific patterns of chloroplast-containing cells at specific stages of embryogenesis. Non-randomly distributed chloroplast-containing cells are seen as early as the globular stage of embryogenesis in Arabidopsis. In the heart stage of embryogenesis, chloroplast containing cells are detected in epidermal cells as well as a central region of the heart stage embryo, forming a triangular septum of chloroplast-containing cells that divides the embryo into three equal sectors. Torpedo stage embryos have chloroplast-containing epidermal cells and a central band of chloroplast-containing cells in the cortex layer, just below the shoot apical meristem. In the walking-stick stage of embryogenesis, chloroplasts are present in the epidermal, cortex and endodermal cells. The chloroplasts appear reduced or absent from the provascular and columella cells of walking-stick stage embryos. These results suggest that there is a tight regulation of plastid differentiation during embryogenesis that generates specific patterns of chloroplast-containing cells in specific cell layers at specific stages of embryogenesis.

  8. Analysis of chlorophyll fluorescence reveals stage specific patterns of chloroplast-containing cells during Arabidopsis embryogenesis.

    Science.gov (United States)

    Tejos, Ricardo I; Mercado, Ana V; Meisel, Lee A

    2010-01-01

    The basic body plan of a plant is established early in embryogenesis when cells differentiate, giving rise to the apical and basal regions of the embryo. Using chlorophyll fluorescence as a marker for chloroplasts, we have detected specific patterns of chloroplast-containing cells at specific stages of embryogenesis. Non-randomly distributed chloroplast-containing cells are seen as early as the globular stage of embryogenesis in Arabidopsis. In the heart stage of embryogenesis, chloroplast containing cells are detected in epidermal cells as well as a central region of the heart stage embryo, forming a triangular septum of chloroplast-containing cells that divides the embryo into three equal sectors. Torpedo stage embryos have chloroplast-containing epidermal cells and a central band of chloroplast-containing cells in the cortex layer, just below the shoot apical meristem. In the walking-stick stage of embryogenesis, chloroplasts are present in the epidermal, cortex and endodermal cells. The chloroplasts appear reduced or absent from the provascular and columella cells of walking-stick stage embryos. These results suggest that there is a tight regulation of plastid differentiation during embryogenesis that generates specific patterns of chloroplast-containing cells in specific cell layers at specific stages of embryogenesis.

  9. Controls on carbon consumption during Alaskan wildland fires

    Science.gov (United States)

    Eric S. Kasischke; Elizabeth E. Hoy

    2012-01-01

    A method was developed to estimate carbon consumed during wildland fires in interior Alaska based on medium-spatial scale data (60 m cell size) generated on a daily basis. Carbon consumption estimates were developed for 41 fire events in the large fire year of 2004 and 34 fire events from the small fire years of 2006-2008. Total carbon consumed during the large fire...

  10. Computational model-informed design and bioprinting of cell-patterned constructs for bone tissue engineering.

    Science.gov (United States)

    Carlier, Aurélie; Skvortsov, Gözde Akdeniz; Hafezi, Forough; Ferraris, Eleonora; Patterson, Jennifer; Koç, Bahattin; Van Oosterwyck, Hans

    2016-05-17

    Three-dimensional (3D) bioprinting is a rapidly advancing tissue engineering technology that holds great promise for the regeneration of several tissues, including bone. However, to generate a successful 3D bone tissue engineering construct, additional complexities should be taken into account such as nutrient and oxygen delivery, which is often insufficient after implantation in large bone defects. We propose that a well-designed tissue engineering construct, that is, an implant with a specific spatial pattern of cells in a matrix, will improve the healing outcome. By using a computational model of bone regeneration we show that particular cell patterns in tissue engineering constructs are able to enhance bone regeneration compared to uniform ones. We successfully bioprinted one of the most promising cell-gradient patterns by using cell-laden hydrogels with varying cell densities and observed a high cell viability for three days following the bioprinting process. In summary, we present a novel strategy for the biofabrication of bone tissue engineering constructs by designing cell-gradient patterns based on a computational model of bone regeneration, and successfully bioprinting the chosen design. This integrated approach may increase the success rate of implanted tissue engineering constructs for critical size bone defects and also can find a wider application in the biofabrication of other types of tissue engineering constructs.

  11. The Effects of Topographical Patterns and Sizes on Neural Stem Cell Behavior

    Science.gov (United States)

    Qi, Lin; Li, Ning; Huang, Rong; Song, Qin; Wang, Long; Zhang, Qi; Su, Ruigong; Kong, Tao; Tang, Mingliang; Cheng, Guosheng

    2013-01-01

    Engineered topographical manipulation, a paralleling approach with conventional biochemical cues, has recently attracted the growing interests in utilizations to control stem cell fate. In this study, effects of topological parameters, pattern and size are emphasized on the proliferation and differentiation of adult neural stem cells (ANSCs). We fabricate micro-scale topographical Si wafers with two different feature sizes. These topographical patterns present linear micro-pattern (LMP), circular micro-pattern (CMP) and dot micro-pattern (DMP). The results show that the three topography substrates are suitable for ANSC growth, while they all depress ANSC proliferation when compared to non-patterned substrates (control). Meanwhile, LMP and CMP with two feature sizes can both significantly enhance ANSC differentiation to neurons compared to control. The smaller the feature size is, the better upregulation applies to ANSC for the differentiated neurons. The underlying mechanisms of topography-enhanced neuronal differentiation are further revealed by directing suppression of mitogen-activated protein kinase/extracellular signaling-regulated kinase (MAPK/Erk) signaling pathway in ANSC using U0126, known to inhibit the activation of Erk. The statistical results suggest MAPK/Erk pathway is partially involved in topography-induced differentiation. These observations provide a better understanding on the different roles of topographical cues on stem cell behavior, especially on the selective differentiation, and facilitate to advance the field of stem cell therapy. PMID:23527077

  12. Spontaneously immortalised bovine mammary epithelial cells exhibit a distinct gene expression pattern from the breast cancer cells

    Directory of Open Access Journals (Sweden)

    Li Qianqian

    2010-10-01

    Full Text Available Abstract Background Spontaneous immortalisation of cultured mammary epithelial cells (MECs is an extremely rare event, and the molecular mechanism behind spontaneous immortalisation of MECs is unclear. Here, we report the establishment of a spontaneously immortalised bovine mammary epithelial cell line (BME65Cs and the changes in gene expression associated with BME65Cs cells. Results BME65Cs cells maintain the general characteristics of normal mammary epithelial cells in morphology, karyotype and immunohistochemistry, and are accompanied by the activation of endogenous bTERT (bovine Telomerase Reverse Transcriptase and stabilisation of the telomere. Currently, BME65Cs cells have been passed for more than 220 generations, and these cells exhibit non-malignant transformation. The expression of multiple genes was investigated in BME65Cs cells, senescent BMECs (bovine MECs cells, early passage BMECs cells and MCF-7 cells (a human breast cancer cell line. In comparison with early passage BMECs cells, the expression of senescence-relevant apoptosis-related gene were significantly changed in BME65Cs cells. P16INK4a was downregulated, p53 was low expressed and Bax/Bcl-2 ratio was reversed. Moreover, a slight upregulation of the oncogene c-Myc, along with an undetectable level of breast tumor-related gene Bag-1 and TRPS-1, was observed in BME65Cs cells while these genes are all highly expressed in MCF-7. In addition, DNMT1 is upregulated in BME65Cs. These results suggest that the inhibition of both senescence and mitochondrial apoptosis signalling pathways contribute to the immortality of BME65Cs cells. The expression of p53 and p16INK4a in BME65Cs was altered in the pattern of down-regulation but not "loss", suggesting that this spontaneous immortalization is possibly initiated by other mechanism rather than gene mutation of p53 or p16INK4a. Conclusions Spontaneously immortalised BME65Cs cells maintain many characteristics of normal BMEC cells and

  13. Development of dielectrophoresis MEMS device for PC12 cell patterning to elucidate nerve-network generation

    Science.gov (United States)

    Nakamachi, Eiji; Koga, Hirotaka; Morita, Yusuke; Yamamoto, Koji; Sakamoto, Hidetoshi

    2018-01-01

    We developed a PC12 cell trapping and patterning device by combining the dielectrophoresis (DEP) methodology and the micro electro mechanical systems (MEMS) technology for time-lapse observation of morphological change of nerve network to elucidate the generation mechanism of neural network. We succeeded a neural network generation, which consisted of cell body, axon and dendrites by using tetragonal and hexagonal cell patterning. Further, the time laps observations was carried out to evaluate the axonal extension rate. The axon extended in the channel and reached to the target cell body. We found that the shorter the PC12 cell distance, the less the axonal connection time in both tetragonal and hexagonal structures. After 48 hours culture, a maximum success rate of network formation was 85% in the case of 40 μm distance tetragonal structure.

  14. Series Resistance Analysis of Passivated Emitter Rear Contact Cells Patterned Using Inkjet Printing

    Directory of Open Access Journals (Sweden)

    Martha A. T. Lenio

    2012-01-01

    Full Text Available For higher-efficiency solar cell structures, such as the Passivated Emitter Rear Contact (PERC cells, to be fabricated in a manufacturing environment, potentially low-cost techniques such as inkjet printing and metal plating are desirable. A common problem that is experienced when fabricating PERC cells is low fill factors due to high series resistance. This paper identifies and attempts to quantify sources of series resistance in inkjet-patterned PERC cells that employ electroless or light-induced nickel-plating techniques followed by copper light-induced plating. Photoluminescence imaging is used to determine locations of series resistance losses in these inkjet-patterned and plated PERC cells.

  15. Nanoimprint-Transfer-Patterned Solids Enhance Light Absorption in Colloidal Quantum Dot Solar Cells

    KAUST Repository

    Kim, Younghoon

    2017-03-13

    Colloidal quantum dot (CQD) materials are of interest in thin-film solar cells due to their size-tunable bandgap and low-cost solution-processing. However, CQD solar cells suffer from inefficient charge extraction over the film thicknesses required for complete absorption of solar light. Here we show a new strategy to enhance light absorption in CQD solar cells by nanostructuring the CQD film itself at the back interface. We use two-dimensional finite-difference time-domain (FDTD) simulations to study quantitatively the light absorption enhancement in nanostructured back interfaces in CQD solar cells. We implement this experimentally by demonstrating a nanoimprint-transfer-patterning (NTP) process for the fabrication of nanostructured CQD solids with highly ordered patterns. We show that this approach enables a boost in the power conversion efficiency in CQD solar cells primarily due to an increase in short-circuit current density as a result of enhanced absorption through light-trapping.

  16. Fire Ant Allergy

    Science.gov (United States)

    ... venom in a fire ant sting will kill bacteria and some of your skin cells. This results in the formation of a blister that fills with a cloudy white material in about 24 hours. While this looks like a pus-filled lesion that should be drained, ...

  17. Patterns of cell division in the filamentous Desmidiaceae, close green algal relatives of land plants.

    Science.gov (United States)

    Hall, John D; McCourt, Richard M; Delwiche, Charles F

    2008-06-01

    Patterns of cell division and cross wall formation vary among the charophytes, green algae closely related to land plants. One group of charophytes, the conjugating green algae (Zygnematophyceae), is species-rich and is known to vary substantially in the mode of cell division, but the details of these cell division patterns and their phylogenetic distribution remain poorly understood. We studied cross wall development in filamentous Desmidiaceae (a clade of conjugating green algae) using differential interference contrast and fluorescence light microscopy. All strains investigated had centripetal encroachment of a septum, but with several different developmental patterns. In most cases, cell wall formation was delayed with respect to the Cosmarium-type of cell division, and the cross wall was modified considerably after deposition in a manner specific to the particular clade of filamentous desmids. These characteristics were mapped on a phylogeny estimated from a data set of two organellar genes, and the evolutionary implications of the character state distribution were evaluated. The data suggest a complex history of evolution of cell division in this lineage and also imply that Desmidium and Spondylosium are polyphyletic. These results indicate that many features of the cell shape are determined at the time of cell division in conjugating green algae.

  18. Multilineage differentiation of porcine bone marrow stromal cells associated with specific gene expression pattern

    DEFF Research Database (Denmark)

    Zou, Lijin; Zou, Xuenong; Chen, Li

    2008-01-01

    genes. However, it is not fully clear whether multilineage differentiation (osteogenesis, chondrogenesis, and adipogenesis) of BMSC is associated with a specific gene expression pattern. In the present study, we investigated the gene expression pattern of representative transcription factors and marker......There are increasing reports regarding differentiation of bone marrow stromal cells (BMSC) from human and various species of animals including pigs. The phenotype and function of BMSC along a mesenchymal lineage differentiation are well characterized by specific transcription factors and marker...

  19. Hippocampal Offline Reactivation Consolidates Recently Formed Cell Assembly Patterns during Sharp Wave-Ripples

    OpenAIRE

    van de Ven, Gido M.; Trouche, Stéphanie; McNamara, Colin G.; Allen, Kevin; Dupret, David

    2016-01-01

    Summary The ability to reinstate neuronal assemblies representing mnemonic information is thought to require their consolidation through offline reactivation during sleep/rest. To test this, we detected cell assembly patterns formed by repeated neuronal co-activations in the mouse hippocampus during exploration of spatial environments. We found that the reinstatement of assembly patterns representing a novel, but not a familiar, environment correlated with their offline reactivation and was i...

  20. Cell pattern in the Arabidopsis root epidermis determined by lateral inhibition with feedback.

    Science.gov (United States)

    Lee, Myeong Min; Schiefelbein, John

    2002-03-01

    In the root epidermis of Arabidopsis, hair and nonhair cell types are specified in a distinct position-dependent pattern. Here, we show that transcriptional feedback loops between the WEREWOLF (WER), CAPRICE (CPC), and GLABRA2 (GL2) genes help to establish this pattern. Positional cues bias the expression of the WER MYB gene, leading to the induction of CPC and GL2 in cells located in a particular position (N) and adoption of the nonhair fate. The truncated MYB encoded by CPC mediates a lateral inhibition mechanism to negatively regulate WER, GL2, and its own gene in the alternative position (H) to induce the hair fate. These results provide a molecular genetic framework for understanding the determination of a cell-type pattern in plants.

  1. 3D Reconstitution of the Patterned Neural Tube from Embryonic Stem Cells

    Science.gov (United States)

    Meinhardt, Andrea; Eberle, Dominic; Tazaki, Akira; Ranga, Adrian; Niesche, Marco; Wilsch-Bräuninger, Michaela; Stec, Agnieszka; Schackert, Gabriele; Lutolf, Matthias; Tanaka, Elly M.

    2014-01-01

    Summary Inducing organogenesis in 3D culture is an important aspect of stem cell research. Anterior neural structures have been produced from large embryonic stem cell (ESC) aggregates, but the steps involved in patterning such complex structures have been ill defined, as embryoid bodies typically contained many cell types. Here we show that single mouse ESCs directly embedded in Matrigel or defined synthetic matrices under neural induction conditions can clonally form neuroepithelial cysts containing a single lumen in 3D. Untreated cysts were uniformly dorsal and could be ventralized to floor plate (FP). Retinoic acid posteriorized cysts to cervical levels and induced localize FP formation yielding full patterning along the dorsal/ventral (DV) axis. Correct spatial organization of motor neurons, interneurons, and dorsal interneurons along the DV axis was observed. This system serves as a valuable tool for studying morphogen action in 3D and as a source of patterned spinal cord tissue. PMID:25454634

  2. 3D Reconstitution of the Patterned Neural Tube from Embryonic Stem Cells

    Directory of Open Access Journals (Sweden)

    Andrea Meinhardt

    2014-12-01

    Full Text Available Inducing organogenesis in 3D culture is an important aspect of stem cell research. Anterior neural structures have been produced from large embryonic stem cell (ESC aggregates, but the steps involved in patterning such complex structures have been ill defined, as embryoid bodies typically contained many cell types. Here we show that single mouse ESCs directly embedded in Matrigel or defined synthetic matrices under neural induction conditions can clonally form neuroepithelial cysts containing a single lumen in 3D. Untreated cysts were uniformly dorsal and could be ventralized to floor plate (FP. Retinoic acid posteriorized cysts to cervical levels and induced localize FP formation yielding full patterning along the dorsal/ventral (DV axis. Correct spatial organization of motor neurons, interneurons, and dorsal interneurons along the DV axis was observed. This system serves as a valuable tool for studying morphogen action in 3D and as a source of patterned spinal cord tissue.

  3. Fire ants

    Science.gov (United States)

    ... 222-1222) from anywhere in the United States. Poisonous Ingredient Fire ant venom contains a chemical called ... Elsevier Saunders; 2013:chap 140. Otten EJ. Venomous animal injuries. In: Walls RM, Hockberger RS, Gausche-Hill ...

  4. Fire safety

    International Nuclear Information System (INIS)

    Keski-Rahkonen, O.; Bjoerkman, J.; Hostikka, S.; Mangs, J.; Huhtanen, R.; Palmen, H.; Salminen, A.; Turtola, A.

    1998-01-01

    According to experience and probabilistic risk assessments, fires present a significant hazard in a nuclear power plant. Fires may be initial events for accidents or affect safety systems planned to prevent accidents and to mitigate their consequences. The project consists of theoretical work, experiments and simulations aiming to increase the fire safety at nuclear power plants. The project has four target areas: (1) to produce validated models for numerical simulation programmes, (2) to produce new information on the behavior of equipment in case of fire, (3) to study applicability of new active fire protecting systems in nuclear power plants, and (4) to obtain quantitative knowledge of ignitions induced by important electric devices in nuclear power plants. These topics have been solved mainly experimentally, but modelling at different level is used to interpret experimental data, and to allow easy generalisation and engineering use of the obtained data. Numerical fire simulation has concentrated in comparison of CFD modelling of room fires, and fire spreading on cables on experimental data. So far the success has been good to fair. A simple analytical and numerical model has been developed for fire effluents spreading beyond the room of origin in mechanically strongly ventilated compartments. For behaviour of equipment in fire several full scale and scaled down calorimetric experiments were carried out on electronic cabinets, as well as on horizontal and vertical cable trays. These were carried out to supply material for CFD numerical simulation code validation. Several analytical models were developed and validated against obtained experimental results to allow quick calculations for PSA estimates as well as inter- and extrapolations to slightly different objects. Response times of different commercial fire detectors were determined for different types of smoke, especially emanating from smoldering and flaming cables to facilitate selection of proper detector

  5. Study of homing patterns of x-irradiated murine lymphoid cells

    International Nuclear Information System (INIS)

    Crouse, D.A.

    1974-01-01

    Effects of in vitro x-ray exposure of murine lymphoid cells on their subsequent in vivo homing patterns were studied. The homing of lymphoid cells to various tissues and organs was followed by using radio-labeled cell preparations or by following the distribution of cells with a specific immunological memory. X irradiation of 51 Cr-labeled spleen, lymph node, bone marrow, or thymus cells was found to significantly alter their subsequent in vivo distribution. Irradiated cells demonstrated an increased distribution to the liver and a significantly lower retention in the lungs. Cells going to the lymph nodes of Peyer's patches showed a significant exposure dependent decrease in homing following irradiation. Irradiated lymph node cells homed in greater numbers to the spleen and bone marrow, while irradiated cells from other sources showed a decrease or no change indistribution to the same tissues. Lymph node cell suspensions from dinitrophenyl-bovine gamma globulin (DNP-BGG) immune LBN rats were prepared, irradiated (0 and 200 R) and injected into intermediate (LBN) hosts and controls. Irradiated memory cells provided a secondary antibody response, which was delayed but not suppressed when compared to unirradiated cells. Alteration in homing of lymphocytes caused by various physical and chemical agents was a result of effects on cell membrane characteristics which controlled some aspects of the phenomenon. Radiation (100 to 200 R) may have had a similar effect or it may have resulted in the selective elimination of a population of cells. (U.S.)

  6. Variability in the recognition of distinctive immunofluorescence patterns in different brands of HEp-2 cell slides

    Directory of Open Access Journals (Sweden)

    Alessandra Dellavance

    2013-06-01

    Full Text Available INTRODUCTION: Indirect immunofluorescence on HEp-2 cells is considered the gold standard for the detection of autoantibodies against cellular antigens. However, the culture conditions, cell fixation and permeabilization processes interfere directly in the preservation and spatial distribution of antigens. Therefore, one can assume that certain peculiarities in the processing of cellular substrate may affect the recognition of indirect immunofluorescence patterns associated with several autoantibodies. OBJECTIVE: To evaluate a panel of serum samples representing nuclear, nucleolar, cytoplasmic, mitotic apparatus, and chromosome plate patterns on HEp-2 cell substrates from different suppliers. MATERIALS AND METHODS: Seven blinded observers, independent from the three selected reference centers, evaluated 17 samples yielding different nuclear, nucleolar, cytoplasmic and mitotic apparatus patterns on HEp-2 cell slides from eight different brands. The slides were coded to maintain confidentiality of both brands and participating centers. RESULTS: The 17 HEp-2 cell patterns were identified on most substrates. Nonetheless, some slides showed deficit in the expression of several patterns: nuclear coarse speckled/U1-ribonucleoprotein associated with antibodies against RNP (U1RNP, centromeric protein F (CENP-F, proliferating cell nuclear antigen (PCNA, cytoplasmic fine speckled associated with anti-Jo-1 antibodies (histidyl synthetase, nuclear mitotic apparatus protein 1 (NuMA-1 and nuclear mitotic apparatus protein 2 (NuMA-2. CONCLUSION: Despite the overall good quality of the assessed HEp-2 substrates, there was considerable inconsistency in results among different commercial substrates. The variations may be due to the evaluated batches, hence generalizations cannot be made as to the respective brands. It is recommended that each new batch or new brand be tested with a panel of reference sera representing the various patterns.

  7. Design of flow-field patterns for proton exchange membrane fuel cell application

    International Nuclear Information System (INIS)

    Rosli, M.I.; Wan Ramli Wan Daud; Kamaruzzaman Sopian; Jaafar Sahari

    2006-01-01

    Fuel cells are electrochemical devices that produce electricity at high efficiency without combustion. Fuel cells are emerging as viable candidates as power sources in many applications, including road vehicles, small-scale power stations, and possibly even portable electronics. This paper addresses the design of flow-field patterns for proton exchange membrane fuel cell (PEMFC). The PEMFC is a low-temperature fuel cell, in which a proton conductive polymer membrane is used as the electrolyte. In PEMFC, flow-field pattern is one important thing that effects the performance of PEMFC. This paper present three types of flow-field pattern that will be consider to be testing using CFD analysis and by experimental. The design look detail on to their shape and dimension to get the best pattern in term of more active electrode area compare to electrode area that will be used. Another advantage and disadvantage for these three type of flow-field patterns from literature also compared in this paper

  8. Pulmonary involvement of peripheral T-cell lymphoma manifesting as crazy paving pattern.

    Science.gov (United States)

    Fraser, Traci; Nagarur, Amulya

    2015-01-01

    Crazy paving pattern is a finding on computed tomography of the chest that is characterized by interlobular septal thickening and ground-glass opacities. Though classically associated with pulmonary alveolar proteinosis, the differential diagnosis for this pattern is broad, and initial workup includes bronchoscopy with bronchoalveolar lavage to evaluate for malignancy, diffuse alveolar hemorrhage, pulmonary alveolar proteinosis, infection, and eosinophilic pneumonia. Herein we present an unusual case of peripheral T-cell lymphoma not otherwise specified (PTCL NOS) with pulmonary involvement that demonstrated crazy paving pattern. The diagnosis was confirmed after cytology from bronchoalveolar lavage revealed atypical lymphocytes with an immunologic profile consistent with the patient's known PTCL NOS.

  9. Structure of polarization-resolved conoscopic patterns of planar oriented liquid crystal cells

    Science.gov (United States)

    Kiselev, A. D.; Vovk, R. G.

    2010-05-01

    The geometry of distributions of the polarization of light in conoscopic patterns of planar oriented nematic and cholesteric liquid crystal (LC) cells is described in terms of the polarization singularities including C-points (points of circular polarization) and L lines (lines of linear polarization). Conditions for the formation of polarization singularities ( C-points) in an ensemble of conoscopic patterns parametrized by the polarization azimuth and ellipticity of the incident light wave have been studied. A characteristic feature of these conditions is selectivity with respect to the polarization parameters of the incident light wave. The polarization azimuth and ellipticity are determining parameters for nematic and cholesteric LC cells, respectively.

  10. The influence of a water current on the larval deposition pattern of females of a diverging fire salamander population (Salamandra salamandra)

    NARCIS (Netherlands)

    Krause, E.T.; Caspers, B.A.

    2015-01-01

    Fire salamanders are amphibians that exhibit a highly specific reproductive mode termed ovo-viviparity. The eggs develop inside their mothers, and the females give birth to fully developed larvae. The larvae in our study area cluster in two distinct genetic groups that can be linked directly to the

  11. Fire risk in the road landscape patterns of the state of Paraná, Brazil - planning grants for the wildland-urban interface

    Science.gov (United States)

    Daniela Biondi; Antonio Carlos Batista; Angeline Martini

    2013-01-01

    Urban growth worldwide has generated great concern in the planning of the different environments belonging to the wildland-urban interface. One of the problems that arise is the landscape treatment given to roads, which must not only comply with aesthetic and ecological principles, but also be functional, adding functions relating to forest fire prevention and control...

  12. Patterned three-dimensional encapsulation of embryonic stem cells using dielectrophoresis and stereolithography.

    Science.gov (United States)

    Bajaj, Piyush; Marchwiany, Daniel; Duarte, Carlos; Bashir, Rashid

    2013-03-01

    Controlling the assembly of cells in three dimensions is very important for engineering functional tissues, drug screening, probing cell-cell/cell-matrix interactions, and studying the emergent behavior of cellular systems. Although the current methods of cell encapsulation in hydrogels can distribute them in three dimensions, these methods typically lack spatial control of multi-cellular organization and do not allow for the possibility of cell-cell contacts as seen for the native tissue. Here, we report the integration of dielectrophoresis (DEP) with stereolithography (SL) apparatus for the spatial patterning of cells on custom made gold micro-electrodes. Afterwards, they are encapsulated in poly (ethylene glycol) diacrylate (PEGDA) hydrogels of different stiffnesses. This technique can mimic the in vivo microscale tissue architecture, where the cells have a high degree of three dimensional (3D) spatial control. As a proof of concept, we show the patterning and encapsulation of mouse embryonic stem cells (mESCs) and C2C12 skeletal muscle myoblasts. mESCs show high viability in both the DEP (91.79% ± 1.4%) and the no DEP (94.27% ± 0.5%) hydrogel samples. Furthermore, we also show the patterning of mouse embryoid bodies (mEBs) and C2C12 spheroids in the hydrogels, and verify their viability. This robust and flexible in vitro platform can enable various applications in stem cell differentiation and tissue engineering by mimicking elements of the native 3D in vivo cellular micro-environment. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Selective deposition contact patterning using atomic layer deposition for the fabrication of crystalline silicon solar cells

    International Nuclear Information System (INIS)

    Cho, Young Joon; Shin, Woong-Chul; Chang, Hyo Sik

    2014-01-01

    Selective deposition contact (SDC) patterning was applied to fabricate the rear side passivation of crystalline silicon (Si) solar cells. By this method, using screen printing for contact patterning and atomic layer deposition for the passivation of Si solar cells with Al 2 O 3 , we produced local contacts without photolithography or any laser-based processes. Passivated emitter and rear-contact solar cells passivated with ozone-based Al 2 O 3 showed, for the SDC process, an up-to-0.7% absolute conversion-efficiency improvement. The results of this experiment indicate that the proposed method is feasible for conversion-efficiency improvement of industrial crystalline Si solar cells. - Highlights: • We propose a local contact formation process. • Local contact forms a screen print and an atomic layer deposited-Al 2 O 3 film. • Ozone-based Al 2 O 3 thin film was selectively deposited onto patterned silicon. • Selective deposition contact patterning method can increase cell-efficiency by 0.7%

  14. Nonreassuring fetal heart rate patterns and nucleated red blood cells in term neonates.

    Science.gov (United States)

    Kovalak, E Ebru; Dede, F Suat; Gelisen, Orhan; Dede, Hulya; Haberal, Ali

    2011-05-01

    The aim of this study was to evaluate the association between nonreassuring fetal heart rate patterns during labor and umbilical cord nucleated red blood cell counts. Nucleated red blood cell data was collected prospectively from 41 singleton term neonates presented with nonreassuring fetal heart rate patterns and/or meconium stained amniotic fluid during labor (study group) and from 45 term neonates without any evidence of nonreassuring fetal status (controls). Umbilical artery pH, blood gases and base excess were also determined to investigate the correlation between independent variables. The median nucleated red blood cells per 100 white blood cells were 13 (range 0-37) in the study group and 8 (range 0-21) in the control group. Stepwise regression analysis have identified meconium stained amniotic fluid (R(2) = 0.15, p patterns. Nucleated red blood cells in the cord blood of newborns were found to be elevated in patients with nonreassuring FHR patterns during labor. However, the wide range and the poor correlation of NRBC count with umbilical artery pH and blood gas values limit its clinical utility as a marker for fetal hypoxia.

