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Sample records for fire danger rating

  1. Fire danger rating network density

    Treesearch

    Rudy M. King; R. William Furman

    1976-01-01

    Conventional statistical techniques are used to answer the question, "What is the necessary station density for a fire danger network?" The Burning Index of the National Fire-Danger Rating System is used as an indicator of fire danger. Results are presented as station spacing in tabular form for each of six regions in the western United States.

  2. Fire Danger Rating: The next 20 Years

    Treesearch

    John E. Deeming

    1987-01-01

    For the next 10 years, few changes will be made to the fire-danger rating system. During that time, the focus will be on the automation of weather observing systems and the streamlining of the computation and display of ratings. The time horizon for projecting fire danger will be pushed to 30 days by the late 1990's. A close alignment of the fire-danger rating...

  3. FIRES: Fire Information Retrieval and Evaluation System - A program for fire danger rating analysis

    Treesearch

    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...

  4. Introduction to fire danger rating and remote sensing - Will remote sensing enhance wildland fire danger prediction?

    USGS Publications Warehouse

    Allgöwer, Britta; Carlson, J.D.; Van Wagtendonk, Jan W.; Chuvieco, Emilio

    2003-01-01

    While ‘Fire Danger’ per se cannot be measured, the physical properties of the biotic and abiotic world that relate to fire occurrence and fire behavior can. Today, increasingly sophisticated Remote Sensing methods are being developed to more accurately detect fuel properties such as species composition (fuel types), vegetation structure or plant water content - to name a few. Based on meteorological input data and physical, semi-physical or empirical model calculations, Wildland Fire Danger Rating Systems provide ‘indirect values’ - numerical indices - at different temporal scales (e.g., daily, weekly, monthly) denoting the physical conditions that may lead to fire ignition and support fire propagation. The results can be expressed as fire danger levels, ranging from ‘low’ to ‘very high’, and are commonly used in operational wildland fire management (e.g., the Canadian Fire Weather Index [FWI] System, the Russian Nesterov Index, or the U.S. National Fire Danger Rating System [NFDRS]). Today, fire danger levels are often turned into broad scale maps with the help of Geographical Information Systems (GIS) showing the areas with the different fire danger levels, and are distributed via the World Wide Web.In this chapter we will outline some key issues dealing with Remote Sensing and GIS techniques that are covered in the following chapters, and elaborate how the Fire Danger Rating concepts could be integrated into a framework that enables comprehensive and sustainable wildland fire risk assessment. To do so, we will first raise some general thoughts about wildland fires and suggest how to approach this extremely complex phenomenon. Second, we will outline a possible fire risk analysis framework and third we will give a short overview on existing Fire Danger Rating Systems and the principles behind them.

  5. A fire danger rating system for Hawaii

    Treesearch

    Robert E. Burgan; Francis M. Fujioka; George H. Hirata

    1974-01-01

    Extremes in rainfall on the Hawaiian Islands make it difficult to judge forest fire danger conditions. The use of an automatic data collection and computer processing system helps to monitor the problem.

  6. Pocket calculator for local fire-danger ratings

    Treesearch

    Richard J. Barney; William C. Fischer

    1967-01-01

    In 1964, Stockstad and Barney published tables that provided conversion factors for calculating local fire danger in the Intermountain area according to fuel types, locations, steepness of terrain, aspects, and times of day. These tables were based on the National Fire-Danger Rating System published earlier that year. This system was adopted for operational use in...

  7. The national fire-danger rating system: basic equations

    Treesearch

    Jack D. Cohen; John E. Deeming

    1985-01-01

    Updating the National Fire-Danger Rating System (NFDRS) was completed in 1977, and operational use of it was begun the next year. The System provides a guide to wildfire control and suppression by its indexes that measure the relative potential of initiating fires. Such fires do not behave erratically–they spread without spotting through continuous ground fuels....

  8. Fire characteristics charts for fire behavior and U.S. fire danger rating

    Treesearch

    Faith Ann Heinsch; Pat Andrews

    2010-01-01

    The fire characteristics chart is a graphical method of presenting U.S. National Fire Danger Rating indices or primary surface or crown fire behavior characteristics. A desktop computer application has been developed to produce fire characteristics charts in a format suitable for inclusion in reports and presentations. Many options include change of scales, colors,...

  9. The 1978 National Fire-Danger Rating System: technical documentation

    Treesearch

    Larry S. Bradshaw; John E. Deeming; Robert E. Burgan; Jack D. Cohen

    1984-01-01

    The National Fire-Danger Rating System (NFDRS), implemented in 1972, has been revised and reissued as the 1978 NFDRS. This report describes the full developmental history of the NFDRS, including purpose, technical foundation, and structure. Includes an extensive bibliography and appendixes.

  10. Fire-danger rating and observed wildfire behavior in the Northeastern United States.

    Treesearch

    Donald A. Haines; William A. Main; Albert J. Simard

    1986-01-01

    Compares the 1978 National Fire-Danger Rating System and its 20 fuel models, along with other danger rating systems, with observed fire behavior and rates the strengths and weaknesses of models and systems.

  11. Fire danger rating in the United States of America: An evolution since 1916

    Treesearch

    Colin C. Hardy; Charles E. Hardy

    2007-01-01

    Fire scientists in the United States began exploring the relationships of fire-danger and hazard with weather, fuel moisture, and ignition probabilities as early as 1916. Many of the relationships identified then persist today in the form of our National Fire-Danger-Rating System. This paper traces the evolution of fire-danger rating in the United States, including...

  12. Forest Fire Danger Rating (FFDR) Prediction over the Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Song, B.; Won, M.; Jang, K.; Yoon, S.; Lim, J.

    2016-12-01

    Approximately five hundred forest fires occur and inflict the losses of both life and property each year in Korea during the forest fire seasons in the spring and autumn. Thus, an accurate prediction of forest fire is essential for effective forest fire prevention. The meteorology is one of important factors to predict and understand the fire occurrence as well as its behaviors and spread. In this study, we present the Forest Fire Danger Rating Systems (FFDRS) on the Korean Peninsula based on the Daily Weather Index (DWI) which represents the meteorological characteristics related to forest fire. The thematic maps including temperature, humidity, and wind speed produced from Korea Meteorology Administration (KMA) were applied to the forest fire occurrence probability model by logistic regression to analyze the DWI over the Korean Peninsula. The regional data assimilation and prediction system (RDAPS) and the improved digital forecast model were used to verify the sensitivity of DWI. The result of verification test revealed that the improved digital forecast model dataset showed better agreements with the real-time weather data. The forest fire danger rating index (FFDRI) calculated by the improved digital forecast model dataset showed a good agreement with the real-time weather dataset at the 233 administrative districts (R2=0.854). In addition, FFDRI were compared with observation-based FFDRI at 76 national weather stations. The mean difference was 0.5 at the site-level. The results produced in this study indicate that the improved digital forecast model dataset can be useful to predict the FFDRI in the Korean Peninsula successfully.

  13. The National Fire Danger Rating System: Derivation of Spread Index for Eastern and Southern States

    Treesearch

    Ralph M. Nelson

    1964-01-01

    Presents standards for locating, operating, and maintaining forest fire danger stations in Eastern and Southern States. Includes tables and forms for deriving the Spread Index of the new National Fire-Danger Rating System.

  14. How to generate and interpret fire characteristics charts for the U.S. fire danger rating system

    Treesearch

    Faith Ann Heinsch; Patricia L. Andrews; Deb Tirmenstein

    2017-01-01

    The fire characteristics chart is a graphical method of presenting U.S. National Fire Danger Rating System (NFDRS) indexes and components as well as primary surface or crown fire behavior characteristics. Computer software has been developed to produce fire characteristics charts for both fire danger and fire behavior in a format suitable for inclusion in reports and...

  15. Climate change and fire danger rating in the Northern Rockies

    Treesearch

    Faith Ann Heinsch; Charles W. McHugh

    2010-01-01

    Studies have indicated that changes in wildland fire activity are, at least in part, a product of climate change. Fire danger indices, driven by climatology, should reflect these changes. Energy Release Component (ERC) is considered to be an effective indicator of drought conditions and seasonal drying of forest fuels and is often used in fire management planning....

  16. Conversion tables for use with the National Fire-Danger Rating System in the Intermountain area

    Treesearch

    Dwight S. Stockstad; Richard J. Barney

    1964-01-01

    Two tables prepared for use with the National Fire-Danger Rating System replace 10 tables previously used with the Model-8 Fire-Danger Rating System. They provide for the conversion of Spread Index values at various altitudes, aspects, and times of day. A rate of spread table facilitates converting Spread Index values to chains per hour of perimeter increase for...

  17. An operational system of fire danger rating over Mediterranean Europe

    NASA Astrophysics Data System (ADS)

    Pinto, Miguel M.; DaCamara, Carlos C.; Trigo, Isabel F.; Trigo, Ricardo M.

    2017-04-01

    A methodology is presented to assess fire danger based on the probability of exceedance of prescribed thresholds of daily released energy. The procedure is developed and tested over Mediterranean Europe, defined by latitude circles of 35 and 45°N and meridians of 10°W and 27.5°E, for the period 2010-2016. The procedure involves estimating the so-called static and daily probabilities of exceedance. For a given point, the static probability is estimated by the ratio of the number of daily fire occurrences releasing energy above a given threshold to the total number of occurrences inside a cell centred at the point. The daily probability of exceedance which takes into account meteorological factors by means of the Canadian Fire Weather Index (FWI) is in turn estimated based on a Generalized Pareto distribution with static probability and FWI as covariates of the scale parameter. The rationale of the procedure is that small fires, assessed by the static probability, have a weak dependence on weather, whereas the larger fires strongly depend on concurrent meteorological conditions. It is shown that observed frequencies of exceedance over the study area for the period 2010-2016 match with the estimated values of probability based on the developed models for static and daily probabilities of exceedance. Some (small) variability is however found between different years suggesting that refinements can be made in future works by using a larger sample to further increase the robustness of the method. The developed methodology presents the advantage of evaluating fire danger with the same criteria for all the study area, making it a good parameter to harmonize fire danger forecasts and forest management studies. Research was performed within the framework of EUMETSAT Satellite Application Facility for Land Surface Analysis (LSA SAF). Part of methods developed and results obtained are on the basis of the platform supported by The Navigator Company that is currently providing

  18. Evaluation of MM5 model resolution when applied to prediction of national fire danger rating indexes

    Treesearch

    Jeanne L. Hoadley; Miriam L. Rorig; Larry Bradshaw; Sue A. Ferguson; Kenneth J. Westrick; Scott L. Goodrick; Paul Werth

    2006-01-01

    Weather predictions from the MM5 mesoscale model were used to compute gridded predictions of National Fire Danger Rating System (NFDRS) indexes. The model output was applied to a case study of the 2000 fire season in Northern Idaho and Western Montana to simulate an extreme event. To determine the preferred resolution for automating NFD RS predictions, model...

  19. 1988 Revisions to the 1978 National Fire-Danger Rating System

    Treesearch

    Robert E. Burgan

    1988-01-01

    The 1978 National Fire-Danger Rating System does not work well in the humid environment of the Eastern United States. System modifications to correct problems and their operational impact on System users are described. A new set of 20 fuel models is defined and compared graphically with the 1978 fuel models. Technical documentation of System changes is provided.

  20. NFDRSPC: The National Fire-Danger Rating System on a Personal Computer

    Treesearch

    Bryan G. Donaldson; James T. Paul

    1990-01-01

    This user's guide is an introductory manual for using the 1988 version (Burgan 1988) of the National Fire-Danger Rating System on an IBM PC or compatible computer. NFDRSPC is a window-oriented, interactive computer program that processes observed and forecast weather with fuels data to produce NFDRS indices. Other program features include user-designed display...

  1. Comparing jack pine slash and forest floor moisture contents and National Fire Danger Rating System predictions.

    Treesearch

    Robert M. Loomis; William A. Main

    1980-01-01

    Relations between certain slash and forest floor moisture contents and the applicable estimated time lag fuel moistures of the National Fire Danger Rating System were investigated for 1-year-old jack pine fuel types in northeastern Minnesota and central Lower Michigan. Only approximate estimates of actual fuel moisture are possible fore the relations determined, thus...

  2. Computer Calculation of Fire Danger

    Treesearch

    William A. Main

    1969-01-01

    This paper describes a computer program that calculates National Fire Danger Rating Indexes. fuel moisture, buildup index, and drying factor are also available. The program is written in FORTRAN and is usable on even the smallest compiler.

  3. Seasonal fire danger forecasts for the USA

    Treesearch

    J. Roads; F. Fujioka; S. Chen; R. Burgan

    2005-01-01

    The Scripps Experimental Climate Prediction Center has been making experimental, near-real-time, weekly to seasonal fire danger forecasts for the past 5 years. US fire danger forecasts and validations are based on standard indices from the National Fire Danger Rating System (DFDRS), which include the ignition component (IC), energy release component (ER), burning...

  4. National fire-danger rating system fine-fuel moisture content tables—an Alaskan adaptation.

    Treesearch

    Richard J. Barney

    1969-01-01

    Fine-fuel moisture content tables, using dry bulb and dewpoint temperatures as entry data, have been developed for use with the National Fire-Danger Rating System in Alaska. Comparisons have been made which illustrate differences resulting from danger-rating calculations based on these new fine-fuel moisture content tables for the cured, transition, and green...

  5. The effect of model resolution in predicting meteorological parameters used in fire danger rating.

    Treesearch

    Jeanne L. Hoadley; Ken Westrick; Sue A. Ferguson; Scott L. Goodrick; Larry Bradshaw; Paul. Werth

    2004-01-01

    Previous studies of model performance at varying resolutions have focused on winter storms or isolated convective events. Little attention has been given to the static high pressure situations that may lead to severe wildfire outbreaks. This study focuses on such an event so as to evaluate the value of increased model resolution for prediction of fire danger. The...

  6. The effect of model resolution in predicting meteorological parameters used in fire danger rating

    Treesearch

    Jeanne L. Hoadley; Ken Westrick; Sue a. Ferguson; Scott L. Goodrick; Larry Bradshaw; Paul Wreth

    2004-01-01

    Previous studies of model perfonnance at varying resolutions have focused on winter stonns or isolated convective events. Little attention has been given to the static high pressure situations that may lead to severe wildfire outbreaks. This study focuses on such an event so as to evaluate the value of increased model resolution for prediction of fire danger. The...

  7. Fire danger rating and fire behavior prediction in the United States

    Treesearch

    Patricia L. Andrews

    2005-01-01

    For the seven year period from 1998 to 2004, an average of almost 79,000 fires per year on U.S. Federal and State land burned a yearly average of over 22,000 km2. An average of 1 billion US dollars was spent on suppression each year by the Federal agencies alone. Variation in climate, vegetation, and population across the U.S. leads to significant differences in the...

  8. NCEP-ECPC monthly to seasonal US fire danger forecasts

    Treesearch

    J. Roads; P. Tripp; H. Juang; J. Wang; F. Fujioka; S. Chen

    2010-01-01

    Five National Fire Danger Rating System indices (including the Ignition Component, Energy Release Component, Burning Index, Spread Component, and the Keetch–Byram Drought Index) and the Fosberg Fire Weather Index are used to characterise US fire danger. These fire danger indices and input meteorological variables, including temperature, relative humidity, precipitation...

  9. Statistical modelling of forest fire danger rating based on meteorological, topographical and fuel factors in the Republic of Korea

    NASA Astrophysics Data System (ADS)

    Won, M.; Yoon, S.; Jang, K.; Lim, J.

    2016-12-01

    Most of fires were human-caused fires in Korea, but meteorological factors are also big contributors to fire behavior and its spread. Thus, meteorological factors as well as social factors were considered in the fire danger rating systems. This study aims to develop an advanced Korean Forest Fire Danger Rating System (KFFDRS) using weather data of automatic mountain meteorology observation systems(AMOSs) to support forest fire prevention strategy in South Korea. The KFFDRS consists of three, 10-scale indices: daily weather index (DWI), fuel model index (FMI), and topography model index (TMI). DWI represents the meteorological characteristics, such as humidity (relative and effective), temperature and wind speed, and we integrated nine logistic regression models of the past into one national model. One integrated national model is [1+exp{2.706+(0.088×maximum temperature)-(0.055×relative humidity)-(0.023×effective humidity)-(0.104×mean wind speed)}-1]-1 and all weather variables significantly (p<0.01) affected the probability of forest fire occurrence in the overall regions. The predictive value of the model is 71.7 percent. Also we estimated accuracy of forest fire occurrences in case of pre or post-fusion of mountain weather data with 55 random sampling in forest fire event days. One integrated national model showed 10% high accuracy than nine logistic regression models when it is applied fused mountain weather data. These findings would be necessary for the policy makers in the Republic of Korea for the prevention of forest fires.

  10. Calibration and evaluation of the Canadian Forest Fire Weather Index (FWI) System for improved wildland fire danger rating in the United Kingdom

    NASA Astrophysics Data System (ADS)

    de Jong, Mark C.; Wooster, Martin J.; Kitchen, Karl; Manley, Cathy; Gazzard, Rob; McCall, Frank F.

    2016-05-01

    Wildfires in the United Kingdom (UK) pose a threat to people, infrastructure and the natural environment. During periods of particularly fire-prone weather, wildfires can occur simultaneously across large areas, placing considerable stress upon the resources of fire and rescue services. Fire danger rating systems (FDRSs) attempt to anticipate periods of heightened fire risk, primarily for early-warning and preparedness purposes. The UK FDRS, termed the Met Office Fire Severity Index (MOFSI), is based on the Fire Weather Index (FWI) component of the Canadian Forest FWI System. The MOFSI currently provides daily operational mapping of landscape fire danger across England and Wales using a simple thresholding of the final FWI component of the Canadian FWI System. However, it is known that the system has scope for improvement. Here we explore a climatology of the six FWI System components across the UK (i.e. extending to Scotland and Northern Ireland), calculated from daily 2km × 2km gridded numerical weather prediction data and supplemented by long-term meteorological station observations. We used this climatology to develop a percentile-based calibration of the FWI System, optimised for UK conditions. We find this approach to be well justified, as the values of the "raw" uncalibrated FWI components corresponding to a very "extreme" (99th percentile) fire danger situation vary by more than an order of magnitude across the country. Therefore, a simple thresholding of the uncalibrated component values (as is currently applied in the MOFSI) may incur large errors of omission and commission with respect to the identification of periods of significantly elevated fire danger. We evaluate our approach to enhancing UK fire danger rating using records of wildfire occurrence and find that the Fine Fuel Moisture Code (FFMC), Initial Spread Index (ISI) and FWI components of the FWI System

  11. Calibration and evaluation of the Canadian Forest Fire Weather Index (FWI) System for improved wildland fire danger rating in the UK

    NASA Astrophysics Data System (ADS)

    De Jong, M. C.; Wooster, M. J.; Kitchen, K.; Manley, C.; Gazzard, R.

    2015-11-01

    Wildfires in the United Kingdom (UK) can pose a threat to people, infrastructure and the natural environment (e.g. to the carbon in peat soils), and their simultaneous occurrence within and across UK regions can periodically place considerable stress upon the resources of Fire and Rescue Services. "Fire danger" rating systems (FDRS) attempt to anticipate periods of heightened fire risk, primarily for early-warning purposes. The UK FDRS, termed the Met Office Fire Severity Index (MOFSI) is based on the Fire Weather Index (FWI) component of the Canadian Forest FWI System. MOFSI currently provides operational mapping of landscape fire danger across England and Wales using a simple thresholding of the final FWI component of the Canadian System. Here we explore a climatology of the full set of FWI System components across the entire UK (i.e. extending to Scotland and Northern Ireland), calculated from daily 2 km gridded numerical weather prediction data, supplemented by meteorological station observations. We used this to develop a percentile-based calibration of the FWI System optimised for UK conditions. We find the calibration to be well justified, since for example the values of the "raw" uncalibrated FWI components corresponding to a very "extreme" (99th percentile) fire danger situation can vary by up to an order of magnitude across UK regions. Therefore, simple thresholding of the uncalibrated component values (as is currently applied) may be prone to large errors of omission and commission with respect to identifying periods of significantly elevated fire danger compared to "routine" variability. We evaluate our calibrated approach to UK fire danger rating against records of wildfire occurrence, and find that the Fine Fuel Moisture Code (FFMC), Initial Spread Index (ISI) and final FWI component of the FWI system generally have the greatest predictive skill for landscape fires in Great Britain, with performance varying seasonally and by land cover type. At the

  12. Relation between the National Fire Danger spread component and fire activity in the Lake States.

    Treesearch

    Donald A. Haines; William A. Main; Von J. Johnson

    1970-01-01

    Relationships between the 1964 version of the spread component of the National Fire Danger Rating System and fire activity were established for Michigan, Minnesota, and Wisconsin. The measures of fire activity included the probability of a fire-day as well as a C, D, or E fire-day, number of fires per fire-day, and acres burned per fire. These measures were examined by...

  13. USGS Fire Science: Fire Danger Monitoring and Forecasting

    USGS Publications Warehouse

    Eidenshink, Jeff

    2007-01-01

    The U.S. Geological Survey (USGS) has advanced the use of moderate-resolution satellite data in a decision support system for assessing national fire potential. Weekly updated digital images of the Normalized Difference Vegetation Index (NDVI), based on data acquired at 1-kilometer (km) resolution (about 0.6 mi), have been used for the past 19 years as a means to assess live vegetation conditions for the purpose of rating fire danger. These images, produced and monitored through the growing season, portray the approximate time of greenup and senescence, as well as the relative amount and condition of growing plants.

  14. Modeling topographic influences on fuel moisture and fire danger in complex terrain to improve wildland fire management decision support

    Treesearch

    Zachary A. Holden; W. Matt Jolly

    2011-01-01

    Fire danger rating systems commonly ignore fine scale, topographically-induced weather variations. These variations will likely create heterogeneous, landscape-scale fire danger conditions that have never been examined in detail. We modeled the evolution of fuel moistures and the Energy Release Component (ERC) from the US National Fire Danger Rating System across the...

  15. The potential predictability of fire danger provided by ECMWF forecast

    NASA Astrophysics Data System (ADS)

    Di Giuseppe, Francesca

    2017-04-01

    The European Forest Fire Information System (EFFIS), is currently being developed in the framework of the Copernicus Emergency Management Services to monitor and forecast fire danger in Europe. The system provides timely information to civil protection authorities in 38 nations across Europe and mostly concentrates on flagging regions which might be at high danger of spontaneous ignition due to persistent drought. The daily predictions of fire danger conditions are based on the US Forest Service National Fire Danger Rating System (NFDRS), the Canadian forest service Fire Weather Index Rating System (FWI) and the Australian McArthur (MARK-5) rating systems. Weather forcings are provided in real time by the European Centre for Medium range Weather Forecasts (ECMWF) forecasting system. The global system's potential predictability is assessed using re-analysis fields as weather forcings. The Global Fire Emissions Database (GFED4) provides 11 years of observed burned areas from satellite measurements and is used as a validation dataset. The fire indices implemented are good predictors to highlight dangerous conditions. High values are correlated with observed fire and low values correspond to non observed events. A more quantitative skill evaluation was performed using the Extremal Dependency Index which is a skill score specifically designed for rare events. It revealed that the three indices were more skilful on a global scale than the random forecast to detect large fires. The performance peaks in the boreal forests, in the Mediterranean, the Amazon rain-forests and southeast Asia. The skill-scores were then aggregated at country level to reveal which nations could potentiallty benefit from the system information in aid of decision making and fire control support. Overall we found that fire danger modelling based on weather forecasts, can provide reasonable predictability over large parts of the global landmass.

  16. Measurements of forest fire danger

    Treesearch

    Leo. Shames

    1938-01-01

    Although the annual destruction of life and property attributable to forest fires is enormous, scientific methods of forest fire control in the United States are of comparatively recent origin. In one important phase of control, that of determining how large a network of observers is necessary for the purpose of discovering forest fires in their infancy, accurate means...

  17. The principles of measuring forest fire danger

    Treesearch

    H. T. Gisborne

    1936-01-01

    Research in fire danger measurement was commenced in 1922 at the Northern Rocky Mountain Forest and Range Experiment Station of the U. S. Forest Service, with headquarters at Missoula, Mont. Since then investigations have been made concerning ( 1) what to measure, (2) how to measure, and ( 3) field use of these measurements. In all cases the laboratory or restricted...

  18. Localized enhancements in fire danger during the 'Black Saturday' fires

    NASA Astrophysics Data System (ADS)

    Lane, T. P.; Engel, C. B.; Reeder, M. J.

    2011-12-01

    On Saturday 7 February 2009 a series of fire complexes occurred over the state of Victoria, Australia. The fires caused more than 150 fatalities, the destruction of more than 2000 residences, and decimated a number of townships. The meteorological conditions on 7 February for the region were categorized as the worst fire weather conditions on record. Specifically, the maximum temperature exceeded 45 C (113 F) and gusty surface winds were sustained at 15 m/s (30 knots) for most of the day. These conditions were followed by the passage of a strong cold front in the late afternoon / early evening. Moreover, vegetation and fuels had suffered significant drying over the prior weeks due to a sequence of hot days and a record heatwave. In addition to these broad scale meteorological conditions, numerous mesoscale atmospheric processes contributed to localized enhancement in fire danger in the vicinity of many of the fires; these phenomena may have contributed to the extraordinary nature of some of the fires occurring that day. This study documents these localized processes using a combination of surface observations and an extremely high-resolution numerical weather prediction model with a horizontal resolution of 500 m. The observations and model forecast identify many notable phenomena of relevance to fire danger that persist throughout the day. These include enhanced down-slope surface winds and organized boundary layer horizontal convective rolls (HCRs). The HCRs are responsible for significant spatial variability in surface winds and forest fire danger index (FFDI). The model forecast elucidates the complex interaction between the cold front and the terrain, including the large variability in the timing and direction of the cool change. Finally, two nocturnal bores are identified that propagate ahead of the cool change; such bores have the potential to cause rapid, yet unexpected, changes to fire danger. In addition to documenting these important phenomena, the model

  19. [Prediction on the changes of forest fire danger rating in Great Xing'an Mountain region of Northeast China in the 21st century under effects of climate change].

    PubMed

    Yang, Guang; Shu, Li-Fu; Di, Xue-Ying

    2012-12-01

    Based on the A2a and B2a climatic scenarios for both the baseline period (1961-1990) and the future scenario periods (2010-2039, 2040-2069, and 2070-2099) from the Hadley Centre's General Circulation, and by using Delta method, WGEN downscaling methods, and Canadian Forest Fire Danger Rating System, this paper classified the forest fire dangers in Great Xing' an Mountains region of Heilongjiang Province, Northeast China, predicted the changes of the forest fire danger rating in the period 2010-2099 relative to baseline period (1961-1990), and analyzed the uncertainty of the long-term prediction of forest fire danger rating. It was predicted that under the background of climate warming, the mean annual days of extremely high, very high, and medium forest dangers in study region in the 21st century all showed an increasing trend, while the mean annual days of high and low forest dangers were in adverse. Relative to the baseline period of 1961-1990, the mean annual days of extremely high and very high forest dangers in the 2040-2069 and 2070-2099 under the scenarios of SRES A2a and B2a would be increased by 43 and 36, and 62 and 61, respectively.

  20. Wildland fire probabilities estimated from weather model-deduced monthly mean fire danger indices

    Treesearch

    Haiganoush K. Preisler; Shyh-Chin Chen; Francis Fujioka; John W. Benoit; Anthony L. Westerling

    2008-01-01

    The National Fire Danger Rating System indices deduced from a regional simulation weather model were used to estimate probabilities and numbers of large fire events on monthly and 1-degree grid scales. The weather model simulations and forecasts are ongoing experimental products from the Experimental Climate Prediction Center at the Scripps Institution of Oceanography...

  1. Forest fire danger in western Oregon and Washington during 1953.

    Treesearch

    Owen P. Cramer

    1953-01-01

    Following two successive fire seasons of record breaking severity, the 1953 season set new records for low fire danger in western Oregon and Washington. The low danger is reflected in the fire record—the U. S. Forest Service and forestry offices of both States all report the lowest acreage burned since fire records have been kept. A cool, wet spring, above...

  2. Estimation of fire danger in Hawai'i using limited weather data and simulation

    Treesearch

    D.R. Weise; S.L. Stephens; F.M. Fujioka; T.J. Moody; J. Benoit

    2010-01-01

    The presence of fire in Hawai'i has increased with introduction of nonnative grasses. Fire danger estimation using the National Fire Danger Rating System (NFDRS) typically requires 5 to 10 yr of data to determine percentile weather values and fire activity. The U.S. Army Pōhakuloa Training Area in Hawai‘i is located in the interface zone between windward...

  3. Using weather forecasts for predicting forest-fire danger

    Treesearch

    H. T. Gisborne

    1925-01-01

    Three kinds of weather control the fluctuations of forest-fire danger-wet weather, dry weather, and windy weather. Two other conditions also contribute to the fluctuation of fire danger. These are the occurrence of lightning and the activities of man. But neither of these fire-starting agencies is fully effective unless the weather has dried out the forest materials so...

  4. Evaluating wildland fire danger and prioritizing vegetation and fuels treatments

    Treesearch

    Paul F. Hessburg; Keith M. Reynolds; Robert E. Keane; Kevin M. James; R. Brion Salter

    2008-01-01

    We present a decision-support application that evaluates danger of severe wildland fire and prioritizes subwatersheds for vegetation and fuels treatment. We demonstrate the use of the system with an example from the Rocky Mountain region in Utah; a planning area of 4.8 million ha encompassing 575 subwatersheds. In a logic model, we evaluate fire danger as a function of...

  5. Fire danger assessment using ECMWF weather prediction system

    NASA Astrophysics Data System (ADS)

    Di Giuseppe, Francesca; Pappemberger, Florian; Wetterhall, Fredrik

    2015-04-01

    Weather plays a major role in the birth, growth and death of a wildfire wherever there is availability of combustible vegetation and suitable terrain topography. Prolonged dry periods creates favourable conditions for ignitions, wind can then increase the fire spread, while higher relative humidity, and precipitation (rain or snow) may decrease or extinguish it altogether. The European Forest Fire Information System (EFFIS), started in 2011 under the lead of the European Joint Research Centre (JRC) to monitor and forecast fire danger and fire behaviour in Europe. In 2012 a collaboration with the European Centre for Medium range Weather Forecast (ECMWF) was established to explore the potential of using state of the art weather forecast systems as driving forcing for the calculations of fire risk indices. From this collaboration in 2013 the EC-fire system was born. It implements the three most commonly used fire danger rating systems (NFDRS, FWI and MARK-5) and it is both initialised and forced by gridded atmospheric fields provided either by ECMWF re-analysis or ECMWF ensemble prediction systems. For consistency invariant fields (i.e fuel maps, vegetation cover, topogarphy) and real-time weather information are all provided on the same grid. Similarly global climatological vegetation stage conditions for each day of the year are provided by remote satellite observations. These climatological static maps substitute the traditional man judgement in an effort to create an automated procedure that can work in places where local observations are not available. The system has been in operation for the last year providing an ensemble of daily forecasts for fire indices with lead-times up to 10 days over Europe and Globally. An important part of the system is provided by its (re)-analysis dataset obtained by using the (re)-analysis forcings as drivers to calculate the fire risk indices. This is a crucial part of the whole chain since these fields are used to establish the

  6. Predicting moisture dynamics of fine understory fuels in a moist tropical rainforest system: results of a pilot study undertaken to identify proxy variables useful for rating fire danger.

    PubMed

    Ray, David; Nepstad, Dan; Brando, Paulo

    2010-08-01

    *The use of fire as a land management tool in the moist tropics often has the unintended consequence of degrading adjacent forest, particularly during severe droughts. Reliable models of fire danger are needed to help mitigate these impacts. *Here, we studied the moisture dynamics of fine understory fuels in the east-central Brazilian Amazon during the 2003 dry season. Drying stations established under varying amounts of canopy cover (leaf area index (LAI) = 0 - 5.3) were subjected to a range of water inputs (5-15 mm) and models were developed to forecast litter moisture content (LMC). Predictions were then compared with independent field data. *A multiple linear regression relating litter moisture content to forest structure (LAI), ambient vapor pressure deficit (VPD(M)) and an index of elapsed time since a precipitation event (d(-1)) was identified as the best-fit model (adjusted R(2) = 0.89). Relative to the independent observations, model predictions were relatively unbiased when the LMC was fire danger based on forest structure and meteorological variables is promising; however, additional information to the LAI, for example forest biomass, may be required to accurately capture the influence of forest structure on understory microclimate.

  7. Fire danger and fire behavior modeling systems in Australia, Europe, and North America

    Treesearch

    Francis M. Fujioka; A. Malcolm Gill; Domingos X. Viegas; B. Mike Wotton

    2009-01-01

    Wildland fire occurrence and behavior are complex phenomena involving essentially fuel (vegetation), topography, and weather. Fire managers around the world use a variety of systems to track and predict fire danger and fire behavior, at spatial scales that span from local to global extents, and temporal scales ranging from minutes to seasons. The fire management...

  8. Community Violent Crime Rates and School Danger.

    ERIC Educational Resources Information Center

    Bowen, Gary L.; Van Dorn, Richard A.

    2002-01-01

    This study investigated the association between community violent crime rates and middle school students' (N=857) perceptions of school danger. Findings indicate that community crime rates are associated with male middle school students' reports of school danger but not female students' reports. Discusses community- and school-based prevention…

  9. The relationship of large fire occurrence with drought and fire danger indices in the western USA, 1984-2008: The role of temporal scale

    Treesearch

    Karin L. Riley; John T. Abatzoglou; Isaac C. Grenfell; Anna E. Klene; Faith Ann Heinsch

    2013-01-01

    The relationship between large fire occurrence and drought has important implications for fire prediction under current and future climates. This study’s primary objective was to evaluate correlations between drought and fire-danger- rating indices representing short- and long-term drought, to determine which had the strongest relationships with large fire occurrence...

  10. Focused sun's rays and forest fire danger: new concept

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Geniy V.; Baranovskiy, Nikolay V.

    2013-10-01

    Estimation of forest fire danger has traditionally been based on historical fire weather climatology. This presentation describes a new concept for an improved estimation of forest fire danger, which takes into account the possibility of forest fuel ignition as a result of focused sun's light. For example, glass containers, their splinters and large drops of coniferous trees pitch can be a fire hazard due to their potential for focusing the sun's rays (under favorable conditions) and, consequently for setting forest fuel ablaze. Our analysis of numerous observational reports suggests that the forest fuel ignition process can be described by system of the non-stationary nonlinear equations of heat conductivity and diffusion with corresponding initial and boundary conditions. To solve these equations, we apply well-established numerical methods. This presentation includes model results and their comparison with available observational constrains together with suggestions for using remote sensing data.

  11. Recent Extreme Forest Fire Activity in Western Russia: Fire Danger Conditions, Fire Behavior and Smoke Transport

    NASA Astrophysics Data System (ADS)

    Stocks, B. J.; Fromm, M.; Goldammer, J.; Carr, R.; Sukhinin, A. I.

    2010-12-01

    During the summer of 2010, widespread forest and peatland fires in western Russia burned over hundreds of thousands of hectares, burning over croplands, destroying hundreds of homes, and directly causing the death of more than 50 people. Unprecedented drought conditions, combined with an extended heat wave, resulted in extreme fire danger conditions and explosive fire behavior in a region of Russia not noted for large fires. Several fires exhibited pyroconvection, injecting smoke directly into the upper troposphere and lower stratosphere, while deep-burning fires created major regional smoke problems. This smoke persisted in the heavily-populated areas around Moscow, exposing millions to high levels of ozone and particulate matter, and creating both immediate and longer-term health risks. This presentation will explore the drought conditions leading to the catastrophic fire behavior experienced in western Russia, and analyze fire behavior in terms of fuel consumption, smoke production, fire intensity levels, and pyroconvection. Impacts of regional and long-range smoke transport will also be discussed.

  12. Evaluating wildland fire danger and prioritizing vegetation and fuels treatments

    Treesearch

    Paul F. Hessburg; Keith M. Reynolds; Robert E. Keane; Kevin M. James; R. Brion Salter

    2010-01-01

    We present a prototype decision support system for evaluating wild-land fire danger and prioritizing subwatersheds for vegetation and fuels treatment. We demonstrate the use of the system with an example from the Rocky Mountain region in the State of Utah, which represents a planning area of about 4.8 million ha and encompasses 575 complete subwatersheds. In a logic...

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

    NASA Astrophysics Data System (ADS)

    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. Modeling Future Fire danger over North America in a Changing Climate

    NASA Astrophysics Data System (ADS)

    Jain, P.; Paimazumder, D.; Done, J.; Flannigan, M.

    2016-12-01

    Fire danger ratings are used to determine wildfire potential due to weather and climate factors. The Fire Weather Index (FWI), part of the Canadian Forest Fire Danger Rating System (CFFDRS), incorporates temperature, relative humidity, windspeed and precipitation to give a daily fire danger rating that is used by wildfire management agencies in an operational context. Studies using GCM output have shown that future wildfire danger will increase in a warming climate. However, these studies are somewhat limited by the coarse spatial resolution (typically 100-400km) and temporal resolution (typically 6-hourly to monthly) of the model output. Future wildfire potential over North America based on FWI is calculated using output from the Weather, Research and Forecasting (WRF) model, which is used to downscale future climate scenarios from the bias-corrected Community Climate System Model (CCSM) under RCP8.5 scenarios at a spatial resolution of 36km. We consider five eleven year time slices: 1990-2000, 2020-2030, 2030-2040, 2050-2060 and 2080-2090. The dynamically downscaled simulation improves determination of future extreme weather by improving both spatial and temporal resolution over most GCM models. To characterize extreme fire weather we calculate annual numbers of spread days (days for which FWI > 19) and annual 99th percentile of FWI. Additionally, an extreme value analysis based on the peaks-over-threshold method allows us to calculate the return values for extreme FWI values.

  15. Relationships between fire danger and the daily number and daily growth of active incidents burning in the northern Rocky Mountains, USA

    Treesearch

    Patrick H. Freeborn; Mark A. Cochrane; W. Matt. Jolly

    2015-01-01

    Daily National Fire Danger Rating System (NFDRS) indices are typically associated with the number and final size of newly discovered fires, or averaged over time and associated with the likelihood and total burned area of large fires. Herein we used a decade (2003-12) of NFDRS indices and US Forest Service (USFS) fire reports to examine daily relationships between fire...

  16. A new website with real-time dissemination of information on fire activity and meteorological fire danger in Portugal

    NASA Astrophysics Data System (ADS)

    DaCamara, Carlos; Trigo, Ricardo; Nunes, Sílvia; Pinto, Miguel; Oliveira, Tiago; Almeida, Rui

    2017-04-01

    In Portugal, like in Mediterranean Europe, fire activity is a natural phenomenon linking climate, humans and vegetation and is therefore conditioned by natural and anthropogenic factors. Natural factors include topography, vegetation cover and prevailing weather conditions whereas anthropogenic factors encompass land management practices and fire prevention policies. Land management practices, in particular the inadequate use of fire, is a crucial anthropogenic factor that accounts for about 90% of fire ignitions. Fire prevention policies require adequate and timely information about wildfire potential assessment, which is usually based on fire danger rating systems that provide indices to be used on an operational and tactical basis in decision support systems. We present a new website designed to provide the user community with relevant real-time information on fire activity and meteorological fire danger that will allow adopting the adequate measures to mitigate fire damage. The fire danger product consists of forecasts of fire danger over Portugal based on a statistical procedure that combines information about fire history derived from the Fire Radiative Power product disseminated by the Land Surface Analysis Satellite Application Facility (LSA SAF) with daily meteorological forecasts provided by the European Centre for Medium-Range Weather Forecasts (ECMWF). The aim of the website is fourfold; 1) to concentrate all information available (databases and maps) relevant to fire management in a unique platform so that access by end users becomes easier, faster and friendlier; 2) to supervise the access of users to the different products available; 3) to control and assist the access to the platform and obtain feedbacks from users for further improvements; 4) to outreach the operational community and foster the use of better information that increase efficiency in risk management. The website is sponsored by The Navigator Company, a leading force in the global pulp

  17. 33 CFR 334.350 - Chesapeake Bay off Fort Monroe, Va.; firing range danger zone.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... water area lying within a section extending seaward a distance of 4,600 yards between radial lines... be fired into the firing range danger zone. (2) During periods when firing is in progress, red...

  18. 33 CFR 334.350 - Chesapeake Bay off Fort Monroe, Va.; firing range danger zone.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... water area lying within a section extending seaward a distance of 4,600 yards between radial lines... be fired into the firing range danger zone. (2) During periods when firing is in progress, red...

  19. 33 CFR 334.350 - Chesapeake Bay off Fort Monroe, Va.; firing range danger zone.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... water area lying within a section extending seaward a distance of 4,600 yards between radial lines... be fired into the firing range danger zone. (2) During periods when firing is in progress, red...

  20. Pacific Ocean Sea Surface Temperatures and Their Relationship to North American Fire Danger and Drought Variability

    NASA Astrophysics Data System (ADS)

    Hall, B. L.; Brown, T. J.; Banta, J. R.

    2007-05-01

    In this study, gridded sea surface temperatures (SST) in the Pacific Ocean are analyzed in relation to monthly North American wildland fire danger and drought. Wildland fire danger is the sum of constant danger and variable danger factors affecting the inception, spread and resistance to control, and subsequent fire damage; often expressed as a relative number indicating the severity of wildland fire danger. Temperature, relative humidity and precipitation are integrated meteorological inputs for the computation of fire danger indices. The drought index used in this study is the Standardized Precipitation Index (SPI) based upon monthly precipitation totals. While it is known that SSTs can influence anomaly patterns of these meteorological elements, it is of interest to examine patterns and variability of fire danger and precipitation anomalies as related to SST patterns. These results provide direct benefit to fire agencies by identifying key regions of potential predictability and areas most likely to be impacted by ocean influence using a decision-support tool (fire danger) common in fire management. In the analysis, positive matrix factorization is used to relate monthly SST, fire danger computed from the 32-km North American Regional Reanalysis for the period 1980-2005, and SPI based upon the approximate 4-km monthly SPI dataset. The fire danger index used in the analysis is the energy release component (ERC) that is the computed total heat released per unit area within the flaming front at the head of an advancing fire, and is a heavily utilized index in fire management. While some studies have focused on and found SST relationships to fire occurrence and drought regionally, this analysis is unique in that 1) fire danger (ERC) spatial patterns are examined for the first time; and 2) drought is analyzed using gridded data as opposed to point-specific or climate division domains. Results of this study suggest several climate modes that indicate an inter

  1. 33 CFR 334.350 - Chesapeake Bay off Fort Monroe, Va.; firing range danger zone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Chesapeake Bay off Fort Monroe, Va.; firing range danger zone. 334.350 Section 334.350 Navigation and Navigable Waters CORPS OF....350 Chesapeake Bay off Fort Monroe, Va.; firing range danger zone. (a) The danger zone. All of the...

  2. 33 CFR 334.350 - Chesapeake Bay off Fort Monroe, Va.; firing range danger zone.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Chesapeake Bay off Fort Monroe, Va.; firing range danger zone. 334.350 Section 334.350 Navigation and Navigable Waters CORPS OF....350 Chesapeake Bay off Fort Monroe, Va.; firing range danger zone. (a) The danger zone. All of the...

  3. Spatio-Temporal Analysis of Forest Fire Risk and Danger Using LANDSAT Imagery

    PubMed Central

    Sağlam, Bülent; Bilgili, Ertuğrul; Durmaz, Bahar Dinç; Kadıoğulları, Ali İhsan; Küçük, Ömer

    2008-01-01

    Computing fire danger and fire risk on a spatio-temporal scale is of crucial importance in fire management planning, and in the simulation of fire growth and development across a landscape. However, due to the complex nature of forests, fire risk and danger potential maps are considered one of the most difficult thematic layers to build up. Remote sensing and digital terrain data have been introduced for efficient discrete classification of fire risk and fire danger potential. In this study, two time-series data of Landsat imagery were used for determining spatio-temporal change of fire risk and danger potential in Korudag forest planning unit in northwestern Turkey. The method comprised the following two steps: (1) creation of indices of the factors influencing fire risk and danger; (2) evaluation of spatio-temporal changes in fire risk and danger of given areas using remote sensing as a quick and inexpensive means and determining the pace of forest cover change. Fire risk and danger potential indices were based on species composition, stand crown closure, stand development stage, insolation, slope and, proximity of agricultural lands to forest and distance from settlement areas. Using the indices generated, fire risk and danger maps were produced for the years 1987 and 2000. Spatio-temporal analyses were then realized based on the maps produced. Results obtained from the study showed that the use of Landsat imagery provided a valuable characterization and mapping of vegetation structure and type with overall classification accuracy higher than 83%. PMID:27879918

  4. Focused sunlight factor of forest fire danger assessment using Web-GIS and RS technologies

    NASA Astrophysics Data System (ADS)

    Baranovskiy, Nikolay V.; Sherstnyov, Vladislav S.; Yankovich, Elena P.; Engel, Marina V.; Belov, Vladimir V.

    2016-08-01

    Timiryazevskiy forestry of Tomsk region (Siberia, Russia) is a study area elaborated in current research. Forest fire danger assessment is based on unique technology using probabilistic criterion, statistical data on forest fires, meteorological conditions, forest sites classification and remote sensing data. MODIS products are used for estimating some meteorological conditions and current forest fire situation. Geonformation technologies are used for geospatial analysis of forest fire danger situation on controlled forested territories. GIS-engine provides opportunities to construct electronic maps with different levels of forest fire probability and support raster layer for satellite remote sensing data on current forest fires. Web-interface is used for data loading on specific web-site and for forest fire danger data representation via World Wide Web. Special web-forms provide interface for choosing of relevant input data in order to process the forest fire danger data and assess the forest fire probability.

  5. Assessment of a Forest Fire Danger Index for Russia Using NOAA Information

    NASA Astrophysics Data System (ADS)

    Sukhinin, A. I.; McRae, D. J.; Ponomarev, E. I.

    2002-05-01

    To be efficient, modern forest fire managers require a reliable method for estimating fire danger. For large remote forested areas, such as found in Russia where a local weather station network does not exist, this can be a major problem. However, remote sensing can provide reasonable estimates of fire danger across Russia to allow for an understanding of the present fire situation. An algorithm has been developed that can assess current fire danger by inputting ambient weather conditions derived from remote sensing data obtained from NOAA series satellites. Necessary inputs for calculating fire danger, such as surface temperature, dew-point temperature, and precipitation, are obtained from AVHRR and TOVS satellites. By generating maps a concise picture can be presented of fire danger across Russia. Fire danger estimates made during the 1996-2000 fire season reveals close correlation between the Russian Nesterov Index (r ¯ 0.9) and the Canadian Forest Fire Weather Index System (r ¯ 0.8). In order to understand future fire-fighting resourcing needs, fire danger predictions for an advanced 7-day period can be made using meteorological forecasts of near surface pressure and air temperatures. The only problem with this type of forecasting is the absence of knowing exactly what precipitation will fall during the period. This is resolved using an interactive method that updates the forecasted fire danger map using current precipitation. One important application of this product for remote sensing will be the ability on burn scar areas to classify fire severity for predicting better carbon release over vast areas. This will require the development of fire behavior models that use components of the fire danger systems as a key independent variable.

  6. The Ofidia Project: a Retrospective Fire Danger Forecast Analysis in Mediterranean Environment

    NASA Astrophysics Data System (ADS)

    Sirca, C.; Bacciu, V. M.; Salis, M.; Mirto, L.; Fiore, S.; Aloisio, G.; Spano, D.

    2015-12-01

    OFIDIA (Operational FIre Danger preventIon plAtform) is a two-year project started in May 2013 funded by the European Territorial Cooperation Programme Greece Italy (2007 - 2013). The project aims to improve the operational capability of forecasting, preventing, and fighting forest wildfires, and enhance the cross-border cooperation for fire danger assessment. More specifically, OFIDIA aims at developing an operational fire danger prevention platform, with the ability for near real-time fire danger forecast and fire behaviour analysis in Apulia (Italy) and Epirus (Greece) regions to help forest fires services in the effective prevention and response to forecasted danger.One of the preliminary activities of the project was the evaluation of fire danger performances by analysing the relationship between the predicted daily fire danger and observed fire activity (number of fires and area burned). To achieve this task, fire activity and danger patterns were characterised and their relationships were investigated for the period 2000-2012. The Italian Forest Service (CFS, Corpo Forestale dello Stato) provided fire statistics at NUT03 level. The data were homogenized and uncertainties corrected, and then burned area and number of fires were analysed according to the main fire regime characteristics (seasonality, fire return interval, fire incidence, fire size distribution, etc). Then, three fire danger models (FFWI, FWI, and IFI) were selected and computed starting from the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model (MM5) forecast.Results showed a high inter- and intra-annual variability in fire activiy, also considering the different type of affected vegetation. As for other Mediterranean areas, a smaller number of large fires caused a high proportion of burned area. Furthermore, fire activity showed significant correlations with the outputs obtained by the applied models. High relationships were found between

  7. Assessment of a Forest-fire Danger Index for Russia Using Remote Sensing Information

    NASA Astrophysics Data System (ADS)

    Sukhinin, Anatoly; McRae, Douglas; Ji-Zhong, Jin; Dubrovskaya, Olga; Ponomarev, Eugene

    2010-05-01

    Intensive exploitation of Siberian forest resources requires to increase the level of their protection. In Russia, forests annually disturbed by fire make up about 6% of the total forest area, whereas they account for hundredth or even thousandth of percent in the West European countries and Canada. Devastating forest fires associated with long draughts have become very common over recent decades in some parts of Siberia and the Russian Far East. Fires burning under these conditions disturb hundreds of thousands hectares of forest lands. Forest fires impact essentially on different biogeocenosis and on ecological situation in region as well. Thus their detrimental effects, including economic damage, are hard to overestimate. Remote sensing data using is more perspective method for forests monitoring in Russia. Moreover satellite data is only available information for non-protected Russian boreal forests and tundra also. To be efficient, modern forest fire managers require a reliable method for estimating fire danger. For large remote forested areas, such as found in Russia where a dense network of local weather station needed to calculate fire danger does not exist, this can be a major problem. However, remote sensing using satellite data can provide reasonable estimates of fire danger across Russia to allow for an understanding of the current fire situation. An algorithm has been developed that can assess current fire danger by inputting ambient weather conditions derived from remote sensing data obtained from NOAA, TERRA-series satellites. Necessary inputs for calculating fire danger, such as surface temperature, dew-point temperature, and precipitation, are obtained from AVHRR, MODIS and ATOVS satellite data. By generating the final products as maps a concise picture can be presented of fire danger across Russia. In order to understand future fire suppression needs, fire danger predictions for an advanced 7-day period can be made using meteorological forecasts

  8. Where and when to measure forest fire danger

    Treesearch

    G. Lloyd. Hayes

    1944-01-01

    This article presents the results of a study to determine the place, time, and number of measurements that should be made to obtain dependable ratings of "average-bad" fire conditions without an excessive number of stations or observations. The author concludes that under the conditions prevailing in the Priest River Experimental Forest in northern Idaho a...

  9. A robust scientific workflow for assessing fire danger levels using open-source software

    NASA Astrophysics Data System (ADS)

    Vitolo, Claudia; Di Giuseppe, Francesca; Smith, Paul

    2017-04-01

    Modelling forest fires is theoretically and computationally challenging because it involves the use of a wide variety of information, in large volumes and affected by high uncertainties. In-situ observations of wildfire, for instance, are highly sparse and need to be complemented by remotely sensed data measuring biomass burning to achieve homogeneous coverage at global scale. Fire models use weather reanalysis products to measure energy release and rate of spread but can only assess the potential predictability of fire danger as the actual ignition is due to human behaviour and, therefore, very unpredictable. Lastly, fire forecasting systems rely on weather forecasts to extend the advance warning but are currently calibrated using fire danger thresholds that are defined at global scale and do not take into account the spatial variability of fuel availability. As a consequence, uncertainties sharply increase cascading from the observational to the modelling stage and they might be further inflated by non-reproducible analyses. Although uncertainties in observations will only decrease with technological advances over the next decades, the other uncertainties (i.e. generated during modelling and post-processing) can already be addressed by developing transparent and reproducible analysis workflows, even more if implemented within open-source initiatives. This is because reproducible workflows aim to streamline the processing task as they present ready-made solutions to handle and manipulate complex and heterogeneous datasets. Also, opening the code to the scrutiny of other experts increases the chances to implement more robust solutions and avoids duplication of efforts. In this work we present our contribution to the forest fire modelling community: an open-source tool called "caliver" for the calibration and verification of forest fire model results. This tool is developed in the R programming language and publicly available under an open license. We will present

  10. Impact of Climate Change on Fire Danger across the Western United States

    NASA Astrophysics Data System (ADS)

    Abatzoglou, J. T.; Kolden, C.; Brown, T. J.

    2009-12-01

    Over the past three decades, the size and number of number of large wildfires have dramatically increased across the western United States. Large wildfires across much of the West preferentially occur during periods of extreme fire danger associated with critically low fuel moistures and limited relative humidity recovery. Anecdotal and analytical evidence suggests that fire danger and fire behavior have been unprecedented in recent years, therein contributing to the significant increase in wildland fire acres burned in recent years. Although fire danger, as a juxtaposition of climate and meteorological conditions, represents only a single determinant of wildfires, mounting evidence suggests that observed changes in climate have played a contributing role in increasing wildfire’s prevalence across the West and its subsequent effects on ecosystems and human infrastructure, Here, the impact of projected climate change on fire danger is examined across the western U.S. Projected changes in fire danger are assessed through a multimodel approach that uses downscaled daily meteorological fields. For a middle of the road climate change scenario results suggests an advance in the onset of fire season and an increase in the frequency of extreme fire danger conditions, with strong intermodel confidence across much of the desert southwest and intermountain western U.S. In addition, the alignment of climate change with low-frequency climate variability is projected to increase the likelihood of seasons that incur prolonged widespread fire danger. Such chronic and west-wide synchronous heightened wildfire potential is likely to tax fire suppression resources and reduce their efficacy, therein resulting in increased large catastrophic wildfires. Given the high degree of confidence regarding projected changes in fire danger and the increasing potential for anthropogenic ignitions, proactive efforts to mitigate the negative impacts of large wildfires are needed by land

  11. Assessing the value of increased model resolution in forecasting fire danger

    Treesearch

    Jeanne Hoadley; Miriam Rorig; Ken Westrick; Larry Bradshaw; Sue Ferguson; Scott Goodrick; Paul Werth

    2003-01-01

    The fire season of 2000 was used as a case study to assess the value of increasing mesoscale model resolution for fire weather and fire danger forecasting. With a domain centered on Western Montana and Northern Idaho, MM5 simulations were run at 36, 12, and 4-km resolutions for a 30 day period at the height of the fire season. Verification analyses for meteorological...

  12. Relation of weather forecasts to the prediction of dangerous forest fire conditions

    Treesearch

    R. H. Weidman

    1923-01-01

    The purpose of predicting dangerous forest-fire conditions, of course, is to reduce the great cost and damage caused by forest fires. In the region of Montana and northern Idaho alone the average cost to the United States Forest Service of fire protection and suppression is over $1,000,000 a year. Although the causes of forest fires will gradually be reduced by...

  13. Anticipating the severity of the fire season in Northern Portugal using statistical models based on meteorological indices of fire danger

    NASA Astrophysics Data System (ADS)

    Nunes, Sílvia A.; DaCamara, Carlos C.; Turkman, Kamil F.; Ermida, Sofia L.; Calado, Teresa J.

    2017-04-01

    Like in other regions of Mediterranean Europe, climate and weather are major drivers of fire activity in Portugal. The aim of the present study is to assess the role played by meteorological factors on inter-annual variability of burned area over a region of Portugal characterized by large fire activity. Monthly cumulated values of burned area in August are obtained from the fire database of ICNF, the Portuguese authority for forests. The role of meteorological factors is characterized by means of Daily Severity Rating, DSR, an index of meteorological fire danger, which is derived from meteorological fields as obtained from ECMWF Interim Reanalysis. The study area is characterized by the predominance of forest, with high percentages of maritime pine and eucalyptus, two species with high flammability in summer. The time series of recorded burned area in August during 1980-2011 is highly correlated (correlation coefficient of 0.93) with the one for whole Portugal. First, a normal distribution model is fitted to the 32-year sample of decimal logarithms of monthly burned area. The model is improved by introducing two covariates:(1) the top-down meteorological factor (DSRtd) which consists of daily cumulated values of DSR since April 1 to July 31 and may be viewed as the cumulated stress on vegetation due to meteorological conditions during the pre-fire season; (2) the bottom-up factor (DSRbu) which consists of the square root of the mean of the squared daily deviations (restricted to days with positive departures of DSR from the corresponding long term mean) and may be viewed as the contribution of days characterized by extreme weather conditions favoring the onset and spreading of wildfires. Three different statistical models are then developed: the "climate anomaly" model, using DSRtd as covariate, the "weather anomaly", using DSRbu as covariate, and the "combined" model using both variables as covariates. These models are used to define background fire danger, fire

  14. Web-GIS platform for forest fire danger prediction in Ukraine: prospects of RS technologies

    NASA Astrophysics Data System (ADS)

    Baranovskiy, N. V.; Zharikova, M. V.

    2016-10-01

    There are many different statistical and empirical methods of forest fire danger use at present time. All systems have not physical basis. Last decade deterministic-probabilistic method is rapidly developed in Tomsk Polytechnic University. Forest sites classification is one way to estimate forest fire danger. We used this method in present work. Forest fire danger estimation depends on forest vegetation condition, forest fire retrospective, precipitation and air temperature. In fact, we use modified Nesterov Criterion. Lightning activity is under consideration as a high temperature source in present work. We use Web-GIS platform for program realization of this method. The program realization of the fire danger assessment system is the Web-oriented geoinformation system developed by the Django platform in the programming language Python. The GeoDjango framework was used for realization of cartographic functions. We suggest using of Terra/Aqua MODIS products for hot spot monitoring. Typical territory for forest fire danger estimation is Proletarskoe forestry of Kherson region (Ukraine).

  15. Forest fire danger indices under extreme meteorological conditions in a complex topography - the situation in the Bavarian Alps in autumn 2011

    NASA Astrophysics Data System (ADS)

    Schunk, C.; Wastl, C.; Leuchner, M.; Schuster, C.; Menzel, A.

    2012-04-01

    Temperature inversions in mountainous areas cause situations in which spatial forest fire danger distribution is quite different than under normal conditions. Due to this effect, fire danger can vary distinctively within a relatively small scale with much greater fire danger at higher than at lower elevations. This paper investigates such a peculiar situation in a case study in the Bavarian Alps and its representation by standard forest fire danger indices. A persistent high pressure system caused a major drought event and a pronounced temperature inversion in the northern part of the European Alps in autumn 2011. This drought, during which no precipitation at all was registered over more than a month in some locations, came at a time when normally the first snow would have been expected (November). In addition to the drought, the atmosphere was stratified very stable with cool, humid conditions in the lower and warmer, dryer conditions in the elevated regions. The result was a massive drying of fuels in higher elevations, which lead to a very high fire danger level and multiple fire occurrences in these areas (e.g. November 7th near Bayrischzell and November 20th near Fall). On the other hand, lower overall temperatures and nightly wetting due to dew and even rime occurred in the valleys, therefore fire danger remained moderate there. To assess the accuracy of fire danger rating indices in this situation, meteorological data and selected indices (Angstrom, M-68, Fine Fuel Moisture Code, Duff Moisture Code, hourly calculated FFMC) from two close-by stations at the valley floor (719m a.s.l.) and a south-facing mid-slope position (1260m a.s.l.) near Garmisch-Partenkirchen (Germany) were compared against the actual fire danger as apparent from expert observations, multiple fire occurrences and some fuel moisture measurements. The results revealed that during temperature inversion, differences in the daily cycle of meteorological parameters have a major influence on

  16. Measuring forest-fire danger in northern Idaho

    Treesearch

    H. T. Gisborne

    1928-01-01

    In most of the forest regions of the United States the fire problem is the greatest forest problem. Wasteful methods of logging and lumbering may result in the loss of a large proportion of the remaining forest growth, but the land will usually produce a new crop of timber without undue delay, unless fire occurs.

  17. Potential forest fire danger over Northern Eurasia: Changes during the 20th century

    NASA Astrophysics Data System (ADS)

    Sherstyukov, B. G.; Razuvaev, V. N.; Groisman, P. Y.; Knight, R. W.; Enloe, J. G.

    2004-12-01

    years. This study supports and justifies our previous findings based on a data set five-times smaller (Groisman et al. 2003) and is corroborated with available statistics of forest fires (Korovin and Zukkert 2003) and with observed changes in characteristics of the forest phenology (Lapenis et al. 2004). Scenarios of the possible future climatic change in Northern Eurasia (IPCC 2001) indicate that the changes will be most prominent in the region. The superposition of these scenarios with the present characteristics of the potential forest fire danger in the Eastern half of Northern Eurasia, show that forest fires themselves may be an important feedback mechanism affecting both the rate and magnitude of the continental climatic changes. An unfortunate corollary is a need to reassess the existing scenarios of future climatic change in Northern Eurasia. These scenarios should include accounting for interactions with the biosphere and its changes.

  18. Assessing Fuel Moisture With Satellite Imaging Radar for Improved Fire Danger Prediction in Boreal Alaska

    NASA Astrophysics Data System (ADS)

    Brown, J.; Bourgeau-Chavez, L. L.; Riordan, K.; Garwood, G.; Slawski, J.; Alden, S.; Cella, B.; Murphy, K.; Kwart, M.