  15. Defining pyromes and global syndromes of fire regimes

    CSIR Research Space (South Africa)

    Archibald, S

    2013-04-01

    Full Text Available datasets to represent each. We assessed how these global fire regime characteristics are related to patterns of climate, vegetation (biomes), and human activity. Cross-correlations demonstrate that only certain combinations of fire characteristics...

  16. Spatial distribution of human-caused forest fires in Galicia (NW Spain)

    Science.gov (United States)

    M. L. Chas-Amil; J. Touza; P. Prestemon

    2010-01-01

    It is crucial for fire prevention policies to assess the spatial patterns of human-started fires and their relationship with geographical and socioeconomic aspects. This study uses fire reports for the period 1988-2006 in Galicia, Spain, to analyze the spatial distribution of human-induced fire risk attending to causes and underlying motivations associated with fire...

  17. Investigation of effect of stopping supply flow into the cell on the confinement of the radioactive materials under fire accident

    International Nuclear Information System (INIS)

    Abe, Hitoshi; Watanabe, Koji

    1999-03-01

    On November 20th 1997, a fire accident happened at Uranium Enrichment Research Laboratory, Tokai, Japan Atomic Energy Research Institute and ventilation filters in the laboratory clogged. When fire accident occurs in a controlled area, a large quantity of smoke generates in the area and dropping exhaust flow from the area by the clogging of ventilation filters and rising pressure in the area are caused. Moreover, leakage of smoke including radioactive materials from the area by the pressure rising is expected. To prevent the leakage, it is expected that stopping supply flow to the area during a fire accident is effective, however, quantitative evaluation about this effect has not been performed. By using CELVA-1D code, one-dimensional thermofluid analysis code, this effect is evaluated quantitatively by modeling the laboratory and estimating source terms released during the fire accident. As the results, it has been found that the efficiency of confinement of the radioactive materials into the area is preserved in the slightly long period of time in case of stopping supply flow to the area, however, this effect can be neglected in case that scale of fire accident is relatively large. (author)

  18. Patterning of stomata in the moss Funaria: a simple way to space guard cells.

    Science.gov (United States)

    Merced, Amelia; Renzaglia, Karen S

    2016-05-01

    Studies on stomatal development and the molecular mechanisms controlling patterning have provided new insights into cell signalling, cell fate determination and the evolution of these processes in plants. To fill a major gap in knowledge of stomatal patterning, this study describes the pattern of cell divisions that give rise to stomata and the underlying anatomical changes that occur during sporophyte development in the moss Funaria. Developing sporophytes at different stages were examined using light, fluorescence and electron microscopy; immunogold labelling was used to investigate the presence of pectin in the newly formed cavities. Substomatal cavities are liquid-filled when formed and drying of spaces is synchronous with pore opening and capsule expansion. Stomata in mosses do not develop from a self-generating meristemoid as in Arabidopsis, but instead they originate from a protodermal cell that differentiates directly into a guard mother cell. Epidermal cells develop from protodermal or other epidermal cells, i.e. there are no stomatal lineage ground cells. Development of stomata in moss occurs by differentiation of guard mother cells arranged in files and spaced away from each other, and epidermal cells that continue to divide after stomata are formed. This research provides evidence for a less elaborated but effective mechanism for stomata spacing in plants, and we hypothesize that this operates by using some of the same core molecular signalling mechanism as angiosperms. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Mechanical Model of Geometric Cell and Topological Algorithm for Cell Dynamics from Single-Cell to Formation of Monolayered Tissues with Pattern

    KAUST Repository

    Kachalo, Sëma

    2015-05-14

    Geometric and mechanical properties of individual cells and interactions among neighboring cells are the basis of formation of tissue patterns. Understanding the complex interplay of cells is essential for gaining insight into embryogenesis, tissue development, and other emerging behavior. Here we describe a cell model and an efficient geometric algorithm for studying the dynamic process of tissue formation in 2D (e.g. epithelial tissues). Our approach improves upon previous methods by incorporating properties of individual cells as well as detailed description of the dynamic growth process, with all topological changes accounted for. Cell size, shape, and division plane orientation are modeled realistically. In addition, cell birth, cell growth, cell shrinkage, cell death, cell division, cell collision, and cell rearrangements are now fully accounted for. Different models of cell-cell interactions, such as lateral inhibition during the process of growth, can be studied in detail. Cellular pattern formation for monolayered tissues from arbitrary initial conditions, including that of a single cell, can also be studied in detail. Computational efficiency is achieved through the employment of a special data structure that ensures access to neighboring cells in constant time, without additional space requirement. We have successfully generated tissues consisting of more than 20,000 cells starting from 2 cells within 1 hour. We show that our model can be used to study embryogenesis, tissue fusion, and cell apoptosis. We give detailed study of the classical developmental process of bristle formation on the epidermis of D. melanogaster and the fundamental problem of homeostatic size control in epithelial tissues. Simulation results reveal significant roles of solubility of secreted factors in both the bristle formation and the homeostatic control of tissue size. Our method can be used to study broad problems in monolayered tissue formation. Our software is publicly

  20. Mechanical model of geometric cell and topological algorithm for cell dynamics from single-cell to formation of monolayered tissues with pattern.

    Directory of Open Access Journals (Sweden)

    Sëma Kachalo

    Full Text Available Geometric and mechanical properties of individual cells and interactions among neighboring cells are the basis of formation of tissue patterns. Understanding the complex interplay of cells is essential for gaining insight into embryogenesis, tissue development, and other emerging behavior. Here we describe a cell model and an efficient geometric algorithm for studying the dynamic process of tissue formation in 2D (e.g. epithelial tissues. Our approach improves upon previous methods by incorporating properties of individual cells as well as detailed description of the dynamic growth process, with all topological changes accounted for. Cell size, shape, and division plane orientation are modeled realistically. In addition, cell birth, cell growth, cell shrinkage, cell death, cell division, cell collision, and cell rearrangements are now fully accounted for. Different models of cell-cell interactions, such as lateral inhibition during the process of growth, can be studied in detail. Cellular pattern formation for monolayered tissues from arbitrary initial conditions, including that of a single cell, can also be studied in detail. Computational efficiency is achieved through the employment of a special data structure that ensures access to neighboring cells in constant time, without additional space requirement. We have successfully generated tissues consisting of more than 20,000 cells starting from 2 cells within 1 hour. We show that our model can be used to study embryogenesis, tissue fusion, and cell apoptosis. We give detailed study of the classical developmental process of bristle formation on the epidermis of D. melanogaster and the fundamental problem of homeostatic size control in epithelial tissues. Simulation results reveal significant roles of solubility of secreted factors in both the bristle formation and the homeostatic control of tissue size. Our method can be used to study broad problems in monolayered tissue formation. Our software

  1. Single-cell profiling reveals heterogeneity and functional patterning of GPCR expression in the vascular system.

    Science.gov (United States)

    Kaur, H; Carvalho, J; Looso, M; Singh, P; Chennupati, R; Preussner, J; Günther, S; Albarrán-Juárez, J; Tischner, D; Classen, S; Offermanns, S; Wettschureck, N

    2017-06-16

    G-protein-coupled receptor (GPCR) expression is extensively studied in bulk cDNA, but heterogeneity and functional patterning of GPCR expression in individual vascular cells is poorly understood. Here, we perform a microfluidic-based single-cell GPCR expression analysis in primary smooth muscle cells (SMC) and endothelial cells (EC). GPCR expression is highly heterogeneous in all cell types, which is confirmed in reporter mice, on the protein level and in human cells. Inflammatory activation in murine models of sepsis or atherosclerosis results in characteristic changes in the GPCR repertoire, and we identify functionally relevant subgroups of cells that are characterized by specific GPCR patterns. We further show that dedifferentiating SMC upregulate GPCRs such as Gpr39, Gprc5b, Gprc5c or Gpr124, and that selective targeting of Gprc5b modulates their differentiation state. Taken together, single-cell profiling identifies receptors expressed on pathologically relevant subpopulations and provides a basis for the development of new therapeutic strategies in vascular diseases.

  2. Functional Virtual Flow Cytometry: A Visual Analytic Approach for Characterizing Single-Cell Gene Expression Patterns

    Directory of Open Access Journals (Sweden)

    Zhi Han

    2017-01-01

    Full Text Available We presented a novel workflow for detecting distribution patterns in cell populations based on single-cell transcriptome study. With the fast adoption of single-cell analysis, a challenge to researchers is how to effectively extract gene features to meaningfully separate the cell population. Considering that coexpressed genes are often functionally or structurally related and the number of coexpressed modules is much smaller than the number of genes, our workflow uses gene coexpression modules as features instead of individual genes. Thus, when the coexpressed modules are summarized into eigengenes, not only can we interactively explore the distribution of cells but also we can promptly interpret the gene features. The interactive visualization is aided by a novel application of spatial statistical analysis to the scatter plots using a clustering index parameter. This parameter helps to highlight interesting 2D patterns in the scatter plot matrix (SPLOM. We demonstrated the effectiveness of the workflow using two large single-cell studies. In the Allen Brain scRNA-seq dataset, the visual analytics suggested a new hypothesis such as the involvement of glutamate metabolism in the separation of the brain cells. In a large glioblastoma study, a sample with a unique cell migration related signature was identified.

  3. Wildland fire as a self-regulating mechanism: the role of previous burns and weather in limiting fire progression.

    Science.gov (United States)

    Parks, Sean A; Holsinger, Lisa M; Miller, Carol; Nelson, Cara R

    2015-09-01

    Theory suggests that natural fire regimes can result in landscapes that are both self-regulating and resilient to fire. For example, because fires consume fuel, they may create barriers to the spread of future fires, thereby regulating fire size. Top-down controls such as weather, however, can weaken this effect. While empirical examples demonstrating this pattern-process feedback between vegetation and fire exist, they have been geographically limited or did not consider the influence of time between fires and weather. The availability of remotely sensed data identifying fire activity over the last four decades provides an opportunity to explicitly quantify-the ability of wildland fire to limit the progression of subsequent fire. Furthermore, advances in fire progression mapping now allow an evaluation of how daily weather as a top-down control modifies this effect. In this study, we evaluated the ability of wildland fire to create barriers that limit the spread of subsequent fire along a gradient representing time between fires in four large study areas in the western United States. Using fire progression maps in conjunction with weather station data, we also evaluated the influence of daily weather. Results indicate that wildland fire does limit subsequent fire spread in all four study areas, but this effect decays over time; wildland fire no longer limits subsequent fire spread 6-18 years after fire, depending on the study area. We also found that the ability of fire to regulate, subsequent fire progression was substantially reduced under extreme conditions compared to moderate weather conditions in all four study areas. This study increases understanding of the spatial feedbacks that can lead to self-regulating landscapes as well as the effects of top-down controls, such as weather, on these feedbacks. Our results will be useful to managers who seek to restore natural fire regimes or to exploit recent burns when managing fire.

  4. Associations between pathogen-specific clinical mastitis and somatic cell count patterns

    NARCIS (Netherlands)

    Haas, de Y.; Veerkamp, R.F.; Barkema, H.W.; Gröhn, Y.T.; Schukken, Y.H.

    2004-01-01

    Associations were estimated between pathogen-specific cases of clinical mastitis (CM) and somatic cell count (SCC) patterns based on deviations from the typical curve for SCC during lactation and compared with associations between pathogen-specific CM and lactation average SCC. Data from 274 Dutch

  5. Integrative analysis of polychaete ontogeny: cell proliferation patterns and myogenesis in trochophore larvae of Sabellaria alveolata

    DEFF Research Database (Denmark)

    Brinkmann, Nora; Wanninger, Andreas

    2010-01-01

    of this crucial mesoderm-derived organ system, particularly in indirect developing representatives of the Lophotrochozoa. Here, we document the temporal and spatial patterns of muscle formation and cell proliferation in the polychaete Sabellaria alveolata during planktotrophic larval development in order...

  6. Fungal pattern-recognition receptors and tetraspanins: partners on antigen-presenting cells.

    NARCIS (Netherlands)

    Figdor, C.G.; Spriel, A.B. van

    2010-01-01

    Fungal pattern-recognition receptors (F-PRRs), including C-type lectins, Toll-like receptors, scavenger receptors and Fc/complement receptors, are crucial for inducing anti-fungal immune responses by antigen-presenting cells. The recent identification of specific F-PRR interactions with tetraspanins

  7. Angiogenesis interactome and time course microarray data reveal the distinct activation patterns in endothelial cells.

    Directory of Open Access Journals (Sweden)

    Liang-Hui Chu

    Full Text Available Angiogenesis involves stimulation of endothelial cells (EC by various cytokines and growth factors, but the signaling mechanisms are not completely understood. Combining dynamic gene expression time-course data for stimulated EC with protein-protein interactions associated with angiogenesis (the "angiome" could reveal how different stimuli result in different patterns of network activation and could implicate signaling intermediates as points for control or intervention. We constructed the protein-protein interaction networks of positive and negative regulation of angiogenesis comprising 367 and 245 proteins, respectively. We used five published gene expression datasets derived from in vitro assays using different types of blood endothelial cells stimulated by VEGFA (vascular endothelial growth factor A. We used the Short Time-series Expression Miner (STEM to identify significant temporal gene expression profiles. The statistically significant patterns between 2D fibronectin and 3D type I collagen substrates for telomerase-immortalized EC (TIME show that different substrates could influence the temporal gene activation patterns in the same cell line. We investigated the different activation patterns among 18 transmembrane tyrosine kinase receptors, and experimentally measured the protein level of the tyrosine-kinase receptors VEGFR1, VEGFR2 and VEGFR3 in human umbilical vein EC (HUVEC and human microvascular EC (MEC. The results show that VEGFR1-VEGFR2 levels are more closely coupled than VEGFR1-VEGFR3 or VEGFR2-VEGFR3 in HUVEC and MEC. This computational methodology can be extended to investigate other molecules or biological processes such as cell cycle.

  8. Stomatal cell wall composition: distinctive structural patterns associated with different phylogenetic groups.

    Science.gov (United States)

    Shtein, Ilana; Shelef, Yaniv; Marom, Ziv; Zelinger, Einat; Schwartz, Amnon; Popper, Zoë A; Bar-On, Benny; Harpaz-Saad, Smadar

    2017-04-01

    Stomatal morphology and function have remained largely conserved throughout ∼400 million years of plant evolution. However, plant cell wall composition has evolved and changed. Here stomatal cell wall composition was investigated in different vascular plant groups in attempt to understand their possible effect on stomatal function. A renewed look at stomatal cell walls was attempted utilizing digitalized polar microscopy, confocal microscopy, histology and a numerical finite-elements simulation. The six species of vascular plants chosen for this study cover a broad structural, ecophysiological and evolutionary spectrum: ferns ( Asplenium nidus and Platycerium bifurcatum ) and angiosperms ( Arabidopsis thaliana and Commelina erecta ) with kidney-shaped stomata, and grasses (angiosperms, family Poaceae) with dumbbell-shaped stomata ( Sorghum bicolor and Triticum aestivum ). Three distinct patterns of cellulose crystallinity in stomatal cell walls were observed: Type I (kidney-shaped stomata, ferns), Type II (kidney-shaped stomata, angiosperms) and Type III (dumbbell-shaped stomata, grasses). The different stomatal cell wall attributes investigated (cellulose crystallinity, pectins, lignin, phenolics) exhibited taxon-specific patterns, with reciprocal substitution of structural elements in the end-walls of kidney-shaped stomata. According to a numerical bio-mechanical model, the end walls of kidney-shaped stomata develop the highest stresses during opening. The data presented demonstrate for the first time the existence of distinct spatial patterns of varying cellulose crystallinity in guard cell walls. It is also highly intriguing that in angiosperms crystalline cellulose appears to have replaced lignin that occurs in the stomatal end-walls of ferns serving a similar wall strengthening function. Such taxon-specific spatial patterns of cell wall components could imply different biomechanical functions, which in turn could be a consequence of differences in

  9. A visualization study on relationship between water-droplet behavior and cell voltage appeared in straight, parallel and serpentine channel pattern cells

    Science.gov (United States)

    Masuda, Hiromitsu; Yamamoto, Atsushi; Sasaki, Kazunari; Lee, Sangkun; Ito, Kohei

    It is a critical issue to understand the relationship between water-droplet behavior and cell voltage for the establishment of PEFC water management. We fabricated three cells, whose channel pattern is different: straight one channel, parallel three channels and serpentine one channel. We operated these different channel-pattern cells and visualized water droplets in cathode channel, with systematically changing operation condition to quantitatively compare the performance and water droplet behavior between the cells. Successive process of water behavior, named as flooding, plugging and flushing, emerged in every channel-pattern cell. However, the each channel pattern cell also has inherent water behavior, showing particular cell voltage variation. Within our experimental condition, the serpentine one channel cell showed a superior tolerance to flooding and the highest performance among the three cells.

  10. Characterization of the Fire Regime and Drivers of Fires in the West African Tropical Forest

    Science.gov (United States)

    Dwomoh, F. K.; Wimberly, M. C.

    2016-12-01

    The Upper Guinean forest (UGF), encompassing the tropical regions of West Africa, is a globally significant biodiversity hotspot and a critically important socio-economic and ecological resource for the region. However, the UGF is one of the most human-disturbed tropical forest ecosystems with the only remaining large patches of original forests distributed in protected areas, which are embedded in a hotspot of climate stress & land use pressures, increasing their vulnerability to fire. We hypothesized that human impacts and climate interact to drive spatial and temporal variability in fire, with fire exhibiting distinctive seasonality and sensitivity to drought in areas characterized by different population densities, agricultural practices, vegetation types, and levels of forest degradation. We used the MODIS active fire product to identify and characterize fire activity in the major ecoregions of the UGF. We used TRMM rainfall data to measure climatic variability and derived indicators of human land use from a variety of geospatial datasets. We employed time series modeling to identify the influences of drought indices and other antecedent climatic indicators on temporal patterns of active fire occurrence. We used a variety of modeling approaches to assess the influences of human activities and land cover variables on the spatial pattern of fire activity. Our results showed that temporal patterns of fire activity in the UGF were related to precipitation, but these relationships were spatially heterogeneous. The pattern of fire seasonality varied geographically, reflecting both climatological patterns and agricultural practices. The spatial pattern of fire activity was strongly associated with vegetation gradients and anthropogenic activities occurring at fine spatial scales. The Guinean forest-savanna mosaic ecoregion had the most fires. This study contributes to our understanding of UGF fire regime and the spatio-temporal dynamics of tropical forest fires in

  11. Patterned ion exchange membranes for improved power production in microbial reverse-electrodialysis cells

    KAUST Repository

    Liu, Jia

    2014-12-01

    Power production in microbial reverse-electrodialysis cells (MRCs) can be limited by the internal resistance of the reverse electrodialysis stack. Typical MRC stacks use non-conductive spacers that block ion transport by the so-called spacer shadow effect. These spacers can be relatively thick compared to the membrane, and thus they increase internal stack resistance due to high solution (ohmic) resistance associated with a thick spacer. New types of patterned anion and cation exchange membranes were developed by casting membranes to create hemispherical protrusions on the membranes, enabling fluid flow between the membranes without the need for a non-conductive spacer. The use of the patterned membrane decreased the MRC stack resistance by ∼22 Ω, resulting in a 38% increase in power density from 2.50 ± 0.04 W m-2 (non-patterned membrane with a non-conductive spacer) to 3.44 ± 0.02 W m-2 (patterned membrane). The COD removal rate, coulombic efficiency, and energy efficiency of the MRC also increased using the patterned membranes compared to the non-patterned membranes. These results demonstrate that these patterned ion exchange membranes can be used to improve performance of an MRC. © 2014 Elsevier B.V. All rights reserved.

  12. Rules and Self-Organizing Properties of Post-embryonic Plant Organ Cell Division Patterns.

    Science.gov (United States)

    von Wangenheim, Daniel; Fangerau, Jens; Schmitz, Alexander; Smith, Richard S; Leitte, Heike; Stelzer, Ernst H K; Maizel, Alexis

    2016-02-22

    Plants form new organs with patterned tissue organization throughout their lifespan. It is unknown whether this robust post-embryonic organ formation results from stereotypic dynamic processes, in which the arrangement of cells follows rigid rules. Here, we combine modeling with empirical observations of whole-organ development to identify the principles governing lateral root formation in Arabidopsis. Lateral roots derive from a small pool of founder cells in which some take a dominant role as seen by lineage tracing. The first division of the founders is asymmetric, tightly regulated, and determines the formation of a layered structure. Whereas the pattern of subsequent cell divisions is not stereotypic between different samples, it is characterized by a regular switch in division plane orientation. This switch is also necessary for the appearance of patterned layers as a result of the apical growth of the primordium. Our data suggest that lateral root morphogenesis is based on a limited set of rules. They determine cell growth and division orientation. The organ-level coupling of the cell behavior ensures the emergence of the lateral root's characteristic features. We propose that self-organizing, non-deterministic modes of development account for the robustness of plant organ morphogenesis. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Neural cell alignment by patterning gradients of the extracellular matrix protein laminin

    Science.gov (United States)

    Chelli, Beatrice; Barbalinardo, Marianna; Valle, Francesco; Greco, Pierpaolo; Bystrenova, Eva; Bianchi, Michele; Biscarini, Fabio

    2014-01-01

    Anisotropic orientation and accurate positioning of neural cells is achieved by patterning stripes of the extracellular matrix protein laminin on the surface of polystyrene tissue culture dishes by micromoulding in capillaries (MIMICs). Laminin concentration decreases from the entrance of the channels in contact with the reservoir towards the end. Immunofluorescence analysis of laminin shows a decreasing gradient of concentration along the longitudinal direction of the stripes. The explanation is the superposition of diffusion and convection of the solute, the former dominating at length scales near the entrance (characteristic length around 50 μm), the latter further away (length scale in excess of 900 μm). These length scales are independent of the channel width explored from about 15 to 45 μm. Neural cells are randomly seeded and selectively adhere to the pattern, leaving the unpatterned areas depleted even upon 6 days of incubation. Cell alignment was assessed by the orientation of the long axis of the 4′,6-diamidino-2-phenylindole-stained nuclei. Samples on patterned the laminin area exhibit a large orientational order parameter. As control, cells on the unpatterned laminin film exhibit no preferential orientation. This implies that the anisotropy of laminin stripes is an effective chemical stimulus for cell recruiting and alignment. PMID:24501672

  14. Using micro-patterned sensors and cell self-assembly for measuring the oxygen consumption rate of single cells

    International Nuclear Information System (INIS)

    Etzkorn, James R; Parviz, Babak A; Wu, Wen-Chung; Tian, Zhiyuan; Kim, Prince; Jang, Sei-Hum; Jen, Alex K-Y; Meldrum, Deirdre R

    2010-01-01

    We present a method for self-assembling arrays of live single cells on a glass chip using a photopatternable polymer to form micro-traps. We have studied the single-cell self-assembly method and optimized the process to obtain a 52% yield of single-trapped cells. We also report a method to measure the oxygen consumption rate of a single cell using micro-patterned sensors. These molecular oxygen sensors were fabricated around each micro-trap allowing optical interrogation of oxygen concentration in the immediate environment of the trapped cell. Micromachined micro-wells were then used to seal the trap, sensor and cell in order to determine the oxygen consumption rate of single cells. These techniques reported here add to the collection of tools for performing 'singe-cell' biology. An oxygen consumption rate of 1.05 ± 0.28 fmol min −1 was found for a data set consisting of 25 single A549 cells.

  15. Effects of fire on major forest ecosystem processes: an overview.

    Science.gov (United States)

    Chen, Zhong

    2006-09-01

    Fire and fire ecology are among the best-studied topics in contemporary ecosystem ecology. The large body of existing literature on fire and fire ecology indicates an urgent need to synthesize the information on the pattern of fire effects on ecosystem composition, structure, and functions for application in fire and ecosystem management. Understanding fire effects and underlying principles are critical to reduce the risk of uncharacteristic wildfires and for proper use of fire as an effective management tool toward management goals. This overview is a synthesis of current knowledge on major effects of fire on fire-prone ecosystems, particularly those in the boreal and temperate regions of the North America. Four closely related ecosystem processes in vegetation dynamics, nutrient cycling, soil and belowground process and water relations were discussed with emphases on fire as the driving force. Clearly, fire can shape ecosystem composition, structure and functions by selecting fire adapted species and removing other susceptible species, releasing nutrients from the biomass and improving nutrient cycling, affecting soil properties through changing soil microbial activities and water relations, and creating heterogeneous mosaics, which in turn, can further influence fire behavior and ecological processes. Fire as a destructive force can rapidly consume large amount of biomass and cause negative impacts such as post-fire soil erosion and water runoff, and air pollution; however, as a constructive force fire is also responsible for maintaining the health and perpetuity of certain fire-dependent ecosystems. Considering the unique ecological roles of fire in mediating and regulating ecosystems, fire should be incorporated as an integral component of ecosystems and management. However, the effects of fire on an ecosystem depend on the fire regime, vegetation type, climate, physical environments, and the scale of time and space of assessment. More ecosystem

  16. Extraordinary Light-Trapping Enhancement in Silicon Solar Cell Patterned with Graded Photonic Super-Crystals

    Directory of Open Access Journals (Sweden)

    Safaa Hassan

    2017-12-01

    Full Text Available Light-trapping enhancement in newly discovered graded photonic super-crystals (GPSCs with dual periodicity and dual basis is herein explored for the first time. Broadband, wide-incident-angle, and polarization-independent light-trapping enhancement was achieved in silicon solar cells patterned with these GPSCs. These super-crystals were designed by multi-beam interference, rendering them flexible and efficient. The optical response of the patterned silicon solar cell retained Bloch-mode resonance; however, light absorption was greatly enhanced in broadband wavelengths due to the graded, complex unit super-cell nanostructures, leading to the overlap of Bloch-mode resonances. The broadband, wide-angle light coupling and trapping enhancement mechanism are understood to be due to the spatial variance of the index of refraction, and this spatial variance is due to the varying filling fraction, the dual basis, and the varying lattice constants in different directions.

  17. Superhydrophilic-Superhydrophobic Patterned Surfaces as High-Density Cell Microarrays: Optimization of Reverse Transfection.

    Science.gov (United States)

    Ueda, Erica; Feng, Wenqian; Levkin, Pavel A

    2016-10-01

    High-density microarrays can screen thousands of genetic and chemical probes at once in a miniaturized and parallelized manner, and thus are a cost-effective alternative to microwell plates. Here, high-density cell microarrays are fabricated by creating superhydrophilic-superhydrophobic micropatterns in thin, nanoporous polymer substrates such that the superhydrophobic barriers confine both aqueous solutions and adherent cells within each superhydrophilic microspot. The superhydrophobic barriers confine and prevent the mixing of larger droplet volumes, and also control the spreading of droplets independent of the volume, minimizing the variability that arises due to different liquid and surface properties. Using a novel liposomal transfection reagent, ScreenFect A, the method of reverse cell transfection is optimized on the patterned substrates and several factors that affect transfection efficiency and cytotoxicity are identified. Higher levels of transfection are achieved on HOOC- versus NH 2 -functionalized superhydrophilic spots, as well as when gelatin and fibronectin are added to the transfection mixture, while minimizing the amount of transfection reagent improves cell viability. Almost no diffusion of the printed transfection mixtures to the neighboring microspots is detected. Thus, superhydrophilic-superhydrophobic patterned surfaces can be used as cell microarrays and for optimizing reverse cell transfection conditions before performing further cell screenings. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Detection of viability of micro-algae cells by optofluidic hologram pattern.