    2005-12-01

    Wildfire is a common occurrence in boreal regions and Alaskan natural resource management agencies devote considerable resources to fire management and suppression. Currently these agencies rely on the Canadian Forest Fire Danger Rating System's Fire Weather Index (FWI) for the assessment of the potential for wildfire. FWI is based solely on point source weather data collected daily in a sparse network across the state of Alaska. There are problems with the current FWI system, particularly in the determination of the spring start up values and problems mid-summer within permafrost regions. Melting permafrost causes increased moisture not accounted for in the weather-based system. The drought code (DC), which is an estimate of moisture in the deep compact duff layers, is the most affected by the default start up values because it has a 52 day lag period. Research has been conducted to improve the prediction of wildfire potential in Alaska using satellite c-band (5.3 cm wavelength) imaging radar. Imaging radar is sensitive to the moisture content of the features being imaged including vegetation and soils. We have been investigating the relationship between in situ soil moisture, c-band backscatter and fire danger codes for several years at a variety of burned and unburned sites in interior Alaska. Focus has been on recently burned (0-7 years) boreal forests because they allow moisture in the ground layer to be measured directly from a satellite sensor without interference of the forest canopy, and because they are a common feature across the Alaskan landscape. Studies of unburned forests adjacent to burned forests have revealed similarities in the temporal patterns of in situ moisture monitored throughout a fire season. Our research has resulted in the development of algorithms to predict DC from c-band backscatter. This will improve current weather-based estimates by providing a means for calibration of the DC throughout the season, and add additional point

  19. Geoinformation system for prediction of forest fire danger caused by solar radiation using remote sensing data

    NASA Astrophysics Data System (ADS)

    Baranovskiy, Nikolay V.; Yankovich, Elena P.

    2015-10-01

    This article reviews the project of subsystem that reflects the Earth remote sensing data from the space in order to monitor the forest fire danger, caused by the focused solar radiation effect. This subsystem is based on the use of sensing data from the MODIS instrument aboard the Terra satellite. We consider the Timiryazevsky Forestry of Tomsk region to be a typical territory of the boreal forest zone. To estimate the forest fire danger level, we use an original method to classify the forest areas according to their characteristics (the ground mensuration data) and the main meteorological parameters, namely, the cloud cover on this territory, obtained from the MODIS satellite data.

  20. Joint processing of RS and WWLLN data for forest fire danger estimation: new concept

    NASA Astrophysics Data System (ADS)

    Baranovskiy, Nikolay V.; Krechetova, Svetlana Yu.; Belikova, Marina Yu.; Kocheeva, Nina A.; Yankovich, Elena P.

    2016-10-01

    The present article describes a new concept of lightning-caused forest fire danger using a probabilistic criterion. The assessment of forest fire danger is made on the basis of the algorithm that classifies the forest territory by vegetation conditions. Lightning activity is processed by the MODIS spectroradiometer according to the World Wide Lightning Location Network data and remote sensing data for the Timiryazevskiy forestry in the Tomsk Region. The cluster analysis of the WWLLN and MOD06_L2 product data are used in the present paper.

  1. Linking Fuel Inventories With Atmospheric Data for Assessment of Fire Danger

    Treesearch

    Christopher W. Woodall; Joseph Charney; Greg Liknes; Brian Potter

    2006-01-01

    Combining forest fuel maps and real-time atmospheric data may enable creation of more dynamic and comprehensive fire danger assessments. The goal of this study was to combine fuel maps, based on data from the Forest Inventory and Analysis (FIA) program of the U.S. Department of Agriculture Forest Service, with real-time atmospheric data to create a more dynamic index...

  2. Differences in fire danger with altitude, aspect, and time of day

    Treesearch

    G. L. Hayes

    1942-01-01

    The measurement of fire danger has progressed remarkably since the early days of measuring humidity alone, or humidity and wind, or humidity, wind, and rain at a few valley bottom stations scattered widely apart over a forest of a million acres or more. Measuring the moisture content of the fuels directly is now known to be more accurate than measuring humidity and...

  3. Predicting the formation and the dispersion of toxic combustion products from the fires of dangerous substances

    NASA Astrophysics Data System (ADS)

    Nevrlý, V.; Bitala, P.; Danihelka, P.; Dobeš, P.; Dlabka, J.; Hejzlar, T.; Baudišová, B.; Míček, D.; Zelinger, Z.

    2012-04-01

    Natural events, such as wildfires, lightning or earthquakes represent a frequent trigger of industrial fires involving dangerous substances. Dispersion of smoke plume from such fires and the effects of toxic combustion products are one of the reference scenarios expected in the framework of major accident prevention. Nowadays, tools for impact assessment of these events are rather missing. Detailed knowledge of burning material composition, atmospheric conditions, and other factors are required in order to describe quantitatively the source term of toxic fire products and to evaluate the parameters of smoke plume. Nevertheless, an assessment of toxic emissions from large scale fires involves a high degree of uncertainty, because of the complex character of physical and chemical processes in the harsh environment of uncontrolled flame. Among the others, soot particle formation can be mentioned as still being one of the unresolved problems in combustion chemistry, as well as decomposition pathways of chemical substances. Therefore, simplified approach for estimating the emission factors from outdoor fires of dangerous chemicals, utilizable for major accident prevention and preparedness, was developed and the case study illustrating the application of the proposed method was performed. ALOFT-FT software tool based on large eddy simulation of buoyant fire plumes was employed for predicting the local toxic contamination in the down-wind vicinity of the fire. The database of model input parameters can be effectively modified enabling the simulation of the smoke plume from pool fires or jet fires of arbitrary flammable (or combustible) gas, liquid or solid. This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic via the project LD11012 (in the frame of the COST CM0901 Action) and the Ministry of Environment of the Czech Republic (project no. SPII 1a10 45/70).

  4. United States Geological Survey fire science: fire danger monitoring and forecasting

    USGS Publications Warehouse

    Eidenshink, Jeff C.; Howard, Stephen M.

    2012-01-01

    Each day, the U.S. Geological Survey produces 7-day forecasts for all Federal lands of the distributions of number of ignitions, number of fires above a given size, and conditional probabilities of fires growing larger than a specified size. The large fire probability map is an estimate of the likelihood that ignitions will become large fires. The large fire forecast map is a probability estimate of the number of fires on federal lands exceeding 100 acres in the forthcoming week. The ignition forecast map is a probability estimate of the number of fires on Federal land greater than 1 acre in the forthcoming week. The extreme event forecast is the probability estimate of the number of fires on Federal land that may exceed 5,000 acres in the forthcoming week.

  5. Daily estimates of fire danger using multitemporal satellite MODIS data: the experience of FIRE-SAT in the Basilicata Region (Italy)

    NASA Astrophysics Data System (ADS)

    Lanorte, R.; Lasaponara, R.; De Santis, F.; Aromando, A.; Nole, G.

    2012-04-01

    Daily estimates of fire danger using multitemporal satellite MODIS data: the experience of FIRE-SAT in the Basilicata Region (Italy) A. Lanorte, F. De Santis , A. Aromando, G. Nolè, R. Lasaponara, CNR-IMAA, Potenza, Italy In the recent years the Basilicata Region (Southern Italy) has been characterized by an increasing incidence of fire disturbance which also tends to affect protected (Regional and national parks) and natural vegetated areas. FIRE_SAT project has been funded by the Civil Protection of the Basilicata Region in order to set up a low cost methodology for fire danger/risk monitoring based on satellite Earth Observation techniques. To this aim, NASA Moderate Resolution Imaging Spectroradiometer (MODIS) data were used. The spectral capability and daily availability makes MODIS products especially suitable for estimating the variations of fuel characteristics. This work presents new significant results obtained in the context of FIRE-SAT project. In order to obtain a dynamical indicator of fire susceptibility based on multitemporal MODIS satellite data, up-datable in short-time periods (daily), we used the spatial/temporal variations of following parameters: (1) Relative Greenness Index (2) Live and dead fuel moisture content (3) Temperature In particular, the dead fuel moisture content is a key factor in fire ignition. Dead fuel moisture dynamics are significantly faster than those observed for live fuel. Dead fine vegetation exhibits moisture and density values dependent on rapid atmospheric changes and strictly linked to local meteorological conditions. For this reason, commonly, the estimation of dead fuel moisture content is based on meteorological variables. In this study we propose to use MODIS data to estimate meteorological data (specifically Relative Humidity) at an adequate spatial and temporal resolution. The assessment of dead fuel moisture content plays a decisive role in determining a fire dynamic danger index in combination with other

  6. What's the fire danger now? Linking fuel inventories with atmospheric data

    Treesearch

    Christopher W. Woodall; Joseph J. Charney; Greg C. Liknes; Brian E. Potter

    2005-01-01

    The combination of forest fuel maps with real-time atmospheric data may enable the creation of more dynamic and comprehensive assessments of fire danger. The goal of this study was to combine fuel maps, based on data from the Forest Inventory and Analysis (FIA) program of the USDA Forest Service, with real-time atmospheric data for the creation of a more dynamic index...

  7. Future projections of fire danger in Brazilian biomes in the 21st century

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    In the global context, Brazil is one of the regions more severely affected by fire occurrences, with important consequences in the global CO2 balance, the state of the Amazon forest and the ecological diversity of the region. Brazil is also one of the few regions experiencing a raise in annual mean temperature above 2.5o during the 20th century, which may further increase between 2o and 7o until 2100 and, likely, be accompanied by a decrease in precipitation [1]. As the fire occurrence and severity largely depends on these two variables, it is worth assessing the evolution of fire danger for the coming decades. In order to obtain a detailed characterization of the future fire patterns in the different biomes of Brazil, we use outputs from a regional-downscaling of the EC-Earth climate model at 0.44 degrees spatial resolution for two future scenarios, an intermediate (RCP4.5) and a more severe (RCP8.5) one. We use a fire danger index specifically developed for the Brazilian climate and biome characteristics, the IFR from INPE. This index relies on values of maximum temperature, accumulated precipitation over different periods, minimum relative humidity and vegetation cover to estimate the likelihood of fire occurrence. We find a systematic increase of the days with critical fire risk, which is more pronounced in RCP8.5 and mostly affects months when fire activity takes place. Temperature increase is the most determinant factor for the increase in fire danger in the dry regions of savannah and shrubland, a result to be expected as fuel is already very dry. [1] Collins, M., R. Knutti, J. Arblaster, J.-L. Dufresne, T. Fichefet, P. Friedlingstein, X. Gao, W.J. Gutowski, T. Johns, G. Krinner, M. Shongwe, C. Tebaldi, A.J. Weaver and M. Wehner, 2013: Long-term Climate Change: Projections, Commitments and Irreversibility. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on

  8. Potential forest fire danger over Northern Eurasia: Changes during the 20th century

    NASA Astrophysics Data System (ADS)

    Groisman, Pavel Ya.; Sherstyukov, Boris G.; Razuvaev, Vyacheslav N.; Knight, Richard W.; Enloe, Jesse G.; Stroumentova, Nina S.; Whitfield, Paul H.; Førland, Eirik; Hannsen-Bauer, Inger; Tuomenvirta, Heikki; Aleksandersson, Hans; Mescherskaya, Anna V.; Karl, Thomas R.

    2007-04-01

    Significant climatic changes over Northern Eurasia during the 20th century have been reflected in numerous variables of economic, social, and ecological interest, including the natural frequency of forest fires. For the former USSR, we are now using the Global Daily Climatology Network and a new Global Synoptic Data Network archive, GSDN, created jointly by U.S. National Climatic Data Center and Russian Research Institute for Hydrometeorological Information. Data from these archives (approximately 1500 of them having sufficiently long meteorological time series suitable for participation in our analyses) are employed to estimate systematic changes in indices used in the United States and Russia to assess potential forest fire danger. We use four indices: (1) Keetch-Byram Drought Index, (KBDI; this index was developed and widely used in the United States); (2) Nesterov, (3) Modified Nesterov, and (4) Zhdanko Indices (these indices were developed and widely used in Russia). Analyses show that after calibration, time series of the days with increased potential forest fire danger constructed using each of these three indices (a) are well correlated and (b) deliver similar conclusions about systematic changes in the weather conditions conducive to forest fires. Specifically, over the Eastern half of Northern Eurasia (Siberia and the Russian Far East) statistically significant increases in indices that characterize the weather conditions conducive to forest fires were found. These areas coincide with the areas of most significant warming during the past several decades south of the Arctic Circle. West of the Ural Mountains, the same indices show a steady decrease in the frequency of "dry weather summer days" during the past 60 yr. This study is corroborated with available statistics of forest fires and with observed changes in drought statistics in agricultural regions of Northern Eurasia.

  9. Influence of slope on fire spread rate

    Treesearch

    B.W. Butler; W.R. Anderson; E.A. Catchpole

    2007-01-01

    Data demonstrate the effect of slope on heading and backing fires burning through woody fuels. The data indicate that the upper limit of heading fire rate of spread is defined by the rate of spread up a vertical fuel array, and the lower limit is defined by the rate of spread of a backing fire burning downslope. The minimum spread rate is found to occur at nominally --...

  10. Simulating spatial and temporally related fire weather

    Treesearch

    Isaac C. Grenfell; Mark Finney; Matt Jolly

    2010-01-01

    Use of fire behavior models has assumed an increasingly important role for managers of wildfire incidents to make strategic decisions. For fire risk assessments and danger rating at very large spatial scales, these models depend on fire weather variables or fire danger indices. Here, we describe a method to simulate fire weather at a national scale that captures the...

  11. Estimating live fuel status by drought indices: an approach for assessing local impact of climate change on fire danger

    NASA Astrophysics Data System (ADS)

    Pellizzaro, Grazia; Dubrovsky, Martin; Bortolu, Sara; Ventura, Andrea; Arca, Bachisio; Masia, Pierpaolo; Duce, Pierpaolo

    2014-05-01

    Mediterranean shrubs are an important component of both Mediterranean vegetation communities and understorey vegetation. They also constitute the surface fuels primarily responsible for the ignition and the spread of wildland fires in Mediterranean forests. Although fire spread and behaviour are dependent on several factors, the water content of live fuel plays an important role in determining fire occurrence and spread, especially in the Mediterranean shrubland, where live fuel is often the main component of the available fuel which catches fire. According to projections on future climate, an increase in risk of summer droughts is likely to take place in Southern Europe. More prolonged drought seasons induced by climatic changes are likely to influence general flammability characteristics of fuel, affecting load distribution in vegetation strata, floristic composition, and live and dead fuel ratio. In addition, variations in precipitation and mean temperature could directly affect fuel water status, and consequently flammability, and length of critical periods of high ignition danger for Mediterranean ecosystems. The main aim of this work was to propose a methodology for evaluating possible impacts of future climate change on moisture dynamic and length of fire danger period at local scale. Specific objectives were: i) evaluating performances of meteorological drought indices in describing seasonal pattern of live fuel moisture content (LFMC), and ii) simulating the potential impacts of future climate changes on the duration of fire danger period. Measurements of LFMC seasonal pattern of three Mediterranean shrub species were performed in North Western Sardinia (Italy) for 8 years. Seasonal patterns of LFMC were compared with the Drought Code of the Canadian Forest Fire Weather Index and the Keetch-Byram Drought Index. Analysis of frequency distribution and cumulative distribution curves were carried out in order to evaluate performance of codes and to identify

  12. FireFamily Plus user's guide, Version 2.0

    Treesearch

    Larry Bradshaw; Erin McCormick

    2000-01-01

    FireFamily Plus is the new software for summarizing and analyzing daily weather observations and computing fire danger indexes based on the National Fire Danger Rating System (NFDRS). While the software and packaging are new, many of the reports are not. FireFamily Plus addressed the year 2000 issues that confronted a litany of DOS programs that operated against fire...

  13. Simulating the Effects of Fire on Forests in the Russian Far East: Integrating a Fire Danger Model and the FAREAST Forest Growth Model Across a Complex Landscape

    NASA Astrophysics Data System (ADS)

    Sherman, N. J.; Loboda, T.; Sun, G.; Shugart, H. H.; Csiszar, I.

    2008-12-01

    The remaining natural habitat of the critically endangered Amur tiger (Panthera tigris altaica) and Amur leopard (Panthera pardus orientalis) is a vast, biologically and topographically diverse area in the Russian Far East (RFE). Although wildland fire is a natural component of ecosystem functioning in the RFE, severe or repeated fires frequently re-set the process of forest succession, which may take centuries to return the affected forests to the pre-fire state and thus significantly alters habitat quality and long-term availability. The frequency of severe fire events has increased over the last 25 years, leading to irreversible modifications of some parts of the species' habitats. Moreover, fire regimes are expected to continue to change toward more frequent and severe events under the influence of climate change. Here we present an approach to developing capabilities for a comprehensive assessment of potential Amur tiger and leopard habitat availability throughout the 21st century by integrating regionally parameterized fire danger and forest growth models. The FAREAST model is an individual, gap-based model that simulates forest growth in a single location and demonstrates temporally explicit forest succession leading to mature forests. Including spatially explicit information on probabilities of fire occurrence at 1 km resolution developed from the regionally specific remotely -sensed data-driven fire danger model improves our ability to provide realistic long-term projections of potential forest composition in the RFE. This work presents the first attempt to merge the FAREAST model with a fire disturbance model, to validate its outputs across a large region, and to compare it to remotely-sensed data products as well as in situ assessments of forest structure. We ran the FAREAST model at 1,000 randomly selected points within forested areas in the RFE. At each point, the model was calibrated for temperature, precipitation, slope, elevation, and fire

  14. Civilian residential fire fatality rates: Six high-rate states versus six low-rate states

    NASA Astrophysics Data System (ADS)

    Hall, J. R., Jr.; Helzer, S. G.

    1983-08-01

    Results of an analysis of 1,600 fire fatalities occurring in six states with high fire-death rates and six states with low fire-death rates are presented. Reasons for the differences in rates are explored, with special attention to victim age, sex, race, and condition at time of ignition. Fire cause patterns are touched on only lightly but are addressed more extensively in the companion piece to this report, "Rural and Non-Rural Civilian Residential Fire Fatalities in Twelve States', NBSIR 82-2519.

  15. Remote Sensing and GIS Based Risk Index Map For Predicting Forest Fire Danger - Evaluation From Forestry Datasets, India

    NASA Astrophysics Data System (ADS)

    Prasad, V. K.; Badarinath, K. V. S.

    Forest fires constitute one of the most serious ecological as well as environmental problems affecting most vegetation zones across the world, including India. In this study, we evaluated forest fire risk for sixteen different forest and vegetation types of India. Data from Normalized Difference Vegetation Index (NDVI) from NOAA AVHRR data has been integrated with bioclimatic data and fuel value index to quantify the forest fire risk. Biomass data for different forest types in different pools has been used as ancillary data. In using the fuel value index, calorific value of wood content for 60 species has been collected and aggregated, for specific species. Results from NDVI and precipitation correlations were found to be highly significant for tropical dry deciduous and moist deciduous forests. Spatial patterns in NDVI closely followed seasonal trends in precipitation for most of the forests. An integrated GIS framework with biophysical, biomass, thermo chemical and bioclimatic parameters allowed the calculation of risk indices for the different forest types. The methodology followed in the study and the maps produced are found to be useful for evaluating forest fire risk and for predicting forest fire danger in different vegetation zones in India.

  16. Performance assessment of fire-sat monitoring system based on satellite time series for fire danger estimation : the experience of the pre-operative application in the Basilicata Region (Italy)

    NASA Astrophysics Data System (ADS)

    Lanorte, Antonio; Desantis, Fortunato; Aromando, Angelo; Lasaponara, Rosa

    2013-04-01

    This paper presents the results we obtained in the context of the FIRE-SAT project during the 2012 operative application of the satellite based tools for fire monitoring. FIRE_SAT project has been funded by the Civil Protection of the Basilicata Region in order to set up a low cost methodology for fire danger monitoring and fire effect estimation based on satellite Earth Observation techniques. To this aim, NASA Moderate Resolution Imaging Spectroradiometer (MODIS), ASTER, Landsat TM data were used. Novel data processing techniques have been developed by researchers of the ARGON Laboratory of the CNR-IMAA for the operative monitoring of fire. In this paper we only focus on the danger estimation model which has been fruitfully used since 2008 to 2012 as an reliable operative tool to support and optimize fire fighting strategies from the alert to the management of resources including fire attacks. The daily updating of fire danger is carried out using satellite MODIS images selected for their spectral capability and availability free of charge from NASA web site. This makes these data sets very suitable for an effective systematic (daily) and sustainable low-cost monitoring of large areas. The preoperative use of the integrated model, pointed out that the system properly monitor spatial and temporal variations of fire susceptibility and provide useful information of both fire severity and post fire regeneration capability.

  17. National fire danger assessment and ecosystem restoration using remote sensing and ecological modeling

    NASA Astrophysics Data System (ADS)

    Zhu, Z.; Rollins, M.

    Hazardous fuel reduction, ecosystem rehabilitation and restoration, and firefighting safety, are land management priorities emphasized by recent national fire policies such as the National Fire Plan. Implementation of these policies requires geospatial data of vegetation conditions, fire fuels, risks, and ecosystem status developed consistently nationwide that can be used at multiple scales (i.e., local, regional, and national). A new research and development project called LANDFIRE is being conducted to develop an integrated methodology to produce geospatial fire data and predictive models for the land management community and a broad range of other applications. Main deliverables include mapped potential and existing vegetation types and vegetation structure parameters, various biophysical data layers, fire fuels models, fire risk layers, as well as state-of-the-art computer models for assessing fire risk, behavior and effects. In this presentation, we will review research results and findings of the LANDFIRE project using results from a prototype study covering central Utah Uinta and Wasatch ecosystems. Particularly we will describe how a consistent and operational vegetation mapping component may be achieved by integrating machine-learning algorithms, field reference data, satellite imagery, and ecologically significant biophysical variables. We will discuss how remotely sensed vegetation cover types and structure can be successfully converted to fire fuel classes and risk layers which are necessary input into fire behavior and fire effect models. Finally we will discuss challenges and opportunities for national implementation of the methodology.

  18. Burning rates of wood cribs with implications for wildland fires

    Treesearch

    Sara McAllister; Mark Finney

    2016-01-01

    Wood cribs are often used as ignition sources for room fire tests and the well characterized burning rates may also have applications to wildland fires. The burning rate of wildland fuel structures, whether the needle layer on the ground or trees and shrubs themselves, is not addressed in any operational fire model and no simple model exists. Several relations...

  19. Comparative ratings of 1951 forest fire weather in western Oregon.

    Treesearch

    Owen P. Cramer; Robert. Kirkpatrick

    1951-01-01

    The 1951 forest fire weather in western Oregon is generally conceded to have been unusually severe. In order to compare this season with others, this report uses a scheme for rating fire seasons recently developed by the Fire Research section of the Experiment Station, The rating is based on indices of three weather characteristics which generally control burning...

  20. Test of wind predictions for peak fire-danger stations in Oregon and Washington.

    Treesearch

    Owen P. Cramer

    1957-01-01

    Relative accuracy of several wind-speed forecasting methods was tested during the forest fire seasons of 1950 and 1951. For the study, three fire-weather forecast centers of the U. S. Weather Bureau prepared individual station forecasts for 11 peak stations within the national. forests of Oregon and Washington. These spot forecasts were considered...

  1. Firing rate of noisy integrate-and-fire neurons with synaptic current dynamics

    SciTech Connect

    Andrieux, David; Monnai, Takaaki

    2009-08-15

    We derive analytical formulas for the firing rate of integrate-and-fire neurons endowed with realistic synaptic dynamics. In particular, we include the possibility of multiple synaptic inputs as well as the effect of an absolute refractory period into the description. The latter affects the firing rate through its interaction with the synaptic dynamics.

  2. Comparison of methods for estimating motor unit firing rate time series from firing times.

    PubMed

    Liu, Lukai; Bonato, Paolo; Clancy, Edward A

    2016-12-01

    The central nervous system regulates recruitment and firing of motor units to modulate muscle tension. Estimation of the firing rate time series is typically performed by decomposing the electromyogram (EMG) into its constituent firing times, then lowpass filtering a constituent train of impulses. Little research has examined the performance of different estimation methods, particularly in the inevitable presence of decomposition errors. The study of electrocardiogram (ECG) and electroneurogram (ENG) firing rate time series presents a similar problem, and has applied novel simulation models and firing rate estimators. Herein, we adapted an ENG/ECG simulation model to generate realistic EMG firing times derived from known rates, and assessed various firing rate time series estimation methods. ENG/ECG-inspired rate estimation worked exceptionally well when EMG decomposition errors were absent, but degraded unacceptably with decomposition error rates of ⩾1%. Typical EMG decomposition error rates-even after expert manual review-are 3-5%. At realistic decomposition error rates, more traditional EMG smoothing approaches performed best, when optimal smoothing window durations were selected. This optimal window was often longer than the 400ms duration that is commonly used in the literature. The optimal duration decreased as the modulation frequency of firing rate increased, average firing rate increased and decomposition errors decreased. Examples of these rate estimation methods on physiologic data are also provided, demonstrating their influence on measures computed from the firing rate estimate. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. [Change trends of summer fire danger in great Xing' an Mountains forest region of Heilongjiang Province, Northeast China under climate change].

    PubMed

    Yang, Guang; Shu, Li-Fu; Di, Xue-Ying

    2012-11-01

    By using Delta and WGEN downscaling methods and Canadian Forest Fire Weather Index, this paper analyzed the variation characteristics of summer fire in Great Xing' an Mountains forest region of Heilongjiang Province in 1966-2010, estimated the change trends of the summer fire danger in 2010-2099, compared the differences of the forest fire in summer, spring, and autumn, and proposed the prevention and control strategies of the summer fire based on the fire environment. Under the background of climate warming, the summer forest fire in the region in 2000-2010 showed a high incidence trend. In foreseeable future, the summer forest fire across the region in 2010-2099, as compared to that in the baseline period 1961-1990, would be increased by 34%, and the increment would be obviously greater than that of spring and autumn fire. Relative to that in 1961-1990, the summer fire in 2010-2099 under both SRES A2a and SRES B2a scenarios would have an increasing trend, and, with the lapse of time, the trend would be more evident, and the area with high summer fire would become wider and wider. Under the scenario of SRES A2a, the summer fire by the end of the 21st century would be doubled, as compared to that in 1961-1990, and the area with high summer fire would be across the region. In the characteristics of fire source, attributes of forest fuel, and fire weather conditions, the summer forest fire was different from the spring and autumn forest fire, and thus, the management of fire source and forest fuel load as well as the forest fire forecast (mid-long term forecast in particular) in the region should be strengthened to control the summer forest fire.

  4. Using fire-weather forecasts and local weather observations in predicting burning index for individual fire-danger stations.

    Treesearch

    Owen P. Cramer

    1958-01-01

    Any agency engaged in forest-fire control needs accurate weather forecasts and systematic procedures for making the best use of predicted and reported weather information. This study explores the practicability of using several tabular and graphical aids for converting area forecasts and local observations of relative humidity and wind speed into predicted values for...

  5. When do correlations increase with firing rates in recurrent networks?

    PubMed Central

    2017-01-01

    A central question in neuroscience is to understand how noisy firing patterns are used to transmit information. Because neural spiking is noisy, spiking patterns are often quantified via pairwise correlations, or the probability that two cells will spike coincidentally, above and beyond their baseline firing rate. One observation frequently made in experiments, is that correlations can increase systematically with firing rate. Theoretical studies have determined that stimulus-dependent correlations that increase with firing rate can have beneficial effects on information coding; however, we still have an incomplete understanding of what circuit mechanisms do, or do not, produce this correlation-firing rate relationship. Here, we studied the relationship between pairwise correlations and firing rates in recurrently coupled excitatory-inhibitory spiking networks with conductance-based synapses. We found that with stronger excitatory coupling, a positive relationship emerged between pairwise correlations and firing rates. To explain these findings, we used linear response theory to predict the full correlation matrix and to decompose correlations in terms of graph motifs. We then used this decomposition to explain why covariation of correlations with firing rate—a relationship previously explained in feedforward networks driven by correlated input—emerges in some recurrent networks but not in others. Furthermore, when correlations covary with firing rate, this relationship is reflected in low-rank structure in the correlation matrix. PMID:28448499

  6. Estimating fire behavior with FIRECAST: user's manual

    Treesearch

    Jack D. Cohen

    1986-01-01

    FIRECAST is a computer program that estimates fire behavior in terms of six fire parameters. Required inputs vary depending on the outputs desired by the fire manager. Fuel model options available to users are these: Northern Forest Fire Laboratory (NFFL), National Fire Danger Rating System (NFDRS), and southern California brushland (SCAL). The program has been...

  7. How to reduce your fire insurance rates

    NASA Technical Reports Server (NTRS)

    Dubain, M.

    1971-01-01

    Construction procedures and utilization of materials to reduce the cost of insuring large buildings against losses from fire are discussed. Examples of good and bad techniques in building construction and fire safety management are provided. The inadequacies of building codes and the hazards resulting from improper construction are examined.

  8. Charts for interpreting wildland fire behavior characteristics

    Treesearch

    Patricia L. Andrews; Richard C. Rothermel

    1982-01-01

    The fire characteristics chart is proposed as a graphical method ofpresenting two primary characteristics of fire behavior – spread rate and intensity. Its primary use is communicating and interpreting either site-specific predictions of fire behavior or National Fire-Danger Rating System (NFDRS) indexes and components. Rate of spread, heat per unit area, flame length...

  9. Foliage moisture content estimation from one-dimensional and two-dimensional spectroradiometry for fire danger assessment

    NASA Astrophysics Data System (ADS)

    de Santis, A.; Vaughan, P.; Chuvieco, E.

    2006-12-01

    Moisture content in live fuels is a critical variable in fire ignition and fire behavior assessment, but it is very difficult to estimate using traditional methods. Remote sensing measurements provide adequate temporal and spatial coverage to be used operationally in fire danger estimation. Before such applications can be routinely undertaken, reflectance changes caused by water content variations must be clearly separable from other factors in reflectance variation (leaf area index, chlorophyll content, dry matter, observation-illumination angles, etc.). This paper analyzes the effect of these variables in a controlled experiment using young Holm oak (Quercus Ilex) plants, a common Mediterranean species. Spectro-radiometric measurements were performed systematically in laboratory conditions using a GER 2600 spectroradiometer (point measurements, one-dimensional (1-D)) and a Specim hyperspectral camera system (matrix measurements, 2-D). Leaf and canopy biophysical parameters were sampled to control their influence on reflectance as water stress increased. Equivalent water thickness (EWT) and fuel moisture content (FMC) were correlated against several variations of a new index: the Normalized Difference Spectral Index, (NDSI(λ1,λ2)). Results indicate that the choice of suitable spectral bands is critical to control plant physiological effects on reflectance. Strong correlations were obtained between NDSI and both EWT and FMC by applying operational bands at 1108 and 1242 nm (NDSI(1108,1242): r > 0.93), while the shorter near infrared bands (1000 and 860 nm) show a stronger influence of external factors. A combination of 2-D pixel selection techniques and first derivative spectroscopy successfully solved absolute reflectance inconsistencies between 2-D and 1-D measurements, which may prove to be a helpful means of scaling up from leaf to canopy level, and from the ground to airborne observation.

  10. What are the most fire-dangerous atmospheric circulations in the Eastern-Mediterranean? Analysis of the synoptic wildfire climatology.

    PubMed

    Paschalidou, A K; Kassomenos, P A

    2016-01-01

    Wildfire management is closely linked to robust forecasts of changes in wildfire risk related to meteorological conditions. This link can be bridged either through fire weather indices or through statistical techniques that directly relate atmospheric patterns to wildfire activity. In the present work the COST-733 classification schemes are applied in order to link wildfires in Greece with synoptic circulation patterns. The analysis reveals that the majority of wildfire events can be explained by a small number of specific synoptic circulations, hence reflecting the synoptic climatology of wildfires. All 8 classification schemes used, prove that the most fire-dangerous conditions in Greece are characterized by a combination of high atmospheric pressure systems located N to NW of Greece, coupled with lower pressures located over the very Eastern part of the Mediterranean, an atmospheric pressure pattern closely linked to the local Etesian winds over the Aegean Sea. During these events, the atmospheric pressure has been reported to be anomalously high, while anomalously low 500hPa geopotential heights and negative total water column anomalies were also observed. Among the various classification schemes used, the 2 Principal Component Analysis-based classifications, namely the PCT and the PXE, as well as the Leader Algorithm classification LND proved to be the best options, in terms of being capable to isolate the vast amount of fire events in a small number of classes with increased frequency of occurrence. It is estimated that these 3 schemes, in combination with medium-range to seasonal climate forecasts, could be used by wildfire risk managers to provide increased wildfire prediction accuracy.

  11. A low input, variable firing rate, oil-fired burner

    NASA Astrophysics Data System (ADS)

    Mariano, C. F.

    1982-05-01

    A prototype low input, VFR oil burner was developed which vaporizes the fuel and mixes it with air prior to combustion. The resulting flame is sootless, odorless, quiet, and efficient (only 5 to 10% excess air). The turndown range is 6:1 and could be extended to 12:1. At 14.25% CO2, the NOx level is typical for a standard gas burner firing at 12% CO2; this is a slight improvement, considering the higher flame temperature of the prototype burner.

  12. Afterhyperpolarization-firing rate relation of turtle spinal neurons.

    PubMed

    Stauffer, E K; Stuart, D G; McDonagh, J C; Hornby, T G; Reinking, R M

    2005-02-01

    This study addressed the afterhyperploarization-firing rate relationship of unanesthetized turtle spinal motoneurons and interneurons. The afterhyperploarization of their solitary action potential at rheobase was compared to that during the cells' minimum and maximum firing rates. Like previous mammalian findings, afterhyperpolarization duration and area at rheobase were 32 and 19% less for high- versus low-threshold motoneurons. Contrariwise, maximum firing rate was two times less for the high-threshold group. Other new findings were that for high- versus low-threshold interneurons, afterhyperpolarization duration and area were 25 and 95% less, and maximum firing rate 21% higher for the high-threshold group. For combined motoneurons versus interneurons, there were no differences in afterhyperpolarization duration and area at rheobase, whereas maximum firing rate was 265% higher for the interneurons. For high-threshold motoneurons alone, there were significant associations between minimum firing rate and afterhyperpolarization duration and area measured at rheobase. In summary, this study showed that (1) the afterhyperploarization values of both turtle spinal motoneurons and interneurons at rheobase provided little indication of their corresponding values at the cells' minimum and maximum firing states, and (2) the evolution of afterhyperploarization from rheobase to maximum firing state differed both qualitatively and quantitatively for motoneurons versus interneurons.

  13. Behavioral Status Influences the Dependence of Odorant-Induced Change in Firing on Prestimulus Firing Rate

    PubMed Central

    Doucette, Wilder T.

    2017-01-01

    The firing rate of the mitral/tufted cells in the olfactory bulb is known to undergo significant trial-to-trial variability and is affected by anesthesia. Here we ask whether odorant-elicited changes in firing rate depend on the rate before application of the stimulus in the awake and anesthetized mouse. We find that prestimulus firing rate varies widely on a trial-to-trial basis and that the stimulus-induced change in firing rate decreases with increasing prestimulus firing rate. Interestingly, this prestimulus firing rate dependence was different when the behavioral task did not involve detecting the valence of the stimulus. Finally, when the animal was learning to associate the odor with reward, the prestimulus firing rate was smaller for false alarms compared with correct rejections, suggesting that intrinsic activity reflects the anticipatory status of the animal. Thus, in this sensory modality, changes in behavioral status alter the intrinsic prestimulus activity, leading to a change in the responsiveness of the second-order neurons. We speculate that this trial-to-trial variability in odorant responses reflects sampling of the massive parallel input by subsets of mitral cells. SIGNIFICANCE STATEMENT The olfactory bulb must deal with processing massive parallel input from ∼1200 distinct olfactory receptors. In contrast, the visual system receives input from a small number of photoreceptors and achieves recognition of complex stimuli by allocating processing for distinct spatial locations to different brain areas. Here we find that the change in firing rate elicited by the odorant in second-order mitral cells depends on the intrinsic activity leading to a change of magnitude in the responsiveness of these neurons relative to this prestimulus activity. Further, we find that prestimulus firing rate is influenced by behavioral status. This suggests that there is top-down modulation allowing downstream brain processing areas to perform dynamic readout of

  14. Flash-Fire Propensity and Heat-Release Rate Studies of Improved Fire Resistant Materials

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.

    1978-01-01

    Twenty-six improved fire resistant materials were tested for flash-fire propensity and heat release rate properties. The tests were conducted to obtain a descriptive index based on the production of ignitable gases during the thermal degradation process and on the response of the materials under a specific heat load.

  15. Hospitals are dangerous places.

    PubMed

    de Richemond, Albert L

    2010-01-01

    Hospital fire dangers are real, widespread, and ever present, the article demonstrates, spelling out the locations, conditions, and ignition potentials which exist in such a setting. Knowledge of codes and standards, good maintenance practices, and frequent drills in fire prevention and suppression are among the practices recommended for keeping a hospital fire from becoming a disaster, the author says.

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

    PubMed

    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.

  17. Coal-Fired Power Plant Heat Rate Reductions

    EPA Pesticide Factsheets

    View a report that identifies systems and equipment in coal-fired power plants where efficiency improvements can be realized, and provides estimates of the resulting net plant heat rate reductions and costs for implementation.

  18. Forest Fire Research--Hindsight and Foresight

    Treesearch

    C. E. Van Wagner

    1987-01-01

    The evolution of Forest fire research in Canada first is examined through the works of Wright and Beall, at the Petawawa National Forestry Institute in Ontario, then some lessons are drawn from the past that ought to bear on the future. Some opinions are delivered on the future course of research in fire danger rating, prescribed fire and the impacts of fire on the...

  19. Population rate dynamics and multineuron firing patterns in sensory cortex

    PubMed Central

    Okun, Michael; Yger, Pierre; Marguet, Stephan; Gerard-Mercier, Florian; Benucci, Andrea; Katzner, Steffen; Busse, Laura; Carandini, Matteo; Harris, Kenneth D.

    2012-01-01

    Cortical circuits encode sensory stimuli through the firing of neuronal ensembles, and also produce spontaneous population patterns in the absence of sensory drive. This population activity is often characterized experimentally by the distribution of multineuron “words” (binary firing vectors), and a match between spontaneous and evoked word distributions has been suggested to reflect learning of a probabilistic model of the sensory world. We analyzed multineuron word distributions in sensory cortex of anesthetized rats and cats, and found that they are dominated by fluctuations in population firing rate rather than precise interactions between individual units. Furthermore, cortical word distributions change when brain state shifts, and similar behavior is seen in simulated networks with fixed, random connectivity. Our results suggest that similarity or dissimilarity in multineuron word distributions could primarily reflect similarity or dissimilarity in population firing rate dynamics, and not necessarily the precise interactions between neurons that would indicate learning of sensory features. PMID:23197704

  20. Synchronization of motor unit firings: an epiphenomenon of firing rate characteristics not common inputs

    PubMed Central

    Kline, Joshua C.

    2015-01-01

    Synchronous motor unit firing instances have been attributed to anatomical inputs shared by motoneurons. Yet, there is a lack of empirical evidence confirming the notion that common inputs elicit synchronization under voluntary conditions. We tested this notion by measuring synchronization between motor unit action potential trains (MUAPTs) as their firing rates progressed within a contraction from a relatively low force level to a higher one. On average, the degree of synchronization decreased as the force increased. The common input notion provides no empirically supported explanation for the observed synchronization behavior. Therefore, we investigated a more probable explanation for synchronization. Our data set of 17,546 paired MUAPTs revealed that the degree of synchronization varies as a function of two characteristics of the motor unit firing rate: the similarity and the slope as a function of force. Both are measures of the excitation of the motoneurons. As the force generated by the muscle increases, the firing rate slope decreases, and the synchronization correspondingly decreases. Different muscles have motor units with different firing rate characteristics and display different amounts of synchronization. Although this association is not proof of causality, it consistently explains our observations and strongly suggests further investigation. So viewed, synchronization is likely an epiphenomenon, subject to countless unknown neural interactions. As such, synchronous firing instances may not be the product of a specific design and may not serve a specific physiological purpose. Our explanation for synchronization has the advantage of being supported by empirical evidence, whereas the common input does not. PMID:26490288

  1. 44 CFR 204.21 - Fire management assistance declaration criteria.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... evaluate the threat posed by a fire or fire complex based on consideration of the following specific criteria: (1) Threat to lives and improved property, including threats to critical facilities... Danger Ratings System; (4) Potential major economic impact....

  2. 44 CFR 204.21 - Fire management assistance declaration criteria.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... complex threatens such destruction as would constitute a major disaster. (b) Evaluation criteria. We will evaluate the threat posed by a fire or fire complex based on consideration of the following specific... Danger Ratings System; (4) Potential major economic impact. ...

  3. Fire Behavior System for the Full Range of Fire Management Needs

    Treesearch

    Richard C. Rothermel; Patricia L. Andrews

    1987-01-01

    An "integrated fire behavior/fire danger rating system" should be "seamless" to avoid requiring choices among alternate, independent systems. Descriptions of fuel moisture, fuels, and fire behavior should be standardized, permitting information to flow easily through the spectrum of fire management needs. The level of resolution depends on the...

  4. Modeling the variability of firing rate of retinal ganglion cells.

    PubMed

    Levine, M W

    1992-12-01

    Impulse trains simulating the maintained discharges of retinal ganglion cells were generated by digital realizations of the integrate-and-fire model. If the mean rate were set by a "bias" level added to "noise," the variability of firing would be related to the mean firing rate as an inverse square root law; the maintained discharges of retinal ganglion cells deviate systematically from such a relationship. A more realistic relationship can be obtained if the integrate-and-fire mechanism is "leaky"; with this refinement, the integrate-and-fire model captures the essential features of the data. However, the model shows that the distribution of intervals is insensitive to that of the underlying variability. The leakage time constant, threshold, and distribution of the noise are confounded, rendering the model unspecifiable. Another aspect of variability is presented by the variance of responses to repeated discrete stimuli. The variance of response rate increases with the mean response amplitude; the nature of that relationship depends on the duration of the periods in which the response is sampled. These results have defied explanation. But if it is assumed that variability depends on mean rate in the way observed for maintained discharges, the variability of responses to abrupt changes in lighting can be predicted from the observed mean responses. The parameters that provide the best fits for the variability of responses also provide a reasonable fit to the variability of maintained discharges.

  5. Firing Rate Dynamics in the Hippocampus Induced by Trajectory Learning

    PubMed Central

    Wilson, Matthew A.

    2008-01-01

    The hippocampus is essential for spatial navigation, which may involve sequential learning. However, how the hippocampus encodes new sequences in familiar environments is unknown. To study the impact of novel spatial sequences on the activity of hippocampal neurons, we monitored hippocampal ensembles while rats learned to switch from two familiar trajectories to a new one in a familiar environment. Here, we show that this novel spatial experience induces two types of changes in firing rates, but not locations of hippocampal place cells. First, place-cell firing rates on the two familiar trajectories start to change before the actual behavioral switch to the new trajectory. Second, repeated exposure on the new trajectory is associated with an increased dependence of place-cell firing rates on immediate past locations. The result suggests that sequence encoding in the hippocampus may involve integration of information about the recent past into current state. PMID:18448645

  6. Sleep regulation of the distribution of cortical firing rates.

    PubMed

    Levenstein, Daniel; Watson, Brendon O; Rinzel, John; Buzsáki, György

    2017-03-10

    Sleep is thought to mediate both mnemonic and homeostatic functions. However, the mechanism by which this brain state can simultaneously implement the 'selective' plasticity needed to consolidate novel memory traces and the 'general' plasticity necessary to maintain a well-functioning neuronal system is unclear. Recent findings show that both of these functions differentially affect neurons based on their intrinsic firing rate, a ubiquitous neuronal heterogeneity. Furthermore, they are both implemented by the NREM slow oscillation, which also distinguishes neurons based on firing rate during sequential activity at the DOWN→UP transition. These findings suggest a mechanism by which spiking activity during the slow oscillation acts to maintain network statistics that promote a skewed distribution of neuronal firing rates, and perturbation of that activity by hippocampal replay acts to integrate new memory traces into the existing cortical network.

  7. Fire effects on infiltration rates after prescribed fire in northern Rocky Mountain forests, USA

    Treesearch

    Peter R. Robichaud

    2000-01-01

    Infiltration rates in undisturbed forest environments are generally high. These high infiltration rates may be reduced when forest management activities such as timber harvesting and/or prescribed fires are used. Post-harvest residue burning is a common site preparation treatment used in the Northern Rocky Mountains, USA, to reduce forest fuels and to prepare sites for...

  8. Charring Rate for Fire Exposed X-Lam

    NASA Astrophysics Data System (ADS)

    Wong, Bernice VY; Fah Tee, Kong

    2017-06-01

    Design of timber structures has been outlined in Eurocode 5. Notional charring rate for softwood and hardwood timber is given. For the performance of X-LAM panels in fire, only little information on charring is available and whether the fire behaviour of X-LAM is similar to homogenous timber panels has not yet been systematically analysed. This paper presents an overview of fire performance of X-LAM and evaluation of its resistance to elevated temperature as an element of structure in comparison to homogeneous timber panels. Numerical study has been carried out based on available experimental results. Charring rates for X-LAM panels obtained from experimental results are compared with those obtained from Eurocode 5 and proposed simplified model.

  9. Synchronization of motor unit firings: an epiphenomenon of firing rate characteristics not common inputs.

    PubMed

    Kline, Joshua C; De Luca, Carlo J

    2016-01-01

    Synchronous motor unit firing instances have been attributed to anatomical inputs shared by motoneurons. Yet, there is a lack of empirical evidence confirming the notion that common inputs elicit synchronization under voluntary conditions. We tested this notion by measuring synchronization between motor unit action potential trains (MUAPTs) as their firing rates progressed within a contraction from a relatively low force level to a higher one. On average, the degree of synchronization decreased as the force increased. The common input notion provides no empirically supported explanation for the observed synchronization behavior. Therefore, we investigated a more probable explanation for synchronization. Our data set of 17,546 paired MUAPTs revealed that the degree of synchronization varies as a function of two characteristics of the motor unit firing rate: the similarity and the slope as a function of force. Both are measures of the excitation of the motoneurons. As the force generated by the muscle increases, the firing rate slope decreases, and the synchronization correspondingly decreases. Different muscles have motor units with different firing rate characteristics and display different amounts of synchronization. Although this association is not proof of causality, it consistently explains our observations and strongly suggests further investigation. So viewed, synchronization is likely an epiphenomenon, subject to countless unknown neural interactions. As such, synchronous firing instances may not be the product of a specific design and may not serve a specific physiological purpose. Our explanation for synchronization has the advantage of being supported by empirical evidence, whereas the common input does not. Copyright © 2016 the American Physiological Society.

  10. An Electronic Timer for Measuring Spread Rates of Wildland Fires

    Treesearch

    Richard W. Blank; Albert J. Simard

    1983-01-01

    There are many disadvantages to current techniques for measuring the spread rate of wildland fires. This paper describes the design and use of an electronic timber that resolves most of the problems. The unit is small, lightweight, inexpensive, easy-to-assemble, self-contained, and long-running.

  11. Initial fuel temperature effects on burning rate of pool fire.

    PubMed

    Chen, Bing; Lu, Shou-Xiang; Li, Chang-Hai; Kang, Quan-Sheng; Lecoustre, Vivien

    2011-04-15

    The influence of the initial fuel temperature on the burning behavior of n-heptane pool fire was experimentally studied at the State Key Laboratory of Fire Science (SKLFS) large test hall. Circular pool fires with diameters of 100mm, 141 mm, and 200 mm were considered with initial fuel temperatures ranging from 290 K to 363 K. Burning rate and temperature distributions in fuel and vessel wall were recorded during the combustion. The burning rate exhibited five typical stages: initial development, steady burning, transition, bulk boiling burning, and decay. The burning rate during the steady burning stage was observed to be relatively independent of the initial fuel temperature. In contrast, the burning rate of the bulk boiling burning stage increases with increased initial fuel temperature. It was also observed that increased initial fuel temperature decreases the duration of steady burning stage. When the initial temperature approaches the boiling point, the steady burning stage nearly disappears and the burning rate moves directly from the initial development stage to the transition stage. The fuel surface temperature increases to its boiling point at the steady burning stage, shortly after ignition, and the bulk liquid reaches boiling temperature at the bulk boiling burning stage. No distinguished cold zone is formed in the fuel bed. However, boiling zone is observed and the thickness increases to its maximum value when the bulk boiling phenomena occurs.

  12. Aids to determining fuel models for estimating fire behavior

    Treesearch

    Hal E. Anderson

    1982-01-01

    Presents photographs of wildland vegetation appropriate for the 13 fuel models used in mathematical models of fire behavior. Fuel model descriptions include fire behavior associated with each fuel and its physical characteristics. A similarity chart cross-references the 13 fire behavior fuel models to the 20 fuel models used in the National Fire Danger Rating System....

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

    PubMed Central

    Wallisch, Pascal; Ostojic, Srdjan

    2016-01-01

    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. SIGNIFICANCE STATEMENT 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. PMID:27807166

  14. Cardiovascular stress, energy expenditure and subjective perceived ratings of fire fighters during typical fire suppression and rescue tasks.

    PubMed

    Bugajska, Joanna; Zuzewicz, Krystyna; Szmauz-Dybko, Magdalena; Konarska, Maria

    2007-01-01

    The study determined physiological and psychophysical responses to fire fighters' typical activities. Self-reported assessment of the most demanding fire fighting/rescue tasks were collected with a questionnaire. Then 19 voluntary fire fighters performed 3 simulated fire fighting/rescue tasks in protective clothing. Heart rate (HR), blood pressure and energy expenditure were measured; the rating of perceived exertion (RPE) was assessed with the Borg scale. The questionnaires showed that carrying out victims, fire suppression and resuscitation were classified as heavy load; climbing stairs with a hose as moderate load. According to RPE the subjects considered their effort during ladder climbing fairly light and only somewhat harder during stair climbing and carrying out injured people. The study demonstrated that typical fire fighting/rescue tasks were associated with high energy expenditure and imposed considerable cardiovascular stress. The Borg scale appeared not suitable for assessing perceived exertion in fire fighters during simulated tasks.

  15. A method for ensemble wildland fire simulation

    Treesearch

    Mark A. Finney; Isaac C. Grenfell; Charles W. McHugh; Robert C. Seli; Diane Trethewey; Richard D. Stratton; Stuart Brittain

    2011-01-01

    An ensemble simulation system that accounts for uncertainty in long-range weather conditions and two-dimensional wildland fire spread is described. Fuel moisture is expressed based on the energy release component, a US fire danger rating index, and its variation throughout the fire season is modeled using time series analysis of historical weather data. This analysis...

  16. Seasonal predictions for wildland fire severity

    Treesearch

    Shyh-Chin Chen; Haiganoush Preisler; Francis Fujioka; John W. Benoit; John O. Roads

    2009-01-01

    The National Fire Danger Rating System (NFDRS) indices deduced from the monthly to seasonal predictions of a meteorological climate model at 50-km grid space from January 1998 through December 2003 were used in conjunction with a probability model to predict the expected number of fire occurrences and large fires over the U.S. West. The short-term climate forecasts are...

  17. Effects of fire intensity on vital rates of an endemic herb of the Florida keys, USA

    USGS Publications Warehouse

    Liu, H.; Menges, E.S.; Snyder, J.R.; Koptur, S.; Ross, M.S.

    2005-01-01

    Fire intensity is one of the important components of a fire regime. However, relatively few studies have linked fire intensity with post-fire population vital rates. In this study, we explored the effects of fire intensity on population vital rates of Chamaecrista keyensis Pennell (Fabaceae) up to two years post-fire. C. keyensis is an endemic understory plant of pine rockland, a fire-dependent ecosystem of the Lower Florida Keys. We measured one fire intensity indicator, fire temperature reached by steel plates on the ground, during three prescribed fires at different sites. We followed marked individuals up to two years post-fire to derive annual survival, annual growth rate, percentage of fruiting plants, mean number of fruits per reproductive plant, and number of seedlings per census plot (1 m2) of C. keyensis. We found fire intensity had significant effects on reproduction in the first year post-fire only. More specifically, mean number of fruits and percentage of fruiting plants increased as fire intensity increased. Results from this study suggest that extremely low fire intensity caused by very short fire return intervals (e.g., less than three years) may not provide sufficient stimulation to reproduction to achieve the best post-fire recovery for C. keyensis.

  18. Computer program for calculating and plotting fire direction and rate of spread.

    Treesearch

    James E. Eenigenburg

    1987-01-01

    Presents an analytical procedure that uses a FORTRAN 77 program to estimate fire direction and rate of spread. The program also calculates the variability of these parameters, both for subsections of the fire and for the fires as a whole. An option in the program allows users with a CALCOMP plotter to obtain a map of the fire with spread vectors.

  19. Rates of initial spread of free-burning fires on the National Forests of California

    Treesearch

    C.A. Abell

    1940-01-01

    As early as 1914 Coert DuBois and his staff recognized that knowledge of the rates which fires spread was essential to sound fire control planning, strategy, and tactics, and therefore designed the fire report form so that such data might be accumulated. Although the individual fire report form has changed appreciably since that time, the supply of data has grown...

  20. Towards the dynamic prediction of wildfire danger. Modeling temporal scenarios of fire-occurrence in Northeast Spain

    NASA Astrophysics Data System (ADS)

    Martín, Yago; Rodrigues, Marcos

    2017-04-01

    Up to date models of human-caused ignition probability have commonly been developed from a static or structural point of view, regardless of the time cycles that drive human behavior or environmental conditions. However, human drivers mostly have a temporal dimension, and fuel conditions are subjected to temporal changes as well, which is why a historical/temporal perspective is often required. Previous studies in the region suggest that human driving factors of wildfires have undergone significant shifts in inter-annual occurrence probability models, thus varying over time. On the other hand, an increasing role of environmental conditions has also been reported. This research comprehensively analyzes the intra-annual dimension of fire occurrence and fire-triggering factors using NW Spain as a test area, moving one-step forward towards achieving more accurate predictions, to ultimately develop dynamic predictive models. To this end, several intra-annual presence-only models have been calibrated, exploring seasonal variations of environmental conditions and short-term cycles of human activity (working- vs non-working days). Models were developed from accurately geolocated fire data in the 2008-2012 period, and GIS and remote sensing (MOD1A2 and MOD16) information . Specifically, 8 occurrence data subsets (scenarios) were constructed by splitting fire records into 4 seasons (winter, spring, summer and autumn) then separating each season into 2 new categories (working and non-working days). This allows analyzing the temporal variation of socioeconomic (urban- and agricultural-interfaces, transport and road networks, and human settlements) and environmental (fuel conditions) factors associated with occurrence. Models were calibrated applying the Maximum Entropy algorithm (MaxEnt). The MaxEnt algorithm was selected as it is the most widespread approach to deal with presence-only data, as may be the case of fire occurrence. The dependent variable for each scenario was

  1. Do great tits (Parus major) suppress basal metabolic rate in response to increased perceived predation danger? A field experiment.

    PubMed

    Mathot, Kimberley J; Abbey-Lee, Robin N; Kempenaers, Bart; Dingemanse, Niels J

    2016-10-01

    Several studies have shown that individuals with higher metabolic rates (MRs) feed at higher rates and are more willing to forage in the presence of predators. This increases the acquisition of resources, which in turn, may help to sustain a higher MR. Elevated predation danger may be expected to result in reduced MRs, either as a means of allowing for reduced feeding and risk-taking, or as a consequence of adaptively reducing intake rates via reduced feeding and/or risk-taking. We tested this prediction in free-living great tits (Parus major) using a playback experiment to manipulate perceived predation danger. There was evidence that changes in body mass and BMR differed as a function of treatment. In predator treatment plots, great tits tended to reduce their body mass, a commonly observed response in birds to increased predation danger. In contrast, birds from control treatment plots showed no overall changes in body mass. There was also evidence that great tits from control treatment plots increased their basal metabolic rate (BMR) over the course of the experiment, presumably due to decreasing ambient temperatures over the study period. However, there was no evidence for changes in BMR for birds from predator treatment plots. Although the directions of these results are consistent with the predicted directions of effects, the effects sizes and confidence intervals yield inconclusive support for the hypothesis that great tits would adaptively suppress BMR in response to increased perceived predation risk. The effect size observed in the present study was small (~1%) and would not be expected to result in substantive reductions in feeding rate and/or risk-taking. Whether or not ecological conditions that generate greater energetic stress (e.g. lower food availability, lower ambient temperatures) could produce an effect that produces biologically meaningful reductions in feeding activity and/or risk-taking remains an open question.

  2. Restoring Upland Forests to Longleaf Pine: Initial Effects on Fuel Load, Fire Danger, Forest Vegetation, and Beetle Populations

    Treesearch

    James D. Haywood; Tessa A. Bauman; Richard A. Goyer; Finis L. Harris

    2004-01-01

    Without fire in the Southeastern United States, loblolly pine (Pinus taeda L.) often becomes the overstory dominant on sites historically dominated by longleaf pine (P. palustris Mill.). Beneath the loblolly pine canopy a mature midstory and understory develops of woody vegetation supporting draped fuels. The resulting deep shade...

  3. Invariance of firing rate and field potential dynamics to stimulus modulation rate in human auditory cortex.

    PubMed

    Mukamel, Roy; Nir, Yuval; Harel, Michal; Arieli, Amos; Malach, Rafael; Fried, Itzhak

    2011-08-01

    The effect of stimulus modulation rate on the underlying neural activity in human auditory cortex is not clear. Human studies (using both invasive and noninvasive techniques) have demonstrated that at the population level, auditory cortex follows stimulus envelope. Here we examined the effect of stimulus modulation rate by using a rare opportunity to record both spiking activity and local field potentials (LFP) in auditory cortex of patients during repeated presentations of an audio-visual movie clip presented at normal, double, and quadruple speeds. Mean firing rate during evoked activity remained the same across speeds and the temporal response profile of firing rate modulations at increased stimulus speeds was a linearly scaled version of the response during slower speeds. Additionally, stimulus induced power modulation of local field potentials in the high gamma band (64-128 Hz) exhibited similar temporal scaling as the neuronal firing rate modulations. Our data confirm and extend previous studies in humans and anesthetized animals, supporting a model in which both firing rate, and high-gamma LFP power modulations in auditory cortex follow the temporal envelope of the stimulus across different modulation rates.

  4. Flame quality monitor system for fixed firing rate oil burners

    DOEpatents

    Butcher, Thomas A.; Cerniglia, Philip

    1992-01-01

    A method and apparatus for determining and indicating the flame quality, or efficiency of the air-fuel ratio, in a fixed firing rate heating unit, such as an oil burning furnace, is provided. When the flame brightness falls outside a preset range, the flame quality, or excess air, has changed to the point that the unit should be serviced. The flame quality indicator output is in the form of lights mounted on the front of the unit. A green light indicates that the flame is about in the same condition as when the burner was last serviced. A red light indicates a flame which is either too rich or too lean, and that servicing of the burner is required. At the end of each firing cycle, the flame quality indicator goes into a hold mode which is in effect during the period that the burner remains off. A yellow or amber light indicates that the burner is in the hold mode. In this mode, the flame quality lights indicate the flame condition immediately before the burner turned off. Thus the unit can be viewed when it is off, and the flame condition at the end of the previous firing cycle can be observed.

  5. VARIABLE FIRING RATE OIL BURNER USING PULSE FUEL FLOW CONTROL.

    SciTech Connect

    KRISHNA,C.R.; BUTCHER,T.A.; KAMATH,B.R.

    2004-10-01

    The residential oil burner market is currently dominated by the pressure-atomized retention head burner, which has an excellent reputation for reliability and efficiency. In this burner, oil is delivered to a fuel nozzle at pressures from 100 to 150 psi. In addition, to atomizing the fuel, the small, carefully controlled size of the nozzle exit orifice serves to control the burner firing rate. Burners of this type are currently available at firing rates of more than 0.5 gallons-per-hour (70,000 Btu/hr). Nozzles have been made for lower firing rates, but experience has shown that such nozzles suffer rapid fouling of the necessarily small passages, leading to bad spray patterns and poor combustion performance. Also, traditionally burners and the nozzles are oversized to exceed the maximum demand. Typically, this is figured as follows. The heating load of the house on the coldest day for the location is considered to define the maximum heat load. The contractor or installer adds to this to provide a safety margin and for future expansion of the house. If the unit is a boiler that provides domestic hot water through the use of a tankless heating coil, the burner capacity is further increased. On the contrary, for a majority of the time, the heating system is satisfying a much smaller load, as only rarely do all these demands add up. Consequently, the average output of the heating system has to be much less than the design capacity and this is accomplished by start and stop cycling operation of the system so that the time-averaged output equals the demand. However, this has been demonstrated to lead to overall efficiencies lower than the steady-state efficiency. Therefore, the two main reasons for the current practice of using oil burners much larger than necessary for space heating are the unavailability of reliable low firing rate oil burners and the desire to assure adequate input rate for short duration, high draw domestic hot water loads. One approach to solve this

  6. Dose- and Rate-Dependent Effects of Cocaine on Striatal Firing Related to Licking

    PubMed Central

    Tang, Chengke; Mittler, Taliah; Duke, Dawn C.; Zhu, Yun; Pawlak, Anthony P.; West, Mark O.

    2011-01-01

    To examine the role of striatal mechanisms in cocaine-induced stereotyped licking, we investigated the acute effects of cocaine on striatal neurons in awake, freely moving rats before and after cocaine administration (0, 5, 10, or 20 mg/kg). Stereotyped licking was induced only by the high dose. Relative to control (saline), cocaine reduced lick duration and concurrently increased interlick interval, particularly at the high dose, but it did not affect licking rhythm. Firing rates of striatal neurons phasically related to licking movements were compared between matched licks before and after injection, minimizing any influence of sensorimotor variables on changes in firing. Both increases and decreases in average firing rate of striatal neurons were observed after cocaine injection, and these changes exhibited a dose-dependent pattern that strongly depended on predrug firing rate. At the middle and high doses relative to the saline group, the average firing rates of slow firing neurons were increased by cocaine, resulting from a general elevation of movement-related firing rates. In contrast, fast firing neurons showed decreased average firing rates only in the high-dose group, with reduced firing rates across the entire range for these neurons. Our findings suggest that at the high dose, increased phasic activity of slow firing striatal neurons and simultaneously reduced phasic activity of fast firing striatal neurons may contribute, respectively, to the continual initiation of stereotypic movements and the absence of longer movements. PMID:17991811

  7. The relationship of motor unit size, firing rate and force.

    PubMed

    Conwit, R A; Stashuk, D; Tracy, B; McHugh, M; Brown, W F; Metter, E J

    1999-07-01

    Using a clinical electromyographic (EMG) protocol, motor units were sampled from the quadriceps femoris during isometric contractions at fixed force levels to examine how average motor unit size and firing rate relate to force generation. Mean firing rates (mFRs) and sizes (mean surface-detected motor unit action potential (mS-MUAP) area) of samples of active motor units were assessed at various force levels in 79 subjects. MS-MUAP size increased linearly with increased force generation, while mFR remained relatively constant up to 30% of a maximal force and increased appreciably only at higher force levels. A relationship was found between muscle force and mS-MUAP area (r2 = 0.67), mFR (r2 = 0.38), and the product of mS-MUAP area and mFR (mS-MUAP x mFR) (r2 = 0.70). The results support the hypothesis that motor units are recruited in an orderly manner during forceful contractions, and that in large muscles only at higher levels of contraction ( > 30% MVC) do mFRs increase appreciably. MS-MUAP and mFR can be assessed using clinical EMG techniques and they may provide a physiological basis for analyzing the role of motor units during muscle force generation.

  8. Separating Spike Count Correlation from Firing Rate Correlation

    PubMed Central

    Vinci, Giuseppe; Ventura, Valérie; Smith, Matthew A.; Kass, Robert E.

    2016-01-01

    Populations of cortical neurons exhibit shared fluctuations in spiking activity over time. When measured for a pair of neurons over multiple repetitions of an identical stimulus, this phenomenon emerges as correlated trial-to-trial response variability via spike count correlation (SCC). However, spike counts can be viewed as noisy versions of firing rates, which can vary from trial to trial. From this perspective, the SCC for a pair of neurons becomes a noisy version of the corresponding firing-rate correlation (FRC). Furthermore, the magnitude of the SCC is generally smaller than that of the FRC, and is likely to be less sensitive to experimental manipulation. We provide statistical methods for disambiguating time-averaged drive from within-trial noise, thereby separating FRC from SCC. We study these methods to document their reliability, and we apply them to neurons recorded in vivo from area V4, in an alert animal. We show how the various effects we describe are reflected in the data: within-trial effects are largely negligible, while attenuation due to trial-to-trial variation dominates, and frequently produces comparisons in SCC that, because of noise, do not accurately reflect those based on the underlying FRC. PMID:26942746

  9. Assertions of "future dangerousness" at federal capital sentencing: rates and correlates of subsequent prison misconduct and violence.

    PubMed

    Cunningham, Mark D; Reidy, Thomas J; Sorensen, Jon R

    2008-02-01

    The federal prison disciplinary records of federal capital inmates (n=145) who were sentenced to life without possibility of release (LWOP) by plea bargain, pre-sentencing withdrawal of the death penalty, or jury determination were retrospectively reviewed (M=6.17 years post-admission). Disaggregated prevalence rates were inversely related to infraction severity: serious infraction =0.324, assaultive infraction =0.207, serious assault =0.09, assault with moderate injury =0.007, assault with major injuries or death =0.00. Frequency rates of misconduct were equivalent to other high-security federal inmates (n=18,561), regardless of infraction severity. Government assertions of "future dangerousness" as a nonstatutory aggravating factor were not predictive of prison misconduct. These findings inform federal capital risk assessments and have public policy implications for procedural reliability in death penalty prosecutions.

  10. Fire effects on infiltration rates after prescribed fire in Northern Rocky Mountain forests, USA

    NASA Astrophysics Data System (ADS)

    Robichaud, P. R.

    2000-05-01

    Infiltration rates in undisturbed forest environments are generally high. These high infiltration rates may be reduced when forest management activities such as timber harvesting and/or prescribed fires are used. Post-harvest residue burning is a common site preparation treatment used in the Northern Rocky Mountains, USA, to reduce forest fuels and to prepare sites for natural and artificial tree regeneration. Prescribed burn operations attempt to leave sites with the surface condition of a low-severity burn. However, some of the areas often experience surface conditions associated with a high-severity burn which may result in hydrophobic or water repellent conditions. In this study, infiltration rates were measured after logging slash was broadcast burned from two prescribed burns. The two sites were in Northern Rocky coniferous forests of Douglas-fir/lodgepole pine and ponderosa pine/Douglas-fir. Simulated rainfall was applied to one-square meter plots in three, 30-min applications at 94 mm h-1 within the three surface conditions found after the burn: unburned-undisturbed areas, low-severity burn areas and high-severity burn areas. Runoff hydrographs from the rainfall simulations were relatively constant from the plots that were in unburned-undisturbed areas and in areas subjected to a low-severity burn. These constant runoff rates indicate constant hydraulic conductivity values for these surface conditions even though there was variation between plots. Hydrographs from the rainfall simulation plots located within areas of high-severity burn indicate greater runoff rates than the plots in low-severity burn areas especially during the initial stages of the first rainfall event. These runoff rates decreased to a constant rate for the last 10 min of the event. These results indicate hydrophobic or water repellent soil conditions, which temporarily cause a 10-40% reduction in hydraulic conductivity values when compared to a normal infiltrating soil condition. Since

  11. Which substance is most dangerous? Perceived harm ratings among students in urban and rural Norway.

    PubMed

    Pedersen, Willy; Von Soest, Tilmann

    2015-06-01

    Recent studies have challenged the idea that illegal substances are necessarily associated with more harm than those that are legal. This study investigates perceived drug harm among students at the University of Oslo (UO) and at a smaller university located on Norway's coast in a more conservative and religious region, called 'Coastal University' (CU). This study consisted of surveys (n=458) about perceived physical harm, mental health conditions, dependence, injuries and social consequences that may be associated with the use of tobacco, alcohol and cannabis. Information about substance use was also collected. Analyses of variance and multiple regression analyses were used to examine whether harm ratings differed for different drugs, whether drug type, gender and university site interacted in predicting harm ratings, and what role the participants' own substance use played in their harm ratings. UO students rated cannabis as overall less harmful than alcohol, while the opposite was true for CU students. Tobacco received the highest physical harm score. Alcohol was rated as most harmful with regard to injuries; cannabis was rated as most harmful with regard to mental health consequences. Use of the substance in question was associated with a reduced harm rating. This was particularly true for cannabis. Norwegian students rate the harm of substances differently from previous reports from the Norwegian general population. Most importantly, their relative ratings of cannabis harm were lower. However, the pattern was most evident among students from the urban Oslo area. © 2015 the Nordic Societies of Public Health.

  12. Fire!

    ERIC Educational Resources Information Center

    Jones, Rebecca

    1996-01-01

    The number of school fires is up nationwide. This article describes unsafe school conditions, problems with new fire codes, and the factors that contribute to school fires. Installation of sprinkler systems is recommended. A fire-safety checklist is included. (LMI)

  13. Distinguishing intrinsic from extrinsic factors underlying firing rate saturation in human motor units

    PubMed Central

    Lester, Rosemary A.; Johns, Richard K.

    2014-01-01

    During voluntary contraction, firing rates of individual motor units (MUs) increase modestly over a narrow force range beyond which little additional increase in firing rate is seen. Such saturation of MU discharge may be a consequence of extrinsic factors that limit net synaptic excitation acting on motor neurons (MNs) or may be due to intrinsic properties of the MNs. Two sets of experiments involving recording of human biceps brachii MUs were carried out to evaluate saturation. In the first set, the extent of saturation was quantified for 136 low-threshold MUs during isometric ramp contractions. Firing rate-force data were best fit by a saturating function for 90% of MUs recorded with a maximum rate of 14.8 ± 2.0 impulses/s. In the second set of experiments, to distinguish extrinsic from intrinsic factors underlying saturation, we artificially augmented descending excitatory drive to biceps MNs by activation of muscle spindle afferents through tendon vibration. We examined the change in firing rate caused by tendon vibration in 96 MUs that were voluntarily activated at rates below and at saturation. Vibration had little effect on the discharge of MUs that were firing at saturation frequencies but strongly increased firing rates of the same units when active at lower frequencies. These results indicate that saturation is likely caused by intrinsic mechanisms that prevent further increases in firing rate in the presence of increasing synaptic excitation. Possible intrinsic cellular mechanisms that limit firing rates of motor units during voluntary effort are discussed. PMID:25475356

  14. Distinguishing intrinsic from extrinsic factors underlying firing rate saturation in human motor units.

    PubMed

    Fuglevand, Andrew J; Lester, Rosemary A; Johns, Richard K

    2015-03-01

    During voluntary contraction, firing rates of individual motor units (MUs) increase modestly over a narrow force range beyond which little additional increase in firing rate is seen. Such saturation of MU discharge may be a consequence of extrinsic factors that limit net synaptic excitation acting on motor neurons (MNs) or may be due to intrinsic properties of the MNs. Two sets of experiments involving recording of human biceps brachii MUs were carried out to evaluate saturation. In the first set, the extent of saturation was quantified for 136 low-threshold MUs during isometric ramp contractions. Firing rate-force data were best fit by a saturating function for 90% of MUs recorded with a maximum rate of 14.8 ± 2.0 impulses/s. In the second set of experiments, to distinguish extrinsic from intrinsic factors underlying saturation, we artificially augmented descending excitatory drive to biceps MNs by activation of muscle spindle afferents through tendon vibration. We examined the change in firing rate caused by tendon vibration in 96 MUs that were voluntarily activated at rates below and at saturation. Vibration had little effect on the discharge of MUs that were firing at saturation frequencies but strongly increased firing rates of the same units when active at lower frequencies. These results indicate that saturation is likely caused by intrinsic mechanisms that prevent further increases in firing rate in the presence of increasing synaptic excitation. Possible intrinsic cellular mechanisms that limit firing rates of motor units during voluntary effort are discussed.

  15. The downs and ups of sensory deprivation: evidence for firing rate homeostasis in vivo.

    PubMed

    Bishop, Hannah I; Zito, Karen

    2013-10-16

    Homeostatic adjustment of neuronal firing rates is considered a vital mechanism to keep neurons operating in their optimal range despite dynamically changing input. Two studies in this issue of Neuron, Hengen et al. (2013) and Keck et al. (2013), provide evidence for firing rate homeostasis in the neocortex of freely behaving rodents.

  16. Estimating wildland fire rate of spread in a spatially nonuniform environment

    Treesearch

    Francis M Fujioka

    1985-01-01

    Estimating rate of fire spread is a key element in planning for effective fire control. Land managers use the Rothermel spread model, but the model assumptions are violated when fuel, weather, and topography are nonuniform. This paper compares three averaging techniques--arithmetic mean of spread rates, spread based on mean fuel conditions, and harmonic mean of spread...

  17. A memristive spiking neuron with firing rate coding

    PubMed Central

    Ignatov, Marina; Ziegler, Martin; Hansen, Mirko; Petraru, Adrian; Kohlstedt, Hermann

    2015-01-01

    Perception, decisions, and sensations are all encoded into trains of action potentials in the brain. The relation between stimulus strength and all-or-nothing spiking of neurons is widely believed to be the basis of this coding. This initiated the development of spiking neuron models; one of today's most powerful conceptual tool for the analysis and emulation of neural dynamics. The success of electronic circuit models and their physical realization within silicon field-effect transistor circuits lead to elegant technical approaches. Recently, the spectrum of electronic devices for neural computing has been extended by memristive devices, mainly used to emulate static synaptic functionality. Their capabilities for emulations of neural activity were recently demonstrated using a memristive neuristor circuit, while a memristive neuron circuit has so far been elusive. Here, a spiking neuron model is experimentally realized in a compact circuit comprising memristive and memcapacitive devices based on the strongly correlated electron material vanadium dioxide (VO2) and on the chemical electromigration cell Ag/TiO2−x/Al. The circuit can emulate dynamical spiking patterns in response to an external stimulus including adaptation, which is at the heart of firing rate coding as first observed by E.D. Adrian in 1926. PMID:26539074

  18. A Scale for Rating Fire-Prevention Contactors

    Treesearch

    M.L. Doolittle

    1979-01-01

    A scale is constructed to help fire-prevention program administrators determine if an individual contactor is effective at influencing people. The 24 items in the scale indicate the qualities that an effective contactor should have.

  19. Fire

    Treesearch

    John R. Jones; Norbert V. DeByle

    1985-01-01

    In some areas, many aspen stands are all the same age, dating from a single great fire or a year of widespread fires (fig. 1). The 1879 fire in the Jackson Hole region of Wyoming (Loope and Gruell 1973) and the 1904 fires in Arizona's White Mountains (Kallander 1969) are examples. Choate (1966) found that almost all aspen stands in New Mexico were even-aged, many...

  20. FIRE

    Atmospheric Science Data Center

    2017-03-16

    Projects:  FIRE Definition/Description:  The F irst I SCCP R egional E xperiments (FIRE) have been designed to improve data products and cloud/radiation ... circulation models (GCMs). Specifically, the goals of FIRE are (1) to improve basic understanding of the interaction of physical ...

  1. Suitability of different Fire Weather Indices for alpine conditions: an extensive evaluation with high resolution data

    NASA Astrophysics Data System (ADS)

    Cane, D.; Arpaci, A.; Conedera, M.; Valese, E.; Barbarino, S.; Vacik, H.; Pezzatti, G. B.

    2012-04-01

    The interpretation and communication of fire danger warning levels based on weather indices values are critical for fire management activities. In the framework of the EU Alpine Space Interreg-project ALP FFIRS (Alpine Forest Fire Warning System) we verified the response of several Fire Weather Indices with respect to the recorded forest fires in the last 10 years. To this purpose, we first set up a platform for sharing historical series of forest fire and weather data and we then developed a common evaluation technique of the fire weather indices skills on the basis of the following principles: a) to be non-parametric, in order to avoid the potential production of spurious results and b) to distinguish skills of several indices in different seasons and different areas. Our analysis demonstrates very clearly that there is no perfect index, the best performing one may change according to the region and the season considered. We also hypothesize that a single index may only partially describe the fire danger and a combination of indices may be of great benefit for establishing a suitable a Fire Danger Rating system in the Alpine context. The study will provide the forest fire suppression services an objective analysis of fire danger systems at the Alpine area scale and contribute to the creation of a common Alpine Forest Fire Danger Scale, even if the regional services will use different fire weather indices.

  2. Measuring the firing rate of high-resistance neurons with cell-attached recording.

    PubMed

    Alcami, Pepe; Franconville, Romain; Llano, Isabel; Marty, Alain

    2012-02-29

    Cell-attached recording is extensively used to study the firing rate of mammalian neurons, but potential limitations of the method have not been investigated in detail. Here we perform cell-attached recording of molecular layer interneurons in cerebellar slices from rats and mice, and we study how experimental conditions influence the measured firing rate. We find that this rate depends on time in cell-attached mode, on pipette potential, and on pipette ionic composition. In the first minute after sealing, action currents are variable in shape and size, presumably reflecting membrane instability. The firing rate remains approximately constant during the first 4 min after sealing and gradually increases afterward. Making the pipette potential more positive leads to an increase in the firing rate, with a steeper dependence on voltage if the pipette solution contains K(+) as the main cation than if it contains Na(+). Ca(2+) imaging experiments show that establishing a cell-attached recording can result in an increased somatic Ca(2+) concentration, reflecting an increased firing rate linked to an increase in the pipette-cell conductance. Pipette effects on cell firing are traced to a combination of passive electrical coupling, opening of voltage- and Ca(2+)-sensitive K(+) channels (BK channels) after action potentials, and random activation of voltage-insensitive, presumably mechanosensitive, cationic channels. We conclude that, unless experimental conditions are optimized, cell-attached recordings in small neurons may report erroneous firing rates.

  3. Error associated with model predictions of wildland fire rate of spread

    Treesearch

    Miguel G. Cruz; Martin E. Alexander

    2015-01-01

    How well can we expect to predict the spread rate of wildfires and prescribed fires? The degree of accuracy in model predictions of wildland fire behaviour characteristics are dependent on the model's applicability to a given situation, the validity of the model's relationships, and the reliability of the model input data (Alexander and Cruz 2013b#. We...

  4. Measuring fire spread rates from repeat pass airborne thermal infrared imagery

    Treesearch

    Douglas A. Stow; Philip J. Riggan; Emanual A. Storey; Lloyd L. Coulter

    2014-01-01

    The objective is to evaluate procedures for direct measurement of fire spread rates (FSRs) based on archived repeat pass airborne thermal infrared (ATIR) imagery and to identify requirements for more refined measurements of FSR and environmental factors that influence FSR. Flaming front positions are delineated on sequential FireMapper ATIR images captured at...

  5. Burning rate of merged pool fire on the hollow square tray.

    PubMed

    Wang, Changjian; Guo, Jin; Ding, Yanming; Wen, Jennifer; Lu, Shouxiang

    2015-06-15

    In order to characterize fire merging, pool fires on hollow trays with varying side lengths were burned under quasi-quiescent condition and in a wind tunnel with the wind speed ranging from 0m/s to 7.5m/s. Burning rate and flame images were recorded in the whole combustion process. The results show that even though the pool surface area was kept identical for hollow trays of different sizes, the measured burning rates and fire evolutions were found to be significantly different. Besides the five stages identified by previous studies, an extra stage, fire merging, was observed. Fire merging appeared possibly at any of the first four stages and moreover resulted in 50-100% increases of the fire burning rates and heights in the present tests. The tests in wind tunnel suggested that, as the wind speed ranges from 0 m/s to 2 m/s, the burning rates decrease. However with further increase of the wind speed from 2 m/s to 7.5 m/s, the burning rate was found to increase for smaller hollow trays while it remains almost constant for larger hollow trays. Two empirical correlations are presented to predict critical burning rate of fire merging on the hollow tray. The predictions were found to be in reasonably good agreement with the measurements. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. The effect of spinal and skin temperatures on the firing rate and thermosensitivity of preoptic neurones

    PubMed Central

    Boulant, J. A.; Hardy, J. D.

    1974-01-01

    1. In anaesthetized rabbits, preoptic single unit activity was recorded while preoptic, spinal cord and skin temperatures were independently manipulated. 2. The units that were insensitive to preoptic temperature were characterized by low firing rates and also by a very low incidence of extrahypothalamic thermosensitivity. 3. Thirty-seven units having positive coefficients to preoptic temperature were tested for their response to spinal or skin temperature. Of these, twenty-two units responded to extrahypothalamic temperature, seventeen with positive thermal coefficients. In addition, the incidence of extrahypothalamic thermosensitivity generally increased among the higher firing units. 4. Twenty-two units had negative coefficients for preoptic temperature and were tested for their extrahypothalamic thermosensitivities. Of these, sixteen units had dual thermosensitivities, ten with negative coefficients for the extrahypothalamic temperatures. In addition, there was no correlation between the incidence of extrahypothalamic thermosensitivity and the level of firing rate. 5. In the units having positive coefficients for preoptic temperature, an increased firing rate, due to extrahypothalamic temperature, generally resulted in a decreased preoptic thermosensitivity. Conversely, a decreased firing rate usually resulted in an increased preoptic thermosensitivity. 6. In the units having negative coefficients for preoptic temperature, an increased firing rate, due to extrahypothalamic temperature, usually increased the preoptic thermosensitivity; while a decreased firing rate tended to decrease the sensitivity to preoptic temperature. PMID:4416218

  7. Effects of high-rate electrical stimulation upon firing in modelled and real neurons.

    PubMed

    Krauthamer, V; Crosheck, T

    2002-05-01

    Many medical devices use high-rate, low-amplitude currents to affect neural function. This study examined the effect of stimulation rate upon action potential threshold and sustained firing rate for two model neurons, the rabbit myelinated fibre and the unmyelinated leech touch sensory cell. These model neurons were constructed with the NEURON simulator from electrophysiological data. Alternating-phase current pulses (0-1250 Hz), of fixed phase duration (0.2 ms), were used to stimulate the neurons, and propagation success or failure was measured. One effect of the high pulse rates was to cause a net depolarisation, and this was verified by the relief of action potential conduction block by 500 Hz extracellular stimulation in leech neurons. The models also predicted that the neurons would maintain maximum sustained firing at a number of different stimulation rates. For example, at twice threshold, the myelinated model followed the stimulus up to 500 Hz stimulation, half the stimulus rate up to 850 Hz stimulation, and it did not fire at 1250 Hz stimulation. By contrast, the unmyelinated neuron model had a lower maximum firing rate of 190 Hz, and this rate was obtained at a number of stimulation rates, up to 1250 Hz. The myelinated model also predicted sustained firing with 1240 Hz stimulation at threshold current, but no firing when the current level was doubled. Most of these effects are explained by the interaction of stimulus pulses with the cell's refractory period.

  8. Towards improving wildland firefighter situational awareness through daily fire behaviour risk assessments in the US Northern Rockies and Northern Great Basin

    Treesearch

    W. Matt Jolly; Patrick H. Freeborn

    2017-01-01

    Wildland firefighters must assess potential fire behaviour in order to develop appropriate strategies and tactics that will safely meet objectives. Fire danger indices integrate surface weather conditions to quantify potential variations in fire spread rates and intensities and therefore should closely relate to observed fire behaviour. These indices could better...

  9. Fuel models and fire potential from satellite and surface observations

    USGS Publications Warehouse

    Burgan, R.E.; Klaver, R.W.; Klarer, J.M.

    1998-01-01

    A national 1-km resolution fire danger fuel model map was derived through use of previously mapped land cover classes and ecoregions, and extensive ground sample data, then refined through review by fire managers familiar with various portions of the U.S. The fuel model map will be used in the next generation fire danger rating system for the U.S., but it also made possible immediate development of a satellite and ground based fire potential index map. The inputs and algorithm of the fire potential index are presented, along with a case study of the correlation between the fire potential index and fire occurrence in California and Nevada. Application of the fire potential index in the Mediterranean ecosystems of Spain, Chile, and Mexico will be tested.

  10. Determine Neuronal Tuning Curves by Exploring Optimum Firing Rate Distribution for Information Efficiency

    PubMed Central

    Han, Fang; Wang, Zhijie; Fan, Hong

    2017-01-01

    This paper proposed a new method to determine the neuronal tuning curves for maximum information efficiency by computing the optimum firing rate distribution. Firstly, we proposed a general definition for the information efficiency, which is relevant to mutual information and neuronal energy consumption. The energy consumption is composed of two parts: neuronal basic energy consumption and neuronal spike emission energy consumption. A parameter to model the relative importance of energy consumption is introduced in the definition of the information efficiency. Then, we designed a combination of exponential functions to describe the optimum firing rate distribution based on the analysis of the dependency of the mutual information and the energy consumption on the shape of the functions of the firing rate distributions. Furthermore, we developed a rapid algorithm to search the parameter values of the optimum firing rate distribution function. Finally, we found with the rapid algorithm that a combination of two different exponential functions with two free parameters can describe the optimum firing rate distribution accurately. We also found that if the energy consumption is relatively unimportant (important) compared to the mutual information or the neuronal basic energy consumption is relatively large (small), the curve of the optimum firing rate distribution will be relatively flat (steep), and the corresponding optimum tuning curve exhibits a form of sigmoid if the stimuli distribution is normal. PMID:28270760

  11. Determine Neuronal Tuning Curves by Exploring Optimum Firing Rate Distribution for Information Efficiency.

    PubMed

    Han, Fang; Wang, Zhijie; Fan, Hong

    2017-01-01

    This paper proposed a new method to determine the neuronal tuning curves for maximum information efficiency by computing the optimum firing rate distribution. Firstly, we proposed a general definition for the information efficiency, which is relevant to mutual information and neuronal energy consumption. The energy consumption is composed of two parts: neuronal basic energy consumption and neuronal spike emission energy consumption. A parameter to model the relative importance of energy consumption is introduced in the definition of the information efficiency. Then, we designed a combination of exponential functions to describe the optimum firing rate distribution based on the analysis of the dependency of the mutual information and the energy consumption on the shape of the functions of the firing rate distributions. Furthermore, we developed a rapid algorithm to search the parameter values of the optimum firing rate distribution function. Finally, we found with the rapid algorithm that a combination of two different exponential functions with two free parameters can describe the optimum firing rate distribution accurately. We also found that if the energy consumption is relatively unimportant (important) compared to the mutual information or the neuronal basic energy consumption is relatively large (small), the curve of the optimum firing rate distribution will be relatively flat (steep), and the corresponding optimum tuning curve exhibits a form of sigmoid if the stimuli distribution is normal.

  12. Can standard surface EMG processing parameters be used to estimate motor unit global firing rate?

    NASA Astrophysics Data System (ADS)

    Zhou, Ping; Zev Rymer, William

    2004-06-01

    The relations between motor unit global firing rates and established quantitative measures for processing the surface electromyogram (EMG) signals were explored using a simulation approach. Surface EMG signals were simulated using the reported properties of the first dorsal interosseous muscle in man, and the models were varied systematically, using several hypothetical relations between motor unit electrical and force output, and also using different motor unit firing rate strategies. The utility of using different EMG processing parameters to help estimate global motor unit firing rate was evaluated based on their relations to the number of motor unit action potentials (MUAPs) in the simulated surface EMG signals. Our results indicate that the relation between motor unit electrical and mechanical properties, and the motor unit firing rate scheme are all important factors determining the form of the relation between surface EMG amplitude and motor unit global firing rate. Conversely, these factors have less impact on the relations between turn or zero-crossing point counts and the number of MUAPs in surface EMG. We observed that the number of turn or zero-crossing points tends to saturate with the increase in the MUAP number in surface EMG, limiting the utility of these measures as estimates of MUAP number. The simulation results also indicate that the mean or median frequency of the surface EMG power spectrum is a poor indicator of the global motor unit firing rate.

  13. Motor unit firing rate patterns during voluntary muscle force generation: a simulation study

    NASA Astrophysics Data System (ADS)

    Hu, Xiaogang; Rymer, William Z.; Suresh, Nina L.

    2014-04-01

    Objective. Muscle force is generated by a combination of motor unit (MU) recruitment and changes in the discharge rate of active MUs. There have been two basic MU recruitment and firing rate paradigms reported in the literature, which describe the control of the MUs during force generation. The first (termed the reverse ‘onion skin’ profile), exhibits lower firing rates for lower threshold units, with higher firing rates occurring in higher threshold units. The second (termed the ‘onion skin’ profile), exhibits an inverse arrangement, with lower threshold units reaching higher firing rates. Approach. Using a simulation of the MU activity in a hand muscle, this study examined the force generation capacity and the variability of the muscle force magnitude at different excitation levels of the MU pool under these two different MU control paradigms. We sought to determine which rate/recruitment scheme was more efficient for force generation, and which scheme gave rise to the lowest force variability. Main results. We found that the force output of both firing patterns leads to graded force output at low excitation levels, and that the force generation capacity of the two different paradigms diverged around 50% excitation. In the reverse ‘onion skin’ pattern, at 100% excitation, the force output reached up to 88% of maximum force, whereas for the ‘onion skin’ pattern, the force output only reached up to 54% of maximum force at 100% excitation. The force variability was lower at the low to moderate force levels under the ‘onion skin’ paradigm than with the reverse ‘onion skin’ firing patterns, but this effect was reversed at high force levels. Significance. This study captures the influence of MU recruitment and firing rate organization on muscle force properties, and our results suggest that the different firing organizations can be beneficial at different levels of voluntary muscle force generation and perhaps for different tasks.

  14. Enclosure fire hazard analysis using relative energy release criteria. [burning rate and combustion control

    NASA Technical Reports Server (NTRS)

    Coulbert, C. D.

    1978-01-01

    A method for predicting the probable course of fire development in an enclosure is presented. This fire modeling approach uses a graphic plot of five fire development constraints, the relative energy release criteria (RERC), to bound the heat release rates in an enclosure as a function of time. The five RERC are flame spread rate, fuel surface area, ventilation, enclosure volume, and total fuel load. They may be calculated versus time based on the specified or empirical conditions describing the specific enclosure, the fuel type and load, and the ventilation. The calculation of these five criteria, using the common basis of energy release rates versus time, provides a unifying framework for the utilization of available experimental data from all phases of fire development. The plot of these criteria reveals the probable fire development envelope and indicates which fire constraint will be controlling during a criteria time period. Examples of RERC application to fire characterization and control and to hazard analysis are presented along with recommendations for the further development of the concept.

  15. 33 CFR 126.27 - General permit for handling dangerous cargo.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... be arranged in a manner that retards the spread of fire, such as by interspersing dangerous cargo with inert or fire retardant material. (k) Dangerous cargo stored on the facility, but not intended...

  16. A variable fork rate affects timing of origin firing and S phase dynamics in Saccharomyces cerevisiae.

    PubMed

    Supady, Adriana; Klipp, Edda; Barberis, Matteo

    2013-10-20

    Activation (in the following referred to as firing) of replication origins is a continuous and irreversible process regulated by availability of DNA replication molecules and cyclin-dependent kinase activities, which are often altered in human cancers. The temporal, progressive origin firing throughout S phase appears as a characteristic replication profile, and computational models have been developed to describe this process. Although evidence from yeast to human indicates that a range of replication fork rates is observed experimentally in order to complete a timely S phase, those models incorporate velocities that are uniform across the genome. Taking advantage of the availability of replication profiles, chromosomal position and replication timing, here we investigated how fork rate may affect origin firing in budding yeast. Our analysis suggested that patterns of origin firing can be observed from a modulation of the fork rate that strongly correlates with origin density. Replication profiles of chromosomes with a low origin density were fitted with a variable fork rate, whereas for the ones with a high origin density a constant fork rate was appropriate. This indeed supports the previously reported correlation between inter-origin distance and fork rate changes. Intriguingly, the calculated correlation between fork rate and timing of origin firing allowed the estimation of firing efficiencies for the replication origins. This approach correctly retrieved origin efficiencies previously determined for chromosome VI and provided testable prediction for other chromosomal origins. Our results gain deeper insights into the temporal coordination of genome duplication, indicating that control of the replication fork rate is required for the timely origin firing during S phase. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Firing rate dynamics in recurrent spiking neural networks with intrinsic and network heterogeneity.

    PubMed

    Ly, Cheng

    2015-12-01

    Heterogeneity of neural attributes has recently gained a lot of attention and is increasing recognized as a crucial feature in neural processing. Despite its importance, this physiological feature has traditionally been neglected in theoretical studies of cortical neural networks. Thus, there is still a lot unknown about the consequences of cellular and circuit heterogeneity in spiking neural networks. In particular, combining network or synaptic heterogeneity and intrinsic heterogeneity has yet to be considered systematically despite the fact that both are known to exist and likely have significant roles in neural network dynamics. In a canonical recurrent spiking neural network model, we study how these two forms of heterogeneity lead to different distributions of excitatory firing rates. To analytically characterize how these types of heterogeneities affect the network, we employ a dimension reduction method that relies on a combination of Monte Carlo simulations and probability density function equations. We find that the relationship between intrinsic and network heterogeneity has a strong effect on the overall level of heterogeneity of the firing rates. Specifically, this relationship can lead to amplification or attenuation of firing rate heterogeneity, and these effects depend on whether the recurrent network is firing asynchronously or rhythmically firing. These observations are captured with the aforementioned reduction method, and furthermore simpler analytic descriptions based on this dimension reduction method are developed. The final analytic descriptions provide compact and descriptive formulas for how the relationship between intrinsic and network heterogeneity determines the firing rate heterogeneity dynamics in various settings.

  18. On the Firing Rate Dependency of the Phase Response Curve of Rat Purkinje Neurons In Vitro

    PubMed Central

    Couto, João; Linaro, Daniele; De Schutter, E; Giugliano, Michele

    2015-01-01

    Synchronous spiking during cerebellar tasks has been observed across Purkinje cells: however, little is known about the intrinsic cellular mechanisms responsible for its initiation, cessation and stability. The Phase Response Curve (PRC), a simple input-output characterization of single cells, can provide insights into individual and collective properties of neurons and networks, by quantifying the impact of an infinitesimal depolarizing current pulse on the time of occurrence of subsequent action potentials, while a neuron is firing tonically. Recently, the PRC theory applied to cerebellar Purkinje cells revealed that these behave as phase-independent integrators at low firing rates, and switch to a phase-dependent mode at high rates. Given the implications for computation and information processing in the cerebellum and the possible role of synchrony in the communication with its post-synaptic targets, we further explored the firing rate dependency of the PRC in Purkinje cells. We isolated key factors for the experimental estimation of the PRC and developed a closed-loop approach to reliably compute the PRC across diverse firing rates in the same cell. Our results show unambiguously that the PRC of individual Purkinje cells is firing rate dependent and that it smoothly transitions from phase independent integrator to a phase dependent mode. Using computational models we show that neither channel noise nor a realistic cell morphology are responsible for the rate dependent shift in the phase response curve. PMID:25775448

  19. Fire extinguishers for manned spacecraft

    NASA Astrophysics Data System (ADS)

    Kopylov, S.; Smirnov, N. V.; Tanklevsky, L. T.

    2015-04-01

    Based on an analysis of fires in the oxygen-enriched atmosphere conditions in spacecraft and other sealed chambers of various purposes, the most dangerous groups of fires are identified. For this purpose, groups were compiled to analyze dependences that describe the increase of fire hazard to a critical value. A criterion for determining timely and effective fire extinguishing was offered. Fire experiments in oxygen-enriched atmosphere conditions were conducted, and an array of experimental data on the mass burning rate of materials and their extinguishing by water mist was obtained. Relationships colligating an array of experimental data were offered. Experimental and analytical studies were taken as a basis for hand fire extinguisher implementation for manned spacecraft.

  20. Do additional inputs change maximal voluntary motor unit firing rates after spinal cord injury?

    PubMed

    Zijdewind, Inge; Gant, Katie; Bakels, Rob; Thomas, Christine K

    2012-01-01

    Motor unit firing frequencies are low during maximal voluntary contractions (MVCs) of human thenar muscles impaired by cervical spinal cord injury (SCI). This study aimed to examine whether thenar motor unit firing frequencies increase when driven by both maximal voluntary drive and other concurrent inputs compared with an MVC alone. Motor unit firing rates, force, and surface electromyographic activity (EMG) were compared across 2 contractions: (a) MVC alone and (b) MVC combined with another input (combination contraction). Other inputs (conditions) included vibration, heat, or cold applied to the anterior surface of the forearm, electrical stimulation delivered to the anterior surface of the middle finger, a muscle spasm, or a voluntary contraction of the contralateral thenar muscles against resistance. The maximal firing frequency (n = 68 units), force, and electromyographic activity (n = 92 contraction pairs) were all significantly higher during the combined contractions compared with MVCs alone. There was a 3-way interaction between contraction, condition, and subject for maximal motor unit firing rates, force, and EMG. Thus, combined contraction responses were different for conditions across subjects. Some conditions (eg, a muscle spasm) resulted in more effective and more frequent responses (increases in unit firing frequency, force, EMG in >50% contractions) than others. Recruitment of new units also occurred in combined contractions. Motoneurons are still responsive to additional afferent inputs from various sources when rate modulation from voluntary drive is limited by SCI. Individuals with SCI may be able to combine inputs to control functional tasks they cannot perform with voluntary drive alone.

  1. Detecting location-specific neuronal firing rate increases in the hippocampus of freely-moving monkeys.

    PubMed

    Ludvig, Nandor; Tang, Hai M; Gohil, Baiju C; Botero, Juan M

    2004-07-16

    The spatial properties of the firing of hippocampal neurons have mainly been studied in (a) freely moving rodents, (b) non-human primates seated in a moveable primate chair with head fixed, and (c) epileptic patients subjected to virtual navigation. Although these studies have all revealed the ability of hippocampal neurons to generate spatially selective discharges, the detected firing patterns have been found to be considerably different, even conflicting, in many respects. The present cellular electrophysiological study employed squirrel monkeys (Saimiri sciureus), which moved freely on the walls and floor of a large test chamber. This permitted the examination of the spatial firing of hippocampal neurons in nearly ideal conditions, similar to those used in rodents, yet in a species that belongs to the primate Suborder Anthropoidea. The major findings were that: (1) a group of slow-firing complex-spike cells increased their basal, awake firing rate more than 20-fold, often above 30 spikes/s, when the monkey was in a particular location in the chamber, (2) these location-specific discharges occurred consistently, forming 4-25 s action potential volleys, and (3) fast-firing cells displayed no such electrical activity. Thus, during free movement in three dimensions, primate hippocampal complex-spike cells do generate high-frequency, location-specific action potential volleys. Since these cells are components of the medial temporal lobe memory system, their uncovered firing pattern may well be involved in the formation of declarative memories on places.

  2. Dynamics of excitatory synaptic components in sustained firing at low rates.

    PubMed

    Wyart, Claire; Cocco, Simona; Bourdieu, Laurent; Léger, Jean-Francois; Herr, Catherine; Chatenay, Didier

    2005-06-01

    Sustained firing is necessary for the persistent activity associated with working memory. The relative contributions of the reverberation of excitation and of the temporal dynamics of the excitatory postsynaptic potential (EPSP) to the maintenance of activity are difficult to evaluate in classical preparations. We used simplified models of synchronous excitatory networks, hippocampal autapses and pairs, to study the synaptic mechanisms underlying firing at low rates. Calcium imaging and cell attached recordings showed that these neurons spontaneously fired bursts of action potentials that lasted for seconds over a wide range of frequencies. In 2-wk-old cells, the median firing frequency was low (11 +/- 8.8 Hz), whereas in 3- to 4-wk-old cells, it decreased to a very low value (2 +/- 1.3 Hz). In both cases, we have shown that the slowest synaptic component supported firing. In 2-wk-old autapses, antagonists of N-methyl-d-aspartate receptors (NMDARs) induced rare isolated spikes showing that the NMDA component of the EPSP was essential for bursts at low frequency. In 3- to 4-wk-old neurons, the very low frequency firing was maintained without the NMDAR activation. However EGTA-AM or alpha-methyl-4-carboxyphenylglycine (MCPG) removed the very slow depolarizing component of the EPSP and prevented the sustained firing at very low rate. A metabotropic glutamate receptor (mGluR)-activated calcium sensitive conductance is therefore responsible for a very slow synaptic component associated with firing at very low rate. In addition, our observations suggested that the asynchronous release of glutamate might participate also in the recurring bursting.

  3. Methods for Estimating Neural Firing Rates, and Their Application to Brain-Machine Interfaces

    PubMed Central

    Cunningham, John P.; Gilja, Vikash; Ryu, Stephen I.; Shenoy, Krishna V.

    2009-01-01

    Neural spike trains present analytical challenges due to their noisy, spiking nature. Many studies of neuroscientific and neural prosthetic importance rely on a smoothed, denoised estimate of a spike train's underlying firing rate. Numerous methods for estimating neural firing rates have been developed in recent years, but to date no systematic comparison has been made between them. In this study, we review both classic and current firing rate estimation techniques. We compare the advantages and drawbacks of these methods. Then, in an effort to understand their relevance to the field of neural prostheses, we also apply these estimators to experimentally-gathered neural data from a prosthetic arm-reaching paradigm. Using these estimates of firing rate, we apply standard prosthetic decoding algorithms to compare the performance of the different firing rate estimators, and, perhaps surprisingly, we find minimal differences. This study serves as a review of available spike train smoothers and a first quantitative comparison of their performance for brain-machine interfaces. PMID:19349143

  4. Reflex origin for the slowing of motoneurone firing rates in fatigue of human voluntary contractions.

    PubMed Central

    Bigland-Ritchie, B R; Dawson, N J; Johansson, R S; Lippold, O C

    1986-01-01

    During fatigue from a sustained maximal voluntary contraction (m.v.c.) the mean motoneurone discharge rates decline. In the present experiments we found no recovery of firing rates after 3 min of rest if the fatigued muscle was kept ischaemic, but near full recovery 3 min after the blood supply was restored. Since 3 min is thus sufficient time for recovery of any central changes in excitability, the results support the hypothesis that, during fatigue, motoneurone firing rates may be regulated by a peripheral reflex originating in response to fatigue-induced changes within the muscle. PMID:3560001

  5. Experience-dependent firing rate remapping generates directional selectivity in hippocampal place cells

    PubMed Central

    Navratilova, Zaneta; Hoang, Lan T.; Schwindel, C. Daniela; Tatsuno, Masami; McNaughton, Bruce L.

    2012-01-01

    When rodents engage in irregular foraging in an open-field environment, hippocampal principal cells exhibit place-specific firing that is statistically independent of the direction of traverse through the place field. When the path is restricted to a track, however, in-field rates differ substantially in opposite directions. Frequently, the representations of the track in the two directions are essentially orthogonal. We show that this directionally selective firing is not hard-wired, but develops through experience-dependent plasticity. During the rats' first pass in each direction, place fields were highly directionally symmetric, whereas over subsequent laps, the firing rates in the two directions gradually but substantially diverged. We conclude that, even on a restricted track, place cell firing is initially determined by allocentric position, and only later, the within-field firing rates change in response to differential sensory information or behavioral cues in the two directions. In agreement with previous data, place fields near local cues, such as textures on the track, developed less directionality than place fields on a uniform part of the track, possibly because the local cues reduced the net difference in sensory input at a given point. Directionality also developed in an open environment without physical restriction of the animal's path, when rats learned to run along a specified path. In this case, directionality developed later than on the running track, only after the rats began to run in a stereotyped manner. Although the average population firing rates exhibited little if any change over laps in either direction, the direction-specific firing rates in a given place field were up-or down-regulated with about equal probability and magnitude, which was independent in the two directions, suggesting some form of competitive mechanism (e.g., LTP/LTD) acting coherently on the set of synapses conveying external information to each cell. PMID:22363267

  6. [Fire behavior of Mongolian oak leaves fuel-bed under no-wind and zero-slope conditions. I. Factors affecting fire spread rate and modeling].

    PubMed

    Jin, Sen; Liu, Bo-Fei; Di, Xue-Ying; Chu, Teng-Fei; Zhang, Ji-Li

    2012-01-01

    Aimed to understand the fire behavior of Mongolian oak leaves fuel-bed under field condition, the leaves of a secondary Mongolian oak forest in Northeast Forestry University experimental forest farm were collected and brought into laboratory to construct fuel-beds with varied loading, height, and moisture content, and a total of 100 experimental fires were burned under no-wind and zero-slope conditions. It was observed that the fire spread rate of the fuel-beds was less than 0.5 m x min(-1). Fuel-bed loading, height, and moisture contents all had significant effects on the fire spread rate. The effect of fuel-bed moisture content on the fire spread had no significant correlations with fuel-bed loading and height, but the effect of fuel-bed height was related to the fuel-bed loading. The packing ratio of fuel-beds had less effect on the fire spread rate. Taking the fuel-bed loading, height, and moisture content as predictive variables, a prediction model for the fire spread rate of Mongolian oak leaves fuel-bed was established, which could explain 83% of the variance of the fire spread rate, with a mean absolute error 0.04 m x min(-1) and a mean relative error less than 17%.

  7. Air tankers in Southern California Fires...effectiveness in delivering retardants rated

    Treesearch

    Theodore G. Storey; Leon W. Cooley

    1967-01-01

    Eleven air attack experts were asked to rate 12 models of fixed-wing tankers and light helitankers for effectiveness ill delivering chemical fire retardants under 21 typical situations. They rated fixed-wing tankers as more effective in strong wind crosswinds, and downwind approaches, but helitankers as more effective in narrow canyons and on steep slopes. Certain...

  8. [Dangerous aquaria].

    PubMed

    Satora, Leszek; Morawska, Jowanka; Szkolnicka, Beata; Mitrus, Małgorzata; Targosz, Dorota; Gwiazdowski, Andrzej

    2005-01-01

    World trends for a home breeding of exotic freshwater and marine fishes did not miss Poland. There are almost all species of aquarium fishes available in Polish pet shops, but there is not enough information about threat given to customers. In some fish, there are masses of one-cell glands, mainly serous, in the proximity of the spines. In others, those one-cell glands may be grouped in larger aggregates of cells called venom glands, that may form organs resembling multicellular glands of terrestrial animals. They are usually located around the spines or hard rays of the fins. Even if covered with a connective tissue sheath, the aggregates of the venom cells do not have any common outlet; they are not, therefore, proper multicellular glands. The venom glands of the catfish are covered with a thin sheath and they release their contents when the fin ray is pressed. Spines are derived from fin rays. When the spine penetrates the body of its prey, it presses its base against the cells, squashes them and squeezes the venomous contents into the wound. Catfish, lionfish and stonefish have the venom glands producing secretion which could be dangerous. The eels and morays blood is also dangerous, as well as slime of reduced squamae. Poison information centers noted several cases of fishes' stings in Poland.

  9. Influence of proprioceptive feedback on the firing rate and recruitment of motoneurons

    PubMed Central

    De Luca, C J; Kline, J C

    2012-01-01

    We investigated the relationships of the firing rate and maximal recruitment threshold of motoneurons recorded during isometric contraction with the number of spindles in individual muscles. At force levels above 10% of maximal voluntary contraction, the firing rate was inversely related to the number of spindles in a muscle, with the slope of the relationship increasing with force. The maximal recruitment threshold of motor units increased linearly with the number of spindles in the muscle. Thus, muscles with a greater number of spindles had lower firing rates and a greater maximal recruitment threshold. These findings may be explained by a mechanical interaction between muscle fibres and adjacent spindles. During low-level (0 to 10%) voluntary contractions, muscle fibres of recruited motor units produce force-twitches that activate nearby spindles to respond with an immediate excitatory feedback that reaches maximal level. As the force increases further, the twitches overlap and tend towards tetanization, the muscle fibres shorten, the spindles slacken, their excitatory firings decrease, and the net excitation to the homonymous motoneurons decreases. Motoneurons of muscles with greater number of spindles receive a greater decrease in excitation which reduces their firing rates, increases their maximal recruitment threshold, and changes the motoneuron recruitment distribution. PMID:22183300

  10. Influence of proprioceptive feedback on the firing rate and recruitment of motoneurons.

    PubMed

    De Luca, C J; Kline, J C

    2012-02-01

    We investigated the relationships of the firing rate and maximal recruitment threshold of motoneurons recorded during isometric contraction with the number of spindles in individual muscles. At force levels above 10% of maximal voluntary contraction, the firing rate was inversely related to the number of spindles in a muscle, with the slope of the relationship increasing with force. The maximal recruitment threshold of motor units increased linearly with the number of spindles in the muscle. Thus, muscles with a greater number of spindles had lower firing rates and a greater maximal recruitment threshold. These findings may be explained by a mechanical interaction between muscle fibres and adjacent spindles. During low-level (0% to 10%) voluntary contractions, muscle fibres of recruited motor units produce force twitches that activate nearby spindles to respond with an immediate excitatory feedback that reaches maximal level. As the force increases further, the twitches overlap and tend towards tetanization, the muscle fibres shorten, the spindles slacken, their excitatory firings decrease, and the net excitation to the homonymous motoneurons decreases. Motoneurons of muscles with greater number of spindles receive a greater decrease in excitation which reduces their firing rates, increases their maximal recruitment threshold, and changes the motoneuron recruitment distribution.

  11. Influence of proprioceptive feedback on the firing rate and recruitment of motoneurons

    NASA Astrophysics Data System (ADS)

    De Luca, C. J.; Kline, J. C.

    2012-02-01

    We investigated the relationships of the firing rate and maximal recruitment threshold of motoneurons recorded during isometric contraction with the number of spindles in individual muscles. At force levels above 10% of maximal voluntary contraction, the firing rate was inversely related to the number of spindles in a muscle, with the slope of the relationship increasing with force. The maximal recruitment threshold of motor units increased linearly with the number of spindles in the muscle. Thus, muscles with a greater number of spindles had lower firing rates and a greater maximal recruitment threshold. These findings may be explained by a mechanical interaction between muscle fibres and adjacent spindles. During low-level (0% to 10%) voluntary contractions, muscle fibres of recruited motor units produce force twitches that activate nearby spindles to respond with an immediate excitatory feedback that reaches maximal level. As the force increases further, the twitches overlap and tend towards tetanization, the muscle fibres shorten, the spindles slacken, their excitatory firings decrease, and the net excitation to the homonymous motoneurons decreases. Motoneurons of muscles with greater number of spindles receive a greater decrease in excitation which reduces their firing rates, increases their maximal recruitment threshold, and changes the motoneuron recruitment distribution.

  12. Millimeter waves thermally alter the firing rate of the Lymnaea pacemaker neuron

    SciTech Connect

    Alekseev, S.I.; Kochetkova, N.V.; Ziskin, M.C.; Bolshakov, M.A.

    1997-05-01

    The effects of millimeter waves (mm-waves, 75 GHz) and temperature elevation on the firing rate of the BP-4 pacemaker neuron of the pond snail Lymnaea stagnalis were studied by using microelectrode techniques. The open end of a rectangular waveguide covered with a thin Teflon film served as a radiator. Specific absorption rates (SARs), measured in physiological solution at the radiator outlet, ranged from 600 to 4,200 W/kg, causing temperature rises from 0.3 to 2.2 C, respectively. Irradiation at an SAR of 4,200 W/kg caused a biphasic change in the firing rate, i.e., a transient decrease in the firing rate followed by a gradual increase to a new level that was 68 {+-} 21% above control. The biphasic changes in the firing rate were reproduced by heating under the condition that the magnitude (2 C) and the rate of temperature rise were equal to those produced by the irradiation. The addition of 0.05 mM of ouabain caused the disappearance of transient responses of the neuron to the irradiation. It was shown that the rate of temperature rise played an important role in the development of a transient neuronal response. The threshold stimulus for a transient response of the BP-4 neutron found in warming experiments was a temperature rise of 0.0025 C/s.

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

    PubMed Central

    Rössert, Christian; Solinas, Sergio; D'Angelo, Egidio; Dean, Paul; Porrill, John

    2014-01-01

    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 modeling 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-fiber 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-fiber 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. PMID:25352777

  14. Tonic Firing Rate Controls Dendritic Ca2+ Signaling and Synaptic Gain in Substantia Nigra Dopamine Neurons

    PubMed Central

    Hage, Travis A.

    2015-01-01

    Substantia nigra dopamine neurons fire tonically resulting in action potential backpropagation and dendritic Ca2+ influx. Using Ca2+ imaging in acute mouse brain slices, we find a surprisingly steep relationship between tonic firing rate and dendritic Ca2+. Increasing the tonic rate from 1 to 6 Hz generated Ca2+ signals up to fivefold greater than predicted by linear summation of single spike-evoked Ca2+-transients. This “Ca2+ supralinearity” was produced largely by depolarization of the interspike voltage leading to activation of subthreshold Ca2+ channels and was present throughout the proximal and distal dendrites. Two-photon glutamate uncaging experiments show somatic depolarization enhances NMDA receptor-mediated Ca2+ signals >400 μm distal to the soma, due to unusually tight electrotonic coupling of the soma to distal dendrites. Consequently, we find that fast tonic firing intensifies synaptically driven burst firing output in dopamine neurons. These results show that modulation of background firing rate precisely tunes dendritic Ca2+ signaling and provides a simple yet powerful mechanism to dynamically regulate the gain of synaptic input. PMID:25855191

  15. Fire

    Treesearch

    John A. Stanturf; Scott L. Goodrick

    2013-01-01

    Key FindingsClimate forecasts indicate that the South’s spring and fall wildfire seasons will be extended.Prescribed fires, currently conducted on roughly a 3 to 5 year rotation across much of the South, would need to become more frequent if conditions become drier.Major wildfire events, such as the 2007...

  16. [Dangerous animals].

    PubMed

    Hasle, Gunnar

    2002-06-30

    As travellers seek ever more exotic destinations they are more likely to encounter dangerous animals. Compared to risks such as AIDS, traffic accidents and malaria, the risk is not so great; many travellers are, however, concerned about this and those who give pre-travel vaccines and advice should know something about it. This article is mainly based on medical and zoological textbooks. Venomous stings and bites may be prevented by adequate clothing and by keeping safe distance to the animals. Listening to those who live in the area is of course important. Travellers should not carry antisera with them, but antisera should be available at local hospitals. It should be borne in mind that plant eaters cause just as many deaths as large predators. In some cases it is necessary to carry a sufficiently powerful firearm.

  17. Current injection and receptor-mediated excitation produce similar maximal firing rates in hypoglossal motoneurons.

    PubMed

    Wakefield, Hilary E; Fregosi, Ralph F; Fuglevand, Andrew J

    2016-03-01

    The maximum firing rates of motoneurons (MNs), activated in response to synaptic drive, appear to be much lower than that elicited by current injection. It could be that the decrease in input resistance associated with increased synaptic activity (but not current injection) might blunt overall changes in membrane depolarization and thereby limit spike-frequency output. To test this idea, we recorded, in the same cells, maximal firing responses to current injection and to synaptic activation. We prepared 300 μm medullary slices in neonatal rats that contained hypoglossal MNs and used whole-cell patch-clamp electrophysiology to record their maximum firing rates in response to triangular-ramp current injections and to glutamate receptor-mediated excitation. Brief pressure pulses of high-concentration glutamate led to significant depolarization, high firing rates, and temporary cessation of spiking due to spike inactivation. In the same cells, we applied current clamp protocols that approximated the time course of membrane potential change associated with glutamate application and with peak current levels large enough to cause spike inactivation. Means (SD) of maximum firing rates obtained in response to glutamate application were nearly identical to those obtained in response to ramp current injection [glutamate 47.1 ± 12.0 impulses (imp)/s, current injection 47.5 ± 11.2 imp/s], even though input resistance was 40% less during glutamate application compared with current injection. Therefore, these data suggest that the reduction in input resistance associated with receptor-mediated excitation does not, by itself, limit the maximal firing rate responses in MNs. Copyright © 2016 the American Physiological Society.

  18. Striatal Input- and Rate-Dependent Effects of Muscarinic Receptors on Pallidal Firing

    PubMed Central

    Querejeta, Enrique; Alatorre, Alberto; Ríos, Alain; Barrientos, Rafael; Oviedo-Chávez, Aldo; Bobadilla-Lugo, Rosa Amalia; Delgado, Alfonso

    2012-01-01

    The globus pallidus (GP) plays a key role in the overall basal ganglia (BG) activity. Despite evidence of cholinergic inputs to GP, their role in the spiking activity of GP neurons has not received attention. We examine the effect of local activation and blockade of muscarinic receptors (MRs) in the spontaneous firing of GP neurons both in normal and ipsilateral striatum-lesioned rats. We found that activation of MRs produces heterogeneous responses in both normal and ipsilateral striatum-lesioned rats: in normal rats the response evoked by MRs depends on the predrug basal firing rate; the inhibition evoked by MRs is higher in normal rats than in striatum-lesioned rats; the number of neurons that undergo inhibition is lower in striatum-lesioned rats than in normal rats. Our data suggest that modulation of MRs in the GP depends on the firing rate before their activation and on the integrity of the striato-pallidal pathway. PMID:22654627

  19. Association between Residential Proximity to Fuel-Fired Power Plants and Hospitalization Rate for Respiratory Diseases

    PubMed Central

    Liu, Xiaopeng; Lessner, Lawrence

    2012-01-01

    Background: Air pollution is known to cause respiratory disease. Unlike motor vehicle sources, fuel-fired power plants are stationary. Objective: Using hospitalization data, we examined whether living near a fuel-fired power plant increases the likelihood of hospitalization for respiratory disease. Methods: Rates of hospitalization for asthma, acute respiratory infection (ARI), and chronic obstructive pulmonary disease (COPD) were estimated using hospitalization data for 1993–2008 from New York State in relation to data for residences near fuel-fired power plants. We also explored data for residential proximity to hazardous waste sites. Results: After adjusting for age, sex, race, median household income, and rural/urban residence, there were significant 11%, 15%, and 17% increases in estimated rates of hospitalization for asthma, ARI, and COPD, respectively, among individuals > 10 years of age living in a ZIP code containing a fuel-fired power plant compared with one that had no power plant. Living in a ZIP code with a fuel-fired power plant was not significantly associated with hospitalization for asthma or ARI among children < 10 years of age. Living in a ZIP code with a hazardous waste site was associated with hospitalization for all outcomes in both age groups, and joint effect estimates were approximately additive for living in a ZIP code that contained a fuel-fired power plant and a hazardous waste site. Conclusions: Our results are consistent with the hypothesis that exposure to air pollution from fuel-fired power plants and volatile compounds coming from hazardous waste sites increases the risk of hospitalization for respiratory diseases. PMID:22370087

  20. Bayesian active learning of neural firing rate maps with transformed gaussian process priors.

    PubMed

    Park, Mijung; Weller, J Patrick; Horwitz, Gregory D; Pillow, Jonathan W

    2014-08-01

    A firing rate map, also known as a tuning curve, describes the nonlinear relationship between a neuron's spike rate and a low-dimensional stimulus (e.g., orientation, head direction, contrast, color). Here we investigate Bayesian active learning methods for estimating firing rate maps in closed-loop neurophysiology experiments. These methods can accelerate the characterization of such maps through the intelligent, adaptive selection of stimuli. Specifically, we explore the manner in which the prior and utility function used in Bayesian active learning affect stimulus selection and performance. Our approach relies on a flexible model that involves a nonlinearly transformed gaussian process (GP) prior over maps and conditionally Poisson spiking. We show that infomax learning, which selects stimuli to maximize the information gain about the firing rate map, exhibits strong dependence on the seemingly innocuous choice of nonlinear transformation function. We derive an alternate utility function that selects stimuli to minimize the average posterior variance of the firing rate map and analyze the surprising relationship between prior parameterization, stimulus selection, and active learning performance in GP-Poisson models. We apply these methods to color tuning measurements of neurons in macaque primary visual cortex.

  1. Rate Dynamics of Leaky Integrate-and-Fire Neurons with Strong Synapses

    PubMed Central

    Nordlie, Eilen; Tetzlaff, Tom; Einevoll, Gaute T.

    2010-01-01

    Firing-rate models provide a practical tool for studying the dynamics of trial- or population-averaged neuronal signals. A wealth of theoretical and experimental studies has been dedicated to the derivation or extraction of such models by investigating the firing-rate response characteristics of ensembles of neurons. The majority of these studies assumes that neurons receive input spikes at a high rate through weak synapses (diffusion approximation). For many biological neural systems, however, this assumption cannot be justified. So far, it is unclear how time-varying presynaptic firing rates are transmitted by a population of neurons if the diffusion assumption is dropped. Here, we numerically investigate the stationary and non-stationary firing-rate response properties of leaky integrate-and-fire neurons receiving input spikes through excitatory synapses with alpha-function shaped postsynaptic currents for strong synaptic weights. Input spike trains are modeled by inhomogeneous Poisson point processes with sinusoidal rate. Average rates, modulation amplitudes, and phases of the period-averaged spike responses are measured for a broad range of stimulus, synapse, and neuron parameters. Across wide parameter regions, the resulting transfer functions can be approximated by a linear first-order low-pass filter. Below a critical synaptic weight, the cutoff frequencies are approximately constant and determined by the synaptic time constants. Only for synapses with unrealistically strong weights are the cutoff frequencies significantly increased. To account for stimuli with larger modulation depths, we combine the measured linear transfer function with the nonlinear response characteristics obtained for stationary inputs. The resulting linear–nonlinear model accurately predicts the population response for a variety of non-sinusoidal stimuli. PMID:21212832

  2. Detection, mapping and estimation of rate of spread of grass fires from southern African ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Wightman, J. M.

    1973-01-01

    Sequential band-6 imagery of the Zambesi Basin of southern Africa recorded substantial changes in burn patterns resulting from late dry season grass fires. One example from northern Botswana, indicates that a fire consumed approximately 70 square miles of grassland over a 24-hour period. Another example from western Zambia indicates increased fire activity over a 19-day period. Other examples clearly define the area of widespread grass fires in Angola, Botswana, Rhodesia and Zambia. From the fire patterns visible on the sequential portions of the imagery, and the time intervals involved, the rates of spread of the fires are estimated and compared with estimates derived from experimental burning plots in Zambia and Canada. It is concluded that sequential ERTS-1 imagery, of the quality studied, clearly provides the information needed to detect and map grass fires and to monitor their rates of spread in this region during the late dry season.

  3. Traveling Charge Gun Firings Using Very High Burning Rate Propellants

    DTIC Science & Technology

    1988-12-01

    21.5 grams. This gave a charge-to-mass ratio of approximately 1.6. Data acquisition is done on analog tape, which is later digitized and reduced by...fashion. Pressure historias indica e a decreasing mass generation rate as a function of burn time. As a consequence of these two observations and in order...Station, Indian Head, MD, December 1980. 11. Gough, P.S., "Extensions of BRLTC. A Code for the Digital Simulation of the Traveling Charge," Contract Report

  4. Variance in population firing rate as a measure of slow time-scale correlation

    PubMed Central

    Snyder, Adam C.; Morais, Michael J.; Smith, Matthew A.