    Science.gov (United States)

    Wang, Junsheng; Yu, Xiaomei; Wang, Yanjuan; Pan, Xinxiang; Li, Dongqing

    2018-03-01

    A rapid detection of micro-algae activity is critical for analysis of ship ballast water. A new method for detecting micro-algae activity based on lens-free optofluidic holographic imaging is presented in this paper. A compact lens-free optofluidic holographic imaging device was developed. This device is mainly composed of a light source, a small through-hole, a light propagation module, a microfluidic chip, and an image acquisition and processing module. The excited light from the light source passes through a small hole to reach the surface of the micro-algae cells in the microfluidic chip, and a holographic image is formed by the diffraction light of surface of micro-algae cells. The relation between the characteristics in the hologram pattern and the activity of micro-algae cells was investigated by using this device. The characteristics of the hologram pattern were extracted to represent the activity of micro-algae cells. To demonstrate the accuracy of the presented method and device, four species of micro-algae cells were employed as the test samples and the comparison experiments between the alive and dead cells of four species of micro-algae were conducted. The results show that the developed method and device can determine live/dead microalgae cells accurately.

  19. Time-sequential observation of spindle and phragmoplast orientation in BY-2 cells with altered cortical actin microfilament patterning.

    Science.gov (United States)

    Kojo, Kei H; Yasuhara, Hiroki; Hasezawa, Seiichiro

    2014-06-18

    Precise division plane determination is essential for plant development. At metaphase, a dense actin microfilament meshwork appears on both sides of the cell center, forming a characteristic cortical actin microfilament twin peak pattern in BY-2 cells. We previously reported a strong correlation between altered cortical actin microfilament patterning and an oblique mitotic spindle orientation, implying that these actin microfilament twin peaks play a role in the regulation of mitotic spindle orientation. In the present study, time-sequential observation was used to reveal the progression from oblique phragmoplast to oblique cell plate orientation in cells with altered cortical actin microfilament patterning. In contrast to cells with normal actin microfilament twin peaks, oblique phragmoplast reorientation was rarely observed in cells with altered cortical actin microfilament patterning. These results support the important roles of cortical actin microfilament patterning in division plane orientation.

  20. Are Molecular Vibration Patterns of Cell Structural Elements Used for Intracellular Signalling?

    Science.gov (United States)

    Jaross, Werner

    2016-01-01

    To date the manner in which information reaches the nucleus on that part within the three-dimensional structure where specific restorative processes of structural components of the cell are required is unknown. The soluble signalling molecules generated in the course of destructive and restorative processes communicate only as needed. All molecules show temperature-dependent molecular vibration creating a radiation in the infrared region. Each molecule species has in its turn a specific frequency pattern under given specific conditions. Changes in their structural composition result in modified frequency patterns of the molecules in question. The main structural elements of the cell membrane, of the endoplasmic reticulum, of the Golgi apparatus, and of the different microsomes representing the great variety of polar lipids show characteristic frequency patterns with peaks in the region characterised by low water absorption. These structural elements are very dynamic, mainly caused by the creation of signal molecules and transport containers. By means of the characteristic radiation, the area where repair or substitution services are needed could be identified; this spatial information complements the signalling of the soluble signal molecules. Based on their resonance properties receptors located on the outer leaflet of the nuclear envelope should be able to read typical frequencies and pass them into the nucleus. Clearly this physical signalling must be blocked by the cell membrane to obviate the flow of information into adjacent cells. If the hypothesis can be proved experimentally, it should be possible to identify and verify characteristic infrared frequency patterns. The application of these signal frequencies onto cells would open entirely new possibilities in medicine and all biological disciplines specifically to influence cell growth and metabolism. Similar to this intracellular system, an extracellular signalling system with many new therapeutic options

  1. Single-cell profiling reveals GPCR heterogeneity and functional patterning during neuroinflammation.

    Science.gov (United States)

    Tischner, Denise; Grimm, Myriam; Kaur, Harmandeep; Staudenraus, Daniel; Carvalho, Jorge; Looso, Mario; Günther, Stefan; Wanke, Florian; Moos, Sonja; Siller, Nelly; Breuer, Johanna; Schwab, Nicholas; Zipp, Frauke; Waisman, Ari; Kurschus, Florian C; Offermanns, Stefan; Wettschureck, Nina

    2017-08-03

    GPCR expression was intensively studied in bulk cDNA of leukocyte populations, but limited data are available with respect to expression in individual cells. Here, we show a microfluidic-based single-cell GPCR expression analysis in primary T cells, myeloid cells, and endothelial cells under naive conditions and during experimental autoimmune encephalomyelitis, the mouse model of multiple sclerosis. We found that neuroinflammation induces characteristic changes in GPCR heterogeneity and patterning, and we identify various functionally relevant subgroups with specific GPCR profiles among spinal cord-infiltrating CD4 T cells, macrophages, microglia, or endothelial cells. Using GPCRs CXCR4, S1P1, and LPHN2 as examples, we show how this information can be used to develop new strategies for the functional modulation of Th17 cells and activated endothelial cells. Taken together, single-cell GPCR expression analysis identifies functionally relevant subpopulations with specific GPCR repertoires and provides a basis for the development of new therapeutic strategies in immune disorders.

  2. Vegetation growth patterns on six rock-covered UMTRA Project disposal cells

    International Nuclear Information System (INIS)

    1992-02-01

    This study assessed vegetation growth patterns, the potential impacts of vegetation growth on disposal cell cover integrity, and possible measures that could be taken to monitor and/or control plant growth, where necessary, on six Uranium Mill Tailings Remedial Action (UMTRA) Project rock-covered disposal cells. A large-scale invasion of volunteer plants was observed on the Shiprock and Burrell disposal cells. Plant growth at the South Clive, Green River, and Tuba City disposal cells was sparse except for the south rock apron and south slope of the Tuba City disposal cell, where windblown sand had filled up part of the rock cover and plant growth was observed. The rock-covered topslope of the Collins Ranch disposal cell was intentionally covered with topsoil and vegetated. Plant roots growing on the disposal cells are changing the characteristics of the cover by drying out the radon barrier, encouraging the establishment of soil-building processes in the bedding and radon barrier layers, creating channels in the radon barrier, and facilitating ecological succession, which could lead to the establishment of additional deep-rooted plants on the disposal cells. If left unchecked, plant roots would reach the tailings at the Burrell and Collins Ranch disposal cells within a few years, likely resulting in the transport of contaminants out of the cells

  3. Affinity flow fractionation of cells via transient interactions with asymmetric molecular patterns

    Science.gov (United States)

    Bose, Suman; Singh, Rishi; Hanewich-Hollatz, Mikhail; Shen, Chong; Lee, Chia-Hua; Dorfman, David M.; Karp, Jeffrey M.; Karnik, Rohit

    2013-07-01

    Flow fractionation of cells using physical fields to achieve lateral displacement finds wide applications, but its extension to surface molecule-specific separation requires labeling. Here we demonstrate affinity flow fractionation (AFF) where weak, short-range interactions with asymmetric molecular patterns laterally displace cells in a continuous, label-free process. We show that AFF can directly draw neutrophils out of a continuously flowing stream of blood with an unprecedented 400,000-fold depletion of red blood cells, with the sorted cells being highly viable, unactivated, and functionally intact. The lack of background erythrocytes enabled the use of AFF for direct enumeration of neutrophils by a downstream detector, which could distinguish the activation state of neutrophils in blood. The compatibility of AFF with capillary microfluidics and its ability to directly separate cells with high purity and minimal sample preparation will facilitate the design of simple and portable devices for point-of-care diagnostics and quick, cost-effective laboratory analysis.

  4. Affinity flow fractionation of cells via transient interactions with asymmetric molecular patterns.

    Science.gov (United States)

    Bose, Suman; Singh, Rishi; Hanewich-Hollatz, Mikhail; Shen, Chong; Lee, Chia-Hua; Dorfman, David M; Karp, Jeffrey M; Karnik, Rohit

    2013-01-01

    Flow fractionation of cells using physical fields to achieve lateral displacement finds wide applications, but its extension to surface molecule-specific separation requires labeling. Here we demonstrate affinity flow fractionation (AFF) where weak, short-range interactions with asymmetric molecular patterns laterally displace cells in a continuous, label-free process. We show that AFF can directly draw neutrophils out of a continuously flowing stream of blood with an unprecedented 400,000-fold depletion of red blood cells, with the sorted cells being highly viable, unactivated, and functionally intact. The lack of background erythrocytes enabled the use of AFF for direct enumeration of neutrophils by a downstream detector, which could distinguish the activation state of neutrophils in blood. The compatibility of AFF with capillary microfluidics and its ability to directly separate cells with high purity and minimal sample preparation will facilitate the design of simple and portable devices for point-of-care diagnostics and quick, cost-effective laboratory analysis.

  5. 46 CFR 28.820 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Aleutian Trade Act Vessels § 28.820 Fire pumps, fire mains... pump connected to a fixed piping system. This pump must be capable of delivering an effective stream of...

  6. 46 CFR 28.315 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... After September 15, 1991, and That Operate With More Than 16 Individuals on Board § 28.315 Fire pumps... be equipped with a self-priming, power driven fire pump connected to a fixed piping system. (1) A...

  7. Identification of distinctive patterns of USP19-mediated growth regulation in normal and malignant cells.

    Directory of Open Access Journals (Sweden)

    Yu Lu

    2011-01-01

    Full Text Available We previously reported that the USP19 deubiquitinating enzyme positively regulates proliferation in fibroblasts by stabilizing KPC1, a ubiquitin ligase for p27(Kip1. To explore whether this role of USP19 extends to other cellular systems, we tested the effects of silencing of USP19 in several human prostate and breast models, including carcinoma cell lines. Depletion of USP19 inhibited proliferation in prostate cancer DU145, PC-3 and 22RV1 cells, which was similar to the pattern established in fibroblasts in that it was due to decreased progression from G1 to S phase and associated with a stabilization of the cyclin-dependent kinase inhibitor p27(Kip1. However, in contrast to previous findings in fibroblasts, the stabilization of p27(Kip1 upon USP19 depletion was not associated with changes in the levels of the KPC1 ligase. USP19 could also regulate the growth of immortalized MCF10A breast epithelial cells through a similar mechanism. This regulatory pattern was lost, though, in breast cancer MCF7 and MDA-MB-231 cells and in prostate carcinoma LNCaP cells. Of interest, the transformation of fibroblasts through overexpression of an oncogenic form of Ras disrupted the USP19-mediated regulation of cell growth and of levels of p27(Kip1 and KPC1. Thus, the cell context appears determinant for the ability of USP19 to regulate cell proliferation and p27(Kip1 levels. This may occur through both KPC1 dependent and independent mechanisms. Moreover, a complete loss of USP19 function on cell growth may arise as a result of oncogenic transformation of cells.

  8. In vitro analysis suggests that difference in cell movement during direct interaction can generate various pigment patterns in vivo.

    Science.gov (United States)

    Yamanaka, Hiroaki; Kondo, Shigeru

    2014-02-04

    Pigment patterns of organisms have invoked strong interest from not only biologists but also, scientists in many other fields. Zebrafish is a useful model animal for studying the mechanism of pigment pattern formation. The zebrafish stripe pattern is primarily two types of pigment cells: melanophores and xanthophores. Previous studies have reported that interactions among these pigment cells are important for pattern formation. In the recent report, we found that the direct contact by xanthophores induces the membrane depolarization of melanophores. From analysis of jaguar mutants, it is suggested that the depolarization affects the movements of melanophores. To analyze the cell movement in detail, we established a unique in vitro system. It allowed us to find that WT xanthophores induced repulsive movement of melanophores through direct contact. The xanthophores also chased the melanophores. As a result, they showed run-and-chase movements. We also analyzed the cell movement of pigment cells from jaguar and leopard mutants, which have fuzzy stripes and spot patterns, respectively. jaguar cells showed inhibited run-and-chase movements, and leopard melanophores scarcely showed repulsive response. Furthermore, we paired mutant and WT cells and showed which of the melanophores and xanthophores have responsibility for the altered cell movements. These results suggested that there is a correspondence relationship between the cell movements and pigment patterns. The correspondence relationship highlighted the importance of the cell movements in the pattern formation and showed that our system is a quite useful system for future study in this field.

  9. Simulation of Burn Probabilities and Fire Size Distributions for the Western United States

    Science.gov (United States)

    Finney, M.

    2009-04-01

    This simulation research was conducted on behalf of five U.S. land management agencies in order to develop a fire risk assessment system for the contiguous land area of the United States. The requirements included generating burn probabilities, characterizing fire behavior variation, and providing a means to evaluate sensitivity to both fire suppression and fuel treatment effects. This paper presents the methods and results of wildland fire size distributions and burn probabilities that were simulated for large units of land that together comprised the entire western United States. The outputs of these simulations are compared with historic data from Federal lands. The methods involved simulating fire ignition and growth for 10,000 to 20,000 "years" of artificial weather. The fire growth simulations were based on previously published methods (Finney 1998, 2002) and, when run repeatedly with different weather and ignition locations, produce fire behavior distributions at each landscape location (e.g. a "cell"). The artificial weather was generated using 1) a time-series analysis of recorded fire danger rating indices for each land unit that served as a proxy of daily and seasonal variation in fuel moisture, and 2) distributions of wind speed and direction from weather records in each unit. The simulations also required spatial data on fuel structure and topography which were provided by the LandFire project for the study area (http://www.landfire.gov). The occurrence and frequency of ignitions were simulated stochastically using empirical relationships that predicted the probability of large fire occurrence from the fire danger rating index. Fire suppression was represented using a modeling analysis of 453 large fires that was used to predict the probability of fire containment (by suppression forces) based on independent predictors of fire growth rates and fuel type. Fuel treatments were implemented into the fuel structure of the landscape to evaluate how these

  10. Changes in Chromosome Counts and Patterns in CHO Cell Lines upon Generation of Recombinant Cell Lines and Subcloning.

    Science.gov (United States)

    Vcelar, Sabine; Melcher, Michael; Auer, Norbert; Hrdina, Astrid; Puklowski, Anja; Leisch, Friedrich; Jadhav, Vaibhav; Wenger, Till; Baumann, Martina; Borth, Nicole

    2018-03-01

    Chinese hamster ovary (CHO) cells are the number one production system for therapeutic proteins. A pre-requirement for their use in industrial production of biopharmaceuticals is to be clonal, thus originating from a single cell in order to be phenotypically and genomically identical. In the present study it was evaluated whether standard procedures, such as the generation of a recombinant cell line in combination with selection for a specific and stable phenotype (expression of the recombinant product) or subcloning have any impact on karyotype stability or homogeneity in CHO cells. Analyses used were the distribution of chromosome counts per cell as well as chromosome painting to identify specific karyotype patterns within a population. Results indicate that subclones both of the host and the recombinant cell line are of comparable heterogeneity and (in)stability as the original pool. In contrast, the rigorous selection for a stably expressing phenotype generated cell lines with fewer variation and more stable karyotypes, both at the level of the sorted pool and derivative subclones. We conclude that the process of subcloning itself does not contribute to an improved karyotypic homogeneity of a population, while the selection for a specific cell property inherently can provide evolutionary pressure that may lead to improved chromosomal stability as well as to a more homogenous population. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Fire Synthesis

    Indian Academy of Sciences (India)

    special infrastructure which require careful maintenance. In such situation fire synthesis is a simpler method that can be adopted for the bulk production of high purity .... reaction between Ti and B to form titanium boride. The reaction between titanium (fuel- electron donor) and boron (oxidiser-electron acceptor) once initiated ...

  12. Forest Fires

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 11. Forest Fires - Origins and Ecological Paradoxes. K Narendran. General Article Volume 6 Issue 11 November 2001 pp 34-41. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/006/11/0034-0041 ...

  13. Fire Synthesis

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Fire Synthesis - Preparation of Alumina Products. Tanu Mimani. Volume 16 Issue 12 December 2011 pp 1324-1332. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/016/12/1324-1332 ...

  14. Fire Synthesis

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 2. Fire Synthesis - Preparation of Alumina Products. Tanu Mimani. General Article Volume 5 Issue 2 February 2000 pp 50-57. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/005/02/0050-0057 ...

  15. Dielectric screening of early differentiation patterns in mesenchymal stem cells induced by steroid hormones.

    Science.gov (United States)

    Ron, Amit; Shur, Irena; Daniel, Ramiz; Singh, Ragini Raj; Fishelson, Nick; Croitoru, Nathan; Benayahu, Dafna; Shacham-Diamand, Yosi

    2010-06-01

    In the framework of this study, target identification and localization of differentiation patterns by means of dielectric spectroscopy is presented. Here, a primary pre-osteoblastic bone marrow-derived MBA-15 cellular system was used to study the variations in the dielectric properties of mesenchymal stem cells while exposed to differentiation regulators. Using the fundamentals of mixed dielectric theories combined with finite numerical tools, the permittivity spectra of MBA-15 cell suspensions have been uniquely analyzed after being activated by steroid hormones to express osteogenic phenotypes. Following the spectral analysis, significant variations were revealed in the dielectric properties of the activated cells in comparison to the untreated populations. Based on the differentiation patterns of MBA-15, the electrical modifications were found to be highly correlated with the activation of specific cellular mechanisms which directly react to the hormonal inductions. In addition, by describing the dielectric dispersion in terms of transfer functions, it is shown that the spectral perturbations are well adapted to variations in the electrical characteristics of the cells. The reported findings vastly emphasize the tight correlation between the cellular and electrical state of the differentiated cells. It therefore emphasizes the vast abilities of impedance-based techniques as potential screening tools for stem cell analysis. Copyright 2009 Elsevier B.V. All rights reserved.

  16. Comparison of microfilament patterns in nurse cells of different insects with polytrophic and telotrophic ovarioles.

    Science.gov (United States)

    Gutzeit, H O; Huebner, E

    1986-04-01

    The localization of F-actin (microfilaments) in the nurse cells of ovarian follicles has been studied in 12 different insect species by fluorescence microscopy after specifically staining F-actin with rhodamine-conjugated phalloidin. In the analysed species with polytrophic ovaries (Apis mellifica, Pimpla turionellae, Bradysia tritici, Ephestia kuehniella, Protophormia terraenovae) a dense F-actin network was found to be associated with the nurse cell membranes. Only in Protophormia were microfilament bundles seen to extend from the cell membrane into the nurse cell cytoplasm and in a few cases appeared to make contact with the nuclear membrane. In the analysed coleopteran species with telotrophic ovarioles (Strangalia melanura, Leptinotarsa decemlineata, Oryzaephilus surinamensis) the fluorescence was also concentrated at the nurse cell membranes only. However, in all analysed hemipteran species (Lygus pratensis, Calocoris affinis, Graphosoma lineatum, Euscelis plebejus) the microfilament pattern was very different: while the nurse cells stained only weakly, we always found a characteristic (in some species massive) microfilament network surrounding the trophic core, a central area in the germarium from where material is transported through the trophic cords into the oocytes. The observed differences in the microfilament patterns are likely to reflect different mechanisms for transporting macromolecules and organelles within the ovariole.

  17. The architecture and conservation pattern of whole-cell control circuitry.

    Science.gov (United States)

    McAdams, Harley H; Shapiro, Lucy

    2011-05-27

    The control circuitry that directs and paces Caulobacter cell cycle progression involves the entire cell operating as an integrated system. This control circuitry monitors the environment and the internal state of the cell, including the cell topology, as it orchestrates orderly activation of cell cycle subsystems and Caulobacter's asymmetric cell division. The proteins of the Caulobacter cell cycle control system and its internal organization are co-conserved across many alphaproteobacteria species, but there are great differences in the regulatory apparatus' functionality and peripheral connectivity to other cellular subsystems from species to species. This pattern is similar to that observed for the "kernels" of the regulatory networks that regulate development of metazoan body plans. The Caulobacter cell cycle control system has been exquisitely optimized as a total system for robust operation in the face of internal stochastic noise and environmental uncertainty. When sufficient details accumulate, as for Caulobacter cell cycle regulation, the system design has been found to be eminently rational and indeed consistent with good design practices for human-designed asynchronous control systems. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Stromal Cells in Dense Collagen Promote Cardiomyocyte and Microvascular Patterning in Engineered Human Heart Tissue.

    Science.gov (United States)

    Roberts, Meredith A; Tran, Dominic; Coulombe, Kareen L K; Razumova, Maria; Regnier, Michael; Murry, Charles E; Zheng, Ying

    2016-04-01

    Cardiac tissue engineering is a strategy to replace damaged contractile tissue and model cardiac diseases to discover therapies. Current cardiac and vascular engineering approaches independently create aligned contractile tissue or perfusable vasculature, but a combined vascularized cardiac tissue remains to be achieved. Here, we sought to incorporate a patterned microvasculature into engineered heart tissue, which balances the competing demands from cardiomyocytes to contract the matrix versus the vascular lumens that need structural support. Low-density collagen hydrogels (1.25 mg/mL) permit human embryonic stem cell-derived cardiomyocytes (hESC-CMs) to form a dense contractile tissue but cannot support a patterned microvasculature. Conversely, high collagen concentrations (density ≥6 mg/mL) support a patterned microvasculature, but the hESC-CMs lack cell-cell contact, limiting their electrical communication, structural maturation, and tissue-level contractile function. When cocultured with matrix remodeling stromal cells, however, hESC-CMs structurally mature and form anisotropic constructs in high-density collagen. Remodeling requires the stromal cells to be in proximity with hESC-CMs. In addition, cocultured cardiac constructs in dense collagen generate measurable active contractions (on the order of 0.1 mN/mm(2)) and can be paced up to 2 Hz. Patterned microvascular networks in these high-density cocultured cardiac constructs remain patent through 2 weeks of culture, and hESC-CMs show electrical synchronization. The ability to maintain microstructural control within engineered heart tissue enables generation of more complex features, such as cellular alignment and a vasculature. Successful incorporation of these features paves the way for the use of large scale engineered tissues for myocardial regeneration and cardiac disease modeling.

  19. Gene expression pattern of functional neuronal cells derived from human bone marrow mesenchymal stromal cells

    Directory of Open Access Journals (Sweden)

    Bron Dominique

    2008-04-01

    Full Text Available Abstract Background Neuronal tissue has limited potential to self-renew or repair after neurological diseases. Cellular therapies using stem cells are promising approaches for the treatment of neurological diseases. However, the clinical use of embryonic stem cells or foetal tissues is limited by ethical considerations and other scientific problems. Thus, bone marrow mesenchymal stomal cells (BM-MSC could represent an alternative source of stem cells for cell replacement therapies. Indeed, many studies have demonstrated that MSC can give rise to neuronal cells as well as many tissue-specific cell phenotypes. Methods BM-MSC were differentiated in neuron-like cells under specific induction (NPBM + cAMP + IBMX + NGF + Insulin. By day ten, differentiated cells presented an expression profile of real neurons. Functionality of these differentiated cells was evaluated by calcium influx through glutamate receptor AMPA3. Results Using microarray analysis, we compared gene expression profile of these different samples, before and after neurogenic differentiation. Among the 1943 genes differentially expressed, genes down-regulated are involved in osteogenesis, chondrogenesis, adipogenesis, myogenesis and extracellular matrix component (tuftelin, AGC1, FADS3, tropomyosin, fibronectin, ECM2, HAPLN1, vimentin. Interestingly, genes implicated in neurogenesis are increased. Most of them are involved in the synaptic transmission and long term potentialisation as cortactin, CASK, SYNCRIP, SYNTL4 and STX1. Other genes are involved in neurite outgrowth, early neuronal cell development, neuropeptide signaling/synthesis and neuronal receptor (FK506, ARHGAP6, CDKRAP2, PMCH, GFPT2, GRIA3, MCT6, BDNF, PENK, amphiregulin, neurofilament 3, Epha4, synaptotagmin. Using real time RT-PCR, we confirmed the expression of selected neuronal genes: NEGR1, GRIA3 (AMPA3, NEF3, PENK and Epha4. Functionality of these neuron-like cells was demonstrated by Ca2+ influx through glutamate

  20. Kv2 Channel Regulation of Action Potential Repolarization and Firing Patterns in Superior Cervical Ganglion Neurons and Hippocampal CA1 Pyramidal Neurons

    Science.gov (United States)

    Liu, Pin W.

    2014-01-01

    Kv2 family “delayed-rectifier” potassium channels are widely expressed in mammalian neurons. Kv2 channels activate relatively slowly and their contribution to action potential repolarization under physiological conditions has been unclear. We explored the function of Kv2 channels using a Kv2-selective blocker, Guangxitoxin-1E (GxTX-1E). Using acutely isolated neurons, mixed voltage-clamp and current-clamp experiments were done at 37°C to study the physiological kinetics of channel gating and action potentials. In both rat superior cervical ganglion (SCG) neurons and mouse hippocampal CA1 pyramidal neurons, 100 nm GxTX-1E produced near-saturating block of a component of current typically constituting ∼60–80% of the total delayed-rectifier current. GxTX-1E also reduced A-type potassium current (IA), but much more weakly. In SCG neurons, 100 nm GxTX-1E broadened spikes and voltage clamp experiments using action potential waveforms showed that Kv2 channels carry ∼55% of the total outward current during action potential repolarization despite activating relatively late in the spike. In CA1 neurons, 100 nm GxTX-1E broadened spikes evoked from −70 mV, but not −80 mV, likely reflecting a greater role of Kv2 when other potassium channels were partially inactivated at −70 mV. In both CA1 and SCG neurons, inhibition of Kv2 channels produced dramatic depolarization of interspike voltages during repetitive firing. In CA1 neurons and some SCG neurons, this was associated with increased initial firing frequency. In all neurons, inhibition of Kv2 channels depressed maintained firing because neurons entered depolarization block more readily. Therefore, Kv2 channels can either decrease or increase neuronal excitability depending on the time scale of excitation. PMID:24695716

  1. Expression pattern of the human ABC transporters in pluripotent embryonic stem cells and in their derivatives.

    Science.gov (United States)

    Erdei, Zsuzsa; Lőrincz, Réka; Szebényi, Kornélia; Péntek, Adrienn; Varga, Nóra; Likó, István; Várady, György; Szakács, Gergely; Orbán, Tamás I; Sarkadi, Balázs; Apáti, Agota

    2014-09-01

    ATP-binding cassette (ABC) transporters have key roles in various physiological functions as well as providing chemical defense and stress tolerance in human tissues. In this study, we have examined the expression pattern of all ABC proteins in pluripotent human embryonic stem cells (hESCs) and in their differentiated progenies. We paid special attention to the cellular expression and localization of multidrug transporter ABC proteins. Stem cell differentiation was carried out without chemical induction or cell sorting, and specialized cell types were separated mechanically. Cellular features regarding pluripotency and tissue identity, as well as ABC transporter expression were studied by flow cytomtery, immuno-microscopy, and qPCR-based low-density arrays. Pluripotent hESCs and differentiated cell types (cardiomyocytes, neuronal cells, and mesenchymal stem cells) were distinguished by morphology, immunostaining markers, and selected mRNA expression patterns. We found that the mRNA expression levels of the 48 human ABC proteins also clearly distinguished the pluripotent and the respective differentiated cell types. When multidrug and lipid transporter ABC protein expression was examined by using well characterized specific antibodies by flow cytometry and confocal microscopy, the protein expression data corresponded well to the mRNA expression results. Moreover, the cellular localization of these important human ABC transporter proteins could be established in the pluripotent and differentiated hESC derived samples. These studies provide valuable information regarding ABC protein expression in human stem cells and their differentiated offspring. The results may also help to obtain further information concerning the specialized cellular functions of selected ABC transporters. © 2014 Clinical Cytometry Society.

  2. Human T-cell leukemia virus types I and II exhibit different DNase I protection patterns

    International Nuclear Information System (INIS)

    Altman, R.; Harrich, D.; Garcia, J.A.; Gaynor, R.B.