    2013-01-01

    Correlated variability in the spiking responses of pairs of neurons, also known as spike count correlation, is a key indicator of functional connectivity and a critical factor in population coding. Underscoring the importance of correlation as a measure for cognitive neuroscience research is the observation that spike count correlations are not fixed, but are rather modulated by perceptual and cognitive context. Yet while this context fluctuates from moment to moment, correlation must be calculated over multiple trials. This property undermines its utility as a dependent measure for investigations of cognitive processes which fluctuate on a trial-to-trial basis, such as selective attention. A measure of functional connectivity that can be assayed on a moment-to-moment basis is needed to investigate the single-trial dynamics of populations of spiking neurons. Here, we introduce the measure of population variance in normalized firing rate for this goal. We show using mathematical analysis, computer simulations and in vivo data how population variance in normalized firing rate is inversely related to the latent correlation in the population, and how this measure can be used to reliably classify trials from different typical correlation conditions, even when firing rate is held constant. We discuss the potential advantages for using population variance in normalized firing rate as a dependent measure for both basic and applied neuroscience research. PMID:24367326

  5. Pseudacteon decapitating fly parasitism rates in fire ant colonies around Gainesville, Florida

    USDA-ARS?s Scientific Manuscript database

    In order to assess the impacts of phorid flies on fire ants in the Gainesville area, we collected 3 g of worker ants from 36 colonies. A total of 672 parasitized workers were recovered from the 36 colony samples. Confirmed parasitism rates ranged from 0-5% with an average of about 0.5%. Including c...

  6. Pre- and Post-Fire Infiltration Rates in a Montane Mixed Conifer Ecosystem

    NASA Astrophysics Data System (ADS)

    Kopp, E. S.; Pohlmann, M. A.; Jones, C. A.; Chorover, J.; Schaap, M. G.

    2013-12-01

    The NSF-funded Catalina-Jemez Critical Zone Observatory (CZO) studies couplings among hydrologic, lithologic, ecological, and geochemical dynamics in the Southwest U.S. The motivation to study this region is to understand and to develop predictive models of how slow changes and abrupt disturbances affect landscape evolution and water resources for growing urban populations. One of the prevalent disturbances in Southwestern forested ecosystems is fire, which can dramatically alter near surface hydraulic properties and cause large changes in hydrological response in catchments. This poster will present a unique data set of pre- and post-fire infiltration and subsurface data collected before and shortly after the June 2013 Thompson Ridge Fire near Redondo Peak in the Valles Caldera 10 miles north of Jemez Springs, NM. Single ring pre-fire infiltration measurements were taken in July 2011 at 22 different locations with high-precision GPS tags. Similar post-fire infiltration measurements were taken within 1 meter of spatial accuracy of the pre-fire measurements in July 2013. The near-surface soil was analyzed for texture and organic matter content at 53 GPS-referenced locations in 2011, and a more detailed soil analysis is currently being analyzed in the laboratory for the 22 infiltration sites (5 depth increments down to about 50 cm). Because of the recent nature of the burn and subsequent sampling, complete results from data analysis are not yet available, however, the poster will provide a statistical analysis among pre- and post fire infiltration rates, established burn intensity classes, and subsurface changes such as soil texture and organic matter content.

  7. Holocene fire regimes and treeline migration rates in sub-arctic Canada

    NASA Astrophysics Data System (ADS)

    Sulphur, Kyle C.; Goldsmith, Shantal A.; Galloway, Jennifer M.; Macumber, Andrew; Griffith, Fritz; Swindles, Graeme T.; Patterson, R. Timothy; Falck, Hendrik; Clark, Ian D.

    2016-10-01

    Holocene climate change resulted in major vegetation reorganization in sub-arctic Canada near modern treeline. However, little is known of the effects of long-term climate change on boreal forest composition and fire regimes below treeline in this region. We present a high-resolution vegetation and fire history from two sites within the modern boreal forest in the central Northwest Territories, Canada, to provide new insight on sub-arctic vegetation response to Holocene climate dynamics and the role of fire in boreal ecosystems. Palynological analysis of sediments retrieved from Waite and Danny's lakes (informal) is used to reconstruct regional vegetation dynamics and boreal fire regimes. The longer Danny's Lake record documents treeline expansion beginning at ca. 7430-7220 cal yr BP. Integration of our new data with previous work shows that treeline expanded between ca. 4050 cal. yr BP and ca. 3840 cal yr BP at a rate of ca. 50 m/yr in response to the 1-2 °C increase in temperature estimated for the Holocene Thermal Maximum. Forest fires were relatively frequent during the early Holocene, before declining in frequency in response to development of cooler and wetter climate conditions associated with the Neoglacial (beginning after ca. 2200-2320 cal yr BP). We document a trend of increasing fire frequency in the 20th century that is correlated with warming at this time. These dynamics south of modern treeline provide insight into factors creating heterogeneity in plant community responses to large-scale climate events in high northern latitudes and suggest that large scale reorganization of boreal vegetation and fire regimes can be expected over the coming decades.

  8. Inferring learning rules from distribution of firing rates in cortical neurons

    PubMed Central

    Lim, Sukbin; McKee, Jillian L.; Woloszyn, Luke; Amit, Yali; Freedman, David J.; Sheinberg, David L.; Brunel, Nicolas

    2015-01-01

    Information about external stimuli is thought to be stored in cortical circuits through experience-dependent modifications of synaptic connectivity. These modifications of network connectivity should lead to changes in neuronal activity, as a particular stimulus is repeatedly encountered. Here, we ask what plasticity rules are consistent with the differences in the statistics of the visual response to novel and familiar stimuli in inferior temporal cortex, an area underlying visual object recognition. We introduce a method that allows inferring the dependence of the ‘learning rule’ on post-synaptic firing rate, and show that the inferred learning rule exhibits depression for low post-synaptic rates and potentiation for high rates. The threshold separating depression from potentiation is strongly correlated with both mean and standard deviation of the firing rate distribution. Finally, we show that network models implementing a rule extracted from data show stable learning dynamics, and lead to sparser representations of stimuli. PMID:26523643

  9. A statistical determination of the performance and coking rate of fired heaters

    SciTech Connect

    Sprague, D.E. ); Roy, K. )

    1988-01-01

    The coke formation processes that occur when oil is subjected to extreme conditions of time and temperature are investigated. These are pertinent to the various fired heaters of the oil refineries. A theory has been developed for a new technique of determining the coking rate in fired heaters and discusses factors affecting the performance of the process heater. The method combines empirical relationships of pressure, temperature, and oil characteristics into a statistical modeling system which can be used to predict the rate of coking or its inhibition. Analysis shows the interactive effects of API gravity, flow viscosity, and temperature upon the coking rate. Field evidence on a process heater of a delayed coking unit demonstrates the intuitive approach of this technique upon the selective coking rate under various severe operating conditions.

  10. Stimulus intensity determines experience-dependent modifications in neocortical neuron firing rates

    PubMed Central

    Glazewski, Stanislaw; Barth, Alison L

    2015-01-01

    Although subthreshold inputs of neocortical sensory neurons are broadly tuned, the spiking output is more restricted. These subthreshold inputs provide a substrate for stimulus intensity-dependent changes their spiking output, as well as for experience-dependent plasticity to alter firing properties. Here we investigated how different stimulus intensities modified the firing output of individual neurons in layer 2/3 of the mouse barrel cortex. Decreasing stimulus intensity over a 30-fold range lowered the firing rates evoked by principal whisker stimulation and reduced the overall size of the responding ensemble in whisker-undeprived animals. We then examined how these responses were changed after single-whisker experience (SWE). After 7 days of SWE, the mean magnitude of response to spared whisker stimulation at the highest stimulus intensity was not altered. However, lower-intensity whisker stimulation revealed a more than 10-fold increase in mean firing output compared with control animals. Also, under control conditions, only ∽15% of neurons showed any firing at low stimulus intensity, compared with more than 70% of neurons after SWE. However, response changes measured in the immediately surrounding representations were detected only for the highest stimulus intensity. Overall, these data showed that the measurement of experience-dependent changes in the spike output of neocortical neurons was highly dependent upon stimulus intensity. PMID:25546174

  11. Coexistence of Reward and Unsupervised Learning During the Operant Conditioning of Neural Firing Rates

    PubMed Central

    Kerr, Robert R.; Grayden, David B.; Thomas, Doreen A.; Gilson, Matthieu; Burkitt, Anthony N.

    2014-01-01

    A fundamental goal of neuroscience is to understand how cognitive processes, such as operant conditioning, are performed by the brain. Typical and well studied examples of operant conditioning, in which the firing rates of individual cortical neurons in monkeys are increased using rewards, provide an opportunity for insight into this. Studies of reward-modulated spike-timing-dependent plasticity (RSTDP), and of other models such as R-max, have reproduced this learning behavior, but they have assumed that no unsupervised learning is present (i.e., no learning occurs without, or independent of, rewards). We show that these models cannot elicit firing rate reinforcement while exhibiting both reward learning and ongoing, stable unsupervised learning. To fix this issue, we propose a new RSTDP model of synaptic plasticity based upon the observed effects that dopamine has on long-term potentiation and depression (LTP and LTD). We show, both analytically and through simulations, that our new model can exhibit unsupervised learning and lead to firing rate reinforcement. This requires that the strengthening of LTP by the reward signal is greater than the strengthening of LTD and that the reinforced neuron exhibits irregular firing. We show the robustness of our findings to spike-timing correlations, to the synaptic weight dependence that is assumed, and to changes in the mean reward. We also consider our model in the differential reinforcement of two nearby neurons. Our model aligns more strongly with experimental studies than previous models and makes testable predictions for future experiments. PMID:24475240

  12. Coexistence of reward and unsupervised learning during the operant conditioning of neural firing rates.

    PubMed

    Kerr, Robert R; Grayden, David B; Thomas, Doreen A; Gilson, Matthieu; Burkitt, Anthony N

    2014-01-01

    A fundamental goal of neuroscience is to understand how cognitive processes, such as operant conditioning, are performed by the brain. Typical and well studied examples of operant conditioning, in which the firing rates of individual cortical neurons in monkeys are increased using rewards, provide an opportunity for insight into this. Studies of reward-modulated spike-timing-dependent plasticity (RSTDP), and of other models such as R-max, have reproduced this learning behavior, but they have assumed that no unsupervised learning is present (i.e., no learning occurs without, or independent of, rewards). We show that these models cannot elicit firing rate reinforcement while exhibiting both reward learning and ongoing, stable unsupervised learning. To fix this issue, we propose a new RSTDP model of synaptic plasticity based upon the observed effects that dopamine has on long-term potentiation and depression (LTP and LTD). We show, both analytically and through simulations, that our new model can exhibit unsupervised learning and lead to firing rate reinforcement. This requires that the strengthening of LTP by the reward signal is greater than the strengthening of LTD and that the reinforced neuron exhibits irregular firing. We show the robustness of our findings to spike-timing correlations, to the synaptic weight dependence that is assumed, and to changes in the mean reward. We also consider our model in the differential reinforcement of two nearby neurons. Our model aligns more strongly with experimental studies than previous models and makes testable predictions for future experiments.

  13. CO2 and CO emission rates from three forest fire controlled experiments in Western Amazonia

    NASA Astrophysics Data System (ADS)

    Carvalho, J. A., Jr.; Amaral, S. S.; Costa, M. A. M.; Soares Neto, T. G.; Veras, C. A. G.; Costa, F. S.; van Leeuwen, T. T.; Krieger Filho, G. C.; Tourigny, E.; Forti, M. C.; Fostier, A. H.; Siqueira, M. B.; Santos, J. C.; Lima, B. A.; Cascão, P.; Ortega, G.; Frade, E. F., Jr.

    2016-06-01

    Forests represent an important role in the control of atmospheric emissions through carbon capture. However, in forest fires, the carbon stored during photosynthesis is released into the atmosphere. The carbon quantification, in forest burning, is important for the development of measures for its control. The aim of this study was to quantify CO2 and CO emissions of forest fires in Western Amazonia. In this paper, results are described of forest fire experiments conducted in Cruzeiro do Sul and Rio Branco, state of Acre, and Candeias do Jamari, state of Rondônia, Brazil. These cities are located in the Western portion of the Brazilian Amazon region. The biomass content per hectare, in the virgin forest, was measured by indirect methods using formulas with parameters of forest inventories in the central hectare of the test site. The combustion completeness was estimated by randomly selecting 10% of the total logs and twelve 2 × 2 m2 areas along three transects and examining their consumption rates by the fire. The logs were used to determine the combustion completeness of the larger materials (characteristic diameters larger than 10 cm) and the 2 × 2 m2 areas to determine the combustion completeness of small-size materials (those with characteristic diameters lower than 10 cm) and the. The overall biomass consumption by fire was estimated to be 40.0%, 41.2% and 26.2%, in Cruzeiro do Sul, Rio Branco and Candeias do Jamari, respectively. Considering that the combustion gases of carbon in open fires contain approximately 90.0% of CO2 and 10.0% of CO in volumetric basis, the average emission rates of these gases by the burning process, in the three sites, were estimated as 191 ± 46.7 t ha-1 and 13.5 ± 3.3 t ha-1, respectively.

  14. Estimating network parameters from combined dynamics of firing rate and irregularity of single neurons.

    PubMed

    Hamaguchi, Kosuke; Riehle, Alexa; Brunel, Nicolas

    2011-01-01

    High firing irregularity is a hallmark of cortical neurons in vivo, and modeling studies suggest a balance of excitation and inhibition is necessary to explain this high irregularity. Such a balance must be generated, at least partly, from local interconnected networks of excitatory and inhibitory neurons, but the details of the local network structure are largely unknown. The dynamics of the neural activity depends on the local network structure; this in turn suggests the possibility of estimating network structure from the dynamics of the firing statistics. Here we report a new method to estimate properties of the local cortical network from the instantaneous firing rate and irregularity (CV(2)) under the assumption that recorded neurons are a part of a randomly connected sparse network. The firing irregularity, measured in monkey motor cortex, exhibits two features; many neurons show relatively stable firing irregularity in time and across different task conditions; the time-averaged CV(2) is widely distributed from quasi-regular to irregular (CV(2) = 0.3-1.0). For each recorded neuron, we estimate the three parameters of a local network [balance of local excitation-inhibition, number of recurrent connections per neuron, and excitatory postsynaptic potential (EPSP) size] that best describe the dynamics of the measured firing rates and irregularities. Our analysis shows that optimal parameter sets form a two-dimensional manifold in the three-dimensional parameter space that is confined for most of the neurons to the inhibition-dominated region. High irregularity neurons tend to be more strongly connected to the local network, either in terms of larger EPSP and inhibitory PSP size or larger number of recurrent connections, compared with the low irregularity neurons, for a given excitatory/inhibitory balance. Incorporating either synaptic short-term depression or conductance-based synapses leads many low CV(2) neurons to move to the excitation-dominated region as

  15. A miniscale ballistic test motor for propellant burning rate characterization from one motor firing

    NASA Astrophysics Data System (ADS)

    Rast, Robert H.; Boyles, Sharon M.; Obney, Phyllis

    1992-07-01

    A mini ballistic test motor for burn rate characterization from one motor firing has been developed. The small charge weight required for this motor allows ballistic characterization of small scale lot set evaluation and R&D propellant mixes in a rocket motor environment. This paper presents results comparing the mini-motor to the standard Naval Surface Warfare Center, Indian Head (IHDIVNAVSURFWARCEN) ballistic test motor, (BTM). Burn rate data from the standard BTM and mini BTM show excellent agreement.

  16. Progress toward the determination of correct classification rates in fire debris analysis.

    PubMed

    Waddell, Erin E; Song, Emma T; Rinke, Caitlin N; Williams, Mary R; Sigman, Michael E

    2013-07-01

    Principal components analysis (PCA), linear discriminant analysis (LDA), and quadratic discriminant analysis (QDA) were used to develop a multistep classification procedure for determining the presence of ignitable liquid residue in fire debris and assigning any ignitable liquid residue present into the classes defined under the American Society for Testing and Materials (ASTM) E 1618-10 standard method. A multistep classification procedure was tested by cross-validation based on model data sets comprised of the time-averaged mass spectra (also referred to as total ion spectra) of commercial ignitable liquids and pyrolysis products from common building materials and household furnishings (referred to simply as substrates). Fire debris samples from laboratory-scale and field test burns were also used to test the model. The optimal model's true-positive rate was 81.3% for cross-validation samples and 70.9% for fire debris samples. The false-positive rate was 9.9% for cross-validation samples and 8.9% for fire debris samples.

  17. Fire and Grazing Influences on Rates of Riparian Woody Plant Expansion along Grassland Streams

    PubMed Central

    Veach, Allison M.; Dodds, Walter K.; Skibbe, Adam

    2014-01-01

    Grasslands are threatened globally due to the expansion of woody plants. The few remaining headwater streams within tallgrass prairies are becoming more like typical forested streams due to rapid conversion of riparian zones from grassy to wooded. Forestation can alter stream hydrology and biogeochemistry. We estimated the rate of riparian woody plant expansion within a 30 m buffer zone surrounding the stream bed across whole watersheds at Konza Prairie Biological Station over 25 years from aerial photographs. Watersheds varied with respect to experimentally-controlled fire and bison grazing. Fire frequency, presence or absence of grazing bison, and the historical presence of woody vegetation prior to the study time period (a proxy for proximity of propagule sources) were used as independent variables to predict the rate of riparian woody plant expansion between 1985 and 2010. Water yield was estimated across these years for a subset of watersheds. Riparian woody encroachment rates increased as burning became less frequent than every two years. However, a higher fire frequency (1–2 years) did not reverse riparian woody encroachment regardless of whether woody vegetation was present or not before burning regimes were initiated. Although riparian woody vegetation cover increased over time, annual total precipitation and average annual temperature were variable. So, water yield over 4 watersheds under differing burn frequencies was quite variable and with no statistically significant detected temporal trends. Overall, burning regimes with a frequency of every 1–2 years will slow the conversion of tallgrass prairie stream ecosystems to forested ones, yet over long time periods, riparian woody plant encroachment may not be prevented by fire alone, regardless of fire frequency. PMID:25192194

  18. Fire and grazing influences on rates of riparian woody plant expansion along grassland streams.

    PubMed

    Veach, Allison M; Dodds, Walter K; Skibbe, Adam

    2014-01-01

    Grasslands are threatened globally due to the expansion of woody plants. The few remaining headwater streams within tallgrass prairies are becoming more like typical forested streams due to rapid conversion of riparian zones from grassy to wooded. Forestation can alter stream hydrology and biogeochemistry. We estimated the rate of riparian woody plant expansion within a 30 m buffer zone surrounding the stream bed across whole watersheds at Konza Prairie Biological Station over 25 years from aerial photographs. Watersheds varied with respect to experimentally-controlled fire and bison grazing. Fire frequency, presence or absence of grazing bison, and the historical presence of woody vegetation prior to the study time period (a proxy for proximity of propagule sources) were used as independent variables to predict the rate of riparian woody plant expansion between 1985 and 2010. Water yield was estimated across these years for a subset of watersheds. Riparian woody encroachment rates increased as burning became less frequent than every two years. However, a higher fire frequency (1-2 years) did not reverse riparian woody encroachment regardless of whether woody vegetation was present or not before burning regimes were initiated. Although riparian woody vegetation cover increased over time, annual total precipitation and average annual temperature were variable. So, water yield over 4 watersheds under differing burn frequencies was quite variable and with no statistically significant detected temporal trends. Overall, burning regimes with a frequency of every 1-2 years will slow the conversion of tallgrass prairie stream ecosystems to forested ones, yet over long time periods, riparian woody plant encroachment may not be prevented by fire alone, regardless of fire frequency.

  19. Reduced firing rates of high threshold motor units in response to eccentric overload.

    PubMed

    Balshaw, Tom G; Pahar, Madhu; Chesham, Ross; Macgregor, Lewis J; Hunter, Angus M

    2017-01-01

    Acute responses of motor units were investigated during submaximal voluntary isometric tasks following eccentric overload (EO) and constant load (CL) knee extension resistance exercise. Ten healthy resistance-trained participants performed four experimental test sessions separated by 5 days over a 20 day period. Two sessions involved constant load and the other two used eccentric overload. EO and CL used both sessions for different target knee eccentric extension phases; one at 2 sec and the other at 4 sec. Maximal voluntary contractions (MVC) and isometric trapezoid efforts for 10 sec at 70% MVC were completed before and after each intervention and decomposed electromyography was used to measure motor unit firing rate. The firing rate of later recruited, high-threshold motor units declined following the 2-sec EO but was maintained following 2sec CL (P < 0.05), whereas MUFR for all motor units were maintained for both loading types following 4-sec extension phases. MVC and rate of force development where maintained following both EO and CL and 2 and 4 sec phases. This study demonstrates a slower firing rate of high-threshold motor units following fast eccentric overload while MVC was maintained. This suggests that there was a neuromuscular stimulus without cost to the force-generating capacity of the knee extensors. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  20. Predicting duff and woody fuel consumed by prescribed fire in the Northern Rocky Mountains

    Treesearch

    James K. Brown; Michael A. Marsden; Kevin C. Ryan; Elizabeth D. Reinhardt

    1985-01-01

    Relationships for predicting duff reduction, mineral soil exposure, and consumption of downed woody fuel were determined to assist in planning prescribed fires. Independent variables included lower and entire duff moisture contents, loadings of downed woody fuels, duff depth, National Fire-Danger Rating System 1,000-hour moisture content, and Canadian Duff Moisture...

  1. Information Transmission and Anderson Localization in two-dimensional networks of firing-rate neurons

    NASA Astrophysics Data System (ADS)

    Natale, Joseph; Hentschel, George

    Firing-rate networks offer a coarse model of signal propagation in the brain. Here we analyze sparse, 2D planar firing-rate networks with no synapses beyond a certain cutoff distance. Additionally, we impose Dale's Principle to ensure that each neuron makes only or inhibitory outgoing connections. Using spectral methods, we find that the number of neurons participating in excitations of the network becomes insignificant whenever the connectivity cutoff is tuned to a value near or below the average interneuron separation. Further, neural activations exceeding a certain threshold stay confined to a small region of space. This behavior is an instance of Anderson localization, a disorder-induced phase transition by which an information channel is rendered unable to transmit signals. We discuss several potential implications of localization for both local and long-range computation in the brain. This work was supported in part by Grants JSMF/ 220020321 and NSF/IOS/1208126.

  2. Neuronal response impedance mechanism implementing cooperative networks with low firing rates and μs precision

    PubMed Central

    Vardi, Roni; Goldental, Amir; Marmari, Hagar; Brama, Haya; Stern, Edward A.; Sardi, Shira; Sabo, Pinhas; Kanter, Ido

    2015-01-01

    Realizations of low firing rates in neural networks usually require globally balanced distributions among excitatory and inhibitory links, while feasibility of temporal coding is limited by neuronal millisecond precision. We show that cooperation, governing global network features, emerges through nodal properties, as opposed to link distributions. Using in vitro and in vivo experiments we demonstrate microsecond precision of neuronal response timings under low stimulation frequencies, whereas moderate frequencies result in a chaotic neuronal phase characterized by degraded precision. Above a critical stimulation frequency, which varies among neurons, response failures were found to emerge stochastically such that the neuron functions as a low pass filter, saturating the average inter-spike-interval. This intrinsic neuronal response impedance mechanism leads to cooperation on a network level, such that firing rates are suppressed toward the lowest neuronal critical frequency simultaneously with neuronal microsecond precision. Our findings open up opportunities of controlling global features of network dynamics through few nodes with extreme properties. PMID:26124707

  3. Post-fire changes in sediment rating curves in a wet Eucalyptus forest in SE Australia

    NASA Astrophysics Data System (ADS)

    Sheridan, Gary J.; Lane, Patrick N. J.; Sherwin, Christopher B.; Noske, Philip J.

    2011-10-01

    SummaryEmpirical power law sediment rating curves of the form C = aQ b (where C is the sediment concentration, Q is the discharge rate, and the coefficient a and exponent b are fitted parameters), or the alternative form given by log( Q s) = log( a) + ( b + 1)log( Q) (where Q s = CQ is the sediment delivery rate, and the natural logarithm is used) are widely used for characterising sediment transport across a broad range of spatial and temporal scales. Fire frequently has a large effect on erosion rates and sediment delivery. We investigate the temporal changes in the coefficient a and exponent b for 3 years following a wildfire between February 2003 and April 2006, for two South Eastern Australian Eucalyptus forested catchments (136 and 244 ha) with mean annual rainfall of 1900 mm. Storm-event integrated sediment loads and discharges were calculated for each of 596 storm events using stage-discharge control structures and in situ turbidity measurements at 15 min intervals. Measurements were converted to sediment concentrations using regression relationships developed from storm activated water auto-samplers. The analysis identified: (i) strong negative linear relationships between the rating coefficient log( a), and the rating exponent b, reflecting sediment rating curves that "pivot" around a common fulcrum point in log-log space, (ii) a systematic shift in this linear relationship between log( a) and b as a function of time since fire, (iii) maximum values of b of ca. 2.5 (i.e. maximum non-linearity in the relationship between discharge and sediment delivery, and therefore maximum sensitivity to high peak-discharge events) immediately following the fire, which decline rapidly and monotonically by a factor of 10 to ca. 0.25 in the first 8 months, attributed to a dominance of hillslope erosion processes and declining rill and interill erodibility, (iv) irregular patterns in the value of b during the vegetation recovery period, probably reflecting a shift from

  4. Firing rate analysis using decompostion-enhanced spike triggered averaging in the quadriceps femoris.

    PubMed

    Conwit, R A; Tracy, B; Cowl, A; McHugh, M; Stashuk, D; Brown, W F; Metter, E J

    1998-10-01

    Electromyographic signals detected from the quadriceps femoris during various constant force contractions were decomposed to identify individual motor unit discharges and mean firing rates (FRs). Subject and group mean FRs were calculated for each force level. Mean FR values and FR variability increased with force. Individual, subject, and group mean FRs showed slight increases until 30% of maximum voluntary contraction and larger increases thereafter. Findings are discussed in relation to motor unit recruitment, frequency modulation, and fatigue.

  5. Spike synchronization and firing rate in a population of motor cortical neurons in relation to movement direction and reaction time.

    PubMed

    Grammont, F; Riehle, A

    2003-05-01

    We studied the dynamics of precise spike synchronization and rate modulation in a population of neurons recorded in monkey motor cortex during performance of a delayed multidirectional pointing task and determined their relation to behavior. We showed that at the population level neurons coherently synchronized their activity at various moments during the trial in relation to relevant task events. The comparison of the time course of the modulation of synchronous activity with that of the firing rate of the same neurons revealed a considerable difference. Indeed, when synchronous activity was highest, at the end of the preparatory period, firing rate was low, and, conversely, when the firing rate was highest, at movement onset, synchronous activity was almost absent. There was a clear tendency for synchrony to precede firing rate, suggesting that the coherent activation of cell assemblies may trigger the increase in firing rate in large groups of neurons, although it appeared that there was no simple parallel shifting in time of these two activity measures. Interestingly, there was a systematic relationship between the amount of significant synchronous activity within the population of neurons and movement direction at the end of the preparatory period. Furthermore, about 400 ms later, at movement onset, the mean firing rate of the same population was also significantly tuned to movement direction, having roughly the same preferred direction as synchronous activity. Finally, reaction time measurements revealed a directional preference of the monkey with, once again, the same preferred direction as synchronous activity and firing rate. These results lead us to speculate that synchronous activity and firing rate are cooperative neuronal processes and that the directional matching of our three measures--firing rate, synchronicity, and reaction times--might be an effect of behaviorally induced network cooperativity acquired during learning.

  6. Hyperpolarization induces a long-term increase in the spontaneous firing rate of cerebellar Golgi cells.

    PubMed

    Hull, Court A; Chu, YunXiang; Thanawala, Monica; Regehr, Wade G

    2013-04-03

    Golgi cells (GoCs) are inhibitory interneurons that influence the cerebellar cortical response to sensory input by regulating the excitability of the granule cell layer. While GoC inhibition is essential for normal motor coordination, little is known about the circuit dynamics that govern the activity of these cells. In particular, although GoC spontaneous spiking influences the extent of inhibition and gain throughout the granule cell layer, it is not known whether this spontaneous activity can be modulated in a long-term manner. Here we describe a form of long-term plasticity that regulates the spontaneous firing rate of GoCs in the rat cerebellar cortex. We find that membrane hyperpolarization, either by mGluR2 activation of potassium channels, or by somatic current injection, induces a long-lasting increase in GoC spontaneous firing. This spike rate plasticity appears to result from a strong reduction in the spike after hyperpolarization. Pharmacological manipulations suggest the involvement of calcium-calmodulin-dependent kinase II and calcium-activated potassium channels in mediating these firing rate increases. As a consequence of this plasticity, GoC spontaneous spiking is selectively enhanced, but the gain of evoked spiking is unaffected. Hence, this plasticity is well suited for selectively regulating the tonic output of GoCs rather than their sensory-evoked responses.

  7. Hyperpolarization induces a long-term increase in the spontaneous firing rate of cerebellar Golgi cells

    PubMed Central

    Hull, Court; Chu, YunXiang; Thanawala, Monica; Regehr, Wade G.

    2013-01-01

    Golgi cells (GoCs) are inhibitory interneurons that influence the cerebellar cortical response to sensory input by regulating the excitability of the granule cell layer. While GoC inhibition is essential for normal motor coordination, little is known about the circuit dynamics that govern the activity of these cells. In particular, while GoC spontaneous spiking influences the extent of inhibition and gain throughout the granule cell layer, it is not known whether this spontaneous activity can be modulated in a long-term manner. Here we describe a form of long-term plasticity that regulates the spontaneous firing rate of GoCs in the rat cerebellar cortex. We find that membrane hyperpolarization, either by mGluR2 activation of potassium channels, or by somatic current injection, induces a long-lasting increase in GoC spontaneous firing. This spike rate plasticity appears to result from a strong reduction in the spike afterhyperpolarization (AHP). Pharmacological manipulations suggest the involvement of calcium-calmodulin dependent kinase II (CaMKII) and calcium-activated potassium channels in mediating these firing rate increases. As a consequence of this plasticity, GoC spontaneous spiking is selectively enhanced, but the gain of evoked spiking is unaffected. Hence this plasticity is well-suited for selectively regulating the tonic output of GoCs rather than their sensory-evoked responses. PMID:23554471

  8. Fire scar growth and closure rates in white oak (Quercus alba) and the implications for prescribed burning

    Treesearch

    Michael C. Stambaugh; Kevin T. Smith; Daniel C. Dey

    2017-01-01

    In burned forestlands, fire scar wounds commonly occur on tree stems as a result of cambial heating. In hardwood forests in particular, wounding can lead to stem decay with the extent of decay being related to scar size and exposure time. Therefore, wound closure rates are important to understand in the context of fire management such that allowing sufficient time for...

  9. Muscle vibration sustains motor unit firing rate during submaximal isometric fatigue in humans

    PubMed Central

    Griffin, L; Garland, S J; Ivanova, T; Gossen, E R

    2001-01-01

    In keeping with the ‘muscular wisdom hypothesis’, many studies have documented that the firing rate of the majority of motor units decreased during fatiguing isometric contractions. The present study investigated whether the application of periodic muscle vibration, which strongly activates muscle spindles, would alter the modulation of motor unit firing rate during submaximal fatiguing isometric contractions. Thirty-three motor units from the lateral head of the triceps brachii muscle were recorded from 10 subjects during a sustained isometric 20 % maximal voluntary contraction (MVC) of the elbow extensors. Vibration was interposed on the contraction for 2 s every 10 s. Twenty-two motor units were recorded from the beginning of the fatigue task. The discharge rate of the majority of motor units remained constant (12/22) or increased (4/22) with fatigue. Six motor units demonstrated a reduction in discharge rate that later returned toward initial values; these motor units had higher initial discharge rates than the other 16 motor units. In a second series of experiments, four subjects held a sustained isometric 20 % MVC for 2 min and then vibration was applied as above for the remainder of the contraction. In this case, motor units initially demonstrated a decrease in firing rate that increased after the vibration was applied. Thus muscle spindle disfacilitation of the motoneurone pool may be associated with the decline of motor unit discharge rate observed during the first 2 min of the contraction. In a third set of experiments, seven subjects performed the main experiment on one occasion and repeated the fatigue task without vibration on a second occasion. Neither the endurance time of the fatiguing contraction nor the MVC torque following fatigue was affected by the application of vibration. This finding calls into question the applicability of the muscular wisdom hypothesis to submaximal contractions. PMID:11559785

  10. Forecasting distribution of numbers of large fires

    Treesearch

    Haiganoush K. Preisler; Jeff Eidenshink; Stephen Howard; Robert E. Burgan

    2015-01-01

    Systems to estimate forest fire potential commonly utilize one or more indexes that relate to expected fire behavior; however they indicate neither the chance that a large fire will occur, nor the expected number of large fires. That is, they do not quantify the probabilistic nature of fire danger. In this work we use large fire occurrence information from the...

  11. Practical approximation method for firing-rate models of coupled neural networks with correlated inputs

    NASA Astrophysics Data System (ADS)

    Barreiro, Andrea K.; Ly, Cheng

    2017-08-01

    Rapid experimental advances now enable simultaneous electrophysiological recording of neural activity at single-cell resolution across large regions of the nervous system. Models of this neural network activity will necessarily increase in size and complexity, thus increasing the computational cost of simulating them and the challenge of analyzing them. Here we present a method to approximate the activity and firing statistics of a general firing rate network model (of the Wilson-Cowan type) subject to noisy correlated background inputs. The method requires solving a system of transcendental equations and is fast compared to Monte Carlo simulations of coupled stochastic differential equations. We implement the method with several examples of coupled neural networks and show that the results are quantitatively accurate even with moderate coupling strengths and an appreciable amount of heterogeneity in many parameters. This work should be useful for investigating how various neural attributes qualitatively affect the spiking statistics of coupled neural networks.

  12. Wildfire Danger Potential in California

    NASA Astrophysics Data System (ADS)

    Kafatos, M.; Myoung, B.; Kim, S. H.; Fujioka, F. M.; Kim, J.

    2015-12-01

    Wildfires are an important concern in California (CA) which is characterized by the semi-arid to arid climate and vegetation types. Highly variable winter precipitation and extended hot and dry warm season in the region challenge an effective strategic fire management. Climatologically, the fire season which is based on live fuel moisture (LFM) of generally below 80% in Los Angeles County spans 4 months from mid-July to mid-November, but it has lasted over 7 months in the past several years. This behavior is primarily due to the ongoing drought in CA during the last decade, which is responsible for frequent outbreaks of severe wildfires in the region. Despite their importance, scientific advances for the recent changes in wildfire risk and effective assessments of wildfire risk are lacking. In the present study, we show impacts of large-scale atmospheric circulations on an early start and then extended length of fire seasons. For example, the strong relationships of North Atlantic Oscillation (NAO) with springtime temperature and precipitation in the SWUS that was recently revealed by our team members have led to an examination of the possible impact of NAO on wildfire danger in the spring. Our results show that the abnormally warm and dry spring conditions associated with positive NAO phases can cause an early start of a fire season and high fire risks throughout the summer and fall. For an effective fire danger assessment, we have tested the capability of satellite vegetation indices (VIs) in replicating in situ LFM of Southern CA chaparral ecosystems by 1) comparing seasonal/interannual characteristics of in-situ LFM with VIs and 2) developing an empirical model function of LFM. Unlike previous studies attempting a point-to-point comparison, we attempt to examine the LFM relationship with VIs averaged over different areal coverage with chamise-dominant grids (i.e., 0.5 km to 25 km radius circles). Lastly, we discuss implications of the results for fire danger

  13. A Tool for Rating the Resilience of Critical Infrastructures in Extreme Fires

    DTIC Science & Technology

    2014-05-01

    against extreme fires. An Advisory Board was formed with 15 members from government departments, fire services, engineering and extreme fire experts...fire resistance evaluation of critical structures or any HJA 43 acceptable curve following an engineering analysis. The RWS time-temperature...Ministry of Transport in the Netherlands based on the assumption that, in a worst case scenario, a 50 m3 fuel, oil or petrol tanker fire, with a fire load

  14. BK channels regulate sinoatrial node firing rate and cardiac pacing in vivo

    PubMed Central

    Lai, Michael H.; Wu, Yuejin; Gao, Zhan; Anderson, Mark E.; Dalziel, Julie E.

    2014-01-01

    Large-conductance Ca2+- and voltage-activated K+ (BK) channels play prominent roles in shaping muscle and neuronal excitability. In the cardiovascular system, BK channels promote vascular relaxation and protect against ischemic injury. Recently, inhibition of BK channels has been shown to lower heart rate in intact rodents and isolated hearts, suggesting a novel role in heart function. However, the underlying mechanism is unclear. In the present study, we recorded ECGs from mice injected with paxilline (PAX), a membrane-permeable BK channel antagonist, and examined changes in cardiac conduction. ECGs revealed a 19 ± 4% PAX-induced reduction in heart rate in wild-type but not BK channel knockout (Kcnma1−/−) mice. The heart rate decrease was associated with slowed cardiac pacing due to elongation of the sinus interval. Action potential firing recorded from isolated sinoatrial node cells (SANCs) was reduced by 55 ± 15% and 28 ± 9% by application of PAX (3 μM) and iberiotoxin (230 nM), respectively. Furthermore, baseline firing rates from Kcnma1−/− SANCs were 33% lower than wild-type SANCs. The slowed firing upon BK current inhibition or genetic deletion was due to lengthening of the diastolic depolarization phase of the SANC action potential. Finally, BK channel immunoreactivity and PAX-sensitive currents were identified in SANCs with HCN4 expression and pacemaker current, respectively, and BK channels cloned from SANCs recapitulated similar activation as the PAX-sensitive current. Together, these data localize BK channels to SANCs and demonstrate that loss of BK current decreases SANC automaticity, consistent with slowed sinus pacing after PAX injection in vivo. Furthermore, these findings suggest BK channels are potential therapeutic targets for disorders of heart rate. PMID:25172903

  15. A critical firing rate associated with tonic-to-bursting transitions in synchronized gap-junction coupled neurons

    NASA Astrophysics Data System (ADS)

    Shaffer, Annabelle; Follmann, Rosangela; Harris, Allison L.; Postnova, Svetlana; Braun, Hans; Rosa, Epaminondas

    2017-06-01

    A transition between tonic and bursting neuronal behaviors is studied using a linear chain of three electrically coupled model neurons. Numerical simulations show that, depending on their individual dynamical states, the neurons first synchronize either in a tonic or in a bursting regime. Additionally, a characteristic firing rate, mediating tonic-to-bursting transitions in networked neurons, is found to be associated with a firing rate encountered in the single neuron's equivalent transition. A few cases describing this peculiar phenomenon are presented.

  16. Evidence for serotonin synthesis-dependent regulation of in vitro neuronal firing rates in the midbrain raphe complex.

    PubMed

    Evans, Andrew K; Reinders, Niels; Ashford, Katie A; Christie, Isabel N; Wakerley, Jonathan B; Lowry, Christopher A

    2008-08-20

    Evidence suggests that 5-hydroxytryptamine 1A (5-HT(1A)) receptor-mediated autoregulation of serotonergic neuronal firing rates is impaired in stress-related neuropsychiatric disorders. In vitro models may provide insight into neural mechanisms underlying regulation of serotonergic systems. However, serotonin synthesis and tonic autoregulation of serotonergic neuronal firing rates are impaired in in vitro preparations lacking tryptophan. We describe the effects of perfusion of living rat brain slices with tryptophan on both 1) tissue concentrations of serotonin metabolites and 2) neuronal firing rates within the dorsal raphe nucleus. Brain slices were perfused with artificial cerebrospinal fluid lacking tryptophan for 4 h, followed by exposure to 1) 40 microM tryptophan (0-60 min) or 2) 0-400 microM tryptophan (23 min) and microdissected for analysis of indole concentrations. Parallel studies examined effects of tryptophan on neuronal firing rates and interactions with drugs expected to alter synaptic concentrations of serotonin. Tryptophan resulted in time-dependent and concentration-dependent increases in serotonin and serotonin metabolites, effects that were correlated with restoration of tonic autoinhibition of dorsal raphe nucleus neuronal firing rates. Inhibition of serotonin synthesis resulted in time-dependent and concentration-dependent increases in 5-hydroxtryptophan that correlated with reversal of the tryptophan-mediated autoinhibition of neuronal firing rates. Tryptophan modulated effects of several drugs on neuronal firing rates, including a selective 5-HT(1A) receptor antagonist (WAY-100635), a monoamine oxidase inhibitor (pargyline), a selective serotonin reuptake inhibitor (fluoxetine), and a serotonin-releasing agent (methylenedioxymethamphetamine). These studies support the hypothesis that tonic autoregulation of serotonergic neuronal firing rates is dependent on tryptophan availability and characterise conditions necessary to study this process

  17. Spike Phase Locking in CA1 Pyramidal Neurons depends on Background Conductance and Firing Rate

    PubMed Central

    Broiche, Tilman; Malerba, Paola; Dorval, Alan D.; Borisyuk, Alla; Fernandez, Fernando R.; White, John A.

    2012-01-01

    Oscillatory activity in neuronal networks correlates with different behavioral states throughout the nervous system, and the frequency-response characteristics of individual neurons are believed to be critical for network oscillations. Recent in vivo studies suggest that neurons experience periods of high membrane conductance, and that action potentials are often driven by membrane-potential fluctuations in the living animal. To investigate the frequency-response characteristics of CA1 pyramidal neurons in the presence of high conductance and voltage fluctuations, we performed dynamic-clamp experiments in rat hippocampal brain slices. We drove neurons with noisy stimuli that included a sinusoidal component ranging, in different trials, from 0.1 to 500 Hz. In subsequent data analysis, we determined action potential phase-locking profiles with respect to background conductance, average firing rate, and frequency of the sinusoidal component. We found that background conductance and firing rate qualitatively change the phase-locking profiles of CA1 pyramidal neurons vs. frequency. In particular, higher average spiking rates promoted band-pass profiles, and the high-conductance state promoted phase-locking at frequencies well above what would be predicted from changes in the membrane time constant. Mechanistically, spike-rate adaptation and frequency resonance in the spike-generating mechanism are implicated in shaping the different phase-locking profiles. Our results demonstrate that CA1 pyramidal cells can actively change their synchronization properties in response to global changes in activity associated with different behavioral states. PMID:23055508

  18. Changes in fire weather distributions: effects on predicted fire behavior

    Treesearch

    Lucy A. Salazar; Larry S. Bradshaw

    1984-01-01

    Data that represent average worst fire weather for a particular area are used to index daily fire danger; however, they do not account for different locations or diurnal weather changes that significantly affect fire behavior potential. To study the effects that selected changes in weather databases have on computed fire behavior parameters, weather data for the...

  19. The Effects of Dynamical Synapses on Firing Rate Activity: A Spiking Neural Network Model.

    PubMed

    Khalil, Radwa; Moftah, Marie Z; Moustafa, Ahmed A

    2017-09-18

    Accumulating evidence relates the fine-tuning of synaptic maturation and regulation of neural network activity to several key factors, including GABAA signaling and a lateral spread length between neighboring neurons (i.e. local connectivity). Furthermore, a number of studies consider Short-Term synaptic Plasticity (STP) as an essential element in the instant modification of synaptic efficacy in the neuronal network and in modulating responses to sustained ranges of external Poisson Input Frequency (IF). Nevertheless, evaluating the firing activity in response to the dynamical interaction between STP (triggered by ranges of IF), and these key parameters in vitro remains elusive. Therefore, we designed a Spiking Neural Network (SNN) model in which we incorporated the following parameters: local density of arbor essences and a lateral spread length between neighboring neurons. We also created several network scenarios based on these key parameters. Then, we implemented two classes of STP: (1) Short-Term synaptic Depression (STD), and (2) Short-Term synaptic Facilitation (STF). Each class has two differential forms based on the parametric value of its synaptic time constant (either for depressing or facilitating synapses). Lastly, we compared the neural firing responses before and after the treatment with STP. We found that dynamical synapses(STP) have a critical differential role on evaluating, and modulating the firing rate activity in each network scenario. Moreover, we investigated the impact of changing the balance between excitation (E) / inhibition (I) on stabilizing this firing activity. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  20. Canadian and Siberian Boreal Fire Activity during ARCTAS Spring and Summer Phases

    NASA Astrophysics Data System (ADS)

    Stocks, B. J.; Fromm, M. D.; Soja, A. J.; Servranckx, R.; Lindsey, D.; Hyer, E.

    2009-12-01

    The summer phase of ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) was designed specifically around forest fire activity in the Canadian boreal forest, and located in areas of northern Canada where summer forest fires are ubiquitous. Lightning fires are most often allowed to burn naturally in these regions, and a number of large free-burning fires in northern Saskatchewan in late June/early July 2008 provided excellent targets during the summer phase of ARCTAS. Smoke generated by a large number of early spring fires in Kazakhstan and southern Siberia unexpectedly made a significant contribution to arctic haze during the Alaska-based spring phase of ARCTAS, Numerous smoke plumes were sampled during the spring phase of ARCTAS, creating interest in the origin and characteristics of the fires in the source regions of East Asia. This presentation is designed to connect aircraft and satellite smoke chemistry/transport measurements with ground-based measurements of fire activity during the spring and summer phases of ARCTAS. The Canadian Forest Fire Danger Rating System (CFFDRS) is used to determine forest fire danger conditions in regions of fire activity, and these measurements are in turn used to project fire behavior characteristics. Fuel consumption, spread rates, and frontal fire intensity are calculated using the CFFDRS. Energy release rates at ground level are related to convection/smoke column development and smoke injection heights.

  1. Kv2 channels regulate firing rate in pyramidal neurons from rat sensorimotor cortex

    PubMed Central

    Guan, Dongxu; Armstrong, William E; Foehring, Robert C

    2013-01-01

    The largest outward potassium current in the soma of neocortical pyramidal neurons is due to channels containing Kv2.1 α subunits. These channels have been implicated in cellular responses to seizures and ischaemia, mechanisms for intrinsic plasticity and cell death, and responsiveness to anaesthetic agents. Despite their abundance, knowledge of the function of these delayed rectifier channels has been limited by the lack of specific pharmacological agents. To test for functional roles of Kv2 channels in pyramidal cells from somatosensory or motor cortex of rats (layers 2/3 or 5), we transfected cortical neurons with DNA for a Kv2.1 pore mutant (Kv2.1W365C/Y380T: Kv2.1 DN) in an organotypic culture model to manipulate channel expression. Slices were obtained from rats at postnatal days (P7-P14) and maintained in organotypic culture. We used biolistic methods to transfect neurons with gold ‘bullets’ coated with DNA for the Kv2.1 DN and green fluorescent protein (GFP), GFP alone, or wild type (WT) Kv2.1 plus GFP. Cells that fluoresced green, contained a bullet and responded to positive or negative pressure from the recording pipette were considered to be transfected cells. In each slice, we recorded from a transfected cell and a control non-transfected cell from the same layer and area. Whole-cell voltage-clamp recordings obtained after 3–7 days in culture showed that cells transfected with the Kv2.1 DN had a significant reduction in outward current (∼45% decrease in the total current density measured 200 ms after onset of a voltage step from –78 to –2 mV). Transfection with GFP alone did not affect current amplitude and overexpression of the Kv2.1 WT resulted in greatly increased currents. Current-clamp experiments were used to assess the functional consequences of manipulation of Kv2.1 expression. The results suggest roles for Kv2 channels in controlling membrane potential during the interspike interval (ISI), firing rate, spike frequency adaptation

  2. Operating Room Fire Safety

    PubMed Central

    Hart, Stuart R.; Yajnik, Amit; Ashford, Jeffrey; Springer, Randy; Harvey, Sherry

    2011-01-01

    Operating room fires are a rare but preventable danger in modern healthcare operating rooms. Optimal outcomes depend on all operating room personnel being familiar with their roles in fire prevention and fire management. Despite the recommendations of major safety institutes, this familiarity is not the current practice in many healthcare facilities. Members of the anesthesiology and the surgery departments are commonly not actively involved in fire safety programs, fire drills, and fire simulations that could lead to potential delays in prevention and management of intraoperative fires. PMID:21603334

  3. Measuring the rate of spread of chaparral prescribed fires in northern California

    Treesearch

    S. L. Stephens; D. R. Weise; D. L. Fry; R. J. Keiffer; J. Dawson; E. Koo; J. Potts; P. J. Pagni

    2008-01-01

    Prescribed fire is a common method used to produce desired ecological effects in chaparral by mimicking the natural role of fire. Since prescribed fires are usually conducted in moderate fuel and weather conditions, models that accurately predict fire behavior and effects under these scenarios are important for management. In this study, explosive audio devices and...

  4. Fire occurrence and fire weather indices in the past and under future climate in Peninsular Spain

    NASA Astrophysics Data System (ADS)

    Urbieta, Itziar R.; Zavala, Gonzalo; Moreno, José M.

    2010-05-01

    Understanding fire occurrence and its relationship with ignition sources and weather conditions is a major environmental challenge in regions affected by fire, particularly under ongoing and projected future climate change. The objectives of this study were: 1) To address a historical reconstruction of fire regime (fire occurrence, area burned, and fire causes) in Peninsular Spain for the last three decades. 2) Analyze the time x space relationship between fire occurrence and area burned with climatic variables and climate-derived fire danger indices. 3) Assess how climate change would affect fire danger indices for various emission scenarios based on projections of five regional climate models. The country was divided into 50x50 km cells, for which fire statistics were available. Climate data were interpolated at this grid so that daily fire danger indices were calculated for present and future conditions. Results showed an overall increase of fire occurrence and area burned over the past decades. Fire activity (number of fires and area burned) showed significant correlations with fire danger indices and climatic variables; although in some areas the relationship was weak given the uncertainty linked to the number of ignitions caused by people. There was a significant correlation between certain fire indices and Gini coefficient of fire sizes, whereby fires under more severe conditions become more variable in size. Towards the end of this century (2071-2100) increases in the fire danger indices, and a longer period of fire danger are projected. This trend is consistent among models.

  5. Contractile function and motor unit firing rates of the human hamstrings.

    PubMed

    Kirk, Eric A; Rice, Charles L

    2017-01-01

    Neuromuscular properties of the lower limb in health, aging, and disease are well described for major lower limb muscles comprising the quadriceps, triceps surae, and dorsiflexors, with the notable exception of the posterior thigh (hamstrings). The purpose of this study was to further characterize major muscles of the lower limb by comprehensively exploring contractile properties in relation to spinal motor neuron output expressed as motor unit firing rates (MUFRs) in the hamstrings of 11 (26.5 ± 3.8) young men. Maximal isometric voluntary contraction (MVC), voluntary activation, stimulated contractile properties including a force-frequency relationship, and MUFRs from submaximal to maximal voluntary contractile intensities were assessed in the hamstrings. Strength and MUFRs were assessed at two presumably different muscle lengths by varying the knee joint angles (90° and 160°). Knee flexion MVCs were 60-70% greater in the extended position (160°). The frequency required to elicit 50% of maximum tetanic torque was 16-17 Hz. Mean MUFRs at 25-50% MVC were 9-31% less in the biceps femoris compared with the semimembranosus-semitendinosus group. Knee joint angle (muscle length) influenced MUFRs such that mean MUFRs were greater in the shortened (90°) position at 50% and 100% MVC. Compared with previous reports, mean maximal MUFRs in the hamstrings are greater than those in the quadriceps and triceps surae and somewhat less than those in the tibialis anterior. Mean maximal MUFRs in the hamstrings are influenced by changes in knee joint angle, with lower firing rates in the biceps femoris compared with the semimembranosus-semitendinosus muscle group. We studied motor unit firing rates (MUFRs) at various voluntary contraction intensities in the hamstrings, one of the only major lower limb muscles to have MUFRs affected by muscle length changes. Within the hamstrings muscle-specific differences have greater impact on MUFRs than length changes, with the biceps femoris

  6. Species production and heat release rates in two-layered natural gas fires

    SciTech Connect

    Zukoski, E.E.; Morehart, J.H.; Kubota, T.; Toner, S.J. )

    1991-02-01

    A fire burning in an enclosure with restricted ventilation will result in the accumulation of a layer of warm products of combustion mixed with entrained air adjacent to the ceiling. For many conditions, the depth of this layer will extend to occupy a significant fraction of the volume of the room. Eventually, the interface between this vitiated ceiling layer and the uncontaminated environment below will position itself so that a large portion of the combustion processes occur in this vitiated layer. A description is given of experimental work concerning the rates of formation of product species and heat release in a turbulent, buoyant natural gas diffusion flame burning in this two-layered configuration. The enclosure was modeled by placing a hood above a burner so that it accumulated the plume gases, and the unsteady development of the ceiling layer was modeled by the direct addition of air into the upper portion of the hood. Measurements of the composition of these gases allowed the computation of stoichiometries and heat release rates. These investigations showed that the species produced in the flame depend primarily on the stoichiometry of the gases present in the ceiling layer and weakly on the temperature of the layer, but are independent of the fuel pair ratio of the mass transported into the layer by the plume. Heat release rates in the fires were compared to a theoretical limit based on a stoichiometric reaction of fuel and air with excess components left unchanged by the combustion.

  7. The empirical relationship between satellite-derived tropospheric NO2 and fire radiative power and possible implications for fire emission rates of NOx

    NASA Astrophysics Data System (ADS)

    Schreier, Stefan F.; Richter, Andreas; Kaiser, Johannes W.; Schepaschenko, Dmitry; Shvidenko, Anatoly; Hilboll, Andreas; Burrows, John P.

    2014-05-01

    Vegetation fires across the globe have various impacts on Earth systems such as the atmosphere and biosphere. Every year, large quantities of biomass in different ecosystems are burned, either started by lightning strikes or caused by humans. Consequently, a considerable amount of trace gases (e.g. NOx) and aerosols is released into the atmosphere. As nitrogen oxides (NOx) affect atmospheric chemistry, air quality, and climate, a quantification of the total emissions is needed. Although several approaches have been developed for the estimation of NOx emissions from fires, they still suffer from large uncertainties. We present a simple statistical approach to estimate fire emission rates (FERs) of NOx based on the linear relationship between satellite-observed tropospheric NO2 vertical columns (TVC NO2) and fire radiative power (FRP). While the great advantage of the method is the spatial coverage of FERs and the application to various biomes and regions, the uncertainties in the two retrieved parameters can lead to uncertainties in the FERs. In general, the approach performs well for the tropical and subtropical regions where both the number and the spatial extent of vegetation fires are rather large throughout the fire season. However, due to the smaller number of fires and the patchy spatial occurrence, the estimation of FERs is more complicated in the boreal regions. Nevertheless, it is possible to derive FERs for some characteristic regions in the North American and Eurasian part of the boreal forest biome. The estimated FERs of NOx for the dominating types of vegetation burned are lowest for open shrublands, savannas, and boreal forest (0.28-1.03 g NOx s-1 MW-1) and highest for croplands and woody savannas (0.82-1.56 g NOx s-1 MW-1). Interestingly, there are large regional discrepancies of up to 40 % observed for evergreen broadleaf forest and boreal forest. Possible explanations for these regional discrepancies are discussed.

  8. Hardening by cooling rate control and post-firing heat treatment in Pd-Ag-Sn alloy for bonding porcelain.

    PubMed

    Yu, Young-Jun; Seol, Hyo-Joung; Cho, Mi-Hyang; Kim, Hyung-Il; Kwon, Yong Hoon

    2016-01-01

    The aim of this study was to determine the hardening effect by controlling the cooling rate during the porcelain firing process and performing an additional post-firing heat treatment in a Pd-Ag-Sn alloy. The most effective cooling rate for alloy hardening was determined by cooling the specimens at various cooling rates after oxidation treatment. A subsequent porcelain firing simulation followed by cooling at the selected cooling rate was performed. A post-firing heat treatment was then done at 600°C in a porcelain furnace. The hardening mechanism was characterized by a hardness test, X-ray diffraction, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. Alloy softening occurred during the porcelain firing process followed by cooling at a controlled cooling rate. A post-firing heat treatment allowed apparent precipitation hardening. It is advisable to perform a postfiring heat treatment at 600°C in a porcelain furnace by annealing metal substructure after porcelain fusing.

  9. Safety Tips: Dangerous Demos.

    ERIC Educational Resources Information Center

    Nagel, Miriam C.

    1986-01-01

    Discusses topics and issues related to conducting dangerous and/or potentially dangerous demonstrations. Includes a number of resources that secondary and college teachers can consult for additional information. (JN)

  10. The effect of fire retardants on the heat-release rate of building materials

    NASA Astrophysics Data System (ADS)

    Martin, S. B.; Inman, L. B.

    1981-07-01

    A method was developed for making up thick cellulosic specimens with thermocouples implanted at various depths to determine the time dependent temperature profiles when exposed to external radiant fluxes. Specimens of alpha cellulose, both untreated and treated with 2 percent by weight of Na2B4O7, were exposed to an applied radiant flux of 3.7 W/sq cm in the heat release rate calorimeter in order to examine the effect of the fire retardants on the heat release rate. The results on a limited number of tests suggest that the char enhancement, produced by the presence of Na2B4O7, reduces the heat release rate mainly by the reduction of the caloric value of the volatile products rather than by the insulating effect of the increased char layer thickness.

  11. Using satellite fire detection to calibrate components of the fire weather index system in Malaysia and Indonesia.

    PubMed

    Dymond, Caren C; Field, Robert D; Roswintiarti, Orbita; Guswanto

    2005-04-01

    Vegetation fires have become an increasing problem in tropical environments as a consequence of socioeconomic pressures and subsequent land-use change. In response, fire management systems are being developed. This study set out to determine the relationships between two aspects of the fire problems in western Indonesia and Malaysia, and two components of the Canadian Forest Fire Weather Index System. The study resulted in a new method for calibrating components of fire danger rating systems based on satellite fire detection (hotspot) data. Once the climate was accounted for, a problematic number of fires were related to high levels of the Fine Fuel Moisture Code. The relationship between climate, Fine Fuel Moisture Code, and hotspot occurrence was used to calibrate Fire Occurrence Potential classes where low accounted for 3% of the fires from 1994 to 2000, moderate accounted for 25%, high 26%, and extreme 38%. Further problems arise when there are large clusters of fires burning that may consume valuable land or produce local smoke pollution. Once the climate was taken into account, the hotspot load (number and size of clusters of hotspots) was related to the Fire Weather Index. The relationship between climate, Fire Weather Index, and hotspot load was used to calibrate Fire Load Potential classes. Low Fire Load Potential conditions (75% of an average year) corresponded with 24% of the hotspot clusters, which had an average size of 30% of the largest cluster. In contrast, extreme Fire Load Potential conditions (1% of an average year) corresponded with 30% of the hotspot clusters, which had an average size of 58% of the maximum. Both Fire Occurrence Potential and Fire Load Potential calibrations were successfully validated with data from 2001. This study showed that when ground measurements are not available, fire statistics derived from satellite fire detection archives can be reliably used for calibration. More importantly, as a result of this work, Malaysia and

  12. Mechanisms of sustained high firing rates in two classes of vestibular nucleus neurons: differential contributions of resurgent Na, Kv3, and BK currents.

    PubMed

    Gittis, Aryn H; Moghadam, Setareh H; du Lac, Sascha

    2010-09-01

    To fire at high rates, neurons express ionic currents that work together to minimize refractory periods by ensuring that sodium channels are available for activation shortly after each action potential. Vestibular nucleus neurons operate around high baseline firing rates and encode information with bidirectional modulation of firing rates up to several hundred Hz. To determine the mechanisms that enable these neurons to sustain firing at high rates, ionic currents were measured during firing by using the action potential clamp technique in vestibular nucleus neurons acutely dissociated from transgenic mice. Although neurons from the YFP-16 line fire at rates higher than those from the GIN line, both classes of neurons express Kv3 and BK currents as well as both transient and resurgent Na currents. In the fastest firing neurons, Kv3 currents dominated repolarization at all firing rates and minimized Na channel inactivation by rapidly transitioning Na channels from the open to the closed state. In slower firing neurons, BK currents dominated repolarization at the highest firing rates and sodium channel availability was protected by a resurgent blocking mechanism. Quantitative differences in Kv3 current density across neurons and qualitative differences in immunohistochemically detected expression of Kv3 subunits could account for the difference in firing range within and across cell classes. These results demonstrate how divergent firing properties of two neuronal populations arise through the interplay of at least three ionic currents.

  13. Estimation of Fire Radiative Energy in Siberia Using MODIS Data

    NASA Astrophysics Data System (ADS)

    Shvetsov, Eugene; Ponomarev, Evgenii

    2014-05-01

    The intensity of heat release during biomass combustion is an important characteristic of wildfires. Space-borne systems, such as MODIS radiometer, provide observations of fire locations, as well as an estimate of the amount of radiant energy emitted by the fire. Such measures of fire radiative power (FRP) provide information on the fireline heat release intensity and on the rate of biomass combustion in large scale and are important for the analysis of fire impact on vegetation. In this study we analyzed the spatial distribution and temporal dynamics of detected wildfires in Siberia considering their radiative power. For the analysis we used database of fire detections made by MODIS instrument located on TERRA and AQUA satellites for 2002- 2013. For the detected fire pixels the frequency of their occurrence was calculated depending on the radiative power. More than 80% of all detected pixels had radiative power less than 100 MW. The distribution of fires according to their radiative power values was obtained for different regions of Siberia characterized by various vegetation and climatic conditions. Geospatial analysis performed using vegetation maps for the territory of Siberia and GIS layers of active fire detections showed that fires in deciduous and pine forests generally had lower intensities than fires in larch and spruce/fir forests. The rate of biomass combustion and the amount of heat emitted are strongly related to fuel moisture and therefore to weather conditions. In this study weather conditions were characterized using Russian and Canadian weather fire danger indices. Using images obtained during day and night satellite passes daily and long-term dynamics of fire radiative power was calculated. The long-term dynamics of fire radiative power measured by MODIS sensor was compared to weather fire danger indices calculated using on-ground weather stations data located in several Siberian regions mostly liable to fires. For most of the weather stations

  14. Assessment of application-rate dependent effects of a long-term fire retardant chemical (Fire Trol 934) on Typha domingensis germination.

    PubMed

    Angeler, David G; Rodríguez, Marta; Martín, Silvia; Moreno, José M

    2004-05-01

    Although long-term fire retardants (LTR) gain increasingly acceptance as effective tools for wildfire management, recent studies indicate their potential harmfulness in the environment, especially in aquatic ecosystems. This study comprises a first laboratory impact assessment of LTR action in temporal Mediterranean wetlands, using seed germination of Typha domingensis as indicator of impact. Our aim was to identify application rates upon which seed germination could be significantly affected. We tested for low (1 l m(-2)) and high (3 l m(-2)) application rates of Fire Trol 934 which are recommended by the manufacturers as a function of fuel characteristics. In addition, we simulated the impact of a higher application rate of 5 l m(-2) because inhomogeneous dispersal of the LTR during fire control and prevention operations can result in locally elevated applications. Results of a microcosm experiment indicate that application rates of 1 or 3 l m(-2) can impact Typha germination rates in the short-term via indirect LTR-mediated effects on water quality, which suppressed necessary cues for germination. However, a subsequent experiment with Petri dishes, using seeds isolated from the LTR treated sediments did not show significantly different germination rates between the control and the treatments with application rates of 1 or 3 l m(-2). This suggests that retardant pre-application germination success could be recovered in nature once the retardant is eliminated. By contrast, seeds almost completely failed to germinate in the microcosm experiment and the subsequent Petri dish essay when an application rate of 5 l m(-2) was used. This suggests a critical level upon which Typha seed germination may be perpetually limited. Research should be extended to other plant species to provide fire managers with guidelines for environmentally safe use of LTR in the Mediterranean region.

  15. Interpersonal Aspects of Dangerousness.

    ERIC Educational Resources Information Center

    Held, Barbara S.; And Others

    1979-01-01

    An interpersonal theory of dangerousness asserts that dangerousness is a function of perceptions and attributions within an interpersonal context, rather than a stable personality trait. Using the guards and 78 inmates of a penal complex, the interpersonal theory of dangerousness was tested from a racial perspective. (Author)

  16. [Dangerous games in schoolchildren].

    PubMed

    Le Heuzey, M-F

    2011-02-01

    Dangerous games inside or outside school are a serious social phenomenon, but unfortunately underrecognized. Aggressive games are a part of school bullying, which is in expansion. Choking games are very dangerous, with many deaths or serious neurologic complications. Pediatricians should be knowledgeable about risky behaviors encountered by their patients, and provide guidance about its dangers. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  17. Interpersonal Aspects of Dangerousness.

    ERIC Educational Resources Information Center

    Held, Barbara S.; And Others

    1979-01-01

    An interpersonal theory of dangerousness asserts that dangerousness is a function of perceptions and attributions within an interpersonal context, rather than a stable personality trait. Using the guards and 78 inmates of a penal complex, the interpersonal theory of dangerousness was tested from a racial perspective. (Author)

  18. Analytical approximations of the firing rate of an adaptive exponential integrate-and-fire neuron in the presence of synaptic noise.

    PubMed

    Hertäg, Loreen; Durstewitz, Daniel; Brunel, Nicolas

    2014-01-01

    Computational models offer a unique tool for understanding the network-dynamical mechanisms which mediate between physiological and biophysical properties, and behavioral function. A traditional challenge in computational neuroscience is, however, that simple neuronal models which can be studied analytically fail to reproduce the diversity of electrophysiological behaviors seen in real neurons, while detailed neuronal models which do reproduce such diversity are intractable analytically and computationally expensive. A number of intermediate models have been proposed whose aim is to capture the diversity of firing behaviors and spike times of real neurons while entailing the simplest possible mathematical description. One such model is the exponential integrate-and-fire neuron with spike rate adaptation (aEIF) which consists of two differential equations for the membrane potential (V) and an adaptation current (w). Despite its simplicity, it can reproduce a wide variety of physiologically observed spiking patterns, can be fit to physiological recordings quantitatively, and, once done so, is able to predict spike times on traces not used for model fitting. Here we compute the steady-state firing rate of aEIF in the presence of Gaussian synaptic noise, using two approaches. The first approach is based on the 2-dimensional Fokker-Planck equation that describes the (V,w)-probability distribution, which is solved using an expansion in the ratio between the time constants of the two variables. The second is based on the firing rate of the EIF model, which is averaged over the distribution of the w variable. These analytically derived closed-form expressions were tested on simulations from a large variety of model cells quantitatively fitted to in vitro electrophysiological recordings from pyramidal cells and interneurons. Theoretical predictions closely agreed with the firing rate of the simulated cells fed with in-vivo-like synaptic noise.

  19. Estimation of population firing rates and current source densities from laminar electrode recordings.

    PubMed

    Pettersen, Klas H; Hagen, Espen; Einevoll, Gaute T

    2008-06-01

    This model study investigates the validity of methods used to interpret linear (laminar) multielectrode recordings. In computer experiments extracellular potentials from a synaptically activated population of about 1,000 pyramidal neurons are calculated using biologically realistic compartmental neuron models combined with electrostatic forward modeling. The somas of the pyramidal neurons are located in a 0.4 mm high and wide columnar cylinder, mimicking a stimulus-evoked layer-5 population in a neocortical column. Current-source density (CSD) analysis of the low-frequency part (<500 Hz) of the calculated potentials (local field potentials, LFP) based on the 'inverse' CSD method is, in contrast to the 'standard' CSD method, seen to give excellent estimates of the true underlying CSD. The high-frequency part (>750 Hz) of the potentials (multi-unit activity, MUA) is found to scale approximately as the population firing rate to the power 3/4 and to give excellent estimates of the underlying population firing rate for trial-averaged data. The MUA signal is found to decay much more sharply outside the columnar populations than the LFP.

  20. Firing-rate resonances in the peripheral auditory system of the cricket, Gryllus bimaculatus.

    PubMed

    Rau, Florian; Clemens, Jan; Naumov, Victor; Hennig, R Matthias; Schreiber, Susanne

    2015-11-01

    In many communication systems, information is encoded in the temporal pattern of signals. For rhythmic signals that carry information in specific frequency bands, a neuronal system may profit from tuning its inherent filtering properties towards a peak sensitivity in the respective frequency range. The cricket Gryllus bimaculatus evaluates acoustic communication signals of both conspecifics and predators. The song signals of conspecifics exhibit a characteristic pulse pattern that contains only a narrow range of modulation frequencies. We examined individual neurons (AN1, AN2, ON1) in the peripheral auditory system of the cricket for tuning towards specific modulation frequencies by assessing their firing-rate resonance. Acoustic stimuli with a swept-frequency envelope allowed an efficient characterization of the cells' modulation transfer functions. Some of the examined cells exhibited tuned band-pass properties. Using simple computational models, we demonstrate how different, cell-intrinsic or network-based mechanisms such as subthreshold resonances, spike-triggered adaptation, as well as an interplay of excitation and inhibition can account for the experimentally observed firing-rate resonances. Therefore, basic neuronal mechanisms that share negative feedback as a common theme may contribute to selectivity in the peripheral auditory pathway of crickets that is designed towards mate recognition and predator avoidance.

  1. A method for mapping fire hazard and risk across multiple scales and its application in fire management

    Treesearch

    Robert E. Keane; Stacy A. Drury; Eva C. Karau; Paul F. Hessburg; Keith M. Reynolds

    2010-01-01

    This paper presents modeling methods for mapping fire hazard and fire risk using a research model called FIREHARM (FIRE Hazard and Risk Model) that computes common measures of fire behavior, fire danger, and fire effects to spatially portray fire hazard over space. FIREHARM can compute a measure of risk associated with the distribution of these measures over time using...

  2. Fire, humans and landscape. Is there a connection?

    NASA Astrophysics Data System (ADS)

    Valese, Eva; Ascoli, Davide; Conedera, Marco; Held, Alex

    2013-04-01

    Fire evolved on the earth under the direct influence of climate and the accumulation of burnable biomass at various times and spatial scales. As a result, fire regimes depend not only on climatic and biological factors, but also greatly reflect the cultural background of how people do manage ecosystems and fire. A new awareness among scientists and managers has been rising about the ecological role of fire and the necessity to understand its past natural and cultural dynamics in different ecosystems, in order to preserve present ecosystem functionality and minimize management costs and negative impacts. As a consequence we assisted in the last decades to a general shift from the fire control to the fire management approach, where fire prevention, fire danger rating, fire ecology, fire pre-suppression and suppression strategies are fully integrated in the landscape management. Nowadays, a large number of authors recognize that a total suppression strategy, as the one adopted during last decades, leads to a fire paradox: the more we fight for putting out all fires, the more extreme events occur and cause long term damages. The aim of this review is to provide a state of art about the connection between fire, humans and landscape, along time and space. Negative and positive impacts on ecosystem services and values are put in evidence, as well as their incidence on human aptitude to fire use as to fire suppression. In order to capture a consistent fragment of fire history, palaeofires and related palynological studies are considered. They enable a valuable, even if partial, look at the millenary fire regime. Actual strategies and future directions are described in order to show what are the alternatives for living with fire, since removing completely this disturbance from earth is not a option, nor feasible neither advisable. Examples from the world, in particular from the Alps and the Mediterranean basin, are shown for better illustrating the signature of

  3. Contribution of Somatic and Dendritic SK Channels in the Firing Rate of Deep Cerebellar Nuclei: Implication in Cerebellar Ataxia

    PubMed Central

    Abbasi, Samira; Abbasi, Ataollah; Sarbaz, Yashar; Shahabi, Parviz

    2016-01-01

    Introduction: Loss of inhibitory output from Purkinje cells leads to hyperexcitability of the Deep Cerebellar Nuclei (DCN), which results in cerebellar ataxia. Also, inhibition of small-conductance calcium-activated potassium (SK) channel increases firing rate of DCN, which could cause cerebellar ataxia. Therefore, SK channel activators can be effective in reducing the symptoms of this disease, and used for the treatment of cerebellar ataxia. In this regard, we hypothesized that blockade of SK channels in different compartments of DCN would increase firing rate with different value. The location of these channels has different effects on increasing firing rate. Methods: In this study, multi-compartment computational model of DCN was used. This computational stimulation allowed us to study the changes in the firing activity of DCN neuron without concerns about interfering parameters in the experiment. Results: The simulation results demonstrated that blockade of somatic and dendritic SK channel increased the firing rate of DCN. In addition, after hyperpolarization (AHP) amplitude increased with blocking SK channel, and its regularity and resting potential changed. However, action potentials amplitude and duration had no significant changes. The simulation results illustrated a more significant contribution of SK channels on the dendritic tree to the DCN firing rate. SK channels in the proximal dendrites have more impact on firing rate compared to distal dendrites. Discussion: Therefore, inhibition of SK channel in DCN can cause cerebellar ataxia, and SK channel openers can have a therapeutic effect on cerebellar ataxia. In addition, the location of SK channels could be important in therapeutic goals. Dendritic SK channels can be a more effective target compared to somatic SK channels. PMID:27303600

  4. 41 CFR 102-74.255 - How must occupant evacuation or relocation be accomplished when there is immediate danger to...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... danger to persons or property, such as fire, explosion or the discovery of an explosive device (not... immediate danger to persons or property, such as fire, explosion or the discovery of an explosive device... evacuation or relocation be accomplished when there is immediate danger to persons or property, such as...

  5. 41 CFR 102-74.255 - How must occupant evacuation or relocation be accomplished when there is immediate danger to...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... danger to persons or property, such as fire, explosion or the discovery of an explosive device (not... immediate danger to persons or property, such as fire, explosion or the discovery of an explosive device... evacuation or relocation be accomplished when there is immediate danger to persons or property, such as...

  6. 41 CFR 102-74.255 - How must occupant evacuation or relocation be accomplished when there is immediate danger to...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... danger to persons or property, such as fire, explosion or the discovery of an explosive device (not... immediate danger to persons or property, such as fire, explosion or the discovery of an explosive device... evacuation or relocation be accomplished when there is immediate danger to persons or property, such as...

  7. 41 CFR 102-74.255 - How must occupant evacuation or relocation be accomplished when there is immediate danger to...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... danger to persons or property, such as fire, explosion or the discovery of an explosive device (not... immediate danger to persons or property, such as fire, explosion or the discovery of an explosive device... evacuation or relocation be accomplished when there is immediate danger to persons or property, such as...

  8. Allocating resources to large wildland fires: a model with stochastic production rates

    Treesearch

    Romain Mees; David Strauss

    1992-01-01

    Wildland fires that grow out of the initial attack phase are responsible for most of the damage and burned area. We model the allocation of fire suppression resources (ground crews, engines, bulldozers, and airdrops) to these large fires. The fireline at a given future time is partitioned into homogeneous segments on the basis of fuel type, available resources, risk,...

  9. Effectiveness of two contrasting mulching rates to reduce post-fire soil and organic matter losses

    NASA Astrophysics Data System (ADS)

    Silva, Flavio; Prats, Sergio; Vieira, Diana; Puga, João; Lopes, Rita; Gonzaléz-Pelayo, Oscar; Caetano, Ana; Campos, Isabel; Keizer, Jacob

    2017-04-01

    Wildfire-affected soils can reveal strong responses in runoff generation and associated soil (fertility) losses, thereby constituting a major threat to the typically shallow and poor forest soils of the Portuguese mountain areas. Mulching with logging residues from these forests has proven to provide a protective soil cover that is highly effective in reducing post-fire runoff and especially erosion (Prats et al., 2012, 2014, 2016a, 2016b). However, these past experiments have all applied comparatively large amounts of forest residues, in the order of 10 Mg ha-1, so that the relationship between application rate and effectiveness is still poorly known. Such relationship would nonetheless be of crucial importance for the employment of forest residue mulching in practice, as one of the possible emergency stabilization measures to be contemplated in post-fire land management of a recently-burned area. Further research gaps that exist in relation to post-fire forest residue mulching include its effectiveness in reducing soil fertility losses (C, N, P; Ferreira et al., 2016a, 2016b) and in minimizing export of contaminants (especially PAHs and metals; Campos et al., 2016), and its (secondary) impacts on soil biological activity and diversity (Puga et al., 2016) and on forest productivity (including through the addition of organic matter to the soil surface, partially replacing the burned litter layer; Prats et al. 2016b). In the framework of the EU-project RECARE, the effectiveness of two contrasting mulching rates with forest logging residues has been tested following a wildfire that on August 9th - 10th 2015 consumed some 715 ha of eucalypt plantations in the Semide municipality, central Portugal. Commercially-available logging residues (chopped bark and twigs) from eucalypt plantations were purchased, transported to the study site and applied to six out of nine 16 m2 erosion bounded plots that had been installed in a burned eucalypt plantation using a randomized

  10. Thermodynamic constraints on neural dimensions, firing rates, brain temperature and size.

    PubMed

    Karbowski, Jan

    2009-12-01

    There have been suggestions that heat caused by cerebral metabolic activity may constrain mammalian brain evolution, architecture, and function. This article investigates physical limits on brain wiring and corresponding changes in brain temperature that are imposed by thermodynamics of heat balance determined mainly by Na(+)/K(+)-ATPase, cerebral blood flow, and heat conduction. It is found that even moderate firing rates cause significant intracellular Na(+) build-up, and the ATP consumption rate associated with pumping out these ions grows nonlinearly with frequency. Surprisingly, the power dissipated by the Na(+)/K(+) pump depends biphasically on frequency, which can lead to the biphasic dependence of brain temperature on frequency as well. Both the total power of sodium pumps and brain temperature diverge for very small fiber diameters, indicating that too thin fibers are not beneficial for thermal balance. For very small brains blood flow is not a sufficient cooling mechanism deep in the brain. The theoretical lower bound on fiber diameter above which brain temperature is in the operational regime is strongly frequency dependent but finite due to synaptic depression. For normal neurophysiological conditions this bound is at least an order of magnitude smaller than average values of empirical fiber diameters, suggesting that neuroanatomy of the mammalian brains operates in the thermodynamically safe regime. Analytical formulas presented can be used to estimate average firing rates in mammals, and relate their changes to changes in brain temperature, which can have important practical applications. In general, activity in larger brains is found to be slower than in smaller brains.

  11. Chaos-induced modulation of reliability boosts output firing rate in downstream cortical areas

    NASA Astrophysics Data System (ADS)

    Tiesinga, P. H.

    2004-03-01

    The reproducibility of neural spike train responses to an identical stimulus across different presentations (trials) has been studied extensively. Reliability, the degree of reproducibility of spike trains, was found to depend in part on the amplitude and frequency content of the stimulus [J. Hunter and J. Milton, J. Neurophysiol. 90, 387 (2003)]. The responses across different trials can sometimes be interpreted as the response of an ensemble of similar neurons to a single stimulus presentation. How does the reliability of the activity of neural ensembles affect information transmission between different cortical areas? We studied a model neural system consisting of two ensembles of neurons with Hodgkin-Huxley-type channels. The first ensemble was driven by an injected sinusoidal current that oscillated in the gamma-frequency range (40 Hz) and its output spike trains in turn drove the second ensemble by fast excitatory synaptic potentials with short term depression. We determined the relationship between the reliability of the first ensemble and the response of the second ensemble. In our paradigm the neurons in the first ensemble were initially in a chaotic state with unreliable and imprecise spike trains. The neurons became entrained to the oscillation and responded reliably when the stimulus power was increased by less than 10%. The firing rate of the first ensemble increased by 30%, whereas that of the second ensemble could increase by an order of magnitude. We also determined the response of the second ensemble when its input spike trains, which had non-Poisson statistics, were replaced by an equivalent ensemble of Poisson spike trains. The resulting output spike trains were significantly different from the original response, as assessed by the metric introduced by Victor and Purpura [J. Neurophysiol. 76, 1310 (1996)]. These results are a proof of principle that weak temporal modulations in the power of gamma-frequency oscillations in a given cortical area

  12. Risk of large-scale fires in boreal forests of Finland under changing climate

    NASA Astrophysics Data System (ADS)

    Lehtonen, I.; Venäläinen, A.; Kämäräinen, M.; Peltola, H.; Gregow, H.

    2016-01-01

    The target of this work was to assess the impact of projected climate change on forest-fire activity in Finland with special emphasis on large-scale fires. In addition, we were particularly interested to examine the inter-model variability of the projected change of fire danger. For this purpose, we utilized fire statistics covering the period 1996-2014 and consisting of almost 20 000 forest fires, as well as daily meteorological data from five global climate models under representative concentration pathway RCP4.5 and RCP8.5 scenarios. The model data were statistically downscaled onto a high-resolution grid using the quantile-mapping method before performing the analysis. In examining the relationship between weather and fire danger, we applied the Canadian fire weather index (FWI) system. Our results suggest that the number of large forest fires may double or even triple during the present century. This would increase the risk that some of the fires could develop into real conflagrations which have become almost extinct in Finland due to active and efficient fire suppression. However, the results reveal substantial inter-model variability in the rate of the projected increase of forest-fire danger, emphasizing the large uncertainty related to the climate change signal in fire activity. We moreover showed that the majority of large fires in Finland occur within a relatively short period in May and June due to human activities and that FWI correlates poorer with the fire activity during this time of year than later in summer when lightning is a more important cause of fires.

  13. Firing rate modulation of human motor units in different muscles during isometric contraction with various forces.

    PubMed

    Seki, K; Narusawa, M

    1996-05-06

    To examine the factors affecting the control of human motor units, rate coding strategies of the motor units were investigated in upper limb and intrinsic hand muscles during voluntary isometric contraction of steady force levels up to 80% of maximal voluntary contraction. Numerous spike trains from single motor units were recorded from the m. first dorsal interosseous (FDI) and the m. biceps brachii (BB) of eight human subjects by means of tungsten micro-electrodes, and the mean firing rate (MFR) was calculated for each subject and inter-individual comparisons made. The MFRs of the FDI were larger than that of the BB at the higher force level, and substantial differences were not found between these muscles at the lower force level. The slope of the linear regression line of MFRs vs. exerted forces for the FDI was more than twice that for the BB. Therefore, isometric force control of the FDI depends more on the rate coding strategy. The difference in rate coding between the FDI and BB motor units may be determined by factors other than muscle fiber composition, because both muscles are known to possess a similar composition of fiber types. Possible mechanisms underlying these characteristics of rate coding strategy are considered in this report.

  14. Interaction of Kv3 potassium channels and resurgent sodium current influences the rate of spontaneous firing of Purkinje neurons.

    PubMed

    Akemann, Walther; Knöpfel, Thomas

    2006-04-26

    Purkinje neurons spontaneously generate action potentials in the absence of synaptic drive and thereby exert a tonic, yet plastic, input to their target cells in the deep cerebellar nuclei. Purkinje neurons express two ionic currents with biophysical properties that are specialized for high-frequency firing: resurgent sodium currents and potassium currents mediated by Kv3.3. How these ionic currents determine the intrinsic activity of Purkinje neurons has only partially been understood. Purkinje neurons from mutant mice lacking Kv3.3 have a reduced rate of spontaneous firing. Dynamic-clamp recordings demonstrated that normal firing rates are rescued by inserting artificial Kv3 currents into Kv3.3 knock-out Purkinje neurons. Numerical simulations indicated that Kv3.3 increases the spontaneous firing rate via cooperation with resurgent sodium currents. We conclude that the rate of spontaneous action potential firing of Purkinje neurons is controlled by the interaction of Kv3.3 potassium currents and resurgent sodium currents.

  15. Closed-loop firing rate regulation of two interacting excitatory and inhibitory neural populations of the basal ganglia.

    PubMed

    Haidar, Ihab; Pasillas-Lépine, William; Chaillet, Antoine; Panteley, Elena; Palfi, Stéphane; Senova, Suhan

    2016-02-01

    This paper develops a new closed-loop firing rate regulation strategy for a population of neurons in the subthalamic nucleus, derived using a model-based analysis of the basal ganglia. The system is described using a firing rate model, in order to analyse the generation of beta-band oscillations. On this system, a proportional regulation of the firing rate reduces the gain of the subthalamo-pallidal loop in the parkinsonian case, thus impeding pathological oscillation generation. A filter with a well-chosen frequency is added to this proportional scheme, in order to avoid a potential instability of the feedback loop due to actuation and measurement delays. Our main result is a set of conditions on the parameters of the stimulation strategy that guarantee both its stability and a prescribed delay margin. A discussion on the applicability of the proposed method and a complete set of mathematical proofs is included.

  16. Fire Risk and Residential Development: A GIS Analysis

    Treesearch

    Jennifer L. Rechel; James B. Davis; Ted K. Bradshaw

    1992-01-01

    Population growth is rapid in rural areas in California. This growth into the wildland-urban interface makes fire protection and suppression more difficult. Fire managers have opportunities to reduce fire danger by improving housing development patterns; however, the overall density and placement of houses is usually set by criteria other than fire danger. By...

  17. Attentional modulation of firing rate varies with burstiness across putative pyramidal neurons in macaque visual area V4.

    PubMed

    Anderson, Emily B; Mitchell, Jude F; Reynolds, John H

    2011-07-27

    One of the most well established forms of attentional modulation is an increase in firing rate when attention is directed into the receptive field of a neuron. The degree of rate modulation, however, can vary considerably across individual neurons, especially among broad spiking neurons (putative pyramids). We asked whether this heterogeneity might be correlated with a neuronal response property that is used in intracellular recording studies to distinguish among distinct neuronal classes: the burstiness of the neuronal spike train. We first characterized the burst spiking behavior of visual area V4 neurons and found that this varies considerably across the population, but we did not find evidence for distinct classes of burst behavior. Burstiness did, however, vary more widely across the class of neurons that shows the greatest heterogeneity in attentional modulation, and within that class, burstiness helped account for differences in attentional modulation. Among these broad spiking neurons, rate modulation was primarily restricted to bursty neurons, which as a group showed a highly significant increase in firing rate with attention. Furthermore, every bursty broad spiking neuron whose firing rate was significantly modulated by attention exhibited an increase in firing rate. In contrast, non-bursty broad spiking neurons exhibited no net attentional modulation, and, although some individual neurons did show significant rate modulation, these were divided among neurons showing increases and decreases. These findings show that macaque area V4 shows a range of bursting behavior and that the heterogeneity of attentional modulation can be explained, in part, by variation in burstiness.

  18. Response time, pistol fire position variability, and pistol draw success rates for hip and thigh holsters.

    PubMed

    Campbell, Amity; Roelofs, Andrea; Davey, Paul; Straker, Leon

    2013-04-01

    The aim of this study was to investigate the effect of pistol holster position on pistol draw time and performance of police officers. Proficient use of the lethal force option is critical to an officer's ability to survive. Traditionally, pistols were worn in hip holsters; however, recently, thigh holsters have also become popular. The effect of holster position on pistol draw performance has not been investigated. For this study, 27 police officers, representing a range of holster familiarity, years of service, and gender, were assessed drawing a training pistol from both the thigh and hip holster positions via a 3-D motion analysis system. Participants were required to draw and fire toward a target as quickly and accurately as possible following a visual stimulus, three times successfully. Temporal characteristics, accuracy variability, and draw success rate were compared between the thigh and hip holster with repeated-measures ANOVA both unadjusted and adjusted for familiarity, years of service, and gender (p < .05). No differences in the temporal variables, accuracy variability, or success rate were detected between the hip and thigh holster positions, either adjusted or unadjusted. Holster familiarity was found to significantly affect draw success rate, with participants more successful when drawing from their familiar holster. Hip and thigh holster positions are both viable options in terms of draw time and accuracy. However, draw success rate will be negatively affected during initial use of an unfamiliar holster position. Further research should address the effect of familiarization on draw performance.

  19. Climate-induced variations in global wildfire danger from 1979 to 2013

    Treesearch

    W. Matt Jolly; Mark A. Cochrane; Patrick H. Freeborn; Zachary A. Holden; Timothy J. Brown; Grant J. Williamson; David M. J. S. Bowman

    2015-01-01

    Climate strongly influences global wildfire activity, and recent wildfire surges may signal fire weather-induced pyrogeographic shifts. Here we use three daily global climate data sets and three fire danger indices to develop a simple annual metric of fire weather season length, and map spatio-temporal trends from 1979 to 2013. We show that fire weather seasons have...

  20. On how correlations between excitatory and inhibitory synaptic inputs maximize the information rate of neuronal firing

    PubMed Central

    Puzerey, Pavel A.; Galán, Roberto F.

    2014-01-01

    Cortical neurons receive barrages of excitatory and inhibitory inputs which are not independent, as network structure and synaptic kinetics impose statistical correlations. Experiments in vitro and in vivo have demonstrated correlations between inhibitory and excitatory synaptic inputs in which inhibition lags behind excitation in cortical neurons. This delay arises in feed-forward inhibition (FFI) circuits and ensures that coincident excitation and inhibition do not preclude neuronal firing. Conversely, inhibition that is too delayed broadens neuronal integration times, thereby diminishing spike-time precision and increasing the firing frequency. This led us to hypothesize that the correlation between excitatory and inhibitory synaptic inputs modulates the encoding of information of neural spike trains. We tested this hypothesis by investigating the effect of such correlations on the information rate (IR) of spike trains using the Hodgkin-Huxley model in which both synaptic and membrane conductances are stochastic. We investigated two different synaptic input regimes: balanced synaptic conductances and balanced currents. Our results show that correlations arising from the synaptic kinetics, τ, and millisecond lags, δ, of inhibition relative to excitation strongly affect the IR of spike trains. In the regime of balanced synaptic currents, for short time lags (δ ~ 1 ms) there is an optimal τ that maximizes the IR of the postsynaptic spike train. Given the short time scales for monosynaptic inhibitory lags and synaptic decay kinetics reported in cortical neurons under physiological contexts, we propose that FFI in cortical circuits is poised to maximize the rate of information transfer between cortical neurons. Our results also provide a possible explanation for how certain drugs and genetic mutations affecting the synaptic kinetics can deteriorate information processing in the brain. PMID:24936182

  1. Effects of Barbell Deadlift Training on Submaximal Motor Unit Firing Rates for the Vastus Lateralis and Rectus Femoris

    PubMed Central

    Stock, Matt S.; Thompson, Brennan J.

    2014-01-01

    Previous investigations that have studied motor unit firing rates following strength training have been limited to small muscles, isometric training, or interventions involving exercise machines. We examined the effects of ten weeks of supervised barbell deadlift training on motor unit firing rates for the vastus lateralis and rectus femoris during a 50% maximum voluntary contraction (MVC) assessment. Twenty-four previously untrained men (mean age  = 24 years) were randomly assigned to training (n = 15) or control (n = 9) groups. Before and following the intervention, the subjects performed isometric testing of the right knee extensors while bipolar surface electromyographic signals were detected from the two muscles. The signals were decomposed into their constituent motor unit action potential trains, and motor units that demonstrated accuracy levels less than 92.0% were not considered for analysis. One thousand eight hundred ninety-two and 2,013 motor units were examined for the vastus lateralis and rectus femoris, respectively. Regression analyses were used to determine the linear slope coefficients (pulses per second [pps]/% MVC) and y-intercepts (pps) of the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. Deadlift training significantly improved knee extensor MVC force (Cohen's d = .70), but did not influence force steadiness. Training had no influence on the slopes and y-intercepts for the mean firing rate and firing rate at recruitment versus recruitment threshold relationships. In agreement with previous cross-sectional comparisons and randomized control trials, our findings do not support the notion that strength training affects the submaximal control of motor units. PMID:25531294

  2. Assessing fire risk in Portugal during the summer fire season

    NASA Astrophysics Data System (ADS)

    Dacamara, C. C.; Pereira, M. G.; Trigo, R. M.

    2009-04-01

    Since 1998, Instituto de Meteorologia, the Portuguese Weather Service has relied on the Canadian Fire Weather Index (FWI) System (van Wagner, 1987) to produce daily forecasts of fire risk. The FWI System consists of six components that account for the effects of fuel moisture and wind on fire behavior. The first three components, i.e. the Fine Fuel Moisture Code (FFMC), the Duff Moisture Code (DMC) and the Drought Code (DC) respectively rate the average moisture content of surface litter, decomposing litter, and organic (humus) layers of the soil. Wind effects are then added to FFMC leading to the Initial Spread Index (ISI) that rates fire spread. The remaining two fuel moisture codes (DMC and DC) are in turn combined to produce the Buildup Index (BUI) that is a rating of the total amount of fuel available for combustion. BUI is finally combined with ISI to produce the Fire Weather Index (FWI) that represents the rate of fire intensity. Classes of fire danger and levels of preparedness are commonly defined on an empirical way for a given region by calibrating the FWI System against wildfire activity as defined by the recorded number of events and by the observed burned area over a given period of time (Bovio and Camia, 1998). It is also a well established fact that distributions of burned areas are heavily skewed to the right and tend to follow distributions of the exponential-type (Cumming, 2001). Based on the described context, a new procedure is presented for calibrating the FWI System during the summer fire season in Portugal. Two datasets were used covering a 28-year period (1980-2007); i) the official Portuguese wildfire database which contains detailed information on fire events occurred in the 18 districts of Continental Portugal and ii) daily values of the six components of the FWI System as derived from reanalyses (Uppala et al., 2005) of the European Centre for Medium-Range Weather Forecasts (ECMWF). Calibration of the FWI System is then performed in two

  3. 41 CFR 102-74.255 - How must occupant evacuation or relocation be accomplished when there is immediate danger to...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... accordance with the plan by sounding the fire alarm system or by other appropriate means when there is... evacuation or relocation be accomplished when there is immediate danger to persons or property, such as fire... danger to persons or property, such as fire, explosion or the discovery of an explosive device (not...

  4. Hydroxyl radical concentrations and Kuwait oil fire emission rates for March 1991

    NASA Astrophysics Data System (ADS)

    McKenna, D. S.; Hord, C. J.; Kent, J. M.

    1995-12-01

    Toward the end of the Gulf War, Iraqi troops damaged several hundred oil wells in Kuwait setting many of them on fire. Measurements made in March 1991, a few weeks after most of the fires had started (Johnson et al., 1991), were used to estimated the total burn rate and the emission rates of individual pollutants. Measurements of the principal carbon species in the plume, obtained from flask samples collected at the same time as continuous measurements of SO2 have been used to derive an "effective" sulphur content of the smoke of 2.4%, almost a third lower than the previous estimate. This sulphur content of 2.4% combined with the capping history of the fires has been used to revise the earlier estimates and provide more detailed information on the speciation of the emissions. It is now estimated that 139×106 t of crude oil were burnt during an 8-month period, resulting in the release of 112×106 t of carbon in carbon dioxide, 3×106 t of carbon in soot, 1.6×106 t of carbon in carbon monoxide, 1.3×106 t of carbon in nonmethane hydrocarbons, 0.11×106 t of nitrogen in nitrogen oxides, and 3.11×106 t of sulphur in sulphur dioxide. In addition to measurements made close to the source of the plume, one flight successfully sampled a plume some 600 km from the fires which had experienced significant photochemical aging. These observations provided a unique data set with which to estimate the rate at which hydrocarbon pollutants in the plume degrade and to infer the hydroxyl radical concentrations which cause that degradation. Most of the aliphatic hydrocarbon concentrations determined from flask samples collected at a range of distances from the Kuwait source conform to a simple loss process proportional to hydrocarbon hydroxyl reactivity and imply a diurnally averaged hydroxyl radical concentration within the plume of 1×106 molecules cm-3. Finally, it is shown that, although theoretically, hydrocarbon concentrations can be combined to predict the difference ratio of

  5. A database on post-fire erosion rates and debris flows in Mediterranean-Basin watersheds

    NASA Astrophysics Data System (ADS)

    Parise, M.; Cannon, S. H.

    2009-04-01

    proceedings. The database derives from critical analysis of the existing literature, integrated by case studies directly studied by the authors. Studies on recently burned areas in the Mediterranean basin are most frequently carried out on small experimental plots, often with simulated rainfall A problem of scale therefore exists when trying to extrapolate the erosion rates (also reported as sediment yields or as sediment losses) from these studies to a watershed scale. Very few articles, on the other hand, were found that document the watershed-scale response of basins to rainfall-induced erosion and debris flows following wildfires. The few reported cases of debris flows in the Mediterranean Basin describe erosion of sediment from the hillslopes and the channels (sometimes down to bedrock), and, for a limited number of sites, failure of discrete landslides. This information indicates that debris-flow generation from recently burned areas in the Mediterranean basin appears to occur primarily through sediment bulking processes. Nevertheless, the database so far compiled shows a distribution of post-fire erosion and debris flows in the western Mediterranean basin (Spain, essentially, but also Portugal), followed by the eastern Mediterranean area (Israel), and then by France, Italy and Greece. Even though still in a preliminary version, that needs to be integrated and updated from further sources, our data compilation allows for the unique opportunity to examine issues related to the generation of post-wildfire debris flows across a variety of environments and under a variety of conditions, and to move from a qualitative conception of the controls on post-fire debris-flow generation to the definition of specific conditions that result in their occurrence. Future activities of the project will include: i) updating and integration of the preliminary version of the database; ii) development of models that can be used to identify the probability of debris-flow occurrence and the

  6. Wildland-urban interface fires and socioeconomic conditions: a case study of a northwestern Patagonia city.

    PubMed

    de Torres Curth, Monica; Biscayart, Carolina; Ghermandi, Luciana; Pfister, Gabriela

    2012-04-01

    In many regions of the world, fires are primarily of anthropogenic origin. In northwestern Patagonia, the number of fires is not correlated with meteorological variables, but is concentrated in urban areas. This study was conducted in the wildland-urban interface (WUI) area of San Carlos de Bariloche (Patagonia, Argentina), within the Nahuel Huapi National Park. WUI fires are particularly problematic because, besides people and goods, they represent a danger to protected areas. We studied the relationship between fire records and socioeconomic indicators within the WUI of San Carlos de Bariloche. We conducted a Multiple Correspondence Factorial Analysis and an Ascendant Hierarchical Classification of the city neighborhoods. The results show that the neighborhoods in Bariloche can be divided into three classes: High Socioeconomic Fire Risk neighborhoods, including neighborhoods with the highest fire rates, where people have low instruction level, high levels of unsatisfied basic needs and high unemployment levels; Low Socioeconomic Fire Risk neighborhoods, that groups neighborhoods which present the opposite characterization, and Moderate Socioeconomic Fire Risk neighborhoods, which are more heterogeneous. Once neighborhoods were classified, a Socioeconomic Fire Risk map was generated, supplementing the existing WUI Fire Danger map. Our results emphasize the relevance of socioeconomic variables to fire policies.

  7. Wildland-Urban Interface Fires and Socioeconomic Conditions: A Case Study of a Northwestern Patagonia City

    NASA Astrophysics Data System (ADS)

    de Torres Curth, Monica; Biscayart, Carolina; Ghermandi, Luciana; Pfister, Gabriela

    2012-04-01

    In many regions of the world, fires are primarily of anthropogenic origin. In northwestern Patagonia, the number of fires is not correlated with meteorological variables, but is concentrated in urban areas. This study was conducted in the wildland-urban interface (WUI) area of San Carlos de Bariloche (Patagonia, Argentina), within the Nahuel Huapi National Park. WUI fires are particularly problematic because, besides people and goods, they represent a danger to protected areas. We studied the relationship between fire records and socioeconomic indicators within the WUI of San Carlos de Bariloche. We conducted a Multiple Correspondence Factorial Analysis and an Ascendant Hierarchical Classification of the city neighborhoods. The results show that the neighborhoods in Bariloche can be divided into three classes: High Socioeconomic Fire Risk neighborhoods, including neighborhoods with the highest fire rates, where people have low instruction level, high levels of unsatisfied basic needs and high unemployment levels; Low Socioeconomic Fire Risk neighborhoods, that groups neighborhoods which present the opposite characterization, and Moderate Socioeconomic Fire Risk neighborhoods, which are more heterogeneous. Once neighborhoods were classified, a Socioeconomic Fire Risk map was generated, supplementing the existing WUI Fire Danger map. Our results emphasize the relevance of socioeconomic variables to fire policies.

  8. What's Your Fire Safety IQ?

    ERIC Educational Resources Information Center

    PTA Today, 1992

    1992-01-01

    The National Fire Protection Association offers a quiz on fire safety designed to help people learn about the major fire dangers and change the way they respond to them. Recommends that families sit down and take the quiz together, focusing on the correct answers provided. (SM)

  9. Motor unit firing rates of the gastrocnemii during maximal brief steady-state contractions in humans.

    PubMed

    Graham, Mitchell T; Rice, Charles L; Dalton, Brian H

    2016-02-01

    The human triceps surae (soleus, medial (MG) and lateral (LG) gastrocnemii) is complex and important for posture and gait. The soleus exhibits markedly lower motor unit firing rates (MUFRs; ∼16Hz) during maximal voluntary isometric contraction (MVC) than other limb muscles, but this information is unknown for the MG and LG. During multiple visits, subjects performed a series of 5-7, ∼7-s plantar flexor MVCs with tungsten microelectrodes inserted into the MG and LG. During a separate testing session, another group of subjects performed submaximal isometric contractions at 25%, 50%, and 75% MVC with inserted fine-wires in the MG, LG and soleus. Maximum steady-state MUFRs for MG and LG (∼23Hz) were not different, but faster than prior reports for the soleus. No differences between the three triceps surae components were detected for 25% or 50% MVC, but at 75% MVC, the MG MUFRs were 31% greater than soleus. The triceps surae exhibit similar torque modulation strategies at <75% MVC, but to achieve higher contraction intensities (>75% MVC) the gastrocnemii rely on faster rates to generate maximal torque than the soleus. Therefore, the MG and LG exhibit a larger range of MUFR capacities.

  10. Post-fire mulching for runoff and erosion mitigation; Part I: Effectiveness at reducing hillslope erosion rates

    Treesearch

    Peter R. Robichaud; Sarah A. Lewis; Joseph W. Wagenbrenner; Louise E. Ashmun; Robert E. Brown

    2013-01-01

    Mulch treatments often are used to mitigate post-fire increases in runoff and erosion rates but the comparative effectiveness of various mulches is not well established. The ability of mulch treatments to reduce sediment yields from natural rainfall and resulting overland flow was measured using hillslope plots on areas burned at high severity following four wildfires...

  11. Time-related changes in firing rates are influenced by recruitment threshold and twitch force potentiation in the first dorsal interosseous.

    PubMed

    Miller, Jonathan D; Herda, Trent J; Trevino, Michael A; Sterczala, Adam J; Ciccone, Anthony B

    2017-08-01

    What is the central question of this study? The influences of motor unit recruitment threshold and twitch force potentiation on the changes in firing rates during steady-force muscular contractions are not well understood. What is the main finding and its importance? The behaviour of motor units during steady force was influenced by recruitment threshold, such that firing rates decreased for lower-threshold motor units but increased for higher-threshold motor units. In addition, individuals with greater changes in firing rates possessed greater twitch force potentiation. There are contradictory reports regarding changes in motor unit firing rates during steady-force contractions. Inconsistencies are likely to be the result of previous studies disregarding motor unit recruitment thresholds and not examining firing rates on a subject-by-subject basis. It is hypothesized that firing rates are manipulated by twitch force potentiation during contractions. Therefore, in this study we examined time-related changes in firing rates at steady force in relationship to motor unit recruitment threshold in the first dorsal interosseous and the influence of twitch force potentiation on such changes in young versus aged individuals. Subjects performed a 12 s steady-force contraction at 50% maximal voluntary contraction, with evoked twitches before and after the contraction to quantify potentiation. Firing rates, in relationship to recruitment thresholds, were determined at the beginning, middle and end of the steady force. There were no firing rate changes for aged individuals. For the young, firing rates decreased slightly for lower-threshold motor units but increased for higher-threshold motor units. Twitch force potentiation was greater for young than aged subjects, and changes in firing rates were correlated with twitch force potentiation. Thus, individuals with greater increases in firing rates of higher-threshold motor units and decreases in lower-threshold motor units

  12. Evaluating crown fire rate of spread predictions from physics-based models

    Treesearch

    C. M. Hoffman; J. Ziegler; J. Canfield; R. R. Linn; W. Mell; C. H. Sieg; F. Pimont

    2015-01-01

    Modeling the behavior of crown fires is challenging due to the complex set of coupled processes that drive the characteristics of a spreading wildfire and the large range of spatial and temporal scales over which these processes occur. Detailed physics-based modeling approaches such as FIRETEC and the Wildland Urban Interface Fire Dynamics Simulator (WFDS) simulate...

  13. Potential dangers of accelerant use in arson.

    PubMed

    Heath, Karen; Kobus, Hilton; Byard, Roger W

    2011-02-01

    Accelerant-enhanced combustion often characterizes a fire that has been deliberately set to disguise a murder scene or to destroy property for insurance purposes. The intensity and rapidity of spread of fires where accelerants have been used are often underestimated by perpetrators who may sustain heat-related injuries. The case of a 49-year-old male who was using gasoline (petrol) as an accelerant is reported to demonstrate another danger of this type of activity. After ignition, an explosion occurred that destroyed the building and caused the death of the victim who was crushed beneath a rear wall of the commercial premises. Gasoline vapour/air mixtures are extremely volatile and may cause significant explosions if exposed to flame. Given the potential danger of explosion, arsonists using accelerants do so at significant risk to themselves and to others in the vicinity.

  14. Differences in globus pallidus neuronal firing rates and patterns relate to different disease biology in children with dystonia

    PubMed Central

    McClelland, V M; Valentin, A; Rey, H G; Lumsden, D E; Elze, M C; Selway, R; Alarcon, G; Lin, J-P

    2016-01-01

    Background The pathophysiology underlying different types of dystonia is not yet understood. We report microelectrode data from the globus pallidus interna (GPi) and globus pallidus externa (GPe) in children undergoing deep brain stimulation (DBS) for dystonia and investigate whether GPi and GPe firing rates differ between dystonia types. Methods Single pass microelectrode data were obtained to guide electrode position in 44 children (3.3–18.1 years, median 10.7) with the following dystonia types: 14 primary, 22 secondary Static and 8 progressive secondary to neuronal brain iron accumulation (NBIA). Preoperative stereotactic MRI determined coordinates for the GPi target. Digitised spike trains were analysed offline, blind to clinical data. Electrode placement was confirmed by a postoperative stereotactic CT scan. Findings We identified 263 GPi and 87 GPe cells. Both GPi and GPe firing frequencies differed significantly with dystonia aetiology. The median GPi firing frequency was higher in the primary group than in the secondary static group (13.5 Hz vs 9.6 Hz; p=0.002) and higher in the NBIA group than in either the primary (25 Hz vs 13.5 Hz; p=0.006) or the secondary static group (25 Hz vs 9.6 Hz; p=0.00004). The median GPe firing frequency was higher in the NBIA group than in the secondary static group (15.9 Hz vs 7 Hz; p=0.013). The NBIA group also showed a higher proportion of regularly firing GPi cells compared with the other groups (p<0.001). A higher proportion of regular GPi cells was also seen in patients with fixed/tonic dystonia compared with a phasic/dynamic dystonia phenotype (p<0.001). The GPi firing frequency showed a positive correlation with 1-year outcome from DBS measured by improvement in the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS-m) score (p=0.030). This association was stronger for the non-progressive patients (p=0.006). Interpretation Pallidal firing rates and patterns differ significantly with dystonia aetiology

  15. Danger signals in stroke.

    PubMed

    Gelderblom, Mathias; Sobey, Christopher G; Kleinschnitz, Christoph; Magnus, Tim

    2015-11-01

    Danger molecules are the first signals released from dying tissue after stroke. These danger signals bind to receptors on immune cells that will result in their activation and the release of inflammatory and neurotoxic mediators, resulting in amplification of the immune response and subsequent enlargement of the damaged brain volume. The release of danger signals is a central event that leads to a multitude of signals and cascades in the affected and neighbouring tissue, therefore providing a potential target for therapy. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Dangerous Electric Waves,

    DTIC Science & Technology

    1982-01-06

    AD-All 283 FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFR OH F/6 19/5 DANGEROUS ELECTRIC WAVES,(U) JAN 82 F X IANCHENG UNCLASS IFI ED FTO-ID(RS)T-O 891...TECHNOLOGY DIVISION DANGEROUS ELECTRIC WAVES by Feng Xiancheng FEB 2 1982 A Approved for public release; distribution unlimited. 82 02 01 070 AlH...FTD -ID(H ST-0891-81 EDITED TANSLATION FTD-ID(RS)T-0891-81 6 January 1982 MICROFICHE NR: FTD-81-C-002058 DANGEROUS ELECTRIC WAVES

  17. Urban Sprawl and Wildfire Danger along the Wildland-Urban Interface

    NASA Astrophysics Data System (ADS)

    Nghiem, S. V.; Kafatos, M.; Myoung, B.

    2015-12-01

    Urban sprawl has created an extensive wildland-urban interface (WUI) where urban areas encroach well into the wilderness that is highly susceptible to wildfire danger. To monitor urbanization along WUI, an innovative approach based on the Dense Sampling Method with the Rosette Transform (DSM-RT) enables the use of satellite scatterometer data to obtain observations without gaps in time and in space at 1-km posting in the decade of the 2000s. To explain how the satellite signature processed with DSM-RT represents physical urban infrastructures, the case of the mega city of Los Angeles is presented with the DSM-RT satellite image overlaid on three-dimensional buildings and road network from the commercial and industrial core of the city to the residential suburb extended into the wild land. Then the rate of urban development in the 2000s in terms of physical urban infrastructure change, rather than the arbitrary boundary defined by administrative or legislative measures, for 14 cities along the San Gabriel Mountains in California are evaluated to rank the degree of urbanization along the local WUI, which may increase the probability of fire ignitions and fire impacts. Moreover, the Enhanced Vegetation Index (EVI) from the MODIS Aqua satellite is used to estimate live fuel moisture (LFM) conditions around the WUI to evaluate fire danger levels, which are consistent to the specific definition currently used by fire agencies in making real-life decisions for fire preparedness pro-actively before the fire occurrence. As an example, a map of EVI-derived LFM for the Colby Fire in 2014 showing a complex spatial pattern of LFM reduction along an extensive WUI illustrates satellite advantage in monitoring LFM over the vast wild land in Southern California. Since the method is based on global satellite data, it is applicable to regions prone to wildfires across the world.

  18. Modelling Odor Decoding in the Antennal Lobe by Combining Sequential Firing Rate Models with Bayesian Inference

    PubMed Central

    Cuevas Rivera, Dario; Bitzer, Sebastian; Kiebel, Stefan J.

    2015-01-01

    The olfactory information that is received by the insect brain is encoded in the form of spatiotemporal patterns in the projection neurons of the antennal lobe. These dense and overlapping patterns are transformed into a sparse code in Kenyon cells in the mushroom body. Although it is clear that this sparse code is the basis for rapid categorization of odors, it is yet unclear how the sparse code in Kenyon cells is computed and what information it represents. Here we show that this computation can be modeled by sequential firing rate patterns using Lotka-Volterra equations and Bayesian online inference. This new model can be understood as an ‘intelligent coincidence detector’, which robustly and dynamically encodes the presence of specific odor features. We found that the model is able to qualitatively reproduce experimentally observed activity in both the projection neurons and the Kenyon cells. In particular, the model explains mechanistically how sparse activity in the Kenyon cells arises from the dense code in the projection neurons. The odor classification performance of the model proved to be robust against noise and time jitter in the observed input sequences. As in recent experimental results, we found that recognition of an odor happened very early during stimulus presentation in the model. Critically, by using the model, we found surprising but simple computational explanations for several experimental phenomena. PMID:26451888

  19. Lognormal firing rate distribution reveals prominent fluctuation–driven regime in spinal motor networks

    PubMed Central

    Petersen, Peter C; Berg, Rune W

    2016-01-01

    When spinal circuits generate rhythmic movements it is important that the neuronal activity remains within stable bounds to avoid saturation and to preserve responsiveness. Here, we simultaneously record from hundreds of neurons in lumbar spinal circuits of turtles and establish the neuronal fraction that operates within either a ‘mean-driven’ or a ‘fluctuation–driven’ regime. Fluctuation-driven neurons have a ‘supralinear’ input-output curve, which enhances sensitivity, whereas the mean-driven regime reduces sensitivity. We find a rich diversity of firing rates across the neuronal population as reflected in a lognormal distribution and demonstrate that half of the neurons spend at least 50 % of the time in the ‘fluctuation–driven’ regime regardless of behavior. Because of the disparity in input–output properties for these two regimes, this fraction may reflect a fine trade–off between stability and sensitivity in order to maintain flexibility across behaviors. DOI: http://dx.doi.org/10.7554/eLife.18805.001 PMID:27782883

  20. Knowledge-Based Systems Approach to Wilderness Fire Management.

    NASA Astrophysics Data System (ADS)

    Saveland, James M.

    The 1988 and 1989 forest fire seasons in the Intermountain West highlight the shortcomings of current fire policy. To fully implement an optimization policy that minimizes the costs and net value change of resources affected by fire, long-range fire severity information is essential, yet lacking. This information is necessary for total mobility of suppression forces, implementing contain and confine suppression strategies, effectively dealing with multiple fire situations, scheduling summer prescribed burning, and wilderness fire management. A knowledge-based system, Delphi, was developed to help provide long-range information. Delphi provides: (1) a narrative of advice on where a fire might spread, if allowed to burn, (2) a summary of recent weather and fire danger information, and (3) a Bayesian analysis of long-range fire danger potential. Uncertainty is inherent in long-range information. Decision theory and judgment research can be used to help understand the heuristics experts use to make decisions under uncertainty, heuristics responsible both for expert performance and bias. Judgment heuristics and resulting bias are examined from a fire management perspective. Signal detection theory and receiver operating curve (ROC) analysis can be used to develop a long-range forecast to improve decisions. ROC analysis mimics some of the heuristics and compensates for some of the bias. Most importantly, ROC analysis displays a continuum of bias from which an optimum operating point can be selected. ROC analysis is especially appropriate for long-range forecasting since (1) the occurrence of possible future events is stated in terms of probability, (2) skill prediction is displayed, (3) inherent trade-offs are displayed, and (4) fire danger is explicitly defined. Statements on the probability of the energy release component of the National Fire Danger Rating System exceeding a critical value later in the fire season can be made early July in the Intermountain West

  1. Comparing the effectiveness of heat rate improvements in different coal-fired power plants utilizing carbon dioxide capture

    NASA Astrophysics Data System (ADS)

    Walsh, Martin Jeremy

    New Congressional legislation may soon require coal-fired power generators to pay for their CO2 emissions and capture a minimum level of their CO2 output. Aminebased CO2 capture systems offer plants the most technically proven and commercially feasible option for CO2 capture at this time. However, these systems require a large amount of heat and power to operate. As a result, amine-based CO2 capture systems significantly reduce the net power of any units in which they are installed. The Energy Research Center has compiled a list of heat rate improvements that plant operators may implement before installing a CO2 capture system. The goal of these improvements is to upgrade the performance of existing units and partially offset the negative effects of adding a CO2 capture system. Analyses were performed in Aspen Plus to determine the effectiveness of these heat rate improvements in preserving the net power and net unit heat rate (NUHR) of four different power generator units. For the units firing high-moisture sub-bituminous coal, the heat rate improvements reduced NUHR by an average of 13.69% across a CO 2 capture level range of 50% to 90%. For the units firing bituminous coal across the same CO2 capture range, the heat rate improvements reduced NUHR by an average of 12.30%. Regardless of the units' coal or steam turbine cycle type, the heat rate improvements preserved 9.7% to 11.0% of each unit's net power across the same CO2 capture range. In general, the heat rate improvements were found to be most effective in improving the performance of units firing high-moisture sub-bituminous. The effect of the CO2 capture system on these units and the reasons for the improvements' greater effectiveness in them are described in this thesis.

  2. Triceps surae contractile properties and firing rates in the soleus of young and old men.

    PubMed

    Dalton, Brian H; Harwood, Brad; Davidson, Andrew W; Rice, Charles L

    2009-12-01

    Mean maximal motor unit firing rates (MUFRs) of the human soleus are lower (5-20 Hz) than other limb muscles (20-50 Hz) during brief sustained contractions. With healthy adult aging, maximal MUFRs are 20-40% lower and twitch contractile speed of lower limb muscles are 10-40% slower compared with young adults. However, it is unknown whether the inherently low maximal MUFRs for the soleus are further reduced with aging in association with age-related slowing in contractile properties. The purpose of the present study was to compare the changes in triceps surae contractile properties and MUFRs of the soleus throughout a variety of contraction intensities in six old ( approximately 75 yr old) and six young ( approximately 24 yr old) men. Neuromuscular measures were collected from the soleus and triceps surae during repeated sessions (2-6 sessions). Populations of single MUFR trains were recorded from the soleus with tungsten microelectrodes during separate sustained 6- to 10-s isometric contractions of varying intensities [25%, 50%, 75%, and 100% maximal voluntary isometric contraction (MVC)]. The old men had weaker triceps surae strength (MVC; 35% lower) and slower contractile properties (contraction duration; 20% longer) than the young men. However, there was no difference in average MUFRs of the soleus at 75% and 100% MVC ( approximately 14.5 Hz and approximately 16.5 Hz, respectively). At 25% and 50% MVC, average rates were 10% and 20% lower in the old men compared with young, respectively. Despite a significant slowing in triceps surae contraction duration, there was no age-related change in MUFRs recorded at high contractile intensities in the soleus. Thus the relationship between the whole muscle contractile properties and MUFRs found in other muscle groups may not exist between the triceps surae and soleus and may be muscle dependent.

  3. High firing rate of neonatal hippocampal interneurons is caused by attenuation of afterhyperpolarizing potassium currents by tonically active kainate receptors.

    PubMed

    Segerstråle, Mikael; Juuri, Juuso; Lanore, Frédéric; Piepponen, Petteri; Lauri, Sari E; Mulle, Christophe; Taira, Tomi

    2010-05-12

    In the neonatal hippocampus, the activity of interneurons shapes early network bursts that are important for the establishment of neuronal connectivity. However, mechanisms controlling the firing of immature interneurons remain elusive. We now show that the spontaneous firing rate of CA3 stratum lucidum interneurons markedly decreases during early postnatal development because of changes in the properties of GluK1 (formerly known as GluR5) subunit-containing kainate receptors (KARs). In the neonate, activation of KARs by ambient glutamate exerts a tonic inhibition of the medium-duration afterhyperpolarization (mAHP) by a G-protein-dependent mechanism, permitting a high interneuronal firing rate. During development, the amplitude of the apamine-sensitive K+ currents responsible for the mAHP increases dramatically because of decoupling between KAR activation and mAHP modulation, leading to decreased interneuronal firing. The developmental shift in the KAR function and its consequences on interneuronal activity are likely to have a fundamental role in the maturation of the synchronous neuronal oscillations typical for adult hippocampal circuitry.

  4. Fire Frequent as a Measure of Fire Prevention Accomplishments

    Treesearch

    A.W. Lindenmuth; J.J. Keetch

    1953-01-01

    At the end of every year fire organizations regularly tally up the number of fires that burned in their territory and then try to decide whether the record is good or bad. Thirteen northeastern states reported 8,948 fires in 1951 on days of known fire danger, for example. Now the question is: would it have been reasonable to expect a larger or smaller number than 8,...

  5. A Danger-Theory-Based Immune Network Optimization Algorithm

    PubMed Central

    Li, Tao; Xiao, Xin; Shi, Yuanquan

    2013-01-01

    Existing artificial immune optimization algorithms reflect a number of shortcomings, such as premature convergence and poor local search ability. This paper proposes a danger-theory-based immune network optimization algorithm, named dt-aiNet. The danger theory emphasizes that danger signals generated from changes of environments will guide different levels of immune responses, and the areas around danger signals are called danger zones. By defining the danger zone to calculate danger signals for each antibody, the algorithm adjusts antibodies' concentrations through its own danger signals and then triggers immune responses of self-regulation. So the population diversity can be maintained. Experimental results show that the algorithm has more advantages in the solution quality and diversity of the population. Compared with influential optimization algorithms, CLONALG, opt-aiNet, and dopt-aiNet, the algorithm has smaller error values and higher success rates and can find solutions to meet the accuracies within the specified function evaluation times. PMID:23483853

  6. Warning against the dangers of wildfires in the Czech Republic

    NASA Astrophysics Data System (ADS)

    Mozny, M.; Bares, D.; Virag, M.; Stalmacher, J.

    2009-04-01

    Many fire risk models have been developed for various temporal and spatial scales and application purposes. The integrated warning service in the Czech Republic is used for wildfire risk assessment model of FDI (Fire Danger Index). The FDI model is being developed in the Doksany observatory based on evaluation of weather conditions. FDI model describes danger of wildfire for vegetation covered countryside. There are five levels of danger: 1 - very low risk, 2 - low risk, 3 - moderate risk, 4 - high risk, 5 - very high risk. Simply say higher index value, reflects to higher risk of wildfire. As input data, the model uses measured values from the Czech Hydrometeorological Institute stations network as well as ALADIN's model predicted conditions. The modelling process computes upper soil profile moisture, surface moistening and the spreading speed of fire. Early warning system for wildfires prevention in the Czech Republic is used since 2006.

  7. Complete Firing-Rate Response of Neurons with Complex Intrinsic Dynamics

    PubMed Central

    Puelma Touzel, Maximilian; Wolf, Fred

    2015-01-01

    The response of a neuronal population over a space of inputs depends on the intrinsic properties of its constituent neurons. Two main modes of single neuron dynamics–integration and resonance–have been distinguished. While resonator cell types exist in a variety of brain areas, few models incorporate this feature and fewer have investigated its effects. To understand better how a resonator’s frequency preference emerges from its intrinsic dynamics and contributes to its local area’s population firing rate dynamics, we analyze the dynamic gain of an analytically solvable two-degree of freedom neuron model. In the Fokker-Planck approach, the dynamic gain is intractable. The alternative Gauss-Rice approach lifts the resetting of the voltage after a spike. This allows us to derive a complete expression for the dynamic gain of a resonator neuron model in terms of a cascade of filters on the input. We find six distinct response types and use them to fully characterize the routes to resonance across all values of the relevant timescales. We find that resonance arises primarily due to slow adaptation with an intrinsic frequency acting to sharpen and adjust the location of the resonant peak. We determine the parameter regions for the existence of an intrinsic frequency and for subthreshold and spiking resonance, finding all possible intersections of the three. The expressions and analysis presented here provide an account of how intrinsic neuron dynamics shape dynamic population response properties and can facilitate the construction of an exact theory of correlations and stability of population activity in networks containing populations of resonator neurons. PMID:26720924

  8. Maturation of Spontaneous Firing Properties after Hearing Onset in Rat Auditory Nerve Fibers: Spontaneous Rates, Refractoriness, and Interfiber Correlations

    PubMed Central

    Wu, Jingjing Sherry; Young, Eric D.

    2016-01-01

    Auditory nerve fibers (ANFs) exhibit a range of spontaneous firing rates (SRs) that are inversely correlated with threshold for sounds. To probe the underlying mechanisms and time course of SR differentiation during cochlear maturation, loose-patch extracellular recordings were made from ANF dendrites using acutely excised rat cochlear preparations of different ages after hearing onset. Diversification of SRs occurred mostly between the second and the third postnatal week. Statistical properties of ANF spike trains showed developmental changes that approach adult-like features in older preparations. Comparison with intracellularly recorded EPSCs revealed that most properties of ANF spike trains derive from the characteristics of presynaptic transmitter release. Pharmacological tests and waveform analysis showed that endogenous firing produces some fraction of ANF spikes, accounting for their unusual properties; the endogenous firing diminishes gradually during maturation. Paired recordings showed that ANFs contacting the same inner hair cell could have different SRs, with no correlation in their spike timing. SIGNIFICANCE STATEMENT The inner hair cell (IHC)/auditory nerve fiber (ANF) synapse is the first synapse of the auditory pathway. Remarkably, each IHC is the sole partner of 10–30 ANFs with a range of spontaneous firing rates (SRs). Low and high SR ANFs respond to sound differently, and both are important for encoding sound information across varying acoustical environments. Here we demonstrate SR diversification after hearing onset by afferent recordings in acutely excised rat cochlear preparations. We describe developmental changes in spike train statistics and endogenous firing in immature ANFs. Dual afferent recordings provide the first direct evidence that fibers with different SRs contact the same IHCs and do not show correlated spike timing at rest. These results lay the groundwork for understanding the differential sensitivity of ANFs to acoustic

  9. Heart rates in fire fighters using light and heavy breathing equipment: similar near-maximal exertion in response to multiple work load conditions.