    1988-01-01

    Human T-cell leukemia virus types I (HTLV-I) and II (HTLV-II) are human retroviruses which normally infect T-lymphoid cells. HTLV-I infection is associated with adult T-cell leukemia-lymphoma, and HTLV-II is associated with an indolent form of hairy-cell leukemia. To identify potential transcriptional regulatory elements of these two related human retroviruses, the authors performed DNase I footprinting of both the HTLV-I and HTLV-II long terminal repeats (LTRs) by using extracts prepared from uninfected T cells, HTLV-I and HTLV-II transformed T cells, and HeLa cells. Five regions of the HTLV-I LTR and three regions of the HTLV-II LTR showed protection by DNase I footprinting. All three of the 21-base-pair repeats previously shown to be important in HTLV transcriptional regulation were protected in the HTLV-I LTR, whereas only one of these repeats was protected in the HTLV-II LTR. Several regions exhibited altered protection in extracts prepared from lymphoid cells as compared with HeLa cells, but there were minimal differences in the protection patterns between HTLV-infected and uninfected lymphoid extracts. A number of HTLV-I and HTLV-II LTR fragments which contained regions showing protection in DNase I footprinting were able to function as inducible enhancer elements in transient CAT gene expression assays in the presence of the HTLV-II tat protein. The alterations in the pattern of the cellular proteins which bind to the HTLV-I and HTLV-II LTRs may in part be responsible for differences in the transcriptional regulation of these two related viruses

  3. Spatial and temporal patterns of the stability and humidity terms in the Haines index to improve the estimate of forest fire risk in the Valencia region of Spain

    OpenAIRE

    Barberà, Maria Jesús; Estrela, María Jesús; Niclòs, Raquel; Valiente, José A.

    2014-01-01

    Ponencia presentada en: IX Congreso de la Asociación Española de Climatología celebrado en Almería entre el 28 y el 30 de octubre de 2014. [EN]The assessment of risk index in the propagation and evolution of a hypothetical forest fire is commonly based on stability and moisture content at different atmospheric levels. The Haines Index combines these terms to determine the environmental potential for wildfire growth. In this study the environmental stability and humidity associated...

  4. Infiltration patterns in monoclonal plasma cell disorders: correlation of magnetic resonance imaging with matched bone marrow histology

    Energy Technology Data Exchange (ETDEWEB)

    Andrulis, Mindaugas [Institute of Pathology, University of Heidelberg, Heidelberg (Germany); Bäuerle, Tobias [Department of Diagnostic and Interventional Radiology, University of Hamburg, Hamburg (Germany); Goldschmidt, Hartmut [Department of Hematology and Oncology, University of Heidelberg, Heidelberg (Germany); Delorme, Stefan [Department of Radiology, German Cancer Research Center (DKFZ), Heidelberg (Germany); Landgren, Ola [Multiple Myeloma Section, Metabolism Branch, National Cancer Institute, Bethesda (United States); Schirmacher, Peter [Institute of Pathology, University of Heidelberg, Heidelberg (Germany); Hillengass, Jens, E-mail: jens.hillengass@med.uni-heidelberg.de [Department of Hematology and Oncology, University of Heidelberg, Heidelberg (Germany); Department of Radiology, German Cancer Research Center (DKFZ), Heidelberg (Germany)

    2014-06-15

    Objectives: To investigate how plasma cell infiltration patterns detected by MRI match the plasma cell distribution in bone marrow biopsy. Methods: We assessed 50 patients with monoclonal plasma cell disorders of all clinical stages. MRI infiltration pattern was compared with matched BM histology from the same anatomic region. Results: MRI revealed a minimal (n = 11, 22%), focal (n = 5, 10%), diffuse (n = 14, 28%) and mixed (n = 20, 40%) infiltration pattern. Diffuse MRI pattern was predominant in smoldering myeloma patients whereas the MRI patterns with “focal component” (i.e. focal and mixed) were most common in symptomatic myeloma (p < 0.01). In histology an interstitial (n = 13, 26%), nodular (n = 23, 46%) and packed marrow (n = 14, 28%) was found respectively. All three histological types of infiltration were observed in patients with diffuse and mixed MRI patterns. Minimal MRI pattern was found in all MGUS patients and was associated with an interstitial BM infiltration. In two patients with minimal MRI pattern an extensive micro-nodular BM infiltration was found in histology. Conclusions: Infiltration patterns in MRI represent different histological growth patterns of plasma cells, but the MRI resolution is not sufficient to visualize micro-nodular aggregates of plasma cells.

  5. The Effects of Vegetative Type, Edges, Fire History, Rainfall and Management in Fire-Maintained Habitat

    Science.gov (United States)

    Breininger, David R.; Foster, Tammy E.; Carter, Geoffrey M.; Duncan, Brean W.; Stolen, Eric D.; Lyon, James E.

    2018-01-01

    The combined effects of fire history, climate, and landscape features (e.g., edges) on habitat specialists need greater focus in fire ecology studies, which usually only emphasize characteristics of the most recent fire. Florida scrub-jays are an imperiled, territorial species that prefer medium (1.2-1.7 m) shrub heights, which are dynamic because of frequent fires. We measured short, medium, and tall habitat quality states annually within 10 ha grid cells (that represented potential territories) because fires and vegetative recovery cause annual variation in habitat quality. We used multistate models and model selection to test competing hypotheses about how transition probabilities vary between states as functions of environmental covariates. Covariates included vegetative type, edges (e.g., roads, forests), precipitation, openings (gaps between shrubs), mechanical cutting, and fire characteristics. Fire characteristics not only included an annual presence/absence of fire covariate, but also fire history covariates: time since the previous fire, the longest fire-free interval, and the number of repeated fires. Statistical models with support included many covariates for each transition probability, often including fire history, interactions and nonlinear relationships. Tall territories resulted from 28 years of fire suppression and habitat fragmentation that reduced the spread of fires across landscapes. Despite 35 years of habitat restoration and prescribed fires, half the territories remained tall suggesting a regime shift to a less desirable habitat condition. Edges reduced the effectiveness of fires in setting degraded scrub and flatwoods into earlier successional states making mechanical cutting an important tool to compliment frequent prescribed fires.

  6. Patterns of Adherence of Helicobacter pylori Clinical Isolates to Epithelial Cells, and its Association with Disease and with Virulence Factors.

    Science.gov (United States)

    Vázquez-Jiménez, Flor Elizabeth; Torres, Javier; Flores-Luna, Lourdes; Cerezo, Silvia Giono; Camorlinga-Ponce, Margarita

    2016-02-01

    Adherence to the gastric epithelium is one of the most important steps of Helicobacter pylori to remain and cause disease. The aim of this study was to analyze whether H. pylori isolates from patients with different gastroduodenal diseases present differences in the pattern of adherence to gastric epithelial cells (AGS), in the ability to induce IL-8, and in the presence of virulence genes. We tested 75 H. pylori strains isolated from nonatrophic gastritis, gastric cancer, and duodenal ulcer patients. The adhesion pattern and IL-8 induction were determined in AGS cells, and invasion of AGS cells was studied using a gentamicin protection assay. The IL-8 levels induced were determined by ELISA. Helicobacter pylori strains presented diffuse adherence (DA) and localized (LA) adherence patterns, similar to those described for enteropathogenic E. coli (EPEC), were observed in AGS cells. A DA pattern was observed in 57% and LA in 43% of the strains, and DA was more frequent in isolates from patients with gastric cancer (p = 0.044). Strains with a LA pattern induced higher levels of IL-8 (p = 0.042) in AGS cells. The adherence pattern was not associated with neither invasiveness nor with the presence of virulence genes. Our study shows that H. pylori strains present adherence patterns to AGS cells resembling those observed in EPEC and that these patterns may be associated with disease and with activity on AGS cells. © 2015 John Wiley & Sons Ltd.

  7. The Role of Duty Cycle in a Three Cell Central Pattern Generator

    Science.gov (United States)

    Wojcik, Jeremy; Clewley, Robert; Shilnikov, Andrey

    We describe a novel computational approach to reduce detailed models of central pattern generation to an equationless mapping that can be studied geometrically. Changes in model parameters, coupling properties, or external inputs produce qualitative changes in the mapping. These changes uncover possible biophysical mechanisms for control and modulation of rhythmic activity. Our analysis does not require knowledge of the equations that model the system, and so provides a powerful new approach to studying detailed models, applicable to a variety of biological phenomena beyond motor control. We demonstrate our technique on a motif of three reciprocally inhibitory cells that is able to produce multiple patterns of bursting rhythms. In particular, we examine the qualitative geometric structure of two-dimensional maps for phase lag between the cells.

  8. Micro patterning of cell and protein non-adhesive plasma polymerized coatings for biochip applications

    DEFF Research Database (Denmark)

    Bouaidat, Salim; Berendsen, C.; Thomsen, P.

    2004-01-01

    Micro scale patterning of bioactive surfaces is desirable for numerous biochip applications. Polyethyleneoxide-like (PEO-like) coating with non-fouling functionality has been deposited using low frequency AC plasma polymerization. The non-fouling properties of the coating were tested with human...... conventional cleanroom photolithography and lift-off. Single cell arrays showed sharp contrast in cell adhesion between the untreated glass surface and the ppCrown layer. Similarly, proteins adsorbed selectively to untreated glass but not to ppCrown. The simplicity of the liftoff technique and the sturdiness...

  9. Coupling Mechanical Deformations and Planar Cell Polarity to Create Regular Patterns in the Zebrafish Retina

    Science.gov (United States)

    Salbreux, Guillaume; Barthel, Linda K.; Raymond, Pamela A.; Lubensky, David K.

    2012-01-01

    The orderly packing and precise arrangement of epithelial cells is essential to the functioning of many tissues, and refinement of this packing during development is a central theme in animal morphogenesis. The mechanisms that determine epithelial cell shape and position, however, remain incompletely understood. Here, we investigate these mechanisms in a striking example of planar order in a vertebrate epithelium: The periodic, almost crystalline distribution of cone photoreceptors in the adult teleost fish retina. Based on observations of the emergence of photoreceptor packing near the retinal margin, we propose a mathematical model in which ordered columns of cells form as a result of coupling between planar cell polarity (PCP) and anisotropic tissue-scale mechanical stresses. This model recapitulates many observed features of cone photoreceptor organization during retinal growth and regeneration. Consistent with the model's predictions, we report a planar-polarized distribution of Crumbs2a protein in cone photoreceptors in both unperturbed and regenerated tissue. We further show that the pattern perturbations predicted by the model to occur if the imposed stresses become isotropic closely resemble defects in the cone pattern in zebrafish lrp2 mutants, in which intraocular pressure is increased, resulting in altered mechanical stress and ocular enlargement. Evidence of interactions linking PCP, cell shape, and mechanical stresses has recently emerged in a number of systems, several of which show signs of columnar cell packing akin to that described here. Our results may hence have broader relevance for the organization of cells in epithelia. Whereas earlier models have allowed only for unidirectional influences between PCP and cell mechanics, the simple, phenomenological framework that we introduce here can encompass a broad range of bidirectional feedback interactions among planar polarity, shape, and stresses; our model thus represents a conceptual framework

  10. Large-Scale Automated Analysis of Location Patterns in Randomly-Tagged 3T3 Cells

    Science.gov (United States)

    Osuna, Elvira García; Hua, Juchang; Bateman, Nicholas W.; Zhao, Ting; Berget, Peter B.; Murphy, Robert F.

    2010-01-01

    Location proteomics is concerned with the systematic analysis of the subcellular location of proteins. In order to perform high-resolution, high-throughput analysis of all protein location patterns, automated methods are needed. Here we describe the use of such methods on a large collection of images obtained by automated microscopy to perform high-throughput analysis of endogenous proteins randomly-tagged with a fluorescent protein in NIH 3T3 cells. Cluster analysis was performed to identify the statistically significant location patterns in these images. This allowed us to assign a location pattern to each tagged protein without specifying what patterns are possible. To choose the best feature set for this clustering, we have used a novel method that determines which features do not artificially discriminate between control wells on different plates and uses Stepwise Discriminant Analysis (SDA) to determine which features do discriminate as much as possible among the randomly-tagged wells. Combining this feature set with consensus clustering methods resulted in 35 clusters among the first 188 clones we obtained. This approach represents a powerful automated solution to the problem of identifying subcellular locations on a proteome-wide basis for many different cell types. PMID:17285363

  11. Pattern of AST and ALT changes in Relation to Hemolysis in sickle cell Disease

    OpenAIRE

    K. Nsiah; V.P. Dzogbefia; D. Ansong; A. Osei Akoto; H. Boateng; D. Ocloo

    2011-01-01

    Background Elevated aminotransferase levels are commonly associated with compromised hepatic integrity from various insults. In sickle cell disease, aspartate transaminase (AST) is also released via intravascular hemolysis. This study was done to determine the pattern of changes in AST and alanine transaminase (ALT), in particular the AST:ALT ratio, and to relate these to the hemolytic state, which we consider to be more important than hepatic and cardiac dysfunction in some individuals with ...

  12. Creating "living" polymer surfaces to pattern biomolecules and cells on common plastics.

    Science.gov (United States)

    Li, Chunyan; Glidle, Andrew; Yuan, Xiaofei; Hu, Zhixiong; Pulleine, Ellie; Cooper, Jon; Yang, Wantai; Yin, Huabing

    2013-05-13

    Creating patterns of biomolecules and cells has been applied widely in many fields associated with the life sciences, including diagnostics. In these applications it has become increasingly apparent that the spatiotemporal arrangement of biological molecules in vitro is important for the investigation of the cellular functions found in vivo. However, the cell patterning techniques often used are limited to creating 2D functional surfaces on glass and silicon. In addition, in general, these procedures are not easy to implement in conventional biological laboratories. Here, we show the formation of a living poly(ethylene glycol) (PEG) layer that can be patterned with visible light on plastic surfaces. This new and simple method can be expanded to pattern multiple types of biomolecule on either a previously formed PEG layer or a plastic substrate. Using common plastic wares (i.e., polyethylene films and polystyrene cell culture Petri-dishes), we demonstrate that these PEG-modified surfaces have a high resistance to protein adsorption and cell adhesion, while at the same time, being capable of undergoing further molecular grafting with bioactive motifs. With a photomask and a fluid delivery system, we illustrate a flexible way to immobilize biological functions with a high degree of 2D and 3D spatial control. We anticipate that our method can be easily implemented in a typical life science laboratory (without the need for specialized lithography equipment) offering the prospect of imparting desirable properties to plastic products, for example, the creation of functional microenvironments in biological studies or reducing biological adhesion to surfaces.

  13. Fire Behavior (FB)

    Science.gov (United States)

    Robert E. Keane

    2006-01-01

    The Fire Behavior (FB) method is used to describe the behavior of the fire and the ambient weather and fuel conditions that influence the fire behavior. Fire behavior methods are not plot based and are collected by fire event and time-date. In general, the fire behavior data are used to interpret the fire effects documented in the plot-level sampling. Unlike the other...

  14. Analysis of Laser Injection Condition and Electrical Properties in Local BSF for Laser Fired Contact c-Si Solar Cell Applications.

    Science.gov (United States)

    Park, Cheolmin; Choi, Gyuho; Balaji, Nagarajan; Ju, Minkyu; Lee, Youn-Jung; Lee, Haeseok; Yi, Junsin

    2018-07-01

    A crystalline silicon (c-Si) local-back-contact (LBC) solar cell for which a laser-condition-optimized surface-recombination velocity (SRV), a contact resistance (Rc), and local back surface fields (LBSFs) were utilized is reported. The effect of the laser condition on the rear-side electrical properties of the laser-fired LBC solar cell was studied. The Nd:YAG-laser (1064-nm wavelength) power and frequency were varied to obtain LBSF values with a lower contact resistance. A 10-kHz laser power of 44 mW resulted in an Rc of 0.125 ohms with an LBSF thickness of 2.09 μm and a higher open-circuit voltage (VOC) of 642 mV.

  15. Influences of climate, fire, and topography on contemporary age structure patterns of Douglas-fir at 205 old forest sites in western Oregon

    Science.gov (United States)

    Nathan J. Poage; Peter J. Weisberg; Peter C. Impara; John C. Tappeiner; Thomas S. Sensenig

    2009-01-01

    Knowledge of forest development is basic to understanding the ecology, dynamics, and management of forest ecosystems. We hypothesized that the age structure patterns of Douglas-fir at 205 old forest sites in western Oregon are extremely variable with long and (or) multiple establishment periods common, and that these patterns reflect variation in regional-scale climate...

  16. 3D reconstitution of the patterned neural tube from embryonic stem cells.

    Science.gov (United States)

    Meinhardt, Andrea; Eberle, Dominic; Tazaki, Akira; Ranga, Adrian; Niesche, Marco; Wilsch-Bräuninger, Michaela; Stec, Agnieszka; Schackert, Gabriele; Lutolf, Matthias; Tanaka, Elly M

    2014-12-09

    Inducing organogenesis in 3D culture is an important aspect of stem cell research. Anterior neural structures have been produced from large embryonic stem cell (ESC) aggregates, but the steps involved in patterning such complex structures have been ill defined, as embryoid bodies typically contained many cell types. Here we show that single mouse ESCs directly embedded in Matrigel or defined synthetic matrices under neural induction conditions can clonally form neuroepithelial cysts containing a single lumen in 3D. Untreated cysts were uniformly dorsal and could be ventralized to floor plate (FP). Retinoic acid posteriorized cysts to cervical levels and induced localize FP formation yielding full patterning along the dorsal/ventral (DV) axis. Correct spatial organization of motor neurons, interneurons, and dorsal interneurons along the DV axis was observed. This system serves as a valuable tool for studying morphogen action in 3D and as a source of patterned spinal cord tissue. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  17. Expression pattern of matrix metalloproteinases in human gynecological cancer cell lines

    International Nuclear Information System (INIS)

    Schröpfer, Andrea; Kammerer, Ulrike; Kapp, Michaela; Dietl, Johannes; Feix, Sonja; Anacker, Jelena

    2010-01-01

    Matrix metalloproteinases (MMPs) are involved in the degradation of protein components of the extracellular matrix and thus play an important role in tumor invasion and metastasis. Their expression is related to the progression of gynecological cancers (e.g. endometrial, cervical or ovarian carcinoma). In this study we investigated the expression pattern of the 23 MMPs, currently known in humans, in different gynecological cancer cell lines. In total, cell lines from three endometrium carcinomas (Ishikawa, HEC-1-A, AN3 CA), three cervical carcinomas (HeLa, Caski, SiHa), three chorioncarcinomas (JEG, JAR, BeWo), two ovarian cancers (BG-1, OAW-42) and one teratocarcinoma (PA-1) were examined. The expression of MMPs was analyzed by RT-PCR, Western blot and gelatin zymography. We demonstrated that the cell lines examined can constitutively express a wide variety of MMPs on mRNA and protein level. While MMP-2, -11, -14 and -24 were widely expressed, no expression was seen for MMP-12, -16, -20, -25, -26, -27 in any of the cell lines. A broad range of 16 MMPs could be found in the PA1 cells and thus this cell line could be used as a positive control for general MMP experiments. While the three cervical cancer cell lines expressed 10-14 different MMPs, the median expression in endometrial and choriocarcinoma cells was 7 different enzymes. The two investigated ovarian cancer cell lines showed a distinctive difference in the number of expressed MMPs (2 vs. 10). Ishikawa, Caski, OAW-42 and BeWo cell lines could be the best choice for all future experiments on MMP regulation and their role in endometrial, cervical, ovarian or choriocarcinoma development, whereas the teratocarcinoma cell line PA1 could be used as a positive control for general MMP experiments

  18. Fire Symfonier

    DEFF Research Database (Denmark)

    Nielsen, Svend Hvidtfelt

    2009-01-01

    sidste fire symfonier. Den er måske snarere at opfatte som et præludium til disse. At påstå, at symfonierne fra Holmboes side er planlagt til at være beslægtede, ville være at gå for vidt. Alene de 26 år, der skiller den 10. fra den 13., gør påstanden - i bedste fald - dubiøs. Når deres udformning...... udkrystallisering som i de sidste små 30 år af hans virke har afkastet disse fire variationer over en grundlæggende central holmboesk fornemmelse for form, melodi, klang og rytme. Denne oplevelse har fået mig til at udforske symfonierne, for at finde til bunds i dette holmboeske fællestræk, som jeg mener her står...

  19. The secretion pattern of perivascular fat cells is different from that of subcutaneous and visceral fat cells.

    Science.gov (United States)

    Rittig, K; Dolderer, J H; Balletshofer, B; Machann, J; Schick, F; Meile, T; Küper, M; Stock, U A; Staiger, H; Machicao, F; Schaller, H-E; Königsrainer, A; Häring, H-U; Siegel-Axel, D I

    2012-05-01

    We have previously found that the mass of perivascular adipose tissue (PVAT) correlates negatively with insulin sensitivity and post-ischaemic increase in blood flow. To understand how PVAT communicates with vascular vessels, interactions between perivascular, subcutaneous and visceral fat cells with endothelial cells (ECs) were examined with regard to inflammatory, metabolic and angiogenic proteins. To test for possible in vivo relevance of these findings, circulating levels of the predominant secretion product, hepatocyte growth factor (HGF), was measured in individuals carefully phenotyped for fat distribution patterns. Mono- and co-cultures of human primary fat cells with ECs were performed. mRNA expression and protein production were studied using Luminex, cytokine array, RealTime Ready and ELISA systems. Effects of HGF on vascular cells were determined by WST assays. In patients, HGF levels were measured by ELISA, and the mass of different fat compartments was determined by whole-body MRI. In contrast with other fat cell types, PVAT cells released higher amounts of angiogenic factors, e.g. HGF, acidic fibroblast growth factor, thrombospondin-1, serpin-E1, monocyte chemotactic protein-1 and insulin-like growth factor-binding protein -3. Cocultures showed different expression profiles from monocultures, and mature adipocytes differed from pre-adipocytes. HGF was preferentially released by PVAT cells and stimulated EC growth and smooth muscle cell cytokine release. Finally, in 95 patients, only PVAT, not visceral or subcutaneous mass, correlated independently with serum HGF levels (p = 0.03; r = 0.225). Perivascular (pre-)adipocytes differ substantially from other fat cells with regard to mRNA expression and protein production of angiogenic factors. This may contribute to fat tissue growth and atherosclerotic plaque complications. Higher levels of angiogenic factors, such as HGF, in patients with increased perivascular fat mass may have pathological relevance.

  20. Photolithographically defined deposition of attachment factors as a versatile method for patterning the growth of different cell types in culture.

    Science.gov (United States)

    Rohr, Stephan; Flückiger-Labrada, Regula; Kucera, Jan P

    2003-04-01

    Spatially defined growth of cells in culture is a useful model for studies ranging from the characterization of cellular motility to the analysis of network behaviour in structurally defined ensembles of excitable cells. Current methodological approaches for obtaining patterned growth include sophisticated modifications of surface chemistry, stamping techniques and microfluidics. The implementation of most of these techniques requires the availability of highly specialized apparatus and some of the methods are specific for certain cell types and/or substrate materials. The goal of the present study was to develop a cell-patterning technique that can be implemented by any laboratory working with cell culture and that is highly adaptable in terms of cell types and substrate materials. The method is based on a photolithographic process that permits the patterned deposition of attachment factors of choice on surfaces previously coated with agar with a spatial resolution (maximal deviation from a straight line) of +/-3 micro m. Because agar efficiently prevents cell adhesion, patterned growth obtained with this technique displays virtually no off-pattern cell attachment. The method permitted the patterning of cardiomyocytes, fibroblasts and HeLa cells on either glass substrates or polymer-coated materials with a spatial resolution of a few micrometers.

  1. Swarming and complex pattern formation in Paenibacillus vortex studied by imaging and tracking cells

    Directory of Open Access Journals (Sweden)

    Jacob Eshel

    2008-02-01

    Full Text Available Abstract Background Swarming motility allows microorganisms to move rapidly over surfaces. The Gram-positive bacterium Paenibacillus vortex exhibits advanced cooperative motility on agar plates resulting in intricate colonial patterns with geometries that are highly sensitive to the environment. The cellular mechanisms that underpin the complex multicellular organization of such a simple organism are not well understood. Results Swarming by P. vortex was studied by real-time light microscopy, by in situ scanning electron microscopy and by tracking the spread of antibiotic-resistant cells within antibiotic-sensitive colonies. When swarming, P. vortex was found to be peritrichously flagellated. Swarming by the curved cells of P. vortex occurred on an extremely wide range of media and agar concentrations (0.3 to 2.2% w/v. At high agar concentrations (> 1% w/v rotating colonies formed that could be detached from the main mass of cells by withdrawal of cells into the latter. On lower percentage agars, cells moved in an extended network composed of interconnected "snakes" with short-term collision avoidance and sensitivity to extracts from swarming cells. P. vortex formed single Petri dish-wide "supercolonies" with a colony-wide exchange of motile cells. Swarming cells were coupled by rapidly forming, reversible and non-rigid connections to form a loose raft, apparently connected via flagella. Inhibitors of swarming (p-Nitrophenylglycerol and Congo Red were identified. Mitomycin C was used to trigger filamentation without inhibiting growth or swarming; this facilitated dissection of the detail of swarming. Mitomycin C treatment resulted in malcoordinated swarming and abortive side branch formation and a strong tendency by a subpopulation of the cells to form minimal rotating aggregates of only a few cells. Conclusion P. vortex creates complex macroscopic colonies within which there is considerable reflux and movement and interaction of cells. Cell

  2. Cell-death-associated molecular patterns as determinants of cancer immunogenicity.

    Science.gov (United States)

    Ladoire, Sylvain; Hannani, Dalil; Vetizou, Marie; Locher, Clara; Aymeric, Laetitia; Apetoh, Lionel; Kepp, Oliver; Kroemer, Guido; Ghiringhelli, François; Zitvogel, Laurence

    2014-03-01

    Accumulating evidence indicates that the success of some anticancer treatments (select chemotherapies or radiotherapy or trastuzumab) could be related to the stimulation of an anticancer immune response through the induction of an immunogenic tumor cell death (ICD). Preclinical data revealed that dying tumor cells can emit a series of danger signals (so-called "cell-death-associated molecular patterns" (CDAMP)) that will dictate the recruitment and activation of specific inflammatory phagocytes. Hence, tumor cells succumbing to ICD are characterized by specific metabolic and molecular changes that will trigger a hierarchy of polarizing cytokine-producing cells, culminating in the recruitment and reactivation of antitumor interferon-γ-producing effector T cells which contribute to the success of cytotoxic treatments. In this review, we summarize the molecular and cellular bases of this ICD, underscoring the crucial role of high mobility group box 1 protein (HMGB1) and adenosine tri-phosphate, both of which are released from dying tumor cells during ICD and are implicated in the chemotherapy-elicited anticancer immune response. We discuss here how such CDAMP could serve as predictive biomarkers that could discriminate immunogenic from nonimmunogenic anti-cancer compounds, and, in case of deficiency, could be compensated by surrogate products to ameliorate the success rate of conventional anticancer treatment modalities.

  3. Dental Pulp Stem Cells Model Early Life and Imprinted DNA Methylation Patterns.

    Science.gov (United States)

    Dunaway, Keith; Goorha, Sarita; Matelski, Lauren; Urraca, Nora; Lein, Pamela J; Korf, Ian; Reiter, Lawrence T; LaSalle, Janine M

    2017-04-01

    Early embryonic stages of pluripotency are modeled for epigenomic studies primarily with human embryonic stem cells (ESC) or induced pluripotent stem cells (iPSCs). For analysis of DNA methylation however, ESCs and iPSCs do not accurately reflect the DNA methylation levels found in preimplantation embryos. Whole genome bisulfite sequencing (WGBS) approaches have revealed the presence of large partially methylated domains (PMDs) covering 30%-40% of the genome in oocytes, preimplantation embryos, and placenta. In contrast, ESCs and iPSCs show abnormally high levels of DNA methylation compared to inner cell mass (ICM) or placenta. Here we show that dental pulp stem cells (DPSCs), derived from baby teeth and cultured in serum-containing media, have PMDs and mimic the ICM and placental methylome more closely than iPSCs and ESCs. By principal component analysis, DPSC methylation patterns were more similar to two other neural stem cell types of human derivation (EPI-NCSC and LUHMES) and placenta than were iPSCs, ESCs or other human cell lines (SH-SY5Y, B lymphoblast, IMR90). To test the suitability of DPSCs in modeling epigenetic differences associated with disease, we compared methylation patterns of DPSCs derived from children with chromosome 15q11.2-q13.3 maternal duplication (Dup15q) to controls. Differential methylation region (DMR) analyses revealed the expected Dup15q hypermethylation at the imprinting control region, as well as hypomethylation over SNORD116, and novel DMRs over 147 genes, including several autism candidate genes. Together these data suggest that DPSCs are a useful model for epigenomic and functional studies of human neurodevelopmental disorders. Stem Cells 2017;35:981-988. © 2016 AlphaMed Press.