    PubMed

    Manning, J E; Griggs, T R

    1983-03-01

    Intense exertion is an occupational hazard inherent to fire fighting. This study was designed to look at the exertion levels that fire fighters attain during a fire fighting exercise when using (1) no self-contained breathing apparatus (SCBA), (2) light SCBA, and (3) heavy SCBA. Exertion levels were measured as a function of the heart rate increase relative to the maximum predicted heart rate determined by a standard treadmill exercise test. Five fire fighters wore electrocardiographic monitors during a routine fire fighting exercise. Heart rates increased rapidly to 70% to 80% of maximum within the first minute and then plateaued at 90% to 100% until the attack on the fire was completed. There was no significant difference between exertion levels when using no SCBA, light SCBA, and heavy SCBA (split-plot analysis of variance, p greater than .25). These results suggest that fire fighters attain an intense level of physical activity quickly and maintain that level as long as they are actively engaged in fighting fire. These results also suggest that regardless of the weight of the SCBA, if employed, fire fighters exert themselves from 85% to 100% of their maximum and adjust their work output to maintain that near-maximal level.

  10. Experimental study of the influence of varying ceiling height on the heat release rate of a pool fire

    NASA Astrophysics Data System (ADS)

    Liu, Jiahao; Wang, Jian; Richard, Yuen

    2017-05-01

    To investigate the influence of ceiling height on the combustion process of a pool fire whose flame impinges the ceiling, a sequence of pool fires with varying ceiling heights was performed using a scaled-down cone calorimeter. N-heptane and jet-A were employed as fuels to conducted the tests. Experimental findings reveal that with the decreasing ceiling height, the maximum and average heat release rates will initially increase due to the enhanced heat feedback, and then decrease as a result of the restriction of air entrainment caused by the extremely small ceiling height. In addition, the dimensionless ceiling height is found to have a linear relationship with the logarithm value of the dimensionless averaged heat release rate for the two given fuels with the similar slope of -2/3.

  11. Fuel type characterization and potential fire behavior estimation in Sardinia and Corsica islands

    NASA Astrophysics Data System (ADS)

    Bacciu, V.; Pellizzaro, G.; Santoni, P.; Arca, B.; Ventura, A.; Salis, M.; Barboni, T.; Leroy, V.; Cancellieri, D.; Leoni, E.; Ferrat, L.; Perez, Y.; Duce, P.; Spano, D.

    2012-04-01

    BEHAVE fire behavior prediction system (Andrews, 1989) and experimental fuel data. Fire behavior was simulated by setting different weather scenarios representing the most frequent summer meteorological conditions. The simulation outputs (fireline intensity, rate of spread, flame length) were then analyzed for clustering the different fuel types in relation to their potential fire behavior. The results of this analysis can be used to produce fire behavior fuel maps that are important tools in evaluating fire hazard and risk for land management planning, locating and rating fuel treatments, and aiding in environmental assessments and fire danger programs modeling. This work is supported by FUME Project FP7-ENV-2009-1, Grant Agreement Number 243888 and Proterina-C Project, EU Italia-Francia Marittimo 2007-2013 Programme.

  12. Substance P Differentially Modulates Firing Rate of Solitary Complex (SC) Neurons from Control and Chronic Hypoxia-Adapted Adult Rats

    PubMed Central

    Nichols, Nicole L.; Powell, Frank L.; Dean, Jay B.; Putnam, Robert W.

    2014-01-01

    NK1 receptors, which bind substance P, are present in the majority of brainstem regions that contain CO2/H+-sensitive neurons that play a role in central chemosensitivity. However, the effect of substance P on the chemosensitive response of neurons from these regions has not been studied. Hypoxia increases substance P release from peripheral afferents that terminate in the caudal nucleus tractus solitarius (NTS). Here we studied the effect of substance P on the chemosensitive responses of solitary complex (SC: NTS and dorsal motor nucleus) neurons from control and chronic hypoxia-adapted (CHx) adult rats. We simultaneously measured intracellular pH and electrical responses to hypercapnic acidosis in SC neurons from control and CHx adult rats using the blind whole cell patch clamp technique and fluorescence imaging microscopy. Substance P significantly increased the basal firing rate in SC neurons from control and CHx rats, although the increase was smaller in CHx rats. However, substance P did not affect the chemosensitive response of SC neurons from either group of rats. In conclusion, we found that substance P plays a role in modulating the basal firing rate of SC neurons but the magnitude of the effect is smaller for SC neurons from CHx adult rats, implying that NK1 receptors may be down regulated in CHx adult rats. Substance P does not appear to play a role in modulating the firing rate response to hypercapnic acidosis of SC neurons from either control or CHx adult rats. PMID:24516602

  13. MUSIC-Expected maximization gaussian mixture methodology for clustering and detection of task-related neuronal firing rates.

    PubMed

    Ortiz-Rosario, Alexis; Adeli, Hojjat; Buford, John A

    2017-01-15

    Researchers often rely on simple methods to identify involvement of neurons in a particular motor task. The historical approach has been to inspect large groups of neurons and subjectively separate neurons into groups based on the expertise of the investigator. In cases where neuron populations are small it is reasonable to inspect these neuronal recordings and their firing rates carefully to avoid data omissions. In this paper, a new methodology is presented for automatic objective classification of neurons recorded in association with behavioral tasks into groups. By identifying characteristics of neurons in a particular group, the investigator can then identify functional classes of neurons based on their relationship to the task. The methodology is based on integration of a multiple signal classification (MUSIC) algorithm to extract relevant features from the firing rate and an expectation-maximization Gaussian mixture algorithm (EM-GMM) to cluster the extracted features. The methodology is capable of identifying and clustering similar firing rate profiles automatically based on specific signal features. An empirical wavelet transform (EWT) was used to validate the features found in the MUSIC pseudospectrum and the resulting signal features captured by the methodology. Additionally, this methodology was used to inspect behavioral elements of neurons to physiologically validate the model. This methodology was tested using a set of data collected from awake behaving non-human primates.

  14. Introducing GFWED: The Global Fire Weather Database

    NASA Technical Reports Server (NTRS)

    Field, R. D.; Spessa, A. C.; Aziz, N. A.; Camia, A.; Cantin, A.; Carr, R.; de Groot, W. J.; Dowdy, A. J.; Flannigan, M. D.; Manomaiphiboon, K.; hide

    2015-01-01

    The Canadian Forest Fire Weather Index (FWI) System is the mostly widely used fire danger rating system in the world. We have developed a global database of daily FWI System calculations, beginning in 1980, called the Global Fire WEather Database (GFWED) gridded to a spatial resolution of 0.5 latitude by 2-3 longitude. Input weather data were obtained from the NASA Modern Era Retrospective-Analysis for Research and Applications (MERRA), and two different estimates of daily precipitation from rain gauges over land. FWI System Drought Code calculations from the gridded data sets were compared to calculations from individual weather station data for a representative set of 48 stations in North, Central and South America, Europe, Russia,Southeast Asia and Australia. Agreement between gridded calculations and the station-based calculations tended to be most different at low latitudes for strictly MERRA based calculations. Strong biases could be seen in either direction: MERRA DC over the Mato Grosso in Brazil reached unrealistically high values exceeding DCD1500 during the dry season but was too low over Southeast Asia during the dry season. These biases are consistent with those previously identified in MERRAs precipitation, and they reinforce the need to consider alternative sources of precipitation data. GFWED can be used for analyzing historical relationships between fire weather and fire activity at continental and global scales, in identifying large-scale atmosphereocean controls on fire weather, and calibration of FWI-based fire prediction models.

  15. Introducing the Global Fire Weather Database (GFWED)

    NASA Astrophysics Data System (ADS)

    Field, Robert

    2016-04-01

    The Canadian Fire Weather Index (FWI) System is the mostly widely used fire danger rating system in the world. We have developed a global database of daily FWI System calculations beginning in 1980 called the Global Fire WEather Database (GFWED) gridded to a spatial resolution of 0.5° latitude by 2/3° longitude. Input weather data were obtained from the NASA Modern Era Retrospective-Analysis for Research (MERRA), and two different estimates of daily precipitation from rain gauges over land. FWI System Drought Code calculations from the gridded datasets were compared to calculations from individual weather station data for a representative set of 48 stations in North, Central and South America, Europe, Russia, Southeast Asia and Australia. Agreement between gridded calculations and the station-based calculations tended to be most different at low latitudes for strictly MERRA-based calculations. Strong biases could be seen in either direction: MERRA DC over the Mato Grosso in Brazil reached unrealistically high values exceeding DC=1500 during the dry season but was too low over Southeast Asia during the dry season. These biases are consistent with those previously-identified in MERRA's precipitation and reinforce the need to consider alternative sources of precipitation data. GFWED can be used for analyzing historical relationships between fire weather and fire activity at continental and global scales, in identifying large-scale atmosphere-ocean controls on fire weather, and calibration of FWI-based fire prediction models. These applications will be discussed.

  16. Rates of post-fire vegetation recovery and fuel accumulation as a function of burn severity and time-since-burn in four western U.S. ecosystems

    USDA-ARS?s Scientific Manuscript database

    Vegetation recovery and fuel accumulation rates following wildfire are useful measures of ecosystem resilience, yet few studies have quantified these variables over 10 years post-fire. Conventional wisdom is that recovery time to pre-fire condition will be slower as a function of burn severity, as i...

  17. Identifying key climate and environmental factors affecting rates of post-fire big sagebrush (Artemisia tridentata) recovery in the northern Columbia Basin, USA

    USGS Publications Warehouse

    Shinneman, Douglas; McIlroy, Susan

    2016-01-01

    Sagebrush steppe of North America is considered highly imperilled, in part owing to increased fire frequency. Sagebrush ecosystems support numerous species, and it is important to understand those factors that affect rates of post-fire sagebrush recovery. We explored recovery of Wyoming big sagebrush (Artemisia tridentata ssp.wyomingensis) and basin big sagebrush (A. tridentata ssp. tridentata) communities following fire in the northern Columbia Basin (Washington, USA). We sampled plots across 16 fires that burned in big sagebrush communities from 5 to 28 years ago, and also sampled nearby unburned locations. Mixed-effects models demonstrated that density of large–mature big sagebrush plants and percentage cover of big sagebrush were higher with time since fire and in plots with more precipitation during the winter immediately following fire, but were lower when precipitation the next winter was higher than average, especially on soils with higher available water supply, and with greater post-fire mortality of mature big sagebrush plants. Bunchgrass cover 5 to 28 years after fire was predicted to be lower with higher cover of both shrubs and non-native herbaceous species, and only slightly higher with time. Post-fire recovery of big sagebrush in the northern Columbia Basin is a slow process that may require several decades on average, but faster recovery rates may occur under specific site and climate conditions.

  18. Domains of Risk in the Developmental Continuity of Fire Setting

    ERIC Educational Resources Information Center

    McCarty, Carolyn A.; McMahon, Robert J.

    2005-01-01

    Juvenile fire setting is a serious, dangerous, and costly behavior. The majority of research examining youth fire setting has been cross-sectional. We sought to examine early risk attributes that could differentiate fire setters from non-fire setters, in addition to examining their association with the developmental continuity of fire-setting…

  19. Domains of Risk in the Developmental Continuity of Fire Setting

    ERIC Educational Resources Information Center

    McCarty, Carolyn A.; McMahon, Robert J.

    2005-01-01

    Juvenile fire setting is a serious, dangerous, and costly behavior. The majority of research examining youth fire setting has been cross-sectional. We sought to examine early risk attributes that could differentiate fire setters from non-fire setters, in addition to examining their association with the developmental continuity of fire-setting…

  20. Investigation of Biomass Combustion Rate of Fire Radiative Energy Using Multiple-Satellite-observed Active Fires and Landsat TM Burn Severities across the Continental United States

    NASA Astrophysics Data System (ADS)

    Li, F.; Zhang, X.; Kondragunta, S.

    2015-12-01

    Biomass burning is a major source of atmospheric aerosol and greenhouse gases that substantially influence climate and regional air quality. However, the accuracy of biomass burning emissions estimated using traditional method is limited by large uncertainties in burned area and fuel loading. Alternatively, fire radiative energy (FRE) has recently been demonstrated to be linearly related to biomass combustion, which potentially improves the estimation of biomass burning emissions. The FRE-based combustion rate is 0.368-0.453 kg/MJ according to field controlled experiments while it varies from 1.37-4.5 kg/MJ derived from satellite-based bottom-up and top-down aerosol optical thickness estimates. Here we investigate the FRE combustion rate in over 1000 burn scars from 2011 to 2012 across the Continental United States (CONUS). Specifically, FRE was calculated by combining the high spatial observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the high temporal observations from the Geostationary Operational Environmental Satellite (GOES). Biomass consumption in burn scars was modeled using Landsat TM 30m burn severities, 30m fuel loading from Fuel Characteristic Classification System, and combustion completeness compiled from recent literatures. The combustion rate was then investigated by correlating FRE to biomass consumption across CONUS and Bailey's ecoregions. Our results show that the combustion rate can be extracted from the linear relationship between biomass consumption and FRE. The combustion rate is 0.415±10% kg/MJ across CONUS, which is similar to the rate derived from field experiments. However, it varies from 0.18-1.9 kg/MJ among ecoregions. This implies that a single combustion rate could produce large uncertainty in the estimation of biomass consumption at large scales. We suggest that ecoregion specified combustion rates should help to improve the accuracy of quantifying biomass burning emissions regionally and globally.

  1. Altered firing rates and patterns in interneurons in experimental cortical dysplasia.

    PubMed

    Zhou, Fu-Wen; Roper, Steven N

    2011-07-01

    Cortical dysplasia (CD) is associated with severe epilepsy in humans, and the in utero irradiation of fetal rats provides a model of this disorder. These animals show a selective loss of inhibitory interneurons, and the surviving interneurons have a reduced excitatory synaptic drive. The current study was undertaken to see how alterations in synaptic input would affect spontaneous firing of interneurons in dysplastic cortex. We recorded spontaneous action potentials and excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs, respectively) from somatostatin (SST)-, parvalbumin (PV)-, and calretinin (CR)-immunoreactive (ir) interneurons. We found that SST- and PV-ir interneurons fired less frequently and with less regularity than controls. This corresponded to a relative imbalance in the ratio of EPSCs to IPSCs that favored inhibition. In contrast, CR-ir interneurons from CD showed no differences from controls in spontaneous firing or ratio of EPSCs to IPSCs. Additional studies demonstrated that synaptic input had a powerful effect on spontaneous firing in all interneurons. These findings demonstrate that a relative reduction in excitatory drive results in less active SST- and PV-ir interneurons in irradiated rats. This would further impair cortical inhibition in these animals and may be an important mechanism of epileptogenesis.

  2. Application of the Nelson model to four timelag fuel classes using Oklahoma field observations: Model evaluation and comparison with national Fire Danger Rating System algorithms

    Treesearch

    J. D. Carlson; Larry S. Bradshaw; Ralph M. Nelson; Randall R Bensch; Rafal Jabrzemski

    2007-01-01

    The application of a next-generation dead-fuel moisture model, the 'Nelson model', to four timelag fuel classes using an extensive 21-month dataset of dead-fuel moisture observations is described. Developed by Ralph Nelson in the 1990s, the Nelson model is a dead-fuel moisture model designed to take advantage of frequent automated weather observations....

  3. Are High-Severity Fires Burning at Much Higher Rates Recently than Historically in Dry-Forest Landscapes of the Western USA?

    PubMed Central

    Baker, William L.

    2015-01-01

    Dry forests at low elevations in temperate-zone mountains are commonly hypothesized to be at risk of exceptional rates of severe fire from climatic change and land-use effects. Their setting is fire-prone, they have been altered by land-uses, and fire severity may be increasing. However, where fires were excluded, increased fire could also be hypothesized as restorative of historical fire. These competing hypotheses are not well tested, as reference data prior to widespread land-use expansion were insufficient. Moreover, fire-climate projections were lacking for these forests. Here, I used new reference data and records of high-severity fire from 1984–2012 across all dry forests (25.5 million ha) of the western USA to test these hypotheses. I also approximated projected effects of climatic change on high-severity fire in dry forests by applying existing projections. This analysis showed the rate of recent high-severity fire in dry forests is within the range of historical rates, or is too low, overall across dry forests and individually in 42 of 43 analysis regions. Significant upward trends were lacking overall from 1984–2012 for area burned and fraction burned at high severity. Upward trends in area burned at high severity were found in only 4 of 43 analysis regions. Projections for A.D. 2046–2065 showed high-severity fire would generally be still operating at, or have been restored to historical rates, although high projections suggest high-severity fire rotations that are too short could ensue in 6 of 43 regions. Programs to generally reduce fire severity in dry forests are not supported and have significant adverse ecological impacts, including reducing habitat for native species dependent on early-successional burned patches and decreasing landscape heterogeneity that confers resilience to climatic change. Some adverse ecological effects of high-severity fires are concerns. Managers and communities can improve our ability to live with high-severity fire

  4. Are High-Severity Fires Burning at Much Higher Rates Recently than Historically in Dry-Forest Landscapes of the Western USA?

    PubMed

    Baker, William L

    2015-01-01

    Dry forests at low elevations in temperate-zone mountains are commonly hypothesized to be at risk of exceptional rates of severe fire from climatic change and land-use effects. Their setting is fire-prone, they have been altered by land-uses, and fire severity may be increasing. However, where fires were excluded, increased fire could also be hypothesized as restorative of historical fire. These competing hypotheses are not well tested, as reference data prior to widespread land-use expansion were insufficient. Moreover, fire-climate projections were lacking for these forests. Here, I used new reference data and records of high-severity fire from 1984-2012 across all dry forests (25.5 million ha) of the western USA to test these hypotheses. I also approximated projected effects of climatic change on high-severity fire in dry forests by applying existing projections. This analysis showed the rate of recent high-severity fire in dry forests is within the range of historical rates, or is too low, overall across dry forests and individually in 42 of 43 analysis regions. Significant upward trends were lacking overall from 1984-2012 for area burned and fraction burned at high severity. Upward trends in area burned at high severity were found in only 4 of 43 analysis regions. Projections for A.D. 2046-2065 showed high-severity fire would generally be still operating at, or have been restored to historical rates, although high projections suggest high-severity fire rotations that are too short could ensue in 6 of 43 regions. Programs to generally reduce fire severity in dry forests are not supported and have significant adverse ecological impacts, including reducing habitat for native species dependent on early-successional burned patches and decreasing landscape heterogeneity that confers resilience to climatic change. Some adverse ecological effects of high-severity fires are concerns. Managers and communities can improve our ability to live with high-severity fire in

  5. Amniotic Fluid or Its Fatty Acids Produce Actions Similar to Diazepam on Lateral Septal Neurons Firing Rate

    PubMed Central

    Gutiérrez-García, Ana G.; Vásquez-Hernández, Diana Idania

    2013-01-01

    Human amniotic fluid (AF) contains eight fatty acids (FATs), and both produce anxiolytic-like effects in adult rats and appetitive responses in human newborns. The medial amygdala and lateral septal nucleus function are related to social behavior, but the action of AF or its FATs in this circuit is known. We obtained 267 single-unit extracellular recordings in Wistar rats treated with vehicle (1 mL, s.c.; n = 12), human AF (1 mL, s.c.; n = 12), a FAT mixture (1 mL, s.c.; n = 13), diazepam (1 mg/kg, i.p.; n = 11), and fluoxetine (1 mg/kg, p.o.; n = 12). Compared with the vehicle group, the spontaneous septal firing rate in the AF, FAT mixture, and diazepam groups was the lowest and in the fluoxetine group the highest. Cumulative peristimulus histograms indicated that the significant change in septal firing occurred only in the AF and FAT mixture groups and exclusively in those neurons that increased their firing rate during amygdala stimulation. We conclude that human AF and its FATs produce actions comparable to anxiolytic drugs and are able to modify the responsivity of a circuit involved in social behavior, suggesting facilitation of social recognition processes by maternal-fetal fluids. PMID:23864826

  6. A Danger to Ourselves

    ERIC Educational Resources Information Center

    Barbieri, Richard

    2013-01-01

    In this article Richard Barbieri asserts that the biggest danger to our own safety and well-being, and that of our children, comes not from adult predators, environmental hazards, or the class bully, but from traits common to us all. The enemy is us, and not least because we too often jump to such strategies as clobbering. Writers from such varied…

  7. A Danger to Ourselves

    ERIC Educational Resources Information Center

    Barbieri, Richard

    2013-01-01

    In this article Richard Barbieri asserts that the biggest danger to our own safety and well-being, and that of our children, comes not from adult predators, environmental hazards, or the class bully, but from traits common to us all. The enemy is us, and not least because we too often jump to such strategies as clobbering. Writers from such varied…

  8. Radon: The Silent Danger.

    ERIC Educational Resources Information Center

    Stoffel, Jennifer

    1989-01-01

    This article discusses the public health dangers associated with radon exposure in homes and schools. In addition, testing and corrective efforts by federal and state agencies are discussed. A map indicating areas in the U.S. with potentially high radon levels is included. (IAH)

  9. Radon: The Silent Danger.

    ERIC Educational Resources Information Center

    Stoffel, Jennifer

    1989-01-01

    This article discusses the public health dangers associated with radon exposure in homes and schools. In addition, testing and corrective efforts by federal and state agencies are discussed. A map indicating areas in the U.S. with potentially high radon levels is included. (IAH)

  10. Trauma is Danger

    DTIC Science & Technology

    2011-01-01

    significant danger signal to the immune system. Cell Stress Chaperones 2003, 8:272-286. 35. Martinon F, Petrilli V, Mayor A, Tardivel A, Tschopp J: Gout ...understanding of gout . Arthritis Res Ther 2008, 10:221. 37. Hawkins PN, Lachmann HJ, Aganna E, McDermott MF: Spectrum of clinical features in Muckle-Wells

  11. Schools as Dangerous Places

    ERIC Educational Resources Information Center

    Potts, Anthony

    2006-01-01

    When students set off for school each day how many of them or their caregivers consider for a moment that they will spend the day at a potentially dangerous place? On the contrary, students and caregivers probably view schools as safe havens, and official research suggests that this is the case for the majority of teachers and pupils. However,…

  12. Body size, but not cooling rate, affects supercooling points in the red imported fire ant, Solenopsis invicta.

    PubMed

    Hahn, Daniel A; Martin, Adam R; Porter, Sanford D

    2008-10-01

    The level of an animal's stress resistance is set by multiple intrinsic physiological and extrinsic environmental parameters. Body size is a critical intrinsic parameter that affects numerous fitness-related organismal traits including fecundity, survival, mating success, and stress resistance. The rate of cooling is a critical extrinsic environmental factor that can affect thermal stress resistance. Workers of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), display considerable variation in adult body size. Therefore, developing ecologically realistic models of thermotolerance in this species requires a consideration of body size. We tested the hypothesis that body size and cooling rate would interact to set the supercooling point in fire ant workers by exposing workers of a range of body sizes to three different cooling regimens: a very fast ramp of -10 degrees C/min, an intermediate ramp of -1 degrees C/min, and an ecologically relevant slow ramp of -0.1 degrees C/min. Specifically, we asked whether large workers were more susceptible to differences in cooling rate than smaller workers. We found that body size had a considerable effect on supercooling point with the largest workers freezing at a temperature approximately 3 degrees C higher than the smallest workers. Cooling rate had a very small effect on supercooling point, and there was no interaction between the two factors. Therefore, the allometry of supercooling points across the range of worker body sizes does not change with cooling rate.

  13. Do monkey F5 mirror neurons show changes in firing rate during repeated observation of natural actions?

    PubMed

    Kilner, J M; Kraskov, A; Lemon, R N

    2014-03-01

    Mirror neurons were first discovered in area F5 of macaque monkeys. In humans, noninvasive studies have demonstrated an increased blood oxygen level-dependent (BOLD) signal in homologous motor areas during action observation. One approach to demonstrating that this indicates the existence of mirror neurons in humans has been to employ functional (f)MRI adaptation to test whether the same population of neurons is active during both observation and execution conditions. Although a number of human studies have reported fMRI adaptation in these areas, a recent study has shown that macaque mirror neurons do not attenuate their firing rate with two repetitions. Here we investigated whether mirror neurons modulate their firing rate when monkeys observed the same repeated natural action multiple times. We recorded from 67 mirror neurons in area F5 of two macaque monkeys while they observed an experimenter perform a reach-to-grasp action on a small food reward using a precision grip. Although no changes were detectable for the first two repetitions, we show that both the firing rate and the latency at which mirror neurons discharged during observation were subtly modulated by the repetition of the observed action over 7-10 trials. Significant adaption was mostly found in the period immediately before the grasp was performed. We also found that the local field potential activity in F5 (beta-frequency range, 16-23 Hz), which is attenuated during action observation, also showed systematic changes with repeated observation. These LFP changes occurred well in advance of the mirror neuron adaptation. We conclude that macaque mirror neurons can show intra-modal adaptation, but whether this is related to fMRI adaptation of the BOLD signal requires further investigation.

  14. Do monkey F5 mirror neurons show changes in firing rate during repeated observation of natural actions?

    PubMed Central

    Kraskov, A.; Lemon, R. N.

    2013-01-01

    Mirror neurons were first discovered in area F5 of macaque monkeys. In humans, noninvasive studies have demonstrated an increased blood oxygen level-dependent (BOLD) signal in homologous motor areas during action observation. One approach to demonstrating that this indicates the existence of mirror neurons in humans has been to employ functional (f)MRI adaptation to test whether the same population of neurons is active during both observation and execution conditions. Although a number of human studies have reported fMRI adaptation in these areas, a recent study has shown that macaque mirror neurons do not attenuate their firing rate with two repetitions. Here we investigated whether mirror neurons modulate their firing rate when monkeys observed the same repeated natural action multiple times. We recorded from 67 mirror neurons in area F5 of two macaque monkeys while they observed an experimenter perform a reach-to-grasp action on a small food reward using a precision grip. Although no changes were detectable for the first two repetitions, we show that both the firing rate and the latency at which mirror neurons discharged during observation were subtly modulated by the repetition of the observed action over 7–10 trials. Significant adaption was mostly found in the period immediately before the grasp was performed. We also found that the local field potential activity in F5 (beta-frequency range, 16–23 Hz), which is attenuated during action observation, also showed systematic changes with repeated observation. These LFP changes occurred well in advance of the mirror neuron adaptation. We conclude that macaque mirror neurons can show intra-modal adaptation, but whether this is related to fMRI adaptation of the BOLD signal requires further investigation. PMID:24371289

  15. Spatial distribution of forest fires and controlling factors in Andhra Pradesh, India using SPOT satellite datasets.

    PubMed

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

    2006-12-01

    Fires are one of the major causes of forest disturbance and destruction in several dry deciduous forests of southern India. In this study, we use remote sensing data sets in conjunction with topographic, vegetation, climate and socioeconomic factors for determining the potential causes of forest fires in Andhra Pradesh, India. Spatial patterns in fire characteristics were analyzed using SPOT satellite remote sensing datasets. We then used nineteen different metrics in concurrence with fire count datasets in a robust statistical framework to arrive at a predictive model that best explained the variation in fire counts across diverse geographical and climatic gradients. Results suggested that, of all the states in India, fires in Andhra Pradesh constituted nearly 13.53% of total fires. District wise estimates of fire counts for Andhra Pradesh suggested that, Adilabad, Cuddapah, Kurnool, Prakasham and Mehbubnagar had relatively highest number of fires compared to others. Results from statistical analysis suggested that of the nineteen parameters, population density, demand of metabolic energy (DME), compound topographic index, slope, aspect, average temperature of the warmest quarter (ATWQ) along with literacy rate explained 61.1% of total variation in fire datasets. Among these, DME and literacy rate were found to be negative predictors of forest fires. In overall, this study represents the first statewide effort that evaluated the causative factors of fire at district level using biophysical and socioeconomic datasets. Results from this study identify important biophysical and socioeconomic factors for assessing 'forest fire danger' in the study area. Our results also identify potential 'hotspots' of fire risk, where fire protection measures can be taken in advance. Further this study also demonstrate the usefulness of best-subset regression approach integrated with GIS, as an effective method to assess 'where and when' forest fires will most likely occur.

  16. Avoiding dangerous climate change

    SciTech Connect

    Hans Joachim Schellnhuber; Wolfgang Cramer; Nebojsa Nakicenovic; Tom Wigley; Gary Yohe

    2006-02-15

    In 2005 the UK Government hosted the Avoiding Dangerous Climate Change conference to take an in-depth look at the scientific issues associated with climate change. This volume presents the most recent findings from the leading international scientists that attended the conference. The topics addressed include critical thresholds and key vulnerabilities of the climate system, impacts on human and natural systems, socioeconomic costs and benefits of emissions pathways, and technological options for meeting different stabilisation levels of greenhouse gases in the atmosphere. Contents are: Foreword from Prime Minister Tony Blair; Introduction from Rajendra Pachauri, Chairman of the IPCC; followed by 41 papers arranged in seven sections entitled: Key Vulnerabilities of the Climate System and Critical Thresholds; General Perspectives on Dangerous Impacts; Key Vulnerabilities for Ecosystems and Biodiversity; Socio-Economic Effects; Regional Perspectives; Emission Pathways; and Technological Options. Four papers have been abstracted separately for the Coal Abstracts database.

  17. [Dangerous scorpions from Niger].

    PubMed

    Goyffon, M; Guette, C

    2005-11-01

    Two dangerous scorpion species are responsible for the severe human envenomations in Niger, Leiurus quinquestriatus (H. et E.), the most abundant, and Androctonus aeneas C.L. Koch, less frequent and described in a Sahel country for the first time. Up to now, A. aeneas was known in North Africa only. Its venom is highly toxic for humans, similar to those of the most dangerous species living in Africa, such as L. quinquestriatus and other species belonging to the genus Androctonus, A. australis (L.) and A. mauretanicus (Poc.), for the envenoming treatment of which specific antivenoms are prepared. Taking into account the absence of a specific antivenom for A. aeneas, the paraspecific neutralising effect of these antivenoms should be tested.

  18. Classroom Dangers of Toxic Minerals.

    ERIC Educational Resources Information Center

    Puffer, John H.

    1979-01-01

    Describes potentially dangerous classroom situations involving toxic minerals. The intent of the article is to make students aware of the dangers so that they may act responsibly in health-related decisions as professional geologists. (Author/SA)

  19. Motor unit firing rates and synchronisation affect the fractal dimension of simulated surface electromyogram during isometric/isotonic contraction of vastus lateralis muscle.

    PubMed

    Mesin, Luca; Dardanello, Davide; Rainoldi, Alberto; Boccia, Gennaro

    2016-12-01

    During fatiguing contractions, many adjustments in motor units behaviour occur: decrease in muscle fibre conduction velocity; increase in motor units synchronisation; modulation of motor units firing rate; increase in variability of motor units inter-spike interval. We simulated the influence of all these adjustments on synthetic EMG signals in isometric/isotonic conditions. The fractal dimension of the EMG signal was found mainly influenced by motor units firing behaviour, being affected by both firing rate and synchronisation level, and least affected by muscle fibre conduction velocity. None of the calculated EMG indices was able to discriminate between firing rate and motor units synchronisation. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

  20. Developing a Global, Short-Term Fire Weather Forecasting Tool Using NWP Input Meteorology and Satellite Fire Data

    NASA Astrophysics Data System (ADS)

    Peterson, D. A.; Hyer, E. J.; Wang, J.

    2011-12-01

    In order to meet the emerging need for better estimates of biomass burning emissions in air quality and climate models, a statistical model is developed to characterize the effect of a given set of meteorological conditions on the following day's fire activity, including ignition and spread potential. Preliminary tests are conducted within several spatial domains of the North American boreal forest by investigating a wide range of meteorological information, including operational fire weather forecasting indices, such as the Canadian Forest Fire Danger Rating System (CFFDRS). However, rather than using local noon surface station data, the six components of the CFFDRS are modified to use inputs from the North America Regional Reanalysis (NARR) and the Navy's Operational Global Atmospheric Prediction System Model (NOGAPS). The Initial Spread Index (ISI) and the Fire Weather Index (FWI) are shown to be the most relevant components of the CFFDRS for short-term changes in fire activity. However, both components are found to be highly sensitive to variations in relative humidity and wind speed input data. Several variables related to fire ignition from dry lighting, such as instability and the synoptic pattern, are also incorporated. Cases of fire ignition, growth, decay, and extinction are stratified using satellite fire observations from the Geostationary Operational Environmental Satellites (GOES) and the MODerate Resolution Imaging Spectroradiometer (MODIS) and compared to the available suite of meteorological information. These comparisons reveal that combinations of meteorological variables, such as the FWI, ISI, and additional indices developed for this study, produce the greatest separability between major fire growth and decay cases, which are defined by the observed change in fire counts and fire radiative power. This information is used to derive statistical relationships affecting the short-term changes in fire activity and subsequently applied to other

  1. Simple Learned Weighted Sums of Inferior Temporal Neuronal Firing Rates Accurately Predict Human Core Object Recognition Performance.

    PubMed

    Majaj, Najib J; Hong, Ha; Solomon, Ethan A; DiCarlo, James J

    2015-09-30

    To go beyond qualitative models of the biological substrate of object recognition, we ask: can a single ventral stream neuronal linking hypothesis quantitatively account for core object recognition performance over a broad range of tasks? We measured human performance in 64 object recognition tests using thousands of challenging images that explore shape similarity and identity preserving object variation. We then used multielectrode arrays to measure neuronal population responses to those same images in visual areas V4 and inferior temporal (IT) cortex of monkeys and simulated V1 population responses. We tested leading candidate linking hypotheses and control hypotheses, each postulating how ventral stream neuronal responses underlie object recognition behavior. Specifically, for each hypothesis, we computed the predicted performance on the 64 tests and compared it with the measured pattern of human performance. All tested hypotheses based on low- and mid-level visually evoked activity (pixels, V1, and V4) were very poor predictors of the human behavioral pattern. However, simple learned weighted sums of distributed average IT firing rates exactly predicted the behavioral pattern. More elaborate linking hypotheses relying on IT trial-by-trial correlational structure, finer IT temporal codes, or ones that strictly respect the known spatial substructures of IT ("face patches") did not improve predictive power. Although these results do not reject those more elaborate hypotheses, they suggest a simple, sufficient quantitative model: each object recognition task is learned from the spatially distributed mean firing rates (100 ms) of ∼60,000 IT neurons and is executed as a simple weighted sum of those firing rates. Significance statement: We sought to go beyond qualitative models of visual object recognition and determine whether a single neuronal linking hypothesis can quantitatively account for core object recognition behavior. To achieve this, we designed a

  2. Simple Learned Weighted Sums of Inferior Temporal Neuronal Firing Rates Accurately Predict Human Core Object Recognition Performance

    PubMed Central

    Hong, Ha; Solomon, Ethan A.; DiCarlo, James J.

    2015-01-01

    To go beyond qualitative models of the biological substrate of object recognition, we ask: can a single ventral stream neuronal linking hypothesis quantitatively account for core object recognition performance over a broad range of tasks? We measured human performance in 64 object recognition tests using thousands of challenging images that explore shape similarity and identity preserving object variation. We then used multielectrode arrays to measure neuronal population responses to those same images in visual areas V4 and inferior temporal (IT) cortex of monkeys and simulated V1 population responses. We tested leading candidate linking hypotheses and control hypotheses, each postulating how ventral stream neuronal responses underlie object recognition behavior. Specifically, for each hypothesis, we computed the predicted performance on the 64 tests and compared it with the measured pattern of human performance. All tested hypotheses based on low- and mid-level visually evoked activity (pixels, V1, and V4) were very poor predictors of the human behavioral pattern. However, simple learned weighted sums of distributed average IT firing rates exactly predicted the behavioral pattern. More elaborate linking hypotheses relying on IT trial-by-trial correlational structure, finer IT temporal codes, or ones that strictly respect the known spatial substructures of IT (“face patches”) did not improve predictive power. Although these results do not reject those more elaborate hypotheses, they suggest a simple, sufficient quantitative model: each object recognition task is learned from the spatially distributed mean firing rates (100 ms) of ∼60,000 IT neurons and is executed as a simple weighted sum of those firing rates. SIGNIFICANCE STATEMENT We sought to go beyond qualitative models of visual object recognition and determine whether a single neuronal linking hypothesis can quantitatively account for core object recognition behavior. To achieve this, we designed a

  3. Potential dangers of cannabis.

    PubMed

    Kaymakçalan, S

    1975-01-01

    Cannabis is not a harmless drug. The potential dangers of cannabis are briefly reviewed in this report. The above-mentioned observations on cannabis users should be kept in mind and carefully examined by all physicians. One could expect that as more potent cannabis preparations become available, some of the toxic manifestations which now seem rare might become more frequent. Some of the remarks about the dangers of cannabis may not be proved in future studies, and they may represent only our anxiety. However, prior to the elimination of these fears, no steps should be taken toward the legalizing of marijuana. At present there is no scientific evidence that cannabis is less harmful than either tobacco or alcohol. The opposite may be true. The analogy can be drawn between opium and cannabis. The permissive attitude toward the use of opium can easily lead to the use of morphine and other opiates. If we legalize the use of marijuana, we cannot prevent the use of more dangerous derivatives of cannabis; namely, hashish, cannabis oil and THC, itself. In my opinion, in the light of our present knowledge, legalizing of marijuana could be hazardous both for the individual and for society.

  4. The synthetic cannabinoid HU210 induces spatial memory deficits and suppresses hippocampal firing rate in rats.

    PubMed

    Robinson, L; Goonawardena, A V; Pertwee, R G; Hampson, R E; Riedel, G

    2007-07-01

    Previous work implied that the hippocampal cannabinoid system was particularly important in some forms of learning, but direct evidence for this hypothesis is scarce. We therefore assessed the effects of the synthetic cannabinoid HU210 on memory and hippocampal activity. HU210 (100 microg kg(-1)) was administered intraperitoneally to rats under three experimental conditions. One group of animals were pre-trained in spatial working memory using a delayed-matching-to-position task and effects of HU210 were assessed in a within-subject design. In another, rats were injected before acquisition learning of a spatial reference memory task with constant platform location. Finally, a separate group of animals was implanted with electrode bundles in CA1 and CA3 and single unit responses were isolated, before and after HU210 treatment. HU210 treatment had no effect on working or short-term memory. Relative to its control Tween 80, deficits in acquisition of a reference memory version of the water maze were obtained, along with drug-related effects on anxiety, motor activity and spatial learning. Deficits were not reversed by the CB(1) receptor antagonists SR141716A (3 mg kg(-1)) or AM281 (1.5 mg kg(-1)). Single unit recordings from principal neurons in hippocampal CA3 and CA1 confirmed HU210-induced attenuation of the overall firing activity lowering both the number of complex spikes fired and the occurrence of bursts. These data provide the first direct evidence that the underlying mechanism for the spatial memory deficits induced by HU210 in rats is the accompanying abnormality in hippocampal cell firing.

  5. Many Ignore Fire Safety at Home, Survey Reveals

    MedlinePlus

    ... medlineplus.gov/news/fullstory_162699.html Many Ignore Fire Safety at Home, Survey Reveals Holiday activities can ... dangerous time of year, but many families ignore fire and burn safety tips, a new survey finds. ...

  6. Wallace L. Fons: fire research pioneer

    Treesearch

    David R. Weise; Ted R. Fons

    2014-01-01

    During his 30-year career with the U.S. Forest Service, Wally Fons laid the foundation for much of the understanding we have today of forest fire's many properties by applying his mechanical engineering background. He left a legacy of research that formed the basis for the fire behavior and danger systems still used in the United States. In addition to fire...

  7. Fire Safety Technician

    ERIC Educational Resources Information Center

    Moore, Pam

    2007-01-01

    Fire protection is one of the most important considerations in the construction and operation of industrial plants and commercial buildings. Fire insurance rates are determined by fire probability factors, such as the type of construction, ease of transporting personnel, and the quality and quantity of fire protection equipment available. Because…

  8. Fire Safety Technician

    ERIC Educational Resources Information Center

    Moore, Pam

    2007-01-01

    Fire protection is one of the most important considerations in the construction and operation of industrial plants and commercial buildings. Fire insurance rates are determined by fire probability factors, such as the type of construction, ease of transporting personnel, and the quality and quantity of fire protection equipment available. Because…

  9. Effect of wearing personal protective clothing and self-contained breathing apparatus on heart rate, temperature and oxygen consumption during stepping exercise and live fire training exercises.

    PubMed

    Bruce-Low, S S; Cotterrell, D; Jones, G E

    2007-01-15

    Fire fighter breathing apparatus instructors (BAIs) must possess the ability to respond to both the extrinsic stress of a high temperature environment and the intrinsic stress from wearing personal protective equipment (PPE) and self-contained breathing apparatus (SCBA), repeatedly and regularly, whilst training recruits in live fire training exercises (LFTEs). There are few previous investigations on BAIs in hot environments such as LFTEs, since the main research focus has been on regular fire fighters undertaking exercises in temperate or fire conditions at a moderate to high exercise intensity. In this study, the intrinsic cardiovascular stress effects of wearing PPE + SCBA were first investigated using a step test whilst wearing gym kit (control), weighted gym kit (a rucksack weighted to the equivalent of PPE + SCBA) and full PPE + SCBA (weight plus the effects of protective clothing). The extrinsic effects of the very hot environment were investigated in BIAs in LFTEs compared to mock fire training exercises (MFTEs), where the fire was not ignited. There was an increase in heart rate due to the modest workload imposed on the BAIs through carrying out the MFTEs (25.0 (18.7)%) compared to resting. However, when exposed to fire during the LFTEs, heat storage appears to be significant as the heart rate increased by up to 39.8 (+/-20.1)% over that of the mock LFTEs at temperate conditions. Thus, being able to dissipate heat from the PPE is particularly important in reducing the cardiovascular responses for BAIs during LFTEs.

  10. Fire Protection for Libraries.

    ERIC Educational Resources Information Center

    Fortson-James, Judith

    1981-01-01

    This overview of preventive measures that can be taken to help minimize damage to library materials from fire discusses the advantages, disadvantages, dangers, and comparative costs of several types of sprinkler systems, including high-expansion foam, total-flooding, dry- and wet-pipe systems, and on-off sprinkler heads. Five references are…

  11. Fire Protection for Libraries.

    ERIC Educational Resources Information Center

    Fortson-James, Judith

    1981-01-01

    This overview of preventive measures that can be taken to help minimize damage to library materials from fire discusses the advantages, disadvantages, dangers, and comparative costs of several types of sprinkler systems, including high-expansion foam, total-flooding, dry- and wet-pipe systems, and on-off sprinkler heads. Five references are…

  12. Fire Suppression, District 5

    Treesearch

    Roy Headley

    1916-01-01

    The increasing effectiveness of suppression practice is shown by the fact that in 1915 fire suppression cost one-third as much as in 1914, and damage to Government property was kept down to one-fourth the 1914 figure. The seasons were approximately equal in danger. Is further progress to be expected?

  13. Experimental study on burning rates of square/rectangular gasoline and methanol pool fires under longitudinal air flow in a wind tunnel.

    PubMed

    Hu, L H; Liu, S; Peng, W; Huo, R

    2009-09-30

    Square pool fires with length of 5, 7.5, 10, 15, 20, 25 and 30 cm and rectangular pool fires with dimensions of 10 cm x 20 cm and 10 cm x 40 cm were burned in a wind tunnel, under a longitudinal air flow ranged from 0 to 3m/s with incremental change of about 0.5m/s. Methanol and gasoline were burned and compared, with results indicated that their burning rates showed different response to the longitudinal air flow. With the increase of the longitudinal air flow speed, the burning rates of methanol pool fires, except the 5 cm square one, first decreased and then increased, but those of the 5 cm methanol square one and the gasoline pool fires increased monotonously. The burning rate of smaller square pool fires increased more significantly than that of the larger ones, as well as the enlargement of their flame attachment length along the ground. The burning rate of a rectangular pool fire with longer rim parallel to the longitudinal flow increased faster, but the flame attachment length seemed to increase more gradually, with the increase of the longitudinal air flow speed than that perpendicular to.

  14. Comparison of GPU- and CPU-implementations of mean-firing rate neural networks on parallel hardware.

    PubMed

    Dinkelbach, Helge Ülo; Vitay, Julien; Beuth, Frederik; Hamker, Fred H

    2012-01-01

    Modern parallel hardware such as multi-core processors (CPUs) and graphics processing units (GPUs) have a high computational power which can be greatly beneficial to the simulation of large-scale neural networks. Over the past years, a number of efforts have focused on developing parallel algorithms and simulators best suited for the simulation of spiking neural models. In this article, we aim at investigating the advantages and drawbacks of the CPU and GPU parallelization of mean-firing rate neurons, widely used in systems-level computational neuroscience. By comparing OpenMP, CUDA and OpenCL implementations towards a serial CPU implementation, we show that GPUs are better suited than CPUs for the simulation of very large networks, but that smaller networks would benefit more from an OpenMP implementation. As this performance strongly depends on data organization, we analyze the impact of various factors such as data structure, memory alignment and floating precision. We then discuss the suitability of the different hardware depending on the networks' size and connectivity, as random or sparse connectivities in mean-firing rate networks tend to break parallel performance on GPUs due to the violation of coalescence.

  15. Acute effects of dynamic exercises on the relationship between the motor unit firing rate and the recruitment threshold.

    PubMed

    Ye, Xin; Beck, Travis W; DeFreitas, Jason M; Wages, Nathan P

    2015-04-01

    The aim of this study was to compare the acute effects of concentric versus eccentric exercise on motor control strategies. Fifteen men performed six sets of 10 repetitions of maximal concentric exercises or eccentric isokinetic exercises with their dominant elbow flexors on separate experimental visits. Before and after the exercise, maximal strength testing and submaximal trapezoid isometric contractions (40% of the maximal force) were performed. Both exercise conditions caused significant strength loss in the elbow flexors, but the loss was greater following the eccentric exercise (t=2.401, P=.031). The surface electromyographic signals obtained from the submaximal trapezoid isometric contractions were decomposed into individual motor unit action potential trains. For each submaximal trapezoid isometric contraction, the relationship between the average motor unit firing rate and the recruitment threshold was examined using linear regression analysis. In contrast to the concentric exercise, which did not cause significant changes in the mean linear slope coefficient and y-intercept of the linear regression line, the eccentric exercise resulted in a lower mean linear slope and an increased mean y-intercept, thereby indicating that increasing the firing rates of low-threshold motor units may be more important than recruiting high-threshold motor units to compensate for eccentric exercise-induced strength loss.

  16. Risk for large-scale fires in boreal forests of Finland under changing climate

    NASA Astrophysics Data System (ADS)

    Lehtonen, I.; Venäläinen, A.; Kämäräinen, M.; Peltola, H.; Gregow, H.

    2015-08-01

    The target of this work was to assess the impact of projected climate change on the number of large forest fires (over 10 ha fires) and burned area in Finland. For this purpose, we utilized a strong relationship between fire occurrence and the Canadian fire weather index (FWI) during 1996-2014. We used daily data from five global climate models under representative concentration pathway RCP4.5 and RCP8.5 scenarios. The model data were statistically downscaled onto a high-resolution grid using the quantile-mapping method before performing the analysis. Our results suggest that the number of large forest fires may double or even triple during the present century. This would increase the risk that some of the fires could develop into real conflagrations which have become almost extinct in Finland due to active and efficient fire suppression. Our results also reveal substantial inter-model variability in the rate of the projected increase in forest-fire danger. We moreover showed that the majority of large fires occur within a relatively short period in May and June due to human activities and that FWI correlates poorer with the fire activity during this time of year than later in summer when lightning is more important cause of fires.

  17. Observations of energy transport and rate of spreads from low-intensity fires in longleaf pine habitat-RxCADRE 2012

    Treesearch

    Bret Butler; C. Teske; Dan Jimenez; Joseph O' Brien; Paul Sopko; Cyle Wold; Mark Vosburgh; Ben Hornsby; E. Louise Loudermilk

    2016-01-01

    Wildland fire rate of spread (ROS) and intensity are determined by the mode and magnitude of energy transport from the flames to the unburned fuels. Measurements of radiant and convective heating and cooling from experimental fires are reported here. Sensors were located nominally 0.5mabove ground level. Flame heights varied from 0.3 to 1.8 m and flaming zone depth...

  18. CRYPTOCHROME is a blue-light sensor that regulates neuronal firing rate.

    PubMed

    Fogle, Keri J; Parson, Kelly G; Dahm, Nicole A; Holmes, Todd C

    2011-03-18

    Light-responsive neural activity in central brain neurons is generally conveyed through opsin-based signaling from external photoreceptors. Large lateral ventral arousal neurons (lLNvs) in Drosophila melanogaster increase action potential firing within seconds in response to light in the absence of all opsin-based photoreceptors. Light-evoked changes in membrane resting potential occur in about 100 milliseconds. The light response is selective for blue wavelengths corresponding to the spectral sensitivity of CRYPTOCHROME (CRY). cry-null lines are light-unresponsive, but restored CRY expression in the lLNv rescues responsiveness. Furthermore, expression of CRY in neurons that are normally unresponsive to light confers responsiveness. The CRY-mediated light response requires a flavin redox-based mechanism and depends on potassium channel conductance, but is independent of the classical circadian CRY-TIMELESS interaction.

  19. Spatio-temporal vulnerability of forest fire to climate change in Korea

    NASA Astrophysics Data System (ADS)

    Kwak, H.; Lee, W.; Lee, S.; Lee, M.; Koo, K.; Won, M.

    2009-12-01

    Climate is known as crucial factor on forest fire occurrence. Although most of forest fires occurred by human activities, climate factor is the most important cause for forest fire due to moisture containment of fuel. The objective of this study is to estimate forest fire occurrence according to the past forest fire and to assess the vulnerability with forest cover map. Spatial data of forest fire was prepared from forest fire record of Korea Forest Service (KFS). The forest fire record consists of date, time and XY coordination of the forest fires between 1991 and 2006. Past climate data obtained at 75 weather stations was rearranged with Inverse Distance Weighted Interpolation. The climate data included temperature, relative humidity, cloudness and precipitation. We considered the laps rate temperature depending on elevation. The 10 days accumulation of rainfall data was used to the precipitation data. Forest fire point data and climate data were matched according to time and location. Prepared data was analyzed in statistical method, Poisson regression. And also, we estimated the probability of forest fire occurrence with future climate data which was simulated by A1B scenario of IPCC. This future climate data was prepared with ECHO-G model by Korea Meteorological Administration (KMA). Finally, the forest fire risk map was overwrapped on forest cover map. Because fire occurrence depends on the species of forest, the fire occurrence probability was weighted according to the forest cover information. In this way, the vulnerability was assessed. Our results showed that relative humidity has a significant effect on forest fire. Using these results, forest fire danger map of the future was derived.

  20. South Asia: Danger Ahead?

    DTIC Science & Technology

    2011-01-01

    2011 4 . TITLE AND SUBTITLE South Asia: Danger Ahead? 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...its opponent and preclude a devastating retaliatory response. 4 Fundamen­ tally, both countries are restricted to use their nuclear forces to threaten...threaten India’s hold in the Kashmir Valley; to control a part of the Himalayan Range to facili­ tate insurgent movement into the Kashmir Valley and the

  1. 1954 forest fire weather in western Oregon and Washington.

    Treesearch

    Owen P. Cramer

    1954-01-01

    For the second successive fire season forest fire weather in western Oregon and Washington was far below normal severity. The low danger is reflected in record low numbers of fires reported by forestry offices of both States and by the U. S. Forest Service for their respective protection areas. Although spring and fall fire weather was near normal, a rain-producing...

  2. Preventing Fire Death and Injury, Conducting a Fire Drill in a Group Home [and] When You Need a Fire Safety Expert. National Fire Safety Certification System. Continuing Education Program. Volume 1, Numbers 1-3.

    ERIC Educational Resources Information Center

    Walker, Bonnie

    Three booklets provide fire safety information for staff of residential facilities serving people with developmental disabilities. Booklets focus on: (1) preventing fire death and injury, (2) conducting a fire drill in a group home, and (3) the role of fire safety experts. The first booklet stresses the elimination of the following dangers:…

  3. Assessing predictive services' 7-day fire potential outlook

    Treesearch

    Karin Riley; Crystal Stonesifer; Dave Calkin; Haiganoush Preisler

    2015-01-01

    The Predictive Services program was created under the National Wildfire Coordinating Group in 2001 to address the need for long- and short-term decision support information for fire managers and operations personnel. The primary mission of Predictive Services is to integrate fire weather, fire danger, and resource availability to enable strategic fire suppression...

  4. Explaining climate danger

    NASA Astrophysics Data System (ADS)

    Oreskes, N.

    2016-12-01

    The idea of `managing planet Earth' is traceable back at least to the 1970s. Recently, it has been reformulated in the idea of a "good Anthropocene": the idea that humans should and can try to manage our planet now that we have become a planetary force. Yet available evidence and experience suggests that our prior attempts to do so have been plagued by under-estimation of the scale of the problems and over-estimation of our capacities to address them. In any case, Earth is not at risk—our planet will survive despite what we do or fail to do. Global climate change, for example, is not a problem for the planet, it is a problem for us. As the UNFCCC articulated in the 1990s, climate change matters because it is dangerous. Yet many Americans still do not understand why this is the case. I suggest that scientists can profitably focus attention on explaining this danger—why climate represents a threat to our health, well-being, and lives—and on what kinds of steps can be taken to reduce the danger.

  5. Dangerous marine animals.

    PubMed

    Edmonds, C

    1976-04-01

    Tales of dangerous marine animals have flourished, entwining history, legend and imagination. Man is now demonstrating his remarkable adaptability in returning to the aquatic environment, from which he had his origins, and factual knowledge of marine creatures is surplanting mystery, folklore and fear. There is still cause to fear certain aspects of the underwater world, and the one aspect that still holds sway over public interest is that of dangerous marine animals. There is little justification for this top priority. The kelp beds of San Diego will claim more diving victims than all the marine animals around the United States of America. The cold seas off the English coastline, the tidal currents of Hawaii and the multitude of drowning accidents in water caves of Florida and Australia belittle the relatively few fatalities caused by marine animals. Nevertheless, the latter do cause injury and death, especially in the tropical, subtropical and temperate regions. The Indo-Pacific area seems particularly well endowed with a variety of potentially lethal species, and some of these will be dealt with in this paper.

  6. Understanding Ozark Forest Litter Variability Through a Synthesis of Accumulation Rates and Fire Events

    Treesearch

    Michael C. Stambaugh; Richard P. Guyette; Keith W. Grabner; Jeremy Kolaks

    2006-01-01

    Measuring success of fuels management is improved by understanding rates of litter accumulation and decay in relation to disturbance events. Despite the broad ecological importance of litter, little is known about the parameters of accumulation and decay rates in Ozark forests. Previously published estimates were used to derive accumulation rates and combined litter...

  7. Progress toward the determination of correct classification rates in fire debris analysis II: utilizing soft independent modeling of class analogy (SIMCA).

    PubMed

    Waddell, Erin E; Williams, Mary R; Sigman, Michael E

    2014-07-01

    A multistep classification scheme was used to detect and classify ignitable liquid residues in fire debris into the classes defined by the ASTM E1618-10 standard method. The total ion spectra (TIS) of the samples were classified by soft independent modeling of class analogy (SIMCA) with cross-validation and tested on fire debris. For detection of ignitable liquid residue, the true-positive rate was 94.2% for cross-validation and 79.1% for fire debris, with false-positive rates of 5.1% and 8.9%, respectively. Evaluation of SIMCA classifications for fire debris relative to a reviewer's examination led to an increase in the true-positive rate to 95.1%; however, the false-positive rate also increased to 15.0%. The correct classification rates for assigning ignitable liquid residues into ASTM E1618-10 classes were generally in the range of 80-90%, with the exception of gasoline samples, which were incorrectly classified as aromatic solvents following evaporative weathering in fire debris.

  8. Effect of correlated lateral geniculate nucleus firing rates on predictions for monocular eye closure versus monocular retinal inactivation

    NASA Astrophysics Data System (ADS)

    Blais, Brian S.; Cooper, Leon N.; Shouval, Harel Z.

    2009-12-01

    Monocular deprivation experiments can be used to distinguish between different ideas concerning properties of cortical synaptic plasticity. Monocular deprivation by lid suture causes a rapid disconnection of the deprived eye connected to cortical neurons whereas total inactivation of the deprived eye produces much less of an ocular dominance shift. In order to understand these results one needs to know how lid suture and retinal inactivation affect neurons in the lateral geniculate nucleus (LGN) that provide the cortical input. Recent experimental results by Linden showed that monocular lid suture and monocular inactivation do not change the mean firing rates of LGN neurons but that lid suture reduces correlations between adjacent neurons whereas monocular inactivation leads to correlated firing. These, somewhat surprising, results contradict assumptions that have been made to explain the outcomes of different monocular deprivation protocols. Based on these experimental results we modify our assumptions about inputs to cortex during different deprivation protocols and show their implications when combined with different cortical plasticity rules. Using theoretical analysis, random matrix theory and simulations we show that high levels of correlations reduce the ocular dominance shift in learning rules that depend on homosynaptic depression (i.e., Bienenstock-Cooper-Munro type rules), consistent with experimental results, but have the opposite effect in rules that depend on heterosynaptic depression (i.e., Hebbian/principal component analysis type rules).

  9. Impacts of changing fire weather conditions on reconstructed trends in U.S. wildland fire activity from 1979 to 2014

    Treesearch

    Patrick H. Freeborn; W. Matt Jolly; Mark A. Cochrane

    2016-01-01

    One component of climate‐fire interactions is the relationship between weather conditions concurrent with burning (i.e., fire danger) and the magnitude of fire activity. Here daily environmental conditions are associated with daily observations of fire activity within ecoregions across the continental United States (CONUS) by aligning the latter 12 years of a 36 year...

  10. Forest fire weather and computed fire occurrence in western Oregon and western Washington in 1960.

    Treesearch

    Owen P. Cramer

    1960-01-01

    Fire season severity in 1960 was about average in western Washington but was very high in western Oregon. Severity of the entire season in both States was slightly greater than in 1959. Although spring was less severe, both summer and fall were slightly more severe than comparable parts of the previous fire season. Spring fire danger in western Washington was as low as...

  11. Is moral bioenhancement dangerous?

    PubMed

    Drake, Nicholas

    2016-01-01

    In a recent response to Persson and Savulescu's Unfit for the Future, Nicholas Agar argues that moral bioenhancement is dangerous. His grounds for this are that normal moral judgement should be privileged because it involves a balance of moral subcapacities; moral bioenhancement, Agar argues, involves the enhancement of only particular moral subcapacities, and thus upsets the balance inherent in normal moral judgement. Mistaken moral judgements, he says, are likely to result. I argue that Agar's argument fails for two reasons. First, having strength in a particular moral subcapacity does not necessarily entail a worsening of moral judgement; it can involve strength in a particular aspect of morality. Second, normal moral judgement is not sufficiently likely to be correct to be the standard by which moral judgements are measured.

  12. Provisional Machine-Gun Firing Manual

    DTIC Science & Technology

    1917-06-21

    a table of fire (angles of elevation and departure, angles of fall, time of flight , etc.); a table of ordinates; a table of dangerous spaces; a table...0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing...units to bring an effective fire to bear upon the desired target at the proper time . It pertains especially to preparation of fire. Fire discipline: Is

  13. Localized states in an unbounded neural field equation with smooth firing rate function: a multi-parameter analysis.

    PubMed

    Faye, Grégory; Rankin, James; Chossat, Pascal

    2013-05-01

    The existence of spatially localized solutions in neural networks is an important topic in neuroscience as these solutions are considered to characterize working (short-term) memory. We work with an unbounded neural network represented by the neural field equation with smooth firing rate function and a wizard hat spatial connectivity. Noting that stationary solutions of our neural field equation are equivalent to homoclinic orbits in a related fourth order ordinary differential equation, we apply normal form theory for a reversible Hopf bifurcation to prove the existence of localized solutions; further, we present results concerning their stability. Numerical continuation is used to compute branches of localized solution that exhibit snaking-type behaviour. We describe in terms of three parameters the exact regions for which localized solutions persist.

  14. Is Brain Emulation Dangerous?

    NASA Astrophysics Data System (ADS)

    Eckersley, Peter; Sandberg, Anders

    2013-12-01

    Brain emulation is a hypothetical but extremely transformative technology which has a non-zero chance of appearing during the next century. This paper investigates whether such a technology would also have any predictable characteristics that give it a chance of being catastrophically dangerous, and whether there are any policy levers which might be used to make it safer. We conclude that the riskiness of brain emulation probably depends on the order of the preceding research trajectory. Broadly speaking, it appears safer for brain emulation to happen sooner, because slower CPUs would make the technology`s impact more gradual. It may also be safer if brains are scanned before they are fully understood from a neuroscience perspective, thereby increasing the initial population of emulations, although this prediction is weaker and more scenario-dependent. The risks posed by brain emulation also seem strongly connected to questions about the balance of power between attackers and defenders in computer security contests. If economic property rights in CPU cycles1 are essentially enforceable, emulation appears to be comparatively safe; if CPU cycles are ultimately easy to steal, the appearance of brain emulation is more likely to be a destabilizing development for human geopolitics. Furthermore, if the computers used to run emulations can be kept secure, then it appears that making brain emulation technologies ―open‖ would make them safer. If, however, computer insecurity is deep and unavoidable, openness may actually be more dangerous. We point to some arguments that suggest the former may be true, tentatively implying that it would be good policy to work towards brain emulation using open scientific methodology and free/open source software codebases

  15. Brain activity modeling in general anesthesia: Enhancing local mean-field models using a slow adaptive firing rate

    NASA Astrophysics Data System (ADS)

    Molaee-Ardekani, B.; Senhadji, L.; Shamsollahi, M. B.; Vosoughi-Vahdat, B.; Wodey, E.