  4. Identification of tissue-specific cell death using methylation patterns of circulating DNA.

    Science.gov (United States)

    Lehmann-Werman, Roni; Neiman, Daniel; Zemmour, Hai; Moss, Joshua; Magenheim, Judith; Vaknin-Dembinsky, Adi; Rubertsson, Sten; Nellgård, Bengt; Blennow, Kaj; Zetterberg, Henrik; Spalding, Kirsty; Haller, Michael J; Wasserfall, Clive H; Schatz, Desmond A; Greenbaum, Carla J; Dorrell, Craig; Grompe, Markus; Zick, Aviad; Hubert, Ayala; Maoz, Myriam; Fendrich, Volker; Bartsch, Detlef K; Golan, Talia; Ben Sasson, Shmuel A; Zamir, Gideon; Razin, Aharon; Cedar, Howard; Shapiro, A M James; Glaser, Benjamin; Shemer, Ruth; Dor, Yuval

    2016-03-29

    Minimally invasive detection of cell death could prove an invaluable resource in many physiologic and pathologic situations. Cell-free circulating DNA (cfDNA) released from dying cells is emerging as a diagnostic tool for monitoring cancer dynamics and graft failure. However, existing methods rely on differences in DNA sequences in source tissues, so that cell death cannot be identified in tissues with a normal genome. We developed a method of detecting tissue-specific cell death in humans based on tissue-specific methylation patterns in cfDNA. We interrogated tissue-specific methylome databases to identify cell type-specific DNA methylation signatures and developed a method to detect these signatures in mixed DNA samples. We isolated cfDNA from plasma or serum of donors, treated the cfDNA with bisulfite, PCR-amplified the cfDNA, and sequenced it to quantify cfDNA carrying the methylation markers of the cell type of interest. Pancreatic β-cell DNA was identified in the circulation of patients with recently diagnosed type-1 diabetes and islet-graft recipients; oligodendrocyte DNA was identified in patients with relapsing multiple sclerosis; neuronal/glial DNA was identified in patients after traumatic brain injury or cardiac arrest; and exocrine pancreas DNA was identified in patients with pancreatic cancer or pancreatitis. This proof-of-concept study demonstrates that the tissue origins of cfDNA and thus the rate of death of specific cell types can be determined in humans. The approach can be adapted to identify cfDNA derived from any cell type in the body, offering a minimally invasive window for diagnosing and monitoring a broad spectrum of human pathologies as well as providing a better understanding of normal tissue dynamics.

  5. Cell Context Dependent p53 Genome-Wide Binding Patterns and Enrichment at Repeats

    Science.gov (United States)

    Botcheva, Krassimira; McCorkle, Sean R.

    2014-01-01

    The p53 ability to elicit stress specific and cell type specific responses is well recognized, but how that specificity is established remains to be defined. Whether upon activation p53 binds to its genomic targets in a cell type and stress type dependent manner is still an open question. Here we show that the p53 binding to the human genome is selective and cell context-dependent. We mapped the genomic binding sites for the endogenous wild type p53 protein in the human cancer cell line HCT116 and compared them to those we previously determined in the normal cell line IMR90. We report distinct p53 genome-wide binding landscapes in two different cell lines, analyzed under the same treatment and experimental conditions, using the same ChIP-seq approach. This is evidence for cell context dependent p53 genomic binding. The observed differences affect the p53 binding sites distribution with respect to major genomic and epigenomic elements (promoter regions, CpG islands and repeats). We correlated the high-confidence p53 ChIP-seq peaks positions with the annotated human repeats (UCSC Human Genome Browser) and observed both common and cell line specific trends. In HCT116, the p53 binding was specifically enriched at LINE repeats, compared to IMR90 cells. The p53 genome-wide binding patterns in HCT116 and IMR90 likely reflect the different epigenetic landscapes in these two cell lines, resulting from cancer-associated changes (accumulated in HCT116) superimposed on tissue specific differences (HCT116 has epithelial, while IMR90 has mesenchymal origin). Our data support the model for p53 binding to the human genome in a highly selective manner, mobilizing distinct sets of genes, contributing to distinct pathways. PMID:25415302

  6. Vegetation and topographical correlates of fire severity from two fires in the Klamath-Siskiyou region of Oregon and California

    Science.gov (United States)

    John D. Alexander; Nathaniel E. Seavy; C Ralph; Bill Hogoboom

    2006-01-01

    We used vegetation data collected in areas before they were burned by the 2500 ha Quartz fire in southern Oregon and the 50 600 ha Big Bar complex in northern California to evaluate the ability of vegetation and topographic characteristics to predict patterns of fire severity. Fire severity was characterized as high, moderate, or low based on crown scorch and...

  7. From pluripotency to forebrain patterning: an in vitro journey astride embryonic stem cells.

    Science.gov (United States)

    Lupo, Giuseppe; Bertacchi, Michele; Carucci, Nicoletta; Augusti-Tocco, Gabriella; Biagioni, Stefano; Cremisi, Federico

    2014-08-01

    Embryonic stem cells (ESCs) have been used extensively as in vitro models of neural development and disease, with special efforts towards their conversion into forebrain progenitors and neurons. The forebrain is the most complex brain region, giving rise to several fundamental structures, such as the cerebral cortex, the hypothalamus, and the retina. Due to the multiplicity of signaling pathways playing different roles at distinct times of embryonic development, the specification and patterning of forebrain has been difficult to study in vivo. Research performed on ESCs in vitro has provided a large body of evidence to complement work in model organisms, but these studies have often been focused more on cell type production than on cell fate regulation. In this review, we systematically reassess the current literature in the field of forebrain development in mouse and human ESCs with a focus on the molecular mechanisms of early cell fate decisions, taking into consideration the specific culture conditions, exogenous and endogenous molecular cues as described in the original studies. The resulting model of early forebrain induction and patterning provides a useful framework for further studies aimed at reconstructing forebrain development in vitro for basic research or therapy.

  8. Cell Death-Associated Molecular-Pattern Molecules: Inflammatory Signaling and Control

    Directory of Open Access Journals (Sweden)

    Beatriz Sangiuliano

    2014-01-01

    Full Text Available Apoptosis, necroptosis, and pyroptosis are different cellular death programs characterized in organs and tissues as consequence of microbes infection, cell stress, injury, and chemotherapeutics exposure. Dying and death cells release a variety of self-proteins and bioactive chemicals originated from cytosol, nucleus, endoplasmic reticulum, and mitochondria. These endogenous factors are named cell death-associated molecular-pattern (CDAMP, damage-associated molecular-pattern (DAMP molecules, and alarmins. Some of them cooperate or act as important initial or delayed inflammatory mediators upon binding to diverse membrane and cytosolic receptors coupled to signaling pathways for the activation of the inflammasome platforms and NF-κB multiprotein complexes. Current studies show that the nonprotein thiols and thiol-regulating enzymes as well as highly diffusible prooxidant reactive oxygen and nitrogen species released together in extracellular inflammatory milieu play essential role in controlling pro- and anti-inflammatory activities of CDAMP/DAMP and alarmins. Here, we provide an overview of these emerging concepts and mechanisms of triggering and maintenance of tissue inflammation under massive death of cells.

  9. Effect of Flow on Cultured Cell at Micro-Pattern of Ridge Lines

    Directory of Open Access Journals (Sweden)

    Haruka Hino

    2017-10-01

    Full Text Available A flow channel with a micro-pattern of ridge lines of a scaffold has been designed to study quantitatively the effect of flow on an oriented cell in vitro. The lines of parallel micro ridges (0.001 mm height, 0.003 mm width, and 0.003 mm interval are made by the lithography technique on the lower surface of the channel as the scaffold to make orientation of each cell. Variation is made about the angle between the longitudinal direction of the ridge line and the direction of the flow: zero, 0.79 and 1.6 rad. The suspension of C2C12 (mouse myoblast cell line was injected to the channel, and incubated for two hours on the micro ridges before the flow test for four hours. The flow rate of 3/hour is controlled by a syringe pump to make variation of the wall shear stress of < 3 Pa. The action of each cell adhered on the micro pattern was analyzed at the time lapse images. The experimental results show that both the migration and the deformation of each myoblast along the micro ridge are restricted by the wall shear stress higher than 3 Pa.

  10. Cord blood hematopoietic cells from preterm infants display altered DNA methylation patterns.

    Science.gov (United States)

    de Goede, Olivia M; Lavoie, Pascal M; Robinson, Wendy P

    2017-01-01

    Premature infants are highly vulnerable to infection. This is partly attributable to the preterm immune system, which differs from that of the term neonate in cell composition and function. Multiple studies have found differential DNA methylation (DNAm) between preterm and term infants' cord blood; however, interpretation of these studies is limited by the confounding factor of blood cell composition. This study evaluates the epigenetic impact of preterm birth in isolated hematopoietic cell populations, reducing the concern of cell composition differences. Genome-wide DNAm was measured using the Illumina 450K array in T cells, monocytes, granulocytes, and nucleated red blood cells (nRBCs) isolated from cord blood of 5 term and 5 preterm (blood cells (nRBCs) showed the most extensive changes in DNAm, with 9258 differentially methylated (DM) sites (FDR  0.10) discovered between preterm and term infants compared to the blood cell populations. The direction of DNAm change with gestational age at these prematurity-DM sites followed known patterns of hematopoietic differentiation, suggesting that term hematopoietic cell populations are more epigenetically mature than their preterm counterparts. Consistent shifts in DNAm between preterm and term cells were observed at 25 CpG sites, with many of these sites located in genes involved in growth and proliferation, hematopoietic lineage commitment, and the cytoskeleton. DNAm in preterm and term hematopoietic cells conformed to previously identified DNAm signatures of fetal liver and bone marrow, respectively. This study presents the first genome-wide mapping of epigenetic differences in hematopoietic cells across the late gestational period. DNAm differences in hematopoietic cells between term and <31 weeks were consistent with the hematopoietic origin of these cells during ontogeny, reflecting an important role of DNAm in their regulation. Due to the limited sample size and the high coincidence of prematurity and

  11. The Effects of Vegetative Type, Edges, Fire History, Rainfall and Management in Fire-Maintained Ecosystems

    Science.gov (United States)

    Breininger, David R.; Foster, Tammy E.; Carter, Geoffrey M.; Duncan, Brean W.; Stolen, Eric D.; Lyon, James E.

    2017-01-01

    The combined effects of repeated fires, climate, and landscape features (e.g., edges) need greater focus in fire ecology studies, which usually emphasize characteristics of the most recent fire and not fire history. Florida scrub-jays are an imperiled, territorial species that prefer medium (1.2-1.7 m) shrub heights. We measured short, medium, and tall habitat quality states annually within 10 ha grid cells that represented potential territories because frequent fires and vegetative recovery cause annual variation in habitat quality. We used multistate models and model selection to test competing hypotheses about how transition probabilities between states varied annually as functions of environmental covariates. Covariates included vegetative type, edges, precipitation, openings (gaps between shrubs), mechanical cutting, and fire characteristics. Fire characteristics not only included an annual presenceabsence of fire covariate, but also fire history covariates: time since the previous fire, the maximum fire-free interval, and the number of repeated fires. Statistical models with support included many covariates for each transition probability, often including fire history, interactions and nonlinear relationships. Tall territories resulted from 28 years of fire suppression and habitat fragmentation that reduced the spread of fires across landscapes. Despite 35 years of habitat restoration and prescribed fires, half the territories remained tall suggesting a regime shift to a less desirable habitat condition. Measuring territory quality states and environmental covariates each year combined with multistate modeling provided a useful empirical approach to quantify the effects of repeated fire in combinations with environmental variables on transition probabilities that drive management strategies and ecosystem change.

  12. Expression Patterns of Killer Cell Immunoglobulin-Like Receptors (KIR) of NK-Cell and T-Cell Subsets in Old World Monkeys

    Science.gov (United States)

    Hermes, Meike; Albrecht, Christina; Schrod, Annette; Brameier, Markus; Walter, Lutz

    2013-01-01

    The expression of killer cell immunoglobulin-like receptors (KIR) on lymphocytes of rhesus macaques and other Old World monkeys was unknown so far. We used our recently established monoclonal anti-rhesus macaque KIR antibodies in multicolour flow cytometry for phenotypic characterization of KIR protein expression on natural killer (NK) cells and T cell subsets of rhesus macaques, cynomolgus macaques, hamadryas baboons, and African green monkeys. Similar to human KIR, we found clonal expression patterns of KIR on NK and T cell subsets in rhesus macaques and differences between individuals using pan-KIR3D antibody 1C7 and antibodies specific for single KIR. Similar results were obtained with lymphocytes from the other studied species. Notably, African green monkeys show only a low frequency of KIR3D expressed on CD8+ αβT cells. Contrasting human NK cells are KIR-positive CD56bright NK cells and frequencies of KIR-expressing NK cells that are independent of the presence of their cognate MHC class I ligands in rhesus macaques. Interestingly, the frequency of KIR-expressing cells and the expression strength of KIR3D are correlated in γδ T cells of rhesus macaques and CD8+ αβT cells of baboons. PMID:23717676

  13. Firing probability and mean firing rates of human muscle vasoconstrictor neurones are elevated during chronic asphyxia

    DEFF Research Database (Denmark)

    Ashley, Cynthia; Burton, Danielle; Sverrisdottir, Yrsa B

    2010-01-01

    Elevated muscle sympathetic nerve activity (MSNA) features in many cardiovascular diseases, but how this sympathoexcitation is brought about differs across pathologies. Unitary recordings from post-ganglionic muscle vasoconstrictor neurones in human subjects have shown that the augmented MSNA...... in the obstructive sleep apnoea syndrome (OSAS) is associated with an increase in firing probability and mean firing rate, and an increase in multiple within-burst firing. Here we characterize the firing properties of muscle vasoconstrictor neurones in patients with chronic obstructive pulmonary disease (COPD), who...... are chronically asphyxic. We tested the hypothesis that this elevated chemical drive would shift the firing pattern from that seen in healthy subjects to that seen in OSAS. The mean firing probability (52%) and mean firing rate (0.92 Hz) of 17 muscle vasoconstrictor neurones recorded in COPD were comparable...

  14. Fire Models and Design Fires

    DEFF Research Database (Denmark)

    Poulsen, Annemarie

    The aim of this project is to perform an experimental study on the influence of the thermal feedback on the burning behavior of well ventilated pre-flashover fires. For the purpose an experimental method has been developed. Here the same identical objects are tested under free burn conditions...... documented a simple relation that can be used for estimating the impact of thermal feedback for pre-flashover design fires. A rapid increase of the heat release rate commenced after the incipient phase. This is seen as thermal runaway caused by the energy gain in the smoke layer exceeding the energy that can...... and in two different rooms, which only are varied by linings of significantly different thermal inertia. As all linings were non-combustible the heat release rate could be found without the influence of thermal feedback and for two different levels of thermal feedback. The ISO 9705 Room Corner Test facility...

  15. FIRE ALARM SYSTEM OUTDATED.

    Science.gov (United States)

    CHANDLER, L.T.

    AN EFFICIENT FIRE ALARM SYSTEM SHOULD--(1) PROVIDE WARNING OF FIRES THAT START IN HIDDEN OR UNOCCUPIED LOCATIONS, (2) INDICATE WHERE THE FIRE IS, (3) GIVE ADVANCE WARNING TO FACULTY AND ADMINISTRATION SO THAT PANIC AND CONFUSION CAN BE AVOIDED AND ORDERLY EVACUATION OCCUR, (4) AUTOMATICALLY NOTIFY CITY FIRE HEADQUARTERS OF THE FIRE, (5) OPERATE BY…

  16. Using a stochastic model and cross-scale analysis to evaluate controls on historical low-severity fire regimes

    Science.gov (United States)

    Maureen C. Kennedy; Donald. McKenzie

    2010-01-01

    Fire-scarred trees provide a deep temporal record of historical fire activity, but identifying the mechanisms therein that controlled landscape fire patterns is not straightforward. We use a spatially correlated metric for fire co-occurrence between pairs of trees (the Sørensen distance variogram), with output from a neutral model for fire history, to infer the...

  17. Sub-sets of cancer stem cells differ intrinsically in their patterns of oxygen metabolism.

    Directory of Open Access Journals (Sweden)

    Luke Gammon

    Full Text Available The glycolytic response of hypoxic cells is primarily mediated by the hypoxia inducible factor alpha (HIF-1α but even in the presence of abundant oxygen tumours typically show high rates of glycolysis. Higher levels of HIF-1α in tumours are associated with a poorer prognosis and up-regulation of markers of epithelial mesenchymal transition (EMT due to HIF-1α actions. We have recently shown that EMT occurs within the CD44(high cancer stem cell (CSC fraction and that epithelial and EMT CSCs are distinguished by high and low ESA expression, respectively. We here show that hypoxia induces a marked shift of the CSC fraction towards EMT leading to altered cell morphology, an increased proportion of CD44(high/ESA(low cells, patterns of gene expression typical of EMT, and enhanced sphere-forming ability. The size of EMT fractions returned to control levels in normoxia indicating a reversible process. Surprisingly, however, even under normoxic conditions a fraction of EMT CSCs was present and maintained high levels of HIF-1α, apparently due to actions of cytokines such as TNFα. Functionally, this EMT CSC fraction showed decreased mitochondrial mass and membrane potential, consumed far less oxygen per cell, and produced markedly reduced levels of reactive oxygen species (ROS. These differences in the patterns of oxygen metabolism of sub-fractions of tumour cells provide an explanation for the general therapeutic resistance of CSCs and for the even greater resistance of EMT CSCs. They also identify potential mechanisms for manipulation of CSCs.

  18. Pattern-triggered immunity suppresses programmed cell death triggered by fumonisin b1.

    Directory of Open Access Journals (Sweden)

    Daisuke Igarashi

    Full Text Available Programmed cell death (PCD is a crucial process for plant innate immunity and development. In plant innate immunity, PCD is believed to prevent the spread of pathogens from the infection site. Although proper control of PCD is important for plant fitness, we have limited understanding of the molecular mechanisms regulating plant PCD. Plant innate immunity triggered by recognition of effectors (effector-triggered immunity, ETI is often associated with PCD. However pattern-triggered immunity (PTI, which is triggered by recognition of elicitors called microbe-associated molecular patterns (MAMPs, is not. Therefore we hypothesized that PTI might suppress PCD. Here we report that PCD triggered by the mycotoxin fumonisin B1 (FB1 can be suppressed by PTI in Arabidopsis. FB1-triggered cell death was suppressed by treatment with the MAMPs flg22 (a part of bacterial flagellin or elf18 (a part of the bacterial elongation factor EF-Tu but not chitin (a component of fungal cell walls. Although plant hormone signaling is associated with PCD and PTI, both FB1-triggered cell death and suppression of cell death by flg22 treatment were still observed in mutants deficient in jasmonic acid (JA, ethylene (ET and salicylic acid (SA signaling. The MAP kinases MPK3 and MPK6 are transiently activated and inactivated within one hour during PTI. We found that FB1 activated MPK3 and MPK6 about 36-48 hours after treatment. Interestingly, this late activation was attenuated by flg22 treatment. These results suggest that PTI suppression of FB1-triggered cell death may involve suppression of MPK3/MPK6 signaling but does not require JA/ET/SA signaling.

  19. Expression patterns and miRNA regulation of DNA methyltransferases in chicken primordial germ cells.

    Directory of Open Access Journals (Sweden)

    Deivendran Rengaraj

    Full Text Available DNA methylation is widespread in most species, from bacteria to mammals, and is crucial for genomic imprinting, gene expression, and embryogenesis. DNA methylation occurs via two major classes of enzymatic reactions: maintenance-type methylation catalyzed by DNA (cytosine-5--methyltransferase (DNMT 1, and de novo methylation catalyzed by DNMT 3 alpha (DNMT3A and -beta (DNMT3B. The expression pattern and regulation of DNMT genes in primordial germ cells (PGCs and germ line cells has not been sufficiently established in birds. Therefore, we employed bioinformatics, RT-PCR, real-time PCR, and in situ hybridization analyses to examine the structural conservation and conserved expression patterns of chicken DNMT family genes. We further examined the regulation of a candidate de novo DNA methyltransferase gene, cDNMT3B by cotransfection of cDNMT3B 3'UTR- and cDNMT3B 3'UTR-specific miRNAs through a dual fluorescence reporter assay. All cDNMT family members were differentially detected during early embryonic development. Of interest, cDNMT3B expression was highly detected in early embryos and in PGCs. During germ line development and sexual maturation, cDNMT3B expression was reestablished in a female germ cell-specific manner. In the dual fluorescence reporter assay, cDNMT3B expression was significantly downregulated by four miRNAs: gga-miR-15c (25.82%, gga-miR-29b (30.01%, gga-miR-383 (30.0%, and gga-miR-222 (31.28%. Our data highlight the structural conservation and conserved expression patterns of chicken DNMTs. The miRNAs investigated in this study may induce downregulation of gene expression in chicken PGCs and germ cells.

  20. Unique cell-type specific patterns of DNA methylation in the root meristem

    Science.gov (United States)

    Kawakatsu, Taiji; Stuart, Tim; Valdes, Manuel; Breakfield, Natalie; Schmitz, Robert J.; Nery, Joseph R.; Urich, Mark A.; Han, Xinwei; Lister, Ryan; Benfey, Philip N.; Ecker, Joseph R.

    2016-01-01

    DNA methylation is an epigenetic modification that differs between plant organs and tissues, but the extent of variation between cell types is not known. Here, we report single-base resolution whole genome DNA methylomes, mRNA transcriptomes, and small RNA transcriptomes for six cell populations covering the major cell types of the Arabidopsis root meristem. We identify widespread cell type specific patterns of DNA methylation, especially in the CHH sequence context. The genome of the columella root cap is the most highly methylated Arabidopsis cell characterized to date. It is hypermethylated within transposable elements, accompanied by increased abundance of transcripts encoding RNA-directed DNA methylation (RdDM) pathway components and 24 nt small RNAs. Absence of the nucleosome remodeler DECREASED DNA METHYLATION 1, required for maintenance of DNA methylation, and low abundance of histone transcripts involved in heterochromatin formation suggests a loss of heterochromatin may occur in the columella, thus allowing access of RdDM factors to the whole genome, and producing excess 24 nt small RNAs in this tissue. Together, these maps provide new insights into the epigenomic diversity that exists between distinct plant somatic cell types. PMID:27243651

  1. Analysis of spatial relationships in three dimensions: tools for the study of nerve cell patterning

    Directory of Open Access Journals (Sweden)

    Raven Mary A

    2008-07-01

    Full Text Available Abstract Background Multiple technologies have been brought to bear on understanding the three-dimensional morphology of individual neurons and glia within the brain, but little progress has been made on understanding the rules controlling cellular patterning. We describe new matlab-based software tools, now available to the scientific community, permitting the calculation of spatial statistics associated with 3D point patterns. The analyses are largely derived from the Delaunay tessellation of the field, including the nearest neighbor and Voronoi domain analyses, and from the spatial autocorrelogram. Results Our tools enable the analysis of the spatial relationship between neurons within the central nervous system in 3D, and permit the modeling of these fields based on lattice-like simulations, and on simulations of minimal-distance spacing rules. Here we demonstrate the utility of our analysis methods to discriminate between two different simulated neuronal populations. Conclusion Together, these tools can be used to reveal the presence of nerve cell patterning and to model its foundation, in turn informing on the potential developmental mechanisms that govern its establishment. Furthermore, in conjunction with analyses of dendritic morphology, they can be used to determine the degree of dendritic coverage within a volume of tissue exhibited by mature nerve cells.

  2. Dynein and EFF-1 control dendrite morphology by regulating the localization pattern of SAX-7 in epidermal cells.

    Science.gov (United States)

    Zhu, Ting; Liang, Xing; Wang, Xiang-Ming; Shen, Kang

    2017-12-01

    Our previous work showed that the cell adhesion molecule SAX-7 forms an elaborate pattern in Caenorhabditis elegans epidermal cells, which instructs PVD dendrite branching. However, the molecular mechanism forming the SAX-7 pattern in the epidermis is not fully understood. Here, we report that the dynein light intermediate chain DLI-1 and the fusogen EFF-1 are required in epidermal cells to pattern SAX-7. While previous reports suggest that these two molecules act cell-autonomously in the PVD, our results show that the disorganized PVD dendritic arbors in these mutants are due to the abnormal SAX-7 localization patterns in epidermal cells. Three lines of evidence support this notion. First, the epidermal SAX-7 pattern was severely affected in dli-1 and eff-1 mutants. Second, the abnormal SAX-7 pattern was predictive of the ectopic PVD dendrites. Third, expression of DLI-1 or EFF-1 in the epidermis rescued both the SAX-7 pattern and the disorganized PVD dendrite phenotypes, whereas expression of these molecules in the PVD did not. We also show that DLI-1 functions cell-autonomously in the PVD to promote distal branch formation. These results demonstrate the unexpected roles of DLI-1 and EFF-1 in the epidermis in the control of PVD dendrite morphogenesis. © 2017. Published by The Company of Biologists Ltd.

  3. Analysis of reticulin fiber pattern in lymph nodes with metastasis from oral squamous cell carcinoma

    Directory of Open Access Journals (Sweden)

    Shanmukha Raviteja Yinti

    2015-01-01

    Full Text Available Introduction: The aim of the study was to determine the susceptibility of lymph nodes to metastasis in oral squamous cell carcinoma (OSCC by analyzing the alterations in reticulin fiber pattern. Materials and Methods: This retrospective study on 30 cases of OSCC had 15 cases that presented with lymph node metastasis (test group and 15 cases without metastatic episodes (control group. Four micron thick sections of the tumor proper and the resected lymph nodes of the cases were stained with hematoxylin and eosin, and Gordon and Sweet′s stain for reticulin. Statistical analysis of the variations in the staining patterns of reticulin at the invasive tumor front (ITF, involved and uninvolved lymph nodes were done with Statistical Package for Social Sciences (SPSS 15 version using chi-square test. Results: The assessment of reticulin fiber patterns at the ITF, cortical and medullary areas of lymph nodes in test cases showed thin, long individual fibers, as compared to thick, shorter interlacing fibers that were seen in control cases. The peritumoral and uninvolved areas in metastatic lymph nodes of almost all test cases showed very scant fibers. Conclusion: Reticulin pattern alteration by aggressive tumors may be appreciated as a part of the wide spectrum of "proneoplastic" stromal alterations. The histopathologist can discern these changes and thereby aid the clinician in predicting tumor behavior, the clinical course of the disease, and weighing the prognostic implications.

  4. A stochastic Forest Fire Model for future land cover scenarios assessment

    Directory of Open Access Journals (Sweden)

    M. D'Andrea

    2010-10-01

    Full Text Available Land cover is affected by many factors including economic development, climate and natural disturbances such as wildfires. The ability to evaluate how fire regimes may alter future vegetation, and how future vegetation may alter fire regimes, would assist forest managers in planning management actions to be carried out in the face of anticipated socio-economic and climatic change. In this paper, we present a method for calibrating a cellular automata wildfire regime simulation model with actual data on land cover and wildfire size-frequency. The method is based on the observation that many forest fire regimes, in different forest types and regions, exhibit power law frequency-area distributions. The standard Drossel-Schwabl cellular automata Forest Fire Model (DS-FFM produces simulations which reproduce this observed pattern. However, the standard model is simplistic in that it considers land cover to be binary – each cell either contains a tree or it is empty – and the model overestimates the frequency of large fires relative to actual landscapes. Our new model, the Modified Forest Fire Model (MFFM, addresses this limitation by incorporating information on actual land use and differentiating among various types of flammable vegetation. The MFFM simulation model was tested on forest types with Mediterranean and sub-tropical fire regimes. The results showed that the MFFM was able to reproduce structural fire regime parameters for these two regions. Further, the model was used to forecast future land cover. Future research will extend this model to refine the forecasts of future land cover and fire regime scenarios under climate, land use and socio-economic change.