    2007-10-01

    In this paper, an enhanced local mean-field model that is suitable for simulating the electroencephalogram (EEG) in different depths of anesthesia is presented. The main building elements of the model (e.g., excitatory and inhibitory populations) are taken from Steyn-Ross [M. L. Steyn-Ross , Phys. Rev. E 64, 011917 (2001), D. A. Steyn-Ross , Phys. Rev. E 64, 011918 (2001)] and Bojak and Liley [I. Bojak and D. T. Liley, Phys. Rev. E 71, 041902 (2005)] mean-field models and a new slow ionic mechanism is included in the main model. Generally, in mean-field models, some sigmoid-shape functions determine firing rates of neural populations according to their mean membrane potentials. In the enhanced model, the sigmoid function corresponding to excitatory population is redefined to be also a function of the slow ionic mechanism. This modification adapts the firing rate of neural populations to slow ionic activities of the brain. When an anesthetic drug is administered, the slow mechanism may induce neural cells to alternate between two levels of activity referred to as up and down states. Basically, the frequency of up-down switching is in the delta band (0-4Hz) and this is the main reason behind high amplitude, low frequency fluctuations of EEG signals in anesthesia. Our analyses show that the enhanced model may have different working states driven by anesthetic drug concentration. The model is settled in the up state in the waking period, it may switch to up and down states in moderate anesthesia while in deep anesthesia it remains in the down state.

  16. A formalism for evaluating analytically the cross-correlation structure of a firing-rate network model.

    PubMed

    Fasoli, Diego; Faugeras, Olivier; Panzeri, Stefano

    2015-01-01

    We introduce a new formalism for evaluating analytically the cross-correlation structure of a finite-size firing-rate network with recurrent connections. The analysis performs a first-order perturbative expansion of neural activity equations that include three different sources of randomness: the background noise of the membrane potentials, their initial conditions, and the distribution of the recurrent synaptic weights. This allows the analytical quantification of the relationship between anatomical and functional connectivity, i.e. of how the synaptic connections determine the statistical dependencies at any order among different neurons. The technique we develop is general, but for simplicity and clarity we demonstrate its efficacy by applying it to the case of synaptic connections described by regular graphs. The analytical equations so obtained reveal previously unknown behaviors of recurrent firing-rate networks, especially on how correlations are modified by the external input, by the finite size of the network, by the density of the anatomical connections and by correlation in sources of randomness. In particular, we show that a strong input can make the neurons almost independent, suggesting that functional connectivity does not depend only on the static anatomical connectivity, but also on the external inputs. Moreover we prove that in general it is not possible to find a mean-field description à la Sznitman of the network, if the anatomical connections are too sparse or our three sources of variability are correlated. To conclude, we show a very counterintuitive phenomenon, which we call stochastic synchronization, through which neurons become almost perfectly correlated even if the sources of randomness are independent. Due to its ability to quantify how activity of individual neurons and the correlation among them depends upon external inputs, the formalism introduced here can serve as a basis for exploring analytically the computational capability of

  17. Effects of Post-Fire Salvage Logging on Erosion Rates at Multiple Scales

    NASA Astrophysics Data System (ADS)

    Wagenbrenner, J. W.; Robichaud, P. R.; MacDonald, L. H.; Brown, R. E.

    2014-12-01

    Forest managers sometimes harvest burned trees after wildfires to realize economic value, reduce fuel loads, or achieve other operational goals. This logging can be controversial because some ecosystem effects are negative, yet the potential impacts on erosion rates have not been clearly identified. Our objectives were to quantify hillslope-scale erosion rates and compare the hillslope erosion rates to rates from larger (swale) and smaller (rill) scales. Soil characteristics, vegetative regrowth, and erosion rates were measured in logged areas and unlogged controls at seven severely burned sites in the western US. One site had replicated measurements at all three scales, five sites had only hillslope or swale scale measurements, and one site had only rill measurements. Erosion rates from hillslopes (70-170 m2) and swales (0.1-2.6 ha) were measured with sediment fences. Rill erosion rates were measured with rill experiments, where water was applied to a hillslope at five flow rates for 12 min each; water samples were collected at a point 9 m downslope. At the hillslope scale the passage of heavy logging equipment reduced soil water repellency, compacted the soil, reduced vegetative regrowth rates, and generally increased erosion rates by one or two orders of magnitude relative to the controls. The rill experiments also showed greater rates of rill incision and erosion from the areas disturbed by heavy logging equipment relative to the controls. At the swale scale erosion rates were higher in the logged areas than the controls when measurements were replicated and simultaneous but there was no detectable change in the other study areas. Overall, the absolute erosion rates from both logged and unlogged areas tended to decline over time while the relative difference in erosion tended to increase due to the slower vegetative recovery in the more heavily disturbed areas. The potential adverse effects of salvage logging can be minimized by reducing compaction and

  18. Can both normal and mildly abnormal albuminuria and glomerular filtration rate be a danger signal for diabetic peripheral neuropathy in type 2 diabetes mellitus?

    PubMed

    Zhang, Yongze; Jiang, Ying; Shen, Ximei; Yan, Sunjie

    2017-08-01

    We aimed to investigate the potential association between urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) and diabetic peripheral neuropathy (DPN). We were especially interested in the relationship between normal or mildly abnormal UACR and eGFR with DPN. A retrospective study was performed in 1059 patients with type 2 diabetes patients from Fuzhou, China, who were seen between 2010 and 2015. The DPN population demonstrated higher UACR and lower eGFR than the non-DPN population. Nerve conduction velocities (NCVs) were negatively correlated with UACR and were positively correlated with eGFR. UACR and eGFR were associated with the risk of DPN. Even in the UACR < 30 mg/g and eGFR ≥ 60 ml/min/1.73 m(2) groups, the relationship above still existed and patients in the highest tertiles of UACR and lowest tertiles of eGFR demonstrated a greater risk of DPN (OR = 2.456, 95% CI 1.461-4.127; OR = 2.021, 95% CI 1.276-3.203). Receiver operating characteristic (ROC) analysis revealed that the area under curve (AUC) of UACR, eGFR, and joints indicates that DPN was 0.749, 0.662, and 0.731, respectively. Lower eGFR and higher UACR may be associated with the risk of DPN, even though normal or mildly abnormal UACR and eGFR have already been found to be predictive factors of DPN. Further, UACR is more sensitive than eGFR. Separately, UACR was a moderate indication of DPN, and combining it with eGFR did not increase its effect of indication to DPN.

  19. Low-dimensional spike rate models derived from networks of adaptive integrate-and-fire neurons: Comparison and implementation

    PubMed Central

    Baumann, Fabian; Obermayer, Klaus

    2017-01-01

    The spiking activity of single neurons can be well described by a nonlinear integrate-and-fire model that includes somatic adaptation. When exposed to fluctuating inputs sparsely coupled populations of these model neurons exhibit stochastic collective dynamics that can be effectively characterized using the Fokker-Planck equation. This approach, however, leads to a model with an infinite-dimensional state space and non-standard boundary conditions. Here we derive from that description four simple models for the spike rate dynamics in terms of low-dimensional ordinary differential equations using two different reduction techniques: one uses the spectral decomposition of the Fokker-Planck operator, the other is based on a cascade of two linear filters and a nonlinearity, which are determined from the Fokker-Planck equation and semi-analytically approximated. We evaluate the reduced models for a wide range of biologically plausible input statistics and find that both approximation approaches lead to spike rate models that accurately reproduce the spiking behavior of the underlying adaptive integrate-and-fire population. Particularly the cascade-based models are overall most accurate and robust, especially in the sensitive region of rapidly changing input. For the mean-driven regime, when input fluctuations are not too strong and fast, however, the best performing model is based on the spectral decomposition. The low-dimensional models also well reproduce stable oscillatory spike rate dynamics that are generated either by recurrent synaptic excitation and neuronal adaptation or through delayed inhibitory synaptic feedback. The computational demands of the reduced models are very low but the implementation complexity differs between the different model variants. Therefore we have made available implementations that allow to numerically integrate the low-dimensional spike rate models as well as the Fokker-Planck partial differential equation in efficient ways for

  20. Fires in Southern Georgia

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Several large fires were burning in southern Georgia on April 29, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite passed overhead and captured this image. Places where MODIS detected actively burning fires are outlined in red. The Roundabout Fire sprang up on April 27, according to the U.S. Southern Area Coordination Center, and was about 3,500 acres as of April 30. That fire was threatening homes in the community of Kirkland. Meanwhile, south of Waycross, two large blazes were burning next to each other in the northern part of Okefenokee Swamp. The Sweat Farm Road Fire threatened the town of Waycross in previous weeks, but at the end of April, activity had moved to the southeastern perimeter. The fire had affected more than 50,000 acres of timber (including pine tree plantations) and swamps. Scores of residences scattered throughout the rural area are threatened. The Big Turnaround Complex is burning to the east. The 26,000-acre fire was extremely active over the weekend, with flame lengths more than 60 feet (just over 18 meters) in places. The two blazes appeared to overlap in fire perimeter maps available from the U.S. Geospatial Multi-Agency Coordination Team. According to the Southern Area Coordination Center morning report on April 30, the Sweat Farm Road Fire 'will be a long term fire. Containment and control will depend on significant rainfall, due to the inaccessible swamp terrain.' No expected containment date was available for the Big Turnaround Complex Fire, either. Describing that fire, the report stated, 'Heavy fuel loading, high fire danger, and difficulty of access continue to hamper suppression efforts.' The large image provided above has a spatial resolution (level of detail) of 250 meters per pixel. The MODIS Rapid Response Team provides twice-daily images of the region in additional resolutions. They also provide a version of the image that shows smoke plumes stretching out across the Atlantic Ocean.

  1. Fires in Southern Georgia

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Several large fires were burning in southern Georgia on April 29, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite passed overhead and captured this image. Places where MODIS detected actively burning fires are outlined in red. The Roundabout Fire sprang up on April 27, according to the U.S. Southern Area Coordination Center, and was about 3,500 acres as of April 30. That fire was threatening homes in the community of Kirkland. Meanwhile, south of Waycross, two large blazes were burning next to each other in the northern part of Okefenokee Swamp. The Sweat Farm Road Fire threatened the town of Waycross in previous weeks, but at the end of April, activity had moved to the southeastern perimeter. The fire had affected more than 50,000 acres of timber (including pine tree plantations) and swamps. Scores of residences scattered throughout the rural area are threatened. The Big Turnaround Complex is burning to the east. The 26,000-acre fire was extremely active over the weekend, with flame lengths more than 60 feet (just over 18 meters) in places. The two blazes appeared to overlap in fire perimeter maps available from the U.S. Geospatial Multi-Agency Coordination Team. According to the Southern Area Coordination Center morning report on April 30, the Sweat Farm Road Fire 'will be a long term fire. Containment and control will depend on significant rainfall, due to the inaccessible swamp terrain.' No expected containment date was available for the Big Turnaround Complex Fire, either. Describing that fire, the report stated, 'Heavy fuel loading, high fire danger, and difficulty of access continue to hamper suppression efforts.' The large image provided above has a spatial resolution (level of detail) of 250 meters per pixel. The MODIS Rapid Response Team provides twice-daily images of the region in additional resolutions. They also provide a version of the image that shows smoke plumes stretching out across the Atlantic Ocean.

  2. Remote sensing information for fire management and fire effects assessment

    NASA Astrophysics Data System (ADS)

    Chuvieco, Emilio; Kasischke, Eric S.

    2007-03-01

    Over the past decade, much research has been carried out on the utilization of advanced geospatial technologies (remote sensing and geographic information systems) in the fire science and fire management disciplines. Recent advances in these technologies were the focus of a workshop sponsored by the EARSEL special interest group (SIG) on forest fires (FF-SIG) and the Global Observation of Forest and Land Cover Dynamics (GOFC-GOLD) fire implementation team. Here we summarize the framework and the key findings of papers submitted from this meeting and presented in this special section. These papers focus on the latest advances for near real-time monitoring of active fires, prediction of fire hazards and danger, monitoring of fuel moisture, mapping of fuel types, and postfire assessment of the impacts from fires.

  3. Stochastic representation of fire behavior in a wildland fire protection planning model for California.

    Treesearch

    J. Keith Gilless; Jeremy S. Fried

    1998-01-01

    A fire behavior module was developed for the California Fire Economics Simulator version 2 (CFES2), a stochastic simulation model of initial attack on wildland fire used by the California Department of Forestry and Fire Protection. Fire rate of spread (ROS) and fire dispatch level (FDL) for simulated fires "occurring" on the same day are determined by making...

  4. Axonal and synaptic failure suppress the transfer of firing rate oscillations, synchrony and information during high frequency deep brain stimulation.

    PubMed

    Rosenbaum, Robert; Zimnik, Andrew; Zheng, Fang; Turner, Robert S; Alzheimer, Christian; Doiron, Brent; Rubin, Jonathan E

    2014-02-01

    High frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a widely used treatment for Parkinson's disease, but its effects on neural activity in basal ganglia circuits are not fully understood. DBS increases the excitation of STN efferents yet decouples STN spiking patterns from the spiking patterns of STN synaptic targets. We propose that this apparent paradox is resolved by recent studies showing an increased rate of axonal and synaptic failures in STN projections during DBS. To investigate this hypothesis, we combine in vitro and in vivo recordings to derive a computational model of axonal and synaptic failure during DBS. Our model shows that these failures induce a short term depression that suppresses the synaptic transfer of firing rate oscillations, synchrony and rate-coded information from STN to its synaptic targets. In particular, our computational model reproduces the widely reported suppression of parkinsonian β oscillations and synchrony during DBS. Our results support the idea that short term depression is a therapeutic mechanism of STN DBS that works as a functional lesion by decoupling the somatic spiking patterns of STN neurons from spiking activity in basal ganglia output nuclei.

  5. A fast-firing shrinkage rate controlled dilatometer using an infrared image furnace

    NASA Astrophysics Data System (ADS)

    Hackenberger, W. S.; Speyer, R. F.

    1994-03-01

    A novel dilatometer design is described for performing rate controlled sintering experiments on powder compacts. Previous rate controlled sintering systems, which control the shrinkage of a sintering compact, possessed only limited shrinkage rate control and shrinkage profile complexity due to the high thermal mass of conventional furnaces and dilatometers. The instrument described in this work features an infrared imaging furnace and a low thermal mass dilatometer assembly which together provide a very rapid temperature response. The system is capable of heating and cooling ceramic samples at up to 500 °C/min. Shrinkage control is accomplished using a modified, computer interfaced proportional-integral-derivative algorithm, and tests on glass-alumina composite samples demonstrated excellent shrinkage control with differences routinely less than 0.2% between the set point and actual shrinkage.

  6. Body Sodium Overload Modulates the Firing Rate and Fos Immunoreactivity of Serotonergic Cells of Dorsal Raphe Nucleus

    PubMed Central

    Godino, Andrea; Pitra, Soledad; Carrer, Hugo F.; Vivas, Laura

    2013-01-01

    In order to determine whether serotonergic (5HT) dorsal raphe nucleus (DRN) cells are involved in body sodium status regulation, the effect of a s.c. infusion of either 2 M or 0.15 M NaCl on 5HT DRN neuron firing was studied using single unit extracellular recordings. In separate groups of 2 M and 0.15 M NaCl-infused rats, water intake, oxytocin (OT) plasma concentration, urine and plasma sodium and protein concentrations were also measured. Also, to determine the involvement of particular brain nuclei and neurochemical systems in body sodium overload (SO), animals from both groups were perfused for brain immunohistochemical detection of Fos, Fos-OT and Fos-5HT expression. SO produced a significant increase in serotonergic DRN neuron firing rate compared to baseline and 0.15 M NaCl-infused rats. As expected, 2 M NaCl s.c. infusion also induced a significant increase of water intake, diuresis and natriuresis, plasma sodium concentration and osmolality, even though plasma volume did not increase as indicated by changes in plasma protein concentration. The distribution of neurons along the forebrain and brainstem expressing Fos after SO showed the participation of the lamina terminalis, extended amygdala, supraoptic and paraventricular hypothalamic nuclei in the neural network that controls osmoregulatory responses. Both Fos-OT immunoreactive and plasma OT concentration increased after s.c. hypertonic sodium infusion. Finally, matching the “in vivo” electrophysiological study, SO doubled the number of Fos-5HT immunolabeled cells within the DRN. In summary, the results characterize the behavioral, renal and endocrine responses after body sodium overload without volume expansion and specify the cerebral nuclei that participate at different CNS levels in the control of these responses. The electrophysiological approach also allows us to determine in an “in vivo" model that DRN 5HT neurons increase their firing frequency during an increase in systemic sodium

  7. Body sodium overload modulates the firing rate and fos immunoreactivity of serotonergic cells of dorsal raphe nucleus.

    PubMed

    Godino, Andrea; Pitra, Soledad; Carrer, Hugo F; Vivas, Laura

    2013-01-01

    In order to determine whether serotonergic (5HT) dorsal raphe nucleus (DRN) cells are involved in body sodium status regulation, the effect of a s.c. infusion of either 2 M or 0.15 M NaCl on 5HT DRN neuron firing was studied using single unit extracellular recordings. In separate groups of 2 M and 0.15 M NaCl-infused rats, water intake, oxytocin (OT) plasma concentration, urine and plasma sodium and protein concentrations were also measured. Also, to determine the involvement of particular brain nuclei and neurochemical systems in body sodium overload (SO), animals from both groups were perfused for brain immunohistochemical detection of Fos, Fos-OT and Fos-5HT expression. SO produced a significant increase in serotonergic DRN neuron firing rate compared to baseline and 0.15 M NaCl-infused rats. As expected, 2 M NaCl s.c. infusion also induced a significant increase of water intake, diuresis and natriuresis, plasma sodium concentration and osmolality, even though plasma volume did not increase as indicated by changes in plasma protein concentration. The distribution of neurons along the forebrain and brainstem expressing Fos after SO showed the participation of the lamina terminalis, extended amygdala, supraoptic and paraventricular hypothalamic nuclei in the neural network that controls osmoregulatory responses. Both Fos-OT immunoreactive and plasma OT concentration increased after s.c. hypertonic sodium infusion. Finally, matching the "in vivo" electrophysiological study, SO doubled the number of Fos-5HT immunolabeled cells within the DRN. In summary, the results characterize the behavioral, renal and endocrine responses after body sodium overload without volume expansion and specify the cerebral nuclei that participate at different CNS levels in the control of these responses. The electrophysiological approach also allows us to determine in an "in vivo" model that DRN 5HT neurons increase their firing frequency during an increase in systemic sodium concentration

  8. Perceived Dangerousness of Recreational Drugs.

    ERIC Educational Resources Information Center

    Luce, Terrence S.; Merrel, Judy C.

    1995-01-01

    In this study both college students and degreed nurses were asked to estimate the abuse potential and lethality of recreational drugs, both licit and illicit. Findings indicate that the illicit drugs under consideration were perceived as presenting the greatest danger to the user. Dangers attributed to the use of licit recreational drugs were…

  9. Fuel treatment effectiveness in reducing fire intensity and spread rate - An experimental overview

    Treesearch

    Eric Mueller; Nicholas Skowronski; Albert Simeoni; Kenneth Clark; Robert Kremens; William Mell; Michael Gallagher; Jan Thomas; Alexander Filkov; Mohamad El Houssami; John Hom; Bret Butler

    2014-01-01

    Fuel treatments represent a significant component of the wildfire mitigation strategy in the United States. However, the lack of research aimed at quantifying the explicit effectiveness of fuel treatments in reducing wildfire intensity and spread rate limits our ability to make educated decisions about the type and placement of these treatments. As part of a larger...

  10. Dangers of limited SDI

    SciTech Connect

    Marsh, G.E.

    1987-03-01

    Recent efforts to redefine the Strategic Defense Initiative (SDI) are mostly aimed at building support for a system to defend US land-based missiles. This is thought to be a more feasible goal than President Reagan's dream of an impregnable shield to defend the US population against ballistic missiles. But a feasible idea is not necessarily a good one. While chasing the population-defense fantasy would destroy the existing arms control regime and waste the national treasure of money and talent, defending land-based missiles would be dangerous and destabilizing. Defense Secretary Caspar Weinberger held fast to the idea of population defense in January, when he told the Senate Armed Services Committee that even early deployments of SDI systems that could be developed in the near future should be the first phase of a system that would protect the continent. But such statements may reflect the administration's determination to do away with the 1972 Anti-Ballistic Missile Treaty more than its belief that population defense is a reasonable goal. The author notes that, to those longstanding problems of defense decision making, they must now add the pressures of SDI. Furthermore, whatever the motives of those who advocate redirecting SDI, it is clear that concerns about the vulnerability of land-based missiles could be addressed in more sensible ways. 5 references.

  11. Drug dangers and reactions.

    PubMed

    WEILERSTEIN, R W

    1961-01-01

    The protection of the consumer against dangerous, adulterated, and misbranded drugs provided by the Federal Food, Drug, and Cosmetic Act has failed in some instances. A general program of reporting adverse drug reactions has been initiated on a pilot basis. Arrangements are being made to extend this program into larger hospitals. Better and more complete reporting of adverse drug reactions together with tightening of the Food and Drug law regarding new drugs will improve this situation. Recently the president of the National Academy of Sciences appointed a committee at the request of the Secretary of Health, Education, and Welfare to review the policies and procedures used by the Food and Drug Administration in reaching decisions and to present recommendations. This committee has completed its work and has made specific recommendations that would give the Food and Drug Administration authority to require proof of efficacy as well as safety of all new drugs, and would provide it with sufficient resources to meet the responsibilities assigned to it.

  12. DRUG DANGERS AND REACTIONS

    PubMed Central

    Weilerstein, Ralph W.

    1961-01-01

    The protection of the consumer against dangerous, adulterated, and misbranded drugs provided by the Federal Food, Drug, and Cosmetic Act has failed in some instances. A general program of reporting adverse drug reactions has been initiated on a pilot basis. Arrangements are being made to extend this program into larger hospitals. Better and more complete reporting of adverse drug reactions together with tightening of the Food and Drug law regarding new drugs will improve this situation. Recently the president of the National Academy of Sciences appointed a committee at the request of the Secretary of Health, Education, and Welfare to review the policies and procedures used by the Food and Drug Administration in reaching decisions and to present recommendations. This committee has completed its work and has made specific recommendations that would give the Food and Drug Administration authority to require proof of efficacy as well as safety of all new drugs, and would provide it with sufficient resources to meet the responsibilities assigned to it. PMID:13783849

  13. Introducing the Global Fire WEather Database (GFWED)

    NASA Astrophysics Data System (ADS)

    Field, R. D.

    2015-12-01

    The Canadian Fire Weather Index (FWI) System is the mostly widely used fire danger rating system in the world. We have developed a global database of daily FWI System calculations beginning in 1980 called the Global Fire WEather Database (GFWED) gridded to a spatial resolution of 0.5° latitude by 2/3° longitude. Input weather data were obtained from the NASA Modern Era Retrospective-Analysis for Research (MERRA), and two different estimates of daily precipitation from rain gauges over land. FWI System Drought Code calculations from the gridded datasets were compared to calculations from individual weather station data for a representative set of 48 stations in North, Central and South America, Europe, Russia, Southeast Asia and Australia. Agreement between gridded calculations and the station-based calculations tended to be most different at low latitudes for strictly MERRA-based calculations. Strong biases could be seen in either direction: MERRA DC over the Mato Grosso in Brazil reached unrealistically high values exceeding DC=1500 during the dry season but was too low over Southeast Asia during the dry season. These biases are consistent with those previously-identified in MERRA's precipitation and reinforce the need to consider alternative sources of precipitation data. GFWED is being used by researchers around the world for analyzing historical relationships between fire weather and fire activity at large scales, in identifying large-scale atmosphere-ocean controls on fire weather, and calibration of FWI-based fire prediction models. These applications will be discussed. More information on GFWED can be found at http://data.giss.nasa.gov/impacts/gfwed/

  14. The correlation between burn mortality rates from fire and flame and economic status of countries.

    PubMed

    Peck, Michael; Pressman, Melissa A

    2013-09-01

    Over 95% of burn deaths occur in low- and middle-income countries globally. However, the association between burn mortality rates and economic health has not been evaluated for individual countries. This study seeks to answer the question, how strong is the correlation between burn mortality and national indices of economic strength? A retrospective review was performed for 189 countries during 2008-2010 using economic data from the World Bank as well as mortality data from the World Health Organization (WHO). Countries were categorized into four groups based on income level according to stratification by the World Bank: low income, lower middle income, upper middle income, and high income. The Pearson correlation coefficient was used to estimate presence and strength of association among death rates, Gini coefficient (measure of inequality of distribution of wealth), gross domestic product (GDP) per capita, and gross national index (GNI) per capita. Statistically significant associations (p<0.05) were found between burn mortality and GDP per capita (r=-0.26), GNI per capita (r=-0.36), and Gini (r=+0.17). A nation's income level is negatively correlated with burn mortality; the lower the income level, the higher the burn mortality rates. The degree to which income within a country is equitably or inequitably distributed also correlates with burn mortality. Both governmental and non-governmental organizations need to focus on preventing burns in low-income countries, as well as in other countries in which there is marked disparity of income. Copyright © 2013 Elsevier Ltd and ISBI. All rights reserved.

  15. Simulated response of conterminous United States ecosystems to climate change at different levels of fire suppression, CO2 emission rate, and growth response to CO2

    Treesearch

    James M. Lenihan; Dominique Bachelet; Ronald P. Neilson; Raymond Drapek

    2008-01-01

    A modeling experiment was designed to investigate the impact of fire management, CO2 emission rate, and the growth response to CO2 on the response of ecosystems in the conterminous United States to climate scenarios produced by three different general circulation models (GCMs) as simulated by the MCl Dynamic General...

  16. Effects of Tail Clipping on Larval Performance and Tail Regeneration Rates in the Near Eastern Fire Salamander, Salamandra infraimmaculata.

    PubMed

    Segev, Ori; Polevikove, Antonina; Blank, Lior; Goedbloed, Daniel; Küpfer, Eliane; Gershberg, Anna; Koplovich, Avi; Blaustein, Leon

    2015-01-01

    Tail-tip clipping is a common technique for collecting tissue samples from amphibian larvae and adults. Surprisingly, studies of this invasive sampling procedure or of natural tail clipping--i.e., bites inflicted by predators including conspecifics--on the performance and fitness of aquatic larval stages of urodeles are scarce. We conducted two studies in which we assessed the effects of posterior tail clipping (~30 percent of tail) on Near Eastern fire salamander (Salamandra infraimmaculata) larvae. In a laboratory study, we checked regeneration rates of posterior tail-tip clipping at different ages. Regeneration rates were hump-shaped, peaking at the age of ~30 days and then decreasing. This variation in tail regeneration rates suggests tradeoffs in resource allocation between regeneration and somatic growth during early and advanced development. In an outdoor artificial pond experiment, under constant larval densities, we assessed how tail clipping of newborn larvae affects survival to, time to, and size at metamorphosis. Repeated measures ANOVA on mean larval survival per pond revealed no effect of tail clipping. Tail clipping had correspondingly no effect on larval growth and development expressed in size (mass and snout-vent length) at, and time to, metamorphosis. We conclude that despite the given variation in tail regeneration rates throughout larval ontogeny, clipping of 30% percent of the posterior tail area seems to have no adverse effects on larval fitness and survival. We suggest that future use of this imperative tool for the study of amphibian should take into account larval developmental stage during the time of application and not just the relative size of the clipped tail sample.

  17. Effects of Tail Clipping on Larval Performance and Tail Regeneration Rates in the Near Eastern Fire Salamander, Salamandra infraimmaculata

    PubMed Central

    Segev, Ori; Polevikove, Antonina; Blank, Lior; Goedbloed, Daniel; Küpfer, Eliane; Gershberg, Anna; Koplovich, Avi; Blaustein, Leon

    2015-01-01

    Tail-tip clipping is a common technique for collecting tissue samples from amphibian larvae and adults. Surprisingly, studies of this invasive sampling procedure or of natural tail clipping – i.e., bites inflicted by predators including conspecifics - on the performance and fitness of aquatic larval stages of urodeles are scarce. We conducted two studies in which we assessed the effects of posterior tail clipping (~30 percent of tail) on Near Eastern fire salamander (Salamandra infraimmaculata) larvae. In a laboratory study, we checked regeneration rates of posterior tail-tip clipping at different ages. Regeneration rates were hump-shaped, peaking at the age of ~30 days and then decreasing. This variation in tail regeneration rates suggests tradeoffs in resource allocation between regeneration and somatic growth during early and advanced development. In an outdoor artificial pond experiment, under constant larval densities, we assessed how tail clipping of newborn larvae affects survival to, time to, and size at metamorphosis. Repeated measures ANOVA on mean larval survival per pond revealed no effect of tail clipping. Tail clipping had correspondingly no effect on larval growth and development expressed in size (mass and snout-vent length) at, and time to, metamorphosis. We conclude that despite the given variation in tail regeneration rates throughout larval ontogeny, clipping of 30% percent of the posterior tail area seems to have no adverse effects on larval fitness and survival. We suggest that future use of this imperative tool for the study of amphibian should take into account larval developmental stage during the time of application and not just the relative size of the clipped tail sample. PMID:26065683

  18. Fire and smoke retardants

    NASA Astrophysics Data System (ADS)

    Drews, M. J.

    Despite a reduction in Federal regulatory activity, research concerned with flame retardancy and smoke suppression in the private sector appears to be increasing. This trend seem related to the increased utilization of plastics for end uses which traditionally have employed metal or wood products. As a result, new markets have appeared for thermally stable and fire resistance thermoplastic materials, and this in turn has spurred research and development activity. In addition, public awareness of the dangers associated with fire has increased as a result of several highly publicized hotel and restaurant fires within the past two years. The consumers recognition of flammability characteristics as important materials property considerations has increased. The current status of fire and smoke retardant chemistry and research are summarized.

  19. Smog O3 Production Rate in California Air: Marker Compounds Allow Checks on Source Attribution to Fire and Other Sources

    NASA Astrophysics Data System (ADS)

    Chatfield, R. B.; Esswein, R. F.; Cai, C.; Kaduwela, A.; Kulkarni, S.; Blake, D. R.; Weinheimer, A. J.; Fried, A.; Huey, L. G.

    2012-12-01

    We are able to attribute sources of both radical reactivity and NO that determined the smog-chemical production rate of ozone, P(O3), for NASA's wide-ranging sampling of California air in June, 2008, part of the ARCTAS intensive. We relate formaldehyde, HCHO, and reactive nitrogen oxides, NOx, to a variety of distinct "marker" species that identify origins. We have labeled the sources and markers as (i) Fire emissions (CH3CN), (ii) Biogenic emissions (Isoprene), (iii) Urban/business emissions (CHCl3), (iv) Transport-related fuel consumption, (SO2), and (v) Refining/Port emissions ("residual" toluene). We use multiple linear regression with some appropriate restrictions. We achieve R-squared or explained variance of 88% for HCHO (VOC's) and 60% for NOx. HCHO and NOx are slowly evolving measures of potential ozone generation. The two related but radiation-influenced measures j (HCHO->H+HCO) x [HCHO] and [NO] quantitatively, but non-linearly, relate to instantaneous ozone production in California air, with R-squared of 86-93%, just as in New York City (Chatfield et al., Atmos. Environ., 2010). Maps of attribution for 650 samples from the Port of San Diego to the Northern Sierra foothills, and offshore -— all show huge variability in source attributions for VOCs and NOx. They indicate a widespread fire-emission influence on VOCs as they produce peroxy radicals, but show no positive influence on NOx, in fact consuming NOx from other sources. Comparisons with simulations help to refine our attribution classes and also to check balances of VOC emissions in available inventories. The use of the P(O3) measures is directly translatable to a method for estimate smog-ozone production rate from space, as data from another intensive, DISCOVER-AQ, show. (Left) A rare example where all sources contribute significantly, with markers and tentative attributions marked. (Right) Three different situations describing the control of smog ozone production, all from the same geographic

  20. SENSOR FOR INDIVIDUAL BURNER CONTROL OF FIRING RATE, FUEL-AIR RATIO, AND COAL FINENESS CORRELATION

    SciTech Connect

    Wayne Hill; Roger Demler; Robert G. Mudry

    2005-04-01

    A no-cost time extension was requested, to permit additional laboratory testing prior to undertaking field data collection. This was received in this reporting period. To minimize program cost, this additional testing is planned to be performed in concert with EPRI-funded testing at the Coal Flow Test Facility. Since the EPRI schedule was undecided, a hiatus occurred in the test effort. Instead, a significant effort was exerted to analyze the available laboratory test data to see whether the source and nature of noise behaviors could be identified, or whether the key flow information could be extracted even in the presence of the noise. One analysis approach involved filtering the data numerically to reject dynamics outside of various frequency bands. By varying the center frequency and width of the band, the effect of signal frequency on flow dynamics could be examined. Essentially equivalent results were obtained for all frequency bands that excluded a neighborhood of the transducer resonance, indicating that there is little advantage to be gained by limiting the experimental frequency window. Another approach examined the variation of the dynamics over a series of 1-second windows of data, producing an improvement in the prediction of coal flow rate. Yet another approach compared the dynamics of a series of 1-second windows to those of a series of 5-second windows, producing still better results. These results will be developed further in the next reporting period, which should also include further laboratory testing at the Coal Flow Test Facility.

  1. SENSOR FOR INDIVIDUAL BURNER CONTROL OF FIRING RATE, FUEL-AIR RATIO, AND COAL FINENESS CORRELATION

    SciTech Connect

    Wayne Hill; Roger Demler; Robert G. Mudry

    2005-01-01

    Additional calibration data were collected in the Coal Flow Test Facility early in this reporting period. These data comprised a total of 181 tests for stud and magnetic accelerometer mounts, with two mounting locations relative to two different pipe elbows, and including some tests with out-of-plane elbows upstream of the test section to produce coal ''roping''. The results found in analyzing these new data were somewhat disappointing: correlations for coal flow rate for a given mount type and mounting location were less accurate than desired, and degraded badly when data from other locations were included in the same analysis. Reviewing all of the data files (from both the earlier testing and recent calibration testing) disclosed a significant fraction of cases with several forms of noise. Eliminating these cases improved the correlations somewhat, but the number of cases that remained did not permit general conclusions to be drawn. It was finally learned that yet another type of noise is present in some data files, producing a strong effect on the correlation accuracy. The cases not subject to this noise correlated very well. It would be desirable to collect additional data in the Coal Flow Test Facility prior to moving on to field data collection, a change in program direction that would require a no-cost time extension.

  2. [Radioecological approaches to ranking radiation dangerous objects].

    PubMed

    Korenkov, I P; Lashchenova, T N; Veselov, E I; Shandala, N K; Maksimova, O A

    2011-01-01

    The paper gives complex criteria for evaluating the hazard of radiation dangerous objects (RDO). The proposed criteria include the following indicators: the ratio of the cumulative activity of radioactive waste to a hazard factor (D value) or to the allowable level of i-radionuclide in the storage; the power of an effective gamma-radiation dose; the rate of radionuclide migration; the doses of human radiation. A scoring system for the hazard of RDO from the above indicators is given.

  3. Dangers of Texting While Driving

    MedlinePlus

    ... Dangers of Distracted Driving Español The popularity of mobile devices has had some unintended and sometimes deadly consequences. ... linked to driving while distracted, including use of mobile devices while driving, resulting in injury and loss of ...

  4. Hidden danger of button batteries.

    PubMed

    Taghavi, Kiarash; Hobson, Andrew; Borzi, Peter

    2015-06-01

    This case highlights a rare but important presentation of aorto-oesophageal fistula caused by a concealed foreign body. Primary prevention strategies are needed to address the danger associated with button batteries.

  5. 49 CFR 172.521 - DANGEROUS placard.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS HAZARDOUS MATERIALS TABLE, SPECIAL... SECURITY PLANS Placarding § 172.521 DANGEROUS placard. (a) Except for size and color, the DANGEROUS...

  6. 49 CFR 172.521 - DANGEROUS placard.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS HAZARDOUS MATERIALS TABLE, SPECIAL... SECURITY PLANS Placarding § 172.521 DANGEROUS placard. (a) Except for size and color, the DANGEROUS...

  7. 49 CFR 172.521 - DANGEROUS placard.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS HAZARDOUS MATERIALS TABLE, SPECIAL... SECURITY PLANS Placarding § 172.521 DANGEROUS placard. (a) Except for size and color, the DANGEROUS...

  8. A short-term predictor of satellite-observed fire activity in the North American boreal forest: Toward improving the prediction of smoke emissions

    NASA Astrophysics Data System (ADS)

    Peterson, David; Hyer, Edward; Wang, Jun

    2013-06-01

    A statistical model, based on numerical weather prediction (NWP), is developed to predict the subsequent day's satellite observations of fire activity in the North American boreal forest during the fire season (24-h forecast). In conjunction with the six components of the Canadian Forest Fire Danger Rating System and other NWP outputs, fire data from the MODerate Resolution Imaging Spectroradiometer (MODIS) and the Geostationary Operational Environmental Satellites (GOES) are used to examine the meteorological separability between the largest fire growth and decay events, with a focus on central Alaska during the large fire season of 2004. This combined information is analyzed in three steps including a maximum likelihood classification, multiple regression, and empirical correction, from which the meteorological effects on fire growth and decay are statistically established to construct the fire prediction model. Both MODIS and GOES fire observations show that the NWP-based fire prediction model is an improvement over the forecast of persistence commonly used by near-real-time fire emission inventories. Results from an independent test (2005 fire season) show that the root-mean-square error (RMSE) of predicted MODIS fire observations is reduced by 5.2% compared with a persistence forecast. Improvements are strongest (RMSE reduction of 11.4%) for cases with observed decay or extinction of fires. Similar results are obtained from additional independent tests using the 2004 and 2005 GOES satellite fire observations. This study uniquely demonstrates the value and importance of combining NWP data and satellite fire observations to predict biomass-burning emissions, which is a critical step toward producing a global short-term fire prediction model and improving operational forecasts of smoke transport at large spatial scales.

  9. A patient with intraoral fire during tonsillectomy.

    PubMed

    Partanen, Esa; Koljonen, Virve; Salonen, Aarre; Bäck, Leif J J; Vuola, Jyrki

    2014-09-01

    Perioperative fires inside the mouth can have long-lasting sequelae. They are potentially dangerous both to the patient and to the operation room staff as well. Herein, we present a flash fire in the oropharynx, secondary to electrosurgery during a tonsillectomy operation in a young child. Despite a potentially devastating situation, the patient recovered well within just a week following intraoral burn injuries, and the initially interrupted tonsillectomy operation was completed without complications. The dangerous situations leading to fire hazards and the prevention measures are discussed.

  10. Remote sensing techniques for vegetation moisture and fire risk estimation

    NASA Astrophysics Data System (ADS)

    Dasgupta, Swarvanu

    This dissertation is aimed at evaluating and improving remote sensing techniques for vegetation moisture and fire risk estimation. Empirical retrievals of vegetation moisture using liquid water absorption based spectral indices such as the NDWI (Normalized Difference Water Index) and NDII (Normalized Difference Infrared Index) may have uncertainties, since these indices cannot fully normalize the reflectance variability due to other biophysical, biochemical, soil and illumination viewing geometry factors. Coupled leaf-canopy reflectance models, National Fire Danger Rating System data and the FARSITE fire behavior model were used to estimate the effect of Live Fuel Moisture Content (LFMC) retrieval uncertainties on fire spread rate predictions. The uncertainty estimation was focused on the Okefenokee National Wildlife Refuge where errors in LFMC retrievals using NDWI and NDII were shown to result in considerable fire spread rate prediction errors at lower LFMC levels. Soil reflectance contamination driven by soil moisture variability was identified as a problem causing errors in Vegetation Water Content (VWC) retrievals over low vegetation conditions. Analysis of canopy reflectance simulations from coupled soil-leaf-canopy reflectance models revealed that VWC isolines were curved and did not converge at the origin of the 1.64mum--0.86mum space. These were identified as causes for the soil moisture contamination of the spectral index NDII. As an improvement strategy an origin transformed NDII, called the SANDII (Soil Adjusted NDII) was designed to minimize soil contamination. Further separate regression models between VWC and the SANDII for different soil moisture classes were proposed to account for the curved nature of VWC isolines. The new technique which requires categorical soil moisture information was shown to reduce VWC estimation errors by about 20% over grassland conditions. The approach was supported using data collected over pastures during the Soil

  11. A Mega-fire event in Central Russia: fire weather, radiative, and optical properties of the atmosphere, and consequences for subboreal forest plants

    Treesearch

    Nataly Y. Chubarova; Nickolay G. Prilepsky; Alexei N. Rublev; Allen R. Riebau

    2009-01-01

    In 2002, a major drought and prolonged high temperatures occurred in central Russia that resulted in unprecedented wildland fires. These fires occurred under extreme fire danger conditions and were impossible for the Russian authorities to extinguish. It is perhaps somewhat unique that the fires were first burning peat bogs and later forests, causing very massive smoke...

  12. Winds, Mountains, and Wildland Fire: Improved Understanding of Coupled Atmosphere-Topography-Fire Interactions Through Large-Eddy Simulation

    NASA Astrophysics Data System (ADS)

    Munoz-Esparza, D.; Sauer, J.; Linn, R.

    2015-12-01

    Anomalous and unexpected fire behavior in complex terrain continues to result in substantial loss of property and extremely dangerous conditions for firefighting field personnel. We briefly discuss proposed hypotheses of fire interactions with atmospheric flows over complex terrain that can lead to poorly-understood and potentially catastrophic scenarios. Then, our recent results of numerical investigations via large-eddy simulation of coupled atmosphere-topography-fire phenomenology with the Los Alamos National Laboratory, HiGrad-Firetec model are presented as an example of the potential for increased understanding of these complex processes. This investigation focuses on the influence of downslope surface wind enhancement through stably stratified flow over an isolated hill, and the resulting dramatic changes in fire behavior including spread rate, and intensity. Implications with respect to counter-intuitive fire behavior and extreme fire events are discussed. This work demonstrates a tremendous opportunity to immediately create safer and more effective policy for field personnel through improved predictability of atmospheric conditions over complex terrain

  13. Negativity Bias in Dangerous Drivers

    PubMed Central

    Chai, Jing; Qu, Weina; Sun, Xianghong; Zhang, Kan; Ge, Yan

    2016-01-01

    The behavioral and cognitive characteristics of dangerous drivers differ significantly from those of safe drivers. However, differences in emotional information processing have seldom been investigated. Previous studies have revealed that drivers with higher anger/anxiety trait scores are more likely to be involved in crashes and that individuals with higher anger traits exhibit stronger negativity biases when processing emotions compared with control groups. However, researchers have not explored the relationship between emotional information processing and driving behavior. In this study, we examined the emotional information processing differences between dangerous drivers and safe drivers. Thirty-eight non-professional drivers were divided into two groups according to the penalty points that they had accrued for traffic violations: 15 drivers with 6 or more points were included in the dangerous driver group, and 23 drivers with 3 or fewer points were included in the safe driver group. The emotional Stroop task was used to measure negativity biases, and both behavioral and electroencephalograph data were recorded. The behavioral results revealed stronger negativity biases in the dangerous drivers than in the safe drivers. The bias score was correlated with self-reported dangerous driving behavior. Drivers with strong negativity biases reported having been involved in mores crashes compared with the less-biased drivers. The event-related potentials (ERPs) revealed that the dangerous drivers exhibited reduced P3 components when responding to negative stimuli, suggesting decreased inhibitory control of information that is task-irrelevant but emotionally salient. The influence of negativity bias provides one possible explanation of the effects of individual differences on dangerous driving behavior and traffic crashes. PMID:26765225

  14. Forecasting distribution of numbers of large fires

    USGS Publications Warehouse

    Eidenshink, Jeffery C.; Preisler, Haiganoush K.; Howard, Stephen; Burgan, Robert E.

    2014-01-01

    Systems to estimate forest fire potential commonly utilize one or more indexes that relate to expected fire behavior; however they indicate neither the chance that a large fire will occur, nor the expected number of large fires. That is, they do not quantify the probabilistic nature of fire danger. In this work we use large fire occurrence information from the Monitoring Trends in Burn Severity project, and satellite and surface observations of fuel conditions in the form of the Fire Potential Index, to estimate two aspects of fire danger: 1) the probability that a 1 acre ignition will result in a 100+ acre fire, and 2) the probabilities of having at least 1, 2, 3, or 4 large fires within a Predictive Services Area in the forthcoming week. These statistical processes are the main thrust of the paper and are used to produce two daily national forecasts that are available from the U.S. Geological Survey, Earth Resources Observation and Science Center and via the Wildland Fire Assessment System. A validation study of our forecasts for the 2013 fire season demonstrated good agreement between observed and forecasted values.

  15. Continental-scale simulation of burn probabilities, flame lengths, and fire size distribution for the United States

    Treesearch

    Mark A. Finney; Charles W. McHugh; Isaac Grenfell; Karin L. Riley

    2010-01-01

    Components of a quantitative risk assessment were produced by simulation of burn probabilities and fire behavior variation for 134 fire planning units (FPUs) across the continental U.S. The system uses fire growth simulation of ignitions modeled from relationships between large fire occurrence and the fire danger index Energy Release Component (ERC). Simulations of 10,...

  16. Modelling the Meteorological Forest Fire Niche in Heterogeneous Pyrologic Conditions

    PubMed Central

    De Angelis, Antonella; Ricotta, Carlo; Conedera, Marco; Pezzatti, Gianni Boris

    2015-01-01

    Fire regimes are strongly related to weather conditions that directly and indirectly influence fire ignition and propagation. Identifying the most important meteorological fire drivers is thus fundamental for daily fire risk forecasting. In this context, several fire weather indices have been developed focussing mainly on fire-related local weather conditions and fuel characteristics. The specificity of the conditions for which fire danger indices are developed makes its direct transfer and applicability problematic in different areas or with other fuel types. In this paper we used the low-to-intermediate fire-prone region of Canton Ticino as a case study to develop a new daily fire danger index by implementing a niche modelling approach (Maxent). In order to identify the most suitable weather conditions for fires, different combinations of input variables were tested (meteorological variables, existing fire danger indices or a combination of both). Our findings demonstrate that such combinations of input variables increase the predictive power of the resulting index and surprisingly even using meteorological variables only allows similar or better performances than using the complex Canadian Fire Weather Index (FWI). Furthermore, the niche modelling approach based on Maxent resulted in slightly improved model performance and in a reduced number of selected variables with respect to the classical logistic approach. Factors influencing final model robustness were the number of fire events considered and the specificity of the meteorological conditions leading to fire ignition. PMID:25679957

  17. Modelling the meteorological forest fire niche in heterogeneous pyrologic conditions.

    PubMed

    De Angelis, Antonella; Ricotta, Carlo; Conedera, Marco; Pezzatti, Gianni Boris

    2015-01-01

    Fire regimes are strongly related to weather conditions that directly and indirectly influence fire ignition and propagation. Identifying the most important meteorological fire drivers is thus fundamental for daily fire risk forecasting. In this context, several fire weather indices have been developed focussing mainly on fire-related local weather conditions and fuel characteristics. The specificity of the conditions for which fire danger indices are developed makes its direct transfer and applicability problematic in different areas or with other fuel types. In this paper we used the low-to-intermediate fire-prone region of Canton Ticino as a case study to develop a new daily fire danger index by implementing a niche modelling approach (Maxent). In order to identify the most suitable weather conditions for fires, different combinations of input variables were tested (meteorological variables, existing fire danger indices or a combination of both). Our findings demonstrate that such combinations of input variables increase the predictive power of the resulting index and surprisingly even using meteorological variables only allows similar or better performances than using the complex Canadian Fire Weather Index (FWI). Furthermore, the niche modelling approach based on Maxent resulted in slightly improved model performance and in a reduced number of selected variables with respect to the classical logistic approach. Factors influencing final model robustness were the number of fire events considered and the specificity of the meteorological conditions leading to fire ignition.

  18. Star Formation Rate Indicators in the FIRE Simulations & SPT 2349-56: A Massive and Active Proto-Cluster Core

    NASA Astrophysics Data System (ADS)

    Miller, Timothy B.

    2017-07-01

    When studying galaxies, the star formation rate (SFR) is an important diagnostic as it gives insight into the evolutionary stage of the galaxy. Young galaxies will be actively forming stars and growing quickly, while older, quiescent galaxies will have low SFRs. The total infrared (IR) luminosity of a galaxy is a commonly used tracer of SFR. A simple radiative transfer model to estimate the IR luminosity of hydrodynamic simulations of galaxies is presented. This algorithm is then applied to the feedback in realistic environments (FIRE) simulation suite. The IR luminosity is then compared directly to the SFR, which is known in the simulations. These results are compared to a well established model. The model is found to have a bias that systematically overestimates the SFR of a galaxy. A large amount of scatter also cautions against the interpretations of observations from this simple model. The most massive galaxies formed quickly in the early Universe and today reside in rich galaxy clusters. Studying progenitors of galaxy clusters (proto-clusters) presents an exciting opportunity to study star formation in extreme environments in the early universe. High resolution sub-mm imaging of the proto-cluster SPT 2349-56 is presented. SPT 2349-56 contains 12 gas rich and star forming galaxies in an extremely confined radius of ∼12''. The high velocity dispersion of these galaxies and enormous gas and star formation densities suggest SPT 2349-56 represents the core of an especially active and massive proto-cluster. Comparison with other known proto-cluster systems shows that SPT 2349-56 is truly unique.

  19. Main Dangers of Our Times.

    NASA Astrophysics Data System (ADS)

    Synek, Miroslav

    2003-03-01

    Terrorism and threatening dictatorships are the main, man-made, dangers of our times. They are run by master demagogues, or, brain-washing manipulators. ----- Our next step in coping with terrorism is to counter master demagoguery. Therefore, supporting EDUCATION that would emphasize the most unifying (and the least controversial), yet, BASIC CIVIC RESPECT for lives of people in a civilian human society, is a priority everywhere on our planet. ----- At the same time we start facing mostly small, threatening, dictatorships, capable of producing weapons of mass destruction. Therefore, we have to try to contribute to developing systems of FREE ELECTIONS, controlling weapons of mass destruction, wherever such dangers exist. ----- In a foreseeable future, unfortunately, we are facing a danger even by orders of magnitude greater. We are facing a possibility of a mass-produced heavy accumulation of inter-continental nuclear missiles, on a computerized "push-button" control, by a very powerful (and, quite possibly, miscalculating, or, suicidal) dictator, dangerous to the very existence of humanity on our planet. Therefore, it is a historical urgency that such a technological power be under the control by a government of the people, by the people and for the people, based on a sufficiently reliable system of FREE ELECTIONS, wherever, on our planet, such a potential danger may originate.

  20. Fire Resistant, Moisture Barrier Membrane

    NASA Technical Reports Server (NTRS)

    St.Clair, Terry L. (Inventor)

    1998-01-01

    A waterproof and breathable, fire-resistant laminate is provided for use in tents, garments, shoes, and covers, especially in industrial, military and emergency situations. The laminate permits water vapor evaporation while simultaneously preventing liquid water penetration. Further, the laminate is fire-resistant and significantly reduces the danger of toxic compound production when exposed to flame or other high heat source. The laminate may be applied to a variety of substrates and is comprised of a silicone rubber and plurality of fire-resistant, inherently thermally-stable polyimide particles.

  1. Fire Resistant, Moisture Barrier Membrane

    NASA Technical Reports Server (NTRS)

    St.Clair, Terry L. (Inventor)

    2000-01-01

    A waterproof and breathable, fire-resistant laminate is provided for use in tents, garments, shoes, and covers, especially in industrial, military and emergency situations. The laminate permits water vapor evaporation while simultaneously preventing liquid water penetration. Further, the laminate is fire-resistant and significantly reduces the danger of toxic compound production when exposed to flame or other high heat source. The laminate may be applied to a variety of substrates and is comprised of a silicone rubber and plurality of fire-resistant, inherently thermally-stable polyimide particles.

  2. The dangerous decade.

    PubMed

    Coiera, Enrico; Aarts, Jos; Kulikowski, Casimir

    2012-01-01

    Over the next 10 years, more information and communication technology (ICT) will be deployed in the health system than in its entire previous history. Systems will be larger in scope, more complex, and move from regional to national and supranational scale. Yet we are at roughly the same place the aviation industry was in the 1950s with respect to system safety. Even if ICT harm rates do not increase, increased ICT use will increase the absolute number of ICT related harms. Factors that could diminish ICT harm include adoption of common standards, technology maturity, better system development, testing, implementation and end user training. Factors that will increase harm rates include complexity and heterogeneity of systems and their interfaces, rapid implementation and poor training of users. Mitigating these harms will not be easy, as organizational inertia is likely to generate a hysteresis-like lag, where the paths to increase and decrease harm are not identical.

  3. The dangerous decade

    PubMed Central

    Aarts, Jos; Kulikowski, Casimir

    2011-01-01

    Over the next 10 years, more information and communication technology (ICT) will be deployed in the health system than in its entire previous history. Systems will be larger in scope, more complex, and move from regional to national and supranational scale. Yet we are at roughly the same place the aviation industry was in the 1950s with respect to system safety. Even if ICT harm rates do not increase, increased ICT use will increase the absolute number of ICT related harms. Factors that could diminish ICT harm include adoption of common standards, technology maturity, better system development, testing, implementation and end user training. Factors that will increase harm rates include complexity and heterogeneity of systems and their interfaces, rapid implementation and poor training of users. Mitigating these harms will not be easy, as organizational inertia is likely to generate a hysteresis-like lag, where the paths to increase and decrease harm are not identical. PMID:22116642

  4. The correlated blanching of synaptic bodies and reduction in afferent firing rates caused by transmitter-depleting agents in the frog semicircular canal

    NASA Technical Reports Server (NTRS)

    Guth, P.; Norris, C.; Fermin, C. D.; Pantoja, M.

    1993-01-01

    Synaptic bodies (SBs) associated with rings of synaptic vesicles and well-defined, pre- and post-synaptic membrane structures are indicators of maturity in most hair cell-afferent nerve junctions. The role of the SBs remains elusive despite several experiments showing that they may be involved in storage of neurotransmitter. Our results demonstrate that SBs of the adult posterior semicircular canal (SCC) cristae hair cells become less electron dense following incubation of the SCC with the transmitter-depleting drug tetrabenazine (TBZ). Objective quantification and comparison of the densities of the SBs in untreated and TBZ-treated frog SCC demonstrated that TBZ significantly decreased the electron density of SBs. This reduction in electron density was accompanied by a reduction in firing rates of afferent fibers innervating the posterior SCC. A second transmitter-depleting drug, guanethidine, previously shown to reduce the electron density of hair cell SBs, also reduced the firing rates of afferent fibers innervating the posterior SCC. In contrast, the electron density of dense granules (DG), similar in size and shape to synaptic bodies (SB) in hair cells, did not change after incubation in TBZ, thus indicating that granules and SBs are not similar in regard to their electron density. The role of SBs in synaptic transmission and the transmitter, if any, stored in the SBs remain unknown. Nonetheless, the association of the lessening of electron density with a reduction in afferent firing rate provides impetus for the further investigation of the SB's role in neurotransmission.

  5. Carbon dioxide dangers demonstration model

    USGS Publications Warehouse

    Venezky, Dina; Wessells, Stephen

    2010-01-01

    Carbon dioxide is a dangerous volcanic gas. When carbon dioxide seeps from the ground, it normally mixes with the air and dissipates rapidly. However, because carbon dioxide gas is heavier than air, it can collect in snowbanks, depressions, and poorly ventilated enclosures posing a potential danger to people and other living things. In this experiment we show how carbon dioxide gas displaces oxygen as it collects in low-lying areas. When carbon dioxide, created by mixing vinegar and baking soda, is added to a bowl with candles of different heights, the flames are extinguished as if by magic.

  6. Impacts of changing fire weather conditions on reconstructed trends in U.S. wildland fire activity from 1979 to 2014

    NASA Astrophysics Data System (ADS)

    Freeborn, Patrick H.; Jolly, W. Matt; Cochrane, Mark A.

    2016-11-01

    One component of climate-fire interactions is the relationship between weather conditions concurrent with burning (i.e., fire danger) and the magnitude of fire activity. Here daily environmental conditions are associated with daily observations of fire activity within ecoregions across the continental United States (CONUS) by aligning the latter 12 years of a 36 year gridded fire danger climatology with the Moderate Resolution Imaging Spectroradiometer fire products. Results reveal that although modern relationships (2003-2014) vary regionally, fires across the majority of CONUS are more likely to be present and burning more vigorously as fire danger increases. Applying modern relationships to the entire climatology (1979-2014) indicates that in the absence of other influences, changes in fire danger have significantly increased the number of days per year that fires are burning across 42-49% of CONUS (by area) while also significantly increasing daily fire growth and daily heat release across 37-45% of CONUS. Increases in the fire activity season length coupled with an intensification of daily burning characteristics resulted in a CONUS-wide +0.02 Mha yr-1 trend in burned area, a 10.6 g m-2 yr-1 trend in the amount of fuel consumed per unit burned area, and ultimately a +0.51 Tg yr-1 trend in dry matter consumption. Overall, the results demonstrate regional variations in the response of fires to changes in fire danger and that weather conditions concurrent with burning have a three-pronged impact on the magnitude of fire activity by affecting the seasonal duration, spatial extent, and combustion intensity.

  7. [Accidents on Iceland's most dangerous roads].

    PubMed

    Bjarnason, Thóroddur; Arnarsson, Sveinn

    2012-02-01

    The objective of this paper was to identify the most dangerous segments of the Icelandic road system in terms of the number of accidents pr km and the rate of accidents pr million km travelled. First to identify the segments where the number of accidents is highest and where the risk of the individual traveller is the greatest. Second to evaluate if the association between the number and the rate of accidents is positive or negative. Third to identify the road segments that are the most dangerous in the sense of many accidents and great risk to individual travellers. Main roads outside urban centers were divided into 45 segments that were on average 78 km in length. Infrequently travelled roads and roads within urban centers were omitted. Information on the length of roads, traffic density and number of accidents was used to calculate the number of accidents per km and the rate of accidents per million km travelled. The correlation between the number and rate of accidents was calculated and the most dangerous road segments were identified by the average rank order on both dimensions. Most accidents pr km occurred on the main roads to and from the capital region, but also east towards Hvolsvöllur, north towards Akureyri and in the Mideast region of the country. The rate of accidents pr million km travelled was highest in the northeast region, in northern Snæfellsnes and in the Westfjords. The most dangerous roads on both dimensions were in Mideast, northern Westfjords, in the north between Blönduós and Akureyri and in northern Snæfellsnes. Most accidents pr km occurred on roads with a low accident rate pr million km travelled. It is therefore possible to reduce accidents the most by increasing road safety where it is already the greatest but that would however increase inequalities in road safety. Policy development in transportation is therefore in part a question of priorities in healthcare. Individual equality in safety and health are not always fully

  8. Forest fire weather and computed fire occurrence in western Oregon and western Washington.

    Treesearch

    Owen P. Cramer

    1959-01-01

    Severity of the 1959 fire season varied from well below normal in western Washington to a record-setting high in southwestern Oregon. The season was characterized by well-distributed, short rainy periods separated by comparatively short dry spells that frequently included days of high fire danger. July was the only month with markedly above-normal temperatures, and...

  9. Use of expert knowledge to develop fuel maps for wildland fire management [chapter 11

    Treesearch

    Robert E. Keane; Matt Reeves

    2012-01-01

    Fuel maps are becoming an essential tool in fire management because they describe, in a spatial context, the one factor that fire managers can control over many scales ­ surface and canopy fuel characteristics. Coarse-resolution fuel maps are useful in global, national, and regional fire danger assessments because they help fire managers effectively plan, allocate, and...

  10. Playing with fire: images of fire on toy packaging.

    PubMed

    Curri, Terese B; Palmieri, Tina L; Aoki, Traci H; Kaulkin, Camille K; Lunn, Melen E; Gregory, Catherine M; Greenhalgh, David G

    2003-01-01

    Despite prevention efforts designed to teach children that fire is not a toy, each year hundreds of children, primarily male, are injured while playing with fire. Mass-produced toys and games shape children's behaviors, and the fire images on toy packaging may send the message that fire is fun rather than dangerous. The purpose of this study was to determine the frequency of male fire-related injuries at our burn center and to investigate the use of fire images in toy packaging. An aisle-by-aisle search was conducted at a national toy store. Toys with fire images on their packaging were identified. Target gender and the setting in which the fire was displayed also were recorded. Only toys with clearly visible flames on their packaging were included. We reviewed our TRACS database from April 1997 to May 1999 for fire-related injuries to children admitted to our institution as a result of playing with fire. Review of toy stores revealed 404 toys with packaging containing fire images. Of these, 97% (393 of 404) were targeted to males. Video games were the leading category of flame-related packaging (208 of 404), followed by toy car/truck displays (84 of 404). Packaging for girls' toys had safe and contained settings, whereas boys' toys used settings that were uncontrolled and associated with speed and weapons. A total of 59 children, 52 males and 7 females, with a mean age of 10 +/- 0.6 years and mean TBSA burn of 12.3 +/- 2.1% were admitted to our facility with fire-related injuries during the study interval. Children imitate life with toys and use play to experiment with new behavior. Boys are receiving a powerful, consistent message from images of fire on toy packaging. These advertisements may help to contribute to the higher incidence of fire-related injuries in boys.

  11. Activity patterns and parasitism rates of fire ant decapitating flies (Diptera:Phoridae:Pseudacteon spp.) in their native Argentina

    USDA-ARS?s Scientific Manuscript database

    Technical Abstract: This work describes the annual and daily activity patterns of two parasitoid fly communities of the fire ant S. invicta (Hymenoptera: Formicidae) in their native Argentina. Pseudacteon (Diptera: Phoridae) flies were censused monthly for one year at two sites in northwestern Corr...