  5. Frequency patterns of T-cell exposed motifs in immunoglobulin heavy chain peptides presented by MHCs

    Directory of Open Access Journals (Sweden)

    Robert D. Bremel

    2014-10-01

    Full Text Available Immunoglobulins are highly diverse protein sequences that are processed and presented to T-cells by B-cells and other antigen presenting cells. We examined a large dataset of immunoglobulin heavy chain variable regions (IGHV to assess the diversity of T-cell exposed motifs (TCEM. TCEM comprise those amino acids in a MHC-bound peptide which face outwards, surrounded by the MHC histotope, and which engage the T-cell receptor. Within IGHV there is a distinct pattern of predicted MHC class II binding and a very high frequency of re-use of the TCEMs. The re-use frequency indicates that only a limited number of different cognate T-cells are required to engage many different clonal B-cells. The amino acids in each outward-facing TCEM are intercalated with the amino acids of inward-facing MHC groove-exposed motifs (GEM. Different GEM may have differing, allele-specific, MHC binding affinities. The intercalation of TCEM and GEM in a peptide allows for a vast combinatorial repertoire of epitopes, each eliciting a different response. Outcome of T-cell receptor binding is determined by overall signal strength, which is a function of the number of responding T-cells and the duration of engagement. Hence, the frequency of T-cell exposed motif re-use appears to be an important determinant of whether a T-cell response is stimulatory or suppressive. The frequency distribution of TCEMs implies that somatic hypermutation is followed by clonal expansion that develop along repeated pathways. The observations of TCEM and GEM derived from immunoglobulins suggest a relatively simple, yet powerful, mechanism to correlate T-cell polyspecificity, through re-use of TCEMs, with a very high degree of specificity achieved by combination with a diversity of GEMs. The frequency profile of TCEMs also points to an economical mechanism for maintaining T-cell memory, recall, and self-discrimination based on an endogenously generated profile of motifs.

  6. The wildland fuel cell concept: an approach to characterize fine-scale variation in fuels and fire in frequently burned longleaf pine forests

    Science.gov (United States)

    J. Kevin Hiers; Joseph J. O’Brien; R. J. Mitchell; John M. Grego; E. Louise Loudermilk

    2009-01-01

    In ecosystems with frequent surface fire regimes, fire and fuel heterogeneity has been largely overlookedowing to the lack of unburned patches and the difficulty in measuring fire behavior at fine scales (0.1–10 m). The diversevegetation in these ecosystems varies at these fine scales. This diversity could be...

  7. Controls on variations in MODIS fire radiative power in Alaskan boreal forests: implications for fire severity conditions

    Science.gov (United States)

    Barrett, Kirsten; Kasischke, Eric S.

    2013-01-01

    Fire activity in the Alaskan boreal forest, though episodic at annual and intra-annual time scales, has experienced an increase over the last several decades. Increases in burned area and fire severity are not only releasing more carbon to the atmosphere, but likely shifting vegetation composition in the region towards greater deciduous dominance and a reduction in coniferous stands. While some recent studies have addressed qualitative differences between large and small fire years in the Alaskan boreal forest, the ecological effects of a greater proportion of burning occurring during large fire years and during late season fires have not yet been examined. Some characteristics of wildfires that can be detected remotely are related to fire severity and can provide new information on spatial and temporal patterns of burning. This analysis focused on boreal wildfire intensity (fire radiative power, or FRP) contained in the Moderate Resolution Imaging Spectroradiometer (MODIS) daily active fire product from 2003 to 2010. We found that differences in FRP resulted from seasonality and intra-annual variability in fire activity levels, vegetation composition, latitudinal variation, and fire spread behavior. Our studies determined two general categories of active fire detections: new detections associated with the spread of the fire front and residual pixels in areas that had already experienced front burning. Residual pixels had a lower average FRP than front pixels, but represented a high percentage of all pixels during periods of high fire activity (large fire years, late season burning, and seasonal periods of high fire activity). As a result, the FRP from periods of high fire activity was less intense than those from periods of low fire activity. Differences related to latitude were greater than expected, with higher latitudes burning later in the season and at a higher intensity than lower latitudes. Differences in vegetation type indicate that coniferous vegetation

  8. Fire Ant Bites

    Science.gov (United States)

    ... Favorite Name: Category: Share: Yes No, Keep Private Fire Ant Bites Share | Fire ants are aggressive, venomous insects that have pinching ... across the United States, even into Puerto Rico. Fire ant stings usually occur on the feet or ...

  9. Crown Fire Potential

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — Crown fire potential was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The...

  10. Pattern of AST and ALT changes in Relation to Hemolysis in sickle cell Disease

    Directory of Open Access Journals (Sweden)

    K. Nsiah

    2011-01-01

    Full Text Available Background Elevated aminotransferase levels are commonly associated with compromised hepatic integrity from various insults. In sickle cell disease, aspartate transaminase (AST is also released via intravascular hemolysis. This study was done to determine the pattern of changes in AST and alanine transaminase (ALT, in particular the AST:ALT ratio, and to relate these to the hemolytic state, which we consider to be more important than hepatic and cardiac dysfunction in some individuals with sickle cell disease. Methods Serum aminotransferase levels were measured in 330 subjects with sickle cell disease, as well as hemoglobin, reticulocytes, and lactate dehydrogenase. The AST:ALT ratio was designated as a hemolytic marker, and simple and multivariate regression analyses were carried out between this ratio and other hemolytic markers. Results Mean AST and ALT levels were 48.24 % 27.78 and 26.48 % 22.73 U/L, respectively. However, for 49 subjects without sickle cell disease, mean AST and ALT levels were the same, ie, 23.0 U/L. In the subjects with sickle cell disease, the increases in AST levels were far higher than for ALT, supporting its release via intravascular hemolysis. In 95.8% of the subjects with sickle cell disease, the AST:ALT ratio was > 1, but our results did not suggest overt malfunctioning of the liver and heart in the majority of subjects. Conclusion Regression analyses support the use of the AST:ALT ratio as a hemolytic marker, because it has an inverse association with the hemoglobin level. Whether in steady state or in crisis, provided hepatic and cardiac integrity has not been compromised, subjects with sickle cell disease would have higher AST levels due to the hemolytic nature of the condition. This is the first report highlighting the AST:ALT ratio in sickle cell disease.

  11. Microfluidic-based patterning of embryonic stem cells for in vitro development studies.

    Science.gov (United States)

    Suri, Shalu; Singh, Ankur; Nguyen, Anh H; Bratt-Leal, Andres M; McDevitt, Todd C; Lu, Hang

    2013-12-07

    In vitro recapitulation of mammalian embryogenesis and examination of the emerging behaviours of embryonic structures require both the means to engineer complexity and accurately assess phenotypes of multicellular aggregates. Current approaches to study multicellular populations in 3D configurations are limited by the inability to create complex (i.e. spatially heterogeneous) environments in a reproducible manner with high fidelity thus impeding the ability to engineer microenvironments and combinations of cells with similar complexity to that found during morphogenic processes such as development, remodelling and wound healing. Here, we develop a multicellular embryoid body (EB) fusion technique as a higher-throughput in vitro tool, compared to a manual assembly, to generate developmentally relevant embryonic patterns. We describe the physical principles of the EB fusion microfluidic device design; we demonstrate that >60 conjoined EBs can be generated overnight and emulate a development process analogous to mouse gastrulation during early embryogenesis. Using temporal delivery of bone morphogenic protein 4 (BMP4) to embryoid bodies, we recapitulate embryonic day 6.5 (E6.5) during mouse embryo development with induced mesoderm differentiation in murine embryonic stem cells leading to expression of Brachyury-T-green fluorescent protein (T-GFP), an indicator of primitive streak development and mesoderm differentiation during gastrulation. The proposed microfluidic approach could be used to manipulate hundreds or more of individual embryonic cell aggregates in a rapid fashion, thereby allowing controlled differentiation patterns in fused multicellular assemblies to generate complex yet spatially controlled microenvironments.

  12. Pattern of Failure in Surgically Treated Patients with Cervical Esophageal Squamous Cell Carcinoma.

    Science.gov (United States)

    Cao, Cai-Neng; Liu, Shao-Yan; Luo, Jing-Wei; Gao, Li; Xu, Guo-Zhen; Xu, Zhen-Gang; Tang, Ping-Zhang

    2014-08-01

    The aim of this study was to analyze the pattern of failure in patients who have undergone surgical resection for cervical esophageal squamous cell carcinoma. Case series with chart review. University hospital. Sixty-two patients who had undergone surgical resection of cervical esophageal squamous cell carcinoma from January 2001 through April 2012. Sites of failure were documented. Twenty-nine patients had developed treatment failure. Of the 29 patients, 14, 13, and 14 had developed local failure, regional failure, and distant metastasis, respectively. Of the 13 regional failures, the images of 2 patients were lost. The other 11 regional failures included left lateral nodal disease at level II (n = 2), level III (n = 4), and level IV (n = 7); right lateral nodal disease at level II (n = 2), level III (n = 3), and level IV (n = 3); and level VI (n = 4). The overall 2-year local failure-free survival rate and regional failure-free survival rates were 79.6% and 58.6% (P = .04) for patients with stage II disease and 79.6% and 59.6% (P = .054) for patients with stage III disease, respectively. The pattern of failure of cervical esophageal squamous cell carcinoma is characterized by early locoregional failure, especially in patients with stage III disease. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2014.

  13. Expression patterns and role of SDF-1/CXCR4 axis in boar spermatogonial stem cells.

    Science.gov (United States)

    Park, Hyun Jung; Lee, Won-Yong; Kim, Jin Hoi; Park, Chankyu; Song, Hyuk

    2018-03-15

    The signaling of chemokine stromal cell-derived factor (SDF)-1 and its receptor C-X-C motif chemokine receptor 4 (CXCR4) is involved in the cellular proliferation, survival, and migration of various cell types. Although SDF-1/CXCR4 has been implicated in the maintenance of the spermatogonial population during mouse testis development, their expression patterns and functions in boar testis remain unclear. In the present study, the expression pattern of SDF-1 and CXCR4 was determined during pre-pubertal and post-pubertal stage boar testes and in vitro cultured porcine spermatogonial stem cells (pSSCs). The role of these proteins in colony formation in cultured pSSCs was also investigated. Interestingly, SDF-1 expression was observed in PGP 9.5-positve spermatogonia in all developing stages of boar testis; however, CXCR4 expression was only detected in spermatogonia from 5-day-old boar testis. In addition, SDF-1 and CXCR4 expression was observed in cultured pSSCs from 5-day-old boar testes, and inhibition of the CXCR4 receptor signaling pathway by AMD3100 significantly decreased the colony formation of pSSCs. These results suggest that SDF-1 and CXCR4 are useful markers for detecting stage-specific spermatogonia in boar testis. Our results reveal the role of the SDF-1/CXCR4 axis in pSSC in vitro culture. Copyright © 2018. Published by Elsevier Inc.

  14. Pattern of epithelial cell abnormality in Pap smear: A clinicopathological and demographic correlation

    Directory of Open Access Journals (Sweden)

    Urmila Banik

    2011-01-01

    Full Text Available Background: In the low resource settings of a developing country, a conventional Papanicolaou (Pap test is the mainstay screening system for cervical cancer. In order to counsel women and to organize a public health system for cervical cancer screening by Pap smear examination, it is imperative to know the pattern of premalignant and malignant lesions. This study was undertaken to find out the prevalence of an abnormal Pap smear, in a tertiary hospital of a developing country, and to carry out a clinicopathological and demographical analysis for establishing the pattern of epithelial cell abnormality in a Pap smear. Materials and Methods: A cross-sectional descriptive study was carried out in a total of 1699 patients who underwent Pap smear examination. The prevalence of epithelial cell abnormality in the Pap smear was calculated in proportions / percentages. Specimen adequacy and reporting was assessed according to the revised Bethesda system. Results: Among the total of 1699 patients who had their Pap smear done, 139 (8.18% revealed epithelial cell abnormality. Altogether 26 smears revealed high-grade lesions and malignancy, most of which were found to be in women belonging to the 30 - 39 and ≥ 45 age group. A total of 75 (53.96% women were in the 20 - 44 age group and 64 (46.04% were in the ≥ 45 age group. A bimodal age distribution was detected in the epithelial cell abnormality, with the bulk being diagnosed in patients aged 45 or above. Overall one-third of the patients with an abnormal Pap smear result showed healthy cervix in per vaginal examination. Conclusions: A raised prevalence of epithelial cell abnormality reflects the lack of awareness about cervical cancer screening. Women aged 45 or above harbor the bulk of premalignant and malignant lesions in the Pap smear, signifying that these women are among the under users of cytological screening.

  15. Common histological patterns in glomerular epithelial cells in secondary focal segmental glomerulosclerosis.

    Science.gov (United States)

    Kuppe, Christoph; Gröne, Hermann-Josef; Ostendorf, Tammo; van Kuppevelt, Toin H; Boor, Peter; Floege, Jürgen; Smeets, Bart; Moeller, Marcus J

    2015-11-01

    Parietal epithelial cells (PECs) are involved in the development of sclerotic lesions in primary focal and segmental glomerulosclerosis (FSGS). Here, the role of PECs was explored in the more common secondary FSGS lesions in 68 patient biopsies, diagnosed with 11 different frequently or rarely encountered glomerular pathologies and additional secondary FSGS lesions. For each biopsy, one section was quadruple stained for PECs (ANXA3), podocytes (synaptopodin), PEC matrix (LKIV69), and Hoechst (nuclei), and a second was quadruple stained for activated PECs (CD44 and cytokeratin-19), PEC matrix, and nuclei. In all lesions, cellular adhesions (synechiae) between Bowman's capsule and the tuft were formed by cells expressing podocyte and/or PEC markers. Cells expressing PEC markers were detected in all FSGS lesions independent of the underlying glomerular disease and often stained positive for markers of activation. Small FSGS lesions, which were hardly identified on PAS sections previously, were detectable by immunofluorescent staining using PEC markers, potentially improving the diagnostic sensitivity to identify these lesions. Thus, similar patterns of cells expressing podocyte and/or PEC markers were found in the formation of secondary FSGS lesions independent of the underlying glomerular disease. Hence, our findings support the hypothesis that FSGS lesions follow a final cellular pathway to nephron loss that includes involvement of cells expressing PEC markers.

  16. Neural Conversion and Patterning of Human Pluripotent Stem Cells: A Developmental Perspective.

    Science.gov (United States)

    Zirra, Alexandra; Wiethoff, Sarah; Patani, Rickie

    2016-01-01

    Since the reprogramming of adult human terminally differentiated somatic cells into induced pluripotent stem cells (hiPSCs) became a reality in 2007, only eight years have passed. Yet over this relatively short period, myriad experiments have revolutionized previous stem cell dogmata. The tremendous promise of hiPSC technology for regenerative medicine has fuelled rising expectations from both the public and scientific communities alike. In order to effectively harness hiPSCs to uncover fundamental mechanisms of disease, it is imperative to first understand the developmental neurobiology underpinning their lineage restriction choices in order to predictably manipulate cell fate to desired derivatives. Significant progress in developmental biology provides an invaluable resource for rationalising directed differentiation of hiPSCs to cellular derivatives of the nervous system. In this paper we begin by reviewing core developmental concepts underlying neural induction in order to provide context for how such insights have guided reductionist in vitro models of neural conversion from hiPSCs. We then discuss early factors relevant in neural patterning, again drawing upon crucial knowledge gained from developmental neurobiological studies. We conclude by discussing open questions relating to these concepts and how their resolution might serve to strengthen the promise of pluripotent stem cells in regenerative medicine.

  17. Neural Conversion and Patterning of Human Pluripotent Stem Cells: A Developmental Perspective

    Directory of Open Access Journals (Sweden)

    Alexandra Zirra

    2016-01-01

    Full Text Available Since the reprogramming of adult human terminally differentiated somatic cells into induced pluripotent stem cells (hiPSCs became a reality in 2007, only eight years have passed. Yet over this relatively short period, myriad experiments have revolutionized previous stem cell dogmata. The tremendous promise of hiPSC technology for regenerative medicine has fuelled rising expectations from both the public and scientific communities alike. In order to effectively harness hiPSCs to uncover fundamental mechanisms of disease, it is imperative to first understand the developmental neurobiology underpinning their lineage restriction choices in order to predictably manipulate cell fate to desired derivatives. Significant progress in developmental biology provides an invaluable resource for rationalising directed differentiation of hiPSCs to cellular derivatives of the nervous system. In this paper we begin by reviewing core developmental concepts underlying neural induction in order to provide context for how such insights have guided reductionist in vitro models of neural conversion from hiPSCs. We then discuss early factors relevant in neural patterning, again drawing upon crucial knowledge gained from developmental neurobiological studies. We conclude by discussing open questions relating to these concepts and how their resolution might serve to strengthen the promise of pluripotent stem cells in regenerative medicine.

  18. Wnt/Yes-Associated Protein Interactions During Neural Tissue Patterning of Human Induced Pluripotent Stem Cells.

    Science.gov (United States)

    Bejoy, Julie; Song, Liqing; Zhou, Yi; Li, Yan

    2018-04-01

    Human induced pluripotent stem cells (hiPSCs) have special ability to self-assemble into neural spheroids or mini-brain-like structures. During the self-assembly process, Wnt signaling plays an important role in regional patterning and establishing positional identity of hiPSC-derived neural progenitors. Recently, the role of Wnt signaling in regulating Yes-associated protein (YAP) expression (nuclear or cytoplasmic), the pivotal regulator during organ growth and tissue generation, has attracted increasing interests. However, the interactions between Wnt and YAP expression for neural lineage commitment of hiPSCs remain poorly explored. The objective of this study is to investigate the effects of Wnt signaling and YAP expression on the cellular population in three-dimensional (3D) neural spheroids derived from hiPSCs. In this study, Wnt signaling was activated using CHIR99021 for 3D neural spheroids derived from human iPSK3 cells through embryoid body formation. Our results indicate that Wnt activation induces nuclear localization of YAP and upregulates the expression of HOXB4, the marker for hindbrain/spinal cord. By contrast, the cells exhibit more rostral forebrain neural identity (expression of TBR1) without Wnt activation. Cytochalasin D was then used to induce cytoplasmic YAP and the results showed the decreased HOXB4 expression. In addition, the incorporation of microparticles in the neural spheroids was investigated for the perturbation of neural patterning. This study may indicate the bidirectional interactions of Wnt signaling and YAP expression during neural tissue patterning, which have the significance in neurological disease modeling, drug screening, and neural tissue regeneration.

  19. Mutation Pattern of Paired Immunoglobulin Heavy and Light Variable Domains in Chronic Lymphocytic Leukemia B Cells

    KAUST Repository

    Ghiotto, Fabio

    2011-01-01

    B-cell chronic lymphocytic leukemia (CLL) patients display leukemic clones bearing either germline or somatically mutated immunoglobulin heavy variable (IGHV ) genes. Most information on CLL immunoglobulins (Igs), such as the definition of stereotyped B-cell receptors (BCRs), was derived from germline unmutated Igs. In particular, detailed studies on the distribution and nature of mutations in paired heavy- and light-chain domains of CLL clones bearing mutated Igs are lacking. To address the somatic hyper-mutation dynamics of CLL Igs, we analyzed the mutation pattern of paired IGHV-diversity-joining (IGHV-D-J ) and immunoglobulin kappa/lambda variable-joining (IGK/LV-J ) rearrangements of 193 leukemic clones that displayed ≥ 2% mutations in at least one of the two immunoglobulin variable (IGV ) genes (IGHV and/or IGK/LV ). The relationship between the mutation frequency in IGHV and IGK/LV complementarity determining regions (CDRs) and framework regions (FRs) was evaluated by correlation analysis. Replacement (R) mutation frequency within IGK/LV chain CDRs correlated significantly with mutation frequency of paired IGHV CDRs in λ but not κ isotype CLL clones. CDRs of IGKV-J rearrangements displayed a lower percentage of R mutations than IGHVs. The frequency/pattern of mutations in kappa CLL Igs differed also from that in κ-expressing normal B cells described in the literature. Instead, the mutation frequency within the FRs of IGHV and either IGKV or IGLV was correlated. Notably, the amount of diversity introduced by replaced amino acids was comparable between IGHVs and IGKVs. The data indicate a different mutation pattern between κ and λ isotype CLL clones and suggest an antigenic selection that, in κ samples, operates against CDR variation.

  20. Basal cell carcinoma: CD56 and cytokeratin 5/6 staining patterns in the differential diagnosis with Merkel cell carcinoma.

    Science.gov (United States)

    Panse, Gauri; McNiff, Jennifer M; Ko, Christine J

    2017-06-01

    Basal cell carcinoma (BCC) can resemble Merkel cell carcinoma (MCC) on histopathological examination and while CK20 is a useful marker in this differential, it is occasionally negative in MCC. CD56, a sensitive marker of neuroendocrine differentiation, is sometimes used to identify MCC, but has been reportedly variably positive in BCC as well. In contrast, CK5/6 consistently labels BCC but is not expressed in neuroendocrine tumors. We evaluated 20 cases of BCC for the pattern of CD56 and cytokeratin 5/6 (CK5/6) staining, hypothesizing that these 2 stains could differentiate BCC from MCC in difficult cases. Seventeen cases of MCC previously stained with CD56 were also examined. All BCCs showed patchy expression of CD56 except for 2 cases, which showed staining of greater than 70% of tumor. CK5/6 was diffusely positive in all cases of BCC. Fifteen of 17 MCCs were diffusely positive for CD56. The difference in the pattern of CD56 expression between MCC and BCC (diffuse vs patchy, respectively) was statistically significant (P < .05). BCC typically shows patchy CD56 expression and diffuse CK5/6 positivity. These 2 markers can be used to distinguish between BCC and MCC in challenging cases. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Tailor-made cell patterning using a near-infrared-responsive composite gel composed of agarose and carbon nanotubes

    International Nuclear Information System (INIS)

    Koga, Haruka; Nakazawa, Kohji; Sada, Takao; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2013-01-01

    Micropatterning is useful for regulating culture environments. We developed a highly efficient near-infrared-(NIR)-responsive gel and established a new technique that enables cell patterning by NIR irradiation. As a new culture substratum, we designed a tissue culture plate that was coated with a composite gel composed of agarose and carbon nanotubes (CNTs). A culture plate coated with agarose only showed no response to NIR irradiation. In contrast, NIR laser irradiation induced heat generation by CNTs; this permitted local solation of the CNT/agarose gel, and consequently, selective cell-adhesive regions were exposed on the tissue culture plate. The solation area was controlled by the NIR intensity, magnification of the object lens and CNT concentration in the gel. Furthermore, we formed circular patterns of HeLa cells and linear patterns of 3T3 cells on the same culture plate through selective and stepwise NIR irradiation of the CNT/agarose gel, and we also demonstrated that individual 3T3 cells migrated along a linear path formed on the CNT/agarose gel by NIR irradiation. These results indicate that our technique is useful for tailor-made cell patterning of stepwise and/or complex cell patterns, which has various biological applications such as stepwise co-culture and the study of cell migration. (paper)

  2. Current and future fire regimes and their influence on natural vegetation in Ethiopia

    DEFF Research Database (Denmark)

    van Breugel, Paulo; Friis, Ib; Demissew, Sebsebe

    2016-01-01

    Fire is a major factor shaping the distribution of vegetation types. In this study, we used a recent high resolution map of potential natural vegetation (PNV) types and MODIS fire products to model and investigate the importance of fire as driver of vegetation distribution patterns in Ethiopia. W...... the influence of future fire regimes....

  3. Recent trends in African fires driven by cropland expansion and El Nino to La Nina transition

    NARCIS (Netherlands)

    Andela, N.; van der Werf, G.R.

    2014-01-01

    Landscape fires are key in African ecosystems and the continent is responsible for ∼70% of global burned area and ∼50% of fire-related carbon emissions. Fires are mostly human ignited, but precipitation patterns govern when and where fires can occur. The relative role of humans and precipitation in

  4. Time-sequential observation of spindle and phragmoplast orientation in BY-2 cells with altered cortical actin microfilament patterning

    OpenAIRE

    Kojo, Kei H; Yasuhara, Hiroki; Hasezawa, Seiichiro

    2014-01-01

    Precise division plane determination is essential for plant development. At metaphase, a dense actin microfilament meshwork appears on both sides of the cell center, forming a characteristic cortical actin microfilament twin peak pattern in BY-2 cells. We previously reported a strong correlation between altered cortical actin microfilament patterning and an oblique mitotic spindle orientation, implying that these actin microfilament twin peaks play a role in the regulation of mitotic spindle ...

  5. Surface Topography Guides Morphology and Spatial Patterning of Induced Pluripotent Stem Cell Colonies

    Directory of Open Access Journals (Sweden)

    Giulio Abagnale

    2017-08-01

    Full Text Available The relevance of topographic cues for commitment of induced pluripotent stem cells (iPSCs is largely unknown. In this study, we demonstrate that groove-ridge structures with a periodicity in the submicrometer range induce elongation of iPSC colonies, guide the orientation of apical actin fibers, and direct the polarity of cell division. Elongation of iPSC colonies impacts also on their intrinsic molecular patterning, which seems to be orchestrated from the rim of the colonies. BMP4-induced differentiation is enhanced in elongated colonies, and the submicron grooves impact on the spatial modulation of YAP activity upon induction with this morphogen. Interestingly, TAZ, a YAP paralog, shows distinct cytoskeletal localization in iPSCs. These findings demonstrate that topography can guide orientation and organization of iPSC colonies, which may affect the interaction between mechanosensors and mechanotransducers in iPSCs.

  6. Fire and fire ecology: Concepts and principles

    Science.gov (United States)

    Mark A. Cochrane; Kevin C. Ryan

    2009-01-01

    Fire has been central to terrestrial life ever since early anaerobic microorganisms poisoned the atmosphere with oxygen and multicellular plant life moved onto land. The combination of fuels, oxygen, and heat gave birth to fire on Earth. Fire is not just another evolutionary challenge that life needed to overcome, it is, in fact, a core ecological process across much...

  7. Cell orientation and regulation of cell–cell communication in human mesenchymal stem cells on different patterns of electrospun fibers

    International Nuclear Information System (INIS)

    Chang, Jui-Chih; Fujita, Satoshi; Tonami, Hiroyuki; Iwata, Hiroo; Kato, Koichi; Hsu, Shan-hui

    2013-01-01

    Cell behavior can be manipulated by the topography of the culture surface. In this study, we examined the intercellular communication and osteogenic differentiation of mesenchymal stem cells (MSCs) grown on electrospun fibers with different orientations and densities. Human bone marrow-derived MSCs (hMSCs) were seeded on poly(ε-caprolactone) (PCL) electrospun scaffolds composed of aligned (1D) or cross-aligned (2D) fibers (1.0–1.2 µm diameter) with high, medium, or low fiber densities. It was found that cells preferred to adhere onto electrospun PCL fibers rather than on the flat substrate. The immunofluorescence staining showed that the expression of vinculin, a focal adhesion protein, was limited to the periphery and the two extremities of aligned cells on the edge of the fibers. Electron microscopy showed that cells extended their lamellipodia across the adjacent fibers and proliferated along the direction of fibers. Cells grown on 1D fibrous scaffolds at all fiber densities had an obvious alignment. On 2D fibers, a higher degree of cell alignment was observed at the higher fiber density. On 1D scaffolds, the gap junction intercellular communication (GJIC) quantified by the lucifer yellow dye transfer assay was significantly promoted in the aligned cells in the direction parallel to the fibers but was abolished in the direction perpendicular to the fibers. The expression of osteogenic marker genes (RUNX2, ALP, and OCN) was significantly enhanced in seven days by culture on 1D but not 2D fibers. It was thus proposed that the promoted osteogenic differentiation of hMSCs may be associated with the fiber-guided and directional induction of GJIC. (paper)

  8. WEREWOLF, a MYB-related protein in Arabidopsis, is a position-dependent regulator of epidermal cell patterning.

    Science.gov (United States)

    Lee, M M; Schiefelbein, J

    1999-11-24

    The formation of the root epidermis of Arabidopsis provides a simple and elegant model for the analysis of cell patterning. A novel gene, WEREWOLF (WER), is described here that is required for position-dependent patterning of the epidermal cell types. The WER gene encodes a MYB-type protein and is preferentially expressed within cells destined to adopt the non-hair fate. Furthermore, WER is shown to regulate the position-dependent expression of the GLABRA2 homeobox gene, to interact with a bHLH protein, and to act in opposition to the CAPRICE MYB. These results suggest a simple model to explain the specification of the two root epidermal cell types, and they provide insight into the molecular mechanisms used to control cell patterning.