  12. Quiet Danger in Chemistry Lab.

    ERIC Educational Resources Information Center

    Swami, Piyush; Singh, Karan

    1985-01-01

    Indicates that the most dangerous laboratory hazards are the least dramatic ones and that hazardous chemicals are often used in laboratories without proper precautions. Selected sources of information essential for secondary schools and recommendations for safe practices and chemical use statistics from a study of Ohio high schools are given. (DH)

  13. Students' Ideas about Dangerous Animals

    ERIC Educational Resources Information Center

    Cardak, Osman

    2009-01-01

    The aim of this article was to study the concepts and thoughts of primary education students about dangerous animals. A total of 316 primary education students attending a primary school in Turkey participated in the study. The research data was obtained through open-ended questions and word association tests. Data obtained from the questions…

  14. Students' Ideas about Dangerous Animals

    ERIC Educational Resources Information Center

    Cardak, Osman

    2009-01-01

    The aim of this article was to study the concepts and thoughts of primary education students about dangerous animals. A total of 316 primary education students attending a primary school in Turkey participated in the study. The research data was obtained through open-ended questions and word association tests. Data obtained from the questions…

  15. A neural network based optimization system provides on-line coal fired furnace air flow balancing for heat rate improvement and NO{sub x} reduction

    SciTech Connect

    Radl, B.J.; Roland, W. Jr.

    1995-12-31

    The optimization system provides on-line, real-time air flow balancing without extensive testing or large complex physical models. NO{sub x} emissions and unit heat rate are very sensitive to air distribution and turbulence in the combustion zone. These issues are continuously changing due to ambient conditions, coal quality and the condition of plant equipment. This report discusses applying on-line, real-time and neural network to adjust secondary air flow and overfire air flow to reduce NO{sub x} and improve heat rate on various coal fired boiler designs.

  16. An aid to streamlining fire-weather station networks

    Treesearch

    R. William Furman

    1975-01-01

    For reasons of economy it may be necessary to close one or several fire-weather stations in a protection area. Since it is logical to close those stations that will have the least impact on the ability of the fire manager to assess overall fire danger, it is desirable to know if there is duplication in monitoring fire climate, and to what degree. A method is proposed...

  17. Seasonal Forecasts of Extreme Conditions for Wildland Fire Management in Alaska using NMME

    NASA Astrophysics Data System (ADS)

    Bhatt, U. S.; Bieniek, P.; Thoman, R.; York, A.; Ziel, R.

    2016-12-01

    The summer of 2015 was the second largest Alaska fire season since 1950 where approximately the land area of Massachusetts burned. The record fire year of 2004 resulted in 6.5 million acres burned and was costly from property loss (> 35M) and emergency personnel (> 17M). In addition to requiring significant resources, wildfire smoke impacts air quality in Alaska and downstream into North America. Fires in Alaska result from lightning strikes coupled with persistent (extreme) dry warm conditions in remote areas with limited fire management and the seasonal climate/weather determine the extent of the fire season in Alaska. Fire managers rely on weather/climate outlooks for allocating staff and resources from days to a season in advance. Though currently few tested products are available at the seasonal scale. Probabilistic forecasts of the expected seasonal climate/weather would aid tremendously in the planning process. Advanced knowledge of both lightning and fuel conditions would assist managers in planning resource allocation for the upcoming season. For fuel conditions, the Canadian Forest Fire Weather Index System (CFFWIS) has been used since 1992 because it better suits the Alaska fire regime than the standard US National Fire Danger Rating System (NFDRS). This CFFWIS is based on early afternoon values of 2-m air temperature, relative humidity, and 10-m winds and daily total precipitation. Extremes of these indices and the variables are used to calculate these indices will be defined in reference to fire weather for the boreal forest. The CFFWIS will be applied and evaluated for the NMME hindcasts. This study will evaluate the quality of the forecasts comparing the hindcast NMME CFFWIS to acres burned in Alaska. Spatial synoptic patterns in the NMME related to fire weather extremes will be constructed using self-organized maps and probabilities of occurrence will be evaluated against acres burned.

  18. Role of perceived danger in the mediation of obsessive-compulsive washing.

    PubMed

    Jones, M K; Menzies, R G

    1998-01-01

    The role of danger expectancies in sub-clinical Obsessive-Compulsive Disorder (OCD) was examined in 18 undergraduate students who had displayed washing/contamination concerns. The perceived level of danger in a Behavioural Avoidance Test (BAT) involving a compound stimulus of potting soil, animal hair, food scraps, and raw meat was manipulated by varying the instructions participants were given at the commencement of the BAT. Participants were randomly allocated into a high-danger instruction condition or a low-danger instruction condition. Participants in the higher-danger instruction condition had higher mean ratings for anxiety and urge in wash, showed greater avoidance, and spent longer washing their hands at the completion of the task than participants in the low-danger instruction condition. However, only the differences in avoidance scores and post-BAT washing were statistically significant. These findings are discussed in relation to danger-based models of OCD.

  19. Geomorphology of coal seam fires

    NASA Astrophysics Data System (ADS)

    Kuenzer, Claudia; Stracher, Glenn B.

    2012-02-01

    Coal fires occur in underground natural coal seams, in exposed surface seams, and in coal storage or waste piles. The fires ignite through spontaneous combustion or natural or anthropogenic causes. They are reported from China, India, USA, South Africa, Australia, and Russia, as well as many other countries. Coal fires lead to loss of a valuable resource (coal), the emission of greenhouse-relevant and toxic gases, and vegetation deterioration. A dangerous aspect of the fires is the threat to local mines, industries, and settlements through the volume loss underground. Surface collapse in coal fire areas is common. Thus, coal fires are significantly affecting the evolution of the landscape. Based on more than a decade of experience with in situ mapping of coal fire areas worldwide, a general classification system for coal fires is presented. Furthermore, coal seam fire geomorphology is explained in detail. The major landforms associated with, and induced by, these fires are presented. The landforms include manifestations resulting from bedrock surface fracturing, such as fissures, cracks, funnels, vents, and sponges. Further manifestations resulting from surface bedrock subsidence include sinkholes, trenches, depressions, partial surface subsidence, large surface subsidence, and slides. Additional geomorphologic coal fire manifestations include exposed ash layers, pyrometamorphic rocks, and fumarolic minerals. The origin, evolution, and possible future development of these features are explained, and examples from in situ surveys, as well as from high-resolution satellite data analyses, are presented. The geomorphology of coal fires has not been presented in a systematic manner. Knowledge of coal fire geomorphology enables the detection of underground coal fires based on distinct surface manifestations. Furthermore, it allows judgments about the safety of coal fire-affected terrain. Additionally, geomorphologic features are indicators of the burning stage of fires

  20. Fire occurrence prediction in the Mediterranean: Application to Southern France

    NASA Astrophysics Data System (ADS)

    Papakosta, Panagiota; Öster, Jan; Scherb, Anke; Straub, Daniel

    2013-04-01

    the German and French Weather Services (Deutscher Wetterdienst and Météo-France). Historical fire events are taken from Prométhée database. Time series 2000-2010 are used as learning data and data from 2011 is used as the validation data. The resulting model can support real-time fire risk estimation for improved allocation of firefighting resources and planning of other mitigation actions. [1] Keeley, J.E.; Bond, W.J.; Bradstock, R.A.; Pausas, J.G.; Rundel, P.W. (2012): Fire in Mediterranean ecosystems: ecology, evolution and management. Cambridge University Press, New York, USA, pp.515 [2] Lawson, B.D.; Armitage, O.B. (2008): Weather Guide for the Canadian Forest Fire Danger Rating System. Natural Resources Canada, Canadian Forest Service, Northern Forestry Centre, Edmonton, Alberta, Canada. [3] Van Wagner, C.E.; Pickett, T.L. (1985): Equations and FORTRAN Program for the Canadian Forest Fire Weather Index System. Forestry Technical Report 33. Canadian Forestry Service, Government of Canada, Ottawa, Ontario, Canada [4] Syphard, A.D.; Radeloff, V.C.; Keuler, N.S.; Taylor, R.S.; Hawbaker, T.J.; Stewart, S.I.; Clayton, M.K. (2008): Predicting spatial patterns of fire on a southern California landscape. International Journal of Wildland Fire, 17, pp.602-613 [5] Papakosta, P.; Klein, F.; König, S.; Straub, D. (2012): Linking spatio-temporal data to the Fire Weather Index to estimate the probability of wildfire in the Mediterranean. Geophysical Research Abstracts, Vol.14, EGU2012-12737, EGU General Assembly 2012

  1. Impacts of the post-fire erosion processes compared with the agricultural erosion rates for a mountain catchment in NW Iberia

    NASA Astrophysics Data System (ADS)

    Marisa Santos, Juliana; Nunes, João Pedro; Bernard-Jannin, Léonard; Gonzalez Pelayo, Oscar; Keizer, Jan Jacob

    2014-05-01

    after forest fires. The last forest fire in August 2011 burned 10% of the total area in the north-west part of the catchment. Post-fire management operations 9 month after the fire (clear-cutting and deep plowing operations) and after plantation of "Quercus robur" left the soil exposed, and relatively mild rainstorms led to large amounts of soil loss, including a large amount of rills and other erosion features. This constituted an opportunity to compare these erosion rates with the ones observed in agricultural fields for similar edapho-climatic conditions, and also observe distinct timing of erosion occurrence which was linked with different periods when soils are exposed. This communication presents the assessment of the impact of this fire on soil erosion rates, where results indicate that soil losses after soil preparation for forest replanting might be equivalent, in long-term, to soil losses in agricultural fields.

  2. Moderate Image Spectrometer (MODIS) Fire Radiative Energy: Physics and Applications

    NASA Technical Reports Server (NTRS)

    Kaufman, Y.

    2004-01-01

    MODIS fire channel does not saturate in the presence of fires. The fire channel therefore is used to estimate the fire radiative energy, a measure of the rate of biomass consumption in the fire. We found correlation between the fire radiative energy, the rate of formation of burn scars and the rate of emission of aerosol from the fires. Others found correlations between the fire radiative energy and the rate of biomass consumption. This relationships can be used to estimates the emissions from the fires and to estimate the fire hazards.

  3. Danger of Antibiotic Overuse (For Parents)

    MedlinePlus

    ... 1- to 2-Year-Old The Danger of Antibiotic Overuse KidsHealth > For Parents > The Danger of Antibiotic ... by not reaching for the prescription pad. How Antibiotics Work Antibiotics, first used in the 1940s, are ...

  4. 29 CFR 1903.13 - Imminent danger.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... immediately or before the imminence of such danger can be eliminated through the enforcement procedures... informed of such danger by the Compliance Safety and Health Officer, the employer immediately eliminates...

  5. Xylitol and Your Dog: Danger, Paws Off

    MedlinePlus

    ... Home For Consumers Consumer Updates Xylitol and Your Dog: Danger, Paws Off Share Tweet Linkedin Pin it ... back to top Why is Xylitol Dangerous to Dogs, but Not People? In both people and dogs, ...

  6. Technologies of Physical Monitoring and Mathematical Modeling for Estimation of Ground Forest Fuel Fire Condition

    NASA Astrophysics Data System (ADS)

    Baranovskiy, Nikolay V.; Bazarov, Alexandr V.

    2016-02-01

    Description of new experimental installations for the control of parameters of environment with a view of monitoring of forest fires presented in article. Stationary and mobile variants developed. Typical results of operation of installations during a fire-dangerous season of 2015 in vicinities of Ulan-Ude (Republic Buryatiya, Russia) presented. One-dimensional mathematical model of forest fuel drying which can be used for monitoring of forest fire danger with attraction of environmental parameters data during fire-dangerous season offered. Verification of mathematical model with use of known experimental data spent.

  7. Basal level of FANCD2 monoubiquitination is required for the maintenance of a sufficient number of licensed-replication origins to fire at a normal rate

    PubMed Central

    Panneerselvam, Jayabal; Pickering, Anna; Han, Bing; Li, Liantao; Zheng, Junnian; Zhang, Jun; Zhang, Yanbin; Fei, Peiwen

    2014-01-01

    Normal DNA replication starts following the stepwise recruitment of replication initiators to assemble Mini-chromosome Maintenance (MCM) 2-7 protein complexes at an adequate amount of DNA replication origins. Under normal conditions, the monoubiquitination of Fanconi Anemia (FA) group D2 protein (FANCD2) occurs in each S-phase of cell cycle, which is the basal level of FANCD2 monoubiquitination. However, little is known regarding the roles of this basal level of monoubiquitinated FANCD2. Here we show that monoubiquitinated FANCD2 in each S-phase of normal cell cycle is essential for replication origins to fire at a normal rate. We found that the basal level of the monoubiquitinated FANCD2 can interact with replication origins as well as mini-chromosome maintenance protein 3 (MCM3) in an S-phase specific manner to secure an enough number of the licensed-origins to fire. Non-monoubiquitinated FANCD2 or mutant MCM3 lacking AA 477-480 responsible for interacting with FANCD2 can lead to an insufficient amount of licensed origins to fire and, thereby, enlarged intervals between the fired origins. Our results demonstrate that the monoubiquitinated FANCD2 in each S-phase of normal cell cycle is required to maintain an enough number of licensed origins to initiate the normal DNA replication. This finding is the first to provide insights into how FANCD2 functions under normal condition of cell cycle to maintain genome stability, as well as resulting implications in the strategic improvement for the fight against human cancer. PMID:24658369

  8. Basal level of FANCD2 monoubiquitination is required for the maintenance of a sufficient number of licensed-replication origins to fire at a normal rate.

    PubMed

    Panneerselvam, Jayabal; Pickering, Anna; Han, Bing; Li, Liantao; Zheng, Junnian; Zhang, Jun; Zhang, Yanbin; Fei, Peiwen

    2014-03-15

    Normal DNA replication starts following the stepwise recruitment of replication initiators to assemble Mini-chromosome Maintenance (MCM) 2-7 protein complexes at an adequate amount of DNA replication origins. Under normal conditions, the monoubiquitination of Fanconi Anemia (FA) group D2 protein (FANCD2) occurs in each S-phase of cell cycle, which is the basal level of FANCD2 monoubiquitination. However, little is known regarding the roles of this basal level of monoubiquitinated FANCD2. Here we show that monoubiquitinated FANCD2 in each S-phase of normal cell cycle is essential for replication origins to fire at a normal rate. We found that the basal level of the monoubiquitinated FANCD2 can interact with replication origins as well as mini-chromosome maintenance protein 3 (MCM3) in an S-phase specific manner to secure an enough number of the licensed-origins to fire. Non-monoubiquitinated FANCD2 or mutant MCM3 lacking AA 477-480 responsible for interacting with FANCD2 can lead to an insufficient amount of licensed origins to fire and, thereby, enlarged intervals between the fired origins. Our results demonstrate that the monoubiquitinated FANCD2 in each S-phase of normal cell cycle is required to maintain an enough number of licensed origins to initiate the normal DNA replication. This finding is the first to provide insights into how FANCD2 functions under normal condition of cell cycle to maintain genome stability, as well as resulting implications in the strategic improvement for the fight against human cancer.

  9. 75 FR 65278 - Pamlico Sound and Adjacent Waters, NC; Danger Zones for Marine Corps Operations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-22

    ... its regulations to establish one new danger zone in Pamlico Sound near Marine Corps Air Station Cherry... scheduled live fire training, Marine Corps Air Station Cherry Point has requested that the Corps establish... advance of the actual training start date. Marine Corps Air Station, Cherry Point will have a call-in...

  10. Selection and maintenance key to fire protection

    SciTech Connect

    Briese, B.L.

    1996-11-01

    Petroleum product and chemical storage terminals, because of the combustible products they handle, face severe fire exposure potentials. A fire at a terminal can grow rapidly and release damaging and deadly heat, threatening personnel, facilities, the adjoining environment and revenue. To combat this danger, terminals employ several types of fire protection systems, both fixed and mobile. All adhere to consensus codes and standards. Following installation of automatic fire protection equipment, its acceptance (sometimes referred to as commissioning) testing, ongoing maintenance and periodic inspection is vitally important to assure that it reliably functions when required.

  11. Fire risk in California

    NASA Astrophysics Data System (ADS)

    Peterson, Seth Howard

    Fire is an integral part of ecosystems in the western United States. Decades of fire suppression have led to (unnaturally) large accumulations of fuel in some forest communities, such as the lower elevation forests of the Sierra Nevada. Urban sprawl into fire prone chaparral vegetation in southern California has put human lives at risk and the decreased fire return intervals have put the vegetation community at risk of type conversion. This research examines the factors affecting fire risk in two of the dominant landscapes in the state of California, chaparral and inland coniferous forests. Live fuel moisture (LFM) is important for fire ignition, spread rate, and intensity in chaparral. LFM maps were generated for Los Angeles County by developing and then inverting robust cross-validated regression equations from time series field data and vegetation indices (VIs) and phenological metrics from MODIS data. Fire fuels, including understory fuels which are not visible to remote sensing instruments, were mapped in Yosemite National Park using the random forests decision tree algorithm and climatic, topographic, remotely sensed, and fire history variables. Combining the disparate data sources served to improve classification accuracies. The models were inverted to produce maps of fuel models and fuel amounts, and these showed that fire fuel amounts are highest in the low elevation forests that have been most affected by fire suppression impacting the natural fire regime. Wildland fires in chaparral commonly burn in late summer or fall when LFM is near its annual low, however, the Jesusita Fire burned in early May of 2009, when LFM was still relatively high. The HFire fire spread model was used to simulate the growth of the Jesusita Fire using LFM maps derived from imagery acquired at the time of the fire and imagery acquired in late August to determine how much different the fire would have been if it had occurred later in the year. Simulated fires were 1.5 times larger

  12. Presynaptic mitochondria in functionally different motor neurons exhibit similar affinities for Ca2+ but exert little influence as Ca2+ buffers at nerve firing rates in situ

    PubMed Central

    Chouhan, Amit K.; Zhang, Jinhui; Zinsmaier, Konrad E.; Macleod, Gregory T.

    2010-01-01

    Mitochondria accumulate within nerve terminals and support synaptic function, most notably through ATP production. They can also sequester Ca2+ during nerve stimulation, but it is unknown whether this limits presynaptic Ca2+ levels at physiological nerve firing rates. Similarly, it is unclear whether mitochondrial Ca2+ sequestration differs between functionally different nerve terminals. We addressed these questions using a combination of synthetic and genetically-encoded Ca2+ indicators (GECIs) to examine cytosolic and mitochondrial Ca2+ levels in presynaptic terminals of tonic (MN13-Ib) and phasic (MNSNb/d-Is) motor neurons in Drosophila, which, as we determined, fire during fictive locomotion at ∼42 Hz and ∼8 Hz, respectively. Mitochondrial Ca2+ sequestration starts in both terminals at ∼250 nM, exhibits a similar Ca2+-uptake affinity (∼410 nM), and does not require Ca2+ release from the endoplasmic reticulum. Nonetheless, mitochondrial Ca2+ uptake in type-Is terminals is more responsive to low frequency nerve stimulation and this is due to higher cytosolic Ca2+ levels. Since type-Ib terminals have a higher mitochondrial density than Is terminals, it seemed possible that greater mitochondrial Ca2+ sequestration may be responsible for the lower cytosolic Ca2+ levels in Ib terminals. However, genetic and pharmacological manipulations of mitochondrial Ca2+ uptake did not significantly alter nerve-stimulated elevations in cytosolic Ca2+ levels in either terminal type within physiologically relevant rates of stimulation. Our findings indicate that presynaptic mitochondria have a similar affinity for Ca2+ in functionally different nerve terminals, but do not limit cytosolic Ca2+ levels within the range of motor neuron firing rates in situ. PMID:20130196

  13. Presynaptic mitochondria in functionally different motor neurons exhibit similar affinities for Ca2+ but exert little influence as Ca2+ buffers at nerve firing rates in situ.

    PubMed

    Chouhan, Amit K; Zhang, Jinhui; Zinsmaier, Konrad E; Macleod, Gregory T

    2010-02-03

    Mitochondria accumulate within nerve terminals and support synaptic function, most notably through ATP production. They can also sequester Ca(2+) during nerve stimulation, but it is unknown whether this limits presynaptic Ca(2+) levels at physiological nerve firing rates. Similarly, it is unclear whether mitochondrial Ca(2+) sequestration differs between functionally different nerve terminals. We addressed these questions using a combination of synthetic and genetically encoded Ca(2+) indicators to examine cytosolic and mitochondrial Ca(2+) levels in presynaptic terminals of tonic (MN13-Ib) and phasic (MNSNb/d-Is) motor neurons in Drosophila, which, as we determined, fire during fictive locomotion at approximately 42 Hz and approximately 8 Hz, respectively. Mitochondrial Ca(2+) sequestration starts in both terminals at approximately 250 nM, exhibits a similar Ca(2+)-uptake affinity (approximately 410 nM), and does not require Ca(2+) release from the endoplasmic reticulum. Nonetheless, mitochondrial Ca(2+) uptake in type Is terminals is more responsive to low-frequency nerve stimulation and this is due to higher cytosolic Ca(2+) levels. Since type Ib terminals have a higher mitochondrial density than Is terminals, it seemed possible that greater mitochondrial Ca(2+) sequestration may be responsible for the lower cytosolic Ca(2+) levels in Ib terminals. However, genetic and pharmacological manipulations of mitochondrial Ca(2+) uptake did not significantly alter nerve-stimulated elevations in cytosolic Ca(2+) levels in either terminal type within physiologically relevant rates of stimulation. Our findings indicate that presynaptic mitochondria have a similar affinity for Ca(2+) in functionally different nerve terminals, but do not limit cytosolic Ca(2+) levels within the range of motor neuron firing rates in situ.

  14. 30 CFR 57.12021 - Danger signs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Danger signs. 57.12021 Section 57.12021 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.12021 Danger signs. Suitable danger signs shall be posted at all major electrical...

  15. 30 CFR 57.12021 - Danger signs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Danger signs. 57.12021 Section 57.12021 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.12021 Danger signs. Suitable danger signs shall be posted at all major electrical...

  16. 30 CFR 57.12021 - Danger signs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Danger signs. 57.12021 Section 57.12021 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.12021 Danger signs. Suitable danger signs shall be posted at all major...

  17. 30 CFR 57.12021 - Danger signs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Danger signs. 57.12021 Section 57.12021 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.12021 Danger signs. Suitable danger signs shall be posted at all major...

  18. 30 CFR 57.12021 - Danger signs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Danger signs. 57.12021 Section 57.12021 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.12021 Danger signs. Suitable danger signs shall be posted at all major...

  19. Documenting PyroCb Development on High-Intensity Boreal Fires: Implications for the Arctic Atmosphere

    NASA Astrophysics Data System (ADS)

    Stocks, B. J.; Fromm, M. D.; Servranckx, R.; Lindsey, D.

    2007-12-01

    The recent confirmation that smoke from high-intensity boreal forest fires can reach the Upper Troposphere/Lower Stratosphere (UTLS) through pyroconvection and be transported long distances has raised concern over the wider-scale environmental impact of boreal fire smoke. This concern is further elevated as climate change projections indicate a significant increase in the frequency and severity of boreal forest fires over the next century. Smoke in the UTLS is frequently transported to the Arctic and may have important implications for the radiative energy budget in the polar region. Soot deposition from fires may lead to enhanced melting of sea ice and glaciers, and the chemical impact of fire emissions at high altitudes is largely unknown. This knowledge gap will be addressed during the International Polar Year (IPY), as boreal fire emissions will be tracked and documented in detail through aerial, satellite and ground-based measurements, as a key component of the POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport) and ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) projects to be conducted in 2008. A large fire in the Canadian Northwest Territories burned throughout the month of June 2007, in a remote region where forest fires are not actively suppressed, eventually reaching 90,000 hectares in size. This fire was monitored for blowup one week in advance; it erupted into pyroconvection on June 25, 2007. We present an analysis of this event combining satellite data with ground-based measurements to document the development and impact of this classic pyroCb event. Under extreme fire danger conditions, the fire burned close to 20,000 hectares on that day. Fire behavior was consistent with predictions using the Canadian Fire Behavior Prediction System, with the fire spreading at 2.7 km/hr, consuming 33,000 kg of fuel hourly, generating an

  20. Assessment of Fire Occurrence and Future Fire Potential in Arctic Alaska

    NASA Astrophysics Data System (ADS)

    French, N. H. F.; Jenkins, L. K.; Loboda, T. V.; Bourgeau-Chavez, L. L.; Whitley, M. A.

    2014-12-01

    An analysis of the occurrence of fire in Alaskan tundra was completed using the relatively complete historical record of fire for the region from 1950 to 2013. Spatial fire data for Alaskan tundra regions were obtained from the Alaska Large Fire Database for the region defined from vegetation and ecoregion maps. A detailed presentation of fire records available for assessing the fire regime of the tundra regions of Alaska as well as results evaluating fire size, seasonality, and general geographic and temporal trends is included. Assessment of future fire potential was determined for three future climate scenarios at four locations across the Alaskan tundra using the Canadian Forest Fire Weather Index (FWI). Canadian Earth System Model (CanESM2) weather variables were used for historical (1850-2005) and future (2006-2100) time periods. The database includes 908 fire points and 463 fire polygons within the 482,931 km2 of Alaskan tundra. Based on the polygon database 25,656 km2 (6,340,000 acres) has burned across the six tundra ecoregions since 1950. Approximately 87% of tundra fires start in June and July across all ecoregions. Combining information from the polygon and points data records, the estimated average fire size for fire in the Alaskan Arctic region is 28.1 km2 (7,070 acres), which is much smaller than in the adjacent boreal forest region, averaging 203 km2 for high fire years. The largest fire in the database is the Imuruk Basin Fire which burned 1,680 km2 in 1954 in the Seward Peninsula region (Table 1). Assessment of future fire potential shows that, in comparison with the historical fire record, fire occurrence in Alaskan tundra is expected to increase under all three climate scenarios. Occurrences of high fire weather danger (>10 FWI) are projected to increase in frequency and magnitude in all regions modeled. The changes in fire weather conditions are expected to vary from one region to another in seasonal occurrence as well as severity and frequency

  1. Development of fire test methods for airplane interior materials

    NASA Technical Reports Server (NTRS)

    Tustin, E. A.

    1978-01-01

    Fire tests were conducted in a 737 airplane fuselage at NASA-JSC to characterize jet fuel fires in open steel pans (simulating post-crash fire sources and a ruptured airplane fuselage) and to characterize fires in some common combustibles (simulating in-flight fire sources). Design post-crash and in-flight fire source selections were based on these data. Large panels of airplane interior materials were exposed to closely-controlled large scale heating simulations of the two design fire sources in a Boeing fire test facility utilizing a surplused 707 fuselage section. Small samples of the same airplane materials were tested by several laboratory fire test methods. Large scale and laboratory scale data were examined for correlative factors. Published data for dangerous hazard levels in a fire environment were used as the basis for developing a method to select the most desirable material where trade-offs in heat, smoke and gaseous toxicant evolution must be considered.

  2. How to generate and interpret fire characteristics charts for surface and crown fire behavior

    Treesearch

    Patricia L. Andrews; Faith Ann Heinsch; Luke Schelvan

    2011-01-01

    A fire characteristics chart is a graph that presents primary related fire behavior characteristics-rate of spread, flame length, fireline intensity, and heat per unit area. It helps communicate and interpret modeled or observed fire behavior. The Fire Characteristics Chart computer program plots either observed fire behavior or values that have been calculated by...

  3. Scientific and social challenges for the management of fire-prone wildland-urban interfaces

    NASA Astrophysics Data System (ADS)

    Gill, A. Malcolm; Stephens, Scott L.

    2009-09-01

    At their worst, fires at the rural-urban or wildland-urban interface cause tragic loss of human lives and homes, but mitigating these fire effects through management elicits many social and scientific challenges. This paper addresses four interconnected management challenges posed by socially disastrous landscape fires. The issues concern various assets (particularly houses, human life and biodiversity), fuel treatments, and fire and human behaviours. The topics considered are: 'asset protection zones'; 'defensible space' and urban fire spread in relation to house ignition and loss; 'stay-or-go' policy and the prediction of time available for safe egress and the possible conflict between the creation of defensible space and wildland management objectives. The first scientific challenge is to model the effective width of an asset protection zone of an urban area. The second is to consider the effect of vegetation around a house, potentially defensible space, on fire arrival at the structure. The third scientific challenge is to present stakeholders with accurate information on rates of spread, and where the fire front is located, so as to allow them to plan safe egress or preparation time in their particular circumstances. The fourth scientific challenge is to be able to predict the effects of fires on wildland species composition. Associated with each scientific challenge is a social challenge: for the first two scientific challenges the social challenge is to co-ordinate fuel management within and between the urban and rural or wildland sides of the interface. For the third scientific challenge, the social challenge is to be aware of, and appropriately use, fire danger information so that the potential for safe egress from a home can be estimated most accurately. Finally, the fourth social challenge is to for local residents of wildland-urban interfaces with an interest in biodiversity conservation to understand the effects of fire regimes on biodiversity, thereby

  4. Vegetation dynamics in response to water inflow rates and fire in a brackish Typha domingensis Pers. marsh in the delta of the Colorado River, Mexico

    USGS Publications Warehouse

    Mexicano, Lourdes; Nagler, Pamela L.; Zamora-Arroyo, Francisco; Glenn, Edward P.

    2012-01-01

    The Cienega de Santa Clara is a 5600 ha, anthropogenic wetland in the delta of the Colorado River in Mexico. It is the inadvertent creation of the disposal of brackish agricultural waste water from the U.S. into the intertidal zone of the river delta in Mexico, but has become an internationally important wetland for resident and migratory water birds. We used high resolution Quickbird and WorldView-2 images to produce seasonal vegetation maps of the Cienega before, during and after a test run of the Yuma Desalting Plant, which will remove water from the inflow stream and replace it with brine. We also used moderate resolution, 16-day composite NDVI imagery from the Moderate Resolution Imaging Spectrometer (MODIS) sensors on the Terra satellite to determine the main factors controlling green vegetation density over the years 2000–2011. The marsh is dominated by Typha domingensis Pers. with Phragmites australis (Cav.) Trin. Ex Steud. as a sub-dominant species in shallower marsh areas. The most important factor controlling vegetation density was fire. Spring fires in 2006 and 2011 were followed by much more rapid green-up of T. domingensis in late spring and 30% higher peak summer NDVI values compared to non-fire years (P < 0.001). Fires removed thatch and returned nutrients to the water, resulting in more vigorous vegetation growth compared to non-fire years. The second significant (P < 0.01) factor controlling NDVI was flow rate of agricultural drain water from the U.S. into the marsh. Reduced summer flows in 2001 due to canal repairs, and in 2010 during the YDP test run, produced the two lowest NDVI values of the time series from 2000 to 2011 (P < 0.05). Salinity is a further determinant of vegetation dynamics as determined by greenhouse experiments, but was nearly constant over the period 2000–2011, so it was not a significant variable in regression analyses. It is concluded that any reduction in inflow volumes will result in a linear decrease in green foliage

  5. Fire safety

    Treesearch

    Robert H. White; Mark A. Dietenberger

    1999-01-01

    Fire safety is an important concern in all types of construction. The high level of national concern for fire safety is reflected in limitations and design requirements in building codes. These code requirements are discussed in the context of fire safety design and evaluation in the initial section of this chapter. Since basic data on fire behavior of wood products...

  6. Perceived Danger while Intoxicated Uniquely Contributes to Driving after Drinking

    PubMed Central

    Morris, David H.; Treloar, Hayley R.; Niculete, Maria E.; McCarthy, Denis M.

    2013-01-01

    Background Previous findings suggest that alcohol alters perceptions of risky behaviors such as drinking and driving. However, studies testing these perceptions as a predictor of drinking and driving typically measure these perceptions while participants are sober. The present study tested whether the perceived danger of driving after drinking assessed while intoxicated was associated with increased willingness to drive and self-reported drinking-and-driving behavior over and above perceptions assessed while sober. Additionally, we tested the effect of acute tolerance on the perceived danger of driving after drinking assessed on the ascending and descending limbs of the breath alcohol concentration (BrAC) curve. Methods Eighty-two young adults attended two counterbalanced laboratory sessions. In one session, participants consumed a moderate dose of alcohol (men: .72 g/kg, women: .65 g/kg) and reported the perceived danger of driving and their willingness to drive at multiple points across the BrAC curve. On a separate occasion, participants remained sober and appraised the dangerousness of driving at a hypothetical, illegal BrAC. Results Perceptions of the dangerousness of driving following alcohol administration were associated with increased willingness to drive and higher rates of self-reported drinking-and-driving behavior over and above perceptions reported when sober. Furthermore, perceived danger was reduced on the descending limb of the BrAC curve, compared to the ascending limb, suggesting the occurrence of acute tolerance. Conclusions Results from this study suggest that intoxicated perceptions are uniquely associated with drinking-and-driving decisions and that the perceived danger of drinking and driving is lower on the descending limb of the BrAC curve. Efforts to prevent alcohol-impaired driving have focused on increasing awareness of the danger of driving after drinking. Prevention efforts may be enhanced by educating drivers about how intoxication

  7. Perceived danger while intoxicated uniquely contributes to driving after drinking.

    PubMed

    Morris, David H; Treloar, Hayley R; Niculete, Maria E; McCarthy, Denis M

    2014-02-01

    Previous findings suggest that alcohol alters perceptions of risky behaviors such as drinking and driving. However, studies testing these perceptions as a predictor of drinking and driving typically measure these perceptions while participants are sober. This study tested whether the perceived danger of driving after drinking assessed while intoxicated was associated with increased willingness to drive and self-reported drinking-and-driving behavior over and above perceptions assessed while sober. Additionally, we tested the effect of acute tolerance on the perceived danger of driving after drinking assessed on the ascending and descending limbs of the breath alcohol concentration (BrAC) curve. Eighty-two young adults attended 2 counterbalanced laboratory sessions. In one session, participants consumed a moderate dose of alcohol (men: 0.72 g/kg, women: 0.65 g/kg) and reported their perceived danger of driving and willingness to drive at multiple points across the BrAC curve. On a separate occasion, participants remained sober and appraised the dangerousness of driving at a hypothetical, illegal BrAC. Perceptions of the dangerousness of driving following alcohol administration were associated with increased willingness to drive and higher rates of self-reported drinking-and-driving behavior over and above perceptions reported when sober. Furthermore, perceived danger was reduced on the descending limb of the BrAC curve, compared with the ascending limb, suggesting the occurrence of acute tolerance. Results from this study suggest that intoxicated perceptions are uniquely associated with drinking-and-driving decisions and that the perceived danger of drinking and driving is lower on the descending limb of the BrAC curve. Efforts to prevent alcohol-impaired driving have focused on increasing awareness of the danger of driving after drinking. Prevention efforts may be enhanced by educating drivers about how intoxication can alter perceived danger, and interventions

  8. Measuring fire behavior with photography

    Treesearch

    Hubert B. Clements; Darold E. Ward; Carl W. Adkins

    1983-01-01

    Photography is practical for recording and measuring some aspects of forest fire behavior if the scale and perspective can be determined. This paper describes a photogrammetric method for measuring flame height and rate of spread for fires on flat terrain. The flames are photographed at known times with a camera in front of the advancing fire. Scale and perspective of...

  9. Thermocouples for forest fire research

    Treesearch

    Erwin H. Breuer

    1965-01-01

    Thermocouples have proved valuable in research conducted by the Fire Physics Project at the Northern Forest Fire Laboratory because they can measure several important fire variables besides flame and convection column temperatures. These include rate of spread and flame residence time. Describes a simple, rapid method of fabrication and reports useful and diverse...

  10. Assessment of dose rate to terrestrial biota in the area around coal fired power plant applying ERICA tool and RESRAD BIOTA code.

    PubMed

    Ćujić, Mirjana; Dragović, Snežana

    2017-09-27

    This paper presents the environmental radiation risk assessment based on two software program approaches ERICA Tool (version 1.2) and RESRAD BIOTA (version 1.5) to estimate dose rates to terrestrial biota in the area around the largest coal fired power plant in Serbia. For dose rate assessment software's default reference animals and plants and the best estimated values of activity concentrations of (238)U, (234)U, (234)Th, (232)Th, (230)Th, (226)Ra, (210)Pb, (210)Po, (137)Cs in soil were used. Both approaches revealed the highest contribution to the internal dose rate due to (226)Ra and (210)Po, while (137)Cs contributed the most to the external dose rate. In the investigated area total dose rate to biota derived using ERICA Tool ranged from 0.3 to 14.4 μGy h(-1). The natural radionuclides exhibited significantly higher contribution to the total dose rate than the artificial one. In the investigated area, only dose rate for lichens and bryophytes exceeded ERICA Tool screening value of total dose rate of 10 μGy h(-1) suggested as confident that environmental risks are negligible. The assessed total dose rates for reference animals and plants using RESRAD BIOTA were found to be 7 and 3 μGy h(-1), respectively. In RESRAD BIOTA - Level 3, 10 species (Lumbricus terrestris, Rana lessonae, Sciurus vulgaris, Anas platyrhynchos, Lepus europaeus, Vulpes vulpes, Capreolus capreolus, Suss crofa, Quercu srobur, Tilia spp.) representative for the study area were modeled. Among them the highest total dose rate (4.5 μGy h(-1)) was obtained for large mammals. Differences in the predicted dose rates to biota using the two software programs are the consequence of the difference in the values of transfer parameters used to calculate activity concentrations in biota. Doses of ionizing radiation estimated in this study will not exhibit deterministic effects at the population level. Thus, the obtained results indicate no significant radiation impact of coal fired power plant

  11. Fighting Fire with Fire.

    ERIC Educational Resources Information Center

    Spoor, Dana L.

    1996-01-01

    School districts are integrating security and life-safety systems into school buildings to protect students and property. This proactive approach includes sprinkler systems, fire alarms, and security systems that monitor door movement. Some school districts that are incorporating the latest life-safety technology are in Missouri, Ohio, California,…

  12. Fighting Fire with Fire.

    ERIC Educational Resources Information Center

    Spoor, Dana L.

    1996-01-01

    School districts are integrating security and life-safety systems into school buildings to protect students and property. This proactive approach includes sprinkler systems, fire alarms, and security systems that monitor door movement. Some school districts that are incorporating the latest life-safety technology are in Missouri, Ohio, California,…

  13. SO/sub 2/(g)-to-sulfate conversion rate in an oil-fired-power-plant plume in a fog bank

    SciTech Connect

    Eatough, D.J.; Arthur, R.J.; Eatough, N.L.; Hill, M.W.; Mangelson, N.F.; Richter, B.E.; Hansen, L.D.; Cooper, J.A.

    1983-01-01

    High acidity in rainfall, cloud droplets and fog droplets in areas influenced by anthropogenic sources of SO/sub 2/(g) and NO/sub x/(g) has been attributed to the formation of both H/sub 2/SO/sub 4/ and HNO/sub 3/. It has been suggested, based on the analysis of field data, that rapid conversion of SO/sub 2/(g) to sulfate must occur in cloud or fog droplets. Direct measurements of the rate of SO/sub 2/(g) to sulfate conversion in an oil-fired power plant plume as it passes through a fog bank are reported here. A conversion rate of 30+-4% SO/sub 2/(g) h/sup -1/ was found in the fog bank.

  14. Dangers of the menopause. 1910.

    PubMed

    Perkins, Anne E

    2012-06-01

    Editor's note: From its first issue in 1900 through to the present day, AJN has unparalleled archives detailing nurses' work and lives over the last century. These articles not only chronicle nursing's growth as a profession within the context of the events of the day, but they also reveal prevailing societal attitudes about women, health care, and human rights. Today's nursing school curricula rarely include nursing's history, but it's a history worth knowing. To this end, From the AJN Archives will be a frequent column, containing articles selected to fit today's topics and times.This month's article, from the September 1910 issue, is "Dangers of the Menopause." The author, Anne E. Perkins, MD, states that its purpose is to correct "popular fallacies," so nurses can "disseminate knowledge of the real dangers" of menopause. It's interesting how much information in the article is still valid 100 years later, such as the need to investigate any postmenopausal bleeding. It's also noteworthy that the three symptoms causing women the most distress-hot flashes, insomnia, and mood problems-haven't changed, although a comparison of Dr. Perkins's article with "Managing Menopausal Symptoms" in this issue reveals that menopause management certainly has: from a "trip abroad" and avoiding "fancy work" in 1910 to physical exercise and acupuncture in 2012. To read the complete article from our archives, go to http://bit.ly/IZkCiD.

  15. Danger signs in drug hypersensitivity.

    PubMed

    Scherer, Kathrin; Bircher, Andreas J

    2010-07-01

    ADRs are frequently considered iatrogenic complications and, therefore, pose a specific challenge for the physician-patient relationship. Early recognition of a potential ADR is possible, especially on the skin, in addition to characteristic clinical danger signs. Cutaneous manifestations are variable, depending on the causative pathomechanism. It is impossible to conclude the causative agent from the morphology of the cutaneous lesions. The intake of several drugs in the time before the elicitation of the drug reaction usually poses a diagnostic challenge. It is crucial for the precision of any further allergological work-up to document the type of rash precisely as well as the time course of drug intake and appearance of the first symptoms. involvement of internal organs or circulating blood cells. Timely recognition of such cutaneous lesions and the correct differential diagnosis with prompt withdrawal of the putative culprit drug are essential to reducing morbidity and preventing mortality. This article discusses risk factors, early symptoms, and danger signs indicating a possibly severe course of an ADR and advises on early actions.

  16. Too Much Too Fast: The Dangers of Technological Momentum.

    ERIC Educational Resources Information Center

    Dyer, Dean

    This paper discusses the dangers of technological momentum. Technological momentum is defined as the increase in the rate of the evolution of technology, its infusion into societal tasks and recreations, society's dependence on technology, and the impact of technology on society. Topics of discussion include changes in response to user needs,…

  17. Designing fire safe interiors.

    PubMed

    Belles, D W

    1992-01-01

    Any product that causes a fire to grow large is deficient in fire safety performance. A large fire in any building represents a serious hazard. Multiple-death fires almost always are linked to fires that grow quickly to a large size. Interior finishes have large, continuous surfaces over which fire can spread. They are regulated to slow initial fire growth, and must be qualified for use on the basis of fire tests. To obtain meaningful results, specimens must be representative of actual installation. Variables--such as the substrate, the adhesive, and product thickness and density--can affect product performance. The tunnel test may not adequately evaluate some products, such as foam plastics or textile wall coverings, thermoplastic materials, or materials of minimal mass. Where questions exist, products should be evaluated on a full-scale basis. Curtains and draperies are examples of products that ignite easily and spread flames readily. The present method for testing curtains and draperies evaluates one fabric at a time. Although a fabric tested alone may perform well, fabrics that meet test standards individually sometimes perform poorly when tested in combination. Contents and furnishings constitute the major fuels in many fires. Contents may involve paper products and other lightweight materials that are easily ignited and capable of fast fire growth. Similarly, a small source may ignite many items of furniture that are capable of sustained fire growth. Upholstered furniture can reach peak burning rates in less than 5 minutes. Furnishings have been associated with many multiple-death fires.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Meteorological conditions affecting the Freeman Lake (Idaho) fire

    Treesearch

    George M. Jemison

    1932-01-01

    Measurements of meteorological conditions prevailing during the rapid spread of forest fires are greatly needed so that when their recurrence seems probable, fire-weather forecasters may issue warnings of the danger. Such determinations also can be used by forest protective agencies which operate meteorological stations to guide their own action in the distribution of...

  19. 29 CFR 1926.909 - Firing the blast.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 8 2013-07-01 2013-07-01 false Firing the blast. 1926.909 Section 1926.909 Labor... Firing the blast. (a) A code of blasting signals equivalent to Table U-1, shall be posted on one or more... code and conform to it. Danger signs shall be placed at suitable locations. (b) Before a blast is...

  20. 29 CFR 1926.909 - Firing the blast.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 8 2014-07-01 2014-07-01 false Firing the blast. 1926.909 Section 1926.909 Labor... Firing the blast. (a) A code of blasting signals equivalent to Table U-1, shall be posted on one or more... code and conform to it. Danger signs shall be placed at suitable locations. (b) Before a blast is...

  1. 29 CFR 1926.909 - Firing the blast.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 8 2011-07-01 2011-07-01 false Firing the blast. 1926.909 Section 1926.909 Labor... Firing the blast. (a) A code of blasting signals equivalent to Table U-1, shall be posted on one or more... code and conform to it. Danger signs shall be placed at suitable locations. (b) Before a blast is...

  2. 29 CFR 1926.909 - Firing the blast.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Firing the blast. 1926.909 Section 1926.909 Labor... Firing the blast. (a) A code of blasting signals equivalent to Table U-1, shall be posted on one or more... code and conform to it. Danger signs shall be placed at suitable locations. (b) Before a blast is...

  3. 29 CFR 1926.909 - Firing the blast.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 8 2012-07-01 2012-07-01 false Firing the blast. 1926.909 Section 1926.909 Labor... Firing the blast. (a) A code of blasting signals equivalent to Table U-1, shall be posted on one or more... code and conform to it. Danger signs shall be placed at suitable locations. (b) Before a blast is...

  4. Integrating models to predict regional haze from wildland fire.

    Treesearch

    D. McKenzie; S.M. O' Neill; N. Larkin; R.A. Norheim

    2006-01-01

    Visibility impairment from regional haze is a significant problem throughout the continental United States. A substantial portion of regional haze is produced by smoke from prescribed and wildland fires. Here we describe the integration of four simulation models, an array of GIS raster layers, and a set of algorithms for fire-danger calculations into a modeling...

  5. The three wheeler (adult tricycle): an unstable, dangerous machine.

    PubMed

    Haynes, C D; Stroud, S D; Thompson, C E

    1986-07-01

    Three-wheel motor vehicular accidents are a common occurrence, yet we found little publicity or published research dedicated to exposing the dangers of this popular recreational vehicle, and manufacturers have released few warnings. In a 3-year period, 125 patients were seen in the emergency department in one east Alabama referral area, a far higher rate of accidents than caused by other similar types of vehicles. The most common mechanism of these accidents was rollover of the machine; fractures were the most frequent injury suffered. The very young are common victims. Accident prevention must begin with education of both parents and children about the potential dangers of three-wheelers--they are, indeed, dangerous, unstable machines.

  6. Mitigating operating room fires: development of a carbon dioxide fire prevention device.

    PubMed

    Culp, William C; Kimbrough, Bradly A; Luna, Sarah; Maguddayao, Aris J

    2014-04-01

    Operating room fires are sentinel events that present a real danger to surgical patients and occur at least as frequently as wrong-sided surgery. For fire to occur, the 3 points of the fire triad must be present: an oxidizer, an ignition source, and fuel source. The electrosurgical unit (ESU) pencil triggers most operating room fires. Carbon dioxide (CO2) is a gas that prevents ignition and suppresses fire by displacing oxygen. We hypothesize that a device can be created to reduce operating room fires by generating a cone of CO2 around the ESU pencil tip. One such device was created by fabricating a divergent nozzle and connecting it to a CO2 source. This device was then placed over the ESU pencil, allowing the tip to be encased in a cone of CO2 gas. The device was then tested in 21%, 50%, and 100% oxygen environments. The ESU was activated at 50 W cut mode while placing the ESU pencil tip on a laparotomy sponge resting on an aluminum test plate for up to 30 seconds or until the sponge ignited. High-speed videography was used to identify time of ignition. Each test was performed in each oxygen environment 5 times with the device activated (CO2 flow 8 L/min) and with the device deactivated (no CO2 flow-control). In addition, 3-dimensional spatial mapping of CO2 concentrations was performed with a CO2 sampling device. The median ± SD [range] ignition time of the control group in 21% oxygen was 2.9 s ± 0.44 [2.3-3.0], in 50% oxygen 0.58 s ± 0.12 [0.47-0.73], and in 100% oxygen 0.48 s ± 0.50 [0.03-1.27]. Fires were ignited with each control trial (15/15); no fires ignited when the device was used (0/15, P < 0.0001). The CO2 concentration at the end of the ESU pencil tip was 95%, while the average CO2 concentration 1 to 1.4 cm away from the pencil tip on the bottom plane was 64%. In conclusion, an operating room fire prevention device can be created by using a divergent nozzle design through which CO2 passes, creating a cone of fire suppressant. This device as

  7. Summer fire increases plant-available nitrogen and phosphorus in the Northern Great Plains

    USDA-ARS?s Scientific Manuscript database

    Fire is an important process maintaining ecosystem functioning in grasslands. Most wildfires in the western U.S. burn during summer and coincide with the greatest fire danger. Consequently, experimental data are lacking and little is known about the impacts of summer fire on ecosystem function. S...

  8. Fire investigation

    NASA Astrophysics Data System (ADS)

    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.

  9. Regional variation in fire weather controls the reported occurrence of Scottish wildfires

    PubMed Central

    Legg, Colin J.

    2016-01-01

    Fire is widely used as a traditional habitat management tool in Scotland, but wildfires pose a significant and growing threat. The financial costs of fighting wildfires are significant and severe wildfires can have substantial environmental impacts. Due to the intermittent occurrence of severe fire seasons, Scotland, and the UK as a whole, remain somewhat unprepared. Scotland currently lacks any form of Fire Danger Rating system that could inform managers and the Fire and Rescue Services (FRS) of periods when there is a risk of increased of fire activity. We aimed evaluate the potential to use outputs from the Canadian Fire Weather Index system (FWI system) to forecast periods of increased fire risk and the potential for ignitions to turn into large wildfires. We collated four and a half years of wildfire data from the Scottish FRS and examined patterns in wildfire occurrence within different regions, seasons, between urban and rural locations and according to FWI system outputs. We used a variety of techniques, including Mahalanobis distances, percentile analysis and Thiel-Sen regression, to scope the best performing FWI system codes and indices. Logistic regression showed significant differences in fire activity between regions, seasons and between urban and rural locations. The Fine Fuel Moisture Code and the Initial Spread Index did a tolerable job of modelling the probability of fire occurrence but further research on fuel moisture dynamics may provide substantial improvements. Overall our results suggest it would be prudent to ready resources and avoid managed burning when FFMC > 75 and/or ISI > 2. PMID:27833814

  10. Regional variation in fire weather controls the reported occurrence of Scottish wildfires.

    PubMed

    Davies, G Matt; Legg, Colin J

    2016-01-01

    Fire is widely used as a traditional habitat management tool in Scotland, but wildfires pose a significant and growing threat. The financial costs of fighting wildfires are significant and severe wildfires can have substantial environmental impacts. Due to the intermittent occurrence of severe fire seasons, Scotland, and the UK as a whole, remain somewhat unprepared. Scotland currently lacks any form of Fire Danger Rating system that could inform managers and the Fire and Rescue Services (FRS) of periods when there is a risk of increased of fire activity. We aimed evaluate the potential to use outputs from the Canadian Fire Weather Index system (FWI system) to forecast periods of increased fire risk and the potential for ignitions to turn into large wildfires. We collated four and a half years of wildfire data from the Scottish FRS and examined patterns in wildfire occurrence within different regions, seasons, between urban and rural locations and according to FWI system outputs. We used a variety of techniques, including Mahalanobis distances, percentile analysis and Thiel-Sen regression, to scope the best performing FWI system codes and indices. Logistic regression showed significant differences in fire activity between regions, seasons and between urban and rural locations. The Fine Fuel Moisture Code and the Initial Spread Index did a tolerable job of modelling the probability of fire occurrence but further research on fuel moisture dynamics may provide substantial improvements. Overall our results suggest it would be prudent to ready resources and avoid managed burning when FFMC > 75 and/or ISI > 2.

  11. Improving growth rate of microalgae in a 1191m(2) raceway pond to fix CO2 from flue gas in a coal-fired power plant.

    PubMed

    Cheng, Jun; Yang, Zongbo; Huang, Yun; Huang, Lei; Hu, Lizuo; Xu, Donghua; Zhou, Junhu; Cen, Kefa

    2015-08-01

    CO2 fixation between microalgal biomass and culture solution and the weight ratio of biomass consumption at nighttime to biomass growth at daytime were compared in an open raceway pond aerated with flue gas from a coal-fired power plant. Average daytime sunlight intensity and solution temperature were optimized to improve microalgal growth rate and to enhance the efficiency of CO2 fixation. When the average daytime solution temperature increased from 12 to 26°C, the rate of biomass consumption due to microalgal respiration at nighttime increased from 6.0 to 7.9g/m(2)/d, which was approximately 25% of the biomass growth rate at daytime. Furthermore, when the average daytime sunlight intensity increased from 39,900 to 88,300lux, CO2 fixation rate in the microalgal biomass increased from 18.4 to 40.7g/m(2)/d, which was approximately 1/3 of CO2 removal rate from flue gas by the microalgal culture system.

  12. Personal Safety in Dangerous Places

    PubMed Central

    Williams, Terry; Dunlap, Eloise; Johnson, Bruce D.; Hamid, Ansley

    2009-01-01

    Personal safety during fieldwork is seldom addressed directly in the literature. Drawing from many prior years of ethnographic research and from field experience while studying crack distributors in New York City, the authors provide a variety of strategies by which ethnographic research can be safely conducted in dangerous settings. By projecting an appropriate demeanor, ethnographers can seek others for protector and locator roles, routinely create a safety zone in the field, and establish compatible field roles with potential subjects. The article also provides strategies for avoiding or handling sexual approaches, common law crimes, fights, drive-by shootings, and contacts with the police. When integrated with other standard qualitative methods, ethnographic strategies help to ensure that no physical harm comes to the field-worker and other staff members. Moreover, the presence of researchers may actually reduce (and not increase) potential and actual violence among crack distributors/abusers or others present in the field setting. PMID:19809525

  13. Meteoroids are Dangerous to Spacecraft

    NASA Technical Reports Server (NTRS)

    Moorhead, Althea V.

    2017-01-01

    Meteoroids put dents in Shuttle windows much like bouncing gravel puts dents in your car's windshield. However, meteoroids move at such high speeds that they can partly vaporize the surfaces they strike! A dust particle (smaller than a meteoroid) hit the STEREO spacecraft and produced this fountain of smaller particles. When a meteoroid breaks up, its "shrapnel" can also be dangerous. Even when meteoroids don't damage a spacecraft, they can cause problems. Here, a small meteoroid bumped a camera on the Lunar Reconnaissance Orbiter (LRO), causing wiggles in this scan of the lunar surface. Meteoroids and pieces of space junk create rough edges on the outside of the Space Station that can damage space suits. The astronauts' gloves had to be thickened to help prevent them from ripping.

  14. Ecstasy is a dangerous drug.

    PubMed

    Murray, J B

    2001-06-01

    Ecstasy, a dangerous psychoactive drug, has become a popular recreational drug on college campuses and dance halls in the United States, United Kingdom, and around the world. No reports on ecstasy have shown addictiveness, and some users of ecstasy claim they prefer infrequent use which is not the usual addictive pattern. Jaw clenching, bruxism, and some cardiac arrhythmias requiring medical attention have been associated with consumption of ecstasy and some fatalities. In large scale retrospective questionnaire studies of subjective experiences users claimed that they felt a gentle relaxation and openness to others and few adversive effects. In rats and monkeys ecstasy has caused depletion of the neurotransmitter serotonin in the brain but similar effects have not been identified for humans. Case reports have shown panic attacks, flashbacks, paranoia, and even fatalities. The Drug Enforcement Administration in 1985 placed ecstasy in Schedule I, the most restrictive drug category.

  15. Chapter 6: Fire damage of wood structures

    Treesearch

    B. Kukay; R.H. White; F. Woeste

    2012-01-01

    Depending on the severity, fire damage can compromise the structural integrity of wood structures such as buildings or residences. Fire damage of wood structures can incorporate several models that address (1) the type, cause, and spread of the fire, (2) the thermal gradients and fire-resistance ratings, and (3) the residual load capacity (Figure 6.1). If there is a...

  16. Modeling post-fire water erosion mitigation strategies

    NASA Astrophysics Data System (ADS)

    Rulli, M. C.; Offeddu, L.; Santini, M.

    2013-06-01

    Severe wildfires are often followed by significant increase in runoff and erosion, due to vegetation damage and changes in physical and chemical soil properties. Peak flows and sediment yields can increase up to two orders of magnitude, becoming dangerous for human lives and the ecosystem, especially in the wildland-urban interface. Watershed post-fire rehabilitation measures are usually used to mitigate the effects of fire on runoff and erosion, by protecting soil from splash and shear stress detachment and enhancing its infiltration capacity. Modeling post-fire erosion and erosion mitigation strategies can be useful in selecting the effectiveness of a rehabilitation method. In this paper a distributed model based on the Revised Universal Soil Loss Equation (RUSLE), properly parameterized for a Mediterranean basin located in Sardinia, is used to determine soil losses for six different scenarios describing both natural and post-fire basin condition, the last also accounting for the single and combined effect of different erosion mitigation measures. Fire effect on vegetation and soil properties have been mimed by changing soil drainage capacity and organic matter content, and RUSLE factors related to soil cover and protection measures. Model results, validated using measured data on erosion rates from the literature and in situ field campaigns, show the effect of the analyzed rehabilitation treatments in reducing the amount of soil losses with the peculiar characteristics of the spatial distribution of such changes. In particular, the mulching treatment substantially decreases erosion both in its mean value (-75%) and in the spatially distribution of the erosion levels over the burned area . On the contrary, the breaking up of the hydrophobic layer decreases post-fire mean soil losses of about the 14%, although it strongly influences the spatial distribution of the erosion levels.

  17. Understory Fires

    NASA Image and Video Library

    The flames of understory fires in the southern Amazon reach on average only a few feet tall, but the fire type can claim anywhere from 10 to 50 percent of a burn area's trees. Credit: NASA/Doug Morton

  18. Investigating Over Critical Thresholds of Forest Megafires Danger Conditions in Europe Utilising the ECMWF ERA-Interim Reanalysis

    NASA Astrophysics Data System (ADS)

    Petroliagkis, Thomas I.; Camia, Andrea; Liberta, Giorgio; Durrant, Tracy; Pappenberger, Florian; San-Miguel-Ayanz, Jesus

    2014-05-01

    The European Forest Fire Information System (EFFIS) has been established by the Joint Research Centre (JRC) and the Directorate General for Environment (DG ENV) of the European Commission (EC) to support the services in charge of the protection of forests against fires in the EU and neighbour countries, and also to provide the EC services and the European Parliament with information on forest fires in Europe. Within its applications, EFFIS provides current and forecast meteorological fire danger maps up to 6 days. Weather plays a key role in affecting wildfire occurrence and behaviour. Meteorological parameters can be used to derive meteorological fire weather indices that provide estimations of fire danger level at a given time over a specified area of interest. In this work, we investigate the suitability of critical thresholds of fire danger to provide an early warning for megafires (fires > 500 ha) over Europe. Past trends of fire danger are analysed computing daily fire danger from weather data taken from re-analysis fields for a period of 31 years (1980 to 2010). Re-analysis global data sets coming from the construction of high-quality climate records, which combine past observations collected from many different observing and measuring platforms, are capable of describing how Fire Danger Indices have evolved over time at a global scale. The latest and most updated ERA-Interim dataset of the European Centre for Medium-Range Weather Forecast (ECMWF) was used to extract meteorological variables needed to compute daily values of the Canadian Fire Weather Index (CFWI) over Europe, with a horizontal resolution of about 75x75 km. Daily time series of CFWI were constructed and analysed over a total of 1,071 European NUTS3 centroids, resulting in a set of percentiles and critical thresholds. Such percentiles could be used as thresholds to help fire services establish a measure of the significance of CFWI outputs as they relate to levels of fire potential, fuel

  19. Fire Detector

    NASA Technical Reports Server (NTRS)

    1978-01-01

    An early warning fire detection sensor developed for NASA's Space Shuttle Orbiter is being evaluated as a possible hazard prevention system for mining operations. The incipient Fire Detector represents an advancement over commercially available smoke detectors in that it senses and signals the presence of a fire condition before the appearance of flame and smoke, offering an extra margin of safety.

  20. Predicting Change in Sediment Transport Rates in the Wake of the Cerro Grande Fire: Limitations and Potential of a Physically-based Approach

    NASA Astrophysics Data System (ADS)

    Canfield, H. E.; Wilson, C. J.; Lane, L. J.; McLin, S. G.; Earles, A.

    2001-12-01

    One of the benefits of physically based hydrologic models is that since they are based on physics, they can potentially be used to describe hydrologic response to change. On the Pajarito Plateau in New Mexico the introduction of cattle in the late 1800s, and then establishment of the Los Alamos National Laboratory in the 1940s has had a profound effect on the cover on the watersheds surrounding Los Alamos, with a proliferation of a more dense under story, on the hillsides, and more impermeable areas at the town site. Since the establishment of the Laboratory, there have been several large forest fires, most recently, the Cerro Grande Fire in May 2000. Hydrologic models suggest an eight-fold increase in the 100yr-6hr-flood peak in Los Alamos Canyon, and a corresponding three to four fold increase in sediment transport in the Canyon under post-burn conditions. However, the magnitude of the predicted scour depends strongly on what processes are allowed to occur in the model. The predicted scour is much greater if the model incorporates an observed inset channel, where modeled velocities are much greater than in the full wetted area. Furthermore, the model suggests that armoring has the potential to cut off the supply of sediment in the bed, so that scour and sediment transport are limited by the capability of the flow to transport larger particles that might otherwise armor the bed. Therefore, the magnitude of the predicted increase in sediment transport depends strongly on the ability of channels to armor as well as an a-priori understanding of how scour and deposition will occur in the canyon in response to flows much greater than the historical record. As such, reliance on model estimates of sediment transport based on the physics of flow is inadequate for assessing the effects of change and, at-best, provides only a range in the possible response to an extreme event. In this poster we examine available data on post-fire armoring rates, and observations about