  9. Tumor Budding, Micropapillary Pattern, and Polyploidy Giant Cancer Cells in Colorectal Cancer: Current Status and Future Prospects

    Directory of Open Access Journals (Sweden)

    Shiwu Zhang

    2016-01-01

    Full Text Available We previously reported that polyploid giant cancer cells (PGCGs induced by CoCl2 could form through endoreduplication or cell fusion. A single PGCC formed tumors in immunodeficient mice. PGCCs are also the key contributors to the cellular atypia and associate with the malignant grade of tumors. PGCCs have the properties of cancer stem cells and produce daughter cells via asymmetric cell division. Compared with diploid cancer cells, these daughter cells express less epithelial markers and acquire mesenchymal phenotype with importance in cancer development and progression. Tumor budding is generally recognized to correlate with a high recurrence rate, lymph node metastasis, chemoresistance, and poor prognosis of colorectal cancers (CRCs and is a good indicator to predict the metastasis and aggressiveness in CRCs. Micropapillary pattern is a special morphologic pattern and also associates with tumor metastasis and poor prognosis. There are similar morphologic features and molecular phenotypes among tumor budding, micropapillary carcinoma pattern, and PGCCs with their budding daughter cells and all of them show strong ability of tumor invasion and migration. In this review, we discuss the cancer stem cell properties of PGCCs, the molecular mechanisms of their regulation, and the relationships with tumor budding and micropapillary pattern in CRCs.

  10. Challenges Found When Patterning Semiconducting Polymers with Electric Fields for Organic Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Fernando A. de Castro

    2012-01-01

    Full Text Available A material-independent, contactless structuring method of semiconducting organic materials for the fabrication of interface-enhanced bilayer solar cells is not available so far. Patterning of thin films using electrohydrodynamic instabilities possesses many desired characteristics and has convincingly been used as a simple method to structure and replicate patterns of nonconducting polymers on submicrometer length scales. However, the applicability of this technique to a wider range of materials has not been demonstrated yet. Here, we report attempts to structure poly(p-phenylene vinylene in a similar way. We found that thin films of poly(2-methoxy-5-(2′-ethylhexyl-oxy-1,4-phenylene-vinylene (MEH-PPV and poly(2-methoxy-5-(3′,7′-dimethyloctyloxy-1,4-phenylene-vinylene (MDMO-PPV could not be destabilized at all in the limited accessible range of the experimental parameters set by the delicate chemical nature of these materials. We discuss failure origins and present possible loopholes for the patterning of semiconducting polymers using electric fields.

  11. Neural crest cells pattern the surface cephalic ectoderm during FEZ formation

    Science.gov (United States)

    Hu, Diane; Marcucio, Ralph S.

    2012-01-01

    Multiple Fibroblast growth factor (Fgf) ligands are expressed in the forebrain and facial ectoderm, and Vascular Endothelial Growth Factor (VEGF) is expressed in the facial ectoderm. Both pathways activate the MAP kinase cascade and can be suppressed by SU5402. We placed a bead soaked in SU5402 into the brain after emigration of neural crest cells was complete. Within 24 hours we observed reduced pMEK and pERK staining that persisted for at least 48 hours. This was accompanied by significant apoptosis in the face. By day 15 the upper beaks were truncated. Molecular changes in the FNP were also apparent. Normally, Shh is expressed in the Frontonasal Ectodermal Zone and controls patterned growth of the upper jaw. In treated embryos Shh expression was reduced. Both the structural and molecular deficits were mitigated after transplantation of FNP-derived mesenchymal cells. Thus, mesenchymal cells actively participate in signaling interactions of the face, and the absence of neural crest cells in neurocristopathies may not be merely structural. PMID:22411554

  12. Automated patterning and probing with multiple nanoscale tools for single-cell analysis.

    Science.gov (United States)

    Li, Jiayao; Kim, Yeonuk; Liu, Boyin; Qin, Ruwen; Li, Jian; Fu, Jing

    2017-10-01

    The nano-manipulation approach that combines Focused Ion Beam (FIB) milling and various imaging and probing techniques enables researchers to investigate the cellular structures in three dimensions. Such fusion approach, however, requires extensive effort on locating and examining randomly-distributed targets due to limited Field of View (FOV) when high magnification is desired. In the present study, we present the development that automates 'pattern and probe' particularly for single-cell analysis, achieved by computer aided tools including feature recognition and geometric planning algorithms. Scheduling of serial FOVs for imaging and probing of multiple cells was considered as a rectangle covering problem, and optimal or near-optimal solutions were obtained with the heuristics developed. FIB milling was then employed automatically followed by downstream analysis using Atomic Force Microscopy (AFM) to probe the cellular interior. Our strategy was applied to examine bacterial cells (Klebsiella pneumoniae) and achieved high efficiency with limited human interference. The developed algorithms can be easily adapted and integrated with different imaging platforms towards high-throughput imaging analysis of single cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Fire severity and ecosytem responses following crown fires in California shrublands

    Science.gov (United States)

    Keeley, J.E.; Brennan, T.; Pfaff, A.H.

    2008-01-01

    Chaparral shrublands burn in large high-intensity crown fires. Managers interested in how these wildfires affect ecosystem processes generally rely on surrogate measures of fire intensity known as fire severity metrics. In shrublands burned in the autumn of 2003, a study of 250 sites investigated factors determining fire severity and ecosystem responses.Using structural equation modeling we show that stand age, prefire shrub density, and the shortest interval of the prior fire history had significant direct effects on fire severity, explaining >50% of the variation in severity.Fire severity per se is of interest to resource managers primarily because it is presumed to be an indicator of important ecosystem processes such as vegetative regeneration, community recovery, and erosion. Fire severity contributed relatively little to explaining patterns of regeneration after fire. Two generalizations can be drawn: fire severity effects are mostly short-lived, i.e., by the second year they are greatly diminished, and fire severity may have opposite effects on different functional types.Species richness exhibited a negative relationship to fire severity in the first year, but fire severity impacts were substantially less in the second postfire year and varied by functional type. Much of this relationship was due to alien plants that are sensitive to high fire severity; at all scales from 1 to 1000 m2, the percentage of alien species in the postfire flora declined with increased fire severity. Other aspects of disturbance history are also important determinants of alien cover and richness as both increased with the number of times the site had burned and decreased with time since last fire.A substantial number of studies have shown that remote-sensing indices are correlated with field measurements of fire severity. Across our sites, absolute differenced normalized burn ratio (dNBR) was strongly correlated with field measures of fire severity and with fire history at a site

  14. Fire severity and ecosytem responses following crown fires in California shrublands.

    Science.gov (United States)

    Keeley, Jon E; Brennan, Teresa; Pfaff, Anne H

    2008-09-01

    Chaparral shrublands burn in large high-intensity crown fires. Managers interested in how these wildfires affect ecosystem processes generally rely on surrogate measures of fire intensity known as fire severity metrics. In shrublands burned in the autumn of 2003, a study of 250 sites investigated factors determining fire severity and ecosystem responses. Using structural equation modeling we show that stand age, prefire shrub density, and the shortest interval of the prior fire history had significant direct effects on fire severity, explaining > 50% of the variation in severity. Fire severity per se is of interest to resource managers primarily because it is presumed to be an indicator of important ecosystem processes such as vegetative regeneration, community recovery, and erosion. Fire severity contributed relatively little to explaining patterns of regeneration after fire. Two generalizations can be drawn: fire severity effects are mostly shortlived, i.e., by the second year they are greatly diminished, and fire severity may have opposite effects on different functional types. Species richness exhibited a negative relationship to fire severity in the first year, but fire severity impacts were substantially less in the second postfire year and varied by functional type. Much of this relationship was due to alien plants that are sensitive to high fire severity; at all scales from 1 to 1000 m2, the percentage of alien species in the postfire flora declined with increased fire severity. Other aspects of disturbance history are also important determinants of alien cover and richness as both increased with the number of times the site had burned and decreased with time since last fire. A substantial number of studies have shown that remote-sensing indices are correlated with field measurements of fire severity. Across our sites, absolute differenced normalized burn ratio (dNBR) was strongly correlated with field measures of fire severity and with fire history at a

  15. Can Variability of Pattern ERG Signal Help to Detect Retinal Ganglion Cells Dysfunction in Glaucomatous Eyes?

    Directory of Open Access Journals (Sweden)

    Alberto Mavilio

    2015-01-01

    Full Text Available Objective. To evaluate variability of steady-state pattern electroretinogram (SS-PERG signal in normal, suspected, and glaucomatous eyes. Methods. Twenty-one subjects with suspected glaucoma due to disc abnormalities (GS, 37 patients with early glaucoma (EG, and 24 normal control (NC were tested with spectral-domain optical coherence tomography (SD-OCT, standard automated perimetry (SAP, and SS-PERG. Mean deviation (MD, pattern standard deviation (PSD, retinal nerve fiber layer (RNFL, and ganglionar complex cells (GCC were evaluated. The SS-PERG was recorded five consecutive times and the amplitude and phase of second harmonic were measured. PERG amplitude and coefficient of variation of phase (CVphase were recorded, and correlation with structural and functional parameters of disease, by means of one-way ANOVA and Pearson’s correlation, was analysed. Results. PERG amplitude was reduced, as expression of retinal ganglion cells (RGCs dysfunction, in EG patients and GS subjects compared to NC patients (P<0.0001. CVphase was significantly increased in EG patients and GS subjects, compared to healthy (P<0.0001, and it was also correlated with PSD (P=0.0009, GCC (P=0.028, and RNFL (P=0.0078 only in EG patients. Conclusions. Increased intrasession variability of phase in suspected glaucomatous eyes may be a sign of RGCs dysfunction.

  16. Regulation of cell behavior and tissue patterning by bioelectrical signals: challenges and opportunities for biomedical engineering.

    Science.gov (United States)

    Levin, Michael; Stevenson, Claire G

    2012-01-01

    Achieving control over cell behavior and pattern formation requires molecular-level understanding of regulatory mechanisms. Alongside transcriptional networks and biochemical gradients, there functions an important system of cellular communication and control: transmembrane voltage gradients (V(mem)). Bioelectrical signals encoded in spatiotemporal changes of V(mem) control cell proliferation, migration, and differentiation. Moreover, endogenous bioelectrical gradients serve as instructive cues mediating anatomical polarity and other organ-level aspects of morphogenesis. In the past decade, significant advances in molecular physiology have enabled the development of new genetic and biophysical tools for the investigation and functional manipulation of bioelectric cues. Recent data implicate V(mem) as a crucial epigenetic regulator of patterning events in embryogenesis, regeneration, and cancer. We review new conceptual and methodological developments in this fascinating field. Bioelectricity offers a novel way of quantitatively understanding regulation of growth and form in vivo, and it reveals tractable, powerful control points that will enable truly transformative applications in bioengineering, regenerative medicine, and synthetic biology.

  17. Fire-driven alien invasion in a fire-adapted ecosystem

    Science.gov (United States)

    Keeley, Jon E.; Brennan, Teresa J.

    2012-01-01

    Disturbance plays a key role in many alien plant invasions. However, often the main driver of invasion is not disturbance per se but alterations in the disturbance regime. In some fire-adapted shrublands, the community is highly resilient to infrequent, high-intensity fires, but changes in the fire regime that result in shorter fire intervals may make these communities more susceptible to alien plant invasions. This study examines several wildfire events that resulted in short fire intervals in California chaparral shrublands. In one study, we compared postfire recovery patterns in sites with different prefire stand ages (3 and 24 years), and in another study we compared sites that had burned once in four years with sites that had burned twice in this period. The population size of the dominant native shrub Adenostoma fasciculatum was drastically reduced following fire in the 3-year sites relative to the 24-year sites. The 3-year sites had much greater alien plant cover and significantly lower plant diversity than the 24-year sites. In a separate study, repeat fires four years apart on the same sites showed that annual species increased significantly after the second fire, and alien annuals far outnumbered native annuals. Aliens included both annual grasses and annual forbs and were negatively correlated with woody plant cover. Native woody species regenerated well after the first fire but declined after the second fire, and one obligate seeding shrub was extirpated from two sites by the repeat fires. It is concluded that some fire-adapted shrublands are vulnerable to changes in fire regime, and this can lead to a loss of native diversity and put the community on a trajectory towards type conversion from a woody to an herbaceous system. Such changes result in alterations in the proportion of natives to non-natives, changes in functional types from deeply rooted shrubs to shallow rooted grasses and forbs, increased fire frequency due to the increase in fine fuels

  18. Serum proteomic patterns of patients with non-small cell lung cancer treated by radiochemotherapy

    International Nuclear Information System (INIS)

    Li Xianglan; You Qingshan; Yang Yanmei; Ma Yuyan; Tang Yali; Cai Huilong

    2007-01-01

    Objective:To detect the serum proteomic patterns of patients with non-small cell lung (NSCLC) treated with radiochemotherapy by surface enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF-MS) protein chip array techniques, and to screen differential expression protein and observe the changes between the patterns before and after the treatment. Methods: SELDI-TOF-MS and CM-10 protein chips were used to detect the serum proteomic patterns of 35 healthy persons (normal control) and 35 patients with NSCLC before radiochemotherapy. Twenty-six out of the 35 patients after the treatment were also studied. BioMarker Wizard 3.01 and BioMarker Pattern System 5. 01 were used in combination to analyze the data and to develop diagnostic models. Results: Sixteen differential expression protein peaks from a total of 251 protein peaks were automatically chosen, including 8 high expressions and 8 low expressions in patients with NSCLC. Of the 16 protein peaks, 6 protein peak patterns ( M 2 572.1, M 2 885.8, M 3 870.4, M 4 161.4, M 5 739.7 and M 8 164.3 mass/charge ratio [ m/z] ) were observed in model that could be used to distinguish lung cancer' from non-cancer diseases. The sensitivity and specificity results were 91% (32/35)and 83% (29/35). When the SELDI marker pattern was tested with the blinded test set, the sensitivity and specificity were 80% (28/35) and 71% (25/35). The 16 differential expression protein peaks of patients before and after the treatment were obviously different. But the peaks of patients after the treatment trended to those of the normal control. Of the 16 protein peaks, M 2 572.1, M 2 885.8, M 4 664.78, M 9 228.39 and M 9 396.42 were significantly changed. Conclusions: SELDI-TOF-MS is possibly significant for screening differential expression proteins and assessing the treatment efficacy and prognosis of patients, which needs to be demonstrated by further study. (authors)

  19. Students' Understanding of Cells & Heredity: Patterns of Understanding in the Context of a Curriculum Implementation in Fifth & Seventh Grades

    Science.gov (United States)

    Cisterna, Dante; Williams, Michelle; Merritt, Joi

    2013-01-01

    This study explores upper-elementary and early-middle-school students' ideas about cells and inheritance and describes patterns of understanding for these topics. Data came from students' responses to embedded assessments included in a technology-enhanced curriculum designed to help students learn about cells and heredity. Our findings suggest…

  20. Bipolar Plasma Membrane Distribution of Phosphoinositides and Their Requirement for Auxin-Mediated Cell Polarity and Patterning in Arabidopsis

    NARCIS (Netherlands)

    Tejos, R.; Sauer, M.; Vanneste, S.; Palacios-Gomez, M.; Li, H.; Heilmann, M.; van Wijk, R.; Vermeer, J.E.M.; Heilmann, I.; Munnik, T.; Friml, J.

    2014-01-01

    Cell polarity manifested by asymmetric distribution of cargoes, such as receptors and transporters, within the plasma membrane (PM) is crucial for essential functions in multicellular organisms. In plants, cell polarity (re)establishment is intimately linked to patterning processes. Despite the

  1. Protein and cell patterning in closed polymer channels by photoimmobilizing proteins on photografted poly(ethylene glycol) diacrylate

    DEFF Research Database (Denmark)

    Larsen, Esben Kjær Unmack; Mikkelsen, Morten Bo Lindholm; Larsen, Niels Bent

    2014-01-01

    on uncoated polymer surfaces. The coating could also efficiently suppress the adhesion of mammalian cells as demonstrated using the HT-29 cancer cell line. In a subsequent equivalent process step, protein in aqueous solution could be anchored onto the PEGDA coating in spatially defined patterns...

  2. Fires, ecological effects of

    Science.gov (United States)

    W. J. Bond; Robert Keane

    2017-01-01

    Fire is both a natural and anthropogenic disturbance influencing the distribution, structure, and functioning of terrestrial ecosystems around the world. Many plants and animals depend on fire for their continued existence. Others species, such as rainforest plants species, are extremely intolerant of burning and need protection from fire. The properties of a fire...

  3. The Frequency and Fate of Understory Forest Fires in Amazonia

    Science.gov (United States)

    Morton, D. C.; le page, Y.; Wang, D.; Chen, Y.; Randerson, J. T.; Collatz, G. J.; Giglio, L.; Hurtt, G. C.; DeFries, R. S.

    2012-12-01

    Fires for deforestation or agricultural management frequently escape their intended boundaries and burn standing Amazon forests. The extent and frequency of understory forest fires are critical to assess forest carbon emissions and the long-term legacy of understory fires in Amazonia. Patterns of understory fire activity under current climate conditions also offer a blueprint for potential changes in Amazon forests under scenarios of future climate and land use. Here, we estimated of the extent and frequency of understory forest fires for the entire arc of deforestation in southern Amazonia using a time series of annual Moderate Resolution Imaging Spectroradiometer (MODIS) data. Understory forest fires burned more than 80,000 km2 during 1999-2010. Fires were widespread along the southern and eastern extents of Amazon forests during the four years with highest fire activity (1999, 2005, 2007, 2010). The interannual variability in understory fires offered new insights into fire-climate dynamics in Amazonia over a range of temporal scales, based on the combination of burned area, MODIS active fire detections, and reanalysis climate data. Initial fire exposure reduces aboveground carbon stocks, and frequent fires are one possible mechanism for long-term changes the structure of Amazon forests. Repeated burning was concentrated in southeastern Amazonia, and >95% of all repeated fires occurred in the Brazilian states of Mato Grosso and Pará. Forests that burned two or more times during this period accounted for 16% of understory fire activity. Finally, deforestation of burned forests was rare, suggesting that forest degradation from understory fires was an independent source of carbon emissions during this period. Modeling the time scales of carbon loss and recovery in burned forests is therefore critical to estimate the net carbon emissions from these fires. The results of this study suggest that understory fires operate as a large-scale edge effect in Amazonia, as

  4. Diagnostic features in two-dimensional light scattering patterns of normal and dysplastic cervical cell nuclei

    Science.gov (United States)

    Arifler, Dizem; MacAulay, Calum; Follen, Michele; Guillaud, Martial

    2014-03-01

    Dysplastic progression in epithelial tissues is linked to changes in morphology and internal structure of cell nuclei. These changes lead to alterations in nuclear light scattering profiles that can potentially be monitored for diagnostic purposes. Numerical tools allow for simulation of complex nuclear models and are particularly useful for quantifying the optical response of cell nuclei as dysplasia progresses. In this study, we first analyze a set of quantitative histopathology images from twenty cervical biopsy sections stained with Feulgen-thionin. Since Feulgen-thionin is stoichiometric for DNA, the images enable us to obtain detailed information on size, shape, and chromatin content of all the segmented nuclei. We use this extensive data set to construct realistic three-dimensional computational models of cervical cell nuclei that are representative of four diagnostic categories, namely normal or negative for dysplasia, mild dysplasia, moderate dysplasia, and severe dysplasia or carcinoma in situ (CIS). We then carry out finite-difference time-domain simulations to compute the light scattering response of the constructed models as a function of the polar scattering angle and the azimuthal scattering angle. The results show that these two-dimensional scattering patterns exhibit characteristic intensity ridges that change form with progression of dysplasia; pattern processing reveals that Haralick features can be used to distinguish moderately and severely dysplastic or CIS nuclei from normal and mildly dysplastic nuclei. Our numerical study also suggests that different angular ranges need to be considered separately to fully exploit the diagnostic potential of two-dimensional light scattering measurements.

  5. Expression of Eag1 K+ channel and ErbBs in human pituitary adenomas: cytoskeleton arrangement patterns in cultured cells.

    Science.gov (United States)

    del Pliego, Margarita González; Aguirre-Benítez, Elsa; Paisano-Cerón, Karina; Valdovinos-Ramírez, Irene; Rangel-Morales, Carlos; Rodríguez-Mata, Verónica; Solano-Agama, Carmen; Martín-Tapia, Dolores; de la Vega, María Teresa; Saldoval-Balanzario, Miguel; Camacho, Javier; Mendoza-Garrido, María Eugenia

    2013-01-01

    Pituitary adenomas can invade surrounded tissue, but the mechanism remains elusive. Ether à go-go-1 (Eag1) potassium channel and epidermal growth factor receptors (ErbB1 and ErbB2) have been associated to invasive phenotypes or poor prognosis in cancer patients. However, cells arrange their cytoskeleton in order to acquire a successful migration pattern. We have studied ErbBs and Eag1 expression, and cytoskeleton arrangements in 11 human pituitary adenomas. Eag1, ErbB1 and ErbB2 expression were studied by immunochemistry in tissue and cultured cells. The cytoskeleton arrangement was analyzed in cultured cells by immunofluorescence. Normal pituitary tissue showed ErbB2 expression and Eag1 only in few cells. However, Eag1 and ErbB2 were expressed in all the tumors analyzed. ErbB1 expression was observed variable and did not show specificity for a tumor characteristic. Cultured cells from micro- and macro-adenomas clinically functional organize their cytoskeleton suggesting a mesenchymal pattern, and a round leucocyte/amoeboid pattern from invasive clinically silent adenoma. Pituitary tumors over-express EGF receptors and the ErbB2 repeated expression suggests is a characteristic of adenomas. Eag 1 was express, in different extent, and could be a therapeutic target. The cytoskeleton arrangements observed suggest that pituitary tumor cells acquire different patterns: mesenchymal, and leucocyte/amoeboid, the last observed in the invasive adenomas. Amoeboid migration pattern has been associated with high invasion capacity.

  6. Diversity and species composition of West African ungulate assemblages: effects of fire, climate and soil

    NARCIS (Netherlands)

    Klop, L.F.; Prins, H.H.T.

    2008-01-01

    Aim Anthropogenic fires are a major component of the ecology of rangelands throughout the world. To assess the effects of these fires on the diversity patterns of herbivores, we related gradients in fire occurrence, climate and soil fertility to patterns in alpha and beta diversity of African

  7. Increasing elevation of fire in the Sierra Nevada and implications for forest change

    Science.gov (United States)

    Mark W. Schwartz; Nathalie Butt; Christopher R. Dolanc; Andrew Holguin; Max A. Moritz; Malcolm P. North; Hugh D. Safford; Nathan L. Stephenson; James H. Thorne; Phillip J. van Mantgem

    2015-01-01

    Fire in high-elevation forest ecosystems can have severe impacts on forest structure, function and biodiversity. Using a 105-year data set, we found increasing elevation extent of fires in the Sierra Nevada, and pose five hypotheses to explain this pattern. Beyond the recognized pattern of increasing fire frequency in the Sierra Nevada since the late 20th century, we...

  8. Prevalence and pattern of sickle cell disease in premarital couples in Southeastern Nigeria.

    Science.gov (United States)

    Nnaji, G A; Ezeagwuna, D A; Nnaji, Ijf; Osakwe, J O; Nwigwe, A C; Onwurah, O W

    2013-01-01

    Premarital haemoglobin screening is an important strategy for the control of Sickle Cell Disease. To determine the prevalence and pattern of sickle cell disease among premarital couples and to assess their attitude to the risk of sickle cell anaemia in their offspring. A cross sectional descriptive study using interviewer administered questionnaire and haemoglobin screening to collect data. Systematic sampling of every third premarital couples attending the General outpatient Clinic of Nnamdi Azikiwe University Teaching Hospital, Nnewi, between November 2010 and October 2011 was used to select the subjects for the study. SPSS version 16 was used for statistical analysis of data from 212 premarital couples or 424 subjects. The prevalence of HbAA and HbAS were 72.64% or 308/424 and 26.4% or 112/424, respectively, while HbSS was 0.94% or 4/424. In 95.3% of the couples there was no risk of offspring inheriting sickle cell anaemia. An equal percentage of males (χ2 = 24.704; df = 6; P = 0.000) and females (χ2 = 12. 684; df 6; P = 0.048) (67.9% or 144/212) would call-off their marriage if there was risk of their offspring being HbSS. Three quarters of the premarital couples had HbAA, while one quarter had Sickle cell trait. A very low percentage of the couples (2.8%) had 1:4 risk of their offspring inheriting SCA (HbSS). About 2/3 of the subjects would call-off the marriage if there was risk of their offspring inheriting SCA.

  9. hESC Differentiation toward an Autonomic Neuronal Cell Fate Depends on Distinct Cues from the Co-Patterning Vasculature

    Directory of Open Access Journals (Sweden)

    Lisette M. Acevedo

    2015-06-01

    Full Text Available To gain insight into the cellular and molecular cues that promote neurovascular co-patterning at the earliest stages of human embryogenesis, we developed a human embryonic stem cell model to mimic the developing epiblast. Contact of ectoderm-derived neural cells with mesoderm-derived vasculature is initiated via the neural crest (NC, not the neural tube (NT. Neurovascular co-patterning then ensues with specification of NC toward an autonomic fate requiring vascular endothelial cell (EC-secreted nitric oxide (NO and direct contact with vascular smooth muscle cells (VSMCs via T-cadherin-mediated homotypic interactions. Once a neurovascular template has been established, NT-derived central neurons then align themselves with the vasculature. Our findings reveal that, in early human development, the autonomic nervous system forms in response to distinct molecular cues from VSMCs and ECs, providing a model for how other developing lineages might coordinate their co-patterning.

  10. ANGUSTIFOLIA mediates one of the multiple SCRAMBLED signaling pathways regulating cell growth pattern in Arabidopsis thaliana.

    Science.gov (United States)

    Kwak, Su-Hwan; Song, Sang-Kee; Lee, Myeong Min; Schiefelbein, John

    2015-09-25

    In Arabidopsis thaliana, an atypical leucine-rich repeat receptor-like kinase, SCRAMBLED (SCM), is required for multiple developmental processes including root epidermal cell fate determination, silique dehiscence, inflorescence growth, ovule morphogenesis, and tissue morphology. Previous work suggested that SCM regulates these multiple pathways using distinct mechanisms via interactions with specific downstream factors. ANGUSTIFOLIA (AN) is known to regulate cell and tissue morphogenesis by influencing cortical microtubule arrangement, and recently, the AN protein was reported to interact with the SCM protein. Therefore, we examined whether AN might be responsible for mediating some of the SCM-dependent phenotypes. We discovered that both scm and an mutant lines cause an abnormal spiral or twisting growth of roots, but only the scm mutant affected root epidermal patterning. The siliques of the an and scm mutants also exhibited spiral growth, as previously reported, but only the scm mutant altered silique dehiscence. Interestingly, we discovered that the spiral growth of roots and siliques of the scm mutant is rescued by a truncated SCM protein that lacks its kinase domain, and that a juxtamembrane domain of SCM was sufficient for AN binding in the yeast two-hybrid analysis. These results suggest that the AN protein is one of the critical downstream factors of SCM pathways specifically responsible for mediating its effects on cell/tissue morphogenesis through cortical microtubule arrangement. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Immunoarchitectural patterns in nodal marginal zone B-cell lymphoma: a study of 51 cases.

    Science.gov (United States)

    Salama, Mohamed E; Lossos, Izidore S; Warnke, Roger A; Natkunam, Yasodha

    2009-07-01

    Nodal marginal zone lymphoma (NMZL) represents a rare and heterogeneous group that lacks markers specific for the diagnosis. We evaluated morphologic and immunoarchitectural features of 51 NMZLs, and the following immunostains were performed: CD20, CD21, CD23, CD5, CD3, CD43, CD10, Ki-67, BCL1, BCL2, BCL6, HGAL, and LMO2. Four immunoarchitectural patterns were evident: diffuse (38 [75%]), well-formed nodular/follicular (5 [10%]), interfollicular (7 [14%]), and perifollicular (1 [2%]). Additional features included a monocytoid component (36 [71%]), admixed large cells (20 [39%]), plasma cells (24 [47%]), compartmentalizing stromal sclerosis (13 [25%]), and prominent blood vessel sclerosis (10 [20%]). CD21 highlighted disrupted follicular dendritic cell meshwork in 35 (71%) of 49 cases, and CD43 coexpression was present in 10 (24%) of 42 cases. A panel of germinal center-associated markers was helpful in eliminating cases of diffuse follicle center lymphoma. Our results highlight the histologic and immunoarchitectural spectrum of NMZL and the usefulness of immunohistochemical analysis for CD43, CD23, CD21, BCL6, HGAL, and LMO2 in the diagnosis of NMZL.

  12. Fire, safety and ventilation

    Energy Technology Data Exchange (ETDEWEB)

    Hindle, D.

    1999-02-01

    Correct ventilation in tunnel environments is vital for the comfort and safety of the people passing through. This article gives details of products from several manufacturers of safety rescue and fire fighting equipment, fire and fume detection equipment, special fire resistant materials, fire resistant hydraulic oils and fire dampers, and ventilation systems. Company addresses and fax numbers are supplied. 4 refs., 5 tabs., 10 photos.

  13. Fire-Walking

    Science.gov (United States)

    Willey, David

    2010-01-01

    This article gives a brief history of fire-walking and then deals with the physics behind fire-walking. The author has performed approximately 50 fire-walks, took the data for the world's hottest fire-walk and was, at one time, a world record holder for the longest fire-walk (www.dwilley.com/HDATLTW/Record_Making_Firewalks.html). He currently…

  14. Smoldering - The Fire Scenario

    OpenAIRE

    Torero, Jose L

    2000-01-01

    There are certain fire initiation scenarios that are particularly common, one of great significance is a fire initiated from the ignition of a porous fuel. Nearly 40% of the deaths due to fire can be traced to cigarette induced smolder of upholstered furniture and the mechanisms that control the process that transforms the weak smolder reaction occurring in the cigarette to a fire are still mostly unknown. A general description of this fire scenario and a discussion of its threats is pr...

  15. Fire and deforestation dynamics in Amazonia (1973–2014)

    Science.gov (United States)

    Field, Robert D.; van der Werf, Guido R.; Estrada de Wagt, Ivan A.; Houghton, Richard A.; Rizzo, Luciana V.; Artaxo, Paulo; Tsigaridis, Kostas

    2017-01-01

    Abstract Consistent long‐term estimates of fire emissions are important to understand the changing role of fire in the global carbon cycle and to assess the relative importance of humans and climate in shaping fire regimes. However, there is limited information on fire emissions from before the satellite era. We show that in the Amazon region, including the Arc of Deforestation and Bolivia, visibility observations derived from weather stations could explain 61% of the variability in satellite‐based estimates of bottom‐up fire emissions since 1997 and 42% of the variability in satellite‐based estimates of total column carbon monoxide concentrations since 2001. This enabled us to reconstruct the fire history of this region since 1973 when visibility information became available. Our estimates indicate that until 1987 relatively few fires occurred in this region and that fire emissions increased rapidly over the 1990s. We found that this pattern agreed reasonably well with forest loss data sets, indicating that although natural fires may occur here, deforestation and degradation were the main cause of fires. Compared to fire emissions estimates based on Food and Agricultural Organization's Global Forest and Resources Assessment data, our estimates were substantially lower up to the 1990s, after which they were more in line. These visibility‐based fire emissions data set can help constrain dynamic global vegetation models and atmospheric models with a better representation of the complex fire regime in this region. PMID:28286373

  16. Fire and deforestation dynamics in Amazonia (1973-2014).

    Science.gov (United States)

    van Marle, Margreet J E; Field, Robert D; van der Werf, Guido R; Estrada de Wagt, Ivan A; Houghton, Richard A; Rizzo, Luciana V; Artaxo, Paulo; Tsigaridis, Kostas

    2017-01-01

    Consistent long-term estimates of fire emissions are important to understand the changing role of fire in the global carbon cycle and to assess the relative importance of humans and climate in shaping fire regimes. However, there is limited information on fire emissions from before the satellite era. We show that in the Amazon region, including the Arc of Deforestation and Bolivia, visibility observations derived from weather stations could explain 61% of the variability in satellite-based estimates of bottom-up fire emissions since 1997 and 42% of the variability in satellite-based estimates of total column carbon monoxide concentrations since 2001. This enabled us to reconstruct the fire history of this region since 1973 when visibility information became available. Our estimates indicate that until 1987 relatively few fires occurred in this region and that fire emissions increased rapidly over the 1990s. We found that this pattern agreed reasonably well with forest loss data sets, indicating that although natural fires may occur here, deforestation and degradation were the main cause of fires. Compared to fire emissions estimates based on Food and Agricultural Organization's Global Forest and Resources Assessment data, our estimates were substantially lower up to the 1990s, after which they were more in line. These visibility-based fire emissions data set can help constrain dynamic global vegetation models and atmospheric models with a better representation of the complex fire regime in this region.

  17. Differential expression pattern of extracellular matrix molecules during chondrogenesis of mesenchymal stem cells from bone marrow and adipose tissue

    DEFF Research Database (Denmark)

    Mehlhorn, A T; Niemeyer, P; Kaiser, S

    2006-01-01

    Adipose-derived adult stem cells (ADASCs) or bone marrow-derived mesenchymal stem cells (BMSCs) are considered as alternative cell sources for cell-based cartilage repair due to their ability to produce cartilage-specific matrix. This article addresses the differential expression pattern...... chondroinduction. TGF-beta1 induces alternative splicing of the alpha(1)-procollagen type II transcript in BMSCs, but not in ADASCs. These findings may direct the development of a cell-specific culture environment either to prevent hypertrophy in BMSCs or to promote chondrogenic maturation in ADASCs....

  18. Advanced Fire Information System - A real time fire information system for Africa

    Science.gov (United States)

    Frost, P. E.; Roy, D. P.

    2012-12-01

    The Council for Scientific and Industrial Research (CSIR) lead by the Meraka Institute and supported by the South African National Space Agency (SANSA) developed the Advanced Fire Information System (AFIS) to provide near real time fire information to a variety of operational and science fire users including disaster managers, fire fighters, farmers and forest managers located across Southern and Eastern Africa. The AFIS combines satellite data with ground based observations and statistics and distributes the information via mobile phone technology. The system was launched in 2004, and Eskom (South Africa' and Africa's largest power utility) quickly became the biggest user and today more than 300 Eskom line managers and support staff receive cell phone and email fire alert messages whenever a wildfire is within 2km of any of the 28 000km of Eskom electricity transmission lines. The AFIS uses Earth observation satellites from NASA and Europe to detect possible actively burning fires and their fire radiative power (FRP). The polar orbiting MODIS Terra and Aqua satellites provide data at around 10am, 15pm, 22am and 3am daily, while the European Geostationary MSG satellite provides 15 minute updates at lower spatial resolution. The AFIS processing system ingests the raw satellite data and within minutes of the satellite overpass generates fire location and FRP based fire intensity information. The AFIS and new functionality are presented including an incident report and permiting system that can be used to differentiate between prescribed burns and uncontrolled wild fires, and the provision of other information including 5-day fire danger forecasts, vegetation curing information and historical burned area maps. A new AFIS mobile application for IOS and Android devices as well as a fire reporting tool are showcased that enable both the dissemination and alerting of fire information and enable user upload of geo tagged photographs and on the fly creation of fire reports

  19. Self-Reported Physical Activity and Exercise Patterns in Children With Sickle Cell Disease.

    Science.gov (United States)

    Omwanghe, Osarhiemen A; Muntz, Devin S; Kwon, Soyang; Montgomery, Simone; Kemiki, Opeyemi; Hsu, Lewis L; Thompson, Alexis A; Liem, Robert I

    2017-08-01

    Sickle cell disease (SCD) significantly affects physical functioning. We examined physical activity (PA) patterns in children with SCD versus a national sample and factors associated with PA and participation in physical education and organized sports. One hundred children with SCD completed a 58-item survey with questions from the 2009-2010 National Health and Nutrition Examination Survey (NHANES) Physical Activity Questionnaire and others on physical education and sports, disease impact, and physical functioning. Compared with NHANES participants, more children with SCD (67 vs 42%, p physical education and sports, respectively. Greater disease impact on PA and physical functioning were associated with lower participation. Children with SCD are active at moderate to vigorous intensity for shorter durations. Negative personal beliefs about disease impact and poor physical functioning represent barriers to PA in SCD.

  20. Effects of Burn Severity and Environmental Conditions on Post-Fire Regeneration in Siberian Larch Forest

    OpenAIRE

    Thuan Chu; Xulin Guo; Kazuo Takeda

    2017-01-01

    Post-fire forest regeneration is strongly influenced by abiotic and biotic heterogeneity in the pre- and post-fire environments, including fire regimes, species characteristics, landforms, hydrology, regional climate, and soil properties. Assessing these drivers is key to understanding the long-term effects of fire disturbances on forest succession. We evaluated multiple factors influencing patterns of variability in a post-fire boreal Larch (Larix sibirica) forest in Siberia. A time-series o...

  1. Nano/micro-patterning the membrane-electrocatalyst layer for fuel cell applications

    Science.gov (United States)

    Omosebi, Ayokunle O.

    Polymer electrolyte membrane fuel cells (PEMFCs) are high energy density electrochemical devices capable of directly converting stored chemical potential into electricity. Their many attributes, including low emissions, quiet operation, scalability, modularity and efficiency make them attractive alternatives to conventional portable and stationary power sources. The emergence of the PEMFC as a dominant technology for electrical power generation is however currently limited by performance losses and the cost of the membrane electrode assembly (MEA). The basic architecture of the MEA, which has remained largely unchanged for over four decades, consists of ink-based platinum supported on carbon catalyst layers dispersed on either side of a Nafion membrane. In order to generate power from the electrochemical reaction, protons, electrons, and oxidant must be available at the catalyst layer-Nafion ionomer interface. As such, to improve performance, the availability of this interface should be maximized without increasing the transport resistance for reactants accessing the reaction plane. To achieve this objective, the membrane-electrode interface could be restructured to possess a larger interfacial area by creating nano/microfeatures on the Nafion membrane. This work introduces electron beam lithography coupled with dry etching and sputtering strategies for creating membrane-electrode structures with over-potential suppression characteristics in PEMFCs. Electron beam lithography provides the ability to fabricate nano/microfeatures in an electron beam sensitive material, while pattern transfer and aspect-ratio control is achieved with dry etching. Conventional and ultra-thin catalyst layers were fabricated by spraying and sputter deposition, and methanol and hydrogen were tested as fuels. Experiments involving the patterned MEA elucidate improved properties that lead to PEMFC performance enhancement. The ability to directly pattern a Nafion membrane

  2. Gene expression patterns induced at different stages of rhinovirus infection in human alveolar epithelial cells.

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Etemadi

    Full Text Available Human rhinovirus (HRV is the common virus that causes acute respiratory infection (ARI and is frequently associated with lower respiratory tract infections (LRTIs. We aimed to investigate whether HRV infection induces a specific gene expression pattern in airway epithelial cells. Alveolar epithelial cell monolayers were infected with HRV species B (HRV-B. RNA was extracted from both supernatants and infected monolayer cells at 6, 12, 24 and 48 hours post infection (hpi and transcriptional profile was analyzed using Affymetrix GeneChip and the results were subsequently validated using quantitative Real-time PCR method. HRV-B infects alveolar epithelial cells which supports implication of the virus with LRTIs. In total 991 genes were found differentially expressed during the course of infection. Of these, 459 genes were up-regulated whereas 532 genes were down-regulated. Differential gene expression at 6 hpi (187 genes up-regulated vs. 156 down-regulated were significantly represented by gene ontologies related to the chemokines and inflammatory molecules indicating characteristic of viral infection. The 75 up-regulated genes surpassed the down-regulated genes (35 at 12 hpi and their enriched ontologies fell into discrete functional entities such as regulation of apoptosis, anti-apoptosis, and wound healing. At later time points of 24 and 48 hpi, predominated down-regulated genes were enriched for extracellular matrix proteins and airway remodeling events. Our data provides a comprehensive image of host response to HRV infection. The study suggests the underlying molecular regulatory networks genes which might be involved in pathogenicity of the HRV-B and potential targets for further validations and development of effective treatment.

  3. Multiciliated cell basal bodies align in stereotypical patterns coordinated by the apical cytoskeleton

    Science.gov (United States)

    Herawati, Elisa; Kanoh, Hatsuho

    2016-01-01

    Multiciliated cells (MCCs) promote fluid flow through coordinated ciliary beating, which requires properly organized basal bodies (BBs). Airway MCCs have large numbers of BBs, which are uniformly oriented and, as we show here, align linearly. The mechanism for BB alignment is unexplored. To study this mechanism, we developed a long-term and high-resolution live-imaging system and used it to observe green fluorescent protein–centrin2–labeled BBs in cultured mouse tracheal MCCs. During MCC differentiation, the BB array adopted four stereotypical patterns, from a clustering “floret” pattern to the linear “alignment.” This alignment process was correlated with BB orientations, revealed by double immunostaining for BBs and their asymmetrically associated basal feet (BF). The BB alignment was disrupted by disturbing apical microtubules with nocodazole and by a BF-depleting Odf2 mutation. We constructed a theoretical model, which indicated that the apical cytoskeleton, acting like a viscoelastic fluid, provides a self-organizing mechanism in tracheal MCCs to align BBs linearly for mucociliary transport. PMID:27573463

  4. Source, pattern and antibiotic resistance of blood stream infections in hematopoietic stem cell transplant recipients

    International Nuclear Information System (INIS)

    El-Mahallawy, H.; Samir, I.; Kadry, D.; Abdel Fattah, R.; El-Kholy, A.

    2014-01-01

    Mucositis developing as a result of myelo-ablative high dose therapy administered prior to hematopoietic stem cell transplantation (HSCT) is associated with the risk of bacteremia. The aim of the present study was to detect the pattern of bacteremia coinciding with the present practice of HSCT, to study the contribution of health-care associated infection (HAI) to the pattern of infection, in the context of the problem of antibiotic resistance in HSCT recipients. Patients and methods: This is a retrospective, single center study including patients who developed febrile neutropenia (FN) among HSCT recipients in one year duration. Results: Ninety FN episodes were recorded in 50 patients. Out of 39 positive blood cultures, Gram negative rods (GNR) were the predominant pathogens, constituting 67% (n =26) of isolated organisms, while 33% of infections were caused by gram positive cocci (GPC) (n= 13). Bacteremia was significantly associated with central venous line (CVL) infections and gastroenteritis (diarrhea and vomiting) with a p-value 0.024, 0.20 and 0.0001, respectively. Multi-drug resistant organisms (MDROs) were identified in 27 (69%) of the 39 positive blood cultures. Conclusion: In one year duration, gram negative pathogens were the predominant causes of infection in HSCT recipients with high rates of MDROs in our institution. Gastroenteritis and central venous line infections are the main sources of bacteremia

  5. Economic feasibility analysis of distributed electric power generation based upon the natural gas-fired fuel cell. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1994-03-01

    The final report provides a summary of results of the Cost of Ownership Model and the circumstances under which a distributed fuel cell is economically viable. The analysis is based on a series of micro computer models estimate the capital and operations cost of a fuel cell central utility plant configuration. Using a survey of thermal and electrical demand profiles, the study defines a series of energy user classes. The energy user class demand requirements are entered into the central utility plant model to define the required size the fuel cell capacity and all supporting equipment. The central plant model includes provisions that enables the analyst to select optional plant features that are most appropriate to a fuel cell application, and that are cost effective. The model permits the choice of system features that would be suitable for a large condominium complex or a residential institution such as a hotel, boarding school or prison. Other applications are also practical; however, such applications have a higher relative demand for thermal energy, a characteristic that is well-suited to a fuel cell application with its free source of hot water or steam. The analysis combines the capital and operation from the preceding models into a Cost of Ownership Model to compute the plant capital and operating costs as a function of capacity and principal features and compares these estimates to the estimated operating cost of the same central plant configuration without a fuel cell.

  6. Wedge cells during regeneration of juvenile and adult feathers and their role in carving out the branching pattern of barbs.

    Science.gov (United States)

    Alibardi, Lorenzo

    2007-01-01

    The present ultrastructural study on regenerating feathers emphasizes the role of supportive cells in determining the branching pattern of barbs. Supportive cells are localized among developing barb and barbule cells, in marginal plates, and underneath the feather sheath, and their differentiative fate, in general, is a form of lipid degeneration. The Latter process determines the carving out of barb branching in both downfeathers and pennaceous feathers. In the latter feathers, some supportive cells (barb vane cells and cylindrical cells of marginal plates) degenerate within each barb ridge leaving separate barbules. Other supportive cells, here termed wedge cells, form columns of cornified material that merge into elongated corneous scaffolds localized among barbs and the rachis. This previously undescribed form of cornification of supportive cells derives from the aggregation of periderm and dense granules present in wedge cells. The latter cells give origin to a corneous material different from feather keratin that may initially sustain the early and soft barbules. After barbules are cornified the supportive cells scaffolds are eventually sloughed as the sheath breaks allowing the new feather to open up and form a planar vane. The corneous material of wedge cells may also contribute to molding of the overlapped nodes of barbule cells that form lateral spines or hooklets in mature barbules. Eventually, the disappearance of wedge cell scaffolding determines the regular spacing of barbs attached to the rachis in order to form a close vane.

  7. Predicting the distribution of spiral waves from cell properties in a developmental-path model of Dictyostelium pattern formation.

    Directory of Open Access Journals (Sweden)

    Daniel Geberth

    2009-07-01

    Full Text Available The slime mold Dictyostelium discoideum is one of the model systems of biological pattern formation. One of the most successful answers to the challenge of establishing a spiral wave pattern in a colony of homogeneously distributed D. discoideum cells has been the suggestion of a developmental path the cells follow (Lauzeral and coworkers. This is a well-defined change in properties each cell undergoes on a longer time scale than the typical dynamics of the cell. Here we show that this concept leads to an inhomogeneous and systematic spatial distribution of spiral waves, which can be predicted from the distribution of cells on the developmental path. We propose specific experiments for checking whether such systematics are also found in data and thus, indirectly, provide evidence of a developmental path.

  8. Davis Fire: Fire behavior and fire effects analysis

    Science.gov (United States)

    LaWen T. Hollingsworth

    2010-01-01

    The Davis Fire presents an interesting example of fire behavior in subalpine fir, partially dead lodgepole pine with multiple age classes, and moist site Douglas-fir vegetation types. This has been summer of moderate temperatures and intermittent moisture that has kept live herbaceous and live woody moistures fairly high and dead fuel moistures at a moderate level....

  9. FIRES: Fire Information Retrieval and Evaluation System - A program for fire danger rating analysis

    Science.gov (United States)

    Patricia L. Andrews; Larry S. Bradshaw

    1997-01-01

    A computer program, FIRES: Fire Information Retrieval and Evaluation System, provides methods for evaluating the performance of fire danger rating indexes. The relationship between fire danger indexes and historical fire occurrence and size is examined through logistic regression and percentiles. Historical seasonal trends of fire danger and fire occurrence can be...

  10. Biological and geophysical feedbacks with fire in the Earth system

    Science.gov (United States)

    Archibald, S.; Lehmann, C. E. R.; Belcher, C. M.; Bond, W. J.; Bradstock, R. A.; Daniau, A.-L.; Dexter, K. G.; Forrestel, E. J.; Greve, M.; He, T.; Higgins, S. I.; Hoffmann, W. A.; Lamont, B. B.; McGlinn, D. J.; Moncrieff, G. R.; Osborne, C. P.; Pausas, J. G.; Price, O.; Ripley, B. S.; Rogers, B. M.; Schwilk, D. W.; Simon, M. F.; Turetsky, M. R.; Van der Werf, G. R.; Zanne, A. E.

    2018-03-01

    Roughly 3% of the Earth’s land surface burns annually, representing a critical exchange of energy and matter between the land and atmosphere via combustion. Fires range from slow smouldering peat fires, to low-intensity surface fires, to intense crown fires, depending on vegetation structure, fuel moisture, prevailing climate, and weather conditions. While the links between biogeochemistry, climate and fire are widely studied within Earth system science, these relationships are also mediated by fuels—namely plants and their litter—that are the product of evolutionary and ecological processes. Fire is a powerful selective force and, over their evolutionary history, plants have evolved traits that both tolerate and promote fire numerous times and across diverse clades. Here we outline a conceptual framework of how plant traits determine the flammability of ecosystems and interact with climate and weather to influence fire regimes. We explore how these evolutionary and ecological processes scale to impact biogeochemical and Earth system processes. Finally, we outline several research challenges that, when resolved, will improve our understanding of the role of plant evolution in mediating the fire feedbacks driving Earth system processes. Understanding current patterns of fire and vegetation, as well as patterns of fire over geological time, requires research that incorporates evolutionary biology, ecology, biogeography, and the biogeosciences.

  11. A cell pattern approach to interpretation of fine needle aspiration cytology of thyroid lesions: A cyto-histomorphological study

    Directory of Open Access Journals (Sweden)

    Bommanahalli Basavaraj

    2010-01-01

    Full Text Available Aim: Our study aimed at a cell pattern approach to interpret thyroid cytology and to demonstrate diagnostic accuracy of fine needle aspiration cytology (FNAC with an emphasis on diagnostic pitfalls. Materials and Methods: A total number of 218 goitre cases, from the year 2000 to 2004, were reviewed retrospectively from the cytology files, without considering the previous cytological diagnosis. Four cases with inadequate aspirate were excluded. The predominant cell pattern, such as macro/normofollicular, microfollicular, papillary, syncytial, dispersed and cystic pattern, was noted in each case. The final diagnosis was arrived by observing the cellular details and background elements. Cytological diagnosis was correlated with histopathology in 75 cases. The sensitivity and specificity were computed. Results: Normo/macrofollicular pattern was seen in 71.96% of nodular goitre and 6.9% of follicular neoplasms. Around 86.2% of follicular neoplasms and 17.6% of papillary carcinoma had microfollicular pattern. The papillary pattern was seen in 47% of papillary carcinoma. Syncytial pattern was noticed in 72.3% of chronic lymphocytic thyroiditis and 29.4% of papillary carcinoma. Cytological diagnosis was concordant with histopathological diagnosis in 65 cases. Overall sensitivity and specificity of FNAC in diagnosing neoplastic lesions of thyroid were 83.33 and 95.55%, respectively. Conclusion: FNAC is more sensitive and specific in triaging neoplastic from non-neoplastic thyroid lesions. Identification of the predominant cell pattern would be complementary to analysis of cell morphology and background details in cytological diagnosis of thyroid lesions. This approach helps to diagnose follicular neoplasm and follicular variant of papillary thyroid carcinoma.

  12. A new approach for determining phase response curves reveals that Purkinje cells can act as perfect integrators.

    Directory of Open Access Journals (Sweden)

    Elena Phoka

    2010-04-01

    Full Text Available Cerebellar Purkinje cells display complex intrinsic dynamics. They fire spontaneously, exhibit bistability, and via mutual network interactions are involved in the generation of high frequency oscillations and travelling waves of activity. To probe the dynamical properties of Purkinje cells we measured their phase response curves (PRCs. PRCs quantify the change in spike phase caused by a stimulus as a function of its temporal position within the interspike interval, and are widely used to predict neuronal responses to more complex stimulus patterns. Significant variability in the interspike interval during spontaneous firing can lead to PRCs with a low signal-to-noise ratio, requiring averaging over thousands of trials. We show using electrophysiological experiments and simulations that the PRC calculated in the traditional way by sampling the interspike interval with brief current pulses is biased. We introduce a corrected approach for calculating PRCs which eliminates this bias. Using our new approach, we show that Purkinje cell PRCs change qualitatively depending on the firing frequency of the cell. At high firing rates, Purkinje cells exhibit single-peaked, or monophasic PRCs. Surprisingly, at low firing rates, Purkinje cell PRCs are largely independent of phase, resembling PRCs of ideal non-leaky integrate-and-fire neurons. These results indicate that Purkinje cells can act as perfect integrators at low firing rates, and that the integration mode of Purkinje cells depends on their firing rate.

  13. Surface patterned dielectrics by direct writing of anodic oxides using scanning droplet cell microscopy

    International Nuclear Information System (INIS)

    Siket, Christian M.; Mardare, Andrei Ionut; Kaltenbrunner, Martin; Bauer, Siegfried; Hassel, Achim Walter

    2013-01-01

    Highlights: • Scanning droplet cell microscopy was applied for local gate oxide writing. • Sharp lines are obtained at the highest writing speed of 1 mm min −1 . • 13.4 kC cm −3 was found as charge per volume for aluminium oxide. • High field constant of 24 nm V −1 and dielectric constant of 12 were determined for Al 2 O 3 by CV and EIS. -- Abstract: Scanning droplet cell microscopy was used for patterning of anodic oxide lines on the surface of Al thin films by direct writing. The structural modifications of the written oxide lines as a function of the writing speed were studied by analyzing the relative error of the line widths. Sharper lines were obtained for writing speeds faster than 1 mm min −1 . An increase in sharpness was observed for higher writing speeds. A theoretical model based on the Faraday law is proposed to explain the constant anodisation current measured during the writing process and yielded a charge per volume of 13.4 kC cm −3 for Al 2 O 3 . From calculated oxide film thicknesses the high field constant was found to be 24 nm V −1 . Electrochemical impedance spectroscopy revealed an increase of the electrical permittivity up to ε = 12 with the decrease of the writing speed of the oxide line. Writing of anodic oxide lines was proven to be an important step in preparing capacitors and gate dielectrics in plastic electronics

  14. Periodic Pattern of Genetic and Fitness Diversity during Evolution of an Artificial Cell-Like System.

    Science.gov (United States)

    Ichihashi, Norikazu; Aita, Takuyo; Motooka, Daisuke; Nakamura, Shota; Yomo, Tetsuya

    2015-12-01

    Genetic and phenotypic diversity are the basis of evolution. Despite their importance, however, little is known about how they change over the course of evolution. In this study, we analyzed the dynamics of the adaptive evolution of a simple evolvable artificial cell-like system using single-molecule real-time sequencing technology that reads an entire single artificial genome. We found that the genomic RNA population increases in fitness intermittently, correlating with a periodic pattern of genetic and fitness diversity produced by repeated diversification and domination. In the diversification phase, a genomic RNA population spreads within a genetic space by accumulating mutations until mutants with higher fitness are generated, resulting in an increase in fitness diversity. In the domination phase, the mutants with higher fitness dominate, decreasing both the fitness and genetic diversity. This study reveals the dynamic nature of genetic and fitness diversity during adaptive evolution and demonstrates the utility of a simplified artificial cell-like system to study evolution at an unprecedented resolution. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Modeling self-organized spatio-temporal patterns of PIP₃ and PTEN during spontaneous cell polarization.

    Science.gov (United States)

    Knoch, Fabian; Tarantola, Marco; Bodenschatz, Eberhard; Rappel, Wouter-Jan

    2014-08-01

    During spontaneous cell polarization of Dictyostelium discoideum cells, phosphatidylinositol (3,4,5)-triphoshpate (PIP3) and PTEN (phosphatase tensin homolog) have been identified as key signaling molecules which govern the process of polarization in a self-organized manner. Recent experiments have quantified the spatio-temporal dynamics of these signaling components. Surprisingly, it was found that membrane-bound PTEN can be either in a high or low state, that PIP3 waves were initiated in areas lacking PTEN through an excitable mechanism, and that PIP3 was degraded even though the PTEN concentration remained low. Here we develop a reaction-diffusion model that aims to explain these experimental findings. Our model contains bistable dynamics for PTEN, excitable dynamics for PIP3, and postulates the existence of two species of PTEN with different dephosphorylation rates. We show that our model is able to produce results that are in good qualitative agreement with the experiments, suggesting that our reaction-diffusion model underlies the self-organized spatio-temporal patterns observed in experiments.

  16. DNA methylation patterns in bladder cancer and washing cell sediments: a perspective for tumor recurrence detection

    International Nuclear Information System (INIS)

    Negraes, Priscilla D; Favaro, Francine P; Camargo, João Lauro V; Oliveira, Maria Luiza CS; Goldberg, José; Rainho, Cláudia A; Salvadori, Daisy MF

    2008-01-01

    Epigenetic alterations are a hallmark of human cancer. In this study, we aimed to investigate whether aberrant DNA methylation of cancer-associated genes is related to urinary bladder cancer recurrence. A set of 4 genes, including CDH1 (E-cadherin), SFN (stratifin), RARB (retinoic acid receptor, beta) and RASSF1A (Ras association (RalGDS/AF-6) domain family 1), had their methylation patterns<